Mitsutoshi Iwashita

Transforming growth factor (TGF) - α in human milk

Abstract Transforming growth factor (TGF) - α and epidermal growth factor (EGF) were measured in human milk by means of homologous radioimmunoassay. As previously reported, EGF concentration in the colostrum was approximately 200 ng/ml and decreased to 50 ng/ml by day 7 postpartum. The value of immunoreactive (IR) -TGF- α was 2.2–7.2 ng/ml, much lower than that of EGF. In contrast to EGF, the concentration of IR-TGF-α was fairly stable during the 7 postpartum days. There was no relationship between the concentrations of IR-TGF-α and IR-EGF, suggesting that the regulatory mechanism in the release of the two growth factors is different. On gel-chromatography using a Sephadex G-50 column, IR-EGF appeared in the fraction corresponding to that of authentic human EGF, while 70%–80% of the IR-TGF-α was eluted as a species with a molecular weight greater than that of authentic human TGF-α. Although the physiological role of TGF-α in milk is not known, it is possible that it is involved in the development of the mammary gland and/or the growth of newborn infants.

Measurement of endometrial tissue blood flow: a novel way to assess uterine receptivity for implantation

OBJECTIVE To assess endometrial receptivity in terms of endometrial tissue blood flow (ETBF) measured hysterofiberscopically by laser blood-flowmetry, and to examine the techniques effectiveness in an in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) program. DESIGN A prospective clinical study. SETTING(S) IVF program in a university hospital. PATIENT(S) A total of 75 infertile women with normal menstrual cycles undergoing IVF/ICSI. INTERVENTION(S) ETBF, conventional ultrasonographic, endocrinologic, and histologic parameters for receptivity and immunoreactivity for vascular endothelial growth factor (VEGF) in endometrium were assessed between days 4 and 6 of the luteal phase in a spontaneous menstrual cycle. Then all patients underwent IVF/ICSI. MAIN OUTCOME MEASURE(S) Achievement of clinical pregnancy by IVF/ICSI. RESULT(S) ETBF, VEGF expression, and the number of embryos were significantly higher in the women who became pregnant than in those who did not. By stepwise multiple logistic regression, significant predictors of pregnancy were the number of embryos and ETBF but not conventional receptivity markers. The rate of pregnancy was significantly higher in women with ETBF values of at least 29 mL/min per 100 grams of tissue than in women with lower values (42 vs. 15% in 36 and 39 women, respectively). ETBF was significantly greater in morphologically normal than abnormal uteri. In normal uteri, ETBF was greatest in the fundus. Correspondingly, in normal uteri 85% of gestational sacs were implanted in the fundus. CONCLUSION(S) ETBF is superior to conventional parameters for determining endometrial receptivity for implantation.

Effects of growth hormone on follicle growth, oocyte maturation, and ovarian steroidogenesis

OBJECTIVES To assess the effects of GH on follicle growth, oocyte maturation, ovulation, and ovarian steroidogenesis. DESIGN In vitro perfused rabbit ovary. INTERVENTIONS The rabbit ovaries were perfused with medium alone, with GH at 1, 10, 100, or 200 ng/mL, or with 50 IU hCG for 12 hours. MAIN OUTCOME MEASURES The follicle diameter, the percent change in follicle diameter, the percentage of oocytes achieving germinal vesicle breakdown, and the production of P and E2 by the perfused rabbit ovaries. RESULTS The addition of GH to the perfusate increased the follicle diameter at 12 hours after perfusion in a dose-dependent manner. The percent change in follicle diameter in GH-treated ovaries did not differ significantly from that in hCG-treated ovaries at each time point of perfusion. However, ovulation did not occur in either the control ovaries or the experimental ovaries treated with GH. Exposure to GH at a concentration of > 10 ng/mL significantly stimulated the resumption of meiosis, as compared with the contralateral control ovaries. Although the concentration of P in the perfusate did not differ significantly between GH-treated and control ovaries, GH stimulated E2 production by the perfused rabbit ovaries in a dose-dependent manner. CONCLUSIONS Growth hormone acts on the rabbit ovary to stimulate follicle growth, oocyte maturation, and ovarian E2 production.

Complete removal of HIV-1 RNA and proviral DNA from semen by the swim-up method: Assisted reproduction technique using spermatozoa free from HIV-1

Background:Use of antiretroviral drugs has reduced the mortality rate for HIV infection and many HIV-discordant couples wish to have children. It is possible for an HIV-infected man to father children without risk of HIV transmission if HIV-free spermatozoa can be obtained from his semen. Methods:An improved swim-up method was used to collect HIV-free spermatozoa from the semen of HIV-positive males. Diluted semen was layered over a Percoll solution with a continuous density gradient of 30–98%, and then centrifuged. The bottom layer was collected by cutting the end from the tube and the sperm suspension was collected using the swim-up method. Spermatozoa were tested by nested polymerase chain reaction (PCR) for HIV-1 RNA and DNA, with a detection limit of one copy. Spermatozoa were used for assisted reproduction in 43 couples. Results:HIV-1 RNA and proviral DNA were not detected by nested-PCR assay in all 73 of the collected spermatozoa samples from 52 patients. The HIV-1-negative sperm was used for in vitro fertilization in 12 couples and for intracytoplasmic sperm injection in 31 couples. No detection of HIV-1 RNA or proviral DNA in the culture medium of the fertilized eggs was confirmed again before embryo transfer. Of the 43 female partners, 20 conceived and 27 babies were born. HIV antibodies, HIV RNA and proviral DNA were negative in all of the females and babies. Conclusions:HIV-negative spermatozoa could be obtained from semen of HIV-positive men. The method involves no risk of HIV transmission to female partners and their children.

Phosphorylated insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) inhibits while non-phosphorylated IGFBP-1 stimulates IGF-I-induced amino acid uptake by cultured trophoblast cells

Summary The effects of phosphorylated insulin-like growth factor-binding protein (plGFBP-1) and non-phosphorylated (nplGFBP-1) IGFBP-1 on amino acid uptake induced by IGF-I were studied using cultured trophoblast cells. Trophoblast cells obtained from term pregnancy were incubated with indicated concentrations of plGFBP-1 or nplGFBP-1 for 24 h and further incubated with 10 nM IGF-I for 3 h. Cells were then incubated with 3 H-α-amino isobutyric acid ( 3 H-AIB) for 30 min. Both plGFBP-1 and nplGFBP-1 alone had no effect on 3 H-AIB uptake; however, plGFBP-1 inhibited IGF-I-stimulated 3 H-AIB uptake with an ED 50 of 0.26 nM while nplGFBP-1 potentiated 3 H-AIB uptake with an ED 50 of 0.27 nM. Maternal IGF-I promotes fetal growth by stimulating nutrient transport in the placenta. As shown in this study, plGFBP-1 inhibits while nplGFBP-1 stimulates this IGF-I action in the placenta. Thus, it is suggested that IGFBP-1 phosphoisoforms are also involved in fetal growth by modulating IGF-I action in the placenta.

Plasma levels of insulin-like growth factor-I and its binding protein in polycystic ovary syndrome

Patients with polycystic ovary syndrome (PCOS) had significantly higher levels of total insulin-like growth factor (IGF-I) than those in age- and weight-matched controls (PCOS, 230 +/- 21 ng/ml; control, 180 +/- 16 ng/ml; mean +/- SE, p less than 0.05) as well as free IGF-I (PCOS, 3.8 +/- 0.2 ng/ml; control, 3.0 +/- 0.2 ng/ml; p less than 0.05). These elevated levels of IGF-I were correlated slightly with levels of LH and LH/FSH ratio (r = 0.171, p less than 0.05 and r = 0.239, p less than 0.01, respectively). Elevated fasting levels of insulin and decreased levels of IGF binding protein (32K-BP) were also observed in PCOS, and the levels of 32K-BP in PCOS were negatively correlated with insulin (r = -0.39, p less than 0.01). These results suggest that elevated IGF-I levels and decreased 32K-BP levels in the circulation are one of the endocrinological features of PCOS and that insulin is responsible for the clinical manifestation of decreased 32K-BP levels in PCOS.

Melatonin as a local regulator of human placental function

Abstract:  Melatonin plays a critical role in a variety of mammalian reproductive processes not only acting on the central nervous system but also behaving as a peripheral physiologic regulator. To address the relevance of melatonin to the maintenance of pregnancy at the feto‐maternal interface, we investigated the expression of two types of membrane melatonin receptors, MT1 and MT2, as well as arylalkylamine N‐acetyltransferase (AA‐NAT) and hydroxyindole‐O‐methyltransferase (HIOMT), the two enzymes required for the conversion of serotonin to melatonin, in the human placenta and the effect of melatonin on the release of human chorionic gonadotropin (hCG) from cultured human trophoblast cells. RT‐PCR analysis and DNA sequencing revealed that transcripts of MT1, MT2, AA‐NAT, and HIOMT were present in the first‐trimester human placenta. We also found that melatonin significantly potentiated hCG secretion at optimal concentrations. These results suggest that melatonin may regulate human placental function in a paracrine/autocrine manner, providing evidence for a novel role in human reproduction.

Induction of trophinin in human endometrial surface epithelia by CGβ and IL-1β

During embryo implantation, trophinin mediates cell adhesion by homophilic binding at the apical surfaces of trophectoderm and endometrium. Trophinin is expressed on the human endometrial epithelia in rare occasions. We developed hCG‐coated agarose beads that mimic the physical and physiological features of an implantation‐stage human blastocyst. When hCG‐coated beads were applied to human endometrial epithelial cells in the presence of IL‐1β, endometrial cells acquired strong trophinin expression and the ability for apical cell adhesion with trophinin‐expressing human trophoblastic cells. These results provide a mechanism for trophinin‐mediated adhesion of human blastocyst to endometrium by a spatially and temporally restricted paracrine effect of hCG derived from the blastocyst.

Physiological Role of Insulin-Like-Growth-Factor-Binding Protein-4 in Human Folliculogenesis

Insulin-like growth factor (IGF)-I and IGF-II, and their binding proteins (IGFBPs) have been demonstrated to play important roles in follicular development as intraovarian regulators. Previous studies have demonstrated that the follicular fluid of atretic follicles contains high levels of IGFBP-2 and IGFBP-4, which are known to inhibit the action of IGFs. In this study, we identified IGFBP-4 protease activity in the follicular fluid of developing but not atretic follicles. To elucidate the regulation mechanism of IGFBP-4 proteolytic activity in the ovary, cultured luteinized granulosa cells (GCs) were incubated with various hormones, and proteolyzed IGFBP-4 in the medium was analyzed. IGFBP-4 proteolytic activity was increased when GCs were incubated with IGFs, estradiol or follicle-stimulating hormone (FSH) but not with testosterone. We also showed that IGFBP-4 inhibited IGF-1-induced estradiol release by GCs while proteolyzed IGFBP-4 did not. These results suggest that human luteinized GCs produce IGFBP-4 protease, and that FSH and IGFs may stimulate folliculogenesis by modulating IGFBP-4 degradation in the ovary.

Effect of gonadal steroids on gonadotropinreleasing hormones stimulated human chorionic gonadotropin release by trophoblast cells

The effect of gonadal steroids on basal and GnRH-stimulated hCG release was studied using collagenase-dispersed trophoblast cells from early pregnancy. Both GnRH and a GnRH superagonist, Buserelin, stimulated hCG release with a similar dose dependency. Progesterone (0.1 to 10 micrograms/ml) inhibited GnRH-stimulated hCG release in a dose dependent manner as well as basal hCG release. Relatively high concentrations of estradiol (10 micrograms/ml) stimulated both basal and GnRH-mediated hCG release and antagonized the inhibitory effect of progesterone on hCG release at 1 micrograms/ml as well as RU486 (1 microgram/ml). These results indicate that progesterone has an important role in both basal and GnRH-mediated hCG regulatory system in the placenta.