Relating cell and tissue mechanics: Implications and applications

The Differential Adhesion Hypothesis (DAH) posits that differences in adhesion provide the driving force for morphogenetic processes. A manifestation of differential adhesion is tissue liquidity and a measure for it is tissue surface tension. In terms of this property, DAH correctly predicts global developmental tissue patterns. However, it provides little information on how these patterns arise from the movement and shape changes of cells. We provide strong qualitative and quantitative support for tissue liquidity both in true developmental context and in vitro assays. We follow the movement and characteristic shape changes of individual cells in the course of specific tissue rearrangements leading to liquid-like configurations. Finally, we relate the measurable tissue-liquid properties to molecular entities, whose direct determination under realistic three-dimensional culture conditions is not possible. Our findings confirm the usefulness of tissue liquidity and provide the scientific underpinning for a novel tissue engineering technology. Developmental Dynamics 237:2438-2449, 2008. (c) 2008 Wiley-Liss, Inc.     

Commodity durability, trader specialization, and market performance

The original double auction studies of supply and demand markets established their strong efficiency and equilibrium convergence behavior using economically unsophisticated and untrained subjects. The results were unexpected because all individual costs and values were private and dependent entirely on the market trading process to aggregate the dispersed information into socially desirable outcomes. The exchange environment, however, corresponded to that of perishable, and not re-traded goods in which participants were specialized as buyers or sellers. We report experiments in repeated single-period markets where tradability, and buyer-seller role specialization, is varied by imposing or relaxing a restriction on re-trade within each period. In re-trade markets scope is given to speculative motives unavailable where goods perish on purchase. We observe greatly increased trade volume and decreased efficiency but subject experience increases efficiency. Observed speculation slows convergence by impeding the process whereby individuals learn from the market whether their private circumstances lead them to specialize as buyers or sellers.     

3味中药对血瘀大鼠血液流动性和黏滞性的影响研究

目的：研究活血化瘀中药对血瘀大鼠血液流动性和黏滞性的影响,探讨其治疗冠心病心肌缺血的作用机制。方法：复制血瘀大鼠模型,以血液流变学、血小板聚集率、凝血酶原时间（PT）、部分凝血活酶时间（APTT）、纤维蛋白原（FIB）及红细胞压积为观测指标,以复方丹参片为平行对照,观察活血化瘀中药干预血瘀大鼠血液流动性和黏滞性的影响。结果：活血化瘀中药能显著降低血瘀大鼠的全血黏度（P〈0.01或P〈0.05）;能显著降低血瘀大鼠的血小板最大聚集率和纤维蛋白原含量,延长凝血酶原时间和部分凝血活酶时间（P〈0.05）;能显著降低血瘀大鼠的红细胞压积（P〈0.05）。结论：活血化瘀中药能改善冠脉血液的流动性和黏滞性,活血、祛瘀通络以促进血液的循环,增加心肌的供血供氧,保护缺血心肌。     

Fusion of uniluminal vascular spheroids: A model for assembly of blood vessels

Zebrafish Intrahepatic Biliary System: Confocal projection through the liver of a 5 day post‐fertilization zebrafish larva immunostained with antibodies raised against the human multidrug resistance protein‐1 (red), also known as Pglcyoprotein, an ABC transporter in the hepatocyte canalicular membrane, and a novel zebrafish epitope 2F11 (green) that recognizes biliary epithelial cells. Hepatocytes secrete bile through their canaliculus into the intrahepatic biliary duct network. 10 μm z‐stack. From Lorent et al., Developmental Dynamics 239:398‐406, 2010.     

The Lab: The Use of Microhematocrits

Due to the recent credit crisis and recession of 2008, hospitals experienced substantial losses in their investment portfolios. The author analyzed key financial accounts of 15 large, multistate healthcare systems that measured their changes in value of their investments, changes in net assets, liquidity ratios, and other performance ratios. Overall, he found that the majority of these systems did incur financial losses in their investment portfolios; however, for the majority of these systems, their liquidity and cash flow margin ratios declined slightly whereas their capital expenditure and community benefits increased.     

Effects of L.F04,the Active Fraction of Lycopus lucidus, on Erythrocytes Rheological Property

Lycopuslucidus(LycopusLucidusTurcz.Var.HirtusRegel)isaherbusedtraditionallyfor promotingbloodcirculationandremovingbloodstasis.Pharmacologicalresearchshowedthatitswaterpreparationcouldreducebloodviscosity(1), fibrinogencontentandhematocrit,shortenredbloodcells(RBC)electrophoresistime,andinhib itaggregationoferythrocytesandplatelets.Italsohaseffectsinresistingcoagulationandthrombo sis(2,3),improvingmicrocirculationandregulating bloodlipidmetabolism(4).Especially,asitcansignificantlyimprove…     

Stochastic control of credit default insurance for subprime residential mortgage‐backed securities

Subprime residential mortgage securitization and its associated risks have been a major topic of discussion since the onset of the mortgage crisis in July 2007. In this paper, we provide a stochastic dynamic model for investing bank profit under mortgage securitization. In addition, aspects of this model are illustrated by means of a numerical example. In addition, we solve a stochastic optimal credit default insurance problem that has the cash outflow rate for satisfying depositor obligations, the investment in structured mortgage products and credit default insurance as controls. As far as the latter is concerned, we compute credit default swap and accrued premiums by considering the credit rating of structured mortgage products such as residential mortgage‐backed securities and collateralized debt obligations. Copyright © 2011 John Wiley & Sons, Ltd.     

泽兰有效部分L.F04对红细胞流变学的影响

目的研究泽兰有效部分L .F0 4对红细胞流变学的影响 ,以探讨其活血化瘀作用机理。方法用高分子右旋糖酐静脉推注造成大鼠血瘀证动物模型 ,观察泽兰L .F0 4对红细胞变形性、聚集性和膜流动性的影响。结果高分子右旋糖酐造成了大鼠红细胞变形性降低 (P <0 .0 5 ) ,聚集性增高 (P <0 .0 1 ) ,膜流动性降低 (P <0 .0 5 )。与模型组相比 ,L .F0 4大 ( 0 .61 2 g/kg)、小 ( 0 .30 6g/kg)剂量明显改善了红细胞变形性(P <0 .0 5 ) ,抑制了红细胞聚集 (P <0 .0 5 ) ;对红细胞膜流动性有增加的趋势 ,但未呈现出量效关系。结论L .F0 4可显著改善血瘀动物异常的红细胞流变学指标。     

Effects of L. F04, the active fraction ofLycopus lucidus, on erythrocytes rheological property

Objective: To study the effects of L. F04, the active fraction of Lycopus lucidus, on erythrocytesrheological property so as to investigate its mechanism in promoting blood circulation and removing blood stasis. Method: The effects of L. F04 (used for treatment for 10 days in different dosages) on deformability, aggregation and membrane liquidity of erythrocytes (MLE) as well as whole blood apparent viscosity (ηb) were examined on the basis of rat model of blood-stasis syndrome induced by venous injection of high molecular weight dextran. Result: As compared with the normal control group, the model group''s RBC deformability and MLE were lower, and the aggregation of erythrocytes and ηb were higher. Compared with the model group, both L. F04 0. 612g/kg and 0. 306g/kg showed significant effect in improving deformability and inhibiting aggregation of red blood cells (RBC) and reducing blood viscosity. The trend of improving MLE was also shown. Conclusion:L. F04 could significantly improve the abnormal rheological property of erythrocytes.