Sustained exercise load by young adult females while wearing surgical mask raises core body temperature measured with zero-heat-flux thermometer.

When a pandemic such as that caused by the novel coronavirus disease termed COVID-19 emerges, it is recommended to wear a mask when in public situations, with information regarding the impact on thermoregulation essential, especially during exercise or hard physical labor. The present study investigated changes in core body temperature (CBT) while wearing a surgical mask (SM) during exercise (TCBT) using a non-invasive zero-heat-flux (ZHF) thermometer. Nine young adult females performed ergometer exercise for 30 min at 60 W with (mask group) and without (control) a SM under a non-hot condition, shown by wet bulb globe temperature (WBGT) findings. TCBT, mean skin temperature (TMST), heart rate (HR), and humidity in the perioral region of the face (%RH) were determined. Each of those markers showed increased values during exercise, with the increases in TCBT, HR, and %RH, but not TMST, during exercise found to be significantly greater in the mask group. HR reserve (%HRR), derived as load intensity during exercise, was also significantly higher in the mask group. Each subject completed all of the experimental protocols without noting pain or discomfort. These results suggest that wearing a SM while performing mild exercise contributes to increased TCBT associated with increased exercise intensity, expressed as %HRR in a non-heated condition. Furthermore, the ZHF thermometer was shown to be safe and is considered useful for conducting such studies. Additional examinations will be necessary to examine gender and age group differences, as well as the use of different exercise methods and intensity and ambient conditions.

Insulin-like growth factor 1 mRNA expression in the uterus of streptozotocin-treated diabetic mice.

Reproductive functions decline with the onset of diabetes in female mice. Diabetic mice have smaller uteri with an underdeveloped endometrium, suggesting diminished estrogen-induced growth. We aimed to clarify the changes in the estrous cycle and in insulin-like growth factor 1 (IGF1) expression in the uteri of streptozotocin (STZ)-treated diabetic mice, because IGF1 is one of the main growth factors involved in estrogen-induced uterine growth. ICR female mice were intraperitoneally administered STZ (10 mg/100 g BW), and blood glucose levels were determined. Mice with blood glucose levels > 200 mg/dl were classified as diabetic mice. The onset of diabetes was associated with acyclic estrous cycles. Diabetes was also induced with STZ in ovariectomized mice. Uterine Igf1 mRNA levels were reduced in ovariectomized STZ-treated diabetic mice. Estrogen is known to stimulate Igf1 mRNA expression in the uterus, but estrogen action was abolished in the uteri of STZ-treated diabetic mice. mRNA expressions of estrogen receptor α (ERα) and steroid hormone receptor coactivators (SRC-1/Ncoa1, SRC-2/Ncoa2, SRC-3/Ncoa3 and CBP/p300/Crebbp) were reduced in the uteri of ovariectomized STZ-treated diabetic mice. The present study demonstrates that diabetes induces a decline in female reproductive functions in mice. Igf1 expression in ovariectomized diabetic female mice was decreased, and decreased responsiveness to estrogen in the uteri of diabetic mice is probably associated with a reduction in ERα and steroid receptor coactivator mRNA expression.