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Biomedical subjects

S Katayama

Publications and source records attributed to S Katayama.

At least 415 records · Page 23Linked to original sources
PubMed1985

Effects of H1-receptor blocking drugs on the frog sartorius neuromuscular junction.

The effects of H1-receptor blocking agents, pyrilamine, promethazine, and diphenhydramine, on the amplitude and time course of endplate potentials (e.p.ps) were studied in the sartorius muscles of frogs. H1-receptor blockers (10(-5)-10(-4) M) reduced the amplitude of e.p.ps recorded intracellularly without affecting the resting membrane potential. The acetylcholine potential was decreased by perfusion of H1-receptor blockers. However, when the muscle fibre was stimulated directly, threshold and magnitude of action potential were not affected by H1-receptor blockers. The time constant of decay of the e.p.ps recorded extracellularly was reduced by H1-receptor blockers and the decay remained exponential with a single time constant. The quantal content was not reduced by perfusion of H1-receptor blockers at a concentration of 10(-4) M. It is assumed that the major site of action of these H1-receptor blocking agents is at the postsynaptic membrane.

Action Potentials↗
PubMed1985

Estradiol stimulates rat renopapillary prostaglandin E2 (PGE2), but not PGF2 alpha biosynthesis.

The effects of estrogen on renal prostaglandin (PG) and renin-angiotensin were investigated in rats in relation to sodium metabolism and blood pressure regulation. Regardless of estrous cycle phase, PGE2 urinary excretion in females was 2-3 times higher than that in males and was associated with higher sodium excretion. A positive correlation was observed between urinary PGE2 and free estradiol concentrations. Reno-papillary PGE2 synthesis in vitro after slice incubation was higher in estrous females than in males. Ovariectomy resulted in a marked decrease in PGE2 renal synthesis and excretion, and estradiol administration (50 micrograms, im) restored these to levels comparable to those in cycling females. This estradiol treatment also was associated with a 3-fold rise in PRA without alteration in blood pressure. In estrogen-primed ovariectomized rats, infusion of the angiotensin antagonist Sar1-Ala8-angiotensin II at a rate of 30 micrograms/microliter X h resulted in a further rise in PRA as well as a significant decrease in renal PGE2 synthesis and excretion toward values observed in the ovariectomized animals. In contrast, renal synthesis and excretion of PGF2 showed no fluctuations during identical variations in estrogenic states. The results suggest that estradiol stimulates renal PGE2, but not PGF2 alpha, synthesis not only via a direct stimulatory action, but also through augmentation of the renin-angiotensin II axis. This increase in vasodilatory PGE2 may function to offset the prohypertensive effects of the estrogen-stimulated renin-angiotensin axis.

Angiotensin I↗
PubMed1985

A long term clinical, immunological, and histological follow-up study of patients with goitrous chronic lymphocytic thyroiditis.

Goiter size, thyroid function, antimicrosomal and antithyroglobulin antibodies, and thyroid histology were compared in 43 patients with goitrous chronic lymphocytic thyroiditis (Hashimoto's disease) confirmed by biopsy before and after an interval of 10-20 yr. Although all were given thyroid hormone therapy, 13 patients took it infrequently, and are considered untreated. Among these 13 patients, 5 (38%) became hypothyroid, and 1 became thyrotoxic. Goiter size decreased in 17 (57%) of 30 patients during therapy and in 3 (23%) of 13 untreated patients, and the incidence of reduction was greater in treated than in untreated patients (P less than 0.05). However, in 13 (43%) of the patients, goiter size did not decrease even during treatment. Titers of antithyroid antibodies decreased in only 8 (21%) of 38 patients. There was no significant correlation between changes in antibodies and the size of goiter, and treatment with thyroid hormone did not decrease the titers of antibodies. In patients whose goiters were initially diffusely enlarged and regressed significantly in size during the follow-up period, the initial biopsies showed histological changes in diffuse lymphocytic infiltration and diffuse epithelial changes. Comparative studies of histological differences between patients who were treated with thyroid hormone and those who were not were made in the patients who had no change in goiter size during the observation period, which was greater than 10 yr. The histological changes were similar in both groups at the beginning of the study, and no significant histological changes during the period of greater than 10 yr were found in either group. In one patient who developed thyrotoxicosis after 20 yr and was rebiopsied, the histological picture was that of thyroid hyperplasia and lymphocytic thyroiditis. These data indicate that goitrous chronic lymphocytic thyroiditis changes little as a function of time in many patients regardless of whether thyroid hormone is administered.

Autoantibodies↗
PubMed1985

Toxic effects of chemicals on mouse post-blastocyst development--a trial to establish a testing system for embryotoxicity.

We established a new testing system to assess embryotoxic chemicals using cultured preimplantation mouse embryos. Randomly bred Crj:CD-1 (ICR) mice were used. Late blastocysts collected on Day 4 of pregnancy (plug day:Day 1) were exposed for 24 hrs. to various chemicals at varying concentrations. Morphological embryonic development, structural chromosome aberrations and sister chromatid exchanges (SCEs) were examined as the parameters of embryotoxicity. Treated embryos were then transferred to pseudopregnant foster mice for the evaluation of in vivo development. Of the morphological developmental endpoints in vitro, the formation of two-layer ICMs (inner cell masses) was the most sensitive to the toxicity of chemicals, followed by ICMs and trophoblast outgrowth. Threshold limit values were confirmed regarding morphological growth. However, exposure of embryos to lower concentrations than threshold enhanced the frequency of chromosome aberrations and SCEs. Transfer of embryos treated with the lower concentration of 4-nitroquinoline 1-oxide induced not only fetal wastage but also developmental retardation. 4-nitroquinoline 1-oxide was the most embryotoxic in mouse blastocysts, followed in order by mitomycin C, bleomycin, methylmercuric chloride, diethylstilbestrol, mercuric chloride and ochratoxin-A. This new testing system appears to be a sensitive method of measuring the direct effects of toxic chemicals which yields results in a short term.

4-Nitroquinoline-1-oxide↗
PubMed1985

Radiation associated hyperthyroidism in patients with gynecological malignancies.

To determine the effect of abdominal and/or pelvic irradiation for gynecological malignancies on the later development of hyperthyroidism, 1,884 medical records of the patients diagnoses as carcinomas of cervix and corpus uteri, and of ovary were reviewed. Among 1,269 patients with radiation therapy, 5 patients developed hyperthyroidism after irradiation to the abdomen and/or pelvis. This is a statistically significant increase when compared with an epidemiological study. Radiation dose to the thyroid was estimated to be 30 to 200 rads. Two other patients who were irradiated to the nose or supraclavicular region in addition to the abdomen also developed hyperthyroidism. However, none of 581 patients without radiation therapy became hyperthyroid. The results indicate that radiation therapy for treatment of gynecological malignancy gives a significant radiation exposure with an increase in the incidence of subsequent hyperthyroidism.

Adolescent↗
PubMed1985

[Fundamental and clinical studies of cefpimizole in obstetrics and gynecology].

The findings from recent fundamental and clinical studies of the efficacy of cefpimizole (AC-1370) in obstetrics and gynecology are reported in this paper. The AC-1370 concentrations in genital tissues sampled 30 to 56 minutes (a mean of 41.4 minutes) after intravenous injection of 1 g of the drug were 14 to 76 micrograms/g (a mean of 32.4 micrograms/g). The mean transfer ratios of the drug into the genital tissues to the concentration in the uterine arterial blood were such that the transfer ratio into the portio vaginalis was the highest, followed by the uterine cervix and the myometrium, and that into the oviduct was the lowest with about 1/2 that into the portio vaginalis. The concentration in the antecubital venous blood and that in the uterine arterial blood remained similar for all patients. The transfer of AC-1370 into the pelvic dead space exudate reached a peak (49.5 micrograms/ml) 1 hour, and also a peak (49.8 micrograms/ml) 2 hours after the intravenous injection. It then decreased gradually, but remained high, being higher than that in the antecubital venous blood about 50 minutes after the intravenous injection. Ten patients with infections in gynecology were treated with 1.0 to 4.0 g daily of AC-1370, to a total dose of 6 to 52 g, over a period of 3 to 13 days. One of them showed excellent response, 8 showed moderate response, and another showed poor response to the treatment: in other words, a response rate of 90% was achieved. Bacteriologically, pathogens were eradicated from 3 and decreased in 3, and microbial substitution occurred in another patient. No side effects of the drug were observed except for eruption in 1 patient. None of the 10 patients showed any abnormalities in laboratory findings. From the present fundamental and clinical studies of AC-1370, we have drawn the conclusion that the drug is one of extremely useful antibiotics in the treatment of infections in obstetrics and gynecology.

Adult↗
PubMed1985

[Methodological study for human in-vitro fertilization related to maturity of gametes].

The correlations with maturity of gametes and fertilizability was studied. Specimens of semen were treated by several methods for induction of capacitation and acrosome reaction (AR). Follicular oocytes were recovered with endoscopic aspiration procedures, and divided to two groups: 1, maturing in vivo (preovulatory) and 2, immature. Immature oocytes were divided further into two subgroups: 1, germinal vesicle breakdown (GVBD) and 2, first polar body formation (FPB), after maturation culture. The sperms treated with the centrifuge-trypsinization-layering method showed a higher incidence of in-vitro fertilization (69.2%) and cleavage (51.3%) of human preovulatory eggs compared with other capacitation inducing methods. It was found that human spermatozoa that have undergone the acrosome reaction prior to zona attachment are capable of fertilizing eggs under the in vitro conditions. On the estimation of fertilizability with reference to egg maturity, 52.5% (21/40) of IMIV-GVBD and 64.7% (22/34) of IMIV-FPB eggs were fertilized. However, only 12.5% (5/40) of IMIV-GVBD and 11.8% (4/34) of IMIV-FPB eggs cleaved. These results showed that IMIV eggs had fair fertilizability, but no developmental capacity after the first cleavage. This may due to prematurity of the cytoplasm in IMIV eggs.

Animals↗
PubMed1984

[A long-term follow-up study of patients with chronic lymphocytic thyroiditis--with special reference to histological findings].

It is generally believed that in the long-term observation of chronic thyroiditis, the goiter decreases in size with thyroid hormone therapy and the thyroid function drops gradually. On the other hand, the histological changes in so-called Hashimoto's thyroiditis have been recognized to show progressive loss of epithelium and increased fibrosis. In this study, goiter size, thyroid function, thyroid microsomal and thyroglobulin antibodies and histology in needle biopsy were investigated in 75 patients with chronic thyroiditis during an interval of more than ten years. Among 75 cases, 8 (11%) were hypothyroid at the first medical examination. Among 21 cases who received no treatment, 7 (33%) became hypothyroid during the period of more than ten years. Among 54 cases with thyroid hormone therapy, 16 (30%) showed a remarkable reduction in size of goiter, but among 21 cases without thyroid hormone therapy only 3 (14%) showed a remarkable reduction. This paper discusses changes in titers of thyroidal antibodies in 47 cases. Among these 47 cases, 21 increased titer of thyroglobulin antibody during the period of more than ten years. 10 (48%) out of these 21 cases showed a remarkable reduction in size of goiter. But among 11 cases with a decrease of titer of thyroglobulin antibody, only one (9%) showed a remarkable reduction in size of goiter. On the other hand, titer of thyroid microsomal antibody increased in 33 cases. 9 (27%) out of these 33 cases showed a remarkable reduction in size of goiter. Only one (13%) of 8 cases, which decreased titer of thyroid microsomal antibody, showed a remarkable reduction in size of goiter.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies↗
PubMed1984

Mechanism of furosemide-induced natriuresis by direct stimulation of renal prostaglandin E2.

Studies were conducted to investigate the interaction of renal prostaglandin E2 (PGE2) production and the renin-angiotensin system in the mechanism of furosemide-induced natriuresis. In conscious rabbits with permanent urinary bladder cannulation, furosemide in vivo (10 mg/kg) increased urinary water, sodium, and PGE2 excretion and plasma renin activity (PRA) over 50 min. Furosemide administered in vivo enhanced renal papillary but not cortical in vitro PGE2 biosynthesis. Prior administration of indomethacin at 2 mg/kg augmented the saluretic effect of furosemide, decreased its effect on UPGE2 V, abolished the rise in PRA, and reduced cortical but not papillary PGE2 biosynthesis. However, at 10 mg/kg, indomethacin reduced the saluretic effect of furosemide and eliminated the increase in UPGE2 V with continued suppression of PRA. Direct addition of furosemide in vitro to the incubation medium (10(-5) and 10(-3) M) markedly augmented papillary PGE2 synthesis. It is concluded that furosemide stimulates renal papillary PGE2 biosynthesis directly without mediation by angiotensin II, resulting in an increase in UPGE2 V, and the enhanced or inhibitory effect of indomethacin on furosemide-induced natriuresis is dose related and dependent on the degree of PGE2 synthesis inhibition in the presence of suppressed PRA, which occurred at all doses studied.

Angiotensin II↗
PubMed1984

Absent or delayed preovulatory luteinizing hormone surge in experimental diabetes mellitus.

The proestrus preovulatory luteinizing hormone (LH) surge was absent or delayed in more than 56% of untreated streptozotocin-diabetic rats. Absence of LH surge was associated with anovulation. Insulin treatment for 10-14 days restored the diminished surge and ovulation frequency. Pituitary LH release in response to exogenous gonadotropin-releasing hormone administration in diabetic rats was not different from controls. Impaired hypothalamic function may comprise the basis for the increased incidence of infertility in diabetes mellitus.

Animals↗