Biomedical subjects

C Stoker

Publications and source records attributed to C Stoker.

5 recordsLinked to original sources

PubMed2003

Sex reversal effects on Caiman latirostris exposed to environmentally relevant doses of the xenoestrogen bisphenol A.

Exposure to environmental contaminants known as endocrine disruptors (EDs) alters the development and function of reproductive organs in several species. Bisphenol A (BPA) is an estrogenic chemical that leaches from dental materials and plastic food and beverage containers. BPA has been found in sewage, surface and drinking water, and therefore poses a potentially significant risk for human and wildlife. Prenatal exposure of rodents to environmentally relevant doses of BPA alters the development of the reproductive organs of male and female offspring. Species with temperature dependent sex determination (TSD) could act as sentinels of ecosystem health by providing sensitive biomarkers of endocrine disruptor's effects. We selected Caiman latirostris as an animal model to study endocrine disruption caused by BPA. The aim of this study was to determine whether exposure in ovum to BPA could cause estrogen-like effects on the reproductive system of C. latirostris. Sex determination and gonadal histoarchitecture were the endpoints evaluated after in ovum exposure to different doses of BPA and 17beta-estradiol (E(2)). We confirmed that C. latirostris is a species with TSD and additionally demonstrated that BPA causes estrogen-like developmental effects by reversing gonadal sex and altering gonadal histoarchitecture. Differences in responses to BPA and E(2) in our in vivo system were on the order of 100-fold. In contrast published in vitro studies have reported differences on the order of 10,000x or more. These results support the utility of C. latirostris, a species in which sex determination is temperature dependent, as a tool in assessing estrogenic activity in vivo and as a sentinel to monitor EDs in aquatic environment.

Air Pollutants, Occupational↗

PubMed2001

Bcl-2 correlates with tumor ploidy and nuclear morphology in early stage prostate carcinoma. A fine needle aspiration biopsy study.

We evaluated the nuclear morphology, ploidy, bcl-2 expression and in situ apoptosis in sections of fine-needle aspiration (FNA) biopsy specimens of thirty-one randomly selected Stage B prostate carcinomas. Sections of paraffin-embedded pelleted cells obtained from FNA biopsy specimens were studied. Nuclear grade was determined according to the WHO system. Nuclear morphometry and DNA ploidy were carried out using an automated image analyzer. We used immunostaining and the TUNEL method to evaluate bcl-2 expression and in situ apoptosis. The median nuclear area increased with increasing nuclear grade. Ploidy analysis showed that 54.8% of tumors were diploid, 3.2% tetraploid and 41.9% aneuploid. Bcl-2 overexpression was found in 10 of 31 tumors. There was a significant positive correlation between bcl-2 expression and nuclear area (r(s): 0.45 p < 0.01). Nine of ten bcl-2-positive tumors had a nuclear area larger than the median of the series, and 70% of bcl-2-positive tumors were of the aneuploid type. The apoptotic index had a negative correlation with nuclear area, and the lowest indexes were found in aneuploid tumors. Bcl-2 expression showed a highly significant association with both parameters of high aggressiveness: nuclear size and aneuploidy. The combined evaluation of nuclear morphology, ploidy and cell survival parameters might better identify patients with poor prognosis among early stage prostate carcinomas diagnosed by FNA biopsies.

Apoptosis↗

PubMed1997

Results from the Mars Pathfinder camera.

Images of the martian surface returned by the Imager for Mars Pathfinder (IMP) show a complex surface of ridges and troughs covered by rocks that have been transported and modified by fluvial, aeolian, and impact processes. Analysis of the spectral signatures in the scene (at 440- to 1000-nanometer wavelength) reveal three types of rock and four classes of soil. Upward-looking IMP images of the predawn sky show thin, bluish clouds that probably represent water ice forming on local atmospheric haze (opacity approximately 0.5). Haze particles are about 1 micrometer in radius and the water vapor column abundance is about 10 precipitable micrometers.

Atmosphere↗

PubMed1993

Chronic constipation in long stay elderly patients: a comparison of lactulose and a senna-fibre combination.

OBJECTIVES: To compare the efficacy and cost effectiveness of a senna-fibre combination and lactulose in treating constipation in long stay elderly patients. DESIGN: Randomised, double blind, cross over study. SETTING: Four hospitals in Northern Ireland, one hospital in England, and two nursing homes in England. SUBJECTS: 77 elderly patients with a history of chronic constipation in long term hospital or nursing home care. INTERVENTION: A senna-fibre combination (10 ml daily) or lactulose (15 ml twice daily) with matching placebo for two 14 day periods, with 3-5 days before and between treatments. MAIN OUTCOME MEASURES: Stool frequency, stool consistency, and ease of evacuation; deviation from recommended dose; daily dose and cost per stool; adverse effects. RESULTS: Mean daily bowel frequency was greater with the senna-fibre combination (0.8, 95% confidence interval 0.7 to 0.9) than lactulose (0.6, 0.5 to 0.7; t = 3.51 p < or = 0.001). Scores for stool consistency and ease of evacuation were significantly higher for the senna-fibre combination than for lactulose. The recommended dose was exceeded more frequently with lactulose than the senna-fibre combination (chi 2 = 8.38, p or = 0.01). As an index of the standard daily dose, the dose per stool was 1.52 for lactulose and 0.97 for the senna-fibre combination, at a cost per stool of 39.7p for lactulose and 10.3p for senna-fibre. Adverse effects were no different for the two treatments. CONCLUSIONS: Both treatments were effective and well tolerated for chronic constipation in long stay elderly patients. The senna-fibre combination was significantly more effective than lactulose at a lower cost.

Aged↗

PubMed1993

A comparison of Agiolax and lactulose in elderly patients with chronic constipation.

In a double-blind crossover study the efficacies of Agiolax, a combination of fibre and senna pod, and lactulose were compared in 77 long-stay elderly patients with chronic constipation. Mean daily bowel frequency, stool consistency and ease of evacuation were significantly greater with Agiolax than lactulose. The recommended dose was exceeded more frequently with lactulose than Agiolax (chi 2 = 8.38, p < 0.01). Adverse effects were not different for the 2 treatments. In long-stay elderly patients with chronic constipation Agiolax and lactulose were well tolerated, but Agiolax proved a more effective treatment.

Aged↗