Description : Cyclooxygenase-1 and –2 are responsible for (a) The synthesis of prostaglandins from arachidonate (b) The synthesis of leukotrienes from arachidonate (c) The conversion of ATP to cAMP (d) The metabolic degradation of cAMP (e) The conversion of GTP to cGMP
Last Answer : Ans: A
Description : Which of the following enzymes is ultimately responsible for the production of prostaglandins associated with inflammatory reactions? (a) Phospholipase (b) Lipoxygenase (c) Cyclooxygenase-I (d) Cyclooxygenase II (e) Xanthine oxidase
Last Answer : Ans: D
Description : Inflammation is a complex tissue reaction that includes the release of cytokines, leukotrienes, prostaglandins, and peptides. Prostaglandins involved in inflammatory processes are produced from arachidonic acid by (a) ... 2 (c) Glutathione - S - transferase (d) Lipoxygenase (e) Phospholipase A2
Last Answer : Ans: B
Description : The synthesis of heme from protophyrin III is catalysed by the enzyme: (A) ALA synthase (B) Ferroreductase (C) Ferrooxidase (D) Ferrochelatase
Last Answer : Answer : D
Description : Non steroidal anti inflammatory drugs, such as aspirin act by inhibiting the activity of the enzyme: (A) Lipoxygenase (B) Cyclooxygenase (C) Phospholipase A2 (D) Lipoprotein lipase
Last Answer : Answer : B
Description : Aspirin inhibits the activity of the enzyme: (A) Lipoxygenase (B) Cyclooxygenase (C) Phospholipae A1 (D) Phospholipase A2
Description : True statements regarding eicosanoids include which of the following? A. Prostaglandins and thromboxanes are synthesized via the cyclo-oxygenase pathway. B. The vasoconstricting, platelet-aggregating, ... prostaglandins have a short circulation half-life and exert most of their effects locally.
Last Answer : Answer: ABD DISCUSSION: The eicosanoids are a group of compounds arising from the metabolism of arachidonic acid. The prostaglandins and thromboxanes are synthesized via the cyclo-oxygenase ... effects and may be involved in the physiologic responses associated with anaphylactic and septic shock
Description : The action of aspirin that results in its greater efficacy as an antithrombotic (anti-platelet) drug is its ability to (a) Inhibit lipoxygenase as well as cyclooxygenase (b) Selectively inhibit ... I (c) Inhibit leukocyte migration (d) Promote uric acid excretion (e) Acetylate cyclooxygenase
Last Answer : Ans: E
Description : Aspirin may reduce inflammatory responses by inhibiting which of the following enzymes? A A. Cyclooxygenase B. Lipoxygenase C. Phospholipase C D. None of these
Last Answer : Cyclooxygenase
Description : Corticosteroids exert antiinflammatory action by inhibiting the following enzyme: A. Cyclooxygenase B. Lipoxygenase C. Phospholipase-A D. Phosphodiesterase
Last Answer : C. Phospholipase-A
Description : Which of the following regarding thromboxane A2 is true? C A. It degrades basement membranes B. It is produced via the lipoxygenase pathway C. It stimulates platelet aggregation D. None of these
Last Answer : It stimulates platelet aggregation
Description : The following eicosanoid is generated through the lipoxygenase pathway: A. Prostaglandin E2 B. Thromboxane A2 C. Leukotriene C4 D. Prostacyclin
Last Answer : C. Leukotriene C4
Description : Two molecules of acetyl-CoA condense to form acetoacetyl-CoA catalysed by (A) Thiolase (B) Kinase (C) Reductase (D) Isomerase
Last Answer : Answer : A
Description : Conversion of the linear tetrapyrrole hydroxymethylbilane to uroporphyrinogen III (A) Occurs spontaneously (B) Catalysed by uroporphyrinogen I synthase (C) Catalysed by uroporphyrinogen III cosynthase (D) Catalysed by combined action of uroporphyrinogen I synthase and uroporphyrinogen III cosynthase
Description : Which of the following statement(s) is/are correct concerning the immunoinflammatory response to shock? a. The anaphylactoxins, C3a and C5a, are products of activation of only the classical pathway ... effects d. Platelet-activating factor can be released by both circulating and fixed tissue cells
Last Answer : Answer: d Inflammatory mediators have recently been recognized as playing a significant role in the clinical manifestations and progression of shock and the development ... increased pulmonary vascular resistance, bronchoconstriction, peripheral vasodilatation, and increased vascular permeability
Description : Dilatation of the peripheral arterial blood vessels can be caused by: a. thromboxane A2 b. adenosine diphosphate c. endothelin d. prostaglandins
Last Answer : prostaglandins
Description : The following are true about chemicals involved in allergic reaction: a. thromboxane -leukocyte activation b. prostaglandin-2 - vasodilatation c. platelet-activating factor - leukocyte activation d. heparin - augments inactivation of prostaglandins
Last Answer : prostaglandin-2 - vasodilatation
Description : In mammals, synthesis of mRNA is catalysed by (A) RNA polymerase I (B) RNA polymerase II (C) RNA polymerase III(D) RNA polymerase IV
Description : The first reaction unique to purine nucleotide synthesis is catalysed by (A) PRPP synthetase (B) PRPP glutamyl amido transferase (C) Phosphoribosyl glycinamide synthetase (D) Formyl transferase
Description : The rate limiting step in catecholamine synthesis is catalysed by (A) Phenylalanine hydroxylase (B) Tyrosine hydroxylase (C) Dopa decarboxylase (D) Phenylethanolamine N-methyl transferase
Description : Synthesis of phosphatidylinositol by transfer of inositol to CDP diacylglycerol is catalysed by the enzyme: (A) CTP phosphatidate cytidyl transferase (B) Phosphatidate phosphohydrolase (C) CDP-diacylglycerol inositol transferase (D) Choline kinase
Last Answer : Answer : C
Description : In gluconeogensis, an allosteric activator required in the synthesis of oxaloacetate from bicarbonate and pyruvate, which is catalysed by the enzyme pyruvate carboxylase is (A) Acetyl CoA (B) Succinate (C) Isocitrate (D) Citrate
Description : De novo synthesis of fatty acids is catalysed by a multi-enzyme complex which contains (A) One-SH group (B) Two-SH groups (C) Three-SH groups (D) Four-SH groups
Description : A cup of strong coffee would be expected to (A) Interfere with synthesis of prostaglandins (B) Decrease the effects of Glucagon (C) Enhance the effects of epinephrine (D) Provide the vitamin nicotinic acid
Description : Aspirin blocks the synthesis of (A) Prostaglandins only (B) Prostacyclins only (C) Thromboxanes only (D) All of these
Description : A cup of strong coffee would be expected to (A) Interfere with the synthesis of prostaglandins (B) Decrease the effect of glucagon (C) Enhance the effect of epinephrine (D) Provide the vitamin nicotinic acid
Description : Cyclo-oxygenase is involved in the synthesis of (A) Prostaglandins (B) Thromboxanes (C) Both (A) and (B) (D) None of these
Description : Lipo-oxygenase is required for the synthesis of (A) Prostaglandins (B) Leukotrienes (C) Thromboxanes (D) All of these
Description : Synthesis of prostaglandins is inhibited by (A) Glucocorticoids (B) Aspirin (C) Indomethacin (D) All of these
Description : Anti-inflammatory corticosteroids inhibit the synthesis of (A) Leukotrienes (B) Prostaglandins (C) Thromboxanes (D) All of these
Description : For synthesis of prostaglandins, the essential fatty acids give rise to a fatty acid containing (A) 12 carbon atoms (B) 16 carbon atoms (C) 20 carbon atoms (D) 24 carbon atoms
Description : A patient who has been taking quantities of aspirin might show increased post operative bleeding because aspirin inhibits:** A. Synthesis of thromboxane A2 and prevents platelet aggregation B. ... network E. Increase the absorption of vitamin K and prevents synthesis of blood clotting factors
Last Answer : A. Synthesis of thromboxane A2 and prevents platelet aggregation
Description : Choose the correct statement about ticlopidine: A. It blocks GPIIb/IIIa receptors on platelet membrane B. It prevents ADP mediated platelet adenylylcyclase inhibition C. It inhibits thromboxane A2 synthesis in platelets D. It does not prolong bleeding time
Last Answer : B. It prevents ADP mediated platelet adenylylcyclase inhibition
Description : Inhibition of thromboxane synthesis by aspirin in platelets lasts for 5-7 days because: A. Aspirin persists in the body for 5-7 days B. Aspirin induced depletion of arachidonic acid lasts 5-7 ... 5-7 days D. Platelets cannot generate fresh thromboxane synthetase and their turnover time is 5-7 days
Last Answer : D. Platelets cannot generate fresh thromboxane synthetase and their turnover time is 5-7 days
Description : Aspirin prolongs bleeding time by inhibiting the synthesis of: A. Clotting factors in liver B. Prostacyclin in vascular endothelium C. Cyclic AMP in platelets D. Thromboxane A2 in platelets
Last Answer : D. Thromboxane A2 in platelets
Description : Selective inhibition of thromboxane A2 synthesis by low dose aspirin therapy might retard the progression of: A. Pregnancy induced hypertension B. Steroid induced hypertension C. Renal hypertension D. Malignant hypertension
Last Answer : A. Pregnancy induced hypertension
Description : Low doses of aspirin prolong bleeding time by selectively inhibiting synthesis of the following mediator in the platelets: A. Thromboxane A2 B. 5-Hydroxytryptamine C. Platelet activating factor D. Prostacyclin
Last Answer : A. Thromboxane
Description : .Which of these is not an important component of initiation of parturition in humans? (a) Release of oxytocin (b) Release of prolactin (c) Increase in estrogen and progesterone ratio (d) Synthesis of prostaglandins
Last Answer : b) Release of prolactin
Description : Leukotrienes: 1) Are formed from the cyclooxygenase pathway 2) Are synthesized by fibroblasts 3) Decrease vascular permeability 4) Leukotriene D4 has been identified as SRS-A which causes bronchial wall smooth muscle relaxation 5) Stimulate mucus secretion
Last Answer : Answers-5 Leukotrienes are synthesized by leucocytes.They are mediators of allergic reaction. They increase vascular permeability and attract neutrophils and eosinophils to inflammatory sites. ... stimulate mucus production, an important consideration in the pathophysiology of bronchial asthma.
Description : Glutathione is a constituent of (A) Leukotriene A4 (B) Thromboxane A1 (C) Leukotriene C4 (D) None of these
Description : What is the effect of thromboxane?
Last Answer : Thromboxane (TXA2) is the main PG produced by platelets. The major effects are vasoconstriction and platelet aggregation. Prostacyclin and thromboxane are opposing in activity.
Description : Conversion of testosterone to estradiol requires the enzyme: (A) Aromatase (B) Dehydrogenase (C) Lyase (D) Isomerase HORMONE METABOLISM 215
Description : The enzyme catalyzing conversion of androstenedione to testosterone is a (A) Oxygenase (B) Dehydrogenase (C) Isomerase (D) Decarboxylase
Description : 3-β-Hydroxysteroid dehydrogenase and ∆5,4 isomerase catalyse the conversion of the weak androgen DHEA to (A) Androstenedione (B) Testosterone (C) Progesterone (D) Estrone
Description : In the biosynthesis of cortiol, the sequence of enzymes involved is (A) Hydroxylase–dehydrogenase + isomerase – hydroxylase (B) Dehydrogenase–hydroxylase–isomerase (C) Hydroxylase–lyase–dehydrogenase isomerase (D) Isomerase–lyase–hydroxylase–dehydrogenase
Description : Urease is a (A) Lyase (B) Ligase (C) Isomerase (D) Hydrolase
Description : Pyruvate dehydrogenase is a/an (A) Isomerase (B) Lyase (C) Ligase (D) Oxido reductase
Description : Glucose-6-phosphate is an allosteric inhibitor of (A) Glucokinase (B) Hexokinase (C) Phosphohexose isomerase (D) None of these
Description : Which of the following is an allosteric enzyme? (A) Phosphohexose isomerase (B) Phosphotriose isomerase (C) Lactate dehydrogenase (D) Phosphofructokinase
Description : In biosynthesis of cholesterol triparanol inhibits the activity of the enzyme: (A) ∆24 Reductase (B) Oxidosqualene-lanosterol cyclase (C) Isomerase (D) Squalene epoxidase ENZYMES 155