Intraplaque hemorrhage is associated with higher structural stresses in human atherosclerotic plaques: an in vivo MRI-based 3D fluid-structure interaction study.

BACKGROUND: Studies using medical images have shown that intraplaque hemorrhage may accelerate plaque progression and may produce a stimulus for atherosclerosis development by increasing lipid core and plaque volume and creating new destabilizing factors. Image-based 3D computational models with fluid-structure interactions (FSI) will be used to perform plaque mechanical analysis and investigate possible associations between intraplaque hemorrhage and both plaque wall stress (PWS) and flow shear stress (FSS). METHODS: In vivo MRI data of carotid plaques from 5 patients with intraplaque hemorrhage confirmed by histology were acquired. 3D multi-component FSI models were constructed for each plaque to obtain mechanical stresses. Plaque Wall Stress (PWS) and Flow Shear Stress (FSS) were extracted from all nodal points on the lumen surface of each plaque for analysis. RESULTS: The mean PWS value from all hemorrhage nodes of the 5 plaques combined was higher than that from non-hemorrhage nodes (75.6 versus 68.1 kPa, P = 0.0003). The mean PWS values from hemorrhage nodes for each of the 5 plaques were all significantly higher (5 out of 5) than those from non-hemorrhage nodes (P < 0.05). The mean FSS value from all hemorrhage nodes of the 5 plaques combined was 30.4% higher than that from all non-hemorrhage nodes (15.0 versus 11.5 dyn/cm2, P = 0.0002). However, the mean flow shear stress values from individual cases showed mixed results: only one out of five plaques showed mean FSS value from hemorrhage nodes was higher than that from non-hemorrhage nodes; three out of five plaques showed that their mean FSS values from hemorrhage nodes were lower than those from non-hemorrhage nodes; and one plaque showed that the difference had no statistical significance. CONCLUSION: The results of this study suggested that intraplaque hemorrhage nodes were associated with higher plaque wall stresses. Compared to flow shear stress, plaque wall stress has a better correlation with plaque component feature (hemorrhage) linked to plaque progression and vulnerability. With further validation, plaque stress analysis may provide additional stress indicators for image-based vulnerability assessment.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Deposition Analysis of Nitrogen and Phosphorus in an Integrated Multi-trophic Aquaculture Pond

通过使用沉积物捕获器获取沉积物,研究了一生态综合养殖池塘的沉积作用,并利用室内模拟实验研究了缢蛏(SInOnOVACulA COnSTrzCTA)的生物沉积作用,同时分析了池塘沉积物及其间隙水的营养盐;应用fICk第一定律对池塘沉积物-池水界面营养盐通量进行了估算.藻类池颗粒物质的日平均沉积速率为44.59 g/M2,贝类池颗粒物质的日平均沉积速率为14.01 g/M2;两个池塘试验期内(90 d)n、P的净沉积量分别为6061.5 g和3411 g(采样池塘面积各0.5 HM2,水深50~60 CM).结果显示实验期内生态综合养殖池塘沉积作用分别占n、P营养元素输出的2.2%和5.8%(质量分数).Deposition in aquaculture areas of an Integrated Multi-trophic Aquaculture(IMTA) Pond in Yunxiao and Zhangzhou was studied by sediment traps which were used to collect sediment.By studing the biodeposition of Sinonovacula constrzcta by indoor simulation experiments, and analysing the amount of NO3--N,NO2--N,NH4 +-N,PO4 3--P of the overlying and interstitial water in the IMTA Pond at the same time.The fluxes of dissolved inorganic N,P from the sediments were estimated by the Fick's first law.The estimation results show that the average daily deposition rate of particulate of the algae pool is 44.59 g/m2, while in the shellfish pool the data is 14.01g/m2.The total net deposition of N and P in the experimental period(90 d) is 6061.5 g and 3411 g(pool area is 0.5 hm2; pool depth is 50 ~60 cm).The results show that the nutrient N and P contributed by seepage took part about 2.2% and 5.8% of the whole output.世界自然基金会(香港)华南湿地项目资

Quantifying Effect of Intraplaque Hemorrhage on Critical Plaque Wall Stress in Human Atherosclerotic Plaques Using Three-Dimensional Fluid-Structure Interaction Models

NSF [DMS-0540684]; NIH [R01 EB004759]; National Natural Science Foundation of China [31100670, 11071203]; Natural Science Foundation of Fujian Province of China [2011J05008]; Fundamental Research Funds for the Central Universities [2012121003]Recent magnetic resonance studies have indicated that intraplaque hemorrhage (IPH) may accelerate plaque progression and play an important role in plaque destabilization. However, the impact of hemorrhage on critical plaque wall stress (CPWS) and strain (CPWSn) has yet to be determined. The objective of this study was to assess the effect of the presence and size of IPH on wall mechanics. The magnetic resonance image (MRI) of one patient with histology-confirmed IPH was used to build eight 3D fluid-structure interaction (FSI) models by altering the dimensions of the existing IPH. As a secondary end point, the combined effect of IPH and fibrous cap thickness (FCT) was assessed. A volume curve fitting method (VCFM) was applied to generate a mesh that would guarantee numerical convergence. Plaque wall stress (PWS), strain (PWSn), and flow shear stress (FSS) were extracted from all nodal points on the lumen surface for analysis. Keeping other conditions unchanged, the presence of intraplaque hemorrhage caused a significant increase (27.5%) in CPWS; reduced FCT caused an increase of 22.6% of CPWS. Similar results were found for CPWSn. Furthermore, combination of IPH presence, reduced FCT, and increased IPH volume caused an 85% and 75% increase in CPWS and CPWSn, respectively. These results show that intraplaque hemorrhage has considerable impact on plaque stress and strain conditions and accurate quantification of IPH could lead to more accurate assessment of plaque vulnerability. Large-scale studies are needed to further validate our findings. [DOI: 10.1115/1.4007954

Sudden death in coronary artery disease are associated with high 3D critical plaque wall stress: A 3D multi-patient fsi study based on EX vivo MRI of coronary plaques

Conference Name:ASME 2013 Summer Bioengineering Conference, SBC 2013. Conference Address: Sunriver, OR, United states. Time:June 26, 2013 - June 29, 2013.Bioengineering Divisio

Higher critical plaque wall stress in patients who died of coronary artery disease compared with those who died of other causes: A 3D FSI study based on ex vivo MRI of coronary plaques

NSF [DMS-0540684]; NIH [R01 EB004759]; National Natural Science Foundation of China [31100670, 2011J05008]; Fundamental Research Funds for the Central Universities [2012121003]; National Natural Sciences Foundation of China [11171030]Mechanical forces play an important role in the rupture of vulnerable plaques. This process is often associated with cardiovascular syndromes, such as heart attack and stroke. In this study, magnetic resonance imaging (MRI)-based models were used to investigate the association between plaque wall stress (PWS) and coronary artery disease (CAD). Ex vivo MRI data of coronary plaques from 12 patients were used to construct 12 three-dimensional (3D) fluid-structure interaction (FSI) computational models. Six of the patients had died from CAD and six had died from non-CAD causes. PWS was assessed using all nodal points on the lumen surface of each plaque. The maximum PWS from all possible vulnerable sites of each plaque was defined as the 3D critical plaque wall stress (CPWS). Mean 3D CPWS in the CAD group was 94.3% higher than that in the non-CAD group (265.6 vs. 136.7 kPa, P=0.0029). There was no statistically significant difference in global maximum plaque wall stress (GMPWS) between the two groups (P=0.347). There was also no statistically significant difference in plaque burden between the CAD group (84.4 +/- 5%) and the non-CAD group (82.0 +/- 8%, P=0.552). The results indicate that plaques from patients who died from CAD were associated with higher CPWS compared with those from patients who died from non-CAD causes. With further validation, analysis of CPWS may prove to be an important component in assessment of plaque vulnerability. (C) 2013 Elsevier Ltd. All rights reserved

Arterial luminal curvature and fibrous-cap thickness affect critical stress conditions within atherosclerotic plaque: An in vivo MRI-based 2D finite-element study

High mechanical stress in atherosclerotic plaques at vulnerable sites, called critical stress, contributes to plaque rupture. The site of minimum fibrous cap (FC) thickness (FCMIN) and plaque shoulder are well-documented vulnerable sites. The inherent weakness of the FC material at the thinnest point increases the stress, making it vulnerable, and it is the big curvature of the lumen contour over FC which may result in increased plaque stress. We aimed to assess critical stresses at FCMIN and the maximum lumen curvature over FC (LCMAX) and quantify the difference to see which vulnerable site had the highest critical stress and was, therefore, at highest risk of rupture. One hundred patients underwent high resolution carotid magnetic resonance (MR) imaging. We used 352 MR slices with delineated atherosclerotic components for the simulation study. Stresses at all the integral nodes along the lumen surface were calculated using the finite-element method. FCMIN and LCMAX were identified, and critical stresses at these sites were assessed and compared. Critical stress at FC MIN was significantly lower than that at LCMAX (median: 121.55 kPa; inter quartile range (IQR) = [60.70-180.32] kPa vs. 150.80 kPa; IQR = [91.39-235.75] kPa, p &lt; 0.0001). If critical stress at FCMIN was only used, then the stress condition of 238 of 352 MR slices would be underestimated, while if the critical stress at LCMAX only was used, then 112 out of 352 would be underestimated. Stress analysis at FCMIN and LCMAX should be used for a refined mechanical risk assessment of atherosclerotic plaques, since material failure at either site may result in rupture

Diagnostic moléculaire des infections neuro-méningées à parechovirus (étude rétrospective sur 5 ans)

PARIS-BIUP (751062107) / SudocSudocFranceF

Conception, Réalisation et Caractérisation de papiers fonctionnels pour des applications de filtrage électromagnétique

Le brouillard électromagnétique dans lequel nous vivons en permanence estaujourd hui montré du doigt car, outre les risques sanitaires qu il pourrait engendrer, illimite l usage de certaines technologies. L importance des interférences entre réseauxsans fil, ou la peur du piratage sur ces mêmes réseaux, en sont deux exemples. Cetravail de thèse vise à développer un nouveau moyen de protection contre certaines deces ondes électromagnétiques. Plus spécifiquement, ce travail se focalise sur unetechnologie capable de filtrer uniquement les ondes WiFi et GSM à travers de grandessurfaces d une habitation, comme un mur. Pour ce faire, la fonctionnalisation d uncomposant standard des bâtiments, le papier-peint, a été étudié.L utilisation de surfaces sélectives en fréquence a été retenue. Ces motifs sontdirectement imprimés sur du papier à l aide d encre conductrice et de la techniqued impression flexographique. L étude s est également portée sur la réalisation de motifsde filtrage innovants. Les résultats de simulation montrent qu ils sont capables de filtrerdeux ou trois bandes, qu ils sont quasiment insensibles à la polarisation et à l angled incidence dans une plage allant de 0 à +- 80. Le travail a ensuite permis dedémontrer la faisabilité pratique de ce concept aux stades laboratoire et industriel.Ensuite, nous avons démontré expérimentalement l efficacité de ce concept dans lesbandes WiFi. La transmission atteint alors -30 dB. Enfin, une validation expérimentaledu produit en situation réelle a été menée, à savoir la pose du papier-peint sur du plâtre,du bois, l influence de la colle ou encore la pose d une couche de papier-peint décoratifpar-dessus le produit.En conclusion, les résultats pratiques obtenus confirment les résultats théoriquesestimés et, permettent à ce nouveau concept, appelé métapapier, d être suffisammentefficace pour permettre la réduction des ondes WiFi ou GSM.Le brouillard électromagnétique dans lequel nous vivons en permanence estaujourd hui montré du doigt car, outre les risques sanitaires qu il pourrait engendrer, illimite l usage de certaines technologies. L importance des interférences entre réseauxsans fil, ou la peur du piratage sur ces mêmes réseaux, en sont deux exemples. Cetravail de thèse vise à développer un nouveau moyen de protection contre certaines deces ondes électromagnétiques. Plus spécifiquement, ce travail se focalise sur unetechnologie capable de filtrer uniquement les ondes WiFi et GSM à travers de grandessurfaces d une habitation, comme un mur. Pour ce faire, la fonctionnalisation d uncomposant standard des bâtiments, le papier-peint, a été étudié.L utilisation de surfaces sélectives en fréquence a été retenue. Ces motifs sontdirectement imprimés sur du papier à l aide d encre conductrice et de la techniqued impression flexographique. L étude s est également portée sur la réalisation de motifsde filtrage innovants. Les résultats de simulation montrent qu ils sont capables de filtrerdeux ou trois bandes, qu ils sont quasiment insensibles à la polarisation et à l angled incidence dans une plage allant de 0 à +- 80. Le travail a ensuite permis dedémontrer la faisabilité pratique de ce concept aux stades laboratoire et industriel.Ensuite, nous avons démontré expérimentalement l efficacité de ce concept dans lesbandes WiFi. La transmission atteint alors -30 dB. Enfin, une validation expérimentaledu produit en situation réelle a été menée, à savoir la pose du papier-peint sur du plâtre,du bois, l influence de la colle ou encore la pose d une couche de papier-peint décoratifpar-dessus le produit.En conclusion, les résultats pratiques obtenus confirment les résultats théoriquesestimés et, permettent à ce nouveau concept, appelé métapapier, d être suffisammentefficace pour permettre la réduction des ondes WiFi ou GSM.SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

中国植物应答环境变化研究的过去与未来

中华人民共和国建国70周年,特别是改革开放40年以来,中国科技工作者在植物研究领域取得了举世瞩目的成绩.这篇综述简要地总结了中国植物学家以模式植物拟南芥,以及水稻、玉米、小麦和棉花等农作物为研究材料,在植物应答非生物逆境胁迫,包括干旱、高温、低温、盐碱、重金属、铝毒害和光胁迫等领域的基础研究和应用成果;同时也提出了植物非生物逆境研究领域亟待解决的重大问题、作物稳产分子设计的重大需求和创制耐受多种逆境环境的绿色新种质的可能性