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Biomedical subjects

S T Donta

Publications and source records attributed to S T Donta.

At least 55 records · Page 3Linked to original sources
PubMed1979

Replication of murine cytomegalovirus in murine Y-1 cells.

Murine Y-1 cells, a continuous epithelial cell line derived from an adrenal adenocarcinoma, are highly susceptible to murine cytomegalovirus (MCMV) infection. Inoculation of these cells with MCMV results in production of infectious virus and is associated with development of both cytopathic changes and the expression of viral-specific nuclear and cytoplasmic antigens. Examination of the ultrastructure of infected Y-1 cells reveals MCMV in various stages of replication. Cytomegalovirus replication in this hormone-responsive epithelial cell line should provide a model system in which virus--host cell interactions and their effects on cellular metabolism can be studied.

Adenocarcinoma↗
PubMed1979

Effect of antibiotics on the adherence of enterobacteriaceae to human buccal cells.

Antibiotics at bacteriostatic concentrations (four times the minimal inhibitory concentration) decreased the attachment of Enterobacteriaceae to human buccal cells in vitro and augmented the reversibility of such adherence. These actions of antibiotics may influence colonization by nosocomial bacteria and the subsequent infection that they cause.

Anti-Bacterial Agents↗
PubMed1979

Specificity of attachment of certain enterobacteriaceae to mammalian cells.

The specificity of adherence of various Enterobacteriaceae to different mammalian cells was studied in vitro. 3H-Labelled organisms of the same species isolated from various clinical sources differed significantly in their abilities to adhere to the same mammalian cells. Bacteria frequently adhered better to cells derived from sites other than those analogous to their original source. Bacteria did not display consistently 'high' or 'low' attachment to a variety of human and tissue-cultured cells and little selective adherence was demonstrable.

Adrenal Glands↗
PubMed1979

Adherence of Enterobacteriaceae to human buccal cells.

A preliminary examination has been made of the adherencae isolated from sputa. The radioadherence method was found to correlate well with the conventional light-microscope adherence technique. Saturation of buccal-cell binding sites with bacteria occurred when less than 10% of the buccal-cell surface was occupied. The adherence of Enterobacter aerogenes to buccal cells was impaired by the prior adherence of bacilli of either the same strain, or of a strain of Klebsiella pneumoniae.

Adhesiveness↗
PubMed1978

Mycobacterium gordonae infection of a prosthetic aortic valve.

A patient prviously suspected of having a mycobacterial infection was found to have a Mycobacterium gordonae infection of his prosthetic aortic valve. Following replacement of his infected prosthesis and systemic therapy for two years, the patient has apparently been cured.

Aortic Valve↗
PubMed1978

Gap junctions and ACTH sensitivity in Y-1 adrenal tumor cells.

Initial studies of adrenocorticotropin-sensitivity (ACTH-sensitive) and ACTH-insensitive Y-1 adrenal cortical tumor cell lines suggest a relationship between responsiveness to ACTH and the presence of gap junctions. An ACTH-sensitive clone of Y-1 cells possesses gap junctions and these junctions appear to enlarge with ACTH treatment. GAP junctions have not been observed, however, in an ACTH-insensitive clone of Y-1 tumor cells even when stimulated to produce cyclic adenosine monophosphate and steroids with cholera toxin.

Adrenal Gland Neoplasms↗
PubMed1978

Cytotoxic activity of Aeromonas hydrophila.

Most strains of Aeromonas hydrophila tested demonstrated cytotoxic activity on several tissue-cultured cell lines. The cytotoxin is heat-labile, non-dialyzable, and immunologically distinct from that of Shigella dysenteriae and Clostridium perfringens. None of the aeromonas isolates was found to be enterotoxigenic by either tissue culture or rabbit ileal loop assays.

Adenylyl Cyclases↗
PubMed1978

The efficacy of rifampin as adjunctive therapy in selected cases of staphylococcal endocarditis.

Three patients with bacterial endocarditis (one case due to Staphylococcus aureus and two to S epidermidis) failed to improve on standard therapeutic regimens which were judged adequate by in vitro testing for sensitivity. Rifampin was added to the regimen in each case and resulted in increased bactericidal activity in the serum, sterilization of the cardiac valves, and clinical cure. The apparent clinical success that was achieved suggests that further investigation of the effectiveness of therapy with rifampin in selected cases of staphylococcal endocarditis is warranted.

Adult↗
PubMed1978

Antibody to Escherichia coli enterotoxin in meat-packing workers.

Meat-packing plant employees exposed to raw animal products had serological evidence of higher infection rates with heat-labile toxin producing enterotoxigenic Escherichia coli (LT-EEC). In those employees with multiple sera available for study over a ten-year period, a drop in mean anti-LT-EEC titer was observed, suggesting altered ecology of or exposure to the organism during this time. Prospective studies need to be done to determine if meat-packing workers actually experience a greater incidence of LT-EEC-induced diarrheal disease.

Adult↗
PubMed1977

Enterotoxigenic Escherichia coli and diarrheal disease in Mexican children.

Enterotoxigenic strains of Escherichia coli were isolated from eight (16%) of 50 Mexican children admitted to the hospital with diarrhea and from one of 50 children hospitalized for nonenteric disorders. All of the toxigenic strains tested elaborated a heat-labile enterotoxin, and in seven of nine patients no E. coli capable of concomitant production of heat-stable enterotoxin were found. None of the strains of E. coli with classical enteropathogenic serotypes isolated from nine patients with diarrhea produced either heat-labile or heat-stable enterotoxin. Although the results of this study strongly suggest that enterotoxigenic strains of E. coli are probably responsible for a significant number of cases of diarrhea in an indigenous Mexican pediatric population, further proof will require demonstration of in vivo production of enterotoxin and/or antitoxin.

Bacterial Toxins↗
PubMed1976

Interactions of choleragenoid and GM1 ganglioside with enterotoxins of Vibrio cholerae and Escherichia coli in cultured adrenal cells.

The heat-labile enterotoxins of Vibrio cholerae and Escherichia coli induce morphologic changes and steroidogenesis in clonal lines of adrenal tumor cells in tissue culture; these effects are preventable by prior incubation of either toxin with GM1 ganglioside (galactosyl-N-acetylgalactosaminyl [sialosyl] lactosyl ceramide; GGnSLC) but are not preventable by prior incubation of adrenal cells with choleragenoid. Choleragenoid, however, is capable of interfering with the ability of GM1 ganglioside to neutralize the effects of either toxin. These results suggest that the GM1 ganglioside may not be the true receptor for the toxins on adrenal cells, but that it is acting as a pseudoreceptor. The ability of a subunit (A) of the cholera enterotoxin molecule to induce in adrenal cells morphologic changes and steroidogenesis similar to those effects inducible by the whole toxin indicates the possibility that separate receptor sites on these adrenal cells may exist for the binding and active fragments of the molecule.

Adrenal Gland Neoplasms↗
PubMed1976

Morphological and steroidogenic changes in cultured adrenal tumor cells induced by a subunit of cholera enterotoxin.

A purified subunit of the cholera enterotoxin molecule was found to have morphological and steroidogenic inducing effects similar to those induced by the native enterotoxin on monolayer tissue cultures of Y1 adrenal tumor cells, although 1,000 times more subunit than toxin (weight basis) was required for maximal effects. In contrast to the whole toxin, the effects of the active subunit could not be prevented by prior incubation with either Gm1 ganglioside or with antibodies directed against choleragenoid (the binding subunit). These results suggest that different receptor sites may exist on cells for the binding and for the active subunits of cholera enterotoxin and/or that the active toxin fragment may exert its effects after gaining access to the intracellular compartment.

Antibodies, Bacterial↗
PubMed1976

Serum antibody to Escherichia coli heat-labile enterotoxin in cattle and swine.

Antibody titers to Escherichia coli heat-labile enterotoxin (LT) were measured in serum samples collected from mature cows, butcher pigs, mature sows and adult sheep, horses, dogs, cats, turkeys, and chickens. The frequency of LT antitoxin titers was greatest in sows (94%) and less in cows (38%). Titers were higher in swine than in cattle. There were no LT antitoxin titers in serums from sheep, horses, dogs, cats, turkeys, and chickens. It was concluded that LT-producing Escherichia coli are prevalent in the swine population, but much less so in cattle and the other species examined.

Animals↗
PubMed1975

Classification of enterotoxins on the basis of activity in cell culture.

Two cell culture systems were used in a study of the biological properties of several bacterial enterotoxins in vitro. By means of one model, in which HeLa cell monolayers were used, cytotoxic effects, interms of detachment of cells from a glass surface due to cell death, were assayed. By means of the second model, activation of the adenyl cyclase-cyclic adenosine 3', 5'-monophosphate (AMP) system, in terms of increased steroidogenesis by Y-1 adrenal cells (an effect which we have termed cytotonic), was assayed. None of the four toxins manifested both properties. Rather there was a clear segregation into two cytotoxic enterotoxins (Shigella dysenteriae type 1 and Clostridium perfingens) and two cytotonic products (Vibrio cholerae and Escherichia coli). These data raise the possibility that some enterotoxins may not interact with the adenyl cyclase-cyclic AMP system; this possibility has also been suggested by studies of the toxin of S. dysenteriae type 1 in the rabbit small bowel. These cell culture systems may therefore serve as convenient models for the study of the mechanism of action of both classes of enterotoxin.

Adenylyl Cyclases↗
PubMed1975

Inhibition of the steroidogenic effects of cholera and heat-labile Escherichia coli enterotoxins by GM1 ganglioside: evidence for a similar receptor site for the two toxins.

The effects of three different ganglioside preparations on cholera enterotoxin (CT) and heat-labile Escherichia coli enterotoxin (ECT)-induced steroidogenesis in Y1 and OS3 adrenal tumor cells in tissue culture were examined. Only with GM1 ganglioside was any inhibition of the toxins' effects noted. Concentrations of the crude ECT preparation that gave similar morphogenic and steroidogenic effects as CT were inhibited by the same amount or less of GM1 as that required to inhibit the effects of CT. The results of competition experiments also demonstrated that previous incubation of GM1 with one toxin could inhibit the ganglioside's ability to inactivate the other toxin. These findings indicate that at least for Y1 and OS3 adrenal tumor cells, GM1 may resemble or be the receptor for both CT and ECT.

Adrenal Gland Neoplasms↗