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Objective:To investigate the effect of degassing and peroxidation on metal-ceramic bonding strength of Pd-Ag alloy. Methods:The metal-ceramic interface of group A (peroxidation)and B (degassing)was investigated under scanning electronic micro-scope(SEM)and energy dispersive spectrum (EDS).The bond strength between metal and ceramics was measured using a three-point bend test according to ISO9693.Results:The formation of nodules on the surface of alloy specimens was observed in both groups by SEM.The nodules on the specimens of group A were more densely than those of group B.The diameter of nodules in group B was 1 .5μm approximately.The interface of the metal-ceramic specimens had a clear transition porcelain layer and no hole or slit was present. The mean bonding strength of group A and B was (45.97 ±3.92)MPa and (49.1 1 ±6.42)MPa respectively(P=0.031 ).Conclu-sion:Degassing can improve metal-ceramic bonding strength of Pd-Ag alloy significantly.
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Objective This study describes the protective effect of myocardial isehemic post- conditioning on ischemic-reperfused myocardium (I/ R) of diabetic rat and its Signaling mechanism. Methods Healthy SD rats weighing 25O-30Og were divided into 6 groups; (1) Blank control; (2) Ischemia-reperfusion; (3) Post conditioning; (4) Diabetic postconditioning ; (5) Diabetic ischemia-reperfusion; ( 6) Diabetic blank control group. Ten rats in each group were randomly selected. Introduction of diabetic rat model: 65 mg/kg STZ was injected into the intraperitoneal cavity, until 2 consecutive blood glucose measurements≥ 16.65 mmol/L were reached after48h. The diabetic model was successful when rats had following symptoms, such as more drinking, more eating, polyuria, weight loss and epilation. Langendorff isolated rat heart perfusion was used for the experiment. Following parameters were measured and compared: Coronary perfusion flow, myocardial infarct size, western blot for measurement of P-Akt, changes in myocardium and mitochondrian observed by Electron microscopy. Results Blood glucose concentration in diabetic group was (23. 15±2. 16) mmol/L and (4. 16±0. 31) mmol/L in non-diabetic group. There was a significant difference (P <0. 01) between the two groups. There were more coronary flow in post-conditioning groups (Post group and Dpost group) than ischemia-reperfusion groups (IR group and DIR group) (6.5±1.2、5.6±1.0 vs. 3.4±1.0、2.0±1.3). The myocardial infarction size was smaller in post-conditioning groups than in ischemia-reperfusion groups (25.2±2.1、34.2±3.6 vs. 47.5±3.5 、65.2±4.5). There was more expression of P-Akt and the myocardial fibers and mitochondrian in post-conditioning groups were better preserved. Conclusion Postconditioning has protective effects in diabetic rat hearts. The mechanism may be associated with Akt activation.
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Objective To study the clinical features and treatment of gingiva plasma cell granulo-ma.Method The clinical information of 9 cases with gingival plasma cell gmnuloma Was analyzed retre-spectively.Results The disease most frequently attacked the people between age 20-40 years(77.8%) and the main pathogenic position were at the gingival of bicuspid and molar teeth.Clinical maJlif.estation were gingival swelling and bleeding,dental loosening and dropping.Three patients were given focal resection. Subgingival curettage and Chinese traditional medicine.After loosening teeth found and peridental absortion shown in X-rays,6 patients were operated to extract loosening teeth and reseet their foci,in which 2 patients were given hormonotherapy and small-dose radiotherapy after operation.All cases were cured and no recurrence were found after follow-up survey from halfa year to 2 years.Conclusions The disease is rare and call result in the loss of periodontal tissue in a short time.In its premature time.the disease can be effectively cured by focal excision with subgingival curettage and Chinese traditional medicine.If Deriodontal tissue has been invaded,Surgical excision and extraction of teeth is the main way.
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Objective:To summarize the experience of surgical treatment of valvular heart disease with enlarged or small left ventricles. Methods:Valvular operations were performed in 473 patients,including 38 with enlarged left ventricles(group Ⅰ)and 40 with small left ventricles(group Ⅱ),from April 1998 to June 2005.Postoperative complications between two groups were com- pared and analyzed statistically. Results:The postoperative eomplications were ventricular arrhythmia,low output syndrome,lung infection,renal failure and brain embolism.Low output syndrome tended to occur in group Ⅱ(20%),whereas there was a higher incidence of ventricular ar- rhythmia in group Ⅰ(65.79%).The difference between groups was significant(P＜0.05). Conclusion:To improve the successful operative rate in patients with enlarged or small left ventricles,we should take effec- tive measures to manage the post-procedural complications,such as ventricular arrhythmia(mainly in group Ⅰ)and low output syndrome(mainly in group Ⅱ).
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Objective To explore the influence of diabetes on the protective effect of ischemic preconditioning(IPC) on ischemic-reperfused(IR) myocardium of rat.Methods Sixty male SD rats(30 with diabetes and 30 without diabetes) were divided into six groups(10 each): non-diabetic rats control group(group A),non-diabetic rats IR group(group B),non-diabetic rats IPC group(group C),diabetic rats control group(group D),diabetic rats IR group(group E) and diabetic rats IPC group(group F).The isolated heart perfusion Langendorff models were established after rats were sacrificed.Isolated hearts of the two control groups were undergone a 90min perfusion without any other intervention;those of the two IR groups were undergone a 30min equilibration period,a 30min ischemia and a 30min reperfusion;those of the two IPC groups were undergone a 10min equilibration,then elicited by two cycles of 5min ischemia interspersed with 5min reperfusion prior to 30min ischemia and a 30min reperfusion.The recovery rates of the left ventricular function,such as cardiac output(CO) and left ventricular developed pressure(LVDP),and the maximum upstroke and decay velocities of left ventricular pressure(?dp/dtmax) were recorded.The activity of creatine kinase(CK) in coronary outflow,contents of malonyldialdehyde(MDA) and superoxide dismutase(SOD) in myocardium were detected,and myocardial water ratio were assessed.Results In non-diabetic rats IPC group,the activity of CK,content of MDA and water ratio of myocardium declined significantly,while the content of SOD increased and the recovery rates of CO,LVDP and ?dp/dtmax rose significantly compared with that in non-diabetic rats IR group(P0.05).Conclusion Diabetes may inhibit the protective effect of ischemic preconditioning on ischemic reperfused rat heart.
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AIM To study mechanism of endothelin (ET) on canine pulmonary veins. METHODS The isometric tension of pulmonary venous strips was recorded. RESULTS ET 3 and IRL1640 produced contraction in pulmonary venous strips. ET 3 induced contraction was markedly suppressed by BQ123 (P