Core promoter mutation of nucleotides A1762T and G1764A of hepatitis B virus increases core promoter transactivation by hepatocyte nuclear factor 1.

Hepatitis B virus (HBV) infection highly increases the risk for liver cirrhosis and hepatocellular carcinoma (HCC). The clinical manifestation of HBV infection is determined by the mutual interplay of the viral genotype, host genetic factors, mode of transmission, adaptive mutations, and environmental factors. Core promoter activation plays a critical role in the pre-genomic RNA transcription of HBV for HBV replication. The mutations of core promoter have been implicated in HCC development. We had obtained HBV genes from Myanmar HBV infectants and identified gene variations at the core promoter region. For measuring the relative transactivation activity on core promoter, we prepared the core-promoter reporter construct. Both of A1762T and G1764A mutation were consistently found in the HBV genes with hepatocellular carcinoma. The A1762T/G1764A mutation was corresponding to K130M/V131I of HBx protein. We prepared the core promoter-luciferase reporter construct containing the double A1762T/G1764A mutation and the K130M/V131I HBx protein expression construct. The A1762T/G1764A mutation highly was responsive to core promoter transactivation by HBx, regardless of HBx mutation. The A1762T/G1764A mutation newly created hepatocyte nuclear factor 1 (HNF1) responsive element. Ectopic expression of HNF1 largely increased the HBV core promoter containing A1762T/G1764A mutation. In addition, hepatic rich fatty acid, palmitic acid and oleic acid, increased K130M/V131I HBx level by core promoter activation. These results provide biological properties and clinical significance of specific HBV core promoter mutants related with HCC development.

A single amino acid variation of NV protein of viral hemorrhagic septicemia virus increases protein stability and decreases immune gene expression.

Viral hemorrhagic septicemia virus (VHSV) causes severe mortality among more than 90 fish species. The 11 kb viral genome encodes six proteins including nonvirion protein (NV). In previous study, we reported that NV gene variations of VHSV decrease cellular energy metabolism. Among several NV mutant proteins, NV-S56L showed the highest cellular energy deprivation. Based on this finding, we further examined a molecular mechanism of one amino acid (S56L) change on differential cellular dysregulation. In the fish cells, the NV-S56L protein showed an increased level of cellular expression than normal and other mutant NV proteins without change of mRNA expression. Using cycloheximide treatment for exclude de novo NV protein expression, NV-S56L had an extensive half-life of intracellular protein. The proteasome inhibitor, MG-132, treatment recovered the all NV protein levels. The ubiquitination of NV was increased in the treatment of MG132 via inhibition of the ubiquitin/proteasome system process. Finally, increased protein stability of NV-S56L led to downregulation of NF-κB response immune gene expression. These results indicate that the prolonged protein stabilization of NV protein variant (NV-S56L) increases its pathological duration and might eventually lead to high virulence activity in the host fish cell.

Effects of inspired oxygen fraction in discriminating venous from arterial blood in percutaneous central venous catheterization under general anesthesia.

BACKGROUND: A low fraction of inspired oxygen (FiO(2)) increases venous deoxygenated hemoglobin concentrations, making the color of the blood darker. The present study was aimed to determine the effects of FiO(2) on the ability to discriminate venous from arterial blood. METHODS: One-hundred and sixty surgical patients undergoing percutaneous central venous access of the internal jugular vein were randomly assigned to receive an FiO(2) of 0.2, 0.4, 0.6, or 1.0 (n = 40 each) for at least 20 min prior to central line placement under general anesthesia. Vascular access was achieved with a 22-gauge needle; 2 ml of blood was withdrawn and shown to three physicians including the operator. Each of them was asked to identify the blood as 'arterial', 'venous' or 'not sure'. Simultaneous blood gas analysis of the samples was performed on blood taken from the puncture site and the artery after visual comparison to confirm blood's origin and hemodynamic measurements. RESULTS: Lowering FiO(2) progressively increased venous deoxygenated hemoglobin concentrations (2.24 ± 1.12, 3.30 ± 1.08, 3.66 ± 1.15, and 3.71 ± 1.33 g/dl) in groups having an FiO(2) of 1.0, 0.6, 0.4 and 0.2, respectively (P < 0.001), thereby facilitating the 'venous' blood identification (P < 0.001). Neither heart rate nor mean arterial pressure differed among the groups. None developed hypoxemia (percutaneous hemoglobin oxygen saturation < 90%) in any group during the study period. CONCLUSIONS: A low FiO(2) increases venous deoxygenated hemoglobin levels, thereby facilitating the recognition by clinicians of its venous origin in percutaneous central venous catheterization under general anesthesia.