BACKGROUND: As the end product of lipid peroxidation, malondialdehyde (MDA) content can be used for assessment lipid peroxidation injury.Glutathione peroxidase (GSH-Px) acts as a free radical scavenger. Currently the effect of static magnetic field on the organism, whether positive or negative, has not been elucidated.OBJECTIVE: To study the effect of static magnetic field on anti-oxidation capacity of mouse hepatic tissues and its intensity dependence for producing such effects.DESIGN: A controlled comparative experiment.SETTING: Laboratories of Medical Physics and Biochemistry of Jiangsu University.MATERIALS: The experiment was conducted in the Laboratories of Medical Physics and Biochemistry of Jiangsu University from January to December 2003. Totally 30 mice of either sex weighing 18-20 g were selected and subjected to magnetic filed exposure using a self-designed ferrite magnet apparatus.METHODS: The mice were equally randomized into normal control group and 4 exposure groups exposed to magnetic field of (24.6±4.2) mT,(42.0±2.1) mT, (63.5±3.0) mT, and (85.1±2.9) mT, respectively. The mice in the 4 exposure groups were exposed to static magnetic field of the specified intensity for 2 hours twice a day, while those in the normal control group were subjected to the sham exposure apparatus without magnetic field at scheduled time points every day. After 15 days of exposure, the mice were sacrificed and the GSH-Px activity and the MDA content in the hepatic tissue were assayed.MAIN OUTCOME MEASURES: GSH-Px activity and MDA content in hepatic tissue of the mice.RESULTS: Thirty mice entered the final analysis without losses. MDA content in (24.6±4.2) mT and (42.0±2.1) mT groups were obviously lower than that in the normal control group [(12.70±0.53), (12.96±0.72), and (17.62±0.91) μmol/g, respectively, F=10.4, 9.89, P ＜ 0.01]. The GSH-Px activity in the hepatic tissue in (24.6±4.2) mT and (42.0±2.1) mT groups were obviously higher than that in the normal control group [(143.36±8.34),(150.69±12.00), (87.51±11.34) μkat/g, respectively, F=10.0, 11.3, P ＜ 0.01].CONCLUSION: Static magnetic field of appropriate intensity can lower MDA content and enhance the GSH-Px activity in the hepatic tissue of mice, and may also improve the activity of antioxidase and reduce the production of lipid peroxidation to diminish the consequent injuries and delay the aging process.

Objective:To analyse the stress distribution of the tooth and inlay with the restoration of resin,porcelain,gold alloy,co-balt chromium materials respectively.Methods:3-D finite element models of mandibular first molar with meiso-occlusal (class II) cavity and different inlays were established.Von-mises stress distribution on the tooth and inlay with vertical load and lingual load at 45°were analyzed.Results:After restoration peak stress of high elastic module materials and dental inlays was higher than that of the low elastic module material inlays,however,the restorations of the different elastic module materials had the similar stress distribution trend.The stress under of lateral load(lingual at 45°)to the teeth inlays was significantly higher than that under vertical load.Peak stress concentration of tooth was on the bottom of the cavity near the pulp chamber dentin;inlay peak stress distribution is mainly in its corresponding to the gingival wall.In the tooth tissues stress level of the contact surface of inlay restoration,the strength was as the fol-lowing:Composite resin inlay >ceramics inlay >the gold alloy ceramics inlay >cobalt chromium alloy inlay.The stress level of the inlay of the four kinds of inlay restoration materials was just opponent with the tooth tissues.Conclusion:Gingival wall is the weakest part of meiso-occlusal(class II)cavity inlay restoration,while near the pulp chamber at the bottom of the cavity is the weakest part of the tooth.Among the 4 materials Under the same load condition,composite resin inlay restoration has minimal tooth stress and uniform stress distribution,and can reduce the posibility of odontoschism and microleakage.

ABSTRACT:Objective To analyze the stress changes of tooth tissues in the medial-occlusal (Class Ⅱ)cavity restored with different kinds of inlay materials by the three-dimensional (3-D)finite element.Methods The inlay restored 3-D finite element model of medial-occlusal (Class Ⅱ)cavity was established by CBCT scanning method and reverse engineering software Mimics,Geomagic Studio,Pro/E5.0 software,and finite element analysis software. The Von-mises stress and change tendency of tooth tissues and four different kinds of inlay materials were compared after taking vertical loading and tongue 45°to loading.Results There were different stress levels of tooth tissues among different inlays of medial-occlusal (MO)Class Ⅱ cavity.The stress level of the cobalt chromium alloy inlay was the largest,the stress level of the gold alloy inlay was lower,and the stress level of the composite inlay was the lowest.Dental tissues stress distribution was similar for the four different restorative materials,and focused on hole bottom of dentin near the pulp in dentin.Conclusion Compared with ceramics,gold alloy and cobalt chromium inlay restoration,restoration with composite resin inlay can reduce the organization stress of the remaining tooth in the medial-occlusal (Class Ⅱ)cavity type.

Objective:To investigate the clinical features and associated influencing factors of cognitive impairment in middle-aged and elderly Chinese adult patients undergoing maintenance hemodialysis (HD).Methods:A cross-sectional study was conducted among HD patients from 11 centers in Beijing city from April 2017 to June 2017. A neuropsychological battery covering domains of attention/processing speed, executive function, memory, language, and visuospatial function was applied in cognitive function assessment. Patients were classified as normal cognitive function group and cognitive impairment group according to the fifth version of the diagnostic and statistical manual of mental disorders criteria (DSM-V). Multivariate binary logistic regression was used to analyze the independent influencing factors of cognitive impairment. Results:A total of 613 HD patients were included in the study, and the prevalence of cognitive impairment was 80.91% (496/613). Attention impairment (81.05%) and memory impairment (63.51%) were the most common impaired domains, and 79.23% was concomitant impairment across two or more cognitive domains among those with cognitive impairment. Compared with the patients in the normal cognitive function group, the patients in the cognitive impairment group had senior age, longer dialysis vintage, higher proportion of diabetes, hypertension, and stroke, higher level of serum intact parathyroid hormone (iPTH), lower education level, and lower urea clearance index (Kt/V) (all P<0.05). Factors were independently associated with cognitive impairment including increasing age ( OR=1.110, 95% CI 1.072-1.150, P<0.001), education time>12 years (with education time<6 years as reference, OR=0.323, 95% CI 0.115-0.909, P=0.032), history of diabetes ( OR=2.151, 95% CI 1.272-3.636, P=0.004), history of stroke ( OR=2.546, 95% CI 1.244-5.210, P=0.011), increased dialysis vintage ( OR=1.016, 95% CI 1.010-1.022, P<0.001), reduced Kt/V( OR=0.008, 95% CI 0.002-0.035, P<0.001), and increased iPTH level ( OR=1.002, 95% CI 1.002-1.003, P=0.012). Conclusions:The prevalence of cognitive impairment in middle-aged and elderly adult Chinese patients undergoing HD is high. Memory and attention are the most commonly impaired domains. Increasing age, low education level, history of diabetes and stroke, increased dialysis vintage, reduced Kt/V and increased serum iPTH are the independent influencing factors associated with cognitive impairment.

Objective:To investigate the association between cognitive impairment and all-cause mortality in middle and elderly adult patients undergoing maintenance hemodialysis (HD).Methods:A prospective cohort study was conducted. Patients from 11 HD centers in Beijing between April and June 2017 were enrolled. Baseline data were collected, and a series of neuropsychological batteries covered 5 domains of cognitive function were applied for the assessment of cognitive function. The patients were then classified as normal and cognitive impairment groups according to the fifth version of the Diagnostic and Statistical Manual of Mental Disorders criteria (DSM-V) and followed-up until June 2018. The clinical characteristics of the two groups of patients were compared. Kaplan-Meier survival analysis was used to compare the difference in the cumulative survival rate between the two groups. Multivariate Cox regression model was used to analyze the independent influencing factors of all-cause mortality, to determine the relationship between cognitive impairment and different cognitive domain impairments and all-cause death.Results:A total of 613 patients were enrolled, of which 496(80.91%) patients had cognitive impairment. Compared with the normal cognitive function group, the patients in the cognitive impairment group tended to be older, longer dialysis vintage, a higher proportion of diabetes, hypertension, and stroke, increased serum iPTH level, and lower education level and urea clearance index (Kt/V) (all P<0.05). After (49.53±8.42) weeks of follow-up, Kaplan-Meier survival analysis showed that the cumulative survival rate of cognitive impairment group was significantly lower than that of cognitive normal group (Log-rank χ2=8.610, P=0.003). Multivariate Cox regression analysis showed that history of diabetes ( HR=2.742, 95% CI 1.598-4.723, P<0.001), coronary heart disease ( HR=1.906, 95% CI 1.169-3.108, P=0.010), dialysis vintage (every increase of 1 month, HR=1.007, 95% CI 1.003-1.011, P=0.001), serum level of albumin (every increase of 1 g/L, HR=0.859, 95% CI 0.809-0.912, P<0.001), cognitive impairment ( HR=2.719, 95% CI 1.088-6.194, P=0.032) were independently associated with all-cause mortality. Multivariate Cox regression analysis on different cognitive domains also indicated that memory impairment ( HR=2.571, 95% CI 1.442-4.584, P<0.001), executive function impairment ( HR=3.311, 95% CI 1.843-5.949, P=0.001) and three, four, five domains combined impairment ( HR=5.746, 95% CI 1.880-17.565, P=0.002; HR=12.420, 95% CI 3.690-41.802, P<0.001; HR=13.478, 95% CI 3.381-53.728, P<0.001) were independently related to all-cause mortality. Conclusions:Cognitive impairment is an independent risk factor of all-cause mortality in middle and elderly adult patients undergoing maintenance hemodialysis, and the risk is significantly increased in patients with the impairment of the domains of memory, executive function, or in the combination of three to five cognitive domains.