Effect of mutating the two cysteines required for HBe antigenicity on hepatitis B virus DNA replication and virion secretion

Hepatitis B virus (HBV) variants with impaired expression of e antigen (HBeAg) frequently arise at the chronic stage of infection, as exemplified by precore and core promoter mutants. Since an intramolecular disulfide bond maintains the secondary structure of HBeAg, we explored effect of missense mutations of either cysteine codon. Consistent with earlier reports, substitution of each cysteine rendered HBeAg nearly undetectable. With underlying nucleotide changes at the loop of pregenome encapsidation signal, the C-7 mutants were severely impaired in pregenomic RNA packaging and hence DNA replication. Although none of the missense mutations at C61 reduced DNA replication, replacement with arginine, but not alanine, aspartic acid, phenylalanine, or serine, blocked virion secretion. Consistent with the detection of C61R genome from a patient serum, secretion block of the C61R mutant could be overcome by co-expression of wild-type core protein. In conclusion, point mutations of the C61 codon may generate viable HBeAg-negative variants.     

Co-expression of Y box-binding protein-1 and P-glycoprotein as a prognostic marker for survival in epithelial ovarian cancer

OBJECTIVES: This study aimed to observe the expressions of Y box-binding protein-1 (YB-1) and P-glycoprotein (P-gp) in primary ovarian tumor and to determine whether they act as biomarkers for survival in epithelial ovarian cancer. METHODS: The expressions of YB-1 and P-gp were examined immunohistochemically in 59 patients who were treated from 1997 to 2000 at Kurume University Hospital. Samples were paraffin-embedded primary ovarian cancer tissue taken from the surgical specimens. RESULTS: Of the 59 primary ovarian tumors examined, 32 (54.2%) and 18 (30.5%) were positive for YB-1 and P-gp, respectively. Co-expression of these two proteins was observed in 20.3% (12/59) cases. Patients showing this co-expression had a worse 3-year survival than those without co-expression (40.0% vs. 73.1%, P = 0.0447). This co-expression significantly correlated with poor prognosis according to multivariate analysis (P = 0.0007). CONCLUSION: Co-expression of YB-1 and P-gp emerged as a promising relevant biomarker for unfavorable prognosis in ovarian cancer.     

The R(-)-enantiomer of efonidipine blocks T-type but not L-type calcium current in guinea pig ventricular myocardium

In guinea pig ventricular cardiomyocytes, the R(-)-enantiomer of efonidipine concentration-dependently blocked T-type Ca2+ current with 85% inhibition at 1 microM. In contrast, R(-)-efonidipine (1 microM) had no effect on the L-type Ca2+ current and Ca2+ transient in cardiomyocytes and contractile force in papillary muscles. Thus, R(-)-efonidipine is a highly selective blocker of the T-type Ca2+ current in native myocardia.     

Effect of cilnidipine on L- and T-type calcium currents in guinea pig ventricle and action potential in rabbit sinoatrial node

Cilnidipine, a dihydropyridine Ca(2+) channel antagonist, is known to have inhibitory effects on both L- and N-type Ca(2+) currents. In the present study, we examined the effect of cilnidipine on myocardial L- and T-type Ca(2+) currents and sinoatrial node action potential configuration. In voltage clamped guinea pig ventricular myocytes, cilnidipine concentration-dependently decreased L- and T-type Ca(2+) currents. In rabbit sinoatrial node tissue, cilnidipine increased cycle length through reduction of phase 4 depolarization slope. In conclusion, cilnidipine has inhibitory effects on T-type Ca(2+) current, which may contribute to its negative chronotropic potency.     

Gender difference in QTc prolongation of people with mental disorders

Background

We examined gender difference in QTc interval distribution and its related factors in people with mental disorders.

Methods

We retrospectively reviewed medical charts of patients discharged from a university psychiatric unit between November 1997 and December 2000. Subjects were 328 patients (145 males and 183 females) taking psychotropics at their admission. We examined patient characteristics, medical history, diagnosis, and medication before admission.

Results

Mean QTc interval was 0.408 (SD = 0.036). QTc intervals in females were significantly longer than those in males. QTc of females without comorbidity was significantly longer than that of males.

Conclusion

The influence of gender difference on QTc prolongation in people with mental disorders merits further research.

     

Inhibitory effects of mulberry leaf extract on postprandial hyperglycemia in normal rats

We examined the inhibitory effects of aqueous ethanol extract from mulberry leaves (ME) on postprandial hyperglycemia in normal Wistar rats. ME dose-dependently suppressed the postprandial rise of blood glucose in rats, when ME (0.02-0.5 g/kg) was given 0.5 h before the administration of carbohydrates such as sucrose, maltose and starch. The ME dose showing 50% inhibition of the increment of blood glucose (ED50) was 0.11 g/kg for sucrose, 0.44 g/kg for maltose, and 0.38 g/kg for starch. ME and its basic fraction (MB) containing 1-deoxynojirimycin were assayed for their inhibitory effects (IC50) on disaccharidase derived from the small intestine of rats. The IC50 value of ME was 3.2 microg/mL for sucrase, 10 microg/mL for isomaltase, and 51 microg/mL for maltase. The IC50 value of MB was 0.36 microg/mL for sucrase, 1.1 microg/mL for isomaltase, and 6.2 microg/mL for maltase. The IC50 value of 1-deoxynojirimycin as the principle component in ME was 0.015 microg/mL for sucrase and 0.21 microg/mL for maltase, and this value was comparable to the IC50 of voglibose. The inhibitory activity of ME in a-amylase was weak. These results suggest that ME strongly suppresses postprandial hyperglycemia after carbohydrate loading by inhibiting the activity of disaccharidases in the small intestine of rats.     

The effects of dietary vitamin B12 deficiency on sperm maturation in developing and growing male rats

ABSTRACT  To evaluate the role of vitamin B₁₂ on spermatogenesis, the effects of dietary vitamin B₁₂ deficiency on sperm maturation in developing rat fetuses and young growing rats were examined. The vitamin B₁₂-defi-cient diet was given to all the animals for three different periods: whole period (gestation to mature), gestation period (gestation to weaning), or immature period (3–12 weeks postnatal). Sperm examination revealed that the sperm count was markedly lower in male progeny (F1) that were vitamin B₁₂-deficient during the whole period. In addition, a significantly higher number of abnormal sperm, such as tailless and amorphous sperm, was observed. In male rats that were vitamin B₁₂-deficient during the immature period, the incidence of abnormal sperms was 14.4% and 4.8% for tailless and short tail, respectively. The motion rates, such as path velocity and straight line velocity, were decreased to 20–40% of the control value in rats that were vitamin B₁₂-deficient both during the whole and gestation periods. However, no effects of vitamin B₁₂ deficiency on sperm motility were observed during the immature and mature periods. From these findings, we suggest that dietary vitamin B₁₂ deficiency during pregnancy may induce irreversible damage in the germ cells of embryos and affect the maturation of spermatozoa.