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Biomedical subjects

S Daya

Publications and source records attributed to S Daya.

At least 91 records · Page 5Linked to original sources
PubMed1993

Cycle characteristics and outcome in relation to ovarian response during in vitro fertilization.

PURPOSE: This retrospective analysis of 148 non-male factor couples sought to determine whether oocyte or embryonic quality was compromised by the magnitude of the ovarian response following clomiphene citrate/human menopausal gonadotropin stimulation for in vitro fertilization. METHODS: Increased oocyte numbers were associated with decreased fertilization rates (r = -0.36, P < 0.001) and estradiol/follicle ratios (r = -0.443, P < 0.001), although the quality of the resulting embryos was not affected. Despite reduced fertilization, higher oocyte numbers yielded additional healthy embryos (r = 0.70, P < 0.001) for immediate replacement or cryopreservation. Implantation rates did not differ among groups and no predictive variables were identified. RESULTS: These results suggest that endometrial receptivity and implantation were not adversely affected by increasing estradiol levels. The decline in oocyte quality associated with the retrieval of larger numbers of oocytes appeared to be offset by the availability of additional embryos for immediate replacement and cryopreservation.

Adult↗
PubMed1993

Accuracy of gestational age estimation by means of fetal crown-rump length measurement.

OBJECTIVE: The purpose of this study was to develop a gestational age table by means of crown-rump length measurements in the first trimester in pregnancies conceived through in vitro fertilization. STUDY DESIGN: Ninety-four infertile women with singleton intrauterine pregnancies resulting from in vitro fertilization underwent ultrasonographic examinations in the first trimester. The relationship between gestational age (calculated with the day of oocyte retrieval used as day 14) and the crown-rump length was explored with regression analysis. RESULTS: A quadratic model demonstrated the best fit to the data, indicating a curvilinear relationship between crown-rump length and gestational age. Estimates of gestational age with crown-rump length measurements between 40 and 60 mm were observed to be similar to published tables, but outside this range the tables either overestimate or underestimate the true gestational age. CONCLUSION: A more accurate equation for gestational age estimation with crown-rump length measurements in early pregnancy has been developed with in vitro fertilization pregnancy data.

Body Height↗
PubMed1993

A randomized trial of in vitro fertilization versus conventional treatment for infertility.

OBJECTIVE: To evaluate the effectiveness of IVF in couples with infertility. DESIGN: Two hundred forty-five consecutive couples with infertility were randomized to receive one cycle of IVF treatment (experimental group) or to wait for a period of 6 months before receiving IVF treatment, during which time other infertility treatments could have been undertaken (control group). SETTING: Patients were referred to the Fertility Clinic at Chedoke-McMaster Hospitals, a university-associated institution in Hamilton, Ontario, Canada, in which IVF has been offered to couples since 1984. PATIENTS: Couples with infertility (mean duration of 65 months) not corrected by conventional treatment. They came from all socioeconomic classes, and the costs of IVF treatment, except medication, were covered by the Ontario Health Insurance Plan. MAIN OUTCOME MEASURE: Pregnancy was confirmed by ultrasound documentation of a gestational sac or histologic examination of tissue. Outcomes included livebirth, spontaneous abortion, and ectopic pregnancy. The overall pregnancy rate (PR) and the interval-to-pregnancy duration were compared in each group. RESULTS: Univariate analysis demonstrated a significant beneficial effect of IVF treatment in patients with bilateral severe tubal disease. Although in other diagnostic categories the crude and cumulative PRs in the experimental group were higher than in the control group, the differences did not reach statistical significance. Among the early IVF group, those with endometriosis had significantly more pregnancies when compared with other diagnostic categories. Although IVF increases the likelihood of pregnancy by 40% with severe tubal disease, the overall 31% increase associated with IVF was not statistically significant. CONCLUSIONS: There was a significant difference in favor of treatment in patients with severe bilateral tubal disease. For couples with other causes of infertility, the confidence limits around the treatment effect included unity. To reject the null hypothesis of no treatment effect, a larger sample size or a meta-analysis to combine the results of similar trials is required.

Adult↗
PubMed1992

Excimer laser photorefractive keratectomy in high myopia. A multicenter study.

Excimer photorefractive keratectomy was performed at three centers on 16 highly myopic eyes (8 diopters [D] or more) and followed up for 6 months. Ablation depths ranged from 137 to 230 microns. The preoperative spherical equivalent of myopia ranged from -8.62 D to -14.50 D (mean +/- SD, -11.57 +/- 1.62 D). Six months after surgery, the mean refraction (spherical equivalent) was -0.90 +/- 2.13 D. Eleven of 16 eyes achieved refractions within 2 D of that attempted. All eight patients at one site were treated with a maximum-beam diameter of 6.0 mm and were corrected to within 2 D of that attempted, and all were 20/40 or better uncorrected. Three of eight eyes at the other two sites were treated with a 5.5- or 5.6-mm maximum-beam diameter, which achieved corrections within 2 D of that attempted. The epithelium healed within 3 to 4 days, and there were no erosions. Mild subepithelial reticular haze, similar to that seen with excimer photorefractive keratectomy for lower myopia, was seen in all patients, with two patients experiencing more significant corneal haze. This peaked at 3 to 6 weeks and then gradually diminished. All but two patients had a return of their best corrected preoperative visual acuity to within one Snellen line at 6 months. This preliminary study shows excimer photorefractive keratectomy to be a promising surgical treatment for patients with higher myopia.

Adult↗
PubMed1992

The routine use of gonadotropin-releasing hormone agonists prior to in vitro fertilization and gamete intrafallopian transfer: a meta-analysis of randomized controlled trials.

OBJECTIVE: To assess the efficacy of gonadotropin-releasing hormone agonists (GnRH-a) used in ovulation induction for in vitro fertilization and embryo transfer (IVF-ET) and gamete intrafallopian transfer (GIFT). DESIGN: Meta-analysis of 10 trials comparing treatment cycle outcomes after GnRH-a (n = 914) with other ovulation induction protocols (n = 722) and 7 trials comparing outcomes after short flare-up (n = 368) with longer suppression (n = 476) GnRH-a protocols. MAIN OUTCOME MEASURES: The outcome of primary interest was clinical pregnancy rate (PR) per treatment cycle commenced. Data describing the amount of gonadotropin used, cycle cancellation rate, clinical pregnancy per ET, and multiple pregnancy and abortion rates were also analyzed. RESULTS: Clinical PR per cycle commenced was significantly improved after GnRH-a use for IVF (common odds ratio [OR] 1.80, 95% confidence interval [CI] 1.33 to 2.44) and GIFT (common OR 2.37, 95% CI 1.24 to 4.51). Clinical PR per embryo transfer was also significantly improved with GnRH-a use (common OR 1.40, 95% CI 1.01 to 1.95). Cycle cancellation was decreased (common OR 0.33, 95% CI 0.25 to 0.44), whereas spontaneous abortion rate was similar with and without GnRH-a use. Cycle cancellation and PRs after short flare-up and longer suppression protocols were similar between groups. CONCLUSIONS: This meta-analysis supports the routine use of GnRH-a for IVF and GIFT. Further research is needed, however, to assess the potential for increased rates of multiple pregnancy and ovarian hyperstimulation syndrome, which may be associated with this treatment.

Abortion, Spontaneous↗
PubMed1992

Adenosine 5'-monophosphate enhances the dark and isoproterenol-induced rise in rat pineal N-acetyltransferase activity.

Exposure of rats to light during darkness or blockade of the pineal beta-adrenoceptor in stimulated pineal glands results in a rapid fall in pineal N-acetyltransferase (NAT) activity. Maintenance of a high level of NAT activity requires continuous stimulation of the pineal beta-adrenoceptors. It is not known what factors in the pinealocyte are responsible for this rapid inactivation of NAT activity. In the present study we have attempted to investigate a possible regulatory role of 5'-AMP on pineal NAT activity. The results show that 5'-AMP further enhances dark-induced as well as isoproterenol-induced NAT activity by approximately 3-fold but does not alter unstimulated daytime NAT activity. Theophylline, an inhibitor of 5'-AMP synthesis, when administered early in the dark phase, caused a rise in pineal cAMP with a concomitant fall in pineal NAT activity. These findings indicate that 5'-AMP could play a role in the activation of pineal NAT. The possibility that the rapid inactivation of NAT is due to a rapid removal of 5'-AMP by, for example, phosphorylation, remains to be investigated.

Adenosine Monophosphate↗
PubMed1992

In vitro fertilisation in immunological infertility.

Fertilisation occurs through a complex and orderly sequence of changes in both the oocyte and the spermatozoon. Although mechanisms have evolved to protect spermatozoa from recognition by the immune system, there is evidence that a breakdown in protection can occur resulting in homologous or heterologous antisperm antibodies which can immobilise or agglutinate spermatozoa leading to infertility. Antisperm antibodies may affect the reproductive process by interfering with sperm survival and motility and sperm transport through cervical mucus. Fertilisation is also affected, and those oocytes that do fertilise go on to develop poorly. Antisperm antibodies appear to inhibit sperm attachment to and penetration of the zona pellucida. Immune recognition of sperm antigens, which are normally present on the surface of the embryo once fertilisation has occurred, may lead to abortion after implantation. Despite the adverse effects of antisperm antibodies on fertilisation and embryo development, acceptable pregnancy rates can be achieved with assisted reproductive techniques using sperm-washing to remove antibody and using a protein source other than female serum. Further study is necessary to understand the mechanism of immunological infertility and to evaluate newer techniques using micromanipulation of gametes to achieve fertilisation.

Antibodies↗
PubMed1992

Isolation and purification of mitochondrial monoamine oxidase B from bovine liver by chromatofocusing.

Mitochondrial monoamine oxidase B has been isolated and purified from bovine liver. The isolation procedure involves (a) a series of purification steps including isolation of the mitochondria, extraction with non-ionic detergents and chromatofocusing; (b) a novel fluorimetric titration assay. The purified enzyme is isolated following a 8.8 fold purification with an overall yield of 12% and a specific activity of 3460 nM.g-1. A comparison is made with other established procedures. Ion exchange chromatography on DEAE-Cellulose produced a 6.8 fold purification, 6.2% yield and 2383.3 nM.g-1 specific activity while with affinity chromatography on Blue Sepharose CL-6B gave a 3 fold purification, 4.1% yield and a specific activity of 1152.7 nM.g-1.

Animals↗
PubMed1991

Early pregnancy assessment with transvaginal ultrasound scanning.

OBJECTIVE: To establish normal parameters in early pregnancy through transvaginal ultrasonography so that gestational age can be determined and to correlate the sonographic findings with serum human chorionic gonadotropin (hCG) levels calibrated against the first international reference preparation standard. SETTING: Infertility clinic. PATIENTS: Thirty-five women with normal intrauterine pregnancy. INTERVENTIONS: Serial measurement of the serum hCG level and the diameter of the gestational sac through transvaginal ultrasonography. MAIN RESULTS: The gestational sac could not be visualized when the hCG level was less than 1100 IU/L. The average growth rate of the sac was 0.9 mm/d. The threshold values for sac diameter, serum hCG level and gestational age below which the yolk sac was not visible were 3.7 mm, 1900 IU/L and 36 days respectively; the corresponding values above which the yolk sac was always visible were 6.7 mm, 5800 IU/L and 40 days. The threshold values below which cardiac activity was not visible were 8.3 mm, 9200 IU/L and 41 days respectively, and the corresponding values above which cardiac activity was always visible were 14.0 mm, 24,000 IU/L and 46 days. The mean gestational ages and the 95% confidence and prediction intervals were tabulated so that measurement of the gestational sac diameter could be used to estimate gestational age early in normal pregnancy. CONCLUSIONS: Transvaginal ultrasonography enables detection of an intrauterine sac and reliable estimation of gestational age on the basis of sac dimensions before an embryo can be seen.

Chorionic Gonadotropin↗
PubMed1991

The detection of spermine and spermidine in human in vitro fertilization supernatants and their relation to early embryo-associated suppressor activity.

Suppressor activity in human IVF supernatants is dependent on the activity of monoamine oxidase present in nonheat-treated FBS and is therefore likely a polyamine. Pooled suppressive growth phase IVF supernatants were concentrated and subjected to HPLC fractionation. The inhibitory peak in the 1,000 to 2,000 d range was neutralized by antibody reactive with spermine and spermidine, and the presence of both polyamines was confirmed by TLC and by ELISA. These data suggest that IVF supernatant polyamines (spermine and spermidine) are responsible for the early embryo-associated suppressor activity correlating with pregnancy success.

Chromatography, High Pressure Liquid↗