Endocytotic formation of vesicles and other membranous structures induced by Ca2+ and axolemmal injury

Vesicles and/or other membranous structures that form after axolemmal damage have recently been shown to repair (seal) the axolemma of various nerve axons. To determine the origin of such membranous structures, (1) we internally dialyzed isolated intact squid giant axons (GAs) and showed that elevation of intracellular Ca21 .100 uM produced membranous structures similar to those in axons transected in Ca21-containing physiological saline; (2) we exposed GA axoplasm to Ca21- containing salines and observed that membranous structures did not form after removing the axolemma and glial sheath but did form in severed GAs after .99% of their axoplasm was removed by internal perfusion; (3) we examined transected GAs and crayfish medial giant axons (MGAs) with time-lapse confocal fluorescence microscopy and showed that many injuryinduced vesicles formed by endocytosis of the axolemma; (4) we examined the cut ends of GAs and MGAs with electron microscopy and showed that most membranous structures were single-walled at short (5–15 min) post-transection times, whereas more were double- and multi-walled and of probable glial origin after longer (30–150 min) post-transection times; and (5) we examined differential interference contrast and confocal images and showed that large and small lesions evoked similar injury responses in which barriers to dye diffusion formed amid an accumulation of vesicles and other membranous structures. These and other data suggest that Ca21 inflow at large or small axolemmal lesions induces various membranous structures (including endocytotic vesicles) of glial or axonal origin to form, accumulate, and interact with each other, preformed vesicles, and/or the axolemma to repair the axolemmal damage.This work was supported by grants from National Institutes of Health (NIH; NS31256) and the State of Texas (Advanced Technology 3658-446).Neuroscienc

Maternal Serologic Screening to Prevent Congenital Toxoplasmosis: A Decision-Analytic Economic Model

We constructed a decision-analytic and cost-minimization model to compare monthly maternal serological screening for congenital toxoplasmosis, prenatal treatment, and post-natal follow-up and treatment according to the current French protocol, versus no systematic screening or perinatal treatment. Costs are based on published estimates of lifetime societal costs of developmental disabilities and current diagnostic and treatment costs. Probabilities are based on published results and clinical practice in the United States and France. We use sensitivity analysis to evaluate robustness of results. We find that universal monthly maternal screening for congenital toxoplasmosis with follow-up and treatment, following the French (Paris) protocol, leads to savings of $620 per child screened. Results are robust to changes in test costs, value of statistical life, seroprevalence in women of childbearing age, fetal loss due to amniocentesis, incidence of primary T. gondii infection during pregnancy, and to bivariate analysis of test costs and incidence of primary T. gondii infection. Given the parameters in this model and a maternal screening test cost of$12, screening is cost-saving for rates of congenital infection above 1 per 10,000 live births. Universal screening according to the French protocol is cost saving for the US population within broad parameters for costs and probabilities

Racial segregation by playing position in elite Australian basketball

Over the past decade basketball has emerged in Australia as a sporting phenomenon. The rapid growth and development of basketball has encouraged the recruitment of many American players and coaches. Consequently, the visibility of Black Americans in Australian basketball has increased dramatically. The purpose of this study was to investigate the nature and degree to which stereotyping, as customary in the United States, is also evidenced by American participation in elite Australian basketball. Using the notion of centrality, the centre and point guard positions were identified as being the most critical in terms of leadership and outcome control. Forwards and shooting guards were identified as non-central positions. Analysis by means of a chi-square, testing the effects of league x 'race' x position, revealed no significance. Further chi-square analyses revealed a significant difference in 'race' x position as well as 'race' x centrality. Results suggested that Blacks were assigned disproportionately to less central positions, and Whites were over-represented at playing positions that emphasized leadership, co-ordination, and outcome control. It appears that evidence of stereotyping is not limited to the United States, but may have a broader international dimension