Objective:To investigate the interventional and protective effect of low-dose L-carnitine(LC)against reproductive system damage in male Wistar rats during acute exposure to simulated high-altitude environment.Methods:A total of 24 specific pathogen-free male Wistar rats,aged 12 weeks,were randomly divided into control group,high-altitude model group,and LC intervention group[intraperitoneal injection of LC at a dose of 50 mg/(kg·d)],with 8 rats in each group.The rats in the control group were fed under normal conditions(at an altitude of approximately 1 500 m),those in the high-altitude model group,and those in the LC intervention group were fed in a hypobaric oxygen chamber(at a simulated alti-tude of 6 000 m).The rats were sacrificed after 3 days.The testis was collected to calculate testicular index;the semen was collected from the epididymis,and the Weili sperm quality analysis system was used to assess sperm quality;blood samples were collected from the abdominal aorta,and ELISA kits were used to measure the serum levels of testosterone(T),luteinizing hormone(LH),and follicle-stimulating hormone(FSH);testicular tissue samples were collected,and biochemical kits were used to measure the activity of reactive oxygen species(ROS),malondialdehyde(MDA),and superoxide dismutase(SOD);testicular tissue was collected to prepare HE and electron microscopy sections,and a light microscope and a transmission electron microscope were used for observation.Results:Com-pared with the blank control group,the high-altitude model group had significant increases in the levels of T,LH,and FSH(P<0.01),testicular tissue damage under the light microscope,and changes in the morphology of spermatogenic cells,including mitochondrial al-terations,membrane edema,loss of cristae,swelling of the matrix,and local dissolution,as well as significant increases in the levels of ROS and MDA(P<0.01)and a significant reduction in SOD activity(P<0.01).Compared with the high-altitude model group,the LC intervention group had a significant increase in the level of T(P<0.01),significant reductions in the levels of FSH and LH(P<0.01),and significant improvements in the pathological changes of testicular tissue,with no marked mitochondrial injury,and there were sig-nificant reductions in the levels of ROS and MDA(P<0.01)and a significant increase in SOD activity(P<0.01).There was no signifi-cant difference in testicular index between groups(P>0.05).The high-altitude model group had a significantly lower sperm count than the blank control group(P<0.05),while there was no significant difference in sperm count between the LC intervention group and the blank control group(P>0.05);there was no significant difference in sperm motility between groups(P>0.05).Conclusion:Low-dose LC can improve reproductive system damage in rats during acute exposure to simulated high-altitude environment,possibly by alleviat-ing oxidative stress response.

Objective: To investigate the effects of plateau environment exposure on the reproductive system of male rats, so as to provide the reference for mechanisms of reproductive damage in plateau environment. Methods: Sixty SPF-grade 12-week-old male Wistar rats were randomly divided into the plain-exposed group, the 1 day-, 3 day-, 7 day-, 14 day- and 28 day- plateau-exposed groups. The rats in the plain-exposed group were raised under normal conditions for 28 days, while the rats in the plateau-exposed groups were raised in a simulated high-altitude plateau chamber. After the completion of the designated feeding periods, the rats were sacrificed under anesthesia, and testicular tissue and abdominal aortic blood were collected to detect the testicular index and evaluate sperm quality. Histological and cellular morphologies of the testicular tissue were analyzed. Additionally, the levels of malondialdehyde (MDA), superoxide dismutase (SOD) and reactive oxygen (ROS) in the testicular tissue were determined, along with serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH) and testosterone (T). Conclusions Plateau environment may cause a decrease in testicular index and sperm quality, impair mitochondrial function, induce oxidative stress, and thus affect reproductive system of male rats. However, there are signs of self-repair in the reproductive system with the increase of exposure duration.

Objective:To understand the current situation and trend of nursing cost research in China so as to provide a reference for researchers in the field of nursing cost research.Methods:We retrieved literature on nursing cost from January 1, 1990 to December 13, 2019 in China National Knowledge Infrastructure (CNKI) . CiteSpace software was used for visual analysis.Results:A total of 463 related literature were obtained, and the number of publications was on the rise as a whole, and research institutions had little cooperation. Nursing economics, nursing human resources, nursing management, cost analysis were the main research directions at present. Long-term care insurance with the highest emergent word intensity was the research frontier in the field.Conclusions:We should strengthen the cooperation in scientific research institutions, and rely on big data, computers and other means to establish a nursing cost accounting model, and extend the scope of research to communities and homes so as to provide a quantitative basis for Chinese long-term care insurance compensation standards.