BACKGROUND: The physical property of porcelain fused to metal (PFM) differs from those of its constituents, which nake impacts on PFM,and the mechanical property of most composites can be estimated with mixture rule. However, there are various factors influencing the mechanical property of PFM and great differences found in the estimations, thus it is necessary to combine the theoretical analysis of mechanical property and mechanics of materials by matbematical models, and provide guidances for PFM' s application.OBJECTIVE: To explore the experiment and computing methods of mechanical analysis on PFM repair materials, and analyze its correlativity and internal relation.DESIGN: Three-point bending experiment and mixture rule of the composites were applied to measure and calculate the intensity and modulus of materials, and then the experimental results and computations were compared.SETTING: Repair Department of Stomatology, West China Stomatological College.MATERIALS: According to the different metal-porcelain ratios, 15 PFM test pieces of 26 mm×4 mm×1.5 mm were divided into 5 groups, with 3 in each.METHODS: Three-point bending experiment was used to detect the bending level and elastic modulus of PFM, whose changing rule was observed,and then was compared with theoretical computed value as well as study the correlation.MAIN OUTCOME MEASURES: PFM experimental result, theoretical computation and the comparison of the two,RESULTS: There were obvious correlations between the experimental measurement and theoretical results, which indicated that the mechanical property of PFM could be predicted by the revised formula.CONCLUSION: The mechanical property of PFM has regular relations with the geometrical morphous parameter and mechanical parameter of PFM constituents, and can be predicted and improved by revised theoretical formula.

Adult ; Aged ; Colon ; physiopathology ; Constipation ; drug therapy ; physiopathology ; Drug Combinations ; Drugs, Chinese Herbal ; therapeutic use ; Female ; Gastrointestinal Transit ; drug effects ; Humans ; Male ; Middle Aged ; Phytotherapy

Objective To study the mRNA expression of myelin basic protein (MBP) and myelin oligodendregha glyeoprotein (MOG) in hippocampus of rats following global brain ischemia.Method The four- vessel occlusion animal model in the Sprague-Dawley rats was used in this study.The mRNA expression levels of MBP and MOG in the hippocampus of rats were analyzed by reverse transcription polymerase chain reaction (RT- PCR) at day 2,4,7,14 and 28 days after global brain ischemia.There were eight rats at each time-point and sham operated group.Results The mRNA expression of both MBP and MOG in hippocampus of rats decreased at 2 days after global brain ischemia.The gene expression of myelin gene decreased significantly at 7 days and it reached to the lowest level at 28 days.Compared with sham operated group,the gene expression of MBP and MOG in hippocampus of rats decreased significantly at 7,14 and 28 days after global brain ischemia (P

Human leukemias are considered as clonal malignancies initiated at stage as early as hematopoietic stem/progenitor cells. The drug resistance and relapse are two major causes for treatment failure of leukemia. Recently, the discovery of leukemia stem/progenitor cells (LSPC) and subsequent research have provided a cue to elucidate the pathogenesis of leukemia and to explore the strategies of targeted therapy against LSPC. This review summarizes the molecular characteristics of LSPC and some research advances of therapy targeting LSPC including therapy targeting to surface molecules of LSPC, interference of interaction between LSPC and bone marrow microenvironment, regulation mechanisms of some specific molecular and so on.
Humans ; Leukemia ; therapy ; Neoplastic Stem Cells ; Stem Cell Transplantation

OBJECTIVETo analyze effects of fracture of processus styloideus ulnae on prognosis in the treatment of distal radial fracture of type C according to AO classification.

METHODSThis was a retrospective case-control study, and the information was got ten through case evaluation and follow-up, including sex, age, patient satisfaction, Gartland & Werley score and radiographic score. There were 76 patient treated with open reduction and plate fixation in People's Hospital Affiliated to Peking University from July 2006 to July 2011. All the patients were divided into two groups: no combination with fracture of processus styloideus ulnae (group A, 56 cases), combination with fracture of processus styloideus ulnae (group B, 20 cases). The patients in group A and B were treated with open reduction and internal fixation; however the fracture of processus styloideus ulnae was not fixed. The indexes such as clinical data, bone grafting, joint movement, Gartland & Werley score and radiographic score were compared between two groups.

RESULTSThe ulnaris pain of patients in group B was more obvious than that in group A. The local VAS, palmar and dorsal flexion degree of wrist joint, motion VAS, patients satisfaction score, radial and ulnar deviation degree, pronation and supination of forearm degree, Gartland & Werley score and radiographic score were separately 0.1 ± 0.1, (51.1 ± 1.9)°, (60.2 ± 1.9)°, 0.6 ± 0.1 (23.1 ± 0.9)°, (28.7 ± 1.3)° (81.5 ± 2.6)°, (68.2 ± 2.7)° 1.9 ± 0.3, 89.6 ± 12.3 in group A; and separately 0.3 ± 0.3, (51.4 ± 2.3)°, (66.6 ± 1.7)°, 0.5 ± 0.2, (24.5 ± 2.0)°, (26.9 ± 1.8)°, (80.3 ± 2.5)°, (70.3 ± 3.7)°, 1.2 ± 0.4, 92.5 ± 7.5 in group B; there were no statistical differences in above indexes between two groups.

CONCLUSIONWhether the distal radial fracture with a concomitant unrepaired ulnar styloid fracture or not exerts no influence on mainly outcomes including function, radiography and motion of the wrist.

Bone Plates ; Case-Control Studies ; Female ; Fracture Fixation, Internal ; methods ; Humans ; Male ; Middle Aged ; Prognosis ; Radius Fractures ; surgery ; Retrospective Studies ; Ulna Fractures ; surgery

Animals ; Herbicides ; poisoning ; Humans ; Paraquat ; poisoning

ObjectiveTo investigate the effects of 1-3-n-Butylphthalide on the blood-brain barrier (BBB) following whole brain irradiation in rats.Methods144 male Sprague Dawley rats were randomly divided into sham-irradiation group,irradiation group,1-3-n-Butylphthalide group,and irradiation plus 1-3-n-Butylphthalide group.Whole-brain irradiation was given as a single-dose of 10 Gy using 4 MV X-ray.The rats were injected intraperitoneally with 1-3-n-Butylphthalide at 0.3 mg/kg,1.0 mg/kg,3.0 mg/kg once per day.The changes of the BBB were assessed by Evans blue (EB) assay.The expression of vascular endothelial growth factor (VEGF) in the brain tissue was determined by immunohistochemistry. The circulating endothelial cells (CECs) isolated from right ventricular blood were counted.MRI was evaluated with the T1-weighted images,T2-weighted images and MRI enhancement images induced by Gd-DTPA.The data were compared among the groups through Student-Newman-Keuls test.ResultsCompared with the sham-irradiation group,the EB content,the expression of VEGF in the brain tissue and the CECs were significantly increased in the irradiation group (2.81∶ 7.82,P =0.002;5.83∶ 10.26,P=0.003;3.16∶6.14,P =0.002).The signal intensity of T1-weighted images was significantly decreased while T2-weighted images and the enhancement rate significantly increased in the irradiation group (P =0.004 -0.018 ).Compared with irradiation group,the EB content,the expression of VEGF and the CECs were decreased significantly in the irradiation plus 1-3-n-Butylphthalide group ( 7.80∶ 3.86,P =0.007 ; 10.83 ∶ 5.26,P =0.008 ;6.36∶ 3.64,P =0.009 ).However,the changes in the MRI were significantly attenuated ( P =0.008-0.026,and 0.006 -0.038,respectively).Conclusions Following whole brain irradiation,1-3-n-Butylphthalide can decrease the permeability of the BBB in rats via decreasing VEGF expression and decreasing the CECs.

Objective To explore the relationship between DNA repair gene XRCC1 and XPD polymorphisms and individual susceptibility to prostate cancer. Methods PCR-restriction fragment length polymorphism assay was used to analyze the XRCC1 (C26304T and G28152A) and XPD A35931C polymorphisms in 358 prostate cancer patients and 312 healthy controls. Unconditional logistic regression analysis was performed to calculate odd ratio (OR) and 95% confidence interval (CD for estimating the correlation between different genotypes and prostate cancer risks. Results Forty-seven(13.1%) cases present XRCC1 28152AA genotype in prostate cancer group, while 24 cases in the control group (7. 1%), individuals with this genotype had a significantly increased risk for prostate cancer (OR 1. 924, 95%CI=1.126 - 3. 288, P=0. 017). There was no significant difference between two groups at XRCC1 C26304T and XPD A35931C sites. Combined analysis of the three sites polymorphisms showed that individuals with XRCC1 28152 AA and XPD 35931AC+CC genotype had a higher risk of prostate cancer than those with three wild genotypes (OR = 3. 087,95%CI 1. 081 - 8.813;OR = 3. 376,95%CI 1.067-10.683;OR 3. 216,95%CI=1. 439-7.188,P = 0. 004). Analysis stratified by age of onset, PSA, Gleason score and T stage revealed that XRCC1 28152AA and XPD 35931 AC+CC high-risk genotype was especially associated with early age at onset of prostate cancer (P<0. 05). Conclusions The XRCC1 and XPD genotypes may be contributed to the risk of developing prostate cancer, particularly for younger patients.

Chemotherapy remains at the first line for the treatment of leukemia. However, the multi-drug resistance of the tumor cells caused by chemotherapeutic drugs has seriously affected the effect of chemotherapy. And this is the main reason for the failure of the leukemia treatment. Therefore, to explore an effective way of reversing drug resistance has become the key of leukemia treatment. RNA interference, a system within living cells, helps to determine which genes are active and how active they are. It is a process in which translation of some cell messenger RNA (mRNA) sequences is prevented, because of the presence of (and consequent destruction of) matching double-stranded RNA sequences. RNA interference is also called post-transcriptional gene silencing (PTGS), since its effect on gene expression occurs after the production of mRNA during transcription. It is believed that RNA interference can protect the cell against viruses and other threats. The greatest advantage of RNAi is the specificity and high efficiency which can induce suppression of specific genes of interest but the unrelated genes are not affected. The selective and robust effect of RNAi on gene expression makes it a valuable research tool both in cell culture and living organisms because synthetic dsRNA introduced into cells can induce the suppression of specific genes of interest. Nowadays, the technology has been widely used in biomedical fields, especially in the diagnosis and treatment of blood system disease. However, besides the stability, targeting and biological safety in genetics, the immune response induced by exogenous RNA is also one of the key factors to limit the clinical practice of this emerging technology. In this review, the breakthrough of the technology in multi-drug resistance reversal in leukemia is summarized with the RNA interference technology as a starting point.
Cell Line, Tumor ; Drug Resistance, Multiple ; genetics ; Drug Resistance, Neoplasm ; genetics ; Gene Silencing ; Humans ; Leukemia ; genetics ; therapy ; RNA Interference

In this study we compare the experimental and mathematical analyses of mechanical properties of PFM and analyze their correlation levels and inner links. Fifteen PFM specimens with different thickness ratio of metal to porcelain are made , with the shape of 26mm x 4mm x 1.5mm, and are divided into 5 groups, the metal thickness increases with 0.05mm change each among every group from 0.25mm to 0.45mm, the porcelain thickness decreases accordingly. The three-point-fracture test is used to measure their bending strength and elastic modulus, exhibit their changing laws, and disclose their inner relationships. When the whole thickness of the specimen is determined, the fracture load, bending strength and elastic modulus increase according to the increase of the metal thickness. The experimental mechanical properties of PFM are significantly influenced by the thickness ratio of metal to porcelain, and are the same as the theoretical ones calculated by the mixed law formula of compound material. There is significant correlation between the experimental analysis and mathematical analysis of mechanical properties of PFM. The regression coefficients can be obtained to describe this relationship. Further more, they can be used as the corrected parameters of the theoretical formula. The corrected mathematical formula is helpful to predicting and improving the mechanical properties of PFM.
Compressive Strength ; Dental Bonding ; Dental Porcelain ; Dental Stress Analysis ; Elasticity ; Materials Testing ; Metal Ceramic Alloys ; Models, Theoretical ; Tensile Strength