In this paper,calcium alginate gel beads were prepared through a homemade microcapsule preparation system with multi-nozzles under forced high-voltage electrostatic field.The effect of operation parameters on the large-scale preparation of gel beads was analyzed.The results showed that the air pressure of feed was the decisive factor affecting the size and yield of gel beads,and the size distribution was dependent on several factors including the distribution of electric field,pulse potential,air pressure of feed,pulse frequency,pulse width and threshold potential.The gel beads with good sphericity,smooth surface and low dispersivity(CV<20%)can be prepared by adjusting and optimizing above parameters.It is more important that the yield of gel beads by the microcapsule preparation system is 20—40 folds higher than the traditional electrostatic droplet generator,which makes it possible to realize the large-scale preparation of gel beads.
BACKGROUND:Acute liver failure (ALF) remains a dramatic and unpredictable disease with high morbidity and mortality. Early and accurate prognostic assessment of patients with ALF is critically important for optimum clinical pathway. DATA SOURCES:Five English-language medical databases,MEDLINE,ScienceDirect,OVID,Springer Link and Wiley Interscience were searched for articles on 'acute liver failure',' prognosis',and related topics. RESULTS:Multi-variable prognostic models including the King’s College Hospital criteria and the model for end-stage liver disease score have been widely used in determination of the prognosis of ALF,but the results are far from satisfactory. Other prognostic indicators including serum Gc-globulin,arterial blood lactate,serum phosphate,arterial blood ammonia,and serum alpha-fetoprotein are promising but await further assessement. CONCLUSIONS:A reliable prognostic model to be developed in the future should not only have predictive value for poor outcome but also help to predict the survival of patients without a liver transplantation. Further studies are necessary to assess the prognostic accuracy of any new models.
BACKGROUND:The bioartificial liver is anticipated to be a promising alternative choice for patients with liver failure. Toxic substances which accumulate in the patients'plasma exert deleterious effects on hepatocytes in the bioreactor,and potentially reduce the efficacy of bioartificial liver devices. This study was designed to investigate the effects of plasma from patients with acute on chronic liver failure(AoCLF)on immortalized human hepatocytes in terms of cytochrome P450 gene expression,drug metabolism activity and detoxification capability. METHODS:Immortalized human hepatocytes(HepLi-2 cells)were cultured in medium containing fetal calf serum or human plasma from three patients with AoCLF.The cytochrome P450(CYP3A5,CYP2E1,CYP3A4)expression, drug metabolism activity and detoxification capability of HepLi-2 cells were assessed by RT-PCR,lidocaine clearance and ammonia elimination assay. RESULTS:After incubation in medium containing AoCLF plasma for 24 hours,the cytochrome P450 mRNA expression of HepLi-2 cells was not significantly decreased compared with control culture.Ammonia elimination and lidocaine clearance assay showed that the ability of ammonia removal and drug metabolism remained stable. CONCLUSIONS:Immortalized human hepatocytes can be exposed to AoCLF plasma for at least 24 hours with no significant reduction in the function of cytochrome P450. HepLi-2 cells appear to be effective in metabolism and detoxification and can be potentially used in the development of bioartificial liver.
Du, Wei-BoPan, Xiao-PingYu, Xiao-PengYu, Cheng-BoLv, Guo-LiangChen, YuLi, Lan-Juan
Alginate-chitosan-alginate (ACA) microcapsules have been widely studied as devices for the immuno-isolation and transplantation of living cells.However, long-term survival of the micro-encapsulated cell grafts and thus their potential clinical applications are hampered by the pericapsular fibrotic overgrowth induced by adsorbed protein.In this study, the adsorption behavior of plasma fibrinogen (Fgn) onto ACA microcapsules was studied by using the batch technique.The results showed that the equilibrium time for the adsorption was 24 h.The adsorption of Fgn onto ACA microcapsules fitted very well with Freundlich isotherm, which was indicative of multilayer adsorption.The kinetic experimental data correlated well with the second-order kinetic model,indicating that chemical sorption was the rate-limiting step.The effects of pH and ionic strength on the adsorption were also studied to interpret the mechanism of adsorption.It was found that the amount of adsorbed Fgn decreased with increasing pH in the range of 4.9—7.4.At pH 7.4, the amount of adsorbed Fgn increased with increasing NaCl concentration, and then decreased with further increase in NaCl concentration.At pH 6.0, the amount of adsorbed Fgn decreased with increasing NaCl concentration, indicating that electrostatic interaction was one of the main interactions between Fgn and ACA microcapsules and the positively charged chitosans which was not sufficiently neutralized on the surface of microcapsules induced the adsorption.
