Objective To observe the effect of benzo[a]pyrene-r-7, t-8-dihydrodiol-t-9, 10-epoxide(±), (anti) (BPDE) on testosterone synthesis from mouse Leydig cells, and investigate the potential mechanism involved mitochondrial damage. Methods TM3 mouse Leydig cells were treated with various doses of BPDE for 48 h. Cell viability was assessed by trypan blue assay. Then the doses under the lethal dose were selected according to results of cell viability. After TM3 cells were treated with 0, 25, 50, or 100 nmol/L BPDE for 48 h, testosterone concentration in the medium, mitochondrial ultrastructure of TM3 cells, mitochondrial membrane potential, ATP level, mitochondrial DNA copy number, and expression levels of PGC-1α, COX Ⅳ, StAR and TSPO were measured through ELISA kit for testosterone, transmission electron microscopy, JC-1 probe, ATP detection kit, quantitative PCR and Western blotting, respectively. Furthermore, TM3 cells were pre-treated with 5 μmol/L ZLN005, a regulator to protect mitochondrial function and stimulate mitochondrial biogenesis. Then, after 24 h, these pre-treated cells were treated with 100 nmol/L BPDE for 48 h, the indicators above were determined in the same ways. Results BPDE at the doses of 25, 50, 100 nmol/L had no significantly effect on cell viability of TM3 cells. Compared to control cells, 50 and 100 nmol/L BPDE reduced testosterone synthesis by 21.15% and 34.96%, respectively (P < 0.01), and also induced mitochondrial structure and function, including alterations of mitochondrial ultrastructure, and appreciable decreases in mitochondrial membrane potential, cellular ATP production and mitochondrial DNA copy number (P < 0.05). What's more, the levels of proteins related to mitochondrial function, COX Ⅳ and to mitochondrial biogenesis, PGC-1α, and the key proteins for testosterone synthesis, StAR and TSPO, were all reduced in a dose-dependent manner. Compared to TM3 cells treated with 100 nmol/L BPDE alone, pre-treatment with 5 μmol/L ZLN005 for 24 h significantly elevated testosterone level in the medium (P < 0.05). Notable restores of the indicators above were observed in the TM3 cells pre-treated with ZLN005, including mitochondrial membrane potential, cellular ATP production, mitochondrial DNA copy number, and protein levels of COX Ⅳ, PGC-1α, StAR and TSPO (P < 0.05). Conclusion BPDE induces reduction of testosterone synthesis via mitochondrial compromise. Protecting mitochondria could alleviate BPDE-induced mitochondrial damage and reduction of testosterone synthesis.

Objective To evaluate the training intensity and fatigue level after 5 km armed off-road training in army special operations forces (SOF), and to screen sensitive indicators for fatigue evaluation. Methods Twenty soldiers at professional posts were collected from a SOF unit during May and June 2018 by simple random sampling. They conducted a training of 5 km armed off-road strictly according to the assessment criteria of SOF. Their fatigue indexes were collected before and after training, and the results were compared and analyzed. A survey questionnaire about training conditions was conducted on 44 officers and 420 soldiers selected from a SOF unit by cluster sampling. The fatigue levels of different SOF training subjects was quantitatively scored and ranked. Results ① Compared with the resting values before 5 km armed off-road training, the peripheral blood level of lactic acid (P < 0.001) was increased significantly, while the pH value of saliva was decreased obviously after training (P=0.013). ② Their heart rate (P < 0.001) and blood perfusion index (P=0.015) were elevated remarkably, but the oxygen saturation was reduced (P < 0.001) after training. ③No significant differences were found in the handgrip strengths of the dominant and non-dominant hands and skin space thresholds before and after the training. ④The training reduced the indicators of neurobehavioral ability, such as memory scanning (P=0.030), visual attention span (P=0.007) and curve fitting ability index (P=0.001) in the subjects when compared with the data before training. ⑤Among the 16 training subjects, there were 6 SOF training subjects causing higher fatigue level than that of 5 km armed off-road training. Conclusion Five-kilometer armed off-road training is an activity of sub-severe intensity. Blood lactic acid, saliva pH value, heart rate, oxygen saturation, visual attention span, and curve fitting ability index can be used as sensitive indicators to evaluate the training fatigue of soldiers in SOF.

Objective To evaluate the training intensity and fatigue level after 400-meter barrier training in army special operations force (SOF), and to screen sensitive indicators for fatigue evaluation. Methods Twenty soldiers at professional posts were collected from a SOF unit during May and June 2018 by simple random sampling. They conducted a training of 400-meter barrier strictly according to the assessment criteria of SOF. Their fatigue indexes were collected before and after training. Results ① Compared with the resting level before 400-meter barrier training, the lactic acid level in the peripheral blood was increased significantly (P < 0.000 1). But there was no statistical difference in the pH value of saliva between pre- and post-training; ②Compared with the resting levels before training, the heart rate, systolic blood pressure, diastolic blood pressure and pulse pressure were elevated significantly after training (P < 0.000 1), but the blood perfusion index and oxygen saturation were decreased remarkably (P < 0.000 1, P=0.001 5); ③ Training showed no effect on the handgrip strength of the dominant and non-dominant hands and skin space thresholds; ④ The training reduced the indicators of neurobehavioral ability, such as visual attention span (P=0.038 4), but no such difference was seen in the other indexes. ⑤ The 400-meter barrier training showed better effectiveness on the improvement of heart rate and pulse pressure when compared with 5-kilometer armed off-road training (P=0.043 7, P < 0.000 1). Conclusion The 400-meter barrier training is an activity of severe intensity and can cause a higher fatigue level than 5-kilometer armed off-road training. Blood lactic acid, heart rate, pulse pressure, oxygen saturation and visual attention span can be used as sensitive indicators to evaluate the training fatigue in SOF soldiers after 400-meter barrier training.