[Disruption of the microfilament cytoskeleton induced by simulated microgravity affects NO/NOS system of osteoblasts].

OBJECTIVE: To study the effect of microfilament cytoskeleton changes induced by simulated microgravity on the NO/NOS system of osteoblasts, and explore the mechanism of weightlessness leading to osteoporosis. METHODS: Mouse osteoblast-like cell line MC3T3-E1 were divided into simulated microgravity (by rotating clinostat) group, 0.5 microg/ml cytochalasins B group, simulated microgravity+cytochalasins B group, and normal gravity group. After cell culture for 48 h with corresponding treatments, immunofluorescence staining of the cells by FITC-phallacidin was performed to observe the changes of microfilament under laser confocal microscope. NOS activity of the cells was tested with NOS detection kit, and the NO concentration in the cell supernatant was measured with nitrate reductase method. RESULTS: Depolymerization of the microfilament cytoskeleton with irregular arrangement and reduced tension fibers occurred in the cells except for those in the normal gravity group, which was especially obvious in the microgravity+cytochalasins B group. Compared with the normal gravity group, the cells in the other groups showed increased iNOS activity and NO concentration but decreased eNOS activity, especially obvious in simulated microgravity+ cytochalasins B group. CONCLUSION: Disruption of the microfilament cytoskeleton induced by simulated microgravity can regulate the NO/NOS system to influence the signal transduction of the osteoblasts.

[Microgravity culture of hepatocytes on cellulose/gelatin macroporous microcarrier].

OBJECTIVE: To compare macroporous microcarrier Cytopore 2 and Cultispher S for their effects in microgravity culture of CL-1 cells. METHODS: CL-1 cells were cultured on Cytopore 2 and Cultispher S respectively in a rotational cell culture system (RCCS) in a volume of 50 ml. Dynamic morphological observation and cell counting and functional test were carried out during the cell culture. RESULTS: The cells were capable of adhering to and proliferating on both of the microcarriers, reaching the growth peak on day 9 of cell culture with the maximum cell density of 4x10(6)/ml on cultispher S. Albumin was significantly higher in the supernatant of Cytopore 2 than in that of Cultispher S on days 10, 11, and 12 (P<0.05), and the urea level in the supernatant of cytopore 2 was also significantly higher on days 10 and 11 (P<0.05). CONCLUSION: The cells cultured on Cytopore 2, though with a smaller cell number, display better functions than those cultured on Cultispher S under RCCS conditions.

[Artificial and bioartificial liver support systems for acute and acute-on-chronic liver failure: a meta-analysis].

OBJECTIVE: To evaluate the effect of artificial and bioartificial liver support systems for management of acute and acute-on-chronic liver failure. METHODS: Articles documenting randomized clinical trials concerning any liver support systems vs standard conservative therapy, published between January, 1970 and June, 2008, were retrieved by database searching. Of the 1134 articles retrieved, 12 randomized trials involving 479 patients were included. The data were extracted and the trial quality was assessed by 2 independent reviewers. The primary outcome measure was all-cause mortality, and the results were combined on the risk ratio (RR) scale. RESULTS: Of the 12 trials included, 10 assessed artificial liver support systems for acute or acute-on-chronic liver failure, and 2 assessed bioartificial systems for acute liver failure. Overall, the liver support systems had moderate effect on mortality compared with standard conservative therapy (RR=0.80; 95% CI 0.664-0.969, P=0.022). Meta-regression indicated that the effect of the support systems depended on the type of liver failure (P=0.00). In stratified meta-analyses, the support systems appeared to reduce the mortality by 43% in acute-on-chronic liver failure (RR=0.57; 95% CI 0.39-0.84, P=0.004), but not in acute liver failure (RR=0.899; 95% CI 0.72-1.12, P=0.361). CONCLUSION: Artificial liver support systems reduce the mortality of acute-on-chronic liver failure as compared with standard conservative therapy, but have no significant effect on the mortality of acute liver failure. Bioartificial liver support systems lower the mortality rates in both acute and acute-on-chronic liver failure, and should be the future focus of development.