Expression of RNase H of human hepatitis B virus polymerase in Escherichia coli

Development of a model of benign esophageal stricture in rats: the optimal concentration of sodium hydroxide for stricture formation

PURPOSE

To investigate the optimal concentration of sodium hydroxide (NaOH) on esophageal stricture formation in rats to establish an animal model of benign esophageal stricture (BES).

METHODS

Corrosive esophageal burn was produced by internal application of different concentrations of NaOH to the distal esophagus in rats. As much as 66 male rats were randomly divided into eight groups: Group A (control, n = 6), Group B (sham-operated group, n = 6), Group C (5% NaOH, n = 8), Group D (10% NaOH, n = 8), Group E (20% NaOH, n = 8), Group F (30% NaOH, n = 10), Group G (40% NaOH, n = 14), and Group H (50% NaOH, n = 6). Surviving rats were killed at 28 days. The survival rate, body weight gain, symptoms, and histopathological changes were assessed.

RESULTS

The mortality rate was high in Groups G and H (73 and 67%). The prevalence of symptoms of BES was 43% in Groups D and E, 50% in Group F, 75% in Group G, and 100% in Group H. Statistically significant stricture formation of the esophagus was observed in Groups F and G. The degree of tissue damage was significantly higher in Groups E, F, and G.

CONCLUSION

A high concentration of NaOH of 30% was required to establish a survivable BES model in rats.

Hydroxyethyl starch 130/0.4 attenuates early hepatic damage in ischemia/reperfusion injury

PURPOSE

Ischemia/reperfusion injury (IRI) remains a clinical challenge. We tested the hypothesis that fluid therapy using hydroxyethyl starch (HES) 130/0.4 during the early phase of IRI in rat liver decreases markers of hepatic injury.

METHODS

We induced liver IRI in three groups of rats anesthetized with ketamine and chlorpromazine by means of 60 min of segmental hepatic ischemia followed by 120 min of reperfusion. At the onset of reperfusion, Group 1 (IRI + HES; n = 12) was given 13 mL.kg(-1) of HES; Group 2 (IRI + HS; n = 12) received the same volume of 7.5% saline (HS), and Group 3 (IRI-only; n = 12) received no fluid. Three other groups of 12 animals each were sham-operated and received the same fluid as the test groups. We euthanized the animals after three hours, drew blood for alanine aminotransferase (ALT) quantification, and took ischemic liver samples for histomorphological study.

RESULTS

Serum ALT activity was greater in all of the IRI groups than in the sham-operated animals. The ALT activity was 1,081 +/- 575 IU.L(-1) in IRI + HES Group 1; 2,363 +/- 1,839 IU.L(-1) in IRI + HS Group 2; and 2,866 +/- 2,491 IU.L(-1) in IRI-only Group 3. There was a statistically significant difference between the IRI + HES and the IRI-only groups (P = 0.001), but not between the IRI + HS and the IRI-only groups (P > 0.05). Likewise, histological scores were greater in all IRI groups compared with the sham-operated animals. Scores were higher in the IRI-only group (median 3.5) than in the groups receiving fluid (IRI + HES median 2; IRI + HS median 3). The difference between IRI + HES and IRI-only was statistically significant (P = 0.008) but not so between IRI + HS and IRI-only (P > 0.05).

CONCLUSIONS

Giving HES 130/0.4 attenuates rat liver IRI compared with no fluid, while giving HS does not. This suggests a role for HES in hepatoprotection associated with liver IRI.

KRAS mutation and microsatellite instability: two genetic markers of early tumor development that influence the prognosis of colorectal cancer

INTRODUCTION

We examined two genetic markers established early in colorectal tumor development, microsatellite instability (MSI) and mutation of the KRAS proto-oncogene, to see if these genetic changes influence metastatic disease progression and survival.

PATIENTS AND METHODS

MSI and KRAS mutation status were assessed in 532 primary adenocarcinomas (stage I-IV) from patients treated by colon resection. Median follow-up was 4.1 years (range 0-13.3 years) overall, 5.4 years for survivors.

RESULTS

MSI and KRAS mutation were detected in 12 and 36% of cases, respectively. MSI was more common in early-stage disease (I, 15%; II, 21%; III, 10%; IV, 2%; P = 0.0001). Prevalence of KRAS mutation did not vary with stage (I, 36%; II, 34%; III, 35%; IV, 40%; P = ns). Disease-specific survival was far superior for MSI tumors than for microsatellite stability (MSS) tumors (5-year survival 92 vs. 59%, P < 0.0001). KRAS mutation was a marker of poor survival (5-year survival 55 vs. 68%, P = 0.0002). Using Cox regression analysis MSI, KRAS mutation, and stage were strong independent predictors of survival in the entire patient population. A high-mortality group with MSS/KRAS-mutant tumors was identified within the stage I and II cohort.

CONCLUSIONS

MSI and KRAS mutation provide fundamental genetic signatures influencing tumor behavior across patient subsets and stages of tumor development.

Rebuilding microbial genomes

Engineered microbes are of great potential utility in biotechnology and basic research. In principle, a cell can be built from scratch by assembling small molecule sets with auto-catalytic properties. Alternatively, DNA can be isolated or directly synthesized and molded into a synthetic genome using existing genomic blueprints and molecular biology tools. Activating such a synthetic genome will yield a synthetic cell. Here we examine obstacles associated with this latter approach using a model system whereby a donor genome from H. influenzae is fragmented, and the pieces are then modified and reassembled stepwise in an E. coli host cell. There are obstacles associated with this strategy related to DNA transfer, DNA replication, cross-talk in gene regulation and compatibility of gene products between donor and host. Encouragingly, analysis of gene expression indicates widespread transcription of H. influenzae genes in E. coli, and analysis of gap locations in H. influenzae and other microbial genome assemblies reveals few genes routinely incompatible with E. coli. In conclusion, rebuilding and booting a genome remains a feasible and pragmatic approach to creating a synthetic microbial cell.

Construction of hepatitis B virus X gene expression vector in eucaryotic cells and its transfection in HL-7702 cells

AIM: To establish a human hepatocyte cell line which can express hepatitis B virus (HBV) X gene.

METHODS: HBV X gene was obtained through PCR techn-ology. After A-tailing added, X gene was connected into vector PUCmT. Vector PUCmT-X and PcDNA3 were digested with EcoRI and HindIII. The fragments of X and PcDNA3 were connected to establish reconstituted plasmid PcDNA3-X. Then PcDNA3-X and PcDNA3 were transfected into HL-7702 cells by lipid-mediated transfection. After selected with G418, HL-7702/HBx cells were analysed by the reverse transcription-PCR to confirm the steady expression of X gene in HL-7702.

RESULTS: Reconstituted plasmid PcDNA3-X included the anticipated fragment of HBV X gene was proved by auto-sequencing assay. RT-PCR analysis showed that reconstituted plasmid PcDNA3-X could express the X protein efficiently in HL-7702 cells.

CONCLUSION: Hepatocyte can express HBV X gene, which is an ideal model to study the effect of HBV X gene on the development of hepatitis and hepatocelular carcinoma.

Effect of HBeAg on the hepatitis B virus vertical transmission in neonates

AIM: To investigate the effect of HBeAg on the hepatitis B virus vertical transmission in neonates.

METHODS: HBsAg positive pregnant women were enrolled,and ELISA or Abbott was employed to detect the HBeAg and HBsAg in the peripheral blood of neonates and their mothers.

RESULTS: Fifty-seven HBsAg positive pregnant women were reconfirmed as HBsAg positive. Fifteen of them were detected as HBeAg positive. Eleven of 16 neonates born to 15 HBeAg positive mother were detected as HBeAg positive. Three neonates diagnosed as HBsAg positive by ELISA or Abbott reagents were detected as HBeAg positive. Statistic analysis indicated that HBeAg in newborns was an important risk factor.

CONCLUSION: HBeAg in neonates played an important role during HBV vertical transmission.