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H Kurachi

Publications and source records attributed to H Kurachi.

18 recordsLinked to original sources
PubMed1992

A new member of the insulin receptor family, insulin receptor-related receptor, is expressed preferentially in the kidney.

Shier and Watt isolated human and guinea pig genomic DNA encoding a putative protein, insulin receptor-related receptor (IRR), the primary structure of which is similar to that of other members of the insulin receptor family, the insulin receptor and type-I IGF receptor (J. Biol. Chem. 264, 14605-14608 (1989)). However, the expression of the IRR gene remained unknown. In this paper, we isolated the IRR cDNA from the rat brain and examined the expression of the IRR mRNA in a variety of rat tissues, including the brain, heart, lung, liver, small intestine, kidney, thymus, spleen, muscle, adipose tissue and cartilage by polymerase chain reaction. In contrast to the wide distribution of the insulin receptor and type-I IGF receptor mRNAs, the IRR mRNA is expressed preferentially in the kidney, which indicates that IRR has unique functions as a member of the insulin receptor family.

Amino Acid Sequence↗
PubMed1992

Activin A increases cytosolic free calcium concentration in rat pituitary somatotropes.

The effect of activin A on the cytosolic free calcium concentration ([Ca2+]i) in normal rat pituitary cells was examined using a calcium sensitive fluorescent dye, indo 1 AM, and a digital imaging fluorescent microscope system. The cells showing an increase in [Ca2+]i in response to activin A were then characterized by comparison with cells responding to growth hormone releasing hormone (GRH), thyrotropin releasing hormone (TRH), corticotropin releasing hormone (CRH), and gonadotropin releasing hormone (GnRH) in monolayer cultures of normal rat pituitary cells. Activin A increased [Ca2+]i in some cells in a mixed population of normal rat pituitary cells. The cells that responded to activin A also responded to GRH. Most of these cells were not affected by other tropic hormones (CRH, TRH, and GnRH), but a few cells responded to both GRH and TRH. None of the activin A-responding cells responded to CRH or GnRH, and none of the CRH- or GnRH-responding cells responded to activin A. In a preparation of somatotropes purified 80-90% by fluorescence-activated cell sorting, activin A increased [Ca2+]i in 30% of the cells that shows a [Ca2+]i-response to GRH. These findings suggest direct involvement of somatotropes in activin A-induced biological events in the rat pituitary gland.

Activins↗
PubMed1992

Binding sites for interleukin-6 in the anterior pituitary gland.

Interleukin-6 (IL-6) binding site in the rat anterior pituitary gland was characterized using radioiodinated human recombinant (hr) IL-6. Results showed that the anterior pituitary gland contained 170 binding sites per cell of a single class with a dissociation constant of 2.7 x 10(-9) M. The binding of 125I-hrIL-6 to the rat anterior pituitary gland was competitively inhibited by unlabeled hrIL-6, but not by hrIL-1 alpha, hrIL-1 beta, hrIL-2 or hr-interferon-gamma, indicating these binding sites are specific for IL-6. We also demonstrated mouse IL-6 receptor gene expression in the rat anterior pituitary gland by Northern blot analysis. Furthermore, the IL-6 receptor was detected on human gonadotrophs by the double immunofluorescence method. Our findings demonstrate the presence and expression of IL-6 binding site in the rat anterior pituitary gland and the presence of IL-6 binding site on human gonadotrophs, suggesting the important role of IL-6 binding site in pituitary hormone release in both species.

Animals↗
PubMed1992

Vasoactive intestinal peptide enhances dopamine accumulation in primary cell culture of rat hypothalamus.

The effect of vasoactive intestinal peptide (VIP) and PHI-27 on dopamine accumulation in cultured rat hypothalamic cells was investigated. VIP enhanced [3H]dopamine accumulation dose dependently. This effect was significant at 10(-8)-10(-5) M VIP with a concomitant increase in intracellular cyclic AMP (cAMP), and reached its plateau level at 10(-6) M VIP. VIP increased [3H]dopamine accumulation significantly within 15 min. PHI-27 and dibutyryl cAMP ((Bu)2-cAMP) also enhanced [3H]dopamine accumulation. These results suggest that VIP enhances dopamine accumulation in hypothalamic cells by increasing intracellular cAMP.

Animals↗
PubMed1992

Intraventricular administration of thyrotrophin-releasing hormone (TRH) suppresses prolactin secretion and synthesis: a possible involvement of dopamine release by TRH from rat hypothalamus.

The administration of thyrotrophin-releasing hormone (TRH) causes a variety of dopamine-related biological events. To understand the specific role of TRH on rat hypothalamic dopamine neurones, we examined the in-vivo effects of intraventricular (i.c.v.) infusion of TRH on the release and synthesis of prolactin in the rat pituitary gland and on the changes in binding of [3H]MeTRH and dopamine turnover rates in rat hypothalamus. We have also examined the in-vitro effects of TRH on the release of [3H]dopamine from dispersed tuberoinfundibular dopamine neurones. Female rats were treated with i.c.v. infusions of 1 mumol TRH/1 daily for 1, 3 and 7 days using Alzet osmotic pumps. Following 7 days of treatment the serum prolactin concentrations were significantly decreased. A reduction in hypothalamic TRH-binding sites (Bmax) was also apparent but the dissociation constant (Kd) was unaffected. Northern blot analysis of total RNA isolated from the pituitary glands of control animals using 32P-labelled prolactin cDNA as a probe indicated the presence of three species of prolactin gene transcripts of approximately 3.7, 2.0 and 1.0 kb in size, and these were decreased by TRH treatment. We examined the turnover rate of dopamine in the rat hypothalamus when TRH was administered i.c.v. for 7 days. There was a significant increase in 3,4-dihydroxyphenylacetic acid/dopamine ratio with TRH treatment. Moreover, exposure to TRH stimulated [3H]dopamine release from rat tuberoinfundibular neurones in a time- and dose-dependent manner. Dopamine receptor antagonists such as SCH23390 and (-)sulpiride, and other neuropeptides such as vasoactive intestinal peptide and oxytocin did not affect TRH-stimulated [3H]dopamine release.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1991

Involvement of transforming growth factor alpha/epidermal growth factor receptor autocrine growth mechanism in an ovarian cancer cell line in vitro.

Although transforming growth factor (TGF) alpha and epidermal growth factor (EGF) receptor (EGFR) autocrine mechanism is widely demonstrated in many kinds of cancers, its biological significances still remain circumstantial. We critically assessed the significance of this mechanism on the growth of an ovarian cancer cell line. Northern blot analysis in polyadenylated RNA isolated from cells by using 32P-labeled pre-TGF alpha, EGRF, and prepro-EGF complementary DNAs as probes revealed that pre-TGF alpha and EGFR but not prepro-EGF gene transcripts were expressed in the cell. TGF alpha and EGFR but not EGF proteins were observed by immunocytochemical stainings, using monoclonal antibodies against human TGF alpha, EGFR, and EGF, respectively. This cell line possessed a class of high affinity EGF receptor by 125I-EGF binding studies; Kd being 2.9 x 10(-10) M and Bmax to be 7.7 x 10(4) sites/cell. As much as 1.12 +/- 0.14 ng (SD; n = 3)/10(7) cells/24 h of TGF alpha was secreted in the conditioned media. These results suggested the expression of a TGF alpha/EGFR autocrine mechanism in this cell line. We, therefore, assessed the biological significance of this mechanism on the growth of this cell line in serum-free monolayer cell cultures. Although 0.1, 1.0, and 10 nM concentrations of TGF alpha did not show significant growth promotion, monoclonal antibodies against TGF alpha and EGFR but not EGF significantly inhibited cell growth. All these data suggested the biological importance of a TGF alpha/EGFR autocrine mechanism on the growth of this cell line in vitro.

Antibodies, Monoclonal↗
PubMed1991

Importance of transforming growth factor alpha/epidermal growth factor receptor autocrine growth mechanism in an ovarian cancer cell line in vivo.

We have elucidated the importance of a transforming growth factor (TGF) alpha and epidermal growth factor receptor autocrine mechanism on the growth of a human ovarian serous cystadenocarcinoma-derived cell line (SHIN-3) in vitro. In this study, we studied the biological significance of this autocrine mechanism in vivo using female athymic nude (nu/nu) mice. We measured the mouse plasma epidermal growth factor and TGF alpha levels by radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Plasma epidermal growth factor concentrations were remarkably decreased by sialoadenectomy (Sx): 410 +/- 65 (SE) pg/ml (n = 10) in intact animals; and undetectable in Sx mice (n = 5). Plasma TGF alpha levels were 90 and 40 pg/ml in intact and in Sx animals, respectively. Ten million SHIN-3 cells inoculated into nu/nu mice formed tumors in 100% of mice, and tumors grew progressively. Implantabilities and tumor growth rates of inoculated cells were not affected by Sx and even by Sx and anti-mouse epidermal growth factor antibody treatment. However, anti-TGF alpha monoclonal antibody (mAb) administered to SHIN-3 cell-inoculated Sx animals drastically reduced the tumor growth. Although 10(7) SHIN-3 cells formed tumors in this group, tumor growth was significantly inhibited by 10 micrograms of anti-TGF alpha mAb given 3 times a week, and growth inhibitions were more by 20 micrograms of anti-TGF alpha mAb. Moreover, as aggressive tumor growth as that in Sx animals was resumed by the cessation of anti-TGF alpha mAb treatments. All these data suggested the biological importance of a TGF alpha/epidermal growth factor receptor autocrine mechanism on the growth of this cell line in vivo.

Animals↗
PubMed1991

Evidence for the involvement of transforming growth factor alpha and epidermal growth factor receptor autocrine growth mechanism in primary human ovarian cancers in vitro.

We examined 35 primary human ovarian adenocarcinomas for the presence of epidermal growth factor (EGF) receptor (EGFR) in plasma membranes from cancer tissues by using 125I-EGF as a ligand. Specific 125I-EGF bindings were observed in 20 (57%) of these 35 cases. Scatchard analysis showed a class of high affinity EGF receptor: Kd 5.0 +/- 1.0 x 10(-10) M; Bmax, 83.3 +/- 12.1 fmol/mg protein (mean +/- SE, n = 20). Northern analysis in polyadenylated RNA from 15 EGFR(+) cancers using pretransforming growth factor alpha (pre-TGF alpha), prepro-EGF complementary DNA, and pE7, a complementary DNA clone of human EGFR, as probes revealed that pre-TGF alpha and EGFR mRNAs but not prepro-EGF mRNA were expressed in all cases examined. Immunocytochemical studies using monoclonal antibodies (mAbs) against TGF alpha, EGF, and EGFR showed that TGF alpha and EGFR but not EGF proteins were present on ovarian cancer cells in all cases. These data suggested a possible TGF alpha/EGFR autocrine mechanism in EGFR(+) ovarian cancers. We, therefore, examined the biological significance of this autocrine mechanism by using primary monolayer cell cultures. In primary cultures from EGFR (+) cancers, TGF alpha added to the culture medium stimulated the [3H]thymidine incorporation dose dependently. Moreover, the addition of mAbs against TGF alpha and EGFR but not EGF inhibited [3H]thymidine incorporation dose dependently in EGFR(+) cancer cells. On the other hand, in primary cultures from EGFR(-) cancers, TGF alpha and anti-TGF alpha, -EGFR, and -EGF mAbs did not show any effects on [3H]thymidine incorporation. All these results suggested the possible crucial role of a TGF alpha/EGFR autocrine growth mechanism in primary human ovarian cancers which express EGFR.

Adenocarcinoma↗
PubMed1991

Epidermal growth factor attenuates cell proliferation by down-regulating the transforming growth factor-beta receptor in the osteoblastic cell line MC3T3-E1.

We investigated the role of transforming growth factor beta 1 (TGF-beta 1) in growth regulation of the murine osteoblastic cell line, MC3T3-E1. We detected TGF-beta activity in the conditioned medium of MC3T3-E1 cells and its activity was increased by acid treatment of the bioassay system using CC1 64 cells. Northern blot analysis revealed the expression of TGF-beta 1 precursor messenger ribonucleic acid (mRNA). MC3T3-E1 cells possessed a single class of high affinity TGF-beta 1 receptor (2.8 x 10(4) sites per cell, Kd = 196 pM). Cross-linking studies revealed three specific TGF-beta receptors with molecular masses of 65, 95 and 280 kDa. Both TGF-beta and epidermal growth factor (EGF) stimulated [3H]-thymidine incorporation into cells. EGF decreased the number of TGF-beta receptor dose-dependently, and pretreatment of cells with 10 nM EGF attenuated cell growth by TGF-beta. All these data suggested that TGF-beta might be an autocrine growth factor in murine osteoblastic MC3T3-E1 cells and that EGF might modulate the growth of cells by down-regulating the TGF-beta receptor level.

Animals↗
PubMed1991

Decrease in epidermal growth factor receptor and its messenger ribonucleic acid levels in intrauterine growth-retarded and diabetes mellitus-complicated pregnancies.

We measured the amounts of epidermal growth factor receptor (EGFR) in plasma membranes from human placentas at term delivery in three groups: appropriate for gestational age (AGA), intrauterine growth-retarded (IUGR), and diabetes mellitus-complicated (DM) pregnancies. At the same time, EGFR mRNA levels were examined in three groups by dot and Northern blot analyses. Binding studies were performed using 125I-labeled human EGF as a ligand, and two classes (high and low) of binding sites were found in all specimens. Although dissociation constants (Kd) were not significantly different among three groups, the number of binding sites was significantly decreased in IUGR and DM placentas compared to that in the AGA group. Total cellular RNA was isolated from a part of the placentas used for binding studies using the guanidinium CsCl method, denatured, and dot blotted onto nitrocellulose filter. Poly(A)+ RNA was selected from the total RNA, electrophoresed in 1% agarose gel, and transferred onto nitrocellulose filters. Then, hybridization with 32P-labeled pE7 (a cDNA of EGFR), autoradiography, and densitometry were performed. The amounts of mRNA hybridized with pE7 were reduced in IUGR and DM placentas compared to that in the AGA group. The molecular sizes of EGFR mRNA were 10 and 5.6 kilobases in all three groups. These results suggest possible physiological actions of EGF on adequate feto-placental growth and development in human pregnancy.

Diabetes Mellitus↗
PubMed1990

Changes of bioactive luteinizing hormone after laparoscopic ovarian cautery in patients with polycystic ovarian syndrome.

The serum levels of bioactive luteinizing hormone (LH), immunoreactive LH, follicle-stimulating hormone, androstenedione (A), and testosterone (T) were determined in nine anovulatory women with polycystic ovarian syndrome (PCOS) before and after laparoscopic ovarian cautery. Eight ovulated spontaneously and three conceived after treatment. Before treatment, the mean (+/- SEM) levels of bioactive LH, immunoreactive LH, A, and T were 51.4 +/- 8.6 mIU/mL, 36.0 +/- 4.5 mIU/mL, 1.98 +/- 0.35 ng/mL, and 1.18 +/- 0.13 ng/mL, respectively, which were significantly higher than those of five control women (19.2 +/- 1.6 mIU/mL, 21.4 +/- 1.2 mIU/mL, 0.54 +/- 0.03 ng/mL, 0.28 +/- 0.03 ng/mL). After treatment, the mean levels of these hormones had significantly decreased. Decreases in the levels of these hormones by laparoscopic ovarian cautery in women with PCOS may result in both restoration of the ovulatory cycle and achievement of pregnancy.

Adult↗
PubMed1990

Electrocautery in polycystic ovary syndrome.

The serum levels of bioactive luteinizing hormone (LH), immunoreactive LH, follicle-stimulating hormone (FSH), and testosterone were determined in eleven anovulatory women with polycystic ovary syndrome (PCOS) before and after laparoscopic ovarian cautery. Before treatment, the mean +/- SEM levels of bioactive and immunoreactive LH and testosterone were 53.1 +/- 7.9 mIU/ml, 35.2 +/- 3.9 mIU/ml, and 1.14 +/- 0.13 ng/ml, respectively, which were significantly higher than those of five control women (19.2 +/- 1.6 mIU/ml, 21.4 +/- 1.2 mIU/ml, 0.28 +/- 0.03 ng/ml). After treatment, the mean levels of these hormones decreased significantly, ten women ovulated spontaneously and four conceived. The present results suggests that decreases in the levels of these hormones by laparoscopic ovarian cautery in women with PCOS may result in both restoration of the ovulatory cycle and the achievement of pregnancy.

Adult↗
PubMed1989

Suppression of serum immunoreactive human epidermal growth factor by acute increase in prolactin in women.

Epidermal growth factor (EGF) is known to stimulate proliferation of various mammalian cells and secretion of prolactin (PRL) from rat anterior pituitary tumor cells. The effect of an acute increase in serum PRL induced by thyrotropin releasing hormone (TRH) or metoclopramide (MCP) on the serum immunoreactive EGF concentration was examined in nine hyperprolactinemic patients and eight normoprolactinemic women. The basal level of serum EGF in normoprolactinemic subjects was 472.8 +/- 51.1 pg/ml (Mean +/- SEM), which was not significantly different from that in hyperprolactinemic patients (487.8 +/- 22.5 pg/ml). The serum EGF concentration was decreased to 40-50% of the basal level after the abrupt increase in serum PRL induced by the injection of TRH or MCP in normoprolactinemic subjects, but no significant change in serum EGF occurred in hyperprolactinemic patients after MCP injection, in spite of a significant increase in PRL. These results suggest that an acute increase of serum PRL in normoprolactinemic women, but not in hyperprolactinemic patients, suppresses serum EGF.

Adenoma↗
PubMed1979

Restoration of the gonadotrophin response to LH-RH and oestrogen administration in patients after molar abortion.

The relation of the hypothalamic-pituitary effect on gonadotrophin secretion and the concentration of serum hCG after molar abortion was investigated. Gonadotrophin release after a bolus injection of LH-RH or conjugated oestrogens was observed in 17 women until 5 months after molar abortion. Little if any response of gonadotrophin was observed at a hCG level of 100 mIU/ml or more, but the response of LH and FSH to LH-RH were restored to normal when the serum hCG level decreased to below 100 mIU/ml. A normal response of LH to conjugated oestrogens was observed at a serum hCG level of 20 mIU/ml or less. These findings suggest that a high level of hCG interferes with pituitary gonadotrophin secretion, that the threshold hCG levels for normal responses of gonadotrophins to LH-RH and oestrogen are 100 and 20 mIU/ml, respectively, and that secretion of gonadotrophins is restored even in the presence of a low hCG level.

Adult↗
PubMed1979

Endocrine and androgen-receptor studies in a patient with XY gonadal agenesis.

A 19-year-old phenotypic female with gonadal agenesis and XY karyotype underwent an endocrinologic study. She lacked secondary sexual characteristics and there was posterior labial fusion, absence of vagina, and no gonadal or gonadal duct tissues present at laparotomy. Elevated levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) responded well to intravenous injection of LH-releasing hormone (LH-RH) but did not respond to clomiphene citrate. Both OH and FSH levels were suppressed by administration of testosterone or estrogen. Low serum concentration of testosterone did not respond to human chorionic gonadotropin (hCG) injection. Dihydrotestosterone binding by cultured skin fibroblast revealed the existence of a binding component with low capacity and high affinity. This is the first report of a patient with XY gonadal agenesis in whom androgen receptors in the target cells are demonstrated.

Adult↗
PubMed1977

Pregnancy following thyroid hormone treatment in a patient with amenorrhea-galactorrhea due to primary hypothyroidism.

A 32-year-old female with amenorrhea-galactorrhea due to primary hypothyroidism was treated with thyroid hormones, and serum levels of thyrotropin (TSH), prolactin (PRL), triiodothyronine (T3), thyroxin (T4), and T3 resin sponge uptake (RT3U) were measured throughout the course of treatment. The elevated serum levels of TSH and PRL fell into the normal range following T3 treatment. Subsequently, the menstrual cycle was restored within 1 month, and galactorrhea completely ceased and conception was achieved within 3 months. Desiccated thyroid was administered during pregnancy, and the patient gave birth to a female infant. Impaired secretion of PRL during pregnancy and poor milk secretion with blunted response of PRL to the suckling stimulus during the puerperium were noted.

Adolescent↗