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Biomedical subjects

M S Gatti

Publications and source records attributed to M S Gatti.

16 recordsLinked to original sources
PubMed2001

Induction of apoptosis in HT29 human intestinal epithelial cells by the cytotoxic enterotoxin of Aeromonas hydrophila.

The cytotoxic enterotoxin produced by Aeromonas hydrophila is considered to be the main virulence factor in gastrointestinal infections mediated by this pathogen. In this study, we examined the morphological and apoptotic effects of this toxin on HT29 cells, using light and electron microscopy in situ, as well as agarose gel electrophoresis of cell DNA. Cells treated with the cytotoxic enterotoxin became round and lost their polarity as well as their adhesion to each other and to the substrate. Cytoplasmic blebbing and nuclear condensation also occurred. DNA fragmentation was detected by TUNEL labelling and agarose gel electrophoresis. These results show that the cytotoxic enterotoxin of A. hydrophila can induce apoptosis in human intestinal cells in culture.

Aeromonas hydrophila↗
PubMed1995

Plasmid coding for drug resistance and invasion of epithelial cells in enteropathogenic Escherichia coli 0111:H.

Enteropathogenic Escherichia coli (EPEC) can adhere to, invade and multiply in human epithelial cells. To define the elements required for bacterial invasion, we isolated from an 0111:H- EPEC a 6.6 kb plasmid that is capable of conferring to an avirulent, non-adherent E. coli K12 strain (DK1) the capacity to invade epithelial cells. With this system a dissociation was possible between bacterial invasion and adherence to epithelial cells. Bacteria containing this plasmid synthesise a protein of 32 kDa (pl 4.93) which seemed to be required for cell invasion. The results provide a new basis for strategies to prevent EPEC infections.

Animals↗
PubMed1993

Bluetongue virus: production and study of viral antigen for serological diagnosis.

A soluble antigen, produced from the culture supernatant of VERO cells infected with bluetongue virus serotype 4 (BTV-S4) and concentrated by sequential ultrafiltration with membranes with cut-off values 10(3) and 25 x 10(3) NMWP, showed complete identity to standard antigens when compared by agar gel immunodiffusion (AGID) and SDS-PAGE profiles, revealing that the main protein component responsible for the AGID reaction has a molecular weight of about 60 kDa corresponding probably to the NS1 protein.

Animals↗
PubMed1993

Rotavirus excretion in naturally infected pigs with and without diarrhoea.

Seven hundred and fifty faecal samples from piglets ranging from 1 to 60 days old were studied for the presence of group A rotavirus by polyacrylamide gel electrophoresis (PAGE) and by enzyme immunoassay (EIA). From 451 diarrhoeic pigs, 117 (25.94%) were positive for rotavirus and only 45 (15.05%) of 299 pigs without diarrhoea excreted the virus (P < 0.005). When these animals were separated into four age groups with regard to the presence or absence of diarrhoea, it was observed that the excretion of rotavirus was associated with diarrhoea in piglets, both before and after weaning.

Animals↗
PubMed1992

Comparison of indirect immunofluorescence with agar gel immunodiffusion for the diagnosis of bluetongue virus infection.

1. Sera from 190 cows and from 72 sheep were examined to compare the results obtained with the agar gel immunodiffusion (AGID) and indirect immunofluorescence (IIF) tests for the diagnosis of bluetongue (BT) disease. 2. In the AGID test, 96 of 190 (50.5%) cattle serum samples and 38 of 72 (52.7%) sheep serum samples were positive, for a total of 134 out of 262 (51.1%) sera. In the IIF test, 98 of 190 (51.6%) cattle serum samples and 39 of 72 (54.2%) sheep serum samples were positive, for a total of 137 out of 262 (52.3%) sera. 3. The fluorescence of the IIF test presented a granular cytoplasmic aspect, which in some cells was observed only on the cell membranes. 4. Statistical analysis of the data showed close agreement between the two techniques, regardless of the kind of sera examined. The IIF test showed high sensitivity (93.8% and 92.1%), specificity (91.4% and 88.2%) and positive (91.8% and 89.7%) and negative (93.48% and 90.9%) predictive values for cattle serum and sheep serum, respectively. 5. The results obtained with IIF were comparable to those obtained with the AGID test, indicating that both techniques can be used routinely in epidemiologic studies of BT. However, the IIF offers the additional advantages that it can be used for antibody quantification and for the detection of viral antigens in BT-infected cell lines.

Animals↗
PubMed1990

Different lethal effects by enzyme-generated triplet indole-3-aldehyde in different Escherichia coli strains.

Strains of Escherichia coli which lack 4-thiouridine (S4U) exhibit a higher survival rate than their wild-type parents which contain S4U after treatment with enzyme-generated triplet indole-3-aldehyde. In a similar manner to results obtained with monochromatic 334 nm UV light, the survival is related to single-strand breakage of DNA in E. coli containing the pBR 322 plasmid. The effects of the excited states generated by an enzymatic system suggest that S4U is an important chromophore in the lethal effects observed. The results also suggest that the energy transferred from triplet indole-3-aldehyde to S4U may also be passed from S4U of t-RNA to DNA, possibly through a singlet oxygen intermediate generated by excited S4U, resulting in a decrease in the survival rate of E. coli containing S4U. These results emphasize the importance of excited states in biological systems.

DNA Damage↗
PubMed1989

Presence of group A and non-A rotaviruses in neonatal piglets in Campinas, SP, Brazil.

Rotaviruses were detected by polyacrylamide gel electrophoresis (PAGE) in 11 (84.6%) of 13 faecal specimens from neonatal piglets with acute diarrhoea in a piggery near the city of Campinas, State of São Paulo, Brazil. An immunoenzimatic assay for group A rotavirus (IEA-A) was positive in ten of the samples, all of which showed a PAGE profile typical of that group. Another sample was showed a group B profile in PAGE. An immunoenzimatic assay specific for group B (IEA-B) for this faecal sample was positive, confirming the PAGE results.

Acute Disease↗
PubMed1989

Viruses with bisegmented double-stranded RNA in pig faeces.

Viruses similar to the bisegmented double-stranded (ds) RNA picobirnaviruses described in human faeces and the intestinal contents of Oryzomys nigripes rats and guinea pigs were isolated from the faeces of pigs taken from several areas in the state of Sao Paulo, Brazil. Samples were collected from 912 pigs of several breeds, aged nine to 61 days, and assayed by polyacrylamide gel electrophoresis with silver staining and a combined enzyme immunoassay for rotavirus and adenovirus, using the simian rotavirus SA11 as control. Electrophoretic profiles resembling the bisegmented dsRNA viruses were detected in 106 pigs with 15.3 per cent occurring in animals with diarrhoea compared to 9.6 per cent in animals without diarrhoea.

Animals↗
PubMed1986

Stability of thermolabile (LT) enterotoxin produced from enterotoxigenic Escherichia coli strains maintained in vitro.

The stability of thermolabile (LT) enterotoxin in 26 strains of porcine enterotoxigenic Escherichia coli (PETEC) belonging to serogroups 08 and 0149 was assayed by the passive immune hemolysis (PIH) test, over a period of 9 months at -70 degrees C. It was found that the percentage of LT+ colonies (% LT+) and the mean value of hemoglobin release (XHb), could predict a change from LT+ to LT-.

Bacterial Toxins↗
PubMed1982

Evaluation of a defined medium for the production of both thermolabile (LT) and thermostable (ST) enterotoxins of Escherichia coli.

The production of thermolabile (LT) enterotoxin was compared in a defined medium reported by Staples et al. (SAG medium) for the production of thermostable (ST) enterotoxin and the Casamino acids-Yeast extract (CAYE) medium. Aliquots were drawn frum cultures of an enterotoxigenic (LT+, ST+) E. coli in both media at different times, growth curves were plotted, and culture filtrates tested for toxin activity. Levels of LT and ST and in the SAG showed that it is as suitable as CAYE for the production of LT. The addition of either glucose (1%) or lincomycin (90 microgram/ml) to SAG medium increased LT levels, but no synergistic effort could be observed if both substances were added concomitantly. Cultures in SAG medium incubated stationarily for 72 h at 37 degrees C yielded more LT than shaking cultures incubated similarly.

Animals↗
PubMed1980

Improvements in the passive immune hemolysis test for assaying enterotoxigenic Escherichia coli.

The sensitivity of the passive immune hemolysis test for the detection of heat-labile enterotoxin from Escherichia coli was increased when the test was carried out with Veronal-buffered saline plus Ca2+ and Mg2+ as diluent, instead of phosphate-buffered saline. The performance of the test was further improved by using stationary cultures to which mitomycin C had been added at the end of the lag phase.

Adrenal Glands↗
PubMedDate not supplied

[The incidence of enterotoxigenic Escherichia coli, rotavirus and Clostridium perfringens from cases of diarrhea in children, in the region of Campinas, SP, Brazil].

A survey for the detection of enterotoxigenic Escherichia coli (ETEC), rotavirus and enterotoxigenic Clostridium perfringens in diarrheic stools of children up to 2 years old was carried out in the region of Campinas, SP, Brazil. Twenty-seven (20.45%) faecal specimens were positive for ETEC. From these samples 41 strains of ETEC were isolated from which 40 produced only thermolabile (LT) enterotoxin, as detected by a modified radial immune haemolysis test. Among the 183 faecal specimens examined for the detection of rotavirus, 29 (15.84%) were positive when examined by polyacrilamide gel electrophoresis (PAGE) and immunoenzymatic assay (EIA) being 15 (51.7%), derived from stools collected from winter months. All strains of rotavirus belonged to group A and through the PAGE technique, it was observed that the most frequent (9 strains) electrophoretype, according to the adopted classification, was Ib, IIc, IIIb, IVa. Only 113 fecal specimens were examined for the presence of enterotoxigenic C. perfringens. For the detection of enterotoxin in culture supernatants the reverse passive haemagglutination and intravenous inoculation of mice were used. Twelve (10.61%) enterotoxigenic C. perfringens strains were found. Taking into consideration these findings the authors call the attention of the relative value of conventional coprocultures for diagnostic purposes, pointing out the important of establishing simplified methods which would render easier, the detection and identification of the groups of enteropathogenic agents studied in this research.

Brazil↗
PubMedDate not supplied

Ultrastructural study of enteropathogenic Escherichia coli O111ab:H2 infection in an infant with acute diarrhea.

Enteropathogenic Escherichia coli is the most important cause of acute diarrhea in developing countries, specially in infants under one year of age. Enteropathogenic Escherichia coli strains are able to induce profound cytoskeletal alterations in the enterocyte known as attaching and effacing lesions, associated with the formation of cuplike pedestals. We report an Enteropathogenic Escherichia coli O11ab:H2 strain isolated from an infant with acute diarrhea, on the eleventh day of disease, that caused attaching and effacing lesion and penetrated the enterocyte, as well as invaded the HeLa cell tissue culture in vitro and the rabbit ileal loop assay in vivo, in the ultrastructural study. This observation indicates that the severe lesions of the small bowel caused by an enteropathogenic Escherichia coli O111ab:H2 strain can occur even in the early stages of the infection.

Acute Disease↗