Stretch‐Induced Increase in Cardiac Contractility Is Independent of Myocyte Ca\u3csup\u3e2+\u3c/sup\u3e While Block of Stretch Channels by Streptomycin Improves Contractility After Ischemic Stunning

Stretching the cardiac left ventricle (LV) enhances contractility but its effect on myoplasmic [Ca2+] is controversial. We measured LV pressure (LVP) and [Ca2+] as a function of intra-LV stretch in guinea pig intact hearts before and after 15 min global stunning ± perfusion with streptomycin (STM), a stretch activated channel blocker. LV wall [Ca2+] was measured by indo-1 fluorescence and LVP by a saline-filled latex balloon inflated in 50 μL steps to stretch the LV. We implemented a mathematical model to interpret crossbridge dynamics and myofilament Ca2+ responsiveness from the instantaneous relationship between [Ca2+] and LVP ± stretching. We found that: (1) stretch enhanced LVP but not [Ca2+] before and after stunning in either control (CON) and STM groups, (2) after stunning [Ca2+] increased in both groups although higher in STM versus CON (56% vs. 39%), (3) STM-enhanced LVP after stunning compared to CON (98% vs. 76% of prestunning values), and (4) stretch-induced effects on LVP were independent of [Ca2+] before or after stunning in both groups. Mathematical modeling suggested: (1) cooperativity in cross-bridge kinetics and myofilament Ca2+ handling is reduced after stunning in the unstretched heart, (2) stunning results in depressed myofilament Ca2+ sensitivity in the presence of attached cross-bridges regardless of stretch, and (3) the initial mechanism responsible for increased contractility during stretch may be enhanced formation of cross-bridges. Thus stretch-induced enhancement of contractility is not due to increased [Ca2+], whereas enhanced contractility after stunning in STM versus CON hearts results from improved Ca2+ handling and/or enhanced actinomyosin cross-bridge cycling

Development of human single-chain antibodies against SARS-associated coronavirus.

The outbreak of severe acute respiratory syndrome (SARS), caused by a distinct coronavirus, in 2003 greatly threatened public health in China, Southeast Asia as well as North America. Over 1,000 patients died of the SARS virus, representing 10% of infected people. Like other coronaviruses, the SARS virus also utilizes a surface glycoprotein, namely the spike protein, to infect host cells. The spike protein of SARS virus consists of 1,255 amino acid residues and can be divided into two sub-domains, S1 and S2. The S1 domain mediates the binding of the virus to its receptor angiotensin-converting enzyme 2, which is abundantly distributed on the surface of human lung cells. The S2 domain mediates membrane fusion between the virus and the host cell. Hence two strategies can be used to block the infection of the SARS virus, either by interfering with the binding of the S1 domain to the receptor or by blocking the fusion of the virus with the cell membrane mediated by the S2 domain. Several antibodies against the S1 domain have been generated and all of them are able to neutralize the virus in vitro and in vivo using animal models. Unfortunately, point mutations have been identified in the S1 domain, so that the virus isolated in the future may not be recognized by these antibodies. As no mutation has been found in the S2 domain indicating that this region is more conserved than the S1 domain, it may be a better target for antibody binding. After predicting the immunogenicity of the epitopes of the S2 domain, we chemically synthesized two peptides and also expressed one of them using a recombinant DNA method. We screened a phage displaying library of human single-chain antibodies (ScFv) against the predicted epitopes and obtained a human ScFv which can recognize the SARS virus in vitro

The impact of multiple sclerosis on the identity of mothers in Italy

Purpose: This paper reports on one of the themes that emerged from the analysis of the study, regarding the perceived influence of multiple sclerosis (MS) on the identity of mothers in the socio-cultural context of Italy. Method: In-depth interviews were conducted with 16 women at various stages of MS, with follow up interviews with seven of the women. Phenomenology guided the methodology and the analysis was conducted using interpretative phenomenological analysis. Results: Through the research the value of motherhood to the women who participated emerged. The findings illustrated how many strove to maintain controlof their MS, which led to some making comparisons of themselves and other mothers and feeling different. Some women described how they adjusted their roles and found strength in being mothers but others spoke of their feelings of loss. Most women described living in the moment, appreciating the present and living each day as it came. Another significant experience was fear of stigma, both realized in the form of “pity” from others, and the perceived and actual associated stigma for their families. This contributed to why some women were reluctant to disclose their condition. The mothers who took part in this study differed in how they perceived their disabled identity. Conclusion: Although this study was conducted in the socio-cultural setting of Italy, the findings have implications for professionals working with disabled mothers and women with MS in Italy and beyond; including recognizing the value associated with fully identifying oneself as a mother, rather than solely focusing on doingmothering tasks. • Implications for Rehabilitation • Professionals need to be mindful of the value of motherhood for women with multiple sclerosis. • Professionals should support women who feel like they are battling with maintaining control of their multiple sclerosis, who may be adjusting their identity as mothers; recognizing that they may be influenced by the stage of their multiple sclerosis and whether they were diagnosed before or after having their children. • Women can have feelings of loss related to their ability to fully participate in their children’s lives and professionals should work with women to help them identify the value of their mothering role not only in physically participating in activities but also in being emotionally and physically present as a mother

Gap modification of atomically thin boron nitride by phonon mediated interactions

A theory is presented for the modification of bandgaps in atomically thin boron nitride (BN) by attractive interactions mediated through phonons in a polarizable substrate, or in the BN plane. Gap equations are solved, and gap enhancements are found to range up to 70% for dimensionless electron-phonon coupling \lambda=1, indicating that a proportion of the measured BN bandgap may have a phonon origin

Two-dimensional Dirac fermions in a topological insulator: transport in the quantum limit

Pulsed magnetic fields of up to 55T are used to investigate the transport properties of the topological insulator Bi_2Se_3 in the extreme quantum limit. For samples with a bulk carrier density of n = 2.9\times10^16cm^-3, the lowest Landau level of the bulk 3D Fermi surface is reached by a field of 4T. For fields well beyond this limit, Shubnikov-de Haas oscillations arising from quantization of the 2D surface state are observed, with the \nu =1 Landau level attained by a field of 35T. These measurements reveal the presence of additional oscillations which occur at fields corresponding to simple rational fractions of the integer Landau indices.Comment: 5 pages, 4 figure

Design studies for twist-coupled wind turbine blades.

This study presents results obtained for four hybrid designs of the Northern Power Systems (NPS) 9.2-meter prototype version of the ERS-100 wind turbine rotor blade. The ERS-100 wind turbine rotor blade was designed and developed by TPI composites. The baseline design uses e-glass unidirectional fibers in combination with {+-}45-degree and random mat layers for the skin and spar cap. This project involves developing structural finite element models of the baseline design and carbon hybrid designs with and without twist-bend coupling. All designs were evaluated for a unit load condition and two extreme wind conditions. The unit load condition was used to evaluate the static deflection, twist and twist-coupling parameter. Maximum deflections and strains were determined for the extreme wind conditions. Linear and nonlinear buckling loads were determined for a tip load condition. The results indicate that carbon fibers can be used to produce twist-coupled designs with comparable deflections, strains and buckling loads to the e-glass baseline

Emergence of structural and dynamical properties of ecological mutualistic networks

Mutualistic networks are formed when the interactions between two classes of species are mutually beneficial. They are important examples of cooperation shaped by evolution. Mutualism between animals and plants plays a key role in the organization of ecological communities. Such networks in ecology have generically evolved a nested architecture independent of species composition and latitude - specialists interact with proper subsets of the nodes with whom generalists interact. Despite sustained efforts to explain observed network structure on the basis of community-level stability or persistence, such correlative studies have reached minimal consensus. Here we demonstrate that nested interaction networks could emerge as a consequence of an optimization principle aimed at maximizing the species abundance in mutualistic communities. Using analytical and numerical approaches, we show that because of the mutualistic interactions, an increase in abundance of a given species results in a corresponding increase in the total number of individuals in the community, as also the nestedness of the interaction matrix. Indeed, the species abundances and the nestedness of the interaction matrix are correlated by an amount that depends on the strength of the mutualistic interactions. Nestedness and the observed spontaneous emergence of generalist and specialist species occur for several dynamical implementations of the variational principle under stationary conditions. Optimized networks, while remaining stable, tend to be less resilient than their counterparts with randomly assigned interactions. In particular, we analytically show that the abundance of the rarest species is directly linked to the resilience of the community. Our work provides a unifying framework for studying the emergent structural and dynamical properties of ecological mutualistic networks.Comment: 10 pages, 4 figure

Influence of the initial chemical conditions on the rational design of silica particles

The influence of the water content in the initial composition on the size of silica particles produced using the Stöber process is well known. We have shown that there are three morphological regimes defined by compositional boundaries. At low water levels (below stoichiometric ratio of water:tetraethoxysilane), very high surface area and aggregated structures are formed; at high water content (>40 wt%) similar structures are also seen. Between these two boundary conditions, discrete particles are formed whose size are dictated by the water content. Within the compositional regime that enables the classical Stöber silica, the structural evolution shows a more rapid attainment of final particle size than the rate of formation of silica supporting the monomer addition hypothesis. The clearer understanding of the role of the initial composition on the output of this synthesis method will be of considerable use for the establishment of reliable reproducible silica production for future industrial adoption