Endothelial cell VE-cadherin functions as a receptor for the beta15-42 sequence of fibrin

The contact of fibrin with the apical surface of human umbilical vein endothelial cells (HUVEC) can induce capillary tube formation via the interaction of fibrin beta15-42 with a putative cell receptor (Chalupowicz, D. G., Chowdhury, Z. A., Bach, T. L., Barsigian, C., and Martinez, J. (1995) J. Cell Biol. 130, 207-215). To characterize this interaction, we studied the binding of the thrombin-cleaved N-terminal disulfide knot of fibrin (NDSK II), a dimeric fragment with exposed beta15-42, to HUVEC in three separate assay systems. Time-course binding of 125I-NDSK II to HUVEC monolayers or suspensions revealed that binding was specific at 50-60%, as determined by the addition of unlabeled NDSK II. Specific binding of 125I-NDSK II to HUVEC was 70% reversible by dilution or by competition, and was found to be divalent cation-independent. Binding plateaued after 10 min at a saturation of 15-20 nM. Scatchard analysis using the LIGAND computer program defined a single population of receptors with a KD of 7.7 +/- 1.6 nM and approximately 21,000 +/- 7000 binding sites/cell. N-terminal disulfide knot derivatives in which beta15-42 was absent (NDSK 325) or unexposed (NDSK, NDSK I) did not show specific binding. Specific binding of 125I-NDSK II could not be inhibited by RGDS or by antibodies to the alphavbeta3 or beta1 integrins, PECAM-1, ICAM-1, or N-cadherin. In contrast, a synthetic beta15-42/ovalbumin conjugate inhibited total 125I-NDSK II binding by 47 +/- 19% (corresponding to 95% of specific 125I-NDSK II bound) and a monoclonal antibody to vascular endothelial cadherin (VE-cadherin) inhibited binding by 35 +/- 8% (corresponding to 70% of specific 125I-NDSK II bound). Another assay was based on the capture of cadherins from HUVEC lysates by a polyclonal pan-cadherin antibody immobilized on plastic dishes. Binding of NDSK II to the captured cadherins was 89 +/- 5% specific, while specific binding of NDSK 325 and NDSK was negligible. An immortalized line of human adipose-derived microvascular endothelial cells, which express N-cadherin but not VE-cadherin, demonstrated no specific binding of NDSK II by the capture assay. These data define a novel interaction of fibrin with VE-cadherin, which is mediated by the fibrin N-terminal beta15-42 sequence, and may contribute to the mechanism through which fibrin induces angiogenesis.     

Monolithic integrated wavelength duplexer-receiver on InP

The monolithic integration of a detector stage comprising a photodiode and a field-effect transistor with a load resistor and a wavelength duplexer, realized in the GaInAsP/InP material system, is described. Design considerations, in particular for the wavelength duplexer, but for the complete chip as well, are reported, and details related to the realization of the device are given. Chips were mounted into housings and operated in a 1.3- mu m/1.55- mu m bidirectional transmission link. At 576 Mb/s and 10/sup -9/ bit error rate, the sensitivity of the module is -21 dBm, the intrinsic sensitivity of the receiver is -28 dBm, and the gain-bandwidth product for the lowest noise bias conditions is 3.8 GHz.<>     

Learning graphical models for stationary time series

Probabilistic graphical models can be extended to time series by considering probabilistic dependencies between entire time series. For stationary Gaussian time series, the graphical model semantics can be expressed naturally in the frequency domain, leading to interesting families of structured time series models that are complementary to families defined in the time domain. In this paper, we present an algorithm to learn the structure from data for directed graphical models for stationary Gaussian time series. We describe an algorithm for efficient forecasting for stationary Gaussian time series whose spectral densities factorize in a graphical model. We also explore the relationships between graphical model structure and sparsity, comparing and contrasting the notions of sparsity in the time domain and the frequency domain. Finally, we show how to make use of Mercer kernels in this setting, allowing our ideas to be extended to nonlinear models.     

Energy values of non-starch polysaccharides: comparative studies in humans and rats

Energy values of non-starch polysaccharides (NSP) were estimated from NSP fermentability and from digestible energy balances in human subjects and in rats. During four studies, humans consumed four low fiber control diets and six high fiber diets. For the rat diets, duplicates of the foods consumed by humans were mixed together, freeze-dried and ground. Calculated from fermentability, partial digestible energy values of NSP in humans and rats, respectively, were 8.2 +/- 1.3 and 5.7 +/- 1.2 (P = 0.0013, fruits and vegetables), 11.4 +/- 0.7 and 5.7 +/- 3.2 (P = 0.0001, citrus fiber), 5.0 +/- 2.1 and 2.2 +/- 3.3 (P = 0.0429, barley fiber at high protein intake), 4.4 +/- 1.8 and 2.4 +/- 2.0 (P = 0.0561, barley fiber at low protein intake), 6.7 +/- 1.4 and 7.6 +/- 1.2 (P = 0.296, coarse whole meal rye bread), and 7.1 +/- 0.6 and 6.1 +/- 1.7 (P = 0.157, fine whole meal rye bread) kJ/g NSP. Calculated from energy balances, partial digestible energy values of NSP in humans and rats, respectively, were 2.1 +/- 3.5 and -5.0 +/- 4.0 (P = 0.026, fruits and vegetables), 10.7 +/- 5.1 and 1.4 +/- 5.6 (P = 0.003, citrus fiber), 1.6 +/- 5.1 and -17.8 +/- 8.6 (P = 0.0001, barley fiber at high protein intake), -2.6 +/- 4.9 and -9.3 +/- 8.2 (P = 0.044, barley fiber at low protein intake), -3.0 +/- 7.0 and 0.9 +/- 2.5 (P = 0.27, coarse whole meal rye bread), and 0.9 +/- 5.1 and 0.6 +/- 3.7 (P = 0.89, fine whole meal rye bread) kJ/g NSP. Net energy values were 70% of digestible energy values. Differences between species were significant for NSP in fruits and vegetables, citrus fiber, and barley fiber at high protein intake. Most energy values calculated from energy balances were significantly lower than values calculated from NSP fermentation, with differences being greater in rats than in humans. Thus, the energy values of some types of NSP contained in mixed diets could not be estimated accurately from NSP fermentability either in humans or rats. In addition, our results suggest that the rat is not always a suitable model of humans for predicting energy values of NSP in mixed diets.     

Good enough quality: beyond the buzzword

The big new force that is propelling the good enough idea is the explosion of market-driven software. With a passion roughly proportional to the price of Microsoft stock, companies are looking for the shortest path to better software, faster, and cheaper. They are willing to take risks, and they have little patience for the traditional moralistic arguments in favor of so-called good practices. Much of the traditional lore of software project management seems irrelevant or stilted when applied to market-driven projects. It's time that we developed approaches and methodologies that apply to the whole craft, not just to space missions, medical devices, or academic experiments. Good enough is a model that encompasses high-reliability products as well as high-entertainment products. Whether you call the idea good enough, or choose another buzzword like economical, pragmatic, or utilitarian, the basic idea remains the same: our behavior should be guided by reason, not compulsion. Beyond the notion of best practices is a more fundamental idea: best thinking. As the good enough idea continues to emerge, the quality of one's thinking, rather than conformance to formalities, will become the issue. Formalities, and the authority behind them, will be re-examined. No wonder so many authorities consider good enough to be a dangerous idea     

Fabrication and characterization of zirconia-toughened alumina obtained by inorganic and organic precursors

In zirconia-toughened alumina (ZTA) the martensitic transformation of zirconia (tetragonal→ monoclinic) is at the origin of toughening. If the zirconia particles have a mean grain size less thand’ _c, they remain tetragonal; if their size is betweend’ _c andd _c (d _c>d’ _c), they are stress-induced transformed into the monoclinic form; if their size is larger thand _c, particles are transformed. We prepared ZTA using different precursors and compared their microstructures. The coprecipitation of aluminium and zirconium chlorides gives an hydroxide mixture. Thus the zirconium hydrate is amorphous, and the aluminium hydroxide structure varies with the precipitation temperature and pH values at the end of the neutralization. Alumina is mixed with zirconia obtained by gas-phase reaction. Zirconia is prepared by vaporization of zirconium chloride in an oxygen-hydrogen flame. Alumina powder is impregnated by a zirconium acetate solution. Zirconium acetate is thermally decomposed in a spray-dryer, then by calcination. The cohydrolysis of II Al-butoxide and IV Zr-propoxide was carried out in an alkaline solution. The hydrolysis pH (10 or 12) changes the grain size of the oxide powders. Mechanical property measurements and microstructural analysis allow a comparison of the different composites. The mean grain-size evolution differs according to the preparative route, and may be varied by different elaboration parameters. Fine microstructures were always observed. The mean grain size of dispersed zirconia being very small (neard’ _c), we observed a little influence of transformation toughening. We noticed a large increase in rupture strength, while toughness was not noticeably improved.     

Lessons Learned from an Initial E-Commerce Failure by A Catalog Retailer

As companies rushed into E-commerce in the late 1990s, many predicted that existing catalog retailers would have a natural advantage over physical store retailers. However, confusing market signals and incorrect management assumptions led to some poor decisions. This article explores what went wrong with a successful catalog retailer, Fingerhut Inc., as it initially embraced E-commerce in the late 1990s, and some of the lessons learned.     

ISOLATION OF ASPHALTENES USING A CONTINUOUS PRECIPITATION METHOD

A new continuous method allows the isolation of heptane asphaltenes which are nearly identical to asphaltenes isolated by a well-studied batch method. Samples of one-half liter of atmospheric resid can be treated using one to two liters of n-heptane, while keeping heptane/resid ratios at 40:1. Asphaltenes precipitated by a well established batch method were identical within the errors of elemental and NMR characterization methods. Small amounts of colored, heptane-soluble materials can be extracted from samples prepared by the continuous technique, but this extraction does not change the analyses of the extracted solids.