Category: Heme Metabolism

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Effect of Lead poisoning on heme biosynthetic pathway

A 3-year- old boy is brought to the emergency room with abdominal pain, mental status changes and fatigue. On taking history the physician finds the child belongs to a very poor family and lives in an old house and has the habit of licking the paint chips that have crumbled in the window sills. The physician suspects lead poisoning. Lead typically interferes with which of the following enzymes? A) Porphobilinogen deaminase B) Protoporphyrinogen oxidase C) ALA synthase D) Coproporphyrinogen oxidase E) ALAdehydratase The correct option is- ALA dehydratase. All the enzymes mentioned above are related with the pathway of heme biosynthesis. Heme is...

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Answer-Case study- Sickle cell disease-A 15-year-old African-American female presents to the emergency room ..

A 15-year-old African-American female presents to the emergency room with complaints of bilateral thigh and hip pain. The pain has been present for 1 day and is steadily increasing in severity. Acetaminophen and ibuprofen have not relieved her symptoms. She denies any recent trauma or excessive exercise. She does report feeling fatigued and has been having burning with urination along with urinating frequently. She reports having similar pain episodes in the past, sometimes requiring hospitalization. On examination, she is afebrile (without fever) and in no acute distress. No one in her family has similar episodes. Her conjunctiva and mucosal membranes...

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Case study- Sickle cell disease-A 15-year-old African-American female presents to the emergency room…

A 15-year-old African-American female presents to the emergency room with complaints of bilateral thigh and hip pain. The pain has been present for 1 day and is steadily increasing in severity. Acetaminophen and ibuprofen have not relieved her symptoms. She denies any recent trauma or excessive exercise. She does report feeling fatigued and has been having burning with urination along with urinating frequently. She reports having similar pain episodes in the past, sometimes requiring hospitalization. On examination, she is afebrile (without fever) and in no acute distress. No one in her family has similar episodes. Her conjunctiva and mucosal membranes...

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Porphyria – A case discussion

QUESTION OF THE DAY A 21-year-old young woman, who recently began taking birth control pills, presents to the emergency room with cramping abdominal pain, anxiety, paranoia, and hallucinations. A surgical evaluation, including ultrasound and computed tomography (CT) scan, fails to demonstrate an acute abdominal process. A urinalysis reveals an increase in urine porphyrins. Which of the following is the most likely defect? A. Congenital erythropoietic porphyria B. Variegate porphyria C. Porphyria cutanea tarda D. Acute intermittent porphyria E. Erythropoietic porphyria Answer- D- Acute intermittent porphyria; the patient is suffering from acute intermittent porphyria as  is evident from the clinical manifestations-...

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Case study- Porphyria

19/01/2014 Heme metabolism  Heme synthesis Heme biosynthesis involves eight enzymatic steps in the conversion of glycine and succinyl-CoA to heme (figure). The first and last three enzymes in the pathway are located in the mitochondrion, whereas the other four are in the cytosol. Heme is required for a variety of hemoproteins such as hemoglobin, myoglobin, respiratory cytochromes, and the cytochrome P450 enzymes (CYPs). Hemoglobin synthesis in erythroid precursor cells accounts for approximately 85% of daily heme synthesis in humans. Hepatocytes account for most of the rest, primarily for synthesis of CYPs, which are especially abundant in the liver endoplasmic reticulum,...

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