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Biomedical subjects

M Marchetti

Publications and source records attributed to M Marchetti.

At least 253 records · Page 14Linked to original sources
PubMed1976

A comparative study of the hemodynamic effects of single intravenous doses of 3-hydrazino-6-[N,N-bis-(2-hydroxyethyl)-amino]-pyridazine-dihydrochloride and hydralazine.

The new pyridazine derivative 3-hydrazino-6-[N,N-bis(2-hydroxyethyl)-amino]-pyridazine-dihydrochloride (DL 150 IT) was administered to five hypertensive patients at the dose of 50 mug/kg by i.v. bolus injection. A parallel group of five patiens received 250 mug/kg of hydralazine. Hemodynamic measurements were obtained before treatment, and then after 30--60 and 80-120 min. Cardiac output was evaluated by radiocardiography and myocardial perfusion by clearance of 86Rb. The antihypertensive effect of DL 150 IT was most pronounced 2 h after the injection, whereas by this time the increased heart rate and cardiac output tended to revert to the baseline values. On the contrary, the magnitude of these effects did not change during the observation period after hydralazine treatment. Both drugs increased myocardial perfusion. The new compound appears at least five times more potent than hydralazine and, possibly, has a longer duration of action.

Adult↗
PubMed1975

Folate metabolism in the rat liver during regeneration after partial hepatectomy.

1. Folate metabolism was studied during the early phases of liver regeneration after partial hepatectomy in rats accustomed to eating during the first 8h of a daily 12h dark period. 2. The content of 5-CH(3)-H(4)folate was drastically decreased during the first hours of regeneration. 3. The total HCO-H(4)folate coenzymes showed a constant decrease during the first 3 days of regeneration, and a continuous interconversion between 5-HCO-H(4)folate and 10-HCO-H(4)folate. 4. 10-HCO-H(4)folate synthetase, serine hydroxymethyl-transferase and 5,10-CH(2)-H(4)folate dehydrogenase activities were relatively low during the first hours after the operation, and increased only several hours later. 5. The increase in enzyme activities showed a stepwise pattern, apparently due to an interaction between the regeneration process and the controlled feeding schedules.

Animals↗
PubMed1975

Effect of surfactant monomers on chloramphenicol association to an albumin-lecithin complex: a model for modified drug absorption.

The binding of chloramphenicol to an albumin-lecithin complex in the presence or absence of premicellar concentrations of both ionic and non-ionic surfactants has been examined. Long chain, strong ionic detergents, such as sodium dodecyl sulphate or cetyltrimethylammonium bromide, severely perturb protein structure and eventually allow full separation of the complex into lecithin and albumin-detergent complexes. The dissociation process is reversible upon the removal of the detergent by exhaustive dialysis. After the splitting of the complex, the amount of antibiotic associated with the lipid-protein mixture increases. Structural alteration of the albumin-lecithin complex and the increase in the binding of chloramphenicol have an effect on the transfer rate of this antibiotic across an artificial barrier consisting of an aqueous dispersion of the same complex, as observed in a model system. It is suggested that a reversible alteration in membrane structure, and consequently in membrane permeability, might be easily effected, at the molecular level, through a reversible dissociation of structural lipoproteins into their components, operated by premicellar concentrations of ionic surfactants. This represents a tentative picture of the possible events taking place within the membrane and modifying the absorption rate of a drug, when it is associated with surfactants in a pharmaceutical preparation.

Absorption↗
PubMed1972

Effects of testosterone on the metabolism of folate coenzymes in the rat.

1. The effects of castration and testosterone treatment on enzymic activities involved in folate coenzyme metabolism in the liver and in accessory sex organs of male adult rats were studied. 2. In the liver of castrated rats the concentration of 10-formyltetrahydrofolate (10-HCO-H(4)folate) synthetase and tetrahydrofolate (H(4)folate) dehydrogenase were significantly decreased whereas that of 5,10-methylenetetrahydrofolate dehydrogenase increased; the treatment with five doses of testosterone caused a return to normal values of these activities. 3. In the prostate of castrated rats a pronounced decrease in H(4)folate dehydrogenase, serine hydroxymethyltransferase and 10-HCO-H(4)folate synthetase activities was observed. The administration of testosterone restored the enzymic activities to normal values. 4. In the seminal vesicles of castrated rats only 10-HCO-H(4)folate synthetase was markedly depressed; testosterone treatment not only restored activity to normal values but raised it to higher than normal values. The slight changes observed in other enzymic activities also returned to normal values with the hormone treatment. 5. These results are discussed in relation to a possible control mechanism of folate metabolism by testosterone.

Animals↗