[Effect of microRNA-34a/SIRT1/p53 signal pathway on notoginsenoside R1 delaying vascular endothelial cell senescence].

This study aimed to investigate the effect of notoginsenoside R1 in delaying H2O2-induced vascular endothelial cell senescence through microRNA-34a/SIRT1/p53 signal pathway. In this study， human umbilical vein endothelial cells(HUVECs) were selected as the study object; the aging model induced by hydrogen peroxide(H2O2) was established， with resveratrol as the positive drug. HUVECs were randomly divided into four groups， youth group， senescence model group， notoginsenoside R1 group and resveratrol group. Notoginsenoside R1 group and resveratrol group were modeled with 100 µmoL·L⁻¹ H2O2 for 4 h after 24 h treatment with notoginsenoside R1(30 µmoL·L⁻¹) and resveratrol(10 µmoL·L⁻¹) respectively. At the end， each group was cultured with complete medium for 24 h. The degree of cellular senescence was detected by senescence-associated ß-galactosidase(SA-ß-Gal) staining kit， the cell viability was detected by cell counting kit-8， the cell cycle distribution was analyzed by flow cytometry， and the cellular SOD activity was detected by WST-1 method in each group. The expressions of SIRT1， p53， p21 and p16 proteins in HUVECs were detected by Western blot. In addition， the mRNA expressions of miRNA-34a， SIRT1 and p53 in HUVECs were assayed by Real-time PCR. These results indicated that notoginsenoside R1 significantly reduced the positive staining rate of senescent cells， enhanced the cell proliferation capacity and intracellular SOD activity， decreased the proportion of cells in G0/G1 phase， and increased the percentage of cells in S phase simultaneously compared with the senescence model group. Moreover， notoginsenoside R1 decreased the mRNA expressions of miRNA-34a and p53 and the protein expression of p53， p21 and p16.At the same time， notoginsenoside R1 increased the protein and mRNA expressions of SIRT1. The differences in these results between the senescence model group and the notoginsenoside R1 group were statistically significant(P<0.05). However， there was not statistically significant difference in these results between the notoginsenoside R1 group and the resveratrol group. In conclusion， the senescence of endothelial cells induced by H2O2 can be used as a model for studying aging. Notoginsenoside R1 has an obvious anti-aging effect on vascular endothelial cells in this study. The possible mechanism is that notoginsenoside R1 can delay the senescence process of vascular endothelial cells induced by H2O2 by regulating microRNA-34a/SIRT1/p53 signal pathway.

[Study on calcium absorption rate in premenarche Chinese girls aged 9 - 11.5 years].

OBJECTIVE: To investigate the characteristics of calcium metabolism in relation to different levels of dietary calcium intakes in premenarche Chinese girls. METHODS: Forty-nine healthy premenarche girls of Han ethic (9 - 11.5 years) were recruited, and divided into four groups respectively, receiving four different doses of calcium intakes for 6 days, 600 mg (usual diet), 900 mg (containing 250 ml of milk), 1200 mg (containing 250ml of milk and 750 mg of calcium carbonate) and 1500mg calcium (250 ml of milk and 1500 mg of calcium carbonate) per day. A 3-day urine and stool, and a 3-d duplicated food samples were collected to assess the calcium excretion in urine and feces and input of the dietary calcium during the treatment period. RESULTS: There were no significant differences in appearance calcium absorption among the four groups (55%, 53%, 52% and 52%). Urine calcium is correlated negatively with dietary protein and dietary phosphorus. And no correlation was found between dietary protein and calcium absorption. CONCLUSION: The appearance calcium absorption was (53 +/- 0.12) % in Chinese premenarche girls with dietary calcium intakes ranged between 800 to 1600 mg/d, high dietary protein intakes increase urine calcium secrete.