Indicadores
Gonadal glycoprotein hormone, Inhibin A, consists of an alpha subunit covalently linked to a beta-A subunit and strongly inhibits pituitary FSH secretion. Serum concentrations transit during the menstrual cycle. Dimers of the beta subunit (a TGF-beta superfamily member), termed activin, are potent stimulators of FSH secretion. (from OMIM 147380 and NCI)
Indicadores
Inhibin B, consisting of an alpha subunit and a beta B subunit linked by disulphide bonds, is a heterodimer hormone produced by the follicle cells of the ovary and by the Sertoli and Ledig cells of testis. Although other forms of inhibin also exist in men, inhibin B is the predominant form in the circulation in men.
Technology
A laboratory test to determine the lowest concentration of a substance that will inhibit a biological or biochemical function, such as microorganism growth or enzymatic activity.
Diagnostic Methods
Indicadores
A natural cyclic polypeptide immunosuppressant isolated from the fungus Beauveria nivea. The exact mechanism of action of cyclosporine is not known but may involve binding to the cellular protein cytophilin, resulting in inhibition of the enzyme calcineurin. This agent appears to specifically and reversibly inhibit immunocompetent lymphocytes in the G0-or G1-phase of the cell cycle. T-lymphocytes are preferentially inhibited with T-helper cells as the primary target. Cyclosporine also inhibits lymphokine production and release. (NCI04)
Indicadores
A nonmetallic chemical element found in trace amounts in human body. Selenium primarily occurs in vivo as selenocompounds, mostly selenoproteins such as glutathione peroxidase and thioredoxin reductase (enzymes responsible for detoxification). Alone or in combination with Vitamin E, selenocompounds act as antioxidants. These agents scavenge free radicals; prevent blood clots by inhibiting platelet aggregation; strengthen the immune system; and have been shown, in some instances, to inhibit chromosomal damage and mutations. Exhibiting chemopreventive activity, selenocompounds also inhibit the induction of protein kinase C.
Indicadores
A natural alkaloid derivative of xanthine isolated from the plants Camellia sinensis and Coffea arabica. Theophylline appears to inhibit phosphodiesterase and prostaglandin production, regulate calcium flux and intracellular calcium distribution, and antagonize adenosine. Physiologically, this agent relaxes bronchial smooth muscle, produces vasodilation (except in cerebral vessels), stimulates the CNS, stimulates cardiac muscle, induces diuresis, and increases gastric acid secretion; it may also suppress inflammation and improve contractility of the diaphragm. (NCI04)
Indicadores
A heat-labile and water-soluble essential vitamin, belonging to the vitamin B family, with antioxidant, erythropoietic, mood modulating, and glucose-regulating activities. Thiamine reacts with adenosine triphosphate (ATP) to form an active coenzyme, thiamine pyrophosphate. Thiamine pyrophosphate is necessary for the actions of pyruvate dehydrogenase and alpha-ketoglutarate in carbohydrate metabolism and for the actions of transketolase, an enzyme that plays an important role in the pentose phosphate pathway. Thiamine plays a key role in intracellular glucose metabolism and may inhibit the action of glucose and insulin on arterial smooth muscle cell proliferation. Thiamine may also protect against lead toxicity by inhibiting lead-induced lipid peroxidation.
Indicadores
A branched tricyclic glycosylated peptide with bactericidal activity against most organisms and bacteriostatic effect on enterococci. At a site different from that of penicillins and cephalosporins, vancomycin binds tightly to the D-alanyl-D-alanine portion of cell wall precursors, thereby interfering with bacterial cell wall synthesis. This leads to activation of bacterial autolysins that destroy the cell wall by lysis. Vancomycin may also alter the permeability of bacterial cytoplasmic membranes and may selectively inhibit RNA synthesis.