Toxic Chemicals

Catastrophic events such as the Bhopal, India tragedy and rising incidences of cancer in areas neighboring industrial facilities have heightened concern over the use of toxic chemicals in manufacturing and industry, particularly with respect to long-term exposure. While legislation and publicity have reduced the use of some chemicals, risks remain that continue to threaten the health of individuals worldwide. Based on the authors’ research conducted through their development of a program in Sao Paulo, Brazil, Toxic Chemicals: Risk Prevention Through Use Reduction examines various toxicity factors and proposes a plan to reduce the toxic impact of these hazardous substances. Explores all factors that contribute to toxicity The book begins by exploring the history of toxic chemical release reporting programs, a trend growing out of the Bhopal tragedy. It surveys their impact both in the United States through the Toxics Release Inventory (TRI) program and in the 29 other countries that maintain similar programs. Then, with the goal of developing a rational method of prioritizing toxic chemicals for reduction, the authors discuss mobility, persistence, and bioconcentration adjustment factors and present a method for integrating all of these factors to estimate the relative impact of chemical release. Compares alternate emphases in existing programs The book describes programs that concentrate on reducing the release of chemicals with the greatest adverse toxic impact and those that require companies to prepare pollution prevention plans and set goals for reducing use or release. It also examines technical assistance programs that help companies search for alternative chemicals to use or process changes that eliminate the use of toxic chemicals. In addition, it explores alternative market-based approaches for achieving environmental protection. Presents a workable plan for the future In the final chapters, the authors lay out their proposed program for reducing the use of toxic chemicals. This plan builds on the existing TRI program and uses lessons learned from this and other programs. The combined research assembled by the authors and their multifaceted approach to the issue of chemical toxicity enables companies and policy makers to move to the next level of toxic chemical use reduction, resulting in a safer environment for future generations

Caenorhabditis elegans as a model system to identify therapeutics for alcohol use disorders

Alcohol use disorders (AUDs) cause serious problems in society and few effective treatments are available. Caenorhabditis elegans (C. elegans) is an excellent invertebrate model to study the neurobiological basis of human behavior with a conserved, fully tractable genome, and a short generation time for fast generation of data at a fraction of the cost of other organisms. C. elegans demonstrate movement toward, and concentration-dependent self-exposure to various psychoactive drugs. The discovery of opioid receptors in C. elegans provided the impetus to test the hypothesis that C. elegans may be used as a medications screen to identify new AUD treatments. We tested the effects of naltrexone, an opioid antagonist and effective treatment for AUDs, on EtOH preference in C. elegans. Six-well agar test plates were prepared with EtOH placed in a target zone on one side and water in the opposite target zone of each well. Worms were treated with naltrexone before EtOH preference testing and then placed in the center of each well. Wild-type worms exhibited a concentration-dependent preference for 50, 70 and 95% EtOH. Naltrexone blocked acute EtOH preference, but had no effect on attraction to food or benzaldehyde in wild-type worms. Npr-17 opioid receptor knockout mutants did not display a preference for EtOH. In contrast, npr-17 opioid receptor rescue mutants exhibited significant EtOH preference behavior, which was attenuated by naltrexone. Chronic EtOH exposure induced treatment resistance and compulsive-like behavior. These data indicate that C. elegans can serve as a model system to identify compounds to treat AUDs

Scheduled access alcohol drinking by alcohol-preferring (P) and high-alcohol-drinking (HAD) rats: modeling adolescent and adult binge-like drinking

Binge alcohol drinking continues to be a public health concern among today’s youth and young adults. Moreover, an early onset of alcohol use, which usually takes the form of binge drinking, is associated with a greater risk for developing alcohol use disorders. Given this, it is important to examine this behavior in rat models of alcohol abuse and dependence. Toward that end, the objective of this article is to review findings on binge-like drinking by selectively bred alcohol-preferring (P) and high-alcohol-drinking (HAD) lines of rats. As reviewed elsewhere in this special issue, the P line meets all, and the HAD line meets most, of the proposed criteria for an animal model of alcoholism. One model of binge drinking is scheduled ethanol access during the dark cycle, which has been used by our laboratory for over 20 years. Our laboratory has also adopted a protocol involving the concurrent presentation of multiple ethanol concentrations. When this protocol is combined with limited access, ethanol intake is maximized yielding blood ethanol levels (BELs) in excess, sometimes greatly in excess, of 80 mg%. By extending these procedures to include multiple scheduled ethanol access sessions during the dark cycle for 5 consecutive days/week, P and HAD rats consume in 3 or 4 h as much as, if not more than, the amount usually consumed in a 24-h period. Under certain conditions, using the multiple scheduled access procedure, BELs exceeding 200 mg% can be achieved on a daily basis. An overview of findings from studies with other selectively bred, inbred, and outbred rats places these findings in the context of the existing literature. Overall, the findings support the use of P and HAD rats as animal models to study binge-like alcohol drinking and reveal that scheduled access procedures will significantly increase ethanol intake by other rat lines and strains as well

Time-course of extracellular nicotine and cotinine levels in rat brain following administration of nicotine: effects of route and ethanol coadministration

RATIONALE: Nicotine and ethanol are commonly coabused drugs, and nicotine-laced ethanol products are growing in popularity. However, little is known about time-course changes in extracellular nicotine and cotinine levels in rat models of ethanol and nicotine coabuse. OBJECTIVES: The objective of the present study was to determine the time-course changes in brain levels of nicotine and cotinine following subcutaneous (SC) and intragastric (IG) nicotine administration in alcohol-preferring (P) and Wistar rats. METHODS: In vivo microdialysis was used to collect dialysate samples from the nucleus accumbens shell (NACsh) for nicotine and cotinine determinations, following SC administration of (-)-nicotine (0.18, 0.35, and 0.70 mg/kg) in female P and Wistar rats or IG administration of (-)-nicotine (0.35 and 0.70 mg/kg) in 15 % (v/v) ethanol or water in female P rats. RESULTS: SC nicotine produced nicotine and cotinine dialysate levels as high as 51 and 14 ng/ml, respectively. IG administration of 15 % EtOH + 0.70 mg/kg nicotine in P rats resulted in maximal nicotine and cotinine dialysate levels of 19 and 14 ng/ml, respectively, whereas administration of 0.70 mg/kg nicotine in water resulted in maximal nicotine and cotinine levels of 21 and 25 ng/ml, respectively. Nicotine and cotinine levels were detectable within the first 15 and 45 min, respectively, after IG administration. CONCLUSIONS: Overall, the results of this study suggest that nicotine is rapidly adsorbed and produces relevant extracellular brain concentrations of nicotine and its pharmacologically active metabolite, cotinine. The persisting high brain concentrations of cotinine may contribute to nicotine addiction

Influence of boron on the morphological and physiological growth parameters of bean

Foi estudada a influência do boro no crescimento do feijoeiro (Phaseolus vulgaris L.) var. Cacahuate cultivado em solução nutritiva nas concentrações de 0,000; 0,005; 0,050 e 0,500 ppm de boro. A deficiência de boro afetou de maneira bastante pronunciada o desenvolvimento das raízes e o crescimento foliar e total das plantas. Através da taxa de assimilação aparente (TAA) observou-se que a deficiência de boro ocasionou um atraso nas atividades fotossintéticas, ao passo que outros parâmetros morfológicos e fisiológicos estudados não apresentaram resultados conclusivos sobre o papel do boro no desenvolvimento do feijoeiro.Effect of boron on Phaseolus vulgaris L. var. Cacahuate was studied in nutrient solutions containing 0.000; 0.005; 0.050 and 0.500 ppm of the element. The deficiency of boron affected root growth, leaf development and plant growth. Lower values of net assimilation rate (NAR) indicated reduced photosynthetic activity in the case of boron deficiency. No definite conclusions regarding the role of boron could be drawn on the basis of the other morphological or physiological parameters studied

The 16OH/18OH and OD/OH isotope ratios in comet C/2002 T7 (LINEAR)

The 16OH/18OH and OD/OH isotope ratios are measured in the Oort-Cloud comet C/2002 T7 (LINEAR) through ground-based observations of the OH ultraviolet bands at 3063 A (0,0) and 3121 A (1,1) secured with the Very Large Telescope (VLT) feeding the Ultraviolet-Visual Echelle Spectrograph (UVES). From the 16OH/18OH ratio, we find 16O/18O = 425 +/- 55, equal within the uncertainties to the terrestrial value and to the ratio measured in other comets, although marginally smaller. We also estimate OD/OH from which we derive D/H = 2.5 +/- 0.7 10-4 in water. This value is compatible with the water D/H ratios evaluated in other comets and marginally higher than the terrestrial value.Comment: Accepted for publication in A&A Letter

The reinforcing properties of ethanol are quantitatively enhanced in adulthood by peri-adolescent ethanol, but not saccharin, consumption in female alcohol-preferring (P) rats

Alcohol drinking during adolescence is associated in adulthood with heavier alcohol drinking and an increased rate of alcohol dependence. Past research in our laboratory has indicated that peri-adolescent ethanol consumption can enhance the acquisition and reduce the rate of extinction of ethanol self-administration in adulthood. Caveats of the past research include reinforcer specificity, increased oral consumption during peri-adolescence, and a lack of quantitative assessment of the reinforcing properties of ethanol. The current experiments were designed to determine the effects of peri-adolescent ethanol or saccharin drinking on acquisition and extinction of oral ethanol self-administration and ethanol seeking, and to quantitatively assess the reinforcing properties of ethanol (progressive ratio). Ethanol or saccharin access by alcohol-preferring (P) rats occurred during postnatal day (PND) 30-60. Animals began operant self-administration of ethanol or saccharin after PND 85. After 10 weeks of daily operant self-administration, rats were tested in a progressive ratio paradigm. Two weeks later, self-administration was extinguished in all rats. Peri-adolescent ethanol consumption specifically enhanced the acquisition of ethanol self-administration, reduced the rate of extinction for ethanol self-administration, and quantitatively increased the reinforcing properties of ethanol during adulthood. Peri-adolescent saccharin consumption was without effect. The data indicate that ethanol consumption during peri-adolescence results in neuroadaptations that may specifically enhance the reinforcing properties of ethanol during adulthood. This increase in the reinforcing properties of ethanol could be a part of biological sequelae that are the basis for the effects of adolescent alcohol consumption on the increase in the rate of alcoholism during adulthood

Reinforcing properties and neurochemical response of ethanol within the posterior ventral tegmental area are enhanced in adulthood by periadolescent ethanol consumption

Alcohol drinking during adolescence is associated with increased alcohol drinking and alcohol dependence in adulthood. Research examining the biologic consequences of adolescent ethanol (EtOH) consumption on the response to EtOH in the neurocircuitry shown to regulate drug reinforcement is limited. The experiments were designed to determine the effects of periadolescent alcohol drinking on the reinforcing properties of EtOH within the posterior ventral tegmental area (pVTA) and the ability of EtOH microinjected into the pVTA to stimulate dopamine (DA) release in the nucleus accumbens shell (AcbSh). EtOH access (24-hour free-choice) by alcohol-preferring rats occurred during postnatal days (PND) 30-60. Animals were tested for their response to EtOH after PND 85. Intracranial self-administration techniques were performed to assess EtOH self-infusion into the pVTA. In the second experiment, rats received microinjections of EtOH into the pVTA, and dialysis samples were collected from the AcbSh. The results indicate that in rats that consumed EtOH during adolescence, the pVTA was more sensitive to the reinforcing effects of EtOH (a lower concentration of EtOH supported self-administration) and the ability of EtOH microinjected into the pVTA to stimulate DA release in the AcbSh was enhanced (sensitivity and magnitude). The data indicate that EtOH consumption during adolescence altered the mesolimbic DA system to be more sensitive and responsive to EtOH. This increase in the response to EtOH within the mesolimbic DA during adulthood could be part of biologic sequelae that are the basis for the deleterious effects of adolescent alcohol consumption on the rate of alcoholism during adulthood