Obesity and Type 2 Diabetes Prevalence in Adults from Two Remote First Nations Communities in Northwestern Ontario, Canada

Objective. To assess the prevalence rates of obesity and type 2 diabetes in adults from two First Nations communities in northwestern Ontario, Canada. Methods. Body weight, height, and waist circumference as well as fasting and postprandial glucose levels following an oral glucose tolerance test were measured in 31 men and 41 women. Results. The mean age of the sample was 43 ± 13 y. The prevalence of obesity was 65.3% and was comparable between men and women. 90.3% of the individuals presented waist circumference levels greater than the thresholds associated with an increased risk of developing health problems. 26 of the 72 individuals (36.1%) were found to be type 2 diabetic. The prevalence of diabetes was not different between men and women. Conclusion. Using objective measurements, this study confirms that First Nations adults from remote communities of Canada continue to experience a disproportionately higher prevalence of obesity and type 2 diabetes than nonaboriginal Canadians

Relationship between the Daily Rhythm of Distal Skin Temperature and Brown Adipose Tissue 18F-FDG Uptake in Young Sedentary Adults

The present study examines whether the daily rhythm of distal skin temperature (DST) is associated with brown adipose tissue (BAT) metabolism as determined by 18F-fluorodeoxyglucose (18F-FDG) uptake in young adults. Using a wireless thermometer (iButton) worn on the nondominant wrist, DST was measured in 77 subjects (26% male; age 22 ± 2 years; body mass index 25.2 ± 4.8 kg/m2) for 7 consecutive days. The temperatures to which they were habitually exposed over the day were also recorded. The interday stability of DST was calculated from the collected data, along with the intraday variability and relative amplitude; the mean temperature of the 5 and 10 consecutive hours with the maximum and minimum DST values, respectively; and when these hours occurred. Following exposure to cold, BAT volume and mean and peak standardized 18F-FDG uptake (SUVmean and SUVpeak) were determined for each subject via static 18F-FDG positron emission tomography/computed tomography scanning. Relative amplitude and the time at which the 10 consecutive hours of minimum DST values occurred were positively associated with BAT volume, SUVmean, and SUVpeak (p ≤ 0.02), whereas the mean DST of that period was inversely associated with the latter BAT variables (p ≤ 0.01). The interday stability and intraday variability of the DST were also associated (directly and inversely, respectively) with BAT SUVpeak (p ≤ 0.02 for both). All of these associations disappeared, however, when the analyses were adjusted for the ambient temperature to which the subjects were habitually exposed. Thus, the relationship between the daily rhythm of DST and BAT activity estimated by 18F-FDG uptake is masked by environmental and likely behavioral factors. Of note is that those participants exposed to the lowest ambient temperature showed 3 to 5 times more BAT volume and activity compared with subjects who were exposed to a warmer ambient temperature

Dysregulation of Cytokine Response in Canadian First Nations Communities: Is There an Association with Persistent Organic Pollutant Levels?

In vitro and animal studies report that some persistent organic pollutants (POPs) trigger the secretion of proinflammatory cytokines. Whether POP exposure is associated with a dysregulation of cytokine response remains to be investigated in humans. We studied the strength of association between plasma POP levels and circulating cytokines as immune activation markers. Plasma levels of fourteen POPs and thirteen cytokines were measured in 39 Caucasians from a comparator sample in Québec City (Canada) and 72 First Nations individuals from two northern communities of Ontario (Canada). Caucasians showed significantly higher levels of organochlorine insecticides (β-HCH, p,p′-DDE and HCB) compared to First Nations. Conversely, First Nations showed higher levels of Mirex, Aroclor 1260, PCB 153, PCB 170, PCB 180 and PCB 187 compared to Caucasians. While there was no difference in cytokine levels of IL-4, IL-6, IL-10 and IL-22 between groups, First Nations had significantly greater average levels of IFNγ, IL-1β, IL-2, IL-5, IL-8, IL-12p70, IL-17A, TNFα and TNFβ levels compared to Caucasians. Among candidate predictor variables (age, body mass index, insulin resistance and POP levels), high levels of PCBs were the only predictor accounting for a small but significant effect of observed variance (∼7%) in cytokine levels. Overall, a weak but significant association is detected between persistent organochlorine pollutant exposure and elevated cytokine levels. This finding augments the already existing information that environmental pollution is related to inflammation, a common feature of several metabolic disorders that are known to be especially prevalent in Canada's remote First Nations communities

Effects of acute hypoxia and cold exposure on glucose and fatty acid fluxes in rainbow trout (Oncorhynchus mykiss).

The first goal of my thesis is to develop a double catheterization method allowing simultaneous infusion of labeled compounds and blood sampling, and to quantify glucose fluxes in resting rainbow trout by continuous infusion of 6-\sp3H-glucose (Chapter 2). The new cannulation technique consists of placing both sampling and infusing catheters in the dorsal aorta. Continuous isotope infusion results show that resting glucose turnover is 9.5 $\pm$ 0.8 $\mu$mol \rm kg\sp{-1}\ min\sp{-1}, a value 4 to 9 times higher than most rates measured with bolus injection technique. Consequently, the second goal is to quantify the accuracy of the continuous infusion technique in estimating glucose turnover rate. Trout are hepatectomizad and liver glucose production is artificially replaced by a pump infusing unlabelled glucose. Glucose flux measured with the continuous infusion technique using either plasma or whole blood is not significantly different from artificial pump glucose entry rate. Therefore, this result suggests that the bolus injection method widely used in previous trout studies strongly underestimates true glucose flux. Using the continuous infusion technique, my third goal is to investigate the effects of two environmental disturbances namely acute hypoxia and cold exposure, on the rates of glucose and NEFA (non-esterified fatty acids) turnover. My hypotheses are that: (1) during hypoxia, a fuel preference for carbohydrates would lead to an increase in glucose flux and a decrease in NEFA flux; (2) during cold exposure, both glucose and NEFA fluxes would decrease in proportion to metabolic rate depression. The results suggest that no fuel preference is occurring during cold exposure. However, while glucose concentration only shows a slight overall decrease, NEFA concentration increases by 30% after 100 minutes at 6\sp\circC. (Abstract shortened by UMI.

We are all exposed, but some are more exposed than others

ABSTRACTThis paper defines functional cold exposure zones that illustrate whether a person is at risk of developing physical performance loss or cold weather injuries. Individual variation in body characteristics, activity level, clothing and protective equipment all contribute to variation in the effective exposure. Nevertheless, with the right education, training, and cold-adapted behaviours the exposure differences might not necessarily lead to increased risk for cold injury. To support the preparation process for cold weather operations, this paper presents a biophysical analysis explaining how much cold exposure risk can vary between individuals in the same environment. The results suggest that smaller persons are prone to be underdressed for moderate activity levels and larger persons are prone to be overdressed. The consequences of these discrepancies place people at different risks for performance loss or cold weather injuries. Nonetheless, even if all are well-dressed at the whole-body level, variation in hand morphology is also expected to influence hand skin temperatures that can be maintained; with smaller hands being more prone to reach skin temperatures associated with dexterity loss or cold weather injuries. In conclusion, this work focusses on bringing cold science to the Arctic warrior, establishing that combating cold stress is not a one size fits all approach

Biomarkers for warfighter safety and performance in hot and cold environments

10.1016/j.jsams.2022.12.006Journal of Science and Medicine in Spor