Keratin 18 phosphorylation as a progression marker of chronic hepatitis B

BACKGROUND: The intermediate filament proteins keratins 18 (K18) and 8 (K8) polymerize to form the cytoskeletal network in the mature hepatocytes. It has been shown that the phosphorylation of K18 at two serine residues, 33 and 52, correlates with the progression of hepatitis C, but little is known of chronic hepatitis B (CHB). In this study, we examined K18 phosphorylation in relation to CHB. RESULTS: Site-specific phosphorylation of K18 was determined in livers of twelve healthy donors, and non-cirrhosis (n = 40) and cirrhosis (n = 21) patients. On average, progressively higher level of Ser52 phosphorylation was observed in non-cirrhotic and cirrhotic livers, while elevated Ser33 phosphorylation was detected in both livers but no significant difference. Progressive increase of Ser33 and Ser52 phosphorylation correlated with the elevation of both histological lesions and enzymatic activities of alanine aminotransferase in non-cirrhotic livers. In the hepatocytes of an inactive HBV carrier, strong signals of Ser33 phosphorylation were co-localized with viral infection, while only basal level of Ser52 phosphorylation was detected in infected cells. CONCLUSION: Assuming all obtained data, our data suggest that K18 phosphorylation is a progression marker for CHB

Investigation on Dynamic Characteristics of Spur Gear Transmission System with Crack Fault

To study the dynamic characteristics of spur gears with crack faults, it is essential to establish the meshing stiffness model accurately. In this paper, the time-varying meshing stiffness (TVMS) model and load-sharing ratio (LSR) model of spur gears were established by the potential energy method, and the correctness of the TVMS model was verified by KISSsoft. The influence of gear crack depth and crack angle on TVMS and LSR was analyzed by introducing gear crack into the TVMS model. The multi-degree of freedom dynamics model of spur gears with centralized parameters was established. The time-domain characteristics of vibration of different crack fault systems were discussed, and statistical indicators were introduced to quantitatively evaluate the gear crack faults. The results show that TVMS decreases due to crack propagation, and the vibration impact increases with crack propagation. The sensitivity of crack depth propagation to gear fault characteristics is higher than that of crack angles; the statistical indicators can be used to monitor the propagation of early crack faults. The research results can provide a reference for the research of gearbox dynamic characteristics and fault diagnosis

Enzymatic Hydrolysis and Succinic Acid Fermentation from Steam-Exploded Corn Stalk at High Solid Concentration by Recombinant Escherichia coli

Steam-exploded corn stalk biomass was used as the substrate for succinic acid production via lignocellulose enzymatic hydrolysis and fermentation. Succinic acid fermentation was investigated in Escherichia coli strains overexpressing cyanobacterium Anabaena sp. 7120 ecaA gene encoding carbonic anhydrase (CA). For the washed steam-exploded corn stalk at 30 % substrate concentration, i.e., 30 % water-insoluble solids (WIS), enzymatic hydrolysis yielded 97.5 g/l glucose solution and a cellulose conversion of 73.6 %, thus a high succinic acid level up to 38.6 g/l. With the unwashed steam-exploded corn stalk, though a cellulose conversion of 71.2 % was obtained in hydrolysis at 30 % solid concentration (27.9 % WIS), its hydrolysate did not ferment at all, and the hydrolysate of 25 % solid loading containing 3.8 g/l acetic acid and 168.2 mg/l furfural exerted a strong inhibition on succinic acid production