PubMed Health⌕ Search

Biomedical subjects

S Oehninger

Publications and source records attributed to S Oehninger.

At least 19 recordsLinked to original sources
PubMed1997

Effects of sperm viability on fertilization and embryo cleavage following intracytoplasmic sperm injection.

PURPOSE: In the human, intracytoplasmic sperm injection is typically performed using "viable" sperm which has been mechanically rendered nonmotile. The purpose of the present study was to determine the ability of nonviable sperm to fertilize human oocytes and the early developmental normalcy of the resulting embryos. METHODS: In this study, immature, prophase I oocytes from a total of 27 consenting patients were matured in vitro and then randomized into two groups: injection with a viable human sperm or injection with a sperm rendered nonviable by freeze-thawing in liquid nitrogen. The rates of fertilization and cleavage were compared between the two groups. RESULTS: The results demonstrated a significantly higher two-pronuclear fertilization rate when oocytes were injected with viable sperm (62.2%) compared to when oocytes were injected with nonviable sperm (16.2%). Oocytes injected with viable sperm also demonstrated a higher cleavage rate (91 vs 33%). CONCLUSIONS: These findings suggest that while the intracytoplasmic injection of nonviable human sperm can result in normal fertilization, it does so at a much reduced rate compared to viable sperm and may not result in normally cleaving embryos.

Cell Survival↗
PubMed1997

Clinical significance of human sperm-zona pellucida binding.

OBJECTIVE: To assess the relationship between sperm morphology and motion parameters and sperm-zona pellucida (ZP) binding capacity under hemizona assay (HZA) conditions and to determine the discriminatory power of the HZA for the prediction of in vitro sperm fertilizing ability. DESIGN: Prospectively designed study. SETTING: Academic tertiary centers. PATIENT(S): One hundred ninety-six couples undergoing IVF therapy participated in this study. INTERVENTION(S): Hemizona assay and IVF results were determined for each couple. MAIN OUTCOME MEASURE(S): Computerized sperm motion analysis, sperm morphology (strict) criteria), and HZA results were correlated with fertilization outcome. RESULT(S): Among sperm parameters from the original ejaculates, morphology was the best predictor of sperm-ZP binding ability; hyperactivated motility was the best predictor of HZA results after swim-up separation of the motile sperm fractions. The HZA index provided the highest discriminatory power for fertilization success/failure, with an overall accuracy of 86%. CONCLUSION(S): Sperm morphology and hyperactivated motility showed a high correlation with the capacity of sperm to achieve tight binding to the ZP. The excellent positive and negative predictive values of the HZA for fertilization outcome provide additional support for the use of this functional bioassay in the decision-making process within the assisted reproduction setting.

Female↗
PubMed1997

Cryopreservation of all prezygotes in patients at risk of severe hyperstimulation does not eliminate the syndrome, but the chances of pregnancy are excellent with subsequent frozen-thaw transfers.

In-vitro fertilization patients (n = 15) at risk of ovarian hyperstimulation syndrome (OHSS) (oestradiol > or =4500 pg/ml on the day of human chorionic gonadotrophin administration and 25 or more follicles of intermediate or large size) underwent aspiration of all follicles and cryopreservation of all fertilized oocytes at the pronuclear stage. Patients were monitored for up to 2 weeks post-retrieval. Subsequent transfer of cryopreserved-thawed embryos was performed in programmed cycles using exogenous oestrogen and progesterone for endometrial preparation. Two patients (13%) developed OHSS necessitating hospitalization and vaginal aspiration of ascitic fluid. Two other patients (13%) developed moderate OHSS requiring ascitic fluid vaginal aspiration in the office setting, with dramatic improvement of the condition. Subsequent transfer of cryopreserved-thawed embryos yielded a clinical pregnancy rate of 58% per transfer and ongoing or delivery rates of 42 and 67% per transfer and per patient respectively. By eliminating pregnancy potential with cryopreservation of all prezygotes and examining the pregnancy potential with subsequent cryopreserved-thawed transfers, it is concluded that OHSS is reduced, but not eliminated for patients at risk. Subsequent transfer of cryopreserved-thawed prezygotes in a programmed cycle with exogenous steroids yields an excellent pregnancy rate.

Adult↗
PubMed1997

Viewing AIDS from a glycobiological perspective: potential linkages to the human fetoembryonic defence system hypothesis.

The primary molecular changes that lead to development of acquired immunodeficiency syndrome (AIDS) are very poorly understood, as are the mechanisms underlying the protection of the developing human from the maternal immune response. Recent data that the human immunodeficiency virus (HIV) may be using the glycosylation system of the T lymphocytes to acquire glycans for its glycoproteins that enable it to disrupt carbohydrate dependent immune cell interactions or induce aberrant immune reactions. Consistent with this hypothesis, gp120 from HIV infected human H9 lymphoblastoid cells expresses biantennary N-linked glycans with a bisecting GlcNAc sequence on 11% of their total oligosaccharides. This specific carbohydrate sequence has recently been shown to protect K562 erythroleukemic cells from natural killer (NK) cell responses when presented on the cell surface. We have recently demonstrated that bisecting biantennary type N-linked glycans are also expressed on the human zona pellucida (ZP); previous lectin binding studies indicate that is also expressed on human spermatozoa. Thus both the human gametes and HIV produced by H9 cells carry this same protective carbohydrate epitope on their outer surfaces. Human alpha-fetoprotein expressed in the developing human also carries the bisecting GlcNAc sequence, indicating that it may be suppressing the emerging fetal immune response by using its carbohydrate sequence as a functional group. We have suggested that the developing human and the gametes are also protected by soluble immunosuppressive glycoproteins found in the amniotic fluid and seminal plasma known as glycodelin-A (GdA) and glycodelin-S (GdS) respectively. Structural analysis of their N-linked oligosaccharides combined with other functional studies suggest that GdA and GdS employ their very unusual carbohydrate sequences as functional groups that enable them to manifest their immunosuppressive activities. GdA and GdS are significant components of our recently proposed model for the protection of the developing human and gametes designated the human fetoembryonic defence system hypothesis. A striking relationship now emerging is that the same unusual carbohydrate sequences associated with these immunosuppressive glycodelins are also specifically expressed on intravascular helminthic parasites, Helicobacter pylori, human tumour cells, and HIV infected T lymphocytes. The information presented in this review suggests that two new corollaries should be added to our recently proposed defence system hypothesis: (i) mimicry or acquisition of glycans that are used in this protective system by pathogens or tumour cells may enable them to either subvert or misdirect the human immune response, thereby greatly increasing their pathogenicity; and (ii) expression of glycoproteins used in this system by normal cells and tissues outside the reproductive system may protect them from immune responses, especially in those cases where major histocompatibility recognition is either absent or minimal. A better understanding of this hypothesis and its corollaries may enable us to address the molecular mechanisms underlying not only AIDS but also a host of other very serious pathological conditions in the human.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Expression of glycans linked to natural killer cell inhibition on the human zona pellucida.

Protection of the gametes from potential immune responses is a primary function in human reproduction. The primary cell type responsible for the innate immune response in the uterus is the natural killer (NK) cell. NK cells normally recognize Class I major histocompatibility (MHC) molecules on potential target cells. Since both human spermatozoa and human oocytes do not express Class I MHC molecules on their surfaces, the appropriate cell surface signal that abrogates potential NK cell-mediated responses directed against these gametes is unknown. Recent evidence indicates that surface expression of bisecting-type N-linked glycans protects cells sensitive to NK cell-mediated lysis. We report that the zona pellucida of the human egg and plasma membranes of human spermatozoa potentially bind a lectin probe specific for bisecting type glycans in a carbohydrate-dependent manner. Since the innate immune response in the uterus is primarily mediated by NK cells, our results indicate that human gametes may be protected from this response by expressing bisecting type N-linked glycans on their surfaces.

Carbohydrate Conformation↗
PubMed1996

Gender-specific glycosylation of human glycodelin affects its contraceptive activity.

We have recently demonstrated that a human amniotic fluid-derived glycoprotein, glycodelin-A (GdA; previously known as PP14 or PAEP), potently inhibits gamete binding in an established sperm-egg binding system and expresses immunosuppressive activities directed against a variety of different immune cell types. GdA has high mannose-, hybrid-, and complex-type biantennary oligosaccharides including structures with fucosylated or sialylated N, N'-diacetyllactosediamine (GalNAcbeta1-4GlcNAc) sequences, which are rare in other human glycoproteins. We now report the characterization of glycodelin-S (GdS). This is a human seminal plasma glycoprotein that is immunologically indistinguishable from GdA, but unlike the latter, does not inhibit human sperm-zona pellucida binding under hemizona assay conditions. Analysis of the N-glycans of GdS by mass spectrometry revealed that all glycoforms of GdS are different from those of GdA. GdS glycans are unusually fucose-rich, and the major complex-type structures are biantennary glycans with Lewisx (Galbeta1-4(Fucalpha1-3)GlcNAc) and Lewisy (Fucalpha1-2Galbeta1-4(Fucalpha1-3)GlcNAc) antennae. It is probable that these highly fucosylated epitopes contribute to the immunosuppressive activity of human seminal plasma and to the low immunogenicity of sperm. This study provides the first evidence for gender-specific glycosylation that may serve to regulate key processes involved in human reproduction.

Contraceptive Agents↗
PubMed1996

Use of a specific zona pellucida (ZP) protein 3 antiserum as a clinical marker for human ZP integrity and function.

OBJECTIVE: To evaluate binding characteristics of a specific zona pellucida (ZP) protein 3 (ZP3) antiserum to human oocytes in order to determine its usefulness as a clinical marker for human ZP integrity and function and its correlation with IVF outcome. DESIGN: Prospectively designed, blinded, internally controlled study. SETTING: Tertiary care academic center. PATIENTS: Patients undergoing IVF therapy who had either total failed fertilization or partial fertilization were studied. INTERVENTIONS: Metaphase II oocytes showing absence of pronuclear formation were salt stored 48 hours after insemination and bisected into matching hemizonae using micromanipulation. One hemizona was incubated with AS ZP3-6 (an antiserum generated against a synthetic ZP3 peptide derived from an amino acid sequence that is highly conserved in the structure of ZP3), whereas the matching hemizona was incubated with AS ZP3-7, an antiserum detecting exclusively mouse ZP3 (internal, negative control). Antibody binding was visualized using the peroxidase-antiperoxidase method and diaminobenzidine as color reagent. RESULTS: A total of 104 unfertilized oocytes were evaluated. Analysis of variance showed a significant interaction between gamete factor groups (sperm and oocyte) and antiserum factor. Patients with oocyte factor had significantly lower mean staining scores for the AS ZP3-6-treated hemizonae than patients with sperm factor. CONCLUSIONS: These results demonstrate that anomalies of human ZP3 can be identified with AS ZP3-6 and that these ZP abnormalities correlate with fertilization failure during IVF treatment. Thus, this newly developed biomarker may be of clinical significance in the identification of oocyte defects that are associated with fertilization disorders and may help in the decision-making process in the IVF-assisted fertilization setting.

Adult↗
PubMed1996

A role for glycoconjugates in human development: the human feto-embryonic defence system hypothesis.

The mechanisms underlying the protection of the human embryo/fetus from the maternal immune response are poorly understood. Substantial evidence indicates that carbohydrate recognition plays a primary role in the sequestration of leukocytes during inflammatory processes, lymphocyte homing, and initial gamete binding. Our previous studies suggest a possible convergence in the types of carbohydrate sequences recognized during initial human gamete binding and immune/inflammatory cell interactions. Our more recent findings indicate that oligosaccharides participating in such processes are also associated with soluble glycoconjugates found in the human placenta, amniotic fluid, and decidua. We theorize that such glycoconjugates may abrogate the maternal immune/inflammatory response by blocking the primary adhesive interactions required for the expression of such activities. Foreign embryonic cells may also be protected by surface expression of oligosaccharide sequences that suppress immune effector cell action in a manner not dependent upon classical major histocompatibility (MHC) recognition. Glycoconjugates expressing selectin ligands may also manifest a potent contraceptive effect that may also be beneficial for both the mother and the developing embryo/fetus. This hypothesis provides a preliminary framework for understanding how temporally and spatially restricted immunosuppressive effects could be expressed in utero that protect the human embryo/fetus during this period of human development.

Animals↗
PubMed1996

Salpingectomy improves the pregnancy rate in in-vitro fertilization patients with hydrosalpinx.

The objective of this study was to assess the impact on pregnancy outcome of excising hydrosalpinx(ges) in patients with repeated in-vitro fertilization (IVF) failures. A group of 15 patients who had previously undergone failed IVF attempts and had unilateral or bilateral hydrosalpinx was subjected to an operative laparoscopy with excision of the affected tube(s). Of these, 10 patients underwent a unilateral salpingectomy and five had a bilateral salpingectomy. Stimulated cycles of IVF and/or cryo-thaw cycles were then carried out post-salpingectomy and the results were compared to those of pre-salpingectomy cycles. There was no statistically significant difference between the number of mature eggs retrieved, peak oestradiol concentrations, number of days to human chorionic gonadotrophin administration, or number of pre-zygotes frozen in the stimulated cycles pre- versus post-salpingectomy. Pre-salpingectomy, 15 patients underwent 38 stimulated cycles and eight patients underwent 14 cycles with cryopreserved-thawed embryos, achieving one pregnancy from a fresh transfer that resulted in a miscarriage. Post-salpingectomy, eight patients underwent 12 stimulated cycles, achieving five clinical pregnancies (two miscarriages and three ongoing pregnancies, i.e. either delivered or a pregnancy > or = 20 weeks), and nine patients underwent 10 cycles with cryopreserved-thawed embryos, achieving four clinical pregnancies (one miscarriage and three ongoing). We conclude that excision of hydrosalpinx(ges) improves the pregnancy potential after IVF, and that new and repeat IVF patients should be counselled accordingly.

Adult↗
PubMed1996

Glycodelin from seminal plasma is a differentially glycosylated form of contraceptive glycodelin-A.

Glycodelin-A is a human amniotic fluid-derived glycoprotein with contraceptive and immunosuppressive activities. An immunoreactive form of glycodelin was detected in seminal plasma over a decade ago, but definitive characterization of this glycoprotein was not pursued. We considered it unlikely that the seminal plasma of fertile men would contain an appreciable amount of contraceptive glycodelin-A. To address this issue we purified seminal plasma glycodelin (glycodelin-S) and performed comparative studies with glycodelin-A. Glycodelin-S behaved differently when compared with glycodelin-A during sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing but identically after enzymatic deglycosylation. N-terminal sequencing of glycodelin-A and glycodelin-S gave identical results, and digestion with trypsin gave identical peptide fragments. The glycoproteins were also found to be indistinguishable from each other based upon immunological analyses. These results indicate that glycodelin-S and glycodelin-A have similar overall protein structure, suggesting the likelihood that these glycoproteins are differentially glycosylated forms of very similar proteins. This latter possibility is supported by lectin binding studies indicating that, unlike glycodelin-A, glycodelin-S does not manifest any affinity for lectins from Wisteria floribunda or Sambucus nigra. The results of sugar analysis and neuraminidase digestion also lead us to conclude that glycodelin-S and glycodelin-A are differentially glycosylated forms of similar proteins. Our evidence indicates that glycodelin-A mediated its biological activities via its unusual oligosaccharide sequences that are not associated with glycodelin-S. In lectin-immunoassay no appreciable amount of contraceptive glycodelin-A was found in the 22 seminal plasma samples studied.

Amidohydrolases↗
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↗