Textbook of Biochemistry 9789350431528, 9789350243152

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TEXTBOOK OF BIOCHEMISTRY [FOR UNDERGRADUATE AND POSTGRADUATE MEDICAL STUDENTS] Dr. ANIL POTNIS Ex. Prof. & Head, Dept. of Biochemistry, Seth. G. S. Medical College & K.E.M. Hospital, Parel, Mumbai 400012, India. Ex. Prof. & Head, Dept. of Biochemistry & Research Centre, K.J. Somaiya Medical College, Ayurvihar, Sion, Mumbai 400022, India.

Dr. DEVAL RESHMA PARANJPE M.D. Board Certified, American Board of Ophthalmology, Diredor of Cornea, External Disease and Refradive Surgery Service. Department of Ophthalmology. Allegheny General Hospital, Pittsburgh, Pennsylvania, USA. Fellowship Training in Cornea, External Disease and Refradive Surgery, University of Minnesota Medical Center Department of Ophthalmology, USA. Residency in Ophthalmology, University of Pittsburgh Medical Center/Eye Institute, USA. t\D, Outstanding Category, Brown University Medical School Sc. B. Magna Cum Laude in Neuroscience, Brown University Providence, Rhode Island, USA.

Dr. ASHA POTNIS M.D., FMP. (Board Certified in Pediatrics) Attending at, Forbes Regional Hospital, Monroeville, po, Attending, Children's Hospital, Pittsburgh, po, USA.

Hal Gflimalaya GpublishingGflouse MUMBAI • DELHI • NAGPUR • BANGALORE • HYDERABAD -

.....

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AUTHORS No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording and/or otherwise without the prior written permission of the author and the publisher.

ISBN

: 978-93-5024-315-2

REVISED EDITION :2010

Published by

Branch Offices: Delhi

Nagpur

Bangalore:

Hyderabad:

Printed by

Mrs. Meena Pandey for HII).'ALAYA PUBLISHING HOUSE, "Ramdoot", Dr. Bhalerao Marg, Girgaon, Mumbai - 400 004. Phones: 23860170 & 23863863, Fax: 022-23877178 Email: [email protected] Website: www.himpub.com "Pooja Apartments", 4-B, Murari Lal Street, Ansari Road. Darya Ganj, New Delhi - 110 002. Phone: 23270392, Fax: 011-23256286 Kundanlal Chandak Industrial Estate, Ghat Road, Nagpur - 440 018. Phone: 2721216, Telefax: 0712-2721215 No. 16/1 (Old 1211), 1st Floor, Next to Hotel Highlands, Madhava Nagar, Race Course Road, Bangalore - 560 001. Phones: 22281541 & 22385461, Fax: 080-22286611 No. 2-2-1 167/2H, 1st Floor, Near Railway Bridge, Tilak Nagar, Main Road, Hyderabad - 500 044. Phone: 55501745, Fax: 040-27560041 Bhave Private Ltd., 242, Belasis Road, Nagpada, Mumbai - 400 008.

DEDICATED TO THE LOVING MEMORIES OF ()lJIt I?l\l'II]~It IJ1\TE ])u.. ".1).

1)()rrl~IS

AND () lJ It I\{ () rr II]~ It IJ1\TE l\1u.s. IC}\l\1}\IJ ".

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THIS BOOK IS PRESENTED AT THE INVOCATION OF DIVINE POWER FROM PARAMPUJJYA

SlIIt]~]~ _l\l~ IIt lJ])]) II]31\I'lJ .T ()S II I AND SIllt]~]~

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HAS BEEN BLESSED FOR THE BENEFIT AND ADVANTAGE OF STUDENTS

"This Page Is Intentionally Left Blank"

CONTENTS ( PART I J 3 - 18

1.

Hydrogen Ion Concentration [pH] Buffers Acid Base Balance

2.

Surface Tension

19 - 24

3.

Viscosity

25-26

4.

Colloids

27 - 28

5.

Nanomols

29 - 31

6.

Cell and Cell Membrane

32 -44

7.

Composition of Air and Hb-function

45 - 51

8.

Chemistry of Carbohydrates

52 -69

9.

Chem!stry of Proteins

70- 93 94 -111

10. - Chemistry of Lipids 11.

Chemistry of Nucleoproteins

112 - 129

12.

Enzymes

130 - 158

13.

Vitamins (Fat Soluble A. D. E. K)

159 - 201

14.

Hormones

202 - 213

15.

Mechanism of Hormonal Action

214 - 220

16.

Biological Oxidation

221 - 233

( PART II J 17.

Carbohydrate Metabolism

237 - 286

18.

Lipid Metabolism

287 - 325

19.

Protein Metabolism

326 - 361

20.

Intermediate Metabolism

362 - 371

21.

Starvation Metabolism

372 - 374

22.

Nucleo-protein Metabolism

375 - 384

23.

DNA (Deoxyribose Nucleic Acid)

385 - 387

24.

RNA [Ribose Nucleic Acid]

388 - 391

25.

Genetic and Protein Synthesis - I

392 - 398

26.

Genetic and Protein Synthesis - II

399 - 409

( PART III ) 27.

Cataract -I

413 - 417

28.

Cataract - II

418 - 434

29.

Anti-biotics

435 - 456

30.

Inorganic Metabolism

457 - 474

31.

Metabolism of Trace Elements

475 - 495

32.

Plasma Proteins

496 - 500

33.

Immunochemistry

501 - 509

34.

Hemoglobin Formation

510-516

35.

Hemoglobinopathis [Abnormal Hb]

517 - 520

( PART IV ) 36.

Nutrition in Health and Disease

523 - 538

37.

Prostaglandins

539 - 543

38.

Cerebro Spinal Fluid [C.S.F.]

544 - 546

39.

HepatiC or Hepatogenous Jaundice

547 - 549

40.

Specific Dynamic Action [So D. A.]

550 - 551

41.

Enegma of Essential Hypertension

552 - 572

42.

Metabolic Errors at Birth and in Life

573 - 580

43.

Urine Formation and Composition

581 - 594

44.

Pollution and its Hazzards

595 - 596

45.

Assessment of Chemical Constituents in Confirming Normal and Clinical Status for Differential Diagnosis

597 - 618

Chapter on Viva Voice

619 - 635

46.

References

636

PART I

"This Page Is Intentionally Left Blank"

HYDROGEN ION CONCENTRATION [pH] BUFFERSACID BASE BALANCE (A) HYDROGEN ION CONCENTRATION [pH] There are certain chemical substances which have the capacity to maintain Hydrogen ion cocnentrations of the medium when a moderate amount of acid or alkali is added to it. This substance or solution of this substances is called a Buffer. A buffer solution usually consits of a pair of substances. For example: A weakly dissociated Acid + the salt of the acid or a weak base of its salt. H2C03 + NaHC0 3 Buffer Pair

y NaHC03 + HCI

-~)

Buffer. When acid is added to this system

.J

Now HCI is a strong acid while H2C0 3 is a weak acid. HCI will raise hydrogen ion concentration as it is strong acid (completely dissociaed) where as H2C0 3 being a weak-acid, the production of H+ ion concentration is less. Hence there will be a less change (fluctuation) in pH. If NaOH is added to this system: H2 C0 3 + NaOH NaOH is strong base (completely dissociated - Na+ + OH-) and H2C0 3 is a weak acid reacts with NaOH to form comparatively a weak base. In this case also H+ ion concentration is not much changed. Common Ion Effect:

In many buffer systems, a common ion effect is observed. if a strong electrolyte is added to a weak electrolyte with an ion common to weak electrolyte, the weak electrolyte dissociates to a lesser degree and the concentration of the ion not in common is lowered. 3

TEXT BOOK OF BIOCHEMISTRY

4

If Sodium acetate is added to acetic acid the dissociation of the acid will become less and consequently these will be decreased of H+ ions. HAc

H+ + Ac-

NaAc

) Na+ + Ac-

The availability of the acetate ion from sodium acetate which is in common with the acetate ions from Acetic acid , thus, as there is an increase of Acetate ions on right side of equation the equilibrium will shift from right to left. On account of this more H+ ions will now combine with acetate ion with the formation of undissociaed acetic acid and the concentration of hydrogen ion is decreased. Bronsted Theory: A base is any molecule or ion which will react with H+ ion if it is readily, it is a strong base, if only slowly, it is a weak base. Henderson - Hasselbalch Equation:

If the composition of the buffer mixture and the dissociation constant of the weaker electrolyte is known, it is possible to calculate the pH values of buffer solutions. If pH and dissociaton constant are known the ratio of buffer pair can be calculated. For dissociation of acetic acid: [HAc] By the Law of Mass Action: KHAc =

Or

[W][Ac-] [HAc -]

[H+] =

KHAc[HAc] [Ac-]

=

KHAc[Acid] [Salt]

When there is a mixture of a weak acid and its salt such as acetic acid (HAc) and sodium acetate (NaAc) the dissociation of acid is very less. Therefore (HAc) may be taken as equal to total acid concentration. On the other hand salt is more or less completely dissociated and therefore [Ac-] may be taken as equal to that of total salt concentration. [W] =

KHAc[Acid] [Salt]

HYDROGEN ION CONCENTRATION [pH] BUFFERS -

ACID BASE BALANCE

5

Taking negative logarithim of both sides, the equation becomes: - log [H+]

~~:~1]

= -

log [KHAC x

= pH

and - log K

By definition - log [H] pH

=-

pK + [

= pK

-lOg [ACid]] [Salt]

[Salt] = - pK + log [Acid] This equation is known as Henderson-Hasselbach Equation. Definition of pH: It is the negative exponent of the potential of logarithm of Hydrogen ion concentration to the base 10 (- log10 H). p stands for potential. Example: pH 7.4, Buffer

NaHC03 H C0 2

3

= pK for H2C03 = 6.1 = pK

According to equation: Salt pH = pK + log Acid 7.4 = 6.1 + log

1.3

Antilog of 1.3

2

3

NaHC0 3 H CO

= log =

NaHC0 3 H C0

2

3

NaHC0 3 H C0 2

3

20 1 Thus if this ratio is maintained pH will be 7.4

6

TEXT BOOK OF BIOCHEMISTRY

Na2HP04 4 Buffer NaH2PO 4 - 1

(2) Blood pH 7.4, pK for NaH 2PO 4

= 6.8

Na2HP0 4

0.6 = log NaH PO

Antilog of 0.6

2

4

=4

:. NaH PO

Normal Blood pH

Na2HP04 2

4

= -1 4

at pH 7.4

= 7.35 to 7.45

pH of Arterial Blood

= 7.4

pH of Venous Blood

= 7.41

to 7.43 ( Difference 0.01 to 0.03).

(~) BUFFER SYSTEMS OF THE BLOOD

Buffers are present both in plasma and in Red Blood Corpuscles. (RBC)

o

Na+ Na

= Extracellular

Plasma

R.B.C.

K

= Strictly intracellular;

Na2HP04 NaH2P0 4

Na-Proteins

K 2HP04

KHb0 2

KH2P04

KHb0 2

However exists in both compartments

H Proteinuli r

KHb KHb

HYDROGEN ION CONCENTRATION [pH] BUFFERS -

ACID BASE BALANCE

Of the various buffer pairs metnioned above the most possible one is

7

NaHC0 3 H C0 or in 2

3

BHCO general form H CO 3 • This pair is useful to counteract non-volatile acid that may find its way 2

3

to blood . It is. taken that more than 50% of all acids which happen to be stronger than H2C03 are neutralized by bicarbonate. Lactic Acid [HL]: HL + NaHC03 -----+ ..

Na-Lactate + H2C03

.

Converted

[Non-Volatile and Stronger Acid]

[Volatile and Weaker acid]

Examples: -~)

H.Proteinuli + Na

HL + KHb02

-~)

H.Hb02 + KL

KOH + H.Hb

-~)

K Hb + HOH (Water)

HL + Na-Proteinuli

Explain: the buffering action of Hb.

{

In all these reactions strong non-volatile acids are converted into weaker or volatile acid.

Chloride Shift: Hambergers' Phenomenon: In the Capillaries of Tissues: Tissue cells, during metabolic acivity consumed oxygen and give out CO 2 , This CO 2 diffuses from Tissue Cells ~ Tissue fluid ~ Blood Plasma ~ R.B.C. C.A.

CO2 + H20

(

) H2C03

This is a enzymatic reaction. Meldrum & Roughton discovered this enzyme and called as carbonic anhydrase. This enzyme is a reversibe one

TEXT BOOK OF BIOCHEMISTRY

8

When the concentration of HC03" ions in R.B.C. is increased, they diffuse out in plasma where HC03 concentration is low. When HC03" ions from the cells diffuse out to plasma, a net negative charge has been transferred from cells to plasma. On account of this, electrostatic neutrality is disturbed. To restore this, either a possible charge has to go out to plasma from the cells or negative charge has to come from plasma to the cells. Actually it is observed that CI- ions from plasma move into the cells to restore electrostatic neutrality which was disturbed because of HC03- ions. As more and more CO2 is formed, it diffuses out from tissue cells to tissue fluid to plasma and then to R.B.C. C.A.

CO2 + H20

R.B.C.

(

Plasma

Equilibrium is shifted to right

As the above reactions are going on in the capillaries of tissues, another set of reaction is also proceeding simultaneously. Lung 02 Tension increased

Tissue 02 Tension is low

Oxyhemoglobin dissociates as K Hb02

) K Hb + 02

}

02 utilized by

H Hb02 -~ H Hb + 02 H2C0 3 + K Hb

-~)

Tissues.

K HC03 + H Hb

Carbonic acid is buffered by K Hb. K + HC03" [Diffuses out]

K HC03

K + CI ~ KCI

In the Capillaries of the Lungs: In the Lungs CO2 tension is less as compared to tissues. Hence: C.A.

CO2 + H20 Hence more CO2 is given off:

) H2C03 C.A. -~)

HC03 + H

On account of this HC03 ion concentrations in R.B.C. will decrease: R.B.C.

Plasma

Low HC03" concentration

High HC03" concentration.

HYDROGEN ION CONCENTRATION [pH] BUFFERS -

,ACID BASE BALANCE

9

HC03' ions move inside the cells. And CI- ions from R.B.C. will move out to maintain electrostatic neutrality. When HC03' ion from tissue cells diffuse out to plasma a net negative charge has been transferred from cells to plasma. On account of this, electro-static neutrality is disturbed. To restore this, either positive charge has to go out to plasma or negative charge has to come from plasma into the cells. Therefore CI- ions shift from plasma to cell, so that electrostatic neutrality is maintained. -~)

K Hb02

-~)

H Hb02 (Stronger Acid)

Oxy Hb is a stronger acid than reduced hemoglobin. K, Oxyhemoglobin (H Hb02) K reduced hemoglobin (H Hb)

=

2.4 x 10-7

=

6.6 x 1(J9

More K will be paired with oxyhemoglobin.

C.A.

Lungs

This change in strength of Hb acid (H Hb02 ) on one side on oxygenation as well as reverse on deoxygenation without any change in blood pH is called as "Isohydric Change." Plasma

Red Cell Wall

CO 2- - - - - -r-(from Tissues)

CO 2- - - - - -

H2C03

H2C03

Red Blood Cell

--

CO2 + H2 0

,.- ,.-

~ ~C03

,.,.- ,.-

,.-

rC03

H2C03 + K Hb - - + H Hb + K NaCI + HC03

~

NaHC03 + CI

HC03'+--+ +.

HC03

, CI

Cr+ K¥

~ KCI

/

.- .-

,

10

TEXT BOOK OF BIOCHEMISTRY

(C) ACID BASE BALANCE OF BLOOD As a result of metabolic activity, the elements present in our food, such as sulphur, phosphorus, carbon, may be converted into acids like sulphuric acid, phosphoric acid, carbonic acid etc. Also there are basic elements present in food such as Na, K, Ca, Mg. Lactic acid is produced as the end product of carbohydrate metabolism. ~-hydroxy butyric acid and aceto-acetic acid are produced as the result of oxidation of fatty acids. Normal pH of Blood (7.4): 7.35 -7.45. This is made possible and following mechanism by which this is made possible. Lines of Defence:

(1) Buffer System of Blood (2) Kidney Mechanism (3) Respiratory Mechanism

NaHC0 3 Of all the buffer pairs mentioned above the most important one is H CO - or in BHC0 3 2 3 general form H;C0 . All strong Acid (more than 50% are neutralised by NaHC03 . 3

Lactic Acid

Na-Lactate + H2C0 3

HL + NaHC0 3

Non-Volatile

Volatile and

and Stronger Acid

Weaker acid

Alkali Reserve:

CO 2 is carried in Blood in three ways: (1) Combined with Hb Hb NH2 + CO2

-~)

Hb NHCOOH Carbamino Hb

(2) Combines with Cations as Na or K (Bicarbonates) NaHC0 3 or KHC0 3 (3) Physical Solution 100 ml of Blood

40 mm Hg CO 2 Tension

37°C Temp.

2.7 ml CO2 is dissolved.

Total CO 2 of Blood: + CO 2 in PhYSical Solution = Alkali Reserve Alkali Reserve or Bicarbonate Level of Blood is defined as number of ml of CO2 in 100 ml of blood which is equilibrated with CO2 tension at 40 mm of Hg (Alveolar CO2 tenSion), the CO2 in Physical solution is deducted or substracted.

HYDROGEN ION CONCENTRATION [pH] BUFFERS -

ACID BASE BALANCE

Normal alkali reserve

50 to 70 ml of CO/100 ml.

Mild Acidosis

41 to 50 ml of CO/100 ml.

Moderate Acidosis

31 to 40 ml of CO/100 ml.

Severe Acidosis

30 or below 30 ml of CO/100 ml.

11

Determination:

Henderson's Hasselbach Equation:

= pK + log

Salt Acid pH

7.4 = 6.1 + log

NaHC03 H CO

7.4 - 6.1 = 1.3 = log

NaHC03 H CO

pH

2

2

= 7.4

NaHC03 H C0 2

3

3

3

Antilog of 1.3 = 20 20 = 1 If 20 :1 is ratio is maintained then only pH will be maintained at 7.4 . . / Excess NaHC03 L-.. Deficit

H2C03~

Excess Deficit

Total

= 8 Cases of compensated =9

/

Compensated

4 cases",~ Uncompensated and uncompensated + 1 Normal

Cases.

Only Alkali Reserve determination will not give correct idea of Acid base balance. It is necessary that pH of Blood should be determined. Example:

(1) CO2 Deficit NaHC03 H2 C03

-~)

Level Diminished, Hence Alkalosis Exists.

12

TEXT BOOK OF BIOCHEMISTRY

There may be excretion of NaHCOs via urine to compensate this with the result that Bicarbonate level of Blood will be low. [Normal Alkali Reserve = 50 - 70 ml of CO/100 ml of blood] Low level may be mistaken as Acidosis whereas it exists as alkolosis. That is the reason why alone alkali reserve will not give the correct picutre. (2) CO2 Excess

NaHC03

-;H7;;C:;;O~'-~) Hence body may try to retain NaHC03 2

3

Excess Subsequently bicarbonate level is increased. Therefore Alkali reserve is increased, hence it is mistaken as Alkalosis. Because of increased Alkali reserve value which will be actually Acidosis. Therefore pH of blood will indicate Acidosis. Alkali reserve value: Normal: 50 to 70 cc CO/100 ml. From the above discussion, pH 7.4 of the blood will be maintined provided the ratio of NaHCOs to H2C03 is maintained to 20 : 1. Only by determination of alkali reserve one cannot get an idea of acid base balance. Therefore pH is to be determined. Any change occurring in blood pH from 7.35 to 7.45 is compenstory phenomenon because body is capable of copensating any pH changes within this range of 7.35 to 7.45. By adjustment of excreting alkali or acid and by adjusting Lung function. If CO2 is accumulated, lung function is promoted and CO2 is expelled out. This will be refered to as compensatory mechanism employed by altering lung function which can drive away CO2 out of body and convert pH to 7.4 which was reduced to 7.35. A similar compensatory phenomenon occurs if there exists a!kolosis. However body can tolerate alkolosis and is capable of excreting Alkali in Urine. Following are some Condition and Body Compensatory Mechanisms: BHC03 I. Uncompensatory Alkali Excess H CO pH is 7.45 or more than 7.45. 2

3

This condition arises when there is a retention of akali or loss of HC!. A diminished Lung function to hold back CO2 or by increasing diuresis or by using oral administration of citrate.

HYDROGEN iON CONCENTRATION [pH] BUFFERS -ACIDBASEBALANCE

BHC03 II. Uncompensated CO2 deficit pC02 H CO

-1

2

13

pH is increased.

3

Hypernea (Voluntary or induced oxygen want at high attitude) or in High body temperature or after Hot water baths. Compensatory mechanism would be Diuresis of NaHC03 . III. Compensated Alkali or CO 2 excess: (C0 2 Retension or Alkali Retnesion)

Patient on NaHC03 therapy or Retarded Gaseous exchange or BHC03 retentsion. Results in Cyanosis (deficient oxygenation). Patient is kept on oxygen improves very fast. IV. Uncompensate CO2 or Alkali Decrease. Deficit

BHCOs

-H--CO 2

pH No Change (NC)

3

Alkali Deficit: Accelerated production or retarded elemination of non-volatile acids CO 2 deficit; Oxygen want at high altitude. Compensatory Mechanism: Increased Respiration. CO2 is driven off and oxygen is retained back (Hypernea).

V. Uncompensated CO2 Excess

BHC03

H2 COr (N.C.) 3

Retaerded Respiration in Cardiac Diseases (CCF) Dyspnea. Lung function and heart function is to be corrected. BHC0 3 .t VI. Uncompensated Alkali Deficit H -CO- (N.C.):. pH is decreased 2

3

Condition occurs in Nephrotic Acidosis or diabetic acidosis compensated. Insulin administration. Causes eclampsia Dyspnea. BHC03 Normal pH 7.4; H CO;2

=

NaHC03 H2C03

20 1

Other Applications: (1) Sub-oxidation Products: Example: Diabetic Condition : Fats burn in the flame of Carbohydrate.

So when carbohydrate metabolism is disturbed because of less insulin formation and action, fats are not oxidized competely. Aceto-acetic acid and p-hydroxy butyric acid are not oxidized further. These are non-volatile acids. Hence pH is decreased. These products are called as suboxidation product. (2) Activity of enzyme depends upon the pH of the medium. Acid reaction favour in stimulating carbohydrate splitting enzyme and proteolytic enzymes. This causes the hydrolysis of protein

14

TEXT BOOK OF BIOCHEMISTRY

(3) Absorption: Absorption of certain ions as Ca++ require acidic pH 5.4 . Ca-salts are soluble in acidic pH.

(4) Imbilation of fluid by body colloids depends on reaction of medium. A slight increase in acidity favours in imbibation, with the result the tissue may swell. (5) A change in pH produces a potential difference at two different surfaces. E

= 0.058 log10

1 [H+]

This gives rise to E.M.F. E.M.F. on the cut and uncut surfaces is measured. This is attributed to changes in pH. (6) Increase in Acidity stimulates respiratory centre. (7) Excitability of nerve and activity of muscle depends on pH of the medium. [Distilled water injection in intramuscular region is very painful because of pH change].

Kidney Mechanism: (I)

Tubular Filtrate

Prtoximal Tubule

C.A. Metabolic

CO2

Back Absorbs

NaHC03 --- pH 7.4

HYDROGEN ION CONCENTRATION [pH] BUFFERS -ACIDBASEBALANCE

15

Exchange of H with Na (from NaHC03 ) takes place until the level of NaHC03 is maintained. (II) Distal Tubule Cell

Na2 Hr "\

Metabolic CO 2

pH 7.4

,-t--___ _

Na+

" Na HPO ' ..

.

,"

,,

4 :

.'

f

l

I

.'

"

~,,---~j\ NaHC0 3 +---- HC03 + Na+ NaH2 P04

~

To Urine (III) Distal Tubule Cell NaCI

Glutamine Glutaminase

h

..

NH3

--~~

Glutamic Acid

r---- - +

--~ ! NH 3 + H CI1_ - - -

r---'

NH4 CI

Respiratory Mechanism:

When Acidity increases (H 2C03 more accumilation) Simulates Respiratory Centre Pulmonary Ventilation Increases More CO2 given off

pH 6.0

16

TEXT BOOK OF BIOCHEMISTRY

When Alkalinity of Blood Increases Depresses Respiratory Centre Pulmonary Ventilation is depressed CO2 is retained back into blood CO2 + H2C03

)

which compensate Alkalosis

QUESTIONS 1. How much energy is contained in a diet, if the average daily intake consists of 75g protein. 300g carbohydrate, & 100 g fat? (A) 1600 CBI (6700 kJ)

(B) 1900 CBI (7950 kJ)

(C) 2400 eBI (10,050 kJ)

(D) 2800 9BI (11,700 kJ)

2. Compensatory response for respiratory alkalosis involves (A) Decrease in bicarbonate levels

(B) Increase in bicarbonate levels

(C) Decrease in PC02

(D) All of the above

3. Most important buffer in the extracellular fluid is (A) Phosphate

(B) Protein

(C) Sodium lactate

4. Respiratory acidosis is seen in (A) Bronchopneumonia

(B) Diabetes Mellitus

(C) Pulmonary Oedema

(D) Salicylate POisoning

5. When the blood pH decreases due to disease, the kidney in order to compensate, excretes (A) More acidic urine and more NH;

(B) More basic urine and more NH;

(C) More basic urine and less NH;

(D) More uric acid

7. Acid base balance of the body is basically the metabolism of (A) H-ions

(B) Na+ i?ns

(C) K+ ions

(D) Ca+ ions

8. Buffering action of haemoglobin is mainly due to its (A) Glutamine residues

(B) Arginine residues

(C) Histidine residues

(D) Lysine residues

10. One of the following conditions observed in normal anion gap (A) Diabetic ketoacidosis

(B) Lactic acidosis

(C) Hyperchloroemic metabolic acidosls(O) Uroemic acidosis 11. Normal anion gap in plasma is about (A) 5 mEqlL

(B) 15 mEq/L

(C) 25 mEq/L

(D) 40 mEqlL

HYDROGEN ION CONCENTRATION [pH] BUFFERS -

ACID BASE BAlANCE

17

12. Following systems are of plasma buffer EXCEPT

(A) NaHCO/H 2 C03

(B) Na2H PO 4/ NaH 2

(C) Na organic acid / H organic acid

(0) K HC03 I H2 C03

13. At pH 7.4 the ratio bicarbonate dissolved CO2 is (A) 1:1

(B) 10:1

(C) 20:1

(0) 40:1

14. Following systems are of red blood cells buffer EXCEPT

(A) KHCO/H 2C03 (C) K organic acid/H organic acid

(B) ~HP04' KH 2 P04 (D) Na organic acid I H organic acid

15. Increased anion gap is observed in (A) Renal tubular acidosis (B) Metabolic acidosis due to diarrhoea (C) Metabolic acidosis due instestinal obstruction (0) Diabetic ketoacidosis 16. Metabolic acidosis occurs in ali EXCEPT (A) Increased synthesis of ketone bodies (B) Increased loss of HCO; in diarrhoea (C) Decreased H- excretion in renal failure (D) Hyperventilation in head injury 17. Metabolic alkalosis can occur in

(A) Severe diarrhoea

(B) Renal fai!ure

(C) Recurrent vomiting

(D) Excessive use of carbonic anhydrase inhibitors

18. Ketoacidosis without glycosuria is seen in (A) Prolonged starvation

(B) Aspirin poisoning

(C) Renal tubular acidosis

(D) Respiratory acidosis

19. Blood chemistry shows following features in uncompensated lactic acidosis EXCEPT (A) pC02 is normal

(B) pH is increased

(C) Bicarbonate is decreaseq

(D) Anion gap is normal

20. All the following changes occur in compensatory respiratory Alkalosis EXCEPT

(A) Decreased secretion of hydrogen ions in urine (8) Increased excretion of sodium in urine (C) Increased excretion of bicrbonate in urine (D) Increased excretion of ammonia in urine 21. One of the following changes is observed in blood chemistry in compensated respiratory acidosis

(A) lincreased PC02

(8) Increased bicarbonate

(C) Decreased chloride

(D) All of the above

TEXT BOOK OF BIOCHEMISTRY

18

22. The ketone which contributes maximally to diabetic ketoacidosis is (A) Pyruvate

(8) Acetone

(C) Acetoacetic acid

(D)

~-oxaloacetate

23. Anion gap is the difference in the plasma concentration of (A) Chloride - bicarbonate

(8) Sodium -

chloride

(C) (Sodium + potassium) and (chloride + Bicarboonate)

(D) Difference between number of cations and anions 24. All of the following changes in blood chemistry can occur in severe diarrhoea EXCEPT (A) Decrease pH

(8) Decreased bicarbonate

(C) Increase PC02

(D) Increased chloride

25. Plasma bicarbonate is decreased in (A) Compensated respiratory acidosis

(8) Compensated metabolic alkalosis

(C) Uncompensated metabolic alkalosis

(D) Compensated respiratory alkalosis

26. Following are the characteristics of hemoglobin buffer system (A) Oxygenated Hb is a stronger acid than de-oxygenated Hb (8) Acidity of the medium favours deoxygenation of Hb02 (C) Alkalinity of the medium favours oxygenation of Hb (D) All of the above

CHlQ

SURFACE TENSION 1. The phenomenon of surface tension:

Molecules at the surface of liquid are unequally attracted while molecules inside the liquid are attracted equally in all directions. Considering molecular theory of matter, the molecules attract each other. Consider molecule @ & @ very close to each other. They are attracted by other molecules in all four direction. Whereas molecules at the surface above, below and on sides of the liquid like are attracted by other molecules on sides and below. As there are no molecules above there will be no attraction forces above. As a result of this unequal forces of attraction, the molecues at the surface of the liquid will be pulled towards the interior of the liquid. This pull or tension is called as Surface Tension or in proper words the molecules at the surface of liquid are unequally attracted and they are subjected to a series of forces, the resultant of which acts at right angles to the surface with the result the molecules are drawn towards the interior of the liquid. It is the surface tenSion, which reduces the surface as small as possible with the result drops and bubbles of liquid assume a spherical form. The phenomenon of capillary is due to surface tension at top of liquid.

©' ©,

2. Definition: The surface tension is defined as the force in dynes which acts at right angles to the surface of a liquid along the line of one centrimeter length on the surface." It is usually represented by the Greek letter y. 19

2 0 T E X T BOOK -OF BIOCHEMISTRY

Units of Surface Tension

: dynes/cm.

Molecular Surface Energy

: Molecular volume x surface tension

(Vol. of one gm. molecule)

= V2i3 y. =yV213 (3) Factors affecting the Surface Tension:

1. Terriperature: As temerature rises surface tension of liquid decreases. 2. Dissolved substances: Various substances that are dissoved in the liquid have different effect on the surface tension: Inoraganic Salts: Little effect on water -

slight rises of S.T.

Sugar and Amino Acids: No effect on S.T. of water. Other Oranlc Substances: Such as soaps, alcohols, acids, esters and bile salts decreases the surface tension of water to a considerable extent when they are dissoled in it..

3.

Electri~1

Charge: Positive charges produced at the surface - decreases the surface

tension. Gibbs Thomson's Principle: Those substances which lower the surface tension of the solvents in which they are dissolved become concentrated in the surface layer and those substances which increase the surface tension, are less concentrated in the surface area than in the bulk of the soltuion. e.g. Inorganic salts raise surface tension. Organic compounds like aldehydes, ketonse, esters, lower surface tension of water. METHOD OF DETERMINING SURFACE TENSION: Stalgmometer or Drop Method: When a liquid flows from a tube at a very slow rate, a drop is formed which increases in size upto a certain pOint and then falls. Taking r as radius of the end of the tube, the total surface tension will be the surface tension per cm multiplied by circumference of the tube. So 2

7t

r

Force which supports this drops = 2

7t

r y (y = S.T.)

= W (Weight of the drops) = VD (Where V = Volume

o = Sp. Gr. Of the Liquid)

SURFACE TENSION

21

It is easier to find out the number of crops than to find out actual weight of drop. If the same tube is used the relative surface tension can be determined. 2

1t

r Y1 N1 = W = VD 1

-~)

Liquid I (H20)

2

1t

r Y2 N2

= W = VD2

-~)

Liquid II

[N 1 = Drops of Liquid I

01

= Density of Liquid I

N1 Y2 N2 Y1

Hence

N2 = Drops of Liquid II

=

O2 = Density of Liquid II]

~ O2

Y1 NP2 = Y2 N2D1

NP2 Y2 = NO 2

XY1

1

But Y (Surface Tension) is directly proportional to sp. Gravity but Inversely proportional to drops of liquids. 1

2

Stalgmometer Applications of Surface Tension: (1 ) .) · Iycen'd e (T'b n utynn T ng

!

(Surface Active)

Normal Serum . ) Lipase + Use Sodium Phosphate

Glycerol + Fatty Acids Na

t

(Surface Inactive)

Addition of Tributyrin to Serum increases surface tension and triglyceride is borken into Glycerol + Fatty Acid - Na . But instead of Normal Serum, if pathological sample - say pulmonary pthisis (Tuberculosis) is added, increase of surface tension is much less as compared to Normal Serum as amount of lipase is comparitively less in normal serum. (2) Embolus Formation: Blood contains many surface lowering substances. If an air bubble is introduced in artery a liquid interface is formed. According to Gibbs-Thomson's Theroy, substances which lower the surface tension of blood, tends to be concentrated at

TEXT BOOK OF BIOCHEMISTRY

22

this interface. If this happens, such substances form a tough membrane around the bubble. This is one of the ways by which an embolus is formed. If this reaches to pulmonary artery or Heart, the person dies. (3) Emulsification of Fats: (Helps in Digestion): Bile salts lower the surface tension. Thus fats are broken down into smaller particles (Emulsification - breaking down one phases into another phase when two phases of different surface tension are brought together) thus exposing larger surface area to enzyme action. (4) Heps in Absorption: It has been observed that lowering of the surface tension of a cell membrane increases the permeability of cell-membrane. This helps in the process of absorption. Substances, lowering S.T. will increase the permeability of intersticial cell membrane. (5) Mathews Hay's Sulphur Flower Test: Helps in Detection of Jaundice. Bile salts (Na-taurocholate & Na-glyco-cholate) lower the surface tension, this causes the sinking of sulphur flowers i.e. sinking shows the test is positive for Jaundice. (6) In the field of public health, this property of surface tension is utilized in the destruction of mosquitos larvae. Stagnant water pools are the sites of breeding for these malaria carriers. Normally these larvae remains suspended by their breathing tubes on the surface of the stagnant water pools. Oil lowers the surface tension of water and thereby the larvae sinks and are thus destructed. (7) In the field of Hygiene: Toothpaste, nasal jellies and mouth washes contains substances which lower S.T. i.e. can be spread all over evenly thus increasing the cleansing effect and antiseptic action of the preparation. (8) Action of Soap: The soap acts as a cleaning agent because it lowers the surface tension between water and greasy substances and thereby water surrounds such substances and washes them away. (9) Muscle contraction: Muscle fibre is considered to be made up of elongated particle arranged as:




Before Contraction

Due to metabolic activity certain substances may be formed which may increase the S.T. and the particles may assume a globular shape thereby shortening and thickening the fibre.

(XXX) After Contraction

(10) Anaesthetic power: It depends on the lowering the surface tension, the more quickly a substances lower the S.T., the greater is its anaesthetic power.

23

SURFACE TENSION

(11) Concept of cell division is based on this Hypothesis: Butschli (1876) stated that if a drop of oil, suspended in aqueous solution would break into two drops if a high surface tension is produced at the equatorial region of the drop. Maclendon Supported this hypothesis:

NaOH Sol.

NaCI Solution Sp. Gravity Adjusted to

----_f_

-+-----i~NaOH

Sol.

-::r---+-.... Racid

Oil Drop

Butschli's View: S.T. may be taking part at the time of Cell Division

A chloroform rancid oil droplet was taken and was put in a solution of NaG!. Sp. Gravity of NaGI is so adjusted that the oil droplet remained suspended in the liquid. Then a dilute solution of NaOH was added with the help of two pipettes at opposite poles of the droplet. The oil in droplet was rancid so the alkali coming in the contact with the oil formed soap which decreased the surface tension of the drop at polar region. This caused the drop to elongate and finally to break into two. (12) Lowering of surface tension at a particular surface may cause adsorption of a sustance at the surface. Adsorption capacity of the adsorbent depends upon surface free energy of holding another molecule by free energy. (13) Molecular Orientation: It is a tendency of certain molecules to arrange themselves in a definite pattern

24

TEXT BOOK OF BIOCHEMISTRY

Symmetrical Molecules

Asymmetrical Molecules

Water

CH3COOH

Acetic Acid

Benzene

C2HSOH

Ethyl Alcohol

C6HsNH2

Aniline

Can be divided into two Halves

Cannot be divided into two halves (Equal)

Unsymmetrical Molecules have COOH, OH, NH2 ...... etc groups. These are called water attracting groups or polar groups.

-d.- _..1._.. =:0- -::IT:::

._-- ........

Non-Polar Group

Water

----.,

--+Oil

~-------.:~~ Ploar group

The polar groups of molecules arranged themselves in such a way that they are directed towards water while N02 - polar grous arrange themselves away from H20. This is called as Molecular orientation. Ex.: When there is an oil-water interface polar groups will be attraced towards water and non polar will try to remain at the surface.

aaa

Viscosity

Viscosity depends on the resistance offered by the contents of fluids to flow easily by the liquid against the inner wall of the container under the normal atmospheric pressure and temperature therefore Viscosity depends upon fluidity Viscosity

=

1 Fluidity

Factors affecting the Viscosity of a liquid in General 1. Temperature: As the temperature rises the viscosity of liquid decreases. Fluidity increases. Viscosity falls by ·2% with the rise of temperature by 1°C. 2. As the molecular weight increases the Viscosity increases. A thickness depends upon its straight chain Hydrocarbons contents as it increases in size fluid become more viscous. 3. Presence of OH ion: As the number increases in OH contents, liquid becomes more viscous. 4. Addition of cane sugar to water increases Viscosity property. q. The presence of suspended matter increases the Viscosity Of Blood, increase of RBC count and WBC count increase the viscosity. Similarly with decrease of blood cell count viscosity decreases. 6. Water at body Temperature 37°C has a viscosity 0.03 Poise. It is convenient to express the viscosity of Biological fluid in relation with water which is termed as Relative Viscosity. 7. Dissolved gases increases the blood viscosity. Similarly after the absorption, Chile becomes more viscous.

25

26

TEXT BOOK OF BIOCHEMISTRY

8. Increase of plasma due large intake of water affect Blood Viscosity. Blood is diluted and large amount of water is excreted out in urine. Therefore water excretion and water retention has a profound effect on body metabolism. 9. In atherogeness, the flow of Blood is affected due to platelet aggregation and sclerotic affection, which also narrows blood flow and offers greater resistance with the result systolic pressure increases. This is the pathology involved, which is the irreversible change. 10. Increase of cell count (Both RBC) Polycythemia or WBC (leukemia) increase blood viscosity. Leucopenia, agranulocytosis, peneceus anemia, decrease of RBC count decreases blood Viscosity. 11. Presence of Triglyceride (Fat) molecules increases Blood Viscosity.

QQQ

Colloids

A solid which dissolves completely in a solvent like water is called as Solution It can be dissolved up to a certain stage. Beyond this stage it can not be further dissolved. This stage is called as supper saturated stage. This is solution when a solid is dissolved completely and is called as Solution. When the solid is suspended in solvent, it is referred to as Suspensoid, the Whole solution is referred to Suspension. Solid phase is suspended in the solvent phase. Distinctions between a True Solution and False solution. When a solid is completed dissolved in a solvent and does not come out of the solution on its super saturation is known to be dissolved completely and thus remains in solution on standing at room temperature and atmospheric pressure, is said to form a true solution. A true solution has a molecular size less than one millimicron 0.1

m~.

The molecular size of colloidal solution is more than 0.1 m~ at room temp. It depends on the nature of substance that is whether it imbibes water and swells up. Such a substance can be separated by the dialysis by the use of a semi permeable membrane and has been utilized in kidney dialysis or in peritoneal dialysis. m~

Suspenso ids

Particle size greater than 0.1

Solution

Particle size ranging less than 0.1

Colloid

Between 0.1 ~ -1 ~

m~

« 0.1

m~)

Suspensoids form opaque solution while colloid forms Translucent solution, and true solution forms Transparent solution. When one phase is suspended or dispersed in the other phase. It is referred to Suspension Particle size is more than 0.1 (micron) Suspensoid terminology is applied to inorganic compounds while Emulsoid is applicable to organic substances such as starch, protein etc.

27

TEXT BOOK OF BIOCHEMISTRY

28

Hydrophobic (water hating) and Hydrophlilic (watE)r loving) The hydrophobic term is used when one phase is immiscible with other phase and 'remain aloof. For example metal particles or stones do not involve themselves even they come \in contact with water phase when on phase shows a tendency of goin~into the solution by ~mbibing water and forming a solution, is said to be Hydrophillic in nat~e or the solid is supposed to get dissolved. \

Emulsoid at room temperature or at high'~r temperature remains in solution form but when allowed ' to cool down, sets into gel formulation. Gel to Sol conversion is based on temperature setting. This procedur~ is used for the separation of colloid from crystalloid. Dialysis: This is a process by which crystalloid could be able to separate from colloid. A mixture of starch and salt (NaCI) is to be separated out. Then this mixture is kept in a dialyser. This dialyser contains a compartment, which is placed in water tank. The membrane is called parchment paper or semi permeable membrane and allows only crystalloid to pass through, till the concentration of salt inside and outside the membrane becomes equal. This process of separating crystalloid from colloid is made use when the urea concentration and creatinine concentration is increased due to renal shut down. So the kidney dialysis becomes essential. Osmotic Dialysis: This is the mechanism when semi permeable membrane permits the flow of the solvent from lower concentration to higher concentration when two solutions of different concentration are separated. The example of salt crystal is put in water it dissolves because of osmotic pressure.

QQQ

NANOMOLS

1 mill mol [mM] = 0.001 M = 1 Formula weight in milligram 1 micromole [J..lM ] = 0.001 mM

= 1 Formula weight in

microgram

1 microgram [J..lg] = 0.001 mg = Weight in microgram [

10~0]

(1 )The relationship of Hydrogen ion and pH is not direct, nor linear, nor arithmatical. But it is inverse, curvi-linear of Logarithmic. Example: As H ion concentration increases, pH value decreases

H ion concentration decreases, pH value increases (Solution becomes relatively alkaline) For Every decrease in 0.3 pH (H+) is doubled Every increase of 1.0 pH (H+) falls 1/10th of former value. (2) Concentrations of various constituents in body fluids are expressed as gm.mol or gm.ion or milli Equivalent [ mE]. Example: K = 0.0042 = 4.2 x 10-3 milli Eq'/Litre

The concentration of all the other electrolytes in the body fluids are expressed in terms which are related to the number of their chemical equivalents or of their gram moles (or gram ions) and there would not be any logical reason for expressing of H+ in concentration in the same way. The use of the term "milli equivalent" or mill mol (mM), allows the small concentration (mEq/litre) of these other electrolytes in the body fluids to be more easily expressed and comprehended than what "Moles" or "Equivalents" are used. It is suitable for example to say that the concentration of potassium in a given solution is 4.2 meq/litre than to say it is 0.0042 Eq/litre. The concentration for H+ ion in most of the body fluids is much smaller than the concentration of the other electrolytes and a still a smaller unit than mill mol is necessary to express them. .29

30

TEXT BOOK OF BIOCHEMISTRY

A neutral pH 7 - H+ ion Concentration is 1 x 10-7 This can be written as 100 x 10-9 M (10+2 x 1Q-9) Hence 1 x 10-9 is a unit and called as Nanomol. This 1 micro of a mill mol pH

nMILi

8.8 7.1 7.4 7 .7

100 80 40 20

With every 0.3 rise in pH the value of nanomol falls to Y2 and every 0.3 pH decrease, the value is doubled. 10,000 J

6,000 mMl4.7

Curvilinear Curve

2,000

400 pH

pH Distilled Water

Urine - Maxi. Alkalinity

7 .0 7.4 (7.36 - 7.44) 6.8 7.8 7.36 - 7.44 1.00 6.00 4.5 8.0

Intra-cellular fluid - Muscle

6.8

Blood - Normal Blood - Very Severe Acidosis BloodVery Servere Alkalosis C.S.F. Normal Pure Gastric Juice Urine - Normal Average Urine - Maxi. Acidity

H+ ion Concentration nMlLit.

100 40 (44 - 36) 160 160 44 - 3F 1,00,000,000 1000 31,600 10 160

NANOMOLS

31

Determined indirectly by the distribution of 5-5 Dimethyl-2-4 -oxazolidine Dimer (Wandeth & Butte's, 1959). (3) Conversion of pH into Nanomol: Equation

nM/Litre 109 -

e.g.

pH of blood (found by pH meter)

[H+]

109 -

7.36

10

pH

= 7.36

1.64

Antilog of 1.64 is 43.4 i.e. 44 nM Within the limits of pH 7.28 and 7.45 Each 0.01 decrease in pH below the Normal (7.4) means increase of 1 nm/Litre. Where in Each 0.01 increase in pH above 7.4 means decrease in [W] is about 1 nM/Litre. Thus pH 7.4 means

H+ 40.0 nM/Litre

pH 7.28 means

H+ 52.5 nM/Litre

pH 7.46 means

H+ 34.0 nM/Litre

Beyond these limits the logarithmic character of the pH : H+ relationship causes H+ concentration, calculated in this simple way to deviate by more than 1.0 nm/Litre from true value. QQQ

CELL AND CELL MEMBRANE

Diagrammatic View of the Cell

RIBOSOMES

EN[)OPLASMIC RETCULUM

LEUS LYSOSOL NUCLEOLUS

GOLGI COMPLEX

--"'-MITOCHONDRION

CENTRIOLES

Prokaryote: A bacterium, unicellular organism, a single chromosome with no nuclear envelope and no membrane bounded organelles. Example: Yeasts.

32

CELL AND CELL MEMBRANE

33

Prokaryote is a Greek word. Pro meaning before and karyon meaning nucleus. This includes bacteria. Under this heading, Escherichia coli has been studied very widely. Eukaryotic: Under this heading either unicellular or multicultural organism are studied. Each cell has a cell membrane and the nucleus is having a distinguished nuclear membrane nucleolus. Eu means True and Karyon - Nucleus. These include multiple chromosomes and internal organelles.

Examples: Animals and Human beings. Prokaryotes: The chief characteristics of Prokaryotes are, smaller size (1 - 10 pm) with no internal organization and do not possess any genetic material having no nucleus and no nuclear membrane. It has no DNA with Histones (Absent). Reproduction does not involve mitosis or meiosis. Cell division is by fission (Budding yeast). Whereas Eukaryotes has a considerable degree of organization of internal structure with specific functions. Nucleus is well organized with specific functions. Reproduction involves mitosis and meiosis. Respiration occurs through mitochondria. Size of this Eukaryotic is 10 to 100 pm or more. These are aerobic in function and with multicellular in function with well defined in function of DNA surrounded by perinuclear membrane. Nucleolus is present with ribosome studded in outer surface of endoplasmic reticulum. Mitochondria serves as power house. While functions of Golgi apparatus Iysosomes, RNA synthesis, and Protein synthesis are seen in cytoplasm. Cell Membrane: Electron Microscopy has revealed the structure of cell membrane or plasma membrane. It is rigid and organized structure of an average thickness of 7sA and consists of a bilayer primarily of phospholipid and penetrated by protein molecules forming a mosaic like pattern. Hydrophobic end - fatty acid tail are oriented towards the centre of bilayer while hydrophilic ends (polar Head) point outwards. The membrane phospholipids act like a solvent for membrane proteins. In other words, the presence of phospholipid makes the protein amphipathic. These proteins have hydrophilic regions protruding inside and outside the membrane but connected by hydrophobic core of the bilayer. This is usually important for an ideal environment for maintaining protein function. Membrane protein are usually Glycoproteins. Membrane protein traverse hydrophilic core of lipid bilayer are called Integral proteins and those, which are closer to outside and are weakly bound to phospholipids are called Peripheral Proteins.

34

TEXT BOOK OF BIOCHEMISTRY

Examples of Integral Protein: • Rhodopsin of the retinal cells. • Immunoglobulin of the Leucocytes. • Hormone receptor protein -of various cell membrane.

Examples of Peripheral Protein: • Ankyrin of the Erythrocytes. • Several secretary protein. • Peptide hormones. • Mitochondrial ATP Synthetase. • Transmembrane Integral proteins acting as ion channels. [The band III protein of erythrocytes binds the integral, protein ankyrin with another protein spectrum and stabilizes the concave shape of these cells]. Enzymes present on cell membrane are Adenyl cyclase, ATPase, phospholipase etc. The membrane has small pore approximates 8 A wide which are more permeable to water and hydrated K+ than Na+ concerned with selective permeability and active transport of ion and molecules.

Aqueous phase Polar---l Heads -Outer Leaflet Non Polar Inner Leaflet Polar ___( Heads

Aqueous phase

LIPID BILAYER

CELL AND CELL MEMBRANE

Oligosaccharide Chains

¥~

Polar Heads


159

< 250

250 - 500

> 500

High Risk mg /100 ml

LIPID DISORDERS

Type I

Deficiency Lipoprotein Lipase. Triglycerides Xanthomas. Recurrent abdominal pain.

i

~

Type II

Family Orientation Defect High Cholesterol values Lipoprotein i LDL-Cholesterol

i

(Contd.)

LIPID METABOLISM

313

Type III: Inherited Diseaase ~-Lipoprotein i LDL i VLDL ! Known as Metabolic Defect i Apo E , Apo B. Cardiac Disorders or Atherosclerosis. Type IV: Familial Hyper Triglyceridemia characterised by hyper VLDL, i Triglycerides, i Cholesterol, Maturity onset of Diabetes Mellitus, Obesity, Chronic alcoholism. Type V

Hyperlipidemias (Inhereditary), Chylomicrons and VLDL, Hyper Triglycerides, Hyper Cholesterolamia.

METABOLISM AND MOBILISATION OF FAT IN ADIPOSE TISSUE Carbohydrate Utilisation Carbohydrate which are utilised by to acetyl Co. A enter into a TCA cycle and are oxidized to C02 and water. One of the pathway of Acetlyl CoA utilysation is the synthesis of Acyl-Co-A. So either fatty acid is synthesized or fat molecule is synthesized in the adipose tissue in the deficiency stage of insulin action, the fat molecule is broken down by the action of lipoprotein Lipase In adipose tissue and is utilized by way of free fatty acid Catabolism thereby provides energy to the body. Hormone sensitive Lypoprotein Lipase becomes active in the absence of insulin action and acts on trigly cerides to liberate free fatty acid which have a very short life and provide energy. The utilization of FFA for the sythesis of fat (anabolic effect) is under the action of insulin depending upon the number of acetyl CoA, molecules. Therefore both the carbohydrate and fat metabolism are linked together and are dependent on each other. The risk in FFA utilization in large amount precipitates In a problem with organal physiological function. (Impotency) Glucose

~

Glucose 6.p

+

Acetyl CoA.

tI ~ . ~

Glucose 6-p

Glycerol-3-PO4

t

i HMP Shunt (+C0 ) ~

Acyl CoA

2

Malonyl CoA + NADPH

.~

Fat Tri aJYI Glycerol Synthesis

B-Oxidation - - - - - - AJYI CoA -Fatty Acid synthesis Adipose Tissue Synthesis

This cycle is reverted back when glucose utilization is slowed down or in the absence of insulin effective action is incomplete. With the result Fat In adipose tissue is broken down by Lipo-protein Lipase. It acts on Triglycerides in adipose Tissue with the result Triglyceride is broken down.

314

TEXT BOOK OF BIOCHEMISTRY

Fat

Lipoprotein

(Tg)

Lipase

FFA + Diglycerides Lipase

1

CD

(Hormone Sensitive Lipase)

FFA + Mono

®

~

Lipo-proteion Lipase

FFA + Glycerol

@ FFA is utilized further for energy. (Inadequate Insulin Action)

PLASMA LIPOPROTEIN These are molecular complexes of Lipids and Proteins. The protein part is known as Apoprotein. These particles are in continuous process of forming, degradation and are removed from plasma to the tissue. The Lipid part constitute such as phospholipids, triglycerides and cholesterol which are sparingly soluble in water or at plasma pH. Therefore they are carried in plasma with combination of proteins. The proteins are known as Apoproteins. Lipids in combination with protein could be transported. The Lipid fractions which are carried, are obtained from diet or by synthesis. The composition of these lipid fraction is the basis of classification of Lipoproteins. Chylomicrons: These are particles having a lowest density and larger molecular size. Different lipids constitute a major portion. Proteins have small portion. Very Low Density Lipoproteins [VLDL] and Low Density Lipoproteins [ LDL] They are more dense and are having a higher content of protein and lower of lipid. High Density Lipoproteins [HDL]: They are more dense as compared to LDL and VLDL Main Transport Intestine --+. Liver -----.Adlpose Tissue Chylomicron.

Liver

•

Muscle and Adipose Tissue

VLDL,LDL HDL-fractlon

After the absorption Lipid fraction proceed to Liver. From the Liver they are transported to muscle and Adipose tissue. Fraction which are transported are Chylomicrons, VLDL, LDL.

315

LIPID METABOLISM

SEPARATION OF PLASMA LIPOPROTEINS BY ELECTROPHORESIS

DENSITY

1

ORIGIIN

0.96

CHYLOMICRONS (CM)

(LOL) 1.006 - 1.063

~-LlPOPROTEINS

01.006 (VLOL)

PRE-~-LlPROPROTEINS

(LOL) (VLOL)

................................... .... - ......................... ............._... ................. ............................. . . . . . . . . . . . . . . ~.~. 2 mo and adults (Immune-competent)

H. Influenzae(Uncommon), Strept pneumoniae, gmnegative rods, N. Meningitidis

3rd generation Cephalosporins and Vancomycin, Dexamethasone

Vancomycin and Chloramphenicol, Dexamethasone

Meningitis Adults > 60 yrs. (Immuno suppressed)

S. Pneumoniae, gmnegative rods, N. Meningitidis, Listeria

3rd generation Cephalosporins and Vancomycin, Dexamethasone

Vancomycin and Trimethopriml Sulphamethoxasole

Meningitis associated with head trauma or postneurosurgery

Staph Aureus, S. Pneumoniae, Staph Epidermidis, gm-negative rods

3rd generation Cephalosporins and Vancomycin

Vancomycin and Gentamicin

Brain Abscess

S. Pneumoniae, Streptococci,3rd generation gm-negative rods, mixed Cephalosporins and anaerobes Metronidazole

Brain abscess associated S. Pneumoniae, Staph with trauma or post-operative Aureus, gm-negative rods

3rd generation Cephalosporins and Vancomycin

Vancomycin, Metronidazole and Gentamicin

Vancomycin and Gentamicin

Disoder

Possible Organism

Antibiotic of choice

Alternative regimen

Gastroenteritis (Traveler'S)

Shigella, Salmonella, Campylobacter, Toxigenic E. Coli

Fluroquinolone

Trimethopriml Sulphamethosaxole

Gastroenteritis (US)

Shigella, Salmonella, Campylobacter, E. Coli, Claustridium Difficile

Fluroquinolone or Metronidazole

Trimethopriml Sulphamethosaxole,

440

TEXT BOOK OF BIOCHEMISTRY

Disorder

Possible organisms

Antibiotics of choice

Alternative regimen

Typhoid fever

Salmonella

Fluroquinolone or Ceftriaxone

Ampicillin. Amoxicillin. Chloramphenicol. Trimethopriml Sulphamethosaxole

Necrotizing enterocolitis

Staph Aureus. Staph Epidermidis. Aerobic gmnegative rods. Claustridium perfringens

Vancomycin and gentamicin and Metronidazole

Vancomycin and 3rd genration Cephalosporins and Clindamycin

Cholecystitis

E. Coli. other gm-negative rods. Strep faecalis. anaerobes

Gentamicin and Ampicillin

3rd generation Cephalosporins and Metranidazole

Peritonitis, Ruptured viscus

Bacillus fragilis, other Ampicillin. Clindamycin, Imipenem or Meropenem Gentamicin anaerobes. E. Coli, other gm-negative rods. S. faecalis Gm-negative rods, Ampicillin and Gentamicin Vancomycin and Gentamicin S. Pneumoniae. S. faecalis. anaerobes(uncommon)

Peritonitis, Spontaneous

Perirectal abscess (Leukemic or Neutropenic)

B. fragilis, other anaerobes. Piperacillin-Tazobactam E.Coli, Pseudomonas, other and Tobramycin gm-negative rods. S.faecalis

Imipenum or Meropenum and Tobramycin

Disoder Cystitis. Outpatient-acquired

Possible Organism E. Coli, other gm-negative rods, Enterococcus. Chlamydia

Alternative regimen Cephalexin. nitrofurantoin or Fosfomycin

Cystitis. Nosocomial. not septic

Antobiotic resitant gmFluroquinolones negative rods, Enterococcus

Oral 3rd generation cephalosporins

Pyelonephritis. First episodeoutpatient

E.Coli. other aerobic gm-negative rods. Enterococcus

Fluroquinolones

TrimethoprimlSulphamethsaxole

Pyelonephritis, recurrenthospitalized

E. Coli, Proteus. Klebsiella. other aerobic gm-negative rods

3rd generation Cephalosporins and Gentamicin

Imipenum or Meropenum or PiperacillinITazobactam

Disorder

Possible Organism

Antibiotic of choice

Alternative regimen

Pharyngitis

Grp A and C Streptococci, C. Diptheriae,

Penicillin V oral or Benzathine penicillin

Erythromycin. Azithromycin. Clarythromycin or oral cephalosporin

Epiglotitis

H. influenzae(Uncommon), Grp A Streptococci. Staph pneumoniae

Third generation cephalosporins

Ampicillin sublactam,

Otitis

H. influenzae, S. pneumoniae, Grp A streptOCOCCi, M.Ctarrhalis

Amoxicillin or Augmentin

TMP-SMX or Erythromycin. sulfamethoxazole or Azithromycin or Clarythromycin or oral cephalosporin

Antibiotic of choice Trimethopriml Sulphamethosaxole or Fluroquinolone

441

ANTIBIOTICS

Disorder

Possible organisms

Antibiotics of choice

Alternative regimen

Sinusitis

S.pneumoniae, Grp A streptococci, S.Aureus

Amoxicillin or Augmentin

TMP-SMX or Clarythromycin or Cefuroxime

Bronchitis -Young Adults

Mycoplasma pneumoniae, None or Erythromycin Viruses, Chlamydia pneumoniae, Bord. Pertussis

Aspiration pneumonia or Lung abscess- outpatient

Mixed oropharyngeal flora, Anaerobes

Clindamycin

Penicillin-G

Adult pneumonia, community acquired -hospitalized

S.pneumoniae, Clebsiella pneumoniae, M.pneumoniae, S.Aureus, Chlamydia pneumoniae, H. influenzae, Legionella, Viruses

TGC (Add vancomycin if severely ill) and Azithromycin or Clarithromycin or Fleuroquinolone

Vancomycin and Azithromycin or Clarythromycin or Fleuroquinolone

Community acquired Outpatient treatment

S.pneumoniae, Klebsiella pneumoniae, Mycoplasma pneumoniae, S.Aureus, H.lnfluenzae, Legionella, Viruses S.Aureus, Antibiotc resistant gram-neg rods

Azithromycin or Clarithromycin or Fleuroquinolone

Doxycycline

Viruses, Grp B Streptococcus, GNR, S.Aureus, Listeria, C.Trachomatis

Ampicillin and Gentamicin

Hospital acquiredinhospital treatment

Neonatal < 1 mo

2-14 weeks ( Afebrile patient- C. Trachomatis nonbacterial pneumonia)

Piperacillin-tazobactam Imipenum or Meropenum(add vancomycin if not responsive), (add v~ncomycin if penicillin resistance staph and Gentamicin aureus) and Gentamicin

Erythromycin

Clarythromycin or Azithromycin

Clarythromycin or Azithromycin (add nafcillin if S.Aureus or vancomycin if not responsive)

1- 3 mo

Viruses, C.Trachomatis, Bord.Purtussis, S.Aureus, S.pneumoniae(uncommon), H.influenzae

Erythromycin

3mo - 4 years

RSV, Influenza virus, other viruses, S.pneumoniae, H.influenzae B

Amoxicillin or Cefuroxime, TGC cefaclor, cefprozil

more than 4 years

S.pneumoniae, C.pneumonia, Erythromycin M.pneumoniae Pseudomonas aero B. Nafcillin for S.aureus, Tobramycifl and cepecia, S.Aureus, Stenotrophomonas ceftazidime for P.aeruginosa and others

Cystic fibrosis

Azithromycin or Clarythromycin Piperacillin and Tobramycin

When you have a definite organism or multiple organisms in culture an~ sensitivity it is easy to institute treatment by above table of microbial sensitivity of each antibiotic. Antibiotic prophylaxis in surgical and medical areas:

442

TEXT BOOK OF BIOCHEMISTRY

Surgical Applications: 1. Cardiac surgery and procedures like cardiac catheterization 2. GI surgery and procedures 3. CNS surgery and ENT surgery 4. Bones and joints surgery 5. Gynecologic

surg~ry

and obstetrics

6. Ophthalmic surgery 7. Urologic surgery 8. Vascular surgery 9. Dirty surgery due to contaminated wounds, Gunshot and sharp object trauma of any kind, Bum victims and animal and human bites 10. Prostatic surgery

Medical Indications: (1) Cardiac-Prevention of bacterial endocarditis prosthetic heart valves, cardiac valve defects, like stenosis or regurgitation, bacteremia producing procedures, congenital heart disease (single ventricle, Transposition of great vessels Tetrology of Fallot). Cardiac conditions associated with endocarditis Endocarditis prophylaxis recommended

High Risk Category • Prosthetic cardiac valves, including bioprosthetic and homograft valves • Previous bacterial endocarditis • Complex cyanotic congenital heart disease (e.g., single ventricle states, transposition of great arteries, Tetralogy of Fallot) • Surgically constructed systemic pulmonary shunts or conduits

Moderate Risk Categories • Most other congenital cardiac malformations (Other than above and below) • Acquired valvular dysfunction (e.g., rheumatic heart disease) • Hypertrophic cardiomyopathy • Mitral valve prolapse with valvular regurgitation and/or thickened leaflets • Endocarditis Prophylaxis not recommended

ANTIBIOTICS

443

Negligible-risk Category (No greater risk than general population) • Isolated secundum atrial septal defect • Surgical repair of atrial defect, ventricular septal defect, or patent ductus arteriosus (without residual effects beyond six months) • Previous coronary artery bypass surgery • Mitral valve prolapse without valvular regurgitation • Physiologic, functional or innocent heart murmurs • Previous Kawasaki disease without valvuiar dysfunction • Previous rheumatic fever without valvular dysfunction • Cardiac pacemakers (intravascular and epicardial) and implanted defibrillators Dental Procedures and Endocarditis Prophylaxis Endocarditis prophylaxis recommended: • Dental extractions • Periodontal procedures including surgery, scaling and root planning, probing and recall maintenance • Dental implant placement and reimplantation of avulsed teeth • Endodontic (root canal) instrumentation or surgery only beyond the apex • Subgingival placement of antibiotic fibers or strips • Initial placement of orthodentic bands but not brackets • Intraligamentary local anesthetic injections • Prophylactic cleaning of teeth or implants where bleeding is anticipated. (1) Prevention of Pneumonia and streptococcal infections and rheumatic fever. (2) Prevention of Pneumococcal infection in asplenic patients due to surgical removal of spleen post trauma or because of treatment due to hematological condition.

(3) Mananagement of recurrent ENT infections (4) Management of recurrent urinary tract infection proven by culture (5) Pertusis prophylaxis. SULPHONAMIDES These are a large group of antibacterial compounds which are structural analogues of P-aminobenzoic aCid(PABA). They differ in substituents in either amido group(S02-NH-R) or the amino group(-NH2) of the sulphonamide nucleus. Substitutes modify the solubility of

444

TEXT BOOK OF BIOCHEMISTRY

the drug resulting in different rate of absorption and excretion. Sulphadiazines for example are largely unabsorbed and therefore they are effective on local gut flora when administered orally. And so used in presurgical bowel sterilization. Sulfisoxazole is rapidly absorbed &rapidly excreted and maintains adequate blood levels upto 24 hours. Therefore they are used in treating chronic infections of urinary tract. Sulfacetamide andsulfadiazine are designed to use in topical conditions for infection of eye or in skin infections in burn patients. Sulfonamides are broad spectrum antibiotics effective against gm positive and some gm negative organisms of enterobacteriaceae. Good activity against E.coli, moderate activity against proteus mirabilis and enterobactor spp, poor activity against indole positive Proteus and Klebsiella spp and no activity against Pseudomonas. and Serratia spp. They are effective against Chlamydia, but super drugs are now available. Sulfonamides .are used in treating infections by Toxoplasma gondi and chloroquin resistant Plasmodium falsiparum malaria. Resistance - ocurrs as a result of one or more alteration in cellular metabolism of bacteria. Both mutation and plasmid mediated resistance. These changes can be irreversible and include alteration of physical and enzymatic properties or enzymes that metabolize PABA and participate in tetrahydrofolic acid synthesis. Bacterial cell resistance can be because of Alternative pathways of PABA synthesis in bacteria or increased capacity to inactivate or eliminate the compound. Bacteria that can use preferred folate are not affected by sulfonamides.

OH

N

Pteridine

PABA

Glutamate

Folic acid and its component molecules

Trimethoprims Structural analogue of pteridine portion of dihydrofolic acid, It differs from Sulfonamides that it acts in second step of folic acid synthesis pathway and completely inhibits dihydrofolate reductase. This is the enzyme that catalyses the reduction of dihydrofolic acid to tetrahydrofolic acid, which is the active form of folate. Dihydrofolate reductase is present in both mammalian tissue and bacteria, but 20 to 60 thousand times more drug is required to inhibit mammalian enzyme thus it is selectively toxic to bacteria. Tmp-smx or trimethoprim-sulfamethoxazole was introduced in 1968. Trimethoprim acts synergistically to inhibit bacterial synthesis of tetrahydrofolic acid. Combination also delays

ANTIBIOTICS

445

bacterial resistance. It is congener of Sulfisoxazole but slow in enteric absoption and excretion. Half life is similar to that of trimethoprim. Antibacterial spectrum is broad, active against most gm positive and gm negative organism especially enterobacteriae. Little activity against anaerobic bacteria like P.aeroginosa, enterecocci, and methicillin resistant staphylococci. Incidance of resistance is less than that observed when the drugs are used individually. Resistance is incrasing problem especially problematic in entrobacteriaceae against which combination is used in AIDs for Pneumocystis carini pneumonia prophylaxis. Uses: Genitourinary, GI Resp infections caused by susceptible bacteria, E.coli, enterococci, P.mirabilis. Some indole positive strains of proteus spp, Klebsiella Pneumonia, for chronic recurrent UTI. Also used for ampicillin resistant Shigella species, and resistant Salmonella spp, carrier state of salmonella typhi. Travellers diarrhea due to susceptible E coli. It is not indicated in E coli strains like 0157:H7 causing hemorrhagic diarrhea because of release of cytotoxic enterotoxin by drugs causing hemolytic uraemic syndrome. Also used in chronic prostatitis, gonorrhoea typhoid fever, Brucellosis, Protozoa, P.carini (used in aids and hemtologic malignancies P.carini causes pneumonia). It is contraindicated in renal damage and blood dyscrasias. Adverse effects are blood dyscrasias, CNS. disturbances ,skin rashes, megaloblastiC anemia, thrombocytopenia ,granulocytopenia and during pregnancy affecting foetus causing neural tube defects.

QUINOLONES Nalidixic Acid and Fluoroquinolones Most FDA approved quinolones in USA contain a tricarboxylic acid moiety in 3rd position in basic ring structure(the 4 quinolones). The 4 quinolones inhibit DNA synthesis through action on DNA gyrases, which are composed of two A and two B subunits. DNA units are the site of action of 4 Quinolones.Recently a second target unique to fluroquinolone identified as topoisomerase type 4 which are responsible for separating the daughter cells following replication. The quinolones are often classified into generation much like cephalosporins. The four generations of quinolones have spectrum specificity, although there is considerable overlap. First -

Nalidixic acid and cinoxacin

Second Third Fourth -

Norfloxacin, Ciprofloxacin, Ofloxacin, Enoxacin,and Lomafloxacin Levofloxacin, Sparfloxacin and Gatifloxacin Trovafloxacin, and Moxifloxacin

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TEXT BOOK OF BIOCHEMISTRY

Several new quinolones have come up as a result of aT prolongation & serious hematological & renal side effects. Antibacterial spectrum: First generation- Limited gram negative activity and so restricted to therapy for bladder infection caused by E. Coli, Clebsiella and Proteus spp. Use is restricted by resistance. Second generation: most reliable activity against Gram negative including Enterobacteriaceae, Hemophilus spp and sexually transmitted diseases (STOs) as caused by N. Gonorrheae, Chlamydia Trachomatis, Ureaplasma Urealyticum, and Moraxella cattarrhallis formerly known as N. Cattarrhallis. The anti pseudomonas activity of Ciprofloxacine, Norfloxacine, Ofloxacine and Lomefloxacine is due to Piperazine moiety. Resistance to these agents is becoming more prevalent. (Greater activity against S.Pneumonia, a gram positive organism is demonstrated by third and fourth generations.) Methicillin resistant Staph Aureus and Enterococcus Faecium are resistant. Fourth generation also possesses activity against anaerobes. Except the first generation, the auinolones are active against pathogens of respiratory tract as Chlamydia pneumonia, Mycoplasma pneumonia, Legionella, Mycobacteroid spp., and Bacilus anthracis- a major bioterrorism agent. Resistance is due to mutation in ONA-gyrase-A and Topoisomerase-4. Killing by quinolones is concentration dependent. and thus has a long post-antibiotic effect. Cross resistance can occur. They are rapidly and completely absorbed by oral route and widely distributed in tissue. The levels are higher in extravascular tissue. Lower levels occur in CSF, bones, and prostatic fluid. Ciprofloxacine and Ofloxacine are detected in breast milk and ascitic fluid. Half life is three to four hours. Elimination is through kidney by glomerular filteration and tubular secretion. Trovafloxacine has hepatic toxicity. Indications: Respiratory- Sinusitis, pneumonia due to H.influenzae, M. cattarrhalis. GI and Abdominal infections, STOs, pelvic and urinary infections. Ciprofloxacine is used for Trepanoma pallidum and Salmonella species. In general they are contraindicated for Entero-hemorrhagic E. coli. Because they can induce cytotoxin and Shiga-like toxin. Nitrofurans (Nitrofurontoins) - Furadantin, Macrodantin, 5-Nitro-2-furaldehyde derivatives. These are used primarily for urinary tract infections. Reduction of 5-Nitro group to nitro-anions results in bacterial toxicity and effect. Intermediate metabolites modify various bacterial macromolecules. That affects DNA and RNA synthesis, protein synthesis. So there is less resistance development. Macrodantin and Furadantin are active against gram negative organisms (E. Coli and P.Mirabilis.) and some gram positive organisms (S. Aureus and Enterococcus faecalis).

ANTIBIOTICS

447

Most proteus (Indole positive), Serratia and pseudomonas spp are resistant. Methenamine- These are aromatic acids that are hydrolysed at pH less than 6 to liberate ammonia and active alkylating agent - Formaldehyde which denatures proteins and is bactericidal. It is administered as Mandelic or Hippuric acid. It is administered orally and is well absorbed from intestinal tract. It needs enteric coating otherwise 30% is destroyed in stomach. It is excreted into urine in 24 hours. Uses: Primary longterm prophylactic or suppression of recurrent UTI. It is not primary drug for acute infection. Drug antagonism with sulphathiazole and sulphamethiazole is reported. B-Lactam Antibiotics A number of antibiotics produced by fungi of genus cephalosporium are Cephalosporins and are in combination with Penicillin-a p-Lactam ring. The other p-Lactams are Carbapenams and Monobactum. All p-Lactams block a critical step in bacterial cell wall synthesis

o

R-tNH-r(Y-

O}-~~COOH

~

(3-lactam ring

Thiazolidine ring

~----~vr------~

6-aminopenicillanic acid

The Structure of Penicillins Final reaction of bacterial cell wall synthesis is cross-linking of adjacent peptidoglycan strands. In this, cleavage of terminal D-alanine occurs from a penta-peptide as one peptidoglycan strand, then cross links it with pentapeptide strand of another peptidoglycan strand and this bacterial wall breaks. Most important resistance is by hydrdlysis of B-Lactam ring by B-Lactamases (Penicillinase and cephalosporinase). Bacteria-like staph. Aureus, Moraxella catarrhal is, N. Gonorrheae, Entrobacteriacaea, H. Influenzae and Bacteroids spp possess B-Lactamases that hydrolyse penicillins and cephalosporins. Transfer of genes between bacterial species has contributed to proliferation of resistant organisms. Clavulinic acid was developed to overcome the action of B-Lactamase. Some BLactamases are resistant to clavulinic acid also, which are cephalosporinases produced by citrobacter sppp species, enterobacter sppp, and pseudomonas aeruginosa. Additionally PBP alteration also causes resistance as in streptococcus pneumoniae, enterococcus, faecium. and methicillin resistant staph. Aureus (MERSA). Some gram negative bacteria have a third mechanism of resistance that reduces access to PBP.

448

TEXT BOOK OF BIOCHEMISTRY

PENICILLINS

Antibacterial activity resides in ~-Lactam ring. The structure common to all penicillin is p-Lactam ring fused to thiazolidine nucleus. Penicillin-G: This is natural penicillin. It is most appropriate for intra-muscular or intravenous use. The drug is excreted by kidneys- 90% by renal tubular secretion and 10% by glomerular filteration. Clinical uses: Endocarditis, pharyngitis (Group A ~-hemolytic streptococcus), cat-bite cellulitis (Past. multocida) and syphilis (Treponema pallidum). Depot injections of intra-muscular formulation like procaine and benzathine penicillins have decreased solubility, delayed absorption and prolonged half-life, therefore these cannot be used for acute infections of serious nature.

Penicillin-V is an orally absorbed phenoxymethyl congener of limited use. The anti-staphyllococcal penicillins are Napthcillin, Oxacillins, Cloxacillins and Dicloxacillins. They are more resistant to bacterial ~-Lactamases therefore they are more effective against streptococci and community-acquired penicillinase producing staphylococci. Napthcillin and Oxacillin are given by parenteral route and are metabolized in liver and excreted by kidneys. They are used in cellulitis, empyema, endocarditis, osteomyelitis, pneumoniae, toxic shock syndrome and septic arthritis. Orally cloxacillins and dicloxacillins are used for skin infections caused by staph. Aureus. Aminopenicillins: These are ampicillin and amoxicillin. Both have good bioavailability if given orally. Ampicillin should be given on empty stomach but amoxicillin can be given with food. Ampicillin achieves good therapeutic levels in CSF only during inflammation, so it is effective treatment in meningitis caused by Listeria monocytogenus. Ampicillin otherwise does not reach good concentration in CSF and is not a good treatment for milder meningitis. Other indication is serious infections like enterococcal endocarditis and pneumonia caused by H. influenza. Another use is to eradicate Heliobacter pylori. Antipseudomonal penicillins: Mezlocillin, piperacillin and ticarcillin are parenteral antibiotics formulated as sodium salts. Therefore they should be used with due consideration in congestive heart failure. Elimination is by renal route. Metabolism is by hepatic route. Spectra: Many gram positive and gram negative organisms including most anaerobes. Antipseudomonal penicillins are used for pneumonia associated with cystic fibrosis or mechanical ventilation. They are not appropriate for patients with renal failure as the dosage needs modification.

Carbenicillin is used by oral route but gets very little concentration in urine of renal failure patients. It is not used in renal failure. Carbenicillin is used for P.aeruginosa, proteus spp. And E.coli.

449

ANTIBIOTICS

~-Lactamase inhibitor combinations are - Unacin (ampicillin

+ sublactams), timentin (ticarcillin + clavulinic acid), zocyn(Piperacillin + tazobactam) and augmentin (amoxicillin + clavulinic acid). All except augmentin are given pareneterally. ~-Lactam

antibiotics have no fatal risk in animal studies.

CEPHALOSPORINS These semisynthetic antibiotics are derived from products of various microorganisms like cephalosporums and sreptomyces. They have a 7-aminocephalosporamic acid compound of dihydtothiazine ring fused to a ~-Lactam ring.

o

R-g-NHJ10 S

o

N

~

R'

eOOH ~

13 -Iactam ring

Dihydrothiazine ring

'----_,v,----.J

7-aminocephalosporanic acid The Structure of Cephalosporlns

As with penicillins antibacterial activity is resided in ~-Lactam ring. They also vary in acid solubility and ~-Lactamase susceptibility. Resistance developes from modification of microbialPBPs. Bactericidal spectrum: These are classified in varius generations, according to antibacterial spectrum and stability of ~-Lactams. First generation: These act against streptococci, methicillin sensitive S.aureus and a few Gm negative bacilli. Second generation: They have greater stability against p-Iactamase with broader Spectrum to include gm positive cocci, gm negative org and anaerobes. Cephalosporins (cefoxitin or Mfoxin) cefotan and cefmetazole (zetazone) have most activity against Bacteroides fragilis. Third generation: These have extended spectrum with higher degree of in vitro potency and p-Iactamase stability. They act against many gm negative bacteria and anaerobes, and also streptococci. They are less active against staphylococci than first and second generation. The agents with greatest activity against P. aeruginossa are Cefepime , Cefoperazone and Ceftazidme.

450

TEXT BOOK OF BIOCHEMISTRY

Cefapime, has been called fourth generation because of great activity against several gm. positive and gm negative organisms The difference between third and fourth generation is errelavent as clinical outcomes are similar. Most cefalosporins are highly bioavailable after intramuscular dose and some are good after oral dose. Cfuroxime (ceftin) and Cefpodixime are oral formulas in which ester is hydrolysed during passage through the intestinal tract mucosa and free cephalosporin enters systemic circulaton. Food with cefaloprrins reduces bioavailbility of some like cefaclor(ceclor) and so should be given on empty stomach. Tissue penetration in most tissues is good except CNS. Only Cefepime. Cefuraxime(zenacef), and Cefutaxime(claforan), Ceftriaxone(rocephin) and Ceftizidime(Fortaz) achieve therapeutic concentration in CSF. Therefore Cefotaxime and Ceftriaxone are of first choice to treat Brain abcess and meningitis. Excretion: Urinary excretion is the major pathway. Therefore patient with renal failure needs adjustment of doses and dose interval extention. Biliary excretion is important for some like Cefmetazole(cefobid), Cefoxitin and Ceftriaxoone as these achieve greater concentration in biliary than in plasma, and so in patients with Hepatic failure dose should be adjusted. Uses: First generation: Skin and wound infections. Used for antibacterial prophylaxis prior to surgery. Second generation: good against lower abdominal and gynecological infections for treatment and prophylaxis. Third generation: used for wide range of infections causing pneumonia, meningitis, peritonitis, peritonsillitis, sepsis syndrome and Iyme disease. Adverse Effects Allergic reaction: 95% of patients with morbiliform skin rashes resembling measles after penicillins, will tolerate cephalosporins. But if any patients had history of urticaria, angioaedema, anaphylaxis with penicillin, they should not be given cephalosporins without doing a skin test for penicillin.Th~ frequency of allergic reaction to cephalosporin is 1.7%, in patients with history of type I penicillin reaction and negative penicillin skin test. Most patients with negative penicillin skin test can receive cefalosporins safely. Cephalosporins have known to be associated with superinfections like Clostridium difficile, enterococci, MRSA, coag negative staphylococci, P.aeruginosa and candida albicans. Overgrowth with C. difficile occasionally causes pseudomembranous colitis in treatment with cephalosporins Extended spectrum betalactamases (ESBL)production can be due to third generation and produce that, P. aeruginosa and various enterobacter species.

ANTIBIOTICS

451

Bleeding is an uncommon side effect. Gall bladder sludge can occur at high dosage, and is diagnosed by ultrasound and occasionally leads to surgery. But it disappears after discontinuation of the antibiotic. The mechanism of action is the same as of others f3-Lactams. Imipenam cilastatin is a chemically stable analogue of Thienamycin produced by streptomyces catteleya. It has broadest of all f3-Lactam antibiotic's spectrum. It is active against most gram positive, gram negative and anaerobic bacteria. It is most potent against E. fecalis, B. fragilis, P. aeruginosa. Organisms resistant to imipenam include E. fecium, stenotrophemonas, maltophilia and MRSA. It is only given parenterally. Oral bioavailability is poor. Due to decreased metabolic clearance, imipenam is combined with cilastin (inhibitor of dehydrpeptidase). It is first line of empirical therapy of many polymicrobial pulmonary, intra-abdominal and soft tissue infections. Notable adverse effects of seizures affect one percent of patients. Three risk factors are old age, head trauma, previous seizure disorder, CVA, and renal failure. Ten percent of patients with history of peniCillin allergy are cross sensitive to imipenam/cilastin. Meropenam: This is another carbapenam with broad spectrum like imipenam. A methyl group attached at the one position of five member ring confers stability to dehydropeptidase. Antibacterial activity is similar to imipenam. Both imipenam and meropenam are used to treat highly resistant klebsiella pneumoniae producing ESBL (extended spectrum f3-Lactamase). Loracarbef (Lorabid), is a synthetic f3-Lactam of carbapenam class. Its chemical structure is similar to cefachlor. Antibacterial activity is similar to second generation cephalosporins. Monobactam: Natural monobactams have little antibacterial activity. A synthetic derivative called Aztreonam(azactam) has an excellent activity against gram negative organisms including P.aeruginosa. It is stable to most f3-Lactamases (Chromosomal and plasmid). It is not bioavailable after oral route. Given parenterally it can attain therapeutic concentration in CSF in presence of inflamed meninges. So it is important antibiotic for treating meningitis caused by gram negative bacilli. Most adverse effect is local reaction at the site of injection. Rarely it causes any other reaction. Aminoglycosides: These are hydrophiliC. polycationic, amine containing carbohydrates composed of three to five rings. Most of them are derivative of soil actinomycetes. Their polycationic chemical structure results in a binding to anionic outer bacterial membrane and causes bactericidal effect. They also bind to anionic phospholipids in mammalian cell membrane which causes toxicity in patients. Major aminoglycosides are amicacin, gentamycin, kanamycin, netilmycin, neomycin, streptomycin, and tobramycin. Action: Antibacterial action involves two synergistic effects. 1. Positively charged aminoglycoside binds to negatively charged sites on outer bacterial membrane and disturbs membrane integrity.

452

TEXT BOOK OF BIOCHEMISTRY

2. They bind to various sites on bacterial 30-S ribosomal subunits, disrupting the initiation of protein synthesis and inducing errors in translation of messenger RNA to peptides. They continue to suppress bacterial growth even after removal of antibiotic from bacterial environment. Ribosome disruption is the cause for this post-antibiotic activity. Administration of ~-Lactam antibiotics reverses the negative effects of low pH and low oxygen tension because of the ability of aminoglycosides to penetrate into bacteria. This accoun~s for synergism that occurs between ~-Lactam antibiotics and aminoglycosides. Uses: Gm negative bacillary pneumonia,acute salpingitisdue to N. gonorrhoea and Chlamydia trach. Combination of gentamycin ,clindamycin and doxicyclin is very effective in polymicrobial infection. Gentamycin and Clindamycin together is a very combination in treatment of intraabdominal infection or abcess secondary to penetrating trauma, diverticulitis, cholangitis appendicitis, peritonitis and postsurgical infection. These infections are often gm negative bacilli and anaerobes. Erradication of facultative gut flora can be done by giving combination of neomycin and nonabsorbable erythromycin orally. Neomycin with polymixin B and Bacitracin is very effective on skin infections and burns and cuts. Cystic fibrosis: P. aeroginosa is commonly found organism in cystic fibrosis in lungs and bronci. Daily inhalations of Tobramycin decreases colonization 100 Fold and improves function Endocarditis: combination of gentamycin and ampicillin is recommended for prophylaxis of endocarditis prior to surgery or instrumentation of gastrointestinal or genitourinary tract in high risk patients. It is also recommended for prophylaxis of endocarditis. Meningitis: High degree of penetration into CSF is related to degree of the inflammation of the meniges.Best combination is with betalactams for meningitis. Tuberculosis: Increase in resistance has been occurring to standard antibiotic chemotherpyand therefore aminoglycosides have been used at greater frequency in tuberculosis. Inhaled aminoglycosides are also used in patients with persistant positive sputum for Tb despite therapy. Streptomycin is most useful in initial therapy of severe or disseminated tuberculosis. Ophthalmic infections: high concentration of gentamycin is achieved in ophthalmic and conjuctival sac and therefore it is very effective against all all pathogens affecting eye. Special high doses are required for bacterial ophthalmic keratitis. Vitreous endophthalmitis requires vitreous aspiration and instillation of gentamycin and cefazolin. Gonococcal urethritis: Spectinomycin is occaSionally used in uncomplicated urethritis. Single daily doses are used more often than BID dosing as they are as effective and not more toxic as thought before. Single dosing in enterococcal endocarditis is not recommended.

ANTIBIOTICS

453

Toxicity: Nephrotoxicity, and ototoxicity Nephrotoxicity is reversible upon prompt discontinuation. Aminoglycosides cause both oto and vestibular toxicity. Streptomycin is more likely to cause vestibular toxicity than oto toxicity. Both are irreversible. Both are worsened by co-administration of vancomycin, furosemide, bumetanide and ethacrynic acid. Intravenous calcium may lessen ototoxic effects. Aminoglycosides also cause neuromuscular toxicity at neuromuscular junction causing blockade by displacing calcium ions. So it should be cautiously used in myasthenia gravis, hypocalcemia, hypermagnesemia and should not be used with neuromuscular blocking agents. These effects are reversible with intravenous calcium administration. Tetracyclines: They all have similar mechanism of action. They are produced by different species of streptomyces and have different chemical structure. There are synthetic structural analogues of these tetracyclines which have improved antimicrobial properties. Several biological processes are modified by tetracyclines. Primary mode of action is inhibition of protein synthesis by binding to 30-S ribosome and binding of aminoacyl transfer-RNA to A site on 50-S ribosomal unit. They penetrate in bacterial membranes, accumulate in cytoplasm by a special transport system that is absent in mammalian cells. Resistance occurs due to change in cell permeability, and production of proteins which alter the interaction of tetracyclines with RNA. They are particularly absorbed from upper GI tract. Food impairs absorption except that of doxycycline and minocycline which actually get better absorption with food. All types of tetracyclines form insoluble chelates with calcium therefore calcium containg foods like milk hamper their absorption. Minocycline and doxycycline are most fat soluble and penetrate meninges and placental barrier. Peak serum level occurs in two hours. All are metabolized in liver, concentrated in bile and excreted in feces. Uses: Doxycycline is good for urinary tract infection because it lacks nephrotoxicity and has prolonged half-life. It is also used in Lyme disease and anthrax in adults and children above eight years. Minocycline is an effective alternative to rifampin for irradication of meningococci from nasopharynx. They have dose related yestibular side-effects. All tetracyclines are drug of choice for cholera, rickettsia, coxiella, granuloma inguinale, relapsing fever, chlamydial diseases, psittacosis, nonspecific urethritis, brucellosis, pasturella, mycoplasma, and pelvic inflammatory disease. They are no longer used for streptococcus pyogen us and strep. Pneumoniae. Reactions: photosensitivity, rashes, staining of teeth, hepatotoxicity (specially during pregnancy), and retardation of bone growth. Pulmonary eosinophilic syndrome may occur during eight to nine days of treatment. Chloramphenicol: It is a nitrobenzene derivativie that affects protein synthesis by binding to 50 S Ribosomal unit and preventing peptide bond formation. The attachment of aminoacid end of aminoacyl RNA to A site is blocked, and association of peptidyl tranferases

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with amino acid substrate is blocked. Mitochondrial protein synthesis inhibition is responsible for toxicity. It is a broad spectrum antibiotic active against gm positive and gm negative organisms including Rickettsia, Mycoplasma and Chlamydia, anaerobes including Bacteroids fragilis. It is rapidly and completely absorbed from g.i. tract.Biological half life is 1.5 to 3.5 hours. 60% of drug is bound to albumin and it penetrates meninges and brain tissue and placental barrier. Inactivated by liver and rapidly excreted in urine up to 80 to 90%. By renal glomerular filteration and tubular secretion. Most adverse effect of fatal nature of chloramphenicol induced bone marrow suppression restricts its use to few life threatening infections in which benefits outweigh the risks. It is the choice treatment in specific bacterial meningitis of H.influenzae, N. meningitides and S. pneumonia. It is also used in osteomyelitis and epiglotitis caused by the above bacteria. It remains a major treatment option in typhoid and paratyphoid fever in developing countries. It is also used for topical. treatment of eye infections, but aplastic anemia even by such route limits its use. Macrolides These are antibiotics with large lactone ring to which sugars are attached. Erythromycin, ilotycin, clarithromycin, azithromycin and oleandromycin are included in this group. Mechanism of action is by binding to 50-S ribosomal subunit of bacteria but not to 80-S mammalian ribosome. Antibacterial activity against a number of organisms including mycoplasma spp, H. Influenzae, Streptococcus spp (Pyogenes and pneumoniae), Staphylococci, Gonococci, Legionella pneumophila, and other legionella spp. There is increasing resistance of S. pneumoniae world-wide to Penicillin and macrolide. Staphylococci resistant to erythromycin are resistant to other macrolides. Clarythromycin and azithromycin are significantly active against mycobacterium avium. They are both used prophyllactically in HIV and AIDS patients to prevent superinfections. Clarythromycin is very active against H. influenzae, Legionella and mycobacterium avium. Azithromycin is very active against Branhamella Neisseria and H. Influenzae. They have good absorption index from GI system. They are given as enteric coated tablets. They defuse readily into the tissues across placental membranes. CSF levels are about 20% of plasma levels. Biliary levels are ten times of the plasma level. They are excreted in active form in bile and only low levels are found in urine. Uses: Erythromycin: used in Mycoplasma pneumonia, eradication of coryne bacterium diphtheriae from pharyngeal carriers, Chlamydial infections and Legionaire's disease. Clarythromycin: has all the above uses plus the action against Toxoplasma gondii, and Mycobacterium avium intraceliularae and untypable strains of H. Influenzae in chronic bronchitis.

ANTIBIOTICS

455

Adverse effects: Low general adversity, mild GI upset, rashes including fever and eosinophilia. Thrombophlebitis may follow intravenous administration and can also cause transient impaired hearing. LlNCOSOMIDES This family of antibiotics includes Lincomycin and clindamycin (Cleccin). Both inhibit protein synthesis. They bind to 50-S ribosomal subunits at a binding site close to binding site for choramphenicol and erythromycin. They block peptide bond formation by interfering at A or P site on the ribosome. Lincomycin is no longer used in United States. Clindamycin is highly active against staphylococci and streptococci other than enterococci. They have significant activity against S. pyogenes (Group A Strep.). Adverse effects: Pseudomonas colitis has limited its use to penicillin resistant anaerobic bacterial infections. It has shown best topical use against Coryne bacterium acnes in recalcitrant cystic facial acne. Precaution should be given to all patients using topical treatment, of development of colitis of pseudomembranous type. Therefore it should not be used without good justification.

REFERENCES Alvarez elleoro and enzier m.j sympozium on antimicrobial agents part ix, part x and part xi 1999. Aznar ar et al eur j. Cardiolothorasic surg 1991 5;515 Barker ii fg neurosurgery1994.25:484 Bass j w antibiotic management of group a sreptococcal pharyngotonsillitis, pediatric infectious dis journal 1991 .10.543 Block sl, hendricks ja, tyler rd. Comparative study of cefixime & peniCillin v for srept phryngitis in children & adolescent. Pediatric inf dis j 1992.11 :919-925 Boswell 1.g and wise r. Advances in the macrolides quinolones infectious dis clinics north america 1998.12 Carabello ba. Mitral valve disease. Curro Problems in cardiology 1993,7,423-478 Child js. Risks for and prevention of endocarditis, cardiology clinics, diagnosis and management of infective endocarditis philadelphia, w'b saunders 1996.14.327-343 nders 1996.14.327-.343 Clancy jp et al evidence that systemic gentamycin supresses premature stop mutationin patients with cystic fibrosis. American j resp crit care med 2001 ;163;1683-1692 Dacosta h et al circulation 1998;97;1796 Dobay kj et al ann surg 1999.65;226 Garret do et al the emergence of deceased susceptibility to vancomycin in staph. Epidermidis infect control hosp epidemiology 1999 Gorback sl infect dis clin pract 1999;8;1 Huang etal drugs 1991 ;41 ;19 Kaye d. Prophylaxis for infective endocarditis annals of int med 1986.104.419-423 Kunin cm urinary tract infect 5th edition baltimore williams &wilkins

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Murray be vancomycin resistant enterococcal inf new eng I j med 2000.342; 710-721. Report of the committee on infect diseases american academy of pediatrics redbook 21 st edition elk grove village iI aap 2000 Resp crit care med 2001;163; 1683-1692 Sanford jp . Guide to antibiotic therapy 1998. 28th edition W.b. Saunders 1996.14.327-343.

QCHl

INORGANIC METABOLISM

SODIUM Sodium is regarded the principal component of the extracellular fluid (plasma) and is chiefly asso'ciated with chloride and bicarbonate. It is also associated with phosphate and lactate. Sources:

Common salt (NaCI). . Requirement:

5 to 15 gm/day (Normal) Hypertensive Disorder: Intake is less or advised Salt-free diet. Congestive Cardiac Failure: Advised Salt-free diet. Almost all dietary ingradients contain NaCI. Therefore meaning of Salt-free diet is not to add any salt (NaCI) while cooking and while eating. Sea-water food (fish) and shell fish, crabs, prowns are to be avoided. Absorption:

Gut is freely permeable to water and NaCI. Functions

1. It maintains the osmolarity of plasma and thereby maintains the osmotic pressure of plasma and to protect fluid loss from the RBC so that hemolysis does not occur and thereby RBC remains suspended with plasma. 2. It maintains the pH of plasma and that of blood by its association with chloride and bicarbonate in regulation of acid-base balance.

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3. Plasma level of sodium is maintained by sodium losses out of the body and sodium intake. 4. Intracellular sodium is maintained by body by 'the Homeostatic mechanism along with that of potassium level which defends the osmolarity of plasma. 5. Normal daily intake of sodium chloride has been recommended to be one gram per day. 6. Sodium intake depends on sodium losses from the body by way of urine, sweat formation, body heat, atmospheric temperature and water (fluid) intake. Therefore water balance and sodium balance goes hand in hand to maintain normal blood pressure. 7. Heavy mannual work (exercise) amounts to heavy losses of water and salts in sweats. This is in addition to extreme climatic condition like hot weather, sultry weather assuming that the endocrine dysfunction is not observed. 8. The body tries to maintain the balance of Salt (NaCI), however this balance is rather disturbed by excessive salt (NaCI) intake which precipitates in water retention, and it results in increase SystOliC pressure with unknown etiology. This is perhaps refered to as Essential Hypertension. 9. It is estimated that 10 gm of NaCI is thus ingested daily in cooking allow 4 gmof . Na+ (Sodium) intake. Besides this, Dietary habits of consuming extra salt while taking the food disturbs Sodium: Potassium balance and then it precipitates into elevation of SystOliC Pressure. 10. Sodium contents are high in bread, cheese, clam, oysters, crabs, wheat germ and soaked cereals, vegetable like carrots, cauliflower, celery, eggs, legumes, spinach, tumips, prunes, raddish, oatmeal etc. 11. About 95% of sodium intake is excreted in urine. 12. Sodium is readily absorbed by active diffusion and by passive diffusion through illium. Distribution of Sodium in Body Fluid or Tissues

Fluid or Tissue

mg/dl (100 g.)

mEq /litre

Whole Blood

160

70

Plasma

330

140

Cells

85

Muscle Tissue

60-160

Nerve Tissue

312

In Chronic Renal Disease, sodium depletion may occur due to poor reabsorption status of tubule and also due to buffering action when excreted in acidosis.

INORGANIC METABOLISM

459

In case of sudden sweating, sodium depletion occurs and sodium potassium balance is disturbed. This may occur following a change of environmental temperature. Any extreme disturbance in Na/K ratio may precipitate in muscular cramps in calf muscle and of the extremities, in abdomenal spasm, headaches, nausea and diarrhea may develop. The levels of sodium may not reflect accurately the total body sodium. If a subject is given salt-free liquid diet, sodium contents of tissue are unaffected but overhydration occurs. Plasma serum shows low sodium values (Hyponatremia occurs). Swelling occurs on extremities. Such a condition is seen in Congestive Cardiac Failure and in cirrhosis of Liver. Under the circumstances serum sodium is low, however, tissue sodium is high. Therefore use of diuretics in correction to water balance and that of sodium contents, has to be done under careful medical supervision. Loss of sodium in sweat followed by dehydration may result in cramps in extremities. These are some effects of Hyponatremia.

Addison's Disease: It is a pathology which brings about the necrosis of Adrenal Cortex or Tuberculosis of Adrenal Cortex whereby cells of adrenal cortex ceased to function. This causes a loss of Na+ and K+ is retained back. A tumor on adrenal cortex or hyperplacia will cause a hyper-secretion of ACTH. This will induce the retention of ·Na and will cause a loss of K. Therefore high levels of sodium will be observed and low levels of potassium results.

High Levels of Na (Hypernatremia) Caused by: (a) High Intake of NaC!. (b) Hyper activity of adrenal cortex. (c) Administration of ACTH or Cortisone Therapy. (d) Rapid loss of Water.

Effect of Low Potassium and High Sodium on ECG: 1. Tachicardia 2. AV Block -

Increase in Heart beats. Atrial Ventricular Block.

3. Enlargement of Heart (Dilatation of Heart) - Enlargement of Heart is accompanied with enlargement of Atrium and Left Ventricle. 4. Sagging of ST Segment. 5. Cardiac Arrest.

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POTASSIUM 1. Potassium is chiefly considered to be a intracellular element but is present in extracellular fluid. 2. It influences the cardiac muscle and the other muscle like skeletal muscle etc. 3. Within the cells it functions like sodium, maintaining acid-base balance and the osmotic pressure. 4. High intracellular potassium concentration are essential or metabolic function like protein biosynthesis by ribosomes. 5. A number of enzyme including glycolytic enzyme pyruvate kinase require K+ for maximum activity. 6. It helps to maintain osmolarity and to maintain water retention. Normal Requirement:

4 gm/day. Sources:

Widely distributed in citrus variety of fruits. Dried Apricots. Peaches, Pineapples, Brocoli, Potatoes, Coconut water, Bananas. Non-Veg. Sources: Veal, chicken, beef liver, beef pork, shell fish etc. Distribution:

Plasma

20 mg/100 ml.

Cells

440 mg/100 gm.

Muscle

250 - 400 mg/100 gm.

Nerve

530 mg/100 gm.

Metabolism:

Any variation in the extracellular fluid affects skeletal muscle, striated muscle following a deficiency. Abnormalities result in conduction affecting thereby cardiac muscle. Aldosterone controls Na+ and K+ metabolism. When Na+ is reabsorbed and K+ is excreted out under the aldoserone secretion. This action takes place on ascending Limb of Loop of Henle. Aldosterone Secretion:

Na+ is reabsorbedlK+ is excreted out. No Secretion:

Na+ is excreted/K+ is absorbed.

461

INORGANIC METABOLISM

Serum potassium level remains slightly elevated in chronic renal failure. This is because potassium is secreted by the cells of distal convaluted tubule. The kidney is the principal organ of excretion for potassium. The capacity of kidney to excrete potassium is so great that hyperkalemia will not occur even after ingestion or intravenous injection at a moderate rate of relatively large quantities of potassium. However, potassium is not to be given Intravenously under any circumstances, lest it should not cause cardiac arrest. Distribution of Potassium In Body Fluids or Tissues

Fluid or Tissue

mg/dl or d/gm

EqlLitre

Whole Blood

200

50

Plasma

20

3.5 - 5

Cells

440

112

Muscle Tissue

250 - 400

Nerve Tissue

530

Hyperkalemia: Hyperkalemia occurs in paitents under the following conditions: 1. Renal failure. 2. Severe Dehydration. 3. Addison's disease due to decreased excretion of potassium by the kidney. 4. Shock. Symptoms:

(a) Bradicardia is induced. (b) Low heart sound followed by peripheral vascular collapse leading to cardiac arrest. (c) Mental confusion, Numbness of extremities, Weakness of respiratory Muscles followed by paralysis. The symptoms are corrected by steroid administration which corrects sodium potassium balance by sodium retention and potassium excretion. Hypokalemia: A long persistant hypokalemia causes injury to myocardium and to kidneys. It may be induced by steroid therapy which retains sodium and excretes potassium. Hypokalemia may be induced by the hyperactivity of Adrenal Cortex (Cushing Syndrome or primary aldosteronism), Diuretics like Acetozolamide (Diamox) and Chlorothiazide (Diuril). Potassium suppliment has to be given since excretion of Na+ and K+ occurs along with water excretion.

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A prolong deficiency of potassium may produce a severe damage to kidney. This may be associated secondarily with the development of pyelonephritis in chronic state. During Heart Failure (CCF) potassium content of myocardium becomes depleted. On recovery intracellular potaSSium repletion occurs. This increases the sensitivity of myocardium to Digitalis intoxication and to arrhythmias. Such patients who have been taking frequent digitalis therapy, if put on diuretics are carefully observed when put on K+ therapy in order to prevent or relieve from Digitalis toxicity. Therefore in such patients correction of water balance is to be restored with correction of Na+ and K+ balance. When one gm of glycogen is stored 0.36 mMol of potassium are simultaneously retained. In the treatment of diabetic coma with insulin and glucose, glycogenesis is rapid and potassium is quickly withdrawn from the extracellular fluid. The resultant hypokalemia may be fatal. Low Serum Potassium (Hypokalemia):

May evoke in the following conditions: 1. Malnutrition 2. Negative Nitrogen Balance 3. Excessive Vomiting 4. Diarrheas 5. Patient with Hypertensive Disorder is kept on Diuretics. 6. Patients under hydro-cortisone therapy (ACTH). Symptoms for Hypokalemia:

1. Muscle weakness, pain in calf muscles and irritability. 2. Tachy-cardia. 3. Dilatation of Heart 4. ECG Changes: (a) T-wave Flattened in the beginning and gets inverted in later stage (b) Sagging of ST segment (c) A.V. Block (d) Cardiac Arrest. Effect of High Concentration and Low Concentration on Cardiac Cycle:

K+ Excess / Na+ Low

K+ Low / Na+ Excess

Bradicardia is induced 2nd or 3 rd degree

Tachicardia

P-R interval is increased. Conduction is very low

P-R interval is reduced. Results in AV Block

Q R S Widening

Enlargement of Atrium

T wave is elongated

Sagging of ST segment and gets inverted.

Induced Bradicardia results in the end of cardiac activity. DEATH.

Cardiac arrests takes place.

INORGANIC METABOLISM

463

CHLORINE Chlorine is a gas which is used in several industrial preparation. In the body it is present as salt of sodium or potassium. Its physiological functions are as follows: 1. It is component of NaCI, KCI and is essential in acid base regulation.

2. It is essential in water balance.

3. It takes part in HCI formation in gastric juice. 4. Chloride acts like an activator for amylase enzyme. Sources: Common salt (NaCI) from sea waer. (Molecular Wt. 58.5). Distribution: Plasma Cells CSF Muscle Nerve

365 mg/100 ml 190 mg/100 gm 440 mg/100 ml 40 mg/100 gm 171 mg/100 gm.

Requirement: Adults

10 gms of NaCVday

Children

5-7 gms of NaCVday

Pregnancy and Lactation

10 gms/day.

Excessive consumption creates problems unless or until industrial worker and the one who is doing laborious hard work in hot weather requires more salt for maintenance of salt and water balance. Blood level of Chloride: Normal level 96-105 mMol ILitre. Distubrances: 1. Arise in excessive loss of NaCI from urine and in excessive sweating. 2. In vomitting gastric juice is lost (chloride is lost). 3. Hypochloremic alkalosis may develop in cushing syndrome (Hypernatremia).

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WATER METABOLISM Intracellular Fluids:

50%

Extracellular Fluids:

20%

(15% Interstitial Fluid 5% Plasma)

70%

Water Intake

Water Loss

Drink Solid Food Oxidation Food

1350 ml 900 ml

Lungs

450ml

Urine

Skin Faces

2700 ml

Total

500 ml

700 ml 1400 ml 100 ml 2700 ml

Water Intake:

Water is supplied to the body via (a) water taken orally (b) along with the food intake (c) water produced on combustion of: Fat produce

107 mV100 gm

Protein produce

41 mV100 gm

Carbohydrates

56 mV100 gm

204 mV100 gm

Water Losses:

Water is lost from the body via four routes: • Evaporation from skin and lung • Urine formation • From large intestine in stool formation • Perspiration Water is lost from the body in GI infection as Diarrhea, vomitting, in excessive urine formation as in osmotic diuress. Water losses depend on climatic conditions. In sultry, wet weather urine formation is fast and frequent urination cause water loss. It is therefore very important to study as to how urine formation takes place with reference to hypotonic urine or hypertonic urine formation defending thereby osmolarity of plasma. Water balance is controlled by intake of water and the water lost from the body. Hormones controlling water-balance are ADH, Vassopressin, Oxytocin and the Aldosterone influences on maintaining osmolarity of plasma in the reabsorption of NaCI. ADH control is very important in the Facultative reabsorption of water.

INORGANIC METABOLISM

465

Functions of Water: 1. It is an essential constituent of living cell. No living entity can resist drying. 2. By its solvent action, it serves as universal medium in which the intra and extracellular reactions take place. Probably no chemical reaction inside the body can take place without water. 3. It acts as a medium for various physical processes such as osmosis, diffusion, filtration etc. 4. Hydrolysis: It is an important chemical process involved in digestion and metabolism. In this process H+ and OH- ions of water are introduced into bigger molecules and the latter are broken down into smaller units. 5. Dehydration and condensation: In these processes, water molecule is removed. This takes place in certain synthetic processes in which bigger particles formed by the union of smaller ones e.g. glycogen synthesis from glucose. 6. Ionising Medium: Water is very good ionising medium. The dielectric constant of water being very high, oppositely charge ions can co-exists in water without much interference. 7. It acts as vehicle for various physiological processes (a) For absorption of food material from intestine. (b) For reabsorption process from renal tubular cell (c) For the transport of various absorbed food particles. (d) For the drainage and excretion of end product of metabolism. (e) For the transport of various secretary juices and (f) For carrying various Hormones for their action. 8. Heat Regulation: (a) Heat Absorption: More heat is required to raise the temperature of 1°C of 1 gm of water. By virtue of this property of water can mop of a large quantity of heat. (b) Water possesses heat conducting power therefore heat is evenly distributed. (c) Heat loss is through the urine and stool formation and from evaporation through skin and lungs. Water has got the highest latent heat of evaporation. 9. Lubricant Action: Water acts as Lubricant to prevent the friction and prevent drying. In jOints, pleura peritoneum, conjunctiva etc the aqueous solution is practically free from fats and acts as a lubricant against rubbing and from drying so that friction would be avoided and joints are not worn out. 10. The aqueous humour helps to keep up the shape and tension of the eye ball and acts like a refractive medium for light. 11. The cerebrospinal fluid contains 99% water which acts like Buffer and helps in preventing shocks to Brain (CNS). (Shock absorbing fluid) 12. Respiratory Function: Though CO2 and 02 are only slightly soluble in water, yet this little solubility is of immense importance for the gaseous exchange in tissues and lungs. The fish derive oxygen almost exclusivly from dissolvd oxygen in water.

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TEXT BOOK OF BIOCHEMISTRY

Major Channels of Excretion: 1. Lungs

2. Skin 3. Kidneys 4. Faces

5. In Lactating Female 6. Ocassionally the Tears. Water Intoxication: This is a condition, caused by retention of water due to failure of water excretion. This occurs because of renal failure basically which because of hyper secretion of Anti-diuretic hormone results in more absorption of water from the tubular filtrate under normai circumstances. ADH activity is excreted provided, more amount of water is to be retained by the body. Secretion of ADH

i

results in retention of water (Hypertonic Urine).

No Secretion of ADH

J..

results in Excretion of Water (Hypotonic Urine).

Water portion which is absorbed by the tubule under the ADH control is refered as Facultative Reabsorption of Water. This is achieved by the anterior hypothalamic region of the brain. In normal circumstances when blood is concentrated, these osmo-receptor are stimulated, ADH secretion occurs. This ADH exerts its action and water is reabsorbed with the result normal urine is formed with normal specific gravity. On the contrary when the Blood is diluted due to lots of water is taken in, little or no ADH activity is seen which permits the water excretion. This is achieved by osmoreceptors which are located on anti-hypothalamic region. When the blood circulates through this region osmo-recepter senses whether ADH activity is to be exerted or not. Accordingly ADH secretion occurs. Dehydration: When the water-loss exceeds the water intake precipitates in a stage of dehydration. As we have seen water balance is dependant on Na+ and K+ balance, therefore a loss of water is always accompanied with disturbance of Na+ and K+ balance. Therefore unless or unitill sodium and potassium balance is restored simply correcting the water-balance wiil be of no use. Diabetes Insipidus: This is condition caused by decreased secretion or absence of ADH hormone. ADH is formed by posterior pituitary gland and it excrets its action when the blood flows through anterior hypothalamic region where osmo-receptors are situated. On their stimulation ADH secretion occurs which prevents Diuresis.

INORGANIC METABOLISM

467

In the absence of ADH, Diabetes Insipidus occurs. A large volume of water is excreted out even upto 30 liters per day with hypotonic urine formation. With this state sodium is lost and potassium is retained and patient is in severe dehydration as the water is also lost. Aldosterone:

This is secreted by Adrenal cortex. Under its action, an active absorption of Na+ occurs from the ascending limb of loop of Henle along with water and Na: K balance is restored. Dehydration:

It is very common in children when any infection occurs in pediatric age. It causes severe diarrhea and vomits, whereby there is loss of sodium and potassium along with water in the fecal matter. This results in severe dehydration and patients gets a shock. Unless or untill infection is treated along with saline drip and the stool binder, control cannot be achieved. Osmotic Diuresis:

This occurs in patients suffering from Diabetes Mellitus. When this is not controlled, the excess sugar above renal threshold (above 180 mg/dl) comes in urine. This causes diuresis which is refered to as osmotic diuresis. Diuresis depends upon on stress hormone i.e. Adrenaline and the stress condition prevails. Simple thinking, worries, unknown thinking can cause the secretion of stress hormone which might precipittate into diuresis and dehydration causing thereby the excessive loss of sodium and potassium along with water and precipitating into hemo-contration and shock. SODIUM - POTASSIUM PUMP

In the erythrocyte, whenever one ATP mol is hydrolysed three sodium (Na+) ions travel out and at the same time two potassium ion travel inside. ATP is hydrolysed ADP and inorganic Phosphate. This transport of Na+ against K+ i~ known as active transport and was discovred by Skou. Such a reaction has been located in many cell membranes. ATP

Na+-K+ ATPase)

ADP + Pi

Credit goes to Skou in 1965; Dahl and Hukiu (1974) for their discovery. Cardiac glycoside e.g. Ouabain inhibits ATPase activity. During the process of glucose absorption Crane had proposed to account for Na+ dependent transport of glucose absorption from the intestine to Blood. This therefore accounts for an active trasport of glucose absorption with sodium which is accompanied with ATP hydrolysis.

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TEXT BOOK OF BIOCHEMISTRY

Cell Membrane

Outside 2 K

+

Inside 2 K

ATP

ATPase

3 Na+

+

0

3 Na + ADP + Pi

CALCIUM Calcium is very important element of the body and its concentration is to be maintained. Basically it should be made available to the body by way of diet and body should make itself complied with all favourable factors required for its absorption through the gut.

Physiological Importance: In body of an adult male weighing 70 Kg contains approximately 1200 gm of calcium. AbouC99% of the body calcium is in the skeleton where it is maintained as deposits of calcium phosphates in a soft fibrous matrix. The matrix of the bone has a unique structure essetial to normal calcification. The bone contains a substantial amount of Non-Crystalline amorphous calcium phosphate . The bone tissue is being formed and reabsorbed more rapidly during early development and at a slower rate as the age advances. It is estimated that in adult male 700 mg of calcium enter and leave the bone each day.

Chief Functions: 1. Calcium and phosphorus are essential in the formation, development and the maintainance of bone structure. 2. Calcium remains in three forms: (1) Ionised form as Ca++ ions 40 to 50%. (2) Protein bound form. (3) Ca as Ca citrate. 3. Ionised form is required for coagulation of blood. 4. It regulates the excitability of nerve fibres and nerve centres. 5. It is essential for conducting Nerve impulses and for muscle contraction.

469

INORGANIC METABOLISM

6. It regulates the permeability of the membrane. 7. Normal activity of muscle is maintained by Ca, Na and K Contents.

8. It acts as an activator for several enzymes reactions e.g. ATPase, Proteolytic and Dehydrogenase enzymes.

Sources: Veg: Natural Milk and Cheese, Nuts, Figs, Cabbage, Cauliflowers, Turnips etc. Non-Veg. Sources: Oysers, Shell-fish, Crabs, Meat, Egg yolk, etc. Daily Requirement: Males and Females

800 mg.

During Pregnancey and Lactation

1200 - 1500 mg.

Infants 1 year

350 - 550 mg.

Children 1-18 years

800 - 1200 mg.

Calcium from the diet is absorbed from the upper part of intestine at optimum pH of 5.4. This pH is maintained by the proteins of diet. For protein acidic pH is maintained in the stomach. When these contents enter the small intestine the pH becomes favourable for· Calcium absorption. Ca-absorption is under the control of active form of Vit. O2 or 0 3 namely 1,25 dihydroxy cholecalciferol which is produced in the kidney. Hydroxylation of cholecalciferol occurs in liver. Tissue Cholesterol

~

7-Dehydro-Cholesterol \

(Skin)

Ultraviolet

Light Plasma Cholecalciferol

Preformed / Cholecalciferol [Fortified, irradiated Foods]

f---+

Liver 25-hydroxy Cholecalciferol

r-.

Kidney 1,25 Dihydroxy Cholecalciferol

Acts on

small Intestine

Calcium Absorption Target - Tissue Small Intestine, Bones etc.

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TEXT BOOK OF BIOCHEMISTRY

Absorption of Calcium is influenced by the following factors: 1. Vitamin D synthesis in the active form i.e. 1,25 dihydro cholecalciferol formation occurs from D2 or D3 in the kidney and its action is exerted on small intestine. 2. Ca++ absorption takes place at pH 5.4. Therefore pH of the upper portion of small intestine should maintain acidic pH for maximal Ca absorption. In the alkaline pH Ca++ is relatively salted out. Hence alkaline pH decreases Ca absorption. Besides pH 5.4 is the isoionic point of Ca++. 3. High concentration of magnesium in diet decreases the absorption of Ca. 4. Phytic (Inositol Hexaphosphate) which occurs in cereal grains form insoluble phytin with Ca and magnesium resulting into poor absorption. 5. High contents of protein in diet favour the Ca absorption. 6. Long chain fatty acids and short chain fatty acids form insoluble Ca-salts and are poorly absorbed. 7. Presence of fiber in diet interferes with Ca-absorption. 8. Oxalic acid in the diet form insoluble Ca-oxalate and is excreted out in faces thereby decreasing the absorption of Ca. 9. After the age of 45-50, intestinal absorption slowly decreases with the result bone becomes weak (porous). 10. Excessive Ca-therapy after the age of 45 is to be monitored for its deposition in the intima of arteries along with cholesterol. 11. Adrenogluco-cortico steroids diminish intestinal transport of calcium. Distribution of Calcium In Body Fluids Serum

9 - 11 mg/100ml

C. S. F.

4.5 - 5 mg/100 ml 70 mg/100 gm 15 mg/100 gm.

Muscle Nerve

Serum Calcium exists in following Three Forms: (a) Ionized Ca++ (b) Protein Bound FOrm}

) )

45 to 50% of Total Calcium 55 to 60% of Total Calcium.

(c) Calcium Citrate Plasma protein (Albumin) is bound to Albumin therefore any decrease in protein will be accompanied by a decrease in calcium level. Plasma phosphate have a reciprocal relationship with Calcium. A marked decreased in serum phosphate causes a fall in serum calcium concentration.

INORGANIC METABOLISM

471

Ionic Product: Ionic Product of Ca X P (in mg/dl) is always 40 in adults while in children it is 50. If this product is reduced, body tries to absorb Ca from the intestine which is under the control of 1,25 dihydroxy cholecalciferol for which diet should be rich in Ca++ and factors favouring the absorption should be positive so that Ca++ absorption takes place under normal metabolic status, the ionic product is kept constant (original value of 40). This value is maintained as per Homeostatic mechanism. If this ionic product is less than 40, first step taken by the body is to correct the intestinal absorption of Ca++ for which the following factors should be favourable. • Ca++ should be present in diet. • pH should be favourable for Calcium absorption (5.4). • There should not be any phitate in diet. If Ca++ absorption takes place, it will correct the ionic product and the metabolism will be corrected. However, if the intestinal absorption is unable to correct then PTH gland is stimulated and PTH is secreted PTH hormone exerts its action on Liver whereby liver produces more of Alk-phosphatase enzyme. It acts on bone salt [Ca3(P04)2] and Ca++ is mobilized which corrects the ionic product of Ca X P to 40. Opposing to this action, another hormone is secreted which is known as Thyrocalcitonin. This opposes the action of Alk. Phosphatase and prevent thereby resorption of bone. Thyrocalcitonin thus acts as antagonist to the action of PTH. If the resorption of bone takes place then bone becomes porous, brittle which is refered as osteoporosis. In children the same conditon prevails because of deficiency of Vit. D active form it is called Rickets. Osteoporosis of bones is not well understood till today. Once the bone loses its Calcium deposits, a large intake of Ca above 1500 mg/day has no significant effect. EveI"' if protein intake is improved, there is no sigificant improvement on osteoporosis.

Hyper Parathyroidism: This causes hyper secretion of parathyroid gland whereby PTH induces more of alkaline phosphatase activity. Bone become decalcified and become porous and brittle. It causes increased renal losses of phosphorus. Ca: P ratio is reduced below 30 since there is a loss of Calcium and Phosphorus from the soft tissue and from Bone. In adenoma of parathyroid ionise calcium ranges from 6.1 to 9.5 mg/dl. Therefore determination of ionised calcium will be of diagnostic and prognostic value.

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Hypo-Parathyroidism: If the cells of PTH gland are depressed in function or by mistake the gland is removed, serum calcium may drop below 7 mg/dl. There is concomitant increase in serum phosphate and a decrease in urinary phosphate. Renal Tubular Defect: Tubular defect exists in reabsorption process: • Failure of reasborption Glucose results in abnormal low glucose in blood since the filtered glucose is lost in urine. • Ca and P are lost in urine because of the tubular defect of reabsorption. Even one tries to correct the defect there is a continuous loss of Ca and P from the kidney. • Low Ca and low phosphorus result in softening of bone (osteomalacia). Such a condtiion is refered to Vito D-resistant Rickets or Idiopathic Osteomalacia. • Loss of amino acids occurs known as Amino-aciduria. All the three defects are Genetic Defects and are termed as Hypophostemic Glycosuric Rickets or De Toni-Fanconi Syndrome. MAGNB;IUM: Magnesium is always combined with Calcium and phosphorus (70%) of total contents == 21 gm) in the form of Bone Salts and 30% remains in soft-tissues and of body fluids. Mg++

activates many enzymes concerned in Phosphate Transfers. Mg. It is required for oxydative phosphorylation. Sources:

Co-c~rboxylase

enzyme contains

Milk, Eggs, Cabbage, Cauliflower and many fruits. Whole Blood

2-4 mg/100 ml

C.S.F.

2-3 mg/100 ml

Muscle

21 mg/100 gm

Normal Serum Mg

1-3 mg/100 ml.

Absorption: Absorption of Mg is vey poor. That is why, its salt MgS04 is used as pergative since it has poor absorption (50%). After ingestion it exerts pergative action by exerting osmotic diuresis. The portion which is not absorbed in the lumen exert a laxative action, since large amount of water from surrounding area enters in large intestine. Excretion: Two third of the total is excreted in the faces and the remaining one third in urine.

INORGANIC METABOLISM

473

Deficiency: 1. Mg deficiency causes depression, muscular weakenss, Serum Mg level is one mgl 100 ml. Extreme deficiency causes convulsions.

2. Deficiency is very prominent, in chronic alcoholism causes muscular weakenss. 3. In case of Kwashiorkar, low Mg causes muscular weakness (Fatigue). PHOSPHORUS Phosphorus is present in all food with the result deficiency is not observed. Phosphorus goes with Ca, therefore distribution of Ca and Phosphorus in food is very similar. Adequate intake of Ca is acompanied with adequate intake of Phosphorus. Human with Ca: P ratio is 2: 1. In the newborns, breast feeding is advised for many reasons. One of the reason is adequate supply of Ca and P (1.5: 1 ratio). Apart from its chief function of formation of bones and teeth, other functions are:

1. Formation of Phospholipids, Nucleic acid and phospho proteins. 2. It is involvd in the formation of organic phosphates such as hexose phosphate, triose phosphate and creatine phosphate.

3. It is requied for formation of ATP molecule. 4. It forms isozymes such as NADP, ADP, AMP etc.

5. It is required in the absorption of glucose by phosphorylation. Sources: Milk, Cheese, egg-yolk, meat, fish and nuts etc. Distribution of Phosphorus In Body Fluids and Tissues: Blood Serum (Inorganic)

40 mgldl

Children

4 - 7 mgldl

Adults Muscle

3 - 4.5 mgldl 170 - 250 mgl100 gm

Nerve Bones and Teeth

360 mgl100 gm 2200 mgl100 gm

Infants Children Adults Pregnancy &Lactation

250 - 400 mg 800 - 1200 mg 800 - 1200 mg 1200 mg

Blood Levels

3 - 4.5 mg 1100 ml in Adults

Dally Requirements:

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TEXT BOOK OF BIOCHEMISTRY

(Plasma)

4.5 - 6.5 mg/100 ml in Children.

• In rickets, serum phosphate level is low. • Phosphate retention causes the acidosis in severe renal disease. • Serum phosphorus levels are increased in hyper-parathyroidism. • In renal rickets, loss of Phosphorus and Ca occurs with increase alkaline phosphatase activity. (Secondary Parathroidism) SULPHUR(S)

Physiological Functions: 1. Sulphur is present in cell protein in the form of cysteine and methionine. 2. The cysteine is important in protein structure. 3. Methionine is the principal methyl group donor in the body. The activated form of methionine is S-adenosyl-methione. 4. Sulphur is a constituent of Co-Enzyme A and Lipoic Acid. 5. Sulphur is a component of other organic compounds such as heparin and glutathione. Sulphur intake is in the form of cysteine and methionine. Percentage of Sulphur present in blood in three forms viz.: 0.5 - 1.1 mg 0.1 - 1.0 mg 1.7 - 3.5 mg

Inorganic Sulphate Ethereal Sulphate Neutral Sulphur (In 100 ml of Blood)

Sulphate concentration is increased impairment of renal function, in glomerulonephrities and in uremic condition.

aaa

METABOLISM OF TRACE ELEMENTS IRON Iron is a component of many respiratory enzymes, Cytochromes, Hemoglobin, Catalase, Porphyrins etc. It is refered as Trace element because of its small contents. Hemoglobin

60 to 70%

Myoglobin

3%

Only 0.1% is carried in plasma in combination with l3-globulin. Transport protein is called as Transferrin. Physiological Functions:

1. It is a constituent of Hemoglobin and therefore its main function is to transport oxygen. 2. l3-globulin is a component of cytochrome enzyme; it takes part in cellular respiration. 3. It is a component of Hemoglobin, myoglobin, cytochrome oxidase, catalase and peroxidase. 4. The non-heme iron is protein bound. This form acts like storage. S. It forms a structural part of Xanthine oxidase, Succinate dehydrogenase and other enzymes. Sources: Rich Source: Non-Veg.: Liver, Heart, Kidney, Spleen, Egg-YOlk, Fish, Oysters, Clams. Veg.: Figs, Nuts, Dates, Beans, Spinach, Salad, Green Vegetables etc.

Poor Sources:

Milk, Wheat Flour, Polished Rice, Potatoes, Human Milk (0.3 to 0.6 ,ug/ml).

475

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Absorption: Traces of Cu are required for utilization of iron in Hemoglobin. Diet contains Iron in Ferric (Fe+++) and Ferrous (Fe++) form as Ferric Hydroxide. In the process of Absorption: Iron compound, by action of gastric hydrochloric acid is broken to Ferric (Fe+++) which are reduced by substances like Vit. C, Cysteine and converted to Ferrous (Fe++) , These are again converted to (Fe+++) in the further alimentary canal.

Mucosal Cells:

IFe+++ Combines with ~-Globulin I

I

This is referred to Apoferritin also called as Ferritin (23% of Iron)

!

Exist as Ferric Hydroxide [Fe(OH):J, Ferric Phosphate Ferritin - -•• Fe+++ Hemoglobin - -•• Fe++ Absorption mainly occurs through mucosal cells of the Stomach, duodenum and upper jejunum. Ten percent of the ingested Iron is only absorbed. Daily Requirement: Children:

1 to 3 years

15 mg

4 to 10 years

10 mg

11 to 18 years

18 mg

Adult Women During Menstrual Period

18 mg

,,16-32 mg

A supplement of 100 mg/day can suffice daily loss and overcome with daily requirement. The iron deficiency occurs as a result of malabsorption from GI tract. For proper iron metabolism, Copper deficiency should not exist. Iron in Blood: Iron in Blood

75 to 175 pg/100 ml

Dietary Iron is absorbed only 10% (usually it is less than 10%). Iron absorption in Children is more than in Adults, Absorption is much better in Ferrous State (Fe++) than in Ferric State (Fe+++).

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METABOLISM OF TRACE ELEMENTS

Factors Affecting Absorption:

1. Absorption of Iron occurs mainly in stomach and duodenum. 2. A diet, high in phosphates causes decreased absorption due to the formation of Fe3(P04)2 (Insoluble).

3. Phytic acid and oxalates interfere with absorption. 4. Vit. C increases absorption.

5. Gastric HCI favours the absorption. In Achlorhydria, absorption is nil. Copper deficiency affects iron absorption.

6. Alcohol ingestion favours the stimulation of gastric HCI secretion which favours iron absorption.

7. Proteins content in diet favours absorption. The iron binding protein, apoferritin in the mucosal cells is the controlling factor. Ferrous ions being oxidized to ferric ions combines with apoferritin to form iron containing protein called as ferritin. It is believed that absorption depends on the formation of ferritin. The maximum capacity of apoferritin to get saturated with iron is 10%, beyond this, no further uptake of iron could take place. Transport in the Plasma: All the iron released from the mucosal cell enters the portal blood in the ferrous state. In the plasma ferrous is oxidized to ferric state by ceruloplasmin (a copper binding plasma protein) exerts a catalytic activity. Human serum also contains a yellow cuproprotein (ferroxidas 11) which catalyses the oxidation of ferrous to ferric are then incorporated into a specific iron binding protein B1• Globulin Transferrin or siderophilin. This is a Glycoprotein (M.Wt. 76,000 daltons) containing 5.3% carbohydrate. Transferrin can bind 2 atoms ferric ions per molecule of protein and form red ferric protein complex. Total Iron Binding Capacity [lIBC]: It is the capacity of the protein

[B1.Globulin]

2Fe++ + 02 + 2C02 + Siderophillin TIBC

1.

.. 2Fe++ + 2C03

= 300 -

Diet: Fe(OH)3 (Ferric Hydroxide)

1 Intestinal Lumen Fe+++ (ic)

Vito C.

to bind with Fe++ and get saturated.

Fe++ (ous)

360 pg/dl.

-

Siderophillin

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TEXT BOOK OF BIOCHEMISTRY

2. Mucosal Cell: Fe++ is converted to Fe+++ (Stored as Apoferritin) 3. Plasma: Fe++ CeruloPlasmin. Fe +++ (ic) Present as Siderophillin or Transferrin Excretion: Only traces of Iron are excreted per day. However, hematuria in urine and loss of blood in stools following an infection amounts to loss of iron. Physiological loss in menstruation requires to be supplimented with iron therapy. During pregnancy iron requirement is more since iron is lost to fetus. Ferritin: It is stored in the form of ferritin and serves as large stores, whenever there is a sudden loss of iron due to bleeding. This is present not only in intestine but also in liver, spleen, and bone marrow. If more iron is administered parentarily exceeding the capacity of the body to store as ferritin, it accumulates in the liver as Hemosiderin in the form of colloidal iron oxide in association with protein. Iron content of Hemosiderin 35% by Weight Normal Hemoglobin content: Male (12 to 18 gm); Female (9-11 gm and above). Any value less than the basic level amounts to deficiency of Iron absorption. Nutritional deficiency may be due to other parasites, like thread worm, round worm, hook worms etc. Therefore after deworming the patient, Iron therapy is to be administered. Nutritional Disorders: 1. Siderosis: When excessive amounts of iron is released or with excessive intake beyond the capacity for its utilization, the excess is deposited in various tissues mainly in the liver. Etiology: Repeated blood transfusion, excessive intake or break-down of red cell. 2. Nutritional Siderosis: The disorder is found among Bantus in South Africa. These people use iron pots for cooking and consume food rich in Iron contents. 3. Hemo-chromatosis: This is rare disease in which large amounts of irons are deposited in all tissues, liver, pancreas, spleen and skin where patches of iron deposits are seen. Hepatic necrosis occurs with diabetes and pigmentation all over the body.

479

METABOLISM OF TRACE ELEMENTS

Iron Deficiency Anaemia: This is very common due to worm infection. Irregular monthly discharge and blood loss where Hb content are within the range of 5-9 gml100ml or less than 5 gm. Nutritional anaemia because of dietary deficiency of iron in diet causes a Microcytic Hypochromic Anaemia. Cells are smaller and having less colour index. The total hemoglobin is less. Effect of high intake (oral) Iron Therapy may cause constipation. Causes of Iron Deficiency: • Insufficient intake. • Inadequate absorption • Increase demand • Increased blood loss.

Summary of Iron Metabolism in Humans: Absorption: Site: Duodenum pH 5 - 6 (Acidic) Fe+++ (ic form) and Fe++ (ous form) 0.6 to 1.5 mg/day. Transport: Fe+++ + Transferrin to Bone Marrow TIBC: Total Iron Binding Capacity (Fe++ + 13 1 Globulin) Metabolism } And Bone Marrow

Erythropoesis under the control of Erythro-poetin Incorporation of Fe+++ with 131 Globulin (Siderophillin or Transferrin)

Storage: Hemoglobin, Storage of Fe (1000 mg) Catabolism: ABC destruction Hemorrhage and Hematuria ABC loss in urine Menstrual loss in Women Bacillary Dysentary (Blood loss in faces)

R.E. System (Aeticulo-endothalial) Spleen Liver, Bone Marrow

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COPPER [Cu]

The deficiency of Copper in diet causes a hepatic failure due to portal hypertension. If not corrected by constructing a porto-caval shunt causes liver cirrhosis. The deficiency also causes a brain necrosis and sclerosis of the corpus structures precipitating into basal ganglion syndrome in advanced age. Eye is affected and produces brown yellowish rings around the cornea. Renal reabsorption is defective. Physiological Function:

1. It participates in Hemoglobin synthesis, phospho-lipid synthesis, Collagen synthesis and in Melanin formation. 2. Cerebrocuprein, erythro-cuprein and hepato-cuprein contain Cu++ are present in brain, Red Blood Cell and in hepatocyes. 3. Cu-containing enzymes are amine oxidase, Super-oxide dismutase and Dopamine hydroxylase. Sources:

Non-Veg.

Liver, Kidney, Meat, Shell-fish.

Veg.

Nuts and dried Legumes.

Poor-Source

Milk and its products.

Distribution:

Human body

Contain 100-150 mg of Copper of 60 kg.

Muscle

64 mg of the total

Bone

23 mg of the total

Liver

18 mg of the total.

Daily Requirements:

Adults

: 2.5 mg

Infants and Children : 0.05 mg/kg body wt. A nutritional deficiency of copper !'las never been demonstrated in Man. Copper Level of Blood:

90-95 pg/100 ml of blood 80% of this is present as superoxide-dismutase (Erythrocuprein) Copper in plasma occurs in two forms: The firmly bound form consist of Ceruloplasmin. While the loosely bound is known as "Direct reacting" copper and is loosely bound to Albumin. Plasma copper levels increase in pregnancy because of their estrogen content. Oral contraceptives have a similar effect.

METABOLISM OF TRACE ELEMENTS

481

Absorption:

30% from Human Duodenum Excretion:

Urine

10 to 60 pg Copper/within 24 hrs.

Biliary

0.5 to 1.3 mg via stools.

Effect of Copper Deficiency:

1. Although iron is not disturbed, the release of iron into plasma is prevented due to decreased synthesis of ceruloplasmin with the result hypoferrima occurs, precipitating into decreased synthesis of heme developing anaemia in severe deficiency of copper. 2. Experimentat animals on copper deficient diet loose weight and die. 3. Copper deficiency produces osteoporosis and fractures. 4. Copper containing enzyme plays an important role in the connective tissue metabolism ( Elastin and Collagen formation). Ceruloplasmin:

It is the plasma protein bound to copper with molecular weight of 1,51,000. It contains about 8 atoms of copper per molecule. Normal plasma contains 30 mg of this protein/100 ml. It functions as ferroxidase enzyt'Tle during Iron transport. Superoxide Dismutase:

1. This is an Enzyme which catalytically scavenges the toxic free radical superoxide ion (02") formed during aerobic metabolism. 2. Its molecular weight is about 32000 and consists of two identical subunits. 3. It contains one Cu++ and one Zn++ per unit. Erythrocuprein in RBC, Hepatocuprein in Liver, Cerebrocuprein in Brain are identical with the enzyme. Wilson's Disease (Hepato-Lenticular Degeneration):

This is associated with abnormalities in the metabolism of copper. In this disease, the liver and the lenticular nucleus of the brain contain abnormally large amounts of copper. Urinary excretion increases and plasma copper levels and ceruloplasmin levels are low. A generalized aminoaciduria occurs. Almost all patients with Wilson's disease have less than 23 mg of ceruloplasmin per dl. The total serum copper level in these patients may appear to be normal or slightly decreased. Excessive copper absorption from intestine and inadequate excretion of copper via intestine may be the factor for genesis of Wilson's Disease.

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IODINE Basic Function of Iodine: It is required for the formation of Thyroxine and Tri-iodothyroxine Hormone. These hormones are required for cellular oxidation, growth, reproduction and for the activity of the central autonomic nervous system. Tri-iodothyroxine is more active than thyroxine in many respects.

Important Source: Water and salt is the main source. Use of Iodized salt prevent all the disorder of thyroid. 100-150 pg required/per day.

Total Iodine Contents of the Body: 10 to 20 mg (Total Iodine). 70-80% of this is present in thyroid gland. Rest of the iodine is present in muscle, salivary glands, overies and pituitary, gland.

Plasma Iodine Level: 4 to 8 pgl1 00 ml. 0.08 to 60 pg/100 ml Inorganic form and rest is organic form which is bound to protein. 90% of protein-bound is present in Thyroxine.

Absorption: Through small intestine as Di-iodothyroxine in the form of thyroxine.

Storage: 90% of Iodine is stored in Thyroid gland as Thyroglobulin in the form of Thyroxine, diiodo and tri-iodo thyroxine. On demand, these forms are mobilized.

Simple Endemic or Colloidal Goiter: A goiter is the enlargement of the gland due to proliferation of cells. These may be accompanied by more secretion of hormone or may not show hyper secretion. In the latter case, it is regarded as Non~toxic proliferation and this goiter is refered to as Inocent Goiter. Excessive proliferation (hypo) with low secretion may induce symptoms of Hypoparathyroidism. This may be caused by inadequate supply of iodine in the diet. The decreased production of thyroid hormone causes overstimulation of thyroid gland because of increased pituitary thyrotropin production incident to the lack of breaking effect of Thyroid Hormone. Iodine supplement with colloidal iodine or with sodium iodide should be adequate for simple Goiter.

METABOLISM OF TRACE ELEMENTS

483

Hyperthyroid States: Hyper secretion of the proliferated cell may occur and precipitate into a toxic secretion. Either the cells proliferate and the goiter is formed or without proliferation, hyper secretion occurs. Any type of hyper secretion exerts its toxic effects of hyperthyroidism as Exopthalmic Goitre (Patients have bulging eyes [Graves Disease]). The enlargement of Thyroid may be diffuse or nodular. Symptoms include nervousness, loss of weight, high body temperature with excessive sweating and all this occurs with Tachicardia induced with Thyroxine production. CHROMIUM [Cr] Important Physiological Functions: 1. Chromium trigers the action of Insulin in the utilization of glucose in body both in animals and in human being suffering from diabetes mellitus. 2. In animal, cholesterol metabolism is controlled. Sources: Freely available in dietary food. Chromium content of the human body is estimated to be 6 mg. Widely present in almost all tissues. Chromium Blood Level: 0.0009 to 0.055 part per million. Requirements: Not mentioned. Advocated in Diabetes Mellitus. Excretion: Mainly in the Urine. Toxicity: High intake of chromium may produce allergy reaction like spasms in circulation precipitating in ischemia of Brain and thereby producing paralysis (TIA - Transient Ischemic Attack). Excessive intake may produce high B.P. However its deficiency causes impairment of carbohydrate tolerance. MANGANESE [Mn] Biological Functions: Mn++ is essential for maintenance of bone structure, reproduction and for normal CNS function. Mn++ is firmly bound to pyruvate carboxylase and superoxide dismutase and inhibit Lipid Peroxidation. Arginase requires Mn++ ion for its activity. Many enzyme reactions in the synthesis of mucopolysaccharides are catalysed by Mn (Cartilage and Prothrombin). It acts like a co-factor Glucose-6-phosphate dehydrogenase.

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Sources: Nut, Whole Grains, Vegetables, Fruits. Distribution: Normal Adult (all over body): 12 - 20 mg. Daily Requirements: 2.5 to 7.0 mg/day. Normal Blood Level: 4 - 20 jJg /100 ml bound with /31-Globulin. Deficiency: Causes Ataxia in animal. Deficiency is not observed in human beings. ZINC [Zn] Zinc is very important, essential constituent of the body metabolism and enzyme preparation such as Carbonic anhydrase, Alkaline phosphatase, Pancreatic carboxy peptidase and of Superoxide dismutase. It is required for the preparation of insulin and insulin action. Zinc is used up in /3-cells of islet of pancreas to store and release insulin when required. The retina contains Zn-metal oenzyme retinene reductase. It helps in maintaining normal concentration of Vit. A in plasma by mobilizing Vit. A from Liver. Besides the rate of wound healing is promoted by Zinc. Sources: Non-veg.

Oysters, Shell-fish, Eggs, Liver, Meat etc.

Veg.

Cereals, pulses, Vegetables, Fruits.

Distribution: Whole body wt. 70 Kg contains 1.4 to 2.3 gm of Zn. 20% of this is present in skin. Human Blood

0.8 mg/100 ml

Plasma

: 0.12 mg/100 ml

R.B.C.

: 1.44 mglWhole Blood.

Concentration falls by 10% in pregnancy and in patients on oral concentraceptives. Requirements: Adults

15 mglday

Breast-fed

0.7 - 5.0 mg/day

New-Born Infants

3 - 5 mg/day

Pregnancy and Lactation

30 mg

METABOLISM OF TRACE ELEMENTS

485

Absorption:

1. Endogenous Zinc is secreted into small intestine in the pancreatic juice. 2. 90% of Zinc intake is lost in faces, rest 5% lost in Urine, 5% retained in the body. Deficiency of Zinc:

1. Zinc deficiency causes dwarfism and hypogonadism (Retarded Genital development) . 2. Zinc deficiency causes anaemia and hepatospleenomegaly. 3. Zinc deficiency produces Zn-incorporation in Insulin synthesis and thus insulin production is reduced precipitating into diabetes mellitus. 4. Zinc contents in Leucocytes is reduced in Leukemias. 5. In acute myocardial infarction Zn levels are decreased. 6. In cirrhosis of Liver, levels are subnormal. 7. Atherosclerotic plaque formation is reduced by Zn therapy. tl. Zn deficiency can produce skin lesions.

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FLUORINE [F]: Physiological Functions: Fluoride in trace quantities are responsible for the mottled tooth formation. Fluoride ions kill the bacteria and thereby stops the growth and development of bacteria. This prevents dental caries. Sodium Fluoride (NaF) is an inhibitor of Enolase enzyme. It is used as a therapeutic agent along with Vit. D for the treatment of osteoporosis. It forms a protective layer which is acid resistant and does not allow the enamel wasting.

Source: Drinking Water.

Daily Requirement: One to two parts per million (1-2 ppm).

Distribution: Bones, teeth and kidney and in extracellular fluid. Effect of Excessive Intake: Dental Fluorosis: 3 to 5 ppm intake in childhood causes Dental Fluorosis [Mottled Enamel]. The enamale of the teeth is worned out and becomes rough. White patches with yellow or brown stains are seen on the surface of teeth. The enamel becomes soft and is worn out.

Excessive high intake of 10 ppm results in increased density, hyper calcification of bone of spine, pelvis and limbs. There is a overall calcification even in the collagene of bone precipitating in neurological disturbances. Such individuals are crippled with loss of normal activities like stiff joints. Fluorosis could be prevented by removing fluorides from water with activated carbon which adsorbs fluorides.

MOLYBDENUM [Mo] Xanthine oxidase, aldehyde oxidase and sulphite oxidase contain molybdenum as their component. Molybdenum is also a component nitrate reductase which is utilized for nitrogen fixation in micro-organism. The level of xanthine oxidase is maintained by molybdenum.

Daily Requirements: Not mentioned since it is present in diet. Most of the absorbed molybdenum is excreted out. Toxicity of this, depend upon the allergic reaction to individual animal as severe diarrhea, loss of weight etc.

METABOLISM OF TRACE ELEMENTS

487

SELENIUM [Se] Not established to be essential for human being although required for normal growth and for fertility in animals. Catalyses the peroxidase enzyme and prevents the accumulation of Hydrogen peroxidation. It is required for immune mechanism. It is required for reductive deamination of glycine.

Sources: Widely distributed. Present in all food stuffs.

Daily Requirement: Not known.

Deficiency Observed in Human Being: 1. Keshan Disease: Involves an acute ECG changes and irregularities. Advocating Selenium suppliment is highly effective. 2. Kaschinbeck's Disease: It retards the growth of children [5 to 15 years]. Fingers are shortened. Enlargement of bones occurs. Dysfunction of joints occurs.

Incidental Occurrence: In Kwashiorkor children show decreased selenium level. Administration of selenium stimulates the growth. In GI of cancer, selenium levels are low. Cardiovascular disorder occurs in selenium low levels. Thrombosis is caused in low intake of selenium.

COBALT [Co] Cobalt is an essential component of Cyanocobalamine. This is required for erythrocyte formation. Besides, enzymes such as methyl-malonyl CoA mutase, methyl-tetrahydrofolate oxidoreductase, homocysteine methyltrans-ferase and ribonucleotide reductase require Vit. B12 for activity.

Sources: If is abundently available in all types of food material. e.g. milk, bone marrow.

Distribution: It is distributed widely in all tissues. The total body content of Cobalt is about 1.1 mg. Kidney and Liver are rich in cobalt contents. Vit. B12 is rich source.

Requirement: It is required as Vit. B12. 1 to 2 pg of Vit. B12 containing 0.045 to 0.09 pg of Cobalt is sufficient to maintain normal bone marrow function in pernicious anaemia.

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TEXT BOOK OF BIOCHEMISTRY

Absorption: It is readily absorbed from small intestine (70 to 80%). Cobalt salt administered is poorly utilized and eliminated in the faces.

Excretion: Via Urine 60 to 65% of the amount ingested is excreted in Urine.

Toxicity: Cobalt produces increased RBC production known as Polycythemia.

QUESTIONS 1. The electrolyte and water balance is regulated by (A) Aldosterone

(8) Antidiuretic hormone

(C) Renin-angiotensin

(D) All of the above

2. Electrolytes can be identified using (A) Emission spectrophotometry

(8) Electrophoresis

(C) Gel chromatography

(D) Ultracentrifugation

3. Sodium reabsorption in the renal tubule is increased by the hormone (A) Renin

(8) Cortisol

(C) Antidirutic hormone

(D) Aldosterone

4. Which of the body compartment contains water as major constituent? (A) Plasma

(8) Extracellular fluid

(C) Intracellular fluid

(D) Interstitial fluid

5. Intracellular compartment contains percentage of total body water as (A) 45 to 55

(8) 55 to 65

(C) 65 to 75

(D) 75 to 85

6. Calcium is required for the activation of the enzyme (A) Isocitrate dehydrogenase

(8) fumarase

(C) Succinate thiokinase

(D) ATPase

7. Osmotic pressure of plasma is primarily due to (A) Proteins

(8) Chloride

(C) Sodium

(D) Glucose

8. One of the functions not performed by water is (A) Participation in biochemical reactions (8) Regulation of body temperature (C) Generation of ATP

(D) Transportation of solute

489

METABOLISM OF TRACE ELEMENTS

9. Urinary water loss is increased in (A) Diabetes mellitus

(8) Diabetes insipidus

(C) Chronic glomerulonephritis

(D) All of the above

10. The principal extracellular cation and intracellular cations are (A) Na and K

(8)

K4

and Na4

(C) Ca4 and Na4

(D)

K4

and Ca4

11. Urinary water loss is increased in (A) Diabetes mellitus

(8) Diabetes insipidus

(C) Chronic glomerulonephritis

(D) All of the above

12. The symptom of water intoxication (A) Muscular weakness

(8) Anemia

(C) Paralysis

(D) Fever

13. The highest concentration to proteins present in (A) Plasma

(8) Cerebrospinal fluid

(C) ICF

(D) ECF

14. Which one of the following constituents of food generates highest amount of metabolic water? (A) Carbohydrates

(8) Fats

(C) Proteins

(D) Vitamins

15. The concentration of serum calcium may drop below 7mg/l00ml in (A) Hyperparathyroidism

(8) Hypoparathyroiism

(C) Tetany

(D) Rickets.

16. Oncotic pressure of plasma is about (A) 10mm of Hg

(8) 15mm of Hg

(C) 25 mm of Hg

(D) 50 mm of Hg

17. The total cations in meq equals that of total anions in (A) Blood plasma

(8) Gastric secretion

(C) Pancreatic secretion

(D) Intestinal secretion

18. The hormone controlling water excretion by the kidney is (A) Renin

(8) 24,25 DHCC

(C) Angiotensin II

(D) ADH

19. The daily intake and output of water through different sources in ml (A) 2500

(8) 2700

(C) 2800

(D) 3000.

20. A mixture of 213 isotonic saline solution and 1/3 lactate solution should be administered intravenously in case of (A) Constipation

(8) Prolonged diarrhea

(C) Malaria

(D) Jaundice

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TEXT BOOK OF BIOCHEMISTRY

21. Hemoglobin formation needs both (A) Iron and zinc

(8) Iron and calcium

(C) Iron and copper

(D) Iron and magnesium

22. Dehydration may be ordinarily corrected by parenteral ingestion of the solution of (A) Sodium bicarbonate

(8) Magnesium chloride

(C) Calcium chloride

(D) Sodium chloride

23. The normal concentration of serum K and serum Na respectively are about (A) 5 meq/I and 142 meqJI

(8) 2 meqll and 10 meqll

(C) 142 meqll and 10 meqll

(D) 10 meqll and 142 meqll

24. Excess of aldostorone causes (A) Oedema

(8) Noctruria

(C) Hyperkalaemia

(D) Hypotension

25. The percent of plasma in the extracellular fluid (A) 50%

(8) 65%

(C) 14.2%

(D) 4.5%

26. The distribution of body water in interstitial tissue fluid and in plasma intravascular fluid in an adult of 70 kg approximately is (A) (15%) 11 Land (5%) 31

(8) (50%) 351 and (20%) 141

(C) (50%) 351 and (5%) 31

(D) (15%) 111 and (20%) 141

27. The regulatory mechanism of body water is influenced by the hormone (A) Oxytocin

(8) ACTH

(C) FSH

(D) Epinephrine.

28. All chemical reactions in the body proceed in presence of (A) Organic salts (8) Inorganic salts

(C) Water

(D) Alkali.

29. Total body water measurement can be determined by using (A) Antipyrine

(8) Mannitol

(C) Insulin

(D) Evans blue dye

30. Zinc is a constituent of (A) Carbonic anhydrase

(8) Malate dehydrogenase

(C) Aldolase

(D) Amkylase

31. The amount of water excreted per day in feces in Normals (ml) (A) 90

(8) 95

(C) 100

(D) 105

32. The percentage of calcium excreted in the feces. (A) 40 to 60

(8) 50 to 70

(C) 60 to 80

33. The types of solutes in body fluids are mainly of (A) Small molecular size organic compounds (8) Large molecular size organic compounds (C) Inorganic electrolytes (D) All of the above

(D) 70 to 90.

491

METABOLISM OF TRACE ELEMENTS

34. The regulatory mechanism of body water is influenced by the hormone (A) Oxytocin

(B) ACTH

(C) FSH

(D) Epinephrine

(C) Niacin

(D) Biotin.

35. Cobalt is a constiuent of (A) Folci acid

(B) Vitamin 8 12

36. The daily loss of calcium in mg. in sweat is about (A) 12

(B) 13

(C) 14

(D) 15

37. Serum phosphate concentration is 1 to 2 mg/100 ml. In (A) Rickets

(B) Tetany

(C) Osteoporosis

(D) Hyperthyroidism

38. Organic compounds of small molecular size. (A) Urea

(B) Uric acid

(C) Creatinine

(D) Phosphates.

39. Transcellular fluid in percent of extracellular fluid is (A) 1.2

(8) 1.5

(C) 4.5

(D) 14.3

40. Dehydration may be ordinarily corrected by parenteral ingestion of the solution of (A) ZnCI2 (B) MgCI2 (C) CaCI2 41. Intracellular fluid contains the percent of the total body weight (A) 45

(B) 50

(C) 55

(D) NaCI

(D) 60

42. The percent of plasma in the extracellular fluid. (A) 3.5

(B) 3.8

(C) 4.2

(D) 4.5

43. Transcellular fluid in percent of extracellular fluid (A) 1.4

(B) 1.5

(C) 1.6

(D) 1.8

44. Organic substances of large moleculare size (A) Starch

(B) Inulin

(C) Lipids

(D) Proteins

45. 100 grams of fat on combustion produces water in ml. (A) 107

(B) 105

(C) 102

(D) 98

(C) Vitamin D

(D) Vitamin B12

46. Calcium absorption is interfered by (A) Fatty acids

(B) Amino acids

47. The absorption of calcium is increased by the dietary higher levels of (A) Fats

(B) Proteins

(C) Cereals

(D) Vitamin A

48. Elements required to be present in diet in amounts more than 1mg. Are called (A) Macroelements

(B) Microelements

(C) Semimicroelements

(D) None of the above

49. The number of principal mineral elements are (A) 5

(B) 6

(C) 7

(D) 8

50. There is virtually no calcium in Erythrocytes. 51. Calcium exists in the plasma in Ca++ Prot. Calcium, Ca- citrate forms.

492

TEXT BOOK OF BIOCHEMISTRY

52. Calcium absorption is interfered by (8) Phytic acid

(C) Oxadic acid

(8) Fatty acids

(0) All the three

53. Decreased ionized fraction of serum calcium causes Tetany. 54. Deficiency of cobalt results in (A) Anemia

(8) Diabetes

(C) Headache

(0) Cataract

55. Phytic acid which occurs in cereal grains forms insoluble salts Phytin with calcium and magnetisium resulting in the impaired absorption of calcium. 56. Which one of the following is not a sulphur containing amino acid?

(0) Methionine

(8) Valine

(C) Cystine

(D) Cysteine

57. Vitamin 0 in ordinary doses does not relieve renal rickets. Hence, it is sometimes refered to as vitamin D-resistant rikets. 58. Which of the following plays dominant role in maintaining the normal osmotic pressure of the different body fluids? (A) Na±

(8) K+

(C) Ct-

(0) All of he above

59. High calcium diet and phytic acid Decrease phosphorus absorption. 60. The reabsorption of phosphorus is inhibited by Parathyroid hormone. 61. Calcium is required for the activation of the enzyme (A) Isocitrate dehydrogenase

(8) ATPase

(C) Furmarase

(0) Succinate thiokinase

62. Magnesium is the principal cation of the soft tissue. 63. Sodium and potassium are the main (A) Intracellular cations (8) Extracellular cations (C) Intracellular and extracellular cations respectively (D) Extracellular and intracellular cations respectively 64. Co-carboxylase is provided with magnesium. Which of the following element is required for the development of erythrocytes? (A) Calcium

(8) Magnesium

65. In uremia the serum magnesium

lev~

(C) Iron

(D) Potassium

is Low.

66. Wilson's disease is associated with the abnormal metabolism of (A) Iron

(8) Potassium

(C) Iodine

(D) Copper

67. In the absorpion of glucose and galactose Sodium ion plays an important role. 68. Zinc is a constituent of (A) Aldolase

(8) Amylase

(C) Melate dehydrogenase

(D) Carbonic anhydrase

69. Aldosterone increases plasma sodium level. 70. The volume of CSF in a normal adult is (A) 30-50ml

(8) 100-150ml

(C) 180-200ml

(D) 250-300ml

493

METABOLISM OF TRACE ELEMENTS

71. Protein boisynhesis by ribosomes requires Potassium. 72. Oxidases are conjugated proteins having the prosthetic group (A) Mg

(B) Mn

(C) Cu

(0) Fe

73. In man, erythrocytes contains Little or No sodium. 74: The normal range of plasma calcium is (A) 3-S mg/dl

(B) 9-11mg/dl

(C) 5-10mg/dl

(0) 11-1Smg/1

7S. Prolonged hypokalemia causes injury to Myocardium and Kidneys. 76. One of the following condition may result in titany (A) Hypercalcaemia

(B) Hypocalcaemia

(C) Alkalosis

d) Hypocalcaemia and alkalosis

77. Chloride ion is important as an activator of Amylase. 78. The metabolism of sodium is regulated by Adrenocortical steroids. 79. Absorption of diatery calcium occurs by one of the following processes. (A)

Active uptake

(C) Endocytosis

(B) Simple diffusion (0) Facilitated diffusion

80. Sodium concentration in sweat is decreased by Aldosterone. 81. Inhibitor of intestinal absorpion of calcium is (A) Phytate

(B) Proteins

(C) Phosphate

(0) Lactose

82. Hypernatremia occurs in prolonged treatment of Cortisone and ACTII as well as Sex hormones. 83. The daily calcium requirement of an adult man is about (A) 600 mg

(B) 800 mg

(C) 1,200 mg

(0) 100 mg

84. Most of the ion in food occur in the Ferric State. 8S. The average quantity of total calcium in the healthy man is about (A) 100gm

(B) 500gm

(C) 1 kg

(0) 5 kg

86. Hypokalemia is exhibited in heart failure treatment with digitalis. 87. The following element is found in the trace amount in human beings (A) Iodine

(B) Zinc

(C) Iron

(0) Cobalt

88. One of the following functions is not performed by the calcium in the body (A) Muscle contraction

(B) Bone formation

(C) Enzyme activation

(0) Coenzyme activity

89. Iron absorption is enhanced by proteins of Low molecular weight digestive products forming Iron chelate. 90. The continuous supply of calcium is provided to the body in the dynamic state by (A) Bone

(B) Liver

(C) Skeletal muscle

(0) Kidney

91. In case of Kwashiorkor the serum magnesium level is low causing weakness due to the absorption of magnesium.

494

TEXT BOOK OF BIOCHEMISTRY

92. Intestinal absorption of calcium is inhibited by (A) Oxalate

(8) Dietory fiber

(C) Free fatty acids

(D) All of the above

93. Parathyroid hormone Increases the absorption of magnesium. 94. Zinc absorption from instestine is inhibited by (A) Calcium

(8) Phylate

(C) Cadmium

(D) All of the above

95. Hypercalcaemia can occur in all the following EXCEPT (A) Hyperparathyroidism

(8) Hypervitaminosis D

(C) Milk alkali syndrome

(D) Nephrotic synrome

96. Excessive consumption of NaCI causes Edema in protein deficiency. 97. Hypocalcaemia can occur in all of the following EXCEPT (A) Rickets

(8) Osteomalacia

(C) Hyperparthyroldism

(D) Malabsorption syndrome

98. In certain stages of pregnancy, the steroid hormones cause the retention of Sodium as well as water which results in gain in weight 99. Iron is absorbed from (A) Stomach

(8) Deodenum and jejunum

(C) Lleum

(D) Caecum

100. Iron is stored in the form of (A) Ferritin and tra •• ~ferring

(8) Transferrin and haermosodrin

(C) Haemoglobin and myoglobin

(D) Ferritin and haemoslderin

101. Copper is the essential component of the following enzymes EXCEPT (A) Catalase

(8) Superoxide dismutase

(C) Uricase

(D) Transfrerase

102. Iron is transported in blood in the form of (A) Ferritin

(8) Haemosiderin

(C) Transferrin

(D) Haemoglobin

103. Iron deficiency results in one of the following disorder (A) Hemolytic anemia

(8) Pernicious anemia

(C) Microcytic anemia

(D) Megaloblastic anemia

104. Zinc is cofactor for the following enzyme (A) Aldolase

(8) Amylase

(C) Succinate dhydrogenase

(D) Cabonic anhydrase

105. Copper is essential for the synthesiS of (A) Hemoglobin

(8) Collagen

(C) Hepato cuprein

(D) All of the above

495

METABOLISM OF TRACE ELEMENTS

106. All of the following statements about Wilson's disease are correct EXCEPT (A) It is a genetic disease

(B) It involves copper dependent ATPase

(C) Copper is deposited in liver

(D) Plasma copper level is increased In It

107. The defective absorption of copper is observed in (A) Wilson's disease

(B) Goiter

(C) Menke's disease

(D) Hemochromatosis

108. One of following enzyme needs zinc as a cofactor (A) Alanin transferase

(B) Alkaline phosphates

(C) Amylase

(D) Lipase

109. Zinc is an essential component of the following enzymes EXCEPT (A) Carbonic anhydrase

(B) Carboxypeptidase

(C) Alkaline phosphatase

(D) Tyrosinase

110. Which hormone is stored and released by the element zinc? (C) Histamin

(B) Epinephrine

(C) PTH

(D) Insulin

111. Delay in healing of wounds may occur due to the deficiency of (A) Selenium

(B) Zinc

(C) Chromium

(D) Copper

112. Copper is necessary for the biosynthesis of the following EXCEPT (A) Hemoglobin

(B) Ceruoplasmin

(C) Collagen

(D) Ferrittin

113. Deficiency of one of the following can lead to hypochromic microcytic anaemia. (A) Zinc

(B) Copper

(C) Manganese

(D) Selenium

(C) Thyroid gland

(D) Salivary gland

114. Most of the body's iodine is present in (A) Liver

(B) Kidney

115. Wilson's disease is characterized by following . EXCEPT (A) Deposition of copper in liver, kidney and brain. (B) Low serum levels of copper and ceruloplsmin (C) Increased exceration of amino acids and glucose into urine. (D) Plasma copper level Is Increased In it.

QQQ

PLASMA PROTEINS

Whole Blood -

Cells = Plasma

Whole Blood -

Clot

= Serum

Distribution of Plasma Proteins % of Total Protein

Concentration (grn/100 ml) 6

~

8 gm %

Albumin

50

60

4

~

5 gm/100 ml

Pre-albumin

0.60

Globulins

40

50

0.1 ~m /100 ml 2 ~ 3 gm/100 ml

Alpha l ( 10: Abnormal < 0: Probable Lab or Calculation Error Creatinine Clearance

CrCI Male

=

(140-age)x(wt in kg.) (SCn) x (72)

CrCI Female = 0.85 x (CrCI male) Note: This estimate is useful only If serum creatine is not changing rapidly.

QQQ

CHAPTER ON VIVA VOICE

CARBODYDRATES (CHEMISTRY): 1. Why carbohydrates are called as carbohydrates? 2. What is the biological importance of mono, di and polysaccharides? 3. Give the examples of these compounds. 4. What is metabolism, anabolism, catabolism? 5. Importance of carbohydrates. 6. Classify carbohydrates, example of monosaccharide. 7. Which is non-reducing sugar? 8. Distinguish lactose/maltose? 9. Sterioisomerism, Mutarotation. 10. Importance of polysaccharides with example. 11. Importance of mucopolysaccharides. 12. Simplest test for carbohydrates(Molish). 13. How many calories of carbohydrates for utilization of 1gm outside and inside the body? 14. Example of polysaccharides. 15. Role of oligosaccharides in cell receptor sites? CARBOHYDRATES (METABOLISM): 1. Natural occurrence. 2. Salivary digestion of CHO, does it occur? 3. Intestinal digestion with the enzymes. 4. What is the pH at which digestion occurs? 619

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TEXT BOOK OF BIOCHEMISTRY

5. Enzymes of lactose, maltose, sucrose digestion? 6. How Does glucose absorption occur? In what form? 7. How does pentose absorbed? 8. Role of liver in carbohydrate metabolism. 9. Explain glycolysis, glycogensis, glycogenolysis. 10. Hormonal control of glycogenesis and glycogenolysis. 11. Rapoport leubering cycle and significance. 12. Glucose-alanine cycle 13. How many pyruvic acid are formed from one glucose? 14. Energetics of glycolysis 15. Process of activation before entry in TCA, explain TCA. 16. What is substrate level phosphorylation in TCA and how many high energy bonds are liberated? 17. Coris cycle? site? 18. Coenzymes involved in pyruvate dehydrogenase complex 19. Site of TCA 20. How many high energy bonds are liberated by utilization of one glucose? 21. Alternate pathway for glucose breakdown. 22. Coenzymes of HMP shunt. 23. Products, energetiCS, significance of HMP shunt. 24. To what extent is HMP shunt operable? 25. Inorganic ions needed in HMP shunt? 26. How is lactose formed and incorporated in milk in lactating women? 27. Fructosuria, lactosuria, maltosuria. 28. Renal sugar threshold. 29. Tubular reabsorption capacity (TMG) for glucose. 30. Essential pentosuria? 31. Link between HMP and uronic acid pathway? 32. By performing only one test, distinguish diabetes mellitus and insipidus. 33. Effects of hypoglycemia. 34. Normal blood sugar level? 35. Fasting blood sugar level, post Lunch level (pp). 36. Glucose tolerance test (GTC) or GTI. 37. Various control of blood glucose level?

CHAPTER ON VIVA VOICE

38. What is mild hyperglycemic curve? 39. Significance of GTC. 40. Differentiate between mild, moderate,severe curves 41. What are oral anti-diabetic drugs and their action? 42. (a) Explain how insulin act? (b) What are plasma receptor? (c) What are insulin Antibodies? (d) What is further fate of insulin? (e) Why insulin resistance is increased in later stage of disease? 43. Resistance of body to insulin administration? 44. Types of insulin used. 45. Can the body live without carbohydrate use? 46. Calorific aspects of living cells. 47. How 02 utilization is reduced in severe diabetes? 48. Complications of uncontrolled diabetes mellitus? 49. How is fat metabolism affected in uncontrolled OM? • 50. Glycosylated Hb? Describe significance of glucose incorporation in Hb? 51. Significance of c-AMP, control in carbohydrate and fat metabolism? 52. What is transient hyperglycaemia? 53. How excess carbohydrate use leads to cholesterol synthesis? 54. What is athero-sclerosis?

LIPID CHEMISTRY: 1. What is true lipid? 2. How do you identify fats from other petroleum products like motor oil? 3. Sio importance of fat, fatty

acid~?

4. Classify fatty acids. 5. Sio importance of PUFA. 6. Different methods of characterization of fatty acids. 7. How do you identify saturated and unsaturated FA? 8. Importance of sphingomyelins, phospholipids. 9. Specific dynamic action of fat. 10. Calorific value of fat. 11. Which are essential FA and describe their role?

621

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TEXT BOOK OF BIOCHEMISTRY

12. Classify prostaglandin and their importance. 13. Importance of PUFA in relation to prostaglandin formation. 14. Technique of TLC can be applied to separation of phospholipids. How? 15. Importance of phospholipids in membrane transport? 16. Which nucleus is present in sphingomyelins?

LIPID METABOLISM: 1. Normal occurance. 2. Digestion and absorption 3. Different absorption theories. 4. Types of lipases and their different sites. 5. Control of cholesterol metabolism; CHO control. 6. Effect of dietary cholesterol on cholesterol formation. 7. Normal levels of: Total cholesterol, free and esterified. 8. Factors controlling cholesterol level. 9. Tg metabolism. 10. What are fat parameters in chylomicrons? 11. Role of essential FA: phospholipids. 12. Factors controlling HMG - COA reductase. 13. Role of lipo/apo proteins in lipid transport 14. Composition of HDL, LDL and their significance. 15. How HDL to LDL ratio is protective of cardiac infarct 16. What is good cholesterol and bad cholesterol? 17. Role of cholic acid and its formation. 18. Endocrine function of chlesterol. 19. Utilization of cholesterol in male/female sex hormone? 20. How hormones control pathogensis of sclerosis in arteries? 21. Catabolic pathways and products of FA oxidation. 22. How oxidation of unsaturated FA controls cholesterol level? 23. Pg formation, types of pg-Prostaglandins and their effects. 24. Types of Leukotrienes. 25. vasoconstritive/dilatatory effect of Prostaglandins. 26. Site of j3-oxidation? Role of carnitine? 27. Transport of different FA in mitochondria

CHAPTER ON VIVA VOICE

623

28. Palmitic acid oxidation forms how many ATP? 29. What is Fatty liver? and how is it prevented? 30. What are lipotropic factors? 31. What is ketosis, ketogensis? Control of ketogensis. 32. How fatty liver leads to cirrhosis? 33. Etiology of acidosis in diabetes mellitus. 34. Adipose tissue metabolism. 35. How disturbance in CHO metabolic affects fat utilization? 36. What is alarming state of FFA value in order to avoid infarct? 37. Why fish liver oil has been given to people after the age 40? 38. Methods to avoid obesity. 39. Inbom errors of cholesterol. 40. Cholesterol transport. 41. Principal organs of synthesis. 42. In what subcellular part is the pathway of denovosynnthesis of fatty acids located? 43. Peculiarity of all enzymes that catalyses sequence of reactions in FA form? 44. Why FA synthase complex is only active as dimmer? 45. Sources of the 2 sulphydryl groups present in proximity in FA synthase complex? 46. What is ACP, importance? 47. Which is rate limiting reaction in pathway of denovo formation?

PROTEIN CHEMISTRY: 1. Biological importance of proteins. 2. Why are proteins so called as protein. 3. Proteins are composed of what? 4. What are amino acids? 5. Classify amino acids? 6. Which are acidic, basic, neutral aminoacids? 7. What is:- Zwitter ion, Isoelectric pH 8. Why casein is precipitated at pH

= 4.6?

9. How do you separate and identify amino acids? 10. What is an lsoionic point? 11. What is primary. secondary, tertiary structure of protein? 12. How do you classify proteins tertiary and Quartemary?

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TEXT BOOK OF BIOCHEMISTRY

13. What bonds are found in tertiary structure? 14. What is denaturation? What happens to the structure? 15. Which proteins undergoes denaturation? 16. What are fibrous, globular proteins? 17. Methods to separate plasma proteins? 18. Principle of protein analysis (elecrophoresis). 19. Types of electrophoresis. 20. How do you identify proteins after separation? 21. Gel electrophoresis and its Applications. 22. Functions of plasma proteins.

23. Essential amino acids. 24. Calorific value of proteins. 25. How proteins are stored in the body? 26. Specific dynamic action of protein?

PROTEIN METABOLISM: 1. Digestion of protein by pepsin and frypsin. 2. Optimum pH for digestion in stomach.

3. Autocatalysis of enzyme? (pepsin) 4. Different phases of HCI secretion? 5. Role of pancreas in protein digestion. 6. Hormones of GIT (Gastro intestinal track) with their role. 7. Deamination and types? 8. Transamination. 9. Glucogenic and ketogenic AA(Amino Acid) 10. Essential AA and their role.

11. Importance of non-essential AA. 12. Transmethylation.

13. What is nitrogen balance? +ve and -ve balance? 14. Role of liver in NH3 metabolism? 15. How is urea formed from NH3? 16. Fate of NH3 in brain, liver, RBC. 17. What is non-protein nitrogen? (NPN) 18. How different AA are incorporated in protein? Protein Synthesis

CHAPTER ON VIVA VOICE

19. Effect of starvation on protein metabolism. 20. Role of DNA, RNA in protein synthesis. 21. Protein calorie malnutrition. 22. Oxidative decarboxylation. 23. Role of vitamins in protein metabolism. 24. Glycine formation and fate. 25. Biogenic amines - formation. 26. Serotonin formation. 27. T 3' T4 formation. 28. Epinephrine, Nor-epinephrine formation. 29. Phenyl ketonuria, alkaptonuria, albinism. 30. Cysteinurla, homocysteinuria, cystinosis. 31. Sources of N,C of purine, pyrimidine. 32. Conversion of ribonucleotide to deoxyribonucleotide. 33. Salvage pathway. 34. Denovosynthesis of nucleotides. 35. What is gout? 36. Degradation product of purines. 37. IMP conversion to AMP, GMP. 38. IMP conversion to CMP,TMP. 39. Oroticaciduria. 40. Lesch-Nyhan syndrome? Which is enzyme defect?

"',~-

'41. Role of B12 , folic acid in nucleotide formation. (

VITAMINS: 1. Explain how vitamins are classsified. 2. What are the deficiencies disease of vitamin A? 3. How many types of vitamin A and their sorces. (a) Fresh water (b) Salt water (c) Vegetable. 4. What is the pro-vitamin for vitamin A? 5. Why is ~-Carotene regarded as the potent form? 6. What are the functions of vitamin A.

625

626

TEXT BOOK OF BIOCHEMISTRY

7. What is the role of vitamin A in the stabilization of the cell. 8. What is called as xeropthalmia? 9. What do you understand by Nyctolopia.

10. What do you understand by dark adaptation test? 11. What is the blood level- of vitamin A? 12. What is Carr price reaction? 13. What is the daily requirement of vitamin A? 14. What is Hypervitaminosis? 15. What do you understand by anti-Rachitic substaces? 16. What is the relationship of stereo and vitamin 0 to sterol 17. Explain whether vitamin O2 & 0 3 are the active form? 18. What is the role of vitamin 0 3? 19. Why vitamin 0 is regarded as the hormone.

20. How vitamin 0 affect the calcium and Phosphorous metabolism? 21. What is the relationship of vitamin 0, parathyroid hormone? Role Alkaline P04 and thyro-calcitonin in maintenance of calcium and Phosphorus ratio in the body. 22. What is Osteomalacia and rickets? 23. What is the Osteoporosis? 24. What is the role of vitamin 0 in bone formation? 25. What is the requirement of vitamin O2 or 0 3 ? 26. What do you understand by 1 I U. for vitamin A and vitamin O? Sources of vitamin

O. 27. How vitamin O2 or 0 3 synthesized in the body by exposure of skin to u.v. radiation 28. What do you understand by anti- sterility factor? 29. What are the anti oxidant properties of vitamin E?

30. Why are vitamin E to copherol regarded as potent form of vitamin E.(a-tocopherol}? 31. How does vitamin E prevents the muscular dystrophy? 32. What is the daily requirement of vitamin E? 33. Why is vitamin K. called as K? 34. What are the different forms of vitamin K? 35. Explain the role of vitamin K in prothorombin synthesis in the liver. 36. What is the role of Thiamine in Carbohydrate metabolism? 37. What are the deficiencies of Thiamine?

CHAPTER ON VIVA VOICE

627

38. What is the requirement and sources of Thiamine? 39. Which is active form/coenzyme for of Thiamine? 40. What is Beri-Beri? Types of Beri Beri.

41. Enzyme thiaminase is present in raw fish therefore eating raw fish leads to a disorder Beri-Beri explain. 42. Name the sulphur containing vitamins. 43. What is the difference between FMN & FAD? 44. Name the deficiency syndromes occuring with vitamin B2 - glositis chelosis & angular stomatitis. Explain the meaning. 45. What is the coenzyme activity of vitamin B2? 46. Why Niacin is called as P.P. factor? 47. What are the three D's? 48. How niacin is synthesized in the body? 49. In how many forms niacin is absorbed and utilized in the body? 50. Name the two forms of niacin? Which is best tolerated by body?

51. What are the Coanzyme forms of pyriodoxin? 52. Name the reaction where the coenzyme is utilized. 53. Which deficiencies are found because of this vitamin? 54. Name the vitamin causing Egg White injury explain the mechanism. 55. Which vitamin is a part of Coenzyme A? 56. What is the role of pantothenic acid in fatty acid synthesis? 57. Which are the anti anaemic vitamins folic acid (B12' vitamin C & B)? 58. Which vitamin causes nurological symptoms? Explaiin their role. (B1' B6 , B12) 59. What is the Conezyme of folic acid? 60. Which amino acid is a part of folic acid (Pteroil glutamic acid)

61. Which type of anaemia results because of folic acid deficiency? (Microacyctic hypochromic)

62. What are the factors causing nutritional anaemias? 63. Which is the intrinsic and extrinsic factor? 64. Which is the mineral as a part of vitamin B12? 65. Why is vitamin C not included in the B complex group? (Deficiency of this particular vitamin causes scurvy.) 66. What is the daily requirement of vitamin B12?

628

TEXT BOOK OF BIOCHEMISTRY

67. What are the physiological function of vitamin C? 68. Why vitamin C cannot be synthesized in the human body? 69. What is Tillmans reaction?

ENZYMES: 1. Why enzymes are called enzymes? 2. What is zymogen secretion? 3. What do you understand by enzymes and coenzymes? 4. What is Prosthetic group? 5. Define enzymes. 6. All enzymes are proteins with exception of _ _ _ _ __ 7. What are the functions of enzymes? 8. Explain simple enzyme reactions? 9. What are the factors affecting enzyme reaction? 10. How products of the reaction inhibts the enzyme reaction? 11. What is the completion period of the enzyme reaction? 12. How do you arrest enzyme reaction? 13. Which is the enzyme secreted after the death of the cell? 14. Explain the enzyme inhibition? 15. What is meant by competitive inhibition? Give example. 16. Explain the inhibition brought by other factors like freezing alcohol etc. 17. Give the examples of competitive and noncompetitive inhibition? 18. What is understood by enzyme activation? 19. Give some examples of enzyme activation. 20. Explain the autocatalytic procedure. 21. What is the role of hormones in converting the inactive form into active form of enzymes? 22. How the Phosphorylation and dephosphorylation affects enzyme activation? give examples? 23. Explain the enzyme-substrate accepted theories in the enzyme reaction. 24. What is the role of vitamins in bringing about reaction? 25. What is understood by coenzyme activity? 26. What is the role of thiamine? 27. What is the role of Pyridoxine?

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629

28. What is the role of B Complex vitamins in the completion of the enzyme reaction? 29. What is feed back inhibition and feed back activation? 30. What is the difference between enzyme and hormone? 31. What is the mechanism of hormonal action of thyroxine? What is the mechanism of hormonal action of steroid Hormones. What is the mechanism of hormonal action of adrenaline Inonradrenaline? 32. What is the feed back and -ve feed back regulation of the endocrines? 33. What are isoenzymes? How are they formed? Give examples. 34. What is the Clinical significance of isoenzymes? 35. How does it help in confirming the differential diagnosis. Give Example. (LDL fraction, CPK 1, CPK2 , CPK3) 36. What is the Pharmacological use of enzymes? 37. What is the use of enzymes in clinical disorders? 38. Which enzyme is administered immediate after ischemia of the myocardium? (streptokinase) 39. What is the significance of Michaclis - Menten constant? 40. High Km value indicates what? 41. How does it affect enzyme activity? 42. What is the Km equation? 43. How the different inhibitions affect Krn value? 44. What is cAMP? How is it formed? 45. What is the role of denydrogenases? 46. What is the role of cAMP in different metabolisms? 47. Name the coenzyme that is associated with L.amino acid oxidase. 48. And with D-amino acid oxidase. 49. Name coenzyme I and coenzyme II?

INORGANIC METABOLISM: Calcium and Phosphorus: 1. Explain the sources of Ca and P in the diet. 2. Factors absorbing Ca and P from the intestin. 3. How Pl1ytic acid prevents the absorption of Ca++? 4. What is the ionic product of Ca and P? How is it maintained? 5. What is the role of PTH gland?

630

TEXT BOOK OF BIOCHEMISTRY

6. What do you understand by CAP? 7. What is the role of thyrocalcitonin? 8. Describe the condition when Ca is removed from the bone? 9. Loss of Ca from the bone in adults is osteoporosis in children is Ricket. 10. What is the Ca level of blood? 11. What is exactly understood by ionic Ca? 12. Describe the percentage of total Ca. 13. Explain the Ca homeostasis in muscle undergoing tetany? 14. What are the functions of Ca and P? 15. Explain Hard water and soft water. 16. Ionic Ca++ and Heart function? Describe relation? 17. Ca exist in how many forms? 18. Normal Level of ionised Ca++ 19. Role of Ca in coagulation of blood. 20. What is the effect hyper calcimia? 21. Why secondary parathyroism is seen in CRF? 22. If absorption is defective, how does it disturb calcium homeostasis? 23. What factors are responsible for Ca and P absorption? 24. Etiology of Anemia in kidney failure (CRF). 25. Status of Ca and P in renal failure and the reasons for osteoporosis 26. What is secondary parathyroidism? 27. Explain the role of Liver. 28. Explain the ricket formation. 29. What is osteoporosis? 30. Excessive excretion of Ca and P in urine causes vitamin D resistant rickets. 31. Name some high energy Phosphate compounds in body. 32. Role of Ca in cloting of the blood? 33. What is Calmodulin? 34. Describe the action of Ca channel blockers. 35. Biochemistry of bone formation. 36. How the mineral matrix is formed? 37. What is the role of mucopolysaccharide in bone formation? 38. Explain Ca, P Homeostasis?

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WATER & ELECTROLYTE BALANCE: 1. Why water intake is necessary? Explain describing various functions of water. 2. How is the water balance maintained? 3. Describe the role of different hormones in the water balance. 4. Describe the role of Na+ and K+ in relation with aldosterone and angiotenesin III in maintainence of water balance. 5. Describe the role of plasma protein in maintainance of water contents in the cell. 6. Explain the causes of Oedema formation or swelling in the relation with Osmolarity maintained at the intracellular and extracellular fluid. 7. Explain the status of water balance and Na+ and K+ in persistant diarehea and in less consumption of water leading to dehydration. 8. How Na+ and K+ are estimated? which instruments are used?

TRACE ELEMENTS: 1. Name some trace elements. 2. Explain the role of iodine in thyroid glands. 3. Why iodized salt is adv!sed? 4. What are the functions of Iodine in human beings. 5. What are the sources of Iodine? 6. What is daily requirement of Iodine? 7. Deficiency syndromes of iodine. 8. What is toxic gOiter & nontoxic goiter? 9. Role of Zn in body as trace elements. 10. Which mineral is required in carboxpepldises activity? 11. What are the Sources of Cu? 12. What are the functions of Cu? 13. What is ceruloloplasmin? 14. Name soma enzymes for which Cu is required. 15. What is wilson's disease? 16. Which vitamin contain cobalt? 17. What are the types of Vitamin 6 12? 18. What is the role of Cr in the body? 19. What are the functions of Mo in the body? Aldehyde oxidase and xanthineoxidase where Mo is component. 20. What are the functions of Se in the body? (Se deficiency disturbs the function of Vitamin E).

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21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34.

What are the functions Iron in the body? What is the abnormality due to fluoride deficiency? What is the abnormality due to excessive fluoride intake? In which form iron is absorbed from intestine? How is iron transported in the body? What is the storage form of Iron? What is the deficiency of Iron? What happens in the excess intake of iron? What is ferritin and haemosiderin? What is the difference between Heme and non heme iron? Which are the non-heme Iron containing compouns? What are the sources of iron? Name of the enzymes containing Iron-sulphur proteins. What is Hemosiderosis?

ACID BASE BALANCE: 1. What is pH of arterial and venous blood? 2. How is pH maintained? 3. Blood buffer types? 4. Ratio of HC03- to H2C03 ? 5. Ratio of NaH2 P04 to Na2 HP04 • 6. Role of Hb as buffer. 7. What is alkali reserve? 8. Acidosis, alkalosis and their compensation. 9. What is uncompensated acidosis/alkalosis?

10. Role of lung, kidney for pH of Blood. 11. Explain Henderson Haselbalch equation? 12. pH - 'p' stands for what?

13. 14. 15. 16.

What is metabolic and respiratory acidosis? Status of blood pH in starvation? What is diabetic acidosis? Explain mechanism in uncompensated acidosis/alkalosis

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DETOXICATION: 1. What is detoxicationn? Define.

2. What is other name for detoxication? 3. What are different mechanisms of detoxication? 4. Explain the mechanism of conjugation with suitable examples. 5. Give a examples of mechanism of oxidation, reduction, hydrolysis. 6. Site? 7. Give an example of a detoxication reaction? Which is involved in liver function test?

ENVIRONMENTAL BIOCHEMISTRY: 1. Cold exposure with its shivering phase?

2. Effect of cold exposure on metabolism of Carbohydrate Metabolism, fat protein. 3. What is heat balance? 4. Various adaptations to heat. 5. Effect of high P02 on mitochondrial enzymes? 6. Effect of low 02 conc. in atmosphere? 7. Biochemical basis of convulsion in 02 toxicity 8. Name inert gases. State their effect on the body. 9. Explain how air pollutants like CO, S02 are harmful?

10. Name electromagnetic radiations with ill effects. 11. Name parameters analysed in the laboratory in order to monitor water pollution.

12. Toxic biochemical effect of metal pollutants 13. Problems associated with food preservation.

BIOLOGICAL OXIDATION: 1. Explain Biological oxidation?

2. What is substrate level phosphorylation? Example? 3. What is oxidative phosphorylation? 4. Explain Electron Transport chain. 5. How cyanide inhibits cytochrome C-oxidase? 6. Different hypothesiS for oxidative phosphorylation?

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GENETICS: 1. What is Transcription, Translation, Replication, Okazaki fragments, Bacteriophage 2. What are plasm ids? 3. Where is lagging strand formed? 4. What is codon? Give specific feature? 5. Wobble Hypothesis, Frame shift Mechanism. 6. Which enzyme takes part in transcription? 7. Which amino acid is activated first? 8. Inhibitors of protein synthesis. 9. Silent and mis-sense mutations. 10. Different elongation factors involved. 11. 'A' site and 'p' site of ribosomes.

HAEMOGLOBIN: 1. What is the difference between oxyhaemoglobin and oxidized Hb? 2. How heme is synthesized in body? 3. What are the functions of Hb? 4. What are the different types of Hb? How are they separated? 5. What are the derivatives of Hb? 6. Give the different types of abnormal Hb? 7. Name the instrument by which you see derivatives of heamoglobin. 8. How do you estimate Hb? Normal range for men and women? 9. What is thalassemia major and minor? 10. What is sickle cell anemia? 11. What is hemophilin?

CANCER: 1. What is:- Neoplasm, Etiology of cancer, Oncogens? 2. Types of tumors? example Of Benign tumor? 3. Types of carcinogens presens. Examples 4. What are proximate and pro-carcinogen? 5. Mutagens? 6. Name DNA, RNA viruses? 7. What is metastasis?

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8. Biochemical, morphological changes in cancer cells? 9. Name antimetabolite of cancer present. 10. Which chromosomes are translocated in Burketts lymphoma? 11. a-fetoprotein (glycoprotein) increase in which cancer? MUSCLE CHEMISTRY: 1. Name different contractile proteins in muscle? 2. What is the role of ATP creatlinine P in muscle contraction? 3. Role of Ca in muscle contraction and relaxation. 4. What is the role of Muscle phosphogen? QQQ

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REFERENCES

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HARPER'S BIOCHEMISTRY, 25th Edition, by .:. Robert K. Murray .:.

Daryl K. Granner

.:.

Peter A. Mays

.:.

Victor W. Rodwell

REVIEW OF PHYSIOLOGICAL CHEMISTRY, 17th Edition,by .:.

Harold A. Harper

.:.

Victor W. Rodwell

.:.

Peter A. Mays

HUMAN BIOCHEMISTRY, 10th Edition,by .:.

James M. Orten and O.H.W. Neuhaus

TEXTBOOK OF MEDICAL BIOCHEMISTRY, 5th Edition, by .:. M.N. Chatterjee and Rana Shinde TEXTBOOK OF BIOCHEMISTRY,3rd Edition, by D.M. Vasudevan and Srikumar's .:. PRINCIPLES OF BIOCHEMISTRY, 1st Edition, by .:.

T.N. Pattibiraman

BIOCHEMISTRY, by .:. Debajyoti Das, 10th Edition .:.

Dr. U. Satyanarayana, 1st Edition

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TEXTBOOK OF BIOCHEMISTRY, by .:. Dinesh Puri TEXTBOOK OF MEDICAL BIOCHEMISTRY, 3rd Edition 2001,by .:.

S. Ramakrishnan

.:.

K.G. Prasanan

.:.

R. Rajan

CLINICAL DIETETICS AND NUTRION, 3rd Edition,by .:.

Late Dr. F.P. Antia (Gastro-enterologist)

.:.

Consultant, Breach Candy Hospital, Mumbai.

LIPPINCOTT'S ILLUSTRATED REVIEWS: BIOCHEMISTRY, 2nd Edition,by .:. Pamela C. Champe .:.

Richard A. Harve

FUNDAMENTAL IN BIOCHEMISTRY, by .:. A.C. Deb

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