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Biomedical subjects

M Shibata

Publications and source records attributed to M Shibata.

At least 757 records · Page 42Linked to original sources
PubMed1982

Responses of preoptic thermosensitive neurons to mediobasal hypothalamic stimulation.

Single-unit responses of preoptic-anterior hypothalamic (PO/AH) thermosensitive neurons to electrical stimulation of the mediobasal hypothalamus (MBH: ventromedial and arcuate nuclei) have been studied in urethane-anesthetized male rats. About half of thermosensitive neurons (46.4% of 69 warm-units and 50% of 28 cold-units) were initially inhibited following MBH stimulation with latencies up to 51.2 msec, while only 29.7% of 91 thermally insensitive units showed the inhibitory response. Orthodromic excitation of spontaneous activity was observed in 17.6% of the units (13.0% of warm-units, 14.3% of cold-units and 21.9% of insensitive units) with the onset latencies between 1.0 and 41.3 msec. A small proportion of neurons (5.3%) were antidromically activated by MBH stimulation, and the estimated conduction velocities of these neurons ranged from 0.11 to 0.67 m/sec. The results suggest reciprocal connections between PO/AH thermosensitive neurons and MBH, which may play some roles in thermoregulation and, also, in functional interactions between thermoregulation and other vital functions controlled in the hypothalamus.

Animals↗
PubMed1982

Lack of carcinogenicity of butylated hydroxytoluene on long-term administration to B6C3F1 mice.

Groups of approximately 50 male and 50 female B6C3F1 mice were given butylated hydroxytoluene (BHT) at concentrations of 200, 1000 or 5000 ppm in their diet for 96 wk followed by a basal diet for 8 wk and were then killed. Similar groups of male and female controls were given basal diet throughout the 104 wk. Females given 1000 or 5000 ppm BHT and males given 5000 ppm showed reduced weight gain. Neither survival rates nor food consumption differed between experimental and control groups. No significant changes attributable to BHT treatment were found in the haematological examinations or serum and urine analyses. Tumours were found in many organs, especially the lungs, liver, lymph nodes and spleen, in both the experimental and control groups, but none were related to BHT treatment. Thus this experiment provided no evidence of BHT carcinogenicity in mice.

Animals↗
PubMed1982

Role of viral glycoproteins in haemolysis by influenza B virus.

Influenza B virus exhibited haemolytic activity at low pH, but the pH profile for its activity varied from strain to strain. The results of selective heat-inactivation of the enzyme activity of neuraminidase (NA) or elimination from virions of the enzyme-active portion of the NA molecule by trypsin digestion, suggest that proteolytically cleaved haemagglutinin, but not enzyme activity of NA, is essential for haemolysis by influenza B virus.

Animals↗
PubMed1982

Stress procedures lowering body temperature augment gastric motility by increasing the sensitivity to acetylcholine in rats.

Exposure of rats to restraint plus water-immersion (25 degrees C) stress produces a marked increase in gastric motility with hypothermia. Although this phenomenon was generally considered to be due to centrally mediated cholinergic mechanisms, the present study was designed to elucidate some local peripheral mechanism in enhancing gastric motility with hypothermia. After the onset of water-immersion (37-17 degrees C), body temperature rapidly varied depending on water temperature and gastric motility changed in its pattern with stress duration; increase in gastric motility reached a maximum at 25 degrees C but declined at 17 degrees C. These alterations of gastric motility pattern were not primarily associated with activation or decline of the sympatho-adrenal system. In these stressed rats, either vagally intact or vagotomized, contractile responses of the stomach to i.v. or i.a. administration of bethanechol and acetylcholine, but not to that of histamine, were markedly augmented by lowering body temperature. Similar observations were noted in rats exposed to restraint plus cold (6 degrees C) stress. These results emphasize the possibility that augmentation of gastric motility during water-immersion (25 degrees C) occurs at least in part through local peripheral mechanisms of increasing the contractile sensitivity of the stomach to acetylcholine with hypothermia.

Acetylcholine↗
PubMed1982

Suppression of the polyclonal B-cell response to lipopolysaccharide by concanavalin-A-treated non-T cells in vitro.

Concanavalin A (Con A), a T-cell mitogen, dose-dependent suppressed the polyclonal antibody response of a purified B-cell population to lipopolysaccharide (LPS) in vitro. This suppression can be attributed to a role of suppressor cells generated in B-cell cultures in response to relatively high doses of Con A. The suppressor cells can be produced in cultures of normal as well as athymic nude spleen cells deprived of plastic-adherent cells and Thy 1.2 positive cells. The suppressing activity of Con-A-treated cells was not abolished by pre-treatment of the cells with anti-Thy 1.2, anti-Lyt 1.1, anti-Lyt 1.2 or anti-Lyt 2.2 serum and complement, and was decreased partially by treatment with anti-Ig serum and complement. Moreover, the suppressing activity was partially decreased by using petri dishes coated with IgG of F(ab')2 fraction of anti-mouse immunoglobulins. Thus, the suppressor activity of Con-A-treated cells was mediated by a non-T cell, possibly a B cell. A role for macrophages was unlikely, but not formally ruled out. The suppressor cells retarded development of polyclonal antibody production by B cells to LPS only when added at the start of culture and was resistant to treatment with anti-mitotic doses of irradiation and mitomycin C. It is possible that the suppressor cells of a B-cell nature play a role in the regulation of excessive B-cell proliferation during antibody responses.

Animals↗
PubMed1982

Carcinogenic effect of carbazole in the liver of (C57BL/6N x C3H/HeN)F1 mice.

The carcinogenic effect of carbazole (9H-carbazole) in (C57BL/6N X C3H/HeN)F1 (B6C3F1) mice was examined. Groups of 50 mice of both sexes were given a basal diet containing 0.6, 0.3, or 0.15% carbazole for 96 weeks and were then placed on an unsupplemented basal diet until they were killed at week 104. Mice surviving longer than 52 weeks were included in effective numbers. Significant increases in the induction of neoplastic lesions were found in the livers and forestomachs of mice given carbazole as compared to the control groups. The lesions in the livers were classified into two types, neoplastic nodules or hepatocellular carcinomas. The incidences of both types of lesions were almost 100% in mice treated with carbazole, and both types of lesions were significantly increased in all mice except the males given 0.6% carbazole in their diet. The incidences of hepatocellular carcinomas were in general higher than those of neoplastic nodules. Though not statistically significant, increased incidences of pulmonary metastases were found in the groups given carbazole. Significantly increased incidences of neoplastic lesions and papillomas in the forestomach in all groups of female and male mice were also noted in the mice fed 0.6% carbazole. Squamous cell carcinoma induction was significantly different in male mice given 0.6% carbazole as compared to controls. These results indicate that carbazole is carcinogenic to the liver and forestomach in B6C3F1 mice and suggest that carbazole may be an environmental carcinogen relevant to cancer risk in humans.

Animals↗
PubMed1982

Activation of polyclonal antibody responses by a synthetic serum thymic factor (FTS) in CBA/N mice.

A synthetic serum thymic factor (FTS) augmented the lipopolysaccharide (LPS)-induced polyclonal B-cell responses in vitro of CBA/N mice and their F1 hybrids having an X-linked B-cell defect. For this augmentation, FTS should be injected in vivo. Splenic B cells derived from FTS-treated mice with the CBA/N defect were receptive to T-cell help from normal or immunodeficient mouse T cells. Thus, the inability of B cells from mice with the CBA/N defect to accept T -cell help may not be caused by an intrinsic T-cell defect, but by a functional B-cell defect that can be corrected by treatment with FTS in vivo. Spleen cells from ATXBM CBA/N mice treated with FTS 3 weeks after cell transfer did not increase the B-cell response. B cells from FTS-treated male F1 mice with the CBA/N defect still have characteristics of neonatal mouse B cells as revealed by inhibition with antimouse Ig and anti-Ia sera. These findings suggest that FTS may act on generation of a B-cell acceptor for T -cell help, rather than on the maturation of a B-cell subset.

Animals↗
PubMed1982

Studies on live attenuated mumps vaccine. III. Long-term follow-up study on the efficacy of Biken vaccine.

Clinical and serological follow-ups were made on 24 children for 8 years after immunization against mumps with attenuated mumps vaccine, Biken vaccine. To evaluate the protective efficacy of the vaccine, matched controls were studied during the same period. Serological examination revealed that 91% of the controls were infected with mumps and 83% of them contracted the disease during the studied period. However, none of the vaccinees developed clinical infection after close contact with mumps patients. There was no substantial decrease in the antibody titers in unexposed vaccines after vaccination.

Antibodies, Viral↗