Skin–textile friction and skin elasticity in young and aged persons

Background/purpose: The mechanical properties of human skin are known to change with ageing, rendering skin less resistant to friction and shear forces, as well as more vulnerable to wounds. Until now, only few and contradictory results on the age-dependent friction properties of skin have been reported. This study has investigated in detail the influence of age on the friction of human skin against textiles.
Methods: In vivo skin-friction measurements on a force plate were combined with skin analyses concerning elasticity, hydration, pH value and sebum content. Thirty-two young and 28 aged persons rubbed their volar forearm in a reciprocating motion against various textiles on the force plate, using defined normal loads and sliding velocities, representing clinically relevant contact conditions.
Results: Mean friction coefficients ranged from 0.30 ± 0.04 (polytetrafluoroethylene) to 0.43 ± 0.04 (cotton/polyester). No significant differences in the friction properties of skin were found between the age groups despite skin elasticity being significantly lower in the aged persons. Skin hydration was significantly higher in the elderly, whereas no significant differences were observed in either skin pH value or sebum content.
Conclusion: Adhesion is usually assumed to be the dominant factor in skin friction, but our observations imply that deformation is also an important factor in the friction of aged skin. In the elderly, lower skin elasticity and skin turgor are associated with more pronounced skin tissue displacements and greater shear forces during frictional contact, emphasizing the importance of friction reduction in wound-prevention programmes.     

乳腺囊实性病变的超声诊断现状及新技术应用进展

乳腺囊实性病变是乳腺囊性病变中较常见的类型，其中恶性病变较多。常规超声联合超声诊断新技术如超声弹性成像、超声造影及三维超声成像等可提高对于乳腺囊实性病变的诊断准确率。本文就常规超声联合新技术在乳腺囊实性病变中的应用进行综述。     

实时二维剪切波弹性成像评价急性肝衰竭大鼠肝脏硬度

目的 探讨实时二维剪切波弹性成像（2D-SWE）对于检测大鼠急性肝衰竭（ALF）和指导预防性用药治疗的应用价值。方法 将28只雄性SD大鼠分为4组，即对照组（8只）、模型组（8只）、乳果糖组（6只）和美常安组（6只）。实验第1~8天，对美常安组予以美常安稀释后灌胃，乳果糖组予以乳果糖灌胃，对照组和模型组予以等量生理盐水。实验第6、7天，对模型组、乳果糖组和美常安组大鼠均腹腔注射硫代乙酰胺，对照组注射生理盐水。实验第8天，采用2D-SWE技术测量4组大鼠肝脏硬度值（LSM）。构建ROC曲线，根据AUC选出准确率最高的LSM进行组间比较。实验第9天，取大鼠肝组织行病理检查。结果 模型组主要病理表现为炎症、坏死；美常安组及乳果糖组炎症坏死程度较模型组减轻；对照组表现为正常肝组织。根据模型组LSM构建的ROC曲线中，平均值诊断效能最佳；以8.44 kPa为截断值，其AUC、敏感度和特异度分别为0.768、100%和62.50%。模型组LSM较其他3组明显升高（P均<0.05）。结论 ALF大鼠LSM增高。2D-SWE对检测ALF及预防性用药后疗效评估具有一定价值。     

超声弹性成像技术评估卒中后痉挛研究进展

超声弹性成像（UE）为新型超声诊断技术，通过直接测量弹性模量反映肌肉硬度变化，近年来逐渐用于定量评估卒中后痉挛（PSS）程度及指导治疗PSS。本文对UE评估PSS研究进展进行综述。     

组织工程化骨修复材料的弹性模量测定及其临床意义

目的对组织工程化骨形成蛋白-脱钙骨基质颗粒-骨水泥复合材料进行弹性模量测定并探讨其临床意义。方法提取牛骨形成蛋白(bBMP)并进行成骨诱导活性测定,制备人的异体脱钙骨基质颗粒(DBM),将bBMP与DBM以1:25的质量比复合后,再与骨水泥(BC)按0:10,4:6,5:5,6:4和7.5:2.5的质量比进行复合,对所得的骨形成蛋白-脱钙骨基质颗粒-骨水泥复合材料进行弹性模量测定,并与正常人成年男性的股骨、股骨下端松质骨的弹性模量相比较。结果对测定结果进行统计学分析,含bBMP-DBM复合物75%的复合材料的弹性模量与正常成年男性股骨下端松质骨的弹性模量差异无显著性意义,P<0.01,其余各组两两比较均差异有显著性意义,P>0.01。结论含bBMP-DBM复合物75%的复合材料与成年男性股骨下端松质骨的弹性模量相接近,用其修复靠近关节面附近骨缺损可有效的防止关节的退行性变。     

Association of carotid arterial distensibility with Doppler indices of left ventricular filling in 50-year-old subjects

Doppler indices of left ventricular diastolic filling are associated with various cardiac and extracardiac factors. Afterload is one of the extracardiac factors influencing left ventricular diastolic filling. The distensibility of the great arteries is one of the components of afterload. In this study, the relation between Doppler indices of left ventricular filling and the distensibility of the common carotid arteries was investigated. We studied 237 subjects at 50 years of age with Doppler echocardiography and ultrasound examination of the common carotid arteries. The following Doppler indices of left ventricular filling were studied: peak early diastolic velocity E-wave, peak atrial diastolic velocity A-wave and early to atrial peak velocity ratio, E/A. Carotid arterial characteristics were: distensibility coefficient, carotid arterial diameter change in systole and fractional change in the carotid arterial diameter. The relation between Doppler indices of left ventricular filling and carotid arterial characteristics was assessed by univariate and multivariate regression analysis. There was a significant univariate, positive association between E/A ratio and carotid arterial distensibility (r = 0·27, P<0·001), carotid arterial systolic diameter change (r = 0·19, P<0·005) and fractional change of the carotid arterial diameter (r = 0·20, P<0·005). In multivariate analysis, E/A ratio was independently associated with carotid arterial distensibility (P<0·005), after adjusting for heart rate, body mass index and gender. Decreased carotid arterial distensibility was associated with a reduction in E/A ratio, suggesting that arterial distensibility may have an effect on left ventricular diastolic filling or that changes in the arterial elastic properties are associated with corresponding structural changes in the left ventricle.     

Silk fibroin scaffolds with muscle‐like elasticity support in vitro differentiation of human skeletal muscle cells

Human adult skeletal muscle has a limited ability to regenerate after injury and therapeutic options for volumetric muscle loss are few. Technologies to enhance regeneration of tissues generally rely upon bioscaffolds to mimic aspects of the tissue extracellular matrix (ECM). In the present study, silk fibroins from four Lepidoptera (silkworm) species engineered into three‐dimensional scaffolds were examined for their ability to support the differentiation of primary human skeletal muscle myoblasts. Human skeletal muscle myoblasts (HSMMs) adhered, spread and deposited extensive ECM on all the scaffolds, but immunofluorescence and quantitative polymerase chain reaction analysis of gene expression revealed that myotube formation occurred differently on the various scaffolds. Bombyx mori fibroin scaffolds supported formation of long, well‐aligned myotubes, whereas on Antheraea mylitta fibroin scaffolds the myotubes were thicker and shorter. Myotubes were oriented in two perpendicular layers on Antheraea assamensis scaffolds, and scaffolds of Philosamia/Samia ricini (S. ricini) fibroin poorly supported myotube formation. These differences were not caused by fibroin composition per se, as HSMMs adhered to, proliferated on and formed striated myotubes on all four fibroins presented as two‐dimensional fibroin films. The Young's modulus of A. mylitta and B. mori scaffolds mimicked that of normal skeletal muscle, but A. assamensis and S. ricini scaffolds were more flexible. The present study demonstrates that although myoblasts deposit matrix onto fibroin scaffolds and create a permissive environment for cell proliferation, a scaffold elasticity resembling that of normal muscle is required for optimal myotube length, alignment, and maturation. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd. StartCopTextStartCopText© 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.     

What economics can contribute to the addiction sciences

Aims The addiction sciences are intrinsically multi‐disciplinary, and economics is among the disciplines that offer useful perspectives on the complex behaviors surrounding substance abuse. This paper summarizes contributions economics has made in the past and could make in the future towards understanding how illegal markets operate, how prices affect use, how use generates various consequences, and how policy shapes all three. Methods Review of literature, concentrating on illegal drugs as insights concerning markets are particularly salient, although we also mention relevant studies from the alcohol and tobacco fields. Findings and Conclusions Economics offers tools and topical expertise that usefully complement other disciplines associated traditionally with the addiction sciences. Its value goes far beyond the ability to monetize non‐monetary outcomes or to calculate a cost‐benefit ratio.     

血管回声跟踪技术检测颈动脉弹性变化及主动脉瓣钙化与冠心病的相关性

目的 应用血管回声跟踪技术检测颈动脉弹性变化及二维超声观察主动脉瓣钙化,研究二者与冠状动脉粥样硬化关系及预测价值.方法 应用血管回声跟踪技术对196例行冠脉造影(CAG)受检者进行颈总动脉检查,记录血管弹性指标,包括弹性系数(Ep)、僵硬度(β)、顺应性(AC)、脉搏波传导速度(PWVβ).同时二维超声观察主动脉瓣有无钙化,并将上述结果与CAG结果进行t检验.结果 颈动脉弹性减退与冠脉病变的相关性:β、Ep与CHD呈正相关(r=0.281,r=0.253,P＜0.01,P＜0.05),AVC与CHD呈正相关(r=0.173,P＜0.05).结论 颈动脉弹性减退及主动脉瓣钙化是冠心病的高危因素,对冠心病有较大的预测价值. Abstract： Objective To study the relationship and predictive value of variation of carotid artery elasticity detected by echotracking (ET) technique and aortic valve calcification detected by two - dimensional ultrasonography with coronary heart disease (CHD). Methods The carotid artery elasticity of 196 cases who underwent coronary angiography(CAG) for suspected CHD were detected by echotracking (ET) technique and the indicators of artery elasticity were recorded, which includes elasticity modulus ( Ep), stiffness parameter ( β ), arterial compliance ( AC ) and pulse wave velocity ( PWVβ ).And aortic valve calcification was detected by two - dimensional ultrasonography, T test was carried out between the results of ultrasound examination and CAG. Results The indicators β, EP of carotid artery elasticity were positively correlated with the extent of CHD( r =0. 281,0.253; P ＜ 0.01, ＜ 0.05). In the mean time, positive correlation between aortic valve calcification and the extent of CHD was found (r = 0. 173, P ＜ 0.05). Conclusions Carotid artery elasticity reducing and AVC are high risk factors of CHD and have great values in predicting CHD.     

应用E-tracking技术评价妊娠期高血压疾病患者颈动脉弹性功能

目的：探讨E-Tracking技术在评价妊娠期高血压疾病患者颈动脉弹性功能中的应用价值。方法：对29例妊娠晚期妊娠期高血压疾病患者（疾病组）和32例正常妊娠晚期妇女（对照组）进行双侧颈总动脉血管弹性指标（弹性模量Ep、僵硬度β、顺应性AC、脉搏波传导速度PWVβ及膨大指数AI）及内中膜厚度（IMT）的测量,并进行统计学分析。结果：疾病组双侧颈总动脉Ep、β、PWVβ及AI较对照组升高,疾病组AC较对照组减低,具有极显著性差异（P〈0.01）;两组间颈总动脉内中膜厚度无显著性差异（P〉0.05）。结论：血管回声跟踪技术在评价妊娠期高血压疾病血管弹性方面具有一定价值。