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Biomedical subjects

A Herman

Publications and source records attributed to A Herman.

At least 19 recordsLinked to original sources
PubMed1992

Mutations defining functional regions of the superantigen staphylococcal enterotoxin B.

Staphylococcal enterotoxin B (SEB) is both a superantigen and toxin. As a superantigen, SEB can bind to major histocompatibility complex (MHC) class II molecules to form a ligand for alpha/beta T cell receptors bearing particular V beta elements. As a toxin, SEB causes rapid weight loss in mice sometimes leading to death. We show here that both of these functions map to the NH2-terminal portion of the toxin. Three regions were identified: one important in MHC class II binding, one in T cell recognition, and one in both functions. These results support the conclusion that the toxicity of SEB is related to massive T cell stimulation and release of cytokine mediators and show that the residues interacting with MHC and the T cell receptor are intertwined.

Amino Acid Sequence↗
PubMed1992

Methotrexate local injection for unruptured tubal pregnancy: an alternative to laparotomy?

Fifty-nine women with early unruptured tubal pregnancy were treated by a single local injection of methotrexate at laparoscopy. All 59 patients underwent the procedure without any adverse reaction, 47 (80%) of them needing no laparotomy. Twelve patients required a laparotomy for reasons such as rising beta-hCG levels and abdominal pain with or without rising levels of beta-hCG. Only one patient ruptured the tube. None of the women needed a blood transfusion. We found tubal patency in 19 out of 21 patients at follow up hysterosalpingography. Eleven pregnancies were subsequently reported, one of them tubal. The appearance of the injected tube was absolutely normal in three patients, one at cesarean section and two at repeated laparoscopy. No peritubal adhesions were observed. We suggest that this new technique is a safe and effective alternative to laparotomy in a patient with an early unruptured tubal pregnancy.

Adult↗
PubMed1992

Increased fertilization and pregnancy rate in polypronuclear fertilization cycles in in vitro fertilization-embryo transfer.

OBJECTIVE: To compare fertilization and pregnancy rates between cycles with polypronuclear fertilizations and cycles with normal fertilizations. DESIGN: In vitro fertilization-embryo transfer (IVF-ET) cycles in which oocytes were retrieved were divided into two groups according to the nature of fertilization. PATIENTS: All patients were participants of our IVF-ET program. RESULTS: A significantly higher fertilization rate was found in the polypronuclear fertilization cycles (61% versus 36.6%) and also an improved pregnancy rate (47.5% versus 19.6%) and per embryo transfers (53% versus 28.8%). The vast majority of polypronuclear fertilizations occurred in mature oocytes. CONCLUSION: We believe that the increased receptability of the oocytes improves fertilization and conception rates. The polypronuclear fertilization is an extreme expression of such improved receptibility and should be considered as an encouraging sign for conception.

Embryo Transfer↗
PubMed1992

Prediction of in vitro fertilization outcome by sperm penetration assay with TEST-yolk buffer preincubation.

OBJECTIVE: To evaluate sperm penetration assay (SPA) value as a screening tool before in vitro fertilization (IVF). DESIGN: Follow-up study comparing sperm variables and IVF outcome. SETTING: Infertile couples in an academic research environment. PATIENTS, PARTICIPANTS: Two hundred forty-one infertile couples scheduled for IVF. INTERVENTIONS: Sperm penetrating assay with cold Tes-TRIS (TEST) Yolk buffer semen preincubation and IVF. MAIN OUTCOME MEASURES: Percent of egg penetration recoded into poor and good category (0% to 20%, 21% to 100%) and compared with fertilization, embryo transfer, and pregnancy rate (PR) in IVF, as well as sperm count motility and morphology. RESULTS: Sperm penetrating assay predicted fertilization with a high negative (74%) and positive (82%) predictive rate and good specificity value (0.96). One of 31 patients in the poor SPA category (3%) fertilized less than 50% of eggs; no pregnancy occurred. In the good SPA category, 87 of 210 patients (41%) fertilized greater than or equal to 50% of eggs with 34.3% PR. Sperm penetrating assay correlated better with fertilization rate than did sperm count and motility but not morphology. CONCLUSIONS: Sperm penetrating assay is a useful screening assay before IVF together with sperm morphology.

Adult↗
PubMed1992

Ultrashort gonadotropin-releasing hormone agonist (GnRH-a) protocol in comparison with the long-acting GnRH-a protocol and menotropin alone.

OBJECTIVE: To compare the in vitro fertilization and embryo transfer (IVF-ET) outcome of a 3-day gonadotropin-releasing hormone agonist (GnRH-a) administration: ultrashort protocol with the outcome of long-acting GnRH-a cycles or human menopausal gonadotropin (hMG) alone. DESIGN: Ninety-two cycles of the ultrashort protocol were matched with 92 cycles with long GnRH-a and with 92 hMG cycles. SETTING: The IVF-ET program. MAIN OUTCOME MEASURES: Amount and duration of hMG treatment, hormonal profile on the day of human chorionic gonadotropin administration, cancellation rate, number of oocytes retrieved, and fertilization and pregnancy rates (PRs) were examined and compared among the three groups. RESULTS: The ultrashort group needed a higher number of hMG ampules than the hMG group but significantly less than in the long GnRH-a regimen. The number of oocytes in the ultrashort protocol was the same as in the long GnRH-a, but the number of embryos per retrieval was significantly lower than with the long GnRH-a protocol and similar to that found in the hMG group. The ultrashort protocol yielded 10% PR per cycle and 17% per replacement, significantly lower than with the long GnRH-a protocol, 26% and 36%, respectively, but also lower than in the hMG one, namely 13% and 28%. CONCLUSION: The ultrashort protocol, although being convenient and having some advantages found in the long GnRH-a protocol, is inferior in its outcome compared with the two other protocols.

Chorionic Gonadotropin↗
PubMed1992

Diagnostic hysteroscopy: its value in an in-vitro fertilization/embryo transfer unit.

A total of 324 patients participating in our in-vitro fertilization/embryo transfer (IVF) programme underwent a diagnostic hysteroscopy. Of these, 152 women were referred before their first IVF attempt, because of some hysterosalpingographic suspicion of an intra-uterine abnormality; the other 172 patients had failed to conceive after IVF and transfer of good quality embryos. An intra-uterine pathology (mainly intra-uterine adhesions) was diagnosed in 50% of the patients in each group. Hysterosalpingography, although very sensitive, had low specificity (23%), a false positive rate of 44% and false negative rate of 10%. The main risk factor for intra-uterine pathology was a previous abortion. Conception rates were 22% after surgical treatment and 38% after the diagnostic procedure. We think that hysteroscopy should be performed in every patient failing to conceive after replacement of good quality embryos. It is also recommended whenever a suspicious finding is revealed by hysterosalpingography, before IVF. Routine hysteroscopy before entering an IVF programme should be seriously considered.

Adult↗
PubMed1992

Impaired corpus luteum function and other undesired results of pregnancies associated with inadvertent administration of a long-acting agonist of gonadotrophin-releasing hormone.

Spontaneous pregnancies associated with inadvertent periconceptional administration of long-acting gonadotrophin releasing-hormone agonist (GnRHa), in in-vitro fertilization, occurred in 11 of 161 patients with non-tubal infertility. All these cases exhibited impaired function of the corpus luteum in terms of declining progesterone levels, despite rising levels of human chorionic gonadotrophin. The patients were categorized according to the timing of GnRHa administration: periovulatory (three cases), midluteal (five cases) and late luteal (three cases). Altogether, of the 11 pregnancies, seven ended with a normal livebirth, three with a preclinical gestation and one with a blighted ovum. It appears that spontaneous pregnancies associated with inadvertent administration of GnRHa are not rare. Awareness for early diagnosis and close hormonal monitoring are recommended for the assessment of corpus luteum function and adequate supplementation.

Adult↗
PubMed1992

Prerequisite work-up of the couple before in-vitro fertilization.

Prerequisite examinations, including immune status for rubella and hepatitis B antigens, cultures for Chlamydia trachomatis and mycoplasmas, Pap smear and hystersalpingogram were performed in 227 couples before their enrollment into an in-vitro fertilization (IVF) programme. The examinations were completed in 187 couples. Immune status for rubella had already been documented in 45% of the women: of the remainder, 11 patients were not immune (6%). A screening test for hepatitis B antigens had already been documented in only 10% of the patients; eight of the remaining women (5%) were carriers of hepatitis B antigen. C. trachomatis and Mycoplasma hominis were each isolated from 14% of the patients and Ureaplasma urealiticum from 16%. Pap smears had been previously performed in only 35% of the enrolled women. Six (5%) of the 122 newly referred cases had cervical intra-epithelial dysplasia. In 21 (11%) cases some pathology in the uterine cavity was demonstrated. One patient conceived after diagnostic hysteroscopy; another two patients conceived following lysis of adhesions and before IVF treatment. The results of this study show the importance of the preparatory examinations before the IVF and embryo transfer procedure, and raise the medical and medico-legal aspects of this prerequisite work-up.

Adult↗
PubMed1991

Identification of the staphylococcal enterotoxin A superantigen binding site in the beta 1 domain of the human histocompatibility antigen HLA-DR.

The staphylococcal enterotoxin A (SEA) is a superantigen that must bind to class II molecules of the major histocompatibility complex to be recognized by T cells. In humans, most HLA-DR class II allelic and isotypic forms, such as DR1, bind SEA well. DRw53 is an exception, binding SEA very poorly. We have localized this difference to a single residue (amino acid 81) in the beta 1 domain. A highly conserved histidine at residue 81 allows SEA binding, but a tyrosine does not. Residue 81 is predicted to lie in an alpha-helix on the surface of the molecule, with its side chain pointing up out of the pocket associated with binding of conventional peptide antigens. This finding supports the hypothesis that superantigens and conventional antigens bind to different sites on the class II molecule.

Amino Acid Sequence↗
PubMed1991

Clear ovarian cyst aspiration guided by vaginal ultrasonography.

Thirty patients with clear ovarian cysts underwent aspiration guided by vaginal ultrasound. In 23 cases a complete aspiration was accomplished. In 4 only partial aspiration was possible, and in the remaining 3 failed aspiration led to surgery. Histological findings correspond to retroperitoneal lipoma and mucinous cystadenoma (2 cases). Malignant cells were not detected in the fluid of any of the 27 aspirates. Eight of the ten patients presenting with abdominal pain experienced a relief following aspiration. Recurrence of the cyst occurred in 12 cases (40%) with significantly smaller dimensions (P less than 0.01). Vaginal ultrasound aspiration of clear cyst is easy and safe and can be considered as an outpatient procedure.

Adult↗
PubMed1991

Fluorescein angiography in hypertensive pregnancies.

A retrospective study in two university hospitals investigating retinal changes in pregnancies complicated by hypertension, seldom revealed retinal vascular changes in pre-eclamptic toxemia. Fluorescein angiography was performed on 16 severe pre-eclamptic toxemias and 14 chronic hypertension pregnancies. Normal caliber retinal vessels and normal filling time, with no subretinal or subepithelium leakage, was found in all pre-eclamptic toxemic patients. Four out of the 14 chronic hypertensive patients showed signs of mild hypertensive retinopathy. A review of the literature on fluorescein angiography in pregnancy showed that vascular changes in pre-eclamptic toxemia are choroidal rather than retinal.

Adult↗
PubMed1991

Extremely large number of twists of the umbilical cord causing torsion and intrauterine fetal death.

Extremely large number of twists of the umbilical cord causing torsion of the entire length of the umbilical cord was found in two cases of intrauterine fetal death. It was twisted in one case 35 times and in the other 20 times. No additional pathology, such as stricture or abnormality of the Wharton's jelly, was found. The two mothers complained of decreased fetal movements and both newborns were found later to be growth retarded. A long cord of 120 cm was present in one case and normal length of 70 cm in the other. Close antenatal care in cases with growth retarded fetuses or decreased fetal movements may help in avoiding fetal demise in such rare cases.

Adult↗
PubMed1991

Delayed fertilization and poor embryonic development associated with impaired semen quality.

Delayed fertilization is common in cycles with immature oocytes. This phenomenon was observed in 42 of 423 with mature oocytes. Of the 42 cycles, 16 were excluded because of the presence of sperm autoantibodies. Sperm parameters of the remaining 26 (6.1%) cycles (group A) were compared with those in cycles with no fertilization at all (group B) and those in the control group (group C). The percentage of normal forms was 15% in group B and 24% in group A compared with 51% in group C. Fertilization rates were 32% in group A compared with 81% in group C. The incidence of poor embryonic morphology was 82% in group A compared with 29% in group C. Delayed fertilization and poor embryonic morphology associated with impaired sperm quality is of clinical and prognostic importance.

Blastomeres↗
PubMed1991

The dilemma of the optimal surgical procedure in ectopic pregnancies occurring in in-vitro fertilization.

Ectopic pregnancy remains one of the undesired sequelae of in-vitro fertilization (IVF) treatment. It seems that mechanical infertility increases the risk of this complication in IVF. Thus, the surgeon treating such a case faces the dilemma of the optimal surgical procedure because of the increased risk for repeated ectopic pregnancy in subsequent IVF cycles. Two cases are presented with repeated ectopic pregnancy occurring in IVF. One case underwent salpingectomy on the first occasion and eventually developed a contralateral repeat ectopic gestation ending with salpingectomy. The second case underwent a conservative salpingotomy in the first event and developed a repeated ectopic gestation on the same side, undergoing bilateral salpingectomy. In order to prevent repeated ectopic pregnancies in an IVF programme, a definitive surgical procedure, such as bilateral salpingectomy, should be considered in the first episode in patients referred for IVF because of tubal pathology.

Adult↗
PubMed1991

Superantigens: mechanism of T-cell stimulation and role in immune responses.

Superantigens combine with MHC class-II molecules to form the ligands that stimulate T cells via the V beta element of the T-cell receptor. Two groups of superantigens have been described so far: first, endogenous murine products that include the Mls determinants, and second, bacterial products such as the Staphylococcal enterotoxins. Here, we review studies that address the interactions between the foreign superantigens and MHC class-II molecules, the mechanism of T-cell stimulation, and the role that tolerance to self-superantigens plays in shaping the T-cell repertoire. We speculate on the possible evolutionary significance of superantigens.

Animals↗