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Biomedical subjects

J W Ramey

Publications and source records attributed to J W Ramey.

12 recordsLinked to original sources
PubMed1998

Transforming growth factor beta receptor expression in hyperstimulated human granulosa cells and cleavage potential of the zygotes.

A possible relationship between transforming growth factor beta receptor type I (TbetaRI) and type II (TbetaRII) protein expression in human granulosa cells and the quality of preimplantation embryo development in vitro was studied using immunoblot analysis of TbetaRI and TbetaRII in hyperstimulated granulosa cells and morphological assessment of the cleavage potential of the zygotes in vitro. Washed granulosa cells were collected from </= 35-yr-old women with either tubal defects or mild endometriosis who were undergoing controlled ovarian hyperstimulation prior to oocyte retrieval for in vitro fertilization. TbetaRI and TbetaRII were immunoprecipitated from 100 000 g soluble and crude membrane fractions using receptor-specific antibodies and analyzed by Western immunoblotting, and the relative expression was quantitated from the luminographs. The gross morphology (embryo grade) of the preimplantation embryos developed in vitro was determined using a stereomicroscope. Both TbetaRI and TbetaRII are expressed in the soluble and membrane fractions of granulosa cells. Most notably, the zygote always developed into a grade 1 quality preimplantation embryo when the oocyte originated from a follicle that expressed a low amount of TbetaR protein in the granulosa cell membrane. Reduced expression of TbetaR in the granulosa cell membrane may form a mechanism critically regulating TGFbeta action on granulosa cells, and the latter in turn precisely control oocyte development, hence, the subsequent cleavage potential.

Blastomeres↗
PubMed1997

Transfer of cryopreserved-thawed pre-embryos in a cycle using exogenous steroids without prior gonadotrophin-releasing hormone agonist suppression yields favourable pregnancy results.

We have analysed the use of a programmed cycle of administration of exogenous steroids without prior suppression with a gonadotrophin-releasing hormone agonist (GnRHa) for the transfer of cryopreserved-thawed pre-embryos. From July 1992 to June 1994, 199 cycles (162 patients) were studied. Pre-embryos had been previously cryopreserved at the pronuclear stage using 1.5 M 1,2-propanediol as a cryoprotectant. Preparation of the endometrium was achieved in a step-up regime with transdermal oestradiol patches (0.1 to 0.4 mg). Progesterone in oil (50 mg i.m.) was started on cycle day 13. Pre-embryos were thawed on day 14 and transferred on day 15 after evidence of survival and cleavage. The mean (+/- SD) age of patients undergoing transfer was 35.4 +/- 4.3 years. The mean number of pre-embryos thawed was 4.7 +/- 1.8 with a mean of 3.3 +/- 1.4 pre-embryos being transferred. Eight of the cycles demonstrated follicular development >16 mm prior to thaw and transfer; however, these patients did not demonstrate a luteinizing hormone surge. Mean endometrial thickness on day 13 was 10.8 +/- 2.1 mm. Overall pregnancy rate was 29.2% (57/195). The ongoing or delivery rate was 16.1% (32/195). The rate of preclinical losses per transfer was 6.2% (12/195). Overall, the implantation rate was 6.2% (47/757). Thus, the use of a programmed cycle for cryopreserved embryo transfer yields favourable pregnancy outcome and offers practical advantages to patients. Prior suppression with a GnRHa is not necessary for endometrial preparation.

Adult↗
PubMed1996

Superior analytic characteristics of an immunometric assay for gonadotropins also provides useful clinical prediction of in vitro fertilization outcomes.

OBJECTIVE: To determine whether an analytically superior gonadotropin assay, the monoclonal, two-site immunometric assay, also provided superior prediction of clinical outcomes when compared with conventional RIA methodology. DESIGN: Methods comparison study. SETTING: Tertiary academic center. PATIENTS: One hundred fifty-seven consecutive IVF patients. INTERVENTION: Comparisons of FSH and LH levels on cycle day 3 were made using paired RIA and immunometric assay procedures. The ability of day 3 LH, FSH, and their ratio in predicting IVF performance was determined using regression analyses. RESULTS: The predictive ability of FSH as assayed by immunometric assay at least equaled that obtained by RIA for both peak E2 levels and the number of mature oocytes retrieved. CONCLUSION: Results from this study indicate that gonadotropin levels as measured by immunometric assay represent an effective clinical tool in predicting IVF outcomes that may prove superior to RIA.

Estradiol↗
PubMed1996

Inability to establish ectopic endometrium in a natural killer cell-deficient murine model. Immunologic, histologic and histochemical assessment.

OBJECTIVE: To investigate what effect natural killer (NK) cells have on the implantation of heterologous endometrial scrapings. STUDY DESIGN: Anti-asialo GM1 (AA-GM1) anti-sera have been shown to eliminate NK cell activity in various strains of rats and mice. Either AA-GM1 antibodies (+) or rabbit antiglobulin (-) was administered to beige mice (NK cell deficient) or beige control mice (not NK cell deficient of the same strain). The heterologous endometrial scrapings were prepared by scraping seven pairs of uterine horns from normal mice of the same strain. Beige and normal mice were then injected intraperitoneally every 3 days with the heterologous endometrial scraping and antibodies for a period of 50 days. The four experimental groups (n = 10 per group) can be summarized as being beige (+), beige (-), normal (+) and normal (-). RESULTS: There was no evidence of ectopic endometrial tissue in any of the four test groups by histologic examination or by using immunohistochemical staining techniques. Histologic evidence of an impaired immune response was clearly demonstrated in the beige mice receiving AA-GM1 antibodies. CONCLUSION: Using this model, a deficiency of NK cell activity did not appear to enhance the implantation of endometrial tissue on the abdominal peritoneum of mice.

Animals↗
PubMed1994

The influence of pentoxifylline (Trental) on the antifertility effect of intrauterine devices in rats.

OBJECTIVE: To test the hypothesis that the inflammatory response stimulated by intrauterine devices (IUDs) plays a role in the antifertility action of IUDs. We treated rats with pentoxifylline (Trental; Hoechst-Roussel Pharmaceuticals, Inc., Somerville, NJ) and evaluated its effect on the anti-implantation action of IUDs. The number of embryos in treated compared with untreated rats was determined. DESIGN: Breeder female Sprague-Dawley rats (Harlan Sprague Dawley, Indianapolis, IN) were randomized into one of five test groups (n = 20 per group). A monofilament nylon IUD was inserted transcervically into one horn of the bicornuate uterus in two groups. The IUD-bearing groups received either intraperitoneal (IP) injections of pentoxifylline (45 mg/kg per every 12 hours) or normal saline (NS). The two non-IUD-bearing groups received IP injections of pentoxifylline or NS. The non-IUD group was not injected. All injections were administered daily for 21 days and the animals then mated. Successful mating was determined by the presence of spermatozoa in vaginal washings. The injections of pentoxifylline or NS were continued until day 12 of pregnancy when the rats were killed. The total number of embryos in each uterine horn was determined. SETTING: University research laboratory. RESULTS: Embryo numbers (1.0 +/- 0.6 [mean +/- SEM]) were reduced in the IUD horn compared with the contralateral non-IUD horn (6.4 +/- 1.0) and with the uterine horns from each of the four other test groups. The number of embryos were increased in the IUD horn (3.5 +/- 0.9) of the pentoxifylline-treated rats. CONCLUSION: Pentoxifylline appeared to reduce the contraceptive effectiveness of the IUDs in this model.

Animals↗
PubMed1993

Peritoneal fluid: its relevance to the development of endometriosis.

OBJECTIVE: To review and evaluate published studies that have examined the role of peritoneal fluid (PF) in the development of endometriosis. DESIGN: Important studies related to this topic have been identified through a computerized bibliographical search (MEDLINE), as well as by manually scanning the published literature of major reproductive journals over the last several years. MAIN OUTCOME MEASURES: Studies that examined the effect of PF or its components on the pathophysiology of endometriosis are discussed. These include reported effects on the histogenesis, maintenance and proliferation of endometriosis, as well as related actions on infertility. RESULTS: The majority of investigations into the role PF plays in the pathogenesis of endometriosis have evaluated how it may adversely affect fertility. Suggestive but inconclusive data in the literature indicate that degenerating endometrial tissue may release a biochemical factor(s) into the peritoneal environment that is capable of inducing ectopic endometrium formation. Peritoneal fluid itself contains growth factor that may play a role in the implantation and maintenance of the ectopic endometrium. CONCLUSIONS: The PF of women with endometriosis has been shown to contain angiogenic as well as other growth factors. These compounds may contribute to the proliferation of the ectopic endometrium.

Ascitic Fluid↗
PubMed1987

The effects of gonadotropin-releasing hormone and estradiol on luteinizing hormone biosynthesis in cultured rat anterior pituitary cells.

This study investigated the effects of physiological concentrations of GnRH and estradiol (E2) on LH biosynthesis and release using cultured anterior pituitary cells. Pituitaries from female rats were enzymatically dispersed and cultured for 48 h in steroid-free alpha-Modified Eagle's Medium, followed by a 24-h culture in medium with or without E2. The cells were then incubated for a 4-h (Exp 1 and 2) or 8-h (Exp 3) period in medium containing radiolabeled precursors with or without GnRH. Radioactive precursor incorporation into LH was determined by immunoprecipitation, while immunoreactive LH (iLH) content was quantified by RIA. In the first experiment, all concentrations of E2 (10(-11)-10(-8) M) enhanced iLH release in response to 1 nM GnRH, confirming previous reports. GnRH increased [3H]glucosamine (3H-Gln) incorporation into LH, but had no effect on [35S]methionine (35S-Met) incorporation. The higher concentrations of E2 enhanced GnRH-stimulated 3H-Gln LH production. In the second experiment, the effects of GnRH (10(-9) M) and E2 (5 X 10(-10) M) on the incorporation of [3H]galactose, [3H]mannose, [3H]fucose, or [35S]sulfate into LH were investigated. Although all precursors were incorporated into LH, no specific effect of GnRH and/or E2 on incorporation of any of the precursors into LH was noted. In Exp 3, pituitary cells were cultured with or without 0.5 nM E2 followed by an 8-h incubation with varying physiological concentrations of GnRH (10(-11)-10(-9) M) and radiolabeled precursors (3H-Gln and 35S-Met). GnRH stimulated iLH release in a dose-dependent manner, and this response was enhanced by E2. GnRH also increased the incorporation of both 3H-Gln and 35S-Met into LH, but the dose of GnRH required for this response was dependent upon the estrogen environment. In the absence of E2, only 10(-9) M GnRH increased 3H-Gln LH and 35S-Met LH production, whereas in cells exposed to E2, all concentrations of GnRH (10(-11)-10(-9) M) increased 3H-Gln LH and 35S-Met LH production. In all experiments, the specific activity of radiolabeled LH released under basal conditions was greatly reduced by stimulation with GnRH. These results suggest that GnRH regulates both LH glycosylation and LH polypeptide synthesis and that E2 lowers the physiological concentration of GnRH necessary to stimulate this biosynthetic response. Moreover, estrogen's enhancement of GnRH-stimulated LH release appears to be due to its action on mechanisms regulating the release of previously synthesized stored hormone as well as the release of newly synthesized LH.

Animals↗
PubMed1987

Effects of a low calcium environment on luteinizing hormone biosynthesis in cultured rat anterior pituitary cells.

The purpose of this study was to investigate the effects of lowering the extracellular calcium concentration on GnRH-stimulated LH glycosylation and LH translation, as measured by the incorporation of [3H]glucosamine (3H-Gln) and [35S]methionine (35S-Met) into immunoprecipitable LH. Cultured anterior pituitary cells, previously exposed to estradiol (5 X 10(-10) M) to maximize precursor incorporation were incubated for 4 h in normal calcium (2.5 mM) or low calcium medium (less than 15 microM) containing radiolabeled precursors with or without 1 nM GnRH. In the presence of normal calcium, GnRH significantly increased 3H-Gln-labeled LH in the medium (278%) and cells (290%), as well as total (cells plus medium) 3H- Gln LH (280%) compared to the control value (no GnRH). GnRH also significantly increased the 35S-Met LH released into the medium (164%) and total 35S-Met LH (186%) over control values. Depletion of extracellular calcium completely inhibited GnRH-stimulated 3H-Gln LH and 35S-Met LH production. Total immunoreactive LH (iLH), as measured by RIA, was also increased significantly by GnRH treatment in the presence of calcium, but this response was prevented by removal of calcium from the medium. Lowering extracellular calcium had no effect on cellular uptake or incorporation of 3H-Gln or 35S-Met into total trichloroacetic acid-precipitable protein. Approximately 80% of newly synthesized LH was released into the medium in all treatment groups independent of whether calcium or GnRH was present. The specific activity (disintegrations per min/microgram iLH) of radiolabeled LH released into the medium was significantly reduced by treatment with GnRH due to the large amount of unlabeled iLH released into the medium. However, when the cells were incubated in low calcium, the SA of 3H-Gln LH and 35S-Met LH in the medium was unaltered by GnRH, whereas GnRH-stimulated iLH release was inhibited. We conclude that GnRH stimulation of LH glycosylation and LH apoprotein synthesis involves extracellular calcium-dependent events, and the release of newly synthesized LH is closely coupled to LH biosynthesis and is less dependent on extracellular calcium, whereas the GnRH-stimulated release of previously synthesized, stored LH is dependent on extracellular calcium.

Animals↗
PubMed1986

An in vitro study of LH release, synthesis and heterogeneity in pituitaries from proestrous and short-term ovariectomized rats.

It is known that acute ovariectomy (OVX) greatly attenuates the pituitary luteinizing hormone (LH) response to gonadotropin-releasing hormone (GnRH) in vitro. The present study evaluated possible quantitative and/or qualitative differences in the biosynthesis and secretion of LH in pituitaries from proestrous and acutely (72 h) OVX rats. Paired anterior pituitary glands were incubated for 4 h in a medium containing +/- 10 nM GnRH. Pituitary and secreted LH were measured by radioimmunoassay with differences in total LH (tissue plus medium) +/- GnRH being indicative of GnRH-stimulated LH synthesis. Qualitative changes in LH were evaluated by isoelectrofocusing (IEF). The results show that the major form of LH stored in and released from the pituitaries consisted of LH molecules with an isoelectric point (pI) in the alkaline pH range (alkaline LH), and a lesser amount (approximately 30%) of LH molecules in the acidic pH range (acidic LH). The ratio of alkaline/acidic LH observed in the pituitary and medium was similar in the proestrous and OVX groups, although the amount of alkaline and acidic LH release in response to GnRH was 2-3 times greater in the proestrous group. In both groups, the alkaline/acidic LH ratio of secreted LH was higher in the presence of GnRH than in its absence. Alkaline LH synthesis was increased by GnRH in both groups, with the response being greater in the proestrous than in the OVX group; GnRH-stimulated acidic LH synthesis was observed only in the proestrous group. In both groups, the amount of LH synthesized was about 60% of the amount released, which suggests that LH synthesis does not fully account for differences in GnRH-stimulated LH release. Treatment of pituitary extracts with neuraminidase decreased acidic LH, and proportionately increased alkaline LH. These results suggest that the quality of LH stored in and secreted from pituitaries of proestrous and OVX rats is similar, and that there is a preferential release of the major alkaline LH isoform in response to GnRH. The ovarian steroid environment, presumably estradiol, proportionately increases the amount of alkaline and acidic LH released, and differentially affects the amounts of the various isoforms synthesized in response to GnRH. The charge heterogeneity of alkaline and acidic LH may be related to the sialic acid content of the LH molecule.

Animals↗
PubMed1983

Characterization of the luteinizing hormone response to continuous infusions of gonadotropin releasing hormone using perifused pituitaries from intact, ovariectomized and steroid-treated rats.

Anterior pituitary glands obtained from rats at various stages of the estrous cycle and from short-term ovariectomized (OVX) rats with or without physiological replacement of estradiol-17 beta (E2) and/or progesterone (P), were perifused in vitro with continuous infusions (4 h) of gonadotropin releasing hormone (GnRH) (12 ng/h). In all treatment groups the in vitro pattern of luteinizing hormone (LH) release in response to GnRH was characterized by an initial low rate of LH release (initial phase; 20-70 min) followed by a significant augmented rate of secretion during the late phase (120-240 min) with the exception of the estrous and OVX + P groups in which LH was released at a constant rate. The total amount of LH released in response to GnRH was similar for glands removed on estrus, diestrus-I (D-I) and D-II, but increased significantly for glands removed on 0900 h proestrus with a further increase at 1400 h proestrus. Ovariectomy reduced the total LH released in vitro by 50-60% and 85-90% compared with estrous, D-I, D-II and proestrous groups, respectively. In vivo treatment of OVX rats with E2 restored the in vitro LH response to levels comparable to those in the 0900 h proestrous group while treatment with P + E2 further increased the rate of LH release in the initial phase to levels similar to those observed in the 1400 h proestrous group. In all treatment groups, addition of 5 microM cycloheximide to the perifusion media significantly inhibited GnRH-stimulated LH release during the late phase without significantly altering the initial LH response except in the OVX + E2P group in which it was partially inhibited. These results demonstrate that perifused pituitaries maintain their characteristic responsiveness to GnRH in vitro. Furthermore, they indicate that LH secretion in response to continual GnRH stimulation involves protein synthesis-independent and -dependent components. E2, in vivo, enhances the magnitude of both components in response to GnRH in vitro, while E2 + P may further enhance the initial in vitro response to GnRH through a protein synthesis-dependent mechanism.

Animals↗