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Biomedical subjects

S A Filho

Publications and source records attributed to S A Filho.

5 recordsLinked to original sources
PubMed2000

Decrease in sperm number after treatment of rats with Austroplenckia populnea.

The purpose of this study was to evaluate the effects of a hexanic extract (HE) made from leaves of A. populnea collected in Botucatu, State of São Paulo, and Nova Lima, State of Minas Gerais, Brazil, at a range of doses during 7 and 14 days, on the male reproductive system of rats. The treatment did not affect the body weight, nor absolute organ weight. The serum testosterone levels, testicular sperm head counts, daily sperm production, and sperm morphology did not differ from that of the control groups. The spermatogenesis and the morphometric parameters of cauda epididymidis were not affected by the treatment. Cauda epididymis sperm number was significantly reduced in the group that received HE of Nova Lima, 1 g/kg/day, during 14 days, from the control group.

Animals↗
PubMed1984

Optimization of a protein synthesizing lysate system from Trypanosoma cruzi.

A protein-synthesizing lysate system from Trypanosoma cruzi epimastigotes analogous to the rabbit reticulocyte lysate system was established. The system was optimized by the 'classical' method where one of the factors is varied while the others are kept constant. With this the following optima were found: [Mg2+]: 1.0 mM, [K+]: 60 mM, T: 25 degrees C, pH: 7.5. This method was compared with the 'sequential simplex' method [Long, D.E. (1969) Anal. Chim. Acta 46,93-100], a method designed to optimize rationally interdependent factors in biological systems. The optima as determined with this method were: [Mg2+]: 1.02 mM, [K+]: 63 mM, T: 25.5 degrees C, pH: 7.25. At these values the system incorporated 43% more amino acids into proteins than a system optimized with the 'classical' method. Fluorographic analysis of the proteins synthesized by the system shows that while proteins in the molecular weight range between 14000 and 45000 are synthesized in amounts comparable to the in vivo situation, the higher molecular weight proteins (greater than 45000) are synthesized in lesser quantities.

Adenosine Triphosphate↗
PubMed1980

Morphologic and biochemical characterization of Crithidia brasiliensis sp. n.

A trypanosomatid with a choanomastigote stage and, therefore, belonging to the genus Crithidia, was isolated in culture from the alimentary tract of the hemipteran genus Zelus. The trypanosomatid was able to grow at 37 C, a characteristic reported to date from only 2 other members of Crithidia, C hutneri and C. luciliae thermophila. Subsequently, the flagellate was cloned for biochemical studies which involved cleaving of kDNA by restriction endonucleases and analyses of the isoenzyme and histone patterns. In all the attributes revealed by the foregoing methods, the organism from Zelus differed from the latter 2 congeneric species. On these and morphologic grounds, this organism appears to belong in a new species for which the name Crithidia brasiliensis sp. n. is proposed.

Animals↗
PubMed1978

The influence of hydroxyurea and colchicine on growth and morphology of Trypanosoma cruzi.

Cultures of Trypanosoma cruzi have been exposed to the drugs hydroxyurea and colchicine. We found that hydroxyurea (200 microgram/ml) completely inhibited growth and differentiation of T. cruzi Y strain. Colchicine (200 microgram/ml) reduced the growth of T. cruzi 30% and stimulated cell differentiation from epimastigotes to trypomastigotes. Furthermore it caused anuclear cells with apparently intact kinetoplasts. The possible use of these anuclear forms in studies on kinetoplast DNA organization and expression is suggested.

Colchicine↗