The IPCS Collaborative Study on Neurobehavioral Screening Methods: V. Results of chemical testing. Steering Group

The goal of the International Programme on Chemical Safety (IPCS) Collaborative Study on Neurobehavioral Screening Methods was to determine the intra- and inter-laboratory reliability of a functional observational battery (FOB) and an automated assessment of motor activity in eight laboratories worldwide. The control data were crucial to the outcome of the studies in terms of sensitivity and reliability of the test measures, which in turn impact on the between-laboratory comparisons of chemical effects. In addition, analyses of control data can aid in determining endpoints that may require modification to improve their sensitivity and reliability. The control data from the eight laboratories were examined in terms of the following parameters: 1) control variability within studies for each laboratory; 2) within-laboratory replicability of control values across studies; 3) within-laboratory stability of control values over the course of testing for a given study; and 4) between-laboratory comparisons of parameters (1), (2), and (3). The analyses indicated considerable differences across endpoints, wherein some measures showed high variability and little replicability, while others were extremely reproducible. Generally, there were similar ranges of variability and replicability of control data across laboratories, although in some cases one or two laboratories were markedly different from the others. The physiological (weight, body temperature) and neuromuscular (grip strength, landing foot splay) endpoints exhibited the least variability, whereas the subjective assessments of reactivity varied the most. These data indicate a reasonable degree of comparability in the data generated in the participating laboratories.     

Multilayered dermal subcompartments for modeling chemical absorption

Dermal penetration of chemicals and drugs is of concern to both toxicologists and pharmacologists. Environmental professionals try to limit exposure to chemicals using protective clothing and gloves or barrier creams to trap chemicals. Drug developers try to enhance penetration of chemicals through the skin for medical purposes. Both can use predictive biologically-based mathematical models to assist in understanding the processes involved. These models are especially useful when they are based on physiological and biochemical parameters which can be measured in the laboratory. Appropriately validated models based on conservation of mass, diffusion and chemical transport by flow can be predictive of human exposures. In this paper we develop two new physiologically-based pharmacokinetic (PBPK) skin models to predict blood concentrations of dibromomethane in rats after skin-only vapor exposures. These new models improve the predictions of the blood concentrations especially at the beginning of the exposures. Sensitivity analysis shows that the permeability constants followed by partition coefficients have the most impact on blood concentration predictions. With proper validation the new models could be used to improve species, dose, and duration extrapolations of chemical or drug penetration. They could also be used to investigate and predict concentrations of drugs or chemicals in the skin.     

Female voice communications in high level aircraft cockpit noises--part II: vocoder and automatic speech recognition systems

BACKGROUND: The purpose of the present study was to assess the implications of cholesterol distribution and its change on coronary heart disease (CHD) mortality and disease prevention at a population level. METHODS AND RESULTS: In five independent risk factor surveys (1972, 1977, 1982, 1987, and 1992) in eastern Finland, serum cholesterol was measured in 27721 randomly selected men and women aged 30 to 59 years. The association between cholesterol level and CHD risk and the prediction of the effect of different prevention strategies was estimated by use of logistic regression models. The entire cholesterol distribution of the population shifted markedly toward lower levels between 1972 and 1992. The proportion of subjects with a very high cholesterol level (> or =8.0 mmol/L), also decreased markedly, from 16% to 3%. The risk of CHD death among subjects with cholesterol > or =8.0 mmol/L was approximately 5-fold that of those individuals having cholesterol <5.0 mmol/L. Nevertheless, because CHD risk increases continuously as serum cholesterol increases, and because the number of people having only slightly or moderately increased serum cholesterol was large, most CHD deaths occurred among them. A 10% reduction in cholesterol levels in the entire population would subsequently reduce CHD mortality by 20%, as much as an effective treatment as a 25% decrease in serum cholesterol among all subjects with cholesterol >6.5 mmol/L and four times more than similar treatment of all subjects with cholesterol > or =8.0 mmol/L. CONCLUSIONS: The community-based population strategy in cardiovascular disease prevention was effective in decreasing cholesterol levels among the entire population, including the subjects with the highest cholesterol values. The balanced application of both high-risk and population strategies is needed for the effective prevention of CHD.     

Gut mucosal ischemia during normothermic cardiopulmonary bypass results from blood flow redistribution and increased oxygen demand

Impaired gut mucosal perfusion has been reported during cardiopulmonary bypass. To better define the adequacy of gut blood flow and oxygenation during cardiopulmonary bypass, we measured overall gut blood flow and ileal mucosal flow and their relationship to mucosal pH, mesenteric oxygen delivery and oxygen consumption in immature pigs (n = 8). Normothermic, noncross-clamped, right atrium-to-aorta cardiopulmonary bypass was maintained at 100 ml/kg per minute for 120 minutes. Animals were instrumented with an ultrasonic Doppler flow probe on the superior mesenteric artery, a mucosal laser Doppler flow probe in the ileum, and pH tonometers in the stomach, ileum, and rectum. Radioactive microspheres were injected before and at 5, 60, and 120 minutes of cardiopulmonary bypass for tissue blood flow measurements. Overall gut blood flow significantly increased during cardiopulmonary bypass as evidenced by increases in superior mesenteric arterial flow to 134.1% +/- 8.0%, 137.1% +/- 7.5%, 130.3% +/- 11.2%, and 130.2% +/- 12.7% of baseline values at 30, 60, 90, and 120 minutes of bypass, respectively. Conversely, ileal mucosal blood flow significantly decreased to 53.6% +/- 6.4%, 49.5% +/- 6.8%, 58.9% +/- 11.6%, and 47.8% +/- 10.0% of baseline values, respectively. Blood flow measured with microspheres was significantly increased to proximal portions of the gut, duodenum and jejunum, during cardiopulmonary bypass, whereas blood flow to distal portions, ileum and colon, was unchanged. Gut mucosal pH decreased progressively during cardiopulmonary bypass and paralleled the decrease in ileal mucosal blood flow. Mesenteric oxygen delivery decreased significantly from 67.0 +/- 10.0 ml/min per square meter at baseline to 42.4 +/- 4.6, 44.9 +/- 3.5, 46.0 +/- 3.6, and 42.9 +/- 3.9 ml/min per square meter at 30, 60, 90, and 120 minutes of bypass. Despite the decrease in mesenteric oxygen delivery, mesenteric oxygen consumption increased progressively from 10.8 +/- 1.4 ml/min per square meter at baseline to 13.4 +/- 1.2, 15.9 +/- 1.2, 16.7 +/- 1.4, and 16.6 +/- 1.54 ml/min per square meter, respectively. We conclude that gut mucosal ischemia during normothermic cardiopulmonary bypass results from a combination of redistribution of blood flow away from mucosa and an increased oxygen demand.     

Memory for odors and odor names: Modalities of elaboration and imagery.

This study examined memory for common odors and odor names that were encoded with visual, verbal, and olfactory elaborations. In the first experiment, subjects elaborated olfactory stimuli by processing a picture of the odor's source, a name for the odor, or both. Two control groups were also included: One group was presented only with the odors, and another group was presented only with odor names. One week later, all subjects were given both a free recall test of odor names and an olfactory recognition test. In general, the elaboration groups outperformed the control groups, with the visual and verbal elaboration group demonstrating the best performance. In a second experiment, olfactory imaginal encoding of odor names was compared with visual imaginal encoding of the same names to measure the relative efficacy of same versus different modality encoding on later stimulus recognition. The results showed that olfactory imaginal encoding aided later recognition of odors, and visual imaginal encoding aided later picture recognition. It is suggested that different modalities contribute unique and mnemonically independent information to episodic memory performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of contrastive rhetoric in teaching professionalcommunication in English as a second or foreign language

People who write in English as a second or foreign language often find it difficult to write clear, coherent, idiomatic English. Contrastive rhetoric studies the structure of language beyond the sentence (discourse), as well as the influence of culture on writing. Findings from contrastive research should be incorporated into writing instruction and teacher training to give nonnative speakers of English more help in writing for the world of work     

Chemistry of male mandibular gland secretions ofPhilanthus basilaris cresson andPhilanthus bicinctus (Mickel) (Hymenoptera: Sphecidae)

Detailed chemical characterizations are provided for the species-specific mixtures of marking pheromones utilized by the male beewolvesPhilanthus basilaris andP. bicinctus. Successful analysis of these complex mixtures of 2-ketones, fatty acids, ethyl esters, and aldehydes was facilitated by the treatment of the crude extracts with 1,1-dimethylhydrazine and direct analysis of the resulting hydrazones, methyl esters, and starting ethyl esters by GC-MS.     

Renal 11 beta-hydroxysteroid dehydrogenase activity is enhanced by ramipril and captopril

Changes of renal 11 beta-hydroxysteroid dehydrogenase activity may contribute to variations of sodium excretion by modulating inactivation of cortisol or corticosterone and thus their access to mineralocorticoid receptors. Angiotensin-converting enzyme inhibitors enhance sodium excretion but by mechanisms still incompletely understood. To test the hypothesis that the angiotensin-converting enzyme inhibitors ramipril and captopril act in part by enhancing renal 11 beta-hydroxysteroid dehydrogenase activity, the effects of these agents in slices of rat renal outer medulla were examined. Conversion of 3H-corticosterone to 3H-11-dehydrocorticosterone was 58% greater in tissue from fasted rats than from fed rats (mean +/- SE 2467 +/- 146 vs. 1584 +/- 102 pmol/mg protein.h, P < 0.01). Incubation of tissue from fed rats with physiological concentrations of ramiprilat, the active form of ramipril, enhanced activity (1497 +/- 76) to fasted levels (2323 +/- 120, P < 0.02). Captopril had a similar in vitro effect (1557 +/- 92 to 2109 +/- 116, P < 0.01). Ramipril given in vivo to fed rats also increased activity to fasted levels (1716 +/- 101 to 2737 +/- 396, P < 0.05). Angiotensin II incubated with renal tissue from fasted rats suppressed activity to fed levels, but this effect was prevented by the presence of ramiprilat. Both ramipril and captopril enhance renal 11 beta-hydroxysteroid dehydrogenase activity, and this effect is only partly explained by limitation of endogenous angiotensin II production.