Biomedical subjects

R Tahara

Publications and source records attributed to R Tahara.

8 recordsLinked to original sources

PubMed2000

Difference in hydrophobicity between botulinum type B activated and non-activated neurotoxins under low pH conditions.

We showed that botulinum type B activated neurotoxin with a di-chain structure became hydrophobic more quickly and extensively than did the non-activated toxin with a single-chain structure on low pH exposure. The activated toxin possessed 50-fold higher toxicity than did the non-activated type. The difference in the susceptibility to hydrophobic change may be one clue to answering the question of why the activated toxin possesses a higher toxicity than does the non-activated type.

Botulinum Toxins↗

PubMed1997

[Gonadal dysfunction].

Function of hypothalamic-pituitary-ovarian axis is an essential factor for the maintenance of regular cycles in mature women. The disturbance of function of those organs causes gonadal dysfunction such as anovulation, amenorrhea and menstrual disorders. Therefore, the correct diagnosis for the assessment of CNS and ovarian function is clinically important to treat the patients those who have an menstrual disorders. In this review, the mechanism of normal gonadal cycles and the diagnostic method and the treatment of gonadal dysfunction are described.

Amenorrhea↗

PubMed1996

[Stage IIIa endometrial carcinoma: MR findings].

[PURPOSE]: An attempt was made to evaluate the ability of magnetic resonance (MR) imaging to diagnose stage IIIa endometrial carcinoma. [MATERIALS AND METHODS]: Thirty-three patients with endometrial carcinoma underwent MR imaging and surgery. Surgical staging was classified as I in 21 patients, II in 3 patients and III in 9 patients. The MR images of each patient were retrospectively reviewed by three radiologists. Only the clinical diagnosis of endometrial carcinoma was previously notified. Segmental disruption of the full thickness of the myometrium was considered serosal invasion. Intraperitoneal metastasis was diagnosed according to three criteria (intraperitoneal solid mass of isointensity compared with endometrial lesion, cystic mass excluding benign ovarian cysts, ascites). These evaluations were compared with the surgical findings and analyzed by the kappa statistic. [RESULTS]: The rates of sensitivity and positive predictive value (PPV) for serosal invasion were 33% and 6%, respectively. False positive evaluation frequently occurred when thickness of the intact myometrium was less than 5mm. The rates of sensitivity and PPV for intraperitoneal metastasis were 86% and 72%, respectively. The reason for false negative evaluation was small foci of intraperitoneal metastasis. Overall, sensitivity and PPV for stage IIIa were 86% and 69%, respectively. [CONCLUSION]: MRI was useful in detecting intraperitoneal metastasis of endometrial carcinoma with the exception of diagnosing serosal invasion. It is difficult to detect small foci of peritoneal metastasis. It is necessary to differentiate adnexal metastasis from benign adnexal masses.

Adenocarcinoma↗

PubMed1990

Determination of a new calcium antagonist, sesamodil fumarate (SD-3211), and its metabolite in plasma by liquid chromatography with electrochemical detection.

A sensitive and selective high-performance liquid chromatographic method is described for the determination of a novel calcium antagonist, (+)-(R)-3,4-dihydro-2-[5-methoxy-2-[3-[N-methyl-N-[2-[(3,4- methylenedioxy)phenoxy]ethyl]amino]propoxy]phenyl]-4-methyl-3-oxo-2H- 1,4-benzothiazine hydrogen fumarate (sesamodil fumarate; JAN, SD-3211, I), and its N-desmethylated metabolite (II) in plasma. Compounds I and II and an internal standard were isolated from plasma by solid-phase and liquid-liquid extraction. The extract was chromatographed on a reversed-phase C18 column, and the compounds of interest were detected by dual coulometric electrodes operated in an oxidative screen mode. The limit of determination for both I and II was at least 0.4 ng/ml in plasma. The utility of the assay was demonstrated by determining plasma levels of I and II in five dogs administered an oral dose of 60 mg of the drug.

Animals↗

PubMed1985

Steroid concentrations in human cervical tissue in relation to cervical ripening.

Steroid concentrations in human cervical tissue were measured in order to study the mechanism of cervical ripening at term. Thirty-four women at 37 to 41 weeks of gestation were selected for the study and divided into two groups. Group A consisted of 21 cases with ripened cervix, and Group B consisted of 13 cases with non-ripened cervix. The condition of the cervix was judged by the Bishop's Score. Free and conjugated estrone (E1), estradiol (E2), estriol (E3), and dehydroepiandrosterone (DHA) concentrations in cervical tissue were measured by radioimmunoassay (RIA). Significantly higher concentrations of free E1, conjugated E2, E3 and DHA were found in Group A than in Group B. Cervical tissue during labor showed a further increase in the concentrations of these steroids. Pronounced increases of the steroid concentrations were noted following DHA-Sulfate (DHA-S) administration. These results suggest an intimate relationship between cervical ripening and steroid concentrations in cervical tissue during pregnancy.

Cervix Uteri↗

PubMed1984

Enhancement of human amniotic phospholipase A2 activity by steroid-sulphate derived from the foeto-placental unit.

To study the control of production of prostaglandins (PG) during pregnancy and parturition, amniotic membranes obtained from normal vaginal delivery were incubated with the substrate of phosphatidylcholine containing [14C]arachidonic acid in the Sn-2 position. Phospholipase A2 activity was calculated as the rate of release of [14C]arachidonic acid from the substrate. Various steroids were added to the incubation medium to elucidate the effect of steroids on the enzymatic activity. The addition of dehydroepiandrosterone-sulphate (DHA-sulphate) to the medium increased by 7-fold the rate of [14C]arachidonic acid release from phosphatidylcholine at a concentration of 1.67 mM. The enhanced rate of arachidonic acid release suggests that DHA-sulphate stimulates phospholipase A2 activity. The same amounts of pregnenolone-sulphate and oestrone-sulphate also enhanced the enzymatic activity, while cholesterol-sulphate, free steroids such as DHA, progesterone, cortisol and oestrogens revealed no effect. These results suggest that steroid sulphates may be involved in the regulatory mechanism for PG synthesis in amniotic membrane.

Amnion↗

PubMed1984

Simple assay of estrogen in urine during pregnancy by means of latex agglutination inhibition reaction.

A simple and rapid method, latex agglutination inhibition reaction (LAIR), using anti-estriol-16-glucuronide coupled with BSA for estimating estrogen in urine has been developed. Agglutination of the latex reagent by the antiserum occurs within 3 min. The agglutination, however, was completely inhibited by 100 ng/ml or more of estriol. There was a good correlation in results obtained by LAIR and by colorimetry, RIA and GLC. Urine samples (3329) obtained at various gestational weeks were assayed. The samples from 94% of the normal pregnant patients in the third trimester revealed 10 micrograms/ml or more of estrogens. Although the assay is semiquantitative, it may be useful in screening for fetal well-being in high-risk pregnancies.

Estriol↗

PubMedDate not supplied

Effect of dehydroepiandrosterone sulphate, oestrogens and prostaglandins on collagen metabolism in human cervical tissue in relation to cervical ripening.

To clarify the mechanism of cervical ripening at term, collagenase activity in human cervical tissue was studied. The effects of steroids and prostaglandins on collagenase activity were also examined. Collagenase activities in cervical tissues obtained from non-pregnant (n = 5) and pregnant women (early-pregnant, n = 3; late-pregnant, n = 14) were measured, with or without the addition of steroids and prostaglandins into the incubation medium prior to the measurement of enzyme activity. The enzyme activity was significantly (P < 0.01-0.05) higher in the cervical tissue obtained from late-pregnant women than that from non-pregnant and early-pregnant women. Collagenase activity was significantly (P < 0.05) elevated when steroid sulphates such as dehydroepiandrosterone sulphate and oestrone sulphate were added to the incubation medium, while the addition of free steroids, prostaglandin E2 and prostaglandin F2 alpha did not alter the activity. These data suggest that conjugated steroid produced in the foetoplacental unit during pregnancy may be involved in cervical ripening through the enhancement of collagenase activity.

Cervix Uteri↗