ABSTRACT
The influence of extracellular polymeric substances (EPS) on the interaction between uranium [U(VI)] and Shewanella putrefaciens (S. putrefaciens), especially the U(VI) biomineralization process occurring on whole cells and cell components of S. putrefaciens was investigated in this study. The removal efficiency of U(VI) by S. putrefaciens was decreased by 22% after extraction of EPS. Proteins were identified as the main components of EPS by EEM analysis and were determined to play a major role in the biosorption of uranium. SEM-EDS results showed that U(VI) was distributed around the whole cell as 500-nanometer schistose structures, which consisted primarily of U and P. However, similar uranium lamellar crystal were wrapped only on the surface of EPS-free S. putrefaciens cells. FTIR and XPS analysis indicated that phosphorus- and nitrogen-containing groups played important roles in complexing U (VI). XRD and U LIII-edge EXAFS analyses demonstrated that the schistose structure consisted of hydrogen uranyl phosphate [H2(UO2)2(PO4)2â¢8H2O]. Our study provides new insight into the mechanisms of induced uranium crystallization by EPS and cell wall membranes of living bacterial cells under aerobic conditions.
Subject(s)
Shewanella putrefaciens , Uranium , Biomineralization , Extracellular Polymeric Substance Matrix/metabolism , Phosphorus , Shewanella putrefaciens/metabolism , Uranium/metabolismABSTRACT
AIM:To evaluate the possibility of using cultured human hepatocytes as a bridge between bioartificial liver and liver transplantation.METHODS:In this experiment,the efficacy of extracorporeal bioartificial liver support system (EBLSS) consisting of spheriodal human liver cells and cultured hepatocytes supernatant was assessed in vivo using galactosamine induced rabbit model of fulminant hepatic failure.RESULTS:There was no difference of survival between the two groups of rabbits, but in the supported rabbits serum alanine aminotransferase, total bilirubin and creatinine were significantly lower and hepatocyte necrosis was markedly milder than those in control animals. In addition, a good viability of human liver cells was noted after the experiment.CONCLUSION:EBLSS plays a biologic role in maintaining and compensating the function of the liver.
ABSTRACT
AIM:To establish an extracorporeal bioartificial liver support system (EBLSS) using cultured human liver cells and to study its support effect for fulminant hepatic failure (FHF).METHODS:The liver support experiment of EBLSS consisting of aggregates cultured human liver cells, hollow fiber bioreactor, and circulation unit was carried out in dizhepatic dogs.RESULTS:The viability of isolated hepatocytes and nonparenchymal liver cells reached 96%. These cells were successfully cultured as multicellular spheroids with synthetic technique. The typical morphological appearance was retained up to the end of the artificial liver experiment. Compared with the control dogs treated with EBLSS without liver cells, the survival time of artificial liver support dogs was significantly prolonged. The changes of blood pressure, heart rate and ECG were slow. Both serum ammonia and lactate levels were significantly lowered at the 3rd h and 5th h. In addition, a good viability of human liver cells was noted after 5h experiment.CONCLUSION:EBLSS playing a metabolic role of cultured human hepatocytes,is capable of compensating the function of the liver, and could provide effective artificial liver support and therapy for patients with FHF.
