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Biochemistry For Medics 1

Biochemistry Spotting Semester Examination- (November-2012)

Biochemistry for Medicswww.namrata.co

Case studies Visuals Graphs Spot Questions Glass wares Reagents Equipments Urine and blood reports

12/13/2012

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Spot-1A laboratory technician accidently consumed Dinitrophenol. Soon after that his body was observed to be extreme hot. He was sweating profusely and was extremely thirsty. What could be the possible reason for these symptoms ?

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Dinitrophenol is an uncoupler of oxidative phosphorylation.

Oxidative phosphorylation is a coupled process, The uncouplers allow the oxidation to proceed but

there is no ATP formation. The surplus energy that would have been used up

for ATP formation is released in the form of heat. The symptoms in the given patient, high body

temperature, sweating and thirst are due to heat released by the said uncoupling of oxidative phosphorylation.

Answer- Spot-1

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Spot-2A patient of long standing Diabetes Mellitus on treatment presents with recurrent fractures and generalized swelling.Physical Examination reveals- Pallor++ Puffiness around eyes+ B.P.- 160/100 mm Hg

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Spot-2 (Contd.)Laboratory Investigations-Blood BiochemistryGlucose 110 mg/dlUrea 100 mg/dlCreatinine 6 mg/dlUric acid 8.8 mg/dlCalcium 6 mg/dlHb 6 G /dl

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Spot-2(Contd.)Urine ExaminationColor- NormalAppearance- ClearSpecific Gravity- 1.010Protein ++Reducing sugar NilWhat is your probable diagnosis ?

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It is a case of Renal failure, as is evident from high blood urea and serum creatinine levels.

Urinary specific gravity (1.010) and proteinuria are also additional findings in support of diagnosis.

It might be a complication of long standing diabetes mellitus (Diabetic nephropathy ) which has progressed to renal failure.

Anemia is due to reduced erythropoietin secretion from the kidney.

Fractures and hypocalcemia are due to vitamin D deficiency. As the last step of activation of vitamin D takes place in kidney.

Puffiness is due to water retention.

Spot-2- Answer

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A fair chubby boy was brought to the hospital with the complaint that he has mental retardation.

Blood Biochemistry revealed that phenyl alanine was abnormally high.

Phenyl pyruvate was present in appreciable amount in urine.

What is the probable diagnosis ? Which other metabolite can be

found in urine ?

Spot-3

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The child is suffering from Phenyl ketonuria It is a congenital disorder of phenyl alanine

metabolism. Caused due to deficiency of phenyl alanine

hydroxylase enzyme, that converts phenyl alanine to tyrosine

In the deficiency of phenyl alanine hydroxylase, phenyl alanine accumulates in blood and is also alternatively transaminated to form phenyl pyruvate, that gets excreted excessively in urine

Spot-3- Answer

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The other metabolites excreted in urine are phenyl acetyl glutamine and phenyl lactate

Phenyl pyruvate produced from transamination reaction can be decarboxylated to phenyl acetate that is conjugated with glutamine to form phenyl acetyl glutamine, which is responsible for imparting characteristic mousy odor to the urine

Phenyl lactate is produced from phenyl acetate by reduction.

Spot-3 – Answer (Contd.)

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Sodium Fluoride is used in combination with potassium oxalate (in the ratio of 1:3) while sample collection for Blood glucose estimation.

Glycolysis is said to be inhibited as a result of inhibition of one of the enzymes of this pathway.

The results are plotted to depict the mode of inhibition.

Spot-4

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State the type of inhibition and name the enzyme inhibited by the action of sodium fluoride

Spot-4 (Contd.)

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There is no change in Km, but Vmax has decreased in the presence of inhibitor.

It is a non competitive inhibition Enolase enzyme that catalyzes the conversion of 2-

Phosphoglycerate to Phospho enol pyruvate is inhibited by sodium fluoride

Glycolysis is required to be inhibited as otherwise, glucose of the sample would get oxidized and falsely low blood glucose values would be obtained and that happens if sodium fluoride is not used

Spot- 4- Answer

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Out of the two instruments (A and B),Which one is use for the determination of pH of the solutions ?

By what other methods, pH of solutions can be measured ?

Spot-5(A) (B)

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The instrument (A) is pH meter that can be used for pH measurement.

The other instrument (B) is Flame photometer that is use for the determination of the ions

pH can also be determined by using indicators, pH papers, indicator papers and universal indicator solutions

Spot-5- Answer

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Which out of the two glass wares (A and B) is used for the centrifugation of the biological fluids ?

What is the use of the other glass ware ?

Spot-6

(A) (B)

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(A) is cuvette, that is used in the colorimetric procedures for determination of the absorbance value of the colored solutions.

(B) is centrifuge tube, that is used for the centrifugation of biological fluids.

Spot-6- Answer

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The urine test of a patient gave the following result-

A purple ring at the junction of two liquids- Identify the substance present in the urine . Name the test carried out.

Spot-7

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This is Rothera’s test carried out for the detection of urinary ketone bodies

A positive reaction is given by acetone and acetoacetate.

Beta- hydroxy butyrate does not give a positive reaction in this test.

The patient is having ketonuria, that might be due to uncontrolled diabetes mellitus, starvation , high fat diet or heavy exercise.

Spot-7- Answer

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A 45-year-old obese lady attended the outpatient department with-

a history of severe right sided abdominal pain

vomiting fever and yellow tinge of sclera. Ultrasound of the abdomen shows the

presence of gall stones.

Spot-8

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State the type of jaundice in this patient ? What would be the urinary findings in this patient ?

Spot-8 (Contd.)

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Gall stones cause obstruction in the common bile duct, hence it is obstructive jaundice

Urine will show the presence of Bilirubin since it is conjugated hyperbilirubinemia

Due to obstruction to the outflow of bile urobilinogen will not synthesized and hence it would be absent in urine

Note-Only conjugated Bilirubin can appear in urine. Unconjugated Bilirubin is water insoluble and is also bound to albumin, hence can not be filtered to appear in urine.

Spot-8- Answer

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The bone marrow smear of a strict vegetarian female patient presenting with weakness, fissured tongue and paralysis is displayed.

Make a diagnosis and suggest the line of treatment.

Spot -9

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Fissured tongue and megaloblastic anemia are signs of vitamin B12 deficiency

The patient is a strict vegetarian that is another proof of vitamin B12 deficiency

Neurological manifestations are also characteristic of B12 deficiency.

The patient should be treated by a supplementation of a combination of folic acid and vitamin B12

Folic acid and B12 deficiencies always coexist due to trapping of folate in methylated form in B12 deficiency (Folate trap )

Spot-9 - Answer

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A new born baby experienced abdominal distension, severe bowel cramps and diarrhea after being fed with milk.

A hydrogen breath analysis of the exhaled breath discovered an eighty fold increase in the production of hydrogen 90 minutes after milk feeding.

Spot-10

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The urine analysis revealed the presence of a reducing sugar which formed the characteristic osazone crystals as shown under the microscope.

Identify and draw the crystals and mention the defect.

Spot-10 (Contd.)

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The given slide shows lactosazone crystals (Powder puff).

The history and clinical features are also suggestive of Lactose intolerance

Lactose intolerance is caused due to deficiency of lactase enzyme

The undigested lactose is absorbed in the intestinal cells by pinocytosis that enters systemic circulation to appear in urine causing lactosuria.

Spot-10 - Answer

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An 8-year-old child has been brought to OPD with pain abdomen and vomiting.

These episodes often occur upon consumption of table sugar and sugar candies.

A provisional diagnosis of “Hereditary Fructose Intolerance "is framed for this child.

There is inability to metabolized fructose in this disorder

Spot-11

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Which of the two tests would be best suitable to confirm the presence of fructose in urine ?

What is the significance of the other test?

Spot-11 (Contd.)

SeliwanoffBarfoed

(B)(A)

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Seliwanoff test is the most confirmatory test for fructose

Barfoed test is given positive by all reducing monosaccharides, it is not a confirmatory test for fructose

Keto hexose (Fructose) in the free or bound form gives this test positive.

This test is also given positive by Sucrose.

Spot-11 (Answer)

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Which of the two reagents is used for the detection of urinary chlorides ?

What is the significance of the other reagent?

Spot-12

Silver Nitrate Mercuric sulphate

(A) (B)12/13/2012


Silver nitrate (A) is used for the detection of urinary chlorides

Mercuric sulphate is used for the detection of Tyrosine by Millon’s test.

Chlorides present in urine react with silver nitrate to form a white precipitate of silver chloride

Spot-12 - Answer

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Urine Examination reportName- Mrs. ParvatiAge - 68 yearsSex - Female Occupation- HousewifePhysical Examination Color- Dark yellow Appearance- Slightly turbid Odor-Aromatic Volume – 75 ml pH- 7.0 Specific Gravity- 1.035

Spot-13

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Chemical examination Reducing sugars- nil Proteins- nil Ketone bodies- nil Blood- nil Bilirubin- absent Urobilinogen- +++++

Spot-13

Make a probable diagnosisBy which method Urinary Bilirubin can be detected ?

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Specific gravity is on the higher side probably due to the presence of urobilinogen

Dark color of urine is also due to high urobilinogen content

There is no Bilirubin. Since urine shows the presence of urobilinogen There is no other abnormal component It is a case of prehepatic jaundice (Acholuric

Jaundice) In prehepatic jaundice bilirubin is Unconjugated,

hence can not appear in urine. Urinary bilirubin can be detected by Fouchet’s test

Spot-13- Answer

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A child stops making developmental progress at the age of 2 years and develops coarse facial features with thick mucus drainage. Skeletal deformities develop over the next year, and the child regresses to a vegetarian state by the age of 10 years.

The child’s urine is positive for glycosaminoglycans, that include which of the followings ?

Spot-14

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A. Heparan SulfateB. CollagenC. GlycogenD. Gamma amino butyric acid

Spot-14(Contd.)

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The right answer is (A). The child is most probably suffering from Hurler

syndrome Heparan sulfate is the mucopolysaccharide

(Glycosaminoglycan- out of all the options) that is excreted out in urine in such affected patients

Collagen is a protein Glycogen is a storage form of glucose Gamma amino butyric acid is an inhibitory

neurotransmitter The last three can not be excreted in urine.

Spot-14- Answer

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A 14 –year-old boy was admitted to the hospital because of sudden pain on the left flank. Urine analysis reveals hexagonal crystals.

24 hours urine sample shows excessive excretion of Cystine.

What is the probable diagnosis ?

Spot-15

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It is a case of Cystinuria, an absorption defect

Cystine, Ornithine , Arginine and Lysine are excessively lost in urine due to deficiency of transporter (COAL)

Cystine is precipitated in acidic urine As urine becomes more concentrated in the

kidneys, the excess cystine forms crystals in acidic pH. As these crystals become larger, they form stones that may lodge in the kidneys or in the bladder.

Spot-15- Answer

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A chronic alcoholic has been brought to casualty in a semi-conscious state

Physical examination reveals mild icterus and moderately enlarged liverBlood biochemistry reveals- High serum Bilirubin High blood ammonia level Low serum protein level A provisional diagnosis of Liver Cirrhosis is

made

Spot-16

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Spot-16

1) What is the normal range of blood ammonia level ?

2) What is the cause of ammonia intoxication in brain ?

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Normal blood ammonia level ranges between-10-80 μg/dl

Excess of ammonia is detoxified by conversion of glutamate to glutamine- first line of defense

Still excess if present- by conversion of Alpha keto glutarate to Glutamate

As a result there is excess of glutamine, but less of glutamate and Alpha keto glutarate

Spot-16- Answer

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Glutamine is exchanged with tryptophan, a precursor of serotonin, that causes over excitation

Low glutamate- Low GABA (Inhibitory neurotransmitter )- State of hyper excitation

Low Alpha keto glutarate- TCA cycle suppressed- Energy depletion

Patients of ammonia intoxication present with slurring of speech, blurring of vision, convulsions, coma and death in untreated cases.

Spot-16- Answer

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Spot-17 Mention the normal reference range of serum total cholesterol Give the names of two cholesterol lowering drugs to be prescribed to a patient with hypercholesterolemia State two most important causes of hypercholesterolemia

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Serum total cholesterol ranges between 150-220 mg/dl

Statins are the most commonly used drugs to lower cholesterol levels

The other lipid lowering drugs are- Ezetimibe, Niacin, Bile acid sequestrants, Fibrates etc

Hypercholesterolemia is observed in Diabetes mellitus, Nephrotic syndrome, Hypothyroidism, Biliary cirrhosis, Obstructive jaundice and in familial cases (Familial hypercholesterolemia)

Spot-17- Answer

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Spot18 A young man with hypercholesterolemia was rushed to the hospital with crushing chest pain radiating to the left arm and a probable heart attack. The attending physician after confirmation of the diagnosis administered streptokinase injection. What is the role of this drug in heart attack ?

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Streptokinase is given as a fibrinolytic agent in coronary thrombosis

It acts by promoting conversion of plasminogen to plasmin ( that can degrade circulating fibrinogen) as well as plasminogen that is bound to a fibrin clot.

It is given in the first 6 hours of myocardial infarction to dissolve the clot

Being non specific in nature, can cause bleeding, it is largely replaced by t PA (tissue plasminogen activator) prepared by recombinant DNA technology.

Spot-18- Answer

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Spot-19Interpret from graph

1) FBS ?2) Peak value of

blood glucose ?

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Spot-19 (Contd.)

Make a complete diagnosis from the blood and urinary findings

Time in hours

zero 1/2 1 1hour 30 mins

2 2hours 30 mins

3

Urinary sugar

+ ++ ++++

++++

++++

++++

++++

Ketone bodies

+++ +++ +++ +++ +++ +++ ++++

Urine Analysis Report

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Fasting blood glucose is high (135 mg/dl) There is delayed peak and the peak value is

also high (200 mg/dl) The blood glucose values after half an hour

of glucose load have crossed renal threshold (160-180 mg/dl)

Glucose and ketone bodies are there in almost all the urine samples

It is a case of diabetic ketoacidosis.

Spot-19 -Answer

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Spot-20 A 70 year-old female patient was seen in an emergency service with a chief complaint of crushing substernal chest pain. Her past medical history revealed a diagnosis of hypertension for five years, for which she received Captopril 25 mg three times a day. Her family history was positive for hypertension and coronary artery disease. What is the basis of using Captopril in this patient ?

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Answer- Spot-20

Captopril is an ACE inhibitor (Angiotensin converting enzyme inhibitor) Angiotensin II is a potent vasoconstrictor, by inhibiting ACE, the formation of Angiotensins from Angiotensinogen is inhibited. Captopril acts by competitive inhibition.

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