Objective:To understand the distribution characteristics of pulse oxygen saturation (SpO 2) in the high altitude areas. Methods:From September 2016 to December 2017, all healthy and full-term live births in the First Hospital of Lanzhou University and Dunhuang, Jiuquan, Jingning and Lintao branches were selected as the research objects.Critical congenital heart disease or pulmonary diseases were excluded in advance.SpO 2 in different parts of newborns within 12 hours of birth was measured.Statistical comparisons of SpO 2 in different parts of male and female neonates in the same area and SpO 2 in different parts of different regions were made.The number of SpO 2 and the distribution of percentile difference between the lower limbs and the right upper limb of newborns at different altitude areas were obtained. Results:There were no significant difference between male and female infants in SpO 2 value at any lo-wer extremity and right upper extremity and the difference value in the same area (all P>0.05). There were significant differences in the median ( M) values of SpO 2 and the M value of the difference between the two values of any lower limb and right upper limb at different altitudes (all P<0.05). The results showed that the M value of SpO 2 of the right upper limb ( M=96%) in Lanzhou (1 520 m above sea level) was lower than that in Dunhuang (1 138 m above sea level, M=97%) and Jiuquan (1 481 m above sea level, M=97%), and the M value of the difference between the two values ( M=2%) was higher than that in Dunhuang and Jiuquan ( M=1%) ( P<0.05). The M of SpO 2 of any lower limb ( M=96%) and right upper limb ( M=96%) in Jingning areas (1 668 m above sea level) were lower than that in Dunhuang and Jiuquan area (all P<0.05). The median value of SpO 2 of any lower limb ( M=96%) and right upper limb ( M=96%) in Lintao area (1 883 m above sea level) was lower than that in Dunhuang and Jiuquan areas, and the M value of the difference between the two values ( M=2%) was higher than that in Dunhuang and Jiuquan (all P< 0.05). When the altitude was lower than 1 500 m, the M value of SpO 2 was 97%, P3- P97 was 93%-100%; the M value of the difference between any lower limb and right upper limb was 1, and P3- P97 was 0-4.When the altitude was higher than 1 500 m, the M value of SpO 2 was 95%-96%, P3- P97 was 89%-100%; the M value of SpO 2 of an lower limb and right upper limb was 1%-2%, and P3- P97 was 0-9%. Conclusions:The SpO 2 number and percentage distribution of the difference between any lower limb and right upper limb of newborns at different altitudes are different.

Objective To investigate the protective effect of insulin-like growth factor-1(IGF-1)precondi-tioning on hypoxic injury in H9c2 rat cardiomyocytes and its mechanism.Methods H9c2 cells were randomly divided into four groups,control group,hypoxia group(CoCl2 group),hypoxia+IGF-1 pretreatment group(CoCl2+IGF-1 group),hypoxia+IGF-1 pretreatment+phosphatidylinositol 3 kinase(PI3K)/protein kinase B(Akt)pathway specific inhibitor LY294002 group(CoCl2+IGF-1+LY294002 group).CCK8 assay was used to detect the survival rate of H9c2 cells,and Tunel assay was used to detect the apoptosis of H9c2 cells,DCFH-DA probe method was used to detect the reactive oxygen species(ROS)level of H9c2 cells in each group.The activities of superoxide dismutase(SOD)and lactate dehydrogenase(LDH)in culture supernatant were detected by kit.The levels of glutathione peroxidase(GSH-Px)and malondialdehyde(MDA)in culture supernatant were detected by enzyme-linked immunosorbent assay(ELISA).Western blot was used to detect the expression of pro-apoptotic protein B cell lymphoma 2 associated X protein(Bax),Caspase-3,anti-apoptot-ic protein Bcl-2,pathway proteins Akt and phosphorylated Akt(p-Akt)in H9c2 cells.Results IGF-1 could increase cell viability(P＜0.05),reduced cell apoptosis rate(P＜0.05),reduced ROS level(P＜0.05),re-duced MDA production(P＜0.05),reduced LDH activity(P＜0.05),and increased SOD and GSH-Px activi-ties(P＜0.05).It also promoted the expression of p-Akt(P＜0.05),reduced the expression of pro-apoptotic proteins Bax and Caspase-3(P＜0.05),and increased the expression of anti-apoptotic protein Bcl-2(P＜0.05).After the addition of PI3K pathway specific inhibitor LY294002,the protective effect of IGF-1 on hy-poxic H9c2 cells disappeared.Conclusion IGF-1 protects cardiomyocytes from hypoxia injury by inhibiting oxidative stress and apoptosis of cardiomyocytes through activating PI3K/Akt pathway and improving the survival rate of cardiomyocytes.