Overview Function generate NADPH required for FA synthesis, steroid synthesis, reduction of oxidizing agents (H2O2 see figure) provide ribose 5-phosphate required for nucleotide synthesis Pathway occurs in cytoplasm of all cells no ATP consumed or generated 2 phases oxidative produces NADPH glucose 6-phosphate (G6P) → 6-phosphogluconate catalyzed by glucose 6-phosphate dehydrogenase (G6PDH) rate limiting step activated by NADP+, insulin inhibited by NADPH irreversible nonoxidative exchanging intermediate substrates between glycolysis and HMP shunt catalyzed by transketolase requires thiamine reversible Clinical relevance glucose-6-phosphate dehydrogenase (G6PDH) deficiency pathophysiology ↓ NADPH production cells (specifically RBCs) lose protection against oxidizing agents cannot regenerate glutathione XR most common human enzyme deficiency ↑ prevalence among blacks ↑ malarial resistance by shortening the circulation life of RBCs Plasmodium does not have enough time for life span plasmodium does not have defense against free radicals ↑ in free radicals kills parasite presentation episodic hemolytic anemia intravascular hemolysis normocytic 2-3 days post precipitating stress foods fava beans common in Mediterranean foods presentation pallor, hemoglobinuria 24-48 post ingestion drugs sulfonamides, primaquine, antituberculosis drugs infection free radicals generated by the immune system Heinz bodies oxidized hemoglobin that precipitates within RBCs bite cells result from the phagocytic removal of Heinz bodies by macrophages back pain test active hemolysis screen Heinz body prep
QUESTIONS 1 of 4 1 2 3 4 Previous Next (M1.BC.17.4707) A 12-year-old boy presents to the emergency department with fatigue and back pain. He has also had tea-colored urine over the last 24 hours. Upon being asked about changes to his routine over the last week, he remembers running a 5K, trying alcohol with a friend, and having a large meal at a friend's house with ingredients that he did not recognize. On physical exam he appears to be pale with conjunctival pallor. Labs are as follows:Hemoglobin: 11 g/dLHematocrit: 32%Mean Corpuscular Volume: 88 fLPeripheral blood smear findings are shown in Figure A. An enzyme defect in which of the following pathways is likely responsible for this patient's symptoms? QID: 108445 FIGURES: A Type & Select Correct Answer 1 Amino acid synthesis 3% (7/230) 2 Glycolysis 14% (32/230) 3 Hemoglobin assembly 7% (17/230) 4 Hexose mono-phosphate (HMP) shunt 59% (136/230) 5 Porphyrin synthesis 13% (29/230) M 1 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (M1.BC.15.74) A 32-year-old male with HIV presents to his physician with complaints of shortness of breath and fatigue. He has a history of being non-compliant with his HAART regimen, and his CD4 count is found to be 149. The physician obtains a chest radiograph, which is shown in Figure A. Further workup demonstrates that the patient is infected with the organism demonstrated in Figure B. The physician prescribes the first-line treatment for this infection. One day later, the patient returns complaining of severe weakness and dark colored urine. On exam, the physician notes that the patient is jaundiced, and a peripheral blood smear demonstrates the findings shown in Figure C. Which of the following would most mimic this patient's condition? QID: 106610 FIGURES: A B C Type & Select Correct Answer 1 Glutathione reductase deficiency 62% (26/42) 2 Galactokinase deficinecy 2% (1/42) 3 Ornithine transcarbamolyase deficiency 10% (4/42) 4 Carnitine deficiency 10% (4/42) 5 Cystathionine synthase deficiency 5% (2/42) M 1 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (M1.BC.13.22) A 55-year-old African American lawyer presents to your office with complaints of fatigue, back pain and dark urine that he notices in the morning when he wakes up. The patient is well known to you. He frequently travels to Bangkok where he has admitted to having unprotected sex. You have treated him in the past for chlamydia, gonorrhea and syphilis. This patient has a family history of sickle cell disease in 4 of his brothers. He has a past medical history of HIV and his most recent CD4 count was 147 cells/µL. His current medications include lisinopril, glyburide, metformin, ibuprofen, and buspirone. Appropriate prophylactic measures were taken one week ago account for his low CD4 count and his traveling. The patient's CBC demonstrates:Hemoglobin: 9 g/dLHematocrit: 32%White blood cell count: 3,600 cells/µLPlatelets: 155,000/µLA peripheral blood smear is shown in Figure A. A chest radiograph is shown in Figure B.Which of the following is the best explanation for this patient's symptoms? QID: 100087 FIGURES: A B Type & Select Correct Answer 1 Decreased levels of CD55 and CD59 14% (23/163) 2 Osteomyelitis of the vertebral column 10% (17/163) 3 Defective conversion of glucose-6-phosphate to 6-phosphogluconate 56% (91/163) 4 Side-effect of rifampin treatment 10% (17/163) 5 Splenic insufficiency 4% (6/163) M 1 Question Complexity E Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic
All Videos (1) Login to View Community Videos Login to View Community Videos HMP Shunt/Pentose Phosphate Pathway Keshav Mudgal Biochemistry - HMP Shunt D 12/18/2015 101 views 5.0 (3)