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Biomedical subjects

C De Marco

Publications and source records attributed to C De Marco.

At least 91 records · Page 5Linked to original sources
PubMed1965

The role of sulphur, sulphide and reducible dyes in the enzymic oxidation of cysteamine to hypotaurine.

1. Cysteamine is oxidized to hypotaurine by an enzyme extracted from horse kidney, with sulphur or sulphide acting as a cofactor. It has been now found that, when the enzyme is omitted, sulphur and sulphide are able to catalyse the oxidation of cysteamine to cystamine by molecular oxygen. 2. Methylene blue may be used in catalytic amounts as a cofactor in the enzymic oxidation of cysteamine to hypotaurine in the place of sulphur or sulphide. The effect of methylene blue is not light-dependent and is not abolished by catalase. Other redox dyes with E'(0) higher than that of methylene blue are also used as cofactors. 3. A property common to all the cofactors is that they are necessary for the enzymic process in catalytic amounts, though they depress the final amount of hypotaurine produced when added over a critical concentration. All the cofactors share also the property of being catalysts for the non-enzymic oxidation of cysteamine to cystamine. 4. Methylene blue is reduced by cysteamine under anaerobic conditions, and is reoxidized in the presence of air. The rate of the reduction is not accelerated by the enzyme, indicating that the dye does not act in this reaction as a hydrogen carrier from the enzyme to oxygen. The possible mechanism of action of methylene blue and of the other cofactors is discussed.

Animals↗
PubMedDate not supplied

Endoscopy of the uterus and its congenital malformations.

Laparoscopy and hysteroscopy are two endoscopic procedures with which the outer surface of the uterus, its cavity can be studied with a detailed analysis of the endometrium and ostia. The stages of the study are described and uterine congenital malformations are described in relation to the reproductive performance of women.

Female↗
PubMedDate not supplied

Oxidative deamination of epsilon-N-acetylthialysine and epsilon-N-acetylselenalysine by snake venom L-aminoacid oxidase.

epsilon-N-acetylthialysine and epsilon-N-acetylselenalysine are oxidatively deaminated by Crotalus adamanteus l-aminoacid oxidase, giving rise to the corresponding alpha-ketoacids, identified by some chemical and chromatographic tests and by comparison with synthetic compounds. no cleavage of the C-S or C-Se bonds of the substrates occurs during the reaction. The enzyme acts as well on the epsilon-N-acetylderivatives of thialysine and selenalysine as on epsilon-N-acetyllysine. The substitution of the gamma methylene group of lysine by a sulfur or a selenium atom seems not to greatly affect the substrate specificity of the enzyme.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Copper catalyzed alkaline autoxidation of selenocystamine.

In alkaline medium and in the presence of cupric ions selenocystamine undergoes autoxidation and is entirely transformed into selenohypotaurine. Among the different metal ions tested, Fe, Co, Ni, Cu, Ag, Mg, Mn, only cupric ions are effective in catalyzing the reaction. The reaction shows an optimum around pH 13. In most respects the autoxidation of selenocystamine is similar to the alkaline autoxidation of cystamine. Some data on the paper and ion exchange chromatographic behaviour of selenohypotaurine and selenotaurine are reported, as also details for the synthesis of selenotaurine.

Cations, Divalent↗