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Biomedical subjects

M Kotani

Publications and source records attributed to M Kotani.

At least 127 records · Page 7Linked to original sources
PubMed1984

Tripeptides acting on opioid receptors in rat colon.

The tripeptides SD-34 and SD-25 induced atropine-, guanethidine-, antihistaminics-resistant but naloxone-sensitive contractions of isolated rat distal colon. They appeared to act on an opioid receptor, probably of the mu subtype, distinct from those for methionine enkephalin and morphine, because the pA2 values of naloxone for the peptides were similar to those for mu-agonists but different from those for methionine enkephalin and morphine, and because the peptides caused contractions of colon that had been desensitized to morphine. Mr 2266, a supposed kappa-antagonist, inhibited the actions of the peptides, ethylketocyclazocine and dynorphin at concentrations much lower than those inhibiting the actions of methionine enkephalin and morphine. Thus these peptides seem to act on the mu- and/or kappa-receptors. The actions of the tripeptides were inhibited by methysergide and methylergometrine, but not by the 5-HT2 antagonist ketanserin, and were not affected by 5-HT or substance P autodesensitization . Thus their actions do not seem to involve 5-HT, histamine, ACh or substance P. It seems likely that the tripeptides, through opioid receptors, directly activate the muscle, or remove some inhibitory modulation of myogenic activity, thus causing contractions.

Animals↗
PubMed1984

Effect of androgen on the expression of the sex difference in susceptibility to infection with Strongyloides ratti in C57BL/6 mice.

The possible site of expression of the sex difference in susceptibility to infection with Strongyloides ratti was studied in C57BL/6 mice. The intensity of infection, measured by daily larval output in faeces or by intestinal worm burden, was significantly higher in males than in females. This sex difference was already expressed during the migration of larvae from the site of subcutaneous inoculation to the cranial cavity or lung as early as 24 h after infection. Conversely, there was no significant difference in the larval output in faeces or in the worm burden of male or female recipients after implantation of adult worms using a stomach tube. When the susceptibility to infection with S. ratti of gonadectomized animals was examined, the daily larval output in faeces of orchidectomized males was significantly reduced to the level of intact females, while ovariectomy had no effect, suggesting that androgen is one of the important regulatory factors for the expression of sex difference. In fact, testosterone treatment of orchidectomized males or normal females could increase their susceptibility to or above the level of intact males. These results strongly suggest that sex difference in the susceptibility to infection with S. ratti in C57BL/6 mice is mediated by 'natural defence mechanisms' which are under the regulation of testosterone.

Animals↗
PubMed1984

The effect of changing the maxillomandibular relationship by a bite plane on the habitual mandibular opening and closing movement.

The relationship between the change of afferent information from occlusal contacts and its influence on the jaw muscles was investigated. For this purpose, the following questions were posed and experimental studies designed. If the subject was given habitual occlusal contacts in centric relations with a bite plane, were the habitual mandibular closing and opening movements influenced? Second, was it easier for the subjects to accomplish regular habitual mandibular opening and closing movements, when the bite plane was inserted and removed? From the results it could be concluded that the centric occlusal contacts in centric relation were more physiological for the jaw muscles. In addition, when the new occlusal position was coincident or close to the centric relation, it was easier for the subject to study and acquire the new habitual mandibular opening and closing movement.

Adolescent↗
PubMed1983

Characterization of low dose induced suppressor cells in adjuvant arthritis in rats.

Characterization of suppressor cells in adjuvant arthritis was performed by using highly susceptible DA strain rats. The results showed that suppressor cells were induced after a single inoculation of subarthritogenic dose of mycobacterial adjuvant. Relatively long incubation period was required for the induction of suppressor cells. Such cells were predominated in the draining lymph node and, after fractionation, only sIg- population was effective in conferring unresponsiveness. In vivo irradiation or hydrocortisone treatment suggested that low dose induced suppressor cells were resistant against such immunosuppressive treatments. In addition, by using alkyldiamine as a non-mycobacterial arthritogenic adjuvant, it was suggested that unresponsiveness induced by low dose priming with mycobacterial adjuvant was antigen specific.

Adjuvants, Immunologic↗
PubMed1983

Effects of estrogen on hepatic hemopoiesis in the adult mouse.

After a single pharmacologic dose of estriol (E3) treatment, an increase in number of focal areas of hepatic hemopoiesis was observed in adult mice. When syngeneic bone marrow cells were transfused into E3-treated mice, focal hepatic hemopoiesis was increased further. In a single experiment, using a single cell suspension, the concentration of CFUs in the liver was increased 5 days after E3-treatment, while that in the blood decreased. In addition, 51Cr-labeled bone marrow cells selectively accumulated in the E3-treated mouse liver. These results suggest, but in not sense prove, that circulating hemopoietic stem cells are trapped in the E3-treated mouse liver, and that E3-activated Kupffer cells may play a central role in focal hemopoiesis in the liver.

Animals↗
PubMed1982

Modulation of the immune responses against SRBC after oestriol treatment in mice.

Delayed-type hypersensitivity (DTH), primary direct and indirect PFC, memory antibody response and suppressor cell induction against sheep red blood cells (SRBC) have been examined in oestriol (E3) pretreated mice. The results showed that DTH and primary direct and indirect PFC responses were suppressed by E3 treatment. These suppressive effects could, however, be overcome when oestrogenized mice were given supra-optimal doses of SRBC for each response. On the other hand, the memory antibody response was markedly enhanced when E3 was given prior to the primary antigen stimulation. Induction of the suppressor cells for the antibody response seemed not to be affected by E3 treatment, but the characterization of the suppressor cells revealed that those obtained from E3 treated mice were surface immunoglobulin positive (sIg+) cells whereas those from control mice were not. These results were discussed in terms of the altered antigen distribution due to the activated phagocytic activity of the reticuloendothelial system (RES) after E3 treatment.

Animals↗
PubMed1981

Destruction of Hassall's corpuscles by macrophages in the sheep thymus.

The dissolution of Hassall's corpuscles by macrophages has been demonstrated in the sheep thymus. The findings indicate that enlarged Hassall's corpuscles are rapidly broken down by macrophages at the end of gestation or immediately after birth and replaced by newly formed corpuscles, and that these cyclic changes in Hassall's corpuscles persist, under normal physiological conditions, throughout life.

Animals↗