Objective To evaluate the dynamic viscoelasticity of unpolymerized light-cured composite resins reinforced with retentive filler(RF)or normal filler(NF),and the effect of dynamic viscoelasticity on clinical manipulation.Methods The dynamic viscoelastic properties of two light-cured composite resins reinforced with RF or NF were measured respectively with the dynamic stress rheometer.Flowing property,filling capacity,shaping and stability were designed to describe the clinical manipulation of the composites.Results The dynamic viscoelastic behavior of the composites is sensitive to changes in frequency,composite resin reinforced with RF had significantly higher shear storage modulus(G')and shear loss modulus(G″)than composite resins reinforced with NF,and had significantly lower loss tangent(tan?).The former was found to be more viscous,and the latter was found to be more elastic.Clinically,composite resin reinforced with RF has a greater ability of stability and shaping,and a lower potential for deformation;composite resin reinforced with NF has a higher flowing ability,and with a good adaptation to the cavity of the tooth.Conclusions The ideal composites should have high G' and low tan?.

BACKGRoUND:The clinical manipulation properties of light-cured composite resin,such as flowing property.filling capacity,shaping and stability has not unified definition in dental materials notwithstanding more studies of rheological behaviors were undertook.OBJECTIVE:To explore the dynamic viscoelasticity difference of unpolymerized light.cured composite resins with retentive filler or normal filler,and to investigate effect on the clinical manipulation properties of rheological behaviors in two light-cured composite resins to define an ideal resin.DESIGN,TIME AND SETTING:This controlled study is a correlation study of integrating the base study and clinical use.Basic study was performed in January 2003 at Key Laboratory of Engineering Plastics of Chinese Academy of Sciences in Beijing.The clinical observation study was conducted at the Stomatology Center,Haikou People's Hospital until December 2006.MATERIALS:Light-cured composites employed in this study were reinforced with RF(experimental composite resin I,ECR-Ⅰ)or NF(experimental composite resin Ⅱ,ECR-Ⅱ),which were supplied by Dental Materials Laboratory.Medical College of Stomatology of Peking University.They contained different types of fillers,but had the same resin matrix and volume percent of filler.METHODS:The dynamic viscoelastic properties of ECR-Ⅰ or ECR-Ⅱ were measured respectively with the dynamic stress rheometer DSR-200 in a room maintained 25℃.Flowing property,filling capacity,shaping and stability property were employed to assess the clinical manipulation property of ECR.MAIN OUTCOME MEASURES:Viscoelasticity(G',G",tan δ)and clinical manipulation of two kinds of compound resins.RESULTS:The dynamic viscoelastic behavior of the two composites was sensitive to changes in frequency.ECR-Ⅰhad significantly higher G'than ECR-Ⅱ.ECR-Ⅰ had a greater ability of stability and shaping.and a lower potential for deformation clinically.ECR-Ⅱ had significantly higher G"than ECR-Ⅰ.and ECR-Ⅱ had a higher flowing ability clinically.ECR-Ⅱ had significantly higher tan δ than ECR-Ⅰ.ECR-Ⅱ was found to be more viscous and better filling capacity,with a good adaptation to the cavity of the tooth clinically.CONCLUSION:The dynamic viscoelasticity(G',G",tan δ)and clinical manipulation properties of ECR-ⅠI or ECR-Ⅱ are compared.The ideal composites should have higher G'and lower tan δ

Objective To evaluate the effect of remote limb ischemic postconditioning on the level of adiponectin during myocardial ischemia-reperfusion (I/R) in rats.Methods Fifty-seven male Sprague-Dawley rats,aged 8 weeks,weighing 250-350 g,were randomly divided into 3 groups (n =19 each):sham operation group (group S); group I/R; remote limb ischemic postconditioning group (group RLIP).Myocardial ischemia was induced by occlusion of anterior descending branch of left coronary artery for 30 min followed by 180 min reperfusion in urethane-anesthetized rats.In group S,the anterior descending branch was only exposed but not ligated.The animals underwent 10 min ischemia of bilateral hind limbs starting from 20 min of occlusion of the anterior descending branch,followed by reperfusion in RLIP group.The changes in S-T segment were recorded at 30,60,120 and 180 min of reperfusion.At 180 min of reperfusion,the blood samples were taken from the jugular vein for determination of serum levels of creatine kinase MB (CK-MB) and cardiac troponin Ⅰ (cTnⅠ).The animals were then sacrificed and hearts were removed for measurement of myocardial infarct size (IS) and adiponectin contents in myocardial tissues (by ELISA).Results Compared with group S,S-T segment was significantly elevated at each time point,myocardial IS,and serum cTnⅠ and CK-MB levels were increased,and adiponectin contents were decreased in I/R and RLIP groups.Compared with group I/R,elevation of S-T segment was significantly decreased at each time point,myocardial IS,and serum cTnⅠ and CK-MB levels were decreased,and adiponectin contents were increased in RLIP group.Conclusion The mechanism by which remote limb ischemic postconditioning reduces myocardial I/R injury is related to increased level of adiponectin in the myocardium of rats.

Objective To evaluate the effects of edaravone postconditioning and remote ischemic postconditioning on myocardial ischemia/reperfusion (I/R) injury in rats.Methods Forty male Sprague-Dawley rats,aged 8 weeks,weighing 250-300 g,were randomly divided into 5 groups (n =8 each):sham operation group (group S); group I/R; edaravone postconditioning group (group E); remote ischemic postconditioning group (group P); edaravone postconditioning and remote ischemic postconditioning group (group EP).Myocardial I/R was induced by occlusion of anterior desending branch of left coronary artery for 30 min followed by 180 min reperfusion.Edaravone 3 mg/kg was injected intravenously at 1 min before reperfusion in groups E and EP.The animals underwent 10 min ischemia of bilateral hind limbs starting from 20 min of myocardial ischemia in groups P and EP.Left ventricular systolic pressure (LVSP),left ventricular end-diastolic pressure (LVEDP) and ± dp/dtmax were measured and recorded during reperfusion.Results Compared with group S,LVSP and ± dp/dtmax were significantly decreased and LVEDP was increased in the other groups (P ＜ 0.05).LVSP and ± dp/dtmax were significantly higher and LVEDP was lower during reperfusion in groups E,P and EP than in group I/R,and in group EP than in groups E and P (P ＜ 0.05).Conclusion Edaravone postconditioning and remote ischemic postconditioning can alleviate myocardial I/R injury and offers better efficacy than either alone.

Objective To evaluate the role of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway in attenuation of ischemia injury by hydrogen-rich University of Wisconsin (HRUW) solution during cold storage of rat donor kidneys.Methods Forty healthy adult male Wistar rats,weighing 200-250 g,were divided into 4 groups (n =10 each) using a random number table:control group (group C),University of Wisconsin (UW) solution group (group UW),HRUW solution group (group HRUW) and Nrf2 inhibitor all-trans retinoic acid (ATRA) group (group ATRA).ATRA 7 mg/kg was intraperitioneally injected once a day for 2 consecutive days,kidneys were isolated and underwent cold storage at 8 h after the last administration,and kidneys were stored in HRUW solution for 48 h at 4 ℃C in group ATRA.In UW and HRUW groups,the equal volume of normal saline was intraperitioneally injected instead,and isolated kidneys were stored in UW solution and HRUW solution for 48 h at 4 ℃C,respectively.Kidney specimens were obtained for microscopic examination and for determination of tumor necrosis factoralpha (TNF-α),interleukin-lbeta (IL-1β3),high-mobility group box 1 protein (HMGB1),IL-10 and 8-iso-prostaglandin F2α (8-iso-PGF2α) contents (by enzyme-linked immunosorlbent assay),superoxide dismutase (SOD) and catalase (CAT) activities (using spectrophotometry),and expression of Nrf2,heme oxygenase-1 (HO-1),Bcl-2,Bax and caspase-3 in renal tissues (by using Western blot).The damage to the renal tubules was scored.Results Compared with group C,renal tubular damage scores were signifieantly increased,TNF-α,IL-1β,HMGB1 and 8-iso-PGF2α contents were increased,IL-10 contents were decreased,the expression of Nrf2 and HO-1 was up-regulated,SOD and CAT activities were decreased,the expression of Bcl-2 was down-regulated,and the expression of Bax and caspase-3 was upregulated in group UW (P＜0.05 or 0.01).Compared w,ith group UW,renal tubular damage scores were significantly decreased,TNF-α,IL-1β,HMGB1 and 8-iso-PGF2α contents were decreased,IL-10 contents were increased,the expression of Nrf2 and HO-1 was up-regulated,SOD and CAT activities were increased,the expression of Bcl-2 was up-regulated,and the expression of Bax and caspase-3 was down-regulated in group HRUW,and the expression of Nrf2 and Bcl-2 was up-regulated (P＜0.05),and no significant change was found in the other parameters in group ATRA (P＞0.05).Compared witb group HRUW,renal tubular damage seores were significantly increased,TNF-α,IL-1β,HMGB1 and 8-iso-PGF2α contents were increased,IL-10 contents were decreased,the expression of HO-1 and Bcl-2 was down-regulated,SOD and CAT activities were decreased,and the expression of Bax and caspase-3 was up-regulated in group ATRA.Conclusion HRUW solution reduces inflammatory responses,oxidative damage and cell apoptosis during cold storage of rat donor kidneys,and the mechanism by which HRUW solution attenuates ischemia injury is related to activation of Nrf2 signaling pathway.

Objective To investigate the effect of berberine pretreatment on hypoxia/reoxygenation (H/R)-induced apoptosis in human renal tubular epithelial cells.Methods The human renal tubular epithelial cells were cultured and seeded in culture dishes (2 ml/dish) or 96-well plates (200 μl/well) with the density of 1 ×106/ml.The cells were then randomly divided into 4 groups (n =30 each):normal control group (group C),berberine group (group B),H/R group and H/R + berberine group (H/R + B group).In groups B and H/R + B,berberine 10 μmol/L was added to the culture medium and the cells were incubated for 2 h.Groups H/R and H/R + B were then exposed to 94％ N2-5％ CO2-1％ O2 for 24 h followed by 3 h reoxygenation.The cell viability,apoptotic rate and level of malondialdehyde (MDA) and superoxide dismutase (SOD) were detected.The expression of caspase-3,activated caspase-3,cytochrome c,glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP) was determined.The ratio of Bax/Bcl-2 was calculated.Results Compared with group C,the cell viability,SOD activity and caspase-3 expression were significantly decreased,the apoptotic rate,Bax/Bcl-2 ratio and concentration of MDA were increased,and the expression of activated caspase-3,cytochrome c,GRP78 and CHOP was up-regulated in groups H/R and H/R + B (P ＜ 0.05).Compared with group H/R,the cell viability,SOD activity and caspase-3 expression were significantly increased,the apoptotic rate,Bax/Bcl-2 ratio and concentration of MDA were decreased,and the expression of activated caspase-3,cytochrome c,GRP78 and CHOP was down-regulated in group H/R + B (P ＜ 0.05).Conclusion Berberine pretreatment can inhibit H/R-induced apoptosis in human renal tubular epithelial cells,and inhibition of mitochondrial stress pathway and endoplasmic reticulum stress pathway is involved in the mechanism.

Objective To investigate the effects of hydrogen-rich HC-A solution,the self-made kidney preservation solution,on renal cold ischemia/reperfusion (I/R) injury in rats.Methods Twenty-four healthy male Wistar rats,aged 8-10 weeks,weighing 200-250 g,were randomly divided into 3 groups (n =8 each):control group (H1 group),common kidney preservation solution group (H2 group) and hydrogen-rich HC-A kidney preservation solution group (H3 group).In H1 group,only the right kidney was removed.In H2 group,the left kidney was perfused with and cold stored in 4 ℃ common HC-A kidney preservation solution.In H3 group,the left kidney was perfused with and cold stored in a container filled with 4 ℃ common HC-A kidney preservation solution.Blood samples were obtained from the inferior vena cava at 24 h of reperfusion to detect the levels of serum blood urea nitrogen (BUN),creatinine (Cr),TNF-α and IL-6.Left kidneys were removed for determination of malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents and for examination of the pathological changes in renal tissues (by light microscopy).Results The levels of serum BUN,Cr,TNF-α and IL-6 and contents of MDA and 8-OHdG were significantly higher in H2 and H3 groups than in H1 group,and lower in H3 group than in H2 group (P ＜ 0.05).There were no significant pathological changes in renal tissues in H1 group,the damage to renal tubules was obvious in H2 group and the damage to renal tubules was significantly ameliorated in H3 group as compared with H2 group.Conclusion Hydrogen-rich kidney preservation solution can attenuate renal cold I/R injury in rats.

OBJECTIVETo inspect the directionality of adhesive strength between composite resins and dental hard tissues.

METHODSTwo kinds of composite resins were bonded with their luting kits to the enamel and dentin surfaces of bovine teeth separately. The dead load shear and impact shear testing were performed from both of root apex direction and cutting edge direction.

RESULTSThe shear adhesive strength between the enamel and two kinds of composite resins was on the same behavior, that the shear adhesive strength of root apex direction was greater than that of cutting edge direction. In the dead load shear testing, the former was about two to three times of the latter (P < 0.05). In the impact shear testing, the former was about three to four times of the latter (P < 0.001). The effect of the direction of acting force was small on the shear adhesive strength between the dentin and two kinds of composite resins. In the both dead load shear testing and impact shear testing, there was no statistically significant difference between the datum of two directional loadings (P > 0.05, P > 0.5).

CONCLUSIONThe shear adhesive strength between the composite resins and enamel of bovine teeth is related to the acting direction of the shear force.

Adhesiveness ; Adhesives ; standards ; Animals ; Cattle ; Composite Resins ; standards ; Dental Bonding ; Dental Enamel ; Dentin ; Dentin-Bonding Agents ; standards ; Materials Testing ; methods ; Resin Cements ; standards ; Shear Strength