Biomedical subjects

K Shiota

Publications and source records attributed to K Shiota.

At least 163 records · Page 9Linked to original sources

PubMed1991

Basic fibroblast growth factor-like substance in nuclei of male germ cells undergoing meiosis.

The presence of a basic fibroblast growth factor-like immunoreactive substance was demonstrated in the nuclei of germ cells at stages from spermatocyte to spermatid in adult rat testis by using immunohistochemistry with an antibody raised against a synthetic peptide corresponding to residues 1-10 of bovine basic fibroblast growth factor [1-146]. The fluorescence was very weak in the nuclei and cytoplasm of spermatogonia, Sertoli cells, and most of the interstitial compartments, except for capillary endothelial cells. This is the first study to demonstrate the presence of basic fibroblast growth factor-like immunoreactive material in the nuclei of haploid cells in vivo.

Animals↗

PubMed1990

Insulin-like growth factor-I stimulates endothelin-3 secretion from rat anterior pituitary cells in primary culture.

Since we found relatively high concentrations of immunoreactive (ir-) ET-3 in the rat pituitary gland (190 pg/g tissue), we have investigated the possible ET-3 secretion from the primary culture of anterior pituitary cells and the effects of various growth factors on the ET-3 secretion. The ir-ET-3 was detected in the incubation medium within 2 h, and 24 h of culture attained the concentrations of 1.15 +/- 0.26 pg/well/6 x 10(5) cells. The ir-ET-3 secretion was stimulated by insulin, insulin like growth factor-II (IGF-II), and most effectively by insulin like growth factor-I (IGF-I) in a dose- and time-dependent manner, whereas the production of ir-ET-1 and ir-big ET-1 was slightly inhibited by IGF-I and IGF-II. In reverse-phase HPLC, the ir-ET-3 released into the culture media showed identical retention time with authentic ET-3. Although ir-ET-1 and ir-big ET-1 secretion was stimulated by transforming growth factor-beta (TGF-beta), ir-ET-3 secretion was inhibited. These results indicate that the anterior pituitary cells secrete ET-3 and the secretion is stimulated by IGF-I.

Animals↗

PubMed1990

Activin A increases the number of follicle-stimulating hormone cells in anterior pituitary cultures.

The mode of action of activin A on the anterior pituitary gland (AP) was investigated using primary cultured cells. The AP cells were cultured with activin A (1 ng/ml) at various cell densities for 24-96 h, and further incubated for 3 h with activin A-free medium. When the cells were pretreated with activin A for 48 h, follicle-stimulating hormone (FSH) secretion during the following 3-h incubation was increased only at a density of 1 x 10(5) cells/200 mm2, but not at 2 x 10(5) or 4 x 10(5) cells/200 mm2. A longer pretreatment (96 h) was required in order to induce this response at a density of 2 x 10(5) cells/200 mm2. Luteinizing hormone (LH) secretion was not affected by activin A. Thus, the FSH secretory activity of the primary culture of AP was stimulated by activin A in a cell density-dependent manner. Furthermore, it was found that treatment with activin A (10 ng/ml) for 72 h increased the number of immunoreactive FSH cells by 25-41%, and that these newly induced FSH cells were low responders to gonadotropin-releasing hormone stimulation. The proportions of immunoreactive LH, thyroid-stimulating hormone, prolactin or growth hormone cells were not affected. From these results, we conclude that activin A increases FSH secretion by changing the cell population of pituitary gonadotropes.

Activins↗

PubMed1990

Expression of the epidermal growth factor receptor in developing fetal mouse palates: an immunohistochemical study.

Epidermal growth factor (EGF) stimulates the growth of various tissues and, therefore, EGF receptor expression in fetal tissues may play a key role in organogenesis. We have examined immunohistochemically the ontogeny and localization of the EGF receptor in the fetal mouse palate during in vivo and in vitro palatogenesis using the anti-human EGF receptor rabbit antibody. Immunoreactive products against the EGF receptor were observed in the palatal tissue examined on days 12, 13, and 14 of gestation. On days 12 and 13, the immunoreactive products were predominantly positive on the oral and medial edge epithelia but were minimal on the epithelium of the vertical shelf. The EGF receptor immunoreactivity was less intense in the posterior palate as compared with the midpalatal region. In the fusing palate of day 14 fetuses, the cells forming the midline epithelial seam were continuously positive for EGF-R immunoreactivity. The mesenchyme of palatal shelves also showed regional heterogeneity and temporal sequence in EGF receptor expression. The localization of the EGF receptor in fetal mouse palates cultured in a serumless medium generally simulated that observed in vivo.

Animals↗

PubMed1990

Morphological observations in normal primary palate and cleft lip embryos in the Kyoto collection.

Normal developmental events during human primary palate formation and alterations associated with cleft lip remain poorly defined. The purpose of this study was to analyze serially sectioned human embryos to identify morphological changes during normal palatal closure and alterations associated with failure of palatal formation. Normal and cleft embryos from the histological collection at the Congenital Anomaly Research Center at the University of Kyoto were studied and photographed for detailed evaluation. Seven serially sectioned cleft lip embryos of stages shortly after primary palate formation (Streeter-O'Rahilly stages 19, 20, and 22) with unilateral or bilateral clefts with varying degrees of clefting were studied. In the normal Kyoto embryos, initial nasal fin (epithelial seam) formation was observed between the medial nasal process and the lateral nasal and maxillary processes at stage 17. During stages 18 and 19, the nasal fin epithelium was replaced by an enlarging mesenchymal bridge, as the maxillary processes united with the medial nasal processes to form the primary palate. The most prominent features observed in the cleft embryos were a reduced thickness of mesenchymal bridging between the medial nasal and maxillary processes, with an excessive amount of epithelium at the junctions between these processes. With ingrowth of the maxillary processes, greater cell dispersion and apparent extracellular matrix accumulation were observed in the medial nasal region. During closure of the primary palate, terminal branches of the maxillary nerve crossed the mesenchymal bridge to the medial nasal region. The partial clefts had reduced maxillary ingrowth and smaller union areas with the medial nasal process. Detailed studies of experimental animal models are required to identify regional growth required for contact between the facial prominences, to clarify the mechanisms of mesenchymal ingrowth and epithelial displacement during palatal formation, and to identify local and/or general factors causing alterations that lead to primary palatal clefting.

Cleft Lip↗

PubMed1990

Hyper-running activity originating from the hypothalamus is blocked by GABA.

Our previous study showed that injection of the hydrogel of a water-absorbent polymer (WAPGEL) into the ventromedial nucleus of the hypothalamus (VMH) induced stereotyped long-lasting running activity without association of any aggressive reactions, and suggested that swelling of the polymer at the site of injection affected the inhibitory neuron system, resulting in the expression of running activity. In the present study, we injected WAPGEL impregnated with different doses of GABA. By this treatment, the expression of running activity was inhibited in a dose-dependent manner. Contrarily, microinjection of a GABA-A receptor blocker, bicuculline methiodide (BM), released the running reaction in a dose-dependent manner with similar features to that induced by WAPGEL. It is suggested that the running-related neurons in the VMH are inhibited by GABA when the animals are at rest.

Aggression↗

PubMed1990

Susceptibility to cyclophosphamide and thalidomide of fetal rat limb buds grafted in athymic (nude) mice.

Limb buds of day-14 rat fetuses were cut into pieces and transplanted into athymic (nude) mice. On the 7th and 9th days after grafting, the host nude mice were given cyclophosphamide intraperitoneally (10-120 mg/kg) or thalidomide orally (30-240 mg/kg). On the 20th day, the grafted tissue was examined macroscopically and histiologically. The grafts maintained in vehicle-treated nude mice showed considerable growth and tissue differentiation similar to in vivo. Growth and histogenesis of the grafts were significantly inhibited by treatment with cyclophosphamide (greater than or equal to 20 mg/kg). There was no indication that treatment with thalidomide (less than or equal to 240 mg/kg) adversely affects the development of grafted limbs. Thus, the susceptibility of transplanted rat limb buds to these two human teratogens was identical to the susceptibility of living rat fetuses. The heterotransplantation method of embryonic tissues may be of potential use for the study of teratogenic mechanisms and for the screening of human teratogens.

Animals↗

PubMed1990

Teratogenic drugs inhibit the differentiation of fetal rat limb buds grafted in athymic (nude) mice.

Forelimb buds of day-14 rat fetuses were cut into pieces and transplanted subcutaneously into athymic (nude) mice. On the 7th, 9th, and 11th days after grafting, the nude mice were treated with various drugs including rat teratogens. On the 20th day, the grafted tissue was examined macroscopically and histologically. While control grafts showed substantial growth and tissue differentiation similar to that observed in vivo, the differentiation of grafts was significantly inhibited by the treatment with 5-fluorouracil, cyclophosphamide, hydroxyurea, cycloheximide, mitomycin C, caffeine, aspirin, retinol palmitate, all-trans-retinoic acid, and ascorbic acid. Hydrocortisone, tetracycline, and thalidomide did not adversely affect the differentiation of grafts. Thus, the susceptibility of transplanted rat limb buds was generally close to the teratologic sensitivity of rat fetuses in vivo. The heterotransplantation method of embryonic tissues may be useful as a new experimental system in developmental toxicology.

Animals↗

PubMed1990

Development of the fetal mouse palate in suspension organ culture.

Explanted palates of day 12 and day 13 mouse fetuses were cultured in a chemically defined serumless medium for 48-72 h by a suspension culture technique. The palate of day 12 fetuses closed successfully within 72 h and that of day 13 fetuses within 48 h. Both macroscopically and histologically, the in vitro fusion of palatal shelves simulated the palatogenetic process in vivo. This novel technique for culturing the fetal mouse palate may be of potential use for the study of palatogenesis and in developmental toxicology.

Animals↗

PubMed1990

Growth and differentiation of fetal rat limb buds transplanted in athymic (nude) mice.

Limb buds of day 14 rat fetuses were cut into pieces and transplanted into the subcutaneous tissue of athymic (nude) mice. In day 14 fetal limbs, mesenchymal cells have begun to condense to form cartilaginous anlage, but no cartilage has been formed. Within 7 days after grafting, masses of hyaline cartilage developed. Numerous osteoblasts appeared, and new bone formation began by 14 days. By 20 days, osteoclasts appeared, and the formation of bone trabeculae and marrow cavities progressed. The cytological characteristics of chondrocytes, osteoblasts and osteoclasts were essentially the same as those seen in vivo. Many grafts developed into long bones, having the diaphysis and epiphysis. The mode of chondrogenesis and osteogenesis in the grafts was histologically similar to the corresponding process in vivo, although the differentiation was slower in the grafted limbs. Since the grafted limb buds showed remarkable growth and tissue differentiation for at least several weeks, this heterotransplantation system would be of potential use for the study of bone formation and resorption as well as for developmental toxicological studies.

Animals↗

PubMed1990

Possible role of transforming growth factor-beta as a mediator of luteotropic action of prolactin in rat luteal cell cultures.

PRL is known to be a hormone carrying luteotropic action in rats and enhances progesterone secretion by suppressing 20 alpha-hydroxysteroid dehydrogenase (20 alpha HSD) activity in the corpus luteum. In this study, we investigated the effects of PRL and transforming growth factor-beta (TGF beta) on the 20 alpha HSD activity of rat luteal cells in vitro and examined whether TGF beta is involved in the luteotropic action of PRL. 20 alpha HSD activity of luteal cells (from midpseudopregnant rats), which had been suppressed by PRL in vivo, increased when the cells were cultured for 48 h without PRL addition. TGF beta (0.01, 0.1, 1.0, and 10.0 ng/ml) as well as PRL (2, 20, 200, and 2000 ng/ml) suppressed this increase in a dose-dependent manner. Furthermore, the suppressive effect of PRL on 20 alpha HSD activity was significantly attenuated by anti-TGF beta antibody. Activin, having homology with TGF beta in its chemical structure, also suppressed the increase in enzyme activity, although the effect was much less marked than that of TGF beta. TGF beta or PRL did not affect total progestin (progesterone plus 20 alpha-dihydroprogesterone) secretion, but induced reduction in 20 alpha-dihydroprogesterone secretion during a 48-h culture period, without any alteration of DNA or protein content per culture dish. These results indicate that TGF beta, like PRL, can suppress luteal 20 alpha HSD activity without producing nonspecific cell damage, and that the luteotropic action of PRL is at least in part mediated by TGF beta or an immunoreactive TGF beta-like substance(s).

20-alpha-Dihydroprogesterone↗

PubMed1990

Endocrinological studies on TAP-144-SR, a sustained-release formulation of a potent GnRH agonist (D-Leu6-[des-Gly10-NH2]-GnRH ethylamide), in male rats.

The paradoxical effects of TAP-144-SR, a biodegradable sustained-release formulation of a potent GnRH agonist (TAP-144, leuprolide acetate) were evaluated in male rats by comparing its potency with that of TAP-144 solution. A single sc injection of TAP-144-SR (equivalent to 0.1 mg/kg/day as TAP-144), prepared by encapsulating the agonist in microcapsules of copoly (DL-lactic/glycolic acid), suppressed serum levels of androgens, and the levels remained suppressed for 4 weeks. The potency of the paradoxical effects of TAP-144-SR was evaluated 4 weeks after treatment by comparing it with that of TAP-144 solution administered daily for 4 weeks. Both daily injections of TAP-144 solution and a single injection of TAP-144-SR (equivalent to 0.02, 0.2 or 2 mg/kg/day as TAP-144) decreased the weight of the testes, prostates and seminal vesicles in a dose-dependent manner in a 4-week assay in male rats. TAP-144-SR was more effective than TAP-144 solution in reducing these organ weights. Serum and pituitary concentrations of LH and FSH and serum testosterone levels were also lower in TAP-144-SR-treated than in TAP-144 solution-treated rats. These results indicate that the paradoxical effects were more extensive upon TAP-144-SR treatment, suggesting that maintaining constant serum TAP-144 levels results in more extensive desensitization of the pituitary and testes. These results also suggest advantages of TAP-144-SR over TAP-144 solution in both efficacy and convenience as an anti-prostatic tumor agent.

Androgens↗

PubMed1990

Participation of ovarian 20 alpha-hydroxysteroid dehydrogenase in luteotrophic and luteolytic processes during rat pseudopregnancy.

In normal rats, before Day 12 of pseudopregnancy, minimal levels of 20 alpha-HSD activity were detected in functional CL whereas those in the residue were 3-5 times higher. When ovulation was blocked for more than 2 weeks by placing rats in a continuously lit environment before the induction of pseudopregnancy, only minimal levels of 20 alpha-HSD activity were detectable in the functional CL and residue before Day 12. In normal pseudopregnant rats, there was a linear increase in 20 alpha-HSD activity from Day 12 to 15 in the functional CL and residue, but the rate of elevation was much higher in functional CL. This tendency was much more clear-cut in rats in the continuous lighting. In immature rats in which pseudopregnancy was induced by PMSG and hCG treatment, 20 alpha-HSD activity peaked twice. The first small peak was attributed to the early regression of some of the large number of corpora lutea, and the changes in 20 alpha-HSD activity in most of the corpora lutea paralleled those in rats in continuous lighting. Bromocriptine abolished the prolactin surges, and in normal pseudopregnant rats an increase in 20 alpha-HSD activity in functional CL started from 12 h and the rate of the increase was accelerated from 36 h afterwards, while a relatively small increase was observed in the residue at 18 h and later.(ABSTRACT TRUNCATED AT 250 WORDS)

20-alpha-Dihydroprogesterone↗

PubMed1990

[A case of mediastinal schwannoma originating from the thoracic vagal nerve complicated by early stomach cancer].

Most of primary tumors of the nerves arising in the mediastinum originate from the sympathetic or intercostal nerves. Schwannoma developing from the vagal nerve is very rare. The patient was a 73-year-old male referred to us with abnormal chest X-rays and stomach cancer. One-staged operation was performed by thoracic and upper abdominal median incision. The tumor was removed, which measured 6 X 5 X 4 cm and involved the origin of the left recurrent nerve, by neurectomy. To our knowledge, this was the 18th reported case of schwannoma of the intrathoracic vagal nerve in Japan. A similar schwannoma was observed also in the celiac plexus, and this case was also a rare instance of multiple schwannoma.

Aged↗

PubMed1990

[Protective effect of calcium channel blockers on the liver against halothane hepatitis in rats].

This study examined whether nifedipine or flunarizine, calcium channel blockers, could protect the liver against halothane hepatotoxicity in rats. Six groups of 102 enzyme-induced male Sprague-Dawley rats were studied. Group N1 and N2 rats received nifedipine 20 micrograms and 100 micrograms.kg-1.day-1, and group F1 and F2 rats received flunarizine 100 micrograms and 1mg.kg-1.day-1 in their drinking water for 24 hours prior to the experiment. They were then anesthetized with N2-O2-halothane 0.5% under the condition of hypoxia (FIO2 0.12) for two hours. Animals in group H were given clear water, and then anesthetized with halothane and hypoxia. Animals in group C were given clear water and exposed to hypoxia alone. Twenty-four hours after anesthesia, all animals were decapitated and their liver specimens were stained with H&E for the examination by light microscopy. Eighty percent of rats in group H showed centrilobular degeneration, but administration of nifedipine or flunarizine reduced the incidence significantly. Furthermore, histological score graded from 0 to 3, according to the degree of centrilobular degeneration was also significantly reduced by administration of nifedipine or flunarizine. These results suggest that oral administration of nifedipine or flunarizine could prevent the incidence of halothane-induced hepatotoxicity in enzyme-induced rats, probably by preventing the increase in cytosolic calcium concentration.

Animals↗

PubMed1990

[Clinical experience with ceftibuten in complicated urinary tract infections].

Twenty-four patients with complicated urinary tract infections (UTI) were received ceftibuten (CETB) 400 mg b.i.d. orally for 5 days, and the following results were obtained. One of the recipients was excluded for negative bacteriuria before treatment. According to the criteria for evaluation of clinical efficacy of antimicrobial agents on UTI, 23 patients were assessed: 9 of them were judged to show excellent responses, 6 to have moderate responses and 8 poor responses. The overall efficacy was 65%. Four patients with indwelling catheter failed to show positive clinical response, but 15 out of 19 patients without indwelling catheter responded positively. As to bacteriological responses, organisms included Gram-positive cocci were eradicated in 28, replaced in 9 and persisted in 6 strains. Of 24 Gram-negative rods except 1 strain of Pseudomonas sp., 23 (96%) were eradicated. Safety evaluation was made in all 24 patients received CETB. No adverse reactions were observed in any cases. As to laboratory test results, slight, transient elevations of GOT, GPT and Al-P of serum were noted in 1 patient. Their values, however, returned to normal levels in 4 weeks.

Adult↗

PubMed1989

The ventromedial nucleus of the hypothalamus outputs long-lasting running in rats.

We have developed a new technique for altering neural construction by implanting self-swelling, the hydrogel of water-absorbent polymer (WAPGEL) into restricted areas of the brain. Using this technique, we found that the VMH is responsible for expression of running activity. Implantation of 1.5 microliters of WAPGEL into the dorsomedial portion of the ventromedial nucleus of the hypothalamus (VMH) of the rat specifically induced bursts of running, whereas implantation into other sites of hypothalamus, e.g., the anterior, lateral and posterior areas, and the dorsomedial nucleus, caused no significant running activity. The WAPGEL-injected rat showed less aversive reactions than the sham-operated rat. Since deafferentation of the VMH after WAPGEL injection prevented the induction of running activity, the output from the VMH appeared to be responsible for the running activity.

Animals↗

PubMed1989

Maternal fertility, reproductive loss, and defective human embryos.

It is possible that many abnormal conceptuses are lost at an early stage without the mother's knowledge. To investigate this further the reproductive history of the mothers of defective embryos (neural tube defects, holoprosencephaly, cleft lip, polydactyly, and early embryonic resorption) was compared with that of the mothers of normal embryos. The frequency of prior miscarriages was higher in the case mothers than in normal controls matched for maternal age and gravidity, the difference being significant for all the anomalies except for polydactyly. The case mothers had fewer prior recognised pregnancies than control mothers matched for maternal age. There were more primigravid mothers in abnormal groups, and the difference from controls was significant for neural tube defects. It was assumed that the gravidity of the case mothers may be underestimated, possibly due to increased early abortions which are not recognised clinically. Thus, it seems that both recognised and unrecognised abortions occur more often in the mothers of defective embryos. Since many spontaneous abortuses are morphologically and/or cytogenetically abnormal, some women appear to conceive abnormal embryos repeatedly. Most of these embryos, however, may be screened out prenatally and escape clinical detection. Information on prior reproductive history of the woman should be examined carefully in genetic counselling.

Abortion, Habitual↗