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.

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.

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.

5-Benzylbarbituric acid derivatives, potent and specific inhibitors of uridine phosphorylase.

5-Benzylbarbituric acid derivatives were synthesized as a series of new, specific, and potent inhibitors of uridine phosphorylase. Among these, 5-(m-benzyloxy)benzyl-1-[(2-hydroxyethoxy)methyl] barbituric acid (5-benzyloxybenzylbarbituric acid acyclonucleoside, BBBA) was found to be the most potent with Ki values of 1.1 +/- 0.2 and 2.6 +/- 0.3 nM with uridine phosphorylase from human and mouse livers, respectively. BBBA exhibited competitive inhibition with uridine phosphorylase from both human and mouse livers. The 5-benzylbarbituric acid derivatives are specific inhibitors of uridine phosphorylase, as they had no effect on thymidine phosphorylase (EC 2.4.2.4), thymidine kinase (EC 2.7.1.21), uridine-cytidine kinase (EC 2.7.1.48), orotate phosphoribosyltransferase (EC 2.4.2.10), orotidine 5'-monophosphate decarboxylase (EC 4.1.2.23), and dihydrouracil dehydrogenase (EC 1.3.1.2). These compounds are more potent, easier to synthesize, and have better water solubility than their uracil counterparts as inhibitors of uridine phosphorylase. Furthermore, the 5-benzylbarbituric acids were found to be better inhibitors of human uridine phosphorylase than the murine enzyme, whereas the reverse holds true for the 5-benzyluracil derivatives. The 5-benzylbarbituric acid derivatives have potential usefulness in the therapy of cancer and AIDS, as well as other pathological and physiological disorders.