Objective To determine the diagnostic value of the change of different parts of electrocardiogram in treadmill exercise test (TET) for coronary heart disease (CHD).MethodsFrom Jan.2006 to Mar.2011,445 patients with CHD underwent treadmill exercise test and coronary angiography (CAG) in our hospital.We analyzed retrospectively the diagnostic value of the change of different parts of electrocardiogram in TET test.Results ( 1 ) There were 200 cases who had positive results during treadmill exercise test and 150 cases of them had been diagnosed of CHD by coronary angiography;The other 245 cases had negative results during treadmill exercise test and 39 cases of them had been diagnosed as CHD by coronary angiography.The sensitivity and specificity rates of treadmill exercise test in diagnosis of CHD were 79.36％( 150/189 ) and 80.47％ ( 206/256 ) respectively. ( 2 ) Of the 200 positive cases tested by coronary angiography,150 cases were diagnosed of CHD,including 22,58 and 70 cases with limb,chest and combined chest and limb leads positive results respectively.The positive rates for the groups of combined chest and limb leads and limb ST leads were significantly higher than that of the chest leads only group ( x2:6.34,3.93 ; P ＜0.05).(3)R wave amplitude of the CAG negative group after exercise (17.54 ± 2.52)mm was significantly lower than the CAG positive group ( 19.42 ± 3.46 )mm ( t =6.33,P ＜ 0.05 ).( 4 ) For the 200 cases with positive TET,there were no significant statistical difference ( P ＞ 0.05 ) on CAG positive rate between T wave normalization group [ 73.3％ (44/60) ] with and TET positive group [ 75.0％ (105/140) ].But these two groups had significantly higher ( x2:80.21,132.82 ; P ＜ 0.05 ) CAG positive rates than TET negative group [ 15.9％ (39/245) ].ConclusionThe treadmill exercise test is valuable in noninvasive diagnosis of CHD.The severity of CAG can be preliminarily estimated by analyzing the pattern of the change of different parts of electrocardiogram

BACKGROUND:The physical properties and chemical composition of teeth are very similar with human bone tissue, and there are a larger proportion of inorganic components. Therefore, tooth can be considered as a potential repair material for autologous or alogeneic bone defects. OBJECTIVE:To prepare polyetheretherketone/odontogenic biphasic bioceramic composite, and to test its mechanical properties. METHODS: The humanin vitro teeth of clinical waste were colected. The organic components were removed after a preliminary calcination. Another calcination was conducted after soaking in diammonium phosphate solution for 24 hours to prepare the biphasic ceramics with the main components of hydroxyapatite and β-tricalcium phosphate. The biphasic ceramics were ground and sieved using 200-mesh sieve folowed by impregnation in organic foam to prepare polyetheretherketone/odontogenic biphasic bioceramics. Phase analysis, scanning electron microscopy, elemental analysis, porosity, compressive strength and bond strength test were conducted. RESULTS AND CONCLUSION:Polyetheretherketone/odontogenic biphasic bioceramics presented porous network structure and interconnected holes, with the aperture of 100-800 μm, porosity of 73.65%, compressive strength of (165.260±11.703) N, bond strength of (14.63±6.21) MPa. P element content accounted for 19.8%, and Ca element content accounted for 40.5%. The main phases were β- tricalcium phosphate and hydroxyapatite. These results demonstrate that polyetheretherketone/odontogenic biphasic bioceramics have good mechanical properties.

Objective: To establish a method for determining the molecular weight and molecular weight distribution of Poly(Lactide-co-Glycolide Acid) (PLGA) using Size Exclusion Chromatography-Refractive Index-Multiangle Laser Light Scattering (SEC-RI-MALLS) and Size Exclusion Chromatography-Refractive Index (SEC-RID), and to compare the results obtained from these two methods.
Methods: For SEC-RI-MALLS, tetrahydrofuran was used as the mobile phase, Shodex GPC KF-803L was employed as the chromatographic column with a flow rate of 1 mL·min^-1, column temperature at 30 ℃, and an injection volume of 100 μL. For SEC-RID, tetrahydrofuran was also used as the mobile phase, Agilent PLgel 5 μm MIXD-D was used as the chromatographic column with a flow rate of 1 mL·min^-1, column temperature at 30 ℃, differential detector temperature at 35 ℃, and an injection volume of 20 μL. The molecular weight and molecular weight distribution were calculated using Agilent’s GPC software. The newly established methods were validated methodologically, and the molecular weight and molecular weight distribution of 13 batches of samples were determined.
Results: The precision, accuracy, stability, and repeatability tests for SEC-RI-MALLS showed RSD values of 1.35%, 1.58%, 1.53%, and 1.26%, respectively. The SEC-RID method exhibited good linearity (r=0.999 9), with RSD values for precision, accuracy, stability, and repeatability tests (n=6) of 2.05%, 1.62%, 1.30%, and 2.97%, respectively. The results obtained from SEC-RI-MALLS were lower than those from SEC-RID, and the molecular weight distribution coefficient was smaller, but the results from the paired T-test performed with the value measured by SEC-RID method and the value measured by SEC-RI-MALLS method multiplied a conversion coefficient of 1.5 showed no significant difference between the two methods.
Conclusion: Both methods are stable and reliable, and can be used for the determination of PLGA molecular weight and molecular weight distribution based on the specific situations.