Biomedical subjects

G E Hofmann

Publications and source records attributed to G E Hofmann.

At least 37 records · Page 2Linked to original sources

PubMed1995

Human intermediate trophoblasts express chorionic gonadotropin/luteinizing hormone receptor gene.

Human cyto- and synchtiotrophoblasts have recently been shown to contain functional hCG/LH receptors. The present study investigated whether human intermediate trophoblasts also contain these receptors. Six implantation sites from 4-8 wk of pregnancy were processed for in situ hybridization for hCG/LH receptors coupled with immunocytochemistry for human placental lactogen (hPL), an endocrine marker for intermediate trophoblasts. In addition, the sections were also double-immunostained for hCG/LH receptor and hPL proteins. The results showed that some but not all the intermediate trophoblasts contained hCG/LH receptors. The intermediate trophoblasts in endovascular locations contained more receptors than those in perivascular locations. Villus syncytiotrophoblasts contained the highest level of receptors, followed by intermediate trophoblasts in endovascular and perivascular locations and then villus cytotrophoblasts. These data, demonstrating the presence of hCG/LH receptors in intermediate trophoblasts, suggest a possible role for hCG in trophoblast invasion and maternal recognition of pregnancy.

Embryo Implantation↗

PubMed1995

Prognostic assessment of ovarian reserve.

OBJECTIVE: To review the literature regarding diminished ovarian reserve, the screening techniques that are currently available, and their appropriate application in clinical practice. DATA RESOURCES: Directed Medline searches. RESULTS: Ovarian reserve screening identifies women with greatly diminished chances of achieving pregnancy. The screening techniques include the clomiphene citrate challenge test, basal day 3 FSH measurements, and the GnRH agonist stimulation test. All have been evaluated in assisted reproduction programs and the predictive values of an abnormal test for failing to conceive is very high. When abnormal, these tests allow physicians to counsel patients that their prognosis for conception is poor. Although the presence of a normal result does indicate better long-term chances for conception, an age-related decline in fecundity remains and patient age should still be considered when counseling patients with normal screening results. Clinicians are urged to validate the threshold values with the assay system used in their own laboratory before the application of these tests. CONCLUSION: The literature consistently demonstrates the value of diminished ovarian reserve screening.

Adult↗

PubMed1994

Global arrest of translation during invertebrate quiescence.

Comparing the translational capacities of cell-free systems from aerobically developing embryos of the brine shrimp Artemia franciscana vs. quiescent embryos has revealed a global arrest of protein synthesis. Incorporation rates of [3H]leucine by lysates from 4-h anoxic embryos were 8% of those from aerobic (control) embryos, when assayed at the respective pH values measured for each treatment in vivo. Exposure of embryos to 4 h of aerobic acidosis (elevated CO2 in the presence of oxygen) suppressed protein synthesis to 3% of control values. These latter two experimental treatments promote developmental arrest of Artemia embryos and, concomitantly, cause acute declines in intracellular pH. When lysates from each treatment were assayed over a range of physiologically relevant pH values (pH 6.4-8.0), amino acid incorporation rates in lysates from quiescent embryos were consistently lower than values for the aerobic controls. Acute reversal of pH to alkaline values during the 6-min assays was not sufficient to return the incorporation rates of quiescent lysates to control values. Thus, a stable alteration in translational capacity of quiescent lysates is indicated. Addition of exogenous mRNA did not rescue the suppressed protein synthesis in quiescent lysates, which suggests that the acute blockage of amino acid incorporation is apparently not due to limitation in message. Thus, the results support a role for intracellular pH as an initial signaling event in translational control during quiescence yet, at the same time, indicate that a direct proton effect on the translational machinery is not the sole proximal agent for biosynthetic arrest in this primitive crustacean.

Animals↗

PubMed1994

Immunohistochemical localization of urokinase-type plasminogen activator and the plasminogen activator inhibitors 1 and 2 in early human implantation sites.

OBJECTIVE: Our purpose was to immunolocalize urokinase-type plasminogen activator and the plasminogen activator inhibitors 1 and 2 in human implantation sites, with emphasis on the types of trophoblast expressing the plasminogen activator and the inhibitors. STUDY DESIGN: Urokinase and the plasminogen activator inhibitors 1 and 2 were localized immunohistochemically in early human implantation sites in unruptured ectopic pregnancies from patients in an in vitro fertilization program. RESULTS: Urokinase kinase and the plasminogen activator inhibitors 1 and 2 were localized in the cytoplasm of cytotrophoblasts and in the cytoplasm and plasma membranes of intermediate and syncytiotrophoblast. Greater staining was noted in nonvillous, relative to villous, cytotrophoblasts for urokinase and both inhibitors. CONCLUSIONS: Urokinase-type plasminogen activator and the plasminogen activator inhibitors 1 and 2 were localized in all three forms of trophoblast at the maternal-fetal interface in early human implantation sites, particularly the differentiated and invasive forms of trophoblast. These results support a role for the plasminogen activator or inhibitors in the controlled invasion of the maternal decidua by the trophoblast during human implantation.

Embryo Implantation↗

PubMed1994

Age-related decline in female fertility is not due to diminished capacity of the uterus to sustain embryo implantation.

OBJECTIVE: To evaluate the contribution of the uterus to age-related reproductive failure in women. PATIENTS: Thirty-eight ovum donors (30.2 +/- 4.9 years [mean +/- SD]) donating oocytes throughout 102 ovum donations. Fifty-one cycles were documented in "younger" recipients (35.8 +/- 3.1 years) and 51 in "older" recipients (44.0 +/- 3.1 years). The study was prospectively designed; same-cohort oocytes obtained from one young donor during a specific cycle were evenly distributed between "young" and "old" ovum recipients. Use of oocytes from a single source and a unique ovulatory cohort provides strict control over oocyte quality. Uterine age is varied by design, according to the age of the recipient at the time of ET. The role of the aging uterus in the decline of female fertility can be thus isolated and scrutinized. RESULTS: No significant (NS) difference in the number of ova received (7.9 +/- 3.4 versus 7.0 +/- 3.5), ova fertilized (4.4 +/- 1.5 versus 4.5 +/- 2.3), or embryos transferred (4.1 +/- 1.5 versus 4.1 +/- 1.6) was observed between the < 40 and > or = 40 recipient age groups. A total of 23 pregnancies occurred among the 102 ETs (22.6%). Eleven clinical pregnancies (21.6%) resulting in 10 deliveries were observed in the < 40 recipient age group, and 12 clinical pregnancies (23.5%) leading to 10 deliveries occurred in the > or = 40 recipient age group (NS). The pregnancy loss rates were 9.1% (1 of 11) and 16.7% (2 of 12) for the two recipient age groups, respectively, (NS). CONCLUSION: The capacity to conceive and to gestate a conception to term when oocyte quality is controlled appears to be independent of uterine aging through the fifth decade of life.

Adult↗

PubMed1994

Comparison of leuprolide acetate and human chorionic gonadotropin for the induction of ovulation in clomiphene citrate-stimulated cycles.

OBJECTIVE: To examine the relative efficacies of leuprolide acetate (LA) and hCG in inducing ovulation and a normal luteal phase during clomiphene citrate (CC)-stimulated superovulation cycles. DESIGN: Prospective, randomized, blinded, and cross-controlled in consecutive cycles. SETTING: Large military tertiary care center. PATIENTS: Twenty-one ovulatory patients undergoing superovulation with CC and IUIs for the treatment of unexplained or male factor infertility. INTERVENTIONS: Clomiphene citrate (100 mg/d) on cycle days 5 through 9 in both of the study cycles. Administration of 2 mg SC LA in one cycle and 10,000 IU IM hCG in another cycle for induction of the midcycle surge. MAIN OUTCOME MEASURES: Serum LH, FSH, E2, and P levels every 12 hours for 36 hours after administration of either LA or hCG to characterize the midcycle hormonal dynamics. Luteal phase duration and serum P levels during the midluteal phase were used to estimate the adequacy of the luteal phase. Serial ultrasounds also were done to determine the incidence of luteinized unruptured follicle syndrome. RESULTS: Serum FSH levels in the periovulatory interval were significantly higher after the administration of LA. There were no differences in the periovulatory E2 or P levels or the incidence of sonographic evidence of ovulation after administration of either LA or hCG. Although midluteal serum P levels were higher in the cycles in which hCG was administered, all 42 treatment cycles had adequate luteal phases as assessed by luteal phase duration and three midluteal P levels. Ongoing pregnancies occurred after both LA- and hCG-stimulated cycles. CONCLUSION: Leuprolide acetate and hCG were equivalent in their abilities to induce ovulation. Further evaluation of the adequacy of the luteal phase and the ensuing pregnancy rates after LA induction of an endogenous gonadotropin surge are indicated.

Adult↗

PubMed1994

Immunohistochemical localization of transforming growth factor-beta in human implantation sites.

Transforming growth factor-beta (TGF beta), a protein known to antagonize many of the functions of the epidermal growth factor-receptor system, was localized immunohistochemically in unruptured ectopic pregnancies (EP) removed by salpingectomy (n = 8), uterine decidua from EP (n = 4), and decidua and trophoblast from electively terminated first trimester pregnancies (ETP; n = 8). Two rabbit polyclonal antisera that recognize both TGF beta 1 and beta 2 were used. Immunostaining for TGF beta was identified in all three forms of trophoblast, cytotrophoblasts, intermediate trophoblasts, and syncytiotrophoblasts, which were differentiated histologically and immunohistochemically. Moderate cytoplasmic immunostaining was found in villous cytotrophoblasts in both EP and ETP. Nonvillous (anchoring) cytotrophoblasts in these same tissues demonstrated moderate immunostaining adjacent to the villous and light immunostaining distal to the villous. In intermediate trophoblasts, moderate to intense immunostaining was seen in EP and ETP. Syncytiotrophoblasts demonstrated moderate cytoplasmic immunostaining in EP and ETP as well as moderate to intense staining of plasma membranes and microvilli. Nuclear staining was not evident in any form of trophoblast. TGF beta immunostaining was demonstrated in both glands and stroma of decidua from both EP and ETP; however, staining was more intense in decidua from ETP. With the known presence of TGF beta receptors and mRNA in placenta, these results suggest an autocrine/paracrine role for TGF beta regulation of endometrial-trophoblast function during human implantation.

Decidua↗

PubMed1993

Evaluation of the significance of the estradiol response during the clomiphene citrate challenge test.

OBJECTIVE: To evaluate the relationship between the E2 response during the clomiphene citrate (CC) challenge test and ovarian responsiveness to exogenous gonadotropins. DESIGN: Performance of a CC challenge test followed by ovulation induction with exogenous gonadotropins as part of participation in an assisted reproduction program. SETTING: Assisted reproduction program in a large military tertiary care center. PATIENTS: Two hundred forty-seven women between the ages of 24 and 39 years with normal CC challenge tests within 1 year of their assisted reproduction cycle. INTERVENTIONS: Performance of CC challenge tests and ovulation induction with exogenous gonadotropins as a component of an assisted reproduction cycle. MAIN OUTCOME MEASURES: Correlation of the E2 response during the CC challenge test and peak E2, the duration of stimulation, number of ampules of exogenous gonadotropins, number of mature follicles, number of mature oocytes recovered, and fertilization and pregnancy rates in an assisted reproduction program. RESULTS: No correlation exists between the E2 response during the CC challenge test and any of the parameters evaluated. CONCLUSION: Monitoring of the E2 response during the CC challenge test did not predict ovarian responsiveness or pregnancy rates in patients participating in an assisted reproduction program and one may choose not to include it in routine testing.

Adult↗

PubMed1993

The duration of leuprolide acetate administration prior to ovulation induction does not impact ovarian responsiveness to exogenous gonadotropins.

OBJECTIVE: To evaluate the possible impact that the duration of GnRH agonist (GnRH-a) suppression has on subsequent ovarian responsiveness to exogenous gonadotropins. DESIGN: Prospective evaluation of the relationship between the duration of GnRH-a and multiple parameters of ovarian responsiveness. SETTING: Assisted reproduction program in a large military tertiary care center. PATIENTS: One hundred sixty-five women being pretreated with leuprolide acetate (LA) before ovulation induction with exogenous gonadotropins. INTERVENTIONS: Variable duration of LA administration before stimulation. MAIN OUTCOME MEASURES: Outcome measures include duration of stimulation, days until doubling of basal E2, number of ampules of exogenous gonadotropins, peak E2, number of mature follicles, and number of mature oocytes. RESULTS: The duration of LA pretreatment had no effect on any of the parameters of ovarian responsiveness analyzed. CONCLUSION: Once complete suppression of gonadal function is attained, the duration of GnRH-a suppression has no impact on subsequent ovarian responsiveness to exogenous gonadotropins.

Adult↗

PubMed1993

Premature luteinization in controlled ovarian hyperstimulation has no adverse effect on oocyte and embryo quality.

OBJECTIVE: To determine if premature luteinization has an adverse effect on oocyte and, hence, embryo quality. DESIGN: Retrospective evaluation of anonymous ovum donors/oocyte recipients. SETTING: A large oocyte donation program. PATIENTS, PARTICIPANTS: Sixty-eight women undergoing controlled ovarian hyperstimulation (COH) as ovum donors were matched to 68 women with ovarian failure as ovum recipients who had endometrial maturation exogenously controlled by an identical hormone replacement protocol. INTERVENTIONS: Serum was collected for E2 and P in donors and recipients. MAIN OUTCOME MEASURES: The incidence of premature luteinization was determined in donors. Cycle characteristics were compared between donors with and without premature luteinization, with emphasis on oocyte and embryo quality. Implantation rates per embryo and delivery rates per transfer were measured in recipients. RESULTS: Twenty-one (31%) of the donors demonstrated premature luteinization. Serum P was higher on day before hCG, day of hCG, and day after hCG in women demonstrating premature luteinization. However, there were no differences between donor cycles with or without premature luteinization as determined by donor age, ampules of gonadotropins used, day of hCG administration, peak E2, total number of oocytes, and number of mature oocytes retrieved. Ovum recipients were of similar age and had similar E2 exposure (area under the E2 curve) before P administration. Similar fertilization rates, incidence of polyspermia, number of embryos transferred of similar embryo grade, and similar implantation rates and deliveries per transfer were observed in women receiving oocytes from donors with and without premature luteinization, respectively. CONCLUSIONS: Similar oocyte quality, fertilization, and polyspermia rates, embryo quality, implantation, and delivery rates suggest that any negative impact of premature luteinization on pregnancy rates in COH cycles from young women is not due to an adverse effect of PL on oocyte and hence embryo quality, but rather on the endometrial environment.

Chorionic Gonadotropin↗

PubMed1993

Premature luteinization is not eliminated by pituitary desensitization with leuprolide acetate in women undergoing gonadotrophin stimulation who demonstrated premature luteinization in a prior gonadotrophin-only cycle.

A total of 40 women who demonstrated premature luteinization (serum progesterone > or = 3.5 nmol/l (1.1 ng/ml) on or before the day of human chorionic gonadotrophin (HCG) administration) during ovarian stimulation with human menopausal gonadotrophins (HMG) were restimulated in 46 subsequent cycles after pituitary desensitization with the gonadotrophin-releasing hormone agonist (GnRHa, 1 mg), leuprolide acetate. Five women were treated with a double dose of agonist (2 mg) when premature luteinization was determined on the single dose protocol. In HMG-only cycles, a frank luteinizing hormone (LH) surge was detected in 30 cycles; 15 cycles were cancelled because of premature ovulation. In agonist cycles there were no cancellations, although 25 cycles demonstrated premature luteinization and in six cycles a frank LH surge was detected. Doubling the dose of the agonist did not prevent premature luteinization. Agonist cycles with and without premature luteinization did not differ in any in-vitro fertilization (IVF) outcome parameters (ampoules of gonadotrophins, day of HCG administration, peak oestradiol concentration, number of oocytes retrieved, fertilized, transferred or cryopreserved). We conclude that in patients who demonstrate premature luteinization in a gonadotrophin-only cycle, pituitary desensitization may not completely eliminate subtle luteinization or a frank LH surge.

Chorionic Gonadotropin↗

PubMed1993

Extension of enzyme half-life during quiescence in Artemia embryos.

Encysted gastrulae of Artemia franciscana are known to enter a reversible state of quiescence in which biosynthetic and catabolic pathways are markedly suppressed. Given that these embryos can survive months of anoxia, we investigated their ability to extend the half-life of cytochrome-c oxidase (COX), a key metabolic enzyme, during anoxia. We calculate that the half-life of COX is extended to 101 days under anoxia, an estimated 77-fold increase compared with aerobic values. During conditions of aerobic acidosis, the half-life of COX was extended sevenfold to a value of 9.7 days. We propose that the extended lifetimes of COX in both cases may be due to suppressed mitochondrial proteolysis under depressed pH. The shorter enzyme half-life observed under the latter condition may be due to the availability of ATP for degradative processes during aerobic acidosis. We also suggest that the presence of oxygen in aerobic acidosis may lead to increased rates of protein damage due to autooxidation.

Acidosis↗

PubMed1993

Transforming growth factor-alpha in human implantation trophoblast: immunohistochemical evidence for autocrine/paracrine function.

Epidermal growth factor (EGF) and its receptor (EGF-R) have been demonstrated in human implantation sites. Transforming growth factor-alpha (TGF-alpha), a protein with extensive sequence homology to EGF and with equal affinity for the EGF-R, was localized immunohistochemically in early intrauterine and ectopic pregnancies. Within the same experiments, TGF-alpha immunostaining was more intense in ectopic than intrauterine pregnancies. In both groups, TGF-alpha immunostaining was moderate to intense in the syncytiotrophoblast (ST), light to moderate in the cytotrophoblast (CT), and moderate to intense in intermediate trophoblast (IT). In ST, TGF-alpha immunostaining localized to the cytoplasm and plasma membranes, including microvilli. No nuclear associated TGF-alpha was noted in ST. In CT, differential TGF-alpha immunostaining was noted between the villous and nonvillous CT. Villous CT demonstrated light to absent cytoplasmic TGF-alpha immunostaining with intense nuclear staining. In contrast, nonvillous CT revealed moderate to intense cytoplasmic staining without demonstrable nuclear staining. These results demonstrate the presence of immunoreactive TGF-alpha in all forms of trophoblast. The known presence of the EGF-R suggests an autocrine/paracrine role for TGF-alpha during human implantation.

Embryo Implantation↗

PubMed1993

Immunohistochemical localization of transforming growth factor-alpha in human endometrium, decidua, and trophoblast.

Transforming growth factor-alpha (TGF-alpha) was localized immunohistochemically in human proliferative and secretory endometrium, decidua, and trophoblast from first, second, and third trimester pregnancies. In proliferative endometrium, TGF-alpha immunostaining was moderate to intense and localized predominantly to stromal cells, whereas glandular staining was absent to light. After ovulation, TGF-alpha staining was light within the stroma, but moderate to intense around spiral arterioles. Moderate to intense staining was also detected in glandular and surface epithelium in secretory endometrium, with no staining noted in subnuclear vacuoles. In hypersecretory endometrium, staining was predominantly epithelial. In decidua, TGF-alpha was detected in intermediate trophoblast and on the surface epithelium. In first trimester trophoblast, TGF-alpha was detected in both cytotrophoblast (CT) and syncytiotrophoblast. Cytoplasmic staining was light in CT and moderate to intense in ST, with particular staining of plasma membranes. Intense TGF-alpha staining of nuclear membranes in CT was noted. TGF-alpha staining was light to absent in second and absent in third trimester trophoblast. This study demonstrates immunoreactive TGF-alpha in tissues known to be responsive to epidermal growth factor, and also demonstrates the presence of immunoreactive TGF-alpha associated with nuclear membranes. Thus, TGF-alpha may play an autocrine/paracrine role in endometrial development and trophoblast function.

Decidua↗

PubMed1993

Amniotic fluid epidermal growth factor concentrations. The effect of intra-amniotic thyroxine for acceleration of fetal maturation.

Intra-amniotic thyroxine (200-500 ug) was administered weekly to 29 women in the third trimester to enhance fetal maturation. Lecithin-sphingomyelin ratio (L/S) and epidermal growth factor (EGF) were measured in amniotic fluid (AF) before (n = 58) and after (n = 92) administration of thyroxine. The AF L/S ratio and EGF concentration increased linearly with increasing gestational age both before (r = 0.76, p < 0.0001; r = 0.41, p < 0.001, respectively) and after (r = 0.62, p < 0.0001; r = 0.43, p < 0.001 respectively) initiation of thyroxine treatment. The slopes of gestational age vs L/S (0.07) and EGF (0.004) before T4 increased significantly after initiation of T4 therapy (L/S:0.23, p < 0.001; EGF:0.015, p < 0.01, respectively). L/S ratios correlated with AF EGF levels before (r = 0.77, p < 0.001) and after (r = 0.63, p < 0.001) initiation of T4 therapy. These results demonstrate that intra-amniotic thyroxine accelerates not only the progression of the amniotic fluid L/S ratio, but the appearance of EGF.

Adult↗

PubMed1993

A prospective evaluation of clomiphene citrate challenge test screening of the general infertility population.

OBJECTIVE: To assess the results of screening an unselected general infertility population for diminished ovarian reserve with the clomiphene citrate challenge test. METHODS: Two hundred thirty-six couples were followed prospectively and studied for the relationship between clomiphene citrate challenge test screening and final diagnoses and long-term fertility rates. RESULTS: Abnormal clomiphene citrate challenge tests were found in two of 61 (3%) of the patients younger than 30 years, in five of 72 (7%) aged 30-34, in seven of 68 (10%) aged 35-39, and in nine of 35 (26%) aged 40 or older. An abnormal test predicted lower pregnancy rates; conception occurred in 92 of 213 (43%) of patients with normal results, but only two of 23 (9%) of patients with abnormal results (P < .004). Unexplained infertility (not considering the clomiphene citrate challenge test) was a common finding in patients with abnormal clomiphene citrate challenge test results (12 of 23). This incidence was significantly higher than that in patients with normal clomiphene citrate challenge test results (20 of 213) (P < .001). CONCLUSIONS: Approximately 10% of the patients in the general infertility population had abnormal clomiphene citrate challenge tests. The incidence of abnormal results increases with age beginning in the early 30s, occurs with a higher frequency in patients who would otherwise be diagnosed with unexplained infertility, and prognosticates decreased long-term pregnancy rates.

Adult↗

PubMed1992

Epidermal growth factor and its receptor in human implantation trophoblast: immunohistochemical evidence for autocrine/paracrine function.

Epidermal growth factor (EGF) and its receptor (EGF-R) were immunohistochemically localized in trophoblast during human implantation from intrauterine and ectopic pregnancies. EGF immunostaining was absent to light in the cytotrophoblast (CT), light to moderate in intermediate trophoblast (IT), and intense in the syncytiotrophoblast (ST). In ST, EGF immunostaining was found mostly in the cytoplasm; however, staining of the plasma membrane was also noted. Immunostaining for the EGF-R was absent to light in the CT and moderate to intense in the IT. Immunostaining for the EGF-R was intense in the ST, with moderate staining in the cytoplasm and intense staining in the plasma membrane. Staining was most intense on the microvilli of the ST. Additionally, EGF-R immunostaining could be demonstrated on nuclear membranes. The increase in the intensity of the immunostaining for both EGF and EGF-R noted in CT, IT, and ST suggests a differentiated expression of this receptor-ligand system in human trophoblast and provides evidence for an autocrine/paracrine role for EGF in trophoblast function. The presence of this receptor-ligand system during early human implantation strongly supports a role for EGF and the EGF-R in embryo-uterine signalling and the implantation process.

Embryo Implantation↗

PubMed1992

Comparison of messenger RNA pools in active and dormant Artemia franciscana embryos: evidence for translational control.

In response to environmental anoxia, embryos of the brine shrimp Artemia franciscana enter a dormant state during which energy metabolism and development are arrested. The intracellular acidification that correlates with this transition into anaerobic dormancy has been linked to the inhibition of protein synthesis in quiescent embryos. In this study, we have addressed the level of control at which a mechanism mediated by intracellular pH might operate to arrest protein synthesis. Two independent lines of evidence suggest that there is an element of translational control when protein synthesis is arrested in dormant embryos. First, as determined by in vitro translation techniques, there were no significant quantitative differences in mRNA pools in dormant as compared to actively developing embryos. In addition, fluorography of the translation products showed that there are no large qualitative changes in mRNA species when embryos become dormant. These data suggest that there was no net degradation of mRNA pools in dormant embryos and that protein synthesis may therefore be controlled more strongly at translation than at transcription. Second, polysome profile studies showed that dormant embryos possess reduced levels of polysomes relative to those found in cells or active embryos. The disaggregation of polysomes is an indication that the initiation step in protein synthesis is disrupted and is further evidence that the mechanism involved in protein synthesis arrest in dormant Artemia involves translational control.

Animals↗