Barbiturate and picrotoxin-sensitive chloride efflux in rat cerebral cortical synaptoneurosomes

AbstractThe effects of various barbiturates and picrotoxin in modifying the efflux of chloride (36Cl−) was studied in a novel subcellular preparation from rat cerebral cortex, the ‘synaptoneurosome’. Dilution of synaptoneurosomes pre-loaded with 36Cl− resulted in rapid efflux of 36Cl− that could be measured as early as 10 s following dilution. In the presence of barbiturates such as pentobarbital and hexobarbital there was a significant increase in 36Cl− efflux which was not observed with the pharmacologically-inactive barbiturate, barbital. The effect of barbiturates in enhancing 36Cl− efflux was also stereospecific [(−)-DMBB > (+)-DMBB] and reversed by picrotoxin. By contrast, picrotoxin alone significantly inhibited 36Cl− efflux. These data demonstrate pharmacologically relevant Cl− transport for the first time in a subcellular brain preparation

Screening for inter-hospital differences in cesarean section rates in low-risk deliveries using administrative data: An initiative to improve the quality of care

BACKGROUND: Rising national cesarean section rates (CSRs) and unexplained inter-hospital differences in CSRs, led national and international bodies to select CSR as a quality indicator. Using hospital discharge abstracts, we aimed to document in Belgium (1) inter-hospital differences in CSRs among low risk deliveries, (2) a national upward CSR trend, (3) lack of better neonatal outcomes in hospitals with high CSRs, and (4) possible under-use of CS. METHODS: We defined a population of low risk deliveries (singleton, vertex, full-term, live born, 2499 g). Using multivariable logistic regression techniques, we provided degrees of evidence regarding the observed departure ([relative risk-1]*100) of each hospital (N = 107) from the national CSR and its trend. To determine a benchmark, we defined three CSR groups (high, average and low) and compared them regarding 1 minute Apgar scores and other neonatal endpoints. An anonymous feedback is provided to the hospitals, the College of Physicians (with voluntary disclosure of the outlying hospitals for quality improvement purposes) and to the policy makers. RESULTS: Compared with available information, the completeness and accuracy of the data, regarding the variables selected to determine our study population, showed adequate. Important inter-hospital differences were found. Departures ranged from -65% up to +75%, and 9 "high CSR" and 13 "low CSR" outlying hospitals were identified. We observed a national increasing trend of 1.019 (95%CI [1.015; 1.022]) per semester, adjusted for age groups. In the "high CSR" group 1 minute Apgar scores <4 were over-represented in the subgroup of vaginal deliveries, suggesting CSs not carried out for medical reasons. Under-use of CS was also observed. Given their questionable completeness, except Apgar scores, our neonatal results, showing a significant association of CS with adverse neonatal endpoints, are to be cautiously interpreted. Taking the available evidence into account, the "Average CSR" group seemed to be the best benchmark candidate. CONCLUSION: Rather than firm statements about quality of care, our results are to be considered a useful screening. The inter-hospital differences in CSR, the national CS upward trend, the indications of over-use and under-use, the geographically different obstetric patterns and the admission day-related concentration of deliveries, whether or not by CS, may trigger initiatives aiming at improving quality of care

Effects of chronic phencyclidine on fixed-ratio responding: No relation to neurotransmitter receptor binding in rat cerebral cortex

The effects of chronic phencyclidine (3.2 mg/kg for 25 days) on responding maintained under a fixed-ratio 30 schedule of food presentation were studied in rats. Initially phencyclidine produced large decreases in the overall rate of responding. This decrease was due primarily to long pauses in responding and secondarily to a decrease in local rates of responding. Although tolerance developed to the rate-decreasing effects of phencyclidine in each subject, the extent and pattern of its development differed among the subjects. After the chronic drug regimen, the rats were sacrificed. Ligand binding to muscarinic cholinergic, opiate, adrenergic, and serotonergic receptors in cortex was then compared to that in rats which received saline with operant training, phencyclidine alone, or saline alone. Neither operant behavior alone, phencyclidine alone, nor the interaction of phencyclidine and operant behavior was found to alter binding to these receptors. The results indicate that behavioral tolerance develops to phencyclidine, but it is not accompanied by changes in binding to the receptors studied. © 1982

Science expectancy, value, and cost profiles and their proximal and distal relations to undergraduate science, technology, engineering, and math persistence

Despite efforts to attract and maintain diverse students in the science, technology, engineering, and math (STEM) pipeline, issues with attrition from undergraduate STEM majors persist. The aim of this study was to examine how undergraduate science students’ competence beliefs, task values, and perceived costs in science combine into motivational profiles and to consider how such profiles relate to short-term and long-term persistence outcomes in STEM. We also examined the relations between underrepresented group membership and profile membership. Using latent profile analysis, we identified three profiles that characterized 600 participants’ motivation during their first semester in college: Moderate All, Very High Competence/Values-Low Effort Cost, and High Competence/Values-Moderate Low Costs. The Moderate All profile was associated with the completion of fewer STEM courses and lower STEM grade point averages relative to the other profiles after 1 and 4 years of college. Furthermore, underrepresented minority students were overrepresented in the Moderate All profile. Findings contribute to our understanding of how science competence beliefs, task values, and perceived costs may coexist and what combinations of these variables may be adaptive or deleterious for STEM persistence and achievement