Tutor profile: Ibroxim Z.
Subject: Biomedical Science
A 57-year-old man with a new-onset burning sensation in mouth and throat, nausea and vomiting, agitation, and diaphoresis after a medication error was noted. Metabolic acidosis is seen on the arterial blood gas. A thiocyanate level is in the toxic range. What is the likely diagnosis?
With the information given, we can assume right away that the patient might have consumed something toxic. Since lab results show that thiocyanate levels were high, we can assume that the patient might've gotten cyanide poisoning. Cyanide inhibits mitochondrial cytochrome oxidase, blocking the electron transport chain and preventing oxygen utilization. Lactic acidosis results secondary to anaerobic metabolism which is explained by the low pH in the blood of the patient.
After excessive drinking over an extended period of time while eating poorly, a middle-aged man is admitted to the hospital with heart failure. Which key enzyme would most likely be inhibited?
This patient has exhibited symptoms of beri-beri heart disease, which is a result of a nutritional deficiency of vitamin B1 (thiamine). The active form of the vitamin, thiamine pyrophosphate, is a required cofactor for the enzyme, a-ketoglutarate dehydrogenase. Therefore, a-ketoglutarate, an essential enzyme in the Citric Acid Cycle or Krebs cycle would most likely be affected.
A pregnant woman is able to transfer oxygen to her fetus because fetal hemoglobin has a greater affinity for oxygen than does adult hemoglobin. Why is the affinity of fetal hemoglobin for oxygen higher?
Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin (HbA). This can be indicated on an Oxyhemoglobin Saturation Curve with a left shift (hyperbolic curve) compared to an normal adult hemoglobin which can be indicated by the sigmoidal curve on the graph. It is observed that fetal hemoglobin binds 2,3-bisphosphoglycerate (a side product of glycolysis) with fewer ionic bonds than the adult form which normally inhibits strong binding of oxygen to the hemoglobin. This is the major reason why fetal hemoglobin binds with a stronger affinity to oxygen compared to normal adult hemoglobin protein.
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