Stéphane Perron

Evidence for a role of endogenous neurotensin in the initiation of amphetamine sensitization

This study was aimed at testing the hypothesis that endogenous neurotensin plays a role in the initiation of sensitization to the locomotor activating effect of amphetamine. During an initial training phase, different groups of male rats were injected on four occasions (every second day: Days 1, 3, 5 and 7) with one of three doses (40, 80 or 160 microg/kg, ip) of the neurotensin antagonist, SR-48692, or its vehicle, followed 30 min later by amphetamine (1.5 mg/kg, ip), or saline. Ambulatory, non-ambulatory, and vertical movements were measured for 2 h in photocell cages immediately following the second injection. One week after the training phase, sensitivity to amphetamine (0.75 mg/kg, ip) was tested in all the rats (sensitization test). The results show that SR-48692, when given alone, produced levels of locomotor activity that were not statistically different from control. At the low dose, it potentiated amphetamine-induced ambulatory and non-ambulatory movements, an effect observed on Day 7 but not on Day 1. On the day of the sensitization test, rats pre-exposed to amphetamine alone displayed stronger ambulatory and non-ambulatory movements than vehicle pre-exposed rats, a sensitization effect that was attenuated and prevented by SR-48692 at 80 and 160 microg/kg, respectively. The present results demonstrate that activation of neurotensin receptors by endogenous neurotensin is required for the initiation of amphetamine sensitization. They provide additional evidence that an increase in central neurotensinergic neurotransmission may lead to a lasting increased sensitivity to psychostimulant drugs.

Cardiovascular effects of sub-daily levels of ambient fine particles: a systematic review

BackgroundWhile the effects of daily fine particulate exposure (PM) have been well reviewed, the epidemiological and physiological evidence of cardiovascular effects associated to sub-daily exposures has not. We performed a theoretical model-driven systematic non-meta-analytical literature review to document the association between PM sub-daily exposures (≤6 hours) and arrhythmia, ischemia and myocardial infarction (MI) as well as the likely mechanisms by which sub-daily PM exposures might induce these acute cardiovascular effects. This review was motivated by the assessment of the risk of exposure to elevated sub-daily levels of PM during fireworks displays.MethodsMedline and Elseviers EMBase were consulted for the years 1996-2008. Search keywords covered potential cardiovascular effects, the pollutant of interest and the short duration of the exposure. Only epidemiological and experimental studies of adult humans (age > 18 yrs) published in English were reviewed. Information on design, population and PM exposure characteristics, and presence of an association with selected cardiovascular effects or physiological assessments was extracted from retrieved articles.ResultsOf 231 articles identified, 49 were reviewed. Of these, 17 addressed the relationship between sub-daily exposures to PM and cardiovascular effects: five assessed ST-segment depression indicating ischemia, eight assessed arrhythmia or fibrillation and five considered MI. Epidemiologic studies suggest that exposure to sub-daily levels of PM is associated with MI and ischemic events in the elderly. Epidemiological studies of sub-daily exposures suggest a plausible biological mechanism involving the autonomic nervous system while experimental studies suggest that vasomotor dysfunction may also relate to the occurrence of MI and ischemic events.ConclusionsFuture studies should clarify associations between cardiovascular effects of sub-daily PM exposure with PM size fraction and concurrent gaseous pollutant exposures. Experimental studies appear more promising for elucidating the physiological mechanisms, time courses and causes than epidemiological studies which employ central pollution monitors for measuring effects and for assessing their time course. Although further studies are needed to strengthen the evidence, given that exposure to sub-daily high levels of PM (for a few hours) is frequent and given the suggestive evidence that sub-daily PM exposures are associated with the occurrence of cardiovascular effects, we recommend that persons with cardiovascular diseases avoid such situations.

Home environmental factors associated with poor asthma control in Montreal children: a population-based study.

Background. Home environmental exposures may aggravate asthma. Few population-based studies have investigated the relationship between asthma control in children and home environmental exposures. Objective: Identify home environmental exposures associated with poor control of asthma among asthmatic children less than 12 years of age in Montreal (Quebec, Canada). Methods. This cross-sectional population-based study used data from a respiratory health survey of Montreal children aged 6 months to 12 years conducted in 2006 (n = 7980). Asthma control was assessed (n = 980) using an adaptation of the Canadian asthma consensus report clinical parameters. Using log-binomial regression models, prevalence ratios (PRs) with 95% confidence intervals (95% CIs) were estimated to explore the relationship between inadequate control of asthma and environmental home exposures, including allergens, irritants, mold, and dampness indicators. Subjects with acceptable asthma control were compared with those with inadequate disease control. Results. Of 980 children with active asthma in the year prior to the survey, 36% met at least one of the five criteria as to poor control of their disease. The populations characteristics found to be related with a lack of asthma control were younger age, history of parental atopy, low maternal education level, foreign-born mothers, and tenant occupancy. After adjustments, children living along high-traffic density streets (PR, 1.35; 95% CI, 1.00–1.81) and those with their bedroom or residence at the basement level (PR, 1.30; 95% CI, 1.01–1.66) were found to be at increased risk of poor asthma control. Conclusions. Suboptimal asthma control appears to be mostly associated with traffic, along with mold and moisture conditions, the latter being a more frequent exposure and therefore having a greater public health impact.

Mental health effects from urban bed bug infestation (Cimex lectularius L.): a cross-sectional study

Objective To assess whether bed bug infestation was linked to sleep disturbances and symptoms of anxiety and depression. Design Exploratory cross-sectional study. Setting Convenience sample of tenants recruited in apartment complexes from Montreal, Canada. Participants 39 bed bug-exposed tenants were compared with 52 unexposed tenants. Main outcome measures The effect of bed bug-exposed tenants on sleep disturbances, anxiety and depression symptoms measured using the Pittsburgh Sleep Quality Index, 5th subscale, Generalised Anxiety Disorder 7-item scale and Patient Health Questionnaire, 9-item, respectively. Results In adjusted models, bed bug infestation was strongly associated with measured anxiety symptoms (OR (95% CI)=4.8 (1.5 to 14.7)) and sleep disturbance (OR (95% CI)=5.0 (1.3–18.8)). There was a trend to report more symptoms of depression in the bed bug-infested group, although this finding was not statistically significant ((OR (95% CI)=2.5(0.8 to 7.3)). Conclusions These results suggest that individuals exposed to bed bug infestations are at risk of experiencing sleep disturbance and of developing symptoms of anxiety and possibly depression. Greater clinical awareness of this problem is needed in order for patients to receive appropriate mental healthcare. These findings highlight the need for undertaking of deeper inquiry, as well as greater collaboration between medical professionals, public health and community stakeholders.

Statistical modeling of the spatial variability of environmental noise levels in Montreal, Canada, using noise measurements and land use characteristics.

The availability of noise maps to assess exposure to noise is often limited, especially in North American cities. We developed land use regression (LUR) models for LAeq24h, Lnight, and Lden to assess the long-term spatial variability of environmental noise levels in Montreal, Canada, considering various transportation noise sources (road, rail, and air). To explore the effects of sampling duration, we compared our LAeq24h levels that were computed over at least five complete contiguous days of measurements to shorter sampling periods (20 min and 24 h). LUR models were built with General Additive Models using continuous 2-min noise measurements from 204 sites. Model performance (adjusted R2) was 0.68, 0.59, and 0.69 for LAeq24h, Lnight, and Lden, respectively. Main predictors of measured noise levels were road-traffic and vegetation variables. Twenty-minute non-rush hour measurements corresponded well with LAeq24h levels computed over 5 days at road-traffic sites (bias: −0.7 dB(A)), but not at rail (−2.1 dB(A)) nor at air (−2.2 dB(A)) sites. Our study provides important insights into the spatial variation of environmental noise levels in a Canadian city. To assess long-term noise levels, sampling strategies should be stratified by noise sources and preferably should include 1 week of measurements at locations exposed to rail and aircraft noise.

Review of the effect of aircraft noise on sleep disturbance in adults

Noise exposure generated by air traffic has been linked with sleep disturbances. The purpose of this systematic review is to clarify whether there is a causal link between aircraft noise exposure and sleep disturbances. Only complete, peer-reviewed articles published in scientific journals were examined. Papers published until December 2010 were considered. To be included, articles had to focus on subjects aged 18 or over and include an objective evaluation of noise levels. Studies were classified according to quality. Given the paucity of studies with comparable outcome measures, we performed a narrative synthesis using a best-evidence synthesis approach. The primary study findings were tabulated. Similarities and differences between studies were investigated. Of the 12 studies surveyed that dealt with sleep disturbances, four were considered to be of high quality, five were considered to be of moderate quality and three were considered to be of low quality. All moderate- to high-quality studies showed a link between aircraft noise events and sleep disturbances such as awakenings, decreased slow wave sleep time or the use of sleep medication. This review suggests that there is a causal relation between exposure to aircraft noise and sleep disturbances. However, the evidence comes mostly from experimental studies focusing on healthy adults. Further studies are necessary to determine the impact of aircraft noise on sleep disturbance for individuals more than 65 years old and for those with chronic diseases.

Active and uncontrolled asthma among children exposed to air stack emissions of sulphur dioxide from petroleum refineries in Montreal, Quebec: a cross-sectional study.

BACKGROUND Little attention has been devoted to the effects on childrens respiratory health of exposure to sulphur dioxide (SO2) in ambient air from local industrial emissions. Most studies on the effects of SO(2) have assessed its impact as part of the regional ambient air pollutant mix. OBJECTIVE To examine the association between exposure to stack emissions of SO(2) from petroleum refineries located in Montreals (Quebec) east-end industrial complex and the prevalence of active asthma and poor asthma control among children living nearby. METHODS The present cross-sectional study used data from a respiratory health survey of Montreal children six months to 12 years of age conducted in 2006. Of 7964 eligible households that completed the survey, 842 children between six months and 12 years of age lived in an area impacted by refinery emissions. Ambient SO(2) exposure levels were estimated using dispersion modelling. Log-binomial regression models were used to estimate crude and adjusted prevalence ratios (PRs) and 95% CIs for the association between yearly school and residential SO(2) exposure estimates and asthma outcomes. Adjustments were made for childs age, sex, parental history of atopy and tobacco smoke exposure at home. RESULTS The adjusted PR for the association between active asthma and SO(2) levels was 1.14 (95% CI 0.94 to 1.39) per interquartile range increase in modelled annual SO(2). The effect on poor asthma control was greater (PR=1.39 per interquartile range increase in modelled SO(2) [95% CI 1.00 to 1.94]). CONCLUSIONS Results of the present study suggest a relationship between exposure to refinery stack emissions of SO(2) and the prevalence of active and poor asthma control in children who live and attend school in proximity to refineries.

Socioeconomic status and environmental noise exposure in Montreal, Canada

BackgroundThis study’s objective was to determine whether socioeconomically deprived populations are exposed to greater levels of environmental noise.MethodsIndicators of socioeconomic status were correlated with LAeq24h noise levels estimated with a land-use regression model at a small geographic scale.ResultsWe found that noise exposure was associated with all socioeconomic indicators, with the strongest correlations found for median household income, proportion of people who spend over 30% of their income on housing, proportion of people below the low income boundary and with a social deprivation index combining several socio-economic variables.ConclusionOur results were inconsistent with a number of studies performed elsewhere, indicating that locally conducted studies are imperative to assessing whether this double burden of noise exposure and low socioeconomic status exists in other contexts. The primary implication of our study is that noise exposure represents an environmental injustice in Montreal, which is an issue that merits both investigation and concern.

Annoyance from road traffic, trains, airplanes and from total environmental noise levels

There is a lack of studies assessing the exposure-response relationship between transportation noise and annoyance in North America. Our aims were to investigate the prevalence of noise annoyance induced by road traffic, trains and airplanes in relation to distance to transportation noise sources, and to total environmental noise levels in Montreal, Canada; annoyance was assessed as noise-induced disturbance. A telephone-based survey among 4336 persons aged >18 years was conducted. Exposure to total environmental noise (A-weighted outdoor noise levels—LAeq24h and day-evening-night equivalent noise levels—Lden) for each study participant was determined using a statistical noise model (land use regression—LUR) that is based on actual outdoor noise measurements. The proportion of the population annoyed by road traffic, airplane and train noise was 20.1%, 13.0% and 6.1%, respectively. As the distance to major roads, railways and the Montreal International Airport increased, the percentage of people disturbed and highly disturbed due to the corresponding traffic noise significantly decreased. When applying the statistical noise model we found a relationship between noise levels and disturbance from road traffic and total environmental noise, with Prevalence Proportion Ratios (PPR) for highly disturbed people of 1.10 (95% CI: 1.07–1.13) and 1.04 (1.02–1.06) per 1 dB(A) Lden, respectively. Our study provides the first comprehensive information on the relationship between transportation noise levels and disturbance in a Canadian city. LUR models are still in development and further studies on transportation noise induced annoyance are consequently needed, especially for sources other than road traffic.

The Montreal heat response plan: evaluation of its implementation towards healthcare professionals and vulnerable populations

ObjectivesSince 2004, the Montreal heat response plan (MHRP) has been developed and implemented on the Island of Montreal to reduce heat-related health effects in the general population. In this paper, we aimed to assess the barriers and facilitators to implementation of the MHRP and evaluate the awareness of key elements of the plan by healthcare professionals and individuals from vulnerable populations.MethodsData were gathered from monitoring reports and a questionnaire administered to managers of healthcare institutions and healthcare workers in Montreal-area health and social services institutions. Individual interviews and focus groups with healthcare workers and with individuals with schizophrenia or suffering from drug or alcohol dependencies were performed. Data were categorized according to predefined subthemes. Coding matrices were then used to determine the most frequently occurring elements in the subthemes.ResultsOur results indicate that actions are progressively implemented each year in the healthcare network. Intensification of surveillance for signs of heat-related illness is the most frequently reported measure. Identification and prioritization of clientele and homecare patients are identified as a challenge, as is ensuring the availability of sufficient personnel during a heat wave. Analysis of practice and awareness in healthcare professionals reveals that preventive measures are known and applied by the personnel. Individuals from vulnerable population groups were not uniformly aware of preventive measures, and consequently, variability was observed in their application.ConclusionThe framework proposed in this study revealed valuable information that can be useful to improve plans aimed at reducing heat-related health effects in the population.RésuméObjectifsLe Plan chaleur accablante ou extrême a été développé et mis en œuvre sur l’Île de Montréal depuis 2004 dans le but d’atténuer les effets sur la santé en lien avec la chaleur chez la population générale. Cet article dresse un portrait des éléments facilitateurs et des défis rencontrés lors de la mise en œuvre du plan chaleur. L’article présente également une évaluation de la connaissance des professionnels de la santé et de la population vulnérable quant à certains éléments-clés du plan chaleur.MéthodesL’information a été recueillie à l’aide de rapports de suivi et à l’aide d’un questionnaire administré aux gestionnaires et aux professionnels de la santé œuvrant dans les institutions de santé et de services sociaux sur l’Île de Montréal. De plus, des entrevues individuelles et des groupes de discussion ont été réalisés auprès de travailleurs de la santé et auprès d’individus vivant avec la schizophrénie ou ayant des dépendances aux drogues ou à l’alcool. L’information recueillie a été catégorisée selon des thèmes prédéfinis et les éléments les plus fréquents ont été identifiés à l’aide de matrices.RésultatsL’analyse des résultats permet de constater la mise en œuvre graduelle des mesures de prévention lors d’épisodes de chaleur. La surveillance accrue des signes et symptômes des effets de la chaleur est la mesure la plus souvent mentionnée dans l’information recueillie. Les principaux défis soulignés sont l’identification et la priorisation de la clientèle et des patients à domicile ainsi que s’assurer d’un personnel suffisant lors d’un épisode de chaleur extrême. Les résultats indiquent que les travailleurs de la santé connaissent et appliquent les mesures de prévention. Quant aux résultats ayant trait aux populations plus vulnérables, l’information sur les mesures de prévention n’était pas connue de tous et conséquemment, l’application efficace de ces mesures n’était pas observée dans tous les groupes.ConclusionCet article propose une méthodologie pouvant être applicable à l’amélioration des plans de réponse pour la chaleur extrême, visant ainsi la réduction des effets de la chaleur chez la population.