Exposição humana a trialometanos presentes em água tratada Human exposure to trihalomethanes in drinking water

Realizou-se uma revisão bibliográfica do período de 1974-1998, no MEDLINE, sobre compostos orgânicos halogenados derivados de hidrocarbonetos denominados de trialometanos. Muitos deles, reconhecidamente carcinogênicos para diferentes espécies animais, podem ser encontrados freqüentemente, inclusive entre nós, em águas tratadas e enviadas à população urbana. É o caso de compostos como o clorofórmio, bromodiclorometano, clorodibromometano e bromofórmio, resultantes da halogenação de precursores, principalmente substâncias húmicas e fúlvicas presentes na água que será tratada (clorada). Assim, descreve-se sua formação, fontes de exposição humana bem como os aspectos toxicológicos de maior importância: disposição cinética e espectro dos efeitos tóxicos (carcinogênicos, mutagênicos e teratogênicos) decorrentes de exposições a longo prazo e baixas concentrações. Níveis seguros de exposição propostos são também fornecidos.<br>Halogenated hydrocarbon compounds, some of them recognized as carcinogenic to different animal species can be found in drinking water. Chloroform, bromodichloromethane, dibromochloromethane and bromoform are the most important trihalomethanes found in potable water. They are produced in natural waters during chlorinated desinfection by the halogenation of precursors, specially humic and fulvic compounds. The review, in the MEDLINE covers the period from 1974 to 1998, presents the general aspects of the formation of trihalomethanes, sources of human exposure and their toxicological meaning for exposed organisms: toxicokinetic disposition and spectrum of toxic effects (carcinogenic, mutagenic and teratogenic)

Molecular mechanisms of muscarinic acetylcholine receptor-stimulated increase in cytosolic free Ca2+ concentration and ERK1/2 activation in the MIN6 pancreatic b-cell line

Muscarinic acetylcholine receptor (mAChR) activation of pancreatic β-cells elevates intracellular Ca2+ and potentiates glucose-stimulated insulin secretion. In addition, it activates a number of signaling molecules, including ERK1/2, whose activation has been shown to play an important role in regulating pancreatic β-cell function and mass. The aim of this work was to determine how mAChR activation elevates intracellular Ca2+ concentration ([Ca2+] i ) and activates ERK1/2 in the pancreatic β-cell line MIN6. We demonstrate that agonist-stimulated ERK1/2 activation is dependent on the activation of phospholipase C and an elevation in [Ca2+] i , but is independent of the activation of diacylglycerol-dependent protein kinase C isoenzymes. Using a pharmacological approach, we provide evidence that agonist-induced increases in [Ca2+] i and ERK activity require (1) IP3 receptor-mediated mobilization of Ca2+ from the endoplasmic reticulum, (2) influx of extracellular Ca2+ through store-operated channels, (3) closure of KATP channels, and (4) Ca2+ entry via L-type voltage-operated Ca2+ channels. Moreover, this Ca2+-dependent activation of ERK is mediated via both Ras-dependent and Ras-independent mechanisms. In summary, this study provides important insights into the multifactorial signaling mechanisms linking mAChR activation to increases in [Ca2+] i and ERK activity

A quarter century of Culture's Consequences: a review of empirical research incorporating Hofstede's cultural values framework

Since Geert Hofstede's Culture's Consequences: International Differences in Work-Related Values (Sage, 1980) was published, researchers have utilized Hofstede's cultural values framework in a wide variety of empirical studies. We review 180 studies published in 40 business and psychology journals and two international annual volumes between 1980 and June 2002 to consolidate what is empirically verifiable about Hofstede's cultural values framework. We discuss limitations in the Hofstede-inspired research and make recommendations for researchers who use Hofstede's framework in the future. Journal of International Business Studies (2006) 37, 285–320. doi:10.1057/palgrave.jibs.8400202