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Biomedical subjects

S Oehninger

Publications and source records attributed to S Oehninger.

At least 91 records · Page 5Linked to original sources
PubMed1996

A comparative analysis of embryo implantation potential in patients with severe teratozoospermia undergoing in-vitro fertilization with a high insemination concentration or intracytoplasmic sperm injection.

The objective of this study was to assess fertilization, implantation and pregnancy rates in infertile patients with severe teratozoospermia [P (poor prognosis) pattern sperm morphology assessed by strict criteria] treated by in-vitro fertilization (IVF) using a high insemination concentration (HIC), or by intracytoplasmic sperm injection (ICSI). This was a retrospective cohort study performed in an academic tertiary institution. The outcome of 115 consecutive ICSI cycles was compared to that of a similar number of cycles of IVF with HIC performed during a similar time frame and matched by woman's age and basal serum (cycle day 3) follicle stimulating hormone concentrations. The inclusion criteria were sperm morphology </=4% normal forms (P pattern) and >/=1x10(6) total motile spermatozoa per ejaculate. The diploid fertilization rate in the HIC-IVF group was 86% and in the ICSI group 68% (P < 0.05). Importantly, an equal number of embryos was transferred to both groups of patients. The morphological quality of the embryos (proportion of transfers having superior morphology embryo scores) was significantly better in the ICSI group than in the patients receiving HIC-IVF. Although there was a clear trend for better implantation and pregnancy rates in the ICSI group, these differences were not statistically significant. We conclude that, although HIC-IVF resulted in a higher fertilization rate than ICSI in patients with severe teratozoospermia, ICSI produced a significantly higher proportion of morphologically superior embryos with a tendency towards a higher implantation potential. Therefore, teratozoospermic patients having adequate numbers of motile spermatozoa should be offered ICSI as an alternative to modified (HIC) IVF treatment.

Cohort Studies↗
PubMed1995

Effects of hydrogen peroxide on human spermatozoa.

PURPOSE: Reactive oxygen species (ROS) have been reported widely to cause deleterious effects on sperm viability and function due to peroxidation of membrane lipids. However, their action appears more selective at low concentrations; recent evidence indicates that the superoxide anion can promote capacitation and induce hyperactivated motility (HA) in human spermatozoa and that hydrogen peroxide (H2O2) may participate in capacitation of hamster spermatozoa. The objective of these studies was to investigate the direct effects of H2O2 on functions crucial to fertilization in human spermatozoa. METHODS: In these prospective studies, we examined the dose- and time-dependent effects of H2O2 on sperm membrane-mediated events (binding to the zona pellucida and changes in intracellular calcium concentration [Ca2+]i, motility patterns, and acrosome reaction). Sperm from fertile donors were used in the experiments under capacitating conditions after separation of the motile fraction by wash/swim-up. [Ca2+]i was measured by the fluorescent fura-2 indicator, and sperm-zona pellucida binding was assessed with the hemizona assay (HZA). Hyperactivated motility was evaluated by computerized analysis, and the percentage of acrosome reacted sperm was detected by FITC-Pisum sativum lectin and indirect immunofluorescence. RESULTS: In the HZA, H2O2 did not influence sperm-zona pellucida binding at low concentrations (0.05 mM and 0.1 mM), but significantly reduced binding at 0.2 mM (P < 0.004 vs controls). H2O2 significantly decreased HA in a dose-dependent manner (P < 0.0001) and had a significant effect (P < 0.01) on acrosome reaction (stimulatory effect at 0.01 mM). H2O2 did not affect basal [Ca2+]i; however, H2O2 (0.1 mM through 10 mM) decreased the initial phase of progesterone-induced (P4: 1 microM) enhancement of [Ca2+]i in a dose- and time-dependent fashion. Preincubation of sperm with catalase (20 micrograms/ml) potentiated the P4-induced increase of [Ca2+]i. H2O2 did not significantly modify [Ca2+]i increase in response to inomycin (10 microM). CONCLUSIONS: These experiments show that H2O2 directly affects sperm functions crucial to fertilization in a dose- and time-dependent fashion. Low concentrations maintain capacitation, whereas higher concentrations have deleterious effects, as determined by the end points of the capacitation process. The latter effects are probably dependent on modifications of plasma membrane and intracellular homeostasis by the oxidative process.

Acrosome↗
PubMed1995

Factors affecting fertilization: endometrial placental protein 14 reduces the capacity of human spermatozoa to bind to the human zona pellucida.

OBJECTIVE: To examine whether placental protein 14 (PP14) may affect directly those sperm functions crucial to fertilization and early embryo development. DESIGN: In these prospective studies, we evaluated semen samples of fertile men incubated under capacitating conditions with and without PP14. SETTING: Academic tertiary institution. INTERVENTIONS: Biologically active PP14 was purified from human midtrimester amniotic fluid by anion exchange and immunoaffinity chromatography. After separation of the motile fraction, spermatozoa were incubated for 30 minutes with or without PP14 (concentration range of 0.01 to 100 micrograms/mL), washed, and then aliquots were prepared for use in the different assays. Human sperm-zona pellucida (ZP) binding was assessed using the hemizona assay (HZA) in a 4-hour gametes coincubation period. Sperm motility parameters were evaluated using a computerized semen analyzer. The acrosome reaction (AR) was determined by fluorescein isothiocyanate-conjugated Pisum sativum agglutinin and indirect immunofluorescence. MAIN OUTCOME MEASURES: Sperm-ZP binding, sperm motility patterns, and AR. RESULTS: Preincubation of sperm (and not the hemizonae) with PP14 produced a significant and dose-dependent inhibition of binding in the HZA. Monoclonal antibodies generated against PP14 showed no direct effect in the HZA and partially neutralized the inhibitory activity of PP14 in the HZA. Insulin-like growth factor binding protein-1 (IGFBP-1), an endometrial stromal cell product, showed no effect in the HZA. Neither PP14 nor IGFBP-1 interfered with sperm motility parameters or the AR. CONCLUSIONS: Placental protein 14 produced a potent, fast, and dose-dependent inhibition of binding of human spermatozoa to the human ZP without affecting other prefertilization events (i.e., hyperactivated motility or AR). The detrimental effect on sperm-zona interaction seems to be specific for this endometrial epithelial protein (not observed with an endometrial stromal product) and may have fundamental bearance to the fertilization process thus providing a mechanism for endometriosis-related infertility.

Acrosome↗
PubMed1995

High doses of gonadotropins have no detrimental effect on in vitro fertilization outcome in normal responders.

OBJECTIVE: To examine the effect of high doses of gonadotropins on IVF outcome in normal (intermediate) responders. DESIGN: Retrospective analysis of patients undergoing IVF therapy from 1990 to 1994 at our institution. SETTING: Academic tertiary center. PATIENTS: A homogeneous group of women that consisted of intermediate responders examined in their initial attempt and who received differing amounts of gonadotropins were examined. INTERVENTIONS: All patients were stimulated using a combination of a GnRH-agonist and FSH and hMG and were allocated into two groups, based on the amount of gonadotropin administered initially (four or six ampules). MAIN OUTCOME MEASURES: Implantation and pregnancy (clinical and ongoing) rates were compared. RESULTS: There were no significant differences between patients receiving high doses versus those patients receiving lower doses of gonadotropins with regard to implantation and pregnancy rates. CONCLUSIONS: We conclude that high doses of gonadotropins have no detrimental effect on IVF outcome in normal (intermediate) responders.

Adult↗
PubMed1995

Intracytoplasmic sperm injection: achievement of high pregnancy rates in couples with severe male factor infertility is dependent primarily upon female and not male factors.

OBJECTIVE: To determine the efficacy and factors affecting outcome of intracytoplasmic sperm injection (ICSI) in patients with severe male factor infertility. DESIGN: Prospectively designed clinical trial of patients selected to participate in the study based upon the following inclusion criteria: previous total failed fertilization or unsuitable sperm parameters for conventional IVF. SETTING: Tertiary care academic center. PATIENTS: Ninety-two consecutive couples undergoing IVF therapy augmented with ICSI during April through December 1994 were studied. MAIN OUTCOME MEASURES: Fertilization and ongoing implantation and pregnancy rates (PRs). RESULTS: A total of 1,163 preovulatory oocytes were manipulated, yielding a diploid fertilization rate of 60.9%; the oocyte damage rate was 13.2%. The transfer rate was 95% with 43.1% of cycles having excess embryos that were cryopreserved. Overall, the clinical and ongoing PRs per transfer were 31.9% and 26.8%, respectively. None of the sperm parameters of the original semen analysis correlated with ICSI outcome. Female age did not affect fertilization results but had a significant impact on PR (< 34 years: 48.9%; 35 to 39 years: 22.9%; > or = 40 years: 5.9% clinical PR per transfer). CONCLUSIONS: Intracytoplasmic sperm injection offers a new and powerful therapeutic option to treat couples with severe male factor infertility associated with a variety of sperm abnormalities. An adequate female age is a pivotal factor determining a successful outcome.

Adult↗
PubMed1995

New concepts in human sperm-zona pellucida interaction.

Binding of spermatozoa to the zona pellucida is an initial, crucial recognition event leading to fertilization. In the mouse, the best species characterized so far, the zona pellucida protein 3 (ZP3) has a central role as the specific, primary sperm receptor on the zona and as the inducer of the acrosome reaction. This sequence of events is not clearly understood as it relates to human gametes. The ideal test for the evaluation of sperm-zona pellucida interaction is one that can examine these events in a sequential fashion (i.e. binding followed by the acrosome reaction) in a standardized and specific bioassay. Here we have used the hemizona assay as an internally controlled test to examine human sperm-zona pellucida interaction. Results presented show that: (i) the hemizona assay has an excellent predictive power for IVF outcome and for the identification of male infertility; (ii) using a specific anti-ZP3 antiserum in immunocytochemical studies, the hemizona assay allows for the identification of structural/functional anomalies of the protein backbone of human ZP3 (identification of oocyte anomalies); and (iii) glycobiological studies using the hemizona assay model indicate that the initial sperm-zona pellucida binding requires a seletin-like interaction between the human gametes. These efforts may help us to characterize the cellular and molecular mechanisms involved in human gametes and their dysfunctions in infertile patients.

Animals↗
PubMed1995

An update on the laboratory assessment of male fertility.

Contemporary methods of assisted reproduction have undoubtedly enhanced the opportunities for conception in couples suffering from male infertility. The causes of male infertility are multiple, and current therapies do not usually address an aetiological or pathophysiological origin. Consequently, there is a fundamental need to gain knowledge for optimization of the clinical management of male infertility. The correct identification of specific sperm deficiencies is the only rational approach to develop pathophysiologically oriented therapies. Therefore, we strongly advocate a thorough andrological evaluation in all cases with the emphasis on the assessment of sperm quality and quantity. Although no single sperm feature can accurately predict fertilization or pregnancy potential (which is related to the complexity of the sperm capacitation-fertilization-embryo development processes), the examination of multiple sperm characteristics allows the clinician to direct the patient to different therapeutic interventions. This laboratory evaluation should be approached using a sequential, multi-step analysis that includes the basic semen evaluation and, where appropriate, a more advanced assessment of sperm functions, including biochemical tests and bioassays predictive of fertilization outcome. The standardization of the most relevant clinical diagnostic tests should be a major goal of all those involved in the care of the infertile couple.

Cytoplasm↗
PubMed1995

Investigation of some biochemical and functional effects of cryopreservation of human spermatozoa using an automated freezing-quick-thawing method.

The objective of the present studies was to assess the functional integrity of the sperm plasma membrane and metabolic and motility characteristics of the recovered motile fraction of human spermatozoa subjected to an automated freezing/quick-thawing method. Sperm membrane features examined included progesterone-induced changes in intracellular levels of calcium ([Ca2+]i), as measured by the fluorescent fura-2 indicator, and the tight binding of spermatozoa to homologous zonae pellucidae as assessed by the hemizona assay (HZA). Basal [Ca2+]i intracellular adenosine triphosphate (ATP) and adenosine diphosphate (ADP) levels determined using chemiluminescence with luciferin-luciferase, and motility parameters determined using a computer-aided semen analyser (CASA) were studied concomitantly as an expression of metabolic/functional status. Ejaculates from fertile men (donors) were evaluated after swim-up separation of the motile fraction in both fresh and cryopreserved-thawed samples, and fractions of each ejaculate (fresh and frozen-thawed) were subjected to parallel measurements of the same parameters at the same time frame. Basal and progesterone-induced increase in [Ca2+]i, and ATP levels (up to 24 h) were similar in fresh and frozen-thawed samples. HZA results showed a modest (26%) although significant (p = 0.008) decrease in binding in frozen-thawed samples. The ratios of ATP/ADP in fresh and frozen-thawed samples were also found to be similar. Although post-thaw sperm motility was significantly lower than that of the fresh samples, comparison of the results indicated that the method was capable of preserving > 65% of motile spermatozoa in almost all of the samples cryopreserved. Additionally, the swim-up rescued a motile fraction in the frozen-thawed samples that was not significantly impaired with regard to motility, mean linear velocity or linearity as compared to the fresh fractions in the first 4 h. Our results show that this automated freezing-quick-thawing method results in a small reduction in sperm-zona binding capacity, and that the time-dependent decline in motility parameters observed for both fresh and cryopreserved-thawed samples cannot be related to ATP deficiency under the conditions of our experiments. These in-vitro results are coincident with the maintenance of fertilizing capacity for donor spermatozoa in the in-vitro fertilization (IVF) setting.

Adenosine Diphosphate↗
PubMed1995

The role of endothelin-1 in regulating human granulosa cell proliferation and steroidogenesis in vitro.

The effects of endothelin-1 (ET-1) on luteinized human granulosa cells (L-HGCs) have not been examined. It is well known that there are differences of actions of several autocrine/paracrine regulators between L-HGCs and GCs of other species, and therefore the present study was designed to examine the effects of ET-1 1) on intracellular Ca2+ concentrations ([Ca2+]i) using the Ca(2+)-responsive fluorescent indicator Fura-2, 2) on cell proliferation by the nonradioactive method using bromodeoxyuridine, and 3) on basal and gonadotropin-stimulated steroidogenesis, and to examine the expression of ET receptor messenger RNA (mRNA) using freshly isolated and cultured L-HGCs obtained from patients undergoing in vitro fertilization. ET-1 increased [Ca2+]i in L-HGCs in a dose-dependent manner between 1 and 1000 nmol/L. High concentrations (100-1000 nmol/L) of ET-1 produced a more rapid and transient increase in [Ca2+]i than that observed with low concentrations (1-10 nmol/L) of ET-1. The increase in [Ca2+]i elicited by ET-3 (1000 nmol/L) and IRL-1620 (1000 nmol/L), a selective ETB receptor agonist, was 16% and 3% (vs. ET-1, 100%), respectively. BQ-123 (1000 nmol/L), an ETA receptor antagonist, inhibited the increase in [Ca2+]i elicited by ET-1 (by 50% at 1000 nmol/L ET-1 and by > 90% at < 500 nmol/L ET-1). mRNAs for the two known receptor subtypes (ETA and ETB) were also present in L-HGCs; however, the expression of ETA receptor mRNA was much greater than that of ETB receptors. ET-1 stimulated cell proliferation in L-HGCs in a dose-dependent manner (1000 nmol/L, 210.5 +/- 13.1%; 100 nmol/L, 198 +/- 11%; 10 nmol/L, 146 +/- 18%; and 1 nmol/L, 103 +/- 9%; vs. control, 100%). These stimulatory effects were completely blocked by BQ-123 (1000 nmol/L). ET-3 and IRL-1620 had no effects on cell proliferation in L-HGCs. Significant stimulatory effects on cell proliferation by the calcium ionophore, ionomycin (10-1000 nmol/L), were observed. ET-1, ET-3, and IRL-1620 attenuated basal progesterone secretion in L-HGCs. These results suggest that ETA receptor predominantly exist in L-HGCs and that ET-1 may stimulate cell proliferation of L-HGCs by increasing [Ca2+]i via ETA receptors.

Calcium↗
PubMed1994

Creatine kinase immunocytochemistry of human sperm-hemizona complexes: selective binding of sperm with mature creatine kinase-staining pattern.

OBJECTIVE: To examine the clinical significance of the increased sperm cytoplasmic content that is due to a fault of spermatogenesis, we have further studied the relationship between increased sperm creatine kinase (CK) concentrations and diminished fertilizing potential in men. In the present work, we used CK immunocytochemistry of human sperm-hemizona (HZ) complexes to examine whether the distribution of mature (clear heads), intermediate (sperm heads with light stippling), and immature (heads with heavy stippling or with solid CK staining) spermatozoa bound to the HZ would follow the incidence of these sperm in the samples tested, or if there is a preferential binding by the mature sperm. DESIGN: Two pairs of HZ were exposed to washed semen and to their swim-up sperm fractions. The sperm and sperm-HZ complexes were treated with a CK antibody followed by horseradish peroxidase immunostaining, and the sperm were evaluated for maturity. SETTING: Men presenting for fertility evaluation were studied in two university-based andrology laboratories. RESULTS: The binding of the HZ was selective for mature sperm as indicated by the incidence of intermediate and immature sperm in washed semen versus bound to the HZ (intermediate: 20.0% versus 1.4%; immature: 7.6% versus 0.5% [mean +/- SEM]) or in swim-up sperm fractions versus the HZ (intermediate: 18.7% versus 3.4%; immature: 2.5% versus 0.2%). The binding was almost exclusive to normal sperm (96.4% to 98.1%) whether the HZ were exposed to washed semen or swim-up fractions in spite of the five to ten times higher incidence of intermediate and immature sperm. CONCLUSIONS: Mature sperm selectively bind to the zona. We suggest that spermatozoa with immature CK-staining patterns are deficient in the site(s) of oocyte recognition and binding.

Blotting, Western↗
PubMed1994

Defective calcium influx and acrosome reaction (spontaneous and progesterone-induced) in spermatozoa of infertile men with severe teratozoospermia.

OBJECTIVE: To evaluate the acrosome reaction and its prerequisite, a calcium influx, in spermatozoa of infertile men with a high incidence of abnormal sperm forms. DESIGN: Prospective, controlled study. SETTING: Academic tertiary assisted reproduction center. PATIENTS: Patients (n = 14) were allocated in the study after semen evaluation showed teratozoospermia (< 14% normal sperm forms) as diagnosed by strict criteria. INTERVENTIONS: After swim-up separation of the motile fraction, acrosome reactions were evaluated using Pisum sativum agglutinin (both spontaneously and exogenously induced with P and the calcium ionophore A23187, both at 10 microM); the intracellular-free [Ca2+]i was assessed by the fluorescent fura-2 indicator (basal and after P). RESULTS: Patients did not show the typical P-induced wave of [Ca2+]i that was observed in controls but rather a blunted response, no response at all, or abnormal basal [Ca2+]i levels. The percent of basal acrosome reaction was significantly lower for patients versus controls postswim-up, and at 1 hour and 3 hours. Furthermore, there was a significant difference in the response of acrosome reaction to P both at 1 hour and 3 hours, with patients showing almost no response at all. However, patients' acrosome reaction response to the calcium ionophore was similar to those of fertile men. CONCLUSION: Infertile patients with a high incidence of abnormal sperm forms as diagnosed by strict criteria have a low incidence of spontaneous acrosome reaction and a diminished P-stimulated acrosome reaction, whereas the nonspecific response to a calcium ionophore is conserved. Parallel abnormalities of [Ca2+]i were observed in patients, suggesting that these sperm populations may have a defective nongenomic P sperm receptor and/or abnormalities of other membrane transduction systems.

Acrosome↗
PubMed1994

Sperm morphology as diagnosed by strict criteria: probing the impact of teratozoospermia on fertilization rate and pregnancy outcome in a large in vitro fertilization population.

OBJECTIVE: To investigate the predictive value of sperm morphology assessed by strict criteria on IVF outcome. DESIGN: Retrospective analysis of all IVF cycles (January 1987 to December 1992). MAIN OUTCOME MEASURES: All patients were assigned to one of three groups based on sperm morphology: P-pattern (< 4% normal forms), G-pattern (4% to 14% normal forms), and N-pattern (> 14% normal forms). Morphology pattern was related to other semen characteristics and IVF outcome. RESULTS: Despite corrective measures at oocyte insemination, the fertilization rate was significantly different among the three morphology groups, P < G < N. N-pattern sperm produced a mean fertilization rate over 85% regardless of low motility or concentration. In a cohort study, P-pattern cycles produced a lower implantation rate and lower ongoing pregnancy rate, independent of the lower fertilization rate. CONCLUSIONS: Strict morphology is an excellent biomarker of sperm fertilizing capacity, independent of motility and concentration. P-pattern sperm may denote a poorer prognosis for establishing a pregnancy, even after a satisfactory fertilization rate is achieved.

Adult↗
PubMed1994

A sequential analysis of the effect of progesterone on specific sperm functions crucial to fertilization in vitro in infertile patients.

The objective of these studies was to evaluate the modulatory effect(s) of progesterone on sperm functions crucial to fertilization in infertile men with abnormal sperm parameters. A prospective, controlled study applying a sequential diagnostic analysis capable of identifying specific dysfunctions of the male gamete was performed. Patients (n = 14) were allocated to the study group if they had a history of infertility of > 1 year duration and after semen evaluation showed teratozoospermia (< 14% normal sperm forms as diagnosed by strict criteria) or terato-asthenozoospermia (< 50% progressive motility). After swim-up separation of the motile sperm fraction, the following functions were assessed with and without previous exposure to progesterone (1.0 micrograms/ml): acrosome reaction (using Pisum sativum agglutinin), hyperactivated motility (using a computerized semen analyser), sperm-zona pellucida binding (in the hemizona assay), sperm-zona pellucida penetration (in a sperm-zona penetration assay), and sperm-oocyte penetration (using the hamster zona-free oocyte/sperm penetration assay). Progesterone did not affect the percentage of acrosome-reacted spermatozoa after 1 or 3 h of incubation. Hyperactivated motility was significantly enhanced by progesterone after 1 h (12 +/- 4 versus 6 +/- 2% in controls; P < 0.02). Although progesterone did not affect sperm-zona binding, it significantly enhanced both sperm-zona pellucida penetration (27 versus 12% in controls; P = 0.03) and sperm-oocyte penetration (15 versus 8% in controls; P < 0.05). Because those sperm functions enhanced by progesterone are crucial to fertilization, the steroid may have value in the treatment of some male-factor patients undergoing assisted reproductive therapy.

Acrosome↗
PubMed1994

Anti-ZP3 antibodies binding to the human zona pellucida: effect of oocyte-storage conditions.

PROBLEM: The zona pellucida protein 3 (ZP3) is a zona pellucida (ZP) glycoprotein crucially involved in fertilization. ZP3 plays a major role in sperm binding and induction of the acrosome reaction. In different species, ZP3 proteins differ in their primary structure as derived from cDNA clones. The hemizona assay (HZA) is a bioassay that evaluates binding of human sperm to human ZP and is highly predictive of fertilization outcome under in vitro conditions. METHOD: In these studies, we used antisera generated against synthetic ZP3 peptides to compare antibody binding patterns to ZP with sperm-ZP binding capacity under different HZA conditions. RESULTS: Analysis of antibody binding to hemizonae derived from metaphase II human oocytes that were used either after refrigeration at 4 degrees C or stored in a hyperosmotic salt solution revealed a strong reaction with human ZP3. However, treatment of human oocytes using a protocol to freeze embryos with the addition of 1,2 propanediol drastically reduced binding of ZP3 antibodies to the hemizonae. Nevertheless, no significant difference of sperm binding occurred under HZA conditions when oocytes were refrigerated, salt-stored, or frozen with 1,2 propanediol. CONCLUSIONS: Our results indicate that the ZP3 protein backbone might be altered by 1,2 propanediol-treatment while the glycoprotein-receptor remains intact. We conclude that antisera against ZP3 peptides can be used as markers for the ZP3 protein backbone in human oocytes and might be useful tools for the evaluation of ZP3 protein integrity.

Cells, Cultured↗
PubMed1994

Existence of P2-purinoceptors on human and porcine granulosa cells.

This study examines the possible roles of extracellular purine nucleotides in regulating ovarian granulosa cell function. Using luteinized human (L-hGC) and porcine granulosa cells (PGC), we examined the effects of purine nucleotides on intracellular free Ca2+ concentrations ([Ca2+]i), and whether they have any effect on steroidogenesis and cell proliferation. L-hGC and PGC were responsive to ATP and ADP at concentrations ranging from 0.1-100 mumol/L in a dose-dependent manner. There was a difference between L-hGC and PGC in the rank orders of agonist potencies for stimulating [Ca2+]i; for L-hGC, UTP > ATP > ATP gamma s > ADP > AMPPNP >> AMP and adenosine; for PGC, 2-methylthio ADP (2-meS ADP) > ADP > ATP = ATP gamma s = UTP > AMPPNP >> AMP and adenosine. No apparent additivity between the responses elicited by UTP and the purine nucleotides (ATP and ADP) was shown in L-hGC. On the other hand, an apparent additive effect between the responses to ADP and UTP was shown on PGC. Furthermore, ATP was a competitive antagonist of the action of ADP on [Ca2+]i levels in PGC. ATP, ADP, and AMP as well as adenosine stimulated basal progesterone and estradiol secretion from L-hGC, however, UTP had no effect on steroidogenesis in L-hGC. On the other hand, purine nucleotides and UTP as well as adenosine inhibited progesterone and estradiol secretion on PGC. However, 2-meS ADP, the most potent agonist for P2T-purinoceptors, did not affect steroidogenesis in PGC. Purine nucleotides had no influence on cell proliferation of L-hGC and PGC. These results indicate the existence of P2U-purinoceptors on L-hGC and P2U- plus P2T-purinoceptors on PGC, and that the inhibitory effect of purine nucleotides on steroidogenesis in PGC is most likely due to A1-adenosine receptors and also P2U-purinoceptors.

Animals↗
PubMed1993

A revised structure for fucoidan may explain some of its biological activities.

Fucoidan from Fucus vesiculosus inhibits human sperm-zona pellucida binding and blocks the zona pellucida-induced acrosome reaction in human sperm. Fucoidan also potently inhibits selectin-mediated adhesion of leukocytes to vascular endothelium. To understand the molecular basis for fucoidan's inhibition of specific cell adhesion events, we have investigated the structure of this fucan using definitive methods of carbohydrate structural analysis. We report the revised average structure for fucoidan. [formula: see text] This average structure differs from the previous model for fucoidan in two respects. First, the core region of the fucan is composed primarily of a polymer of alpha 1-3-linked fucose with sulfate groups substituted at the 4 position on some of the fucose residues. Secondly, fucose is also attached to this polymer to form branch points, one for every 2-3 fucose residues within the chain. This revised average structure is consistent with previous studies suggesting a branched random coil as the best model for this polysaccharide. The proposed model is also a closer structural analogue of the sulfated carbohydrate ligands that bind to selectins. This information should be useful for determining whether a relationship exists between selectin-mediated adhesion of leukocytes and human sperm-egg binding.

Carbohydrate Conformation↗
PubMed1993

The specificity of human spermatozoa/zona pellucida interaction under hemizona assay conditions.

The objective of this prospective study was to evaluate the specificity of human sperm/zona pellucida interaction under hemizona assay (HZA) conditions in experiments with gametes from the same and different species. Human, cynomolgus monkey and hamster oocytes were used after salt-storage. Oocytes were bisected into matching hemizonae by micromanipulation and used in the HZA. Semen was obtained from healthy men (donors) and male cynomolgus monkeys and prepared by wash and swim-up. Sperm binding to matching hemizonae was assessed (tight binding) after 4-h coincubation in the HZA in homologous and interspecies experiments. Acrosome reaction was evaluated in the sperm droplets using FITC-PSA and on the hemizonae using the T-6 monoclonal antibody. On human hemizonae, the number of tightly bound sperm for human and monkey were 93.2 +/- 15.8 and 3.9 +/- 1.3, respectively (P < 0.001). On monkey hemizonae, the number of tightly bound sperm for monkey and human were 126.0 +/- 34.8 and 2.8 +/- 1.6, (P = 0.02) respectively. On hamster hemizonae, there was negligible binding of human and monkey sperm. There was a significantly higher incidence of acrosome reacted sperm on the zona pellucida in homologous compared to heterologous experiments. These results demonstrate a high species-specificity of human gamete functions under HZA conditions, providing further support for the use of this bioassay in infertility and contraception testing.

Acrosome↗