[Effects of rapid and progressive ascent to Tibet plateau on cardiovascular function and stress factors of pre-selected expeditioners for Chinese Antarctic expedition for Kunlun station].

Objective: To explore the different effects of rapid and progressive ascent to Tibet plateau on cardiovascular function and stress factors in pre-selected expeditioners for the 31st, 32nd and 33rd Chinese Antarctic expedition for inland station, to provide a scientific basis for the selection of qualified expeditioners. Methods: A total of 85 pre-selected expeditioners for the 31st, 32nd and 33rd Chinese Antarctic expedition for Kunlun station were enrolled in this study. According to the different manners of entering the plateau, they were divided into the rapid ascent group by aircraft (RAG, n=55) and the progressive ascent group by train (PAG, n=30). Hemodynamics and electrocardiogram were examined at 4 m (Shanghai), areas at altitude of 3 658 m (Lhasa) and 4 300 m(Yangbajain), respectively. Saliva levels of stress factors, including testosterone (T), cortisol (COR) and immunoglobulin A (IgA), were tested by ELISA. Results: The heart rates (HR) were increased significantly, while the SpO2 was decreased significantly in the two groups within 24 hours at altitudes of 3 658 m and 4 300 m (P＜0.05), while there was no significant difference between the two groups at the same altitude. Compared with 4 m, the blood pressure (BP) of the two groups at 3 658 m and 4 300 m was significantly increased (P＜0.05), and some indexes of myocardial contraction and pumping function were significantly reduced (P＜0.05). However, due to the increase of HR, there was no significant change in Cardiac Output (CO). At 4 300 m, the Thoracic Fluid Content (TFC) of the rapid ascent group was significantly higher than that of the progressive ascent group (P＜0.05). Compared with 4m, there was no significant difference in salivary testosterone change between the two groups at 3 658 m above sea level (P＞0.05), while COR and IgA changes in the rapid ascent group were significantly higher than those in another group (P＜0.05). Conclusion: Compared with the progressive ascent by train,expeditioners that rapid ascent to high altitude have significant effects on cardiovascular function and the stress hormones and immunoglobulin levels in saliva. It's suggested that hypoxia adaptation before Antarctic expediting for Kunlun Station could ensure the selected expeditioners' physical and psychological health, so that the mission could be finished smoothly.

[Effects of simulated 5 500 m hypobaric and hypoxia on HPT axis and intestinal flora in rats].

Objective: To investigate the effects of simulated hypoxia environment at an altitude of 5 500 meters on hypothalamic-pituitary-thyroid (HPT) axis and intestinal flora of rats and the correlation between them. Methods: The hypoxia model of adult male SD rats was established by hypobaric chamber with simulated altitude of 5 500 m. The hypoxia groups were set for 1, 3, 7, 14, 21 and 28 days, and the normoxic recovery group were set for 1 and 3 days after hypoxia (8 rats per group, hypoxia time 24h per day). Daily body weight and food intake of rats were recorded. The serum levels of HPT axis hormones were detected by enzyme-linked immunosorbent assay (ELISA). Intestinal flora was analyzed by 16s rDNA sequencing. The correlation between intestinal flora and serum HPT axis hormone was analyzed by Spearman correlation analysis. Results: Compared with the normoxic group, the body weight and food intake were significantly reduced (P＜0.01). In the 1-day and 3-day groups, the levels of thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (TSH) were decreased significantly (P＜0.05), the levels of total thyroxine (TT4), total triiodothyronine (TT3), free thyroxine (FT4) and free triiodothyronine (FT3) were increased significantly (P＜0.05), and the abundance of Prevotella was decreased significantly (P＜0.05), while those of Parabacteroides, Lactobacillus, Butyricimonas, Bacteroides, Odoribacter and RC4-4 were increased significantly (P＜0.05). In the 14-day, 21-day and 28-day hypoxia groups, the levels of TRH and TSH were decreased significantly (P＜0.05), and the levels of TT4 and TT3 were increased significantly (P＜0.05), and there was no significant difference in other indexes, the abundance of Parabacteroides, Sphaerochaeta, Akkermansia, Elusimicrobium was increased significantly, but that of Lactobacillus and Sutterella was decreased significantly (P＜0.05). Correlation analysis of intestinal flora and HPT axis hormones showed that Butyricimonas, Elusimicrobium and Sutterella were significantly negatively correlated with TRH and TSH (P＜ 0.05), Prevotella, Bacteroides, Odoribacter and Parabacteroides were significantly correlated with TSH, TT4, TT3 and FT4 (P＜ 0.05), respectively. Lactobacillus was significantly correlated with TRH, TSH and FT4 (P＜0.05). Akkermansia was significantly correlated with TRH and FT4 (P＜0.05). RC4-4 was significantly associated with TSH and TT3 (P＜0.05). Conclusion: Hypoxia stress at an altitude simulating 5500 meters significantly changed the composition of the intestinal flora of SD rats. This may be a change in thyroid function adapted to the hypoxia environment, and the degree of change is related to the time of hypoxia stress. The change of intestinal microflora is significantly correlated with the hormone level of HPT axis.

[Effects of exhaustive exercise-induced oxidative stress on red blood cell deformability].

OBJECTIVE: The aim of the present study is to explore the effects of exhaustive exercise-induced oxidative stress on the antioxidant capacity and diformability of rat red blood cells. METHODS: Rats were divided into three group (n = 10): sedentary control (C), exhaustive running exercise (ERE) and moderate running exercise (MRE) groups. Animals in the ERE group started treadmill running at a speed of 20 m/min speed with a 5% gradient, and reached a speed of 25 m/min with gradient 15% in 20 min. Running was continued until exhaustion. MRE group rats running at a speed of 20 m/min with a 5% gradient for 40 min. The levels of free thiol in erythrocyte membrane protein, lipidperoxidation levels and membrane protein components were analyzed. The red blood cell deformability of different groups was also observed. RESULTS: The results showed that red blood cells were damaged by severe oxidative stress and the anti-oxidative capacity decreased significantly under exhaustive exercise conditions. Besides, lipid peroxidation and protein sulfhydryl cross-link based clustering of membrane were found after exhaustive exercise, and polymers high molecular weight (HMW) was formed. The elongation index (EI) was found to decline significantly in the ERE group compared with the C and MRE groups under shear stress (control group, 0.41 +/- 0.01 at 3 Pa and 0.571 +/- 0.008 at 30 Pa; ERE group, 0.314 +/- 0.013 at 3 Pa and 0.534 +/- 0.009 at 30 Pa; P < 0.05 and P < 0.01, respectively). CONCLUSION: These exercise-induced oxidative injure result in a significant decrease in deformability of rat erythrocytes, which in turn leads to dysfunction in the microcirculatory.

[Effect of HIF-1alpha on sex hormone levels and germ cell apoptosis of mice].

OBJECTIVE: To study the effect of hypoxia on hypothalamus-adenohypophysis-testis axis hormone levels, germ cell apoptosis and hypoxia-inducible factor-1alpha (HIF-1alpha) expression in testis of adolescent mice, and explore HIF-1alpha regulation on the reproductive function of male mice. METHODS: Eighty SPF grade adolescent C57BL/6 mice were randomly divided into normoxia group, hypoxia 3, 7, 14 and 28 d groups. The level of serum testosterone (T), free testosterone (FT), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) was analyzed by ELISA. Detected the sperm count, motility rate and abnormal sperm rate of epididymal sperm suspension. The apoptosis cells in testis were determined using TUNEL method. The expression of HIF-1alpha was analyzed using Western blot. RESULTS: Compared with corresponding normoxia group, serum T, FT, FSH and LH concentrations in hypoxia 3 d group were significantly higher (P < 0.05); T and LH concentrations in hypoxia 14 d group were significantly lower (P < 0.05). Sperm count and motility rate in hypoxia 7 and 14 d groups significantly declined (P < 0.05); abnormal sperm rate in all hypoxia groups significantly increased (P < 0.05). The apoptosis index (AI) of germ cells in hypoxia 7, 14 and 28 d groups significantly increased (P < 0.05), and the levels of HIF-1alpha protein expression were significantly higher (P < 0.05). CONCLUSION: HIF-1alpha protein highly expressed in mice testis could induce germ cell apoptosis increased in chronic hypoxia environment.

Fluorouracil selectively enriches stem-like cells in the lung adenocarcinoma cell line SPC.

Most adult stem cells are in the G0 or quiescent phase of the cell cycle and account for only a small percentage of the cells in the tissue. Thus, isolation of stem cells from tissues for further study represents a major challenge. This study sought to enrich cancer stem cells and explore cancer stem-like cell clones using 5-fluorouracil (5-FU) in the lung adenocarcinoma cell line, SPC. Proliferation inhibition was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, according to which half maximal inhibitory concentration values were calculated. Expression levels of stem cell markers after treatment with 5-FU were examined using immunofluorescence and Western blotting. Additionally, side population (SP) cells were sorted using FACS. Properties of SP cells were evaluated by using Transwell, colony-forming assays, and tumor formation experiments. 5-FU greatly inhibits proliferation, especially of cells in S phase. SP cells possess greater invasive potential, higher clone-forming potential, and greater tumor-forming ability than non-SP cells. Treatment with 5-FU enriches the SP cells with stem cell properties in human lung adenocarcinoma cell lines.