ABSTRACT
OBJECTIVE： To investigate the protective effect and potential mechanism of epigallocatechin gallate （EGCG） on myocardial ischemia-reperfusion injury. METHODS： H9C2 cardiomyocytes were treated with tert-butyl hydroperoxide （TBHP） to establish ischemia-reperfusion cell model. The cell viability was measured by MTS after pretreated with different doses of EGCG （3.125， 6.25， 12.5， 25， 50， 100， 200 μmol/L）， and the survival rate was calculated. The expression of apoptotic proteins （Bcl-2， Bax） in cardiomyocytes pretreated with different doses of EGCG （100， 200 μmol/L） were detected by Western blotting. Male C57BL/6 mice were randomly divided into sham operation group， model group and EGCG group （5 mg/g）， with 15 mice in each group. Sham operation group and model group were given constant volume of normal saline intragastrically， while EGCG group was given relevant medicine intragastrically， once a day， for consecutive 7 d. Twelve hours after last medication， myocardial ischemia-reperfusion injury model was established by anterior descending coronary artery ligation. The area of myocardial infarction was observed by double staining of Evan’s blue and TTC； the percentage of infarction area to cross-sectional area was calculated；SOD activity and MDA content in serum were determined by WST-1 assay； the expression of apoptotic proteins （Bcl-2， Bax） in myocardial tissue were detected by Western blotting， while the phosphorylation levels of signaling pathway related proteins （PI3K， p-PI3K， Akt， p-Akt） were also detected. RESULTS： Cell test results showed that， compared with control group， survival rate and relative expression of Bcl-2 were decreased significantly in model group， while relative expression of Bax was increased significantly （P＜0.05）. Compared with model group， survival rate of cardiomyocyte in 25， 50， 100， 200 μmol/L EGCG groups as well as relative expression of Bcl-2 in 100， 200 μmol/L EGCG groups were increased significantly， while relative expression of Bax in 100， 200 μmol/L EGCG groups were decreased significantly （P＜0.05）. Animal experiments showed that no ischemia of myocardial tissue and enlargement of cardiac cavity were observed in sham operation group. Myocardial infarction was observed in model group. Compared with sham operation group， percentage of infarction area to cross-sectional area， the serum content of MDA， the relative expression of Bax in myocardial tissue and p-PI3K/PI3K， p-Akt/Akt were increased significantly in model group， while SOD activity and relative expression of Bcl-2 were decreased significantly （P＜0.05）. Compared with model group， myocardial infarction area of mice in EGCG group was reduced， the percentage of infarction area to cross-sectional area， the serum content of MDA， the relative expression of Bax in myocardial tissue and p-PI3K/PI3K， p-Akt/Akt were significantly decreased， the activity of SOD activity and the relative expression of Bcl-2 were increased significantly （P＜0.05）. CONCLUSIONS： EGCG can protect against myocardial ischemia-reperfusion injury， the mechanism of which may be associated with inhibiting the apoptosis of myocardial cells， improving oxidation stress， regulating the expression of apoptotic protein， reducing the phosphorylation level of PI3K/Akt signaling pathway-related proteins.
ABSTRACT
Objective To evaluate the efficacy and drug resistance profiles of nucleosides (NA) retreatment in NA experienced chronic hepatitis B (CHB) patients. Methods Totally 104 NA experienced CHB subjects were enrolled in this study.All these subjects had received at least 3 months NA monotherapy and stopped the treatment,and then received NA retreatment for at least one year.The subjects were divided into three groups according to the following criteria:reached the therapy endpoint of China guideline when they stopped NA-naive treatment (group A,n =39); did not reach the therapy endpoint when they stopped NA-naive treatment but hepatitis B virus (HBV) DNA＜1.0× 103 copy/mL (group B,n=33); and with HBV DNA＞1.0× 103 copy/mL (group C,n=32).The efficacy and drug resistance profiles of retreatment were compared among three groups. The effects of baseline alanine aminotransferase (ALT) levels,HBV DNA levels and HBeAg titers on the retreatment efficacies were analyzed. The mutations of HBV P gene were detected by nested polymerase chain reaction (PCR) and direct sequencing.The data were analyzd by Wilcoxon test and x2 test.Results The time to ALT normalization in patients with baseline ALT＜ 1.3 × upper limit normal (ULN) was shorter than that in patients with ALT≥1.3×ULN (2 months vs 4 months; Z=2.281,P=0.023).The time to virological response in patients with baseline HBV DNA＜5 lg copy/mL was shorter than that in patients with HBV DNA≥5 lg copy/mL (1 month vs 2 months; Z=2.054,P =0.040). The time to virological response and ALT normalization in baseline HBeAg negative were both shorter than those in patients with baseline HBeAg positive patents ( 1 month vs 3 months and 2 months vs 4.5 months,respectively; Z=2.580 and 2.304,respectively; both P＜0.05). The subjects in group A achieved virological response and HBeAg seroconversion after retreatment earlier compared to previous NA-naive therapy ([1.61 ± 1.76] months vs [3.48±4.066]months and [3.38 ± 3.34] months vs [9.92-11.22] months,respectively; Z=-2.854 and-1.094,respectively; both P＜0.05).The cumulative HBeAg seroconversion rate in group A was higher compared to those in group B and group C (80.0％ vs 36.8％ and 37.5％,respectively; x2 =4.368 and 5.100,respectively; both P＜0.05).Thirteen patients developed clinical resistance and four of them developed genotypic resistance proved by PCR direct sequencing.Among the patients retreated with the same regimen as previous in the C group,the cumulative resistance rate was highest compared to group A and B (44％ vs 9％ and 0,respectively; x2 =5.019 and 6.588,respectively;both P＜0.05).No resistance was detected in the 14 patients retreated with combined NA treatment without cross resistance.Conclusions For NA experienced CHB patients who fulfill the indication of antiviral therapy,the retreatment should be started as earlier as possible. Retreatment with NA combination without cross resistance can prevent (reduce) the risk of developing drug resistance.