Large-Scale Production of 3D Bioactive Glass Macroporous Scaffolds for Tissue Engineering

For tissue engineering applications, a scaffold is required that can act as a template and guide for cell proliferation, cell differentiation and tissue growth. Interconnected pores with diameters greater than 100 m are required for tissue ingrowth, vascularisation and nutrient delivery to the centre of the scaffold. 3D bioactive glass scaffolds have been produced, by foaming sol-gel derived bioactive glasses. The method to produce foams with a modal macropore diameter of 100 m, and a handling strength suitable for cell culture, was to foam 50 ml batches of sol with the aid of a surfactant and gelling agent. In vitro and in vivo tests show that the scaffolds have high potential to be used in bone tissue engineering applications. Larger batches are required to produce scaffolds commercially. The aim of this work was to investigate how the process could be up-scaled for commercial use. This study shows that foaming larger aliquots of sol decreased the scaffold porosity and interconnectivity and investigates methods of modifying the process to obtain large quantities of foam scaffolds with pores in excess of 100 m. The optimum method to produce foams of similar pore structure from 200 ml sol to those produced from 50 ml sol comprised of adding 3 ml surfactant and 12 ml dionised water to the sol to start foaming and injecting a gas mixture (70% helium, 30% nitrogen) at 0.2 bar while applying vigorous agitation.     

用于细胞及组织培养的中等强度LED生物光源

研制出可用于细胞及组织培养的中等强度发光二极管光源,介绍了光源的光路原理和简要结构,测试了该光源的辐射照度及其强度分布,使用统计分析软件SPSS拟合得到该光源的辐射照度经验公式。     

Polystyrene Microspheres in Tissue-Simulating Phantoms Can Collisionally Quench Fluorescence

Tissue-simulating phantoms that replicate intrinsic optical properties in a controlled manner are useful for quantitative studies of photon transport in turbid biological media. In such phantoms, polystyrene microspheres are often used to simulate tissue optical scattering. Here, we report that using polystyrene microspheres in fluorescent tissue-simulating phantoms can reduce fluorophore quantum yield via collisional quenching. Fluorescence lifetime spectroscopy was employed to characterize quenching in phantoms consisting of a fluorescein dye and polystyrene microspheres (scattering coefficients _s 100-600cm^–1). For this range of tissue-simulating phantoms, analysis using the Stern-Volmer equation revealed that collisional quenching by polystyrene microspheres accounted for a decrease in fluorescence intensity of 6-17% relative to the intrinsic intensity value when no microspheres (quenchers) were present. The intensity decrease from quenching is independent of additional, anticipated losses arising from optical scattering associated with the microspheres. These results suggest that quantitative fluorescence measurements in studies employing such phantoms may be influenced by collisional quenching.     

Mie理论在生物组织散射特性分析中的应用

根据等效颗粒散射模型，运用经典的Mie理论，对生物组织的散射相函数、各向异性因子及散射系数进行了数值计算.计算结果表明：可见光照射生物组织时，各向异性因子、散射系数随等效颗粒直径增大而增大；等效颗粒直径较小时，各向异性因子、散射系数随入射光波长增大而单调减小；随着等效颗粒直径增大，各向异性因子、散射系数随入射光波长变化不再具有单调性.上述计算结果可合理解释公布的实验结果. 关键词： 生物组织 散射 Mie理论 等效颗粒     

胃粘膜组织共焦显微拉曼光谱分类研究

采用基于小波变换的光谱去噪和背景扣除预处理技术,对32例(其中:13例正常,19例癌变)胃粘膜组织拉曼光谱进行分析,克服了手动背景扣除的一些缺点,并观察到一些新的光谱特征。基于此,给出能对所有正常组织和癌变组织进行有效分类的特征量和判据。通过研究这些特征量与胃粘膜组织癌变发展阶段之间的定量关系,可望实现胃癌的早期诊断。     

Sensitive liquid chromatography/tandem mass spectrometry method for the determination of two novel highly lipophilic anticancer drug candidates in rat plasma and tissues

A simple and sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC‐ESI‐MS/MS) method was developed and validated for determination of two highly lipophilic anticancer drug candidates, LG1980 and GH501, in rat plasma and tissues (liver, kidney and femur bones). LG1980 and GH501 were extracted from rat plasma and tissue homogenates using liquid–liquid extraction. The method provided a linear range of 1.0–200.0 ng/mL for GH501 in plasma and LG1980 in plasma and liver. For both analytes in other tissue homogenates the linear range was 2.0–400.0 ng/mL. The method was validated with precision within 15% relative standard deviation, accuracy within 15% relative error and a consistent recovery. This method has been successfully applied in two preclinical studies for LG1980 and GH501 to determine their concentrations in rat plasma, liver, kidney and bone over 24 h after intravenous injection of compounds.     

Nanosecond Time-Gated Spectroscopy of Laser-Ablation Plume of Human Hair to Detect Calcium for Potential Diagnoses

We demonstrate the nanosecond time-gated spectroscopy of plume luminescence in UV laser ablation of human hair. Clear and sharp peaks of calcium ion (Ca⁺) appear in the spectrum although the Ca content is only 0.1% in human hair. Highly sensitive detection of Ca is thus possible. In the experiment, the peak intensity of Ca⁺ was measured for human hair samples of female subjects over a wide range of age, and compared to the bone mineral density of the lumbar vertebrae of the subjects themselves. Our experimental results suggest that this specific spectroscopy has the potential for novel diagnoses including monitoring of daily Ca intake and a screening diagnosis of osteoporosis. The spectroscopic system and time transition of plume-luminescence spectra are also described.     

The Effect of Blood Contained in the Samples on the Metabolomic Profile of Mouse Brain Tissue: A Study by NMR Spectroscopy

(1) Recently, metabolic profiling of the tissue in the native state or extracts of its metabolites has become increasingly important in the field of metabolomics. An important factor, in this case, is the presence of blood in a tissue sample, which can potentially lead to a change in the concentration of tissue metabolites and, as a result, distortion of experimental data and their interpretation. (2) In this paper, the metabolomic profiling based on NMR spectroscopy was performed to determine the effect of blood contained in the studied samples of brain tissue on their metabolomic profile. We used 13 male laboratory CD-1^® IGS mice for this study. The animals were divided into two groups. The first group of animals (n = 7) was subjected to the perfusion procedure, and the second group of animals (n = 6) was not perfused. The brain tissues of the animals were homogenized, and the metabolite fraction was extracted with a water/methanol/chloroform solution. Samples were studied by high-frequency ¹H-NMR spectroscopy with subsequent statistical data analysis. The group comparison was performed with the use of the Student’s test. We identified 36 metabolites in the brain tissue with the use of NMR spectroscopy. (3) For the major set of studied metabolites, no significant differences were found in the brain tissue metabolite concentrations in the native state and after the blood removal procedure. (4) Thus, it was shown that the presence of blood does not have a significant effect on the metabolomic profile of the brain in animals without pathologies.     

A pseudo active kinematic constraint for a biological living soft tissue: An effect of the collagen network

Recent studies in mammalian hearts show that left ventricular wall thickening is an important mechanism for systolic ejection, and that during contraction the cardiac muscle develops significant stresses in the muscular cross-fiber direction. We suggested that the collagen network surrounding the muscular fibers could account for these mechanical behaviors. To test this hypothesis we develop a model for large deformation response of active, incompressible, nonlinear elastic and transversely isotropic living soft tissue (such as cardiac or arteries tissues) in which we include a coupling effect between the connective tissue and the muscular fibers. Then, a three-dimensional finite element formulation including this internal pseudo-active kinematic constraint is derived. Analytical and finite element solutions are in a very good agreement. The numerical results show this wall thickening effect with an order of magnitude compatible with the experimental observations.     

Polyurethane vascular prostheses in pigs

Microporous, compliant vascular prostheses made from segmented polyurethanes of various molecular stability, have been implanted in the infrarenal aorta of young pigs. Prostheses prepared from a hydrolytically suble polyetherurethane showed a limited patency up to 1 month. Composite prostheses with the wall made from a hydrolytically stable polyurethane and the lumen side prepared from a degradable polyurethane, were patent up to one year. A degradable layer of this composite prosthesis induced the growth of a neo-artery. Prostheses prepared from a degradable polyurethane alone, were substituted within 4 months with a functional neo-artery.Presented in part at the 17th International Biomaterials Symposium, San Diego, California, April 1985.