Body Temperature Frequency Distributions: A Tool for Assessing Thermal Performance in Endotherms?

There is increasing recognition that rather than being fully homeothermic, most endotherms display some degree of flexibility in body temperature. However, the degree to which this occurs varies widely from the relatively strict homeothermy in species, such as humans to the dramatic seasonal hibernation seen in Holarctic ground squirrels, to many points in between. To date, attempts to analyse this variability within the framework generated by the study of thermal performance curves have been lacking. We tested if frequency distribution histograms of continuous body temperature measurements could provide a useful analogue to a thermal performance curve in endotherms. We provide examples from mammals displaying a range of thermoregulatory phenotypes, break down continuous core body temperature traces into various components (active and rest phase modes, spreads and skew) and compare these components to hypothetical performance curves. We did not find analogous patterns to ectotherm thermal performance curves, in either full datasets or by breaking body temperature values into more biologically relevant components. Most species had either bimodal or right-skewed (or both) distributions for both active and rest phase body temperatures, indicating a greater capacity for mammals to tolerate body temperatures elevated above the optimal temperatures than commonly assumed. We suggest that while core body temperature distributions may prove useful in generating optimal body temperatures for thermal performance studies and in various ecological applications, they may not be a good means of assessing the shape and breath of thermal performance in endotherms. We also urge researchers to move beyond only using mean body temperatures and to embrace the full variability in both active and resting temperatures in endotherms.

In the eye of the beholder: Assessing the water quality of shoreline parks around the Island of Montreal through citizen science.

As a part of the FreshWater Watch project aiming to promote volunteers' water monitoring in 25 cities around the world, St. Lawrence River water quality was characterized at 28 public shoreline parks around Montreal Island, Quebec, Canada. This involved training of 69 citizen scientists by researchers of the Université de Montréal in five one-day sessions. Shoreline sampling yielded 174 data points over three summers (May 2013 to November 2015). Water turbidity, nitrate and phosphate concentrations were measured in situ, together with the thickness and type of beach-cast vegetation, and the relative abundance of different types of beach litter. Data generated by citizen scientists provided 1) an overview of the water quality of the St. Lawrence and Des Prairies rivers around the Island of Montreal, 2) an estimation of the quantity and types of beach-cast aquatic plants and filamentous algae, and 3) novel insights into the distribution of the nuisance cyanobacterium Lyngbya wollei. Overall, half of the sites were classified as "good" being characterized by low turbidity, nitrate and phosphate concentrations, and little deposition of beach-cast vegetation. Lyngbya wollei was found at 57% of the sites, revealing a more frequent occurrence than initially anticipated. The amount of litter recorded along the shoreline was generally small, comprising items related to picnicking (cans/bottles), smoking, and fishing activities in most parks. Wind exposure and rain events explained a significant fraction of the variability in nutrient concentration and turbidity among sites and dates. Shoreline condition assessed from water quality and vegetation data from this study was not correlated, however, with the most serious problem of faecal coliform counts gathered by the City of Montreal. This assessment of the quality and utilization of shoreline parks provides additional information to support planning and management activities of municipalities.

Inspection of thick welded joints using laser-ultrasonic SAFT.

The detection of defects in thick butt joints in the early phase of multi-pass arc welding would be very valuable to reduce cost and time in the necessity of reworking. As a non-contact method, the laser-ultrasonic technique (LUT) has the potential for the automated inspection of welds, ultimately online during manufacturing. In this study, testing has been carried out using LUT combined with the synthetic aperture focusing technique (SAFT) on 25 and 50mm thick butt welded joints of steel both completed and partially welded. EDM slits of 2 or 3mm height were inserted at different depths in the multi-pass welding process to simulate a lack of fusion. Line scans transverse to the weld are performed with the generation and detection laser spots superimposed directly on the surface of the weld bead. A CCD line camera is used to simultaneously acquire the surface profile for correction in the SAFT processing. All artificial defects but also real defects are visualized in the investigated thick butt weld specimens, either completed or partially welded after a given number of passes. The results obtained clearly show the potential of using the LUT with SAFT for the automated inspection of arc welds or hybrid laser-arc welds during manufacturing.

Congenital esophageal stenosis associated with esophageal atresia.

Congenital esophageal stenosis (CES) is a rare clinical condition but is frequently associated with esophageal atresia (EA). The aim of this study is to report the diagnosis, management, and outcome of CES associated with EA. Medical charts of CES-EA patients from Lille University Hospital, Sainte-Justine Hospital, and Montreal Children's Hospital were retrospectively reviewed. Seventeen patients (13 boys) were included. The incidence of CES in patients with EA was 3.6%. Fifteen patients had a type C EA, one had a type A EA, and one had an isolated tracheoesophageal fistula. Seven patients had associated additional malformations. The mean age at diagnosis was 11.6 months. All but two patients had non-specific symptoms such as regurgitations or dysphagia. One CES was diagnosed at the time of surgical repair of EA. In 12 patients, CES was suspected based on abnormal barium swallow. In the remaining four, the diagnostic was confirmed by esophagoscopy. Eleven patients were treated by dilation only (1-3 dilations/patient). Six patients underwent surgery (resection and anastomosis) because of failure of attempted dilations (1-7 dilations/patient). Esophageal perforation was encountered in three patients (18%). Three patients had histologically proven tracheobronchial remnants. CES associated with EA is frequent. A high index of suspicion for CES must remain in the presence of EA. Dilatation may be effective to treat some of them, but perforation is frequent. Surgery may be required, especially in CES secondary to ectopic tracheobronchial remnants.

A pilot investigation of feeding problems in children with esophageal atresia.

While many long-term complications of esophageal atresia (EA) have been well investigated, little is known about feeding difficulties in children after surgical correction of EA and its impact on caregivers. This study investigates the feeding behaviors of children with EA through a validated feeding questionnaire. The Montreal Children's Hospital Feeding Scale (MCH-FS) was filled out by the primary caregiver during patient follow-up visits in the multidisciplinary EA clinic. Demographic information, EA subtype, associated anomalies and outcomes were recorded. Results were compared between groups and to a normative sample. Thirty caregivers have completed the MCH-FS; 26 patients had type C atresia (86.7%). In comparison to controls, 17.5% of EA cases are one standard deviation above the mean feeding difficulty score, while 6.7% (n = 2) cases are greater than two standard deviations above normative values. Typical EA patients (type C who were not born <30 weeks) had mean MCH-FS scores in the subclinical range, whereas one extremely premature child and the patients with non-type C EA (n = 4) all had scores in the severe range. Feeding difficulties of patients with typical EA appear mild. Likely explanations include the use of early protocolized care and intensive multidisciplinary care in follow up. Nonetheless, patients with complicated EA (non-type C) and their caregivers tend to experience significant feeding difficulties. Early targeted care may be required for this patient subset, and additional cases will be investigated to confirm these preliminary findings and explore further risk factors of feeding problem in this cohort.

Liquid-vapor transition and critical behavior of the ultrasoft restricted primitive model of polyelectrolytes: a Monte Carlo study.

We present a Monte Carlo study of the liquid-vapor transition and the critical behavior of a model of polyelectrolytes with soft Gaussian charge distributions introduced recently by Coslovich, Hansen, and Kahl [J. Chem. Phys. 134, 244514 (2011)]. A finite size study involving four different volumes in the grand canonical ensemble yields a precise determination of the critical temperature, chemical potential, and density of the model. Attempts to determine the nature of the criticality and to obtain reliable values for the critical exponents are not conclusive.

Does the perception of psychosocial factors increase the risk of pesticide exposure among seasonal Hispanic farmworkers?

BACKGROUND: Migrant farmworkers are prone to several psychosocial stressors. OBJECTIVE: To investigate the effect of perceived psychosocial factors on pesticide exposure among seasonal migrant Hispanic farmworkers in North Carolina, USA. METHODS: A cross-sectional interview survey of 187 seasonal migrant farmworkers of Mexican descent, identified from labor camps located in rural counties in North Carolina, was conducted using nonprobability purposive sampling approach. Multivariable ordinal logistic regression analysis was used to determine the relationship between perceived control over the harmful effects of pesticide exposure, lack of social support, and the impact of anxiety on perception of pesticide exposure. RESULTS: More than 20% (n=39) of farmworkers reported frequent or constant contact with pesticides while working in the fields. More than 68% of farmworkers reported they believe they have control over avoiding harmful effects of pesticide exposure; the odds of pesticide exposure were 55% lower in this group (adjusted OR: 0.45; 95% CI: 0.22-0.91). No significant relationship was observed between farmworkers perception of lack of social support and presence of anxiety with odds of on-field pesticide exposure. CONCLUSION: The study results suggest that perception of control is an important predictor of reduced pesticide exposure among seasonal migrant farmworkers.

Size effect and stability of polarized fluid phases.

The existence of a ferroelectric fluid phase for systems of 1000-2000 dipolar hard or soft spheres is well established by numerical simulations. Theoretical approaches proposed to determine the stability of such a phase are either in qualitative agreement with the simulation results or disagree with them. Experimental results for systems of molecules or particles with large electric or magnetic dipole moments are also inconclusive. As a contribution to the question of existence and stability of a fluid ferroelectric phase this simulation work considers system sizes of the order of 10 000 particles, thus an order of magnitude larger than those used in previous studies. It shows that although ferroelectricity is not affected by an increase of system size, different spatial arrangements of the dipolar hard spheres in such a phase are possible whose free energies seem to differ only marginally.

Long-term behavioral effects of neonatal blockade of gastrin-releasing peptide receptors in rats: similarities to autism spectrum disorders.

Gastrin releasing peptide, the mammalian counterpart of the amphibian peptide, bombesin, has been increasingly implicated in regulating normal brain function as well as in the pathogenesis of psychiatric and/or neurodevelopmental disorders. We have previously shown that the neonatal blockade of the gastrin-releasing peptide receptor (GRPr) in rats produces long-lasting consequences during central nervous system development that are commonly observed in neurodevelopmental disorders such as autism spectrum disorders. The present investigation assessed in further detail, long-term behavioral effects of neonatal GRPr blockade. During postnatal days 1-10, male Wistar rat pups (n=5-10/litter) were injected (subcutaneously) with the GRPr antagonist, RC-3095 (1 mg/kg), or a vehicle (control), twice daily. Following the drug treatment regimen, several behaviors were assessed (starting on postnatal day 14) including specific social behaviors (namely, group huddling characteristics, social interaction, and social approach), restrictive/repetitive and stereotyped behaviors (y-maze, repetitive novel object contact task, observation for stereotypies) and anxiety/fear-related responses (open field, elevated plus maze and contextual fear conditioning). Rats treated neonatally with RC-3095 showed reduced sociability, restrictive interests, motor stereotypies and enhanced learned fear response compared to the controls (vehicle-treated rats). These behavioral abnormalities are consistent with those observed in autism spectrum disorders and provide further evidence that neonatal blockade of GRPr could potentially serve as a useful model to gain a better understanding of the underlying neurodevelopmental disruptions contributing to the expression of autism-relevant phenotypes.

Refractory strictures post-esophageal atresia repair: what are the alternatives?

Esophageal strictures remain the most frequent complication after esophageal atresia (EA) repair despite refinements in operative techniques. With an incidence of anastomotic stricture between 8% and 49%, EA is the most frequent cause of benign esophageal stricture in children. The mainstay of treatment for esophageal stricture is dilatation with a 58-96% success rate. In order to relieve dysphagia, between 1 and 15 dilatations will be required in each EA patient with an esophageal stricture. However dilatations may lead to complications including perforation (0.1-0.4% of all esophageal benign strictures) and sociopsychological morbidity. Fifty percent of EA strictures will improve in 6 months. However, 30% will persist and require repeat dilatations. The present article explores the variety of non-surgical alternative treatments for anastomotic strictures after EA repair, focusing on triamcinolone acetonide, mitomycin C and esophageal stents. We propose an algorithm for a more standardized therapeutic approach, with the hope that an international panel of experts could meet and establish a consensus.

Relationship between BDNF expression in major striatal afferents, striatum morphology and motor behavior in the R6/2 mouse model of Huntington's disease.

Patients with Huntington's disease (HD) and transgenic mouse models of HD show neuronal loss in the striatum as a major feature, which contributes to cognitive and motor manifestations. Reduced expression of the neurotrophin brain-derived neurotrophic factor (BDNF) in striatal afferents may play a role in neuronal loss. How progressive loss of BDNF expression in different cortical or subcortical afferents contributes to striatal atrophy and behavioral dysfunction in HD is not known, and may best be determined in animal models. We compared age-dependent alterations of BDNF mRNA expression in major striatal afferents from the cerebral cortex, thalamus and midbrain in the R6/2 transgenic mouse model of HD. Corresponding changes in striatal morphology were quantified using unbiased stereology. Changes in motor behavior were measured using an open field, grip strength monitor, limb clasping and a rotarod apparatus. BDNF expression in cortical limbic and midbrain striatal afferents is reduced by age 4 weeks, prior to onset of motor abnormalities. BDNF expression in motor cortex and thalamic afferents is reduced by 6 weeks, coinciding with early motor dysfunction and reduced striatum volume. BDNF loss in afferents progresses until death at 13-15 weeks, correlating with progressive striatal neuronal loss and motor abnormalities. Mutant huntingtin protein expression in R6/2 mice results in progressive loss of BDNF in both cortical and subcortical striatal afferents. BDNF loss in limbic and dopaminergic striatal inputs may contribute to cognitive/psychiatric dysfunction in HD. Subsequent BDNF loss in cortical motor and thalamic afferents may accelerate striatal degeneration, resulting in progressive involuntary movements.

Association between workplace and housing conditions and use of pesticide safety practices and personal protective equipment among North Carolina farmworkers in 2010.

BACKGROUND: There are inconsistencies about the effects of farmworker housing and workplace conditions and use of self-protective behavior practices and personal protective equipment (PPE). OBJECTIVE: To investigate the association between workplace and housing conditions and farmworker use of pesticide safety practices and PPE. METHODS: This study was conducted in 4 counties in North Carolina, USA, from July to October, 2010, during the agricultural growing season. Farmworkers working in agriculture aged 18 to 62 (n = 187) were administered a structured questionnaire to collect self-reported measures on housing and workplace conditions. Use of pesticide safety and PPE were examined by asking questions about wearing gloves, wearing socks, and wearing a hat. Chi-square and multiple logistic regression analyses were used for statistical analyses. RESULTS: Farmworkers reporting availability of enough hot and cold water for bathing and doing laundry were 13.6 times more likely to use pesticide safety practices (adjusted OR: 13.6, 95% CI: 1.4-135.4), whereas, those who reported that soap for handwashing was always or usually available while doing agricultural work were 7.8 times more likely to use pesticide safety practices (adjusted OR: 7.8, 95% CI: 3.3-18.5). Farmworkers that reported access to water to wash their hands with while performing agricultural work were more likely to use PPE (adjusted OR: 3.4, 95% CI: 1.3-9.2). CONCLUSION: Some migrant farmworker labor camps are not supplying acceptable housing conditions such as 1 handwashing sink per 6 people (n = 10, 5.4%). Use of pesticide safety practices and PPE is greater when farmers provide decontamination supplies. Improvement of housing and workplace conditions are crucial to increase use of pesticide safety practices and PPE.

Molecular simulation of fluid-solid interfaces at nanoscale.

The equilibrium states of vapor and liquid coexistent phases in contact with a solid surface are studied at the nanoscale by molecular dynamics simulations for a temperature close to the fluid triple point. The characteristics of the solid-fluid interfaces are determined when the interaction strength between the fluid and the solid varies in order to go from a situation of complete drying to that of complete wetting. From the vapor-liquid density profiles of liquid drops lying on the substrate surface or menisci of liquid films confined in slit pores, the contact angles made by the vapor-liquid interface with the solid are computed. The angle values are similar for the drops and the films. They are also in good qualitative agreement with the estimates obtained through the Young's relation from the surface tensions associated with the vapor-solid, liquid-solid, and vapor-liquid interfaces. However, at this scale, the uncertainties inherent to the angle computation and, to a lesser extent, to size effects seem to preclude that the quantitative agreement between the angle estimates obtained from the interface geometry and calculated from the Young's relation can be better than few degrees.

Replicated association of the NR4A3 gene with smoking behaviour in schizophrenia and in bipolar disorder.

Schizophrenia and bipolar disorder are associated with dopamine neurotransmission and show high comorbidity with tobacco dependence. Recent evidence indicates that the family of the NR4A orphan nuclear receptors, which are expressed in dopamine neurons and in dopaminoceptive brain areas, may play a role in dopamine-mediated effects. We have, therefore, analysed the association of six single nucleotide polymorphisms (SNPs) within the three genes belonging to the NR4A orphan nuclear receptor family, NR4A1 (rs2603751, rs2701124), NR4A2 (rs12803, rs834835) and NR4A3 (rs1131339, rs1405209), with the degree of smoking in a sample of 204 unrelated schizophrenia patients, which included 126 smokers and 78 non-smokers. SNPs within the NR4A3 gene (rs1131339 and rs1405209) were significantly associated with heavy smoking in this cohort, using a stepwise analysis of the escalated number of cigarettes smoked per day (P = 0.008 and 0.006, respectively; satisfying the Nyholt significance threshold of 0.009, an adjustment for multiple testing). We then repeated the association analysis of the NR4A3 markers (rs1131339 and rs1405209) in a larger cohort of 319 patients with bipolar disorder, which included 167 smokers and 152 non-smokers. We have replicated the positive association with smoking of the NR4A3 SNP rs1131339 in this group (P = 0.04), providing an important confirmation of the involvement of the NR4A3 gene in nicotine addiction in patients with mental health disease, a population significantly at risk for nicotine addiction.

Cystamine prevents MPTP-induced toxicity in young adult mice via the up-regulation of the brain-derived neurotrophic factor.

Preclinical data suggest that cystamine stands as a promising neuroprotective agent against Huntington's and Parkinson's diseases. To decipher the mechanisms of action of cystamine, we investigated the effects of various doses of cystamine (10, 50, and 200mg/kg) on the regulation of the brain-derived neurotrophic factor (BDNF), its receptor tropomyosin-receptor-kinase B (TrkB) and on the heat shock protein 70 (Hsp70) brain mRNA expression in relation to the time after administration. We have determined that the lower cystamine dose is the most efficient to promote putative neuroprotective effects. Indeed, an acute administration of 10mg/kg of cystamine increased the expression of BDNF mRNA in the substantia nigra compacta (SNc), although it did not significantly influence TrkB or Hsp70 mRNA. Higher cystamine doses resulted in the absence of activation of any of these markers or led to non-specific effects. We have also substantiated the neuroprotective effect of a 21-day treatment of 10mg/kg/day of cystamine in young adult mice against MPTP-induced loss of tyrosine hydroxylase-striatal fiber density, nigral dopamine cells and nigral Nurr1 mRNA expression. The neuroprotective action of cystamine in the same animals was associated with an up-regulation of BDNF in the SNc. Taken together, these results strengthen the neuroprotective potential of cystamine in the treatment of Parkinson's disease and point towards the up-regulation of BDNF as an important mechanism of action.

Enhanced glutamatergic phenotype of mesencephalic dopamine neurons after neonatal 6-hydroxydopamine lesion.

There is increasing evidence that a subset of midbrain dopamine (DA) neurons uses glutamate as a co-transmitter and expresses vesicular glutamate transporter (VGLUT) 2, one of the three vesicular glutamate transporters. In the present study, double in situ hybridization was used to examine tyrosine hydroxylase (TH) and VGLUT2 mRNA expression during the embryonic development of these neurons, and postnatally, in normal rats and rats injected with 6-hydroxydopamine (6-OHDA) at P4 to destroy partially DA neurons. At embryonic days 15 and 16, there was a regional overlap in the labeling of TH and VGLUT2 mRNA in the ventral mesencephalon, which was no longer found at late embryonic stages (E18-E21) and postnatally. In normal pups from P5 to P15, only 1-2% of neurons containing TH mRNA in the ventral tegmental area (VTA) and substantia nigra, pars compacta, also displayed VGLUT2 mRNA. In contrast, after the cerebroventricular administration of 6-OHDA at P4, 26% of surviving DA neurons in the VTA of P15 rats expressed VGLUT2. To search for a colocalization of TH and VGLUT2 protein in axon terminals of these neurons, the nucleus accumbens of normal and 6-OHDA-lesioned P15 rats was examined by electron microscopy after dual immunocytochemical labeling. In normal rats, VGLUT2 protein was found in 28% of TH positive axon terminals in the core of nucleus accumbens. In 6-OHDA-lesioned rats, the total number of TH positive terminals was considerably reduced, and yet the proportion also displaying VGLUT2 immunoreactivity was modestly but significantly increased (37%). These results lead to the suggestion that the glutamatergic phenotype of a VTA DA neurons is highly plastic, repressed toward the end of normal embryonic development, and derepressed postnatally following injury. They also support the hypothesis of co-release of glutamate and DA by mesencephalic neurons in vivo, at least in the developing brain.

Diffusion of nanoparticles in dense fluids.

The diffusion process of a single spherical nanoparticle immersed in a fluid solvent is studied by molecular dynamics simulations. When the nanoparticle mass stays constant, it is shown that, at short times, the decay of the nanoparticle velocity autocorrelation function is strongly modified when the particle diameter increases. It is also shown that, at large times, the characteristic algebraic decay induced by the hydrodynamic correlations between the solvated particle and the solvent presents a scaling behavior depending on the particle diameter.

Long-time behavior of the velocity autocorrelation function at low densities and near the critical point of simple fluids.

Numerous theoretical and numerical works have been devoted to the study of the algebraic decrease at large times of the velocity autocorrelation function of particles in a fluid. The derivation of this behavior, the so-called long-time tail, generally based on linearized hydrodynamics, makes no reference to any specific characteristic of the particle interactions. However, in the literature doubts have been expressed about the possibility that by numerical simulations the long-time tail can be observed in the whole fluid phase domain of systems in which the particles interact by soft-core and attractive pair potentials. In this work, extensive and accurate molecular-dynamics simulations establish that the predicted long-time tail of the velocity autocorrelation function exists in a low-density fluid of particles interacting by a soft-repulsive potential and near the liquid-gas critical point of a Lennard-Jones system. These results contribute to the confirmation that the algebraic decay of the velocity autocorrelation function is universal in these fluid systems.