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O Davis

Publications and source records attributed to O Davis.

7 recordsLinked to original sources
PubMed1992

Effects of alprazolam on pituitary-adrenal and catecholaminergic responses to metabolic stress in humans.

Concurrent effects of benzodiazepines on stress-induced activation of the three classical "stress" systems: pituitary-adrenal, adrenomedullary, and sympathoneural systems have not been extensively investigated in humans. In the present study, the effects of alprazolam (1.5 mg) on plasma levels of adrenocorticotropin hormone (ACTH), epinephrine, norepinephrine, dihydroxyphenylglycol (DHPG, the intraneuronal metabolite of norepinephrine), and mood states were examined in 10 healthy volunteers undergoing glucoprivic stress. Glucoprivic stress was induced by intravenous administration of the glucose analog, 2-deoxyglucose (2DG), at a dose (50 mg/kg) that impairs cellular glucose metabolism and produces a state comparable to hypoglycemia. Alprazolam and 2DG were administered in a double-blind, placebo-controlled manner. 2DG produced robust elevations in plasma ACTH and epinephrine levels, modest elevations in plasma norepinephrine levels, and decreases in plasma DHPG levels. Alprazolam significantly attenuated the 2DG-induced increases in plasma ACTH and epinephrine, but did not significantly effect plasma norepinephrine and DHPG. These data suggest that benzodiazepines attenuate metabolic stress-induced activation of the pituitary-adrenal and adrenomedullary systems but do not effect 2DG-related effects on peripheral sympathoneural function. The possible mechanisms involved are discussed.

Adrenocorticotropic Hormone↗
PubMed1992

Microsurgical fertilization procedures: the absence of stringent criteria for patient selection.

Subzonal sperm insertion and partial zona dissection were applied in 250 in vitro fertilization cycles in couples (n = 200) with abnormal semen analyses; 61 clinical pregnancies were established (24% per egg retrieval). Patients were selected without using minimal cutoff criteria. The study included patients with 0% normal sperm forms (strict criteria), no motile sperm (but some live cells), and sperm counts which could be assessed only after centrifugation. Patients were categorized into three subsets. Group A (n = 116 cycles) failed to fertilize in a previous cycle. Group B (n = 40) was excluded from IVF due to the severity of sperm profiles, such as a maximum of 2% normal forms. Group C (n = 94) constitutes those patients for whom a standard cycle could possibly result in failure. Monospermic fertilization rates were 18% (A), 19% (B), and 24% (C). The incidences of embryo replacement were 63% (A), 53% (B), and 69% (C). Rates of clinical pregnancy were 22% (A), 23% (B), and 28% (C). The presence of one, two, or three semen abnormalities did not correlate with the outcome of microsurgical fertilization. Twenty-two percent of patients with combined oligoasthenoteratozoospermia became pregnant. Moreover, ongoing pregnancies were established in instances with 0% normal sperm forms and no progressively motile spermatozoa. It is concluded that stringent cutoff criteria may not be necessary when both partial zona dissection and subzonal sperm insertion are performed efficiently.

Culture Techniques↗
PubMed1992

Improved pregnancy outcome with gonadotropin releasing hormone agonist (GnRH-a) stimulation is due to the improvement in oocyte quantity rather than quality.

The impact of gonadotropin releasing hormone agonist (GnRH-a) on the quality and quantity of oocytes harvested in in vitro fertilization-embryo transfer (IVF-ET) patients was studied by comparing the results for patients stimulated with gonadotropin alone and with gonadotropin plus GnRH-a. Adding GnRH-a significantly improved the viable pregnancies per transfer and reduced the spontaneous abortions, which seemed to improve oocyte quality. However, when oocyte quality was evaluated by the fertilization rate and the implantation and delivery rates per embryos transferred, there were no significant difference in the results, indicating that GnRH-a did not improve the oocyte quality. On the other hand, GnRH-a significantly increased the average number of oocytes harvested, fertilized, and transferred, and this increased number of oocytes transferred has been demonstrated to increase pregnancy and multiple-pregnancy rates. Multiple pregnancy with more embryos implanted would significantly reduce the abortion rate. Abortion rates decreased inversely to the number of embryos implanted. Our data strongly suggest that the efficacy of GnRH-a on IVF-ET patients was due more to the quantity increase than the quality of embryos transferred.

Embryo Implantation↗
PubMed1991

Late luteal estradiol patterns are a better prognosticator of pregnancy outcome than serial beta-human chorionic gonadotropin concentrations.

OBJECTIVE: Since the corpus luteum (CL) is known to play an important role in early pregnancy, its activity could possibly be a marker for pregnancy outcome. DESIGN: The late estradiol (E2) concentration in 48 viable pregnancies and 39 pregnancies which resulted in spontaneous abortions after in vitro fertilization and embryo transfer were used to evaluate such predictability. SETTING: All patients studied were of the Center for Reproductive Medicine at Cornell University Medical College. PATIENTS, PARTICIPANTS: Eighty-seven patients. INTERVENTIONS: None. MAIN OUTCOME MEASURE: Serum E2 and human chorionic gonadotropin (hCG) concentrations on day +11, +13, +15 (day +1 = day of ovum pick-up) were measured and studied. RESULTS: The late luteal CL activity after rescue had a positive correlation with the number and quality of the implanted embryos. Reduced CL activity was indicative of abortion. The late luteal E2 pattern when compared with hCG doubling time had a better abortion predictability (37.8% versus 63.9%, respectively). CONCLUSION: Corpus luteum activity demonstrated to be a better prognosticator of abortion than serial beta-hCG titers.

Chorionic Gonadotropin↗
PubMed1991

Microsurgical fertilization and teratozoospermia.

Semen parameters were correlated with the outcome of partial zona dissection (PZD) in 42 couples with male factor infertility. Although fertilization rates were reduced, 12% of the embryos implanted following replacement. Spermatozoa from teratozoospermic sperm populations were able to fuse with oocytes following zona penetration through the artificial gaps. PZD followed by insemination with less than 5% normal spermatozoa led to 20 embryos which, upon replacement, did not implant. Motility and sperm count were not clearly correlated with the outcome of PZD and are therefore less useful indicators for patient selection. Teratozoospermic patients who previously failed to fertilize were compared to a group of similar patients who had not attempted IVF before. Although fertilization was significantly improved in first-time patients, 41% of the patients whose spermatozoa were initially unable to fertilize had at least one embryo when PZD was performed. Several pregnancies were established in this group. Subzonal sperm insertion (SZI) and PZD were compared in 19 patients using sibling oocytes. A significant fraction of spermatozoa from infertile men were able to fuse with the oolemma when directly inserted into the perivitelline area. Using a sucrose solution to shrink the ooplasm, only 1% of the oocytes were damaged during SZI. Monospermic fertilization rates following PZD and SZI were 15 and 16%, respectively. Both micromanipulation methods were successful in most patients. However, in two small groups of patients, only one technique resulted in fertilization.

Female↗
PubMedDate not supplied

Pes anserinus transfer: an in vivo biomechanical analysis.

Fifteen patients who had undergone pes anserinus transfer for anteromedial rotary instability were tested for peak internal rotation torque at three stations of knee flexion. Despite the fact that all patients had apparently benefited from surgery, from a strict analytical standpoint the conclusions of this study do not support the contentions of previous authors, who suggest that pes anserinus transfer results in enhanced stability by increasing rotary effectiveness; nor do they demonstrate a consequential decrease in knee flexion power.

Adolescent↗