Flow patterns in blood vessels contribute to focal distribution of atherosclerosis; the underlying mechanotransduction pathways remain to be investigated. We demonstrate that different flow patterns elicit distinct responses of Krüppel-like factor-2 (KLF2) in endothelial cells (ECs) in vitro and in vivo. While pulsatile flow with a significant forward direction induced sustained expression of KLF2 in cultured ECs, oscillatory flow with little forward direction caused prolonged suppression after a transient induction. The suppressive effect of oscillatory flow was Src-dependent. Immunohistochemical studies on ECs at arterial branch points revealed that KLF2 protein levels were related to local hemodynamics. Such flow-associated expression patterns were also demonstrated in a rat aortic restenosis model. Inhibition of KLF2 with siRNA sensitized ECs to oxidized LDL-induced apoptosis, indicating a protective role of KLF2. In conclusion, differential regulation of KLF2 may mediate the distinct vascular effects induced by various patterns of shear stress.
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http://dx.doi.org/10.1016/j.bbrc.2006.01.089 | DOI Listing |
Sci Rep
December 2024
College of Civil Engineering, Guizhou University, Huaxi District, Guiyang, 550025, Guizhou, China.
In order to investigate the influence of shear on contact characteristics and fluid flow evolution of rough rock fractures, a series of shear-flow tests were carried out by numerical experiments. Firstly, a sandstone specimen with a rough fracture was made in the laboratory, and the numerical model of the fracture was reconstructed in FLAC3D software. Experiments were conducted to investigate the depth of penetration of the fracture under different normal stress (1, 3, and 5 MPa) and shear displacement (2, 4, 6, 8, and 10 mm).
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December 2024
Research Center of Space Structures, Guizhou University, Guiyang, 550025, China.
This study employed numerical simulation to investigate the dynamic response characteristics of open-web girders subjected to proximity blast loading and to compare these characteristics with those of solid-web girders. The research utilized the Coupled Eulerian-Lagrangian (CEL) method for simulation, effectively combining the advantages of both Eulerian and Lagrangian approaches. This method mitigated issues related to mesh distortion while accurately modeling the damage inflicted by blast loads on the structures.
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December 2024
Department of Geography and Environment, Loughborough University, Loughborough, LE11 3TU, UK.
Wave ripples can provide valuable information on their formative hydrodynamic conditions in past subaqueous environments by inverting dimension predictors. However, these inversions do not usually take the mixed non-cohesive/cohesive nature of sediment beds into account. Recent experiments involving sand-kaolinite mixtures have demonstrated that wave-ripple dimensions and the threshold of motion are affected by bed clay content.
View Article and Find Full Text PDFTo address the challenges of performing in-situ tests on riverbed overburden gravel, this study employs three scaling methods-equal mass substitution, similar gradation, and the mixed method-to investigate the original gradation of the gravel. Large-scale triaxial consolidated drained shear tests were conducted to evaluate the effects of the maximum particle size reduction ratio (M) and confining pressure on the stress-strain behavior, fractal dimension, particle breakage, and the parameters of the Duncan-Chang model (an elastic model describing nonlinear stress-strain relationships). The study explores how scaling, based on fractal dimension and particle breakage rate, impacts the strength and deformation characteristics of gravel materials.
View Article and Find Full Text PDFInt Dent J
December 2024
Center of Excellence for Dental Stem Cell Biology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand; Faculty of Dentistry, Department of Anatomy, Chulalongkorn University, Bangkok, Thailand.
Human periodontal ligament (hPDL) is continuously exposed to mechanical forces that can induce inflammatory responses in resident stem cells (hPDLSCs). Here, we review the impact of mechanical force on hPDLSCs, focusing on the activation of inflammatory cytokines and related signalling pathways, which subsequently influence periodontal tissue remodelling. The effects of various mechanical forces, including compressive, shear, and tensile forces, on hPDLSCs are discussed.
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