Tagged: Clinical cases

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Splicing

The most common cause of β- Thalassemia is the defect in mRNA splicing of the beta globin gene. Mutations that affect the splicing create aberrant transcripts that are degraded before they are translated. If patients inherit a single mutated gene (thalassemia minor), the disease manifests with a mild anemia. However, patients with homozygous mutations (thalassemia major) have severe transfusion-dependent anemia. Which of the following types of RNA are involved in the splicing process? A. Ribosomal RNA (r RNA) B. Small nuclear RNA (sn RNA) C. Transfer RNA (t RNA) D. Small cytoplasmic RNA (sc RNA) E. Heterogeneous nuclear RNA (hn...

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Reaction catalyzed by Xanthine oxidase

Allopurinol, (the inhibitor of xanthine oxidase), is used in the treatment of Gout. More recently, febuxostat, a novel nonpurine analog inhibitor of xanthine oxidase, has been used. Which of the following reactions is catalyzed by xanthine oxidase? A. Hypoxanthine to Xanthine B. Xanthine to Hypoxanthine C. Hypoxanthine to uric acid D. Inosine to hypoxanthine E. Adenosine to Inosine. The correct answer is- A, Conversion of hypoxanthine to xanthine. Basic concept Gout is a metabolic disease most often affecting middle-aged to elderly men and postmenopausal women. It is the result of an increased body pool of urate with hyperuricemia, typically characterized...

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Cholesterol content and membrane fluidity

Membrane fluidity is required for the proper movement of erythrocytes through capillaries of the spleen. Patients with spur cell anemia have increased cholesterol content (> 40%) in the membranes of their erythrocytes, resulting in decreased membrane fluidity. Thus, erythrocytes from these patients are destroyed in the spleen. Which of the following statements is incorrect concerning the significance of cholesterol? A. Elevated levels of cholesterol are associated with atherosclerosis. B. The serum total cholesterol content should be less than 200 mg/dl. C. Cholesterol is a major component of gall stones. D. Excess cholesterol is excreted from the liver in the bile...

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Effect of pH on enzyme activity

The optimal pH for pepsin is 2, reflecting its need as a digestive enzyme in the gastric juice of the stomach; whereas the optimal pH for alkaline phosphatase is 9, reflecting the basic environment in bone (Figure-1)   Figure-1- Effect of pH on catalytic activity of enzyme. Changes in the pH can alter these changes, so that the reaction proceeds at a slower rate. If the pH is too high or too low, the enzyme can also undergo denaturation. Which of the following statements is true of denaturation? A. The enzyme loses its capacity to hold the substrate B. The...

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Gray Baby syndrome and the role of Glucuronic acid

Case details Infants have decreased ability to conjugate Glucuronic acid on to drugs such as Chloramphenicol. Administration of this antibiotic during the neonatal period can result in elevated plasma levels of the drug and a fetal shock-like syndrome referred to as Gray Baby syndrome. Glucuronic acid is produced from Glucose in the Uronic acid pathway by the process of: A. Oxidation B. Reduction C. Hydrolysis D. Carboxylation E. Decarboxylation. Details The correct answer is- A- Oxidation. Glucuronic acid is produced from Glucose by oxidation in the Uronic acid pathway, which is an alternative pathway of glucose utilization. Glucuronic acid in...

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Question of the day-Enzyme catalyzing Carbon-Carbon bond cleavage in Glycolysis

Which of the following enzymes cleaves a carbon-carbon bond in glycolysis? A. Phospho triose isomerase B. Aldolase C. Phospho glycerate kinase D. Enolase E. Pyruvate Kinase The correct answer is B- Aldolase. The Aldolase cleaves fructose-1,6-bisphosphate (the product of 2nd glycolytic reaction catalyzed by Phospho fructo kinase -1) between the C-3 and C-4 carbons to yield two triose phosphates. The products are dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate (figure). Figure- Reactions of glycolysis. Phospho triose isomerase Of the two products of the Aldolase reaction, only glyceraldehyde-3-phosphate goes directly into the second phase of glycolysis. The other triose phosphate, dihydroxyacetone phosphate, must be...

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Role of “Nucleoside analogs” in HIV infection

Case details A 34-year-old homosexual man has recently been diagnosed with HIV (human immunodeficiency virus) infection. His CD4+ T-cell count has dramatically decreased, and he has a high viral load. He has been referred to an infectious disease clinic where he has been prescribed with a nucleoside analog. The nucleoside analogs inhibit DNA synthesis. Which of the following chemical groups essentially required for DNA polymerization is absent in the nucleoside analogs? A. 5′ Phosphate B. 3′ Hydroxyl C. 2′ Methyl D. 3′-Phosphate E. 5′ Hydroxyl. The correct answer is- B-3′ Hydroxyl. Basic concept Nucleosides Nucleosides are derivatives of purines and pyrimidines...

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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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Protein folding defect

Case details A 50-year-old male presents with “dancing –like” movements of his arms and progressive dementia. He cannot control the movement of his arms. He states that he knows that he has Huntington’s disease because his mother has the same disease. The disease is caused by abnormal protein folding. Which of the following helps to mediate proper protein folding? A. Chaperones B. Transcription factors C. DNA binding proteins D. RNA binding proteins E. All of the above.   Figure-Folding of a protein to acquire a mature functional conformation Discussion- The correct answer is Chaperones. Most proteins must fold into defined three-dimensional...

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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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Role of ACAT in the esterification of cholesterol

See the image below and note the role of ACAT (Acyl Co A cholesterol acyl transferase) in the esterification of cholesterol. Cholesterol is stored in the cell in the form of cholesteryl esters. Esterification involves the coupling of cholesterol with a fatty acid, generally this fatty acid is a- A. Saturated fatty acid B. Monounsaturated fatty acid C. Polyunsaturated fatty acid D. Dienoic acid E. Any of the above. Figure-1- Uptake of LDL and fate of cholesterol The correct answer is- Monounsaturated fatty acid, Commonly Oleic acid is used for the esterification (figure-2) Oleic acid is a mono- unsaturated fatty...

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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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Nitrogen balance

A 22 -year-old man started to work out twice a day with the goal of competing in an upcoming bodybuilding competition. Despite his strict working routine, he continues eating a diet of fast food hamburgers and French fries. After a gain of 15 pounds, it is likely he is in a: A. Vitamin overload B. Negative nitrogen balance C. Positive nitrogen balance D. State of decreased BMR E. State of increased BMR Answer- The correct answer is- C-Positive nitrogen balance. The gain in weight despite strict work out signifies positive nitrogen balance. The state of protein nutrition can be determined...

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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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Significance of Lipoproteins

Case details A 50 -year-old male presents with weakness in his left leg. History reveals that he is a known hypertensive and a diabetic from the past 5 years, but is non- compliant to medication. Based on the clinical findings and imaging of the brain, he has been diagnosed with “Brain stroke”. His serum total cholesterol is abnormally elevated. Which of the following would also be expected to be abnormally high? A. Chylomicrons B. LDL C. HDL D. VLDL E. IDL The correct option is- B, LDL (Low density lipoprotein) Lipids absorbed from the diet and synthesized by the liver...

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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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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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‘Hereditary fructose Intolerance’- Case discussion

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- 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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Introductory message

Welcome to Biochemistry for Medics© – Clinical Cases™.  Our Vision We want this website to be a dynamic environment whereby everyone can interact freely in order to discuss Clinical Cases and solve them. Registration In order to be able to comment on cases, you will need to “register” with us. And the way to do so cannot get any simpler. All you have to do is just click on any one of your preferred Social Accounts amongst Facebook, Twitter, Google, LinkedIn or Microsoft Live, – on the left sidebar – and you shall forever be registered with us. We do...

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