The Toxic Effect of Lanthanum on Planaria Is Mediated by a Variety of Ion Channels.

The effect of toxic concentrations of La3+ on the Ca, K, Na, Mg, and Cl channels of planaria was investigated through the use of various agonists and antagonists to those channels. It was demonstrated that La exerts its toxic effects through L-type, but not T-type, Ca channels. La also demonstrated activity at Na, K, Mg, and Cl channels, but, these effects were most likely mediated by other effects of La on Ca activity. However, these interactions appear to be very complex and confounded by oxidative stresses. The study also introduces a planaria stress scale which allows the effects of toxic substances to be examined on a continuum.

Experimental toxicology: Issues of statistics, experimental design, and replication.

The difficulty of replicating experiments has drawn considerable attention. Issues with replication occur for a variety of reasons ranging from experimental design to laboratory errors to inappropriate statistical analysis. Here we review a variety of guidelines for statistical analysis, design, and execution of experiments in toxicology. In general, replication can be improved by using hypothesis driven experiments with adequate sample sizes, randomization, and blind data collection techniques.

Eating Self-Regulation in Overweight and Obese Adults: A Concept Analysis.

BACKGROUND: Poor eating behaviors greatly influence the development of becoming overweight or obese. Learning to better self-regulate eating is one area in which individuals can positively influence their own health. PURPOSE: The purpose of this concept analysis is to provide an in-depth analysis of the concept eating self-regulation as it pertains to overweight and obese adults using Walker and Avant's method. RESULTS: The definition for eating self-regulation formulated as a result of this concept analysis and based on the critical attributes is the ability to initiate goal-related behaviors, to consistently self-monitor dietary intake, to regularly apply willpower to resist temptations, to self-evaluate where one stands in relationship to goal attainment, and finally to maintain motivation to positively change eating behaviors. Cognitive restraint, moderation, mindfulness, disinhibition, delayed gratification, emotions and moods, self-efficacy, social support, the environment, and physical activity are the antecedents that may influence eating self-regulation. CONCLUSION: Examining an individual's weight, body mass index, lipid levels, or blood pressure are some ways to determine if self-regulation of eating behavior is achieved. With a consistent definition of self-regulation and a better understanding of the critical factors that influence eating behaviors, research can better explore how to help individuals change their eating behaviors more effectively.

Motivational Factors Predict Weight Loss in Rural Adults.

OBJECTIVE: The objective was to: (a) describe the changes over time in motivational factors of weight loss and (b) to examine predictors of weight loss in rural adults enrolled in a weight loss program. DESIGN AND SAMPLE: A longitudinal study was conducted in a convenience sample of 50 adults recruited from a rural Young Men's Christian Association. MEASURES: Questionnaires were completed at baseline (preprogram), 1, 2 and 3 months (end of program). RESULTS: Mean age was 42.4 (SD ± 11.8); 84% were female and mean BMI was 32.9 (SD ± 4.3). Individuals lost an average of 12.1 pounds. Barriers to healthy eating decreased significantly over time (p < .001). Significant predictors of weight loss included gender (ß = .501, p < .001), and the amount of change between baseline and 3 months in controlled regulation (ß = .270, p < .05), barriers to healthy eating (ß = -0.225, p < .05), and physical activity (ß = .238, p < .05) explaining 45% of the variance (F[(8, 41] = 5.92, p < .001) in weight loss. CONCLUSIONS: Rural adults were more likely to lose weight if they had higher levels of controlled regulation, if barriers were reduced, and if physical activity levels increased during the 3-month weight loss program.

The role of metal regulatory proteins in brain oxidative stress: a tutorial.

The proteins that regulate the metabolism of a metal must also play a role in regulating the redox activity of the metal. Metals are intrinsic to a substantial number of biological processes and the proteins that regulate those activities are also considerable in number. The role these proteins play in a wide range of physiological processes involves them directly and indirectly in a variety of disease processes. Similarly, it may be therapeutically advantageous to pharmacologically alter the activity of these metal containing proteins to influence disease processes. This paper will introduce the reader to a number of important proteins in both metal metabolism and oxidative stress, with an emphasis on the brain. Potential pharmacological targets will be considered.

The toxicity of depleted uranium.

Depleted uranium (DU) is an emerging environmental pollutant that is introduced into the environment primarily by military activity. While depleted uranium is less radioactive than natural uranium, it still retains all the chemical toxicity associated with the original element. In large doses the kidney is the target organ for the acute chemical toxicity of this metal, producing potentially lethal tubular necrosis. In contrast, chronic low dose exposure to depleted uranium may not produce a clear and defined set of symptoms. Chronic low-dose, or subacute, exposure to depleted uranium alters the appearance of milestones in developing organisms. Adult animals that were exposed to depleted uranium during development display persistent alterations in behavior, even after cessation of depleted uranium exposure. Adult animals exposed to depleted uranium demonstrate altered behaviors and a variety of alterations to brain chemistry. Despite its reduced level of radioactivity evidence continues to accumulate that depleted uranium, if ingested, may pose a radiologic hazard. The current state of knowledge concerning DU is discussed.

The effects of motivational interviewing on physiological outcomes.

This study examined the effects of a motivational interviewing (MI) intervention on physiological outcomes among hyperlipidemic persons randomly assigned to an MI (n = 12) or an attention-control (AC; n = 12) group. Lipid and cardiorespiratory fitness levels were measured pre- and postintervention. The MI intervention was significant in reducing total cholesterol and low-density-lipoprotein cholesterol but not in increasing VO(2max) when compared with the AC group. Contrary to what was expected, the MI intervention significantly reduced high-density-lipoprotein cholesterol. Although this study was limited by a small sample size, findings suggested that an MI telephone session can have a positive effect on lipid profiles and fitness levels.

The evolution of depleted uranium as an environmental risk factor: lessons from other metals.

Depleted uranium (DU) is used in both civilian and military applications. Civilian uses are primarily limited to ballast and counterweights in ships and aircraft with limited risk of environmental release. The very nature of the military use of DU releases DU into the environment. DU released into the environment from military use takes the form of large fragments that are chemically unchanged and dust in the form of oxides. DU dust is nearly insoluble, respirable and shows little mobility in the soil. Exposure to DU occurs primarily from inhalation of dust and possible hand to mouth activity. Toxicity of DU is believed to be primarily chemical in nature with radiological activity being a lesser problem. DU has been shown to have a variety of behavioral and neurological effects in experimental animals. DU has been used the Balkans, Afghanistan, and both Iraq wars and there is a high probability of its use in future conflicts. Further, other nations are developing DU weaponry; some of these nations may use DU with a greater radiological risk than those currently in use. The toxicity of DU has been studied mostly as an issue of the health of military personnel. However, many tons of DU have been left in the former theater of war and indigenous populations continue to be exposed to DU, primarily in the form of dust. Little epidemiological data exists concerning the impact of DU on these groups. It may be possible to extrapolate what the effects of DU may be on indigenous groups by examining the data on similar metals. DU has many similarities to lead in its route of exposure, chemistry, metabolic fate, target organs, and effect of experimental animals. Studies should be conducted on indigenous groups using lead as a model when ascertaining if DU has an adverse effect.

Effects of short-term and long-term depleted uranium exposure on open-field behavior and brain lipid oxidation in rats.

Male and female rats were exposed to depleted uranium acetate (DU) in drinking water at doses of 0, 75, or 150 mg/L for either 2 weeks or 6 months. After exposure, the animals were tested for behaviors in the open-field. After testing in the open-field, the brains were examined for levels of lipid oxidation using the thiobarbituric acid (TBA) assay. Behavioral differences (line crossing and rearing) were seen in male rats after 2 weeks exposure to DU in drinking water for the highest dose group. Increased brain lipid oxidation was seen for the highest dose group for both genders. Lipid oxidation levels correlated significantly with line crossing and rearing in the open-field. After 6 months exposure, behavioral differences for male rats in the open-field remained and expanded to include other behaviors (grooming, defecation, and urination). Female rats also demonstrated some behavioral changes after 6 months exposure. Lipid oxidation in the brain continued to be seen; however, these levels no longer correlated with open-field behaviors. These data suggest that DU is a toxin that crosses the blood-brain barrier, producing behavioral changes in male rats and lipid oxidation regardless of gender in as little as 2 weeks in the rat. Longer exposures to DU may produce greater behavioral changes but compensatory mechanisms may reduce the effects of lipid oxidation. Males appear to be more sensitive to the behavioral effects of DU.

Acute physiologic and chronic histologic changes in rats and mice exposed to the unique hallucinogen salvinorin A.

Salvinorin A is a unique hallucinogen that is seeing increased use in humans. It is not currently a controlled substance and is used as a legal alternative to controlled substances. Usually smoked or buccally absorbed by chewing, doses of approximately 200 mcg can produce profound hallucinogenic effects of short duration. The mechanism of action of salvinorin A is at the kappa-opioid receptor. Little data is available on the medical effects of this substance so animal studies were undertaken to explore the acute toxic effects of this substance in rats and the chronic effects in mice. Rats were anesthetized and administered salvinorin A at 1600 mcg/kg or vehicle. Recordings were made of galvanic skin response, EKG, temperature, and pulse pressure for 100 minutes. Mice were chronically exposed to vehicle or 400, 800, 1600, 3200, or 6400 mcg/kg of salvinorin A for two weeks. After exposure the animals were sacrificed and brain, heart, kidney, bone marrow, blood and spleen were removed, fixed, sectioned, stained and examined by light microscopy. No effects were seen on cardiac conduction, temperature, or galvanic skin response. A nonsignificant rise was seen in pulse pressure. Histologic studies of spleen, blood, brain, liver, kidney, and bone marrow did not find any significant histologic changes at any of the doses examined. These data suggests that the toxicity of salvinorin A is relatively low, even at doses many times greater than what humans are exposed to. However, further studies should be done on blood pressure effects. The psychological impact of this potent hallucinogen should also be investigated.