Protein Metabolism -Urea cycle

SGD –Protein metabolism-Urea cycle REFERENCES : ACC TO ME TEACHER'S POINTS NOTABLE POINTS 06-07-2021 1.A full term child born after normal pregnancy developed grunting respiration 24 hours after birth ammonium ion stimulates the medullary center of the brain responsible for controlling respiration. After 2 days he had severe bouts of vomiting and became lethargic and unresponsive to stimuli.A blood sample showed the following results Test Patients results Reference range pH 7.58 7.35-7.45 Urea 11mg% 15-45mg% Ammonia 468µg/dl 20-63 µg/dl Increase in plasma levels of amino acids glutamine and alanine were seen. Urine contained high amount of uracil. (uracil is a pyrimidine) • What is the probable diagnosis - and enzyme defect . • ANS- congentital hyperammonemia i.e hyperammonemia 2 -ORNITHINE TRANSCARBOAMYLASE DEF.. • How will you correlate the condition with the clinical features • ANS - Neurological symptoms seen • Explain the reason for an increase in glutamine,alanine and uracil • ANS - glutamine more due to more ammonia trapping in csf • alanine more due to muscle proteolysis(vomiting) • uracil more due to carb phosphate goes to pyrimidine synth. • How does phenylacetate help in the treatment. What are the other treatment options. • reduces glutamine and thus N2 waste • reduce protein intake • gene therapy 2. A 50 year old chronic alcoholic male patient was brought to the ER with altered sensorium for one day and history of convulsions that morning. On examination he was icteric affected with jaundice.,with hepatomegaly,ascites Abdominal swelling ,haemorrhages and spidernaevi cluster of minute red blood vessels visible under the skin suggestive of portal hypertension increase in the pressure within the portal vein due to blockage .Blood urea level 15mg/dl ,Ammonia -60 µg/dl . a) What is your probable diagnosis. hepatic encephalopathy i.e acquired hyperammonemia b) Explain the reason for the rise in ammonia and decreased urea. portal blood circulation gets shunted ***c) Discuss the cause of hyperammonemia in renal failure GFR IS DECREASED DUE TO RENAL FAILURE AMMONIA IN BLOOD INCREASES AND URINARY EXCRETION OF AMMONIA

IS DECREASED PROBABLY UREASE ENZYME IS IN EXCESS AND BACTERIA 3. A two year old child presented in the paediatric out patient department with skin rashes on sun exposed areas. The child was underweight had unsteady gait with slow motor and mental milestones.The parents were of consanguineous marriage .The elder sibling had a similar history and was treated with a high protein diet and sunscreens .A urine screening test showed large amounts of tryptophan. a) Suggest a probable diagnosis. autosonal recessive disorder- HARTNUP'S DISEASE b) How are pepsin,trypsin and chymotrypsin activated and state their specific site of action on polypeptides pepsinogen activated by hcl ; endopeptidase hydrolyses bonds formed by carboxyl grp of phenylalanine tyrosine tryptophan and methionine

trypsin activated by enterokinase which hydrolyses the bonds of the lysine and arginine chymotrypsin activated by trypsin ; hydrophobic aa , met , leu and aromatic aa c)Role of aminopeptidases and dipeptidases in preventing dietary protein allergy. Enterocytes secrete theses aa

allergy due to absorption of partially digested proteins

larger aa can pass through paracellularly and these peptidases destroy the larger di and tripeptides ------------------------------------------------------------------------------------------------