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Biomedical subjects

Y Ishida

Publications and source records attributed to Y Ishida.

At least 757 records · Page 42Linked to original sources
PubMed1977

Raphe induced inhibition of intralaminar thalamic unitary activities and its blockade by para-chlorophenylalanine in cats.

Extracellular recordings were made of intralaminar thalamic neurones responding to stimulation of the radial nerves. The effects on this response of a conditioning stimulation of the median raphe nucleus were studied in both untreated and p-CPA pretreated cats. Ninety-two percent of thalamic responses to somatic stimulation in untreated cats was inhibited by conditioning stimulation of the raphe nucleus. The intensities of conditioning stimulation required for the inhibition were significantly higher in cats pretreated with p-CPA than in cats not treated with the drug. It is suggested that raphe projection to intralaminar thalamus excerts an inhibitory influence on thalamic activities, and that the inhibition is mediated by a putative neurotransmitter, serotonin. The possible involvement of the median raphe nucleus in pain processing is discussed.

Animals↗
PubMed1976

The mobile clinic of St. Mary's health center--a functional plan.

Specialized medical facilities tend to be concentrated in medical centers in metropolitan areas, which results in unavailability of adequate medical care to large portions of our population. One solution is a mobile unit, staffed by personnel representing several different disciplines (physicians, nurses, social workers, nutritionists, etc) and extending a health ministry beyond the confines of a medical center to medically deprived areas. The unit also has educational benefits as the medical and nursing students gain valuable experience by evaluating the patients and relating them to the environment in which they live. The mobile clinic allows for a workable situation in a congenial atmosphere without compromising the quality of health care.

Delivery of Health Care↗
PubMed1976

Temperature-pH effect upon germination of bacterial spores.

Using several kinds of criteria for the germination of bacterial spores, germination-pH curves were drawn for Bacillus subtilis spores observed at different temperatures. The experiments revealed that optimum pH for spore germination was markedly changed by changing the incubation temperature; the optimum pH for germination was 7.4 at 37 degrees C and 5.4 at 10 degrees C. A possible mechanism involved in this phenomenon is discussed.

Bacillus subtilis↗
PubMed1976

Effect of anoxia on isotonic shortening induced by high-K medium in rat uterus.

The effect of anoxia on the shortening induced by high-K medium was investigated in isolated rat uterus. The shortening induced by high-K medium was maintained for 75 min or more under normoxia in the initial load (0.35 g). Under normoxia 1, 2, 2.5, and 3 g load to the uterus reduced the maximum shortening induced by high-K medium to 93, 65, 18 and 3%, respectively. Under anoxia the high-K-induced shortening in the initial load was not so affected and it was maintained at least for 60 min. However, against 0.7 and 1 g load to the uterus, the maximum shortening reduced greatly to 14 and 13% under anoxia. Effects of anoxia on the shortenings induced by high-K medium in guinea pigs taenia coli and longitudinal muscle from ileum were also studied. Our observations support the theory that the shortening of the light loaded muscle under anoxia is maintained by only a little force and the muscle may not be so dependent on metabolic energy.

Animals↗
PubMed1976

Selective alpha-adrenoceptor blocking actions of a new derivative of 2-halogenotheylamine: 6-(2-bromoethyl)-10,11-methylenedioxy-5,6,7,8-tetrahydrodibenz[c,e]azocine.

A new compound, 6-(2-bromoethyl)-10,11-methylenedioxy-5,6,7,8-tetrahydrodibenz [c,e] azocine (DA-VIII-MBr) was found to have a more selective alpha-adrenergic blocking action than dibenamine or phenoxybenzamine. From dose-response curves for adrenaline and 5-hydroxytryptamine (5-HT) obtained in strips of rat aorta before and after incubation with each of the three blocking agents, the fractions of receptors remaining active for adrenaline and 5-HT, respectively, were estimated. After blockade with DA-VIII-MBr the receptors for adrenaline were blocked considerably, but those for 5-HT were little affected. Dibenamine blocked the receptors to adrenaline and 5-HT almost equally. The effective dose of phenoxybenzamine for adrenaline receptors was less than one hundredth that of dibenamine or DA-VIII-MBr, but specificity for these receptors was intermediate between those of dibenamine and DA-VIII-MBr. The structure of DA-VIII-MBr is an analog of apogalanthamine and its nitrogen atom bears the 2-halogenoethylamine group in part of an eight membered ring.

Adrenergic alpha-Antagonists↗
PubMed1976

Effects of palytoxin on isolated intestinal and vascular smooth muscles.

Palytoxin (PTX), the most potent marine toxin isolated from the Zoanthid, Palythoa tuberculosa, was studied to determine the effect on isolated smooth muscles. In guinea pig taenia coli PTX at above 3 X 10(-10) g/ml caused a contraction which slowly subsided under isotonic recording. Under isometric recording PTX at above 1 X 10(-10) g/ml caused a contraction which depended on the spontaneous activity. The PTX-induced contraction was not affected by atropine, tripelenmamine or tetrodotoxin but was inhibited by 5 mM Mg, norephinrphrine, isoprenaline or papaverine. PTX at above 1 X 10(-9) g/ml induced an increase in spike frequency and a slight depolarization accompanied with a contraction when measured using a sucrose gap method. In some cases the spike generation was almost abolished after a long exposure to higher dose of PTX and the developed tension gradually decreased. Under isometric recording PTX caused a sustained contraction in rabbit aorta, dog mesenteric and coronary arteries at above 1 X 10(-10) and 1 X 10(-11) g/ml, respectively, in a dose-dependent manner. The coronary artery was most sensitive among the preparation used. PTX-induced contraction in aorta was irreversible, was not influenced by phentolamine but diminished with 5 mM Mg and disappeared in a D-600 or Ca-free medium. PTX is thus an extremely potent and direct stimulant which acts on smooth muscles.

Acrylamides↗
PubMed1975

Fine structure of primary reticulum cell sacroma of the brain.

An electron microscopic study was made on two cases of reticulum cell sarcoma (microglioma) of the brain. In both, the tumour was composed of several type of cells; cells with an undifferentiated appearance and cells with ultrastructural features of the reticulum cell and histiocyte. There seemed to be no significant difference in the fine structure between the tumour cells in reticulum cell sarcoma of the brain and extracerebral forms. The ultrastructures of a lymphosarcoma of the spinal epidural space was also examined and resembles that of such tumours occurring elsewhere in the body.

Adult↗
PubMed1975

Histopathological studies of the nervous system tumors in rats induced by N-nitroso-methyl-urea.

Histopathological examinations were made on tumors of the nervous system induced in rats of Donryu strain by weekly intravenous injections with N-nitroso-methyl-urea (NMU) or by a single administration of NMU through the mothers. A total of 176 neural and nonneural neoplasms were produced in this study. It was suggested that the fetal nervous system of Donryu rats was also highly susceptible to the oncogenic effects of NMU. Of these tumors produced, those of the peripheral nervous system amounted to 121, comprising 68.7% of the total number of the neoplasm. Microscopically, most of the nerve tumors showed the histology corresponding to that of human neurinomas. Many tumors, however, disclosed more or less anaplastic cytological appearance. Fifteen gliomas were produced in the brain and spinal cord. Microscopically, they were classified into mixed glioma, oligondendroglioma and anaplastic astrocytoma. The commonest brain tumors produced in rats from intravenously treated group were periventricular mixed gliomas, while gliomas in rats from transplacentably treated group showed an isomorphic histology with a close resemblance to that of oligodendroglioma.

Animals↗
PubMed1975

Inhibitory effects of caffeine on developed tension and calcium movement in guinea pig taenia coli in high-K medium.

Since the correlation between the K-induced contracture and the Ca movement during the contrature in guinea-pig taenia coli has been clarified, the effects of caffeine were deemed worthy of investigation. The tonic contraction induced by 40 mM K disappeared within 5 min in the presence of caffeine above 7 mM. The inhibitory effect of caffeine was reversed by a high concentration of Ca added to the external medium. High-K added to the medium increased tissue Ca, Ca uptake and the size of cellular Ca fraction that did not exchange within 4 min (tightly bound fraction TBF), and it decreased Ca efflux. An application of 7 mM caffeine to the muscle treated with high-K for 30 min restored all parameters to the control level. Further, caffeine had no effect on the developed tension of the glycerinated taenia induced by Ca, Mg and ATP. It was observed that 14C-caffeine entered the cell in the presence of high-K. From these data, it is suggested that caffeine inhibits high-K induced contracture by inhibiting Ca influx into the contractile mechanism.

Animals↗