Influence of Varied Dietary Cholesterol Levels on Lipid Metabolism in Hamsters.

Syrian hamsters are valuable models for studying lipid metabolism due to their sensitivity to dietary cholesterol, yet the precise impact of varying cholesterol levels has not been comprehensively assessed. This study examined the impact of varying dietary cholesterol levels on lipid metabolism in Syrian hamsters. Diets ranging from 0% to 1% cholesterol were administered to assess lipid profiles and oxidative stress markers. Key findings indicate specific cholesterol thresholds for inducing distinct lipid profiles: below 0.13% for normal lipids, 0.97% for elevated LDL-C, 0.43% for increased VLDL-C, and above 0.85% for heightened hepatic lipid accumulation. A cholesterol supplementation of 0.43% induced hypercholesterolemia without adverse liver effects or abnormal lipoprotein expression. Furthermore, cholesterol supplementation significantly increased liver weight, plasma total cholesterol, LDL-C, and VLDL-C levels while reducing the HDL-C/LDL-C ratio. Fecal cholesterol excretion increased, with stable bile acid levels. High cholesterol diets correlated with elevated plasma ALT activities, reduced hepatic lipid peroxidation, and altered leptin and CETP levels. These findings underscore Syrian hamsters as robust models for hyperlipidemia research, offering insights into experimental methodologies. The identified cholesterol thresholds facilitate precise lipid profile manipulation, enhancing the hamster's utility in lipid metabolism studies and potentially informing clinical approaches to managing lipid disorders.

Regulation of autophagy following ex vivo heating in peripheral blood mononuclear cells from young adults.

Under conditions of extreme heat stress, the process of autophagy has previously been shown to protect human cells, but the exact body temperature at which autophagic activation occurs is largely unknown. Further, the interplay between autophagy, the heat shock response (HSR), inflammation, and apoptosis have yet to be examined together under temperature conditions representative of human internal body temperatures at rest (37 °C) or under severe heat stress conditions (41 °C). Thus, the purpose of this study was to examine threshold changes in autophagy, the HSR, inflammation, and apoptosis to increasing levels of ex vivo heat stress. Whole blood was collected from 20 young (23 ± 4 years; 10 men, 10 women) physically active participants. Peripheral blood mononuclear cells (PBMCs) were isolated immediately (baseline) and after 90-min of whole blood heating in 37, 39, and 41 °C water baths, representative of normal resting (non-heat stress) as well as moderate and severe heat stress conditions in humans, respectively. At 37 °C, increased autophagic activity was demonstrated, with no change in the HSR, and inflammation. Subsequently, responses of autophagy, the HSR, and inflammation increased with a moderate heat stress (39 °C), with further increases in only autophagy and the HSR under a severe heat stress of 41 °C. We observed no increase in apoptosis under any temperature condition. Our findings show that in human PBMCs, the autophagy and HSR systems may act cooperatively to suppress apoptotic signaling following heat stress, which may in part be mediated by an acute inflammatory response.

Relative Importance of Four Muscle Groups for Indoor Rock Climbing Performance.

Little research is available to guide training programs for rock climbers. To help meet this need, we sought to determine the relative importance of 4 muscle groups for rock climbing performance. Eleven male climbers were familiarized with an indoor climbing route before 5 separate days of testing. On testing days, subjects were randomly assigned to climb with no prefatiguing exercise (control climb) or after a prefatiguing exercise designed to specifically target the digit flexors (DF), shoulder adductors (SA), elbow flexors (EF), or lumbar flexors (LF). Immediately after the prefatiguing exercise, the subject climbed the route as far as possible without rest until failure. The number of climbing moves was recorded for each climb. Surface electromyography of the target muscles was recorded during the prefatigue. Fewer climbing moves were completed after prefatigue of the DF (50 ± 18%) and EF (78 ± 22%) (p ≤ 0.05) compared with the control climb. The number of moves completed after prefatigue of the LF and SA were not statistically significant compared with the control climb (p > 0.05). The short time lapse between the end of prefatiguing exercise and the start of climbing (transit time), which may have allowed for some recovery, was not different among trials (p > 0.05). Electromyography median frequency was reduced from beginning to end of each prefatiguing exercise. These results suggest that among the muscle groups studied in men, muscular endurance of DF and EF muscle groups is especially important for rock climbing on 40° overhanging terrain.