Islet isolation assessment in man and large animals

Recent progress in islet isolation from the pancreas of large mammals including man, accentuated the need for the development of precise and reproducible techniques to assess islet yield. In this report both quantitative and qualitative criteria for islet isolation assessment were discussed, the main topics being the determination of number, volume, purity, morphologic integrity and in vitro and in vivo function tests of the final islet preparations. It has been recommended that dithizone should be used as a specific stain for immediate detection of islet tissue making it possible to estimate both the total number of islets (dividing them into classes of 50 μ diameter range increments) and the purity of the final preparation. Appropriate morphological assessment should include confirmation of islet identification, assessment of the morphological integrity and of the purity of the islet preparation. The use of fluorometric inclusion and exclusion dyes together have been suggested as a viability assay to simultaneously quantitate the proportion of cells that are intact or damaged. Perifusion of islets with glucose provides a dynamic profile of glucose-mediated insulin release and of the ability of the cells to down regulate insulin secretion after the glycemic challenge is interrupted. Although perifusion data provides a useful guide to islet viability the quantity and kinetics of insulin release do not necessarily predict islet performance after implantation. Therefore, the ultimate test of islet viability is their function after transplantation into a diabetic recipient. For this reason, in vivo models of transplantation of an aliquot of the final islet preparation into diabetic nude (athymic) rodents have been suggested. We hope that these general guidelines will be of assistance to standardize the assessment of islet isolations, making it possible to better interpret and compare procedures from different centers. © 1990 Casa Editrice il Ponte

Antioxidant treatment enhances human mesenchymal stem cell anti-stress ability and therapeutic efficacy in an acute liver failure model

published_or_final_versio

Effect of Sucrose Esters on the Physicochemical Properties of Wheat Starch

Purpose: To investigate the effect of sucrose esters on the physicochemical properties of wheat starch.Methods: Sucrose ester was mixed with wheat starch extracted from normal soft wheat cultivars and heated. Change in starch properties arising from the interaction between were assessed for starch blue value, viscosity, solubility and retrogradation. In addition, the structure and thermodynamic properties of the modified starch were analyzed by Fourier transform infrared spectroscopy (FITR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC).Results: The properties of wheat starch changed greatly by adding different sucrose esters to their structures. Starch containing 0.30 % sucrose esters had the lowest peak (2034 cps), trough (1331 cps), final (1896 cps), setback viscosities (565 cps), iodine value (0.378), supernatant volume (76.6mL), and lower dissolution rate (0.063g). The unmodified starch had higher peak (3576 cps), trough (2971 cps), final (4394 cps), setback viscosities (1423 cps), blue value (0.464), supernatant volume (85.4 mL ), and dissolution rate ( 0.076 g). After adding sucrose esters, the onset temperature (To) and peak temperature (Tp) of wheat starches increased by 1 - 5 °C and 1 - 3 °C, respectively; the conclusion temperature (Tc) and enthalpy, however, decreased by 5 - 6°C and 0.2 - 1.9 J/g, respectively. SEM and FT-IR showed that the microstructure and molecular structure of the starches with sucrose esters did not differ significantly from that of the unmodified starch.Conclusion: Incorporation of small amounts of sucrose ester in the structure of wheat starch can change the physicochemical properties of the starch to meet various functional requirements, including in the food and pharmaceutical industries.Keywords: Sucrose esters, Wheat starch, Viscosity, Microscopy; Microstructure, Differential scanning calorimetry, Fourier transform infrared spectroscopy

Automated data analysis to rapidly derive and communicate ecological insights from satellite-tag data: A case study of reintroduced red kites

Analysis of satellite-telemetry data mostly occurs long after it has been collected, due to the time and effort needed to collate and interpret such material. Such delayed reporting does reduce the usefulness of such data for nature conservation when timely information about animal movements is required. To counter this problem we present a novel approach which combines automated analysis of satellite-telemetry data with rapid communication of insights derived from such data. A relatively simple algorithm (comprising speed of movement and turning angle calculated from fixes), allowed instantaneous detection of excursions away from settlement areas and automated calculation of home ranges on the remaining data Automating the detection of both excursions and home range calculations enabled us to disseminate ecological insights from satellite-tag data instantaneously through a dedicated web portal to inform conservationists and wider audiences. We recommend automated analysis, interpretation and communication of satellite tag and other ecological data to advance nature conservation research and practice

The what and where of adding channel noise to the Hodgkin-Huxley equations

One of the most celebrated successes in computational biology is the Hodgkin-Huxley framework for modeling electrically active cells. This framework, expressed through a set of differential equations, synthesizes the impact of ionic currents on a cell's voltage -- and the highly nonlinear impact of that voltage back on the currents themselves -- into the rapid push and pull of the action potential. Latter studies confirmed that these cellular dynamics are orchestrated by individual ion channels, whose conformational changes regulate the conductance of each ionic current. Thus, kinetic equations familiar from physical chemistry are the natural setting for describing conductances; for small-to-moderate numbers of channels, these will predict fluctuations in conductances and stochasticity in the resulting action potentials. At first glance, the kinetic equations provide a far more complex (and higher-dimensional) description than the original Hodgkin-Huxley equations. This has prompted more than a decade of efforts to capture channel fluctuations with noise terms added to the Hodgkin-Huxley equations. Many of these approaches, while intuitively appealing, produce quantitative errors when compared to kinetic equations; others, as only very recently demonstrated, are both accurate and relatively simple. We review what works, what doesn't, and why, seeking to build a bridge to well-established results for the deterministic Hodgkin-Huxley equations. As such, we hope that this review will speed emerging studies of how channel noise modulates electrophysiological dynamics and function. We supply user-friendly Matlab simulation code of these stochastic versions of the Hodgkin-Huxley equations on the ModelDB website (accession number 138950) and http://www.amath.washington.edu/~etsb/tutorials.html.Comment: 14 pages, 3 figures, review articl

Theories for influencer identification in complex networks

In social and biological systems, the structural heterogeneity of interaction networks gives rise to the emergence of a small set of influential nodes, or influencers, in a series of dynamical processes. Although much smaller than the entire network, these influencers were observed to be able to shape the collective dynamics of large populations in different contexts. As such, the successful identification of influencers should have profound implications in various real-world spreading dynamics such as viral marketing, epidemic outbreaks and cascading failure. In this chapter, we first summarize the centrality-based approach in finding single influencers in complex networks, and then discuss the more complicated problem of locating multiple influencers from a collective point of view. Progress rooted in collective influence theory, belief-propagation and computer science will be presented. Finally, we present some applications of influencer identification in diverse real-world systems, including online social platforms, scientific publication, brain networks and socioeconomic systems.Comment: 24 pages, 6 figure

Structure and evolutionary origin of Ca2+-dependent herring type II antifreeze protein

10.1371/journal.pone.0000548PLoS ONE26

Effect of Some Oligosaccharides on Functional Properties of Wheat Starch

Purpose: To investigate the effects of oligosaccharides on the functional properties of wheat starch.Methods: The blue value, retrogradation and pasting properties of wheat starch were determined. In addition, water activity (Aw), melting enthalpy and melting temperature of wheat starch paste were analyzed.Results: Fructo-oligosaccharide (FOS) and xylo-oligosaccharide (XOS) inhibited the retrogradation of wheat starch. The peak viscosity of wheat starch with oligosaccharides increased from 3238 ± 8 to 3822 ± 10 cP, with the highest peak obtained for sucrose. The setback of wheat starch decreased (from 1158 ± 5 to 799 ± 6 cP), with the lowest setback for FOS. Aw of control sample changed significantly (falling from 0.978 ± 0.025 to 0.397 ± 0.013) when the drying time was from 6 to 12 hours, while the Aw of the samples to which different oligosaccharides were added only showed slight decrease (from 0.98 ± 0.019 to 0.854 ± 0.022). During storage, the Aw of all starch pastes decreased, and the Aw and melting enthalpy of the samples containing FOS and XOS were significantly lower than that of the control after 6 days storage at 4 and 30 °C.Conclusion: A certain level of oligosaccharides can improve the functional properties of wheat starch paste and thus broaden its application prospects in food and pharmaceutical industries.Keywords: Melting enthalpy, Oligosaccharides, Pasting properties, Water activity, Wheat starc

Measurement of CP-violation asymmetries in D0 to Ks pi+ pi-

We report a measurement of time-integrated CP-violation asymmetries in the resonant substructure of the three-body decay D0 to Ks pi+ pi- using CDF II data corresponding to 6.0 invfb of integrated luminosity from Tevatron ppbar collisions at sqrt(s) = 1.96 TeV. The charm mesons used in this analysis come from D*+(2010) to D0 pi+ and D*-(2010) to D0bar pi-, where the production flavor of the charm meson is determined by the charge of the accompanying pion. We apply a Dalitz-amplitude analysis for the description of the dynamic decay structure and use two complementary approaches, namely a full Dalitz-plot fit employing the isobar model for the contributing resonances and a model-independent bin-by-bin comparison of the D0 and D0bar Dalitz plots. We find no CP-violation effects and measure an asymmetry of ACP = (-0.05 +- 0.57 (stat) +- 0.54 (syst))% for the overall integrated CP-violation asymmetry, consistent with the standard model prediction.Comment: 15 page

Observation of the Baryonic Flavor-Changing Neutral Current Decay Lambda_b -> Lambda mu+ mu-

We report the first observation of the baryonic flavor-changing neutral current decay Lambda_b -> Lambda mu+ mu- with 24 signal events and a statistical significance of 5.8 Gaussian standard deviations. This measurement uses ppbar collisions data sample corresponding to 6.8fb-1 at sqrt{s}=1.96TeV collected by the CDF II detector at the Tevatron collider. The total and differential branching ratios for Lambda_b -> Lambda mu+ mu- are measured. We find B(Lambda_b -> Lambda mu+ mu-) = [1.73+-0.42(stat)+-0.55(syst)] x 10^{-6}. We also report the first measurement of the differential branching ratio of B_s -> phi mu+ mu- using 49 signal events. In addition, we report branching ratios for B+ -> K+ mu+ mu-, B0 -> K0 mu+ mu-, and B -> K*(892) mu+ mu- decays.Comment: 8 pages, 2 figures, 4 tables. Submitted to Phys. Rev. Let