Polysaccharides and Their Derivatives for Versatile Tissue Engineering Application

Research and development in the design, synthesis, modification, evaluation, and characterization of polysaccharide‐based bioactive polymeric materials for guiding and promoting new tissue in‐growth is reviewed. Emphasis is given in this interdisciplinary field of tissue engineering (TE) with particular reference to bone, cartilage, and skin TE. Current strategies in scaffold‐guided TE approaches using polymers of natural origin and their composites are elaborated. Innovative modification techniques in creating functional materials for advanced TE applications are presented. Challenges and possible solutions in the technological innovation in factor molecules incorporation and surface functionalization for improving the fabrication of biomaterials scaffolds for cost‐effective TE are also presented.

     

A Simple,Scalable Process for the Production of Porous Polymer Microspheres by Ink‐Jetting Combined with Thermally Induced Phase Separation

Porous microspheres capable of delivering high payloads of biomolecules with suitable biodegradability and biocompatibility would be valuable in delivery systems to aid tissue regeneration. This study describes a facile, scalable technique to produce biodegradable porous microspheres by combining continuous ink‐jetting through a piezoelectric nozzle with thermally induced phase separation (TIPS). A selection of biomaterials is investigated to suit delivery in tissue engineering, the synthetic polyesters poly(lactic‐co‐glycolic acid) (PLGA), and poly caprolactone (PCL) and a natural polymer, gelatin. The parameters governing the microsphere production are determined experimentally and compared to theoretical predictions derived from the fluid mechanics and heat transfer during the ink‐jetting process. The microspheres produced have open interconnected pores with mean particle diameters of 80–200 μm and no significant skin region. The physical properties, such as the mean particle diameter, pore size, and surface area could be controlled by varying production parameters including the ink‐jetting pressure, nozzle height, and the size and oscillation frequency of the nozzle. The technique is demonstrated to successfully encapsulate a model hydrophobic molecule during microsphere production with uniform distribution. Porous PLGA microspheres are also used to achieve much higher adsorption capacities of a short peptide than non‐porous microspheres of the same material.     

火焰原子吸收法测鼠肺组织总钙

本文经十二烷基硫酸钠，十二烷基二甲基苄基溴化铵和壬基酚基聚氧乙烯醚复配而成的混合微乳液体系对鼠肺组织进行浸取前处理，用火焰原子吸收法测定了其中的钙含量。用混合微乳液法与溶液法进行了一系列对照试验，结果表明：在灵敏度、精密度、选择性、工作曲线线性方面均优于后者。检出限为１．９２ｎｇ·ｃｍ－３，相对标准偏差为１．９２％（ｎ＝１０），工作曲线线性范围０～２０μｇ·ｃｍ－３，线性回归系数ｒ＝０．９９９８，用于鼠肺组织中总钙的测定，结果与样品高温灰化法溶液ＦＡＡＳ结果一致。     

Short‐term effects of synchrotron irradiation on vasculature and tissue in healthy mouse brain

The purpose of this study is to measure the effects of a tomographic synchrotron irradiation on healthy mouse brain. The cerebral cortexes of healthy nude mice were irradiated with a monochromatic synchrotron beam of 79 keV at a dose of 15 Gy in accordance with a protocol of photoactivation of cisplatin previously tested in our laboratory. Forty‐eight hours, one week and one month after irradiation, the blood brain barrier (BBB) permeability was measured in the irradiated area with intravital multiphoton microscopy using fluorescent dyes with molecular weights of 4 and 70 kDa. Vascular parameters and gliosis were also assessed using quantitative immunohistochemistry. No extravasation of the fluorescent dyes was observed in the irradiated area at any measurement time (48 h, 1 week, 1 month). It appears that the BBB remains impermeable to molecules with a molecular weight of 4 kDa and above. The vascular density and vascular surface were unaffected by irradiation and no gliosis was induced. These findings suggest that a 15 Gy/79 keV synchrotron irradiation does not induce important damage on brain vasculature and tissue on the short term following irradiation.     

组织工程瓣的拉伸试验及力学参数的选取

一种全新的组织工程瓣膜的一维拉伸试验是研究其力学性能的基本方法。本文根据生物软组织粘弹性的理论和实验原理提出一维拉伸试验应包括预调、加载、卸载、定伸长下的应力松弛和断裂试验：确定了特征弹性模量E、变形恢复能力P、特征应力松弛速度R8、应力松弛的残值Ek、极限抗拉强度Tu和断裂伸长率λu作为特征参数。试图规范试验方法和试验参数的选取，以利于各种生物膜和组织工程瓣进行力学性能的相互比较。     

Determination of mercury in tuna fish tissue using isotope dilution-inductively coupled plasma mass spectrometry

Isotope dilution-inductively coupled plasma mass spectrometry (ID-ICP/MS) was applied to determine mercury in living tissue. Microwave digestion method using HNO₃/H₂O₂ media for the dissolution of solid sample was studied. The procedure for accurate determination of total mercury in tuna fish tissue sample by ID-ICP/MS is described. For the method validation, total Hg concentration in tuna fish CRM (BCR CRM 463) was determined by ID-ICP/MS after addition of ²⁰²Hg to CRM followed by acid decomposition of the spiked sample. This method was applied to the determination of Hg in tuna fish CCQM-P39 sample provided by IRMM (Institute for Reference Materials and Measurement, GEEL, Belgium) for the international comparison study.     

短穗柽柳幼苗形态解剖结构观察

柽柳（ＴａｍａｒｉｘＳｐｐ．）在荒漠的非河岸区自然侵移现象已被发现，本文试图通过对短穗柽柳（ＴａｍａｒｉｘＬａｘａ）幼苗在生长发育过程中形态解剖结构变化规律的研究，探讨柽柳在沙漠非河岸区自然侵移定居成功的内部形态的适应特征，幼苗自５月萌发至９月，叶面积由２．９１ｍｍ＾２减小到０．８０ｍｍ＾２，栅栏组织细胞排列由疏松到紧密，栅栏组织厚度由５４．５μｍ，增至８６．０μｍ，维管束／茎半径的比值由２５．３     

利用空间分辨漫反射无损测量生物组织的光学参量

利用空间分辨漫反射光确定生物组织的光学参量进行了实验研究，分别用光纤探测器和CCD无损测量了半无限大生物组织(牛脂肪和牛肉)表面的漫反射光的径向分布．由漫射方程对漫反射光强的相对分布值作非线性拟合确定了生物组织的吸收系数和约化散射系数，所得结果与国外报道的绝对测量法测量的结果相比，其差别小于9．4％．研究结果表明，光纤测量和CCD测量有较好的一致性，而CCD探测具有测量准确、简单和快捷的特点。     

时间分辨光谱法用于离体人肺鳞癌,腺癌及正常组织的荧光寿命测量

用Ｎｄ：ＹＡＧ倍频光５３２．０ｎｍ泵浦ＤＣＭ染料输出的６３２．８ｎｍ激光作激发源，通过时间分辨法测得离体人肺腺癌，鳞癌及正常组织的特征峰荧光寿命分别为５．１，５．６和６．３ｎｓ实验结果表明：肿瘤组织的荧光寿命总小于正常组织的荧光寿命，这种方法将有可能用于精确诊断和定位肿瘤。