基于MRI的成人正常膝关节软骨形态学测量

目的：了解正常膝关节软骨分布及股骨髁承重区的软骨厚度特点,为膝关节病变早期诊断和动态观察提供依据。方法：选取100名成人志愿者,男、女各50名,年龄20—30岁,平均25．3岁,膝关节均行MRI扫描。应用MIMICS软件对图像进行处理,在矢状位窗面上测量膝关节各部位软骨最大厚度。选择膝关节正常运动时的承重区,测量承重区域软骨的最大厚度并与其他区域进行比较。基于MRI图像行膝关节软骨三维重建,观察膝关节软骨的三维形态特征。结果：膝关节各部位的最大软骨厚度如下。胫骨外侧平台3．19mm,胫骨内侧平台3．07mm,股骨外侧髁2．93mm,股骨内侧髁3．19mm,股骨滑车软骨3．57mm,髌软骨3．75mm。不同性别与左右侧之间的软骨厚度差异无统计学意义（P〉0．05）。胫股关节承重区软骨厚度大于其他区域,有统计学差异（P〈0．05）。结论：成人正常膝关节各区域软骨厚度不同,胫股关节承重区软骨厚度大于非承重区域。基于MRI可以准确地测量膝关节各部软骨的厚度及重建膝关节软骨的三维形态。     

Clinical risk factors related to failures with zirconia-based restorations: An up to 9-year retrospective study

Objectives

The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis.

Methods

147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n = 46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique.

Results

The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan–Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p = 0.0048), the presence of a ceramic restoration as an antagonist (p = 0.013), the presence of parafunctional activity (p = 0.018), and the presence of implants as support (p = 0.026). The implant abutments success rate was 100%.

Conclusions

The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies.

Clinical significance

Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate.     

GC护牙素在固定正畸中预防釉质脱矿的临床研究

目的观察固定正畸矫治中GC护牙素预防牙釉质脱矿的临床效果。方法选择固定矫治器治疗的患者64名,随机分为2组,护牙素组32例,657颗牙;对照组32例,678颗牙。矫治结束后对牙面脱矿情况进行临床观察,用SPSS13.0统计软件进行数据处理分析。结果矫治前二组患者被观察牙齿牙釉质脱矿率和脱矿程度均无明显差异(P>0.05)。矫治后护牙素组牙釉质脱矿率为5.78%,对照组为15.78%。护牙素处理组牙釉质脱矿率和脱矿程度明显低于对照组,有显著性差异(P<0.01)。结论在固定正畸治疗中配合使用GC护牙素处理牙面,可预防牙釉质脱矿的发生。     

Experimental and Analytical Performance Evaluation of Short Circular Hydrodynamic Journal Bearings Used in Rotary Blood Pumps

Rotary blood pumps (RBPs) have demonstrated considerable promise while treating heart failure patients, such that they are being placed at an earlier stage of the disease. These devices may therefore be required to operate for prolonged durations which yields the need for RBPs exhibiting high durability, reliability, and blood compatibility. Noncontacting bearings, utilizing magnetic and/or hydrodynamic suspension techniques, appear to provide a suitable solution to these challenges. Hydrodynamic suspension has the advantage that it does not need feedback control systems. Among various hydrodynamic bearing types, the circular journal bearing has the particular benefit of easy manufacturing. This study presents methods to evaluate the performance of short (length to diameter ratio <1) circular hydrodynamic journal bearings (HJBs) for RBPs. Analytical calculations with specific boundary conditions are presented to predict the rotor's eccentricity under equilibrium states and thus the related performance parameters such as load capacity, power loss, and shear rates. These results and boundary conditions were confirmed experimentally in a specially designed test set‐up. The bearing performance was found to correlate to analytical solutions using the full Sommerfeld boundary condition instead of the half Sommerfeld condition conventionally used for such applications. Geometrical and operational parameter variations showed that HJB designs with a short Sommerfeld Number S_S >0.02 can provide sufficient fluid film thicknesses and low shear rates. The measurements were further used to evaluate the bearings' stability. The estimation of the stability threshold drawn in relation to a modified stability index and the equilibrium eccentricity of the rotor allows the prediction of stability for short circular HJB designs under full Sommerfeld condition.     

Efficacy of a fixed combination of ciclesonide and formoterol: the EXCITED-study

Recommended treatment for moderate to severe asthma is the combination of an inhaled corticosteroid and a long-acting beta2-agonist. The present study was designed to evaluate the efficacy of a newly developed fixed combination of ciclesonide and formoterol in comparison to the marketed fixed combination of fluticasone and salmeterol in patients with moderate asthma. This was a phase II, multi-centre, randomized, parallel-group, double-blind, double-dummy study. After a 2-week run-in period, 160 patients with moderate asthma were randomized to a 6-week treatment with ciclesonide/formoterol 320/9?μg bid (CIC/F) or fluticasone propionate/salmeterol 250/50?μg bid (FP/S), both delivered as powder formulations. The primary outcome FEV1 increased during treatment by 0.356?L in the CIC/F group and by 0.288?L in the FP/S group (p?相似文献   

模拟急诊结合TBL教学在颈椎损伤固定搬运术教学中的应用

【摘要】随着对运动性损伤的重视,颈椎损伤固定搬运术成为急诊医护人员必须熟练掌握的最基本及重要的急救技能之一,基于既往采用传统教学方法对医学生培训效果欠佳,为改善教学效果,顺应教学需求,结合前几年急救技能培训的经验,使用模拟急诊结合TBL (Team-Based Learning)教学模式进行颈椎损伤固定搬运术的教学,获得了良好的教学效果。     

Effect of Implant Design on Knee Flexion

From March 2006 to August 2008, 93 subjects (186 knees) underwent simultaneous bilateral total knee arthroplasty performed by eight surgeons at North American centers. This randomized study was conducted to determine whether non-weight-bearing passive flexion was superior for knees receiving a posterior stabilized high flexion device compared to a posterior stabilized standard device in the contra-lateral knee. Weight-bearing single leg active flexion was one secondary endpoint. Follow-up compliance was 92.5%. Results show small, but significant superiority in the motion metrics for the high flexion device compared to the standard device 12 months after surgery, especially for a subgroup of patients with pre-operative flexion less than 120° in both knees. Thus, the ideal candidate for the high flexion device may be one with lesser pre-operative flexion.     

Synthesis and preliminary evaluation of a 99mTc‐labeled folate‐PAMAM dendrimer for FR imaging

Folate receptor is an ideal target for tumor‐specific diagnostic and therapeutic. The aim of this study was to synthesize ^99mTc‐labeled folate‐polyamidoamine dendrimer modified with 2‐hydrazinonicotinic acid (^99mTc‐HP ₃FA ) for FR imaging. The ^99mTc‐HP ₃FA conjugate was prepared using N‐tris‐(hydroxymethyl)‐methylglycine and trisodium triphenylphosphine‐3,3′,3″‐trisulfonate as coligands. Physicochemical properties, in vitro cell uptake study, and in vivo micro‐single‐photon emission computed tomography/CT imaging were performed. The radiolabeled ^99mTc‐HP ₃FA conjugate was prepared with high radiolabeling yield, good stability, and water solubility (logP  = ?1.70 ± 0.21). In cell uptake study, the radiolabeled conjugate showed high uptakes in the FR ‐abundant KB cells and could be blocked significantly by excess folic acid. The 7721 cells which served as control group substantially had no uptakes. The results of micro‐single‐photon emission computed tomography/CT imaging exhibited that high accumulation of activity was found in FR ‐overexpressed KB tumor, and the tumor‐to‐muscle ratio was approximately 25.78, while, using free FA as inhibitor, the uptakes of ^99mTc‐HP ₃FA in KB tumor and kidney were obviously inhibited. In summary, a new radiocompound was synthesized successfully with specific FR targeting ability. The feasibility of ^99mTc‐HP ₃FA for early diagnosis of FR ‐positive tumors with non‐invasive single‐photon emission computed tomography imaging was demonstrated and the possibility of imaging‐guided drug delivery based on multifunctional polyamidoamine will be studied in the future.