60 research outputs found
Experimental studies on the pathogenicity of Vibrio mimicus strains isolated in Bangladesh
Vibrio mimicus, a newly described species of the genus Vibrio has been isolated from stools of 14 patients with diarrhoea. Live cells of all the 14 strains tested caused accumulation of fluid in rabbit gut loops and diarrhoea in infant rabbits. Culture filtrates of all the strains caused increased capillary permeability in rabbit skin; however, five of the filtrates resembled cholera toxin in that they gave positive reactions in rabbit loops, chinese hamster ovarian and mouse adrenal cell monolayers and GM1 ELISA tests and were neutralized by cholera antitoxin. None of the strains produced heat-stable toxin or possessed invasive capability as determined by Sereny's test. Thus, V. mimicus strains were divided into a group which produced a toxin immunobiologically similar to cholera toxin and the rest producing a heat-labile toxin unrelated to that of V. cholerae
Nuclear uncertainties in the NeNa-MgAl cycles and production of 22Na and 26Al during nova outbursts
Classical novae eject significant amounts of nuclear processed material into
the interstellar medium. Among the isotopes synthesized during such explosions,
two radioactive nuclei deserve a particular attention: 22Na and 26Al. In this
paper, we investigate the nuclear paths leading to 22Na and 26Al production
during nova outbursts by means of an implicit, hydrodynamic code that follows
the course of the thermonuclear runaway from the onset of accretion up to the
ejection stage. New evolutionary sequences of ONe novae have been computed,
using updated nuclear reaction rates relevant to 22Na and 26Al production.
Special attention is focused on the role played by nuclear uncertainties within
the NeNa and MgAl cycles in the synthesis of such radioactive species. From the
series of hydrodynamic models, which assume upper, recommended or lower
estimates of the reaction rates, we derive limits on the production of both
22Na and 26Al. We outline a list of nuclear reactions which deserve new
experimental investigations in order to reduce the wide dispersion introduced
by nuclear uncertainties in the 22Na and 26Al yields.Comment: 46 pages, 4 figures. Accepted for publication in The Astrophysical
Journa
Cholesterol Corrects Altered Conformation of MHC-II Protein in Leishmania donovani Infected Macrophages: Implication in Therapy
Previously we reported that Kala-azar patients show progressive decrease in serum cholesterol as a function of splenic parasite burden. Splenic macrophages (MΦ) of Leishmania donovani (LD) infected mice show decrease in membrane cholesterol, while LD infected macrophages (I-MΦ) show defective T cell stimulating ability that could be corrected by liposomal delivery of cholesterol. T helper cells recognize peptide antigen in the context of
class II MHC molecule. It is known that the conformation of a large number of membrane proteins is dependent on membrane cholesterol. In this investigation we tried to understand the influence of decreased membrane cholesterol in I-MΦ on the conformation of MHC-II protein and peptide-MHC-II stability, and its bearing on the antigen specific T-cell activatio
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