PubMed Health⌕ Search

Biomedical subjects

K Hayata

Publications and source records attributed to K Hayata.

17 recordsLinked to original sources
PubMed1994

Corticotropin-releasing factor stimulates Ca2+ influx in cultured rat astrocytes.

Corticotropin-releasing factor (CRF) increased intracellular Ca2+ concentration in single astrocytes. The effect in increasing intracellular Ca2+ was not observed in Ca2(+)-free solution. Furthermore, CRF at concentrations more than 10 nM stimulated 45Ca2+ uptake in cultured rat astrocytes. The action was blocked by alpha-helical CRF(9-41) in a competitive manner, but not by nifedipine and 3,4-dichlorobenzamil. On the other hand, CRF did not stimulate cAMP formation, cGMP formation and phosphoinositide hydrolysis in astrocytes. These results indicate that CRF increases Ca2+ influx via an activation of CRF receptors in a cAMP-independent mechanism in cultured astrocytes.

1-Methyl-3-isobutylxanthine↗
PubMed1993

Endothelins modulate dibutyryl cAMP-induced stellation of cultured astrocytes.

Effect of endothelin-3 (ET-3) on dibutyryl cAMP (DBcAMP)-induced stellation of rat cerebral cultured astrocytes was examined. Treatment with 1 mM DBcAMP, 10 microM forskolin, 100 microM isoproterenol and 500 nM phorbol 12-myristate 13-acetate changed protoplasmic cultured astrocytes into process-bearing ones. ET-3 (1 nM) completely prevented the astrocytic stellation induced by these agents. The effect of ET-3 showed a dose-dependence, where IC50 value and maximal effective dose were 49 pM and about 0.1 nM, respectively. ET-1 and sarafotoxin (SRTX) S6b prevented the DBcAMP-induced astrocytic stellation with potencies similar to that of ET-3. ET-3 (1 nM) did not affect the cAMP accumulation after DBcAMP treatment in cultured astrocytes. Stellate astrocytes were reversed to the protoplasmic type cells by addition of 1 nM ET-3 in the presence of DBcAMP. ET-1 and SRTX similarly reversed the astrocytic stellation. ET-3 reversed the astrocytic stellation in the absence of extracellular Ca2+. Pre-loading of BAPTA-AM, a permeable Ca2+ chelator, on stellate astrocytes had no effect on the reversal by ET-3. ET-3 did not increase intracellular free Ca2+ concentration ([Ca2+]i) of most astrocytes tested at 0.1 nM. A high concentration (100 nM) of ET-3 increased astrocytic [Ca2+]i which was negated by Ca(2+)-free and BAPTA-AM loading. These results suggest that ETs modulate morphological changes in astrocytes through cAMP- and Ca(2+)-independent mechanisms.

Animals↗
PubMed1985

Rapid and simultaneous measurement of estrone, estradiol, estriol and estetrol in serum by high performance liquid chromatography with electrochemical detection.

A high performance liquid chromatographic (HPLC) method with electrochemical detection (ECD) was developed for the simultaneous measurement of estrone, estradiol, estriol and estetrol in serum. These hormones were extracted with diethylether, chromatographed on an silica-octadecyl silane (ODS) column with an eluent of phosphate buffer solution-acetonitrile-methanol (volume ratio 152:85:40), and detected by ECD at +1.0V vs. Ag/AgCl. In comparisons between the values measured by this method and radioimmunoassay, significant correlations were noted for estrone (r = 0.759, p less than 0.01), estradiol (r = 0.816, p less than 0.001) and estriol (r = 0.830, p less than 0.001). In clinical applications of this method, differences between cases of the normal and the anencephalic pregnancy in the thirty-eighth week of gestation were distinct not only in the individual estrogen, but also in the profile analysis of estrogens. With this method, all 4 serum estrogens above approximately 500 pg/ml could be measured within 2 h, and the method seemed to be clinically applicable.

Chromatography, High Pressure Liquid↗
PubMed1985

Application of rapid and simultaneous measurement of sex steroid hormones to the monitoring of gonadotropin therapy.

A high performance liquid chromatographic (HPLC) method with both electrochemical detection (ECD) and ultraviolet spectrometric detection (UVD) was developed for the rapid and simultaneous measurement of estradiol (E2), estrone (E1), testosterone (T), 17 alpha-hydroxyprogesterone (17-OHP) and progesterone (P) in serum. These hormones were extracted with diethylether, and chromatographed on an octadecyl silane-silica (ODS) column with an eluent of a phosphate buffer solution - acetonitrile mixture (volume ratio 49:51). Estrogens were detected by ECD at +1.0 V vs. Ag/AgCl, and other hormones by UVD at 242 nm. With this method, the simultaneous determination of sex steroid hormones could be performed within approximately two hours with high precision. The hormones of 34 patients (39 menstrual cycles) undergoing human menopausal gonadotropin (HMG)-human chorionic gonadotropin (HCG) therapy were measured. It was concluded that the switch from HMG to HCG should be performed when the E2 level reaches 400 pg/ml for ovulation and 800 pg/ml for pregnancy. The occurrence of ovarian hyperstimulation syndrome (OHSS) can be predicted when the P level rises above 30 ng/ml on the 7th day after the switch. Moreover, conception may be indicated when the P level does not increase from the 7th to 14th day after the switch. In this way, this method proved to be useful for the monitoring of HMG-HCG therapy.

Chorionic Gonadotropin↗
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↗