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Biomedical subjects

R Bossa

Publications and source records attributed to R Bossa.

82 records · Page 5Linked to original sources
PubMedDate not supplied

The effects of roxatidine on neuromuscular transmission.

We have investigated the effects of the H2 receptor antagonist roxatidine on the neuromuscular transmission by using the sciatic nerve-gastrocnemius muscle preparation of the rat in vivo. Roxatidine, administered by i.v. injection, potentiates the neuromuscular blockade induced by d-tubocurarine, pancuronium and aminoglycoside antibiotic, kanamycin. Moreover, the drug alone is capable of producing a blockade on the preparation stimulated at high frequency. The neuromuscular blockade induced by roxatidine is partially reversed by 4-aminopyridine but not by dimaprit.

4-Aminopyridine↗
PubMedDate not supplied

Antitumor and cardiotonic activity of imidazo[2,1-b]thiazole guanylhydrazones.

A number of imidazo[2,1-b]thiazole guanylhydrazones, whose antitumor activity has already been described, were tested as potential cardiotonic agents. The guanylhydrazone of 2,3-dihydro-6-chloroimidazo[2,1-b]thiazole-5-carboxaldehyde (2a) was the most interesting compound showing both antitumor and cardiotonic activity.

Animals↗
PubMedDate not supplied

Glycyrrhizin and 18 beta-glycyrrhetinic acid: a comparative study of the pharmacological effects induced in the rat after prolonged oral treatment.

Recent clinical and toxicological studies have investigated the mineralcorticoid-like and hypertensive effects of liquorice, and we therefore set out to identify the active component responsible for these effects. We conducted a 30-day comparative analysis of glycyrrhizin and 18 beta-glycyrrhetinic acid and found that the latter causes significant variations both in systolic blood pressure and in the excretion in the urine of Ca++. The effects were fully reversible on suspension of treatment.

Administration, Oral↗
PubMedDate not supplied

Potential antitumor agents. XXII. Synthesis and cytotoxic activity of imidazo [2,1-b]thiazole adamantylthioureas.

A series of imidazo[2,1-b]thiazole adamantylthioureas (3a-f) was synthesized by reaction of the methylsulfanylethylamines 2a-f (prepared in turn from the hydroxymethylimidazo[2,1-b]thiazoles 1a-f and cysteamine) with 1-adamantylisothiocyanate. 1-Adamant-1-yl-3-[2-(6-chloro-2,3- dihydroimidazo[2,1-b]thiazol-5-ylmethylsulfanyl)ethyl] thiourea (3d) was significantly active.

Animals↗
PubMedDate not supplied

Influence of glycyrrhizin on the evolution and respiration of Ehrlich ascites tumour cells.

It has been demonstrated that 18 alpha-glycyrrhetinic acid, 18 beta-glycyrrhetinic acid and glycyrrhizin effectively inhibit the inception and growth of skin tumours. Moreover, glycyrrhizin and its aglycone act on the growth and differentiation of mouse melanoma cells in culture. In this study we investigated the effect of glycyrrhizin, 18 alpha- and 18 beta-glycyrrhetinic acids on the evolution of Ehrlich ascites tumour in mice. A prolonged glycyrrhizin treatment proved to be effective in modifying the animals' survival pattern.

Animals↗
PubMedDate not supplied

Reduction of adriamycin cardiotoxicity by enoximone.

Several non catecholamine, non glycoside cardiotonic drugs have been described recently. New compounds include amrinone, sulmazole, milrinone and pimobendan. In an attempt to alleviate or prevent anthracycline toxicity, we have reported that these compounds reduce the negative effects of adriamycin, 4-epiadriamycin and esorubicin in isolated guinea pig atria. The present study reports the effects of a new cardiotonic agent: enoximone. Enoximone was administered after adriamycin (100 micrograms/ml) on the isolated and spontaneously beating atria, and on electrically driven left atria of guinea pig-in normodynamic and hypodynamic conditions. Exposure for 60 minutes to the antitumor drug causes a depression of contractile force (g) and its derivative versus time (dF/dt, as maximal rate of contractile force). The negative effects of adriamycin are antagonised by enoximone (100, 200 micrograms/ml).

Animals↗
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Synthesis and cytotoxic activity of peptides containing basic amino acids residues.

We synthesized eight peptides containing from three to twenty residues of arginine, lysine and histidine, using an automated synthetiser and Fmoc strategy. All peptides were purified by preparative reverse-phase HPLC and characterized by electrospay mass spectometry. Cytotoxic activity was assessed on HeLa cells. One peptide inhibited the colony-forming ability of tumor cells.

Amino Acid Sequence↗
PubMedDate not supplied

Antitumor activity of an alkylating derivative of dipyridamole.

Synthesis of 2,6-Bis[bis(2-chloroethyl)amino]-4,8-dipiperidino-pyrimido [5,4-d]pyrimidine (DIP-C1) was carried out, and the new derivative showed cytotoxic activity comparable to other alkylating drugs on cultured P388 leukaemia cells and HeLa cells. The present paper reports the effects of DIP-C1 on respiration of Ehrlich ascites tumor cells and on survival of the mice implanted with Ehrlich ascites tumor cells. The compound showed a significant activity in both experimental models.

Animals↗
PubMedDate not supplied

Enhancement of cytotoxic activity by synthesis of peptide multimeric forms.

Synthesis of four multimeric H-Lys-His-His-Arg-Lys-Lys-His-Arg-Lys-Arg-Lys-His-His-Lys-Arg-Lys-oH peptides containing two, four, eight and sixteen branches was carried out by solid phase utilizing a lysine core matrix. These multimeric peptides enhanced activity by inhibiting the colony-forming ability of HeLa cells, from twenty-four to fifty-six times in comparison with the monomeric form. Unexpectedly the peptide with only two-branched sequences showed the highest inhibitory activity.

Amino Acid Sequence↗