Effects of environmental noise pollution on perceived stress and cortisol levels in street vendors

The present study describes and analyzes experimental results of a study performed with street vendors exposed to noise pollution by monitoring daily variations in cortisol levels taking into account the influence of variables such as age and body mass index (BMI). The study was conducted with 17 male street vendors, inhabitants of Uberlândia – Brazil, who work in the central region of the city. The levels of exposure to noise were assessed using an audio dosimeter and, every two hr, samples of saliva were collected for determination of salivary cortisol levels through an enzymatic immunoassay. The measured equivalent A-weighted sound level (LAeq) ranged from 70.2 to 76.6 dB (A) during the monitoring period of endogenous salivary cortisol levels. Morning levels of cortisol in street vendors were higher in older and overweight individuals. The noise levels to which the subjects were exposed were above the acoustic comfort threshold established by the World Health Organization and hence may be associated with severe discomfort and stress     

Effects of sea water pollution on chicken embryos.

Organic matter and heavy metal contamination in sea water obstruct vital functions of chicken embryos and interrupt their growth. Histological examination of contaminated fetuses showed a menacing growth of abnormal protuberances in the lungs as well as highly impeded formation of capillaries, although the windpipes exhibited normal expansion. Compared with controls, liver tissue also showed retarded growth accompanied by decrease in liver weight. Consequently, vital metabolic functions were impaired, hydropsy and evisceration developed, and fetuses were deformed.     

Effects of apomorphine on self-stimulation behavior

Self-stimulation behavior was studied in untreated rats and rats injected with apomorphine with electrodes implanted in the nucleus accumbens, the lateral hypothalamus, the catecholaminergic cell-groups A9–A10 and the locus coeruleus.Apomorphine (0.2 mg/kg s. c.) consistently facilitated self-stimulation in a number of rats but inhibited this behavior in others.This individual variation could be observed in all four groups of rats but was further analysed in the rats with an electrode in the A9–A10 area. The effect of the drug was highly reproducible for individual animals.Extinction after reduction of the rewarding current to zero could not be demonstrated as long as the drug was active.These results substantiate the hypothesis that apomorphine is able to replace the reinforcing action of intracranial rewarding stimulation.     

Effects of drugs on avoidance behavior

Summary Thirty-five rats were observed on two occasions in a novel environment, and then trained in a Sidman avoidance response. Each was tested in the avoidance situation following injection of a single dose of chlorpromazine, d-amphetamine, atropine, and scopolamine.Effects of the drugs on avoidance behavior were similar to those reported in earlier studies. Changes from baseline values in response rate and shock rate under drug were found to be the best measures of individual rats' susceptibilities to the drugs.Susceptibilities to the response-stimulating effects of amphetamine, atropine and scopolamine were highly interrelated, but susceptibility to chlorpromazine was distinct. Susceptibility to chlorpromazine was greatest in rats with high baseline rates of responding and shock avoidance. Change in shock rates after administration of stimulant drugs was greatest in rats with high baseline rates of shocks (poor avoiders). Increase in response rate under the stimulants was greatest in animals that tended to groom and freeze in the novel environment, rather than boldly exploring.The effects of the stimulants are discussed in terms of a model relating to the balance of excitation versus inhibition in response to aversive stimulation. Differences in baseline avoidance rates and in susceptibilityThis experiment was supported by grant MH-04139 from The National Institute of Mental Health and by The California Department of Mental Hygiene.     

Effects of surfactants on gel behavior

The recent advances in the design and synthesis of new polymeric systems have opened a wide range of possibilities for the use of gels as drug dosage forms. These systems are able to act not only as simple reservoirs, but also as controlled-release systems and/or targeting agents for site-specific delivery. Applications of gels are determined by their drug-loading capability, rheological properties, and the mechanisms and kinetics of drug release. The incorporation of small proportions of surfactants, which are able to promote or hinder intra- or interchain polymeric bonds, may modify these properties and be a useful tool for developing gel-based dosage forms. Polymers and surfactants may interact, depending on their chemical structure, through ionic, hydrophobic and hydrogen-bonding mechanisms. The strength of the interaction is strongly affected by pH, ionic strength and presence of other substances, and physiological changes in these variables. These physiologic parameters affect the performance of polymer/surfactant gels as drug delivery systems. Surfactants may also promote cutaneous or mucosal drug penetration. Drug release processes from polymer/surfactant gels depend on the microstructure of the gel and the drug ‘state’ in the system. The drug can be: solubilized in water without interacting with any of the components; electrostatically or hydrophobically bound to the polymer; or solubilized inside micelles or polymer/surfactant aggregates. Interactions between surface-active drugs and polymers should also be taken into account because of their important repercussions on gel behavior. Finally, polymer/surfactant systems have a great potential for gene therapy, and some polymers that are able to interact with natural surfactants can be used as trap systems of bile salts for controlling the physiological levels of cholesterol.     

Effects of caffeine on human behavior.

The literature suggests that the following effects on behavior of adult humans may occur when individuals consume moderate amounts of caffeine. (1) Caffeine increases alertness and reduces fatigue. This may be especially important in low arousal situations (e.g. working at night). (2) Caffeine improves performance on vigilance tasks and simple tasks that require sustained response. Again, these effects are often clearest when alertness is reduced, although there is evidence that benefits may still occur when the person is unimpaired. (3) Effects on more complex tasks are difficult to assess and probably involve interactions between the caffeine and other variables which increase alertness (e.g. personality and time of day). (4) In contrast to the effects of caffeine consumption, withdrawal of caffeine has few effects on performance. There is often an increase in negative mood following withdrawal of caffeine, but such effects may largely reflect the expectancies of the volunteers and the failure to conduct "blind" studies. (5) Regular caffeine usage appears to be beneficial, with higher users having better mental functioning. (6) Most people are very good at controlling their caffeine consumption to maximise the above positive effects. For example, the pattern of consumption over the day shows that caffeine is often consumed to increase alertness. Indeed, many people do not consume much caffeine later in the day since it is important not to be alert when one goes to sleep. In contrast to effects found from normal caffeine intake, there are reports that have demonstrated negative effects when very large amounts are given or sensitive groups (e.g. patients with anxiety disorders) were studied. In this context caffeine has been shown to increase anxiety and impair sleep. There is also some evidence that fine motor control may be impaired as a function of the increase in anxiety. Overall, the global picture that emerges depends on whether one focuses on effects that are likely to be present when caffeine is consumed in moderation by the majority of the population or on the effects found in extreme conditions. The evidence clearly shows that levels of caffeine consumed by most people have largely positive effects on behavior. Excessive consumption can lead to problems, especially in sensitive individuals.     

Effects of hydrazine on behavior in rats

The effects of hydrazine (1–52 mg/kg) were tested on several behavioral schedules in rats. Spontaneous motor activity was depressed in a majority of the experiments; significant depression occurred at doses of 39 and 52 mg/kg. On a fixed-ratio water reinforcement schedule, hydrazine significantly decreased the running rate and increased the post-reinforcement pause at 13–39 mg/kg. Under a schedule of differential reinforcement of low rates at 3.3 mg/kg, it significantly increased the response rate and decreased the reinforcement. On a shock avoidance task, hydrazine (3.3–39 mg/kg) increased the number of shocks in the majority of the sessions, while the avoidance response showed variability. This study shows that the doses of hydrazine needed to produce behavioral effects were comparatively lower than those used in toxicologic studies and indicates the possibility of using behavioral techniques in the toxicologic evaluation of chemicals.     

Effects of alcohol on human aggressive behavior

Eleven men were administered placebo and three doses (0.12, 0.23 and 0.46 g of absolute alcohol per kg of body weight) of 50% alcohol (vodka) in a laboratory situation that provided both aggressive and nonaggressive response options. Two aggressive responses were available to subjects: the ostensible subtraction of money from a fictitious other person and the ostensible presentation of a loud noise to a fictitious other person. A nonaggressive monetary reinforced response was also available. Aggressive responding was elicited by the subtraction of money from the subjects which was attributed to the fictitious other person. Relatively low doses of alcohol (0.23 and 0.46 g/kg) increased aggressive monetary subtraction responses, but had no effect on decreased nonaggressive monetary reinforced responses. Thus, the observed increase in aggressive responding cannot be attributed to a generalized stimulant action of low alcohol doses. The increased aggressive responding was observed at blood alcohol levels well below those usually defined as intoxicating. It is suggested that responses to aggression-provoking situations can be altered by the consumption of the equivalent of one or two alcoholic drinks.     

Effects of d-amphetamine on human aggressive behavior

Male research subjects were administered placebo and three doses of d-amphetamine (5, 10 and 20 mg/70 kg) in a laboratory situation which provided both aggressive and non-aggressive response options. The non-aggressive response was button pressing maintained by presentation of points exchangeable for money at the end of the session. The aggressive response was button pressing on a separate manipulanda which ostensibly subtracted points from a fictitious partner. Aggressive responding was elicited by subtracting points from the research subjects which was attributed to the fictitious partner. d-Amphetamine increased both aggressive and non-aggressive responding, particularly at 5 and 10 mg/70 kg. At the highest dose (20 mg/70 kg), aggressive responding decreased to levels similar to those observed during placebo sessions, while monetary reinforced responding remained elevated.     

Effects of drugs on nondiscriminated avoidance behavior

Summary Thirteen male, Long-Evans rats were trained to press a lever to postpone a brief electric shock. Each rat was subjected to several different doses of chlorpromazine, d-amphetamine, atropine and benactyzine, and then tested for four hours under a mixed schedule of extinction and nondiscriminated avoidance behavior. In comparison with interspersed control sessions, chlorpromazine produced a consistent depression. Amphetamine increased response rates at moderate doses, and led to severely toxic reactions at higher doses. The three anticholinergic drugs produced qualitatively similar reactions within rats, but very different patterns of response between rats. Most animals showed higher response rates, but a few were depressed.Rats differed markedly in their response to all of the drugs. Both quantitative differences in the dosage necessary to produce a common effect and qualitative differences in the pattern of response to the drug were seen.Supported by research grant No. MY-4139 from the National Institute of Mental Health and by the California Department of Mental Hygiene.     

Effects of phencyclidine on aggressive behavior in mice

The effects of phencyclidine on aggressive behavior in mice and the possible mechanism of action for these effects were examined. PCP at a dose of 10.0 mg/kg significantly decreased the number of attacks by resident mice toward intruders. Significant increases in the number of attacks by non-drugged residents toward the intruders who were given high doses of PCP (6.0 and 10.0 mg/kg) were observed. Only the higher doses of PCP (6.0 and 10.0 mg/kg) significantly increased the duration of locomotion. The increase in locomotion was dependent upon the time after administration of the drug. Hyperactivity was present at 30 minutes for both doses and hypoactivity was present at three hours after administration of 3.0 mg/kg. PCP did not significantly alter the frequency of attacks in an unfamiliar test locale. Pretreatment with haloperidol (1 mg/kg) partially blocked the PCP-induced hyperactivity but pretreatment with methysergide (3 mg/kg) did not. Neither haloperidol nor methysergide blocked the suppressive effects of PCP on aggressive behavior. It is concluded that PCP does not increase aggressive behavior in mice but high doses will decrease aggression. PCP-treated intruder animals provoke more aggression by non-drugged animals. PCP-induced hyperactivity appears to be mediated by dopaminergic systems.     

Effects of chlorpromazine on food-maintained and observing behavior

Pigeons were trained to peck each of two response keys. Periods during which pecks on one key (the food key) produced access to grain according to a random-ratio 80 schedule alternated irregularly with periods during which food-key responses had no scheduled consequences (extinction). Both keys remained amber unless a random-ratio 8-response requirement on the second key (the observing key) was met. Completion of the observing-response requirement darkened the observing key and illuminated the food key either red or green for 15 s, depending on whether food could be obtained by pecking the food key. Food-key response rate was high and constant when food could be obtained (and the key was illuminated red). Observing-key response rate was somewhat lower but also constant when the observing key was amber, and near zero otherwise. Increasing doses of chlorpromazine (0.03–17.0 mg/kg, IM) decreased food-key response rate, but sometimes increased observing-key response rate. Additionally, larger doses were required to decrease response rate on the observing key. The differential effect of chlorpromazine upon the two performances may have been due to differences in reinforcer type (conditioned versus unconditioned) or other aspects of reinforcement.     

Effects of river pollution on the colonisation of artificial substrates by macrozoobenthos

The impact of pesticides on macrobenthos communities was studied on two aquatic environments in Northern Italy; River Meolo, a site exposed to agricultural pollution, and River Upper Livenza a low pollution reference site. Colonisation of artificial substrates was compared throughout the productive season. The relevance of multiple environmental stressors other than pesticides (e.g. oxygen depletion) was also assessed. Biochemical indicators (enzyme and metabolite biomarkers) were measured on selected organisms. Biomarker results (acetylcholinesterase, glutathione S-transferase, and napthylacetate esterase), as well as community structure patterns, revealed a significant difference between the two rivers. Cause-effect relationships between results and multiple stress factors were discussed.     

Effects of diazepam on operant behavior in man

The effects of diazepam (10 mg orally) on the responding of normal human volunteers was studied in a procedure that involved the maintenance of operant behavior by monetary reinforcement and its suppression by monetary loss (punishment). Diazepam produced an antipunishment effect as shown by an increase in behavior suppressed by monetary loss. An analogy to animal procedures that selectively detect antianxiety drugs is apparent.     

Effects of amphetamine on choice behavior of pigeons

Key-pecking behavior of three pigeons was maintained by concurrent variable-interval, variable-interval schedules of reinforcement. Dose-response curves of amphetamine on four operants involved in the choice situation were obtained. None of the doses of amphetamine studied produced any rate-increasing effect on responding, irrespective of the differences in control baseline rates. Responding at the changeover key was relatively more depressed than main-key responding in spite of occuring at lower rates in non-drug conditions.     

Effects of some volatile sedative-hypnotics on punished behavior

Lever-press responses of rats were established under a schedule in which punished and unpunished responding alternated. Every 30th response produced food (unpunished responding) during one schedule component, while every tenth response produced both food and shock (punished responding) during an alternate schedule component. Each schedule component was correlated with a different visual stimulus. Unpunished behavior was characterized by high sustained rates which followed brief pauses after food delivery. Punished behavior occurred at less than 10% the rate of unpunished behavior. Oral administration of diazepam, ethchlorvynol, chloral hydrate, tertiary-butanol, and ethanol all produced marked dose-related increases in punished behavior at doses that decreased or had little effect on unpunished responding. Potency estimates for increasing punished responding varied over a 400-fold range. The potency ranking was diazepam > ethchlorvynol > chloral hydrate > tertiary-butanol > ethanol. Higher doses of all drugs decreased unpunished responding with relative potencies comparable to those found for doses producing maximal increases in punished responding. increases in punished behavior appear to be a characteristic feature of drugs with sedative-hypnotic properties.     

Effects of trimethyltin on homecage behavior of rats

Diurnal patterns of feeding, drinking, locomotor activity, and rearing in male Fischer-344 rats were examined for 2 weeks after a single oral dose of trimethyltin chloride (TMT) at 0, 3, 5, or 7 mg/kg. Body weights and feeding and drinking efficiency ratios (ratios of amount of food or water consumed per unit effort) were also determined daily. TMT caused a dose- and time-related drop in body weight; two of five rats in the 7 mg/kg group were killed moribund on 15 days after dosing. Feed consumption fell to 25% of control within 5 days after 7 mg/kg TMT, and to 50% of control for Days 2 and 3 after 5 mg/kg TMT. Water consumption doubled within 2 days after 7 mg/kg TMT and remained elevated for 2 weeks. Feeding efficiency dropped to 40% of control after 7 mg/kg, but drinking efficiency was unchanged. The diurnal patterns of drinking and of rearing were disrupted at all doses of TMT; a normal peak in rearing activity, occurring immediately prior to light onset, was markedly attenuated after all doses on Day 3, and at 5 and 7 mg/kg on Days 5 and 7 post-TMT. These results suggest (1) that the regulation of feed and water intake is severely compromised after a high dose of TMT, and (2) that the rat's cyclical patterns of homecage behavior are sensitive to TMT doses as low as 3 mg/kg.