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Biomedical subjects

T Nishimura

Publications and source records attributed to T Nishimura.

At least 1,603 records · Page 89Linked to original sources
PubMed1980

[Dual action of prostaglandins in the regulation of HCG-induced ovulation in immature rats (author's transl)].

With the aid of indomethacin, a potent inhibitor of prostaglandin synthesis, the mechanism of action of prostaglandins on follicle rupture was studied. Mean number of ova shed following treatment of immature rats sequentially with PMS and hCG was reduced in a dose-dependent manner by simultaneous injection with increasing doses of indomethacin. The minimum effective dose to block ovulation completely was 90 micrograms. However, the anti-ovulatory action of the minimum effective dose at 0 h became progressively less potent as the time between hCG injection and indomethacin administration was increased. Another dose-dependent relationship was found 10 h after hCG injection, the closest time prior to the onset of ovulation, the minimum effective dose necessary to prevent ovulation was 8 times higher than at 0 h, suggesting that prostaglandins acted differently on ovulation in the later stage of the preovulatory process. It is concluded that prostaglandins may mediate the action of hCG on ovulation at least through two mechanisms.

Animals↗
PubMed1980

[An ultrastructural study of capillaries of rabbit ovarian follicles during ovulatory process (author's transl)].

The observations that perifollicular capillaries of the ovary become engorged with prominent edema in the theca interna and externa around the time of ovulation, suggest a preovulatory increase in permeability of perifollicular capillaries. In order to obtain an ultrastructural evidence for this increased capillary permeability, we examined the perifollicular capillaries in the theca interna by using mature rabbit ovaries at various time intervals after the hCG injection for induction of ovulation. We observed a capillary engorgement at 9, 10, 12 hours after the hCG injection, most prominent at 9 hours, and edema in the pericapillary space at 10, 12 hours. Pinocytotic vesicles were seen through the all stages of follicular development and they did not show any significant changes in their size, number and distribution. Fenestrations were observed at 0, 3, 4, 6 hours after the hCG injection, most frequent at 4 hours. Intercellular gaps (500 approximately 1,200 A) between two endothelial cells were demonstrated at 10, 12 hours, and thrombocytes in these gaps were also noticed. The present observations suggest that increased permeability of perifollicular capillaries just prior to ovulation were mainly due to the formation of gaps between the endothelial cells.

Animals↗
PubMed1980

[An ultrastructural study of capillary permeability of rabbit ovarian follicles during ovulation using carbon tracer (author's transl)].

The observations that perifollicular capillaries of the ovary become engorged with prominent edema in the theca interna and externa around the time of ovulation, suggest a preovulatory increase in permeability of perifollicular capillaries. In previous study, we reported ultrastructural evidences which suggested the increased permeability of perifollicular capillaries just prior to ovulation. In this study, we further examined the perifollicular capillaries of rabbit ovary by using carbon particles as a tracer at various time intervals after the hCG injection for induction of ovulation. Pinocytotic vesicles exhibited no significant changes in size, number and distribution through all preovulatory stages. Carbon particles were not taken into them. Fenestrations were observed at 0,3,4,6 hrs after the hCG injection, most frequently at 4 hrs, but no carbon particles could penetrate them. Intercellular gaps between two adjacent endothelial cells began to be observed at 10 hrs after the hCG injection. Carbon particles passed through these gaps with staying inside the basement membrane (so-called intramural leaking). These observations indicated that the increased permeability of the perifollicular capillaries, just before ovulation, were due to intercellular gaps.

Animals↗
PubMed1980

Physiological study of the human mesotubarium ovarica.

The human mesotubarium ovarica has been shown to contain bundles of smooth muscle cells. Its contractility at various phases of the menstrual cycle was studied in vitro in 51 tissue strips obtained at laparotomy. The strips obtained at the ovulatory phase showed the greatest spontaneous contractile activity as well as the greatest contractile response to norepinephrine, acetylcholine, and prostaglandin F2 alpha. This corresponds to the increased contractility of the ovary at this phase of the cycle. It is suggested that these contractile actions may, under the influence of chemical transmitters, play a role in ovum pick-up by the tubal fimbria at ovulation.

Acetylcholine↗
PubMed1979

Suppression of mixed lymphocyte reaction by progesterone and estradiol-17beta.

The effects of estrone, estradiol-17beta, estriol, testosterone, progesterone, and 20alpha-dihydroprogesterone on incorporation of 3H-thymidine into cultured lymphocytes from normal men and nonpregnant women in response to allogeneic stimulation was investigated with two-way MLR. A dose-dependent reduction in the mean percent incorporation was observed in the range of progesterone concentration between 2 x 10(3) and 10(4) ng/ml with statistically significant differences from the control cultures. Estradiol-17 beta at 10(4) ng/ml produced a slight but significant inhibition of incorporation. No significant change in incorporation occurred with the other steroids tested. Since the suppressive property of progesterone in phytohemagglutinin-induced lymphocyte culture reported in our previous communication was reproduced by the present investigation in MLR, the possible role of progesterone in immunoregulation during pregnancy is emphasized as has been postulated previously.

20-alpha-Dihydroprogesterone↗
PubMed1979

A method for specific detection of autoantibodies to the zona pellucida in infertile women.

Human antibodies to porcine erythrocytes were found to bind to porcine but not to human zonae pellucidae, whereas human isohemagglutinins bound to human but not to porcine zonae. On the basis of the binding behavior of agglutinins, it was found that the immunofluorescence of porcine zonae produced by selected sera from infertile women was due to an antibody of different specifity from that which agglutinated pig red blood cells. However, no serum component other than heteroagglutinin was contained in selected sera from control subjects which fluoresced porcine zonae. Since the component was present in the immunoglobulin G fraction, bound to human zonae, and was reactive with zona-specific antigen(s), it was judged an autoantibody to zonae. Thus a method for specific detection of autoantibodies to zonae has been developed by indirect membrane immunofluorescence using porcine ova as targets.

Absorption↗
PubMed1979

Noradrenaline clearance in hypertensive patients with various degrees of renal function.

1. Hypertensive patients with normal renal function showed significantly higher plasma urinary noradrenaline than the normotensive controls, and the hypertensive patients with mild to moderate disturbance of renal function showed the same noradrenaline concentration as the controls. 2. Hypertensive patients with severe renal function disturbance showed significantly higher plasma noradrenaline concentrations and lower urinary noradrenaline excretion than the controls. 3. Noradrenaline clearance calculated by free plasma noradrenaline and total urinary noradrenaline was significantly decreased in those subjects with severe renal dysfunction. 4. Conjugated plasma noradrenaline was increased in the hypertensive patients with the severe disturbance of renal function, and conjugated urinary noradrenaline increased in those without severe renal dysfunction.

Adult↗
PubMed1979

Plasma catecholamines determination using high pressure liquid chromatography and their roles in blood pressure regulation and experimental hypertension in rats.

Plasma catecholamine levels have been used experiemtally and clinically as the indices of the sympathetic nerve activity. We measured plasma catecholamines using high pressure liquid chromatography in rats to assess the significance of plasma catecholamines as an index of the sympathetic nerve activity and its role in hypertension. Pentobarbital anesthesia depressed plasma catecholamine levels, especially plasma adrenaline. Sodium loading for 5 weeks suppressed plasma noradrenaline, while administration of furosemide (1 mg/kg) produced the elevation of plasma noradrenaline. Experimental hypertension, one-kidney and two-kidney types of Goldblatt hypertension and DOCA-salt hypertension, raised plasma noradrenalines both in acute and chronic phases. The infusion of pressor doses of angiotensin II suppressed plasma noradrenaline by the reflex mechanism. Sar1, Ile8-angiotensin II and SQ 14,225 did not suppress plasma cathecholamine elevation due to hemorrhage. L-Hydroxyldopamine produced elevation of plasma catecholamines in experimental nypertension and controls in rats. After adrenal demedullation, plasma noradrenaline was decreased by the administration of 6-hydroxy-dopamine. Acute reduction of circulating blood volume and blood pressure fall produced the elevation of plasma catecholamine, especially plasma adrenaline. In rats, the adrenal medulla plays an important role in the regulation of blood pressure.

Aging↗