Non-invasive determination of hepatic steatosis by acoustic structure quantification from ultrasound echo amplitude

AIM:To use leptin-deficient(ob/ob) mice with demonstrated differences in steatosis levels to test a new diagnostic method using the acoustical structure quantification(ASQ) mode and the associated analytical parameter,"focal disturbance ratio"(FD-ratio).METHODS:Nine ob/ob mice,at 5,8,and 12 wk of age(n = 3 in each age group),were used as models for hepatic steatosis.Echo signals obtained from ultrasonography in the mice were analyzed by ASQ,which uses a statistical analysis of echo amplitude to estimate inhomogeneity in the diagnostic region.FD-ratio,as calculated from this analysis,was the focus of the present study.FD-ratio and fat droplet areas and sizes were compared between age groups.RESULTS:No fibrosis or inflammation was observed in any of the groups.The fat droplet area significantly(P < 0.01) increased with age from 1.25% ± 0.28% at 5 wk to 31.07% ± 0.48% at 8 wk to 51.69% ± 3.19% at 12 wk.The median fat droplet size also significantly(P < 0.01) increased with age,from 1.33(0.55-10.52) m at 5 wk,2.82(0.61-44.13) m at 8 wk and 6.34(0.66-81.83) m at 12 wk.The mean FD-ratio was 0.42 ± 0.11 at 5 wk,0.11 ± 0.05 at 8 wk,and 0.03 ± 0.02 at 12 wk.The FD-ratio was significantly lower at 12 wk than at 5 wk and 8 wk(P < 0.01).A significant negative correlation was observed between the FD-ratio and either the fat droplet area(r =-0.7211,P = 0.0017) or fat droplet size(r =-0.9811,P = 0.0052).CONCLUSION:This tool for statistical analysis of signals from ultrasonography using the FD-ratio can be used to accurately quantify fat in vivo in an animal model of hepatic steatosis,and may serve as a quantitative biomarker of hepatic steatosis.

STRUCTURE IN THE PRECORE REGION OF HEPATITIS B CORE GENE AFFECTING ITS EXPRESSION IN E.coil

Restriction fragments of HBV-DNA, cleaved by endonuclease HhaI,containing HBcAg gene were trimmed by BAL-31 exonuclease to remove different lengths of the precore sequence.They were inserted into plasmid pUR222 at EcoRI site through synthetic linker ligation. Transformants in E.coli BMH7118 showing different levels of HBcAg gene expression were screened and analyzed for their nucleotide sequences in the junction region both by Maxam and Gilbert's chemical degradation method and by M13 chain termination method. Results of sequence analysis of different transformants revealed a partial palindromic (loop and stem) structure, at -7 to -35 nucleotide with regard to ATG of the HBcAg gene as position +1, which has dramatic effect on the level of expression of the inserted gene using the same promoter,SD sequence and identical N-terminus.The amount of HBcAg synthesized differed from 9% in the high expressing plasmid to less than 0.01% of the total cell proteins in the low expressing transformants.The findings were compared to results obtained by other workers in studies of HBcAg expression in procaryotes and their significance in the expression of eucaryotic genes in procaryotic cells were discussed.