Objective To explore in vitro the best time window for using sinusoidal electromagnetic fields to promote the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs).Methods BMSCs were isolated and cultured from 4-week-old Sprague-Dawley rats (male and female,80-120g).The BMSCs (from passage 3) were exposed 0,1,4 or 8h/d for 7d,14,or 28d,respectively,to 15Hz sinusoidal electromagnetic fields with a maximum amplitude of lmT.Those exposed 0h/d served as the control.The relative expressions of runt related gene-2 (RUNX2),bone sialoprotein (BSP) and osteopontin (OPN) were determined using real-time,quantitative reverse transcription-polymerase chain reactions (RT-PCRs).The level of RUNX2 protein was determined by Western blotting after 14d.Alizarin red staining was used to compare calcium distribution in each group.Results Obvious promotion of differentiation to osteoblasts was observed after 7 days of exposure to the15 Hz sinusoidal electromagnetic fields,most obviously manifested by an outstanding increase of the early osteogenic index RUNX2 in those exposed 4h/d.After 14 days of intervention,the 1h/d exposure showed to be most effective,especially in inducing the changes of the late osteogenic index OPN.The trends of changes in RUNX2 protein were similar in all groups.After stimulating 1h/d for 14 and 28days,calcium deposition increased to the greatest extent.Conclusions Exposure to sinusoidal electromagnetic fields induces osteogenic differentiation to osteoblasts in rat BMSCs in vitro.There is an apparent window effect.The best results are observed with more days of exposure and shorter exposure time (1h) every day.

ObjectiveTo investigate the relationship between hyponatremia and degree of liver injury, complications and survival time, and the prognostic value of hyponatremia in patients with decompensated liver cirrhosis. MethodsA total of 218 patients who were diagnosed with decompensated liver cirrhosis for the first time in The First Affiliated Hospital of Dalian Medical University from January 2000 to March 2005 were enrolled in this study, and according to the serum sodium concentration, these patients were divided into group Ⅰ with a serum sodium concentration of ≥130 mmol/L (n=51), group Ⅱ with a serum sodium concentration of ≥120 and ＜130 mmol/L (n=97), group Ⅲ with a serum sodium concentration of ＜120 mmol/L (n=70). The patients′sex, age, serum sodium concentration, Child-Pugh class, and complications were analyzed, and the survival time was calculated. The one-way analysis of variance was applied for comparison of continuous data between groups, and the least significant difference t-test was applied for comparison between any two patients; the chi-square test was applied for comparison of categorical data between groups; the Kaplan-Meier method was applied for survival analysis, and the Cox regression model was applied for regression analysis. ResultsCompared with groups Ⅰ and Ⅱ, group Ⅲ had the highest proportion of patients with Child-Pugh C cirrhosis. With the increasing Child-Pugh score, the serum sodium concentration decreased; the serum sodium concentration showed significant differences across the patients with Child-Pugh A, B, and C cirrhosis (F=17.336, P＜0001), and differed significantly between any two groups of these patients (all P ＜0.05). Compared with groups Ⅰ and Ⅱ, group Ⅲ had the highest incidence rate of complications, and the incidence rates of hepatic encephalopathy and hepatorenal syndrome showed significant differences across the three groups (χ2=17.718 and 6.277, both P＜0.05). Group Ⅲ had a significantly shorter survival time than groups Ⅰ and Ⅱ (both P＜0.05). ConclusionIn patients with decompensated liver cirrhosis, the severity and incidence rate of hyponatremia increase significantly as liver injury becomes more severe, which suggests that hyponatremia can be used as a prognostic indicator in patients with decompensated liver cirrhosis.