The role of mutations in core protein of hepatitis B virus in liver fibrosis

The core protein of hepatitis B virus encompasses B- and T-cell immunodominant epitopes and subdivided into two domains: the N-terminal and the functional C-terminal consisted phosphorylation sites. Mutations of the core gene may change the conformation of the core protein or cause alteration of important epitopes in the host immune response. In this study twenty nine men (mean age 40 ± 9 years old) with chronic hepatitis B were recruited for direct sequencing of the core gene. Serum ALT and HBV DNA level were measured at the time of liver biopsy. The effects of core protein mutations on patients' characteristics and subsequently mutations in B cell, T helper and cytotoxic T lymphocyte (CTL) epitopes and also C-terminal domain of core protein on the activity of liver disease was evaluated. Liver fibrosis was significantly increased in patients with core protein mutation (1.0 ± 0.8 vs 1.9 ± 1.4 for mean stage of fibrosis P = 0.05). Mutations in CTL epitopes and in phosphorylation sites of C-terminal domain of core protein also were associated with higher liver fibrosis (P = 0.003 and P = 0.04; Fisher's exact test for both). Patients with mutation in C-terminal domain had higher serum ALT (62 ± 17 vs 36 ± 12 IU/l, p = 0.02). Patients with mutations in B cell and T helper epitopes did not show significant difference in the clinical features. Our data suggests that core protein mutations in CTL epitopes and C-terminal domain accompanied with higher stage of liver fibrosis may be due to alterations in the function of core protein

Effects of left prefrontal transcranial direct current stimulation on the acquisition of contextual and cued fear memory

Objective(s): Behavioral and neuroimaging studies have shown that transcranial direct current stimulation, as a non-invasive neuromodulatory technique, beyond regional effects can modify functionally interconnected remote cortical and subcortical areas. In this study, we hypothesized that the induced changes in cortical excitability following the application of cathodal or anodal tDCS over the left frontal cortex as pre-training would affect functional connectivity in resting-state circuits of fear memory and consequently could improve or disturb the acquisition of fear memory. Materials and Methods: In order to evaluate the polarity-dependent effects of tDCS on the acquisition of fear memory and the functional connectivity, we applied left prefrontal anodal or cathodal stimulation at 200 μA for one session to healthy mice for the durations of 20 and 30 min prior to fear conditioning. Results: Our results revealed that the administration of left prefrontal anodal (for both 20 and 30 min durations) and cathodal (at 30 min duration) tDCS impaired the acquisition of both contextual and cued fear memory. In addition, we did not observe a direct correlation between stimulation duration and the efficacy of tDCS on the acquisition of contextual and cued fear memory. Conclusion: In this study, the impairments of both contextual and cued memory further confirmed the previous studies reporting that the administration of transcranial stimulation would affect the activity of deeper structures like amygdala and hippocampus as the main components of the fear memory circuit in acquisition, storage, and expression of the memory