Coronary plaque natural history displays significant longitudinal heterogeneity along the length of individual coronary plaques

Background The natural history of plaque growth is, among other systemic risk factors, related to the blood flow induced local shear stress. Especially at regions of low shear stress plaques are initiated. Upon plaque encroachment into the lumen, plaques will be exposed to high shear stress. Interestingly, it has been observed that individual plaques are very heterogeneous regarding the local shear stress exposure and remodeling patterns along the plaque length. However no information is available on the spatial heterogeneity of temporal changes in plaques burden. We studied the longitudinal spatial heterogeneity of plaque burden progression, regression, quiescence in human coronary plaques. Methods 591 coronary arteries from 302 patients with coronary artery disease who presented with an acute coronary syndrome from the PREDICTION study were investigated for local plaque progression, regression, quiescence patterns after 6–10 months follow up. Arterial geometry was derived from angiography/IVUS-based vascular profiling and reported in 3 mm segments. Plaques were defined as >3 consecutive segments with maximal wall thickness>0.5 mm. Plaque progression was defined as >5% increase, regression as <−5% decrease, and quiescence as no change in plaque burden (plaque area/ total vessel area * 100%). Logistic mixed model regression analysis was performed with plaque progression features as outcome and plaque length as independent variable with vessel as random factor to account for clustering of the data. Results 5658 3mm-segments of 661 plaques were analyzed. Plaque burden changes over time ranged from −22% to +20%, with an average of −0.4%±4% which was not significant different from 0. Among all plaques, 56% showed segments with plaque progression of more than 5%, 60% with plaque regression (<−5%) and 96% of the plaques had segments that did not change over time (quiescence). On average, 17% of the plaque length displayed plaque progression, 20% regression and 63% was quiescent. The presence and number of features (progression, regression, quiescence) within the plaque were significantly related to the plaque length (figure). Conclusion Plaques are very heterogeneous in plaque progression patterns. Most of the plaques show within the plaque length simultaneously more than one plaque progression feature (segments that do not change in plaque burden, segments that regress or progress). The number of observed plaque progression features was related to the plaque length. Funding Acknowledgement Type of funding source: None

Atherogenic diet-diminished endothelial glycocalyx contributes to impaired vasomotor properties in rat

Twelve-week high-cholesterol (HC) diet reduces the thickness of the endothelial glycocalyx in Sprague-Dawley (SD) male rats, which is mainly attributed to a downregulation of heparan sulfate proteoglycan-related genes (syndecan-3, glypican-1, EXT1), not resulting from an enhanced shedding of sulfated glycosaminoglycans (sGAGs) into the plasma. HC-diminished glycocalyx may disturb its mechanotransduction of local shear stress, lower nitric oxide (NO) release, and impair vasomotor responses to norepinephrine (NE) and acetylcholine (ACh).

Experimental Investigation on Influence of Inclination and Curved Surface of Ship Bottom in Air Lubrication Method

The air lubrication method, which mixes millimeter bubbles into the flow around the hull and reduces frictional resistance, is expected to have a large energy saving effect among a number of marine energy saving technologies. Concerning the frictional drag reduction effect using the air lubrication method, in this study, the frictional drag reduction effect was experimentally investigated for gas-liquid two phase flow considering the influence of inclination and curved surface of the ship bottom. Measurement of local shear stress and measurement of void fraction distribution near the wall surface were carried out and the correlation between local shear stress and local void fraction distribution was grasped.

A Graphical Technique for Solving the Couette-Poiseuille Problem for Generalized Newtonian Fluids

This paper addresses the mixed Couette-Poiseuille problem, that is the flow between two parallel plates, in the presence of simultaneous pressure gradient and wall motion. Instead of the wall-normal coordinate y, we use the local shear stress as our primary variable and rewrite the corresponding formulae for the velocity profile, flow rate, etc. This gives rise to a graphical technique for solving the problem in the case of arbitrary (possibly measured) generalized Newtonian fluid rheology. We demonstrate the use of the proposed technique on two problems: (a) Bingham fluid and (b) a non-Newtonian fluid with general, nonmonotonous viscosity function.