Сім сліз Івана Чендея

Розглядається творчість Івана Чендея на рівні структурних та функціональних особливостей символічних образів сльози, уточнюються оцінки окремих творів з погляду їхньої взаємодії з часом

Journal Staff

Purpose: To investigate the accuracy of wall shear stress (WSS) estimation using MRI. Specifically, to investigate the impact of different parameters and if MRI WSS estimates are monotonically related to actual WSS. Materials and Methods: The accuracy of WSS estimation using methods based on phase-contrast (PC) MRI velocity mapping, Fourier velocity encoding (FVE) and intravoxel velocity standard deviation mapping were studied using numerical simulations. The influence of spatial resolution, velocity encoding, wall segmentation, and voxel location were investigated over a range of WSS values. Results: WSS estimates were found to be sensitive to parameter settings in general and spatial resolution in particular. All methods underestimated WSS, except for the FVE-based method, which instead was extremely sensitive to voxel position relative to the wall. Methods using PC-based WSS estimation with wall segmentation showed to be accurate for low WSS, but were sensitive to segmentation errors. Conclusion: Even in the absence of noise and for relatively simple velocity profiles, MRI WSS estimates cannot always be assumed to be linearly or even monotonically related to actual WSS. High WSS values cannot be resolved and the estimates depend on parameter setting. Nevertheless, distinguishing areas of low and moderate WSS may be feasible

Assessment of energy loss across aortic valves using accelerated CMR multi-point flow measurements

ISSN:1097-6647ISSN:1532-429

Fibromodulin Interacts with Collagen Cross-linking Sites and Activates Lysyl Oxidase

The hallmark of fibrotic disorders is a highly cross-linked and dense collagen matrix, a property driven by the oxidative action of lysyl oxidase. Other fibrosis-associated proteins also contribute to the final collagen matrix properties, one of which is fibromodulin - its interactions with collagen affect collagen cross-linking, packing, and fibril diameter. We investigated the possibility that a specific relationship exists between fibromodulin and lysyl oxidase, potentially imparting a specific collagen matrix phenotype. We mapped the fibromodulin-collagen interaction sites using the Collagen II and III Toolkit peptide libraries. Fibromodulin interacted with the peptides containing the known collagen cross-linking sites and the MMP-1 cleavage site in collagens I and II. Interestingly, the interaction sites are closely aligned within the quarter-staggered collagen fibril, suggesting a multivalent interaction between fibromodulin and several collagen helices. Furthermore, we detected an interaction between fibromodulin and lysyl oxidase - a major collagen cross-linking enzyme - and mapped the interaction site to 12 N-terminal amino acids on fibromodulin. This interaction also increases the activity of lysyl oxidase. Altogether, the data suggest a fibromodulin-modulated collagen cross-linking mechanism, where fibromodulin binds to a specific part of the collagen domain and also forms a complex together with lysyl oxidase, targeting the enzyme towards specific cross-linking sites.SK and KR were supported by grants from the Swedish Cancer Foundation, the Swedish Research Council, the Alfred Österlund Foundation, the Crafoord Foundation, the Magnus Bergvall Foundation, and the Åke Wiberg Foundation; AB, DB and RWF by grants from the Wellcome Trust (094470/Z/10/Z) and British Heart Foundation (RG/15/4/31268).This is the final version of the article. It first appeared from the American Society for Biochemistry and Molecular Biology] via http://dx.doi.org/10.1074/jbc.M115.69340

Impact of dobutamine stress on diastolic energetic efficiency of healthy left ventricle: an in vivo kinetic energy analysis

The total kinetic energy (KE) of blood can be decomposed into mean KE (MKE) and turbulent KE (TKE), which are associated with the phase-averaged fluid velocity field and the instantaneous velocity fluctuations, respectively. The aim of this study was to explore the effects of pharmacologically induced stress on MKE and TKE in the left ventricle (LV) in a cohort of healthy volunteers. 4D Flow MRI data were acquired in eleven subjects at rest and after dobutamine infusion, at a heart rate that was ∼60% higher than the one in rest conditions. MKE and TKE were computed as volume integrals over the whole LV and as data mapped to functional LV flow components, i.e., direct flow, retained inflow, delayed ejection flow and residual volume. Diastolic MKE and TKE increased under stress, in particular at peak early filling and peak atrial contraction. Augmented LV inotropy and cardiac frequency also caused an increase in direct flow and retained inflow MKE and TKE. However, the TKE/KE ratio remained comparable between rest and stress conditions, suggesting that LV intracavitary fluid dynamics can adapt to stress conditions without altering the TKE to KE balance of the normal left ventricle at rest

Left Ventricular Flow Analysis: Novel Imaging Biomarkers and Predictors of Exercise Capacity in Heart Failure.

Background: Cardiac remodeling, after a myocardial insult, often causes progression to heart failure. The relationship between alterations in left ventricular blood flow, including kinetic energy (KE), and remodeling is uncertain. We hypothesized that increasing derangements in left ventricular blood flow would relate to (1) conventional cardiac remodeling markers, (2) increased levels of biochemical remodeling markers, (3) altered cardiac energetics, and (4) worsening patient symptoms and functional capacity. Methods: Thirty-four dilated cardiomyopathy patients, 30 ischemic cardiomyopathy patients, and 36 controls underwent magnetic resonance including 4-dimensional flow, BNP (brain-type natriuretic peptide) measurement, functional capacity assessment (6-minute walk test), and symptom quantification. A subgroup of dilated cardiomyopathy and control subjects underwent cardiac energetic assessment. Left ventricular flow was separated into 4 components: direct flow, retained inflow, delayed ejection flow, and residual volume. Average KE throughout the cardiac cycle was calculated. Results: Patients had reduced direct flow proportion and direct-flow average KE compared with controls (P<0.0001). The residual volume proportion and residual volume average KE were increased in patients (P<0.0001). Importantly, in a multiple linear regression model to predict the patient’s 6-minute walk test, the independent predictors were age (β=−0.3015; P=0.019) and direct-flow average KE (β=0.280, P=0.035; R2 model, 0.466, P=0.002). In contrast, neither ejection fraction nor left ventricular volumes were independently predictive. Conclusions: This study demonstrates an independent predictive relationship between the direct-flow average KE and a prognostic measure of functional capacity. Intracardiac 4-dimensional flow parameters are novel biomarkers in heart failure and may provide additive value in monitoring new therapies and predicting prognosis.This study was supported by the British Heart Foundation [grant number FS/12/14/29354 to VMS]; Medical Research Council (ATH); Oxford British Heart Foundation Centre of Research Excellence (ATH and SN); Sir Henry Dale Fellowship from the Wellcome Trust and the Royal Society (098436/Z/12/B to CTR); National Institute for Health Research Oxford Biomedical Research Centre Programme (SN and SGM); Swedish Research Council (PD and TE); the Swedish Heart and Lung Foundation [grant number 20140398 to CJC]. The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 310612 to TE