Incisional healing in rats treated with diethyl maleate

Diethyl maleate (DEM) which binds and thus depletes tissue glutathione levels was used to aggravate the injury and to determine its effect on incisional healing. A 5 cm dorsal midline skin incision was performed on 40 albino Wistar rats in two groups and then closed by interrupted sutures. Groups received 0.9% NaCl and DEM at a dosage of 1 mg/kg/day intraperitoneally for seven days, respectively. On postoperative days 7 and 14, histopathological assessment and tensile strengths were measured. The DEM treated group had a marked inflammation with poorly defined collagen formation and the tensile strength measurements revealed a significant decrease (p <0.001) on the 7t day. On the other hand, the first group showed better collagenization and a lesser degree of inflammation. However, on the 14th day, there was no noticeable histopathological difference between the two groups; but, tensile strength values of the second group were still lower (p <0.05). In this animal model, DEM postponed the healing process and reduced the tensile strength.     

N—酰化壳聚糖膜性能的研究

讨论了一系列N-酰化壳聚糖膜的抗张强度、透水性、VB_(12)的透过性、透氧性以及血液相容性。N-已酰化壳聚糖膜具有良好的血液相容性。在制膜过程中,加入分子量为1500的聚乙二醇为致孔剂,则可使N-己酰化壳聚糖膜的渗透性有较大提高。同时保持较好的血液相容性和强度。     

Laser welded vascular anastomosis

Summary A comparative study was undertaken to investigate the application of a specially adapted microsurgical Neodymium Yag Laser system with a wavelength of 1,319 m and a CO₂ laser system for laser assisted microvascular end-to-end anastomosis (LAMA) of the rat femoral artery. Conventionally sutured anastomoses served as controls. Postoperative investigations included patency tests, light microscopy and tensile strength measurements. Both laser systems seem to be equally suitable for LAMA: The patency rates do not differ from those of sutured anstomoses and formation of microscopically small aneurysms occurred predominantly in control animals and only once in laser groups. The clamp time needed for LAMA was half the time that was needed for sutured anastomoses. Wound healing in all groups was similar with less fibrotic reactions and less foreign body granulomas in laser groups. At all intervals tensile strength was significantly higher for sutured anastomoses while differences between the CO₂- and the ND: Yag-laser groups were not statistically significant. Potential applications in urology include microvascular anastomoses in erectile dysfunction, pediatric and reconstructive urology.Contains parts of a dissertation     

羟基磷灰石与骨界面抗张强度测试及扫描电镜观察

本文测试了孔隙率为１４％，孔径小于２μｍ的纯羟基磷灰石（ＨＡ）与兔胫骨皮质骨之间界面的抗张强度，２周时为０．７２ＭＰａ；４、８、１６周之间强度无明显差异平均为１．５ＭＰａ。扫描电镜观察表明，２周时拉伸断裂位于ＨＡ－骨界面，４周以后多在ＨＡ晶体颗粒之间。ＨＡ与骨生物适应性好，矿化组织可以直接沉着于ＨＡ表面或ＨＡ内部，近界面处的ＨＡ发生了一定的生物降解反应，且骨矿化与ＨＡ的降解可能达到某种平衡。     

人体肠道生物力学特性的研究

为探讨人体肠道的生物力学特性，采用电子拉伸机对人体肠道进行一维拉伸试验。结果表明，人体肠道应力-应变关系为指数函数关系。人体肠道各段的指数系数a值接近，但材料常数C有一定的差异，说明肠道各段应力-应变趋势是一致的。在一定应力下，肠道各段轴向与环向的相对伸长率是不同的，表明人体肠道具有各向异性的特性。在一定应变下，肠道各段的增量弹性模量不同，结肠增量弹性模量相对较小，因而更容易发生变形。本研究为肠道内窥镜机器人的研制提供了理论基础。     

人体寰椎横韧带拉伸性能的实验研究

目的：研究人体寰椎横韧带的拉伸性能。方法：新鲜寰椎标本８例,制备成拉伸试件,进行定速率单向拉伸至横韧带断裂。结果：寰椎横韧带平均最大载荷为３１１．６Ｎ,最大变形量为６．０ｍｍ,刚度为７２．９Ｎ／ｍｍ。结论：寰椎侧块间的分离超过６．０ｍｍ,就可存在横韧带断裂。     

Subcutaneous Tissue Mechanical Behavior is Linear and Viscoelastic Under Uniaxial Tension

Subcutaneous tissue is part of a bodywide network of “loose” connective tissue including interstitial connective tissues separating muscles and surrounding all nerves and blood vessels. Despite its ubiquitous presence in the body and its potential importance in a variety of therapies utilizing mechanical stretch, as well as normal movement and exercise, very little is known about loose connective tissue's biomechanical behavior. This study aimed to determine elastic and viscoelastic mechanical properties of ex-vivo rat subcutaneous tissue in uniaxial tension with incremental stress relaxation experiments. The elastic response of the tissue was linear, with instantaneous and equilibrium tensile moduli of 4.77 kPa and 2.75 kPa, respectively. Using a 5 parameter Maxwell solid model, material parameters μ₁ = 0.95 ± 0.24 Ns/m and μ₂ = 8.49 ± 2.42 Ns/m defined coefficients of viscosity related to time constants τ_1M = 3.83 ± 0.15 sec and τ_2M = 30.15 ± 3.16 sec, respectively. Using a continuous relaxation function, parameters C = 0.25 ± 0.12, τ_1C = 1.86 ± 0.34 sec, and τ_2C = 110.40 ± 25.59 sec defined the magnitude and frequency limits of the relaxation spectrum. This study provides baseline information for the stress-strain behaviors of subcutaneous connective tissue. Our results underscore the differences in mechanical behaviors between loose and high-load bearing connective tissues and suggest that loose connective tissues may function to transmit mechanical signals to and from the abundant fibroblasts, immune, vascular, and neural cells present within these tissues.     

常规消毒对ProTaper镍钛根管锉抗拉强度的影响

目的 探讨超声清洗时间和消毒灭菌频率对镍钛根管锉的抗拉性能的影响,以了解超声清洗和高温高压消毒灭菌法在镍钛根管锉灭菌中应用的安全性和可行性.方法 采用全新的ProTaper S2锉和F2锉各25支,分为5组:标准组(未处理)、对照组(未超声-高压灭菌)、A组(超声震荡50 min+高压灭菌5次)、B组(超声震荡100 min+高压灭菌10次)、C组(超声震荡150 min+高压灭菌15次),分别用万能测试仪对其进行抗拉伸强度的性能试验.结果 S2及F2的标准组之间的抗拉伸强度差异无统计学意义(P>0.05),提示样本间不存在差异性;经不同时间超声清洗及不同次数高温高压处理的S2镍钛锉抗拉伸强度测试结果显示:对照组、A组、B组、C组分别为(76.58±4.87)MPa、(71.00±5.39)MPa、(72.33±3.43)MPa、(66.81±4.08)MPa;F2镍钛锉抗拉伸强度结果分别为:(111.75±6.83)MPa、(110.46±3.88)MPa、(107.29±3.89)MPa、(94.53±6.61)MPa;A、B组与对照组的ProTaper S2锉和F2锉的抗拉强度差异均无统计学意义(P>0.05),即镍钛锉经超声震荡50 min+高压灭菌5次及超声震荡100 min+高压灭菌10次消毒后,其抗拉伸强度无明显影响;C组与对照组间差异存在统计学意义(P<0.05),即镍钛锉经超声震荡150 min+高压灭菌15次消毒后,对其抗拉伸强度有影响.结论 常规超声-高压灭菌消毒超过一定频率可能增加ProTaper系统镍钛根管锉折断可能性.     

In vitro characterisation of arterial stiffening: From the macro- to the nano-scale

Accurate measurement of the material properties of arterial tissue is important for better characterisation of diseases and the development of reliable computational models. There are a number of in vitro techniques that are applied to study the biomechanical properties of arterial tissue. This review article presents data obtained using tensile testing, nanoindentation, scanning acoustic microscopy (SAM) and atomic force microscopy (AFM). Each of these techniques provides material property information at a different spatial resolution and in many ways are complementary techniques. The lack of consensus in the literature with regard to the appropriate stress and strain definitions that should be used when reporting tensile testing data is also highlighted. The potential of higher spatial resolution techniques, which provide data at micro-scale (nanoindentation and SAM) and nano-scale (AFM) for application to the characterisation of human aortic tissue are discussed. Finally, studies, which have examined age-related changed in the aorta at these different length scales, are highlighted.