Evaluation of a novel Web-based pediatric advanced life support course.

Objective: To assess the educational efficacy of a Web-based pediatric advanced life support course (Web-PALS).

Design: Nonrandomized, prospective, cohort study.

Setting: University medical center.

Population growth kinetics and bulk membrane lipid alterations in Tetrahymena pyriformis: exposure to pentachlorophenol.

This study describes effects of exposure of the freshwater ciliate Tetrahymena pyriformis to the "classic" weak acid respiratory uncoupler pentachlorophenol (PCP) on the population growth kinetics and membrane lipid profiles. The assessment of growth kinetics of naive populations exposed to PCP, at concentrations eliciting < 50% growth inhibition, showed generation times of exposed cultures similar to generation times of controls but preceded by a short lag phase (< 2 h). Assessment of exposed cultures exhibiting > 50% growth inhibition revealed generation times that increased with increasing concentrations of toxicant.

Xenoestrogenic gene expression: structural features of active polycyclic aromatic hydrocarbons.

Estrogenicity was assessed using the Saccharomyces cerevisiae-based Lac-Z reporter assay and was reported as the logarithm of the inverse of the 50% molar beta-galactosidase activity (log[EC50(-1)]). In an effort to quantify the relationship between molecular structure of polycyclic aromatic hydrocarbons (PAHs) and estrogenic gene expression, a series of PAHs were evaluated. With noted exceptions, the results of these studies indicate that the initial two-dimensional structural warning for estrogenicity, the superpositioning of a hydroxylated aromatic system on the phenolic A-ring of 17-beta-estradiol, can be extended to the PAHs.

Structure-activity relationships for gene activation oestrogenicity: evaluation of a diverse set of aromatic chemicals.

Structure-activity relationships for oestrogenicity were developed based on 120 aromatic chemicals evaluated in the Saccharomyces cerevisiae-based Lac-Z reporter assay. Relative gene activation was compared to 17 beta-estradiol and varied over eight orders of magnitude. Analysis of the data compared to 17 beta-estradiol identified three structural criteria that were related to xenoestrogen activity and potency: (1) the hydrogen-bonding ability of the phenolic ring mimicking the A-ring, (2) a hydrophobic centre similar in size and shape to the B- and C-rings, and (3) a hydrogen-bond donor mimicking the 17 beta-hydroxyl moiety of the D-ring, especially with an oxygen-to-oxygen distance similar to that between the 3- and 17 beta-hydroxyl groups of 17 beta-estradiol.

Population growth impairment of sulfur-containing compounds to Tetrahymena pyriformis.

A series of 37 aliphatic and aromatic sulfur-containing compounds were evaluated in 2-day Tetrahymena pyriformis population growth impairment assay. The results indicate that, except for select compounds, the in-ring sulfur-containing compounds, sulfates, sulfites, thiols, sulfones, and sulfoxides model as neutral and noncovalent-reacting narcotics. Abiotic loss due to volatility appears to interfere in accurate model prediction because actual toxicity was less than predicted.