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Biomedical subjects

R A Neal

Publications and source records attributed to R A Neal.

At least 19 recordsLinked to original sources
PubMed1979

A comparison of challenge with Trypanosoma cruzi blood-stream trypomastigotes and metacyclic trypomastigotes from Rhodnius prolixus in mice immunized with killed antigens.

Groups of CD-1 mice were immunized with vaccines prepared from freeze-thawed or ultra-sonicated epimastigotes, blood trypomastigotes, or "plasma antigen", of Trypanosoma cruzi strains Y, M1 and Tulahuen. The mice were challenged by the injection of blood stream trypomastigotes obtained from mice, or of metacyclic trypomastigotes harvested from the rectum of Rhodnius prolixus. Both challenges induced virulent infections in control mice. Blood-stream trypomastigotes killed mice more rapidly than the same number of bug-derived trypomastigotes. Vaccinated mice resisted infection with bug-derived trypomastigotes as well as with blood trypomastigotes, and in some instances better. It is concluded that results obtained with the more convenient, but artificial blood trypomastigote challenge are comparable with the more natural, bug-derived, challenge.

Animals↗
PubMed1977

Effect of chronic ethanol administration on thiamin metabolism in the rat.

The effect of chronic alcohol administration on the absorption, excretion and metabolism of thiamin in the rat has been examined. In ethanol-fed rats receiving a marginal daily intake of thiamin (10 microgram/day) by stomach tube or by intraperitoneal injection, less of the vitamin and its metabolites were excreted in the urine as compared to controls administered the same diet except that sucrose replaced the energy represented by ethanol. More of the oral dose of thiamin was excreted in the feces of the ethanol-fed as compared to control rats. These data support previous reports of decreased adsorption of thiamin from the gut in animals exposed to ethanol. The studies in which the thiamin was administered by intraperitoneal injection also indicate an effect of ethanol on thiamin excretion in the urine which appears not to be related to absorption of the vitamin from the gut. An examination reveals no difference in the level of thiamin and its metabolites in the tissues of ethanol-fed as compared to control rats receiving thiamin by stomach tube. Thus, the decreased absorption of thiamin from the gut in the ethanol-fed rats seems to be balanced by a decreased excretion in the urine leading to a comparable accumulation of the vitamin in the tissues as controls.

Alcoholism↗
PubMed1977

Comparison of infectivity of Trypanosoma cruzi blood stream trypomastigotes and metacyclic trypomastigotes from Rhodnius prolixus.

Four strains of Trypanosoma cruzi (Y, BG, M and Peru) retain their ability to infect Rhodnius prolixus and to produce virulent infections in mice for from 12 to 39 years. About 60 or more metacyclic trypomastigotes were consistently lethal to mice. The mean number of metacyclics per bug ranged from 1.2 to 17.3 x 10(3). Comparative studies of virulence of metacyclics and blood trypomastigotes showed the blood forms to be slightly more virulent. The route of injection was shown to be more significant in varying the host response to infection, subcutaneous inoculation being the preferred route.

Animals↗
PubMed1977

Immunization against Trypanosoma cruzi using killed antigens and with saponin as adjuvant.

The immunization of mice with killed epimastigotes or trypomastigotes with saponin SPL as adjuvant was challenged by inoculation of blood or metacyclic trypomastigotes of T. cruzi. Immunogenic preparations were obtained by freeze-thawing of formalin treatment. The protection was effective against homologous and heterologous challenge, and lasted up to 12 weeks after the last immunization. The immunization was also effective against metacyclic trypomastigote challenge. The immunogenicity of the killed T. cruzi suspension was retained after freeze-drying.

Adjuvants, Immunologic↗