AIM:To observe the effect of continuous light on the structure and differential metabolites of gut microbiota in mice.METHODS:The mice were randomly divided into normal light(light/dark,LD)group and 24-hour continuous light(light/light,LL)group.The body weight,fasting blood glucose,serum free fatty acids,serum triacylglycerol and serum total cholesterol levels of each group of mice were measured after 10 weeks.Fresh feces were collected,and 16S rRNA sequencing technology was used to study the effect of continuous light on the diversity,structure,and species composition of gut microbiota in mice.Additionally,liquid chromatography-mass spectrometry(LC-MS)analysis was per-formed to observe the effect of continuous light on the metabolites in mice.RESULTS:Compared with the LD group,the body weight,fasting blood glucose and lipid levels of the LL group were increased(P＜0.05).At the phylum level,the proportion of Firmicutes in the LL group increased,while the proportion of Bacteroidetes decreased.At the class level,the abundance of norank_f_Muribaculaceae and Prevotellaceae_UCG-001 in the LL group decreased significantly,while the abundance of Lactobacillus,Turicibacter and Odoribacter increased significantly.Non-targeted metabolomics analysis iden-tified 65 and 73 differential metabolites under positive and negative modes,involving six major metabolic pathways,in-cluding ABC transporters,purine metabolism,pyrimidine metabolism,secondary bile acid biosynthesis,protein digestion and absorption,and choline metabolism in cancer.CONCLUSION:The structure and metabolites of gut microbiota in mice exposed to continuous light are relatively specific,and inosine may be a key biomarker and potential therapeutic tar-get for biological clock disorders.

AIM:To explore the central mechanisms by which metformin(Met)attenuates insulin resistance in high-fat diet(HF)-fed rats.METHODS:Forty healthy male Sprague-Dawley rats were randomly divided into 4 groups:normal chow(NC)group,HF group,HF+Met group,and HF+Met+SHU9119[melanocortin 4 receptor(MC4R)antagonist]group,with 10 rats per group.Treatments with HF and Met lasted for 12 weeks,while SHU9119 was injected for the last 10 d.Skeletal muscle AMP-activated protein kinase(AMPK)and silent information regulator 1(SIRT1)ex-pression and activity were measured,along with mitochondria oxidative stress markers,mitochondrial function and quanti-ty.Systemic and skeletal muscle insulin sensitivity were assessed using the average glucose infusion rate from 60 to 120 min(GIR60-120)and 2-deoxyglucose uptake(DGU)during hyperinsulinemic-euglycemic clamp.RESULTS:The rats in HF group exhibited significantly reduced expression and activity of AMPK/SIRT1 in skeletal muscles(P<0.05).More-over,mitochondrial oxidative stress markers,reactive oxygen species(ROS)and malondialdehyde(MDA),were marked-ly elevated(P<0.05),and the activity of antioxidant enzymes glutathione peroxidase(GPX)and manganese superoxide dismutase(MnSOD)was significantly decreased in HF group(P<0.05).There was also a notable decline in the activity of citrate synthase(P<0.05),a marker of mitochondrial oxidative capacity,and the copy number of mitochondrial DNA in HF group.These changes were correlated with significantly decreased GIR60-120 and DGU(P<0.05).Notably,Met treat-ment(HF+Met)restored the AMPK/SIRT1 expression and activity,improved mitochondrial function,and reduced oxida-tive stress,leading to improved insulin sensitivity(P<0.05).However,these beneficial effects of Met were reversed by the MC4R antagonist SHU9119 in HF+Met+SHU9119 group.CONCLUSION:Treatment with Met enhances skeletal muscle AMPK/SIRT1 expression and activity,reverses mitochondrial dysfunction,and improves insulin resistance in HF-fed rats.These effects might be mediated through the activation of hypothalamic MC4R.

OBJECTIVE To investigate the effects of peiminine B （PEI） on Streptococcus pneumoniae （SP）-induced alveolar epithelial cell injury by regulating the Ras-related C3 botulinum toxin substrate 1 in nucleus accumbens （Rac1）/protein kinase B （Akt）/nuclear factor κB （NF-κB） signaling pathway. METHODS Human alveolar epithelial cells （HPAEpiC） were taken and randomly divided into the Control group， SP group （1×108 cfu/mL SP bacterial solution）， low-， medium-， and high-concentration PEI groups （1×108 cfu/mL SP bacterial solution+0.05， 0.10， 0.20 mmol/L PEI）， and high-concentration PEI+Akt activator group （P-H+SC79 group， 1×108 cfu/mL SP bacterial solution+0.20 mmol/L PEI+10 μmol/L SC79）. Except for the Control group， the other groups of cells were treated with SP bacterial solution and/or corresponding drug solution. After 24 h of treatment， the levels of inflammatory factors （interleukin-6， -18， -1β） in the supernatant solution， the contents of oxidative stress indexes [lactate dehydrogenase （LDH）， reactive oxygen species （ROS） and superoxide dismutase （SOD）]， apoptosis rate， as well as the expressions of proliferation/apoptosis-related proteins [cyclin-dependent kinase 1 （CDK1）， B cell lymphoma-2 related X protein （Bax）] and pathway-related proteins （Rac1， Akt， phosphorylated Akt， NF-κB and phosphorylated NF-κB） were detected in each group. RESULTS Compared with the Control group， the levels of inflammatory factors in supernatant solution， LDH and ROS contents， apoptosis rate， the protein expressions of Bax and Rac1 and the phosphorylation levels of Akt and NF-κB in the SP group were significantly increased or up-regulated， while SOD content and the protein expression of CDK1 were significantly decreased or down-regulated （P＜0.05）. Compared with the SP group， the above indexes in PEI groups were significantly improved in a concentration-dependent manner （P＜0.05）. SC79 could significantly reverse the improvement effect of the high concentration of PEI （P＜0.05）. CONCLUSIONS PEI can alleviate SP-induced inflammation and oxidative stress damage of alveolar epithelial cells and inhibit apoptosis， which may be achieved by inhibiting Rac1/Akt/NF-κB signaling pathway.

Objective To explore the effect of exenatide on oxidative stress in the hypothalamus of diabetes mice and its potential mechanism.Methods After one week of adaptive feeding,C57BL/6J mice were randomly divided into the CON group(normal chaw diet),the T2DM group(high-fat diet,HFD),and the T2DM+Exe group(HFD+exenatide).After 8 weeks of HFD,mice in the T2DM+Exe group were intraperitoneally injected with exenatide[24 nmol/(kg·d)]for 8 weeks.The weight and glucose and lipid metabolism levels of the mice were measured,and the levels of inflammatory and adipokine factors in mice were detected using the ELISA method.Western Blot was used to detect the expression of melanocortin receptor-4(MC4R)and proopiomelanocor-tin(POMC)in the hypothalamus.Hypothalamic mitochondria were extracted,and the content of mitochondrial reactive oxygen species(ROS)was measured using a flow cytometer.The content of malondialdehyde(MDA)and the activities of superoxide dismutase(SOD)in the mitochondria were detected using assay kits.Changes in the ultrastructure of mitochondria were observed using a transmission electron microscope.In vitro experiments,pal-mitic acid(PA)and exenatide were used to treat hypothalamic GT1-7 cells,and short hairpin RNA(shRNA)was used to silence the melanocortin 4 receptor(MC4R),and observe the cellular oxidative stress and lipid deposition.Results Compared with the CON group,the T2DM group mice showed a significant increase in glucose and lipid metabolism indicators,pro-inflammatory factors,and adipose factor levels(P<0.05),the expression of MC4R and POMC proteins in the hypothalamus were decreased(P<0.05),and the mitochondrial ROS and MDA content in the hypothalamus significantly were increased(P<0.05),while SOD and CAT activities were decreased(P<0.05).Mitochondrial morphology was abnormal.After intervention with exenatide,the above indicators were signifi-cantly improved.After inhibiting MC4R expression in vitro experiments,compared with the intervention group with exenatide,the ROS and MDA content was significantly increased(P<0.05),SOD activity was decreased(P<0.05),and lipid deposition occurred in the cells.Conclusions Exenatide exhibits a protective effect on hypotha-lamic oxidative stress injury in diabetic mice,and this mechanism may be associated with the upregulation of MC4R expression.

AIM:To explore the central mechanisms by which metformin(Met)attenuates insulin resistance in high-fat diet(HF)-fed rats.METHODS:Forty healthy male Sprague-Dawley rats were randomly divided into 4 groups:normal chow(NC)group,HF group,HF+Met group,and HF+Met+SHU9119[melanocortin 4 receptor(MC4R)antagonist]group,with 10 rats per group.Treatments with HF and Met lasted for 12 weeks,while SHU9119 was injected for the last 10 d.Skeletal muscle AMP-activated protein kinase(AMPK)and silent information regulator 1(SIRT1)ex-pression and activity were measured,along with mitochondria oxidative stress markers,mitochondrial function and quanti-ty.Systemic and skeletal muscle insulin sensitivity were assessed using the average glucose infusion rate from 60 to 120 min(GIR60-120)and 2-deoxyglucose uptake(DGU)during hyperinsulinemic-euglycemic clamp.RESULTS:The rats in HF group exhibited significantly reduced expression and activity of AMPK/SIRT1 in skeletal muscles(P<0.05).More-over,mitochondrial oxidative stress markers,reactive oxygen species(ROS)and malondialdehyde(MDA),were marked-ly elevated(P<0.05),and the activity of antioxidant enzymes glutathione peroxidase(GPX)and manganese superoxide dismutase(MnSOD)was significantly decreased in HF group(P<0.05).There was also a notable decline in the activity of citrate synthase(P<0.05),a marker of mitochondrial oxidative capacity,and the copy number of mitochondrial DNA in HF group.These changes were correlated with significantly decreased GIR60-120 and DGU(P<0.05).Notably,Met treat-ment(HF+Met)restored the AMPK/SIRT1 expression and activity,improved mitochondrial function,and reduced oxida-tive stress,leading to improved insulin sensitivity(P<0.05).However,these beneficial effects of Met were reversed by the MC4R antagonist SHU9119 in HF+Met+SHU9119 group.CONCLUSION:Treatment with Met enhances skeletal muscle AMPK/SIRT1 expression and activity,reverses mitochondrial dysfunction,and improves insulin resistance in HF-fed rats.These effects might be mediated through the activation of hypothalamic MC4R.

Objective To explore the effect of exenatide on oxidative stress in the hypothalamus of diabetes mice and its potential mechanism.Methods After one week of adaptive feeding,C57BL/6J mice were randomly divided into the CON group(normal chaw diet),the T2DM group(high-fat diet,HFD),and the T2DM+Exe group(HFD+exenatide).After 8 weeks of HFD,mice in the T2DM+Exe group were intraperitoneally injected with exenatide[24 nmol/(kg·d)]for 8 weeks.The weight and glucose and lipid metabolism levels of the mice were measured,and the levels of inflammatory and adipokine factors in mice were detected using the ELISA method.Western Blot was used to detect the expression of melanocortin receptor-4(MC4R)and proopiomelanocor-tin(POMC)in the hypothalamus.Hypothalamic mitochondria were extracted,and the content of mitochondrial reactive oxygen species(ROS)was measured using a flow cytometer.The content of malondialdehyde(MDA)and the activities of superoxide dismutase(SOD)in the mitochondria were detected using assay kits.Changes in the ultrastructure of mitochondria were observed using a transmission electron microscope.In vitro experiments,pal-mitic acid(PA)and exenatide were used to treat hypothalamic GT1-7 cells,and short hairpin RNA(shRNA)was used to silence the melanocortin 4 receptor(MC4R),and observe the cellular oxidative stress and lipid deposition.Results Compared with the CON group,the T2DM group mice showed a significant increase in glucose and lipid metabolism indicators,pro-inflammatory factors,and adipose factor levels(P<0.05),the expression of MC4R and POMC proteins in the hypothalamus were decreased(P<0.05),and the mitochondrial ROS and MDA content in the hypothalamus significantly were increased(P<0.05),while SOD and CAT activities were decreased(P<0.05).Mitochondrial morphology was abnormal.After intervention with exenatide,the above indicators were signifi-cantly improved.After inhibiting MC4R expression in vitro experiments,compared with the intervention group with exenatide,the ROS and MDA content was significantly increased(P<0.05),SOD activity was decreased(P<0.05),and lipid deposition occurred in the cells.Conclusions Exenatide exhibits a protective effect on hypotha-lamic oxidative stress injury in diabetic mice,and this mechanism may be associated with the upregulation of MC4R expression.

AIM:To observe the effect of continuous light on the structure and differential metabolites of gut microbiota in mice.METHODS:The mice were randomly divided into normal light(light/dark,LD)group and 24-hour continuous light(light/light,LL)group.The body weight,fasting blood glucose,serum free fatty acids,serum triacylglycerol and serum total cholesterol levels of each group of mice were measured after 10 weeks.Fresh feces were collected,and 16S rRNA sequencing technology was used to study the effect of continuous light on the diversity,structure,and species composition of gut microbiota in mice.Additionally,liquid chromatography-mass spectrometry(LC-MS)analysis was per-formed to observe the effect of continuous light on the metabolites in mice.RESULTS:Compared with the LD group,the body weight,fasting blood glucose and lipid levels of the LL group were increased(P＜0.05).At the phylum level,the proportion of Firmicutes in the LL group increased,while the proportion of Bacteroidetes decreased.At the class level,the abundance of norank_f_Muribaculaceae and Prevotellaceae_UCG-001 in the LL group decreased significantly,while the abundance of Lactobacillus,Turicibacter and Odoribacter increased significantly.Non-targeted metabolomics analysis iden-tified 65 and 73 differential metabolites under positive and negative modes,involving six major metabolic pathways,in-cluding ABC transporters,purine metabolism,pyrimidine metabolism,secondary bile acid biosynthesis,protein digestion and absorption,and choline metabolism in cancer.CONCLUSION:The structure and metabolites of gut microbiota in mice exposed to continuous light are relatively specific,and inosine may be a key biomarker and potential therapeutic tar-get for biological clock disorders.

Objective:To provide references for cardiovascular health management of military pilots by investigating the risk of ischemic cardiovascular diseases (ICVD) in military pilots.Methods:The physical examination data of military pilots in Air Force Healthcare Center for Special Services Hangzhou were retrospectively analyzed. The military pilots were divided into 2 groups by age (22-34 years, 35-56 years), and they were divided into 5 groups by flying hours (≤500 h, 500-≤1 000 h, 1 000-≤2 000 h, 2 000-≤3 000 h, >3 000 h). The 10-year ICVD incidence risk of pilots was evaluated according to the 10-year ICVD incidence risk assessment table of Chinese people. The distribution and influencing factors of absolute risk and relative risk of ICVD incidence in military pilots were analyzed, and the risk factors between different age groups were compared.Results:①A total of 337 military pilots were included, 194 in the 22-34 years group and 143 in the 35-56 years group. ②Absolute risk detection: there were 336 very low-risk military pilots and a low-risk military pilot. Relative risk detection: 87 (25.82%) military pilots were relatively high risk including 41 (21.13%) cases in 22-34 years group, 46 (32.17%) cases in 35-56 years group, the difference between 2 groups was statistically significant ( χ2=5.23, P=0.022); there were 250 (74.18%) relatively low-risk military pilots. ③Among the pilots aged 22-34 years, there was significant difference in relative high-risk ratio between flying hours ( χ2=17.00, P<0.001). The relative high-risk ratio of the pilots with flying hours 500-≤1 000 h was higher than that of pilots with flying hours ≤500 h, and the difference was statistically significant ( P<0.05); the proportion of pilots with elevated triglyceride and low density lipoprotein cholesterol indexes was higher than that of those with normal indicators (all P<0.05). The relative high-risk ratio of pilots with hypertension in 35-56 years group was higher than that of those with normal blood pressure ( χ2=23.70, P<0.001); the proportion of pilots with elevated triglyceride indicators was higher than that of high-risk groups ( P<0.05). ④The smoking rate, BMI and total cholesterol abnormality rate were higher in the 35-56 years group than in the 22-34 years group, and the differences were statistically significant ( χ2=9.71, 29.72, 19.17, P=0.002, <0.001,<0.001). ⑤The aggregation analysis of the risk factors of smoking, BMI, total cholesterol, systolic blood pressure and diabetes showed that the number of risk factor aggregates ≥2 species accounted for 51.04%, and the aggregation of risk factors in different age groups was statistically significant ( Z=6.38, P<0.001). Conclusions:The relative risk of ICVD in pilots is high, and the aggregation of risk factors is serious. Simply improving a single index is hardly to meet the demand of risk reduction. It needs a variety of joint interventions to improve the lifestyle and reduce the abnormal rate of total cholesterol, overweight rate, systolic blood pressure level and smoking rate. It is suggested that ICVD incidence risk prediction score should be routinely used in the risk assessment of chronic diseases in aviation medicine.

Objective:To provide references for cardiovascular health management of military pilots by investigating the risk of ischemic cardiovascular diseases (ICVD) in military pilots.Methods:The physical examination data of military pilots in Air Force Healthcare Center for Special Services Hangzhou were retrospectively analyzed. The military pilots were divided into 2 groups by age (22-34 years, 35-56 years), and they were divided into 5 groups by flying hours (≤500 h, 500-≤1 000 h, 1 000-≤2 000 h, 2 000-≤3 000 h, >3 000 h). The 10-year ICVD incidence risk of pilots was evaluated according to the 10-year ICVD incidence risk assessment table of Chinese people. The distribution and influencing factors of absolute risk and relative risk of ICVD incidence in military pilots were analyzed, and the risk factors between different age groups were compared.Results:①A total of 337 military pilots were included, 194 in the 22-34 years group and 143 in the 35-56 years group. ②Absolute risk detection: there were 336 very low-risk military pilots and a low-risk military pilot. Relative risk detection: 87 (25.82%) military pilots were relatively high risk including 41 (21.13%) cases in 22-34 years group, 46 (32.17%) cases in 35-56 years group, the difference between 2 groups was statistically significant ( χ2=5.23, P=0.022); there were 250 (74.18%) relatively low-risk military pilots. ③Among the pilots aged 22-34 years, there was significant difference in relative high-risk ratio between flying hours ( χ2=17.00, P<0.001). The relative high-risk ratio of the pilots with flying hours 500-≤1 000 h was higher than that of pilots with flying hours ≤500 h, and the difference was statistically significant ( P<0.05); the proportion of pilots with elevated triglyceride and low density lipoprotein cholesterol indexes was higher than that of those with normal indicators (all P<0.05). The relative high-risk ratio of pilots with hypertension in 35-56 years group was higher than that of those with normal blood pressure ( χ2=23.70, P<0.001); the proportion of pilots with elevated triglyceride indicators was higher than that of high-risk groups ( P<0.05). ④The smoking rate, BMI and total cholesterol abnormality rate were higher in the 35-56 years group than in the 22-34 years group, and the differences were statistically significant ( χ2=9.71, 29.72, 19.17, P=0.002, <0.001,<0.001). ⑤The aggregation analysis of the risk factors of smoking, BMI, total cholesterol, systolic blood pressure and diabetes showed that the number of risk factor aggregates ≥2 species accounted for 51.04%, and the aggregation of risk factors in different age groups was statistically significant ( Z=6.38, P<0.001). Conclusions:The relative risk of ICVD in pilots is high, and the aggregation of risk factors is serious. Simply improving a single index is hardly to meet the demand of risk reduction. It needs a variety of joint interventions to improve the lifestyle and reduce the abnormal rate of total cholesterol, overweight rate, systolic blood pressure level and smoking rate. It is suggested that ICVD incidence risk prediction score should be routinely used in the risk assessment of chronic diseases in aviation medicine.

Objective: To investigate the correlation between takeaway food consumption and poor sleep status of college students in Jiangxi Province, to provide a theoretical basis for poor sleep prevention and intervention among college students. Methods: A total of 2 610 college students were selected from a university in Shangrao City, Jiangxi Province by cluster stratified random sampling in May of 2018. The frequency and type of takeaway food consumption, sleep quality and drowsiness were investigated. Results: The detection rate of takeaway food consumption behavior(≥4 times in a week) for college students was 74.8%. The detection rates of poor sleep quality and drowsiness were 17.0% and 18.3%, respectively. The difference of sleep quality was statistically significant with sex, college, different self rated family conditions, study burden, physical activity level, depression and daily smoking ( χ 2=4.33，8.67，23.14，39.03，12.89，313.37，15.23， P <0.05). There were statistically significant differences between drowsiness and college, grade, learning burden, physical activity and depression ( χ 2=12.81，6.57，20.61，8.42，228.06， P <0.05). Logistic regression analysis showed that takeaway consumption (≥4 times in a week) had statistical significance with poor sleep quality and drowsiness ( P <0.05). Conclusion College students takeaway consumption (≥4 times in a week) of rice noodles, malatang, fragrant pot hot pot increase the risk of poor sleep. It is suggested that schools should strengthen nutrition and health education for college students.