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Biomedical subjects

P Quinn

Publications and source records attributed to P Quinn.

At least 19 recordsLinked to original sources
PubMed1992

Two separate pools of sphingomyelin in BHK cells.

In BHK cells labelled to equilibrium with [3H]choline and treated with sphingomyelinase the surface pool of sphingomyelin is degraded very rapidly (half-time 10 min) but the internal pool of sphingomyelin which accounts for about 30% of the total is only degraded slowly (half-time about 80 h) showing that the internal pool does not normally reach the surface. In [3H]choline incorporation experiments the internal pool begins to accumulate radioactivity at about the same time as phosphatidylcholine (30 min) but label does not enter the surface pool of sphingomyelin for a further 90 min. The internal and external pools reach the same specific activity only after about 20 h. Pulse-chase analysis with [3H]choline shows that radioactivity in each pool of sphingomyelin continues to increase when the specific radioactivity of phosphatidylcholine is decreasing, consistent with both pools being synthesised from a phosphatidylcholine precursor. The results suggest that sphingomyelin in BHK cells is present not only in the plasma membrane but also in a more rapidly labelling pool which does not mix with the surface pool.

Animals↗
PubMed1992

Isolation of plasma membrane exovesicles from BHK cells using merocyanine 540.

Treatment of cultured BHK cells with merocyanine 540 caused the non-lytic release of vesicular material having the phospholipid composition characteristic of plasma membrane. The protein composition of the vesicles closely resembled that of the soluble fraction of the cell, as expected for exovesicles budding from the cell surface. Vesicles prepared from cells surface-iodinated with 125I contained no obvious iodinated membrane polypeptides, suggesting that no major proteins in the plasma membrane of the BHK cell are free to diffuse with lipids. The procedure described should represent a general method, applicable to a wide range of cell types, for isolating plasma membrane vesicles.

Cell Membrane↗
PubMed1991

Effects of feeder cells on the X-ray sensitivity of human colon cancer cells.

The survival responses to 250 kVp X-irradiation of 20 different exponentially growing human colon tumor lines have been described using the linear-quadratic equation of cell survival. Because some of these tumor lines (6/20) showed statistically significant increases in colony forming efficiency (CFE) when feeder cells (FCs) were added (10(5) FCs/60 mm dish), radiation survival parameters were determined for all 20 tumor lines with and without added feeder cells. In neither FC independent nor FC dependent lines did addition of FCs significantly affect any of the derived radiation survival parameters, including the alpha and beta inactivation constants, the mean inactivation dose (D, Gy), or the surviving fraction of cells at 2 Gy (S2). The average alpha, beta, and S2 values for these 20 human colon cancer cell lines with added feeder cells were: 0.281 Gy-1, 0.0711 Gy-2, and 0.443. A cumulative frequency distribution plot of the mean inactivation dose (D) which includes other published radiobiological data on human colon cancer cell lines (N = 26) indicates that the D50 value is 2.17 Gy.

Cell Line↗
PubMed1991

In vitro radiation survival parameters of human colon tumor cells.

As part of an ongoing research program in the biology of human colon cancer cells, a database is being generated on the radiation responses of established lines in vitro. In this report, data are summarized on the graded single dose clonogenic survival responses to graded single doses of 250 kVp X rays of 16 exponentially growing lines. These data were analyzed using the linear quadratic (LQ) formalism for X ray inactivation; the 95% confidence limits on the colony forming efficiencies (CFEs), the alpha and beta parameters from the LQ equation, the surviving percentage at 2 Gy, and the mean inactivation dose (D, Gy) are listed herein. The average D from these 16 colon tumor lines was 2.35 Gy (95% confidence limits 2.10-2.60 Gy), which indicates that these tumor cells are of equal radioresistance to melanoma or head and neck cells, with only glioblastoma cells being of greater radioresistance.

Carcinoembryonic Antigen↗
PubMed1990

Tris reversibly inhibits secretion of albumin and alpha-1-antitrypsin at different sites.

We have investigated the effect of the weak base Tris on the processing and secretion of albumin and alpha-1 antitrypsin by hepatocytes in culture. We show that the secretion of both proteins is 90% inhibited by 30 mM Tris. The post-synthetic processing of both proteins is inhibited to the same extent. These effects are completely reversible. Cell fractionation indicates that albumin accumulates in the Golgi, whereas alpha-1 antitrypsin fails to leave the endoplasmic reticulum.

Albumins↗
PubMed1990

Male germ cell specific sulfogalactoglycerolipid is recognized and degraded by mycoplasmas associated with male infertility.

Sulfogalactosylglycerolipid (SGG) is the major mammalian male germ cell glycolipid and has been implicated in sperm/egg binding. Mycoplasma pulmonis, a species of Mollicutes, is associated with male infertility in rodents. Purified SGG incubated in the presence of M. pulmonis was enzymatically degraded by both desulfation and deacylation. Desulfation occurred primarily at alkaline pH, and deacylation also increased with increased pH, indicating that these represent novel enzymatic activities. Digestion was facilitated, but not dependent on, the presence of detergent. Rat spermatozoa exposed to M. pulmonis showed a reduction in SGG content which was particularly marked for cauda (mature) spermatozoa. With the aid of tlc overlay binding procedure, intact M. pulmonis were found to bind specifically to sulfated glycolipids and thus SGG may provide the cell membrane receptor for this organism. The topology of mycoplasma binding to rat sperm was consistent with the known topology of sperm SGG. The reduced binding (and subsequent digestion) of caput spermatozoan SGG correlates with the membrane colocalization of SGG and its endogenous binding protein at this stage. Separation of SGG and its binding protein during epididymal sperm maturation appears to facilitate M. pulmonis binding to and digestion of cauda sperm SGG. The binding and degradation of the sperm SGG by M. pulmonis may play a role in the induction of infertility which follows infection with these organisms by interfering in sperm/egg receptor recognition.

Animals↗
PubMed1990

Effect of human follicular fluids from pregnant and nonpregnant patients on the development of mouse zygotes in vitro.

Mouse zygotes were cultured in medium containing follicular fluid from patients who had follicles containing oocytes which fertilized, did not fertilize, or were atretic and who did or did not become pregnant after in vitro fertilization and embryo replacement. The inhibitory effect was least with the follicular fluid from follicles in which the oocytes subsequently fertilized, greater when the oocytes did not fertilize, and most inhibitory when the follicle contained an atretic oocyte. More mouse zygotes developed to blastocysts when culture medium was supplemented with follicular fluid from patients who became pregnant compared to those who did not become pregnant. There was no difference in pregnancy outcome when an oocyte which subsequently fertilized was obtained from the follicle. These results indicate that follicles contain a substance(s) which inhibits mouse zygote development in vitro and that the inhibitory activity is related to the developmental potential of the oocyte in the follicle.

Adolescent↗
PubMed1990

Suboptimal laboratory conditions can affect pregnancy outcome after embryo transfer on day 1 or 2 after insemination in vitro.

We have demonstrated that the replacement of pronuclear stage human embryos on the day after insemination in IVF-ET results in a pregnancy rate as good as, if not better than, the rate after ET on day 2. The pregnancy rate appears to be influenced by the culture environment used for the gametes. We would recommend that ET be undertaken as soon as possible after insemination on day 1 so that if suboptimal culture conditions are present, they do not have sufficient time to affect the viability of the embryos and reduce the subsequent chance of pregnancy after replacement. If culture conditions have been optimized there is no difference in pregnancy rate after embryo transfer on day 1 or day 2 and one can then replace embryos on either day and expect the pregnancy rate obtained in either case to be similar.

Embryo Transfer↗
PubMed1990

Grouping students for instruction: effects of learning style on achievement and attitudes.

The present study examined the effects of matching and mismatching American middle-school students with a preference for learning alone or learning with peers with selected instructional treatments in order to determine the impact upon their attitudes and achievement in social studies. Analysis revealed that the learning-alone preference performed significantly better in the learning-alone condition and that the learning-with-peers preference performed significantly better in the learning-with-peers condition. However, no-preference students also performed significantly better in the learning-alone condition than with peers. In addition, data revealed that the learning-alone and the learning-with-peers students had significantly more positive attitudes when matched with their preferred learning style; the nopreference students had more positive attitudes in the learning-alone condition.

Achievement↗
PubMed1990

Between-lot variability in chromatographic and biochemical properties of hMG.

Ten lots of dissociated hMG were characterized by reverse-phase gradient high-performance liquid chromatography. Areas of 12 discrete peaks were directly related to dosages of hMG injected. The lots were further analysed for immunoactive-FSH (41.6-106.2 IU/ampule), immunoactive-LH (11.0-20.4 IU/ampule), bioactive-LH (2.7-17.1 IU/ampule) and bioactive-hMG (149-298 pg E2/mIU immunoactive-FSH/ml). Relationships between integrated areas of the HPLC peaks and biochemical properties of the hMG lots were analysed by stepwise multiple linear regression. Between-lot differences in immunoactive-LH and immunoactive-FSH were related to HPLC peak areas (p less than 0.05); differences in bioactive-LH were not. Areas of 8 peaks were related to differences in bioactive-hMG activity, facilitating close approximation of bioactive-hMG from the derived multi-linear model (p less than 0.001). Rapid characterization of hMG by HPLC is of relevance as recent reports have shown that ovarian responses and pregnancy outcomes of patients are related to the immunoactive and bioactive gonadotropin content of hMG preparations used to induce multiple folliculogenesis before oocyte aspiration, in vitro fertilization, and embryo replacement.

Animals↗
PubMed1989

Tailoring a commercial radioimmunoassay to the range of levels of progesterone occurring in human serum during controlled ovarian hyperstimulation and following embryo/gamete transfer.

While the Pantex direct P radioimmunoassay is used widely in programs of assisted conception, its sensitivity and range do not encompass the wide range of levels of P in serum of many patients during COH and through the first trimester of pregnancy. The present communication details minor modifications to the proprietary Pantex assay which accommodate these requirements. The nature of the changes does not compromise the performance characteristics or simplicity of the original assay and facilitates precise, accurate, and rapid measurement of serum P between 0.05 and 1280 ng/ml.

Embryo Transfer↗
PubMed1989

Responses of patients to different lots of human menopausal gonadotropins during controlled ovarian hyperstimulation.

Responses of patients treated with different lots of human menopausal gonadotropin (hMG) during controlled ovarian hyperstimulation were analyzed. Levels of luteinizing hormone (LH) in serum varied between groups of patients treated with different hMG lots, serum follicle-stimulating hormone (FSH) levels did not differ. In the analysis of levels of estradiol (E2) in serum of patients pretreated with leuprolide acetate (gonadotropin-releasing hormone analog; GnRH-a), there was an interaction between hMG lot and day of stimulation. E2 levels/follicle also diverged between hMG batches as ovum pick-up approached. Within the groups of patients pretreated with GnRH-a, serum FSH/LH ratios varied between 5 and 20, with a batch x day interaction. Ongoing pregnancy rates in the hMG-treatment groups ranged between 0/24 and 7/33 (21%).

Estradiol↗
PubMed1989

Development of mouse embryos cryopreserved by an ultra-rapid method of freezing.

High concentrations of cryoprotectant combined with sucrose were utilized in an ultra-rapid freezing protocol for mouse preimplantation embryos. Dimethylsulphoxide (DMSO, 1.5 or 3.5 M) or propanediol (PROH, 1.5 or 3.0 M) combined with 0.25 M sucrose were used as freezing solutions. One-, 2- or 8-cell embryos were placed directly into these solutions at room temperature, loaded into straws and plunged into liquid nitrogen within 2-3 min. The straws were rapidly thawed and the embryos expelled into the solution in which they were frozen for 10 min. The cryoprotectants were then removed by single- or multi-step dilution. Survival and development of the embryos in vitro and in vivo were assessed. DMSO (1.5 M) and both concentrations of PROH were totally inadequate as a cryoprotectant in this freezing protocol. A concentration of 3.5 M DMSO gave high survival and development rates when a multi-step dilution procedure was used, but not with a single-step dilution. One-cell embryos gave 71% survival, 35% in-vitro development and 10% in-vivo viability; 2-cell embryos showed 87% survival, 77% in-vitro development and 66% in-vivo viability; and 8-cell embryos showed 97% survival, 87% in-vitro development and 62% in-vivo viability. The results for the 2- and 8-cell stages compared favourably with non-frozen controls, which had 71% in-vivo viability. This method of cryopreservation is therefore fast and viable.

Animals↗
PubMed1989

Gonadotropin and estradiol levels during ovarian stimulation in women treated with leuprolide acetate.

Levels of FSH, LH, and estradiol (E2) were measured in the serum of 209 gonadotropin-releasing hormone analogue-treated women and in 202 control subjects during the final 5 days of ovarian stimulation in our in vitro fertilization program. Levels of FSH and E2 in serum of gonadotropin-releasing hormone analogue-treated subjects significantly exceeded control values during the sampling period, whereas LH levels were significantly lower. Concentrations of E2 in serum of gonadotropin-releasing hormone analogue-treated and control subjects were similar when corrected for differences in numbers of follicles aspirated at oocyte retrieval (mean of 8.9 and 7.2 follicles per subject, respectively). Pregnancy rates by diagnostic ultrasound were 18 and 11%, respectively, a statistically significant difference.

Estradiol↗