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Biomedical subjects

G A Hill

Publications and source records attributed to G A Hill.

At least 19 recordsLinked to original sources
PubMed2001

Male partner screening before in vitro fertilization: preselecting patients who require intracytoplasmic sperm injection with the sperm penetration assay.

OBJECTIVES: To determine the diagnostic accuracy of the sperm penetration assay (SPA) and standard semen parameters for subsequent fertilization in in vitro fertilization-embryo transfer (IVF-ET). DESIGN: Prospective study. SETTING: Andrology Laboratory, and university research laboratory. PATIENTS: Two hundred sixteen couples undergoing male-partner screening before IVF-ET (265 cycles). INTERVENTION(S): Male-partner screening (semen analyses [SA] and SPA), standard IVF-ET procedures, follow-up of fertilization in IVF-ET. MAIN OUTCOME MEASURE(S): Diagnostic accuracy of SA and SPA for prediction of fertilization in IVF-ET. RESULT(S): The SPA predicted IVF fertilization with high negative (84%) and positive (98%) predictive rates, and correct prediction in 88% of cycles. In contrast, sperm concentration, motility, morphology, and complete SA showed poor diagnostic accuracy, with correct prediction of IVF fertilization in 64%, 65%, 45%, and 68% of cycles, respectively. CONCLUSION(S): Very low sperm concentration and/or motility were good predictors of poor IVF fertilization, however, low to normal semen parameters were not predictive of successful IVF fertilization. The SPA is a useful screening tool that predicts IVF fertilization with high diagnostic accuracy. The SPA may be useful to discriminate between those couples with a high probability of normal fertilization in IVF and those with a low probability of normal fertilization that may benefit from assisted fertilization by intracytoplasmic sperm injection (ICSI).

Animals↗
PubMed2001

How to be paid for what you do: know the process.

Current Procedural Terminology and ICD-9-CM codes are tools used in clinical medicine to define work done and diagnoses or conditions for which the work was performed. It is important that all physicians become knowledgeable about these schemes to describe services provided correctly and accurately.

American Medical Association↗
PubMed2000

Femoral nailing for metastatic disease of the femur: a comparison of reamed and unreamed femoral nailing.

A total of 73 consecutive intramedullary femoral nails were inserted for metastatic disease of the femur; 43 were reamed and 30 were solid nails. The two groups were similar with regards to age, type of primary tumour, anatomical site, acute or 'impending' fracture and postoperative survival. The 'solid' nail offers a satisfactory alternative form of stabilisation for metastatic disease of the femur with rates of implant failure which are comparable with the reamed nail. In this series bilateral nailing was not associated with any increase in mortality. Contrary to other reports, imposing a delay in patients with pain and a short life expectancy seems unjustified. The use of the 'solid' femoral nail does not prevent sudden death due to massive fat embolism.

Adolescent↗
PubMed1999

Quantitative and qualitative analysis of type III antifreeze protein structure and function.

Some cold water marine fishes avoid cellular damage because of freezing by expressing antifreeze proteins (AFPs) that bind to ice and inhibit its growth; one such protein is the globular type III AFP from eel pout. Despite several studies, the mechanism of ice binding remains unclear because of the difficulty in modeling the AFP-ice interaction. To further explore the mechanism, we have determined the x-ray crystallographic structure of 10 type III AFP mutants and combined that information with 7 previously determined structures to mainly analyze specific AFP-ice interactions such as hydrogen bonds. Quantitative assessment of binding was performed using a neural network with properties of the structure as input and predicted antifreeze activity as output. Using the cross-validation method, a correlation coefficient of 0.60 was obtained between measured and predicted activity, indicating successful learning and good predictive power. A large loss in the predictive power of the neural network occurred after properties related to the hydrophobic surface were left out, suggesting that van der Waal's interactions make a significant contribution to ice binding. By combining the analysis of the neural network with antifreeze activity and x-ray crystallographic structures of the mutants, we extend the existing ice-binding model to a two-step process: 1) probing of the surface for the correct ice-binding plane by hydrogen-bonding side chains and 2) attractive van der Waal's interactions between the other residues of the ice-binding surface and the ice, which increases the strength of the protein-ice interaction.

Antifreeze Proteins↗
PubMed1998

Permanent impairment of embryo development by hydrosalpinges.

Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy outcome for in-vitro fertilization (IVF) and improvement following surgical treatment. We compared the effect of hydrosalpinx on pregnancy outcome in 286 patients having 348 IVF cycles and followed the development of untransferred embryos for 7 days to determine if hydrosalpinges affect oocyte quality or embryo development. The delivery rate per retrieval was significantly lower for patients with hydrosalpinx, but was restored by surgical treatment to that of patients without hydrosalpinx. However, the implantation rate per embryo transferred and normal blastulation of untransferred embryos, which were significantly decreased in patients with hydrosalpinx, and growth arrest and degeneration of untransferred embryos, which were significantly increased compared to patients without hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We conclude that surgical treatment of hydrosalpinges decreases early pregnancy loss and improves pregnancy outcome, possibly by diminishing reversible deleterious effects exerted on the endometrium. As we have seen in our laboratory, hydrosalpinges may have a permanent negative influence on ovarian function, follicular development and oocyte quality since implantation of transferred embryos and normal blastulation of untransferred embryos remain low, and in-vitro growth arrest and degeneration remain high despite surgical treatment of hydrosalpinges.

Abortion, Spontaneous↗
PubMed1998

Survey results on behavioral health promotion in managed primary health care.

Casual observation suggests that many managed health care providers support health promotion and preventive care, including efforts addressing such behavioral health objectives as reduced alcohol use during pregnancy, prevention of family violence, and improved parenting. Respondents from roughly 40 percent of 200 health maintenance organizations (HMOs) selected for a 1995-1996 survey reported some type of health promotion activities with potential behavioral health impact. These 80 HMOs were found to be divided among eight distinct models of interaction between behavioral health promotion and managed primary health care.

Community Health Services↗
PubMed1998

Critical mandates: prevention and health promotion.

Health maintenance organizations are supposed to maintain health, not just contain the cost of treating illness. Prevention and health promotion are critical mandates for managed care organizations, including managed behavioral health plans. More often than not, however, health plans have neglected to include prevention and behavioral health promotion services within their spectrum of covered benefits. In this article, the authors explain why there is a growing trend toward including coverage for prevention and promotion services in managed behavioral health plans, including the financial advantages and cost-containment opportunities that result. The article also illustrates several simple and straightforward models for structuring prevention benefits, managing the utilization and quality of prevention services, and including community-based preventive services organizations in provider networks.

Contract Services↗
PubMed1997

Assessment of methodological practices in the evaluation of alcohol and other drug (AOD) abuse prevention.

No authoritative consensus has been achieved on which substance abuse prevention activities are effective for given populations. One response to concern about "what works" took the form of a National Structured Evaluation (NSE), mandated by the Anti-Drug Abuse Act of 1988. The present paper describes the NSE's pivotal task of determining whether evaluation methodologies applied to substance abuse prevention were adequate to produce credible findings. The lessons learned from this evaluation experience, in turn, offer guidance on changes that must be made in the application of evaluation methodology prior to a conclusive demonstration of the value of prevention efforts.

Alcoholism↗
PubMed1996

Cometabolic degradation of 4-chlorophenol by Alcaligenes eutrophus.

Alcaligenes eutrophus was grown in batch cultures using either phenol as a sole substrate or mixtures of phenol and 4-chlorophenol. Phenol was found to be the sole source for carbon and energy while 4-chlorophenol was utilized only as a cometabolite. Maximum growth rates on phenol reached only 0.26 h-1, significantly below the growth rates reported earlier with Pseudomonas putida. The cometabolite was found to decrease biomass yield and increase lag time before logarithmic growth occurred. Both phenol and 4-chlorophenol were found to inhibit the growth rate linearly with maximum concentrations of 1080 ppm and 69 ppm respectively, beyond which no growth occurred. The best-fit parameters are incorporated into a simple, dynamic (i.e. time-varying) model capable of predicting all the batch growth conditions presented here. It is shown that P. putida is capable of faster bioremediation when phenol is the sole carbon source or for mixed substrates with low concentrations of the cometabolite, but for high concentrations of 4-chlorophenol, A. eutrophus becomes superior because of the long lag times that occur in the Pseudomonas species.

Alcaligenes↗
PubMed1996

Autologous granulosa cell coculture demonstrates zygote suppression of granulosa cell steroidogenesis.

OBJECTIVE: To determine if embryos can modulate steroid hormone production by luteinized granulosa cells. DESIGN: Granulosa cells obtained from follicular aspirates were cultured alone or in the presence of a two-pronuclear zygote. The production of E2 and P by these cultures was evaluated by RIA. SETTING: In Vitro Fertilization Unit in an academic research environment. PATIENTS: Sixteen women undergoing IVF. INTERVENTIONS: Standard IVF-ET treatment cycle using leuprolide acetate for pituitary desensitization before hMG or urofollitropin for ovarian stimulation. MAIN OUTCOME MEASURES: Estradiol and P concentration in culture media of luteinized granulosa cells alone or granulosa cells cocultured with a two-pronuclear embryo. RESULTS: Both E2 and P production by luteinized granulosa cells was reduced when cultured in the presence of an embryo. CONCLUSIONS: Human embryos secrete a factor that regulates granulosa cell steroidogenesis.

Adult↗
PubMed1995

Granulosa cell co-culture enhances human embryo development and pregnancy rate following in-vitro fertilization.

A preliminary study and related clinical trial were performed to evaluate the effects of granulosa-lutein cell co-culture on human embryo development and pregnancy rates for in-vitro fertilization (IVF). In the study, sibling two-pronuclear zygotes were randomly allocated to culture with (co-culture) or without (control) autologous granulosa-lutein cells. After 24 h, embryos were examined for blastomere number and degree of fragmentation. Co-culture had no effect on the average number of blastomeres per embryo at 24 h; however, fragmentation was significantly decreased in co-cultured embryos (0.7 +/- 0.1) compared with controls (1.3 +/- 0.2; P < 0.05). In the subsequent clinical trial, all two-pronuclear zygotes were co-cultured for 48 h prior to embryo transfer. The live birth rate per embryo transfer was 43.4% with an implantation rate per embryo of 17.6%. Of the untransferred embryos, 68% developed to the blastocyst stage and were cryopreserved. We conclude that the simple system of autologous granulosa-lutein cell co-culture improves embryo development, implantation and subsequent pregnancy rates for IVF.

Blastomeres↗
PubMed1994

A rabbit model of free bladder mucosal grafting in a damaged urethral bed.

Proximal and distal penile-urethral stomas were created in the rabbit and 1 to 3 months later a free bladder mucosal graft was placed in the damaged urethral bed. The graft adhered to a rapidly proliferating submucosa with active regeneration by post-transplantation day 5. All grafts were adherent and viable by days 10 to 14, during which time sham operated animals that had been stented only showed a degree of epithelial regeneration that was of variable quality and without submucosal proliferation. The graft may stimulate the subepithelial layer, and the most viable bladder mucosa may be associated with the most actively proliferating subepithelial layer, which is also the area of greatest neovascularity. Further studies may explain the apparent paradox of how a free bladder mucosal graft survives in a poorly vascularized, scarred urethral bed.

Animals↗
PubMed1993

The modified pyramid hypospadias procedure: repair of megameatus and deep glanular groove variants.

We present our experience with the pyramid hypospadias repair in 37 patients with distal or subcoronal hypospadias. We also describe a significant modification (in the 7 most recent patients) of Duckett's original procedure that minimizes the risk of ventral fistula formation. This modification involves the creation of a vascularized second-layer tissue flap. We incorporated the modified pyramid hypospadias repair into the general surgical approach to subcoronal hypospadias. Our operative approach permits the delayed selection of either a perimeatal-based flap, preputial flap or a modified pyramid type repair after release of the shaft skin. In 35 patients the repair achieved excellent results, while only 2 had urethrocutaneous fistulas. No patient who underwent the modified repair suffered fistula formation. Our surgical technique is applicable to a number of variants of subcoronal hypospadias and maximizes repair options.

Humans↗
PubMed1993

Coculture of mouse embryos with cells isolated from the human ovarian follicle, oviduct, and uterine endometrium.

OBJECTIVE: To examine the specificity of somatic cell support by comparing embryonic development during long-term in vitro coculture with feeder cells derived from the human ovarian follicle, oviduct, and endometrium. DESIGN: Comparative study of murine embryo development and degeneration during 6 days of in vitro coculture. RESULTS: All feeder-cell cultures were beneficial to embryonic development and viability. Few differences were observed between feeder cell types (epithelial or fibroblastic) or cell origin (ovarian follicle, oviductal, or endometrial). Embryos developed to the eight-cell stage in 24 hours whether in coculture (83.6% to 100%) or in media alone (85.2%); however, further development in media alone decreased compared with coculture (15.6% versus 63.4% to 87.7%, plating) and embryo degeneration increased (67.9% versus 5.5% to 19.4%) after 6 days. CONCLUSIONS: [1] Coculture of embryos with human reproductive tract cells is beneficial to embryonic development and viability. [2] Human somatic cell support of murine embryos during long-term in vitro coculture is not tissue specific nor dependent on cell type.

Adult↗