Sex differences in thermal strain induced by a typical hiking scenario in a cool environment

Most research investigating hill walking has focused on the mechanisms of accidental hypothermia with protocols involving males exposed to prolonged wet and windy environments [1]. No attention has been paid to discomfort associated with the different phases of recreational hiking in non-adverse conditions. The present study was designed to evaluate overall and local thermal strain during a typical hiking scenario and to highlight potential differences between males and females. This knowledge can be of practical importance for improved clothing requirement

Different physiological responses but similar thermal perceptions for males with various body fatness during cold air exposure

There is no consensus regarding the potential effect of body fatness on subjective responses to cold at rest [1,2]. Most studies have examined overall sensation and comfort with no attention to regional values or the influence of exercise on thermal perception. The present study aimed at exploring overall and regional perceptual responses of males, varying in body fat content (¿) in association with their physiological responses, specifically regional skin temperatures (Tsk)

Body mapping of thermoregulatory and perceptual responses of males and females running in the cold

Thermoregulatory parameters during exercise are typically reported as global responses (T and mean T). In contrast, this study investigated regional skin temperatures (T) over the body, in relation to regional skinfold thickness and regional perceptual responses for both sexes using a body-mapping approach. Nine males and nine females, of equivalent fitness, minimally clothed, ran for 40min at 70% VO2max in a 10°C, 50%rh, 2.8ms air velocity environment. T was recorded by infrared thermography and processed to obtain population-averaged body maps. Rectal temperature and heart rate were monitored continuously throughout the running trial. Skinfold thickness was obtained for 24 sites and thermal sensation votes for 11 body regions.Males and females had similar rectal temperature, heart rate and regional sensations. Whole-body maps of T highlighted the significantly lower regional T for females (-1.6°C overall, p<0.01). However, the distribution of T across the body was similar between sexes and this was not correlated with the distribution of skinfold thickness, except for the anterior torso. On the other hand, regional thermal sensation votes across the body were correlated with T distribution during exercise (females: r=0.61, males: r=0.73, p<0.05), but not at rest.Our thermographic results demonstrate the similar T distribution for active males and females during submaximal running in the cold, though shifted to a lower mean value for females. This T distribution was associated with regional sensations but not with local fat thickness. The described body-mapping approach can have implications in physiological modelling and clothing design. © 2013 Elsevier Ltd

Electrocardiographic correlates of mechanical dyssynchrony in recipients of cardiac resynchronization therapy devices

SummaryBackgroundThe relationship between electrical and mechanical indices of cardiac dyssynchronization in systolic heart failure (HF) remains poorly understood.ObjectivesWe examined retrospectively this relationship by using the daily practice tools in cardiology in recipients of cardiac resynchronization therapy (CRT) systems.MethodsWe studied 119 consecutive patients in sinus rhythm and QRS≥120ms (mean: 160±17ms) undergoing CRT device implantation. P wave duration, PR, ePR (end of P wave to QRS onset), QT, RR–QT, JT and QRS axis and morphology were putative predictors of atrioventricular (diastolic filling time [DFT]/RR), interventricular mechanical dyssynchrony (IVMD) and left intraventricular mechanical dyssynchrony (left ventricular pre-ejection interval [PEI] and other measures) assessed by transthoracic echocardiography (TTE). Correlations between TTE and electrocardiographic measurements were examined by linear regression.ResultsStatistically significant but relatively weak correlations were found between heart rate (r=−0.5), JT (r=0.3), QT (r=0.3), RR–QT intervals (r=0.5) and DFT/RR, though not with PR and QRS intervals. Weak correlations were found between: (a) QRS (r=0.3) and QT interval (r=0.3) and (b) IVMD>40ms; and between (a) ePR (r=−0.2), QRS (r=0.4), QT interval (r=0.3) and (b) LVPEI, though not with other indices of intraventricular dyssynchrony.ConclusionsThe correlations between electrical and the evaluated mechanical indices of cardiac dyssynchrony were generally weak in heart failure candidates for CRT. These data may help to explain the discordance between electrocardiographic and echocardiographic criteria of ventricular dyssynchrony in predicting the effect of CRT

Female Thermal Sensitivity to Hot and Cold During Rest and Exercise

Regional differences in thermal sensation to a hot or cold stimulus are often limited to male participants, in a rested state and cover minimal locations. Therefore, magnitude sensation to both a hot and cold stimulus were investigated during rest and exercise in 8 females (age: 20.4 ± 1.4 years, mass: 61.7 ± 4.0 kg, height: 166.9 ± 5.4 cm, VO2max: 36.8 ± 4.5 ml·kg− 1·min− 1). Using a repeated measures cross over design, participants rested in a stable environment (22.3 ± 0.9 °C, 37.7 ± 5.5% RH) whilst a thermal probe (25 cm2), set at either 40 °C or 20 °C, was applied in a balanced order to 29 locations across the body. Participants reported their thermal sensation after 10 s of application. Following this, participants cycled at 50% VO2max for 20 min and then 30% VO2max whilst the sensitivity test was repeated. Females experienced significantly stronger magnitude sensations to the cold than the hot stimulus (5.5 ± 1.7 and 4.3 ± 1.3, p < 0.05, respectively). A significant effect of location was found during the cold stimulation (p < 0.05). Thermal sensation was greatest at the head then the torso and declined towards the extremities. No significant effect of location was found in response to the hot stimulation and the pattern across the body was more homogenous. In comparison to rest, exercise caused a significant overall reduction in thermal sensation (5.2 ± 1.5 and 4.6 ± 1.7, respectively, p < 0.05). Body maps were produced for both stimuli during rest and exercise, which highlight sensitive areas across the body

Modeling the Impact of Tuberculosis Control Strategies in Highly Endemic Overcrowded Prisons

International audienceBACKGROUND: Tuberculosis (TB) in prisons is a major health problem in countries of high and intermediate TB endemicity such as Brazil. For operational reasons, TB control strategies in prisons cannot be compared through population based intervention studies. METHODOLOGY/PRINCIPAL FINDINGS: A mathematical model is proposed to simulate the TB dynamics in prison and evaluate the potential impact on active TB prevalence of several intervention strategies. The TB dynamics with the ongoing program was simulated over a 10 year period in a Rio de Janeiro prison (TB prevalence 4.6 %). Then, a simulation of the DOTS strategy reaching the objective of 70 % of bacteriologically-positive cases detected and 85 % of detected cases cured was performed; this strategy reduced only to 2.8% the average predicted TB prevalence after 5 years. Adding TB detection at entry point to DOTS strategy had no major effect on the predicted active TB prevalence. But, adding further a yearly X-ray mass screening of inmates reduced the predicted active TB prevalence below 1%. Furthermore, according to this model, after applying this strategy during 2 years (three annual screenings), the TB burden would be reduced and the active TB prevalence could be kept at a low level by associating X-ray screening at entry point and DOTS. CONCLUSIONS/SIGNIFICANCE: We have shown that X-ray mass screenings should be considered to control TB in highly endemic prison. Prisons with different levels of TB prevalence could be examined thanks to this model which provides a rational tool for public health deciders

A method for whole-body skin temperature mapping in humans (Eine Methode zur Aufzeichnung der Hautemperatur des gesamten menschlichen Korpers)

The described method provides a novel way to quantitatively and qualitatively report thennographic assessments of different humans. It combines a segmentation of defined body regions as well as a morphingtechnique in order to produce skin temperature body maps regardless of anthropometry and body position. This mapping method can be suitable for the creation of a skin temperature database of healthy individuals in various situations and environments