Does ecological release from distantly related species affect phenotypic divergence in brook charr?

Ecological opportunity occurs when a resource becomes available through a decrease of interspecific competition and another species colonizes the vacant niche through phenotypic plasticity and intraspecific competition. Brook charr exhibit a resource polymorphism in some Canadian Shield lakes, where a littoral ecotype feeds mainly on zoobenthos and a pelagic ecotype feeds mostly on zooplankton. The objectives of this study were to test that (i) resource polymorphism is common in these brook charr populations, (ii) the presence creek chub and white sucker, two introduced species competing with brook charr for littoral resources, will decrease the phenotypic divergence between the two brook charr ecotypes, and (iii) the ecological release from introduced species will increase population and/or individual niche widths in brook charr. The study was based on 27 lakes and five indicators of resource use (stomach content, liver δ13C, muscle astaxanthin concentration, pyloric caecum length, and gill raker length). Our results indicate that within-lake differences in resource use by both ecotypes are common and stable through time. When facing interspecific competition, both littoral and pelagic brook charr incorporated more pelagic prey into their diet but maintained the amplitude of their differences in resource use, which contradicts our second prediction. Finally, we did not find any significant effect of introduced species on population and individual niche widths of brook charr. We suggest that the difference in feeding mode among distantly related competitors could prevent the complete exclusion of a species from a given niche and explain the lack of response to the ecological release.

Attention and non-REM sleep in neuroleptic-naive persons with schizophrenia and control participants.

The relationship between sleep architecture and attentional performance was evaluated in neuroleptic-naive patients with schizophrenia and healthy controls. Participants were recorded in a sleep laboratory for two consecutive nights after which selective and sustained attention performance was tested. In both groups of participants, Spearman's rho statistics revealed a negative correlation between reaction time on the selective attention task and sleep spindle density. Only control participants showed a negative correlation between reaction time and duration of stage 2 sleep and a positive correlation between reaction time and duration of stage 1 ("light") sleep. Only persons with schizophrenia showed a negative correlation between reaction time and duration of stage 4 ("deep") sleep. In the sustained attention task, we found no correlation between reaction time and sleep for control participants while persons with schizophrenia showed a negative correlation between reaction time and duration of stage 4 sleep. It is proposed that EEG sleep spindle activity is associated with automatic attentional processing, while stage 2 sleep continuity in healthy individuals and percentage of stage 4 in patients with schizophrenia are associated with voluntary processes. These results support the existence of a relationship between non-rapid-eye-movement sleep and cognitive performance in healthy individuals as well as in persons with schizophrenia.

Youth gambling behaviors: an examination of the role of resilience.

The study of resilient children has overturned many deficit-focused models concerning the ontogenesis of children raised in adversity. This study explored the relationship between risk and protective factors, resilience, and youth gambling behavior. More specifically, this study examined the relative contribution of various risk and protective domains in relation to problem gambling behavior and examined whether youth identified as resilient (high risk exposure-high internalized protection) were as likely as those identified as vulnerable (high risk exposure-low internalized protection) to engage in excessive gambling behavior. The sample consisted of 1,273 students ages 12 to 19. The findings demonstrated that risk and protective factors each provide a unique contribution to the prediction model of gambling problems. Resilient and vulnerable youth differed significantly in their self-reported gambling severity. As well, resilient youth were not statistically distinguishable from low-risk exposure groups in terms of their gambling severity. Findings are interpreted with respect to resilience and prevention research.

Risk, compensatory, protective, and vulnerability factors related to youth gambling problems.

This study explores the additive (i.e., risk or compensatory) or moderating (i.e., protective or exacerbating) role of individual resources (social bonding, personal competence, and social competence) and environmental risk (family, peers, and neighborhood) in regard to the association between established personal risk attributes (i.e., impulsivity, anxiety) and youth gambling problems. Using a cross-sectional design, regression analyses indicated that among a sample of mostly first-generation immigrant adolescents from low-income homes (N = 1,055; M = 15.03; SD = 1.64), social bonding was associated with a decrease in gambling problems (odds ratio [OR] = 0.15, p < .01) while peer and neighborhood risk were associated with an increase in gambling problems (OR = 2.24, p = .01 and OR = 2.31, p = .01, respectively), net of personal risk attributes. In terms of protective processes, no putative moderating effect was found for composite individual resources. The findings are discussed with respect to the roles of compensatory, risk, and protective processes.

Specific symptomatic changes following donepezil treatment of Alzheimer's disease: a multi-centre, primary care, open-label study.

BACKGROUND: Standard measurement scales used in anti-dementia trials may not capture symptomatic changes recognized by clinicians and caregivers. We studied a symptom checklist, completed separately by caregivers and by clinicians, to identify patterns of change associated with donepezil treatment. METHODS: In a multi-centre, 6-month, open-label study of 101 primary care patients, changes in a 19-symptom checklist were assessed in relation to changes in standardized scales of cognition, activities of daily living, behavior, and caregiver burden. RESULTS: Three symptoms were reported in more than 80% of patients by both clinicians and caregivers: problems in remembering, (97%), temporal orientation (89%), and repetitiveness (85%). Five others overlapped on each of the clinician and caregiver 'top ten', including cognitive activation, spatial orientation, leisure, attention, and apathy. Clinicians reported that symptoms did not improve in 38 patients, whereas there was some improvement in 43, and improvement in most symptoms in 20. Caregivers reported that symptoms did not improve in 55 patients, whereas 27 and 19 patients showed some and most symptoms improving respectively. Patients with the greatest symptomatic improvement also improved most on the ADAS-Cog and the other standardized measures, whereas no improvement (or decline) in each standardized measure was observed in people whose symptoms worsened or did not improve. CONCLUSION: A symptom checklist allowed clinically meaningful profiles to be identified, but revealed different estimates of response between clinicians and caregivers. Both agreed that improved executive function was the most common response. A symptom checklist can help translate between standard measures and everyday practice.

The application of youth substance use media campaigns to problem gambling: a critical evaluation.

Despite the negative impact that problem gambling poses on individuals and society there have been few gambling prevention campaigns specifically targeting youth. The authors review the literature on past and current drug, alcohol, and tobacco use prevention media campaigns, examining the similarities across 25 health communication programs with the aim of viewing their applicability for the prevention of youth problem gambling. Critical features of effective campaigns are identified and assessed in terms of their applicability for youth problem gambling. Recommendations for the design, implementation, and evaluation of a youth gambling media campaign are discussed.

Potential treatment effects of donepezil not detected in Alzheimer's disease clinical trials: a physician survey.

OBJECTIVES: Clinical trials of the cholinesterase inhibitor donepezil have used standard psychometric tools to evaluate treatment efficacy. These trials, however, appear not to capture clinically demonstrable, but otherwise unmeasured, beneficial treatment effects. We sought to identify and categorize clinically recognizable effects of donepezil treatment in Alzheimer's disease. METHODS: A list of potential effects was developed using clinical trials data and the experience of an expert panel. These were incorporated in a questionnaire, which was tested with a focus group, revised and then used in a postal survey of physicians. Data were classified by cognitive domain, and reviewed by a second panel. RESULTS: Items that were most often rated as being improved were related to frontal systems function, including attentional capacity and initiative. Behavioral symptoms that were among the highest rated items were apathy, mood, and agitation. The top two other items were social interactions and involvement in domestic activities. Of the top ten symptomatic treatment effects, only four appeared to be readily identified by current standard measures. CONCLUSIONS: Physicians recognize as important several treatment effects that are not well captured by current standard measures. New methods are needed to capture such effects, which also have the potential to offer insight into the neurobiology of the human cholinergic system.

Twinning in tufted capuchins (Cebus apella): rate, survivorship, and weight gain.

We calculated the rate of twinning across four captive collections of tufted capuchins (Cebus apella) to be 2.4%. This rate contrast with previous reports that twinning in tufted capuchins is rare. Additionally, we present data on the survival and weight gain of twins in this species as compared to singletons. Twins face their greatest risk of mortality on or before the first day of life, when 45% will die compared to 16% of singletons. After the first day of life, twins and singletons demonstrate comparable survival rates. This, in conjunction with the finding that at no time during the first year of life do twins and singletons differ significantly in their weights, suggests that twinning is a viable reproductive form for these animals, especially in the captive setting where nutritional demands are met.

Relationship between platelet-activating factor concentration in rhesus monkey (Macaca mulatta) spermatozoa and sperm motility.

Platelet-activating factor (PAF) is a potent signaling phospholipid that has been implicated in a number of biological activities. PAF concentration in primate spermatozoa has a positive correlation with fertility. While PAF is present in rhesus spermatozoa, there are no relational reports on its concentration and the cell's motility. The study objective was to determine if PAF concentration in rhesus spermatozoa was correlated with motility indices (percent motility and forward progression). Semen was collected from sexually mature males and cell counts, and percent motilities and forward progressions were recorded prior to PAF measurement by radioimmunoassay. Spermatozoa-derived PAF concentration ranged from a low of 0.9 picomoles/10(6) cells to a high of 13.0 picomoles/10(6) cells. The overall mean (+/-SEM) PAF concentration was 4.6 (+/-1.6) picomoles/10(6) spermatozoa. Regression analysis revealed a positive and significant relationship between PAF concentration in the spermatozoa and percent motility (R2 = 0.914; P < 0.01) as well as forward progression (R2 = 0.849; P < 0.05). A receiver-operator characteristic curve and the calculation of the probability that a positive forward progression will be predicted indicated a cutoff limit of 1.5 picomoles/10(6) cells for PAF concentration in rhesus sperm. Rhesus monkey spermatozoa motility was significantly greater (P < 0.01) in the high-PAF (> or =2 picomoles/10(6) cells) group (31.0 +/- 7.6) than in the low-PAF (<2 picomoles/10(6) cells) group (6.8 +/- 2.1). Rhesus monkey spermatozoa forward progression was significantly greater (P < 0.05) in the high-PAF (> or =2 picomoles/10(6) cells) group (3.0 +/- 1.0) than in the low-PAF (<2 picomoles/10(6) cells) group (0.7 +/- 0.3). The data demonstrate that PAF concentration in rhesus spermatozoa has a significant relationship with percent motility and the cell's forward progression. Determining PAF concentration in spermatozoa may be a significant predictor of fertility in the primate. Additional studies will elucidate the role of PAF in spermatozoa function and the significance PAF plays in primate fertility.