Heat tolerance and acclimation in female athletes

This thesis aimed to develop a running heat tolerance test (RHTT) to assess changes in heat tolerance and to investigate the mechanism and optimisation of heat acclimation (HA) for female athletes. The first study introduced a RHTT and assessed its repeatability. Results demonstrate good agreement, strong correlations and small differences between repeated trials. The typical error of measure values suggested low within-participant variability. Furthermore, the RHTT was effective in differentiating between individuals’ physiological responses, demonstrating that heat tolerance lies along a continuum. The second study examined the sensitivity of the RHTT to changes in heat tolerance and to evaluate individual responses to HA. Results demonstrate that the RHTT is sensitive to changes in heat tolerance and that the magnitude of adaptation is highly individual; supporting the use of the RHTT in future investigations. Reducing thermal strain through HA in not fully understood for a female population. The third study compared males’ and females’ temporal patterning to short-term HA (STHA; 5-d) and long-term HA (LTHA; 10-d). The RHTT was used to quantify changes in heat tolerance. The results confirm that whilst STHA may be effective in achieving partial adaptation in males and females, females require LTHA to establish reductions in thermoregulatory and cardiovascular strain. Improved thermotolerance following HA, reduces disruptions to cellular homeostasis principally, but not exclusively, by increasing basal heat shock protein 72 following transcription of its gene (Hsp 72 mRNA) as part of the heat shock response (HSR). The fourth study compared males’ and females’ Hsp72 mRNA response during STHA and LTHA. The similar transcription of Hsp72 mRNA observed in all participants suggests that there are no differences in the endogenous criteria to elicit the HSR between sexes. The fifth study assessed the effectiveness of preceding STHA with a passive heat exposure (HAsauna) in females. HAsauna resulted in reductions in thermoregulatory, cardiovascular and perceptual strain. The adaptation pathway was likely mediated in part, by plasma volume expansion and an improved thermoeffector and thermosensitivity response of the sudomotor function. Together, evidence in this thesis supports the notion that special considerations need to be taken when using HA to attenuate thermoregulatory strain in female athletes prior to training and competing in the heat

A comparison of males and females' temporal patterning to short-and long-term heat acclimation

The current study assessed sex differences in thermoregulatory and physiological adaptation to short-term (STHA) and long-term heat acclimation (LTHA). Sixteen (eight males; eight females) participants performed three running heat tolerance test

Municipal bylaw to reduce cosmetic/non-essential pesticide use on household lawns - a policy implementation evaluation

<p>Abstract</p> <p>Background</p> <p>Pesticide use on urban lawns and gardens contributes to environmental contamination and human exposure. Municipal policies to restrict use and educate households on viable alternatives deserve study. We describe the development and implementation of a cosmetic/non-essential pesticide bylaw by a municipal health department in Toronto, Ontario, Canada and assess changes in resident practices associated with bylaw implementation.</p> <p>Methods</p> <p>Implementation indicators built on a logic model and were elaborated through key informant interviews. Bylaw impacts on awareness and practice changes were documented through telephone surveys administered seasonally pre, during and post implementation (2003-2008). Multivariable logistic regression models assessed associations of demographic variables and gardening season with respondent awareness and practices.</p> <p>Results</p> <p>Implementation indicators documented multiple municipal health department activities and public involvement in complaints from commencement of the educational phase. During the enforcement phases only 40 warning letters and 7 convictions were needed. The number of lawn care companies increased. Among survey respondents, awareness of the bylaw and the Natural Lawn campaign reached 69% and 76% respectively by 2008. Substantial decreases in the proportion of households applying pesticides (25 to 11%) or hiring lawn care companies for application (15 to 5%) occurred. Parallel absolute increases in use of natural lawn care methods occurred among households themselves (21%) and companies they contracted (7%).</p> <p>Conclusions</p> <p>Bylaws or ordinances implemented through education and enforcement are a viable policy option for reducing urban cosmetic pesticide use.</p

Sauna Exposure Immediately Prior to Short-term Heat Acclimation Accelerates Phenotypic Adaptation in Females

Objectives: Investigate whether a sauna exposure prior to short-term heat acclimation (HA) accelerates phenotypic adaptation in females. Design: Randomised, repeated measures, cross-over trial. Methods: Nine females performed two 5-d HA interventions (controlled hyperthermia Tre ≥ 38.5°C), separated by 7-wk, during the follicular phase of the menstrual cycle confirmed by plasma concentrations of 17-β estradiol and progesterone. Prior to each 90-min HA session participants sat for 20-min in either a temperate environment (20°C, 40% RH; HAtemp) wearing shorts and sports bra or a hot environment (50°C, 30% RH) wearing a sauna suit to replicate sauna conditions (HAsauna). Participants performed a running heat tolerance test (RHTT) 24-hr pre and 24-hr post HA. Results: Mean heart rate (HR) (85±4 vs. 68±5 bpm, p≤0.001), sweat rate (0.4±0.2 vs. 0.0±0.0 L.hr-1, p≤0.001), and thermal sensation (6±0 vs. 5±1, p=0.050) were higher during the sauna compared to temperate exposure. Resting rectal temperature (Tre) (-0.28±0.16°C), peak Tre (-0.42±0.22°C), resting HR (-10±4 bpm), peak HR (-12±7 bpm), Tre at sweating onset (-0.29±0.17°C) (p≤0.001), thermal sensation (-0.5±0.5; p=0.002), and perceived exertion (-3±2; p≤0.001) reduced during the RHTT, following HAsauna; but not HAtemp. Plasma volume expansion was greater following HAsauna (HAsauna, 9±7%; HAtemp, 1±5%; p=0.013). Sweat rate (p≤0.001) increased and sweat NaCl (p=0.006) reduced during the RHTT following HAsauna and HAtemp. Conclusions: This novel strategy initiated HA with an attenuation of thermoregulatory, cardiovascular, and perceptual strain in females due to a measurably greater strain in the sauna compared to temperate exposure when adopted prior to STHA

Uterine Torsion Dystocia Complicated by Perosomus Elumbis in an Angus Calf Associated with a Consanguineous Mating

A six-year-old multiparous Angus cow was presented for dystocia. Vaginal and rectal examinations revealed an approximately 360° counterclockwise uterine torsion. The torsion was corrected by rolling the cow counterclockwise (three episodes) with the aid of a plank coupled with manual detorsion via the vagina. The placement of obstetric chains followed by manual traction ultimately delivered a stillborn male calf with evidence of vertebral aplasia, arthrogryposis, and abdominal organ herniation. Patient history and subsequent parentage verification revealed that the calf was the result of a consanguineous (mother to son) mating. Tissue samples from the affected calf and blood samples from the dam, sire, and ten half siblings were collected for genetic testing and parentage verification. Necropsy, radiographic, and computed tomography examinations all supported a diagnosis of perosomus elumbis. Perosomus elumbis is a congenital abnormality of unknown origin(s), and this is the first report of a case associated with a consanguineous mating

Changes in immune cell populations in the periphery and liver of GBV-B-infected and convalescent tamarins (Saguinus labiatus)

AbstractFlaviviruses related to hepatitis C virus (HCV) in suitable animal models may provide further insight into the role that cellular immunity contributes to spontaneous clearance of HCV. We characterised changes in lymphocyte populations in tamarins with an acute GBV-B infection, a hepatitis virus of the flaviviridae. Major immune cell populations were monitored in peripheral and intra-hepatic lymphocytes at high viraemia or following a period when peripheral virus was no longer detected. Limited changes in major lymphocyte populations were apparent during high viraemia; however, the proportions of CD3+ lymphocytes decreased and CD20+ lymphocytes increased once peripheral viraemia became undetectable. Intrahepatic lymphocyte populations increased at both time points post-infection. Distinct expression patterns of PD-1, a marker of T-cell activation, were observed on peripheral and hepatic lymphocytes; notably there was elevated PD-1 expression on hepatic CD4+ T-cells during high viraemia, suggesting an activated phenotype, which decreased following clearance of peripheral viraemia. At times when peripheral vRNA was not detected, suggesting viral clearance, we were able to readily detect GBV-B RNA in the liver, indicative of long-term virus replication. This study is the first description of changes in lymphocyte populations during GBV-B infection of tamarins and provides a foundation for more detailed investigations of the responses that contribute to the control of GBV-B infection