Palmitic acid induces hepatocellular oxidative stress and activation of inflammasomes / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the effect of palmitic acid (PA) on oxidative stress and activation of inflammasomes in hepatocytes.</p><p><b>METHODS</b>To test the dose-dependent effect of PA on normal murine hepatocytes AML12, the cells were treated with 0, 0.15, 0.25 and 0.4 mmol/L of palmitic acid (PA). The cells were also divided into blank control group, 0.25 mmol/L PA group and 0.25 mmol/L PA+N-acetylcysteine (NAC) group to examine the effect of reactive oxygen species (ROS) on the activation of inflammasomes. After 24 h of treatment, lipid accumulation, total ROS, mitochondrial ROS, expression and localization of NOX4, and expressions of inflammasomes and IL-1β were detected in the hepatocytes.</p><p><b>RESULTS</b>Compared with the control cells, PA treatment of the cells significantly increased cytoplasmic lipid accumulation, concentrations of total ROS (12 463.09±2.72 vs 6691.23±2.45, P=0.00) and mitochondrial ROS (64.98±0.94 vs 45.04±0.92, P=0.00), and the expressions of NOX4, NLRP3, ASC, caspase-1, and IL-1β (1603.52±1.32 vs 2629.33±2.57, P=0.00). The mitochondria and NOX4 were found to be co-localized in the cytoplasm. NAC obviously reduced cellular ROS level stimulated by PA (7782.15±2.87 vs 5445.6±1.17, P=0.00) and suppressed the expressions of NLRP3, ASC and caspase-1.</p><p><b>CONCLUSION</b>PA treatment can stimulate lipid accumulation in hepatocytes and induce oxidative stress through NOX4 and mitochondria pathway to activate inflammasomes and stimulate the secretion of IL-1β.</p>

Value of urgent colonoscopy in diagnosis of severe acute lower gastrointestinal bleeding in patients with different bowel cleanliness / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the value of urgent colonoscopy in the diagnosis of severe acute lower gastrointestinal bleeding and the optimal bowel preparation before examination.</p><p><b>METHODS</b>The clinical data were collected from 188 patients undergoing wither urgent or elective colonoscopy for severe acute lower gastrointestinal bleeding in Nanfang Hospital. Univariate analysis was used to assess the effect of the timing of colonoscopy on the diagnostic rate of hemorrhage, and a multivariate model which stratified bowel cleanliness was used to analyze the impact of bowel cleanliness on the diagnostic rate of urgent colonoscopy.</p><p><b>RESULTS</b>Of the 188 patients, 118 underwent urgent colonoscopy and 70 underwent elective colonoscopy examinations. The diagnostic rates were comparable between the two groups (44.1% vs 41.4%, P=0.724), but urgent colonoscopy resulted in a significantly higher diagnostic rate for identifying the bleeding source (32.2% vs 18.6%, P=0.041). The proportion of the patients taking oral laxatives was significantly lower in urgent colonoscopy group (P<0.001). Oral laxatives versus enema resulted in good, moderate, and poor bowel cleanliness in 63.6% vs 13.5%, 28.6% vs 24.3%, and 7.8% vs 62.2% of the patients (P<0.001). Univariate analysis indicated that good bowel cleanliness was associated with a significantly higher diagnostic rate of colonoscopy than poor bowel cleanliness (P=0.012). Multivariate analysis showed that with good bowel cleanliness, urgent colonoscopy yielded a significantly higher diagnostic rate than elective colonoscopy (P=0.030); subgroup analyses suggested that good bowel cleanliness improved the diagnostic rate of urgent colonoscopy as compared with poor bowel cleanliness (P=0.015).</p><p><b>CONCLUSION</b>In patients with good bowel cleanliness, urgent colonoscopy yields a higher diagnostic rate than elective colonoscopy for severe acute lower gastrointestinal bleeding. Poor bowel cleanliness resulting from bowel preparation by enema significantly lowers the diagnostic performance of urgent colonoscopy. Oral laxatives are recommended over enemas for bowel preparation before urgent colonoscopy when the patients have stable hemodynamics.</p>

Lentivirus-mediated RNA interference suppresses APRIL expression and enhances chemosensitivity in colorectal cancer cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of lentivirus-mediated RNA interference (RNAi) targeting a proliferation-inducing ligand (APRIL) on the chemosensitivity to 5-FU of colorectal cancer cell line LoVo.</p><p><b>METHODS</b>The lentiviral vector siRNA-APRIL was constructed and verified by PCR and DNA sequencing. LoVo cells were transfected with siRNA-APRIL plasmid, non-targeting siRNA plasmid, or empty plasmid. Forty-eight hours after the transfection, the cells were examined for APRIL expression using Western blot. Seventy-two hours after treatment with 10 µg/ml 5-FU, flow cytometry was used to detect the cell apoptosis and cell cycle changes. The cell growth inhibition rate following 5-FU exposure was detected by MTT assay.</p><p><b>RESULTS</b>PCR analysis and DNA sequencing demonstrated that the RNAi sequence targeting APRIL gene was successfully inserted into the lentiviral vector. siRNA-APRIL transfection resulted in obviously reduced expression of APRIL in LoVo cells. After 5-FU exposure, the apoptosis rate of siRNA-APRIL-transfected cells were increased to (21.12∓3.35)%, significantly higher than that in cells transfected with the non-targeting plasmid or the empty plasmid [(13.06∓1.92)% and (12.28∓1.79)%, respectively, P<0.01]; the cell number in G0/G1 phase increased while that in G2/M phase decreased in siRNA-APRIL-transfected cells. The growth inhibition rate in siRNA-APRIL group was (59.67∓5.03)%, significantly higher than that in the other two groups [(42.33∓4.16)% and (39.67∓4.73)%, respectively, P<0.01].</p><p><b>CONCLUSION</b>Lentivirus-mediated RNAi targeting APRIL can effectively suppress the expression of APRIL in LoVo cells and enhance the chemosensitivity of the cells to 5-FU.</p>

Selective COX-2 inhibitor delays experimental gastric ulcer healing by stimulating gastric acid secretion in rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To observe the effect of selective cyclooxygenase-2 (COX-2) inhibitor on the healing of experimental gastric ulcer in rats and explore its mechanisms in light of gastric acid secretion.</p><p><b>METHODS</b>Gastric ulcers were induced in rats by an application of acetic acid to the serosal surface of the anterior gastric body. The effects of selective COX-2 inhibitor, celecoxib, on the healing of gastric ulcer, the total acidity of gastric juice, the expressions of H+, K+-ATPase mRNA and protein, and the ultrastructure of the parietal cell were observed in comparison with the effects of normal saline.</p><p><b>RESULTS</b>Nine days after ulcer induction, the ulcer area was 11.9-/+3.1 mm square and 19.7-/+3.8 mm square in rats with normal saline and celecoxib treatments, respectively (P<0.01). The total acidity of gastric juice and the expressions of H+, K+-ATPase mRNA and protein in celecoxib group were significantly higher than that in normal saline group at both 6 and 9 days after ulcer induction, but no significant difference was found between the two groups in the amount of secretary canaliculus and microvillus.</p><p><b>CONCLUSION</b>Selective COX-2 inhibitor can significantly delay the healing of experimental gastric ulcer in rats, the mechanism of which might be associated with enhanced digestive action of gastric acid on the new granulation tissue at the ulcer base as a result of celecoxib-stimulated gastric acid secretion of the parietal cells.</p>