Study on the synergetic degradation of chitosan with ultraviolet light and hydrogen peroxide.

Chitosan was effectively degraded by hydrogen peroxide under irradiation with ultraviolet light. The existence of a synergetic effect on the degradation was demonstrated by means of viscometry. In addition, the optimal conditions of degradation were determined on the basis of orthogonal tests. The structure of the degraded product was characterized by Fourier-transform infrared spectra (FTIR) analysis and diffuse reflectance spectra (DRS) analysis. The mechanism of the degradation of chitosan was correlated with cleavage of the glycosidic bond.

Effect of methylene blue on hydrogen peroxide-induced apoptosis in macrophages through mitochondria-dependent pathway in mice / 中华麻醉学杂志

Objective To evaluate the effect of methylene blue (MB) on hydrogen peroxide (H2O2)-induced apoptosis in macrophages through mitochondria-dependent pathway in mice.Methods Mouse peritoneal macrophage line RAW264.7 cells were cultured in DMEM culture medium containing 10％ fetal bovine serum.Cells were divided into 6 groups (n =24 each) using a random number table method:control group (group C),H2O2 group,prophylactic different concentrations of MB groups (MB1,2 groups) and therapeutic different concentrations of MB groups (MB3.4 groups).H2O2 50 μmol/L was added to the culture medium in group H2O2.MB was added to the culture medium with the final concentrations of 0.1 μmol/L (in MB1 and MB3 groups) and 1.0 μmol/L (in MB2 and MB4 groups) at 30 min before adding H2O2 in MB1.2 groups and 30 min after adding H2O2 in MB3.4 groups.At 24 h of culture or incubation in each group,the cell survival rate was measured by methyl thiazolyl tetrazolium assay,the activity of reactive oxygen species (ROS) in cells was determined with the fluorescent probe,the lactate dehydrogenase (LDH) activity in supernatant was detected by spectrophotometry,the activity of superoxide dismutase (SOD) in cells was detected by colorimetric method,mitochondrial membrane potential (MMP) was measured using rhodamine 123 staining,the content of ATP was determined by an ATP bioluminescent method,the expression of pro-caspase-3 and spliceosomes P20 protein and P 18 protein was detected by Western blot,and cell apoptosis was detected using flow cytometry.Results Compared with group C,the cell survival rate,SOD activity and contents of MMP and ATP were significantly decreased,the ROS activity and activity of LDH in supernatant were increased,the expression of pro-caspase-3 and spliceosomes P20 protein and P18 protein was up-regulated,and early and late apoptosis rates were increased in the other five groups (P＜0.05).Compared with group H2O2,the cell survival rate,SOD activity and contents of MMP and ATP were significantly increased,the ROS activity and activity of LDH in supernatant were decreased,the expression of pro-caspase-3 and spliceosomes P20 protein and P18 protein was down-regulated,and early and late apoptosis rates were decreased in MB1-4 groups (P＜0.05).Compared with group MB1,the cell survival rate was significantly decreased,and the expression of caspase-3 spliceosome P 18 was down-regulated in group MB2,and the cell survival rate and SOD activity were significantly decreased,and the activity of ROS was increased in group MB3 (P＜0.05).Compared with group MB4,the expression of caspase-3 spliceosome P 18 was significantly down-regulated,early and late apoptosis rates were decreased,and the activity of ROS was increased in group MB2,and the activity of ROS was significantly increased in group MB3 (P＜0.05).Conclusion The mechanism by which MB attenuates H2O2-induced oxidative damage to macrophages is related to inhibiting cell apoptosis in macrophages through mitochondria-dependent pathway in mice.

Protective effects of methylene blue on ischemia/reperfusion-induced mitochondrial injury in isolated rat hearts / 中国病理生理杂志

AIM:To study the effects of methylene blue (MB) on myocardial ischemia/reperfusion (I/R)-induced mitochondrial injury in isolated rat hearts.METHODS:Spragure-Dawley (SD) rats were divided into 3 groups randomly (n=6): control group, I/R model group and MB treatment group (IR+MB group).The isolated rat hearts were prepared and set up to Langendorff perfusion.The rats in I/R+MB group received MB (2 mg/kg) by intraperitoneal injection 2 h before operation.The hearts in control group were perfused with K-H solution for 110 min consecutively.The hearts in I/R group and I/R+MB group were in equilibrium for 20 min, following by 45 min of global ischemia, and then reperfused for 60 min.The heart rate (HR), left ventricular developed pressure (LVDP), left ventricular pressure maximum change rate (±dp/dtmax) and left ventricular end-diastolic pressure (LVEDP) were recorded.The perfusate was collected to determine the activity of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH).The contents of reactive oxygen species (ROS), malondialdehyde (MDA) and adenosine triphosphate (ATP), and the activity of superoxide dismutase (SOD) in the myocardial tissues were all determined.Histopathological examination of left ventricle was performed.The mitochondria from the heart tissues was isolated and the mitochondrial swelling and mitochondrial membrane potential (MMP) were analyzed.RESULTS:Compared with control group, the hearts in I/R group showed poorer function, higher CK-MB and LDH levels in the perfusate, increased ROS and MDA contents, higher SOD activity and less ATP content in the heart tissues (P<0.05).Furthermore, the mitochondrial swelling level increased and MMP reduced in I/R group (P<0.05).Compared to I/R group, MB improved heart function and reduced the release of CK-MB and LDH (P<0.05).MB also decreased ROS and MDA contents, and increased the activity of SOD and the content of ATP (P<0.05).In addition, MB alleviated mitochondrial swelling and restored the reduced MMP (P<0.05).CONCLUSION: MB protects the isolated rat hearts from I/R-induced injury by attenuating the damage of mitochondria.

Biliverdin Protects the Isolated Rat Lungs from Ischemia-reperfusion Injury via Antioxidative, Anti-inflammatory and Anti-apoptotic Effects / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Biliverdin (BV) has a protective role against ischemia-reperfusion injury (IRI). However, the protective role and potential mechanisms of BV on lung IRI (LIRI) remain to be elucidated. Thus, we aimed to investigate the protective role and potential mechanisms of BV on LIRI.</p><p><b>METHODS</b>Lungs were isolated from Sprague-Dawley rats to establish an ex vivo LIRI model. After an initial 15 min stabilization period, the isolated lungs were subjected to ischemia for 60 min, followed by 90 min of reperfusion with or without BV treatment.</p><p><b>RESULTS</b>Lungs in the I/R group exhibited significant decrease in tidal volume (1.44 ± 0.23 ml/min in I/R group vs. 2.41 ± 0.31 ml/min in sham group; P< 0.001), lung compliance (0.27 ± 0.06 ml/cmH2O in I/R group vs. 0.44 ± 0.09 ml/cmH2O in sham group; P< 0.001; 1 cmH2O=0.098 kPa), and oxygen partial pressure (PaO2) levels (64.12 ± 12 mmHg in I/R group vs. 114 ± 8.0 mmHg in sham group; P< 0.001; 1 mmHg = 0.133 kPa). In contrast, these parameters in the BV group (2.27 ± 0.37 ml/min of tidal volume, 0.41 ± 0.10 ml/cmH2O of compliance, and 98.7 ± 9.7 mmHg of PaO2) were significantly higher compared with the I/R group (P = 0.004, P< 0.001, and P< 0.001, respectively). Compared to the I/R group, the contents of superoxide dismutase were significantly higher (47.07 ± 7.91 U/mg protein vs. 33.84 ± 10.15 U/mg protein; P = 0.005) while the wet/dry weight ratio (P < 0.01), methane dicarboxylic aldehyde (1.92 ± 0.25 nmol/mg protein vs. 2.67 ± 0.46 nmol/mg protein; P< 0.001), and adenosine triphosphate contents (297.05 ± 47.45 nmol/mg protein vs. 208.09 ± 29.11 nmol/mg protein; P = 0.005) were markedly lower in BV-treated lungs. Histological analysis revealed that BV alleviated LIRI. Furthermore, the expression of inflammatory cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-β) was downregulated and the expression of cyclooxygenase-2, inducible nitric oxide synthase, and Jun N-terminal kinase was significantly reduced in BV group (all P< 0.01 compared to I/R group). Finally, the apoptosis index in the BV group was significantly decreased (P < 0.01 compared to I/R group).</p><p><b>CONCLUSION</b>BV protects lung IRI through its antioxidative, anti-inflammatory, and anti-apoptotic effects.</p>

PI3 K/Akt/Sirt1 signaling pathway mediated hydrogen sulfide postconditioning-induced protection against I/R injury / 中国药理学通报

Aim To explore the role of PI3 K/Akt/Sirt1 pathway in cardioprotection of hydrogen sulfide ( H2 S ) postconditioning against ischemia/reperfusion ( I/R) injury. Methods Langendorff perfusion appa-ratus was used to build an isolated rat myocardial I/R model. Isolated rat hearts were subjected to 30 min global ischemia followed by 60 min reperfusion after 20 min of equilibrium. 60 male SD rats were randomly di-vided into 5 groups(n=12):control group(Control), ischemia/reperfusion group( I/R) , H2 S postcondition-ing group( H2 S) , inhibitor LY294002 group( LY) and H2 S with inhibitor group( H2 S+LY) . The left ventric-ular diastolic pressure ( LVEDP ) , the left ventricular developed pressure(LVDP), the maximum rate of in-crease or decrease of left ventricular pressure ( ± dp/dtmax ) were registered at the end of 20 min equilibri-um, 30 and 60 min of reperfusion separately. Triphe-nyl tetrazolium chloride( TTC) staining was used to de-termine the myocardial infarct size. The levels of Sirt1 and PGC-1 mRNA were tested using real-time PCR. The expressions of Sirt1 and PGC-1αwere detected with Western blot analysis. Immunohistochemical method was used to determine the location of Sirt1 . Results There were no differences in equilibrium hemodynamics observed between the experimental groups(P>0. 05). At the end of reperfusion, compared with I/R group, H2 S group had obviously ameliorated functional recov-ery and significantly decreased the myocardial infarct size(26. 9 ± 4. 9)% vs(48. 9 ± 5. 6)%(P <0. 05). Meanwhile, the expression of Sirt1 and PGC-1α in-creased significantly. However,LY294002 reversed the cardioprotective effects provided by hydrogen sulfide postconditioning and reduced the level of Sirt1 and PGC-1α, the percentage of Sirt1-positive nuclei. Con-clusion PI3 K/Akt/Sirt1 signaling pathway mediates the hydrogen sulfide postconditioning-induced protec-tion against I/R injury.

A novel supramolecular compound 2,2'-bipyridyl-phosphotungstic acid: synthesis and catalysis.

A new supramolecular compound (C(10)H(8)N(2))(3.2).H(3)PW(12)O(40).25.6H(2)O (Bipy-PW(12)) was synthesized by self-assembly design, and characterized by elemental analysis, Fourier-transform infrared spectra (FTIR), and (31)P NMR spectra. Bipy-PW(12) can effectively catalyze oxidative degradation of chitosan with H(2)O(2) in heterogeneous phase. To obtain water-soluble chitosan with an average molecular weight of 5000, the optimum reaction conditions were determined as follows: reaction temperature, 80 degrees C; reaction time, 13min; H(2)O(2) concentration, 2.7mol/L; and mass ratio of Bipy-PW(12) to chitosan, 0.01.