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ABSTRACT: Endothelial nitric oxide synthase (eNOS) is the primary enzyme that produces nitric oxide (NO), which plays an important role in blood vessel relaxation. eNOS activation is stimulated by various mechanical forces, such as shear stress. Several studies have shown that local cooling of the human finger causes strong vasoconstriction, followed after several minutes by cold-induced vasodilation (CIVD). However, the role played by endothelial cells (ECs) in blood vessel regulation in respond to cold temperatures is not fully understood. In this study, we found that low temperature alone does not significantly increase or decrease eNOS activation in ECs. We further found that the combination of shear stress with temperature change leads to a significant increase in eNOS activation at 37°C and 28°C, and a decrease at 4°C. These results show that ECs play an important role in blood vessel regulation under shear stress and low temperature.
Biochemical and Biophysical Research Communications 07/2011; 412(2):318-22. · 2.48 Impact Factor
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ABSTRACT: This study was undertaken to clarify the molecular basis for human skin color variation and the environmental adaptability to ultraviolet irradiation, with the ultimate goal of predicting the impact of changes in future environments on human health risk. One hundred twenty-two Caucasians living in Toledo, Ohio participated. Back and cheek skin were assayed for melanin as a quantitative trait marker. Buccal cell samples were collected and used for DNA extraction. DNA was used for SNP genotyping using the Masscode system, which entails two-step PCR amplification and a platform chemistry which allows cleavable mass spectrometry tags. The results show gene-gene interaction between SNP alleles at multiple loci (not necessarily on the same chromosome) contributes to inter-individual skin color variation while suggesting a high probability of linkage disequilibrium. Confirmation of these findings requires further study with other ethic groups to analyze the associations between SNP alleles at multiple loci and human skin color variation. Our overarching goal is to use remote sensing data to clarify the interaction between atmospheric environments and SNP allelic frequency and investigate human adaptability to ultraviolet irradiation. Such information should greatly assist in the prediction of the health effects of future environmental changes such as ozone depletion and increased ultraviolet exposure. If such health effects are to some extent predictable, it might be possible to prepare for such changes in advance and thus reduce the extent of their impact.
Evolutionary bioinformatics online 02/2007; 3:169-78. · 1.23 Impact Factor
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ABSTRACT: Endothelial cells (ECs) that line the inner surface of blood vessels are continuously exposed to fluid frictional force (shear stress) induced by blood flow, and shear stress affects the intracellular calcium ([Ca2+]i), which initiates cellular responses. Here, we studied the effect of long-term exposure of shear stress on [Ca2+]i responses in cultured ECs by using a confocal laser microscope and calcium indicator. At the initiation of shear stress of 20 dyn/cm2 (0 hr), 27% of the cells exhibited [Ca2+]i responses. This percentage gradually decreased with increasing exposure time, reaching about 4% after 24 hr of exposure. These data indicate that long-term shear-stress exposure affects [Ca2+]i responses in cultured ECs. Furthermore, we studied the effect of magnitude of shear stress on macromolecule uptake. For the low shear-stress, the uptake was enhanced, whereas the uptake was inhibited for higher shear-stress.
Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science 08/2005; 24(4):459-61.
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ABSTRACT: We present a conceptual framework for applying techniques of SNP genotyping as a molecular biological approach and remote sensing as an ecological approach to elucidation of the contribution of polygene and environmental factors to inter-individual variation in skin pigmentation phenotype. Additionally, we discuss the obstacles that frustrate our efforts to identify how the human genome encodes the complex phenotype and suggest the use of computational methods designed for knowledge discovery within hereditary database.
Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science 08/2005; 24(4):483-6.
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ABSTRACT: To determine the nature of intracellular Mg2+ stores and Mg2+ release mechanisms in differentiated PC12 cells, Mg2+ and Ca2+ mobilizations were measured simultaneously in living cells with KMG-104, a fluorescent Mg2+ indicator, and fura-2, respectively. Treatment with the mitochondrial uncoupler, carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), increased both the intracellular Mg2+ concentration ([Mg2+]i) and the [Ca2+]i in these cells. Possible candidates as intracellular Mg2+ stores under these conditions include intracellular divalent cation binding sites, endoplasmic reticulum (ER), Mg-ATP and mitochondria. Given that no change in [Mg2+]i was induced by caffeine application, intracellular IP3 or Ca2+ liberated by photolysis, it appears that no Mg2+ release mechanism thus exists that is mediated via the action of Ca2+ on membrane-bound receptors in the ER or via the offloading of Mg2+ from binding sites as a result of the increased [Ca2+]i. FCCP treatment for 2 min did not alter the intracellular ATP content, indicating that Mg2+ was not released from Mg-ATP, at least in the first 2 min following exposure to FCCP. FCCP-induced [Mg2+]i increase was observed at mitochondria localized area, and vice versa. These results suggest that the mitochondria serve as the intracellular Mg2+ store in PC12 cell. Simultaneous measurements of [Ca2+]i and mitochondrial membrane potential, and also of [Ca2+]i and [Mg2+]i, revealed that the initial rise in [Mg2+]i followed that of mitochondrial depolarization for several seconds. These findings show that the source of Mg2+ in the FCCP-induced [Mg2+]i increase in PC12 cells is mitochondria, and that mitochondrial depolarization triggers the Mg2+ release.
Biochimica et Biophysica Acta 06/2005; 1744(1):19-28. · 4.66 Impact Factor
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ABSTRACT: Shear stress stimulus is expected to enhance angiogenesis, the formation of microvessels. We determined the effect of shear stress stimulus on three-dimensional microvessel formation in vitro. Bovine pulmonary microvascular endothelial cells were seeded onto collagen gels with basic fibroblast growth factor to make a microvessel formation model. We observed this model in detail using phase-contrast microscopy, confocal laser scanning microscopy, and electron microscopy. The results show that cells invaded the collagen gel and reconstructed the tubular structures, containing a clearly defined lumen consisting of multiple cells. The model was placed in a parallel-plate flow chamber. A laminar shear stress of 0.3 Pa was applied to the surfaces of the cells for 48 h. Promotion of microvessel network formation was detectable after approximately 10 h in the flow chamber. After 48 h, the length of networks exposed to shear stress was 6.17 (+/-0.59) times longer than at the initial state, whereas the length of networks not exposed to shear stress was only 3.30 (+/-0.41) times longer. The number of bifurcations and endpoints increased for networks exposed to shear stress, whereas the number of bifurcations alone increased for networks not exposed to shear stress. These results demonstrate that shear stress applied to the surfaces of endothelial cells on collagen gel promotes the growth of microvessel network formation in the gel and expands the network because of repeated bifurcation and elongation.
AJP Heart and Circulatory Physiology 10/2004; 287(3):H994-1002. · 3.71 Impact Factor
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奨 工藤,
憲治 池澤,
伸治 松村,
満里子 池田,
浩太郎 岡,
一夫 谷下, Susumu Kudo,
Kenji IKEZAWA,
Shinji MATSUMURA,
Mariko Ikeda,
Kotaro Oka,
Kazuo Tanishita
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ABSTRACT: rights: 社団法人日本機械学会 rights: 本文データは学協会の許諾に基づきCiNiiから複製したものである relation：isVersionOf: http://ci.nii.ac.jp/naid/110002397044/ The purpose of this study is to reveal (1) the energy dependence of albumin uptake into endothelial cells, and (2) the effect of shear stress on the albumin uptake area and the its content per unit area. The uptake of the fluorescent labeled albumin (tetramethylrhodamine isothiocyanate conjugated albumin, TRITC-albumin) was visualized with a confocal laser scanning microscope. The uptake into the endothelial cells is inhibited completely at 4℃ or by 1 μM FCCP, that is a potent energy metabolism inhibitor. This result indicates that the albumin uptake is an energy-dependent, active transport. After 48 hour exposure to shear stress to the endothelial cells, the albumin uptake area and the albumin content per unit area were changed. At 10 dyn/cm^2,at 5 μm the uptake area increases by 363% and the albumin content per unit area increases by 192%. At 60 dyn/cm^2,at 3μm the uptake area decreases by 21% and the albumin content per unit area decreases by 54%. It is, therefore, considered that the effect of shear stress on the uptake area is more influential than that on the albumin content per unit area. We conclude that endothelial cells affected by sher stress change the albumin uptake function and especially the cells change the uptake area.
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奨 工藤,
憲治 池澤,
伸治 松村,
満里子 池田,
浩太郎 岡,
一夫 谷下, Susumu Kudo,
Kenji IKEZAWA,
Shinji MATSUMURA,
Mariko Ikeda,
Kotaro Oka,
Kazuo Tanishita
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ABSTRACT: rights: 社団法人日本機械学会 rights: 本文データは学協会の許諾に基づきCiNiiから複製したものである relation：isVersionOf: http://ci.nii.ac.jp/naid/110002396800/ The purpose of this study is to reveal macromolecule uptake route (intercellular or intracellular) in the endothelial cell layer, and to examine the effect of wall shear stress on the uptake. After 48 hour exposure to shear stress, the endothelial cell layer on coverslips were incubated at 37℃ for 60 minutes in PBS containing tetramethylrhodamine isothiocyanate conjugated albumin (TRITC-albumin). Thereafter, the uptake of albumin and the shape of endothelial cells were observed by a confocal laser scanning microscope (CLSM). Albumin is found in intracellular region, not in intercellular region. The albumin uptake depends on imposed shear stress. At 10 dyn/cm^2,the albumin uptake showed a 1.3 folds increase. The albumin uptake decreases with increasing shear stress, and minimum uptake is quarter of the control value at 60 dyn/cm^2. This shear dependence of uptake is an unique feature of the cell and may play a key role for the controlling mechanism of endothelial cells.
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ABSTRACT: Endothelial cell adhesion and growth were investigated on three types of surfaces with a plasma-polymerized coating (PPC): (1) the pristine surface of a hexamethyldisiloxane (HMDS) PPC (hydrophobic, electrically neutral surface); (2) an HMDS PPC surface with nitrogen-containing plasma treatment (hydrophilic, positively charged surface); and (3) an HMDS PPC surface treated with oxygen plasma (hydrophilic, negatively charged surface). Endothelial cells grew on surface (2) but not on surfaces (1) or (3). Next, endothelial cell adhesion and growth was investigated on a surface on which 80-μm squares were micro-patterned at 160-μm intervals in a mosaic composed of two different (cell-adhesive and non-cell-adhesive) regions. Cell growth on the patterned surfaces was different from that on non-patterned surfaces. PPC was shown to be a simple process for modulating cell adhesion to surfaces.
