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Objective:To explore the mechanism of lysosomal membrane permeabilization(LMP)inuranyl acetate-induced death of human kidney proximal tubular epithelial HK-2 cells.Methods:HK-2 cells were exposed to uranyl acetate at concentrations of 100, 300 and 600 μmol/L for 24 h, then in tracellular reactive oxygen species (ROS)and mitochondrial superoxide were measured by DCFH-DA and MitoSOX probe, respectively. HK-2 cells were divided into four groups: blank control group, NAC or CA-074 Me group, uranyl acetate exposure group and uranyl acetate exposure plus NAC or CA-074 Me group. Two-color immune of luorescence staining was used to detect the co-localization of galectin-1 and lysosomal associated membrane protein-1 (LAMP-1) to measure the extent of LMP, and to detect the non- co-localization of cathepsin B and LAMP-1 to reflect the release of cathepsin B in lysosomes. Calcein-AM/PI double staining method was used to detect cell death. One-color immune of luorescence staining of cleaved-caspase-3 expression was used to detect apoptosis. Results:Intracellular ROS and mitochondrial superoxide levels were significantly increased in HK-2 cells after exposure with 100, 300 and 600 μmol/L uranyl acetate for 24 h, about 1.1-2.5 times or 4.0-28 times, respectively( tROS=17.98, 11.84, 11.75, P< 0.05; tmitochondrial superoxide=6.14, 16.02, 13.06, P< 0.05), and they also increased with uranyl acetate concentrations ( tROS=10.10, 10.37, 5.59, P< 0.05; tmitochondrial superoxide=21.50, 15.16, 5.93, P< 0.05). The percentage of co-localization of galectin-1 and LAMP-1 and the percentage of non- co-localization of cathepsin B and LAMP-1 were markedly increased in HK-2 cells after exposure with 600 μmol/L uranyl acetate for 24 h, 5.4-6.7 times or 1.5-2.1 times, respectively ( tGalectin-1=15.85, 12.70, P< 0.05; tCathepsin B=5.95, 6.69, P< 0.05), but these increases were inhibited by NAC ( tGalectin-1=4.74, P<0.05; tCathepsin B=4.51, P< 0.05). Moreover, the cell death rate and the cleaved-caspase-3 expression level were also significantly increased in HK-2 cells after exposure with 600 μmol/L uranyl acetate for 24 h, about 28-47 times or 2.4-6.0 times, respectively( tPI=30.40, 10.34, P<0.05; tCleaved-caspase-3=18.49, 9.52, P<0.05), and these increases were obviously diminished by CA-074 Me ( tPI= 6.76, P<0.05; tCleaved-caspase-3=13.47, P<0.05). Conclusions:Exposure to uranyl acetate induces a burst of intracellular ROSthat leads to LMP and consequently causes leakage of cathepsin B from lysosomes to cytoplasm, in turn triggering the lysosomal-dependent cell death and mitochondrial-regulated apoptosis of HK-2 cells.
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Objective To explore the effect of umbilical artery blood pH on the diagnosis of neonatal asphyxia and the evaluation of its prognosis. Methods Blood samples were obtained from 108 normal newborns and 51 asphyxial newborns,who were randomly chosen among newborns delivered in our hospital from november 2007 to may 2008. Umbilical artery blood gas was measured and compared with apgur rating. Results With the degression of umbilical blood pH, the incidence rate of neonatal asphyxia increased and the normal apgar rating decreased(P < 0.01), which suggesting that there was tight relevant between umbilical blood pH and neonatal asphyxia. Conclusion Compared with apgur rating, umbilical artery blood pH could reflect the asphyxia degree of newborns more objectively andsensitively and it might play a guiding role in the prognosis of neonatal asphyxia.