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Biomedical subjects

P W Shaw

Publications and source records attributed to P W Shaw.

14 recordsLinked to original sources
PubMed2000

Genetic population structure indicates sympatric speciation of Lake Malawi pelagic cichlids.

Allopatric processes of speciation have routinely been presented to explain the extraordinary radiation of the East African Great Lakes cichlid fish species flocks. The 21 or more species of pelagic cichlids within the Lake Malawi flock appear to have lake-wide distributions that challenge such a concept. Data from six microsatellite DNA loci indicate single, panmictic populations across the lake of three Diplotaxodon species. Levels of variability at these loci suggest that populations have been large and stable. Mitochondrial DNA sequence data (872 bp of control region + 981 bp of the NADH-2) from 90 species, representing all major clades within the Lake Malawi flock, indicate reciprocal monophyly of the pelagic clade. We suggest that these data support a hypothesis that speciation in sympatry is more plausible (and widespread) within the cichlid species flocks than previously thought.

Animals↗
PubMed1999

Microsatellite DNA analysis of population structure in Atlantic herring (Clupea harengus), with direct comparison to allozyme and mtDNA RFLP analyses.

Previous attempts to test for small-scale stock structuring within Atlantic herring (Clupea harengus L.) with molecular markers have been hampered by uninformative levels of genetic variation. Here we report the first application of microsatellite DNA markers to investigate population subdivision in Atlantic herring from Norwegian waters and the Barents Sea, and also examine microsatellite differentiation between C. harengus and Pacific herring (C. pallasi). Results from four microsatellite loci indicate high, and informative, variation compared to molecular markers used previously: number of alleles per locus=18-41; mean expected heterozygosity within samples=0.90-0.93. Significant genetic differences were detected between almost all samples representing postulated Icelandic summer-spawner, Norwegian spring-spawner and Norwegian fjord stocks, using Fisher's exact test, FST and RST values. Levels of allele frequency differentiation between Atlantic and Pacific herring overlapped the range seen among Atlantic herring samples, indicating that microsatellites are poor indicators of the degree of species differentiation. Comparison with allozyme and mitochondrial DNA restriction fragment length polymorphism (RFLP) datasets from the same samples suggests that microsatellites may detect structuring at a finer scale, but are less informative at larger scales of divergence.

Animals↗
PubMed1993

United States v. Levin: entrapment by estoppel doctrine applied in Medicare reimbursement context.

The decision in Levin reaffirms that health care providers should be entitled to rely in good faith on official interpretations and representations by authorized government officials as to the propriety of their conduct under the Medicare program. Although the doctrine of entrapment by estoppel was developed as a due process defense to a criminal prosecution, the fundamental notions of fairness underlying the doctrine should be applicable as well as in a civil action. Thus, the defense of entrapment by estoppel should be available, for example, in the context of civil health care reimbursement recoupment audits, where a provider has acted in reliance on the interpretation of a statute or regulation by the appropriate administrative agency charged with its enforcement.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1992

Vitrification of mouse oocytes using short cryoprotectant exposure: effects of varying exposure times on survival.

The effects on oocyte viability of varying the duration of exposure to cryoprotectants before rapid cooling to -196 degrees C were examined, using the vitrification protocol of Nakagata. A very short exposure (15 sec) was found to be optimal, resulting in an overall rate of development from vitrified oocytes to hatching blastocysts of 31.8%. Very high rates of survival (77-89%) of oocytes exposed to the cryoprotectant media, but without the vitrification, together with extreme variability in results between straws in the vitrified groups, suggest that losses in viability during vitrification may result from ice damage during devitrification of the medium.

Animals↗
PubMed1991

Vitrification of mouse oocytes: improved rates of survival, fertilization, and development to blastocysts.

Rall and Fahy's (1985) vitrification procedure for the cryopreservation of 8-cell embryos was applied to unfertilized mouse oocytes. Unchanged, this method resulted in a mean of 24.1% of vitrified oocytes fertilizing and developing to blastocysts in vitro. Exposure of oocytes to the cryoprotectant media, but without the vitrification, resulted in 30.8% developing to blastocysts. Modifications to the durations of and media used in the dilution and equilibration steps of the procedure produced a final protocol giving a mean of 55.4% of vitrified oocytes and 72.4% of nonvitrified VS1-exposed oocytes developing to blastocysts; 85.7% of control oocytes develop to blastocysts. Osmotically induced damage was found to be the most important cause of loss of viability in these methods. Cooling of oocytes to 5-8 degrees C during the procedure had no significant effect on their viability. No parthenogenetic activation of oocytes occurred as a result of exposure to the procedure.

Animals↗
PubMed1991

Use of statistical sampling and extrapolation in overpayment audits of physicians.

The successful defense of claims for physician overpayments by insurers requires the health care attorney to be familiar with the statistical sampling procedures employed during these types of audits. In this article, the author describes when audits are initiated, the factors that are taken into account in determining if statistical sampling is appropriate, how the statistical sampling study is conducted, and what defenses the health care attorney can assert when confronted with the results of a statistical sampling audit.

Insurance Claim Review↗
PubMed1991

Impact of a pharmacist on the educational value of pharmaceutical industry film showings.

A controlled trial was performed to assess the impact of drug information provided by a pharmacist on the educational value to physicians of pharmaceutical manufacturers' film showings. The trial consisted of two teams of physicians who attended pharmaceutical manufacturers' films and who afterward answered multiple choice questions on the drug being promoted. In one group, the liaison pharmacist, who had no knowledge of the content of the questionnaire, presented information on the drug being featured prior to the film showing while the control group did not have a pharmacist presentation. Out of a perfect score of five, there was a higher test score in the group of physicians who attended the pharmacist presentation/film showing (n = 75) than in the group which only attended the film (n = 65) (3.3 +/- 1.1 versus 2.8 +/- 1.2, respectively (p = 0.017)). While there was no difference in the scores obtained by the clerks, interns and residents (3.2 +/- 1.1, 3.3 +/- 0.9, 3.4 +/- 1.2 respectively) when a pharmacist was present, in his or her absence the scores for clerks, interns and residents were 2.5 +/- 1.3, 2.8 +/- 1.0, 3.6 +/- 1.2 respectively with residents scoring higher than clerks (p = 0.047). A pharmacist can enhance the educational value of a pharmaceutical manufacturer's film showing.

Attitude of Health Personnel↗