Destabilizing effect of glycyrrhetinic acid on pre-formed biofilms of Streptococcus mutans / 대한구강보건학회지

OBJECTIVES: In this study, the destabilizing effect of glycyrrhetinic acid on pre-formed biofilms of Streptococcus mutans (S. mutans) was observed. METHODS: Alamar blue assay was used to determine the toxicity of glycyrrhetinic acid on pre-formed biofilms of S. mutans. Four different concentrations (0, 3.75, 7.5, 15 µg/ml) of glycyrrhetinic acid were tested. Changes in the biofilm architecture after exposure to glycyrrhetinic acid were analyzed by scanning electron microscopy (SEM). Moreover, the role of glycyrrhetinic acid in enhancing the antimicrobial activity of cetylpyridinium chloride (CPC), an antimicrobial agent commonly used in oral health care products, was evaluated. RESULTS: Glycyrrhetinic acid concentration of up to 15 µg/ml had little cytotoxic effect but significantly changed the biofilm architecture. SEM analysis revealed destabilized biofilm structure after the preformed biofilms were exposed to glycyrrhetinic acid. Supplementing 2.5 µg/ml CPC with 15 µg/ml glycyrrhetinic acid significantly enhanced the bactericidal effect of CPC on the pre-formed biofilms than that in the non-supplemented CPC treated control. This indicates that glycyrrhetinic acid enhanced the antimicrobial activity of CPC by modifying the structure, thus facilitating the penetration of CPC into the biofilm. CONCLUSIONS: Glycyrrhetinic acid could be a potential agent to effectively control S. mutans biofilms responsible for dental caries.

Durability after discontinuation of nucleos(t)ide therapy in chronic HBeAg negative hepatitis patients

BACKGROUND/AIMS: Relapse has been reported after stopping nucleos(t)ide (NUC) therapy in the majority of chronic HBeAg negative hepatitis patients. However, the ideal treatment duration of HBeAg negative chronic hepatitis B (CHB) is not well known. We investigated the frequency of relapse in HBeAg negative CHB patients receiving NUC therapy. METHODS: The NUC therapy was discontinued at least 3 times undetectable level of HBV DNA leave 6 months space in 45 patients. Clinical relapse was defined as HBV DNA >2,000 IU/mL and alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >2 times of upper limit of normal range. Virological relapse was defined as HBV DNA >2,000 IU/mL. RESULTS: Clinical relapse developed in 16 (35.6%) and 24 (53.3%) patients after stopping therapy at 6 months and 12 months off therapy, respectively. Virological relapse developed 22 (48.9%) and 33 (73.3%) patients at 6 months and 12 months off therapy. The factors such as age, gender, cirrhosis, baseline AST, ALT, HBV DNA levels, treatment duration, and consolidation duration were analyzed to investigate the predictive factors associated with 1 year sustained response. Of these factors, cirrhosis (86.1% in CHB, 22.2% in LC) was significantly associated with 1 year virological relapse rate. Baseline HBV DNA and total treatment duration tended to be associated with virological relapse. CONCLUSIONS: Virological relapse developed in the majority (73.3%) of HBeAg negative CHB patients and clinical relapse developed in the half (53.3%) of patients at 1 year off therapy. Cirrhosis may be associated with the low rate of virological relapse.

Clinical efficacy of entecavir therapy and factors associated with treatment response in naive chronic hepatitis B patients / 대한간학회지

BACKGROUND/AIMS: Entecavir is a potent and selective guanosine analogue that has demonstrated a significant antiviral efficacy against hepatitis B virus (HBV). The aim of this study was to characterize the response to entecavir and to examine the factors affecting that response. METHODS: We administered 0.5 mg of entecavir once daily for more than 12 months to 114 naive chronic hepatitis B (CHB) patients. We measured the levels of liver enzymes, serological markers, and serum HBV DNA at 3-month interval. RESULTS: Normalization of serum alanine aminotransferase levels was observed in 68.5% (76/114), 74.6% (85/114), and 81.6% (62/76) of patients after 6, 12, and 24 months of therapy, respectively. HBV DNA levels of <50 copies/mL (as evaluated by polymerase chain reaction) were observed in 43.9% (50/114), 71.1% (81/114), and 85.5% (65/76) of patients after 6, 12, and 24 months, respectively. Viral breakthrough was not observed. The rates of HBeAg loss and seroconversion were 43.5% (27/62) and 14.5% (9/62), respectively, after 12 months of therapy, and 56.4% (22/39) and 15.4% (6/39) after 24 months. The independent factor associated with PCR negativity was early virologic response (EVR; HBV DNA <2,000 copies/mL after 3 months of therapy, P<0.001). The independent factors predicting HBeAg loss were found to be serum albumin levels (P=0.041) and EVR (P=0.005). CONCLUSIONS: Entecavir induced excellent biochemical and virologic responses in naive CHB patients. EVR was an independent factor for predicting HBV PCR negativity and HBeAg loss.