Measurement of phycocyanin fluorescence as an online early warning system for cyanobacteria in reservoir intake water

Cyanobacterial blooms in drinking water reservoirs may cause a variety of water quality problems, including those of taste and odor, and can compromise the water supply destined for human consumption. In response to this problem an online monitoring tool for analyzing the cyanobacterial concentration in intake water is of practical value. This study demonstrated a positive correlation between phycocyanin fluorescence and cyanobacterial biomass during Microcystis aeruginosa blooms in a lowland drinking water reservoir, using online detection. The highest correlation coefficients were found for a cyanobacterial biomass concentration below 15 mg freshweight/L, indicating that this method can be an effective early warning system. Rapid changes in fluorescence were observed when wind drift moved higher cyanobacterial concentrations into the water intake, indicating that fluorescence could be employed as a quick warning for changed requirements for plant operations.     

Transfer of learning to compensate for impairment by alcohol and visual degradation

Rationale Past research on social drinkers shows that prior experience performing a task in a visually degraded environment results in the reduction of alcohol-induced impairment. It is possible that task experience under alcohol might similarly carry over to reduce impairment from visual degradation. Objectives The purpose of this study was to test the symmetry of the transfer of learning between two distinct sources of impairment, visual degradation and alcohol. Materials and methods Psychomotor impairment was measured by a pursuit rotor tracking task. Forty two participants were randomly assigned to one of six treatment groups. Two groups were tested under alcohol after having prior task experience performing with or without visual degradation. Two groups were tested under visual degradation after having prior task experience performing under active (0.65 g/kg) or inactive (placebo) doses of alcohol. The remaining two groups served as controls that tested the learning effects of repeating each active treatment. Results Clear evidence for asymmetrical transfer of learning was observed. Prior task experience with visual degradation reduced the impairing effects of alcohol. By contrast, prior task experience under alcohol had no effect on impairment produced by visual degradation. Conclusions Evidence for differential transfer of learning to compensate for alcohol- and visual-degradation-induced impairment is of practical interest, given that the two disturbances commonly co-occur outside the laboratory. Reasons for the asymmetry are unclear, and likely involve differences in mechanisms by which each treatment impairs psychomotor function.     

Dissociation of wanting and liking for alcohol in humans: a test of the incentive-sensitisation theory

RATIONALE: Incentive sensitisation theory (IST) claims that the mechanism of reward is comprised of separate neurobiological systems of wanting and liking, that dependent drug use occurs as a result of sensitisation of the system controlling wanting, and that the two systems can be dissociated. OBJECTIVE: To test the IST prediction that wanting and liking for alcohol can be dissociated in humans. METHODS: Measures of wanting and liking for alcohol were obtained in three experiments. Experiment 1 examined whether liking for alcohol was associated with levels of wanting, as indexed by self-reported weekly alcohol intake. Experiments 2 and 3 also assessed the association between liking and wanting but in these experiments wanting was also indexed by alcohol consumption in the laboratory. Experiment 2 increased wanting for alcohol using an alcohol priming dose to determine whether liking would be similarly affected. Experiment 3 reduced liking for alcohol by adulterating drinks with Tween to see whether wanting would also be reduced. RESULTS: Little evidence for an association between liking and wanting for alcohol was found in Experiments 1-3 but, collapsing across all experiments, a weak positive correlation between liking and wanting was found. However, in Experiment 2, wanting was increased by the alcohol priming dose whereas liking was not and in Experiment 3 liking was reduced without a concurrent reduction in wanting. CONCLUSIONS: Although correlations between wanting and liking can be observed these results support the contention of the IST that wanting and liking for alcohol can be dissociated in human participants.     

Memory encoding and retrieval on the ascending and descending limbs of the blood alcohol concentration curve

Rationale Little is known about acute effects of alcohol on memory encoding and retrieval on different limbs (ascending and descending) of the blood alcohol concentration (BAC) curve. Objectives This extensive experiment was designed to examine alcohol's effects on memory encoding and retrieval throughout a protracted drinking episode. Methods In a 9-h session, male participants consumed either alcohol (1 ml/kg) or placebo (n=32/32) over a period of 90 min and learned various materials in different memory tasks before, during, and after consuming the drinks, while their BAC levels were monitored. A week later, in a similar session, they were tested on learned materials before, during, and after drinking. Mood was assessed throughout both sessions. Results Alcohol impaired recall of words more than recognition, and cued recall most severely. Perceptual priming and picture recognition were not affected by alcohol. Alcohol impaired encoding in cued recall, recognition of completed word fragments, and free recall regardless of limb, but impaired retrieval in word recognition only during the ascending BAC. Alcohol increased negative mood on the descending limb during the first session, and on the ascending limb during the second session. Conclusions Under naturalistic drinking conditions, alcohol's effects on memory depend on task, memory process, and limb of the BAC curve. The differential effects of alcohol on retrieval during the ascending and descending limbs demonstrate the importance of examining the differential effects on the two limbs.     

Leptin and post-prandial satiety: acute central leptin more potently reduces meal frequency than meal size in the rat

Rationale Many attempts to understand ingestion have sought to clarify the control of meals. Little is known about the effects of the anorexogenic hormone leptin on meal patterning.Objective The present study sought to perform a dose–response analysis of the effects of acute central leptin administration on meal patterning using a validated, objective meal definition and to compare these results to those obtained with a previously used, subjective meal definition.Methods To validate the objective meal definition pharmacologically, the microstructural effects of the well-studied compound fenfluramine (SC 0, 1, 2, 4 mg/kg) on spontaneous nocturnal intake were determined in mature, non-deprived male Wistar rats (n=8) using a full Latin square design. The effects of intracerebroventricular leptin administration (0, 0.3, 1, 3, 6.25 g; n=10) were also examined, and perceived meal patterns obtained from the objective and subjective definitions were compared.Results Fenfluramine reduced meal size and eating rate at doses that did not reduce meal frequency or duration. In contrast, comparably anorectic doses of leptin had potent post-meal satiety-like effects, reducing meal frequency and prolonging the intermeal interval without reducing average meal size, a finding opposite to that suggested by the previously used subjective meal definition. Unlike comparably and more anorectic doses of fenfluramine, leptin non-specifically reduced both prandial and non-prandial drinking.Conclusions Acute increases in central leptin levels may potently augment post-prandial satiety and influence body-fluid homeostasis. The results reveal unappreciated central modes of action for the ob protein which qualitatively differ from the intra-meal satiating-like effects of fenfluramine.     

A single injection of the kappa opioid antagonist norbinaltorphimine increases ethanol consumption in rats

Rationale Kappa opioid receptor (KOR) agonists interfere with the reinforcing effects of drugs of abuse. KOR agonists decrease heroin, cocaine, and ethanol self-administration, and block heroin and cocaine conditioned place preference (CPP) in rats. However, KOR agonists also produce emesis and dysphoria, making it difficult to determine if their effects on self-administration are due to an action on reward mechanisms or are secondary to the drug's direct aversive effects. Assuming that endogenous KOR ligands modulate circuits involved in drug and alcohol reward, selective KOR antagonists can be used to clarify these issues. If KOR antagonists increase drug self-administration then it is likely that endogenous KOR agonists directly modulate drug intake. Objectives To determine the effects of nor-BNI, the highly selective KOR antagonist, on ethanol consumption and CPP. Methods Thirty-eight male Lewis rats were given free access to ethanol until stable self-administration was achieved. Animals were then administered a single injection of nor-BNI (10 mg kg⁻¹) while ethanol intake was monitored. Results A single injection of nor-BNI induces a long-lasting increase in ethanol consumption, but does not induce a CPP. A high/low split revealed that this effect was primarily due to an increase in drinking in nor-BNI-treated high drinkers, which drank significantly more than saline-treated high drinkers and also drank significantly more when compared to their own pretreatment baseline. Conclusions Blocking the KOR system increases ethanol self-administration, suggesting that the decrease in self-administration seen with KOR agonists is due to a direct modulation of reward circuitry.     

Voluntary alcohol intake in two rat lines selectively bred for learned helpless and non-helpless behavior

Rationale A high comorbidity between depression and alcoholism has been reported in several studies, but the mechanisms underlying this relationship remain unknown.Objectives We tested whether learned helplessness in rats as a model for depression is associated with enhanced alcohol intake and relapse behavior.Methods Congenital learned helplessness (cLH) and congenital non-learned helplessness (cNLH) rats were selectively bred for differences in an escape paradigm. Sucrose preference was tested at the first hour of the dark phase. In order to study an association with alcohol drinking behavior, rats underwent a free-choice procedure with access to water, and 5% and 20% alcohol solutions for 6 weeks. After acquisition of alcohol drinking behavior, the alcohol deprivation effect (ADE) was assessed. Sensitivity to the sedative-hypnotic effect of alcohol was measured by loss of the righting reflex.Results cLH rats showed significantly lower preference for sucrose solutions during the second half hour of the dark phase than cNLH rats. Alcohol intake of male cLH rats was not significantly different from that of male cNLH rats. In contrast, cLH female rats consumed higher amounts of alcohol than female cNLH rats. The ADE was more pronounced in female animals, although the magnitude of the ADE was similar in both cNLH and cLH female rats. The time to regain the righting reflex was significantly higher in both male and female cLH rats than in cNLH rats.Conclusions In summary, these data suggest that an inborn depressive-like behavior in female rats is associated with enhanced alcohol intake.     

Drinking patterns and traffic casualties in Switzerland: matching survey data and police records to design preventive action

OBJECTIVE: To examine the association between drinking patterns and alcohol-related traffic casualties. STUDY DESIGN: Data linkage of cross-sectional survey data on alcohol consumption with official traffic casualty records. METHODS: Alcohol consumption measures for usual heavy drinking and risky single occasion drinking were derived for different time segments of the day from a 7-day drinking diary study of 747 current drinkers. Measures were correlated with official records of alcohol-related traffic casualties. RESULTS: There was a high correlation between alcohol-related traffic casualties and the number of risky single occasion drinkers that consumed alcohol outside their homes (r=0.92). On average, about 50% of these drinking occasions were attributed to usual moderate drinkers. The proportion of usual heavy drinkers was lowest in the time segments with the most alcohol-related casualties. CONCLUSION: Preventive countermeasures should be targeted at the general population, enforced particularly during specific periods of the week.     

Examining the Effects of Fatal Vision Goggles on Changing Attitudes and Behaviors Related to Drinking and Driving

This study investigated the effectiveness of the Fatal Vision goggles. College students (N = 251) were randomly assigned to one of four groups including two control groups, a group wearing the goggles, and a group watching those wearing the goggles. Attitudes and behaviors toward drinking and driving were assessed immediately prior to and after the intervention, and then again at a four-week follow up. The group wearing the goggles reported significantly greater declines in accepting attitudes toward drinking and driving compared to the other groups at the immediate post-test. However, these differences disappeared after four weeks. Also, the change in attitude was not accompanied by a similar decrease in drunk driving behaviors. Editors Strategic Implications: School and agency administrators, seeking to reduce unacceptably high rates of drinking and driving, will benefit from this well-designed longitudinal experiment. Replication will be necessary, but the authors present strong evidence that this is a prevention strategy that does not result in behavioral change.     

Alcohol drinking and colorectal cancer: A population-based prospective cohort study in China

Study objective: To asses the association between alcohol consumption and the risk of colorectal cancer (CRC) in the Chinese population. Design: A population-based prospective cohort study was initiated from the colorectal cancer screening population in Jiashan County in 1989–1990. The drinking habits of individuals were investigated with demographic information. Setting: A cohort study was followed-up from 1st May 1990 to 1st January 2001 and censored at the date of diagnosis of CRC, at death from any causes, or at 1st January 2001, whichever came first, and the person-time was computed. Participants: Two hundred and forty two CRC patients were diagnosed during the study period and 64,100 individuals finished the follow-up. Results: The distribution of sex, smoking status, occupation, education level and marital status were all significantly different among different drinking habits at baseline. When the above factors were adjusted, no significant association was observed between alcohol consumption and the risk of CRC. Exclusion of individuals diagnosed cancer less than 1 year after the examination date did not alter the strength of an alcohol–CRC relationship. Further analysis in sex strata also did not show a significant relationship. Conclusions: Alcohol drinking may not be associated with a higher risk of CRC in the Chinese population.This revised was published online in April 2005. In the previous version the article category was missing.