Trehalose acts as a non-toxic cryoprotectant agent (CPA) to CHO-TRET1 cells, which are CHO-K1 cells that express the trehalose transporter. This study examines the viabilities during long-term storage at 193K of cryopreserved CHO-TRET1 cells with trehalose, and compares them to the corresponding viabilities with 10wt%-dimethyl sulfoxide (DMSO). The cryopreserved samples are selected to have a 1-week storage viability exceeding 0.7. Results show that this high viability with trehalose is maintained at the same level for about one year of storage, and gradually decrease to about 0.55±0.16 after about 2.5 years. Comparison of this result with the corresponding case with DMSO suggests that the cryoprotective ability of trehalose is slightly weaker than that of DMSO at this temperature. We discuss the effect of recrystallization of ice, and also the biological damaging, on the viabilities. Then we concluded that the cell membrane slowly degrades at 193K, with the rate being a little faster with trehalose than with DMSO.
The purpose of this study was to examine the physiological responses to intensive snow shoveling. The subjects were six males (25-71, 50±8 years) who participated in a snow removal volunteer tour. Prior to the tour, each subject engaged in a cycle ergometer test (Test 1) and a multistage shoveling test (Test 2) to evaluate the relationship between volume of oxygen consumption (VO2) and heart rate. Field measurements were performed in Miruto of Iwamizawa City, Hokkaido, Japan on February 2, 2014. Average air temperatures of that day were －6.3°C in the morning and －1.4°C in the afternoon. The snow layer at the work site had various grain shapes and snow density linearly increased with snow depth. While snow hardness increased exponentially with increase in snow depth. Mean heart rate during working time in the afternoon (142±9 beats min－1) was significantly (p<0.01) higher than that in the morning (131±9 beats min－1). These heart rates correspond 84% and 77% of the predicted maximum heart rate (HRmax), respectively. Ratings of perceived exertion were not different in the morning (12.9±0.4) and afternoon (12.4±0.3). The mean values of VO2 in the total work period (111±3 min) was estimated to be 22.2±1.2ml kg－1min－1 (Metabolic equivalent; 6.4±0.3METs). Estimated energy expenditure averaged 782±46kcal. It is conceivable that increase in snow hardness and snow density caused an increase in work intensity.