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Biomedical subjects

R Colombo

Publications and source records attributed to R Colombo.

At least 199 records · Page 11Linked to original sources
PubMed1981

Actin in Xenopus development: indirect immunofluorescence study of actin localization.

Actin was studied in Xenopus unfertilized eggs and early developmental stages. Immunochemical proof is given of structural differences between Xenopus laevis muscle actin and nonmuscle cell actin. Actin localization and changes of actin aggregation during Xenopus development were observed using indirect immunofluorescence. We have also tried to explain the presence of an actin shell around the yolk platelets that appeared in our experiments.

Actins↗
PubMed1981

Drugs affecting porphyrin and lipid metabolism in rats: effects exerted by allylisopropylacetamide and related molecules.

Allylisopropylacetamide (AIA), a drug known to cause lesions in porphyrin and lipid metabolism, and drugs with structure related to AIA [propylisopropylacetamide (PIA) and 2-isopropyl-4-hydroxyvaleric acid] were injected subcutaneously into rats. Measurements were taken of the effect of these compounds on the levels of 5-aminolevulinic acid synthetase (ALA synthetase) and hepatic porphyrins and on the values of hepatic and plasmatic triglycerides and plasma free fatty acids. To a different degree, both AIA and PIA increase the activity of ALA synthetase, and also increase the levels of hepatic porphyrins and hepatic and plasmatic triglycerides, while they both initially lower the levels of plasmatic free fatty acids (FFAs). The administration of 2-isopropyl-4-hydroxyvaleric acid has no effect on the parameters studied. The findings seem to suggest that the activity affecting porphyrin and lipid metabolism is connected in both cases with the presence of the amide function.

5-Aminolevulinate Synthetase↗
PubMed1981

Liquid-phase synthesis of naturally occurring peptides, I. Syntheses of leucine-enkephalin and methionine-enkephalin of a p-alkoxybenzyl-modified soluble support.

The liquid-phase synthesis of two pentapeptides corresponding to the amino acid sequence of Leu- and Met-enkephalin is described. Modified monofunctional poly(ethylene glycol) containing a p-alkoxybenzyl alcohol functional group was employed as the soluble polymeric support. Cleavage of the peptides from the polymer, as well as the removal of protecting groups, was achieved with trifluoroacetic acid at room temperature. The free peptides were purified by column chromatography on DEAE-Sephadex, and were identical in both physical and biological characteristics with reference material. The results showed that the proposed support is effective for a mild cleavage of peptides from the soluble polymer during liquid-phase synthesis.

Amino Acids↗
PubMed1981

Liquid-phase synthesis of naturally occurring peptides, II. Syntheses of three mast cell degranulating tetradecapeptide amides from wasp venoms.

The liquid-phase synthesis of three tetradecapeptideamides corresponding to the amino acid sequences of the wasp venoms mastoparan, mastoparan X, and Polistes mastoparan is described. The 4-(aminomethyl)-3-nitrobenzoyl-amino-poly(ethylene glycol) monomethyl ether was employed as the soluble support, and the completed peptideamides were cleaved from it by photolysis at 350 nm. After removal of protecting groups, the free peptide amides were purified by column chromatography on Sephadex G-25, and found to have expected elemental and amino acid composition; a satisfactory recovery of tryptophan from synthetic Mastoparan X and Polistes Mastoparan suggests that no extensive destruction of its indole ring occurred during the photolysis. The peptideamides so obtained are active in degranulating the rat peritoneal mast cells.

Amino Acid Sequence↗
PubMedDate not supplied

Characterization of the chlorpropamide-alcohol-flush in patients with type 1 and type 2 diabetes.

The aim of the present paper was to evaluate the prevalence of the chlorpropamide-alcohol-flush (CPAF) in patients with type 2 and with type 1 diabetes. Ninety-seven patients with type 2 diabetes and 33 with type 1 diabetes drank 40 ml vermouth 12 h after placebo and again 12 h after 1 tablet of chlorpropamide (250 mg) or 12 h after the last of repeated administrations of chlorpropamide (250 mg b.i.d. for 2 days). Skin temperature was recorded in all patients by a thermocouple probe connected to the left cheek. In 47 patients serum concentrations of chlorpropamide and of its metabolite CBSU were also determined. The prevalence of CPAF was similar in type 1 and type 2 diabetes, was greater in women than in men, and was significantly greater after repeated administrations than after one single administration of chlorpropamide. The increase of skin temperature during a 30-min period was significantly higher in patients with CPAF than in patients without CPAF. Serum concentrations of chlorpropamide and of its metabolite CBSU were more elevated after 4 than after 1 tablet of chlorpropamide, but were not significantly different in patients with and without CPAF. These data indicate that both genetic factors and the amount of chlorpropamide used affect the appearance of CPAF. To assess the possible role of serotonin and of dopamine in the CPAF, some patients with CPAF were tested again after treatment with metergoline, an antiserotonin agent, or with bromocriptine, a dopamine-agonist. Neither drug influenced the CPAF, indicating that the two neurotransmitters are not involved in the CPAF.

Bromocriptine↗