Background-The functional changes associated with cellular senescence may be involved in human aging and age-related vascular disorders. We have shown the important role of telomere and telomerase in vascular cell senescence in vitro. Progressive telomere shortening in vivo has been observed in the regions susceptible to atherosclerosis, implying contributions to atherogenesis. However, whether senescent vascular cells are present in the vasculature and contribute to the pathogenesis of atherosclerosis remains unclear. Methods and Results-Senescence-associated ␤-galactosidase (␤-gal) activity was examined in the coronary arteries and the internal mammary arteries retrieved from autopsied individuals who had had ischemic heart diseases. Strong ␤-gal stainings were observed in atherosclerotic lesions of the coronary arteries but not in the internal mammary arteries. Key Words: aging Ⅲ atherosclerosis Ⅲ endothelium C ellular senescence is a limited ability of primary human cells to divide when cultured in vitro. This cessation of cell division is accompanied by a specific set of changes in cell function, morphology, and gene expression. These changes in cell phenotype may contribute to age-associated diseases, including atherosclerosis. However, cellular senescence has largely been investigated in vitro, and the presence of senescent vascular cells in vivo has not been clarified.Recently, accumulating evidence has suggested a critical role of telomere and telomerase in cellular senescence in vitro. 1 We have demonstrated previously that the introduction of telomerase catalytic component (TERT) into human vascular smooth muscle cells extends cell life span and preserves a younger phenotype, suggesting that telomere stabilization is important for long-term cell viability of vascular cells. 2 Progressive telomere shortening in human arteries has been observed in the regions susceptible to atherosclerosis. 3 Moreover, telomere length has been reported to inversely correlate with pulse pressure and atherosclerotic grade in human. 4,5 Although these observations imply that telomere shortening in vivo may contribute to the pathogenesis of age-associated vascular disorders, it remains unclear whether loss of telomere function induces vascular dysfunction associated with aging.In the present study, we demonstrate the presence of vascular endothelial cells with senescence-associated phenotypes in the atherosclerotic regions of human coronary arteries. We also show that loss of telomere function induces endothelial dysfunctions that are observed in aged arteries, whereas inhibition of telomere shortening suppresses these alterations with senescence. Methods Tissue SpecimensHuman coronary arteries and internal mammary arteries were obtained from 4 autopsied individuals who had ischemic heart diseases. The autopsy tissues were obtained within 12 hours after death and were subjected to ␤-galactosidase (␤-gal) staining. HistologySenescence-associated ␤-gal activity was examined in the tissues as described previously. 6 Briefly, t...

The quantification procedure of oxygen-transport resistances for different fuel-cell layers and phenomena is described. The total transport resistance is obtained from limiting-current measurements under conditions where oxygen diffusion is dominant (i.e., high flow rates, small cell size, humidified but subsaturated feeds, and low feed oxygen partial pressure). By systematically varying the experimental conditions, the contributions of molecular and Knudsen diffusion and permeation through the ionomer film covering the catalyst-layer agglomerates are determined. It is found that the ionomer-film resistance is dominant, especially at lower temperatures and lower Pt loadings. The calculated film properties through the ionomer hint that it is much more resistive than the bulk membrane for state-of-the-art cells.

The Fuel Cell Commercialization Conference of Japan (FCCJ) revised in 2011 a part of the target performance, durability, and cost of fuel cells for transportation application based on the latest technical data and knowledge obtained from the vehicle tests in the public thoroughfare and the simple systems to be expected in the commercialization stage. FCCJ also updated a methodology for testing membrane-electrode assemblies (MEAs) and its materials: electrolyte membranes and electrocatalysts. This revision is intended to assist the development of materials for industry, university, and research institutes from practicality, simplicity, and convenience points of view. The purpose of this paper is to describe the revised targets and the updated evaluation methods with the background technical information related to fuel cell vehicles (FCVs).

This article presents a high-level overview of the various technological advances that were performed to enable the commercialization of the Toyota MIRAI fuel cell vehicle. The article describes the innovations made in flow-field structure, catalyst layer structure and composition, various stack components, the hydrogen storage tank, and in streamlining the humidification process. Finally, the article highlights the importance of leveraging mass manufactured parts from prior generations/platforms to the maximum extent possible to achieve the requisite cost reductions and concludes with some thoughts on the future of fuel cell vehicles, and the necessity for a concerted effort to develop a hydrogen fueling infrastructure.