Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Yasuhiko Kamada is active.

Publication


Featured researches published by Yasuhiko Kamada.


Gynecologic and Obstetric Investigation | 1999

Clinical Experience of Long-Term Transdermal Treatment with Nitric Oxide Donor for Women with Preeclampsia

Mikiya Nakatsuka; Katsuhiko Tada; Yoshihiro Kimura; Kazuo Asagiri; Yasuhiko Kamada; Masayo Takata; Takakimi Nakata; Nanako Inoue; Takafumi Kudo

Isosorbide dinitrate (ISDN), a nitric oxide donor, was applied transdermally for 4–16 days to 4 preeclamptic women with oligohydramnios, intrauterine fetal growth retardation (IUGR), and elevated resistance of blood flow in the uterine arteries. Pulsed Doppler ultrasonography revealed immediate and drastic improvement of pulsatility index (PI) of uterine arteries following treatment with ISDN. The average PI in uterine arteries of the 4 patients was reduced to approximately 67% of that of the untreated state. In 2 patients the amniotic fluid gradually increased over a few days which suggested improvement of fetoplacental circulation during administration of ISDN. This study suggests that long-term transdermal ISDN is an effective therapy, at least in a portion of preeclamptic women, to avoid maternal hypertension, fetal distress, oligohydramnios, and IUGR, and consequentially to prolong the gestational period.


International Immunopharmacology | 2003

Nafamostat mesilate suppresses NF-κB activation and NO overproduction in LPS-treated macrophages

Soichi Noguchi; Mikiya Nakatsuka; Hideki Konishi; Yasuhiko Kamada; Chebib Chekir; Takafumi Kudo

Nafamostat mesilate (NM), a clinically used serine protease inhibitor, suppressed the overproduction of nitric oxide (NO) and the expression of inducible nitric oxide synthase (iNOS) in RAW264.7 murine macrophages treated with lipopolysaccharide (LPS, 100 ng/ml); however, it had little effect on endothelial NOS (eNOS) in human umbilical vein endothelial cells (HUVEC). Electrophoretic mobility shift assay (EMSA) revealed that LPS activated nuclear factor-kappaB (NF-kappaB) in RAW264.7 cells and that this activation was suppressed by nafamostat mesilate. Western blotting showed that nafamostat mesilate suppressed the phosphorylation and degradation of inhibitor kappaB-alpha (IkappaB-alpha), which holds NF-kappaB in the cytoplasm in an inactivated state. Our observations suggest that nafamostat mesilate is a candidate agent for various diseases such as ischemia-reperfusion, graft rejection, inflammatory diseases, and autoimmune diseases, in which iNOS and/or NF-kappaB are upregulated.


Acta Obstetricia et Gynecologica Scandinavica | 2005

Impaired uterine perfusion associated with metabolic disorders in women with polycystic ovary syndrome

Chebib Chekir; Mikiya Nakatsuka; Yasuhiko Kamada; Soichi Noguchi; Aiko Sasaki; Yuji Hiramatsu

Background.  Risk factors for cardiovascular disease, including chronic anovulation, obesity, hyperandrogenism, hyperinsulinemia, and dyslipidemia, are commonly observed in women with polycystic ovary syndrome (PCOS). We evaluated uterine perfusion and its correlation with clinical and biochemical parameters in women with PCOS.


Journal of Obstetrics and Gynaecology Research | 2011

Increased arterial stiffness in mildly-hypertensive women with polycystic ovary syndrome

Aiko Sasaki; Yayoi Emi; Miwa Matsuda; Sharula; Yasuhiko Kamada; Chebib Chekir; Yuji Hiramatsu; Mikiya Nakatsuka

Aim:  Although risk factors for cardiovascular disease, such as obesity, hyperinsulinemia, and dyslipidemia, are commonly observed in women with polycystic ovary syndrome (PCOS), impairment of vascular function is still controversial. We evaluated the vascular function in young women with PCOS.


Endocrine Journal | 2015

Pregnancy complications and glucose intolerance in women with polycystic ovary syndrome.

Mari Sawada; Hisashi Masuyama; Kei Hayata; Yasuhiko Kamada; Keiichiro Nakamura; Yuji Hiramatsu

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by insulin resistance and hyperandrogenism. The interaction of these factors might result in increased risks of miscarriage and pregnancy complications such as gestational diabetes mellitus (GDM). To examine the pregnancy risks in women with PCOS, we compared obstetrical outcomes between patients with and without PCOS. We also studied the differences in maternal characteristics, glucose intolerance and pregnancy complications between PCOS patients with and without GDM, with and without obesity, and between successful pregnancies and miscarriages. We observed a high incidence of GDM and prevalence of GDM diagnosis in the first trimester in PCOS. Patients with GDM had higher body mass index (BMI) and lower homeostasis model assessment of β-cell function (HOMA-β) at preconception than those without GDM. Obese pregnant women with PCOS demonstrated a high incidence of GDM with severe insulin resistance, including high fasting insulin, HOMA of insulin resistance (HOMA-IR), and HOMA-β at preconception compared with normal-weight patients. BMI was significantly correlated with HOMA-IR or HOMA-β, and both indices were lower in PCOS patients with than without GDM for the same BMI. There were no significant differences in maternal characteristics (excluding maternal age) between PCOS patients with successful pregnancy and PCOS patients with miscarriages. Our data suggest that pregnant women with PCOS have an increased risk of GDM, especially if they have obesity and/or poorer insulin secretion. Measure of β-cell function, such as HOMA-β, at preconception might be a useful predictor of the risk of GDM in pregnant PCOS patients.


The Journal of Steroid Biochemistry and Molecular Biology | 2017

A regulatory role of androgen in ovarian steroidogenesis by rat granulosa cells

Toru Hasegawa; Yasuhiko Kamada; Takeshi Hosoya; Shiho Fujita; Yuki Nishiyama; Nahoko Iwata; Yuji Hiramatsu; Fumio Otsuka

Excess androgen and insulin-like growth factor (IGF)-I in the ovarian follicle has been suggested to be involved in the pathophysiology of polycystic ovary syndrome (PCOS). Here we investigated the impact of androgen and IGF-I on the regulatory mechanism of ovarian steroidogenesis using rat primary granulosa cells. It was revealed that androgen treatment with dihydrotestosterone (DHT) amplified progesterone synthesis in the presence of FSH and IGF-I, whereas it had no significant effect on estrogen synthesis by rat granulosa cells. In accordance with the effects of androgen on steroidogenesis, DHT enhanced the expression of progesterogenic factors and enzymes, including StAR, P450scc and 3βHSD, and cellular cAMP synthesis induced by FSH and IGF-I. Of note, treatment with DHT and IGF-I suppressed Smad1/5/8 phosphorylation and transcription of the BMP target gene Id-1, suggesting that androgen and IGF-I counteract BMP signaling that inhibits FSH-induced progesterone synthesis in rat granulosa cells. DHT was revealed to suppress the expression of BMP-6 receptors, consisting of ALK-2, ALK-6 and ActRII, while it increased the expression of inhibitory Smads in rat granulosa cells. In addition, IGF-I treatment upregulated androgen receptor (AR) expression and DHT treatment suppressed IGF-I receptor expression on rat granulosa cells. Collectively, the results indicate that androgen and IGF-I mutually interact and accelerate progesterone production, at least in part, by regulating endogenous BMP signaling in rat granulosa cells. Cooperative effects of androgen and IGF-I counteract endogenous BMP-6 activity in rat granulosa cells, which is likely to be functionally linked to the steroidogenic property shown in the PCOS ovary.


Journal of Obstetrics and Gynaecology Research | 2015

Altered autonomic nervous system activity in women with unexplained recurrent pregnancy loss

Kumie Kataoka; Yumi Tomiya; Ai Sakamoto; Yasuhiko Kamada; Yuji Hiramatsu; Mikiya Nakatsuka

Autonomic nervous system activity was studied to evaluate the physical and mental state of women with unexplained recurrent pregnancy loss (RPL).


The Journal of Steroid Biochemistry and Molecular Biology | 2018

Interaction between orexin A and bone morphogenetic protein system on progesterone biosynthesis by rat granulosa cells

Shiho Fujita; Toru Hasegawa; Yuki Nishiyama; Satoshi Fujisawa; Yasuhiro Nakano; Takahiro Nada; Nahoko Iwata; Yasuhiko Kamada; Hisashi Masuyama; Fumio Otsuka

The involvement of orexins in reproductive function has been gradually uncovered. However, the functional role of orexins in ovarian steroidogenesis remains unclear. In the present study, we investigated the effects of orexin A on ovarian steroidogenesis by using rat primary granulosa cells that express both OX1 and OX2 receptors for orexins. Treatment with orexin A enhanced progesterone, but not estradiol, biosynthesis induced by FSH, whereas it did not affect basal levels of progesterone or estradiol. In accordance with the effects on steroidogenesis, orexin A increased the mRNA levels of progesterogenic enzymes, including StAR, P450scc and 3βHSD, but not P450arom, and cellular cAMP synthesis induced by FSH. Under the condition of blockage of endogenous BMP actions by noggin or BMP-signaling inhibitors, orexin A failed to increase levels of progesterone synthesis induced by FSH treatment, suggesting that endogenous BMP activity in granulosa cells might be involved in the enhancement of progesterone synthesis by orexin A. Treatment with orexin A impaired Smad1/5/9 activation as well as Id-1 mRNA expression stimulated by BMP-6 and BMP-7, the latter of which was reversed by treatment with an OX1 antagonist. It was also found that orexin A suppressed the mRNA expression of both type-I and -II receptors for BMPs and increased that of inhibitory Smad6 and Smad7 in granulosa cells. On the other hand, treatments with BMP-6 and -7 suppressed the expression of OX1 and OX2. Collectively, the results indicated that orexin A enhances FSH-induced progesterone production, at least in part, by downregulating BMP signaling in granulosa cells. Thus, a new role of orexin A in facilitating progesterone synthesis and functional interaction between the orexin and BMP systems in granulosa cells were revealed.


Reproductive Sciences | 2017

High Expression of High-Mobility Group Box 1 in Menstrual Blood: Implications for Endometriosis:

Keiko Shimizu; Yasuhiko Kamada; Ai Sakamoto; Miwa Matsuda; Mikiya Nakatsuka; Yuji Hiramatsu

Endometriosis is a benign gynecologic disease characterized by the presence of ectopic endometrium and associated with inflammation and immune abnormalities. However, the molecular basis for endometriosis is not well understood. To address this issue, the present study examined the expression of high-mobility group box (HMGB) 1 in menstrual blood to investigate its role in the ectopic growth of human endometriotic stromal cells (ESCs). A total of 139 patients were enrolled in this study; 84 had endometriosis and 55 were nonendometriotic gynecological patients (control). The HMGB1 levels in various fluids were measured by enzyme-linked immunosorbent assay. Expression of receptor for advanced glycation end products (RAGE) in eutopic and ectopic endometrium was assessed by immunohistochemistry, and RAGE and vascular endothelial growth factor (VEGF) messenger RNA expression in HMGB1- and lipopolysaccharide (LPS)-treated ESCs was evaluated by real-time polymerase chain reaction. The HMGB1 concentration was higher in menstrual blood than in serum or peritoneal fluid (P < .001 for both). RAGE was expressed in both normal and ectopic endometrium. Administration of 1000 ng/mL HMGB1 or coadministration of 100 ng/mL HMGB1 and 100 ng/mL LPS induced VEGF production in ESCs relative to the control (P < .05). These results suggest that menstrual fluid has naturally high levels of HMGB1 and may promote endometriosis following retrograde menstruation when complexed with other factors such as LPS by inducing inflammation and angiogenesis.


Journal of Obstetrics and Gynaecology Research | 2012

Altered arterial stiffness in male‐to‐female transsexuals undergoing hormonal treatment

Sharula; Chebib Chekir; Yayoi Emi; Fujimi Arai; Yukako Kikuchi; Aiko Sasaki; Miwa Matsuda; Keiko Shimizu; Kazuhiro Tabuchi; Yasuhiko Kamada; Yuji Hiramatsu; Mikiya Nakatsuka

Aim:  Male‐to‐female (MTF) transsexuals are treated with estrogen with and without progestin through a variety of routes. The aim of this study is to evaluate the arterial stiffness in MTF transsexuals undergoing hormonal treatment.

Collaboration


Dive into the Yasuhiko Kamada's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge