Tissue 8

Tissue stress (TS) is defined as the stress which acts on atissue layer in an organ in excess of the turgor-induced tensilestress which also acts on the layer when it is isolated fromthe organ. The tensile TS in one layer of an organ is alwaysaccompanied by com-pressive TS in another layer. To calculateTS from data obtained for isolated tissue, one needs to knowthe Poisson ratios V_IKcontraction in the k-direction/extension in the i-direction for the tensile force applied in the i-direction for that tissue.Poisson ratios apply in the relationships between (i) tissueextensions caused by uniaxial stress (due to applied force)and multiaxial stress (due to turgor pressure); (ii) extensionsof tissues subjected to lateral constraint, and (iii) TSs indifferent directions. The ratios V_IW and V_WI, for the stressapplied either longitudinally (I) or in the direction of width(W), respectively, were determined for the outer tissue (OT)of sunflower hypocotyls, tulip leaves and tulip stems. The tworatios for a particular OT differed considerably. The ratiosdepended on the applied extension (strain). Knowing them, thetensile force (F₁) generating TS in the OT of an intact organcould be calculated from the longitudinal force (F_I(s)) whichwhen applied to the isolated (unconstrained laterally) OT restoredits original length. In the case of the sunflower hypocotyls,F_I(s)<F₁<1.3 F_I(s). The ratio V_Ir (r denotes the radialdirection), which was determined for segments of inner tissue,from sunflower hypocotyls and tulip stems, did not depend onthe applied stress (extension). This ratio allowed us to calculatethe relationship between the strain changes caused by equalchanges of uniaxial and multiaxial stresses: the uniaxial stresswas approximately 3-fold more efficient than the multiaxialstress. Key words: Elastic strains, Poisson ratios, tissue stresses, tissue elasticity, uni- and multiaxial stresses.     

组织芯片

组织芯片技术已广泛应用于人类基因组研究、医学诊断和基础研究,尤其是在肿瘤基因筛选、肿瘤抗原筛选及寻找与肿瘤发生、发展及预后相关的标记物等方面显示了巨大的潜能.组织芯片作为芯片家族的新成员,具有高通量、大样本、省时快速等优点.综述了组织芯片的制作方法、应用、优缺点及其发展前景.     

Tissue microarrays

The identification of disease-related genes is a major focus of modern biomedical research. Recent techniques, including array-based platforms for molecular profiling of disease tissues such as DNA arrays for expression profiling or matrix comparative genomic hybridization, allow for the comprehensive screening of the whole genome in a single experiment. Consequently, thousands of candidate genes have already been identified that may be linked to disease development and progression, and the process of lead discovery continues unimpeded. The evaluation of the clinical value of such leads is challenging because thousands of well-characterized tissue specimens must be analyzed. Tissue microarray (TMA) technology enables high-throughput tissue analyses to keep pace with the rapid process of lead discovery. With this technique, up to 1000 minute tissue samples are brought into an array format and analyzed simultaneously. The TMA technology is a fast, cost-effective, and statistically powerful method that will substantially facilitate translational research.     

Tissue 4

The finding that there are considerable tissue stresses (TSs)in the hypocotyl of Helianthus annuus L. prompts the question:how are the stresses generated? Here, a one-dimensional modelis formulated which, based on (i) symplastic, turgor-inducedextensions of tissues which differ in moduli of elasticity,and (ii) static equilibrium, predicts the occurrence of longitudinalTSs in stem-like organs, and gives their dependence on turgorpressure. To calculate the longitudinal forces which generatethe TSs in a stem, the moduli of elasticity of the tissues needto be known. The moduli were determined for uniaxial and multiaxialstresses for the outer tissue (OT) and the inner tissue (IT)of the hypocotyl. In the OT, the moduli were strongly dependenton applied uniaxial stress. The magnitudes of the calculatedlongitudinal forces (tensile and compressive) in the hypocotyl,were comparable to those measured. It follows that the TSs mayarise without differential growth of the tissues. Key words: Epidermis, model, moduli of elasticity, turgor, sunflower hypocotyl, tissue stresses     

Tissue 3

Carbon dioxide and ethylene evolution began to increase rapidlyafter 10 and 21 h respectively when banana fruit were inducedto ripen by treatment with propylene. At 36 h the soluble solidscontent of pulp tissue and the proportion of linolenic acidesterified to phospholipids extracted from pulp tissue increased.From 44 h onwards there was a progressive increase in pulp tissuepermeability, as measured by leakage of electrolytes. The causesof the increased electrolyte leakage are discussed, with referenceto the change in the proportion of linolenic acid and the increasein pulp soluble solids.