Tagged: Histamine

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Histidine to histamine conversion

Histamine causes vasodilatation and bronchoconstriction. In the stomach it stimulates the secretion of hydrochloric acid (HCl). Histamine binds to H1 receptors in the stomach, stimulating the release of gastric acid. Pharmacological blockers of H1 receptors are used in the treatment of gastric reflux. H2 receptors are located on basophils; histamine stimulates their degranulation during the allergic responses. H2 receptor blockers are used to treat allergic conditions. Histamine is produced from Histidine by: A. Deamination B. Transamination C. Carboxylation D. Decarboxylation E. Methylation The correct answer is D- Decarboxylation. Histamine is a biogenic amine. A biogenic amine is a potent signaling...

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Answer- Case study- Oral contraceptives induced vitamin deficiencies

Case Details Oral contraceptives are known to lower blood levels of folate and vitamin B6. Which of the following conversion processes might be directly affected? A. Ornithine to Citrulline B. Histidine to histamine C. Glutamate to Glutamine D. Propionyl co A to Methyl malonyl co A E. Phenyl alanine to Tyrosine Answer- B- The correct answer is conversion of Histidine to histamine. The reaction is catalyzed by decarboxylase that requires B6-P as a cofactor (Figure-1) that gets deficient in women upon long-term oral contraceptive usage. Folic acid is not required in this reaction. Figure-1- Decarboxylation of Histidine is carried out...

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