Predictors of relapse in chronic hepatitis B after discontinuation of anti-viral therapy

BACKGROUND

Optimal duration of anti-viral therapy in chronic hepatitis B virus (HBV) infection remains unclear.

AIM

To investigate factors that could predict relapse after stopping anti-viral agents.

METHODS

Chronic hepatitis B patients who were treated with anti-viral agents (lamivudine, adefovir, entecavir) and have stopped the treatment were recruited. Anti-viral agents were stopped according to the recommendations of the Asian Pacific Association for the Study of the Liver. Virological relapse was defined as an increase in serum HBV DNA to >1000 copies/mL after discontinuation of treatment.

RESULTS

Eighty-four (69 treatment naïve and 15 lamivudine resistant) patients were eligible for this study. Thirty-seven patients developed virological relapse at 4.3 ± 2.9 (range 1-11) months after discontinuation of therapy. The 1-year cumulative probability of virological relapse was 42% and 47% in HBeAg (hepatitis B e antigen)-positive (n = 41) and HBeAg (hepatitis B e antigen)-negative (n = 43) patients, respectively. On multivariate analysis by Cox proportional hazard model, pre-existing lamivudine resistance, delayed suppression of HBV DNA to undetectable level during anti-viral therapy and to a higher HBsAg (hepatitis B surface antigen) level at the end of treatment were associated with virological relapse. Twelve of the 15 (80%) lamivudine resistant patients developed virological relapse. Among the 11 treatment naïve patients who had HBsAg ≤ 2 log IU/mL at the end of treatment, 1 (9%) of them had virological relapse.

CONCLUSIONS

Treatment cessation among lamivudine resistant patients is associated with high risk of virological relapse. Serum HBsAg level at the end of treatment and rate of HBV DNA suppression can provide supplementary information to guide the timing of stopping anti-viral drugs.

Multilineage differentiation of dental follicle cells and the roles of Runx2 over-expression in enhancing osteoblast/cementoblast-related gene expression in dental follicle cells

OBJECTIVES

Dental follicle cells (DFCs) provide the origin of periodontal tissues, and Runx2 is essential for bone formation and tooth development. In this study, pluripotency of DFCs was evaluated and effects of Runx2 on them were investigated.

MATERIALS AND METHODS

The DFCs were induced to differentiate towards osteoblasts, adipocytes or chondrocytes, and alizarin red staining, oil red O staining or alcian blue staining was performed to reveal the differentiated states. Bone marrow stromal cells (BMSCs) and primary mouse fibroblasts served as controls. DFCs were also infected with recombinant retroviruses encoding either full-length Runx2 or mutant Runx2 without the VWRPY motif. Western blot analysis, real-time real time RT-PCR and in vitro mineralization assay were performed to evaluate the effects of full-length Runx2 or mutant Runx2 on osteogenic/cementogenic differentiation of the cells.

RESULTS

The above-mentioned staining methods demonstrated that DFCs were successfully induced to differentiate towards osteoblasts, adipocytes or chondrocytes respectively, confirming the existence of pluripotent mesenchymal stem cells in dental follicle tissues. However, staining intensity in DFC cultures was weaker than in BMSC cultures. Real-time PCR analysis indicated that mutant Runx2 induced a more pronounced increase in expression levels of OC, OPN, Col I and CP23 than full-length Runx2. Mineralization assay also showed that mutant Runx2 increased mineralization nodule formation more prominently than full-length Runx2.

CONCLUSIONS

Multipotent DFCs can be induced to differentiate towards osteoblasts, adipocytes or chondrocytes in vitro. Runx2 over-expression up-regulated expression levels of osteoblast/cementoblast-related genes and in vitro enhanced osteogenic differentiation of DFCs. In addition, mutant Runx2-induced changes in DFCs were more prominent than those induced by full-length Runx2.

Time change of perceptual reversal of ambiguous figures by rTMS

The aim of this study was to investigate the effect of stimulus frequency and number of pulses during rTMS (repetitive transcranial magnetic stimulation) on the phenomenon of perceptual reversal. Particularly, we focused on the temporal dynamics of perceptual reversal in the right SPL (superior parietal lobule), using the spinning wheel illusion. We measured the IRT (inter-reversal time) of perceptual reversal. To investigate whether stimulus frequency or the number of pulses is critical for the rTMS effect, we applied the following schedules over the right SPL and the right PTL (posterior temporal lobe): 0.25Hz 60 pulses, 0.25Hz 120pulses, 0.5Hz 120 pulses, and 1Hz 120 pulses biphasic rTMS at 90% of the resting motor threshold. As a control, we included a No-TMS condition. The results showed that rTMS with 0.25Hz 60 pulses over the right SPL caused shorter IRT. There were no significant differences between IRTs for rTMS with 0.25Hz 120 pulses, 0.5Hz 120 pulses or 1Hz 120 pulses over the right SPL. Comparing these results with those of a previous study, we found that an rTMS condition with 60 pulses causes shorter IRT; 240 pulses causes longer IRT; and 120 pulses does not change IRT. Therefore, when applying rTMS over the right SPL, the IRT of perceptual reversal is primarily affected by the number of pulses.

Polyurethane as a potential knee hemiarthroplasty biomaterial: An in-vitro simulation of its tribological performance

Hemiarthroplasty is an attractive alternative to total joint replacement for the young active patient, when only one side of the synovial joint is damaged. In the development of a hemiarthroplasty prosthesis, a comprehensive understanding of the tribology of both the natural joint and the hemireplaced joint is necessary. The objectives of this study were to investigate the tribological response of polyurethane (PU) as a potential hemiarthroplasty material. Bovine medial compartmental knees were tested in a Prosim pendulum friction simulator, which applied physiologically relevant loading and motion. The healthy medial compartment was investigated as a negative control; a stainless steel hemiarthroplasty was investigated as a positive control; and three PU hemiarthroplasty plates of different moduli (1.4 MPa, 6.5 MPa, and 22 MPa) were also investigated. Using the lower-modulus PU caused reduced levels of contact stress and friction shear stress, which resulted in reduced levels of opposing cartilage wear. The two PU bearings with the lowest moduli demonstrated a similar tribological performance to the negative control. The higher-modulus PU (22 MPa) did demonstrate higher levels of friction shear stress, and wear resulted on the opposing cartilage, although not as severe as the wear from the stainless steel group. This study supports the use of compliant PU designs in future tribological experiments and hemiarthroplasty design applications.