Tagged: Biochemistry

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Alcohol induced hypoglycemia

Case details A known alcoholic is found lying semiconscious at the bottom of a stairwell with a broken arm by his landlady, who called an ambulance to take him to the emergency room. Initial laboratory studies showed are relatively large anion gap of 34 (normal = 9 to 15). His blood alcohol was elevated at 245 mg/dL (intoxication level = 150 to 300 mg/dL), and his blood glucose was 38 mg/dL (low normal). The patient/s large anion gap and hypoglycemia can best be explained by which of the following? A. Decreased secretion of glucagon B. Increased secretion of insulin C....

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Implications of maternal hyperglycemia

Case details A pregnant mother with a history of long-standing uncontrolled diabetes mellitus has come for a routine check up. The examination reveals a normal pregnancy. Blood chemistry reveals random blood glucose – 165 mg/dl and Glycated hemoglobin (HbA1c) of 10.5 %. What are the possible complications in a fetus under such conditions of maternal hyperglycemia? A. Fetal hyperglycemia B. Large fetal size C. Hypoglycemia after birth D. Fetal hyperinsulinemia E. All of the above. See the image below and try to find out the answer Figure- Showing the implications of maternal hyperglycemia. The correct answer – E- all of the...

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Case study- Hyperammonemia

Question of the day -Hyperammonemia A new-born becomes progressively lethargic after feeding. His respiratory rate increases and he becomes virtually comatose, responding only to painful stimuli, and exhibits mild respiratory alkalosis. Suspicion of a urea cycle disorder is aroused and evaluation of serum amino acid levels is initiated. In the presence of hyperammonemia, production of which of the following amino acids is always increased? A. Glycine B. Arginine C. Proline D. Histidine E. Glutamine Answer- The correct answer is Glutamine. Urea cycle disorder results in reduced ammonia disposal and hence the patients present with symptoms of hyperammonemia. Ammonia is detoxified by...

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A common intermediate of Urea and TCA cycle

Question of the day Which one of the following can be converted to an intermediate of either the citric acid cycle or urea cycle? A. Tyrosine B. Lysine C. Leucine D. Tryptophan E. Aspartate Answer- The correct answer is- E -Aspartate. 1) Role of Aspartate in urea cycle Aspartate participates in urea cycle for condensation with citrulline to form Argino succinic acid. The reaction is catalyzed by Argino succinic acid synthetase (Aspartate provides one out of the two nitrogens of urea, the other nitrogen is contributed by Glutamate). In the subsequent reaction, Argino succinic acid undergoes a lytic reaction to...

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Immediate treatment of Acute MI

Case details A 56-year-old man with hypercholesterolemia was rushed to the hospital with crushing chest pain radiating to his left arm and a probable heart attack. Which of the following treatments should be considered? A. A platelet transfusion B. Heparin transfusion C. Thrombin transfusion D. Fibrinogen infusion E. Tissue plasminogen activator infusion The correct answer is- E- Tissue plasminogen activator infusion. Tissue plasminogen activator (tPA) causes activation of plasminogen (zymogen form) to plasmin (active form). Plasmin hydrolyzes fibrin to form soluble degradation products (Figure-1). Figure-1- Mechanism of action of tPA The main goals of medical therapy of acute myocardial infarction...

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Action of Alpha- Amylase on starch

Prior to a race, many marathon runners will try to increase their glycogen concentrations by loading up with foods with high starch content, such as pasta. α-Amylase secreted by the pancreas will digest the starch into which of the following major products? A. Amylose, amylopectin, and maltose B. Glucose, galactose, and fructose C. Glucose, sucrose, and maltotriose D. Limit dextrins, maltose, and maltotriose E. Limit dextrins, lactose, and sucrose   Answer- The correct answer is-D- Limit dextrins, maltose, and maltotriose Starch consists of two fractions. About 20% is a water soluble material called Amylose. The majority of the starch is...

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Angular stomatitis and impaired TCA cycle activity

Case details A postoperative patient on intravenous fluids develops lesions in the mouth (angular stomatitis). Urinalysis indicates an excretion of 15 μg riboflavin/mg creatinine, which is abnormally low. Which of the following TCA cycle enzymes is most likely to be affected? A. Citrate synthase B. Isocitrate dehydrogenase C. Fumarase D. Malate dehydrogenase E. Succinate dehydrogenase Answer- The correct answer is- E- Succinate dehydrogenase Angular stomatitis and low excretion of riboflavin are indicators of underlying Riboflavin deficiency, hence the activities of only Riboflavin requiring enzymes would be affected . Riboflavin functions in several different enzyme systems. Two derivatives, riboflavin 5′ phosphate (flavin...

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Low body fat mass and hormone levels ?

An 11-year-old girl is presented at the clinic with reports of frequent fainting and lethargy. The girl is 5 ft tall and weighs 80 lb. Skin fold tests show an abnormally low percentage of body fat mass. Which of the following hormones is likely to be severely diminished in this patient? A. Cortisol B. Epinephrine C. Glucagon D. Insulin E. Thyroid Answer- The correct answer is D. The patient has low body weight and fat mass and there are frequent fainting attacks. Apparently her condition is consistent with a low energy state that might be due to poor diet or...

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Prolonged fasting and gluconeogenesis…

A 14-year-old high school girl who is extremely conscious about her appearance has gone a full day fasting to fit in to a dress she intentionally brought a size smaller than her actual size for a dance party. Which of the following organs/tissues contribute to the glucose that is being synthesized through gluconeogenesis during periods of prolonged fasting? A. Spleen B. Red blood cells C. Skeletal muscle D. Liver E. Brain D-Liver is the correct answer. Gluconeogenesis is the process of converting noncarbohydrate precursors to glucose or glycogen. The major substrates are the glucogenic amino acids, lactate, glycerol, and propionate....

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Role of Insulin in Diabetic ketoacidosis

Case details An 8-year old boy, a known diabetic (type 1 DM), has been brought to emergency room in a state of coma. His breathing is rapid and deep, and his breath has a fruity odor. His blood glucose is 480 mg/dL. The attending physician has administered IV fluids, insulin, and potassium chloride. A rapid effect of insulin in this situation is to stimulate A. Gluconeogenesis in liver B. Fatty acid release from adipose C. Glucose transport in muscle D. Ketone utilization in the brain E. Glycogenolysis in the liver Answer- The right answer is- c) Glucose transport in muscle....

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# About the web site

Dear viewers, This web site emphasizes on discussion of the essentials of Biochemistry with Clinical correlations. The purpose of this web site is to present a clear discussion of Biochemistry in relation to physiological processes occurring at the cellular levels and to cite examples of deviant biochemical processes in different clinical conditions. A clinical problem is published and the discussion is held subsequently. Through each case study the fundamentals of the basic defect, entire format of pathophysiology and the clinically relevant details are provided. The motive of this web site is not only to inculcate knowledge but also to make...

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Case study- Starvation

Case details A 25 –year-old woman living alone became severely depressed after the termination of her engagement. Two months later, she was brought to the emergency room by a friend because of weakness and lethargy. She appeared thin and pale. Questioning revealed that she had not eaten for several weeks. Analysis of a plasma sample indicated elevated levels of acetoacetate, β hydroxybutyrate, and blood urea nitrogen (BUN). However her plasma glucose concentration was within normal limits. She was hospitalized, given intravenous feeding and antidepressant medications and subsequently shifted to an 1800 Cal (7500 kJ) diet. Her recovery was uneventful. During...

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Case study- Renal glycosuria

Case details A 22-year-old man collapsed from dehydration during maneuvers in the desert and was sent to the emergency. A high level of glucose was observed in his urine. He was suspected of being a diabetic. Further tests, however, determined that his serum insulin level was normal. A glucose tolerance test exhibited a normal pattern; further testing of the urine revealed that only D-glucose was elevated. Other sugars were not elevated. The patient was diagnosed with, ‘Renal glycosuria’. This patient’s elevated urinary glucose and his dehydration episode are caused by a deficiency in which of the following? A. GLUT 2...

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Methotrexate in rheumatoid arthritis

Case details A 63- year-old woman presents with a long history of joint pains. Physical examination reveals severely deformed fingers secondary to rheumatoid arthritis. The rheumatologist recommends Methotrexate. This drug inhibits which of the following conversions? A. Dopamine to norepinephrine B. Tyrosine to Dopa C. Folate to dihydrofolate D. Histidine to formiminoglutamate (FIGLU) E. Norepinephrine to Vanillylmandelic acid The correct answer is- C. Folate to dihydrofolate conversion. The reaction is catalyzed by dihydrofolate reductase; the same enzyme catalyzes the conversion of Dihydrofolate to tetrahydrofolate. The enzyme is competitively inhibited by Methotrexate, which is also used as an anticancer drug. It...

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Fructose 2, 6 Bis phosphate and regulation of glycolysis

Case details A patient presents with dizziness, fatigue and tremors. A finger stick test indicates blood glucose of 36mmol/L. Of the allosteric activators of glycolysis in the liver, which of the following is the most important in maintaining a normal blood glucose level? A. Citrate B. ATP C. Fructose 2, 6 bisphosphate D. Glucose-6-Phosphate E. Acetyl Co A The correct answer is- C- Fructose 2,6 bisphosphate Generally, enzymes that catalyze essentially irreversible steps in metabolic pathways are potential sites for regulatory control.  Although most of the reactions of glycolysis are reversible, three are markedly exergonic and must therefore be considered...

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Biotin deficiency- A case report

Case details A 23-year-old body builder visits his physician with complaints of fatigue, depression, insomnia, hair loss and dry skin. He tells the physician he has been “bulking up” for an upcoming competition, and his meals consist mostly of eight raw eggs along with low-fat milk. The physician suspects biotin deficiency given the patients’ diet and symptoms. Which of the following is biotin required for? A. The formation of cis-retinal B. Transfer of 1-carbon units C. Hydroxylation reactions D. Carboxylation of pyruvate E. Decarboxylation of α-Keto acids Answer- D- Carboxylation of pyruvate is the right answer. Biotin is required for...

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Biochemical basis of difference in the electrophoretic mobilities of Hb A and HbS

Normal hemoglobin (Hb A) and sickle-cell hemoglobin (Hb S) have different electrophoretic mobilities because these two proteins have different what? A. Amount of bound oxygen B. Amount of bound 2, 3 bisphosphoglycerate C. Charges D. Size E. Hydrophobicity Answer- The correct answer is-C- charges. In Sickle cell disease, also called as sickle-cell anemia, a single nucleotide alteration (point mutation) in the β globin gene of hemoglobin causes a change of thymine for adenine (GAG to GTG.), at the sixth codon of the ß gene. This change encodes Valine instead of Glutamic acid in the sixth position on the ß-globin molecule....

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Case study- Achlorhydria (Discussion)

A 65- year-old woman is evaluated by a gastroenterologist for progressive signs and symptoms of malnutrition. Throughout her work up, she is found to have significantly decreased stomach acid. She is also found to have antibodies to gastric parietal cells, which are normally responsible for the production of acid. Why is hydrochloric acid important in digestion? A. It stimulates the cleavage of trypsinogen to trypsin B. It is required for the activity of α- Amylase C. It converts pepsinogen to pepsin D. It is required for lipid digestion E. It drives the secondary transport of amino acids Answer- The correct...

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About the Author- Biochemistry for Medics-Clinical Cases

Dr. Namrata Chhabra is a distinguished Senior-Level Medical Biochemistry Professional with extensive clinical, instructional, research, and administrative experience within prestigious institutions. Over the course of her career she has developed and conducted numerous courses focused on Chemistry, Biochemistry, Research & Analysis, and various other topics. She carries an award-winning track record in conducting high-caliber research, with complementary qualifications in quality management systems and medical laboratory auditing. She has proven herself committed to improving learning experiences for diverse student populations through strategic administrative leadership and curriculum development. She also serves on various academic and extracurricular committees. She also possesses a lengthy...

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Case study- Metabolic disorder- A 3-month-old girl is brought to the pediatrician due to fussiness and lethargy….

QUESTION OF THE DAY A 3-month-old girl is brought to the pediatrician due to fussiness and lethargy. According to the parents, the baby was just fine until the mother needed to return to work, and the baby was being switched from breast milk to baby foods, formula, and fruit juices. At that time, the child cried while feeding, sometimes vomited, and had been lethargic. The baby’s appetite seemed to have worsened. The parents thought that if only formula was used, the baby was better, but they really could not remember. Which possible enzyme defect might lead to this case presentation?...

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Case study- Pellagra

QUESTION OF THE DAY A 56 – year-old male on Isoniazid therapy for tuberculosis has developed rashes on the exposed parts of the body. History is also suggestive of disoriented memory and diarrhea. The patient has been diagnosed with pellagra. Pellagra is known to manifest in individuals deficient of niacin. What is the correlation of Isoniazid therapy and niacin deficiency? A. Isoniazid inhibits biological activation of niacin B. Isoniazid prevents absorption of niacin C. Isoniazid promotes excessive excretion of niacin D. Isoniazid inhibits endogenous synthesis of niacin E. Isoniazid acts a competitive inhibitor of niacin Answer- D- Isoniazid inhibits the...

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Case study Malignant hyperthermia (Electron transport chain and oxidative phosphorylation)

Case details A 23-year-old college foot ball player sustains a compound fracture on the field. He is taken to surgery, during which the anesthesiologist notes a significantly increased body temperature (102 0 F). The operation is terminated without completion, as malignant hyperthermia is suspected. Which of the following components of ETC is likely to be responsible for this phenomenon? A. Complex I B. Complex II C. Complex III D. Complex IV E.  ATP synthase complex Answer- The right answer is- E- ATP Synthase complex. Patients with malignant hyperthermia experience uncoupling of oxidative phosphorylation . OXIDATIVE PHOSPHORYLATION Chemiosmosis- As the electrons...

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