Riboflavin is involved in maintaining normal circulating levels of homocysteine; in riboflavin deficiency, homocysteine levels increase, elevating the risk of cardiovascular diseases. Redox reactions
Redox reactions are processes that involve the transfer of electrons. The flavin coenzymes support the function of roughly 70-80 flavoenzymes in humans (and hundreds more across all organisms, including those encoded by archeal, bacterial and fungal genomes) that are responsible for one- or two-electron redox reactions which capitalize on the ability of flavins to be converted between oxidized, half-reduced and fully reduced forms. FAD is also required for the activity of glutathione reductase, an essential enzyme in formation of the endogenous antioxidant, glutathione. Micronutrient metabolism
Riboflavin, FMN, and FAD are involved in the metabolism of niacin, vitamin B6, and folate. The synthesis of the niacin-containing coenzymes, NAD and NADP, from tryptophan involves the FAD-dependent enzyme, kynurenine 3-monooxygenase. Dietary deficiency of riboflavin can decrease the production of NAD and NADP, thereby promoting niacin deficiency. Conversion of vitamin B6 to its coenzyme, pyridoxal 5-phosphate synthase, involves the enzyme, pyridoxine 5-phosphate oxidase, which requires FMN. An enzyme involved in folate metabolism, 5,10-methylenetetrahydrofolate reductase, requires FAD to form the amino acid, methionine, from homocysteine.Riboflavin deficiency appears to impair the metabolism of the dietary mineral, iron, which is essential to the production of hemoglobin and red blood cells. Alleviating riboflavin deficiency in people who are deficient in both riboflavin and iron improves the effectiveness of iron supplementation for treating iron-deficiency anemia. Synthesis
Biosynthesis
Biosynthesis takes place in bacteria, fungi and plants, but not animals.
Vesical tenesmus refers to the feeling of incomplete emptying of the bladder following urination. When the word tenesmus is used without modification, it usually refers to rectal tenesmus. Vesical tenesmus is caused by urogenital diaphragm muscle spasms. See also
Post-void dribbling
Prostate
Rectal tenesmus

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