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Biomedical subjects

A F de Castro

Publications and source records attributed to A F de Castro.

27 records · Page 2Linked to original sources
PubMedDate not supplied

Erythrocyte receptors for cholera and heat-labile enterotoxins of Escherichia coli.

Many serological reactions using red blood cells (RBC) such as radial immune haemolysis (RIH) and indirect haemagglutination (IH) tests have often been used for the detection of cholera toxin (CT) and heat-labile (LT) enterotoxin produced by porcine and human Escherichia coli strains. In these tests, the enterotoxins bind to sheep, bovine and guinea-pig RBC without any ligand. We studied several factors which might interfere with such binding, as well as the nature of the receptors involved. Treatment of erythrocytes with different enzymes revealed that proteolytic enzymes had no effect on the adsorption of enterotoxins to RBC. Conversely, treatment with neuraminidase increased the adsorption. Experiments carried out with delipidized RBC revealed that none of the enterotoxins under study bound to the cells thus treated. Pre-incubation of ganglioside fractions with the enterotoxins blocked RIH and IH reactions and the biological effect of them on Vero cells. Assaying RBC ganglioside fractions by thin-layer chromatography revealed the presence of GM1. Our results suggest that the receptors for GT and LT enterotoxins in sheep, bovine and guinea pig RBC are gangliosides: mainly GM1.

Absorption↗
PubMedDate not supplied

Research of antigen and antibodies from retroviruses, CMV and HBV among prisoners of the penitentiary complex of the region of Campinas, SP, Brazil.

Some viruses of the families Retroviridae, such as Human T Lymphotropic Virus (HTLV); Herpesviridae as the Cytomegalovirus (CMV) and Hepadnaviridae such as the Hepatitis B Virus (HBV) are liable to be co-transmitted with the Human Immunodeficiency Virus (HIV). Since prisoners are exposed to several and important risk factors involved in the transmission of HIV and the above mentioned viruses, male inmates from the penitentiary complex of Campinas, SP, Brazil, including HIV+ and HIV- ones, were examined for the presence of HTLV-I and/or II antibodies; IgG and IgM anti-CMV antibodies, and the research of the superficial hepatitis B antigen (HBsAg). The presence of anti-HTLV-I and/or II was determined by the Western Blot (WB) technique, whereas IgG and IgM anti-CMV and the search of HBsAg were carried out by the Microparticle Enzyme Immunoassay (MEIA-Abbott Lab). With regard to anti-HTLV-I and/or II, 58.3% (14/24-Number of positive reactions/number of sera examined) were reactive among the anti-HIV positive sera. Conversely, only 12.5% (3/24) among the HIV- negative sera showed positive reactions to HTLV-I and/or II antibodies. When looking for IgG anti-CMV percentages of 97.7% (43/44) and 95% (38/40) were obtained for anti-HIV positive and negative sera, respectively. As to IgM anti-CMV antibodies 11.36% (5/44) and 2.5% (1/40) of reactive sera were found for anti-HIV positive and negative, respectively. The HBsAg was found in 12.8% (5/39) of the sera which were anti-HIV positive.

Antibodies, Viral↗
PubMedDate not supplied

Use of an indirect haemagglutination test for the detection of Clostridium perfringens type A enterotoxin.

An indirect haemagglutination (IH) test is described for the detection of Clostridium perfringens type A enterotoxin, produced by strains isolated from human cases of food poisoning and from contaminated food. Though no strict relationship could be observed between titers in the IH test and the time it took mice to die from the intravenous inoculation of mice (IIM test), results of the supernatants examined by both methods demonstrated that the IH test was more sensitive than the IIM one. No unspecific reaction was obtained in the IH with a negative control and the inhibitions of the IH and IIM tests by specific antiserum against C. perfringens enterotoxin showed that the IH test is very specific. The IH assay is recommended for its sensitivity and easy performance by less-equipped laboratories, by these and other data.

Clostridium perfringens↗