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1

Mechanisms of plaque formation and rupture.  

PubMed

Atherosclerosis causes clinical disease through luminal narrowing or by precipitating thrombi that obstruct blood flow to the heart (coronary heart disease), brain (ischemic stroke), or lower extremities (peripheral vascular disease). The most common of these manifestations is coronary heart disease, including stable angina pectoris and the acute coronary syndromes. Atherosclerosis is a lipoprotein-driven disease that leads to plaque formation at specific sites of the arterial tree through intimal inflammation, necrosis, fibrosis, and calcification. After decades of indolent progression, such plaques may suddenly cause life-threatening coronary thrombosis presenting as an acute coronary syndrome. Most often, the culprit morphology is plaque rupture with exposure of highly thrombogenic, red cell-rich necrotic core material. The permissive structural requirement for this to occur is an extremely thin fibrous cap, and thus, ruptures occur mainly among lesions defined as thin-cap fibroatheromas. Also common are thrombi forming on lesions without rupture (plaque erosion), most often on pathological intimal thickening or fibroatheromas. However, the mechanisms involved in plaque erosion remain largely unknown, although coronary spasm is suspected. The calcified nodule has been suggested as a rare cause of coronary thrombosis in highly calcified and tortious arteries in older individuals. To characterize the severity and prognosis of plaques, several terms are used. Plaque burden denotes the extent of disease, whereas plaque activity is an ambiguous term, which may refer to one of several processes that characterize progression. Plaque vulnerability describes the short-term risk of precipitating symptomatic thrombosis. In this review, we discuss mechanisms of atherosclerotic plaque initiation and progression; how plaques suddenly precipitate life-threatening thrombi; and the concepts of plaque burden, activity, and vulnerability. PMID:24902970

Bentzon, Jacob Fog; Otsuka, Fumiyuki; Virmani, Renu; Falk, Erling

2014-06-01

2

Thermal detection of cellular infiltrates in living atherosclerotic plaques: possible implications for plaque rupture and thrombosis  

Microsoft Academic Search

SummaryBackground Atherosclerotic lesions are heterogeneous and prognosis cannot easily be predicted, even with intracoronary ultrasound and angioscopy. Serial angiographic and necropsy studies suggest that the risk of plaque rupture correlates only weakly with the degree of stenosis. Most ruptured plaques are characterised by a large pool of cholesterol or necrotic debris and a thin fibrous cap with a dense infiltration

W. Casscells; W. K. Vaughn; H. McAllister; J. T. Willerson; B. Hathorn; M. David; T. Krabach; G. Bearman

1996-01-01

3

Plaque rupture with severe pre-existing stenosis precipitating coronary thrombosis. Characteristics of coronary atherosclerotic plaques underlying fatal occlusive thrombi  

Microsoft Academic Search

Ruptured atheromatous plaques were identified by step-sectioning technique as responsible for 40 of 51 recent coronary artery thrombi and 63 larger intimal haemorrhages. The degree of pre-existing luminal narrowing at the site of rupture was decisive for whether plaque rupture caused occlusive thrombosis or just intimal haemorrhage. If the pre-existing stenosis was greater than 90% (histologically determined) then plaque rupture

E Falk

1983-01-01

4

Optical measurement of arterial mechanical properties: from atherosclerotic plaque initiation to rupture  

NASA Astrophysics Data System (ADS)

During the pathogenesis of coronary atherosclerosis, from lesion initiation to rupture, arterial mechanical properties are altered by a number of cellular, molecular, and hemodynamic processes. There is growing recognition that mechanical factors may actively drive vascular cell signaling and regulate atherosclerosis disease progression. In advanced plaques, the mechanical properties of the atheroma influence stress distributions in the fibrous cap and mediate plaque rupture resulting in acute coronary events. This review paper explores current optical technologies that provide information on the mechanical properties of arterial tissue to advance our understanding of the mechanical factors involved in atherosclerosis development leading to plaque rupture. The optical approaches discussed include optical microrheology and traction force microscopy that probe the mechanical behavior of single cell and extracellular matrix components, and intravascular imaging modalities including laser speckle rheology, optical coherence elastography, and polarization-sensitive optical coherence tomography to measure the mechanical properties of advanced coronary lesions. Given the wealth of information that these techniques can provide, optical imaging modalities are poised to play an increasingly significant role in elucidating the mechanical aspects of coronary atherosclerosis in the future.

Nadkarni, Seemantini K.

2013-12-01

5

Bacteria present in carotid arterial plaques are found as biofilm deposits which may contribute to enhanced risk of plaque rupture.  

PubMed

Atherosclerosis, a disease condition resulting from the buildup of fatty plaque deposits within arterial walls, is the major underlying cause of ischemia (restriction of the blood), leading to obstruction of peripheral arteries, congestive heart failure, heart attack, and stroke in humans. Emerging research indicates that factors including inflammation and infection may play a key role in the progression of atherosclerosis. In the current work, atherosclerotic carotid artery explants from 15 patients were all shown to test positive for the presence of eubacterial 16S rRNA genes. Density gradient gel electrophoresis of 5 of these samples revealed that each contained 10 or more distinct 16S rRNA gene sequences. Direct microscopic observation of transverse sections from 5 diseased carotid arteries analyzed with a eubacterium-specific peptide nucleic acid probe revealed these to have formed biofilm deposits, with from 1 to 6 deposits per thin section of plaque analyzed. A majority, 93%, of deposits was located proximal to the internal elastic lamina and associated with fibrous tissue. In 6 of the 15 plaques analyzed, 16S rRNA genes from Pseudomonas spp. were detected. Pseudomonas aeruginosa biofilms have been shown in our lab to undergo a dispersion response when challenged with free iron in vitro. Iron is known to be released into the blood by transferrin following interaction with catecholamine hormones, such as norepinephrine. Experiments performed in vitro showed that addition of physiologically relevant levels of norepinephrine induced dispersion of P. aeruginosa biofilms when grown under low iron conditions in the presence but not in the absence of physiological levels of transferrin. Importance: The association of bacteria with atherosclerosis has been only superficially studied, with little attention focused on the potential of bacteria to form biofilms within arterial plaques. In the current work, we show that bacteria form biofilm deposits within carotid arterial plaques, and we demonstrate that one species we have identified in plaques can be stimulated in vitro to undergo a biofilm dispersion response when challenged with physiologically relevant levels of norepinephrine in the presence of transferrin. Biofilm dispersion is characterized by the release of bacterial enzymes into the surroundings of biofilm microcolonies, allowing bacteria to escape the biofilm matrix. We believe these enzymes may have the potential to damage surrounding tissues and facilitate plaque rupture if norepinephrine is able to stimulate biofilm dispersion in vivo. This research, therefore, suggests a potential mechanistic link between hormonal state and the potential for heart attack and stroke. PMID:24917599

Lanter, Bernard B; Sauer, Karin; Davies, David G

2014-01-01

6

Detection of plaque rupture using 64-slice multidetector row computed tomography  

PubMed Central

The present case report describes a 37-year-old man who presented to the emergency room with symptoms of a myocardial infarction but no high-grade stenosis on conventional catheter angiography. Consecutive multi-detector row computed tomography of the coronary arteries showed an intimal flap along a fibrous plaque formation in the left anterior descending artery. This finding was found to represent a plaque rupture, and the lesion was treated with an 18 mm stent. Multidetector row computed tomography helped to correctly position the stent by identifying the exact location of the rupture along the long plaque formation.

Reimann, Anja J; Beck, Torsten; Heuschmid, Martin; Brodoefel, Harald; Burgstahler, Christof; Schroder, Stephen; Kopp, Andreas F

2008-01-01

7

Emergence of dendritic cells in rupture-prone regions of vulnerable carotid plaques.  

PubMed

Dendritic cells (DC), which are critically involved in various immunological disorders, were detected in atherosclerotic plaques in 1995. Since DC might be related to the immunological processes in atherosclerosis (AS), we analyzed the emergence of DC and other inflammatory cells in different stages of AS. Serial cross-sections of 44 carotid specimens were immunohistochemically analyzed for the presence of DC, T cells, macrophages, and HLA-DR. Atherosclerotic specimens were histologically defined as initial lesions, advanced stable, or vulnerable plaques. In initial lesions significantly lower DC numbers were detected than in advanced plaques (P < 0.001). For advanced plaques, DC numbers were significantly higher in vulnerable than in stable plaques (P = 0.005). In contrast to initial lesions, approximately 70% of DC in advanced plaques exhibited a mature phenotype (CD83+, DC-LAMP+), indicating a functional activity of DC. In plaques of patients with acute ischemic symptoms DC numbers were markedly elevated (P = 0.03), whereas significantly lower DC numbers and more often a stable plaque morphology were detected in statin-treated patients (P = 0.02). DC clusters with a strong HLA-DR expression and frequent DC-T cell contacts were located particularly in the rupture-prone plaque regions and at complications. The results of the present study indicate that DC might contribute to plaque destabilization through an activation of T cells. PMID:15306181

Yilmaz, Atilla; Lochno, Marlene; Traeg, Friedemann; Cicha, Iwona; Reiss, Christine; Stumpf, Christian; Raaz, Dorette; Anger, Thomas; Amann, Kerstin; Probst, Thomas; Ludwig, Josef; Daniel, Werner G; Garlichs, Christoph D

2004-09-01

8

Multiple Atherosclerotic Plaque Rupture in Acute Coronary Syndrome: A Three-Vessel Intravascular Ultrasound Study  

Microsoft Academic Search

Background—To test the hypothesis of general atherosclerotic plaque destabilization during acute coronary syndrome (ACS), the present study sought to analyze the 3 coronary arteries by systematic intravascular ultrasound scan (IVUS). Methods and Results—Seventy-two arteries were explored in 24 patients referred for percutaneous coronary intervention after a first ACS with troponin I elevation. Fifty plaque ruptures (mean, 2.08 per patient; range,

G. Rioufol; G. Finet; I. Ginon; X. André-Fouët; R. Rossi; E. Vialle; E. Desjoyaux; G. Convert; J. F. Huret; A. Tabib

2002-01-01

9

Plaque Rupture is a Determinant of Vascular Events in Carotid Artery Atherosclerotic Disease: Involvement of Matrix Metalloproteinases 2 and 9  

PubMed Central

Background and Purpose Unstable carotid atherosclerotic plaques are characterized by cap rupture, leading to thromboembolism and stroke. Matrix metalloproteinases (MMPs) have been implicated in the progression of atherosclerosis and plaque rupture. The aim of this study was to assess the relationship between the expressions of MMP-2 and MMP-9 and carotid plaque instability. Methods Eighty atherosclerotic plaques were collected from 74 patients undergoing carotid endarterectomy. Clinical information was obtained from each patient, and plaque morphology was examined at the macroscopic and microscopic levels. The immunohistochemical expressions of MMPs were graded using semiquantitative scales. Results Macroscopic ulceration (84.6% versus 63.4%, p=0.042) and microscopic cap rupture (79.5% versus 51.2%, p=0.010) were more common in symptomatic than in asymptomatic patients. Immunoreactivities of MMP-2 and MMP-9 were increased in 40 and 36 atheromatous plaques, respectively. Macroscopic ulceration was strongly correlated with the expressions of MMP-2 (p<0.001) and MMP-9 (p=0.001). There were significant correlations between increased MMP-2 expression and cap rupture (p=0.002), intraplaque hemorrhage (p=0.039), and a thin fibrous cap (p=0.002), and between increased MMP-9 expression and cap rupture (p=0.010) and a large lipid core (p=0.013). Conclusions Plaque rupture was significantly associated with the development of vascular events in carotid atherosclerotic disease. MMP-2 and MMP-9 are strongly correlated with plaque instability.

Heo, Sung Hyuk; Cho, Chang-Hoon; Kim, Hye Ok; Jo, Yong Hwa; Lee, Ju Hie; Park, Ju-Cheol; Park, Key Chung; Ahn, Tae-Beom; Chung, Kyung Cheon; Chang, Dae-Il

2011-01-01

10

Developing a Rabbit Model of Neointimal Stenosis and Atherosclerotic Fibrous Plaque Rupture  

PubMed Central

Background A precise understanding of the mechanism of human neointimal stenoses and atherosclerotic fibrous plaques, which give rise to thromboses in vital arteries, requires a suitable animal model that would mimic the same characteristics well. We developed a rabbit model of neointimal stenosis and fibrotic plaque rupture in the carotid artery to visualize the lesion progress and to characterize the lesion types according to the American Heart Association classification. Methods Twenty-eight healthy male New Zealand white rabbits were randomly divided into two groups: The rabbits in group A (n = 14) consumed a standard chow diet, and those in group B (n = 14) were injured via perivascular cold injury using liquid nitrogen at the right common carotid artery before being fed a high cholesterol diet (1.5%) for eight weeks. Plasma lipid evaluation was performed before the sacrificing of the rabbits. At the end of every week, at least 1 rabbit from group B was sacrificed for an analysis of lesion histopathology and calculation of the area ratios of the intima to media. Results The plasma lipid level in group B was significantly higher than that in group A (p value < 0.05). The histopathological results revealed atherosclerosis characteristics such as endothelial layer destruction, fatty streaks and lipid-containing macrophages (foam cells) formation in the intima and media layers, extracellular lipid collections, smooth muscle cells proliferation and migration, neointima formation, intima thickening and deformation, fibrotic plaque formation, and finally plaque rupture. Statistical analysis revealed a significant increase in the intima-to-media ratio at the end of the eighth week (6.41 ± 0.27, p value < 0.05). Conclusion We successfully developed a rabbit model of neointimal stenosis and atherosclerotic fibrous connective tissue plaque rupture, which is not only quickly and easily reproducible and inexpensive but also without mortality. The merits of our model render the evaluation of neointimal stenoses and fibrotic plaques and their treatment strategies more feasible in humans.

Mehrad, Hossein; Mokhtari-Dizaji, Manijhe; Ghanaati, Hossein; Shahbazfar, Amir-Ali; Mohsenifar, Afshin

2011-01-01

11

Current status of vulnerable plaque detection.  

PubMed

Critical coronary stenoses have been shown to contribute to only a minority of acute coronary syndromes (ACS) and sudden cardiac death. Autopsy studies have identified a subgroup of high-risk patients with disrupted vulnerable plaque and modest stenosis. Consequently, a clinical need exists to develop methods to identify these plaques prospectively before disruption and clinical expression of disease. Recent advances in invasive and noninvasive imaging techniques have shown the potential to identify these high-risk plaques. The anatomical characteristics of the vulnerable plaque such as thin cap fibroatheroma and lipid pool can be identified with angioscopy, high frequency intravascular ultrasound, intravascular MRI, and optical coherence tomography. Efforts have also been made to recognize active inflammation in high-risk plaques using intravascular thermography. Plaque chemical composition by measuring electromagnetic radiation using spectroscopy is also an emerging technology to detect vulnerable plaques. Noninvasive imaging with MRI, CT, and PET also holds the potential to differentiate between low and high-risk plaques. However, at present none of these imaging modalities are able to detect vulnerable plaque neither has been shown to definitively predict outcome. Nevertheless in contrast, there has been a parallel development in the physiological assessment of advanced atherosclerotic coronary artery disease. Thus recent trials using fractional flow reserve in patients with modest non flow-limiting stenoses have shown that deferral of PCI with optimal medical therapy in these patients is superior to coronary intervention. Further trials are needed to provide more information regarding the natural history of high-risk but non flow-limiting plaque to establish patient-specific targeted therapy and to refine plaque stabilizing strategies in the future. PMID:19670307

Sharif, Faisal; Murphy, Ross T

2010-01-01

12

Elucidating atherosclerotic vulnerable plaque rupture by modeling cross substitution of ApoE-/- mouse and human plaque components stiffnesses.  

PubMed

The structure of mouse atherosclerotic lesions may differ from that of humans, and mouse atherosclerotic plaques do not rupture except in some specific locations such as the brachiocephalic artery. Recently, our group was the first to observe that the amplitudes of in vivo stresses in ApoE-/- mouse aortic atherosclerotic lesions were much lower and differed from those found in a previous work performed on human lesions. In this previous preliminary work, we hypothesized that the plaque mechanical properties (MP) may in turn be responsible for such species differences. However, the limited number of human samples used in our previous comparative study was relevant but not sufficient to broadly validate such hypothesis. Therefore, in this study, we propose an original finite element strategy that reconstructs the in vivo stress/strain (IVS/S) distributions in ApoE-/- artherosclerotic vessels based on cross substitution of ApoE-/- mouse and human plaque components stiffnesses and including residual stress/strain (RS/S). Our results: (1) showed that including RS/S decreases by a factor 2 the amplitude of maximal IVS/S, and more importantly, (2) demonstrated that the MP of the ApoE-/- plaque constituents are mainly responsible for the low level-compared with human-of intraplaque stress in ApoE-/- mouse aortic atherosclerotic lesions (8.36 ± 2.63 kPa vs. 182.25 ± 55.88 kPa for human). Our study highlights that such differences in the distribution and amplitude of vessel wall stress might be one key feature for explaining for the difference in lesion stability between human coronary and mouse aortic lesions. PMID:21986797

Ohayon, Jacques; Mesnier, Nicolas; Broisat, Alexis; Toczek, Jakub; Riou, Laurent; Tracqui, Philippe

2012-07-01

13

Proportion of fibrin and platelets differs in thrombi on ruptured and eroded coronary atherosclerotic plaques in humans  

PubMed Central

Objective: To determine the proportion of platelets and fibrin in coronary thrombi. Design: Immunohistochemical and morphometric means to examine the coronary arteries of 31 patients who died of acute myocardial infarction. Results: Fresh thrombi were detected in the feeding arteries of infarction areas in 23 cases (74%) and were associated with plaque rupture in 18 (78%) and plaque erosion in 5 (22%). An immunohistochemical study showed that the thrombi consisted of a mixture of fibrin and platelets as well as some other types of blood cells. The fibrin and platelet positive areas in the thrombi associated with plaque rupture accounted for 74 (19)% and 35 (20)% (p < 0.01) and those associated with erosion accounted for 51 (6)% and 70 (21)%, respectively, of the total areas. Areas of positive immunoreactivity for tissue factor and C reactive protein were also significantly greater in ruptured than in eroded plaques. Conclusion: These results indicate that the proportions of fibrin and of platelets differ in coronary thrombi on ruptured and eroded plaques. Higher proportions of tissue factor and C reactive protein contribute more significantly to thrombus formation on plaque rupture than on plaque erosion.

Sato, Y; Hatakeyama, K; Yamashita, A; Marutsuka, K; Sumiyoshi, A; Asada, Y

2005-01-01

14

Biomechanical modeling and morphology analysis indicates plaque rupture due to mechanical failure unlikely in atherosclerosis-prone mice  

PubMed Central

Spontaneous plaque rupture in mouse models of atherosclerosis is controversial, although numerous studies have discussed so-called “vulnerable plaque” phenotypes in mice. We compared the morphology and biomechanics of two acute and one chronic murine model of atherosclerosis to human coronaries of the thin-cap fibroatheroma (TCFA) phenotype. Our acute models were apolipoprotein E-deficient (ApoE?/?) and LDL receptor-deficient (LDLr?/?) mice, both fed a high-fat diet for 8 wk with simultaneous infusion of angiotensin II (ANG II), and our chronic mouse model was the apolipoprotein E-deficient strain fed a regular chow diet for 1 yr. We found that the mouse plaques from all three models exhibited significant morphological differences from human TCFA plaques, including the plaque burden, plaque thickness, eccentricity, and amount of the vessel wall covered by lesion as well as significant differences in the relative composition of plaques. These morphological differences suggested that the distribution of solid mechanical stresses in the walls may differ as well. Using a finite-element analysis computational solid mechanics model, we computed the relative distribution of stresses in the walls of murine and human plaques and found that although human TCFA plaques have the highest stresses in the thin fibrous cap, murine lesions do not have such stress distributions. Instead, local maxima of stresses were on the media and adventitia, away from the plaque. Our results suggest that if plaque rupture is possible in mice, it may be driven by a different mechanism than mechanics.

Campbell, Ian C.; Weiss, Daiana; Suever, Jonathan D.; Virmani, Renu; Veneziani, Alessandro; Vito, Raymond P.; Oshinski, John N.

2013-01-01

15

Biomechanical modeling and morphology analysis indicates plaque rupture due to mechanical failure unlikely in atherosclerosis-prone mice.  

PubMed

Spontaneous plaque rupture in mouse models of atherosclerosis is controversial, although numerous studies have discussed so-called "vulnerable plaque" phenotypes in mice. We compared the morphology and biomechanics of two acute and one chronic murine model of atherosclerosis to human coronaries of the thin-cap fibroatheroma (TCFA) phenotype. Our acute models were apolipoprotein E-deficient (ApoE(-/-)) and LDL receptor-deficient (LDLr(-/-)) mice, both fed a high-fat diet for 8 wk with simultaneous infusion of angiotensin II (ANG II), and our chronic mouse model was the apolipoprotein E-deficient strain fed a regular chow diet for 1 yr. We found that the mouse plaques from all three models exhibited significant morphological differences from human TCFA plaques, including the plaque burden, plaque thickness, eccentricity, and amount of the vessel wall covered by lesion as well as significant differences in the relative composition of plaques. These morphological differences suggested that the distribution of solid mechanical stresses in the walls may differ as well. Using a finite-element analysis computational solid mechanics model, we computed the relative distribution of stresses in the walls of murine and human plaques and found that although human TCFA plaques have the highest stresses in the thin fibrous cap, murine lesions do not have such stress distributions. Instead, local maxima of stresses were on the media and adventitia, away from the plaque. Our results suggest that if plaque rupture is possible in mice, it may be driven by a different mechanism than mechanics. PMID:23203971

Campbell, Ian C; Weiss, Daiana; Suever, Jonathan D; Virmani, Renu; Veneziani, Alessandro; Vito, Raymond P; Oshinski, John N; Taylor, W Robert

2013-02-01

16

In Vivo Detection of Activated Platelets Allows Characterizing Rupture of Atherosclerotic Plaques with Molecular Magnetic Resonance Imaging in Mice  

PubMed Central

Background Early and non-invasive detection of platelets on micro atherothrombosis provides a means to identify unstable plaque and thereby allowing prophylactic treatment towards prevention of stroke or myocardial infarction. Molecular magnetic resonance imaging (mMRI) of activated platelets as early markers of plaque rupture using targeted contrast agents is a promising strategy. In this study, we aim to specifically image activated platelets in murine atherothrombosis by in vivo mMRI, using a dedicated animal model of plaque rupture. Methods An antibody targeting ligand-induced binding sites (LIBS) on the glycoprotein IIb/IIIa-receptor of activated platelets was conjugated to microparticles of iron oxide (MPIO) to form the LIBS-MPIO contrast agent causing a signal-extinction in T2*-weighted MRI. ApoE?/? mice (60 weeks-old) were fed a high fat diet for 5 weeks. Using a small needle, the surface of their carotid plaques was scratched under blood flow to induce atherothrombosis. In vivo 9.4 Tesla MRI was performed before and repetitively after intravenous injection of either LIBS-MPIO versus non-targeted-MPIO. Results LIBS-MPIO injected animals showed a significant signal extinction (p<0.05) in MRI, corresponding to the site of plaque rupture and atherothrombosis in histology. The signal attenuation was effective for atherothrombosis occupying ?2% of the vascular lumen. Histology further confirmed significant binding of LIBS-MPIO compared to control-MPIO on the thrombus developing on the surface of ruptured plaques (p<0.01). Conclusion in vivo mMRI detected activated platelets on mechanically ruptured atherosclerotic plaques in ApoE?/? mice with a high sensititvity. This imaging technology represents a unique opportunity for noninvasive detection of atherothrombosis and the identification of unstable atherosclerotic plaques with the ultimate promise to prevent strokes and myocardial infarctions.

Wiens, Kristina; Neudorfer, Irene; Zirlik, Andreas; Meissner, Mirko; Tilly, Peg; Charles, Anne-Laure; Bode, Christoph; Peter, Karlheinz; Fabre, Jean-Etienne

2012-01-01

17

A mechanistic analysis of the role of microcalcifications in atherosclerotic plaque stability: potential implications for plaque rupture  

PubMed Central

The role of microcalcifications (?Calcs) in the biomechanics of vulnerable plaque rupture is examined. Our laboratory previously proposed (Ref. 44), using a very limited tissue sample, that ?Calcs embedded in the fibrous cap proper could significantly increase cap instability. This study has been greatly expanded. Ninety-two human coronary arteries containing 62 fibroatheroma were examined using high-resolution microcomputed tomography at 6.7-?m resolution and undecalcified histology with special emphasis on calcified particles <50 ?m in diameter. Our results reveal the presence of thousands of ?Calcs, the vast majority in lipid pools where they are not dangerous. However, 81 ?Calcs were also observed in the fibrous caps of nine of the fibroatheroma. All 81 of these ?Calcs were analyzed using three-dimensional finite-element analysis, and the results were used to develop important new clinical criteria for cap stability. These criteria include variation of the Young's modulus of the ?Calc and surrounding tissue, ?Calc size, and clustering. We found that local tissue stress could be increased fivefold when ?Calcs were closely spaced, and the peak circumferential stress in the thinnest nonruptured cap (66 ?m) if no ?Calcs were present was only 107 kPa, far less than the proposed minimum rupture threshold of 300 kPa. These results and histology suggest that there are numerous ?Calcs < 15 ?m in the caps, not visible at 6.7-?m resolution, and that our failure to find any nonruptured caps between 30 and 66 ?m is a strong indication that many of these caps contained ?Calcs.

Maldonado, Natalia; Kelly-Arnold, Adreanne; Vengrenyuk, Yuliya; Laudier, Damien; Fallon, John T.; Virmani, Renu; Cardoso, Luis

2012-01-01

18

Infections and atheromatous plaque: current therapeutic implications.  

PubMed

Infections are the most common inflammatory triggers and acute and chronic infections have been associated with the development and progression of atherosclerotic disease raising interest in the infectious hypothesis of atherosclerosis. Pathogens have been identified in atherosclerotic plaques and large epidemiological studies have documented conflicting associations between serological evidence of infection and cardiovascular events. Influenza A was mostly studied as a trigger for cardiovascular events during winter months, whilst cytomegalovirus, Chlamydia pneumoniae, helicobacter pylori and porphyromonas ginigivalis were the most studied chronic pathogens which had been associated with the development and progression of cardiovascular disease. Infectious agents can contribute to atherosclerosis by having a direct effect on the vascular wall or via indirect effects including inflammatory responses and molecular mimicry. Efforts to prevent infection with vaccination or treat specific infectious agents with antibiotics have provided mostly negative results, thereby challenging the validity of the infectious hypothesis of atherosclerosis. PMID:23016720

Charakida, Marietta; Tousoulis, Dimitris

2013-01-01

19

Bacteria Present in Carotid Arterial Plaques Are Found as Biofilm Deposits Which May Contribute to Enhanced Risk of Plaque Rupture  

PubMed Central

ABSTRACT Atherosclerosis, a disease condition resulting from the buildup of fatty plaque deposits within arterial walls, is the major underlying cause of ischemia (restriction of the blood), leading to obstruction of peripheral arteries, congestive heart failure, heart attack, and stroke in humans. Emerging research indicates that factors including inflammation and infection may play a key role in the progression of atherosclerosis. In the current work, atherosclerotic carotid artery explants from 15 patients were all shown to test positive for the presence of eubacterial 16S rRNA genes. Density gradient gel electrophoresis of 5 of these samples revealed that each contained 10 or more distinct 16S rRNA gene sequences. Direct microscopic observation of transverse sections from 5 diseased carotid arteries analyzed with a eubacterium-specific peptide nucleic acid probe revealed these to have formed biofilm deposits, with from 1 to 6 deposits per thin section of plaque analyzed. A majority, 93%, of deposits was located proximal to the internal elastic lamina and associated with fibrous tissue. In 6 of the 15 plaques analyzed, 16S rRNA genes from Pseudomonas spp. were detected. Pseudomonas aeruginosa biofilms have been shown in our lab to undergo a dispersion response when challenged with free iron in vitro. Iron is known to be released into the blood by transferrin following interaction with catecholamine hormones, such as norepinephrine. Experiments performed in vitro showed that addition of physiologically relevant levels of norepinephrine induced dispersion of P. aeruginosa biofilms when grown under low iron conditions in the presence but not in the absence of physiological levels of transferrin.

Lanter, Bernard B.; Sauer, Karin

2014-01-01

20

In vivo MRI-based simulation of fatigue process: a possible trigger for human carotid atherosclerotic plaque rupture  

PubMed Central

Background Atherosclerotic plaque is subjected to a repetitive deformation due to arterial pulsatility during each cardiac cycle and damage may be accumulated over a time period causing fibrous cap (FC) fatigue, which may ultimately lead to rupture. In this study, we investigate the fatigue process in human carotid plaques using in vivo carotid magnetic resonance (MR) imaging. Method Twenty seven patients with atherosclerotic carotid artery disease were included in this study. Multi-sequence, high-resolution MR imaging was performed to depict the plaque structure. Twenty patients were found with ruptured FC or ulceration and 7 without. Modified Paris law was used to govern crack propagation and the propagation direction was perpendicular to the maximum principal stress at the element node located at the vulnerable site. Results The predicted crack initiations from 20 patients with FC defect all matched with the locations of the in vivo observed FC defect. Crack length increased rapidly with numerical steps. The natural logarithm of fatigue life decreased linearly with the local FC thickness (R2?=?0.67). Plaques (n=7) without FC defect had a longer fatigue life compared with those with FC defect (p?=?0.03). Conclusion Fatigue process seems to explain the development of cracks in FC, which ultimately lead to plaque rupture.

2013-01-01

21

Drug Therapies to Prevent Coronary Plaque Rupture and Erosion: Present and Future  

Microsoft Academic Search

Patients at high risk for coronary heart disease usually have a number of atherosclerotic plaques in their coronary arteries. Some plaques grow inward and, once they have caused a critical degree of luminal stenosis, lead to chronic anginal symptoms. Other plaques grow outward and remain silent unless they disrupt and trigger an acute coronary event. Either type of plaque may

P. T. Kovanen; M. Mäyränpää; K. A. Lindstedt

22

Stabilizing Role of Platelet P2Y12 Receptors in Shear-Dependent Thrombus Formation on Ruptured Plaques  

Microsoft Academic Search

BackgroundIn most models of experimental thrombosis, healthy blood vessels are damaged. This results in the formation of a platelet thrombus that is stabilized by ADP signaling via P2Y12 receptors. However, such models do not predict involvement of P2Y12 in the clinically relevant situation of thrombosis upon rupture of atherosclerotic plaques. We investigated the role of P2Y12 in thrombus formation on

Reyhan Nergiz-Unal; Judith M. E. M. Cosemans; Marion A. H. Feijge; Paola E. J. van der Meijden; Robert F. Storey; J. J. J. van Giezen; Mirjam G. A. Oude Egbrink; Johan W. M. Heemskerk; Marijke J. E. Kuijpers; Yu Wang

2010-01-01

23

The ruptured Achilles tendon: a current overview from biology of rupture to treatment.  

PubMed

The Achilles tendon (AT) is the most frequently ruptured tendon in the human body yet the aetiology remains poorly understood. Despite the extensively published literature, controversy still surrounds the optimum treatment of complete rupture. Both non-operative management and percutaneous repair are attractive alternatives to open surgery, which carries the highest complication and cost profile. However, the lack of a universally accepted scoring system has limited any evaluation of treatment options. A typical UK district general hospital treats approximately 3 cases of AT rupture a month. It is therefore important for orthopaedic surgeons to correctly diagnose and treat these injuries with respect to the best current evidence-based practice. In this review article, we discuss the relevant pathophysiology and diagnosis of the ruptured AT and summarize the current evidence for treatment. PMID:23546858

Thevendran, G; Sarraf, K M; Patel, N K; Sadri, A; Rosenfeld, P

2013-04-01

24

Intravascular Modalities for Detection of Vulnerable Plaque Current Status  

Microsoft Academic Search

Progress in the diagnosis, treatment, and prevention of atherosclerotic coronary artery disease is dependent on a greater understanding of the mechanisms of coronary plaque progression. Autopsy studies have characterized a subgroup of high-risk, or vulnerable, plaques that result in acute coronary syndromes or sudden cardiac death. These angiographically modest plaques share certain pathologic characteristics: a thin, fibrous cap, lipid-rich core,

Briain D. MacNeill; Harry C. Lowe; Masamichi Takano; Valentin Fuster; Ik-Kyung Jang

25

Magnetic resonance imaging of vulnerable atherosclerotic plaques: current imaging strategies and molecular imaging probes.  

PubMed

The vulnerability or destabilization of atherosclerotic plaques has been directly linked to plaque composition. Imaging modalities, such as magnetic resonance (MR) imaging, that allow for evaluation of plaque composition at a cellular and molecular level, could further improve the detection of vulnerable plaque and may allow for monitoring the efficacy of antiatherosclerotic therapies. In this review we focus on MR imaging strategies for the detection and evaluation of atherosclerotic plaques and their composition. We highlight recent advancements in the development of MR pulse sequences, computer image analysis, and the use of commercially available MR contrast agents, such as gadopentic acid (Gd-DTPA), for plaque characterization. We also discuss molecular imaging strategies that are currently being used to design specific imaging probes targeted to biochemical and cellular markers of atherosclerotic plaque vulnerability. PMID:17729343

Briley-Saebo, Karen C; Mulder, Willem J M; Mani, Venkatesh; Hyafil, Fabien; Amirbekian, Vardan; Aguinaldo, Juan Gilberto S; Fisher, Edward A; Fayad, Zahi A

2007-09-01

26

Atherosclerosis and Atheroma Plaque Rupture: Normal Anatomy of Vasa Vasorum and Their Role Associated with Atherosclerosis  

PubMed Central

Atherosclerosis is primarily a degenerative disorder related to aging with a chronic inflammatory component. There are differences in expression among different vascular beds, inflicting a range of vascular diseases. The majority of studies focus on the inner and medial vascular layers, which are affected at the development of atherosclerosis. Recent evidence shows that the outer layer of blood vessels, composed of the adventitial layer and the vasa vasorum, not only plays a significant role in maintaining vessel integrity, but also reacts to atheroma. What is not clear is the extent of contribution of the outer layer to the process of atherosclerosis. Is it involved in the initiation, progression, and clinical expression of atheroma? Is the inflammation associated with atheroma limited to being merely reactive or is there a proactive element? This paper provides an overview of the normal anatomy of vasa vasorum and potential mechanism of plaque formation due to vascular injury (vasa vasorum) and microhemorrhage.

2014-01-01

27

Evaluation of Fibrous Cap Rupture of Atherosclerotic Carotid Plaque with Thin-Slice Source Images of Time-of-Flight MR Angiography  

PubMed Central

Objective: To investigate the ability of source image of time-of-flight magnetic resonance angiography (TOF-MRA) in the detection of fibrous cap rupture of atherosclerotic carotid plaques. Materials and Methods: From the database of radiological information in our hospital, 35 patients who underwent carotid MR imaging and subsequent carotid endoarterectomy within 2 weeks were included in this retrospective study. MR imaging included thin-slice time-of-flight MR angiography, black-blood T1- and T2-weighted imaging. Sensitivity, specificity and accuracy were calculated for the detection of fibrous cap rupture with source image of TOF-MRA. The Cohen k coefficient was also calculated to quantify the degree of concordance of source image of TOF-MRA with histopathological data. Results: Sensitivity, specificity and accuracy in the detection of fibrous cap rupture were 90% (95%CI: 81–98), 69% (95%CI: 56–82) and 79% (95%CI: 71–87) with a k value of 0.59. The false positives (n = 15) were caused by partial-volume averaging between fibrous cap and lumen at the shoulder of carotid plaque. The false negatives (n = 5) were underestimated as partial thinning of fibrous cap. Conclusion: Source image of TOF-MRA can be useful in the detection of fibrous cap rupture with high sensitivity, but further technical improvement should be necessary to overcome shortcomings causing image degradation.

2014-01-01

28

Meshless Generalized Finite Difference Method and Human Carotid Atherosclerotic Plaque Progression Simulation Using Multi-Year MRI Patient-Tracking Data  

PubMed Central

Atherosclerotic plaque rupture and progression have been the focus of intensive investigations in recent years. Plaque rupture is closely related to most severe cardiovascular syndromes such as heart attack and stroke. A computational procedure based on meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Participating patients were scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression. Since there was insufficient data with the current technology to quantify individual plaque component growth, the whole plaque was assumed to be uniform, homogeneous, hyperelastic, isotropic and nearly incompressible. The linear elastic model was used. The 2D plaque model was discretized and solved using a meshless generalized finite difference (GFD) method. Starting from the T2 plaque geometry, plaque progression was simulated by solving the solid model and adjusting wall thickness using plaque growth functions iteratively until T3 is reached. Numerically simulated plaque progression agreed very well with actual plaque geometry at T3 given by MRI data. We believe this is the first time plaque progression simulation based on multi-year patient-tracking data was reported. Serial MRI-based progression simulation adds time dimension to plaque vulnerability assessment and will improve prediction accuracy for potential plaque rupture risk.

Yang, Chun; Tang, Dalin; Yuan, Chun; Kerwin, William; Liu, Fei; Canton, Gador; Hatsukami, Thomas S.; Atluri, Satya

2009-01-01

29

Imaging of the unstable plaque: how far have we got?  

PubMed

Rupture of unstable plaques may lead to myocardial infarction or stroke and is the leading cause of morbidity and mortality in western countries. Thus, there is a clear need for identifying these vulnerable plaques before the rupture occurs. Atherosclerotic plaques are a challenging imaging target as they are small and move rapidly, especially in the coronary tree. Many of the currently available imaging tools for clinical use still provide minimal information about the biological characteristics of plaques, because they are limited with respect to spatial and temporal resolution. Moreover, many of these imaging tools are invasive. The new generation of imaging modalities such as magnetic resonance imaging, nuclear imaging such as positron emission tomography and single photon emission computed tomography, computed tomography, fluorescence imaging, intravascular ultrasound, and optical coherence tomography offer opportunities to overcome some of these limitations. This review discusses the potential of these techniques for imaging the unstable plaque. PMID:19833636

Matter, Christian M; Stuber, Matthias; Nahrendorf, Matthias

2009-11-01

30

Imaging of the unstable plaque: how far have we got?  

PubMed Central

Rupture of unstable plaques may lead to myocardial infarction or stroke and is the leading cause of morbidity and mortality in western countries. Thus, there is a clear need for identifying these vulnerable plaques before the rupture occurs. Atherosclerotic plaques are a challenging imaging target as they are small and move rapidly, especially in the coronary tree. Many of the currently available imaging tools for clinical use still provide minimal information about the biological characteristics of plaques, because they are limited with respect to spatial and temporal resolution. Moreover, many of these imaging tools are invasive. The new generation of imaging modalities such as magnetic resonance imaging, nuclear imaging such as positron emission tomography and single photon emission computed tomography, computed tomography, fluorescence imaging, intravascular ultrasound, and optical coherence tomography offer opportunities to overcome some of these limitations. This review discusses the potential of these techniques for imaging the unstable plaque.

Matter, Christian M.; Stuber, Matthias; Nahrendorf, Matthias

2009-01-01

31

Current Management of Traumatic Rupture of the Descending Thoracic Aorta  

PubMed Central

Traumatic rupture of the descending thoracic aorta remains a leading cause of death following major blunt trauma. Management has evolved from uniformly performing emergent open repair with clamp and sew technique to include open repair with mechanical circulatory support, medical management and most recently, endovascular repair. This latter approach appears, in the short term, to be associated with perhaps better outcome, but long term data is still accruing. While an attractive option, there are specific anatomic and physiologic factors to be considered in each individual case.

Karmy-Jones, Riyad; Jackson, Nichole; Long, William; Simeone, Alan

2009-01-01

32

Symptomatic and asymptomatic carotid artery plaque  

PubMed Central

Carotid atherosclerotic plaques represent both stable and unstable atheromatous lesions. Atherosclerotic plaques that are prone to rupture owing to their intrinsic composition such as a large lipid core, thin fibrous cap and intraplaque hemorrhage are associated with subsequent thromboembolic ischemic events. At least 15–20% of all ischemic strokes are attributable to carotid artery atherosclerosis. Characterization of plaques may enhance the understanding of natural history and ultimately the treatment of atherosclerotic disease. MRI of carotid plaque and embolic signals during transcranial Doppler have identified features beyond luminal stenosis that are predictive of future transient ischemic attacks and stroke. The value of specific therapies to prevent stroke in symptomatic and asymptomatic patients with severe carotid artery stenosis are the subject of current research and analysis of recently published clinical trials that are discussed in this article.

Mughal, Majid M; Khan, Mohsin K; DeMarco, J Kevin; Majid, Arshad; Shamoun, Fadi; Abela, George S

2011-01-01

33

A comparative study on plaque vulnerability using constitutive equations.  

PubMed

Atherosclerosis is the most serious and common form of cardiovascular disease in which plaque builds up inside the arteries. Peak plaque stress is considered as the main reason for plaque rupture, which results in heart attack and stroke. In the current research, the finite element method is used to anticipate plaque vulnerability, using human samples. A total of 23 healthy and atherosclerotic human coronary arteries (14 healthy and 9 atherosclerotic) were removed within 5 h postmortem. The samples were mounted on a uniaxial tensile test machine and the obtained mechanical properties were used in finite element models. The peak plaque stresses for the Ogden hyperelastic model were compared to the Mooney-Rivlin and Neo-Hookean outcomes. The results indicated that hypocellular plaque in all three models has the highest stress values compared to the cellular and calcified ones and, as a result, is quite prone to rupture. The calcified plaque type, in contrast, has the lowest stress values and remains stable. The results can be used in plaque vulnerability prediction and have clinical implications for interventions and surgeries such as balloon-angioplasty, cardiopulmonary bypass and stenting. PMID:23999817

Karimi, A; Navidbakhsh, M; Faghihi, S

2014-03-01

34

Three-Dimensional Carotid Plaque Progression Simulation Using Meshless Generalized Finite Difference Method Based on Multi-Year MRI Patient-Tracking Data  

PubMed Central

Cardiovascular disease (CVD) is becoming the number one cause of death worldwide. Atherosclerotic plaque rupture and progression are closely related to most severe cardiovascular syndromes such as heart attack and stroke. Mechanisms governing plaque rupture and progression are not well understood. A computational procedure based on three-dimensional meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data was introduced to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Participating patients were scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Vessel wall thickness (WT) changes were used as the measure for plaque progression. Since there was insufficient data with the current technology to quantify individual plaque component growth, the whole plaque was assumed to be uniform, homogeneous, isotropic, linear, and nearly incompressible. The linear elastic model was used. The 3D plaque model was discretized and solved using a meshless generalized finite difference (GFD) method. Four growth functions with different combinations of wall thickness, stress, and neighboring point terms were introduced to predict future plaque growth based on previous time point data. Starting from the T2 plaque geometry, plaque progression was simulated by solving the solid model and adjusting wall thickness using plaque growth functions iteratively until T3 is reached. Numerically simulated plaque progression agreed very well with the target T3 plaque geometry with errors ranging from 11.56%, 6.39%, 8.24%, to 4.45%, given by the four growth functions. We believe this is the first time 3D plaque progression simulation based on multi-year patient-tracking data was reported. Serial MRI-based progression simulation adds time dimension to plaque vulnerability assessment and will improve prediction accuracy for potential plaque rupture risk.

Yang, Chun; Tang, Dalin; Atluri, Satya

2010-01-01

35

Is there a role for coronary angiography in the early detection of the vulnerable plaque?  

PubMed

The identification of the coronary "vulnerable plaque" that is prone to disruption and thrombosis remains a "holy grail" in the treatment of coronary artery disease. The widespread use of coronary angiography for the identification of coronary atherosclerotic disease has led to numerous earlier studies exploring the role of angiography in the early detection of the vulnerable plaque. Some of the angiographic features explored for risk of plaque rupture include the degree of luminal stenosis, presence of plaque calcification, complex lesions with plaque disruption and thrombosis, and coronary artery movement patterns. However, a major limiting factor with coronary angiography is that it is a "luminogram", and provides little characterization of plaque morphology or vessel wall, both of which play an important role in the development of plaque vulnerability. Newer intravascular imaging techniques have been developed to permit more detailed interrogation of plaque morphology and vessel wall, potentially allowing for more accurate detection of plaque vulnerability. Whilst coronary angiography may be increasingly superseded by these advances in imaging technologies, it is likely that it will continue to play an important complementary role in the quest for the early detection of the vulnerable plaque. The prospective identification of the vulnerable plaque currently remains elusive, as definitive tools for its detection do not exist. Hence, further prospective studies on the natural history of the atherosclerotic plaque, as well as validation of imaging modalities in clinical studies are needed before the notion of early detection of the vulnerable plaque becomes a clinical reality. PMID:22289298

Chan, Kim Hoe; Ng, Martin K C

2013-04-15

36

Imaging of the unstable plaque  

Microsoft Academic Search

Atherosclerosis is now considered a systemic inflammatory disorder affecting the arterial tree. Inflammation plays a role in all stages of the disease, from the initiation of the fatty streak to the final stage of plaque rupture. Atherosclerotic plaques that demonstrate the features of active inflammation are more likely to become symptomatic. In addition to having a higher risk of developing

Kiat Tsong Tan; Gregory Y. H. Lip

2008-01-01

37

Molecular mechanisms and therapeutic strategies of vulnerable atherosclerotic plaques  

Microsoft Academic Search

Vulnerable atherosclerotic plaque rupture leading to thrombosis is the major cause of acute coronary syndrome (ACS). Studies\\u000a on the pathophysiologic mechanism of both ACS and plaque stabilizing treatment are driving the development of animal models\\u000a of vulnerable plaque. In our laboratory, we established animal models of plaque rupture and thrombosis in rabbits and mice\\u000a that are similar to human plaque

Wen-Qiang Chen; Yun Zhang

2010-01-01

38

Influence of microcalcifications on vulnerable plaque mechanics using FSI modeling  

Microsoft Academic Search

Sudden heart attacks remain one of the primary causes of premature death in the developed world. Asymptomatic vulnerable plaques that rupture are believed to prompt such fatal heart attacks and strokes. The role of microcalcifications in the vulnerable plaque rupture mechanics is still debated. Recent studies suggest the microcalcifications increase the plaque vulnerability. In this manuscript we present a numerical

Danny Bluestein; Yared Alemu; Idit Avrahami; Morteza Gharib; Kris Dumont; John J. Ricotta; Shmuel Einav

39

Finite element modeling and intravascular ultrasound elastography of vulnerable plaques: parameter variation  

Microsoft Academic Search

Background and goal: More than 60% of all myocardial infarction is caused by rupture of a vulnerable plaque. A vulnerable plaque can be described as a large, soft lipid pool covered by a thin fibrous cap. Plaque material composition, geometry, and inflammation caused by infiltration of macrophages are considered as major determinants for plaque rupture. For diagnostic purposes, these determinants

Radj A. Baldewsing; Chris L. de Korte; Johannes A. Schaar; Frits Mastik; Antonius F. W. van der Steen

2004-01-01

40

Plaque Psoriasis  

MedlinePLUS

... Programs Calendar of Events Medical Professionals Donate Donate Psoriasis About Psoriasis Symptoms and Diagnosis Types of Psoriasis ... Kit Find Us Online YouTube Twitter Facebook Plaque Psoriasis Plaque psoriasis is the most common form of ...

41

Update on aneurysm disease: current insights and controversies: peripheral aneurysms: when to intervene - is rupture really a danger?  

PubMed

Peripheral artery aneurysms are rarer than abdominal aortic aneurysms (AAA), although the true prevalence is not well known. They often coexist with aortic and other peripheral artery aneurysms. In contrast to AAA, where the principal risk is that of rupture, thromboembolism is more common, contributing a bigger risk in the more common lesions. Although rupture does occur, with incidence related to anatomical site, aneurysm diameter cannot be used to guide management with the same confidence as in AAA. In addition, the rarity of these lesions results in a paucity of evidence with which to guide intervention. Consequently they are difficult lesions to manage, and numerous aneurysm and patient factors must be considered to provide treatment individualised for each case. We discuss popliteal, femoral, carotid, subclavian, upper limb, visceral and false aneurysms, focussing on the risk of rupture and thromboembolism, and current thresholds for intervention, based on the available published literature. PMID:23993236

Dawson, Joe; Fitridge, Robert

2013-01-01

42

Gene therapy for the vulnerable plaque  

Microsoft Academic Search

Rupture of coronary atherosclerotic plaque and subsequent formation of an occlusive intracoronary thrombus (Figure 410-1)\\u000a are the major events precipitating acute coronary syndromes [1–6]. The vulnerable plaque is smaller in size [7], richer in lipids [1],[2], and more infiltrated with macrophages [2,3,8–10] than the stable, fibromuscular lesion. Therefore, lowering the lipid and\\/or macrophage pools stored in the plaque may “stabilize”

Douglas W. Losordo; Jeffrey M. Isner

43

Image-Based Modeling and Precision Medicine: Patient-Specific Carotid and Coronary Plaque Assessment and Predictions  

PubMed Central

Atherosclerotic plaques may rupture without warning and cause acute cardiovascular events such as heart attack and stroke. Current clinical screening tools are insufficient to identify those patients with risks early and prevent the adverse events from happening. Medical imaging and image-based modeling have made considerable progress in recent years in identifying plaque morphological and mechanical risk factors which may be used in developing improved patient screening strategies. The key steps and factors in image-based models for human carotid and coronary plaques were illustrated, as well as grand challenges facing the researchers in the field to develop more accurate screening tools.

Yang, Chun; Zheng, Jie; Canton, Gador; Bach, Richard; Hatsukami, Thomas S.; Wang, Liang; Yang, Deshan; Billiar, Kristen L.; Yuan, Chun

2013-01-01

44

Fluorescence lifetime imaging microscopy for the characterization of atherosclerotic plaques  

Microsoft Academic Search

Atherosclerotic plaque composition has been associated with plaque instability and rupture. This study investigates the use of fluorescence lifetime imaging microscopy (FLIM) for mapping plaque composition and assessing features of vulnerability. Measurements were conducted in atherosclerotic human aortic samples using an endoscopic FLIM system (spatial resolution of 35 µm; temporal resolution 200 ps) developed in our lab which allows mapping

Jennifer Phipps; Yinghua Sun; Ramez Saroufeem; Nisa Hatami; Laura Marcu

2009-01-01

45

Intravascular Ultrasound Elastography: A Clinician's Tool for Assessing Vulnerability and Material Composition of Plaques  

Microsoft Academic Search

The material composition and morphology of the atherosclerotic plaque components are considered to be more important determinants of acute coronary ischemic syndromes than the degree of stenosis. When a vulnerable plaque ruptures it causes an acute thrombotic reaction. Rupture prone plaques contain a large lipid pool covered by a thin fibrous cap. The stress in these caps increases with decreasing

R. A. Baldewsing; J. A. Schaar; C. L. de Korte; F. Mastik; P. W. Serruys

2005-01-01

46

Compressive mechanical properties of atherosclerotic plaques--indentation test to characterise the local anisotropic behaviour.  

PubMed

Accurate material models and associated parameters of atherosclerotic plaques are crucial for reliable biomechanical plaque prediction models. These biomechanical models have the potential to increase our understanding of plaque progression and failure, possibly improving risk assessment of plaque rupture, which is the main cause of ischaemic strokes and myocardial infarction. However, experimental biomechanical data on atherosclerotic plaque tissue is scarce and shows a high variability. In addition, most of the biomechanical models assume isotropic behaviour of plaque tissue, which is a general over-simplification. This review discusses the past and the current literature that focus on mechanical properties of plaque derived from compression experiments, using unconfined compression, micro-indentation or nano-indentation. Results will be discussed and the techniques will be mutually compared. Thereafter, an in-house developed indentation method combined with an inverse finite element method is introduced, allowing analysis of the local anisotropic mechanical properties of atherosclerotic plaques. The advantages and limitations of this method will be evaluated and compared to other methods reported in literature. PMID:24480703

Chai, Chen-Ket; Speelman, Lambert; Oomens, Cees W J; Baaijens, Frank P T

2014-03-01

47

Pathophysiology of atherosclerosis plaque progression.  

PubMed

Atherosclerotic plaque rupture with luminal thrombosis is the most common mechanism responsible for the majority of acute coronary syndromes and sudden coronary death. The precursor lesion of plaque rupture is thought to be a thin cap fibroatheroma (TCFA) or "vulnerable plaque". TCFA is characterised by a necrotic core with an overlying thin fibrous cap (?65 ?m) that is infiltrated by macrophages and T-lymphocytes. Intraplaque haemorrhage is a major contributor to the enlargement of the necrotic core. Haemorrhage is thought to occur from leaky vasa vasorum that invades the intima from the adventitia as the intima enlarges. The early atherosclerotic plaque progression from pathologic intimal thickening (PIT) to a fibroatheroma is thought to be the result of macrophage infiltration. PIT is characterised by the presence of lipid pools which consist of proteoglycan with lipid insudation. The conversion of the lipid pool to a necrotic core is poorly understood but is thought to occur as a result of macrophage infiltration which releases matrix metalloproteinase (MMPs) along with macrophage apoptosis that leads to the formation of a acellular necrotic core. The fibroatheroma has a thick fibrous cap that begins to thin over time through macrophage MMP release and apoptotic death of smooth muscle cells converting the fibroatheroma into a TCFA. Other causes of thrombosis include plaque erosion which is less frequent than plaque rupture but is a common cause of thrombosis in young individuals especially women <50 years of age. The underlying lesion morphology in plaque erosion consists of PIT or a thick cap fibroatheroma. Calcified nodule is the least frequent cause of thrombosis, which occurs in older individuals with heavily calcified and tortious arteries. PMID:23541627

Sakakura, Kenichi; Nakano, Masataka; Otsuka, Fumiyuki; Ladich, Elena; Kolodgie, Frank D; Virmani, Renu

2013-06-01

48

Material-specific imaging of atherosclerotic plaque using coherently scattered x rays  

NASA Astrophysics Data System (ADS)

The formation and development of plaques in the arterial wall is a direct consequence of atherosclerosis. The composition of a plaque is of particular interest as it is thought to be an important indicator of vulnerability, or risk of rupture and thrombosis. Current diagnostic methods do not yet have the ability to fully characterize plaque composition. Coherent-scatter imaging, a technique being developed in our laboratory, produces images based on the low-angle scattering properties of tissue. As these properties depend on molecular structure, material-specific maps of the different components in a tissue can be created. Material-specific images were produced for an atherosclerotic carotid artery. The image distributions of fatty and calcified deposits agreed with visual examination of the specimen. Preliminary results indicate that fat and calcifications, two typical plaque constituents, can be identified and distinguished from the undiseased vessel wall using coherently scattered x rays.

Davidson, Melanie T.; Batchelar, Deidre L.; Cunningham, Ian A.

2002-05-01

49

The vulnerable coronary plaque: update on imaging technologies.  

PubMed

Several studies have been carried out on vulnerable plaque as the main culprit for ischaemic cardiac events. Historically, the most important diagnostic technique for studying coronary atherosclerotic disease was to determine the residual luminal diameter by angiographic measurement of the stenosis. However, it has become clear that vulnerable plaque rupture as well as thrombosis, rather than stenosis, triggers most acute ischaemic events and that the quantification of risk based merely on severity of the arterial stenosis is not sufficient. In the last decades, substantial progresses have been made on optimisation of techniques detecting the arterial wall morphology, plaque composition and inflammation. To date, the use of a single technique is not recommended to precisely identify the progression of the atherosclerotic process in human beings. In contrast, the integration of data that can be derived from multiple methods might improve our knowledge about plaque destabilisation. The aim of this narrative review is to update evidence on the accuracy of the currently available non-invasive and invasive imaging techniques in identifying components and morphologic characteristics associated with coronary plaque vulnerability. PMID:23803753

Rosa, Gian Marco; Bauckneht, Matteo; Masoero, Giovanni; Mach, François; Quercioli, Alessandra; Seitun, Sara; Balbi, Manrico; Brunelli, Claudio; Parodi, Antonello; Nencioni, Alessio; Vuilleumier, Nicolas; Montecucco, Fabrizio

2013-10-01

50

Effects of bacteriophage traits on plaque formation  

PubMed Central

Background The appearance of plaques on a bacterial lawn is one of the enduring imageries in modern day biology. The seeming simplicity of a plaque has invited many hypotheses and models in trying to describe and explain the details of its formation. However, until now, there has been no systematic experimental exploration on how different bacteriophage (phage) traits may influence the formation of a plaque. In this study, we constructed a series of isogenic ? phages that differ in their adsorption rate, lysis timing, or morphology so that we can determine the effects if these changes on three plaque properties: size, progeny productivity, and phage concentration within plaques. Results We found that the adsorption rate has a diminishing, but negative impact on all three plaque measurements. Interestingly, there exists a concave relationship between the lysis time and plaque size, resulting in an apparent optimal lysis time that maximizes the plaque size. Although suggestive in appearance, we did not detect a significant effect of lysis time on plaque productivity. Nonetheless, the combined effects of plaque size and productivity resulted in an apparent convex relationship between the lysis time and phage concentration within plaques. Lastly, we found that virion morphology also affected plaque size. We compared our results to the available models on plaque size and productivity. For the models in their current forms, a few of them can capture the qualitative aspects of our results, but not consistently in both plaque properties. Conclusions By using a collection of isogenic phage strains, we were able to investigate the effects of individual phage traits on plaque size, plaque productivity, and average phage concentration in a plaque while holding all other traits constant. The controlled nature of our study allowed us to test several model predictions on plaque size and plaque productivity. It seems that a more realistic theoretical approach to plaque formation is needed in order to capture the complex interaction between phage and its bacterium host in a spatially restricted environment.

2011-01-01

51

[Plaque indices].  

PubMed

The objective quantitative evaluation of the extent of plaques is necessary for epidemiologic studies and for the estimation of the effects of various cleaning methods and agents. Numerous indices have been elaborated for this purpose. Relation planimetry is used for the detection and exact evaluation of small differences. The surfaces are measured with a compensating planimeter, the slides to be evaluated being projected on a white sheet by means of a microfilm reader. In this way, the plaque covered surfaces are determined as percentages of the total surfaces. PMID:283608

Kötzschke, R

1978-11-01

52

Collagenases and cracks in the plaque  

PubMed Central

The core of an atheromatous plaque contains lipids, macrophages, and cellular debris, typically covered by a fibrous cap that separates the thrombogenic core from the blood. Rupture of the fibrous cap causes most fatal myocardial infarctions. Interstitial collagen confers tensile strength on the cap, as it does in skin and tendons. In 1994, Peter Libby and colleagues demonstrated overexpression of collagenolytic enzymes in atheromatous plaques and implicated MMPs in the destabilization of these lesions.

Libby, Peter

2013-01-01

53

Smooth Muscle Cells and the Formation, Degeneration, and Rupture of Saccular Intracranial Aneurysm Wall-a Review of Current Pathophysiological Knowledge.  

PubMed

Subarachnoid hemorrhage or intracerebral hemorrhage caused by rupture of a saccular intracranial aneurysm (sIA) is often fatal and causes significant loss of productive live years in addition to significant mortality. Around 3.5 % of the middle aged otherwise healthy population carries unruptured sIAs. Many sIAs never rupture, and since their prophylactic treatment is associated with risks of morbidity and even mortality, it is paramount to elucidate the biology that leads to sIA rupture in order be able to identify rupture-prone sIAs and to improve current therapies. Smooth muscle cells (SMCs) play a critical role both in the formation of sIAs, as well as in the repair and adaptation of the sIA wall to hemodynamic and proteolytic stress to which it is subjected. Loss of mural SMCs is characteristic to ruptured sIA walls, and experiments in animal models suggest that this loss of mural SMCs is causative to sIA growth and eventual rupture. Genetic factors that impair the function or survival of SMCs may predispose to sIA formation. Local or systemic therapy that increases the number of functioning SMCs in the sIA wall may have a potential to reduce the risk of sIA rupture. This review discusses the mechanisms and cellular interactions that SMCs have in the pathobiology of the sIA wall. PMID:24683005

Frösen, Juhana

2014-06-01

54

Growth of necrotic cores in atherosclerotic plaque.  

PubMed

Plaques are fatty deposits that grow mainly in arteries and develop as a result of a chronic inflammatory response. Plaques are characterized as 'vulnerable' when they have large internal regions of necrosis and are heavily infiltrated by macrophages. The particular composition of a vulnerable plaque renders it susceptible to rupture, which releases thrombogenic agents into the bloodstream and can result in myocardial infarction. In this paper, we propose a mathematical model to predict the development of a plaque's necrotic core. By solving coupled reaction-diffusion equations for macrophages and dead cells, we focus on the joint effects of hypoxic cell death and chemoattraction to oxidized low-density lipoprotein (Ox-LDL), a molecule that is strongly linked to atherosclerosis. We do not model the mechanical properties of the plaque, its growth or rupture. Our model predicts cores that have approximately the right size and shape when compared to ultrasound images. Because our model is linear and autonomous, normal mode analysis and subsequent calculation of the smallest eigenvalue allow us to compute the times taken for the necrotic core to form. We find that the spatial distribution of Ox-LDL within the plaque determines not only the placement and size of cores, but their time of formation. Although plaques are biochemically complex, our study shows that certain aspects of their composition can be predicted and are, in fact, governed by simple physical models. PMID:21908792

Fok, Pak-Wing

2012-12-01

55

Comprehensive plaque assessment by coronary CT angiography.  

PubMed

Most acute coronary syndromes are caused by sudden luminal thrombosis due to atherosclerotic plaque rupture or erosion. Preventing such an event seems to be the only effective strategy to reduce mortality and morbidity of coronary heart disease. Coronary lesions prone to rupture have a distinct morphology compared with stable plaques, and provide a unique opportunity for noninvasive imaging to identify vulnerable plaques before they lead to clinical events. The submillimeter spatial resolution and excellent image quality of modern computed tomography (CT) scanners allow coronary atherosclerotic lesions to be detected, characterized, and quantified. Large plaque volume, low CT attenuation, napkin-ring sign, positive remodelling, and spotty calcification are all associated with a high risk of acute cardiovascular events in patients. Computation fluid dynamics allow the calculation of lesion-specific endothelial shear stress and fractional flow reserve, which add functional information to plaque assessment using CT. The combination of morphologic and functional characteristics of coronary plaques might enable noninvasive detection of vulnerable plaques in the future. PMID:24755916

Maurovich-Horvat, Pál; Ferencik, Maros; Voros, Szilard; Merkely, Béla; Hoffmann, Udo

2014-07-01

56

ACTIVATION OF T LYMPHOCYTES IN ATHEROSCLEROTIC PLAQUES  

PubMed Central

Objective To decipher the immunological mechanisms of plaque maturation and rupture, it is necessary to analyze the phenotypes and distribution of individual lymphocytes which migrate to the plaques as well as their activation at different stages of plaque formation. Methods and Results We developed a protocol to isolate plaque-residing immune cells and analyze their status using polychromatic flow cytometry. We found that the composition and phenotype of T lymphocytes in the plaques differs from that in blood. CD4 and, in particular, CD8+ T cells in plaques are highly activated; the fraction of CD8 T cells co-expressing CD25 and HLA-DR in plaques was 10 times larger than in blood. Conclusions The first flow-cytoanalysis of individual T cells in atherosclerotic plaques indicates that plaques represent a separate immunological compartment from blood with lymphocytes characterized by a high level of T cells activation, which is compatible with the presence of antigen(s) that trigger infiltration activation of these cells. The ability to isolate and characterize these cells may lead to the identification of such antigens.

Grivel, Jean-Charles; Ivanova, Oxana; Pinegina, Natalia; Blank, Paul S.; Shpektor, Alexander; Margolis, Leonid B.; Vasilieva, Elena

2011-01-01

57

Ruptured eardrum  

MedlinePLUS

Tympanic membrane perforation; Eardrum - ruptured or perforated; Perforated eardrum ... Buttaravoli P, Leffler SM. Perforated tympanic membrane (ruptured eardrum). ... Pa: Mosby Elsevier; 2012:chap 37. Kerschner JE. Otitis ...

58

Assessment of vulnerable plaque composition by matching the deformation of a parametric plaque model to measured plaque deformation  

Microsoft Academic Search

Intravascular ultrasound (IVUS) elastography visualizes local radial strain of arteries in so-called elastograms to detect rupture-prone plaques. However, due to the unknown arterial stress distribution these elastograms cannot be directly interpreted as a morphology and material composition image. To overcome this limitation we have developed a method that reconstructs a Young's modulus image from an elastogram. This method is especially

Radj A. Baldewsing; Johannes A. Schaar; Frits Mastik; Cees. W. J. Oomens; Antonius F. W. van der Steen

2005-01-01

59

The Impact of Calcification on the Biomechanical Stability of Atherosclerotic Plaques  

Microsoft Academic Search

Background—Increased biomechanical stresses in the fibrous cap of atherosclerotic plaques contribute to plaque rupture and, consequently, to thrombosis and myocardial infarction. Thin fibrous caps and large lipid pools are important determinants of increased plaque stresses. Although coronary calcification is associated with worse cardiovascular prognosis, the relationship between atheroma calcification and stresses is incompletely described. Methods and Results—To test the hypothesis

Hayden Huang; Renu Virmani; Hesham Younis; Allen P. Burke; Roger D. Kamm; Richard T. Lee

2001-01-01

60

Multiphoton microscopy of atheroslcerotic plaques  

NASA Astrophysics Data System (ADS)

Multiphoton microscopy is a techniques that fascilitates three dimensional imaging of intact, unstained tissue. Especially connective tissue has a relatively strong nonlinear optical response and can easily be imaged. Atherosclerosis is a disease where lipids accumulate in the vessel wall and there is a thickening of the intima by growth of a cap of connective tissue. The mechanical strength of this fibrous cap is of clinically importance. If the cap ruptures a thrombosis forms which can block a coronary vessel and therby causing myocardial infarction. Multiphoton microscopy can be used to image the fibrous cap and thereby determine the thickness of the cap and the structure of the connective fibres. This could possibly be developed into a diagnostic and clincal tool to monitor the vulnerability of a plaque and also to better understand the development of a plaque and effects of treatment. We have collected multiphoton microscopy images from atherosclerotic plaque in human aorta, both two photon excited fluorescens and second harmonic generated signal. The feasability of using this technique to determine the state of the plaque is explored.

Lilledahl, Magnus B.; de Lange Davies, Catharina; Haugen, Olav A.; Svaasand, Lars O.

2007-03-01

61

Nature or The Natural Evolution of Plaque: What Matters?  

PubMed Central

ABSTRACT Progression to major acute cardiovascular events often is triggered by an atherosclerotic plaque complicated by rupture or erosion, namely the vulnerable plaque. Early and secure identification of these plaques would allow the development of individualized therapeutic and pharmacological strategies, applied in a timely manner. Imaging methods have a huge potential in detecting and monitoring the evolution of vulnerable plaque. Even though there are multiple invasive and noninvasive techniques, clinical application is for now a matter of choosing the relevant imaging feature for the prognosis, the methodo­logy of study and the target population.

AURSULESEI, Viviana

2013-01-01

62

Comprehensive overview of definitions for optical coherence tomography-based plaque and stent analyses.  

PubMed

Optical coherence tomography (OCT) is the current state-of-the-art intracoronary imaging modality that allows visualization of detailed morphological characteristics of both atherosclerotic plaque and stent. So far, three expert review documents have been released for standardization of OCT image analysis. In the real world, a variety of definitions are being used by different groups and by different core laboratories to analyze OCT findings because of different clinical/procedural contexts in which OCT research has been carried out. This comprehensive overview is aimed to summarize different applicable definitions used by different research groups in plaque and stent analysis using OCT. In addition, it presents readers with a panoramic view to select the best definition of OCT measurement for one's own study purpose. We divided this review article into two parts: Part I - Plaque analysis, and Part II - Stent analysis. The plaque analysis section summarizes the definitions of plaque composition, rupture, erosion, protruding calcific nodules, macrophages, microvessels, and cholesterol crystal. The stent analysis section includes the classification of stent struts, features of neointimal hyperplasia, and other stent-related findings such as tissue protrusion, thrombus, intrastent, and stent edge dissections. In each case of controversy, an explanation for the specific context is provided. PMID:24356250

Di Vito, Luca; Yoon, Joo Heung; Kato, Koji; Yonetsu, Taishi; Vergallo, Rocco; Costa, Marco; Bezerra, Hiram G; Arbustini, Eloisa; Narula, Jagat; Crea, Filippo; Prati, Francesco; Jang, Ik-Kyung

2014-03-01

63

Carotid Plaque Age Is a Feature of Plaque Stability Inversely Related to Levels of Plasma Insulin  

PubMed Central

Background The stability of atherosclerotic plaques determines the risk for rupture, which may lead to thrombus formation and potentially severe clinical complications such as myocardial infarction and stroke. Although the rate of plaque formation may be important for plaque stability, this process is not well understood. We took advantage of the atmospheric 14C-declination curve (a result of the atomic bomb tests in the 1950s and 1960s) to determine the average biological age of carotid plaques. Methodology/Principal Finding The cores of carotid plaques were dissected from 29 well-characterized, symptomatic patients with carotid stenosis and analyzed for 14C content by accelerator mass spectrometry. The average plaque age (i.e. formation time) was 9.6±3.3 years. All but two plaques had formed within 5–15 years before surgery. Plaque age was not associated with the chronological ages of the patients but was inversely related to plasma insulin levels (p?=?0.0014). Most plaques were echo-lucent rather than echo-rich (2.24±0.97, range 1–5). However, plaques in the lowest tercile of plaque age (most recently formed) were characterized by further instability with a higher content of lipids and macrophages (67.8±12.4 vs. 50.4±6.2, p?=?0.00005; 57.6±26.1 vs. 39.8±25.7, p<0.0005, respectively), less collagen (45.3±6.1 vs. 51.1±9.8, p<0.05), and fewer smooth muscle cells (130±31 vs. 141±21, p<0.05) than plaques in the highest tercile. Microarray analysis of plaques in the lowest tercile also showed increased activity of genes involved in immune responses and oxidative phosphorylation. Conclusions/Significance Our results show, for the first time, that plaque age, as judge by relative incorporation of 14C, can improve our understanding of carotid plaque stability and therefore risk for clinical complications. Our results also suggest that levels of plasma insulin might be involved in determining carotid plaque age.

Hagg, Sara; Salehpour, Mehran; Noori, Peri; Lundstrom, Jesper; Possnert, Goran; Takolander, Rabbe; Konrad, Peter; Rosfors, Stefan; Ruusalepp, Arno; Skogsberg, Josefin; Tegner, Jesper; Bjorkegren, Johan

2011-01-01

64

In Vivo/Ex Vivo MRI-Based 3D Non-Newtonian FSI Models for Human Atherosclerotic Plaques Compared with Fluid/Wall-Only Models  

PubMed Central

It has been recognized that fluid-structure interactions (FSI) play an important role in cardiovascular disease initiation and development. However, in vivo MRI multi-component FSI models for human carotid atherosclerotic plaques with bifurcation and quantitative comparisons of FSI models with fluid-only or structure-only models are currently lacking in the literature. A 3D non-Newtonian multi-component FSI model based on in vivo/ex vivo MRI images for human atherosclerotic plaques was introduced to investigate flow and plaque stress/strain behaviors which may be related to plaque progression and rupture. Both artery wall and plaque components were assumed to be hyperelastic, isotropic, incompressible and homogeneous. Blood flow was assumed to be laminar, non-Newtonian, viscous and incompressible. In vivo/ex vivo MRI images were acquired using histologically-validated multi-spectral MRI protocols. The 3D FSI models were solved and results were compared with those from a Newtonian FSI model and wall-only/fluid-only models. A 145% difference in maximum principal stresses (Stress-P1) between the FSI and wall-only models and 40% difference in flow maximum shear stress (MSS) between the FSI and fluid-only models were found at the throat of the plaque using a severe plaque sample (70% severity by diameter). Flow maximum shear stress (MSS) from the rigid wall model is much higher (20–40% in maximum MSS values, 100–150% in stagnation region) than those from FSI models.

Yang, Chun; Tang, Dalin; Yuan, Chun; Hatsukami, Thomas S.; Zheng, Jie; Woodard, Pamela K.

2009-01-01

65

Imaging Atherosclerosis and Vulnerable Plaque  

PubMed Central

Identifying patients at high risk for an acute cardiovascular event such as myocardial infarction or stroke and assessing the total atherosclerotic burden are clinically important. Currently available imaging modalities can delineate vascular wall anatomy and, with novel probes, target biologic processes important in plaque evolution and plaque stability. Expansion of the vessel wall involving remodeling of the extracellular matrix can be imaged, as can angiogenesis of the vasa vasorum, plaque inflammation, and fibrin deposits on early nonocclusive vascular thrombosis. Several imaging platforms are available for targeted vascular imaging to acquire information on both anatomy and pathobiology in the same imaging session using either hybrid technology (nuclear combined with CT) or MRI combined with novel probes targeting processes identified by molecular biology to be of importance. This article will discuss the current state of the art of these modalities and challenges to clinical translation.

Sadeghi, Mehran M.; Glover, David K.; Lanza, Gregory M.; Fayad, Zahi A.; Johnson, Lynne L.

2010-01-01

66

Clinical classification of plaque morphology in coronary disease.  

PubMed

In published post-mortem pathological studies, more than two-thirds of acute coronary events are associated with the rupture of lipid-rich, voluminous, and outwardly remodelled plaques covered by attenuated and inflamed fibrous caps in the proximal part of coronary arteries. Superficial erosion of the plaques is responsible for most of the remaining events; the eroded plaques usually do not demonstrate much lipid burden, do not have thin fibrous caps, are not positively remodelled, and are not critically occlusive. Both noninvasive and invasive imaging studies have been performed to clinically define the plaque characteristics in acute coronary syndromes in an attempt to identify the high-risk plaque substrate susceptible to development of an acute coronary event. Optical coherence tomography (OCT)-an intravascular imaging modality with high resolution-can be used to define various stages of plaque morphology, which might allow its use for the identification of high-risk plaques vulnerable to rupture, and their amenability to pre-emptive interventional treatment. OCT might also be employed to characterize plaque pathology at the time of intervention, to provide a priori knowledge of the mechanism of the acute coronary syndrome and, therefore, to enable improved management of the condition. PMID:24776706

Otsuka, Fumiyuki; Joner, Michael; Prati, Francesco; Virmani, Renu; Narula, Jagat

2014-07-01

67

The influence of genetics on intracranial aneurysm formation and rupture: current knowledge and its possible impact on future treatment  

Microsoft Academic Search

The etiology of intracranial aneurysm formation and rupture remains mostly unknown, but lately several studies have increasingly\\u000a supported the role of genetic factors. In reports so far, genome-wide linkage studies suggest several susceptibility loci\\u000a that may contain one or more predisposing genes. Depending on the examined ethnic population, several different non-matching\\u000a chromosomal regions have been found. Studies of several candidate

B. Krischek; M. Tatagiba

68

Multimodal characterization of compositional, structural and functional features of human atherosclerotic plaques  

PubMed Central

Detection of atherosclerotic plaque vulnerability has critical clinical implications for avoiding sudden death in patients with high risk of plaque rupture. We report on multimodality imaging of ex-vivo human carotid plaque samples using a system that integrates fluorescence lifetime imaging (FLIM), ultrasonic backscatter microscopy (UBM), and photoacoustic imaging (PAI). Biochemical composition is differentiated with a high temporal resolution and sensitivity at the surface of the plaque by the FLIM subsystem. 3D microanatomy of the whole plaque is reconstructed by the UBM. Functional imaging associated with optical absorption contrast is evaluated from the PAI component. Simultaneous recordings of the optical, ultrasonic, and photoacoustic data present a wealth of complementary information concerning the plaque composition, structure, and function that are related to plaque vulnerability. This approach is expected to improve our ability to study atherosclerotic plaques. The multimodal system presented here can be translated into a catheter based intraluminal system for future clinical studies.

Sun, Yang; Chaudhari, Abhijit J.; Lam, Matthew; Xie, Hongtao; Yankelevich, Diego R.; Phipps, Jennifer; Liu, Jing; Fishbein, Michael C.; Cannata, Jonathan M.; Shung, K. Kirk; Marcu, Laura

2011-01-01

69

Carotid Atheroma Rupture Observed In Vivo and FSI-Predicted Stress Distribution Based on Pre-rupture Imaging  

PubMed Central

Atherosclerosis at the carotid bifurcation is a major risk factor for stroke. As mechanical forces may impact lesion stability, finite element studies have been conducted on models of diseased vessels to elucidate the effects of lesion characteristics on the stresses within plaque materials. It is hoped that patient-specific biomechanical analyses may serve clinically to assess the rupture potential for any particular lesion, allowing better stratification of patients into the most appropriate treatments. Due to a sparsity of in vivo plaque rupture data, the relationship between various mechanical descriptors such as stresses or strains and rupture vulnerability is incompletely known, and the patient-specific utility of biomechanical analyses is unclear. In this article, we present a comparison between carotid atheroma rupture observed in vivo and the plaque stress distribution from fluid–structure interaction analysis based on pre-rupture medical imaging. The effects of image resolution are explored and the calculated stress fields are shown to vary by as much as 50% with sub-pixel geometric uncertainty. Within these bounds, we find a region of pronounced elevation in stress within the fibrous plaque layer of the lesion with a location and extent corresponding to that of the observed site of plaque rupture.

Rayz, Vitaliy L.; Soares, Bruno; Wintermark, Max; Mofrad, Mohammad R. K.; Saloner, David

2010-01-01

70

Macrophage expression of active MMP-9 induces acute plaque disruption in apoE-deficient mice  

PubMed Central

The majority of acute clinical manifestations of atherosclerosis are due to the physical rupture of advanced atherosclerotic plaques. It has been hypothesized that macrophages play a key role in inducing plaque rupture by secreting proteases that destroy the extracellular matrix that provides physical strength to the fibrous cap. Despite reports detailing the expression of multiple proteases by macrophages in rupture-prone regions, there is no direct proof that macrophage-mediated matrix degradation can induce plaque rupture. We aimed to test this hypothesis by retrovirally overexpressing the candidate enzyme MMP-9 in macrophages of advanced atherosclerotic lesions of apoE–/– mice. Despite a greater than 10-fold increase in the expression of MMP-9 by macrophages, there was only a minor increase in the incidence of plaque fissuring. Subsequent analysis revealed that macrophages secrete MMP-9 predominantly as a proform, and this form is unable to degrade the matrix component elastin. Expression of an autoactivating form of MMP-9 in macrophages in vitro greatly enhances elastin degradation and induces significant plaque disruption when overexpressed by macrophages in advanced atherosclerotic lesions of apoE–/– mice in vivo. These data show that enhanced macrophage proteolytic activity can induce acute plaque disruption and highlight MMP-9 as a potential therapeutic target for stabilizing rupture-prone plaques.

Gough, Peter J.; Gomez, Ivan G.; Wille, Paul T.; Raines, Elaine W.

2006-01-01

71

Uterine Rupture  

Microsoft Academic Search

\\u000a Uterine rupture may be defined as a disruption of the uterine muscle extending to and involving the uterine serosa or disruption\\u000a of the uterine muscle with extension to the bladder or broad ligament [1]. Uterine dehiscence is defined as disruption of\\u000a the uterine muscle with intact uterine serosa [1]. Uterine rupture is associated with severe maternal and perinatal morbidity\\u000a and

Sharon R. Sheehan; Deirdre J. Murphy

72

(Shear) Strain Imaging Used in Noninvasive Detection of Vulnerable Plaques in the Carotid Arterial Wall  

Microsoft Academic Search

\\u000a The primary trigger for myocardial infarction and stroke is destabilization of atherosclerotic plaques. The chance of a plaque\\u000a to rupture is related to its composition and geometry. Ultrasound (shear) strain imaging allows assessment of local tissue\\u000a mechanics and possible risk assessment of vulnerable plaques. Intravascularly, in coronary arteries using a catheter, strain\\u000a imaging has been demonstrated to be successful. At

T. Idzenga; H. H. G. Hansen; C. L. Korte

73

The first spontaneous coronary artery perforation due to disruption of atherosclerotic plaque  

Microsoft Academic Search

Spontaneous coronary artery rupture is rarely seen and most of the reorted cases in the world literature are related to rupture of a coronary artery aneurysm or of a saphenous vein graft. There is no report in the literature of a patient with spontaneous coronary artery perforation due to disruption of coronary atherosclerotic plaque. We can confirm that our patient

Engin Bozkurt; Mustafa Kemal Erol; Mahmut Acikel; H. Yekta Gürlertop; Mustafa Yilmaz; Sebahattin Atesal; ?ule Karakelleo?lu

2004-01-01

74

Preliminary in vivo atherosclerotic carotid plaque characterization using the accumulated axial strain and relative lateral shift strain indices  

NASA Astrophysics Data System (ADS)

In this paper, we explore two parameters or strain indices related to plaque deformation during the cardiac cycle, namely, the maximum accumulated axial strain in plaque and the relative lateral shifts between plaque and vessel wall under in vivo clinical ultrasound imaging conditions for possible identification of vulnerable plaque. These strain indices enable differentiation between calcified and lipidic plaque tissue utilizing a new perspective based on the stiffness and mobility of the plaque. In addition, they also provide the ability to distinguish between softer plaques that undergo large deformations during the cardiac cycle when compared to stiffer plaque tissue. Soft plaques that undergo large deformations over the cardiac cycle are more prone to rupture and to release micro-emboli into the cerebral bloodstream. The ability to identify vulnerable plaque, prone to rupture, would significantly enhance the clinical utility of this method for screening patients. We present preliminary in vivo results obtained from ultrasound radio frequency data collected over 16 atherosclerotic plaque patients before these patients undergo a carotid endarterectomy procedure. Our preliminary in vivo results indicate that the maximum accumulated axial strain over a cardiac cycle and the maximum relative lateral shift or displacement of the plaque are useful strain indices that provide differentiation between soft and calcified plaques.

Shi, Hairong; Mitchell, Carol C.; McCormick, Matthew; Kliewer, Mark A.; Dempsey, Robert J.; Varghese, Tomy

2008-11-01

75

Oxysterols and symptomatic versus asymptomatic human atherosclerotic plaque.  

PubMed

Atherosclerosis is the most common cause of mortality in the Western world, contributing to about 50% of all deaths. Atherosclerosis is characterized by deposition of lipids onto the coronary or carotid arterial wall and formation of an atherosclerotic plaque. Atherosclerotic plaques are categorized into two groups: symptomatic and asymptomatic. The symptomatic plaques tend to be unstable and prone to rupture, and are associated with an increase in ischemic events. Oxysterols, products of cholesterol oxidation, are cytotoxic materials. Their level and type may be associated with plaque formation, development and stability. Oxysterols stimulate the formation of foam cells, advance atherosclerotic plaque progression, and contribute to plaque vulnerability and instability due to their cytotoxicity and their ability to induce cell apoptosis. Studies indicate that plasma 7?-OH CH level can be used as a biomarker for detecting carotid and coronary artery disease. Further clinical studies are needed to evaluate the potential of oxysterols for use as biomarkers for plaque vulnerability and instability. The identification of biomarkers in the blood that can distinguish between symptomatic and asymptomatic plaques remains an unresolved issue. PMID:24393847

Khatib, Soliman; Vaya, Jacob

2014-04-11

76

HIV Mother-to-Child Transmission, Mode of Delivery, and Duration of Rupture of Membranes: Experience in the Current Era  

PubMed Central

Objective. To evaluate whether the length of time of rupture of membranes (ROM) in optimally managed HIV-positive women on highly active antiretroviral therapy (HAART) with low viral loads (VL) is predictive of the risk of mother to child transmission (MTCT) of the human immunodeficiency virus (HIV). Study Methods. A retrospective case series of all HIV-positive women who delivered at two academic tertiary centers in Toronto, Canada from January 2000 to November 2010 was completed. Results. Two hundred and ten HIV-positive women with viral loads <1,000 copies/ml delivered during the study period. VL was undetectable (<50 copies/mL) for the majority of the women (167, 80%), and <1,000 copies/mL for all women. Mode of delivery was vaginal in 107 (51%) and cesarean in 103 (49%). The median length of time of ROM was 0.63 hours (range 0 to 77.87 hours) for the entire group and 2.56 hours (range 0 to 53.90 hours) for those who had a vaginal birth. Among women with undetectable VL, 90 (54%) had a vaginal birth and 77 (46%) had a cesarean birth. Among the women in this cohort there were no cases of MTCT of HIV. Conclusions. There was no association between duration of ROM or mode of delivery and MTCT in this cohort of 210 virally suppressed HIV-positive pregnant women.

Mark, Siobhan; Murphy, Kellie E.; Read, Stanley; Bitnun, Ari; Yudin, Mark H.

2012-01-01

77

Monocytes and neutrophils expressing myeloperoxidase occur in fibrous caps and thrombi in unstable coronary plaques  

PubMed Central

Background Myeloperoxidase (MPO) -containing macrophages and neutrophils have been described at sites of plaque rupture. The presence of these cells in precursor lesions to acute rupture (thin cap atheroma, or vulnerable plaque) and within thrombi adjacent to ruptures has not been described, nor an association with iron-containing macrophages within unstable plaques. Methods We studied 61 acute ruptures, 15 organizing ruptures, 31 thin cap fibroatheromas, and 28 fibroatheromas from 72 sudden coronary death victims by immunohistochemical and histochemical techniques. Inflammatory cells were typed with anti-CD68 (macrophages), anti-BP-30 (neutrophil bactericidal glycoprotein), and anti-MPO. Iron was localized by Mallory's Prussian blue stain. In selected plaques alpha smooth muscle actin (DAKO, Carpinteria, CA, clone M0851) was performed. Results MPO positive cells were present in 79% of ruptured caps, 28% of thin cap fibroatheroma, and no fibroatheromas; neutrophils were present in 72% of ruptures, 8% of thin cap fibroatheromas, and no fibroatheromas. Iron containing foam cells were present in the caps of 93% of acute ruptures, of 85% of organizing ruptures, 20% of thin cap atheromas, and 10% of fibroatheromas. MPO positive cells were more frequent in occlusive than non-occlusive thrombi adjacent to ruptures (p = .006) and were more numerous in diabetics compared to non-diabetics (p = .002) Conclusion Unstable fibrous caps are more likely to contain MPO-positive cells, neutrophils, and iron-containing macrophages than fibrous caps of stable fibroatheromas. MPO-positive cells in thrombi adjacent to disrupted plaques are associated with occlusive thrombi and are more numerous in diabetic patients.

Tavora, Fabio R; Ripple, Mary; Li, Ling; Burke, Allen P

2009-01-01

78

SMC-Specific IGF-1 Overexpression in Apoe?/? Mice Does Not Alter Atherosclerotic Plaque Burden but Increases Features of Plaque Stability  

PubMed Central

Objective Growth factors may play a permissive role in atherosclerosis initiation and progression, in part via their promotion of VSMC accumulation in plaques. However, unstable human plaques often have a relative paucity of VSMC which has been suggested to contribute to plaque rupture and/or erosion and to clinical events. IGF-1 is an endocrine and autocrine/paracrine growth factor that is a mitogen for VSMC, but when infused into Apoe?/? mice paradoxically reduces atherosclerosis burden. Methods & Results To determine the effect of stimulation of VSMC growth on atherosclerotic plaque development and to understand mechanisms of IGF-1’s atheroprotective effect we assessed atherosclerotic plaques in mice overexpressing IGF-1 in SMC under the control of the ?SMA promoter, after backcrossing to the Apoe?/? background (SMP8/Apoe?/?). When compared with Apoe?/? mice these SMP8/Apoe?/? mice developed comparable plaque burden after 12 wks on a Western diet, suggesting that the ability of increased circulating IGF-1 to reduce plaque burden was mediated in large part via non-SMC target cells. However, advanced plaques in SMP8/Apoe?/? mice displayed several features of plaque stability, including increased fibrous cap area, ?SMA positive SMC and collagen content and reduced necrotic cores. Conclusion These findings indicate that stimulation of VSMC IGF-1 signaling does not alter total atherosclerotic plaque burden and may improve atherosclerotic plaque stability.

Shai, Shaw-Yung; Sukhanov, Sergiy; Higashi, Yusuke; Vaughn, Charlotte; Kelly, James; Delafontaine, Patrice

2010-01-01

79

Imaging of coronary atherosclerosis and identification of the vulnerable plaque  

PubMed Central

Identification of the vulnerable plaque responsible for the occurrence of acute coronary syndromes and acute coronary death is a prerequisite for the stabilisation of this vulnerable plaque. Comprehensive coronary atherosclerosis imaging in clinical practice should involve visualisation of the entire coronary artery tree and characterisation of the plaque, including the three-dimensional morphology of the plaque, encroachment of the plaque on the vessel lumen, the major tissue components of the plaque, remodelling of the vessel and presence of inflammation. Obviously, no single diagnostic modality is available that provides such comprehensive imaging and unfortunately no diagnostic tool is available that unequivocally identifies the vulnerable plaque. The objective of this article is to discuss experience with currently available diagnostic modalities for coronary atherosclerosis imaging. In addition, a number of evolving techniques will be briefly discussed. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6Figure 7

de Feyter, P.J.; Serruys, P. W.; Nieman, K.; Mollet, N.; Cademartiri, F.; van Geuns, R. J.; Slager, C.; van der Steen, A.F.W.; Krams, R.; Schaar, J.A.; Wielopolski, P.; Pattynama, P.M.T.; Arampatzis, A.; van der Lugt, A.; Regar, E.; Ligthart, J.; Smits, P.

2003-01-01

80

CT evaluation of vulnerable plaque: noninvasive fortune-telling?  

PubMed

Recently, cardiac CTA has been proposed as a promising noninvasive tool for identification of rupture-prone plaques prior to a subsequent coronary event. This task is particularly challenging but the reward is high: identification of high-risk lesions could preclude plaque thrombosis and possibly prevent acute coronary syndromes. We present a case of a borderline mixed plaque with positive remodeling in the proximal left anterior descending artery (LAD). After 6 months and despite aggressive medical therapy, the patient developed acute ST-elevation myocardial infarction caused by a thrombotic lesion in the proximal LAD. We review the literature on CT characteristics of vulnerable plaque and discuss the possible preventive interventions. PMID:21505956

Opolski, Maksymilian P; Kepka, Cezary; Witkowski, Adam

2012-10-01

81

Assessment of vulnerable plaque composition by matching the deformation of a parametric plaque model to measured plaque deformation.  

PubMed

Intravascular ultrasound (IVUS) elastography visualizes local radial strain of arteries in so-called elastograms to detect rupture-prone plaques. However, due to the unknown arterial stress distribution these elastograms cannot be directly interpreted as a morphology and material composition image. To overcome this limitation we have developed a method that reconstructs a Young's modulus image from an elastogram. This method is especially suited for thin-cap fibroatheromas (TCFAs), i.e., plaques with a media region containing a lipid pool covered by a cap. Reconstruction is done by a minimization algorithm that matches the strain image output, calculated with a parametric finite element model (PFEM) representation of a TCFA, to an elastogram by iteratively updating the PFEM geometry and material parameters. These geometry parameters delineate the TCFA media, lipid pool and cap regions by circles. The material parameter for each region is a Young's modulus, EM, EL, and EC, respectively. The method was successfully tested on computer-simulated TCFAs (n = 2), one defined by circles, the other by tracing TCFA histology, and additionally on a physical phantom (n = 1) having a stiff wall (measured EM = 16.8 kPa) with an eccentric soft region (measured EL = 4.2 kPa). Finally, it was applied on human coronary plaques in vitro (n = 1) and in vivo (n = 1). The corresponding simulated and measured elastograms of these plaques showed radial strain values from 0% up to 2% at a pressure differential of 20, 20, 1, 20, and 1 mmHg respectively. The used/reconstructed Young's moduli [kPa] were for the circular plaque EL = 50/66, EM = 1500/1484, EC = 2000/2047, for the traced plaque EL = 25/1, EM = 1000/1148, EC = 1500/1491, for the phantom EL = 4.2/4 kPa, EM = 16.8/16, for the in vitro plaque EL = n.a./29, EM = n.a./647, EC = n.a./1784 kPa and for the in vivo plaque EL = n.a./2, EM = n.a./188, Ec = n.a./188 kPa. PMID:15822809

Baldewsing, Radj A; Schaar, Johannes A; Mastik, Frits; Oomens, Cees W J; van der Steen, Antonius F W

2005-04-01

82

Plaque Inhibiting Oligosaccharide.  

National Technical Information Service (NTIS)

The present invention relates to a purified oligosaccharide which can be isolated from a natural source, e.g. from the cell wall polysaccharide of Streptococcus sanguis. S. sanguis is found in significant numbers in human dental plaque. This oligosacchari...

F. J. Cassels J. London

1989-01-01

83

Sintered plaque characteristics  

NASA Technical Reports Server (NTRS)

The structural transformations occurring during sintering, the fabrication of a slurry produced sintered plaque, are detailed. Degradation of the positive electrode in performance in cycling in a nickel hydrogen battery were traced to the quality of the sintered plaque. Electrode degradation was found to be a limiting factor in the battery cycle life. Details of microstructural characterization and distribution of pores, examination of plastic flow during shrinkage, and observations of the rounding of nickel powder particles during the slurry process are presented.

Vaidyanathan, H.

1982-01-01

84

Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis  

PubMed Central

Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite-Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was < 1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI are orders of magnitude lower than the stresses associated with blood pressure.

Doherty, Joshua R.; Dumont, Douglas M.; Trahey, Gregg E.; Palmeri, Mark L.

2012-01-01

85

Acoustic radiation force impulse imaging of vulnerable plaques: a finite element method parametric analysis.  

PubMed

Plaque rupture is the most common cause of complications such as stroke and coronary heart failure. Recent histopathological evidence suggests that several plaque features, including a large lipid core and a thin fibrous cap, are associated with plaques most at risk for rupture. Acoustic Radiation Force Impulse (ARFI) imaging, a recently developed ultrasound-based elasticity imaging technique, shows promise for imaging these features noninvasively. Clinically, this could be used to distinguish vulnerable plaques, for which surgical intervention may be required, from those less prone to rupture. In this study, a parametric analysis using Finite Element Method (FEM) models was performed to simulate ARFI imaging of five different carotid artery plaques across a wide range of material properties. It was demonstrated that ARFI imaging could resolve the softer lipid pool from the surrounding, stiffer media and fibrous cap and was most dependent upon the stiffness of the lipid pool component. Stress concentrations due to an ARFI excitation were located in the media and fibrous cap components. In all cases, the maximum Von Mises stress was<1.2 kPa. In comparing these results with others investigating plaque rupture, it is concluded that while the mechanisms may be different, the Von Mises stresses imposed by ARFI imaging are orders of magnitude lower than the stresses associated with blood pressure. PMID:23122224

Doherty, Joshua R; Dumont, Douglas M; Trahey, Gregg E; Palmeri, Mark L

2013-01-01

86

Genetic deletion or TWEAK blocking antibody administration reduce atherosclerosis and enhance plaque stability in mice.  

PubMed

Clinical complications associated with atherosclerotic plaques arise from luminal obstruction due to plaque growth or destabilization leading to rupture. Tumour necrosis factor ligand superfamily member 12 (TNFSF12) also known as TNF-related weak inducer of apoptosis (TWEAK) is a proinflammatory cytokine that participates in atherosclerotic plaque development, but its role in plaque stability remains unclear. Using two different approaches, genetic deletion of TNFSF12 and treatment with a TWEAK blocking mAb in atherosclerosis-prone mice, we have analysed the effect of TWEAK inhibition on atherosclerotic plaques progression and stability. Mice lacking both TNFSF12 and Apolipoprotein E (TNFSF12(-/-) ApoE(-/-) ) exhibited a diminished atherosclerotic burden and lesion size in their aorta. Advanced atherosclerotic plaques of TNFSF12(-/-) ApoE(-/-) or anti-TWEAK treated mice exhibited an increase collagen/lipid and vascular smooth muscle cell/macrophage ratios compared with TNFSF12(+/+) ApoE(-/-) control mice, reflecting a more stable plaque phenotype. These changes are related with two different mechanisms, reduction of the inflammatory response (chemokines expression and secretion and nuclear factor kappa B activation) and decrease of metalloproteinase activity in atherosclerotic plaques of TNFSF12(-/-) ApoE(-/-) . A similar phenotype was observed with anti-TWEAK mAb treatment in TNFSF12(+/+) ApoE(-/-) mice. Brachiocephalic arteries were also examined since they exhibit additional features akin to human atherosclerotic plaques associated with instability and rupture. Features of greater plaque stability including augmented collagen/lipid ratio, reduced macrophage content, and less presence of lateral xanthomas, buried caps, medial erosion, intraplaque haemorrhage and calcium content were present in TNFSF12(-/-) ApoE(-/-) or anti-TWEAK treatment in TNFSF12(+/+) ApoE(-/-) mice. Overall, our data indicate that anti-TWEAK treatment has the capacity to diminish proinflamatory response associated with atherosclerotic plaque progression and to alter plaque morphology towards a stable phenotype. PMID:24479820

Sastre, Cristina; Fernández-Laso, Valvanera; Madrigal-Matute, Julio; Muñoz-García, Begoña; Moreno, Juan A; Pastor-Vargas, Carlos; Llamas-Granda, Patricia; Burkly, Linda C; Egido, Jesús; Martín-Ventura, Jose L; Blanco-Colio, Luis M

2014-04-01

87

A computational fluid-structure interaction model for plaque vulnerability assessment in atherosclerotic human coronary arteries  

NASA Astrophysics Data System (ADS)

Coronary artery disease is responsible for a third of global deaths worldwide. Computational simulations of blood flow can be used to understand the interactions of artery/plaque and blood in coronary artery disease and to better predict the rupture of atherosclerotic plaques. So far, the mechanical properties of animals' coronary artery have been mostly used for hemodynamic simulation of atherosclerotic arteries. The mechanical properties of animals' coronary arteries are often not accurate enough and can be only used for an approximate estimation and comparative assessment of the cognate parameters in human. In this study, a three-dimensional (3D) computational fluid-structure interactions model with three different plaque types is presented to perform a more accurate plaque vulnerability assessment for human atherosclerotic plaques. The coronary arteries of twenty-two male individuals were removed during autopsy and subjected to uniaxial tensile loading. The hyperelastic material coefficients of coronary arteries were calculated and implemented to the computational model. The fully coupled fluid and structure models were solved using the explicit dynamics finite element code LS-DYNA. The normal and shear stresses induced within the plaques were significantly affected by different plaque types. The highest von Mises (153 KPa) and shear (57 KPa) stresses were observed for hypocellular plaques, while the lowest von Mises (70 KPa) and shear (39 KPa) stresses were observed on the stiffer calcified plaques. The results suggest that the risk of plaque rupture due to blood flow is lower for cellular and hypocellular plaques, while higher for calcified plaques with low fracture stresses.

Karimi, Alireza; Navidbakhsh, Mahdi; Razaghi, Reza; Haghpanahi, Mohammad

2014-04-01

88

Fluorescence lifetime imaging microscopy for the characterization of atherosclerotic plaques  

PubMed Central

Atherosclerotic plaque composition has been associated with plaque instability and rupture. This study investigates the use of fluorescence lifetime imaging microscopy (FLIM) for mapping plaque composition and assessing features of vulnerability. Measurements were conducted in atherosclerotic human aortic samples using an endoscopic FLIM system (spatial resolution of 35 ?m; temporal resolution 200 ps) developed in our lab which allows mapping in one measurement the composition within a volume of 4 mm diameter × 250 ?m depth. Each pixel in the image represents a corresponding fluorescence lifetime value; images are formed through a flexible 0.6 mm side-viewing imaging bundle which allows for further intravascular applications. Based on previously recorded spectra of human atherosclerotic plaque, fluorescence emission was collected through two filters: f1: 377/50 and f2: 460/60 (center wavelength/bandwidth), which together provides the greatest discrimination between intrinsic fluorophores related to plaque vulnerability. We have imaged nine aortas and lifetime images were retrieved using a Laguerre expansion deconvolution technique and correlated with histopathology. Early results demonstrate discrimination using fluorescence lifetime between early, lipid-rich, and collagen-rich lesions which are consistent with previously reported time-resolved atherosclerotic plaque measurements.

Phipps, Jennifer; Sun, Yinghua; Saroufeem, Ramez; Hatami, Nisa; Marcu, Laura

2009-01-01

89

Prophylaxis for infective endocarditis: antibiotic sensitivity of dental plaque  

Microsoft Academic Search

The antibiotic sensitivity pattern of bacteria isolated from bacteraemia after dental extraction was compared with that of bacteria isolated from dental plaque samples from the same patient. The results supported the current practice of using penicillin and erythromycin empirically for prophylaxis. The prediction of the most appropriate antibiotic for prophylaxis using dental plaque samples was most accurate when the minimum

T W MacFarlane; D A McGowan; K Hunter; D MacKenzie

1983-01-01

90

Visualization of coronary atherosclerotic plaques in patients using different imaging modalities  

Microsoft Academic Search

Different imaging modalities have been developed over the last several years in order to better characterize the atherosclerotic plaque and attempt to predict those in peril of complication. Specific information such as variations in temperature, plaque stiffness and calcification level is currently being researched as well as biological and chemical markers. Since vulnerable plaques cannot be identified by stress testing

Mohammad Karimi Moridani

2010-01-01

91

How Does Calcification Influence Plaque Vulnerability? Insights from Fatigue Analysis  

PubMed Central

Background. Calcification is commonly believed to be associated with cardiovascular disease burden. But whether or not the calcifications have a negative effect on plaque vulnerability is still under debate. Methods and Results. Fatigue rupture analysis and the fatigue life were used to evaluate the rupture risk. An idealized baseline model containing no calcification was first built. Based on the baseline model, we investigated the influence of calcification on rupture path and fatigue life by adding a circular calcification and changing its location within the fibrous cap area. Results show that 84.0% of calcified cases increase the fatigue life up to 11.4%. For rupture paths 10D far from the calcification, the life change is negligible. Calcifications close to lumen increase more fatigue life than those close to the lipid pool. Also, calcifications in the middle area of fibrous cap increase more fatigue life than those in the shoulder area. Conclusion. Calcifications may play a positive role in the plaque stability. The influence of the calcification only exists in a local area. Calcifications close to lumen may be influenced more than those close to lipid pool. And calcifications in the middle area of fibrous cap are seemly influenced more than those in the shoulder area.

Wu, Baijian; Pei, Xuan; Li, Zhi-Yong

2014-01-01

92

Non-pulsed electrochemical impregnation of flexible metallic battery plaques  

DOEpatents

A method of loading active battery material into porous, flexible, metallic battery plaques, comprises the following steps: precipitating nickel hydroxide active material within the plaque, by making the plaque cathodic, at a high current density, in an electro-precipitation cell also containing a consumable nickel anode and a solution comprising nickel nitrate, having a pH of between 2.0 and 2.8; electrochemically oxidizing the precipitate in caustic formation solution; and repeating the electro-precipitation step at a low current density.

Maskalick, Nicholas J. (Pittsburgh, PA)

1982-01-01

93

Interrelation Between Plaque Surface Morphology and Degree of Stenosis on Carotid Angiograms and the Risk of Ischemic Stroke in Patients With Symptomatic Carotid Stenosis  

Microsoft Academic Search

Background and Purpose—The risk of ischemic stroke distal to an atherothrombotic carotid stenosis increases with the degree of stenosis. The main mechanism of stroke is thought to be embolism from fissured or ruptured plaque, but there are few published data on the relationship between plaque morphology and severity of stenosis and their independent effects on the risk of ischemic stroke.

P. M. Rothwell; R. Gibson; C. P. Warlow

94

Longitudinal MRI Study on the Natural History of Carotid Artery Plaques in Symptomatic Patients  

PubMed Central

Purpose To investigate the natural history of carotid atherosclerosis in patients who experienced a TIA or ischemic stroke. Patients and Methods Ninety-two TIA/stroke patients (57 men, mean age 67.7±9.8 years) with ipsilateral <70% carotid stenosis underwent multisequence MRI of the plaque ipsilateral to the symptomatic side at baseline and after one year. For each plaque, several parameters were assessed at both time points. Results Carotid lumen, wall and total vessel (?=?carotid lumen and wall) volume did not significantly change. Forty-four patients had a plaque with a lipid-rich necrotic core (LRNC) at baseline, of which 34 also had a LRNC after one year. In three patients a LRNC appeared after one year. Thirty patients had a plaque with a thin and/or ruptured fibrous cap (FC) at both time points. In seven patients, FC status changed from thin and/or ruptured into thick and intact. In three patients, FC status changed from thick and intact into thin and/or ruptured. Twenty patients had intraplaque hemorrhage (IPH) at both time points. In four patients, IPH disappeared, whereas in three patients, new IPH appeared at follow-up. Conclusion In TIA/stroke patients, carotid plaque morphology does not significantly change over a one-year period. IPH and FC status change in a minority of patients.

Kwee, Robert M.; Truijman, Martine T. B.; van Oostenbrugge, Robert J.; Mess, Werner H.; Prins, Martin H.; Franke, Cees L.; Korten, Arthur G. G. C.; Wildberger, Joachim E.; Kooi, M. Eline

2012-01-01

95

Biology of atherosclerotic plaques: What we are learning from proteomic analysis  

Microsoft Academic Search

Atherosclerotic plaque rupture triggers the onset of cardiovascular complications such as myocardial infarction and stroke, which represent the main cause of death in western countries. Atherogenesis is a complex process characterized by lipid retention, proteolytic injury and a chronic inflammatory response. The resulting pathological vascular remodeling involves inflammatory cell recruitment, fibrosis, smooth muscle cell proliferation, neovascularization and intraplaque hemorrhage. However,

Luis Miguel Blanco-Colio; Jose Luis Martín-Ventura; Fernando Vivanco; Jean-Baptiste Michel; Olivier Meilhac; Jesús Egido

2006-01-01

96

[Achilles tendon rupture].  

PubMed

The treatment of acute of Achilles tendon rupture experienced a dynamic development in the last ten years. Decisive for this development was the application of MRI and above all the ultrasonography in the diagnostics of the pathological changes and injuries of tendons. The question of rupture morphology as well as different courses of healing could be now evaluated objectively. These advances led consequently to new modalities in treatment concepts and rehabilitation protocols. The decisive input for improvements of the outcome results and particularly the shortening of the rehabilitation period came with introduction of the early functional treatment in contrast to immobilizing plaster treatment. In a prospective randomized study (1987-1989) at the Trauma Dept. of the Hannover Medical School could show no statistical differences comparing functional non-operative with functional operative therapy with a special therapy boot (Variostabil/Adidas). The crucial criteria for therapy selection results from the sonographically measured position of the tendon stumps in plantar flexion (20 degrees). With complete adaptation of the tendons' ends surgical treatment does not achieve better results than non-operative functional treatment in term of tendon healing and functional outcome. Regarding the current therapeutic standards each method has is advantages and disadvantages. Both, the operative and non-operative functional treatment enable a stable tendon healing with a low risk of re-rupture (1-2%). Meanwhile there is consensus for early functional after-treatment of the operated Achilles' tendons. There seems to be a trend towards non-operative functional treatment in cases of adequate sonographical findings, or to minimal invasive surgical techniques. PMID:10798233

Thermann, H; Hüfner, T; Tscherne, H

2000-03-01

97

Plaque assay for murine norovirus.  

PubMed

Murine norovirus (MNV) is the only member of the Norovirus genus that efficiently grows in tissue culture. Cell lysis and cytopathic effect (CPE) are observed during MNV-1 infection of murine dendritic cells or macrophages. This property of MNV-1 can be used to quantify the number of infectious particles in a given sample by performing a plaque assay. The plaque assay relies on the ability of MNV-1 to lyse cells and to form holes in a confluent cell monolayer, which are called plaques. Multiple techniques can be used to detect viral infections in tissue culture, harvested tissue, clinical, and environmental samples, but not all measure the number of infectious particles (e.g. qRT-PCR). One way to quantify infectious viral particles is to perform a plaque assay, which will be described in detail below. A variation on the MNV plaque assay is the fluorescent focus assay, where MNV antigen is immunostained in cell monolayers. This assay can be faster, since viral antigen expression precedes plaque formation. It is also useful for titrating viruses unable to form plaques. However, the fluorescent focus assay requires additional resources beyond those of the plaque assay, such as antibodies and a microscope to count focus-forming units. Infectious MNV can also be quantified by determining the 50% Tissue Culture Infective Dose (TCID50). This assay measures the amount of virus required to produce CPE in 50% of inoculated tissue culture cells by endpoint titration. However, its limit of detection is higher compared to a plaque assay. In this article, we describe a plaque assay protocol that can be used to effectively determine the number of infectious MNV particles present in biological or environmental samples. This method is based on the preparation of 10-fold serial dilutions of MNV-containing samples, which are used to inoculate a monolayer of permissive cells (RAW 264.7 murine macrophage cells). Virus is allowed to attach to the cell monolayer for a given period of time and then aspirated before covering cells with a mixture of agarose and cell culture media. The agar enables the spread of viral progeny to neighboring cells while limiting spread to distantly located cells. Consequently, infected cells are lysed and form holes in the monolayer known as plaques. Upon sufficient spread of virus, plaques become visible following staining of cells with dyes, like neutral red, methylene blue, or crystal violet. At low dilutions, each plaque originates from one infectious viral particle and its progeny, which spread to neighboring cells. Thus, counting the number of plaques allows one to calculate plaque-forming units (PFU) present in the undiluted sample. PMID:22951568

Gonzalez-Hernandez, Mariam B; Bragazzi Cunha, Juliana; Wobus, Christiane E

2012-01-01

98

A finite element investigation on plaque vulnerability in realistic healthy and atherosclerotic human coronary arteries.  

PubMed

Atherosclerosis is the most common arterial disease. It has been shown that stresses that are induced during blood circulation can cause plaque rupture and, in turn, lead to thrombosis and stroke. In this study, finite element method is used to predict plaque vulnerability based on peak plaque stress using human samples. A total of 23 healthy and atherosclerotic human coronary arteries of 14 healthy and 9 atherosclerotic patients are excised within 5 h postmortem. The samples are mounted on an uniaxial tensile test machine, and the obtained mechanical properties are used in two-dimensional and three-dimensional finite element models. The results including the Neo-Hookean hyperelastic coefficients of the samples as well as peak plaque stresses are analyzed. The results indicate that the atherosclerotic human coronary arteries have significantly (p < 0.05) higher stiffness compared with the healthy ones. The hypocellular plaque also has the highest stress values and, as a result, is most likely (vulnerable) to rupture, while the calcified type has the lowest stress values and, consequently, is expected to remain stable. The results could be used in the plaque vulnerability anticipation and have clinical implications in interventions and surgeries, including balloon angioplasty, bypass, and stenting. PMID:23513986

Karimi, Alireza; Navidbakhsh, Mahdi; Faghihi, Shahab; Shojaei, Ahmad; Hassani, Kamran

2013-02-01

99

Routes to chemical plaque control  

Microsoft Academic Search

A logical approach to the prevention of periodontal disease is through excellent supragingival plaque control. Such control is not generally achieved by mechanical oral hygiene procedures alone. Thus, there is a clear rationale for the use of antiplaque agents to augment mechanical means. The principle routes to chemical plaque control are to prevent colonization of the tooth surface, to inhibit

D. Cummins

1991-01-01

100

Denitrification in human dental plaque  

Microsoft Academic Search

BACKGROUND: Microbial denitrification is not considered important in human-associated microbial communities. Accordingly, metabolic investigations of the microbial biofilm communities of human dental plaque have focused on aerobic respiration and acid fermentation of carbohydrates, even though it is known that the oral habitat is constantly exposed to nitrate (NO3-) concentrations in the millimolar range and that dental plaque houses bacteria that

Frank Schreiber; Peter Stief; Armin Gieseke; Ines M Heisterkamp; Willy Verstraete; Dirk de Beer; Paul Stoodley

2010-01-01

101

Intravascular Thermography for Assessing Vulnerable Plaques  

Microsoft Academic Search

Atherosclerosis and its cardiovascular complications remain the leading cause of death in developed countries. Current knowledge\\u000a of coronary artery disease progression has significantly evolved and the interest has been focused on the development of new\\u000a imaging techniques for the early detection of vulnerable lesions. Intracoronary thermography is a method that detects local\\u000a plaque inflammation. Clinical studies with intracoronary thermography have

Konstantinos Toutouzas; Maria Drakopoulou; Andreas Synetos; Christodoulos Stefanadis

2010-01-01

102

Plaque Assay for Rickettsia rickettsii  

PubMed Central

A plaque technique for the assay of Rickettsia rickettsii is described. The method employs primary chick or green monkey kidney monolayer cell cultures with either an agarose or special Noble agar overlay. Plaques were counted in 6 days and resultant titers correlated well with ld50 end points obtained by a standard assay in embryonated eggs. Identification of the plaque-forming organisms was accomplished by direct observation of rickettsiae-like bodies in the monolayer lesions, inhibition of plaques by antibiotics, sensitivity of plaques to specific immune serum, and failure to cultivate other microorganisms from the infected cells. Versatility of the test was demonstrated by assaying samples of rickettsiae from several different sources commonly used in our laboratory. These included infected yolk sacs, various cell cultures, and infected guinea pig tissue. Sufficient numbers of viable rickettsiae were present in the cells of a single lesion to permit direct recovery. Images

Weinberg, Edmund H.; Stakebake, Jack R.; Gerone, Peter J.

1969-01-01

103

A double layer plaque assay using spread plate technique for enumeration of bacteriophage MS2.  

PubMed

Bacteriophage MS2 is used widely as a model organism to estimate pathogenic virus survival in various environments, and is usually quantified by plaque assay. Although current plaque assays work well in enumeration of MS2 in environmental samples, quantification of MS2 calls for better visibility and higher consistency. In an attempt to improve the visibility and consistency of the current plaque assay, spread plate technique was introduced, instead of the pour plate technique used commonly in existing methods. Other parameters that influence the outcome of the plaque assay were also compared. Using spread plate technique resulted in an increase of plaque size by approximately 50% and contributed to a better visibility. Addition of supplements (glucose, CaCl2 and thiamine); reduction of agar thickness and hardness, also contributed to enhanced plaque visibility and increased plaque count. Among all the conditions tested, a supplemented thin bottom agar (10ml 1% agar) and a supplemented thin top agar (10ml 0.45% agar) with spread plate technique gave the maximum countable plaques with a minimum standard deviation. When compared to other methods, it produced significantly higher plaque count and lower variation. The optimized plaque assay significantly improved visibility and consistency of the existing plaque assay methods and could be used in quantification of MS2. PMID:24211298

Cormier, Jiemin; Janes, Marlene

2014-02-01

104

Intravascular photoacoustic imaging: a new tool for vulnerable plaque identification.  

PubMed

The vulnerable atherosclerotic plaque is believed to be at the root of the majority of acute coronary events. Even though the exact origins of plaque vulnerability remain elusive, the thin-cap fibroatheroma, characterized by a lipid-rich necrotic core covered by a thin fibrous cap, is considered to be the most prominent type of vulnerable plaque. No clinically available imaging technique can characterize atherosclerotic lesions to the extent needed to determine plaque vulnerability prognostically. Intravascular photoacoustic imaging (IVPA) has the potential to take a significant step in that direction by imaging both plaque structure and composition. IVPA is a natural extension of intravascular ultrasound that adds tissue type specificity to the images. IVPA utilizes the optical contrast provided by the differences in the absorption spectra of plaque components to image composition. Its capability to image lipids in human coronary atherosclerosis has been shown extensively ex vivo and has recently been translated to an in vivo animal model. Other disease markers that have been successfully targeted are calcium and inflammatory markers, such as macrophages and matrix metalloproteinase; the latter two through application of exogenous contrast agents. By simultaneously displaying plaque morphology and composition, IVPA can provide a powerful prognostic marker for disease progression, and as such has the potential to transform the current practice in percutaneous coronary intervention. PMID:24631379

Jansen, Krista; van Soest, Gijs; van der Steen, Antonius F W

2014-06-01

105

Pathology and Vulnerability of Atherosclerotic Plaque: Identification, Treatment Options, and Individual Patient Differences for Prevention of Stroke  

Microsoft Academic Search

Opinion statement  Vulnerable carotid plaques at risk for rupture\\/ulceration do not always correlate with the severity of stenosis at bifurcation\\u000a sites. Therefore, information on plaque morphology and composition is essential for identifying patients at high risk for\\u000a acute major cerebrovascular events. Traditional imaging modalities, including angiography and ultrasound, are slowly being\\u000a replaced by CT imaging, as this technology is readily available

Saami K. Yazdani; Marc Vorpahl; Elena Ladich; Renu Virmani

2010-01-01

106

Composition and genesis of calcium deposits in atheroma plaques.  

PubMed

Abstract The composition of atheromatous plaque determines its progression toward rupture or thrombosis. Although its histopathological structure has been widely studied, little attention has been paid to its structural and chemical composition and even less to its mineral component. Thirty-three atheromatous plaques were obtained by carotid thromboendarterectomy. Three types of materials were observed under polarized light microscopy: apatite crystals in the form of glomeruli (dark with plane polarized illumination and greensh with cross-polarized illumination); fibrous-like cholesterol (uncolored or grayish with plane-polarized illumination); and amorphous organic material as brownish deposits. SEM-EDX analysis showed an abundance of phosphorus and calcium in sufficient quantities to form calcium phosphates, and appreciably reduced levels of sodium. X-ray diffraction results differentiated samples into three groups: group I with predominance of hydroxyapatite-type crystals, group II with crystalline material containing an amorphous component, and group III with wholly amorphous material. The most abundant mineral in atheromatous plaque is hydroxyapatite, on which crystals of cholesterol and lipid nuclei are deposited, stratifying the plaque into layers that reflect the different stages of its formation. The difference in calcium and sodium concentrations between arteries with and without atheromata may indicate an important relationship in the pathophysiological development of calcium deposits. PMID:24134634

Lara, María Jesús; Ros, Eduardo; Sierra, Manuel; Dorronsoro, Carlos; Aguilar, José

2014-05-01

107

Imaging of the Fibrous Cap in Atherosclerotic Carotid Plaque  

SciTech Connect

In the last two decades, a substantial number of articles have been published to provide diagnostic solutions for patients with carotid atherosclerotic disease. These articles have resulted in a shift of opinion regarding the identification of stroke risk in patients with carotid atherosclerotic disease. In the recent past, the degree of carotid artery stenosis was the sole determinant for performing carotid intervention (carotid endarterectomy or carotid stenting) in these patients. We now know that the degree of stenosis is only one marker for future cerebrovascular events. If one wants to determine the risk of these events more accurately, other parameters must be taken into account; among these parameters are plaque composition, presence and state of the fibrous cap (FC), intraplaque haemorrhage, plaque ulceration, and plaque location. In particular, the FC is an important structure for the stability of the plaque, and its rupture is highly associated with a recent history of transient ischaemic attack or stroke. The subject of this review is imaging of the FC.

Saba, Luca, E-mail: lucasaba@tiscali.i [Azienda Ospedaliero-Universitaria di Cagliari, Department of Radiology (Italy); Potters, Fons; Lugt, Aad van der [Erasmus Medical Center Rotterdam, Department of Radiology (Netherlands); Mallarini, Giorgio [Azienda Ospedaliero-Universitaria di Cagliari, Department of Radiology (Italy)

2010-08-15

108

Impact of flow rates in a cardiac cycle on correlations between advanced human carotid plaque progression and mechanical flow shear stress and plaque wall stress  

Microsoft Academic Search

Background  Mechanical stresses are known to play important roles in atherosclerotic plaque initiation, progression and rupture. It has\\u000a been well-accepted that atherosclerosis initiation and early progression correlate negatively with flow wall shear stresses\\u000a (FSS). However, mechanisms governing advanced plaque progression are not well understood.\\u000a \\u000a \\u000a \\u000a \\u000a Method  In vivo serial MRI data (patient follow-up) were acquired from 14 patients after informed consent. Each patient

Chun Yang; Gador Canton; Chun Yuan; Marina Ferguson; Thomas S Hatsukami; Dalin Tang

2011-01-01

109

Painting blood vessels and atherosclerotic plaques with an adhesive drug depot  

PubMed Central

The treatment of diseased vasculature remains challenging, in part because of the difficulty in implanting drug-eluting devices without subjecting vessels to damaging mechanical forces. Implanting materials using adhesive forces could overcome this challenge, but materials have previously not been shown to durably adhere to intact endothelium under blood flow. Marine mussels secrete strong underwater adhesives that have been mimicked in synthetic systems. Here we develop a drug-eluting bioadhesive gel that can be locally and durably glued onto the inside surface of blood vessels. In a mouse model of atherosclerosis, inflamed plaques treated with steroid-eluting adhesive gels had reduced macrophage content and developed protective fibrous caps covering the plaque core. Treatment also lowered plasma cytokine levels and biomarkers of inflammation in the plaque. The drug-eluting devices developed here provide a general strategy for implanting therapeutics in the vasculature using adhesive forces and could potentially be used to stabilize rupture-prone plaques.

Kastrup, Christian J.; Nahrendorf, Matthias; Figueiredo, Jose Luiz; Lee, Haeshin; Kambhampati, Swetha; Lee, Timothy; Cho, Seung-Woo; Gorbatov, Rostic; Iwamoto, Yoshiko; Dang, Tram T.; Dutta, Partha; Yeon, Ju Hun; Cheng, Hao; Pritchard, Christopher D.; Vegas, Arturo J.; Siegel, Cory D.; MacDougall, Samantha; Okonkwo, Michael; Thai, Anh; Stone, James R.; Coury, Arthur J.; Weissleder, Ralph; Langer, Robert; Anderson, Daniel G.

2012-01-01

110

Painting blood vessels and atherosclerotic plaques with an adhesive drug depot.  

PubMed

The treatment of diseased vasculature remains challenging, in part because of the difficulty in implanting drug-eluting devices without subjecting vessels to damaging mechanical forces. Implanting materials using adhesive forces could overcome this challenge, but materials have previously not been shown to durably adhere to intact endothelium under blood flow. Marine mussels secrete strong underwater adhesives that have been mimicked in synthetic systems. Here we develop a drug-eluting bioadhesive gel that can be locally and durably glued onto the inside surface of blood vessels. In a mouse model of atherosclerosis, inflamed plaques treated with steroid-eluting adhesive gels had reduced macrophage content and developed protective fibrous caps covering the plaque core. Treatment also lowered plasma cytokine levels and biomarkers of inflammation in the plaque. The drug-eluting devices developed here provide a general strategy for implanting therapeutics in the vasculature using adhesive forces and could potentially be used to stabilize rupture-prone plaques. PMID:23236189

Kastrup, Christian J; Nahrendorf, Matthias; Figueiredo, Jose Luiz; Lee, Haeshin; Kambhampati, Swetha; Lee, Timothy; Cho, Seung-Woo; Gorbatov, Rostic; Iwamoto, Yoshiko; Dang, Tram T; Dutta, Partha; Yeon, Ju Hun; Cheng, Hao; Pritchard, Christopher D; Vegas, Arturo J; Siegel, Cory D; MacDougall, Samantha; Okonkwo, Michael; Thai, Anh; Stone, James R; Coury, Arthur J; Weissleder, Ralph; Langer, Robert; Anderson, Daniel G

2012-12-26

111

Coronary plaque imaging by coronary computed tomography angiography  

PubMed Central

Coronary computed tomography angiography (CTA) has become the useful noninvasive imaging modality alternative to the invasive coronary angiography for detecting coronary artery stenoses in patients with suspected coronary artery disease (CAD). With the development of technical aspects of coronary CTA, clinical practice and research are increasingly shifting toward defining the clinical implication of plaque morphology and patients outcomes by coronary CTA. In this review we discuss the coronary plaque morphology estimated by CTA beyond coronary angiography including the comparison to the currently available other imaging modalities used to examine morphological characteristics of the atherosclerotic plaque. Furthermore, this review underlies the value of a combined assessment of coronary anatomy and myocardial perfusion in patients with CAD, and adds to an increasing body of evidence suggesting an added diagnostic value when combining both modalities. We hope that an integrated, multi-modality imaging approach will become the gold standard for noninvasive evaluation of coronary plaque morphology and outcome data in clinical practice.

Sato, Akira

2014-01-01

112

Ruptured intracranial dermoid cysts  

Microsoft Academic Search

Summary  Rupture of intracranial dermoid cysts (RICDC) is a rare phenomenon. The mechanism of rupture, pathophysiology of fat in the\\u000a ventricles and subarachnoid spaces, possible complications, and proper management of such conditions are proposed on the basis\\u000a of a review of the literature and experience with two cases of ruptured intracranial dermoid cysts (One was in the pineal\\u000a region, while another

K. El-Bahy; A. Kotb; A. Galal; A. EL-Hakim

2006-01-01

113

An interactive treatment planning system for ophthalmic plaque radiotherapy.  

PubMed

Brachytherapy using removable episcleral plaques containing sealed radioisotope sources is being studied as an alternative to enucleation in the treatment of choroidal melanoma and other tumors of the eye. Encouraging early results have been reported, but late complications which lead to loss of vision continue to be a problem. A randomized national study, the Collaborative Ocular Melanoma Study (COMS) is currently in progress to evaluate the procedure. The COMS specified isotope is 125I. Precise dosimetric calculations near the plaque may correlate strongly with complications and could also be used to optimize isotope loading patterns in the plaques. A microcomputer based treatment planning system has been developed for ophthalmic plaque brachytherapy. The program incorporates an interactive, 3-dimensional, solid-surface, color-graphic interface. The program currently supports 125I and 192Ir seeds which are treated as anisotropic line sources. Collimation effects related to plaque structure are accounted for, permitting detailed study of shielding effectiveness near the lip of a plaque. A dose distribution matrix may be calculated in any subregion of a transverse, sagittal, or coronal planar cross section of the eye, in any plane transecting the plaque and crossing the eye diametrically, or on a spherical surface within or surrounding the eye. Spherical surfaces may be displayed as 3-dimensional perspective projections or as funduscopic diagrams. Isodose contours are interpolated from the dose matrix. A pointer is also available to explicitly calculate and display dose at any location on the dosimetry surface. An interactive editing capability allows new plaque designs to be rapidly added to the system. PMID:2318702

Astrahan, M A; Luxton, G; Jozsef, G; Kampp, T D; Liggett, P E; Sapozink, M D; Petrovich, Z

1990-03-01

114

IVUS-Based Computational Modeling and Planar Biaxial Artery Material Properties for Human Coronary Plaque Vulnerability Assessment  

PubMed Central

Image-based computational modeling has been introduced for vulnerable atherosclerotic plaques to identify critical mechanical conditions which may be used for better plaque assessment and rupture predictions. In vivo patient-specific coronary plaque models are lagging due to limitations on non-invasive image resolution, flow data, and vessel material properties. A framework is proposed to combine intravascular ultrasound (IVUS) imaging, biaxial mechanical testing and computational modeling with fluid-structure interactions and anisotropic material properties to acquire better and more complete plaque data and make more accurate plaque vulnerability assessment and predictions. Impact of pre-shrink-stretch process, vessel curvature and high blood pressure on stress, strain, flow velocity and flow maximum principal shear stress was investigated.

Liu, Haofei; Cai, Mingchao; Yang, Chun; Zheng, Jie; Bach, Richard; Kural, Mehmet H.; Billiar, Kristen L.; Muccigrosso, David; Lu, Dongsi; Tang, Dalin

2012-01-01

115

IVUS-based computational modeling and planar biaxial artery material properties for human coronary plaque vulnerability assessment.  

PubMed

Image-based computational modeling has been introduced for vulnerable atherosclerotic plaques to identify critical mechanical conditions which may be used for better plaque assessment and rupture predictions. In vivo patient-specific coronary plaque models are lagging due to limitations on non-invasive image resolution, flow data, and vessel material properties. A framework is proposed to combine intravascular ultrasound (IVUS) imaging, biaxial mechanical testing and computational modeling with fluid-structure interactions and anisotropic material properties to acquire better and more complete plaque data and make more accurate plaque vulnerability assessment and predictions. Impact of pre-shrink-stretch process, vessel curvature and high blood pressure on stress, strain, flow velocity and flow maximum principal shear stress was investigated. PMID:22428362

Liu, Haofei; Cai, Mingchao; Yang, Chun; Zheng, Jie; Bach, Richard; Kural, Mehmet H; Billiar, Kristen L; Muccigrosso, David; Lu, Dongsi; Tang, Dalin

2012-03-01

116

A feasibility study of carotid elastography for risk assessment of atherosclerotic plaques validated by magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Stroke is a leading cause of mortality worldwide. One of its main reasons is rupture of carotid atherosclerotic plaques. Conventional B-mode ultrasound images and Doppler/color flow measurements are mostly used to evaluate degree of stenosis, which underestimates plaque vulnerability. Alternatively, the correspondence between multi-contrast magnetic resonance imaging (MRI) features, plaque composition and histology has been well established. In this study, the feasibility of ultrasound carotid elastography in risk assessment of carotid atherosclerotic plaques is investigated. Preliminarily in-vivo results on a small number of human subjects are initially validated by multi-contrast, highresolution MRI, and it shows that maximum strain rate might be feasible to evaluate the plaque vulnerability.

Pan, Xiaochang; Huang, Lingyun; Huang, Manwei; Zhao, Xihai; He, Le; Yuan, Chun; Bai, Jing; Luo, Jianwen

2014-03-01

117

Dental plaque identification at home  

MedlinePLUS

... special tablets that contain a red dye that stains the plaque. One tablet is chewed thoroughly, moving ... this method is that it leaves no pink stains in the mouth. In the office, dentists are ...

118

Plaque removal with variable instrumentation.  

PubMed

The purpose of this study was to evaluate dental plaque removal in a normal healthy mouth, during routine oral hygiene appointments using different techniques and without the use of any disclosing agents. 12 dental hygienists, randomly selected from a continuing education course, were asked to perform oral hygiene on the same patient to remove all the supra-gingival plaque without any time restriction and without the use of a disclosing agents. The plaque index score (O'Leary) was assessed before and after each session with the use of fluorescine and UV light source by an independent examiner. 3 groups of instruments were utilized: group A: ultrasonic scalers + prophy cups; group B: ultrasonic scalers + prophy cups + dental floss; group C: Gracey curettes + prophy cups. While no group was able to remove all the plaque, groups B and C performed significantly better. PMID:9350554

Checchi, L; Forteleoni, G; Pelliccioni, G A; Loriga, G

1997-10-01

119

Disappearance of La Caille Plaque  

NASA Astrophysics Data System (ADS)

A bronze plaque erected to the memory of N.-L. de La Caille near the site of his observatory in Central Cape Town, has been stolen by metal thieves. It was designed by the famous architect Sir Herbert Baker.

2010-04-01

120

Carotid endarterectomy for high plaques.  

PubMed

Seventeen instances of high plaque (plaque extending up to the level of the second cervical vertebra) were encountered out of a total of 454 carotid endarterectomies (3.7 percent). With careful dissection and knowledge of anatomy superior to hypoglossal nerve, carotid endarterectomy was accomplished without resorting to mandibular subluxation or dislocation. There was no operative mortality or perioperative strokes. One patient had perioperative myocardial infarction and another sustained temporary glossopharyngeal nerve dysfunction. High carotid plaques were more common in male patients with bilateral stenoses or contralateral internal carotid occlusion and could be suspected by findings of preoperative carotid arteriography in some instances. In the majority of cases, extension of high plaque in a tongue-shaped manner on the posterior wall of the internal carotid artery was an unexpected finding at the time of carotid endarterectomy. PMID:2929868

Hans, S S; Shah, S; Hans, B

1989-04-01

121

Periodontal pathogens in atheromatous plaque.  

PubMed

Background: There has been increasing attention paid in recent years to the possibility that oral bacterial infection, particularly periodontal disease may influence the initiation and or progression of systemic diseases. These studies confirm the observation that heart disease is the most commonly found systemic condition in patients with periodontal disease. Moreover, the literature has also highlighted substantial evidence indicating the presence of Gram-negative periodontal pathogens in atheromatous plaques. Aim: This study intends to investigate the possible association between periodontal health and coronary artery disease by evaluating periodontal status, association between the periodontal plaque and coronary atheromatous plaques for presence of micro-organisms such as, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia. Materials and methods: A case-control study was designed with seven patients who had undergone coronary endarterectomy for cardiovascular disease and 28 controls. The periodontal examination for cases was performed 1 day before vascular surgery and the controls were clinically examined. The atheromatous plaque sample collected during endarterectomy and the intraoral plaque samples were subjected to polymerase chain reaction for identification of A. actinomycetemcomitans, P. gingivalis, P. intermedia and T. forsythia. Results: The presence of periodontal bacteria DNA in coronary atheromatous plaques and sub-gingival plaque samples of the same patients was confirmed by this study. CONCLUSION A correlation was established between putative bacteria contributing to atheromatous plaques and species associated with periodontal disease. One particularly important study to be carried out is the investigation of a possible clinically meaningful reduction in coronary heart disease resulting from the prevention or treatment of periodontal disease. PMID:24943760

Rath, Saroj K; Mukherjee, Manish; Kaushik, R; Sen, Sourav; Kumar, Mukesh

2014-01-01

122

Recent concepts in plaque formation.  

PubMed

Dental plaque is an adherent, bacterial film, and is the main pathological agent for periodontal diseases. The formation of dental plaque can occur both supragingivally and subgingivally. The development of plaque is a three-step process. Following the formation of a pellicle, pioneer micro-organisms will adhere to it, proliferate and form colonies. The final stage involves the aggregation of filamentous organisms and spirochetes into a cohesive biofilm. Many products of the plaque bacteria reach the subepithelial tissue, causing inflammatory responses such as increased vascularity and leukocyte diapedesis. Both supragingival and subgingival plaque may form a hard, mineralized mass called calculus. The surface of calculus harbours bacteria, which may exacerbate the inflammatory responses. An effective oral antiseptic must be active against a wide range of Gram-positive and Gram-negative bacterial species, including streptococci and fusobacteria. Ideally, an effective agent would also penetrate the plaque biofilm. Data show that essential oil and chlorhexidine mouthwashes have the broadest antimicrobial effects. PMID:12787195

Bernimoulin, J-P

2003-01-01

123

Identification of amyloid plaques in retinas from Alzheimer's patients and noninvasive in vivo optical imaging of retinal plaques in a mouse model  

Microsoft Academic Search

Noninvasive monitoring of ?-amyloid (A?) plaques, the neuropathological hallmarks of Alzheimer's disease (AD), is critical for AD diagnosis and prognosis. Current visualization of A? plaques in brains of live patients and animal models is limited in specificity and resolution. The retina as an extension of the brain presents an appealing target for a live, noninvasive optical imaging of AD if

Maya Koronyo-Hamaoui; Yosef Koronyo; Alexander V. Ljubimov; Carol A. Miller; MinHee K. Ko; Keith L. Black; Michal Schwartz; Daniel L. Farkas

2011-01-01

124

Leptin Locally Synthesized in Carotid Atherosclerotic Plaques Could Be Associated With Lesion Instability and Cerebral Emboli  

PubMed Central

Background Unstable carotid plaques cause cerebral emboli. Leptin promotes atherosclerosis and vessel wall remodeling. We hypothesized that carotid atherosclerotic lesion instability is associated with local leptin synthesis. Methods and Results Carotid endarterectomy plaques from symptomatic (n=40) and asymptomatic patients with progressive stenosis (n=38) were analyzed for local expression of leptin, tumor necrosis factor (TNF)-?, and plasminogen activator inhibitor type 1. All lesions exhibited advanced atherosclerosis inclusive of thick- and thin-cap fibroatheromas or lesion rupture. Symptomatic lesions exhibited more plaque ruptures and macrophage infiltration (P=0.001 and P=0.05, respectively). Symptomatic plaques showed preferential leptin, TNF-?, and plasminogen activator inhibitor type 1 transcript (P=0.03, P=0.04, and P=0.05, respectively). Leptin mRNA and antigen in macrophages and smooth muscle cells were confirmed by in situ hybridization and immunohistochemistry. Plasma leptin levels were not significantly different between groups (P=1.0), whereas TNF-? was significantly increased in symptomatic patients (P=0.006). Human aortic smooth muscle cell culture stimulated by TNF-?, lipopolysaccharide, or lipoteichoic acid revealed 6-, 6.7-, and 6-fold increased secreted leptin antigen, respectively, at 72 hours (P<0.05). Conclusions Neurologically symptomatic patients overexpress leptin mRNA and synthesize leptin protein in carotid plaque macrophages and smooth muscle cells. Local leptin induction, presumably by TNF-?, could exert paracrine or autocrine effects, thereby contributing to the pathogenesis of lesion instability. Clinical Trial Registration URL: www.Clinicaltrials.gov. Unique identifier: NCT00449306.

Schneiderman, Jacob; Schaefer, Katrin; Kolodgie, Frank D.; Savion, Naphtali; Kotev-Emeth, Shlomo; Dardik, Rima; Simon, Amos J.; Halak, Moshe; Pariente, Clara; Engelberg, Isaac; Konstantinides, Stavros; Virmani, Renu

2012-01-01

125

Plaque Assay for Murine Norovirus  

PubMed Central

Murine norovirus (MNV) is the only member of the Norovirus genus that efficiently grows in tissue culture 1, 2. Cell lysis and cytopathic effect (CPE) are observed during MNV-1 infection of murine dendritic cells or macrophages 1. This property of MNV-1 can be used to quantify the number of infectious particles in a given sample by performing a plaque assay 1. The plaque assay relies on the ability of MNV-1 to lyse cells and to form holes in a confluent cell monolayer, which are called plaques 3. Multiple techniques can be used to detect viral infections in tissue culture, harvested tissue, clinical, and environmental samples, but not all measure the number of infectious particles (e.g. qRT-PCR). One way to quantify infectious viral particles is to perform a plaque assay 3, which will be described in detail below. A variation on the MNV plaque assay is the fluorescent focus assay, where MNV antigen is immunostained in cell monolayers 4. This assay can be faster, since viral antigen expression precedes plaque formation. It is also useful for titrating viruses unable to form plaques. However, the fluorescent focus assay requires additional resources beyond those of the plaque assay, such as antibodies and a microscope to count focus-forming units. Infectious MNV can also be quantified by determining the 50% Tissue Culture Infective Dose (TCID50) 3. This assay measures the amount of virus required to produce CPE in 50% of inoculated tissue culture cells by endpoint titration 5. However, its limit of detection is higher compared to a plaque assay 4. In this article, we describe a plaque assay protocol that can be used to effectively determine the number of infectious MNV particles present in biological or environmental samples 1, 4, 6. This method is based on the preparation of 10-fold serial dilutions of MNV-containing samples, which are used to inoculate a monolayer of permissive cells (RAW 264.7 murine macrophage cells). Virus is allowed to attach to the cell monolayer for a given period of time and then aspirated before covering cells with a mixture of agarose and cell culture media. The agar enables the spread of viral progeny to neighboring cells while limiting spread to distantly located cells. Consequently, infected cells are lysed and form holes in the monolayer known as plaques. Upon sufficient spread of virus, plaques become visible following staining of cells with dyes, like neutral red, methylene blue, or crystal violet. At low dilutions, each plaque originates from one infectious viral particle and its progeny, which spread to neighboring cells. Thus, counting the number of plaques allows one to calculate plaque-forming units (PFU) present in the undiluted sample 3.

Gonzalez-Hernandez, Mariam B.; Bragazzi Cunha, Juliana; Wobus, Christiane E.

2012-01-01

126

Ruptured intracranial dermoid cyst  

PubMed Central

Rupture of an intracranial dermoid cyst is a rare event with considerable associated morbidity and potential mortality. We present a case of intracranial rupture of a dermoid cystic tumor with consequent dissemination of subarachnoid fat droplets resulting in acute aseptic chemical meningitis. Radiographic findings, operative treatment, and pathologic features are described.

Barnett, David W.; Snipes, George J.; Layton, Kennith F.; Opatowsky, Michael J.

2012-01-01

127

Ruptured intracranial dermoid cysts  

Microsoft Academic Search

BACKGROUNDIntracranial dermoid cysts are rare congenital neoplasms that are believed to arise from ectopic cell rests incorporated in the closing neural tube. The rupture of an intracranial dermoid cyst is a relatively rare event that typically occurs spontaneously. In the past it was believed that rupture is always fatal, a hypothesis that is not supported by more recently reported cases.

Ruediger Stendel; Terttu Aulikki Pietilä; Kerstin Lehmann; Ralf Kurth; Olaf Suess; Mario Brock

2002-01-01

128

Non-calcified coronary atherosclerotic plaque visualization on CT: effects of contrast-enhancement and lipid-content fractions.  

PubMed

Computed tomography (CT) may characterize lipid-rich and presumably rupture-prone non-calcified coronary atherosclerotic plaque based on its Hounsfield-Unit (HU), but still inconclusively. This study aimed to evaluate factors influencing the HU-value of non-calcified plaque using software simulation. Several realistic virtual plaqueburdened coronary phantoms were constructed at 5 ?m resolution. CT scanning was simulated with settings resembling a 64-row multi-detector CT (64-MDCT) and reconstructed at 64-MDCT (0.4 mm) and MicroCT (48 ?m) resolutions. Influences of lumen contrast-enhancement, stenosis-grades, and plaque compositions on plaque visualization were analyzed. Lumen contrast-enhancement and mean plaque HU-value were positively correlated (R(2) > 0.92), with approximately the same slopes for all plaque compositions. Percentage lipid-content and mean plaque HU-value were negatively correlated (R(2) > 0.98). Stenosis-grade and noise had minimal influence on the correlations. Influence of lumen contrast-enhancement on plaque HU-value was following a specific exponentially declining pattern (y = Ae(-?x) + c) from the lumen border until 2-pixel radius. Outside 2-pixel radius, plaque HU-values deviated maximally 5 HU from non-contrast-enhanced reference. Thus, to avoid lumen contrast-enhancement influence, plaques should be measured outside 2-pixel radius from the lumen border. Based on the patterns found, a lumen influence correction algorithm may be developed. HU-based plaque percentage lipid-content determination might serve as an alternative plaque characterization method. However, its applicability is still hindered by many inherent limitations. PMID:23324971

Kristanto, Wisnumurti; van Ooijen, Peter M A; Greuter, Marcel J W; Groen, Jaap M; Vliegenthart, Rozemarijn; Oudkerk, Matthijs

2013-06-01

129

Adhesive Strength of Atherosclerotic Plaque in a Mouse Model Depends on Local Collagen Content and Elastin Fragmentation  

PubMed Central

Atherosclerotic plaque rupture is a major cause of myocardial infarction and ischemic stroke. The adhesive strength of the bond between a plaque and the vascular wall, measured as local energy release rate, G, is used for quantitative plaque stability estimation. We tested the hypothesis that adhesive strength varies with plaque composition. Matrix metalloproteinase-12 (MMP12) deficiency was previously reported to alter lesion composition. To estimate G values, peeling experiments are performed on aortic plaques from apolipoprotein E knockout (apoE KO) and apoE MMP12 double knockout (DKO) male mice after 8 months on high-fat diet. For plaques in apoE KO and apoE MMP12 DKO mice, experimental values for G differ significantly (p<0.002) between genotypes, averaging 19.2 Joule/m2 and 12.1 J/m2, respectively. Histology confirms that plaques delaminate along their interface with the underlying internal elastic lamina (IEL) in both genotypes. Quantitative image analysis of stained tissue sections demonstrates a significant positive correlation (p<0.05) between local collagen content of lesions and G values in both genotypes, indicating that adhesive strength of plaques depends on local collagen content. Surprisingly, macrophage content of aortic plaques is neither significantly correlated with G values nor significantly different between genotypes. The IEL underlying plaques in apoE KO mice is significantly more fragmented (number of breaks and length of breaks) than in apoE MMP12 DKO mice, suggesting that elastin fragmentation also influences adhesion strength of plaques. Overall, our results suggest that plaques adhere more strongly to the underlying IEL in apoE KO mice than in apoE MMP12 DKO mice.

Wang, Ying; Johnson, John A.; Fulp, Abigail; Sutton, Michael A.; Lessner, Susan M.

2012-01-01

130

Doxycycline Stabilizes Vulnerable Plaque via Inhibiting Matrix Metalloproteinases and Attenuating Inflammation in Rabbits  

PubMed Central

Enhanced matrix metalloproteinases (MMPs) activity is implicated in the process of atherosclerotic plaque instability. We hypothesized that doxycycline, a broad MMPs inhibitor, was as effective as simvastatin in reducing the incidence of plaque disruption. Thirty rabbits underwent aortic balloon injury and were fed a high-fat diet for 20 weeks. At the end of week 8, the rabbits were divided into three groups for 12-week treatment: a doxycycline-treated group that received oral doxycycline at a dose of 10 mg/kg/d, a simvastatin-treated group that received oral simvastatin at a dose of 5 mg/kg/d, and a control group that received no treatment. At the end of week 20, pharmacological triggering was performed to induce plaque rupture. Biochemical, ultrasonographic, pathologic, immunohistochemical and mRNA expression studies were performed. The results showed that oral administration of doxycycline resulted in a significant increase in the thickness of the fibrous cap of the aortic plaque whereas there was a substantial reduction of MMPs expression, local and systemic inflammation, and aortic plaque vulnerability. The incidence of plaque rupture with either treatment (0% for both) was significantly lower than that for controls (56.0%, P<0.05). There was no significant difference between doxycycline-treated group and simvastatin-treated group in any serological, ultrasonographic, pathologic, immunohistochemical and mRNA expression measurement except for the serum lipid levels that were higher with doxycycline than with simvastatin treatment. In conclusion, doxycycline at a common antimicrobial dose stabilizes atherosclerotic lesions via inhibiting matrix metalloproteinases and attenuating inflammation in a rabbit model of vulnerable plaque. These effects were similar to a large dose of simvastatin and independent of serum lipid levels.

Dong, Mei; Zhong, Lin; Chen, Wen Qiang; Ji, Xiao Ping; Zhang, Mei; Zhao, Yu Xia; Li, Li; Yao, Gui Hua; Zhang, Peng Fei; Zhang, Cheng; Zhang, Lei; Zhang, Yun

2012-01-01

131

Leukotriene B4 Levels in Human Atherosclerotic Plaques and Abdominal Aortic Aneurysms  

PubMed Central

Background Leukotriene B4 (LTB4) has been associated with the initiation and progression of atherosclerosis and abdominal aortic aneurysm (AAA) formation. However, associations of LTB4 levels with tissue characteristics and adverse clinical outcome of advanced atherosclerosis and AAA are scarcely studied. We hypothesized that LTB4 levels are associated with a vulnerable plaque phenotype and adverse clinical outcome. Furthermore, that LTB4 levels are associated with inflammatory AAA and adverse clinical outcome. Methods Atherosclerotic plaques and AAA specimens were selected from two independent databases for LTB4 measurements. Plaques were isolated during carotid endarterectomy from asymptomatic (n?=?58) or symptomatic (n?=?317) patients, classified prior to surgery. LTB4 levels were measured without prior lipid extraction and levels were corrected for protein content. LTB4 levels were related to plaque phenotype, baseline patient characteristics and clinical outcome within three years following surgery. Seven non-diseased mammary artery specimens served as controls. AAA specimens were isolated during open repair, classified as elective (n?=?189), symptomatic (n?=?29) or ruptured (n?=?23). LTB4 levels were measured similar to the plaque measurements and were related to tissue characteristics, baseline patient characteristics and clinical outcome. Twenty-six non-diseased aortic specimens served as controls. Results LTB4 levels corrected for protein content were not significantly associated with histological characteristics specific for vulnerable plaques or inflammatory AAA as well as clinical presentation. Moreover, it could not predict secondary manifestations independently investigated in both databases. However, LTB4 levels were significantly lower in controls compared to plaque (p?=?0.025) or AAA (p?=?0.017). Conclusions LTB4 levels were not associated with a vulnerable plaque phenotype or inflammatory AAA or clinical presentation. This study does not provide supportive evidence for a role of LTB4 in atherosclerotic plaque destabilization or AAA expansion. However, these data should be interpreted with care, since LTB4 measurements were performed without prior lipid extractions.

van den Borne, Pleunie; van der Laan, Sander W.; Bovens, Sandra M.; Koole, Dave; Kowala, Mark C.; Michael, Laura F.; Schoneveld, Arjan H.; van de Weg, Sander M.; Velema, Evelyn; de Vries, Jean-Paul; de Borst, Gert J.; Moll, Frans L.; de Kleijn, Dominique P. V.; Quax, Paul H. A.; Hoefer, Imo E.; Pasterkamp, Gerard

2014-01-01

132

Coronary artery atherectomy reduces plaque shear strains: An endovascular elastography imaging study.  

PubMed

Mechanical response and properties of the arterial wall can be used to identify the biomechanical instability of plaques and predict their vulnerability to rupture. Shear strain elastography (SSE) is proposed to identify vulnerable plaque features attributed to mechanical structural heterogeneities. The aims of this study were: 1) to report on the potential of SSE to identify atherosclerotic plaques; and 2) to use SSE maps to highlight biomechanical changes in lesion characteristics after directional coronary atherectomy (DCA) interventions. For this purpose, SSE was imaged using in vivo intravascular ultrasound (IVUS) radio-frequency data collected from 12 atherosclerotic patients before and after DCA intervention. Coronary atherosclerotic plaques (pre-DCA) showed high SSE magnitudes with large affected areas. There were good correlations between SSE levels and soft plaque content (i.e., cellular fibrosis, thrombosis and fibrin) (mean |SSE| vs. soft plaque content: r = 0.82, p < 0.01). Significant differences were noticed between SSE images before and after DCA. Stable arteries (post-DCA) exhibited lower values than pre-DCA vessels (e.g., pre-DCA: mean |SSE| = 3.9 ± 0.2% vs. 1.1 ± 0.2% post-DCA, p < 0.001). Furthermore, SSE magnitude was statistically higher in plaques with a high level of inflammation (e.g., mean |SSE| had values of 4.8 ± 0.4% in plaques with high inflammation, whereas it was reduced to 1.8 ± 0.2% with no inflammation, p < 0.01). This study demonstrates the potential of the IVUS-based SSE technique to detect vulnerable plaques in vivo. PMID:24835433

Keshavarz-Motamed, Zahra; Saijo, Yoshifumi; Majdouline, Younes; Riou, Laurent; Ohayon, Jacques; Cloutier, Guy

2014-07-01

133

The rhythmic expression of clock genes attenuated in human plaque-derived vascular smooth muscle cells  

PubMed Central

Background Acute myocardial infarction and stroke are more likely to occur in the early morning. Circadian pacemakers are considered to be involved in the process. Many peripheral tissues and cells also contain clock systems. In this study, we examined whether the primary cultured human plaque-derived vascular smooth muscle cells (VSMCs) process circadian rhythmicity; furthermore, we investigated the expression difference of clock genes between normal human carotid VSMCs and human plaque-derived VSMCs. Methods Fifty-six human carotid plaques provided the atherosclerotic tissue, and 21 samples yielded viable cultured primary VSMCs. The normal carotid VSMCs were cultured from donors’ normal carotids. The mRNA levels of the target genes were measured by Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). Results After serum shock, both types of cells showed clear circadian expressions of Bmal1, Cry1, Cry2, Per1, Per2, Per3 and Rev-erb? mRNA; meanwhile the Clock mRNA show a rhythmic expression in plaque-derived SMCs but not in normal carotid VSMCs. The expression levels of these main clock genes were significantly attenuated in human plaque-derived VSMCs compared with normal human carotid VSMCs. The rhythm of Bmal1 mRNA in plaque-derived VSMCs was changed. Conclusion The present results demonstrate that the human plaque-derived VSMCs possess different circadian rhythmicity from that of normal carotid VSMCs. The rhythm changes of clock genes in plaque-derived VSMCs may be involved in the process of atherosclerosis and finally promote the rupture of plaque.

2014-01-01

134

Surgical treatment of distal biceps rupture.  

PubMed

Rupture of the distal biceps tendon accounts for 10% of all biceps brachii ruptures. Injuries typically occur in the dominant elbow of men aged 40 to 49 years during eccentric contraction of the biceps. Degenerative changes, decreased vascularity, and tendon impingement may precede rupture. Although nonsurgical management is an option, healthy, active persons with distal biceps tendon ruptures benefit from early surgical repair, gaining improved strength in forearm supination and, to a lesser degree, elbow flexion. Biomechanical studies have tested the strength and displacement of various repairs; the suspensory cortical button technique exhibits maximum peak load to failure in vitro, and suture anchor and interosseous screw techniques yield the least displacement. Surgical complications include sensory and motor neurapraxia, infection, and heterotopic ossification. Current trends in postoperative rehabilitation include an early return to motion and to activities of daily living. PMID:20190104

Sutton, Karen M; Dodds, Seth D; Ahmad, Christopher S; Sethi, Paul M

2010-03-01

135

An incisor plaque model in rats.  

PubMed

An in vivo model for studying plaque accumulation in rats has been described. This model investigates plaque formation on the mandibular incisors in animals which have been found to be rapid plaque-formers during a pre-test period. The accessibility of these tooth surfaces permits the removal of plaque prior to initiation of tests, the use of test groups balanced on the basis of plaque-forming potential, and interim assessments of plaque formation throughout the test period. In addition, baseline plaque scores of near zero can be attained, thereby permitting investigations of the impact of experimental measures on plaque formation. Moreover, the model permits intermittent plaque assessments throughout the test period. This model was found to have adequate sensitivity to distinguish effects between antimicrobial agents known to differ in their clinical activity and to detect differences between varying concentrations of the same agent. PMID:6582077

Schemehorn, B R; McDonald, J L; Stookey, G K; Park, K K

1984-01-01

136

Denitrification in human dental plaque  

PubMed Central

Background Microbial denitrification is not considered important in human-associated microbial communities. Accordingly, metabolic investigations of the microbial biofilm communities of human dental plaque have focused on aerobic respiration and acid fermentation of carbohydrates, even though it is known that the oral habitat is constantly exposed to nitrate (NO3-) concentrations in the millimolar range and that dental plaque houses bacteria that can reduce this NO3- to nitrite (NO2-). Results We show that dental plaque mediates denitrification of NO3- to nitric oxide (NO), nitrous oxide (N2O), and dinitrogen (N2) using microsensor measurements, 15N isotopic labelling and molecular detection of denitrification genes. In vivo N2O accumulation rates in the mouth depended on the presence of dental plaque and on salivary NO3- concentrations. NO and N2O production by denitrification occurred under aerobic conditions and was regulated by plaque pH. Conclusions Increases of NO concentrations were in the range of effective concentrations for NO signalling to human host cells and, thus, may locally affect blood flow, signalling between nerves and inflammatory processes in the gum. This is specifically significant for the understanding of periodontal diseases, where NO has been shown to play a key role, but where gingival cells are believed to be the only source of NO. More generally, this study establishes denitrification by human-associated microbial communities as a significant metabolic pathway which, due to concurrent NO formation, provides a basis for symbiotic interactions.

2010-01-01

137

Intravascular probe for detection of vulnerable plaque  

NASA Astrophysics Data System (ADS)

Coronary angiography is unable to define the status of the atheroma, and only measures the luminal dimensions of the blood vessel, without providing information about plaque content. Up to 70% of heart attacks are caused by minimally obstructive vulnerable plaques, which are too small to be detected adequately by angiography. We have developed an intravascular imaging detector to identify vulnerable coronary artery plaques. The detector works by sensing beta or conversion electron radiotracer emissions from plaque-binding radiotracers. The device overcomes the technical constraints of size, sensitivity and conformance to the intravascular environment. The detector at the distal end of the catheter uses six 7mm long by 0.5mm diameter scintillation fibers coupled to 1.5m long plastic fibers. The fibers are offset from each other longitudinally by 6mm and arranged spirally around a guide wire in the catheter. At the proximal end of the catheter the optical fibers are coupled to an interface box with a snap on connector. The interface box contains a position sensitive photomultiplier tube (PSPMT) to decode the individual fibers. The whole detector assembly fits into an 8-French (2.7 mm in diameter) catheter. The PSPMT image is further decoded with software to give a linear image, the total instantaneous count rate and an audio output whose tone corresponds to the count rate. The device was tested with F-18 and Tl-204 sources. Spectrometric response, spatial resolution, sensitivity and beta to background ratio were measured. System resolution is 6 mm and the sensitivity is >500 cps / micrometers Ci when the source is 1 mm from the detector. The beta to background ratio was 11.2 for F-18 measured on a single fiber. The current device will lead to a system allowing imaging of labeled vulnerable plaque in coronary arteries. This type of signature is expected to enable targeted and cost effective therapies to prevent acute coronary artery diseases such as: unstable angina, acute myocardial infarction, and sudden cardiac death.

Patt, Bradley E.; Iwanczyk, Jan S.; MacDonald, Lawrence R.; Yamaguchi, Yuko; Tull, Carolyn R.; Janecek, Martin; Hoffman, Edward J.; Strauss, H. William; Tsugita, Ross; Ghazarossian, Vartan

2001-12-01

138

Non-invasive measurement of coronary plaque from coronary CT angiography and its clinical implications.  

PubMed

Coronary CT angiography (CTA) is increasingly used worldwide for direct, non-invasive evaluation of the coronary arteries. Advances in computed tomography (CT) technology over the last decade have enabled such reliable imaging of the coronary arteries. Beyond arterial stenosis, coronary CTA also permits assessment of atherosclerotic plaque (including plaque burden) and coronary artery remodeling, previously only achievable through invasive means. It has been shown that coronary plaque volumes for non-calcified and mixed plaques and the arterial remodeling index, correlate closely with invasive intravascular ultrasound. Several studies have also shown a strong relationship of adverse plaque features imaged by coronary CTA with acute coronary syndrome, all-cause death, major adverse cardiovascular events and myocardial ischemia. The aim of this review is to summarize current methods for quantitative measurement of atherosclerotic plaque features from coronary CTA and to discuss their clinical implications. PMID:23984930

Dey, Damini; Schuhbaeck, Annika; Min, James K; Berman, Daniel S; Achenbach, Stephan

2013-08-01

139

[Ruptured abdominal aortic aneurysm].  

PubMed

Rupture of the abdominal aortic aneurysm is a high lethal risk pathology, which requires precise diagnosis and urgent and efficient surgical treatment. Despite improved diagnostic capabilities (echoscopy, in specialized departments--angiography, computed tomography, magnetic nucleus resonance), mortality related to this pathology remains high in intensive care units. In the present article data concerning prevalence and clinical outcomes of the rupture of the abdominal aortic aneurysm for 1999-2001 is presented in detail. During this period 22 patients have undergone surgery due to abdominal aortic aneurysm rupture. Described are most prevalent complications, mortality rates and causes, analyzed are treatment strategy and tactics. PMID:12474751

Urbonavicius, Sigitas; Antusevas, Aleksandras

2002-01-01

140

Magnetic Resonance Imaging of Carotid Atherosclerotic Plaque in Clinically Suspected Acute Transient Ischemic Attack and Acute Ischemic Stroke  

PubMed Central

Background Carotid atherosclerotic plaque rupture is thought to cause transient ischemic attack (TIA) and ischemic stroke (IS). Pathological hallmarks of these plaques have been identified through observational studies. Although generally accepted, the relationship between cerebral thromboembolism and in situ atherosclerotic plaque morphology has never been directly observed noninvasively in the acute setting. Methods and Results Consecutive acutely symptomatic patients referred for stroke protocol magnetic resonance imaging/angiography underwent additional T1- and T2-weighted carotid bifurcation imaging with the use of a 3-dimensional technique with blood signal suppression. Two blinded reviewers performed plaque gradings according to the American Heart Association classification system. Discharge outcomes and brain magnetic resonance imaging results were obtained. Image quality for plaque characterization was adequate in 86 of 106 patients (81%). Eight TIA/IS patients with noncarotid pathogenesis were excluded, yielding 78 study patients (38 men and 40 women with a mean age of 64.3 years, SD 14.7) with 156 paired watershed vessel/cerebral hemisphere observations. Thirty-seven patients had 40 TIA/IS events. There was a significant association between type VI plaque (demonstrating cap rupture, hemorrhage, and/or thrombosis) and ipsilateral TIA/IS (P<0.001). A multiple logistic regression model including standard Framingham risk factors and type VI plaque was constructed. Type VI plaque was the dominant outcome-associated observation achieving significance (P<0.0001; odds ratio, 11.66; 95% confidence interval, 5.31 to 25.60). Conclusions In situ type VI carotid bifurcation region plaque identified by magnetic resonance imaging is associated with ipsilateral acute TIA/IS as an independent identifier of events, thereby supporting the dominant disease pathophysiology.

Parmar, Jaywant P.; Rogers, Walter J.; Mugler, John P.; Baskurt, Erol; Altes, Talissa A.; Nandalur, Kiran R.; Stukenborg, George J.; Phillips, C. Douglas; Hagspiel, Klaus D.; Matsumoto, Alan H.; Dake, Michael D.; Kramer, Christopher M.

2010-01-01

141

Identification of carotid plaque tissue properties using an experimental-numerical approach.  

PubMed

A biomechanical stress analysis could help to identify carotid plaques that are vulnerable to rupture, and hence reduce the risk of thrombotic strokes. Mechanical stress predictions critically depend on the plaque's constitutive properties, and the present study introduces a concept to derive viscoelastic parameters through an experimental-numerical approach. Carotid plaques were harvested from two patients during carotid endarterectomy (CEA), and, in total, nine test specimens were investigated. A novel in-vitro mechanical testing protocol, which allows for dynamic testing, keeping the carotid plaque components together, was introduced. Macroscopic pictures overlaid by histological stains allowed for the segmentation of plaque tissues, in order to develop high-fidelity and low-fidelity Finite Element Method (FEM) models of the test specimens. The FEM models together with load-displacement data from the mechanical testing were used to extract constitutive parameters through inverse parameter estimation. The applied inverse parameter estimation runs in stages, first addressing the hyperelastic parameters then the viscoelastic ones. Load-displacement curves from the mechanical testing showed strain stiffening and viscoelasticity, as is expected for both normal and diseased carotid tissue. The estimated constitutive properties of plaque tissue were comparable to previously reported studies. Due to the highly non-linear elasticity of vascular tissue, the applied parameter estimation approach is, as with many similar approaches, sensitive to the initial guess of the parameters. PMID:23790614

Heiland, Vincent M; Forsell, Caroline; Roy, Joy; Hedin, Ulf; Gasser, T Christian

2013-11-01

142

Imaging plaques to predict and better manage patients with acute coronary events.  

PubMed

Culprit lesions of patients, who have had an acute coronary syndrome commonly, are ruptured coronary plaques with superimposed thrombus. The precursor of such lesions is an inflamed thin-capped fibroatheroma. These plaques can be imaged by means of invasive techniques, such as intravascular ultrasound (and derived techniques), optical coherence tomography, and near-infrared spectroscopy. Often these patients exhibit similar (multiple) plaques beyond the culprit lesion. These remote plaques can be assessed noninvasively by computed tomographic angiography and MRI and also using invasive imaging. The detection of these remote plaques is not only feasible but also in natural history studies have been associated with clinical coronary events. Different systemic pharmacological treatments have been studied (mostly statins) with modest success and, therefore, newer approaches are being tested. Local treatment for such lesions is in its infancy and larger, prospective, and randomized trials are needed. This review will describe the pathological and imaging findings in culprit lesions of patients with acute coronary syndrome and the assessment of remote plaques. In addition, the pharmacological and local treatment options will be reviewed. PMID:24902974

Garcia-Garcia, Hector M; Jang, Ik-Kyung; Serruys, Patrick W; Kovacic, Jason C; Narula, Jagat; Fayad, Zahi A

2014-06-01

143

Uterine rupture following termination of pregnancy in a scarred uterus.  

PubMed

We present a series of two cases complicated by uterine rupture following termination of pregnancy (TOP) in the 1st and 2nd trimesters using misoprostol in women with caesarean section scar. Current literature and practise have also been reviewed on ruptured uterus in women with caesarean section scar undergoing TOP using misoprostol; the diagnosis of adherent placenta in the 1st and 2nd trimesters in women with previous caesarean uterine scar; and likely implications of a ruptured uterus. PMID:24456452

Bika, O; Huned, D; Jha, S; Selby, K

2014-02-01

144

Partial Rotator Cuff Ruptures  

Microsoft Academic Search

\\u000a Partial rotator cuff ruptures are not rare and occur mainly in the supraspinatus tendon and may extend to that of infraspinatus,\\u000a but rarely to the tendon of subscapularis. Isolated lesions in the tendons of infraspinatus, teres minor or subscapularis\\u000a are rare. Partial ruptures usually occur before the sixth decade of life and can be a cause of unexplained pain in

Antonio Cartucho

145

Raised Soluble P-Selectin Moderately Accelerates Atherosclerotic Plaque Progression  

PubMed Central

Soluble P-selectin (sP-selectin), a biomarker of inflammatory related pathologies including cardiovascular and peripheral vascular diseases, also has pro-atherosclerotic effects including the ability to increase leukocyte recruitment and modulate thrombotic responses in vivo. The current study explores its role in progressing atherosclerotic plaque disease. Apoe?/? mice placed on a high fat diet (HFD) were given daily injections of recombinant dimeric murine P-selectin (22.5 µg/kg/day) for 8 or 16 weeks. Saline or sE-selectin injections were used as negative controls. In order to assess the role of sP-selectin on atherothrombosis an experimental plaque remodelling murine model, with sm22?-hDTR Apoe?/? mice on a HFD in conjunction with delivery of diphtheria toxin to induce targeted vascular smooth muscle apoptosis, was used. These mice were similarly given daily injections of sP-selectin for 8 or 16 weeks. While plaque mass and aortic lipid content did not change with sP-selectin treatment in Apoe?/? or SM22?-hDTR Apoe?/? mice on HFD, increased plasma MCP-1 and a higher plaque CD45 content in Apoe?/? HFD mice was observed. As well, a significant shift towards a more unstable plaque phenotype in the SM22?-hDTR Apoe?/? HFD mice, with increased macrophage accumulation and lower collagen content, leading to a lower plaque stability index, was observed. These results demonstrate that chronically raised sP-selectin favours progression of an unstable atherosclerotic plaque phenotype.

Andrews, Karen L.; Aprico, Andrea; Harris, Emma; Irvine, Jennifer C.; Jefferis, Ann-maree; Fang, Lu; Kanellakis, Peter; Bobik, Alex; Chin-Dusting, Jaye P. F.

2014-01-01

146

Optical detection of structural changes in human carotid atherosclerotic plaque  

NASA Astrophysics Data System (ADS)

Background: Arterial bifurcations are commonly the sites of developing atherosclerotic plaque that lead to arterial occlusions and plaque rupture (myocardial infarctions and strokes). Laser induced fluorescence (LIF) spectroscopy provides an effective nondestructive method supplying spectral information on extracellular matrix (ECM) protein composition, specifically collagen and elastin. Purpose: To investigate regional differences in the ECM proteins -- collagen I, III and elastin in unstable plaque by analyzing data from laser-induced fluorescence spectroscopy of human carotid endarterectomy specimens. Methods: Gels of ECM protein extracts (elastin, collagen types I & III) were measured as reference spectra and internal thoracic artery segments (extra tissue from bypass surgery) were used as tissue controls. Arterial segments and the endarterectomy specimens (n=21) were cut into 5mm cross-sectional rings. Ten fluorescence spectra per sampling area were then recorded at 5 sites per ring with argon laser excitation (357nm) with a penetration depth of 200 ?m. Spectra were normalized to maximum intensity and analyzed using multiple regression analysis. Tissue rings were fixed in formalin (within 3 hours of surgery), sectioned and stained with H&E or Movat's Pentachrome for histological analysis. Spectroscopy data were correlated with immunohistology (staining for elastin, collagen types I, III and IV). Results: Quantitative fluorescence for the thoracic arteries revealed a dominant elastin component on the luminal side -- confirmed with immunohistology and known artery structure. Carotid endarterectomy specimens by comparison had a significant decrease in elastin signature and increased collagen type I and III. Arterial spectra were markedly different between the thoracic and carotid specimens. There was also a significant elevation (p<0.05) of collagen type I distal to the bifurcation compared to proximal tissue in the carotid specimens. Conclusion: Fluorescence spectroscopy is an effective method for evaluating ECM (collagen and elastin) associated with vascular remodeling despite the considerable variability in the plaque structure. Consistent regional differences were detected in the carotid specimens.

Korol, R. M.; Canham, P. B.; Finlay, H. M.; Hammond, R. R.; Quantz, M.; Ferguson, G. G.; Liu, L. Y.; Lucas, A. R.

2005-08-01

147

In vivo Raman spectral pathology of human atherosclerosis and vulnerable plaque  

NASA Astrophysics Data System (ADS)

The rupture of vulnerable atherosclerotic plaque accounts for the majority of clinically significant acute cardiovascular events. Because stability of these culprit lesions is directly related to chemical and morphological composition, Raman spectroscopy may be a useful technique for their study. Recent developments in optical fiber probe technology have allowed for the real-time in vivo Raman spectroscopic characterization of human atherosclerotic plaque demonstrated in this work. We spectroscopically examine 74 sites during carotid endarterectomy and femoral artery bypass surgeries. Of these, 34 are surgically biopsied and examined histologically. Excellent signal-to-noise ratio spectra are obtained in only 1 s and fit with an established model, demonstrating accurate tissue characterization. We also report the first evidence that Raman spectroscopy has the potential to identify vulnerable plaque, achieving a sensitivity and specificity of 79 and 85%, respectively. These initial findings indicate that Raman spectroscopy has the potential to be a clinically relevant diagnostic tool for studying cardiovascular disease.

Motz, Jason T.; Fitzmaurice, Maryann; Miller, Arnold; Gandhi, Saumil J.; Haka, Abigail S.; Galindo, Luis; Dasari, Ramachandra R.; Kramer, John R., Jr.; Feld, Michael S.

2006-03-01

148

Human coronary plaque wall thickness correlated positively with flow shear stress and negatively with plaque wall stress: an IVUS-based fluid-structure interaction multi-patient study  

PubMed Central

Background Atherosclerotic plaque progression and rupture are believed to be associated with mechanical stress conditions. In this paper, patient-specific in vivo intravascular ultrasound (IVUS) coronary plaque image data were used to construct computational models with fluid-structure interaction (FSI) and cyclic bending to investigate correlations between plaque wall thickness and both flow shear stress and plaque wall stress conditions. Methods IVUS data were acquired from 10 patients after voluntary informed consent. The X-ray angiogram was obtained prior to the pullback of the IVUS catheter to determine the location of the coronary artery stenosis, vessel curvature and cardiac motion. Cyclic bending was specified in the model representing the effect by heart contraction. 3D anisotropic FSI models were constructed and solved to obtain flow shear stress (FSS) and plaque wall stress (PWS) values. FSS and PWS values were obtained for statistical analysis. Correlations with p?plaque wall stress. The mean Pearson correlation r-value was -0.530?±?0.210. Conclusion Our results showed that plaque vessel wall thickness correlated positively with FSS and negatively with PWS. The patient-specific IVUS-based modeling approach has the potential to be used to investigate and identify possible mechanisms governing plaque progression and rupture and assist in diagnosis and intervention procedures. This represents a new direction of research. Further investigations using more patient follow-up data are warranted.

2014-01-01

149

MRI Plaque Imaging Detects Carotid Plaques with a High Risk for Future Cerebrovascular Events in Asymptomatic Patients  

PubMed Central

Purpose The aim of this study was to investigate prospectively whether MRI plaque imaging can identify patients with asymptomatic carotid artery stenosis who have an increased risk for future cerebral events. MRI plaque imaging allows categorization of carotid stenosis into different lesion types (I–VIII). Within these lesion types, lesion types IV–V and VI are regarded as rupture-prone plaques, whereas the other lesion types represent stable ones. Methods Eighty-three consecutive patients (45 male (54.2%); age 54–88 years (mean 73.2 years)) presenting with an asymptomatic carotid stenosis of 50–99% according to ECST-criteria were recruited. Patients were imaged with a 1.5-T scanner. T1-, T2-, time-of-flight-, and proton-density weighted studies were performed. The carotid plaques were classified as lesion type I–VIII. Clinical endpoints were ischemic stroke, TIA or amaurosis fugax. Survival analysis and log rank test were used to ascertain statistical significance. Results Six out of 83 patients (7.2%) were excluded: 4 patients had insufficient MR image quality; 1 patient was lost-to-follow-up; 1 patient died shortly after the baseline MRI plaque imaging. The following results were obtained by analyzing the remaining 77 patients. The mean time of follow-up was 41.1 months. During follow-up, n?=?9 (11.7%) ipsilateral ischemic cerebrovascular events occurred. Only patients presenting with the high-risk lesion types IV–V and VI developed an ipsilateral cerebrovascular event versus none of the patients presenting with the stable lesion types III, VII, and VIII (n?=?9 (11.7%) vs. n?=?0 (0%) during follow-up). Event-free survival was higher among patients with the MRI-defined stable lesion types (III, VII, and VIII) than in patients with the high-risk lesion types (IV–V and VI) (log rank test P<0.0001). Conclusions MRI plaque imaging has the potential to identify patients with asymptomatic carotid stenosis who are particularly at risk of developing future cerebral ischemia. MRI could improve selection criteria for invasive therapy in the future.

Esposito-Bauer, Lorena; Saam, Tobias; Ghodrati, Iman; Pelisek, Jaroslav; Heider, Peter; Bauer, Matthias; Wolf, Petra; Bockelbrink, Angelina; Feurer, Regina; Sepp, Dominik; Winkler, Claudia; Zepper, Peter; Boeckh-Behrens, Tobias; Riemenschneider, Matthias; Hemmer, Bernhard; Poppert, Holger

2013-01-01

150

Laser-induced fluorescence of atherosclerotic plaques  

NASA Astrophysics Data System (ADS)

In vitro laser-induced fluorescence (LIF) spectra and lifetimes of normal and atherosclerotic tissues are reported. The experimental arrangement conceived to measure LIF contained a 700 ps nitrogen pulsed laser (337.1 nm) and two quartz optical fibers to induce and respectively collect the fluorescence of normal and diseased samples. With UV laser excitation we found proeminent differences both in spectral and temporal range between normal artery and atherosclerotic plaques which was standard pathological classified in five types such as: normal artery, fibrous plaque, atherosclerotic plaque, calcified plaque and ulcerated plaque. As for statistics, the total number of measurements performed on each of the five mentioned types of tissues was 25.

Moise, N.; Pascu, Mihai L.; Carp, C.; Volvoreanu, C.

1998-07-01

151

Incomplete Cesarean Scar Rupture  

PubMed Central

Background Uterine rupture at the site of a previous cesarean scar is an uncommon but catastrophic complication of pregnancy, which is associated with significant maternal and fetal morbidity and mortality. Case Presentation A 30-year old woman at 24th week of gestation and complaint of pain, contractions and spotting was admitted in Royan Institute in Tehran, Iran. She had a past medical history of an EP and a cesarean section delivery, respectively 4 and 2 years before hospitalization. Herniation of an amniotic membrane into the maternal bladder was found on ultrasound examination. Conclusion Risk factors of cesarean scar rupture should be considered in women undergoing subsequent pregnancies as they need extra care. Ultrasonography can be used to evaluate women with previous cesarean section to assess the risks of scar rupture during subsequent pregnancies.

Ahmadi, Firoozeh; Siahbazi, Shiva; Akhbari, Farnaz

2013-01-01

152

Differential association of visceral adipose tissue with coronary plaque characteristics in patients with and without diabetes mellitus  

PubMed Central

Background Excess visceral adipose tissue (VAT) is closely associated with the presence of coronary artery plaques that are vulnerable to rupture. Patients with diabetes mellitus (DM) have more VAT than patients without DM, but the extent to which VAT contributes to the characteristics of coronary plaques before and after the development of DM is not fully understood. Methods We retrospectively evaluated 456 patients (60% male, age 64?±?16 years) who were suspected to have cardiovascular disease and underwent 64-slice computed tomography angiography (CTA). Seventy-one (16%) patients had vulnerable plaques (CT density??1.05, and adjacent spotty areas of calcification). Results Patients were divided into tertiles according to the VAT area. There were stepwise increases in noncalcified and vulnerable plaques with increasing tertiles of VAT area in patients without DM, but not in patients with DM. Multivariate analysis showed that a larger VAT area was significantly associated with a higher risk of vulnerable plaque in patients without DM (odds ratio 3.17, 95% confidence interval 1.08–9.31, p?=?0.04), but not in patients with DM. Conclusions The VAT area is associated with the characteristics of coronary plaques on CTA in patients without DM, but not in patients with DM. VAT may be a significant cardiometabolic risk factor that is associated with plaque vulnerability before the development of DM. CTA findings may help to improve risk stratification in such patients.

2014-01-01

153

[Indirect traumatic diaphragmatic rupture].  

PubMed

Between 1969 and 1988 51 polytraumatized patients were treated for rupture of the diaphragm due to blunt trauma. In 39 cases the lesion was in the left hemidiaphragm, in 11 cases on the right side and in one case on both sides. Clinical investigation and posterior-anterior chest X-ray were the most important diagnostic procedures. A high percentage of ruptures was only detected intraoperatively during acute laparotomy/thoracotomy. Early or delayed surgery had no influence on the survival of patients. The prognosis depends on the severity of associated injuries, which are the main causes of death in these patients. PMID:1858376

Holzberger, P; Königsrainer, A; Tauscher, T; Müller, L; Thöni, H

1991-01-01

154

Splenic abscess rupture postappendicectomy  

PubMed Central

The authors present a case of splenic abscess rupture postappendicectomy. Splenic abscess is rare with a reported incidence of 0.05%–0.7%. It is extremely unusual for a splenic abscess to result in splenic rupture. Contiguous spread, in this case from postappendix perforation, can cause splenic abscess formation. Postemergency splenectomy, the patient required admission to intensive therapy unit for 5 days but made a good postoperative recovery. This case is important to report as this is a rare postoperative complication of generalised peritonitis and this case highlights that astute diagnosis and management of the deteriorating surgical patient and rapid mobilisation of theatre are lifesaving.

Patel, Roshani; Pai, Aakash; Al-Shoek, Ihsan; Evans, Charles; Gordon, Andrew

2012-01-01

155

[Non plaque-related gingivitis].  

PubMed

Gingivitis is a symptom revealing an underlying pathology, mostly due to a bacterial accumulation. This explains why for dentists gingivitis is often synonymous of a plaque-related gingivitis. This is a dangerous simplification since it can be due to very different etiologies, which evidently imply very different treatments. This paper illustrates the most frequent causes, not only encountered by the periodontologist, but also by the general practitioner, such as erosive lichen planus, herpes, Candida and radiotherapy. PMID:12494701

van Steenberghe, D; Quirynen, M

2002-11-01

156

The relevance of Randall's plaques  

PubMed Central

The pathophysiology of nephrolithiasis is not fully understood. The pioneering work of Alexander Randall in the 1940s sought to clarify our understanding of stone formation. This review traces the inception of the theory of Randall's plaques and the refinement of the hypothesis in the early days of kidney stone research. It then reviews the contemporary findings utilizing sophisticated investigative techniques that shed additional light on the pathophysiology and redefine the seminal findings of Dr. Randall that were made 70 years ago.

Strakosha, Ruth; Monga, Manoj; Wong, Michael Y. C.

2014-01-01

157

Bacterial sex in dental plaque.  

PubMed

Genes are transferred between bacteria in dental plaque by transduction, conjugation, and transformation. Membrane vesicles can also provide a mechanism for horizontal gene transfer. DNA transfer is considered bacterial sex, but the transfer is not parallel to processes that we associate with sex in higher organisms. Several examples of bacterial gene transfer in the oral cavity are given in this review. How frequently this occurs in dental plaque is not clear, but evidence suggests that it affects a number of the major genera present. It has been estimated that new sequences in genomes established through horizontal gene transfer can constitute up to 30% of bacterial genomes. Gene transfer can be both inter- and intrageneric, and it can also affect transient organisms. The transferred DNA can be integrated or recombined in the recipient's chromosome or remain as an extrachromosomal inheritable element. This can make dental plaque a reservoir for antimicrobial resistance genes. The ability to transfer DNA is important for bacteria, making them better adapted to the harsh environment of the human mouth, and promoting their survival, virulence, and pathogenicity. PMID:23741559

Olsen, Ingar; Tribble, Gena D; Fiehn, Nils-Erik; Wang, Bing-Yan

2013-01-01

158

Intravascular photoacoustic imaging of atherosclerotic plaques: ex-vivo study using a rabbit model of atherosclerosis  

NASA Astrophysics Data System (ADS)

Diagnosis and treatment of atherosclerosis necessitates the detection and differentiation of rupture prone plaques. In principle, intravascular photoacoustic (IVPA) imaging has the ability to simultaneously visualize the structure and composition of atherosclerotic plaques by utilizing the difference in optical absorption. Extensive studies are required to validate the utility of IVPA imaging in detecting vulnerable plaques and address issues associated with the clinical implementation of the technique. In this work, we performed ex vivo imaging studies using a rabbit model of atherosclerosis. The intravascular photoacoustic (IVPA) and ultrasound (IVUS) images of the normal aorta and aorta with plaque were obtained and compared with histological slices of the tissue. The results indicate that IVPA imaging is capable of detecting plaques and showed potential in determining the composition. Furthermore, we initially addressed several aspects of clinical implementation of the IVPA imaging. Specifically, the configuration of combined IVPA and IVUS catheter was investigated and the effect of the optical absorption of the luminal blood on the IVPA image quality was evaluated. Overall, this study suggests that IVPA imaging can become a unique and important clinical tool.

Sethuraman, S.; Mallidi, S.; Aglyamov, S. R.; Amirian, J. H.; Litovsky, S.; Smalling, R. W.; Emelianov, S. Y.

2007-03-01

159

Anterior Cruciate Ligament Rupture and Osteoarthritis Progression  

PubMed Central

Anterior Cruciate Ligament (ACL) rupture is a common sporting injury that frequently affects young, athletic patients. Apart from the functional problems of instability, patients with ACL deficient knees also develop osteoarthritis. Although this is frequently cited as an indication for ACL reconstruction, the relationship between ACL rupture, reconstruction and the instigation and progression of articular cartilage degenerative change is controversial. The purpose of this paper is to review the published literature with regards ACL rupture and the multifactorial causes for osteoarthritis progression, and whether or not this is slowed or stopped by ACL reconstruction. There is no evidence in the published literature to support the view that ACL reconstruction prevents osteoarthritis, although it may prevent further meniscal damage. It must be recognised that this conclusion is based on the current literature which has substantial methodological limitations.

Wong, James Min-Leong; Khan, Tanvir; Jayadev, Chethan S; Khan, Wasim; Johnstone, David

2012-01-01

160

Premature Rupture of Membranes  

PubMed Central

The management of premature rupture of the amniotic membranes before 37 weeks gestation remains controversial. The authors of this article outline the risks involved for the fetus, define the various terms related, and discuss the antepartum and intrapartum management of such an event and offer a protocol that they have developed.

Akierman, Albert; Iwanicki, Stanislaw

1988-01-01

161

Plaque characteristics and arterial remodeling in coronary and peripheral arterial systems  

PubMed Central

Background Few studies have examined plaque characteristics among multiple arterial beds in vivo. The purpose of this study was to compare the plaque morphology and arterial remodeling between coronary and peripheral arteries using gray-scale and radiofrequency intravascular ultrasound (IVUS) at clinical presentation. Methods and Results IVUS imaging was performed in 68 patients with coronary and 93 with peripheral artery lesions (29 carotid, 50 renal, and 14 iliac arteries). Plaques were classified as fibroatheroma (VH-FA) (further subclassified as thin-capped [VH-TCFA] and thick-capped [VH-ThCFA]), fibrocalcific plaque (VH-FC) and pathological intimal thickening (VH-PIT). Plaque rupture (13% of coronary, 7% of carotid, 6% of renal, and 7% of iliac arteries; P=NS) and VHTCFA (37% of coronary, 24% of carotid, 16% of renal, and 7% of iliac arteries; p=0.02) were observed in all arteries. Compared with coronary arteries, VH-FA was less frequently observed in renal (p<0.001) and iliac arteries (p<0.006). Lesions with positive remodeling demonstrated more characteristics of VH-FA in coronary (84% vs. 25%, p<0.001), carotid (72% vs. 20%, p=0.001), and renal arteries (42% vs. 4%, p=0.001) compared with those with intermediate/negative remodeling. There was positive relationship between RI and percent necrotic area in all four arteries. Conclusions Atherosclerotic plaque phenotypes were heterogeneous among four different arteries; renal and iliac arteries had more stable phenotypes compared with coronary artery. In contrast, the associations of remodeling pattern with plaque phenotype and composition were similar among the various arterial beds.

Matsuo, Yoshiki; Takumi, Takuro; Mathew, Verghese; Chung, Woo-Young; Barsness, Gregory W.; Rihal, Charanjit S.; Gulati, Rajiv; McCue, Eric T.; Holmes, David R; Eeckhout, Eric; Lennon, Ryan J.; Lerman, Lilach O.; Lerman, Amir

2012-01-01

162

Safrole-2',3'-oxide induces atherosclerotic plaque vulnerability in apolipoprotein E-knockout mice.  

PubMed

Safrole-2',3'-oxide (SFO) is the major electrophilic metabolite of safrole (4-allyl-1, 2-methylenedioxybenzene), a natural plant constituent found in essential oils of numerous edible herbs and spices and in food containing these herbs, such as pesto sauce, cola beverages and bologna sausages. The effects of SFO in mammalian systems, especially the cardiovascular system, are little known. Disruption of vulnerable atherosclerotic plaques in atherosclerosis, a chronic inflammatory disease, is the main cause of cardiovascular events. In this study, we investigated SFO-induced atherosclerotic plaque vulnerability (possibility of rupture) in apolipoprotein E-knockout (apoE(-/-)) mice. Lipid area in vessel wall reached 59.8% in high dose SFO (SFO-HD) treated group, which is only 31.2% in control group. SFO treatment changed the lesion composition to an unstable phenotype, increased the number of apoptotic cells in plaque and the endothelium in plaques was damaged after SFO treatment. Furthermore, compared with control groups, the plaque endothelium level of p75(NTR) was 3-fold increased and the liver level of p75(NTR) was 17.4-fold increased by SFO-HD. Meanwhile, the serum level of KC (a functional homolog of IL-8 and the main proinflammatory alpha chemokine in mice) in apoE(-/-) mice was up to 357pg/ml in SFO-HD treated group. Thus, SFO contributes to the instability of atherosclerotic plaque in apoE(-/-) mice through activating p75(NTR) and IL-8 and cell apoptosis in plaque. PMID:23270965

Su, Le; Zhang, Haiyan; Zhao, Jing; Zhang, Shangli; Zhang, Yun; Zhao, Baoxiang; Miao, Junying

2013-02-27

163

Some Observations Regarding the Statistical Determination of Stress Rupture Minimums.  

National Technical Information Service (NTIS)

Observations concerning the statistical evaluation of creep data are presented. Methods currently employed in the determination of stress rupture minimum values can result in conflicting and necessarily invalid results. Anomalous behavior is principally a...

P. P. Pizzo

1971-01-01

164

Kyrieleis plaques in cytomegalovirus retinitis  

Microsoft Academic Search

Purpose  The purpose of this study is to report a case of Kyrieleis plaques (segmental retinal periarteritis) associated with cytomegalovirus\\u000a (CMV) retinitis.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A 47-year-old female with recently diagnosed human immunodeficiency virus and a CD4 count of 55 cells\\/µl presented with decreased\\u000a vision and floaters in her left eye. Ophthalmic examination revealed an advancing border of white granular CMV retinitis extending\\u000a into

Amar Patel; Matthew Pomykala; Krishna Mukkamala; Ronald C. Gentile

165

Patient-Specific Carotid Plaque Progression Simulation Using 3D Meshless Generalized Finite Difference Models with Fluid-Structure Interactions Based on Serial In Vivo MRI Data  

PubMed Central

Previously, we introduced a computational procedure based on three-dimensional meshless generalized finite difference (MGFD) method and serial magnetic resonance imaging (MRI) data to quantify patient-specific carotid atherosclerotic plaque growth functions and simulate plaque progression. Structure-only models were used in our previous report. In this paper, fluid-stricture interaction (FSI) was added to improve on prediction accuracy. One participating patient was scanned three times (T1, T2, and T3, at intervals of about 18 months) to obtain plaque progression data. Blood flow was assumed to laminar, Newtonian, viscous and incompressible. The Navier-Stokes equations with arbitrary Lagrangian-Eulerian (ALE) formulation were used as the governing equations. Plaque material was assumed to be uniform, homogeneous, isotropic, linear, and nearly incompressible. The linear elastic model was used. The 3D FSI plaque model was discretized and solved using a meshless generalized finite difference (GFD) method. Growth functions with a) morphology alone; b) morphology and plaque wall stress (PWS); morphology and flow shear stress (FSS), and d) morphology, PWS and FSS were introduced to predict future plaque growth based on previous time point data. Starting from the T2 plaque geometry, plaque progression was simulated by solving the FSI model and adjusting plaque geometry using plaque growth functions iteratively until T3 is reached. Numerically simulated plaque progression agreed very well with the target T3 plaque geometry with errors ranging from 8.62%, 7.22%, 5.77% and 4.39%, with the growth function including morphology, plaque wall stress and flow shear stress terms giving the best predictions. Adding flow shear stress term to the growth function improved the prediction error from 7.22% to 4.39%, a 40% improvement. We believe this is the first time 3D plaque progression FSI simulation based on multi-year patient-tracking data was reported. Serial MRI-based progression simulation adds time dimension to plaque vulnerability assessment and will improve prediction accuracy for potential plaque rupture risk.

Yang, Chun; Tang, Dalin; Atluri, Satya

2011-01-01

166

Inhibition of a4 Integrin and ICAM-1 Markedly Attenuate Macrophage Homing to Atherosclerotic Plaques in ApoE-Deficient Mice  

Microsoft Academic Search

Background—Monocytes\\/macrophages play a central role in many stages of development of atherosclerotic plaques, including the conversion to an unstable morphology with rupture and fissuring. A better understanding of the mechanism of attachment of monocytes to activated endothelial cells would prove useful in developing strategies aimed at blocking this initial step. Here we describe a novel in vivo model that directly

Shilpesh S. Patel; Ram Thiagarajan; James T. Willerson; Edward T. H. Yeh

167

Rupture Dynamics of Subduction Megathrust Earthquakes  

NASA Astrophysics Data System (ADS)

Motivated by recent megathrust earthquakes, we have begun a systematic investigation of the influence of depth-dependent frictional properties, slab geometry and fault dip angle, and strength of the accretionary prism on rupture propagation. A particular focus is on identifying the conditions under which rupture reaches the trench, as this maximizes seafloor uplift and the resulting tsunami. We tackle this problem with fully dynamic two-dimensional simulations, using a high order finite difference method with coordinate transforms to handle the complex geometry. The fault obeys rate-and-state friction and the off-fault material response includes continuum Drucker-Prager plasticity that is activated at sufficiently high stress levels. We directly account for variations in material properties across curved crust and mantle layers, since waveguide effects are an essential part of the rupture process in this geometry. For shallowly dipping faults, free surface effects are particularly pronounced. Wave reflections from the seafloor transiently decrease normal stress on the fault surface, thereby reducing its strength. We have found that this effect can be sufficient to permit rupture all the way to the trench axis, even if the upper portion of the fault is velocity-strengthening and thus incapable of unstable frictional sliding. Additionally, current thinking appears to assume that this upper part of the fault will rupture only if it is locked during the interseismic period, thereby resulting in strain accumulation in the surrounding material. Our preliminary models instead suggest that this part of the fault can still slip coseismically, even with negligible prestress. We are now exploring how robust this tentative conclusion is, as it would have significant implications for predictions of rupture extent based on observational estimates of the extent of fault locking during the interseismic period.

Dunham, E. M.; Kozdon, J. E.

2011-12-01

168

Distal biceps tendon rupture  

Microsoft Academic Search

The authors report a rupture of the distal tendon of biceps brachii in a 42-year-old athlete. Magnetic resonance imaging confirmed the injury. Early surgical repair was performed by reinsertion of the tendon on the radial tuberosity according to modified Boyd-Anderson technique. Indomethacin was administered prophylactically. No complications were noted. At the latest follow-up, the patient had full elbow range of

Olga D. Savvidou; Panayiotis J. Papagelopoulos; Andreas F. Mavrogenis; Antonios A. Partsinevelos; Evangelos J. Karadimas; Demetrios S. Korres

2004-01-01

169

Amyloid plaques in PSAPP mice bind less metal than plaques in human Alzheimer's disease  

Microsoft Academic Search

Amyloid beta (A?) is the primary component of Alzheimer's disease (AD) plaques, a key pathological feature of the disease. Metal ions of zinc (Zn), copper (Cu), iron (Fe), and calcium (Ca) are elevated in human amyloid plaques and are thought to be involved in neurodegeneration. Transgenic mouse models of AD also exhibit amyloid plaques, but fail to exhibit the high

Andreana C. Leskovjan; Antonio Lanzirotti; Lisa M. Miller

2009-01-01

170

Plaquing procedure for infectious hematopoietic necrosis virus  

USGS Publications Warehouse

A single overlay plaque assay was designed and evaluated for infectious hematopoietic necrosis virus. Epithelioma papillosum carpio cells were grown in normal atmosphere with tris(hydroxymethyl)aminomethane- or HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered media. Plaques were larger and formed more quickly on 1- to 3-day-old cell monolayers than on older monolayers. Cell culture medium with a 10% addition of fetal calf serum (MEM 10) or without serum (MEM 0) were the most efficient virus diluents. Dilution with phosphate-buffered saline, saline, normal broth, or deionized water reduced plaque numbers. Variations in the pH (7.0 to 8.0) of a MEM 0 diluent did not affect plaque numbers. Increasing the volume of viral inoculum above 0.15 ml (15- by 60-mm plate) decreased plaquing efficiency. Significantly more plaques occurred under gum tragacanth and methylcellulose than under agar or agarose overlays. Varying the pH (6.8 to 7.4) of methylcellulose overlays did not significantly change plaque numbers. More plaques formed under the thicker overlays of both methylcellulose and gum tragacanth. Tris(hydroxymethyl)aminomethane and HEPES performed equally well, buffering either medium or overlay. Plaque numbers were reduced when cells were rinsed after virus adsorption or less than 1 h was allowed for adsorption. Variation in adsorption time between 60 and 180 min did not change plaque numbers. The mean plaque formation time was 7 days at 16 degrees C. The viral dose response was linear when the standardized assay was used.

Burke, J. A.; Mulcahy, D.

1980-01-01

171

The Psoriasis Area and Severity Index Is the Adequate Criterion to Define Severity in Chronic Plaque-Type Psoriasis  

Microsoft Academic Search

Background: Chronic plaque-type psoriasis is a major dermatosis, but a significant question is still unanswered: What defines severity in chronic plaque-type psoriasis? While objective assessments like the Psoriasis Area and Severity Index (PASI) have frequently been used in clinical trials, quality of life (QOL) questionnaires are currently becoming more and more popular. Objective: This article summarizes the most important objective

Jochen Schmitt; Gottfried Wozel

2005-01-01

172

Fluoride bioavailability in saliva and plaque  

PubMed Central

Background Different fluoride formulations may have different effects on caries prevention. It was the aim of this clinical study to assess the fluoride content, provided by NaF compared to amine fluoride, in saliva and plaque. Methods Eight trained volunteers brushed their teeth in the morning for 3 minutes with either NaF or amine fluoride, and saliva and 3-day-plaque-regrowth was collected at 5 time intervals during 6 hours after tooth brushing. The amount of collected saliva and plaque was measured, and the fluoride content was analysed using a fluoride sensitive electrode. All subjects repeated all study cycles 5 times, and 3 cycles per subject underwent statistical analysis using the Wilcoxon-Mann-Whitney test. Results Immediately after brushing the fluoride concentration in saliva increased rapidly and dropped to the baseline level after 360 minutes. No difference was found between NaF and amine fluoride. All plaque fluoride levels were elevated after 30 minutes until 120 minutes after tooth brushing, and decreasing after 360 minutes to baseline. According to the highly individual profile of fluoride in saliva and plaque, both levels of bioavailability correlated for the first 30 minutes, and the fluoride content of saliva and plaque was back to baseline after 6 hours. Conclusions Fluoride levels in saliva and plaque are interindividually highly variable. However, no significant difference in bioavailability between NaF and amine fluoride, in saliva, or in plaque was found.

2012-01-01

173

Imaging of High-Risk Plaque  

Microsoft Academic Search

‘High-risk’ or ‘vulnerable’ plaques in the coronary arteries have characteristics that make them more prone to disruption and subsequent thrombosis – the mechanisms of most acute coronary syndromes (ACS). There are a number of imaging modalities that are capable of visualizing these features. This article discusses invasive modalities for identifying ‘high-risk’ plaque such as intravascular ultrasound, coronary angioscopy, optical coherence

Dmitry Nemirovsky

2003-01-01

174

The explosive growth of small voids in vulnerable cap rupture; cavitation and interfacial debonding  

PubMed Central

While it is generally accepted that ruptures in fibrous cap atheromas cause most acute coronary deaths, and that plaque rupture occurs in the fibrous cap at the location where the tissue stress exceeds a certain critical peak circumferential stress, the exact mechanism of rupture initiation remains unclear. We recently reported the presence of multiple microcalcifications (?Calcs) < 50?m diameter embedded within the fibrous cap, ?Calcs that could greatly increase cap instability by introducing up to a 5-fold increase in local tissue stress. Here, we explore the hypothesis that, aside from cap thickness, ?Calc size and interparticle spacing are principal determinants of cap rupture risk. Also, we propose that cap rupture is initiated near the poles of the ?Calcs due to the presence of tiny voids that explosively grow at a critical tissue stress and then propagate across the fibrous cap. We develop a theoretical model based on classic studies in polymeric materials by Gent (1980), which indicates that cavitation as opposed to interfacial debonding is the more likely mechanism for cap rupture produced by ?Calcs < 65?m diameter. This analysis suggests that there is a critical ?Calc size range, from 5?m to 65?m, in which cavitation should be prevalent. This hypothesis for cap rupture is strongly supported by our latest ?CT studies in which we have observed trapped voids in the vicinity of ?Calcs within fibrous caps in human coronaries.

Maldonado, Natalia; Kelly-Arnold, Adreanne; Cardoso, Luis; Weinbaum, Sheldon

2013-01-01

175

Uptake of 68gallium in atherosclerotic plaques in LDLR-/-ApoB100/100 mice  

PubMed Central

Background Atherosclerosis is a chronic inflammatory disease of artery wall characterized by infiltration of monocytes into subendothelial space and their differentiation into macrophages. Since rupture-prone plaques commonly contain high amounts of activated macrophages, imaging of the macrophage content may provide a useful tool for the evaluation of plaque vulnerability. The purpose of this study was to explore the uptake of 68gallium (68Ga) in atherosclerotic plaques in mice. Methods Uptake of ionic 68Ga was investigated in atherosclerotic LDLR-/-ApoB100/100 and C57BL/6N control mice at 3 h after injection. The ex vivo biodistribution of the 68Ga was assessed and autoradiography of aortic cryosections was defined. In vivo imaging of 68Ga was performed using a small animal positron emission tomography PET/CT scanner. Results Our results revealed that the uptake of 68Ga-radioactivity was higher in atherosclerotic plaques than in healthy vessel wall (ratio 1.8 ± 0.2, p = 0.0002) and adventitia (ratio 1.3 ± 0.2, p = 0.0011). The autoradiography signal co-localized with macrophages prominently as demonstrated by Mac-3 staining. In both mice strains, the highest level of radioactivity was found in the blood. Conclusions We observed a moderate but significantly elevated 68Ga-radioactivity uptake in the aortic plaques of atherosclerotic mice, especially at the sites rich in macrophages. While the uptake of 68Ga was promising in this animal model, the slow blood clearance may limit the usability of 68Ga as a PET tracer for clinical imaging of atherosclerotic plaques.

2011-01-01

176

Nox4 NADPH oxidase contributes to smooth muscle cell phenotypes associated with unstable atherosclerotic plaques  

PubMed Central

Plaque instability associated with acute coronary syndromes results in part from apoptosis and senescence of cells within the atherosclerotic (AS) lesion. Increased cellular oxidative stress has been proposed to contribute to plaque progression and changes in composition, leading to plaque instability. Our objective was to examine the role of NADPH oxidase in smooth muscle cell (SMC) phenotypes associated with an unstable plaque. Aortae were isolated from pre-lesion (8 weeks of age) and post-lesion (35 weeks of age) hypercholesterolemic mice (ApoE-/-/LDLR-/-, AS), and age-matched normal C57BL/6J mice. We observed an age-dependent increase in reactive oxygen species (ROS) in aorta from AS mice, with evidence for elevated ROS prior to lesion development. Whereas macrophage infiltration was restricted to the lesion, oxidized lipids extended beyond the plaque and into the vessel wall. Consistent with these findings, we observed dynamic changes in the expression of NADPH oxidases in AS vessels. Specifically, Nox1 expression was increased early and decreased with lesion progression, while induction of Nox4 was a late event. Nox2 and p22phox were elevated throughout lesion development. Similar to observations in aortae, SMCs isolated from the lesion of AS aortae had decreased Nox1 and increased Nox4 levels as compared to SMCs from normal mice. AS SMCs demonstrated increased generation of ROS, cell cycle arrest, evidence of senescence, and increased susceptibility to apoptosis. Overexpression of Nox4 in normal SMCs recapitulated the phenotypes of the AS SMCs. We conclude that increased expression of Nox4 in AS may drive SMC phenotypes that lead to the plaque instability and rupture responsible for myocardial infarction and stroke.

Xu, Shaoping; Chamseddine, Ali H.; Carrell, Samuel; Miller, Francis J.

2014-01-01

177

Receptor-targeted iron oxide nanoparticles for molecular MR imaging of inflamed atherosclerotic plaques.  

PubMed

In a number of literature reports iron oxide nanoparticles have been investigated for use in imaging atherosclerotic plaques and found to accumulate in plaques via uptake by macrophages, which are critical in the process of atheroma initiation, propagation, and rupture. However, the uptake of these agents is non-specific; thus the labeling efficiency for plaques in vivo is not ideal. We have developed targeted agents to improve the efficiency for labeling macrophage-laden plaques. These probes are based on iron oxide nanoparticles coated with dextran sulfate, a ligand of macrophage scavenger receptor type A (SR-A). We have sulfated dextran-coated iron oxide nanoparticles (DIO) with sulfur trioxide, thereby targeting our nanoparticle imaging agents to SR-A. The sulfated DIO (SDIO) remained mono-dispersed and had an average hydrodynamic diameter of 62 nm, an r(1) relaxivity of 18.1 mM(-1) s(-1), and an r(2) relaxivity of 95.8 mM(-1) s(-1) (37 °C, 1.4 T). Cell studies confirmed that these nanoparticles were nontoxic and specifically targeted to macrophages. In vivo MRI after intravenous injection of the contrast agent into an atherosclerotic mouse injury model showed substantial signal loss on the injured carotid at 4 and 24 h post-injection of SDIO. No discernable signal decrease was seen at the control carotid and only mild signal loss was observed for the injured carotid post-injection of non-sulfated DIO, indicating preferential uptake of the SDIO particles at the site of atherosclerotic plaque. These results indicate that SDIO can facilitate MRI detection and diagnosis of vulnerable plaques in atherosclerosis. PMID:21742374

Tu, Chuqiao; Ng, Thomas S C; Sohi, Hargun K; Palko, Heather A; House, Adrian; Jacobs, Russell E; Louie, Angelique Y

2011-10-01

178

Effects of the direct lipoprotein-associated phospholipase A2 inhibitor darapladib on human coronary atherosclerotic plaque  

Microsoft Academic Search

Background - Lipoprotein-associated phospholipase A2 (Lp-PLA2) is expressed abundantly in the necrotic core of coronary lesions, and products of its enzymatic activity may contribute to inflammation and cell death, rendering plaque vulnerable to rupture. Methods and Results - This study compared the effects of 12 months of treatment with darapladib (an oral Lp-PLA2 inhibitor, 160 mg daily) or placebo on

Patrick W. Serruys; H. M. Garcia-Garcia; Pawel Buszman; Paul Erne; Stefan Verheye; Michael Aschermann; Henrikus Duckers; Oyvind Bleie; Dariusz Dudek; H. E. Bøtker; Clemens von Birgelen; Don D'Amico; Tammy Hutchinson; Andrew Zambanini; Frits Mastik; Es van G. A; Steen van der A. F. W; D. Geoffrey Vince; Peter Ganz; Christian W. Hamm; William Wijns; Andrew Zalewski

2008-01-01

179

Advanced Techniques for MRI of Atherosclerotic Plaque  

PubMed Central

This review examines the state of the art in vessel wall imaging by MRI with an emphasis on the biomechanical assessment of atherosclerotic plaque. Three areas of advanced techniques are discussed. First, alternative contrast mechanisms, including susceptibility, magnetization transfer, diffusion and perfusion, are presented in regards to how they facilitate accurate determination of plaque constituents underlying biomechanics. Second, imaging technologies, including hardware and sequences, are reviewed in regards to how they provide the resolution and SNR necessary for determining plaque structure. Finally, techniques for combining MRI data into an overall assessment of plaque biomechanical properties, including wall shear stress and internal plaque strain, are presented. The paper closes with a discussion of the extent to which these techniques have been applied to different arteries commonly targeted by vessel wall MRI.

Kerwin, William S.; Canton, Gador

2011-01-01

180

Osseous changes in meningioma en plaque.  

PubMed

Hyperostosis is the most common skull change associated with meningioma. Five hyperostosis cases of meningioma en plaque infiltrating the skull processed without previous decalcification of the bone tissue were investigated histologically and immunohistochemically with antibodies against somatostatin receptor 2A (SSR2A). Undecalcified bone biopsies embedded in methylmethacrylate and paraffin-embedded extraosseous tumor tissues were analyzed. All five cases were well-differentiated meningotheliomatous meningiomas en plaque according to the WHO classification of tumors and revealed areas of hyperosteoidosis. Furthermore, all five meningiomas en plaque presented strong positive reactions to antibodies against SSR2A in both the intraosseous and extraosseous tumor proliferates. In summary, similar morphological changes characterized by hyperosteoidosis were observed in a small cohort of meningioma en plaque associated with expression of SSR2A and reports in the literature of the histogenesis of hyperostosis in meningioma en plaque are discussed. PMID:21378343

Matschke, Jakob; Addo, Jasmine; Bernreuther, Christian; Zustin, Jozef

2011-02-01

181

Best approach for the repair of distal biceps tendon ruptures  

PubMed Central

The preferred treatment of distal biceps tendon ruptures is by operative repair. However, the best approach for repair (single vs double incision) is still subject of debate. Grewal and colleagues recently presented the results of a randomized clinical trial evaluating two different surgical approaches for the repair of distal biceps tendon ruptures. Despite the fact that this article currently presents the highest level of evidence for the surgical repair of distal biceps tendon ruptures, we have some comments on the study that might be interesting to discuss. We think that some of the results and conclusions presented in this study need to be interpreted in the light of these comments.

Kodde, Izaak F; van den Bekerom, Michel P J; Eygendaal, Denise

2013-01-01

182

Assessment of plaque composition by intravascular ultrasound and near-infrared spectroscopy.  

PubMed

Atherosclerosis is the main cause of coronary artery disease (CAD), which is today the leading cause of death worldwide and will continue to be the first in the world in 2030. Vulnerable coronary plaques are usually characterized by a high content of necrotic core, a thin inflamed fibrous cap (intense accumulation of macrophages) and scarce presence of smooth muscle cells. None of these characteristics can be estimated by coronary angiography, which on the contrary underestimates the magnitude of atherosclerotic burden, particularly in earlier stage disease when positive vascular remodeling may allow "normal" lumen caliber despite substantial vascular wall plaque. The recognition of the ubiquity of substantial but non-flow limiting lesions that may be at high risk for subsequent plaque rupture has resulted in a paradigm shift in thinking about the pathophysiology of CAD, with the focus no longer solely on the degree of arterial luminal narrowing. This growing need for more information about coronary atherosclerosis in order to identify patients and lesions at risk for complications during PCI and for future adverse cardiac events has been the primary impetus for the development of novel intracoronary imaging methods able to detect plaque composition, in particular presence of a necrotic core/lipid pool, such as intravascular ultrasound virtual histology and near-infrared spectroscopy. These imaging technologies and their clinical and clinical/research applications are discussed in detail. (Circ J 2014; 78: 1531-1539). PMID:24931516

Brugaletta, Salvatore; Sabaté, Manel

2014-06-25

183

Critical mechanical conditions around neovessels in carotid atherosclerotic plaque may promote intraplaque hemorrhage  

PubMed Central

Objective Intraplaque hemorrhage is an increasingly recognized contributor to plaque instability. Neovascularization of plaque is believed to facilitate the entry of inflammatory and red blood cells (RBC). Under physiological conditions, neovessels are subject to mechanical loading from the deformation of atherosclerotic plaque by blood pressure and flow. Local mechanical environments around neovessels and their relevant pathophysiologic significance have not yet been examined. Methods and results Four carotid plaque samples removed at endarcterectomy were collected for histopathological examination. Neovessels and other components were manually segmented to build numerical models for mechanical analysis. Each component was assumed to be non-linear isotropic, piecewise homogeneous and incompressible. The results indicated that local maximum principal stress and stretch and their variations during one cardiac cycle were greatest around neovessels. Neovessels surrounded by RBC underwent a much larger stretch during systole than those without RBCs present nearby (median [inter quartile range]; 1.089 [1.056, 1.131] vs. 1.034 [1.020, 1.067]; p < 0.0001) and much larger stress (5.3 kPa [3.4, 8.3] vs. 3.1 kPa [1.6, 5.5]; p < 0.0001) and stretch (0.0282 [0.0190, 0.0427] vs. 0.0087 [0.0045, 0.0185]; p < 0.0001) variations during the cardiac cycle. Conclusions Local critical mechanical conditions may lead to the rupture of neovessels resulting in the formation and expansion of intraplaque hemorrhage.

Teng, Zhongzhao; He, Jing; Degnan, Andrew J.; Chen, Shengyong; Sadat, Umar; Bahaei, Nasim Sheikh; Rudd, James H.F.; Gillard, Jonathan H.

2012-01-01

184

Blood vessel rupture by cavitation  

PubMed Central

Cavitation is thought to be one mechanism for vessel rupture during shock wave lithotripsy treatment. However, just how cavitation induces vessel rupture remains unknown. In this work, a high-speed photomicrography system was set up to directly observe the dynamics of bubbles inside blood vessels in ex vivo rat mesenteries. Vascular rupture correlating to observed bubble dynamics were examined by imaging bubble extravasation and dye leakage. The high-speed images show that bubble expansion can cause vessel distention, and bubble collapse can lead to vessel invagination. Liquid jets were also observed to form. Our results suggest that all three mechanisms, vessel distention, invagination and liquid jets, can contribute to vessel rupture.

Chen, Hong; Brayman, Andrew A.; Bailey, Michael R.

2011-01-01

185

Associations of reactive hyperemia index and intravascular ultrasound-assessed coronary plaque morphology in patients with coronary artery disease.  

PubMed

Although reactive hyperemia index (RHI) predicts future coronary events, associations with intravascular ultrasound (IVUS)-assessed coronary plaque structure have not been reported. This study therefore investigated associations between RHI and IVUS-assessed coronary plaques. In 362 patients RHI was measured by noninvasive peripheral arterial tonometry and coronary plaque components (fibrous, fibrofatty, necrotic core, and dense calcium) were identified by IVUS in 594 vessel segments of the left anterior descending, circumflex, and/or right coronary arteries. RHI values <1.67 were considered abnormal. Analysis of variance was used to detect independent associations between RHI and plaque composition. Patients with an abnormal RHI had greater plaque burden (41% vs 39% in patients with normal RHI, p = 0.047). Compared to patients with normal RHI, plaque of patients with abnormal RHI had more necrotic core (21% vs 17%, p <0.001) and dense calcium (19% vs 15%, p <0.001) and less fibrous (49% vs 54%, p <0.001) and fibrofatty (11% vs 14%, p = 0.002) tissue. After adjustment for age, gender, cardiovascular risk factors, and drug therapy, abnormal RHI remained significantly associated with fibrous (F ratio 14.79, p <0.001), fibrofatty (F ratio 5.66, p = 0.018), necrotic core (F ratio 14.47, p <0.001), and dense calcium (F ratio 10.80, p = 0.001) volumes. In conclusion, coronary artery plaques of patients with abnormal RHI had a larger proportion of necrotic core and dense calcium. The association of an abnormal RHI with a plaque structure that is more prone to rupture may explain why these patients exhibit a greater risk of coronary events. PMID:22440130

Schoenenberger, Andreas W; Urbanek, Nadja; Bergner, Michael; Toggweiler, Stefan; Resink, Thérèse J; Erne, Paul

2012-06-15

186

Anti-inflammatory strategies for plaque stabilization after acute coronary syndromes.  

PubMed

Despite dramatic advances in standard of care, the risk of recurrent myocardial infarction early after an acute coronary syndrome (ACS) remains high. This period of elevated risk after a cardiovascular event is associated with an acute inflammatory response. While post-ACS inflammation correlates with the risk for recurrent events and is likely to play a causal role in this period, the precise pathophysiologic mechanisms have been unclear. Recent studies have proposed that the cardiac event itself activates the sympathetic nervous system to directly mobilize hematopoietic stem cells to differentiate into inflammatory monocytes, acutely infiltrate plaque, and lead to recurrent plaque rupture. Here, we summarize the existing and emerging evidence implicating post-ACS activation of systemic inflammation in the progression of atherosclerosis, and identify possible targets for therapeutic intervention. We highlight experimental therapies and ongoing clinical studies that will validate these targets. PMID:23636864

Baruch, Amos; van Bruggen, Nicholas; Kim, Juyong Brian; Lehrer-Graiwer, Joshua E

2013-06-01

187

Plaque regression and progenitor cell mobilization with intensive lipid elimination regimen (PREMIER) trial design.  

PubMed

Progression of lipid rich necrotic core elements of atherosclerotic vulnerable plaque (VP) or its rupture leads to a majority of cardiovascular events. Endothelial progenitor cells (EPC) contribute to vascular healing and play a crucial role in repair following ischemic injury primarily by endothelialization of VP and neovascularization of ischemic myocardium. We present the rationale and design of the Plaque Regression and Progenitor Cell Mobilization with Intensive Lipid Elimination Regimen or the PREMIER Trial, which is designed to address the question for the very first time whether a highly intensive low-density lipoprotein (LDL)-lowering therapy with LDL-apheresis could lead to a more rapid and detectable reduction in coronary atheroma volume, along with a robust mobilization of EPC compared to standard statin therapy, in patients selected for percutaneous coronary intervention for an acute coronary syndrome. PMID:24123098

Banerjee, Subhash; Abu Fadel, Mazen; Sarode, Ravi; Terada, Lance; Moritz, Thomas; Luo, Ping; Hastings, Jeffrey; Brilakis, Emmanouil S; Reda, Domenic

2014-04-01

188

Predicting rupture arrests, rupture jumps and cascading earthquakes  

NASA Astrophysics Data System (ADS)

The devastation inflicted by recent earthquakes demonstrates the danger of under-predicting the size of earthquakes. Unfortunately, earthquakes may rupture fault-sections larger than previously observed, making it essential to develop predictive rupture models. We present numerical models based on earthquake physics and fault zone data, that determine whether a rupture on a segmented fault could cascade and grow into a devastating, multisegment earthquake. We demonstrate that weakened (damaged) fault zones and bi-material interfaces promote rupture propagation and greatly increase the risk of cascading ruptures and triggered seismicity. This result provides a feasible explanation for the outstanding observation of a very large (10 km) rupture jump documented in theMW7.8 2001 Kunlun, China earthquake. However, enhanced inter-seismic deformation and energy dissipation at fault tips suppress rupture propagation and may turn even small discontinuities into effective earthquake barriers. By assessing fault stability, identifying rupture barriers and foreseeing multisegment earthquakes, we provide a tool to improve earthquake prediction and hazard analysis.

Finzi, Y.; Langer, S.

2012-12-01

189

[Ruptured abdominal aortic aneurysms].  

PubMed

Eighty two aortic replacements of ruptured abdominal aortic aneurysms have been performed during the last 6 years. There were 72 male and 10 female patients, and the average age was 71.33 years. Hemorrhagic shock on the admission was observed in 45 patients, and 13 have been operated urgently without any diagnostic procedures. The transperitoneal approach have been used for the operation. Two aorto duodenal and one aorto caval fistulas, have been found. Only exploration (three patients died immediately after laparotomy and 6 after cross clamping) has been done in 9 cases, and the aortic replacement in 70 cases (27 with tubular, and 43 with bifurcated graft). In 3 cases and axillobifemoral bypass had to be done. During the operation eleven patients died, and 30 in postoperative period, during the period between one and 40 days. Total intrahospital mortality rate was 50%, compared with 3.5% for 250 electively operated patients with abdominal aortic aneurysms in same period. In postoperative period the most important cause of death was multiple organs failures. Statistically significant greater mortality rate (p > 0.01%) was found in cases of late operative treatment, hemorrhagic shock, intra-operational bleeding, ruptured front wall, suprarenal cross clamping and in patients older than 75 year. In complicated cases such as juxtarenal aneurysm, 3 sutures parachute technique for proximal anastomosis, a temporary transection of the left renal vein, and intraaortal balloon occlusive catheter for proximal bleeding control are recommended. PMID:10951761

Lotina, S I; Davidovi?, L B; Kosti?, D M; Stojanov, P L; Velimirovi?, D B; Djuki?, P L; Cinara, I S; Vojnovi?, B M; Savi?, D V

190

[Chemical control of plaque: comparative review].  

PubMed

Plaque control can be achieved by mechanical means. Since plaque removal can be laborious and difficult, chemical agents became important adjuncts to traditional oral hygiene procedures. Chlorhexidine is one of the synthetic antiseptics that has a unique antiplaque effect and 0.2% chlorhexidine can achieve a practically complete plaque control. It has one negative effect namely an extrinsic brown-yellow staining. Listerine has proven its ability to reduce plaque and gingivitis in a moderate way. Hexetidine has a greater antiplaque effect in combination with zinc and can be compared with a 0.1% chlorhexidine. Povidone-iodine can not be used to keep plaque at low levels. Sanguinarine can reduce plaque accumulation when the toothpaste and mouthrinse are used together. H2O2 is an antiplaque agent but has some negative effects such as ulcerations... One can conclude that the use of a chemical agent cannot replace a good mechanical plaque control but is rather an adjunct to oral hygiene under certain conditions. PMID:1891629

Marechal, M

1991-01-01

191

Parvovirus (feline panleucopaenia virus) plaque formation.  

PubMed

A plaque assay was developed for feline parvovirus (FPV; feline panleucopaenia virus) in a feline embryo (FEmb) cell line. Higher numbers and larger diameter plaques were obtained with a) seeding rates of 0.7 X 10(5) and 1.5 X 10(5) cells cf. 3 X 10(5) and 6 X 10(5) cells/well of 35 mm diameter, b) synchronised cells infected at the G1-S interface cf. nonsynchronised cells and c) 5 to 6 days incubation post inoculation. The plaque assay was standardised by using serum deprivation for 24 hours to synchronize cells, a seeding rate of 1.5 X 10(5) cells/35 mm diameter well, inoculation of virus 16 hours post seeding followed by 5 days incubation. The standardised assay gave consistent, reproducible results. A dose-response curve using the assay showed a linear, 45 degrees slope, relationship between plaque forming units and virus dilution which further verified the sensitivity and reliability of the assay. Plaques produced by "wild" type and plaque purified virus were invariably non uniform in diameter; diameter of plaques in fact followed a normal frequency distribution under standard assay conditions. PMID:2986580

Tham, K M; Studdert, M J

1985-01-01

192

Impact of flow rates in a cardiac cycle on correlations between advanced human carotid plaque progression and mechanical flow shear stress and plaque wall stress  

PubMed Central

Background Mechanical stresses are known to play important roles in atherosclerotic plaque initiation, progression and rupture. It has been well-accepted that atherosclerosis initiation and early progression correlate negatively with flow wall shear stresses (FSS). However, mechanisms governing advanced plaque progression are not well understood. Method In vivo serial MRI data (patient follow-up) were acquired from 14 patients after informed consent. Each patient had 2-4 scans (scan interval: 18 months). Thirty-two scan pairs (baseline and follow-up scans) were formed with slices matched for model construction and analysis. Each scan pair had 4-10 matched slices which gave 400-1000 data points for analysis (100 points per slice on lumen). Point-wise plaque progression was defined as the wall thickness increase (WTI) at each data point. 3D computational models with fluid-structure interactions were constructed based on in vivo serial MRI data to extract flow shear stress and plaque wall stress (PWS) on all data points to quantify correlations between plaque progression and mechanical stresses (FSS and PWS). FSS and PWS data corresponding to both maximum and minimum flow rates in a cardiac cycle were used to investigate the impact of flow rates on those correlations. Results Using follow-up scans and maximum flow rates, 19 out of 32 scan pairs showed a significant positive correlation between WTI and FSS (positive/negative/no significance correlation ratio = 19/9/4), and 26 out of 32 scan pairs showed a significant negative correlation between WTI and PWS (correlation ratio = 2/26/4). Corresponding to minimum flow rates, the correlation ratio for WTI vs. FSS and WTI vs. PWS were (20/7/5) and (2/26/4), respectively. Using baseline scans, the correlation ratios for WTI vs. FSS were (10/12/10) and (9/13/10) for maximum and minimum flow rates, respectively. The correlation ratios for WTI vs. PWS were the same (18/5/9), corresponding to maximum and minimum flow rates. Conclusion Flow shear stress corresponding to the minimum flow rates in a cardiac cycle had slightly better correlation with WTI, compared to FSS corresponding to maximum flow rates. Choice of maximum or minimum flow rates had no impact on PWS correlations. Advanced plaque progression correlated positively with flow shear stress and negatively with plaque wall stress using follow-up scans. Correlation results using FSS at the baseline scan were inconclusive.

2011-01-01

193

The prevention and regression of atherosclerotic plaques: emerging treatments  

PubMed Central

Occlusive vascular diseases, such as sudden coronary syndromes, stroke, and peripheral arterial disease, are a huge burden on the health care systems of developed and developing countries. Tremendous advances have been made over the last few decades in the diagnosis and treatment of atherosclerotic diseases. Intravascular ultrasound has been able to provide detailed information of plaque anatomy and has been used in several studies to assess outcomes. The presence of atherosclerosis disrupts the normal protective mechanism provided by the endothelium and this mechanism has been implicated in the pathophysiology of coronary artery disease and stroke. Efforts are being put into the prevention of atherosclerosis, which has been shown to begin in childhood. This paper reviews the pathophysiology of atherosclerosis and discusses the current options available for the prevention and reversal of plaque formation.

Kalanuria, Atul Ashok; Nyquist, Paul; Ling, Geoffrey

2012-01-01

194

A modified COMS plaque for iris melanoma  

PubMed Central

Melanoma of the iris is a rare condition compared to posterior ocular tumors and in this case report we present a 51-year-old female patient with diffuse iris melanoma. Traditional COMS (Collaborative Ocular Melanoma Study) plaques are used at our institution for radiation therapy, so a novel modification of the traditional plaque was required to allow better conformance with placement on the cornea. The usual silastic insert was machined to dimensions in compliance with the cornea, placed without incident, and treatment delivered with excellent patient tolerance of the modified plaque.

Vasudev, Deepta; Rice, Roger K.; Goldbaum, Michael; Mundt, Arno J.

2011-01-01

195

Effect of Time-dependent Rupture on Tsunami Generation  

NASA Astrophysics Data System (ADS)

Differential GPS data from the recent Chile 2009 and Japan 2011 seismic events have unveiled complex time-dependent ground motion dynamics during seismic rupture. Current tsunami modeling techniques usually ignore this time-dependent behavior in tsunami sources by assuming an instantaneous initial deformation field. Initial attempts to include time-dependent rupture behavior have motivated scientists to simulate this phenomenon as a series of instantaneous changes in the sea-floor. The present study investigates the effect of dynamic ground motion rupture on tsunami generation by including the time-dependent initial conditions in the derivation of the linear shallow-water wave equations. We then study the sensitivity of initial water surface deformation to time-dependent seafloor rupture by performing a parametric study of varying speed and rupture direction, while assuming a monotonic deformation from an initial pre-rupture state to a post-rupture final state. Numerical results for some selected scenarios are validated by comparing with analytical solutions of the non-homogeneous linear shallow-water equations.

Arcas, D.; Kanoglu, U.; Moore, C. W.; Aydin, B.

2013-12-01

196

Ruptured Abdominal AorticAneurysm  

Microsoft Academic Search

Background and Purpose: A ruptured abdominal aortic aneurysm is one of the most urgent surgical conditions with high mortality. The aim of the present study was to define relevant prognostic predictors for the outcome of surgical treatment. Patients and Methods: This study included 229 subsequent patients (83% males, 17% females, age 67.0 ± 7.5 years) with a ruptured abdominal aortic

Miroslav Markovi?; Lazar Davidovi?; Živan Maksimovi?; Dušan Kosti?; Ilijas ?inara; Slobodan Cvetkovi?; Radomir Sindjelic; Petar M. Seferovi?; Arsen D. Risti?

2004-01-01

197

Plantar Fascia Ruptures in Athletes  

Microsoft Academic Search

Objective: To educate sports medicine practitioners as to length of time for an athlete to return to activity after sustaining a rupture of the plantar fascia.Methods: Athletic patients sustaining plantar fascia ruptures and subsequent treatment were reviewed. Diagnosis was based on clinical findings, although radiographic studies were done. Patients were treated for 2 to 3 weeks with a below-knee or

Amol Saxena; Brian Fullem

2004-01-01

198

Consequential rupture of gas pipeline  

Microsoft Academic Search

In the earlier part of the year 2003, various pipeline ruptures were caused by sabotage activities in the southern part of Pakistan. The event being presented in this paper was fascinating because a pipe, which was blasted with the help of explosives, subsequently caused another pipe (buried 20ft away) to rupture through slow and gradual consequential erosion. On 8 April

F. Hasan; J. Iqbal

2006-01-01

199

Ruptured thought: rupture as a critical attitude to nursing research.  

PubMed

In this paper, we introduce the notion of ‘rupture’ from the French philosopher Michel Foucault, whose studies of discourse and governmentality have become prominent within nursing research during the last 25 years. We argue that a rupture perspective can be helpful for identifying and maintaining a critical potential within nursing research. The paper begins by introducing rupture as an inheritance from the French epistemological tradition. It then describes how rupture appears in Foucault's works, as both an overall philosophical approach and as an analytic tool in his historical studies. Two examples of analytical applications of rupture are elaborated. In the first example, rupture has inspired us to make an effort to seek alternatives to mainstream conceptions of the phenomenon under study. In the second example, inspired by Foucault's work on discontinuity, we construct a framework for historical epochs in nursing history. The paper concludes by discussing the potential of the notion of rupture as a response to the methodological concerns regarding the use of Foucault-inspired discourse analysis within nursing research. We agree with the critique of Cheek that the critical potential of discourse analysis is at risk of being undermined by research that tends to convert the approach into a fixed method. PMID:24741691

Beedholm, Kirsten; Lomborg, Kirsten; Frederiksen, Kirsten

2014-04-01

200

Evaluation of multicontrast MRI including fat suppression and inversion recovery spin echo for identification of intra-plaque hemorrhage and lipid core in human carotid plaque using the mahalanobis distance measure.  

PubMed

Intra-plaque hemorrhage (IPH) and lipid core, characteristics of rupture prone carotid plaques, are often visualized in vivo with MRI using T1 weighted gradient and spin echo, respectively. Increasing magnetic field strength may help to identify IPH and lipid core better. As a proof of concept, automatic segmentation of plaque components was performed with the Mahalanobis distance (MD) measure derived from image contrast from multicontrast MR images including inversion recovery spin echo and T1 weighted gradient echo with fat suppression. After MRI of nine formaldehyde-fixated autopsy specimens, the MDs and Euclidean Distances between plaque component intensities were calculated for each MR weighting. The distances from the carotid bifurcation and the size and shape of calcification spots were used as landmarks for coregistration of MRI and histology. MD between collagen/cell-rich area and IPH was largest with inversion recovery spin echo (4.2/9.3, respectively), between collagen/cell-rich area/foam cells and lipid core with T1 weighted gradient echo with fat suppression (26.9/38.2/4.6, respectively). The accuracy of detection of IPH, cell-rich area, and collagen increased when the MD classifier was used compared with the Euclidean Distance classifier. The enhanced conspicuity of lipid core and IPH in human carotid artery plaque, using ex vivo T1 weighted gradient echo with fat suppression and inversion recovery spin echo MRI and MD classifiers, demands further in vivo evaluation in patients. PMID:21997890

te Boekhorst, Bernard C; van 't Klooster, Ronald; Bovens, Sandra M; van de Kolk, Kees W; Cramer, Maarten J; van Oosterhout, Matthijs F; Doevendans, Pieter A; van der Geest, Rob J; Pasterkamp, Gerard; van Echteld, Cees J

2012-06-01

201

Retinal arterial wall plaques in Susac syndrome  

Microsoft Academic Search

PurposeTo demonstrate retinal arterial wall plaques (RAWPs) in patients with Susac syndrome, a disorder that consists of the triad of branch retinal artery occlusion, encephalopathy, and hearing loss. The clinician may misinterpret these RAWPs as emboli.

Robert A Egan; Thuy Ha Nguyen; J. Donald M Gass; Joseph F Rizzo III; John Tivnan; John O Susac

2003-01-01

202

Historical Plaque at Marshall Space Flight Center  

NASA Technical Reports Server (NTRS)

This plaque, located on the grounds of Marshall Space Flight Center in Huntsville, Alabama,commemorates the designation of the Saturn V Rocket as a National Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers in 1980.

2000-01-01

203

Historical Plaque at Marshall Space Flight Center  

NASA Technical Reports Server (NTRS)

This plaque, displayed on the grounds of Marshall Space Flight Center in Huntsville, Alabama, commemorates the Redstone Test Stand as an Alabama Historic Civil Engineering Landmark. The site was desinated as such in 1979.

2002-01-01

204

Tissue characterisation of atherosclerotic carotid plaques by MRI  

Microsoft Academic Search

Carotid artery plaques with intraplaque haemorrhage or atheromatous debris have been found to be associated with an increased risk of embolic stroke. Other methods have failed to detect plaque morphology, and it is not clear whether MRI allows differentiation between prognostically and therapeutically relevant plaque types. We examined 17 carotid bifurcation plaques which had been removed in toto by MRI.

M. Giirtler; A. Goldmann; W. Mohr; B. Widder

1995-01-01

205

A new inexpensive customized plaque for choroidal melanoma iodine-125 plaque therapy  

SciTech Connect

The authors have developed a new inexpensive precious metal alloy plaque for use in customized iodine-125 plaque therapy. Each plaque is formed from two flat circular gold/palladium foils which are used in dental crown work. Using a simple manual mechanism, the two forms are stamped over a customized acrylic die shaped to the dimensions of the tumor base plus a 2-mm margin. Completed plaques consist of a back wall, a 2-mm side wall, and a 1.5-mm wide lip with holes for suture placement. Advantages include: simple construction from inexpensive components, customized shape, and iodine seeds that are readily visible on plane radiographs.

Vine, A.K.; Tenhaken, R.K.; Diaz, R.F.; Maxson, B.B.; Lichter, A.S.

1989-04-01

206

Detection of High-Risk Atherosclerotic Plaque  

PubMed Central

The leading cause of major morbidity and mortality in most countries around the world is atherosclerotic cardiovascular disease, most commonly caused by thrombotic occlusion of a high-risk coronary plaque resulting in myocardial infarction or cardiac death, or embolization from a high-risk carotid plaque resulting in stroke. The lesions prone to result in such clinical events are termed vulnerable or high-risk plaques, and their identification may lead to the development of pharmacological and mechanical intervention strategies to prevent such events. Autopsy studies from patients dying of acute myocardial infarction or sudden death have shown that such events typically arise from specific types of atherosclerotic plaques, most commonly the thin-cap fibroatheroma. However, the search in human beings for vulnerable plaques before their becoming symptomatic has been elusive. Recently, the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study demonstrated that coronary plaques that are likely to cause future cardiac events, regardless of angiographic severity, are characterized by large plaque burden and small lumen area and/or are thin-cap fibroatheromas verified by radiofrequency intravascular ultrasound imaging. This study opened the door to identifying additional invasive and noninvasive imaging modalities that may improve detection of high-risk atherosclerotic lesions and patients. Beyond classic risk factors, novel biomarkers and genetic profiling may identify those patients in whom noninvasive imaging for vulnerable plaque screening, followed by invasive imaging for risk confirmation is warranted, and in whom future pharmacological and/or device-based focal or regional therapies may be applied to improve long-term prognosis.

Fleg, Jerome L.; Stone, Gregg W.; Fayad, Zahi A.; Granada, Juan F.; Hatsukami, Thomas S.; Kolodgie, Frank D.; Ohayon, Jacques; Pettigrew, Roderic; Sabatine, Marc S.; Tearney, Guillermo; Waxman, Sergio; Domanski, Michael J.; Srinivas, Pothur R.; Narula, Jagat

2013-01-01

207

Study of the regulatory position on postulated pipe rupture location criteria: piping reliability project  

Microsoft Academic Search

This report presents the results of studies on the current regulatory position on postulated pipe rupture location criteria and recommends future licensing regulations. The report contains five parts. The first part highlights the current regulatory positions on criteria for postulated pipe rupture locations. The second part reviews data on nuclear piping failures related to the failure locations in the piping

Woo

1983-01-01

208

Studies of the Rickettsial Plaque Assay Technique  

PubMed Central

A plaque assay system for pathogenic rickettsiae, which utilizes primary chick embryo tissue cultures, is described. It proved to be a highly reproducible measure of infectiousness for Rickettsia rickettsi and R. typhi, which were employed in most studies; as well as for R. canada, R. prowazeki, R. sibirica, R. akari, R. conori, and Coxiella burneti. Plaque-forming units (PFU) were compared to direct rickettsial counts and to 50% infectious dose (ID50) values for embryonated eggs, mice, and guinea pigs. Plaque size, appearance, and number were influenced by diluent, incubation temperature after nutrient overlay, centrifugation of inoculated tissue cultures, and number of host cells planted initially in each flask. The most critical factors in plaque formation were diluent used in making rickettsial suspensions and incubation temperature (32 C) after nutrient overlay. Brain Heart Infusion was the only diluent capable of preventing significant delay in plaque formation and decreases in PFU and mouse ID50. Plaque formation was unaffected by genetic background of host cells, volume of inoculum, temperature and length of incubation period before nutrient overlay, and rapid freezing and thawing of rickettsial seed. Centrifugation of inoculated cultures at 600 × g resulted in 100% irreversible absorption of rickettsiae to host cells within 5 min, whereas without centrifugation at least 4 hr was required to achieve the same effect. Images

Wike, David A.; Tallent, George; Peacock, Marius G.; Ormsbee, Richard A.

1972-01-01

209

Studies of the rickettsial plaque assay technique.  

PubMed

A plaque assay system for pathogenic rickettsiae, which utilizes primary chick embryo tissue cultures, is described. It proved to be a highly reproducible measure of infectiousness for Rickettsia rickettsi and R. typhi, which were employed in most studies; as well as for R. canada, R. prowazeki, R. sibirica, R. akari, R. conori, and Coxiella burneti. Plaque-forming units (PFU) were compared to direct rickettsial counts and to 50% infectious dose (ID(50)) values for embryonated eggs, mice, and guinea pigs. Plaque size, appearance, and number were influenced by diluent, incubation temperature after nutrient overlay, centrifugation of inoculated tissue cultures, and number of host cells planted initially in each flask. The most critical factors in plaque formation were diluent used in making rickettsial suspensions and incubation temperature (32 C) after nutrient overlay. Brain Heart Infusion was the only diluent capable of preventing significant delay in plaque formation and decreases in PFU and mouse ID(50). Plaque formation was unaffected by genetic background of host cells, volume of inoculum, temperature and length of incubation period before nutrient overlay, and rapid freezing and thawing of rickettsial seed. Centrifugation of inoculated cultures at 600 x g resulted in 100% irreversible absorption of rickettsiae to host cells within 5 min, whereas without centrifugation at least 4 hr was required to achieve the same effect. PMID:4629250

Wike, D A; Tallent, G; Peacock, M G; Ormsbee, R A

1972-05-01

210

High-resolution intravascular magnetic resonance quantification of atherosclerotic plaque at 3T  

PubMed Central

Background The thickness of fibrous caps (FCT) of atherosclerotic lesions is a critical factor affecting plaque vulnerability to rupture. This study tests whether 3 Tesla high-resolution intravascular cardiovascular magnetic resonance (CMR) employing tiny loopless detectors can identify lesions and accurately measure FCT in human arterial specimens, and whether such an approach is feasible in vivo using animal models. Methods Receive-only 2.2 mm and 0.8 mm diameter intravascular loopless CMR detectors were fabricated for a clinical 3 Tesla MR scanner, and the absolute signal-to-noise ratio determined. The detectors were applied in a two-step protocol comprised of CMR angiography to identify atherosclerotic lesions, followed by high-resolution CMR to characterize FCT, lesion size, and/or vessel wall thickness. The protocol was applied in fresh human iliac and carotid artery specimens in a human-equivalent saline bath. Mean FCT measured by 80 ?m intravascular CMR was compared with histology of the same sections. In vivo studies compared aortic wall thickness and plaque size in healthy and hyperlipidemic rabbit models, with post-mortem histology. Results Histology confirmed plaques in human specimens, with calcifications appearing as signal voids. Mean FCT agreed with histological measurements within 13% on average (correlation coefficient, R = 0.98; Bland-Altman analysis, -1.3 ± 68.9 ?m). In vivo aortic wall and plaque size measured by 80 ?m intravascular CMR agreed with histology. Conclusion Intravascular 3T CMR with loopless detectors can both locate atherosclerotic lesions, and accurately measure FCT at high-resolution in a strategy that appears feasible in vivo. The approach shows promise for quantifying vulnerable plaque for evaluating experimental therapies.

2012-01-01

211

A Meta Analysis and Hierarchical Classification of HU-Based Atherosclerotic Plaque Characterization Criteria  

PubMed Central

Background Many computed tomography (CT) studies have reported that lipid-rich, presumably rupture-prone atherosclerotic plaques can be characterized according to their Hounsfield Unit (HU) value. However, the published HU-based characterization criteria vary considerably. The present study aims to systematically analyze these values and empirically derive a hierarchical classification of the HU-based criteria which can be referred in clinical situation. Material and Methods A systematic search in PubMed and Embase for publications with HU-criteria to characterize lipid-rich and fibrous atherosclerotic plaques resulted in 36 publications, published between 1998 and 2011. The HU-criteria were systematically analyzed based on the characteristics of the reporting study. Significant differences between HU-criteria were checked using Student’s t-test. Subsequently, a hierarchical classification of HU-criteria was developed based on the respective study characteristics. Results No correlation was found between HU-criteria and the reported lumen contrast-enhancement. Significant differences were found for HU-criteria when pooled according to the respective study characteristics: examination type, vessel type, CT-vendor, detector-rows, voltage-setting, and collimation-width. The hierarchical classification resulted in 21 and 22 CT attenuation value categories, for lipid-rich and fibrous plaque, respectively. More than 50% of the hierarchically classified HU-criteria were significantly different. Conclusion In conclusion, variations in the reported CT attenuation values for lipid-rich and fibrous plaque are so large that generalized values are unreliable for clinical use. The proposed hierarchical classification can be used to determine reference CT attenuation values of lipid-rich and fibrous plaques for the local setting.

Kristanto, Wisnumurti; van Ooijen, Peter M. A.; Jansen-van der Weide, Marijke C.; Vliegenthart, Rozemarijn; Oudkerk, Matthijs

2013-01-01

212

The Dental Plaque Microbiome in Health and Disease  

PubMed Central

Dental decay is one of the most prevalent chronic diseases worldwide. A variety of factors, including microbial, genetic, immunological, behavioral and environmental, interact to contribute to dental caries onset and development. Previous studies focused on the microbial basis for dental caries have identified species associated with both dental health and disease. The purpose of the current study was to improve our knowledge of the microbial species involved in dental caries and health by performing a comprehensive 16S rDNA profiling of the dental plaque microbiome of both caries-free and caries-active subjects. Analysis of over 50,000 nearly full-length 16S rDNA clones allowed the identification of 1,372 operational taxonomic units (OTUs) in the dental plaque microbiome. Approximately half of the OTUs were common to both caries-free and caries-active microbiomes and present at similar abundance. The majority of differences in OTU’s reflected very low abundance phylotypes. This survey allowed us to define the population structure of the dental plaque microbiome and to identify the microbial signatures associated with dental health and disease. The deep profiling of dental plaque allowed the identification of 87 phylotypes that are over-represented in either caries-free or caries-active subjects. Among these signatures, those associated with dental health outnumbered those associated with dental caries by nearly two-fold. A comparison of this data to other published studies indicate significant heterogeneity in study outcomes and suggest that novel approaches may be required to further define the signatures of dental caries onset and progression.

Peterson, Scott N.; Snesrud, Erik; Liu, Jia; Ong, Ana C.; Kilian, Mogens; Schork, Nicholas J.; Bretz, Walter

2013-01-01

213

Stone Morphology Suggestive of Randall's Plaque  

NASA Astrophysics Data System (ADS)

Randall's plaques are found in a number of calcium oxalate stone formers. Stones developed on a Randall's plaque typically present a small depressed zone (``umbilication'') corresponding to the tip of the papilla and containing material detached from the plaque. By examining the morphology and infrared composition of 45,774 calculi referred to our laboratory over the past three decades, we identified 8,916 umbilicated calculi (19.5%). We have selected three periods of time corresponding to the first years of each decade. Over these periods, we analyzed 26,182 consecutive calculi. Among them, we identified 5,401 umbilicated calculi, of which 91.5% had an identifiable plaque. We analyzed the relative prevalence of umbilicated stones over time and the respective composition of Randall's plaque and stones. The proportion of umbilicated stones rose significantly from 10% in period 1 (1978-1984) to 21% in period 2 (1990-1993) and 22.2% in period 3 (2000-2006), with a parallel rise in the prevalence of stones with identifiable Randall's plaque. The main component of plaques was carbapatite in 90.8% of cases, whereas other components such as amorphous carbonated calcium phosphate, sodium hydrogen urate or uric acid were found in other cases. The morphology of plaques made of carbapatite was diverse, as was their carbonate content, thus suggesting variable pathophysiological mechanisms. Stones were made of whewellite as the main component in 51.4% of cases, or admixed with weddellite in 26.8%, predominant weddellite in 12.5% and other components (mainly uric acid) in 7.5% of cases. Our findings confirm that Randall's plaques are made of carbapatite in the great majority of cases, but with the stones more frequently composed of calcium oxalate monohydrate (which is associated with hyperoxaluria) than of calcium oxalate dihydrate (associated with hypercalciuria). In conclusion, in our country, stones developed on a carbapatite Randall's plaque are as frequently made of monohydrate than dihydrate calcium oxalate, thus suggesting a role for a high urine concentration in both oxalate and calcium ions in the lithogenic process.

Daudon, Michel; Traxer, Olivier; Jungers, Paul; Bazin, Dominique

2007-04-01

214

Antimicrobial effects of a stabilized stannous fluoride dentifrice in reducing plaque acid production--a single-brushing PGRM study.  

PubMed

A Plaque Glycolysis and Regrowth Method (PGRM) has been used to evaluate the in vivo antimicrobial activity of a new stabilized stannous fluoride dentifrice in comparison to a control dentifrice (Regular Crest, containing NaF) and a second commercial dentifrice containing SnF2. In the method, plaque collected from subjects prior to toothbrushing served as control for subsequent plaque samples collected following toothbrushing with assigned formulations. Inhibition of plaque metabolic activity was determined by the comparative acidogenicity of normalized plaque samples as contrasted with control plaques incubated similarly. Results from a sixteen-person cross-over study demonstrated that the improved stabilized stannous fluoride dentifrice significantly reduced plaque metabolism of sucrose in comparison to both placebo and commercial SnF2 dentifrice formulations following a single toothbrushing with 2.5 grams of dentifrice for over 90 minutes following treatment. These results support the strong antimicrobial activity of the stabilized stannous fluoride dentifrice, currently marketed as Crest Gum Care, in inhibiting plaque metabolism/acid production following in vivo toothbrushing. PMID:8593197

Liang, N; White, D J; Cox, E; Busemeyer, B A

1995-01-01

215

Carotid plaque assessment using fast 3D isotropic resolution black-blood MRI.  

PubMed

Black-blood MRI is a promising tool for carotid atherosclerotic plaque burden assessment and compositional analysis. However, current sequences are limited by large slice thickness. Accuracy of measurement can be improved by moving to isotropic imaging but can be challenging for patient compliance due to long scan times. We present a fast isotropic high spatial resolution (0.7×0.7×0.7 mm3) three-dimensional black-blood sequence (3D-MERGE) covering the entire cervical carotid arteries within 2 min thus ensuring patient compliance and diagnostic image quality. The sequence is optimized for vessel wall imaging of the carotid bifurcation based on its signal properties. The optimized sequence is validated on patients with significant carotid plaque. Quantitative plaque morphology measurements and signal-to-noise ratio measures show that 3D-MERGE provides good blood suppression and comparable plaque burden measurements to existing MRI protocols. 3D-MERGE is a promising new tool for fast and accurate plaque burden assessment in patients with atherosclerotic plaque. PMID:20941742

Balu, Niranjan; Yarnykh, Vasily L; Chu, Baocheng; Wang, Jinnan; Hatsukami, Thomas; Yuan, Chun

2011-03-01

216

A Fluorescence Lifetime Imaging Classification Method to Investigate the Collagen to Lipid Ratio in Fibrous Caps of Atherosclerotic Plaque  

PubMed Central

Background and Objective This study describes a novel fluorescence lifetime imaging (FLIM) classification method to determine the ratio of collagen to lipid content in the fibrous cap of atherosclerotic plaques. Additionally, an analytical process to assess risk of plaque rupture based on this ratio is proposed. Collagen to lipid ratio has been shown to be an important parameter to evaluate structural integrity of the fibrous cap. FLIM and other time-resolved fluorescence techniques have recently been applied to the study of atherosclerosis based on the ability to assess biochemical composition. Study Design/Materials and Methods Autofluorescence of specimens retrieved during carotid endarterectomy procedures was measured through three optical filters, F377: 377/50 nm, F460: 460/66 nm, and F510: 510/ 84 nm (center wavelength/bandwidth). A Laguerre deconvolution technique was used for the evaluation of fluorescence decay dynamics. The resulting decay parameters (average fluorescence lifetime and 4 Laguerre coefficients at each of the recorded bandwidths) were used for sample characterization. Linear discriminant analysis (LDA) was used to classify each image into collagen or lipid-rich regions based on these parameters. Ultimately, a risk-level was assigned based on the ratio of collagen to lipid on the surface of the fibrous cap. Results FLIM images were acquired in 18 carotid plaque specimens at 43 locations. Classification of collagen and lipid-rich regions within the fibrous cap was performed with sensitivity and specificity of 80% and 82%, respectively. Conclusions Results from this study show that an LDA method of classifying regions of FLIM images of carotid plaque into collagen and lipid-rich regions is capable of being automated and used to rate the risk of plaque rupture based on autofluorescence decay dynamics and without the need for fluorescence intensity or contrast agents. Lasers Surg. Med. 44:564–571, 2012.

Phipps, Jennifer E.; Sun, Yinghua; Fishbein, Michael C.; Marcu, Laura

2014-01-01

217

Amyloid Plaques in PSAPP Mice Bind Less Metal than Plaques in Human Alzheimer's Disease  

PubMed Central

Amyloid beta (A?) is the primary component of Alzheimer’s disease (AD) plaques, a key pathological feature of the disease. Metal ions of zinc (Zn), copper (Cu), iron (Fe), and calcium (Ca) are elevated in human amyloid plaques and are thought to be involved in neurodegeneration. Transgenic mouse models of AD also exhibit amyloid plaques, but fail to exhibit the high degree of neurodegeneration observed in humans. In this study, we imaged the Zn, Cu, Fe, and Ca ion distribution in the PSAPP transgenic mouse model representing end-stage AD (N = 6) using synchrotron X-ray fluorescence (XRF) microprobe. In order to account for differences in density in the plaques, the relative protein content was imaged with synchrotron Fourier transform infrared microspectroscopy (FTIRM) on the same samples. FTIRM results revealed a 61% increase in protein content in the plaques compared to the surrounding tissue. After normalizing to protein density, we found that the PSAPP plaques contained only a 29% increase in Zn and there was actually less Cu, Fe, and Ca in the plaque compared to the surrounding tissue. Since metal-binding to A? is thought to induce redox chemistry that is toxic to neurons, the reduced metal-binding in PSAPP mice is consistent with the lack of neurodegeneration in these animals. These findings were in stark contrast to the high metal ion content observed in human AD plaques, further implicating the role of metal ions in human AD pathology.

Leskovjan, Andreana C.; Lanzirotti, Antonio; Miller, Lisa M.

2009-01-01

218

A plaque-specific antibody clears existing ?-amyloid plaques in Alzheimer's disease mice.  

PubMed

A? Immunotherapy is a promising therapeutic approach for Alzheimer's disease. Preclinical studies demonstrate that plaque prevention is possible; however, the more relevant therapeutic removal of existing plaque has proven elusive. Monoclonal antibodies in development target both soluble and insoluble A? peptide. We hypothesized that antibody specificity for deposited plaque was critical for plaque removal since soluble A? peptide would block recognition of deposited forms. We developed a plaque-specific antibody that targets a modified A? peptide (A?(p3-42)), which showed robust clearance of pre-existing plaque without causing microhemorrhage. Interestingly, a comparator N-terminal A? antibody 3D6, which binds both soluble and insoluble A?(1-42), lacked efficacy for lowering existing plaque but manifested a significant microhemorrhage liability. Mechanistic studies suggested that the lack of efficacy for 3D6 was attributed to poor target engagement in plaques. These studies have profound implications for the development of therapeutic A? antibodies for Alzheimer's disease. PMID:23217740

Demattos, Ronald B; Lu, Jirong; Tang, Ying; Racke, Margaret M; Delong, Cindy A; Tzaferis, John A; Hole, Justin T; Forster, Beth M; McDonnell, Peter C; Liu, Feng; Kinley, Robert D; Jordan, William H; Hutton, Michael L

2012-12-01

219

The ruptured PIP breast implant.  

PubMed

Public concern erupted about the safety of Poly Implant Prothèse (PIP) breast implants when it was revealed in 2011 that they contained an inferior, unlicensed industrial-grade silicone associated with a high rate of rupture. There followed national guidance for UK clinicians, which led to a considerable increase in referrals of asymptomatic women for breast implant assessment. In this review we discuss possible approaches to screening the PIP cohort and the salient characteristics of a ruptured implant. PMID:23622796

Helyar, V; Burke, C; McWilliams, S

2013-08-01

220

In Vitro Shear Stress Measurements Using Particle Image Velocimetry in a Family of Carotid Artery Models: Effect of Stenosis Severity, Plaque Eccentricity, and Ulceration  

PubMed Central

Atherosclerotic disease, and the subsequent complications of thrombosis and plaque rupture, has been associated with local shear stress. In the diseased carotid artery, local variations in shear stress are induced by various geometrical features of the stenotic plaque. Greater stenosis severity, plaque eccentricity (symmetry) and plaque ulceration have been associated with increased risk of cerebrovascular events based on clinical trial studies. Using particle image velocimetry, the levels and patterns of shear stress (derived from both laminar and turbulent phases) were studied for a family of eight matched-geometry models incorporating independently varied plaque features – i.e. stenosis severity up to 70%, one of two forms of plaque eccentricity, and the presence of plaque ulceration). The level of laminar (ensemble-averaged) shear stress increased with increasing stenosis severity resulting in 2–16 Pa for free shear stress (FSS) and approximately double (4–36 Pa) for wall shear stress (WSS). Independent of stenosis severity, marked differences were found in the distribution and extent of shear stress between the concentric and eccentric plaque formations. The maximum WSS, found at the apex of the stenosis, decayed significantly steeper along the outer wall of an eccentric model compared to the concentric counterpart, with a 70% eccentric stenosis having 249% steeper decay coinciding with the large outer-wall recirculation zone. The presence of ulceration (in a 50% eccentric plaque) resulted in both elevated FSS and WSS levels that were sustained longer (?20 ms) through the systolic phase compared to the non-ulcerated counterpart model, among other notable differences. Reynolds (turbulent) shear stress, elevated around the point of distal jet detachment, became prominent during the systolic deceleration phase and was widely distributed over the large recirculation zone in the eccentric stenoses.

Kefayati, Sarah; Milner, Jaques S.; Holdsworth, David W.; Poepping, Tamie L.

2014-01-01

221

Rupture process of the 2013 Okhotsk deep mega earthquake from iterative backprojection and compress sensing methods  

NASA Astrophysics Data System (ADS)

On May 24th 2013 a Mw 8.3 normal faulting earthquake occurred at a depth of approximately 600 km beneath the sea of Okhotsk, Russia. It is a rare mega earthquake that ever occurred at such a great depth. We use the time-domain iterative backprojection (IBP) method [1] and also the frequency-domain compressive sensing (CS) technique[2] to investigate the rupture process and energy radiation of this mega earthquake. We currently use the teleseismic P-wave data from about 350 stations of USArray. IBP is an improved method of the traditional backprojection method, which more accurately locates subevents (energy burst) during earthquake rupture and determines the rupture speeds. The total rupture duration of this earthquake is about 35 s with a nearly N-S rupture direction. We find that the rupture is bilateral in the beginning 15 seconds with slow rupture speeds: about 2.5km/s for the northward rupture and about 2 km/s for the southward rupture. After that, the northward rupture stopped while the rupture towards south continued. The average southward rupture speed between 20-35 s is approximately 5 km/s, lower than the shear wave speed (about 5.5 km/s) at the hypocenter depth. The total rupture length is about 140km, in a nearly N-S direction, with a southward rupture length about 100 km and a northward rupture length about 40 km. We also use the CS method, a sparse source inversion technique, to study the frequency-dependent seismic radiation of this mega earthquake. We observe clear along-strike frequency dependence of the spatial and temporal distribution of seismic radiation and rupture process. The results from both methods are generally similar. In the next step, we'll use data from dense arrays in southwest China and also global stations for further analysis in order to more comprehensively study the rupture process of this deep mega earthquake. Reference [1] Yao H, Shearer P M, Gerstoft P. Subevent location and rupture imaging using iterative backprojection for the 2011 Tohoku Mw 9.0 earthquake. Geophysical Journal International, 2012, 190(2): 1152-1168. [2]Yao H, Gerstoft P, Shearer P M, et al. Compressive sensing of the Tohoku-Oki Mw 9.0 earthquake: Frequency-dependent rupture modes. Geophysical Research Letters, 2011, 38(20).

Qin, W.; Yin, J.; Yao, H.

2013-12-01

222

Localized pleural plaques and lung cancer  

SciTech Connect

In a mass chest radiography survey conducted in 1971 for 7,986 residents of three Finnish communities, 604 subjects (7.6%) with pleural plaques but not other asbestos-related radiographic signs were identified. The same number of referents, each individually matched to each plaque carrier on sex, birth year, and community, was selected from among persons in the same source population with no pleural plaques. The two groups were followed for investigation of incidence of lung cancer during 1972-1989. Twenty-eight of those with plaques and 25 referents contracted lung cancer (crude conditional RR = 1.1; CL95 = 0.7, 1.9). The application of the proportional hazards model, with adjustment for sex, age, and residence, resulted in a hazard ratio of 1.1 (CL = 0.6, 1.8). The risk ratio estimate may be biased; hence, the result is inconclusive in regard to the predictive assessment of lung cancer risk among carriers of pleural plaques.

Partanen, T.; Nurminen, M.; Zitting, A.; Koskinen, H.; Wiikeri, M.; Ahlman, K. (Department of Epidemiology and Biostatistics, Institute of Occupational Health, Helsinki (Finland))

1992-01-01

223

Hyperspectral imaging of atherosclerotic plaques in vitro  

NASA Astrophysics Data System (ADS)

Vulnerable plaques constitute a risk for serious heart problems, and are difficult to identify using existing methods. Hyperspectral imaging combines spectral- and spatial information, providing new possibilities for precise optical characterization of atherosclerotic lesions. Hyperspectral data were collected from excised aorta samples (n = 11) using both white-light and ultraviolet illumination. Single lesions (n = 42) were chosen for further investigation, and classified according to histological findings. The corresponding hyperspectral images were characterized using statistical image analysis tools (minimum noise fraction, K-means clustering, principal component analysis) and evaluation of reflectance/fluorescence spectra. Image analysis combined with histology revealed the complexity and heterogeneity of aortic plaques. Plaque features such as lipids and calcifications could be identified from the hyperspectral images. Most of the advanced lesions had a central region surrounded by an outer rim or shoulder-region of the plaque, which is considered a weak spot in vulnerable lesions. These features could be identified in both the white-light and fluorescence data. Hyperspectral imaging was shown to be a promising tool for detection and characterization of advanced atherosclerotic plaques in vitro. Hyperspectral imaging provides more diagnostic information about the heterogeneity of the lesions than conventional single point spectroscopic measurements.

Larsen, Eivind L. P.; Randeberg, Lise L.; Olstad, Elisabeth; Haugen, Olav A.; Aksnes, Astrid; Svaasand, Lars O.

2011-02-01

224

Modelling Blood Flow and Analysis of Atherosclerotic Plaque Rupture under G-Force  

Microsoft Academic Search

In normal life the human body is quite often subjected to g-force. Prolonged exposure to such accelerations can generate significant effects on the blood circulation and its theological behavior depending on the configuration and geometry of the blood vessels. To analyze the effect of body acceleration in blood flow in arteries, blood is considered as a non-Newtonian fluid. The Navier-Stokes

T. K. Deepa; L. S. Binu; A. K. Sukesh

2009-01-01

225

Rapid Estimates of Rupture Extent for Large Earthquakes Using Aftershocks  

NASA Astrophysics Data System (ADS)

The spatial distribution of aftershocks is closely linked to the rupture extent of the mainshock that preceded them and a rapid analysis of aftershock patterns therefore has potential for use in near real-time estimates of earthquake impact. The correlation between aftershocks and slip distribution has frequently been used to estimate the fault dimensions of large historic earthquakes for which no, or insufficient, waveform data is available. With the advent of earthquake inversions that use seismic waveforms and geodetic data to constrain the slip distribution, the study of aftershocks has recently been largely focused on enhancing our understanding of the underlying mechanisms in a broader earthquake mechanics/dynamics framework. However, in a near real-time earthquake monitoring environment, in which aftershocks of large earthquakes are routinely detected and located, these data may also be effective in determining a fast estimate of the mainshock rupture area, which would aid in the rapid assessment of the impact of the earthquake. We have analyzed a considerable number of large recent earthquakes and their aftershock sequences and have developed an effective algorithm that determines the rupture extent of a mainshock from its aftershock distribution, in a fully automatic manner. The algorithm automatically removes outliers by spatial binning, and subsequently determines the best fitting “strike” of the rupture and its length by projecting the aftershock epicenters onto a set of lines that cross the mainshock epicenter with incremental azimuths. For strike-slip or large dip-slip events, for which the surface projection of the rupture is recti-linear, the calculated strike correlates well with the strike of the fault and the corresponding length, determined from the distribution of aftershocks projected onto the line, agrees well with the rupture length. In the case of a smaller dip-slip rupture with an aspect ratio closer to 1, the procedure gives a measure of the rupture extent and dimensions, but not necessarily the strike. We found that using standard earthquake catalogs, such as the National Earthquake Information Center catalog, we can constrain the rupture extent, rupture direction, and in many cases the type of faulting, of the mainshock with the aftershocks that occur within the first hour after the mainshock. However, this data may not be currently available in near real-time. Since our results show that these early aftershock locations may be used to estimate first order rupture parameters for large global earthquakes, the near real-time availability of these data would be useful for fast earthquake damage assessment.

Polet, J.; Thio, H. K.; Kremer, M.

2009-12-01

226

Integrated IVUS-OCT Imaging for Atherosclerotic Plaque Characterization  

PubMed Central

For the diagnosis of atherosclerosis, biomedical imaging techniques such as intravascular ultrasound (IVUS) and optical coherence tomography (OCT) have been developed. The combined use of IVUS and OCT is hypothesized to remarkably increase diagnostic accuracy of vulnerable plaques. We have developed an integrated IVUS-OCT imaging apparatus, which includes the integrated catheter, motor drive unit, and imaging system. The dual-function imaging catheter has the same diameter of current clinical standard. The imaging system is capable for simultaneous IVUS and OCT imaging in real time. Ex vivo and in vivo experiments on rabbits with atherosclerosis were conducted to demonstrate the feasibility and superiority of the integrated intravascular imaging modality.

Li, Xiang; Li, Jiawen; Jing, Joe; Ma, Teng; Liang, Shanshan; Zhang, Jun; Mohar, Dilbahar; Raney, Aidan; Mahon, Sari; Brenner, Matthew; Patel, Pranav; Shung, K. Kirk; Zhou, Qifa; Chen, Zhongping

2014-01-01

227

Blood flow characteristics in a terminal basilar tip aneurysm prior to its fatal rupture  

PubMed Central

Background and Purpose The development and validation of methods to stratify the risk of rupture of cerebral aneurysms is highly desired since current treatment risks can exceed the natural risk of rupture. Because unruptured aneurysms are typically treated before they rupture, it is very difficult to connect the proposed risk indices to the rupture of an individual aneurysm. The purpose of this case study was to analyze the hemodynamic environment of a saccular aneurysm of the terminal morphology sub-type that was imaged just prior to its rupture and to test whether the hemodynamic characteristics would designate this particular aneurysm as at high risk. Methods A patient-specific computational fluid dynamics model was constructed from 3D rotational angiography images acquired just hours before the aneurysm ruptured. A pulsatile flow calculation was performed and hemodynamic characteristics previously connected to rupture were analyzed. Results It was found that the aneurysm had a concentrated inflow stream, small impingement region, complex intra-aneurysmal flow structure, asymmetric flow split from the parent vessel to the aneurysm and daughter branches, and high levels of aneurysmal wall shear stress near the impaction zone. Conclusions The hemodynamics characteristics observed in this aneurysm right before its rupture are consistent with previous studies correlating aneurysm rupture and hemodynamic patterns in saccular and terminal aneurysms. This study supports the notion that hemodynamic information may be used to help stratify the rupture risk of cerebral aneurysms.

Sforza, D.M.; Putman, C.M.; Scrivano, E.; Lylyk, P.; Cebral, J.R.

2010-01-01

228

Infliximab for the treatment of plaque psoriasis  

PubMed Central

Infliximab is a monoclonal antibody that targets tumor necrosis factor-? (TNF?). It is used in the treatment of a number of inflammatory disorders including severe plaque psoriasis. TNF? is thought to have a major role in psoriasis by promoting an inflammatory infiltrate into the skin and inducing keratinocyte proliferation and preventing keratinocyte apoptosis, which directly contributes to the characteristic plaque skin lesions. Based on four randomized, placebo-controlled, double-blind clinical trials and nine open-label uncontrolled trials of the use of infliximab in plaque psoriasis, it was found that infliximab is a highly efficacious, rapid, sustainable, and relatively safe therapy. Yet as with any biologic, caution is recommended in its use as infusion reactions, lupus-like syndromes, infections, malignancies including lymphomas, as well as other rare events have been reported.

Gall, Jennifer S; Kalb, Robert E

2008-01-01

229

Fault Branching and Rupture Directivity  

NASA Astrophysics Data System (ADS)

Can the rupture directivity of past earthquakes be inferred from fault geometry? Nakata et al. [J. Geogr., 1998] propose to relate the observed surface branching of fault systems with directivity. Their work assumes that all branches are through acute angles in the direction of rupture propagation. However, in some observed cases rupture paths seem to branch through highly obtuse angles, as if to propagate ``backwards". Field examples of that are as follows: (1) Landers 1992. When crossing from the Johnson Valley to the Homestead Valley (HV) fault via the Kickapoo (Kp) fault, the rupture from Kp progressed not just forward onto the northern stretch of the HV fault, but also backwards, i.e., SSE along the HV [Sowers et al., 1994, Spotila and Sieh, 1995, Zachariasen and Sieh, 1995, Rockwell et al., 2000]. Measurements of surface slip along that backward branch, a prominent feature of 4 km length, show right-lateral slip, decreasing towards the SSE. (2) At a similar crossing from the HV to the Emerson (Em) fault, the rupture progressed backwards along different SSE splays of the Em fault [Zachariasen and Sieh, 1995]. (3). In crossing from the Em to Camp Rock (CR) fault, again, rupture went SSE on the CR fault. (4). Hector Mine 1999. The rupture originated on a buried fault without surface trace [Li et al., 2002; Hauksson et al., 2002] and progressed bilaterally south and north. In the south it met the Lavic Lake (LL) fault and progressed south on it, but also progressed backward, i.e. NNW, along the northern stretch of the LL fault. The angle between the buried fault and the northern LL fault is around -160o, and that NNW stretch extends around 15 km. The field examples with highly obtuse branch angles suggest that there may be no simple correlation between fault geometry and rupture directivity. We propose that an important distinction is whether those obtuse branches actually involved a rupture path which directly turned through the obtuse angle (while continuing also on the main fault), or rather involved arrest by a barrier on the original fault and jumping [Harris and Day, JGR, 1993] to a neighboring fault on which rupture propagated bilaterally to form what appears as a backward-branched structure. Our studies [Poliakov et al., JGR in press, 2002; Kame et al, EOS, 2002] of stress fields around a dynamically moving mode II crack tip show a clear tendency to branch from the straight path at high rupture speeds, but the stress fields never allow the rupture path to directly turn through highly obtuse angles, and hence that mechanism is unlikely. In contrast, study of fault maps in the vicinity of the Kp to HV fault transition [Sowers et al., 1994], discussed as case (1) above, strongly suggest that the large-angle branching occurred as a jump, which we propose as the likely general mechanism. Implications for the Nakata et al. [1998] aim of inferring rupture directivity from branch geometry is that this will be possible only when rather detailed characterization (by surface geology, seismic relocation, trapped waves) of fault connectivity can be carried out in the vicinity of the branching junction, to ascertain whether direct turning of the rupture path through an angle, or jumping and then propagating bilaterally, were involved in prior events. They have opposite implications for how we would associate past directivity with a (nominally) branched fault geometry.

Dmowska, R.; Rice, J. R.; Kame, N.

2002-12-01

230

Should ruptured liver haemangioma be treated by surgery or by conservative means? A case report.  

PubMed

Spontaneous rupture of a liver haemangioma is a rare but life-threatening acute clinical situation following haemorrhage within the liver, the subcapsular space and the peritoneal cavity in cases of capsular rupture. Rupture of a liver haemangioma has been reported to occur spontaneously in the majority of cases. In the past, prompt surgical treatment was recommended but was associated with high morbidity and mortality. Currently, conservative management and, in cases of recurrent haemorrhage, delayed surgery may be proposed. We report a case of spontaneous rupture of hepatic haemangioma treated by arterial embolisation and conservative means. The literature is also reviewed. PMID:19241936

Vokaer, B; Kothonidis, K; Delatte, P; De Cooman, S; Pector, J C; Liberale, G

2008-01-01

231

Regions of high wall stress can predict the future location of rupture of abdominal aortic aneurysm.  

PubMed

Predicting the wall stress in abdominal aortic aneurysm (AAA) using computational modeling may be a useful adjunct to traditional clinical parameters that indicate the risk of rupture. Maximum diameter has been shown to have many limitations, and using current technology it is possible to provide a patient-specific computational risk assessment using routinely acquired medical images. We present a case of AAA rupture where the exact rupture point was clearly visible on the computed tomography (CT) images. A blind computational study based on CT scans acquired 4 months earlier predicted elevated wall stresses in the same region that later experienced rupture. PMID:24554200

Doyle, Barry J; McGloughlin, Timothy M; Miller, Karol; Powell, Janet T; Norman, Paul E

2014-06-01

232

The Role of Geometric and Biomechanical Factors in Abdominal Aortic Aneurysm Rupture Risk Assessment  

PubMed Central

The current clinical management of abdominal aortic aneurysm (AAA) disease is based to a great extent on measuring the aneurysm maximum diameter to decide when timely intervention is required. Decades of clinical evidence show that aneurysm diameter is positively associated with the risk of rupture, but other parameters may also play a role in causing or predisposing the AAA to rupture. Geometric factors such as vessel tortuosity, intraluminal thrombus volume, and wall surface area are implicated in the differentiation of ruptured and unruptured AAAs. Biomechanical factors identified by means of computational modeling techniques, such as peak wall stress, have been positively correlated with rupture risk with a higher accuracy and sensitivity than maximum diameter alone. The objective of this review is to examine these factors, which are found to influence AAA disease progression, clinical management and rupture potential, as well as to highlight on-going research by our group in aneurysm modeling and rupture risk assessment.

Raut, Samarth S.; Chandra, Santanu; Shum, Judy; Finol, Ender A.

2013-01-01

233

Visualizing the atherosclerotic plaque: a chemical perspective.  

PubMed

Atherosclerosis is the major underlying pathologic cause of coronary artery disease. An early detection of the disease can prevent clinical sequellae such as angina, myocardial infarction, and stroke. The different imaging techniques employed to visualize the atherosclerotic plaque provide information of diagnostic and prognostic value. Furthermore, the use of contrast agents helps to improve signal-to-noise ratio providing better images. For nuclear imaging techniques and optical imaging these agents are absolutely necessary. We report on the different contrast agents that have been used, are used or may be used in future in animals, humans, or excised tissues for the distinct imaging modalities for atherosclerotic plaque imaging. PMID:24526041

Teresa Albelda, Ma; Garcia-España, Enrique; Frias, Juan C

2014-04-21

234

Dobesilate in the treatment of plaque psoriasis.  

PubMed

Fibroblast growth factor (FGF)-mediated pathways participate in many of the cellular events implicated in the pathogenesis of psoriasis. Thus, targeting FGF signals may be potentially therapeutic in the treatment of psoriasis. We report for the first time on a 43-year-old man with chronic-type plaque psoriasis with a daily topical treatment of dobesilate, a new FGF inhibitor. As early as at day 14, the patient had cleared or achieved excellent improvement of psoriatic skin lesions. Topical dobesilate offers the potential for treatment of plaque psoriasis without atrophy or other local side effects associated with the use of topical corticosteroids. PMID:16183548

Cuevas, Pedro; Arrazola, Jose M

2005-09-12

235

Molecular Imaging of Atherosclerotic Plaques Targeted to Oxidized LDL Receptor LOX-1 Using SPECT/CT and Magnetic Resonance  

PubMed Central

Background The oxidized-LDL receptor LOX-1 plays a crucial role in atherosclerosis. We sought to detect and assess atherosclerotic plaque in vivo using SPECT/CT and magnetic resonance imaging (MRI) using a molecular probe targeted at LOX-1. Methods & Results Apo E?/? mice on Western diet and LDLR?/? and LDLR?/?/LOX-1?/? mice on atherogenic diet were used. Imaging probes consisted of liposomes decorated with LOX-1 antibodies (LOX-1) or nonspecific IgG (nIgG), 111In or gadolinium (Gd), and DiI fluorescence markers. In vivo imaging was performed 24 hrs after intravenous injection (150 µl) of LOX-1 (or nIgG) probes labeled with either 111In (600 µCi) or Gd (0.075 mmol/kg) followed by aortic excision for phosphor imaging and Sudan IV staining or fluorescence imaging and H&E staining. The LOX-1 probe was also co-localized with specific cell types, apoptosis, and MMP9 expression using frozen aortic sections. SPECT/CT imaging of the LOX-1 probe showed aortic arch hotspots in Apo E?/? mice (n=8), confirmed by phosphor imaging. MRI showed significant Gd enhancement in atherosclerotic plaques in LDLR?/? mice with the LOX-1 (n=7), but not nIgG, probe (n=5). No signal enhancement was observed in LDLR?/?/LOX-1?/? mice injected with LOX-1 probe (n=5). These results were confirmed by ex-vivo fluorescence imaging. The LOX-1 probe bound preferentially to the plaque shoulder, a region with vulnerable plaque features including extensive LOX-1 expression, macrophage accumulation, apoptosis and MMP9 expression. Conclusions LOX-1 can be used as a target for molecular imaging of atherosclerotic plaque in vivo. Furthermore, LOX-1 imaging may identify rupture-prone atherosclerotic plaque.

Li, Dayuan; Patel, Amit; Klibanov, Alexander L.; Kramer, Christopher M.; Ruiz, Mirta; Kang, Bum-Yong; Mehta, Jawahar L.; Beller, George A.; Glover, David K.; Meyer, Craig H

2010-01-01

236

DIFFERENTIAL EFFECT OF TETRAZOLIUM UPON BACTERIOPHAGE PLAQUE ASSAY TITERS  

EPA Science Inventory

This study examined whether the practice of incorporating either tetrazolium red ortetrazolium violet dye into plaque assay medium deleteriously influences plaque assay titers. epresentative members of six different virus families were studied: ystoviridae (06), Leviviridae (MS2)...

237

Enumeration of bacteriophages by the direct plating plaque assay.  

PubMed

A method is described for determination of the concentration of infectious phage particles by the direct plating plaque assay, which is simpler and faster than the double agar overlay plaque procedure outlined in the previous chapter. PMID:19066812

Mazzocco, Amanda; Waddell, Thomas E; Lingohr, Erika; Johnson, Roger P

2009-01-01

238

Polymeric nanoparticle PET/MR imaging allows macrophage detection in atherosclerotic plaques.  

PubMed

Rationale: Myeloid cell content in atherosclerotic plaques associates with rupture and thrombosis. Thus, imaging of lesional monocytes and macrophages could serve as a biomarker of disease progression and therapeutic intervention. Objective: To noninvasively assess plaque inflammation with dextran nanoparticle (DNP)-facilitated hybrid positron emission tomography/magnetic resonance imaging (PET/MRI). Methods and Results: Using clinically approved building blocks, we systematically developed 13-nm polymeric nanoparticles consisting of cross-linked short chain dextrans, which were modified with desferoxamine for zirconium-89 radiolabeling ((89)Zr-DNP) and a near-infrared fluorochrome (VT680) for microscopic and cellular validation. Flow cytometry of cells isolated from excised aortas showed DNP uptake predominantly in monocytes and macrophages (76.7%) and lower signal originating from other leukocytes, such as neutrophils and lymphocytes (11.8% and 0.7%, P<0.05 versus monocytes and macrophages). DNP colocalized with the myeloid cell marker CD11b on immunohistochemistry. PET/MRI revealed high uptake of (89)Zr-DNP in the aortic root of apolipoprotein E knock out (ApoE(-/-)) mice (standard uptake value, ApoE(-/-) mice versus wild-type controls, 1.9±0.28 versus 1.3±0.03; P<0.05), corroborated by ex vivo scintillation counting and autoradiography. Therapeutic silencing of the monocyte-recruiting receptor C-C chemokine receptor type 2 with short-interfering RNA decreased (89)Zr-DNP plaque signal (P<0.05) and inflammatory gene expression (P<0.05). Conclusions: Hybrid PET/MRI with a 13-nm DNP enables noninvasive assessment of inflammation in experimental atherosclerotic plaques and reports on therapeutic efficacy of anti-inflammatory therapy. PMID:23300273

Majmudar, Maulik D; Yoo, Jeongsoo; Keliher, Edmund J; Truelove, Jessica J; Iwamoto, Yoshiko; Sena, Brena; Dutta, Partha; Borodovsky, Anna; Fitzgerald, Kevin; Di Carli, Marcelo F; Libby, Peter; Anderson, Daniel G; Swirski, Filip K; Weissleder, Ralph; Nahrendorf, Matthias

2013-03-01

239

Enzyme-Sensitive MR Imaging Targeting Myeloperoxidase Identifies Active Inflammation in Experimental Rabbit Atherosclerotic Plaques  

PubMed Central

Background Inflammation undermines the stability of atherosclerotic plaques, rendering them susceptible to acute rupture, the cataclysmic event that underlies clinical expression of this disease. Myeloperoxidase (MPO) is a central inflammatory enzyme secreted by activated macrophages, and is involved in multiple stages of plaque destabilization and patient outcome. We report here that a unique functional in vivo magnetic resonance (MR) agent can visualize MPO activity in atherosclerotic plaques in a rabbit model. Methods and Results We performed MR imaging of the thoracic aorta of New Zealand white (NZW) rabbits fed a cholesterol (n=11) or normal (n=4) diet up to 2 hours after injection of the MPO sensor bis-5HT-DTPA(Gd) (MPO(Gd)), the conventional agent, DTPA(Gd), or an MPO (Gd) analog, bis-tyr-DTPA(Gd), as controls. Delayed MPO(Gd) images (2 hour post injection) showed focal areas of increased contrast (>2-fold) in diseased wall, but not in normal wall (p=0.84), compared to both DTPA(Gd) (n=11; p<0.001) and bis-tyr-DTPA(Gd) (n=3; p<0.05). Biochemical assays confirmed that diseased wall possessed three-fold elevated MPO activity compared to normal wall (p<0.01). Areas detected by MPO(Gd) imaging co-localized and correlated with MPO-rich areas infiltrated by macrophages on histopathological evaluations (r=0.91, p<0.0001). While macrophages were the main source of MPO, not all macrophages secreted MPO, suggesting that distinct subpopulations contribute differently to atherogenesis and supporting our functional approach. Conclusions Our study represents a unique approach in the detection of inflammation in atherosclerotic plaques by examining macrophage function and the activity of an effector enzyme, to noninvasively provide both anatomic and functional information in vivo.

Ronald, John A.; Chen, John W.; Chen, Yuanxin; Hamilton, Amanda M.; Rodriguez, Elisenda; Reynolds, Fred; Hegele, Robert A.; Rogers, Kem A.; Querol, Manel; Bogdanov, Alexei; Weissleder, Ralph; Rutt, Brian K.

2009-01-01

240

Apolipoprotein D is a component of compact but not diffuse amyloid-beta plaques in Alzheimer's disease temporal cortex  

Microsoft Academic Search

Apolipoprotein D (apoD) is elevated in Alzheimer's disease (AD) cortex, localizing to cells, blood vessels, and neuropil deposits (plaques). The role of apoD in AD pathology and the extent of its co-distribution with diffuse (amorphous) and compact (dense fibrillar) amyloid-beta (A?) plaques are currently unclear. To address this issue, we combined apoD and A? immunohistochemistry with ThioS\\/X-34 staining of the

Purnima P. Desai; Milos D. Ikonomovic; Eric E. Abrahamson; Ronald L. Hamilton; Barbara A. Isanski; Caroline E. Hope; William E. Klunk; Steven T. DeKosky; M. Ilyas Kamboh

2005-01-01

241

Vortex dynamics in ruptured and unruptured intracranial aneurysms  

NASA Astrophysics Data System (ADS)

Intracranial aneurysms (IAs) are a potentially devastating pathological dilation of brain arteries that affect 1.5-5 % of the population. Causing around 500 000 deaths per year worldwide, their detection and treatment to prevent rupture is critical. Multiple recent studies have tried to find a hemodynamics predictor of aneurysm rupture, but concluded with distinct opposite trends using Wall Shear Stress (WSS) based parameters in different clinical datasets. Nevertheless, several research groups tend to converge for now on the fact that the flow patterns and flow dynamics of the ruptured aneurysms are complex and unstable. Following this idea, we investigated the vortex properties of both unruptured and ruptured cerebral aneurysms. A brief comparison of two Eulerian vortex visualization methods (Q-criterion and lambda 2 method) showed that these approaches gave similar results in our complex aneurysm geometries. We were then able to apply either one of them to a large dataset of 74 patient specific cases of intracranial aneurysms. Those real cases were obtained by 3D angiography, numerical reconstruction of the geometry, and then pulsatile CFD simulation before post-processing with the mentioned vortex visualization tools. First we tested the two Eulerian methods on a few cases to verify their implementation we made as well as compare them with each other. After that, the Q-criterion was selected as method of choice for its more obvious physical meaning (it shows the balance between two characteristics of the flow, its swirling and deformation). Using iso-surfaces of Q, we started by categorizing the patient-specific aneurysms based on the gross topology of the aneurysmal vortices. This approach being unfruitful, we found a new vortex-based characteristic property of ruptured aneurysms to stratify the rupture risk of IAs that we called the Wall-Kissing Vortices, or WKV. We observed that most ruptured aneurysms had a large amount of WKV, which appears to agree with the current hypothesized biological triggers of pathological remodeling of the artery walls. Having a good natural ratio of statuses in our IA cohort (55 unruptured vs. 19 ruptured), we were able to test the statistical significance of our predictor to fortify our findings. We also performed a distribution analysis of our cohort with respect to the number of WKV to strengthen the encouraging statistical analysis result; both analyses provided a clear good separation of the status of the aneurysms based on our predictor. Lastly, we constructed a receiver operating characteristic (ROC) curve to analyze the power different thresholds of WKV had in splitting the data in a binary way (unruptured/ruptured). The number of WKV was efficaciously able to stratify the rupture status, identifying 84.21 % of the ruptured aneurysms (with 25.45 % of false positives, i.e. unruptured IAs tagged as ruptured) when using a threshold value of 2. Our novel work undertaken to study the vortex structures in IAs brought to light interesting characteristics of the flow in the aneurysmal sac. We found that there are several distinct categories in which the aneurysm vortex topologies can be put in without relationship to the aneurysm rupture status. This first finding was in contradiction with available already-published results. Nonetheless, ruptured IAs had a statistically significant larger amount of WKV as opposed to unruptured aneurysms. This new predictor we propose to the community could very well clear a new path among the currently controversial WSS-based parameters. Although it needs to be improved to be more resilient, the first results obtained by the WKV-based parameter are promising when applied to a large dataset of 74 IAs patient-specific transient CFD simulations.

Trylesinski, Gabriel

242

Improved treatment planning for COMS eye plaques  

Microsoft Academic Search

Purpose: A recent reanalysis of the Collaborative Ocular Melanoma Study (COMS) medium tumor trial concluded that incorporating factors to account for anisotropy, line source approximation, the gold plaque, and attenuation in the Silastic seed carrier into the dose calculations resulted in a significant and consistent reduction of calculated doses to structures of interest within the eye. The authors concluded that

Melvin A. Astrahan

2005-01-01

243

Spontaneous Rupture of the Esophagus  

PubMed Central

Spontaneous rupture of the esophagus remains a medical and surgical challenge. Its diagnosis is often missed or delayed resulting in increased morbidity and mortality, and controversy exists as to the mode of therapy for the cases seen later than 12 hours after rupture. During the last seven years, nine patients were treated at Grady Memorial Hospital. Four patients, “early group,” were operated upon within 12 hours from the onset of their symptoms and five, “late group,” were operated upon between 20-76 hours (average 41) after rupture. All four patients in the “early group” had primary repair of the rupture and two had, in addition, fundoplication. From the two patients with primary repair alone, one developed postoperative leakage at the esophageal suture line, which closed spontaneously; whereas, in the two patients with fundoplication, no leakage occurred. Three of the four patients recovered and one died from renal failure, gastrointestinal bleeding, and gastric perforation. In the “late group” one patient had T-tube drainage of the esophagus and died. Two had primary repair alone with one death and the other two had primary repair with fundoplication 20 and 76 hours postrupture and both recovered. The two deaths in the “late group” were due to leakage at the site of the rupture. This study suggests that even in patients diagnosed late as having rupture of the esophagus, primary repair can be implemented with reasonable success. Good mediastinal, pleural and gastric drainage, high levels of appropriate antibiotics, and provision of good nourishment are of paramount importance for the successful management of these desperately ill patients. ImagesFig. 2A.FIG. 2B.FIG. 2C.Fig. 2D.

Symbas, Panagiotis N.; Hatcher, Charles R.; Harlaftis, Nickolaos

1978-01-01

244

Requirements for imaging vulnerable plaque in the coronary artery using a coded aperture imaging system  

NASA Astrophysics Data System (ADS)

A coded aperture1 plate was employed on a conventional gamma camera for 3D single photon emission computed tomography (SPECT) imaging on small animal models. The coded aperture design was selected to improve the spatial resolution and decrease the minimum detectable activity (MDA) required to image plaque formation in the APoE (apolipoprotein E) gene deficient mouse model when compared to conventional SPECT techniques. The pattern that was tested was a no-two-holes-touching (NTHT) modified uniformly redundant array (MURA) having 1,920 pinholes. The number of pinholes combined with the thin sintered tungsten plate was designed to increase the efficiency of the imaging modality over conventional gamma camera imaging methods while improving spatial resolution and reducing noise in the image reconstruction. The MDA required to image the vulnerable plaque in a human cardiac-torso mathematical phantom was simulated with a Monte Carlo code and evaluated to determine the optimum plate thickness by a receiver operating characteristic (ROC) yielding the lowest possible MDA and highest area under the curve (AUC). A partial 3D expectation maximization (EM) reconstruction was developed to improve signal-to-noise ratio (SNR), dynamic range, and spatial resolution over the linear correlation method of reconstruction. This improvement was evaluated by imaging a mini hot rod phantom, simulating the dynamic range, and by performing a bone scan of the C-57 control mouse. Results of the experimental and simulated data as well as other plate designs were analyzed for use as a small animal and potentially human cardiac imaging modality for a radiopharmaceutical developed at Bristol-Myers Squibb Medical Imaging Company, North Billerica, MA, for diagnosing vulnerable plaques. If left untreated, these plaques may rupture causing sudden, unexpected coronary occlusion and death. The results of this research indicated that imaging and reconstructing with this new partial 3D algorithm improved the SNR, spatial resolution, dynamic range of 4:1 to 6:1, and decreased the MDA required at the site of a plaque by twofold in comparison with other nuclear medicine imaging methods. Recommendations to increase the field of view (FOV) along with a better imaging geometry would enable placement of larger objects (human heart included) within the fully encoded FOV while improving spatial resolution, magnification factors, and efficiency. Further improvements to the algorithm and imaging system may enable novel vulnerable plaque imaging and early detection of coronary artery disease. 1See definitions beginning on page xvii.

Tozian, Cynthia

245

Delayed tracheal rupture following thyroidectomy.  

PubMed

Thyroidectomy is a commonly performed, low-risk procedure. Tracheal perforation during thyroidectomy is rare, and delayed rupture of the trachea rarer still. We present the case of a patient who underwent total thyroidectomy secondary to Grave's disease who, on postoperative day 7, developed massive subcutaneous emphysema and respiratory distress. Surgical exploration revealed a rupture of the anterolateral tracheal wall at the level of the first tracheal ring. The defect was repaired primarily and the patient recovered uneventfully. The risk factors for and the management of this rare complication are discussed. PMID:18487029

Damrose, Edward J; Damrose, John F

2009-02-01

246

Is silica involved in neuritic (senile) plaque formation?  

Microsoft Academic Search

The agent responsible for inducing neuritic (senile) plaque formation in senile dementia of the Alzheimer's type and in the ageing non-demented brain is unknown. Other workers have detected a high concentration of silicon in the rims and cores of senile neuritic plaques. We have therefore looked at whether the reaction of brain tissue to silica particles resembles a neuritic plaque.

S. Reesl; B. Cragg

1983-01-01

247

Three-Dimensional Ultrasound Observation of Carotid Artery Plaque Ulceration  

Microsoft Academic Search

Background and Purpose—Carotid artery plaque ulceration is associated with an increased risk of cerebral embolism. However, because of the rather poor diagnostic quality of conventional 2-D ultrasound and angiography compared with the evaluation of pathological specimens, little information exists on the natural course of carotid plaque ulceration. Recently, the introduction of 3-D ultrasound has made reproducible investigation of plaque morphology

Ulf Schminke; Lillian Motsch; Lutz Hilker; Christof Kessler

248

In vivo imaging reveals sigmoidal growth kinetic of ?-amyloid plaques.  

PubMed

A major neuropathological hallmark of Alzheimer's disease is the deposition of amyloid plaques in the brains of affected individuals. Amyloid plaques mainly consist of fibrillar ?-amyloid, which is a cleavage product of the amyloid precursor protein. The amyloid-cascade-hypothesis postulates A? accumulation as the central event in initiating a toxic cascade leading to Alzheimer's disease pathology and, ultimately, loss of cognitive function. We studied the kinetics of ?-amyloid deposition in Tg2576 mice, which overexpress human amyloid precursor protein with the Swedish mutation. Utilizing long-term two-photon imaging we were able to observe the entire kinetics of plaque growth in vivo. Essentially, we observed that plaque growth follows a sigmoid-shaped curve comprising a cubic growth phase, followed by saturation. In contrast, plaque density kinetics exhibited an asymptotic progression. Taking into account the fact that a critical concentration of A? is required to seed new plaques, we can propose the following kinetic model of ?-amyloid deposition in vivo. In the early cubic phase, plaque growth is not limited by A? concentration and plaque density increases very fast. During the transition phase, plaque density stabilizes whereas plaque volume increases strongly reflecting a robust growth of the plaques. In the late asymptotic phase, A? peptide production becomes rate-limiting for plaque growth. In conclusion, the present study offers a direct link between in vitro and in vivo studies facilitating the translation of A?-lowering strategies from laboratory models to patients. PMID:24678659

Burgold, Steffen; Filser, Severin; Dorostkar, Mario M; Schmidt, Boris; Herms, Jochen

2014-01-01

249

Correlation of hemodynamic forces and atherosclerotic plaque components  

NASA Astrophysics Data System (ADS)

Local hemodynamic forces in atherosclerotic carotid arteries are thought to trigger cellular and molecular mechanisms that determine plaque vulnerability. Magnetic Resonance Imaging (MRI) has emerged as a powerful tool to characterize human carotid atherosclerotic plaque composition and morphology, and to identify plaque features shown to be key determinants of plaque vulnerability. Image-based computational fluid dynamics (CFD) has allowed researchers to obtain time-resolved wall shear stress (WSS) information for atherosclerotic carotid arteries. A deeper understanding of the mechanisms of initiation and progression of atherosclerosis can be obtained through the comparison of WSS and plaque composition. The aim of this study was to explore the hypothesis that intra-plaque hemorrhage, a feature associated with adverse outcomes and plaque progression, is more likely to occur in plaques with elevated WSS levels. We compared 2D representations of the WSS distribution and the amount of intra-plaque hemorrhage to determine relationships between WSS patterns and plaque vulnerability. We extracted WSS data to compare patterns between cases with and without hemorrhage. We found elevated values of WSS at regions where intra-plaque hemorrhage was detected, suggesting that WSS might be used as a marker for the risk of intra-plaque hemorrhage and subsequent complications.

Canton, Gádór; Chiu, Bernard; Yuan, Chun; Kerwin, William S.

2010-03-01

250

In vivo imaging reveals sigmoidal growth kinetic of ?-amyloid plaques  

PubMed Central

A major neuropathological hallmark of Alzheimer’s disease is the deposition of amyloid plaques in the brains of affected individuals. Amyloid plaques mainly consist of fibrillar ?-amyloid, which is a cleavage product of the amyloid precursor protein. The amyloid-cascade-hypothesis postulates A? accumulation as the central event in initiating a toxic cascade leading to Alzheimer’s disease pathology and, ultimately, loss of cognitive function. We studied the kinetics of ?-amyloid deposition in Tg2576 mice, which overexpress human amyloid precursor protein with the Swedish mutation. Utilizing long-term two-photon imaging we were able to observe the entire kinetics of plaque growth in vivo. Essentially, we observed that plaque growth follows a sigmoid-shaped curve comprising a cubic growth phase, followed by saturation. In contrast, plaque density kinetics exhibited an asymptotic progression. Taking into account the fact that a critical concentration of A? is required to seed new plaques, we can propose the following kinetic model of ?-amyloid deposition in vivo. In the early cubic phase, plaque growth is not limited by A? concentration and plaque density increases very fast. During the transition phase, plaque density stabilizes whereas plaque volume increases strongly reflecting a robust growth of the plaques. In the late asymptotic phase, A? peptide production becomes rate-limiting for plaque growth. In conclusion, the present study offers a direct link between in vitro and in vivo studies facilitating the translation of A?-lowering strategies from laboratory models to patients.

2014-01-01

251

Videocapillaroscopic Findings in the Microcirculation of the Psoriatic Plaque  

Microsoft Academic Search

Background: Videocapillaroscopy (VCP) is a method to study the morphology and dynamics of microcirculation, but information about capillaroscopic features of the psoriatic plaque is limited. Objective: To investigate the distribution, morphology and density of capillaries in lesional and perilesional skin of the psoriatic plaque. Methods: VCP of a well-delimited plaque of the trunk, arms or legs in 15 consecutive patients

Rossella De Angelis; Leonardo Bugatti; Patrizia Del Medico; Massimiliano Nicolini; Giorgio Filosa

2002-01-01

252

Intraplaque haemorrhages as the trigger of plaque vulnerability  

PubMed Central

Atherothrombosis remains one of the main causes of morbidity and mortality in the western countries. Human atherothrombotic disease begins early in life in relation to circulating lipid retention in the inner vascular wall. Risk factors enhance the progression towards clinical expression: dyslipidaemia, diabetes, smoking, hypertension, ageing, etc. The evolution from the initial lipid retention in the arterial wall to clinical events is a continuum of increasingly complex biological processes. Current strategies to fight the consequences of atherothrombosis are orientated either towards the promotion of a healthy life style1 and preventive treatment of risk factors, or towards late interventional strategies.2 Despite this therapeutic arsenal, the incidence of clinical events remains dramatically high,3 dependent, at least in part, on the increasing frequency of type 2 diabetes and ageing. But some medical treatments, focusing only on prevention of the metabolic risk, have failed to reduce cardiovascular mortality, thus illustrating that our understanding of the pathophysiology of human atherothrombosis leading to clinical events remain incomplete. New paradigms are now emerging which may give rise to novel experimental strategies to improve therapeutic efficacy and prediction of disease progression. Recent studies strengthen the concept that the intraplaque neovascularization and bleeding (Figure 1, upper panel) are events that could play a major role in plaque progression and leucocyte infiltration, and may also serve as a measure of risk for the development of future events. The recent advances in our understanding of IntraPlaque Hemorrhage as a critical event in triggering acute clinical events have important implications for clinical research and possibly future clinical practice. Figure 1Macroscopic view and schematic representation of the detrimental consequences of intraplaque haemorrhages on plaque biology and stability.

Michel, Jean-Baptiste; Virmani, Renu; Arbustini, Eloisa; Pasterkamp, Gerard

2011-01-01

253

Effect of Heating Method on Stress-Rupture Life.  

National Technical Information Service (NTIS)

The effect of radiant(furnace), resistance(electric current), burner(hot gas stream), and a combination of resistance and burner heating on intermediate time (100 to 300 hr) stress-rupture life and reduction of area was evaluated. All heating methods were...

P. T. Bizon F. D. Calfo

1977-01-01

254

Analyzing Single-Event Gate Ruptures In Power MOSFET's  

NASA Technical Reports Server (NTRS)

Susceptibilities of power metal-oxide/semiconductor field-effect transistors (MOSFET's) to single-event gate ruptures analyzed by exposing devices to beams of energetic bromine ions while applying appropriate bias voltages to source, gate, and drain terminals and measuring current flowing into or out of each terminal.

Zoutendyk, John A.

1993-01-01

255

Indocyanine Green Enables Near-Infrared Fluorescence Imaging of Lipid-Rich, Inflamed Atherosclerotic Plaques  

PubMed Central

New high-resolution molecular and structural imaging strategies are needed to visualize high-risk plaques that are likely to cause acute myocardial infarction, because current diagnostic methods do not reliably identify at-risk subjects. While molecular imaging agents are available for lower-resolution detection of atherosclerosis in large arteries, a lack of imaging agents coupled to high-resolution modalities has limited molecular imaging of atherosclerosis in the smaller coronary arteries [AU: ok? YES]. Here, we have demonstrated that indocyanine green (ICG), an FDA-approved near-infrared fluorescence (NIRF) emitting compound, targets atheromas within 20 minutes of injection and provides sufficient signal enhancement for in vivo detection of lipid-rich, inflamed, coronary-sized plaques in atherosclerotic rabbits. In vivo NIRF sensing was achieved with an intravascular wire in the aortae, a vessel of comparable caliber to human coronary arteries. Ex vivo fluorescence reflectance imaging studies showed high plaque target-to-background ratios in atheroma-bearing rabbits injected with ICG, compared to atheroma-bearing rabbits injected with saline. In vitro studies using human macrophages established that ICG preferentially targets lipid-loaded macrophages. In an early clinical study of human atheroma specimens from four patients, we found that ICG colocalized with plaque macrophages and lipids. The atheroma-targeting capability of ICG has the potential to accelerate the clinical development of NIRF molecular imaging of high-risk plaques in humans.

Vinegoni, Claudio; Botnaru, Ion; Aikawa, Elena; Calfon, Marcella A.; Iwamoto, Yoshiko; Folco, Eduardo J.; Ntziachristos, Vasilis; Weissleder, Ralph; Libby, Peter; Jaffer, Farouc A.

2011-01-01

256

An integrated approach for the mechanisms responsible for atherosclerotic plaque regression  

PubMed Central

Atherosclerosis was originally considered to be an ongoing process that was inevitably associated with age. However, plaques are highly dynamic, and are able to progress, stabilize or regress depending on their surrounding milieu. A great deal of research attention has been focused on understanding the involvement of high-density lipoprotein in atherosclerotic plaque regression. However, atherosclerotic plaque regression encompasses a variety of processes that can be grouped into three main areas: removal of lipids and necrotic material; restoration of endothelial function and repair of denuded areas; and cessation of vascular smooth muscle cell proliferation and phenotype reversal. In addition to the role of high-density lipoproteins in lipid removal, resident macrophages and foam cells are able to regain motility and rapidly migrate on milieu improvement, moving both lipids and necrotic material to regional lymph nodes. Neighbouring endothelial cells can proliferate and replace dead and dysfunctional cells. Circulating endothelial progenitor cells can similarly restore vessel function. Finally, abrogation of smooth muscle cell proliferation occurs secondarily to these processes. This information is integrated in the current article to present a comprehensive and clear depiction of plaque regression. This integrated view of regression is essential to optimize the pharmaceutical targeting of the many processes and pathways involved in plaque regression.

Francis, Andrew A; Pierce, Grant N

2011-01-01

257

The Effect of pH, Temperature and Plaque Thickness on the Hydrolysis of Monofluorophosphate in Experimental Dental Plaque  

Microsoft Academic Search

Monofluorophosphate (MFP), an anti-caries agent commonly used in toothpaste, is known to be degraded to fluoride and orthophosphate by bacterial phosphatases in dental plaque. We have examined the effect of pH, temperature, plaque thickness and some ions on this process. Both natural plaque and artificial microcosm plaque incubated with purified MFP at pH 4–10 showed an optimum pH of ?8

E. I. F. Pearce; G. H. Dibdin

2003-01-01

258

Simple Method for Plating Escherichia coli Bacteriophages Forming Very Small Plaques or No Plaques under Standard Conditions  

Microsoft Academic Search

The use of low concentrations (optimally 2.5 to 3.5 g\\/ml, depending on top agar thickness) of ampicillin in the bottom agar of the plate allows for formation of highly visible plaques of bacteriophages which otherwise form extremely small plaques or no plaques on Escherichia coli lawns. Using this method, we were able to obtain plaques of newly isolated bacteriophages, propagated

J. M. Los; Piotr Golec; G. Wegrzyn; A. Wegrzyn; M. Los

2008-01-01

259

Beyond Coronary Stenosis: Coronary Computed Tomographic Angiography for the Assessment of Atherosclerotic Plaque Burden  

PubMed Central

Coronary computed tomographic angiography (CCTA) is emerging as a key non-invasive method for assessing cardiovascular risk by measurement of coronary stenosis and coronary artery calcium (CAC). New advancements in CCTA technology have led to the ability to directly identify and quantify the so-called “vulnerable” plaques that have features of positive remodeling and low density components. In addition, CCTA presents a new opportunity for noninvasive measurement of total coronary plaque burden that has not previously been available. The use of CCTA needs also to be balanced by its risks and, in particular, the associated radiation exposure. We review current uses of CCTA, CCTA’s ability to measure plaque quantity and characteristics, and new developments in risk stratification and CCTA technology. CCTA represents a quickly developing field that will play a growing role in the non-invasive management of cardiovascular disease.

Kwan, Alan C; Cater, George; Vargas, Jose

2013-01-01

260

Comparison of Gadofluorine-M and Gd-DTPA for Non-Invasive Staging of Atherosclerotic Plaque Stability Using MRI  

PubMed Central

Background Inflammation and neovascularization play critical roles in the stability of atherosclerotic plaques. Whole-body quantitative assessment of these plaque features may improve patient risk-stratification for life-threatening thromboembolic events and direct appropriate intervention. Here we determined the utility of the MR contrast agent Gadofluorine-M (GdF) for staging plaque stability and compared this to the conventional agent Gd-DTPA. Methods and Results 5 control and 7 atherosclerotic rabbits were sequentially imaged following administration of Gd-DTPA (0.2 mmol/kg) and GdF (0.1 mmol/kg) using a T1-weighted pulse sequence on a 3T MRI scanner. Diseased aortic wall could be distinguished from normal wall based on wall-to-muscle contrast-to-noise values following GdF administration. RAM-11 (macrophages) and CD-31 (endothelial cells) immunostaining of MR-matched histological sections revealed that GdF accumulation was related to the degree of inflammation at the surface of plaques and the extent of core neovascularization. Importantly, an MR measure of GdF accumulation at both 1 and 24 hours post-injection, but not Gd-DTPA at peak enhancement, was shown to correlate with a quantitative histological morphology index related to these two plaque features. Conclusions GdF-enhanced MRI of atherosclerotic plaques allows non-invasive quantitative information about plaque composition to be acquired at multiple time points post-injection (within 1 and up to 24 hours post-injection). This dramatically widens the imaging window for assessing plaque stability that is currently attainable with clinically approved MR agents, therefore opening the possibility of whole-body (including coronary) detection of unstable plaques in the future and potentially improved mitigation of cataclysmic cardiovascular events.

Ronald, John A.; Chen, Yuanxin; Belisle, Andre J.-L.; Hamilton, Amanda M.; Rogers, Kem A.; Hegele, Robert A.; Misselwitz, Bernd; Rutt, Brian K.

2009-01-01

261

Quadriceps Tendon Rupture due to Postepileptic Convulsion  

PubMed Central

We present a case of quadriceps tendon (QT) rupture. QT ruptures can occur in all ages. The cause is mostly traumatic in origin. Spontaneous ruptures that are thought to result from predisposing conditions are rare. Post-convulsion QT ruptures lacking traumas in their history can be overlooked in clinical examinations. This should be born in mind by the attending physician, as early diagnosis and treatment of the condition can lead to satisfactory outcomes.

Erkut, Adem; Guvercin, Yilmaz; Sahin, Rifat; Keskin, Davut

2014-01-01

262

Spontaneous Splenic Rupture in Melanoma  

PubMed Central

Spontaneous rupture of spleen due to malignant melanoma is a rare situation, with only a few case reports in the literature. This study reports a previously healthy, 30-year-old man who came with chief complaint of acute abdominal pain to emergency room. On physical examination, abdominal tenderness and guarding were detected to be coincident with hypotension. Ultrasonography revealed mild splenomegaly with moderate free fluid in abdominopelvic cavity. Considering acute abdominal pain and hemodynamic instability, he underwent splenectomy with splenic rupture as the source of bleeding. Histologic examination showed diffuse infiltration by tumor. Immunohistochemical study (positive for S100, HMB45, and vimentin and negative for CK, CD10, CK20, CK7, CD30, LCA, EMA, and chromogranin) confirmed metastatic malignant melanoma. On further questioning, there was a past history of a nasal dark skin lesion which was removed two years ago with no pathologic examination. Spontaneous (nontraumatic) rupture of spleen is an uncommon situation and it happens very rarely due to neoplastic metastasis. Metastasis of malignant melanoma is one of the rare causes of the spontaneous rupture of spleen.

Oryan, Ahmad; Davari, Aida; Daneshbod, Khosrow; Daneshbod, Yahya

2014-01-01

263

Spontaneous rupture of a varicocoele.  

PubMed

We present the case of a young male with an acute scrotal haematoma due to spontaneous rupture of a spermatic cord varicocoele confirmed by Doppler ultrasonography. After failure of conservative management, surgical exploration was performed with successful evacuation of the scrotal haematoma. PMID:20441071

Chin, W N; Cadogan, M; Wan, R; Harrison, L

2009-11-01

264

Computerized Assessment of Carotid Plaque Echogenicity before Stenting.  

PubMed

Summary: To assess the ability of transcutaneous ultrasound (US) to identify carotid atherosclerotic plaques at high risk for development of procedural strokes, the authors retrospectively analyzed the plaque echomorphology by means of gray-scale value (GSV). Both transcutaneous and intravascular US demonstrated a similar ability to characterize the atherosclerotic plaques. A case with embolic complication was proven to have had the lowest GSV in the studied cases. With computerized assessment of plaque echogenicity, pre-procedural transcutaneous US may be used to predict plaques that are associated with a high risk of distal embolization. PMID:20663397

Takahata, H; Hayashi, K; Kitagawa, N; Kaminogo, M; Koga, H; Shibata, S

2001-12-22

265

Therapeutic strategies to deplete macrophages in atherosclerotic plaques  

PubMed Central

Macrophages can be found in all stages of atherosclerosis and are major contributors of atherosclerotic plaque development, progression and destabilization. Continuous recruitment of monocytes drives this chronic inflammatory disease, which can be intervened by several strategies: reducing the inflammatory stimulus by lowering circulating lipids and promoting cholesterol efflux from plaque, direct and indirect targeting of adhesion molecules and chemokines involved in monocyte adhesion and transmigration and inducing macrophage death in atherosclerotic plaques in combination with anti-inflammatory drugs. This review discusses the outlined strategies to deplete macrophages from atherosclerotic plaques to promote plaque stabilization.

De Meyer, Inge; Martinet, Wim; De Meyer, Guido R. Y.

2012-01-01

266

Atherosclerotic plaque characterization by spatial and temporal speckle pattern analysis  

NASA Astrophysics Data System (ADS)

Improved methods are needed to identify the vulnerable coronary plaques responsible for acute myocardial infraction or sudden cardiac death. We describe a method for characterizing the structure and biomechanical properties of atherosclerotic plaques based on speckle pattern fluctuations. Near-field speckle images were acquired from five human aortic specimens ex vivo. The speckle decorrelation time constant varied significantly for vulnerable aortic plaques (? = 40 ms) versus stable plaques (? = 400 ms) and normal aorta (? = 500 ms). These initial results indicate that different atherosclerotic plaque types may be distinguished by analysis of temporal and spatial speckle pattern fluctuations.

Tearney, Guillermo J.; Bouma, Brett E.

2002-04-01

267

Centrally-Rupturing Squib-Closure Disks  

NASA Technical Reports Server (NTRS)

Rupture-disk design makes squib action more predictable. In new design, center of rupture disk contains cruciform indentation in which thickness reduced to about 0.5 mil (0.013 mm). Reduces strength of center of rupture disk in same manner as that of pull tabs on beverage cans; therefore, disk will fail predictably in center.

Richter, R.

1986-01-01

268

46 CFR 64.61 - Rupture disc.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST...Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc is the only pressure relief device on the tank,...

2013-10-01

269

Conservative treatment for postintubation tracheobronchial rupture  

Microsoft Academic Search

Background. Postintubation tracheobronchial rupture is usually responsible for unstable intraoperative or postoperative conditions, and its management is discussed. We insist on conservative treatment as a viable alternative after late diagnosis of postintubation tracheobronchial rupture.Methods. We conducted a retrospective study including 14 consecutive patients treated between April 1981 and July 1998.Results. Twelve tracheobronchial ruptures occurred after intubation for general surgery and

Jacques Jougon; Michel Ballester; Emmanuel Choukroun; Jean Dubrez; Gilles Reboul; Jean-François Velly

2000-01-01

270

Predominant cultivable flora isolated from human root surface caries plaque.  

PubMed Central

Plaque samples were obtained from tooth surfaces exhibiting typical lesions of root surface caries and were immediately cultured by a continuous anaerobic procedure. The bacterial composition of root caries flora was determined on individual samples. Representative isolates from each specimen were characterized by morphological and physiological criteria. In addition, fluorescent antibody reagents were used to confirm the identification of Streptococcus mutans and Actinomyces viscosus. The plaque samples could be divided into two groups on the basis of the presence or absence of S. mutans in the plaque. In group I plaques, S. mutans comprised 30 percent of the total cultivable flora. S. sanguis was either not found or was present in very low number. In group II plaques, S. mutans was not detected, and S. sanguis formed 48 percent of the total plaque flora. A. viscosus was the dominant organism in all plaque samples, accounting for 47 percent of the group I isolates and 41 percent of the group II isolates.

Syed, S A; Loesche, W J; Pape, H L; grenier, E

1975-01-01

271

Plaque Production by Arboviruses in Singh's Aedes albopictus Cells  

PubMed Central

We report plaquing tests of 124 virus strains, mostly arboviruses of 21 serological groups, in Singh's line of Aedes albopictus cells. Thirty of these plaqued; all were arboviruses of six groups and were known or presumed to be mosquito borne. Failing to plaque were 86 strains of arboviruses, mostly tick borne, two strains of insect pathogens, and six animal viruses not classified as arboviruses. Among mosquito-borne agents, plaquing ability appeared related to serological classification. California group and most A-group viruses failed to plaque, but nearly all members of B and Bunyamwera groups readily plaqued. Within serological group B, 14 of 16 mosquito-borne agents plaqued, but none of 13 tick-borne or vector-unassociated viruses did so. Some implications of these results for recognition and classification of arboviruses are discussed. Images

Yunker, C. E.; Cory, J.

1975-01-01

272

Variable land-level changes at a non-persistent megathrust rupture boundary, Sitkinak Island, Alaska  

NASA Astrophysics Data System (ADS)

Fault-rupture segmentation models require paleoseismic data to validate inferred rupture boundaries. We examined the southwestern end of the 1964 Mw 9.2 rupture along the Alaska-Aleutian megathrust to test the prehistoric persistence of this historical rupture boundary. On Sitkinak Island in the Trinity Islands, 20 hand-collected cores and tidal outcrops beneath tidal and freshwater marshes reveal five abrupt lithologic contacts that record a mixed record of coseismic uplift (3 events) and subsidence (2 events) in the last ~1000 years. Diatom and foraminiferal assemblages in modern and core material obtained from the southwestern Sitkinak lagoon indicate rapid uplift ca. AD 1788 and just prior to 575 × 65 cal yr and 735 × 65 cal yr; and rapid subsidence in AD 1964 and soon after ~735 cal yr as constrained by 14C ages and tephra correlation. Because the northern coast of Sitkinak was reportedly uplifted in AD 1964 and the island is currently subsiding interseismically above a locked patch of the megathrust, we interpret coseismic subsidence as representing the along-strike transition from elastic uplift to subsidence at the rupture boundary; this implies that the AD 1964 zero uplift isobase crosses the island. Similar behavior has been observed during large megathrust ruptures in Indonesia and the Solomon Islands and is predicted by elastic dislocation models. A sand bed traced inland 1.5 km and bracketed with 14C, 137Cs, and 210Pb ages was most likely deposited by a tsunami associated with megathrust rupture in 1788. Historical records suggest that the AD 1788 rupture extended from the southwest at least 100 km northeast to the Russian settlement at Three Saints Bay near Old Harbor, Kodiak Island. The complicated uplift and subsidence record we observe on Sitkinak Island, interpreted in the context of historical reports of the AD 1788 rupture, is consistent with at least three rupture segmentation models. In Model A, Sitkinak is located at a boundary for 1964- and 1788-type ruptures. A complication with Model A is that it requires 1788-type ruptures to extend at least 100 km into the AD 1964 rupture area. Model B assumes coseismic uplift for large megathrust events on Sitkinak, with subsidence accompanying only updip ruptures or upper-plate deformation. Model B is inconsistent with the observation of coseismic subsidence of the southwestern lagoon in AD 1964. At present we prefer Model C, where megathrust ruptures end or continue near Sitkinak in a complex, and as yet undetermined, pattern. An implication of our field evidence is that seismic hazard models should relax the assumption that the AD 1964 rupture endpoint is persistent.

Briggs, R. W.; Engelhart, S. E.; Nelson, A. R.; Kemp, A.; Haeussler, P. J.; Dura, T.

2013-12-01

273

Simple Method for Plating Escherichia coli Bacteriophages Forming Very Small Plaques or No Plaques under Standard Conditions ?  

PubMed Central

The use of low concentrations (optimally 2.5 to 3.5 ?g/ml, depending on top agar thickness) of ampicillin in the bottom agar of the plate allows for formation of highly visible plaques of bacteriophages which otherwise form extremely small plaques or no plaques on Escherichia coli lawns. Using this method, we were able to obtain plaques of newly isolated bacteriophages, propagated after induction of prophages present in six E. coli O157:H? strains which did not form plaques when standard plating procedures were employed.

Los, Joanna M.; Golec, Piotr; Wegrzyn, Grzegorz; Wegrzyn, Alicja; Los, Marcin

2008-01-01

274

Simple method for plating Escherichia coli bacteriophages forming very small plaques or no plaques under standard conditions.  

PubMed

The use of low concentrations (optimally 2.5 to 3.5 microg/ml, depending on top agar thickness) of ampicillin in the bottom agar of the plate allows for formation of highly visible plaques of bacteriophages which otherwise form extremely small plaques or no plaques on Escherichia coli lawns. Using this method, we were able to obtain plaques of newly isolated bacteriophages, propagated after induction of prophages present in six E. coli O157:H(-) strains which did not form plaques when standard plating procedures were employed. PMID:18586961

Lo?, Joanna M; Golec, Piotr; Wegrzyn, Grzegorz; Wegrzyn, Alicja; Lo?, Marcin

2008-08-01

275

Thrombogenesis of the Rabbit Arterial Plaque  

PubMed Central

Rabbit arteries, de-endothelialized with an intravascular balloon catheter and allowed to heal for 4 weeks, showed intimal changes that were similar to the preatherosclerotic fibromusculoelastic plaques of man. Reinjury of the healed vessels by balloon catheter produced marked quantitative and qualitative alterations of hemostasis, as compared to that in previously uninjured vessels. The most apparent modification of thrombogenesis 10 minutes after injury to the plaque was a large increase in the size of the thrombotic deposits. Features of this exaggerated response were the major participation of fibrin in thrombus formation and greater platelet accumulation. Some platelets and fibrin strands appeared to penetrate into and beneath the neointima. By 3 hours, these deposits had diminished in size, although the hemostatic mass remained larger in the doubly injured vessels. ImagesFig 9Fig 3Fig 4Fig 5Fig 10Fig 6Fig 7Fig 1Fig 8Fig 2

Stemerman, Michael B.

1973-01-01

276

[Pruritic urticarial papules and plaques in pregnancy].  

PubMed

PUPP is a specific eruptive dermatosis in pregnancy, clinically characterized by erythematous papules and plaques with intense itching in periumbilical localization. This disease typically tends to spread to the extremities without involving the head and neck regions. The differential diagnosis of PUPP can be established by immunological and microscopical investigations. Since PUPP is a benign disease with a good prognosis and spontaneous clearing, we recommend only mild symptomatic treatment. PMID:2264374

Füzesi, S; Antal, I; Petres, J

1990-09-01

277

Earliest Known Roman London Plaque Discovered  

NSDL National Science Digital Library

Earlier today, archaeologists working on a massive dig on the southern banks of the River Thames uncovered the oldest known plaque inscribed with the city's Roman name, Londinium. While the exact date of the plaque is unknown, it is believed to date from between 50 and 150 AD, and would most likely have been placed on some type of building or in a shrine. Equally important, the plaque offers some initial concrete evidence that there was an emerging merchant class in London during this period. The actual location of the plaque's discovery is near the junction of what were three key roads in Roman Britain, and the finding represents only a small portion of what may be unearthed in this 40-week archaeology project.The first link is to a recent news story about the recent find in London. The second site leads to the Council for British Archaeology, which features numerous links to ongoing research projects within Britain and frequent updates about new findings from the field. The third site offers some perspective on the historical notion of Roman Britain, and particularly how scholars understand that epoch. The fourth site is a link to the complete work "Roman Roads in Britain," a historical study that seeks to describe and delineate the exact location of these very important Roman pathways. Information about the Museum of London, which is working jointly on this project, is provided by the fifth link. The last link, Britannia, is a nice omnibus listing of sites dealing with various aspects of Roman Britain history and archaeology, provided by the Dalton School in New York.

Grinnell, Max

2002-01-01

278

Traumatic rupture of horseshoe kidney.  

PubMed

We present the case of a 25-year-old male who came to the emergency room for pain and abdominal distension following trauma to the mesogastrium. A CT scan was performed, revealing a voluminous retroperitoneal hematoma with laceration of both inferior renal poles with regard to rupture of the isthmus of a horseshoe kidney. The patient presented anemization and increased pain, requiring selective embolization by means of arteriography of a branch of the right renal artery and placement of a double J stent due to urinary extravasation in the lower left kidney pole. Following 1 year of monitoring, the patient has maintained normal renal function. Renal affection in blunt abdominal trauma is frequent, occurring in 7% of previously pathological kidneys. The traumatic rupture of horseshoe kidney is facilitated by its particular anatomical characteristics, constituting an infrequent entity, knowledge of which is necessary to achieve conservative management that renders it possible to preserve renal function. PMID:21934278

Molina Escudero, R; Cancho Gil, M J; Husillos Alonso, A; Lledó García, E; Herranz Amo, F; Ogaya Piniés, G; Ramón Botella, E; Simó, G; Navas Martínez, M C; Hernández Fernández, C

2012-01-01

279

Bacteriology of Human Experimental Gingivitis: Effect of Plaque Age  

PubMed Central

Twenty-five subjects with previously excellent hygiene and healthy gingiva developed heavy plaque accumulations and bleeding or nonbleeding gingivitis about certain papilla after 21 days of no oral hygiene. Gingival marginal plaque about a single papilla was collected at 0, 1, 2, and 3 weeks of no oral hygiene in each subject. The plaque was dispersed, serially diluted, and plated on MM10 sucrose agar in an oxygen-free atmosphere. From 50 to 100 colonies from a single high-dilution plate were characterized for each sample. Over 8,500 isolates were partially characterized and placed into one of 29 taxonomic species or groups. The flora was predominantly gram-positive at all time periods. Streptococcal species dominated in the 0- and 1-week-old plaques, i.e. 62 and 43% of the colonyforming units (CFU), but dropped to 26 to 32% of the CFU in the 2- and 3-week-old plaques. Actinomyces species dominated in the older plaques, i.e., 40 to 50% of the CFU. Actinomyces israelii was the most prominent species in the older plaques. Veillonella accounted for 15 to 20% of the CFU at all time periods. Although the other gram-negative species increased with time, collectively they averaged less than 5% of the CFU at week 3. The shift from a Streptococcus-dominated plaque to an Actinomyces-dominated plaque was the most striking microbial change observed as the plaque aged.

Syed, S. A.; Loesche, W. J.

1978-01-01

280

Bacteriology of human experimental gingivitis: effect of plaque age.  

PubMed

Twenty-five subjects with previously excellent hygiene and healthy gingiva developed heavy plaque accumulations and bleeding or nonbleeding gingivitis about certain papilla after 21 days of no oral hygiene. Gingival marginal plaque about a single papilla was collected at 0, 1, 2, and 3 weeks of no oral hygiene in each subject. The plaque was dispersed, serially diluted, and plated on MM10 sucrose agar in an oxygen-free atmosphere. From 50 to 100 colonies from a single high-dilution plate were characterized for each sample. Over 8,500 isolates were partially characterized and placed into one of 29 taxonomic species or groups. The flora was predominantly gram-positive at all time periods. Streptococcal species dominated in the 0- and 1-week-old plaques, i.e. 62 and 43% of the colonyforming units (CFU), but dropped to 26 to 32% of the CFU in the 2- and 3-week-old plaques. Actinomyces species dominated in the older plaques, i.e., 40 to 50% of the CFU. Actinomyces israelii was the most prominent species in the older plaques. Veillonella accounted for 15 to 20% of the CFU at all time periods. Although the other gram-negative species increased with time, collectively they averaged less than 5% of the CFU at week 3. The shift from a Streptococcus-dominated plaque to an Actinomyces-dominated plaque was the most striking microbial change observed as the plaque aged. PMID:711336

Syed, S A; Loesche, W J

1978-09-01

281

Splenic rupture following endoscopic polypectomy.  

PubMed

A 70-year-old man presented with two medium-sized colon polyps at the office of a gastroenterologist. After endoscopic polypectomy in a hospital, the patient was admitted to another hospital because of collapse and increasing abdominal pain. CT scan revealed hematoperitoneum and splenic subcapsular hematoma. Laparotomy with splenectomy was performed because of extended splenic rupture. The postoperative course was unremarkable except late wound dehiscence. PMID:20352593

Wiedmann, M W; Kater, F; Böhm, B

2010-04-01

282

Achilles tendon rupture in badminton.  

PubMed Central

The typical badminton player with an Achilles tendon rupture is 36 years old and, despite limbering up, is injured at the rear line in a sudden forward movement. He resumes work within three months and has a slight lack of dorsiflexion in the ankle as the main complication. Most patients resume badminton within one year, but some finish their sports career, mainly due to fear of a new injury. The investigation discusses predisposing factors and prophylactic measures.

Kaalund, S; Lass, P; H?gsaa, B; N?hr, M

1989-01-01

283

Molecular dynamics of interface rupture  

NASA Technical Reports Server (NTRS)

Several situations have been studied in which a fluid-vapor or fluid-fluid interface ruptures, using molecular dynamics simulations of 3000 to 20,000 Lennard-Jones molecules in three dimensions. The cases studied are the Rayleigh instability of a liquid thread, the burst of a liquid drop immersed in a second liquid undergoing shear, and the rupture of a liquid sheet in an extensional flow. The late stages of the rupture process involve the gradual withdrawal of molecules from a thinning neck, or the appearance and growth of holes in a sheet. In all cases, it is found that despite the small size of the systems studied, tens of angstroms, the dynamics is in at least qualitative accord with the behavior expected from continuum calculations, and in some cases the agreement is to within tens of percent. Remarkably, this agreement occurs even though the Eulerian velocity and stress fields are essentially unmeasurable - dominated by thermal noise. The limitations and prospects for such molecular simulation techniques are assessed.

Koplik, Joel; Banavar, Jayanth R.

1993-01-01

284

CT of blunt diaphragmatic rupture.  

PubMed

The diagnosis of blunt diaphragmatic rupture (BDR) is difficult and often missed, leaving many patients with this traumatic injury at risk for life-threatening complications. The potential diagnostic pitfalls are numerous and include anatomic variants and congenital and acquired abnormalities. Chest radiography, despite its known limitations, may still be helpful in the early assessment of severe thoracoabdominal trauma and for detecting initially overlooked BDR or late complications of BDR. However, since the development of helical and multidetector scanners, computed tomography (CT) has become the reference standard; thus, knowledge of the CT signs suggestive of BDR is important for recognition of this injury pattern. A large number of CT signs of BDR have been described elsewhere, many of them individually, but the use of various appellations for the same sign can make previously published reports confusing. The systematic description and classification of CT signs provided in this article may help clarify matters and provide clues for diagnosing BDR. The authors describe 19 distinct CT signs grouped in three categories: direct signs of rupture, indirect signs that are consequences of rupture, and signs that are of uncertain origin. Since no single CT sign can be considered a marker leading to a correct diagnosis in every case of BDR, accurate diagnosis depends on the analysis of all signs present. PMID:22411944

Desir, Amandine; Ghaye, Benoît

2012-01-01

285

Quantification of human atherosclerotic plaques using spatially enhanced cluster analysis of multicontrast-weighted magnetic resonance images.  

PubMed

One of the current limitations of magnetic resonance imaging (MRI) is the lack of an objective method to classify plaque components. Here we present a cluster analysis technique that can objectively quantify and classify MR images of atherosclerotic plaques. We obtained three-dimensional (3D) images from 12 human coronary artery specimens on a 9.4T imaging system using multicontrast-weighted fast spin-echo (T1-, proton density-, and T2-weighted) imaging with an isotropic voxel size of 39 micro. Spatially enhanced cluster analysis (SECA) was performed on multicontrast MR images, and the resulting segmentation was evaluated against histological tracings. To visualize the overall structure of plaques, the MR images were rendered in 3D. The specimens exhibited lesions of American Heart Association (AHA) plaque classification types I-VI. Both MR images and histological sections were independently reviewed, categorized, and compared. Overall, the classification obtained from the cluster-analyzed MR and histopathology images showed very good agreement for all AHA types (92%, Cohen's kappa = 0.89, P < 0.0001). All plaque types were identified and quantified by SECA with a high degree of correlation between cluster-analyzed MR and manually traced histopathology data. MRI combined with SECA provides an objective method for atherosclerotic plaque component characterization and quantification. PMID:15334569

Itskovich, Vitalii V; Samber, Daniel D; Mani, Venkatesh; Aguinaldo, Juan Gilberto S; Fallon, John T; Tang, Cheuk Y; Fuster, Valentin; Fayad, Zahi A

2004-09-01

286

PLACD-7T Study: Atherosclerotic Carotid Plaque Components Correlated with Cerebral Damage at 7 Tesla Magnetic Resonance Imaging  

PubMed Central

Introduction: In patients with carotid artery stenosis histological plaque composition is associated with plaque stability and with presenting symptomatology. Preferentially, plaque vulnerability should be taken into account in pre-operative work-up of patients with severe carotid artery stenosis. However, currently no appropriate and conclusive (non-) invasive technique to differentiate between the high and low risk carotid artery plaque in vivo is available. We propose that 7 Tesla human high resolution MRI scanning will visualize carotid plaque characteristics more precisely and will enable correlation of these specific components with cerebral damage. Study objective: The aim of the PlaCD-7T study is 1: to correlate 7T imaging with carotid plaque histology (gold standard); and 2: to correlate plaque characteristics with cerebral damage ((clinically silent) cerebral (micro) infarcts or bleeds) on 7 Tesla high resolution (HR) MRI. Design: We propose a single center prospective study for either symptomatic or asymptomatic patients with haemodynamic significant (70%) stenosis of at least one of the carotid arteries. The Athero-Express (AE) biobank histological analysis will be derived according to standard protocol. Patients included in the AE and our prospective study will undergo a pre-operative 7 Tesla HR-MRI scan of both the head and neck area. Discussion: We hypothesize that the 7 Tesla MRI scanner will allow early identification of high risk carotid plaques being associated with micro infarcted cerebral areas, and will thus be able to identify patients with a high risk of periprocedural stroke, by identification of surrogate measures of increased cardiovascular risk.

den Hartog, A.G; Bovens, S.M; Koning, W; Hendrikse, J; Pasterkamp, G; Moll, F.L; de Borst, G.J

2011-01-01

287

The comparative effect of acidified sodium chlorite and chlorhexidine mouthrinses on plaque regrowth and salivary bacterial counts.  

PubMed

Acidified sodium chlorite (ASC) is recognised as a highly potent, broad spectrum antimicrobial system that has been successfully developed for uses in veterinary, food processing and medical device fields. The current studies aimed to investigate the persistence of antimicrobial action and plaque inhibitory properties of 3 ASC mouthrinses by comparison with positive control, chlorhexidine 0.12%, and placebo control, water, rinses. Both studies were randomised, double-blind, cross-over 5-cell designs balanced for carryover. The 1st study involved 15 healthy subjects who immediately before and at 30, 60, 180, 300 and 420 min after rinsing provided 2 ml saliva samples. The samples were immediately processed for total anaerobic bacterial counts recorded after 96 h incubation. Washout periods were a minimum of 3 days. The second study involved 20 healthy subjects who on day 1 of each study were rendered plaque free, suspended normal oral hygiene methods and commenced rinsing twice daily with the allocated rinse. On day 5, plaque was scored by index and area after disclosing with erythrosin. Washout periods were 2 1/2 days. The 3 ASC and chlorhexidine rinses produced similar reductions in salivary bacterial counts which remained significantly below the placebo control to 7 h. There were no significant differences between ASC and chlorhexidine rinses except at 30 and 60 min when significantly greater reductions were produced by 2 ASC rinses compared to the chlorhexidine rinse. Plaque indices and areas were considerably and significantly lower with the ASC and chlorhexidine rinses compared to the placebo rinse. There were no significant differences between plaque scores for the 3 ASC rinses and the chlorhexidine rinse, although for 2 ASC rinses plaque scores were lower than for the chlorhexidine rinse. The results indicate that the 3 ASC rinses have equivalent plaque inhibitory action to chlorhexidine as a rinse. Similar to chlorhexidine, the plaque inhibitory action of the rinses appears to be derived from a persistence of antimicrobial action in the mouth. PMID:9378830

Yates, R; Moran, J; Addy, M; Mullan, P J; Wade, W G; Newcombe, R

1997-09-01

288

T-Cell Activation Leads to Reduced Collagen Maturation in Atherosclerotic Plaques of Apoe?/? Mice  

PubMed Central

Rupture of the collagenous, fibrous cap of an atherosclerotic plaque commonly causes thrombosis. Activated immune cells can secrete mediators that jeopardize the integrity of the fibrous cap. This study aimed to determine the relationship between T-cell-mediated inflammation and collagen turnover in a mouse model of experimental atherosclerosis. Both Apoe?/? × CD4dnT?RII mice with defective transforming growth factor-? receptors in T cells (and hence released from tonic suppression of T-cell activation) and lesion size-matched Apoe?/? mice were used. Picrosirius red staining showed a lower content of thick mature collagen fibers in lesions of Apoe?/? × CD4dnT?RII mice, although both groups had similar levels of procollagen type I or III mRNA and total collagen content in lesions. Analysis of both gene expression and protein content showed a significant decrease of lysyl oxidase, the extracellular enzyme needed for collagen cross-linking, in aortas of Apoe?/? ? CD4dnT?RII mice. T-cell-driven inflammation provoked a selective and limited increase in the expression of proteinases that catabolize the extracellular matrix. Atheromata of Apoe?/? ? CD4dnT?RII mice had increased levels of matrix metalloproteinase-13 and cathepsin S mRNAs and of the active form of cathepsin S protein but no increase was detected in collagen fragmentation. Our results suggest that exaggerated T-cell-driven inflammation limits collagen maturation in the atherosclerotic plaque while having little effect on collagen degradation.

Ovchinnikova, Olga; Robertson, Anna-Karin L.; Wagsater, Dick; Folco, Eduardo J.; Hyry, Marjo; Myllyharju, Johanna; Eriksson, Per; Libby, Peter; Hansson, Goran K.

2009-01-01

289

Multimodality imaging of carotid atherosclerotic plaque: Going beyond stenosis  

PubMed Central

Apart from the degree of stenosis, the morphology of carotid atherosclerotic plaques and presence of neovascularization are important factors that may help to evaluate the risk and ‘vulnerability’ of plaques and may also influence the choice of treatment. In this article, we aim to describe the techniques and imaging findings on CTA, high resolution MRI and contrast enhanced ultrasound in the evaluation of carotid atherosclerotic plaques. We also discuss a few representative cases from our institute with the related clinical implications.

Hingwala, Divyata; Kesavadas, Chandrasekharan; Sylaja, Padmavathy N; Thomas, Bejoy; Kapilamoorthy, Tirur Raman

2013-01-01

290

Diabetes Adversely Affects Macrophages During Atherosclerotic Plaque Regression in Mice  

PubMed Central

OBJECTIVE Patients with diabetes have increased cardiovascular risk. Atherosclerosis in these patients is often associated with increased plaque macrophages and dyslipidemia. We hypothesized that diabetic atherosclerosis involves processes that impair favorable effects of lipid reduction on plaque macrophages. RESEARCH DESIGN AND METHODS Reversa mice are LDL receptor–deficient mice that develop atherosclerosis. Their elevated plasma LDL levels are lowered after conditional knockout of the gene encoding microsomal triglyceride transfer protein. We examined the morphologic and molecular changes in atherosclerotic plaques in control and streptozotocin-induced diabetic Reversa mice after LDL lowering. Bone marrow–derived macrophages were also used to study changes mediated by hyperglycemia. RESULTS Reversa mice were fed a western diet for 16 weeks to develop plaques (baseline). Four weeks after lipid normalization, control (nondiabetic) mice had reduced plasma cholesterol (?77%), plaque cholesterol (?53%), and plaque cells positive for macrophage marker CD68+ (?73%), but increased plaque collagen (+116%) compared with baseline mice. Diabetic mice had similarly reduced plasma cholesterol, but collagen content increased by only 34% compared with baseline; compared with control mice, there were lower reductions in plaque cholesterol (?30%) and CD68+ cells (?41%). Diabetic (vs. control) plaque CD68+ cells also exhibited more oxidant stress and inflammatory gene expression and less polarization toward the anti-inflammatory M2 macrophage state. Many of the findings in vivo were recapitulated by hyperglycemia in mouse bone marrow–derived macrophages. CONCLUSIONS Diabetes hindered plaque regression in atherosclerotic mice (based on CD68+ plaque content) and favorable changes in plaque macrophage characteristics after the reduction of elevated plasma LDL.

Parathath, Saj; Grauer, Lisa; Huang, Li-Shin; Sanson, Marie; Distel, Emilie; Goldberg, Ira J.; Fisher, Edward A.

2011-01-01

291

Gene expression profiles in the Peyronie’s disease plaque  

Microsoft Academic Search

Objectives. To provide molecular insight into the pathophysiology of Peyronie’s disease (PD), a preliminary profile of differential gene expression between the PD plaque and control tunica albuginea was obtained with DNA microarrays.Methods. Seven PD plaques and five control tunica albugineas were studied. cDNA specimens were prepared from RNA isolated from one calcified PD plaque and one control tissue and hybridized

Thomas R Magee; Ansha Qian; Jacob Rajfer; Fred C Sander; Laurence A Levine; Nestor F Gonzalez-Cadavid

2002-01-01

292

Dosimetric Benefit of a New Ophthalmic Radiation Plaque  

SciTech Connect

Purpose: To determine whether the computed dosimetry of a new ophthalmic plaque, EP917, when compared with the standard Collaborative Ocular Melanoma Study (COMS) plaques, could reduce radiation exposure to vision critical structures of the eye. Methods and Materials: One hundred consecutive patients with uveal melanoma treated with COMS radiation plaques between 2007 and 2010 were included in this study. These treatment plans were generated with the use of Bebig Plaque Simulator treatment-planning software, both for COMS plaques and for EP917 plaques using I-125. Dose distributions were calculated for a prescription of 85 Gy to the tumor apex. Doses to the optic disc, opposite retina, lens, and macula were obtained, and differences between the 2 groups were analyzed by standard parametric methods. Results: When compared with the COMS plaques, the EP917 plaques used fewer radiation seeds by an average difference of 1.94 (P<.001; 95% confidence interval [CI], -2.8 to -1.06) and required less total strength of radiation sources by an average of 17.74 U (air kerma units) (P<.001; 95% CI, -20.16 to -15.32). The total radiation doses delivered to the optic disc, opposite retina, and macula were significantly less by 4.57 Gy, 0.50 Gy, and 11.18 Gy, respectively, with the EP917 plaques vs the COMS plaques. Conclusion: EP917 plaques deliver less overall radiation exposure to critical vision structures than COMS treatment plaques while still delivering the same total therapeutic dose to the tumor.

Marwaha, Gaurav, E-mail: marwahg2@ccf.org [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States) [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States); Cleveland Clinic Foundation, Cleveland, Ohio (United States); Wilkinson, Allan [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States) [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States); Cleveland Clinic Foundation, Cleveland, Ohio (United States); Bena, James [Department of Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, Ohio (United States) [Department of Quantitative Health Sciences, Cleveland Clinic Foundation, Cleveland, Ohio (United States); Cleveland Clinic Foundation, Cleveland, Ohio (United States); Macklis, Roger [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States) [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States); Cleveland Clinic Foundation, Cleveland, Ohio (United States); Singh, Arun D. [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States) [Department of Radiation Oncology, Taussig Cancer Center, Cleveland Clinic Foundation, Cleveland, Ohio (United States); Department of Ophthalmic Oncology, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio (United States); Cleveland Clinic Foundation, Cleveland, Ohio (United States)

2012-12-01

293

[Plaque surgery for Peyronie's disease: heterologous grafts].  

PubMed

Surgical treatment of Induratio Penis Plastica includes conservative procedures (phalloplasty), substitutive procedures (prosthesis) and combined procedures (phalloplasty plus prosthesis). Our policy for conservative treatment is based on radical removal of the plaque and replacement with biological patches. During a 15 year experience we employed lyophilized dura mater, autologous dermal graft, preputial skin, cadaveric dermal graft (AlloDerm), venous graft and porcine SIS (Small Intestine Submucosa) graft. Our experience confirms the superiority of venous grafts, but preliminary results with SIS grafts are encouraging. PMID:12868152

Paradiso, Matteo; Sedigh, Omid; Milan, Gian Luca

2003-06-01

294

Plaque inhibition by hexetidine and zinc.  

PubMed

Rinsing experiments with mouthwashes containing zinc ions, hexetidine and a combination of hexetidine and zinc ions were performed with a group of 10 volunteers. The amount of plaque was assessed after rinsing with the test solutions for 4 days during which mechanical toothcleaning was discontinued. Significantly improved inhibition was observed by the combination of hexetidine and zinc ions compared with the two agents used separately. In vitro bacteriological tests showed that hexetidine and zinc ions had a synergistic inhibitory effect on the growth of Streptococcus mutans. PMID:3470899

Giertsen, E; Svatun, B; Saxton, A

1987-02-01

295

Dynamics of plaque formation in Alzheimer's disease.  

PubMed Central

Plaques that form in the brains of Alzheimer patients are made of deposits of the amyloid-beta peptide. We analyze the time evolution of amyloid-beta deposition in immunostained brain slices from transgenic mice. We find that amyloid-beta deposits appear in clusters whose characteristic size increases from 14 microm in 8-month-old mice to 22 microm in 12-month-old mice. We show that the clustering has implications for the biological growth of amyloid-beta by presenting a growth model that accounts for the experimentally observed structure of individual deposits and predicts the formation of clusters of deposits and their time evolution.

Urbanc, B; Cruz, L; Buldyrev, S V; Havlin, S; Irizarry, M C; Stanley, H E; Hyman, B T

1999-01-01

296

Effectiveness of Veadent as a plaque-inhibiting mouthwash.  

PubMed

The aim of this study was to compare the effect of the commercially available Veadent mouthwash and chlorhexidine on plaque formation. Plaque accumulating during two 5-day periods was recorded in a group of 10 students. During the experimental periods, the test subjects abstained from mechanical cleaning of the teeth, and chewed sucrose-containing chewing gum every 4th h in order to enhance plaque formation. They also rinsed with either chlorhexidine or Veadent twice a day according to the manufacturer's recommendations. Chlorhexidine mouthrinses resulted in significantly lower plaque scores than did Veadent in the present short-term model study. PMID:3912956

Abbas, D K; Thrane, P; Othman, S J

1985-12-01

297

The rupture process of the 2002 Alaska earthquake  

NASA Astrophysics Data System (ADS)

The 2002 Alaska earthquake (Mw=7.9) is one of the largest strike-slip earthquakes in recent history. Seismic waveforms recorded at teleseismic distances show evidence for a complex rupture history, with substantial high-frequency energy. We have carried out preliminary inversions of teleseismic body and surface waves to model the slip distribution and time-history of this event. The earthquake can be divied into two parts, an initial thrusting event followed by a strike-slip part. Although the P waves for the initial thrust event are very prominent, the contribution of the thrust mechanism accounts for about 30% of the total moment release. The main slip distribution on the strike-slip fault in our model starts more than 100 km east-south-east of the epicenter, and extends over a length of more than 200 km. The slip distribution shows a strong heterogeneity, with maximum slip of 12 meters, and is consistent with the observed fault offsets. From the body waves, we find that the rise-times are generally short, and the rupture velocity on the order of 3.5 km/sec, or even more. In the light of recent observations on anomalous rupture propagation during the 1999 Kocaeli earthquake, we are currently investigating the possible occurrence of high rupture velocities during this earthquake, or the triggering of the strike-slip segment by P waves arriving from the hypocenter.

Thio, H. K.

2003-04-01

298

Optimal parameters for near infrared fluorescence imaging of amyloid plaques in Alzheimer's disease mouse models  

NASA Astrophysics Data System (ADS)

Amyloid-? plaques are an Alzheimer's disease biomarker which present unique challenges for near-infrared fluorescence tomography because of size (<50 µm diameter) and distribution. We used high-resolution simulations of fluorescence in a digital Alzheimer's disease mouse model to investigate the optimal fluorophore and imaging parameters for near-infrared fluorescence tomography of amyloid plaques. Fluorescence was simulated for amyloid-targeted probes with emission at 630 and 800 nm, plaque-to-background ratios from 1-1000, amyloid burden from 0-10%, and for transmission and reflection measurement geometries. Fluorophores with high plaque-to-background contrast ratios and 800 nm emission performed significantly better than current amyloid imaging probes. We tested idealized fluorophores in transmission and full-angle tomographic measurement schemes (900 source-detector pairs), with and without anatomical priors. Transmission reconstructions demonstrated strong linear correlation with increasing amyloid burden, but underestimated fluorescence yield and suffered from localization artifacts. Full-angle measurements did not improve upon the transmission reconstruction qualitatively or in semi-quantitative measures of accuracy; anatomical and initial-value priors did improve reconstruction localization and accuracy for both transmission and full-angle schemes. Region-based reconstructions, in which the unknowns were reduced to a few distinct anatomical regions, produced highly accurate yield estimates for cortex, hippocampus and brain regions, even with a reduced number of measurements (144 source-detector pairs).

Raymond, S. B.; Kumar, A. T. N.; Boas, D. A.; Bacskai, B. J.

2009-10-01

299

The development and potential of acoustic radiation force impulse (ARFI) imaging for carotid artery plaque characterization.  

PubMed

Stroke is the third leading cause of death and long-term disability in the USA. Currently, surgical intervention decisions in asymptomatic patients are based upon the degree of carotid artery stenosis. While there is a clear benefit of endarterectomy for patients with severe (> 70%) stenosis, in those with high/moderate (50-69%) stenosis the evidence is less clear. Evidence suggests ischemic stroke is associated less with calcified and fibrous plaques than with those containing softer tissue, especially when accompanied by a thin fibrous cap. A reliable mechanism for the identification of individuals with atherosclerotic plaques which confer the highest risk for stroke is fundamental to the selection of patients for vascular interventions. Acoustic radiation force impulse (ARFI) imaging is a new ultrasonic-based imaging method that characterizes the mechanical properties of tissue by measuring displacement resulting from the application of acoustic radiation force. These displacements provide information about the local stiffness of tissue and can differentiate between soft and hard areas. Because arterial walls, soft tissue, atheromas, and calcifications have a wide range in their stiffness properties, they represent excellent candidates for ARFI imaging. We present information from early phantom experiments and excised human limb studies to in vivo carotid artery scans and provide evidence for the ability of ARFI to provide high-quality images which highlight mechanical differences in tissue stiffness not readily apparent in matched B-mode images. This allows ARFI to identify soft from hard plaques and differentiate characteristics associated with plaque vulnerability or stability. PMID:21447606

Allen, Jason D; Ham, Katherine L; Dumont, Douglas M; Sileshi, Bantayehu; Trahey, Gregg E; Dahl, Jeremy J

2011-08-01

300

Increased brain iron coincides with early plaque formation in a mouse model of Alzheimer's disease  

PubMed Central

Elevated brain iron content, which has been observed in late stage human Alzheimer’s disease, is a potential target for early diagnosis. However, the time course for iron accumulation is currently unclear. Using the PSAPP mouse model of amyloid plaque formation, we conducted a time course study of metal ion content and distribution [iron (Fe), copper (Cu), and zinc (Zn)] in the cortex and hippocampus using X-ray fluorescence microscopy (XFM). We found that iron in the cortex was 34% higher than age-matched controls at an early stage, corresponding to the commencement of plaque formation. The elevated iron was not associated with the amyloid plaques. Interestingly, none of the metal ions were elevated in the amyloid plaques until the latest time point (56 weeks), where only the Zn content was significantly elevated by 38%. Since neuropathological changes in human Alzheimer’s disease are presumed to occur years before the first cognitive symptoms appear, quantification of brain iron content could be a powerful marker for early diagnosis of Alzheimer’s disease.

Leskovjan, Andreana C.; Kretlow, Ariane; Lanzirotti, Antonio; Barrea, Raul; Vogt, Stefan; Miller, Lisa M.

2011-01-01

301

mTOR inhibition: a promising strategy for stabilization of atherosclerotic plaques.  

PubMed

Statins are currently able to stabilize atherosclerotic plaques by lowering plasma cholesterol and pleiotropic effects, but a residual risk for atherosclerotic disease remains. Therefore, effective prevention of atherosclerosis and treatment of its complications is still a major clinical challenge. A large body of evidence indicates that mammalian target of rapamycin (mTOR) inhibitors such as rapamycin or everolimus have pleiotropic anti-atherosclerotic effects so that these drugs can be used as add-on therapy to prevent or delay the pathogenesis of atherosclerosis. Moreover, bioresorbable scaffolds eluting everolimus trigger a healing process in the vessel wall, both in pigs and humans, that results in late lumen enlargement and plaque regression. At present, this phenomenon of atheroregression is poorly understood. However, given that mTOR inhibitors suppress cell proliferation and trigger autophagy, a cellular survival pathway and a process linked to cholesterol efflux, we hypothesize that these compounds can inhibit (or reverse) the basic mechanisms that control plaque growth and destabilization. Unfortunately, adverse effects associated with mTOR inhibitors such as dyslipidemia and hyperglycemia have recently been identified. Dyslipidemia is manageable via statin treatment, while the anti-diabetic drug metformin would prevent hyperglycemia. Because metformin has beneficial macrovascular effects, this drug in combination with an mTOR inhibitor might have significant promise to treat patients with unstable plaques. Moreover, both statins and metformin are known to inhibit mTOR via AMPK activation so that they would fully exploit the beneficial effects of mTOR inhibition in atherosclerosis. PMID:24534455

Martinet, Wim; De Loof, Hans; De Meyer, Guido R Y

2014-04-01

302

Effect of a stabilized stannous fluoride dentifrice on plaque acid (toxin) production.  

PubMed

A Plaque Glycolysis and Regrowth Method (PGRM) has been used to examine the effects of single brushing with a new stabilized stannous fluoride dentifrice on plaque acid production. Plaque samples collected 45 minutes after subject toothbrushing were compared with samples collected prior to toothbrushing for glycolytic activity (pH reduction in incubation media), and the composition and proportion of acids produced during metabolism (capillary electrophoresis). Subjects brushed with both active SnF2 and placebo dentifrices in a cross-over design. Acetic and lactic acid were found to be produced during PGRM metabolism. SnF2 dentifrice was observed to significantly inhibit plaque glycolysis, reducing the pH drop associated with acid production. and specifically inhibiting both lactic acid and acetic acid production. Control dentifrice had a modest inhibitory effect on acid production, primarily inhibiting acetic acid production. SnF2 dentifrice inhibited lactic acid production more effectively than control dentifrice, and this effect appeared to be related to SnF2 specificity in metabolic inhibition, as opposed to the components of control dentifrice, namely ionic fluoride and surfactant. These experimental results support the in vivo antimicrobial activity of SnF2 formulated in a new stabilized matrix (currently marketed as Crest Gum Care), and demonstrate the utility of the PGRM method in elucidating specific mechanisms of action for antimicrobial agents. PMID:8593198

White, D J; Cox, E R; Gwynn, A V

1995-01-01

303

Increased brain iron coincides with early plaque formation in a mouse model of Alzheimer's disease  

SciTech Connect

Elevated brain iron content, which has been observed in late-stage human Alzheimer's disease, is a potential target for early diagnosis. However, the time course for iron accumulation is currently unclear. Using the PSAPP mouse model of amyloid plaque formation, we conducted a time course study of metal ion content and distribution [iron (Fe), copper (Cu), and zinc (Zn)] in the cortex and hippocampus using X-ray fluorescence microscopy (XFM). We found that iron in the cortex was 34% higher than age-matched controls at an early stage, corresponding to the commencement of plaque formation. The elevated iron was not associated with the amyloid plaques. Interestingly, none of the metal ions were elevated in the amyloid plaques until the latest time point (56 weeks), where only the Zn content was significantly elevated by 38%. Since neuropathological changes in human Alzheimer's disease are presumed to occur years before the first cognitive symptoms appear, quantification of brain iron content could be a powerful marker for early diagnosis of Alzheimer's disease.

Leskovjan, A.C.; Miller, L.; Kretlow, A.; Lanzirotti, A.; Barrea,R.; Vogt, S.

2010-11-23

304

Spontaneous Rupture of a Functioning Adrenocortical Carcinoma  

PubMed Central

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis, and it can be classified as either a functional or nonfunctional tumor. Affected patients usually present with abdominal pain or with symptoms related to the mass effect or hormonal activity of the tumor. Several cases of spontaneously ruptured nonfunctional adrenocortical carcinoma have been reported, but no case of a spontaneous rupture of functioning adrenocortical carcinoma has been described. We report a functioning adrenocortical carcinoma that spontaneously ruptured during a work-up.

Chung, Jin Ook; Cho, Dong Hyeok; Lee, Jae Hyuk; Kwon, Dong Deuk; Chung, Dong Jin

2010-01-01

305

Multidisciplinary management of ruptured hepatocellular carcinoma  

Microsoft Academic Search

Spontaneous rupture of hepatocellular carcinoma (HCC) is a dramatic presentation of the disease. Most published studies are\\u000a from Asian centers, and North American experience is limited. This study was under-taken to review the experience of ruptured\\u000a HCC at a North American multidisciplinary unit. Thirty pa-tients presenting with ruptured HCC at a tertiary care center from\\u000a 1985 to 2004 were studied

Andrzej K. Buczkowski; Peter T. W. Kim; Stephen G. Ho; David F. Schaeffer; Sung I. Lee; David A. Owen; Alan H. Weiss; Stephen W. Chung; Charles H. Scudamore

2006-01-01

306

Endoluminal stent reconstruction of low-grade, symptomatic carotid plaques: a treatment alternative--report of two cases  

PubMed Central

Introduction Medical treatment of low-grade (<50% luminal narrowing) symptomatic carotid stenosis has been the treatment of choice because trial data showed no evident benefit to carotid endarterectomy for these patients. Such patients may have recurrent neurological symptoms despite adequate medical therapy owing to recurrent plaque rupture. In such cases, carotid stenting may represent an option for treatment but has not been tested in trials because of previous failure of carotid endarterectomy to demonstrate any benefit for patients with low-grade carotid stenosis. The cases presented here illustrate the perioperative safety and potential benefit of carotid stenting for such patients with persistent neurological symptoms despite adequate medical therapy. Case material Two patients with low-grade stenosis and recurrent transient ischemic attack or stroke despite antiplatelet therapy were treated with carotid stenting. Both patients were treated after recent ipsilateral neurological events in the absence of an evident cardioembolic source. Carotid plaque ulceration thought to be related to the ischemic events was present in both cases. No perioperative complications were noted. On followup, the patients showed resolution of symptoms and had no new neurological events. Conclusion Carotid stenting of low-grade but symptomatic carotid plaque refractory to medical management represents a surgical option for treatment. Further studies may be warranted to evaluate stenting as a suitable treatment option.

Shallwani, Hussain; Dumont, Travis M.; Wach, Michael M.; Levy, Elad I.; Siddiqui, Adnan H.

2014-01-01

307

Crucial roles of holes in electronic bond rupture on semiconductor surfaces  

NASA Astrophysics Data System (ADS)

Structural changes on cleaved (110) surfaces of InP, induced by tunneling carriers from the tip of a scanning tunneling microscope, were studied. Bond rupture takes place at intrinsic P-sites only at negative sample voltages (i.e., under hole-injection conditions), resulting in the formation of P-vacancies, while injected electrons induce no structural change. The rate of bond rupture, showing a prominent threshold sample voltage at - 2.2 V, is a quadratic function of the tunneling current. Nonlinear localization of two holes injected into surface bands is crucial as the primary step in the electronic bond rupture on semiconductor surfaces.

Tsuruta, J.; Inami, E.; Kanasaki, J.; Tanimura, K.

2014-08-01

308

Acute achilles tendon rupture in athletes.  

PubMed

The incidence of AT rupture has increased in recent decades. AT ruptures frequently occur in the third or fourth decade of life in sedentary individuals who play sport occasionally. Ruptures also occur in elite athletes. Clinical examination must be followed by imaging. Conservative management and early mobilization can achieve excellent results, but the rerupture rate is not acceptable for the management of young, active, or athletic individuals. Open surgery is the most common option for AT ruptures, but there are risks of superficial skin breakdown and wound problems. These problems can be prevented with percutaneous repair. PMID:23707180

Longo, Umile Giuseppe; Petrillo, Stefano; Maffulli, Nicola; Denaro, Vincenzo

2013-06-01

309

Neck curve polynomials in neck rupture model  

SciTech Connect

The Neck Rupture Model is a model that explains the scission process which has smallest radius in liquid drop at certain position. Old fashion of rupture position is determined randomly so that has been called as Random Neck Rupture Model (RNRM). The neck curve polynomials have been employed in the Neck Rupture Model for calculation the fission yield of neutron induced fission reaction of {sup 280}X{sub 90} with changing of order of polynomials as well as temperature. The neck curve polynomials approximation shows the important effects in shaping of fission yield curve.

Kurniadi, Rizal; Perkasa, Yudha S.; Waris, Abdul [Nuclear Physics and Biophysics Research Division, Department of Physics, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung 40132 (Indonesia)

2012-06-06

310

Tendon Ruptures Associated With Corticosteroid Therapy  

PubMed Central

In five patients, tendon ruptures occurred in association with corticosteroid therapy, either systemic or local infiltration. The chronic nature of the pain in all of these patients suggests that what we often call tendinitis may in fact be early or partial ruptures of tendons. Patients who receive local infiltration of corticosteroids should perhaps be advised of the risk of a ruptured tendon. In addition, particularly when the Achilles tendon is involved, immobilization should be utilized initially for a presumed tendinitis or early rupture, to protect the tendon from further injury. ImagesFigure 1.Figure 2.

Halpern, Alan A.; Horowitz, Bruce G.; Nagel, Donald A.

1977-01-01

311

Granulomatous rosacea: unusual presentation as solitary plaque.  

PubMed

A 45-year-old male presented with a 6 month history of an enlarging smooth, erythematous plaque over the central part of his face. Mild erythema of both eyes was present. Sarcoidosis, Hansen disease, lupus vulgaris, cutaneous leishmaniasis, pseudolymphoma, foreign body granuloma, granuloma faciale, discoid lupus erythematosus, and granulomatous rosacea were considered in the differential diagnosis. CBC, urinalysis, renal function tests, liver function tests, serum electrolytes, and blood sugar were all normal. Chest X-ray and ECG revealed no abnormality. Serology for syphilis and HIV, and mantoux test were negative. Slit-skin smear, tissue smear and culture for AFB and fungi were negative. Skin biopsy revealed multiple non-caseating epitheloid granulomas around the pilosebaceous unit suggestive of granulomatous rosacea. Granulomatous rosacea, a rare entity comprising only about 10 percent of cases of rosacea can mimic many granulomatous conditions both clinically and histologically making the diagnosis an enigma. It usually presents as yellowish brown-red discrete papules on the face; non-caseating epithelioid granulomas are seen on histology examination. We herein report the case because it presented in atypical fashion, as a solitary indurated plaque on the nose, likely representing Morbihan's disease or solid persistent facial edema of rosacea (rosacea lymphedema). PMID:21382292

Batra, Mayanka; Bansal, Cherry; Tulsyan, Suman

2011-01-01

312

Evaluating practice patterns for managing moderate to severe plaque psoriasis  

PubMed Central

Abstract Objective To describe practice patterns for care of Canadian patients with moderate to severe plaque psoriasis. Design Online survey of a consumer panel. Setting Participants were drawn from a population-wide Canadian consumer database. Participants To be eligible to participate, respondents had to have been diagnosed with plaque psoriasis within the past 5 years, and to have had body surface area involvement of 3% or greater in the past 5 years, or to have psoriasis on a sensitive area of the body (hands, feet, scalp, face, or genitals), or to be currently receiving treatment with systemic agents or phototherapy for psoriasis. Main outcome measures Proportion of respondents with psoriasis managed by FPs and other specialists, psoriasis therapies, comorbidities, and patient satisfaction. Results Invitations were sent to 3845 panelists with self-reported psoriasis, of which 514 qualified to complete the survey. Family physicians were reported to be the primary providers for diagnosis and ongoing care of psoriasis in all provinces except Quebec. Overall physician care was reported to be satisfactory by 62% of respondents. Most respondents receiving over-the-counter therapies (55%) or prescribed topical therapies (61%) reported that their psoriasis was managed by FPs. Respondents receiving prescription oral or injectable medications or phototherapy were mainly managed by dermatologists (42%, 74%, and 71% of respondents, respectively). Ongoing management of respondents with body surface area involvement of 10% or greater was mainly split between dermatologists (47%) and FPs (45%), compared with rheumatologists (4%) or other health care professionals (4%). Of those respondents receiving medications for concomitant health conditions, treatment for high blood pressure was most common (92%), followed by treatment for heart disease (75%) and elevated cholesterol and lipid levels (68%). Conclusion Patient-reported practice patterns for the diagnosis and management of moderate to severe psoriasis vary among provinces and in primary and secondary care settings.

Poulin, Yves; Wasel, Norman; Chan, Daphne; Bernstein, Geula; Andrew, Robin; Fraquelli, Elisa; Papp, Kim

2012-01-01

313

Apollo Soyuz Test Project Commemorative plaque in orbit  

NASA Technical Reports Server (NTRS)

The Apollo-Soyuz Test Project (ASTP) Commemorative Plaque is assembled in the Soviet Soyuz Orbital Module during the joint U.S.-U.S.S.R. Apollo-Soyuz Test Project docking in Earth orbit mission. The plaque is written both in English and Russian.

1975-01-01

314

New low-viscosity overlay medium for viral plaque assays  

PubMed Central

Background Plaque assays in cell culture monolayers under solid or semisolid overlay media are commonly used for quantification of viruses and antiviral substances. To overcome the pitfalls of known overlays, we tested suspensions of microcrystalline cellulose Avicel RC/CL™ as overlay media in the plaque and plaque-inhibition assay of influenza viruses. Results Significantly larger plaques were formed under Avicel-containing media, as compared to agar and methylcellulose (MC) overlay media. The plaque size increased with decreasing Avicel concentration, but even very diluted Avicel overlays (0.3%) ensured formation of localized plaques. Due to their low viscosity, Avicel overlays were easier to use than methylcellulose overlays, especially in the 96-well culture plates. Furthermore, Avicel overlay could be applied without prior removal of the virus inoculum thus facilitating the assay and reducing chances of cross-contamination. Using neuraminidase inhibitor oseltamivir carboxylate, we demonstrated applicability of the Avicel-based plaque reduction assay for testing of antiviral substances. Conclusion Plaque assay under Avicel-containing overlay media is easier, faster and more sensitive than assays under agar- and methylcellulose overlays. The assay can be readily performed in a 96-well plate format and seems particularly suitable for high-throughput virus titrations, serological studies and experiments on viral drug sensitivity. It may also facilitate work with highly pathogenic agents performed under hampered conditions of bio-safety labs.

Matrosovich, Mikhail; Matrosovich, Tatyana; Garten, Wolfgang; Klenk, Hans-Dieter

2006-01-01

315

Characterization of bacteriophage communities and CRISPR profiles from dental plaque  

PubMed Central

Background Dental plaque is home to a diverse and complex community of bacteria, but has generally been believed to be inhabited by relatively few viruses. We sampled the saliva and dental plaque from 4 healthy human subjects to determine whether plaque was populated by viral communities, and whether there were differences in viral communities specific to subject or sample type. Results We found that the plaque was inhabited by a community of bacteriophage whose membership was mostly subject-specific. There was a significant proportion of viral homologues shared between plaque and salivary viromes within each subject, suggesting that some oral viruses were present in both sites. We also characterized Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) in oral streptococci, as their profiles provide clues to the viruses that oral bacteria may be able to counteract. While there were some CRISPR spacers specific to each sample type, many more were shared across sites and were highly subject specific. Many CRISPR spacers matched viruses present in plaque, suggesting that the evolution of CRISPR loci may have been specific to plaque-derived viruses. Conclusions Our findings of subject specificity to both plaque-derived viruses and CRISPR profiles suggest that human viral ecology may be highly personalized.

2014-01-01

316

Investigation of Plaque Effects on Cardiovascular Stent System  

Microsoft Academic Search

A 3D composite stent model, which consists of the stent, plaque, and artery wall, is generated to characterize stent transient expansion and deflection behavior using Finite Element Method (FEM) approach. Two types (flat and central-thicker) of plaque models have been employed to evaluate the geometrical effects of atherosclerotic artery on the cardiovascular stent deployment system. Simulation results demonstrated that the

Heng-Chuan Kan

2010-01-01

317

Plaque assay for African swine fever virus on swine macrophages.  

PubMed

A plaque assay developed to detect the infection of African Swine Fever Virus on swine macrophages is described. Plaques were generated by all of the virus isolates tested. The method is suitable not only for virus titration but also for the selection of clones in protocols for isolation/purification of recombinant viruses. PMID:12111419

Bustos, M J; Nogal, M L; Revilla, Y; Carrascosa, A L

2002-07-01

318

Measurement of Atherosclerotic Carotid Plaque Size In Vivo Using High Resolution Magnetic Resonance Imaging  

Microsoft Academic Search

Background—Current imaging modalities, such as contrast angiography, accurately determine the degree of luminal narrowing but provide no direct information on plaque size. Magnetic resonance imaging (MRI), however, has potential for noninvasively determining arterial wall area (WA). This study was conducted to determine the accuracy of in vivo MRI for measuring the cross-sectional maximum wall area (MaxWA) of atherosclerotic carotid arteries

Chun Yuan; Kirk W. Beach; Llewellyn Hillyer Smith; Thomas S. Hatsukami

319

Papillary muscle rupture after blunt chest trauma.  

PubMed

We report a case of anterolateral papillary muscle rupture in a 22-year-old man who had blunt chest trauma caused by a car accident. Transesophageal echocardiography revealed severe mitral regurgitation caused by the rupture. He successfully underwent emergency mitral valve replacement and was discharged 9 days after the surgical correction. PMID:16581491

Cordovil, Adriana; Fischer, Claudio H; Rodrigues, Ana Clara T; Lira Filho, Edgar B; Vieira, Marcelo L C; Cury, Alexandre F; Naccarato, Gustavo A F; Valente, Carmen; Brandão, Carlos M; Pommerantzeff, Pablo M; Morhy, Samira S

2006-04-01

320

Rupture of the uterus: A changing picture  

Microsoft Academic Search

Eighty nine cases of rupture of the gravid uterus occurring over a period of 15 years with 77,133 deliveries, were analysed. The overall incidence of ruptured uteri was 1 per 866 deliveries. The patients were devided into two groups, those with a scarred uterus (47) and those with an unscarred uterus (42). Distinct differences in terms of parity, age, aetiology

J. V. Van der Merwe; W. U. A. M. Ombelet

1987-01-01

321

Urinary bladder rupture during voiding cystourethrography  

PubMed Central

Voiding cystourethrography (VCUG) is a commonly performed diagnostic procedure for the evaluation of vesicoureteral reflux with urinary tract infection or congenital renal diseases in children. The procedure is relatively simple and cost-effective, and complications are very rare. The iatrogenic complication of VCUG range from discomfort, urinary tract infection to bacteremia, as well as bladder rupture. Bladder rupture is a rare complication of VCUG, and only a few cases were reported. Bladder rupture among healthy children during VCUG is an especially uncommon event. Bladder rupture associated with VCUG is usually more common in chronically unused bladders like chronic renal failure. Presented is a case of bladder rupture that occurred during a VCUG in a healthy 9-month-old infant, due to instilled action of dye by high pressure. This injury completely healed after 7 days of operation, and it was confirmed with a postoperative cystography. The patient's bladder volume, underlying disease, velocity of the contrast media instilled, catheter size, and styles of instillation are important factors to prevent bladder rupture during VCUG. Management of bladder rupture should be individualized, but the majority of infants are treated with the operation. In conclusion, bladder rupture is a rare complication, however, delicate attention is needed in order to prevent more dire situations.

Lee, Kyong Ok; Park, Se Jin; Shin, Jae Il; Lee, Suk Young

2012-01-01

322

Rupture of wetting films caused by nanobubbles  

Microsoft Academic Search

It is now widely accepted that nanometer sized bubbles, attached at a hydrophobic silica surface, can cause rupture of aqueous wetting films due to the so-called nucleation mechanism. But the knowledge of the existence of such nanobubbles does not give an answer to how the subprocesses of this rupture mechanism operate. The aim of this paper is to describe the

K. W. Stöckelhuber; Boryan Radoev; Andreas Wenger; Hans Joachim Schulze

2004-01-01

323

Spontaneous Rupture Processes on a Bending Fault  

Microsoft Academic Search

We simulated spontaneous rupture processes on vertical bending faults, using a 3-D finite-difference method. Since shear and normal stresses on the fault depend upon its angle to the principal stresses, rupture velocity and slip ahead of a bending point vary with strike change. Moreover, slip on a bending fault is less than one on a flat fault, since a bending

Y. Kase; S. M. Day

2004-01-01

324

Rupture Velocity of Plane Strain Shear Cracks  

Microsoft Academic Search

Propagation of plane strain shear cracks is calculated numerically by using finite difference equations with second-order accuracy. The rupture model, in which stress drops gradually as slip increases, combines two different rupture criteria: (1) slip begins at a finite stress level; (2) finite energy is absorbed per unit area as the crack advances. Solutions for this model are nonsingular. In

D. J. Andrews

1976-01-01

325

Fractal avalanche ruptures in biological membranes  

NASA Astrophysics Data System (ADS)

Bilayer membranes envelope cells as well as organelles, and constitute the most ubiquitous biological material found in all branches of the phylogenetic tree. Cell membrane rupture is an important biological process, and substantial rupture rates are found in skeletal and cardiac muscle cells under a mechanical load. Rupture can also be induced by processes such as cell death, and active cell membrane repair mechanisms are essential to preserve cell integrity. Pore formation in cell membranes is also at the heart of many biomedical applications such as in drug, gene and short interfering RNA delivery. Membrane rupture dynamics has been studied in bilayer vesicles under tensile stress, which consistently produce circular pores. We observed very different rupture mechanics in bilayer membranes spreading on solid supports: in one instance fingering instabilities were seen resulting in floral-like pores and in another, the rupture proceeded in a series of rapid avalanches causing fractal membrane fragmentation. The intermittent character of rupture evolution and the broad distribution in avalanche sizes is consistent with crackling-noise dynamics. Such noisy dynamics appear in fracture of solid disordered materials, in dislocation avalanches in plastic deformations and domain wall magnetization avalanches. We also observed similar fractal rupture mechanics in spreading cell membranes.

Gözen, Irep; Dommersnes, Paul; Czolkos, Ilja; Jesorka, Aldo; Lobovkina, Tatsiana; Orwar, Owe

2010-11-01

326

Non-invasive imaging of atherosclerotic plaque macrophage in a rabbit model with F-18 FDG PET: a histopathological correlation  

PubMed Central

Background Coronary atherosclerosis and its thrombotic complications are the major cause of mortality and morbidity throughout the industrialized world. Thrombosis on disrupted atherosclerotic plaques plays a key role in the onset of acute coronary syndromes. Macrophages density is one of the most critical compositions of plaque in both plaque vulnerability and thrombogenicity upon rupture. It has been shown that macrophages have a high uptake of 18F-FDG (FDG). We studied the correlation of FDG uptake with histopathological macrophage accumulation in atherosclerotic plaques in a rabbit model. Methods Atherosclerosis was induced in rabbits (n = 6) by a combination of atherogenic diet and balloon denudation of the aorta. PET imaging was performed at baseline and 2 months after atherogenic diet and coregistered with magnetic resonance (MR) imaging. Normal (n = 3) rabbits served as controls. FDG uptake by the thoracic aorta was expressed as concentration (?Ci/ml) and the ratio of aortic uptake-to-blood radioactivity. FDG uptake and RAM-11 antibody positive areas were analyzed in descending aorta. Results Atherosclerotic aortas showed significantly higher uptake of FDG than normal aortas. The correlation of aortic FDG uptake with macrophage areas assessed by histopathology was statistically significant although it was not high (r = 0.48, p < 0.0001). When uptake was expressed as the ratio of aortic uptake-to-blood activity, it correlated better (r = 0.80, p < 0.0001) with the macrophage areas, due to the correction for residual blood FDG activity. Conclusion PET FDG activity correlated with macrophage content within aortic atherosclerosis. This imaging approach might serve as a useful non-invasive imaging technique and potentially permit monitoring of relative changes in inflammation within the atherosclerotic lesion.

Zhang, Zhuangyu; Machac, Josef; Helft, Gerard; Worthley, Stephen G; Tang, Cheuk; Zaman, Azfar G; Rodriguez, Oswaldo J; Buchsbaum, Monte S; Fuster, Valentin; Badimon, Juan J

2006-01-01

327

Automated coronary CT angiography plaque-lumen segmentation  

NASA Astrophysics Data System (ADS)

We are investigating the feasibility of a computer-aided detection (CAD) system to assist radiologists in diagnosing coronary artery disease in ECG gated cardiac multi-detector CT scans having calcified plaque. Coronary artery stenosis analysis is challenging if calcified plaque or the iodinated blood pool hides viable lumen. The research described herein provides an improved presentation to the radiologist by removing obscuring calcified plaque and blood pool. The algorithm derives a Gaussian estimate of the point spread function (PSF) of the scanner responsible for plaque blooming by fitting measured CTA image profiles. An initial estimate of the extent of calcified plaque is obtained from the image evidence using a simple threshold. The Gaussian PSF estimate is then convolved with the initial plaque estimate to obtain an estimate of the extent of the blooming artifact and this plaque blooming image is subtracted from the CT image to obtain an image largely free of obscuring plaque. In a separate step, the obscuring blood pool is suppressed using morphological operations and adaptive region growing. After processing by our algorithm, we are able to project the segmented plaque-free lumen to form synthetic angiograms free from obstruction. We can also analyze the coronary arteries with vessel tracking and centerline extraction to produce cross sectional images for measuring lumen stenosis. As an additional aid to radiologists, we also produce plots of calcified plaque and lumen cross-sectional area along selected blood vessels. The method was validated using digital phantoms and actual patient data, including in one case, a validation against the results of a catheter angiogram.

Cline, Harvey E.; Krishnan, Karthik; Napel, Sandy; Rubin, Geoffrey D.; Turner, Wesley D.; Avila, Ricardo S.

2009-02-01

328

Do buried-rupture earthquakes trigger less landslides than surface-rupture earthquakes for reverse faults?  

NASA Astrophysics Data System (ADS)

Gorum et al. (2013, Geomorphology 184, 127-138) carried out a study on inventory compilation and statistical analyses of landslides triggered by the 2010 Mw 7.0 Haiti earthquake. They revealed that spatial distribution patterns of these landslides were mainly controlled by complex rupture mechanism and topography. They also suggested that blind-rupture earthquakes trigger fewer landslides than surface-rupture earthquakes on thrust reverse faults. Although a few lines of evidence indicate that buried-rupture earthquakes might trigger fewer landslides than surface-rupture earthquakes on reverse faults, more careful comparisons and analyses indicate that it is not always true. Instead, some cases show that a buried-rupture earthquake can trigger a larger quantity of landslides that are distributed in a larger area, whereas surface-rupture earthquakes can trigger larger but a fewer landslides distributed in a smaller area.

Xu, Chong

2014-07-01

329

Quantification of coronary arterial plaque volume using 3D reconstructions formed by fusing intravascular ultrasound and biplane angiography  

NASA Astrophysics Data System (ADS)

This paper, through plaque quantification, demonstrates the use of three-dimensional (3D) reconstructions of coronary arteries to assess compensatory enlargement. The lumen and medial-adventitial border are segmented from intravascular ultrasound (IVUS) images using a novel 3D method called active surfaces and the segmented data is used to calculate the cross-sectional area of the lumen and vessel, respectively. The area of plaque for each slice is the difference of the two. Information about the distance between path points, located using a calibrated biplane angiography system, is used for the calculation of plaque volume. This quantification system can be used to track the progression or regression of atherosclerosis and is currently being used to document compensatory enlargement, a physiological phenomenon in which the overall vessel cross-sectional area increases with an increase in plaque area with little or no decrease in luminal cross-sectional area. Four ex-vivo cases have been quantified, all demonstrating this remodeling mechanism, shown by strong positive correlation between plaque area and vessel area over the reconstructed length of the vessel (R equals 0.98, R equals 0.93, R equals 0.98, R equals 0.68).

Klingensmith, Jon D.; Vince, David G.; Shekhar, R.; Kuban, Barry D.; Tuzcu, E. M.; Cornhill, J. Fredrick

1999-05-01

330

Management of prelabour rupture of membranes (PROM) at term.  

PubMed

Over a 20-month period we identified several cases of neonatal pneumonia associated with prelabour rupture of membranes (PROM) at term. PROM complicates 8%-10% of all pregnancies, yet 60% of cases occur at term. Ascending infection is a contributing factor and the incidence of chorioamnionitis in these patients is relatively high, especially with prolonged membrane rupture. The signs and symptoms NICE recommends patients look out for are not always present as the majority of infections are subclinical, yet associated maternal and neonatal morbidity of chorioamnionitis is potentially devastating. A survey of maternity units in the West Midlands reveals significant variance in management of these cases. Given the lack of consensus and clear evidence on optimal management of PROM at term, we believe early detection of developing infections could be enhanced by using a combination of investigations (at presentation, 12 and 24 h), as well as current advice to self-monitor temperature and vaginal loss. PMID:23828422

Ismail, Abdul Qader Tahir; Lahiri, Soma

2013-11-01

331

Effect of heating method on stress-rupture life  

NASA Technical Reports Server (NTRS)

The effect of radiant(furnace), resistance(electric current), burner(hot gas stream), and a combination of resistance and burner heating on intermediate time (100 to 300 hr) stress-rupture life and reduction of area was evaluated. All heating methods were studied using the nickel-based alloy Udimet 700 while all but burner heating were evaluated with the cobalt-based alloy Mar-M 509. Limited test results of eight other superalloys were also included in this study. Resistance heated specimens had about 20 to 30 percent of the stress-rupture life of radiant heated specimens. The limited burner heating data showed about a 50 percent life reduction as compared to the radiant heated tests. A metallurgical examination gave no explanation for these reductions.

Bizon, P. T.; Calfo, F. D.

1977-01-01

332

[Spinal destruction caused by chronic contained rupture of an infra-renal abdominal aortic aneurysm].  

PubMed

The erosion of the lumbar vertebral bodies by a chronic contained rupture of an infra-renal abdominal aortic aneurysm is a rare event. Chronic contained rupture can cause diagnostic difficulties as there are many clinical presentations, such as: back pain, sciatic pain or an expansive abdominal mass. The diagnosis is sometimes made following an incidental finding on radiological examination. Currently a CT scan is the gold standard diagnostic tool. The outcome following urgent surgical or endovascular repair is equivalent to that of an elective aneurysm repair. We report a case of a 59 year old man admitted for septic rupture of a cutaneous fistula resulting from a false aneurysm in the left groin. Pre-operative CT scan revealed a 6 cm abdominal aortic aneurysm, with chronic contained rupture. This had caused bone erosion of the vertebral body of the third lumbar vertebrae. PMID:16840951

Penard, J; Picquet, J; Jousset, Y; Blin, V; Papon, X; Enon, B

2006-07-01

333

Association of Carotid Plaque Echogenicity with Recurrence of Ischemic Stroke  

PubMed Central

Background: Atherosclerosis is related to various cardiovascular and cerebrovascular events like cerebral infarction. Recurrence of ischemic stroke is specifically related to atherosclerotic load as determined by the presence of carotid atheromatous plaques and its echogenicity. Aim: This study was to evaluate the association of recurrence of stroke with echogenic characteristics of carotid plaque in ischemic stroke patients. Materials and Methods: Carotid sonography using high-resolution 7.5 MHz along with gray-scale technique was done in each ischemic stroke patient to find the occurrence of plaque and its echogenicity according to Mannheim Carotid Intima-Media Thickness Consensus (2004-2006). Followup of patient done to know the recurrence of stroke during 6-month duration and its association with plaque echogenicity. Results: A significant association found between the presence of plaque and known cerebrovascular risk factors. Also significant association found between recurrence of stroke and echolucent character of carotid plaque in bivariate analysis (P = 0.0028). Conclusions: Recurrence of stroke is related to advanced stage of atherosclerosis that is specified by carotid plaque and its characteristics. It will help us to identify groups of patients at different risk for stroke and planning better strategies to prevent such events.

Singh, Amit Shankar; Atam, Virendra; Jain, Nirdesh; Yathish, Besthanahalli Errapa; Patil, Malagouda R; Das, Liza

2013-01-01

334

The association of pericardial fat with calcified coronary plaque  

PubMed Central

Background Pericardial fat has a higher secretion of inflammatory cytokines than subcutaneous fat. Cytokines released from pericardial fat around coronary arteries may act locally on the adjacent cells. Objective We examined the relationship between pericardial fat and calcified coronary plaque. Design Participants in the community-based Multi-Ethnic Study of Atherosclerosis underwent a computed tomography scan for the assessment of calcified coronary plaque in 2001/02. We measured the volume of pericardial fat using these scans in 159 whites and blacks without symptomatic coronary heart disease from Forsyth County, NC, aged 55–74 years. Results Calcified coronary plaque was observed in 91 participants (57%). After adjusting for height, a one standard deviation increment in pericardial fat was associated with an increased odds of calcified coronary plaque (odds ratio (95% confidence interval): 1.92 (1.27, 2.90)). With further adjustment of other cardiovascular factors, pericardial fat was still significantly associated with calcified coronary plaque. This relationship did not differ by gender and ethnicity. On the other hand, body mass index and height-adjusted waist circumference were not associated with calcified coronary plaque. Conclusions Pericardial fat is independently associated with calcified coronary plaque.

Ding, Jingzhong; Kritchevsky, Stephen B.; Harris, Tamara B.; Burke, Gregory L.; Detrano, Robert C.; Szklo, Moyses; Carr, J. Jeffrey

2014-01-01

335

Collagenolytic Activity of Dental Plaque Associated with Periodontal Pathology  

PubMed Central

Certain dental plaques, removed from sites of gingival and periodontal pathology in mentally retarded, institutionalized individuals, when incubated in phosphate buffer with Achilles tendon collagen, gave rise to an increase in ninhydrin-positive material. These plaques, while showing great variability, released significantly more ninhydrin-positive material per milligram of plaque (wet weight) than did either the endogenous or heat-treated controls. Certain plaques could also break down soluble, tritiated, labeled collagen isolated from the calvaria of chicken embryos. Bacteroides melaninogenicus and Clostridia histolyticum were found in plaques by either fluorescent antibody or cultural methods. C. histolyticum, when detected, accounted for about 0.01 to 0.1% of the bacteria in plaque. A conspicuous isolate from some plaques was a Bacillus species which rapidly liquefied gelatin. Cell-free supernatants of this organism were able to degrade about 50 to 70% of the soluble collagen when incubated at 36 C. C. histolyticum ATCC 8034 caused an 80% degradation of the collagen under the same conditions of incubation. The Bacillus strains were facultative, could ferment glucose, reduced nitrate to nitrite, and were catalase, indole, and urease negative. The limited taxonomic information for the isolates is compatible with the description given for Bacillus cereus.

Loesche, W. J.; Paunio, K. U.; Woolfolk, M. P.; Hockett, R. N.

1974-01-01

336

Siglec receptors and hiding plaques in Alzheimer's disease.  

PubMed

Alzheimer's disease (AD) is a progressive neurodegenerative disease. One hallmark of this disease is the continuous increase in the numbers and size of aggregating amyloid plaques. The accumulation of extracellular plaques is an immunologically interesting phenomenon since microglial cells, brain-specific macrophages, should be able to cleanse the aggregating material from the human brain. Immunotherapy targeting beta-amyloid peptides in plaques with antibodies represents a promising therapy in AD. Recent progress in pattern recognition receptors of monocytes and macrophages has revealed that the sialic acid-binding, immunoglobulin-like lectin (Siglec) family of receptors is an important recognition receptor for sialylated glycoproteins and glycolipids. Interestingly, recent studies have revealed that microglial cells contain only one type of Siglec receptors, Siglec-11, which mediates immunosuppressive signals and thus inhibits the function of other microglial pattern recognition receptors, such as TLRs, NLRs, and RAGE receptors. We will review here the recent literature which clearly indicates that aggregating amyloid plaques are masked in AD by sialylated glycoproteins and gangliosides. Sialylation and glycosylation of plaques, mimicking the cell surface glycocalyx, can activate the immunosuppressive Siglec-11 receptors, as well as hiding the neuritic plaques, allowing them to evade the immune surveillance of microglial cells. This kind of immune evasion can prevent the microglial cleansing process of aggregating amyloid plaques in AD. PMID:19390836

Salminen, Antero; Kaarniranta, Kai

2009-07-01

337

Microglial response to amyloid plaques in APPsw transgenic mice.  

PubMed Central

Microglial activation is central to the inflammatory response in Alzheimer's Disease (AD). A recently described mouse line, Tg(HuAPP695.K670N/M671L)2576, expressing human amyloid precursor protein with a familial AD gene mutation, age-related amyloid deposits, and memory deficits, was found to develop a significant microglial response using Griffonia simplicifolia lectin or phosphotyrosine probe to identify microglia Both Griffonia simplicifolia lectin and phosphotyrosine staining showed increased numbers of intensely labeled, often enlarged microglia clustered in and around plaques, consistent with microglial activation related to beta-amyloid formation. Using quantitative image analysis of coronal phosphotyrosine-immunostained sections, transgene-positive 10- to 16-month-old, hemizygous, hybrid Tg2576 (APPsw) animals showed significantly increased microglial density and size in plaque-forming areas of hippocampus and frontal, entorhinal, and occipital cortex. Quantitative analysis of microglia as a function of distance from the center of plaques (double labeled for A beta peptide and microglia) revealed highly significant, two- to fivefold elevations in microglial number and area within plaques compared with neighboring regions. Tg2576 beta-amyloid-plaque-forming mice should be a useful system for assessing the consequences of the microglial-mediated inflammatory response to beta-amyloid and developing anti-inflammatory therapeutic strategies for Alzheimer's disease. These results provide the first quantitative link between beta-amyloid plaque formation and microglial activation in an animal model with neuritic plaques and memory deficits. Images Figure 1 Figure 2

Frautschy, S. A.; Yang, F.; Irrizarry, M.; Hyman, B.; Saido, T. C.; Hsiao, K.; Cole, G. M.

1998-01-01

338

Dynamic Rupture Through Branched Fault Configurations With Off-fault Inelastic Response  

NASA Astrophysics Data System (ADS)

We analyze the propagation of shear ruptures along branched fault paths, allowing for elastic-plastic deformation in damaged fault-bordering zones. Geometric complexities (step-overs, bends and branches) along faults can control earthquake rupture propagation and in many cases confine propagation extent. Multiple numerical investigations have focused on such complexities during rupture (Harris and Day, 1991, 1993; Aochi et al., 2000; Kame et al., 2003) and, separately, on the role of inelastic off- fault material response during rupture (Andrews, 2005, 2007; Shi and Ben-Zion, 2006; Templeton and Rice, 2008; Viesca et al., 2008; Duan, 2008). Those inelastic studies use pressure-dependent elastic-plastic material descriptions such as Mohr-Coulomb or Drucker-Prager, which are standard models for describing plastic deformation in granulated or cracked materials like expected in damaged fault-bordering zones. We first summarize current understanding of rupture path selection at fault branching junctions, as supported by field and laboratory comparisons with modeling, including previous studies in our group based on boundary integral equation implementations of slip-weakening rupture, but with assumption of elastic off-fault response (Poliakov et al., 2002; Kame et al., 2003; Bhat et al., 2004, 2007; Fliss et al., 2005). We then show through dynamic finite element modeling how inelastic deformation in damaged fault-bordering zones contributes to path selection, and how branch activation affects seismic radiation. We assess dynamic path selection for a variety of branch angles and pre-stress directions, considering both sub-Rayleigh and supershear propagation speeds at the branching junction, and compare results for incohesive elastic-plastic off-fault response with those for elastic response. In particular, we have modeled rupture through possible fault branches along Solitario Canyon Fault (SCF) in the hanging wall, a normal fault bordering Yucca Mountain, NV. We find that (incohesive) inelastic response during rupture slightly increases the range of branch angles activated during dynamic rupture for supershear rupture speeds, but decreases the range of angles for sub-Rayleigh speeds. The inelastic response significantly reduces seismically generated ground accelerations at the proposed repository site, approximately 300 m below the crest of Yucca Mountain. We also address the energy partitioning during rupture, and find that branch activation can decrease the plastic energy dissipation during rupture compared with the no-branch case.

Templeton, E. L.; Bhat, H. S.; Dmowska, R.; Rice, J. R.

2008-12-01

339

In vivo Near Infrared Fluorescence (NIRF) Intravascular Molecular Imaging of Inflammatory Plaque, a Multimodal Approach to Imaging of Atherosclerosis  

PubMed Central

The vascular response to injury is a well-orchestrated inflammatory response triggered by the accumulation of macrophages within the vessel wall leading to an accumulation of lipid-laden intra-luminal plaque, smooth muscle cell proliferation and progressive narrowing of the vessel lumen. The formation of such vulnerable plaques prone to rupture underlies the majority of cases of acute myocardial infarction. The complex molecular and cellular inflammatory cascade is orchestrated by the recruitment of T lymphocytes and macrophages and their paracrine effects on endothelial and smooth muscle cells.1 Molecular imaging in atherosclerosis has evolved into an important clinical and research tool that allows in vivo visualization of inflammation and other biological processes. Several recent examples demonstrate the ability to detect high-risk plaques in patients, and assess the effects of pharmacotherapeutics in atherosclerosis.4 While a number of molecular imaging approaches (in particular MRI and PET) can image biological aspects of large vessels such as the carotid arteries, scant options exist for imaging of coronary arteries.2 The advent of high-resolution optical imaging strategies, in particular near-infrared fluorescence (NIRF), coupled with activatable fluorescent probes, have enhanced sensitivity and led to the development of new intravascular strategies to improve biological imaging of human coronary atherosclerosis. Near infrared fluorescence (NIRF) molecular imaging utilizes excitation light with a defined band width (650-900 nm) as a source of photons that, when delivered to an optical contrast agent or fluorescent probe, emits fluorescence in the NIR window that can be detected using an appropriate emission filter and a high sensitivity charge-coupled camera. As opposed to visible light, NIR light penetrates deeply into tissue, is markedly less attenuated by endogenous photon absorbers such as hemoglobin, lipid and water, and enables high target-to-background ratios due to reduced autofluorescence in the NIR window. Imaging within the NIR 'window' can substantially improve the potential for in vivo imaging.2,5 Inflammatory cysteine proteases have been well studied using activatable NIRF probes10, and play important roles in atherogenesis. Via degradation of the extracellular matrix, cysteine proteases contribute importantly to the progression and complications of atherosclerosis8. In particular, the cysteine protease, cathepsin B, is highly expressed and colocalizes with macrophages in experimental murine, rabbit, and human atheromata.3,6,7 In addition, cathepsin B activity in plaques can be sensed in vivo utilizing a previously described 1-D intravascular near-infrared fluorescence technology6, in conjunction with an injectable nanosensor agent that consists of a poly-lysine polymer backbone derivatized with multiple NIR fluorochromes (VM110/Prosense750, ex/em 750/780nm, VisEn Medical, Woburn, MA) that results in strong intramolecular quenching at baseline.10 Following targeted enzymatic cleavage by cysteine proteases such as cathepsin B (known to colocalize with plaque macrophages), the fluorochromes separate, resulting in substantial amplification of the NIRF signal. Intravascular detection of NIR fluorescence signal by the utilized novel 2D intravascular NIRF catheter now enables high-resolution, geometrically accurate in vivo detection of cathepsin B activity in inflamed plaque. In vivo molecular imaging of atherosclerosis using catheter-based 2D NIRF imaging, as opposed to a prior 1-D spectroscopic approach,6 is a novel and promising tool that utilizes augmented protease activity in macrophage-rich plaque to detect vascular inflammation.11,12 The following research protocol describes the use of an intravascular 2-dimensional NIRF catheter to image and characterize plaque structure utilizing key aspects of plaque biology. It is a translatable platform that when integrated with existing clinical imaging technologies including angiography and intravascular ultrasound (IVUS), offers a unique and novel integrate

Calfon, Marcella A.; Rosenthal, Amir; Mallas, Georgios; Mauskapf, Adam; Nudelman, R. Nika; Ntziachristos, Vasilis; Jaffer, Farouc A.

2011-01-01

340

Isolated gallbladder rupture following blunt abdominal trauma.  

PubMed

The gallbladder is a relatively well-protected organ; consequently its rupture following blunt abdominal injury is rare and usually associated with other visceral injuries. Isolated gallbladder rupture is extremely rare. We report a healthy Nigerian adult male who sustained isolated gallbladder rupture following blunt abdominal injury from riding a motor cycle (Okada). A high index of suspicion with positive bile aspirate might lead to early diagnosis. Open cholecystectomy is a safe option of treatment in a resource poor centre especially in delayed presentation and has a good outcome. PMID:23771471

Gali, B M; Ali, N; Bakari, A A; Suleiman, I E

2013-01-01

341

Human APOE4 increases microglia reactivity at A? plaques in a mouse model of A? deposition  

PubMed Central

Background Having the apolipoprotein E4 (APOE-?4) allele is the strongest genetic risk factor for the development of Alzheimer’s disease (AD). Accumulation of amyloid beta (A?) in the brain is influenced by APOE genotype. Transgenic mice co-expressing five familial AD mutations (5xFAD) in the presence of human APOE alleles (?2, ?3 or ?4) exhibit APOE genotype-specific differences in early A? accumulation, suggesting an interaction between APOE and AD pathology. Whether APOE genotype affects A?-plaque-associated neuroinflammation remains unclear. In the current study, we address the role of APOE genotype on A?-associated microglial reactivity in the EFAD transgenic mouse model. Methods We analyzed A?-induced glial activation in the brains of 6-month-old EFAD transgenic mice (E2FAD, E3FAD and E4FAD). Region-specific morphological profiles of A? plaques in EFAD brain sections were compared using immunofluorescence staining. We then determined the degree of glial activation in sites of A? deposition while comparing levels of the inflammatory cytokine Interleukin-1? (IL-1?) by ELISA. Finally, we quantified parameters of A?-associated microglial reactivity using double-stained EFAD brain sections. Results Characterization of A? plaques revealed there were larger and more intensely stained plaques in E4FAD mice relative to E2FAD and E3FAD mice. E4FAD mice also had a greater percentage of compact plaques in the subiculum than E3FAD mice. Reactive microglia and dystrophic astrocytes were prominent in EFAD brains, and primarily localized to two sites of significant A? deposition: the subiculum and deep layers of the cortex. Cortical levels of IL-1? were nearly twofold greater in E4FAD mice relative to E3FAD mice. To control for differences in levels of A? in the different EFAD mice, we analyzed the microglia within domains of specific A? deposits. Morphometric analyses revealed increased measures of microglial reactivity in E4FAD mice, including greater dystrophy, increased fluorescence intensity and a higher density of reactive cells surrounding cortical plaques, than in E3FAD mice. Conclusions In addition to altering morphological profiles of A? deposition, APOE genotype influences A?-induced glial activation in the adult EFAD cortex. These data support a role for APOE in modulating A?-induced neuroinflammatory responses in AD progression, and support the use of EFAD mice as a suitable model for mechanistic studies of A?-associated neuroinflammation.

2014-01-01

342

Describing Soils: Calibration Tool for Teaching Soil Rupture Resistance  

ERIC Educational Resources Information Center

Rupture resistance is a measure of the strength of a soil to withstand an applied stress or resist deformation. In soil survey, during routine soil descriptions, rupture resistance is described for each horizon or layer in the soil profile. The lower portion of the rupture resistance classes are assigned based on rupture between thumb and…

Seybold, C. A.; Harms, D. S.; Grossman, R. B.

2009-01-01

343

[Methylation profiling of human atherosclerotic plaques].  

PubMed

Somatic mutation theory of atherogenesis proved by alterations at the DNA level such as "loss of heterozygosity" and microsatellite instability in atherosclerotic plaque is complemented by the date of epigenetic variability of genetic loci involved in the pathological process. However, only recently large-scale analysis of epigenetic modifications in the human genome became possible. For the first time quantitative microarray-based methylation profiling of 1505 CpG-sites across 807 genes was performed in atherosclerotic aorta and carotid artery wall lesions using the GoldenGate Methylation Cancer Panel I ("Illumina", USA). One hundred and three (7%) CpG-sites in 90 (11%) genes were differentially methylated between tissue samples. The most pronounced differences in DNA methylation levels were registered for a site which is located in CpG-island of imprinted gene H19. By comparing 90 genes that were differentially methylated between tissue samples in our study, 10 genes (ICAM1, GSTM1, IGFBP1, POMC, APOA1, IL1RN, INS, LTA, MMP3, THBS2) were overlapped with data in Human Genome Epidemiology Network (HuGENet), in which they were identified as candidates for cardiovascular disease continuum. PMID:21954592

Nazarenko, M S; Puzyrev, V P; Lebedev, I N; Frolov, A V; Barbarash, O L; Barbarash, L S

2011-01-01

344

Cerebrovascular plaque segmentation using object class uncertainty snake in MR images  

NASA Astrophysics Data System (ADS)

Atherosclerotic cerebrovascular disease leads to formation of lipid-laden plaques that can form emboli when ruptured causing blockage to cerebral vessels. The clinical manifestation of this event sequence is stroke; a leading cause of disability and death. In vivo MR imaging provides detailed image of vascular architecture for the carotid artery making it suitable for analysis of morphological features. Assessing the status of carotid arteries that supplies blood to the brain is of primary interest to such investigations. Reproducible quantification of carotid artery dimensions in MR images is essential for plaque analysis. Manual segmentation being the only method presently makes it time consuming and sensitive to inter and intra observer variability. This paper presents a deformable model for lumen and vessel wall segmentation of carotid artery from MR images. The major challenges of carotid artery segmentation are (a) low signal-to-noise ratio, (b) background intensity inhomogeneity and (c) indistinct inner and/or outer vessel wall. We propose a new, effective object-class uncertainty based deformable model with additional features tailored toward this specific application. Object-class uncertainty optimally utilizes MR intensity characteristics of various anatomic entities that enable the snake to avert leakage through fuzzy boundaries. To strengthen the deformable model for this application, some other properties are attributed to it in the form of (1) fully arc-based deformation using a Gaussian model to maximally exploit vessel wall smoothness, (2) construction of a forbidden region for outer-wall segmentation to reduce interferences by prominent lumen features and (3) arc-based landmark for efficient user interaction. The algorithm has been tested upon T1- and PD- weighted images. Measures of lumen area and vessel wall area are computed from segmented data of 10 patient MR images and their accuracy and reproducibility are examined. These results correspond exceptionally well with manual segmentation completed by radiology experts. Reproducibility of the proposed method is estimated for both intra- and inter-operator studies.

Das, Bipul; Saha, Punam K.; Wolf, Ronald; Song, Hee Kwon; Wright, Alexander C.; Wehrli, Felix W.

2005-04-01

345

Spectroscopic intravascular photoacoustic imaging to differentiate atherosclerotic plaques.  

PubMed

The potential of intravascular photoacoustic (IVPA) imaging to detect atherosclerosis was previously demonstrated using a 532 nm nanosecond pulsed laser and an intravascular ultrasound (IVUS) imaging catheter. However, to differentiate vulnerable plaques, the composition of plaques needs to be imaged. Therefore, we introduce a multi-wavelength photoacoustic imaging method to distinguish various types of plaques. Multi-spectral IVPA imaging of ex vivo samples of normal and atherosclerotic rabbit aorta was performed at several wavelengths within 680-900 nm range. The spectral variation of photoacoustic response was extracted and a spectroscopic analysis was performed. The results of our preliminary study suggest that the spectroscopic intravascular photoacoustic imaging technique can be used to differentiate fibrous and lipid components of the atherosclerotic plaques. PMID:18542427

Sethuraman, Shriram; Amirian, James H; Litovsky, Silvio H; Smalling, Richard W; Emelianov, Stanislav Y

2008-03-01

346

6. VIEW OF COMMEMORATIVE PLAQUE, EAST APPROACH GUARDRAIL, WHICH STATES ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VIEW OF COMMEMORATIVE PLAQUE, EAST APPROACH GUARDRAIL, WHICH STATES 'SALINE RIVER; ARK. GENERAL CONST. CO.; CONTRACTOR; ARKANSAS; STATE HIGHWAY DEPARTMENT; 1928, BRIDGE NO. __.' - Saline River Bridge, County Highway 365 across Saline River, Benton, Saline County, AR

347

Advances in mechanisms, imaging and management of the unstable plaque.  

PubMed

Post-mortem observations demonstrated that plaque fissure was the final event leading to coronary thrombosis and occlusion in about two-thirds of cases of sudden coronary death. Plaques prone to fissure have, therefore, been defined "vulnerable plaques" and are identified by specific anatomic features including thin inflamed fibrous cap, large lipidic core and positive remodeling. Accordingly, elegant imaging modalities have been developed in order to identify this "holy grail". However, the results of prognostic studies based on the identification of vulnerable plaques have not been encouraging because of the low positive predictive value for major cardiovascular events. This observation is not surprising as the pathogenesis of acute coronary syndromes is complex and multifactorial. In this review we propose a pathogenetic classification of acute coronary syndromes in the attempt to identify homogeneous groups of patients with a common mechanism of coronary instability which can be identified by using specific biomarkers and imaging techniques, and become a specific therapeutic target. PMID:24530781

Niccoli, Giampaolo; Liuzzo, Giovanna; Montone, Rocco A; Crea, Filippo

2014-04-01

348

Penetrating the plaque biofilm: impact of essential oil mouthwash.  

PubMed

The interaction between saliva-coated tooth surfaces and pathogenic bacteria is partly governed by electrostatic and hydrophobic interactions, providing a solid rationale for using chemical agents as part of a plaque-control routine. Chlorhexidine works in several ways. For example, it binds to salivary mucins on the bacterial cell membrane, and penetrates the plaque biofilm. Essential oil (EO) mouthwashes kill micro-organisms by disrupting their cell walls and inhibiting their enzymic activity. They prevent bacterial aggregation, slow multiplication and extract endotoxins. Recent studies have shown that bacterial phenotypes are altered when organisms change from a planktonic to a sessile state. This suggests that an effective mouthwash must also penetrate the plaque biofilm. Two studies have demonstrated the ability of an EO mouthwash to penetrate the plaque biofilm. PMID:12787196

Ouhayoun, J-P

2003-01-01

349

Correlation between aortic/carotid atherosclerotic plaques and cerebral infarction  

PubMed Central

The aim of this study was to investigate the correlation between aortic/carotid atherosclerotic plaques and cerebral infarction. We examined 116 cases of cerebral infarction using transcranial Doppler ultrasound in order to exclude cerebrovascular stenosis. Transesophageal echocardiography and color Doppler ultrasound were used to detect aortic atherosclerotic plaques (AAPs) and carotid atherosclerotic plaques (CAPs). AAPs were detected in a total of 70 of the 116 cases (60.3%), including 56 with moderate/severe atherosclerotic changes (48.3%). The difference in the incidence of various types of infarction between APP severity levels was significant (P<0.01). Of the 116 cases, 64 had CAPs (55.2%), including 46 with unstable plaque (39.7%). The difference in the incidence of various types of infarction between CAP stability levels was significant (P<0.01). The results indicate that moderate/severe AAP and unstable CAP are significant causes of embolic infarction without stenosis in the internal carotid arteries.

WANG, BAOJUN; SUN, SHAOLI; LIU, GUORONG; LI, YUECHUN; PANG, JIANGXIA; ZHANG, JINGFEN; YANG, LIJUAN; LI, RUIMING; ZHANG, HUI; JIANG, CHANGCHUN; LI, XIUE

2013-01-01

350

Some aspects of plaque formation by human influenza viruses  

Microsoft Academic Search

Summary Infective influenza virus seems to be essential for plaque production in chick embryo fibroblasts (CEF). With some virus strains, the amounts of virus produced by infected monolayers under an agarose overlay are very small.

C. P. de Sousa; G. Belyavin

1970-01-01

351

Elevation view of dedication plaque on east wall of south ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Elevation view of dedication plaque on east wall of south lobby - National Home for Disabled Volunteer Soldiers, Pacific Branch, Main Mental Health Building, 11301 Wilshire Boulevard, West Los Angeles, Los Angeles County, CA

352

32. STUDIO VIEW OF PLAQUE PLACED ON MILL HOUSE AT ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

32. STUDIO VIEW OF PLAQUE PLACED ON MILL HOUSE AT TIME OF COMPLETION, COMMEMORATING EDWARD J. LUKE (SEE TEXT) - Sperry Corn Elevator Complex, Weber Avenue (North side), West of Edison Street, Stockton, San Joaquin County, CA

353

8. DESCRIPTION PLAQUE Copy photograph of photogrammetric plate LCHAERPS052000402 ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. DESCRIPTION PLAQUE Copy photograph of photogrammetric plate LC-HAER-PS05-2000-402 - Falls Bridge, Spanning Schuylkill River, connecting East & West River Drives, Philadelphia, Philadelphia County, PA

354

Enzymes of Plaque Polysaccharides and Dental Caries Incidence.  

National Technical Information Service (NTIS)

Plaque samples from 50 subjects have been obtained in cooperation with the Great Lakes Naval Training Center. These samples were analyzed to determine the activity of the following enzymes--levansucrase, dextrane-sucrase, levanase, and dextranase. It was ...

R. S. Manly

1972-01-01

355

Consequences of expansion joint bellows rupture.  

National Technical Information Service (NTIS)

Expansion joints are used in piping systems to accommodate pipe deflections during service and to facilitate fitup. Typically, the expansion joint bellows is the thinnest part of the pressure boundary, bellows rupture frequencies are typically several ord...

W. L. Daugherty R. F. Miller D. S. Cramer

1992-01-01

356

Rupture of intracranial aneurysm during angiography  

Microsoft Academic Search

A case of rupture of intracranial aneurysm during angiography is presented. Carotid angiograms showed extravasation of contrast medium into the subarachnoid space at the base of the brain. The literature is reviewed and possible mechanisms are briefly discussed.

Shiro Waga; Akinori Kondo; Kozo Moritake; Hajime Handa

1973-01-01

357

Plantaris rupture: why is it important?  

PubMed

Plantaris muscle is accessory plantar flexor of calf, a vestigial muscle of triceps surae complex. Its importance lies in the fact that its rupture cans mimic deep vein thrombosis (DVT). Sometimes when there is rupture of Achilles tendon, intact plantaris can still cause plantar flexion at ankle presenting a confusing picture. We present one such case of plantaris rupture confused by radiology resident with DVT. A 51-year-old man had a feeling as if kicked in back of calf along with a snapping sound and severe pain while playing tennis. On seeing fluid between muscle plane and a hypoechoic structure radiology resident labelled it DVT. MRI suggested ruptured plantaris as fluid and muscle stump were seen between gastronemius and soleus. Patient was treated conservatively with rest, ice compression and elevated leg and showed significant reduction in pain and swelling. PMID:23345486

Rohilla, Seema; Jain, Nitin; Yadav, Rohtas

2013-01-01

358

Spontaneous splenic rupture in typhoid fever.  

PubMed Central

Three cases of multidrug-resistant Salmonella typhi infection presenting as spontaneous splenic rupture are presented. One patient died and two recovered completely. This is a previously unreported presentation of typhoid fever.

Ali, G.; Kamili, M. A.; Rashid, S.; Mansoor, A.; Lone, B. A.; Allaqaband, G. Q.

1994-01-01

359

Acute Iliac Artery Rupture: Endovascular Treatment  

SciTech Connect

The authors present 7 patients who suffered iliac artery rupture over a 2 year period. In 5 patients, the rupture was iatrogenic: 4 cases were secondary to balloon angioplasty for iliac artery stenosis and 1 occurred during coronary angioplasty. In the last 2 patients, the rupture was secondary to iliac artery mycotic aneurysm. Direct placement of a stent-graft was performed in all cases, which was dilated until extravasation was controlled. Placement of the stent-graft was successful in all the cases, without any complications. The techniques used, results, and mid-term follow-up are presented. In conclusion, endovascular placement of a stent-graft is a quick, minimally invasive, efficient, and safe method for emergency treatment of acute iliac artery rupture, with satisfactory short- and mid-term results.

Chatziioannou, A.; Mourikis, D.; Katsimilis, J.; Skiadas, V., E-mail: bill_skiadas@yahoo.gr; Koutoulidis, V.; Katsenis, K.; Vlahos, L. [University of Athens, Radiology Department, Areteion Hospital (Greece)

2007-04-15

360

Duodenal rupture following trauma in a child.  

PubMed

We present a case of delayed presentation of a traumatic duodenal rupture in a 15-year-old boy. He presented 12 hours after falling six feet and sustaining blunt trauma to his anterior abdominal wall. On arrival in the Emergency Department he was shocked and peritonitic. After initial resuscitation he was stable and transferred to computed tomography where free retroperitoneal air and duodenal rupture was found. He was transferred to theatre where he underwent laparotomy and successful repair of the rupture. He made an uneventful recovery and was discharged nine days later. Duodenal rupture is a rare but serious complication of blunt abdominal trauma. Diagnosis is difficult but missed diagnosis and delayed presentation is associated with high morbidity and mortality. A high index for suspicion must be kept when dealing with blunt abdominal trauma to ensure this is not missed. PMID:21680305

McWhirter, Derek

2011-05-01

361

Evaluation of Steam Generator Tube Rupture Events.  

National Technical Information Service (NTIS)

The NRC Staff's review of three domestic pressurized water reactor steam generator tube rupture events has shown that no significant offsite doses or systems performance inadequacies have occurred. The plant operators and systems successfully avoided dire...

L. B. Marsh

1980-01-01

362

Management of traumatic aortic rupture.  

PubMed

A traumatic thoracic aortic injury is a severe and life-threatening clinical entity. Although largely fatal; if untreated, these injuries are amenable to surgical repair if appropriately diagnosed. Therefore, early triage of this condition is critically important. Unfortunately, aortic injuries rarely occur in isolation, and there has been no good cutoff value to help select the appropriate surgical strategy. Algorithms for the both diagnosis and treatment of traumatic thoracic aortic injury have undergone changes in recent years. There have been several case reports, retrospective series and registry data describing the treatment of patients with traumatic thoracic aortic rupture using endovascular treatment. Endovascular treatment is a less-invasive management option for polytraumatized patients. Because it is less invasive, without the need for thoracotomy or the use of heparin, endovascular repair can be performed even in acutely injured patients, without the risk of destabilizing pulmonary, head or abdominal traumatic lesions. Long-term follow-up especially in young patients is necessary after endovascular treatment. PMID:23338596

Watanabe, Ken-ichi; Fukuda, Ikuo; Asari, Yasushi

2013-12-01

363

Radiobiology for eye plaque brachytherapy and evaluation of implant duration and radionuclide choice using an objective function  

SciTech Connect

Purpose: Clinical optimization of Collaborative Ocular Melanoma Study (COMS) eye plaque brachytherapy is currently limited to tumor coverage, consensus prescription dosage, and dose calculations to ocular structures. The biologically effective dose (BED) of temporary brachytherapy treatments is a function of both chosen radionuclide R and implant duration T. This study endeavored to evaluate BED delivered to the tumor volume and surrounding ocular structures as a function of plaque position P, prescription dose, R, and T. Methods: Plaque-heterogeneity-corrected dose distributions were generated with MCNP5 for the range of currently available COMS plaques loaded with sources using three available low-energy radionuclides. These physical dose distributions were imported into the PINNACLE{sup 3} treatment planning system using the TG-43 hybrid technique and used to generate dose volume histograms for a T = 7 day implant within a reference eye geometry including the ciliary body, cornea, eyelid, foveola, lacrimal gland, lens, optic disc, optic nerve, retina, and tumor at eight standard treatment positions. The equation of Dale and Jones was employed to create biologically effective dose volume histograms (BEDVHs), allowing for BED volumetric analysis of all ROIs. Isobiologically effective prescription doses were calculated for T = 5 days down to 0.01 days, with BEDVHs subsequently generated for all ROIs using correspondingly reduced prescription doses. Objective functions were created to evaluate the BEDVHs as a function of R and T. These objective functions are mathematically accessible and sufficiently general to be applied to temporary or permanent brachytherapy implants for a variety of disease sites. Results: Reducing T from 7 to 0.01 days for a 10 mm plaque produced an average BED benefit of 26%, 20%, and 17% for {sup 103}Pd, {sup 125}I, and {sup 131}Cs, respectively, for all P; 16 and 22 mm plaque results were more position-dependent. {sup 103}Pd produced a 16%-35% BED benefit over {sup 125}I, whereas {sup 131}Cs produced a 3%-7% BED detriment, independent of P, T, and plaque size. Additionally, corresponding organ at risk physical doses were lowest using {sup 103}Pd in all circumstances. Conclusions: The results suggest that shorter implant durations may correlate with more favorable outcomes compared to 7 day implants when treating small or medium intraocular lesions. The data also indicate that implant duration may be safely reduced if the prescription physical dose is likewise diminished and that {sup 103}Pd offers a substantial radiobiological benefit over {sup 125}I and {sup 131}Cs irrespective of plaque position, implant duration, and tumor size.

Gagne, Nolan L.; Leonard, Kara L.; Rivard, Mark J. [Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States)

2012-06-15

364

Thin-film rupture for large slip  

Microsoft Academic Search

The rupture of thin liquid films on hydrophobic substrates, assuming large slip at the liquid-solid interface, is studied\\u000a using a recently developed strong slip lubrication model, it is shown that the rupture passes through up to three self-similar regimes with different dominant balances\\u000a and different scaling exponents. For one of these regimes the similarity is of second kind, and the

D. Peschka; A. Münch; B. Niethammer

2010-01-01

365

Left Ventricular Rupture Post Mitral Valve Replacement  

PubMed Central

Prevention is better than cure best applies here. As per many authors, posterior leaflet chordae preservation prevent Left ventricular rupture (LVR) and preserve LV geometry. We are presenting here 5 types of left ventricular rupture (LVR) post Mitral valve replacement (MVR) with different methods to repair with the advantages and disadvantages of each. The mortality rate is still very high despite the advances in cardiac surgery. Many therapeutic approaches have been adopted. Yet, none is ideal.

Sersar, Sameh I.; Jamjoom, Ahmed A.

2009-01-01

366

Ultrashort echo time cardiovascular magnetic resonance of atherosclerotic carotid plaque  

Microsoft Academic Search

BACKGROUND: Multi-contrast weighted cardiovascular magnetic resonance (CMR) allows detailed plaque characterisation and assessment of plaque vulnerability. The aim of this preliminary study was to show the potential of Ultra-short Echo Time (UTE) subtraction MR in detecting calcification. METHODS: 14 ex-vivo human carotid arteries were scanned using CMR and CT, prior to histological slide preparation. Two images were acquired using a

Cheuk F Chan; Niall G Keenan; Sonia Nielles-Vallespin; Peter Gatehouse; Mary N Sheppard; Joseph J Boyle; Dudley J Pennell; David N Firmin

2010-01-01

367

Molecular MRI of Atherosclerotic Plaque With Targeted Contrast Agents  

PubMed Central

Molecular MRI of atherosclerosis involves the use of novel contrast agents to image cellular and molecular processes within atherosclerotic plaque. Agents to image plaque lipid content, inflammation, angiogenesis, and thrombosis have been developed and studied extensively in animal models of atherosclerosis and vascular injury. Selected agents have also been studied in humans, with highly promising initial results. In this brief review, recent advances as well as opportunities and challenges in the field are discussed.

Sosnovik, David E.; Caravan, Peter

2009-01-01

368

Identification of Autoantigens in Psoriatic Plaques Using Expression Cloning  

Microsoft Academic Search

To search for autoantigens in psoriatic plaques, we screened cDNA libraries of plaque epidermis with psoriatic serum samples. This approach has been highly successful in identifying tumor antigens, but has not been widely applied to autoimmune disease. We identified 11 autoantigens including three with prominent reactivity and plausible disease relevance. These are keratin 13 (K13), heterogeneous nuclear ribonucleoprotein-A1 (hnRNP-A1), and

David A. Jones; Nikhil Yawalkar; Ki-Young Suh; Sara Sadat; Benjamin Rich; Thomas S. Kupper

2004-01-01

369

Lipid-Rich Plaque Masquerading as a Coronary Thrombus  

PubMed Central

A 43-year-old woman presented with exertional chest pressure. Right coronary angiography showed a clear filling defect. Intravascular ultrasound revealed a plaque with 80% stenosis and a large lipid pool. Therefore, a stent was placed, and the patient became angina-free. Lipid-rich plaques are a cause of angiographic filling defects. Intravascular ultrasound is an integral part of coronary artery evaluation.

Rezkalla, Shereif H.; Holmes, David R.

2006-01-01

370

Tryptase Promotes Atherosclerotic Plaque Haemorrhage in ApoE-/- Mice  

PubMed Central

Tryptase, the most abundant mast cell (MC) granule protein, plays an important role in atherosclerosis plaque development. To test the hypothesis that tryptase participates directly in atherosclerosis plaque haemorrhage, the gene sequence and siRNA for tryptase were cloned into a lentivirus carrier and atherosclerosis plaque haemorrhage models in ApoE-/- mice were constructed. After a cuffing-cervical artery operation, the mice were randomly divided into 6 groups. Hematoxylin and eosin(HE) staining showed that the cervical artery plaque area was much larger in the tryptase overexpression group compared to the other groups, and there was greater artery stenosis. The artery stenosis from the cuff-side in all groups was more than 90%, except the siRNA group. Tryptase promotes plaque haemorrhage distinctively because 50% of the mice in the tryptase overexpression group had plaque haemorrhage, while only 10% in the siRNA group did. The immunohistochemistry of the cervical artery plaque showed that plasminogen activator inhibitor-1 (PAI-1) expression was the lowest while tissue plasminogen activator (tPA), CD31, CD34 and VEGF was the highest in the tryptase overexpression groups. This observation was completely contrary to what was observed in the siRNA group. Tryptase promoted bEnd.3 cell growth, migration and capillary-like tube formation, which suggests that tryptase can promote microvessel angiogenesis. PAI-1 expression was inhibited, while tPA expression was increased by tryptase in bEnd.3 cells. Our in vivo and in vitro studies suggest that trypase can promote atherosclerotic plaque haemorrhage by promoting angiogenesis and regulating the balance of PAI-1 and tPA. Thus, regulating tryptase expression in MCs may provide a potential target for atherosclerosis treatment.

Tian, Dai; Li, Xiaobo; Ning, Yanxia; Yin, Lianhua

2013-01-01

371

The Concomitant Deposition of Strontium and Fluoride in Dental Plaque  

Microsoft Academic Search

We have investigated the feasibility of incorporating Sr into dental plaque by means of an enzyme-dependent system known to increase Ca, P, and F levels in plaque. A solution containing Ca (20 mmoll L), P (12 mmol\\/L), MFP (4.7 mmol\\/L), F (0.3 mmol\\/L), and urea (500 mmol\\/L) was modified by equimolar replacement of Ca with 1, 2, 5, and 10

E. I. F. Pearce; C. H. Sissons

1987-01-01

372

Detail of plaque beneath column on the south parapet at ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Detail of plaque beneath column on the south parapet at the west end of the bridge. The plaque reads ?1914; Mayor E.J. Drussel; Councilmen E.S. Henry, E.F. Hogan, R.P. Lamdin, C.F. Ross, J.H. Shuppert; Leonard & Day, Engineers; C.H. Gildersleeve, Builder.? - First Street Bridge, Spanning Napa River at First Street between Soscol Avenue & Juarez Street, Napa, Napa County, CA

373

Antibacterial effect of taurolidine (2%) on established dental plaque biofilm  

Microsoft Academic Search

Preliminary data have suggested that taurolidine may bear promising disinfectant properties for the therapy of bacterial infections.\\u000a However, at present, the potential antibacterial effect of taurolidine on the supragingival plaque biofilm is unknown. To\\u000a evaluate the antibacterial effect of taurolidine on the supragingival plaque biofilm using the vital fluorescence technique\\u000a and to compare it with the effect of NaCl and

Nicole Birgit Arweiler; Thorsten Mathias Auschill; Anton Sculean

374

Methotrexate toxicity presenting as cutaneous ulcerations on psoriatic plaques.  

PubMed

Methotrexate (MTX) is an effective but potentially toxic treatment for psoriasis. We describe a patient who administered 20?mg daily of MTX for 5?d and presented with ulcerated and necrotic lesions on the psoriatic plaques, mouth erosions and hair loss. However, his psoriatic plaques and ulcerations totally healed rapidly within two weeks and no recurrence has been observed for the 6 months of follow up. PMID:23537374

Koçak, Asl?han Yonca; Koçak, O?uzhan; Aslan, Figen; Tekta?, Mustafa

2013-10-01

375

P231Molecular and cellular components of human carotid artery plaque related to thrombogenicity.  

PubMed

Atherosclerosis is a dynamic progressive disease of the large arteries characterized by accumulation of lipids, inflammatory and smooth muscle cells (SMCs) and extracellular matrix. In situ growth or embolization of arterial thrombi following a plaque rupture may lead to acute coronary syndrome and stroke. Fibrous cap rupture may expose thrombogenic material, initiating platelet aggregation and coagulation pathways. These thrombotic changes result from activation of the clotting cascade by tissue factor (TF) and coagulation contact phase. Aim of the project is to study Carotid Plaque (CP) thrombogenicity and the vascular wall components responsible for thrombus formation. CP (n=12) from patients submitted to endoarterectomy for significant stenosis and internal mammary artery fragments (n=4, controls not atherosclerotic) from individuals undergoing coronary artery bypass surgery were snap-frozen and sectioned. Thrombogenesis induced by CP was evaluated ex-vivo under flow conditions using healthy volunteer blood drawn into citrate anticoagulant. Recalcified blood was perfused over CP cryosections at constant flow velocity and 37 °C, and the volume of platelet aggregates and fibrin deposited onto the surface was measured in real time by confocal videomicroscopy. The areas with same XY coordinates than those analyzed in blood flow experiments were relocalized in serial cryosections, to identify by histology (Movat's, Hematoxylin/Eosin) and confocal microscopy the vascular cell phenotypes and wall components involved in thrombus formation. Thrombi formed mainly over endothelium/intima layer (including fibrous cap); were abundant in the media rich in SMC and in foam cells, in the presence of FSP1, collagen type I, proteoglycans, fibrinogen and TF. The fibro-necro-calcific core was quite unreactive, except when TF was present. IMA wall layers were reactive with analogous pattern but showed a different amount of thrombus formation. Addition to blood before perfusion of anti-human TF monoclonal antibody, or antibody blocking factor XI activation, or a combination of them reduced the volume of platelet aggregates, and of fibrin to a different extent in the different vascular layers. These data suggest an in-situ role of vascular cells and matrix, as well as of intra-tissue TF in thrombus formation over CP, involving both TF and contact phase coagulation pathways. PMID:25020646

Foglieni, C; Marchese, P; Lombardi, M; Mantione, Me; Baccellieri, D; Ferrara, D; Castellano, R; Kamami, K; Ruf, W; Ruggeri, Zm

2014-07-15

376

Splenic artery aneurysm rupture in pregnancy.  

PubMed

Splenic artery aneurysm (SAA) is the commonest visceral artery aneurysm. It is diagnosed more frequently in younger women, with up to 95% presenting during pregnancy. Rupture is associated with a disproportionately high maternal and fetal mortality. We performed a literature search on the patient and SAA characteristics, clinical presentations, management and outcome of this serious complication. There were 32 patients in total with a mean age of 27.9 years (range 20-38). The mean SAA size was 2.25 cm (range 0.5-4 cm) and from the available data half of the ruptured SAA were 2 cm or less. Only one case (3.1%) was discovered incidentally, whilst the rest (96.9%) were found following rupture. The majority ruptured spontaneously. Most (62%) of the patients underwent SAA ligation and splenectomy. The maternal death rate was 21.9% (n=7), and fetal death rate was 15.6% (n=5). Most cases are not diagnosed until surgery following rupture. Ruptured SAA should be considered in the differential diagnosis of a pregnant patient with severe and unexplained abdominal pain. PMID:19596508

Ha, Jennifer Fong; Phillips, Michael; Faulkner, Kingsley

2009-10-01

377

Phenotypic modulation of macrophages in response to plaque lipids  

PubMed Central

Purpose of review The accumulation of macrophages in the vascular wall is a hallmark of atherosclerosis. The biological properties of atherosclerotic plaque macrophages determine lesion size, composition and stability. In atherosclerotic plaques, macrophages encounter a microenvironment that is comprised of a variety of lipid oxidation products, each of which has diverse biological effects. In this review, we summarize recent advances in our understanding of the effects of plaque lipids on macrophage phenotypic polarization. Recent findings Atherosclerotic lesions in mice and in humans contain various macrophage phenotypes, which play different roles in mediating inflammation, the clearance of dead cells, and possibly resolution. Macrophages alter their phenotype and biological function in response to plaque lipids through the upregulation of specific sets of genes. Interaction of oxidized lipids with pattern recognition receptors and activation of the inflammasome by cholesterol crystals drive macrophages towards an inflammatory M1 phenotype. A new phenotype, Mox, develops when oxidized phospholipids activate stress response genes via Nrf2. Other lipid mediators such as nitrosylated-fatty acids and omega-3 fatty acid-derived products polarize plaque macrophages towards anti-inflammatory and proresolving phenotypes. Summary A deeper understanding of how lipids that accumulate in atherosclerotic plaques affect macrophage phenotype and function and thus atherosclerotic lesion development and stability will help to devise novel strategies for intervention.

Adamson, Samantha; Leitinger, Norbert

2014-01-01

378

Reproducibility of IVUS Border Detection for Carotid Atherosclerotic Plaque Assessment  

PubMed Central

Plaque composition is a potentially important diagnostic feature for carotid artery stenting (CAS). The purpose of this investigation is to evaluate the reproducibility of manual border correction in intravascular ultrasound with virtual histology (VH IVUS) images. Three images each were obtained from 51 CAS datasets on which automatic border detection was corrected manually by two trained observers. Plaque was classified using the definitions from the CAPITAL (Carotid Artery Plaque Virtual Histology Evaluation) study, listed in order from least to most pathological: no plaque, pathological intimal thickening, fibroatheroma, fibrocalcific, calcified fibroatheroma, thin-cap fibroatheroma, and calcified thin-cap fibroatheroma. Inter-observer variability was quantified using both weighted and unweighted Kappa statistics. Bland-Altman analysis was used to compare the cross-sectional areas of the vessel and lumen. Agreement using necrotic core percentage as the criterion was evaluated using the unweighted Kappa statistic. Agreement between classifications of plaque type was evaluated using the weighted Kappa statistic. There was substantial agreement between the observers based on necrotic core percentage (? = 0.63), while the agreement was moderate (?quadratic = 0.60) based on plaque classification. Due to the time-consuming nature of manual border detection, an improved automatic border detection algorithm is necessary for using VH IVUS as a diagnostic tool for assessing the suitability of patients with carotid artery occlusive disease for CAS.

Siewiorek, Gail M.; Loghmanpour, Natasha A.; Winston, Brion M.; Wholey, Mark H.; Finol, Ender A.

2011-01-01

379

Preliminary study of the detectability of coronary plaque with PET  

NASA Astrophysics Data System (ADS)

The evaluation of coronary plaque vulnerability could be of great diagnostic value in cardiology. Positron emission tomography (PET) is a good candidate due to its ability to quantify micromolar concentrations of targeted drugs. However, the detectability of sub-voxel targets such as coronary plaque is limited by partial volume effects and by cardiorespiratory motion. The goal of this paper is to investigate the impact of these factors in the detectability of plaque uptake. Radioactive markers were implanted on the epicardium of a pig and in vivo scans were performed. This was complemented with phantom measurements to determine the minimum detectable uptake as a function of background activity. Simulations were used to evaluate the effect of cardiorespiratory motion on the reconstructed lesions. Despite cardiorespiratory motion of up to 7 mm, the markers were detectable in the in vivo scans even after the injection of background. A lower limit of 250 Bq was found for a target to be detectable. Motion reduced the contrast of the reconstructed lesions to 23% of their static counterpart. Respiratory gating improved this to 49% of the static value. The results suggest that coronary plaque evaluation with PET is possible, provided that sufficient plaque-to-myocardium uptake contrast (50 to 100) can be achieved. This requirement increases exponentially for lesions with uptake below 250 Bq. The described experiments provide a means of estimating the minimum uptake and contrast required to ensure the detectability of plaque lesions.

Delso, G.; Martinez-Möller, A.; Bundschuh, R. A.; Nekolla, S. G.; Ziegler, S. I.; Schwaiger, M.

2011-04-01

380

Expression of lipoprotein-associated phospholipase A2 in carotid artery plaques predicts long-term cardiac outcome  

PubMed Central

Aims The aim was to test the hypothesis that carotid artery plaque expression of lipoprotein-associated phospholipase A2 (Lp-PLA2) predicts cardiac events. Methods and results Prospective cohort study of 162 consecutive patients undergoing elective carotid endarterectomy. Lipoprotein-associated phospholipase A2 content was quantified by immunoblotting and lysophosphatidylcholine (lysoPC) by liquid chromatography tandem mass spectrometry. Additional biomolecular profiling by immunoblotting included C-reactive protein, p67phox, and matrix metalloproteinase-2 and -9. Macrophage plaque content was determined by quantitative immunostaining, plaque collagen content by quantitative Sirius red staining. Follow-up for cardiac death and non-fatal acute myocardial infarction was accomplished over a period of 48 ± 14 months. Expression of Lp-PLA2 and lysoPC was higher in carotid plaques of patients with than without cardiac events [median 1.6 (25th, 75th percentile 0.9, 2.5) vs. 0.8 (0.5, 2.0), P = 0.01 and 413 (281, 443) vs. 226 (96, 351) mmol/L, P = 0.03]. Smoking and point increase in carotid Lp-PLA2 expression but no other traditional cardiovascular risk factor, histological or molecular marker remained predictive of cardiac events in the multivariate Cox proportional hazard analyses [HR 3.65 (1.36–9.83), P = 0.01 and HR 1.34 (1.01–1.77), P = 0.039]. Carotid plaque Lp-PLA2 expression above the median constituted a more than three times higher risk for cardiac events [HR 3.39 (1.13–10.17), P = 0.03]. Conclusion Lipoprotein-associated phospholipase A2 expression in carotid artery plaques is a predictor of long-term cardiac outcome. The current study supports the concept of atherosclerosis as a systemic disease with multi-focal complications and personalized medicine.

Herrmann, Joerg; Mannheim, Dallit; Wohlert, Christine; Versari, Daniele; Meyer, Fredric B.; McConnell, Joseph P.; Gossl, Mario; Lerman, Lilach O.; Lerman, Amir

2009-01-01

381

Current concept of partial anterior cruciate ligament ruptures.  

PubMed

A partial tear of the anterior cruciate ligament is a frequent pattern of ACL injury, observed in 10 to 27% of isolated ACL lesions. There are three reasons to preserve these remnants: biomechanical, vascular and proprioceptive advantages for the patient. Good quality fibers work as graft protection during the healing process. Periligamentous and endoligamentous vessels present into the native ACL tissue may enhance the vascularization of the ACL augmentation. Mechanoreceptors still remaining in the residual ACL fibers may have proprioceptive function. Definition is controversial, based on anatomy, on clinical examination, on instrumental laxity assessment or on MRI findings. Continuous remnant ACL fibers bridging the femur and tibia, from native femoral ACL footprint to native tibial ACL footprint seem to be a good definition. Diagnostic is suspected by accumulation of arguments brought by a thorough clinical examination, precise MRI analysis and examination under anesthesia. But the final diagnostic needs an arthroscopic evaluation to confirm the presence of fibers in good position and to validate its good mechanical properties. The treatment of ACL partial tear is a demanding surgery; difficulties to visualize the graft insertion site, especially on the femoral side, require a perfect knowledge of the normal anatomy of the native ACL footprint. Adapted portals, perfect controls of the tunnel drilling process, intercondylar notch space management are the keys of success. The pivot shift test under anesthesia, a hard stop Lachman test, MRI findings, level and type of sport, arthroscopic aspects of the remnants and its mechanical properties, allow the surgeon decide between non operative treatment, ACL augmentation or standard ACL reconstruction. PMID:21056025

Colombet, P; Dejour, D; Panisset, J-C; Siebold, R

2010-12-01

382

Spontaneous rupture of spleen masquerading as acute pancreatitis.  

PubMed

Splenic rupture most commonly follows blunt abdominal trauma. Nontraumatic rupture of the spleen is rare. Nontraumatic rupture of the spleen has been described in a variety of pathologic conditions, which include neoplastic, infectious, and hematologic diseases affecting the spleen. Spontaneous rupture of nondiseased spleen is extremely rare. We report a case of spontaneous rupture of spleen in a chronic alcoholic clinically simulating acute pancreatitis. PMID:24268850

Debnath, Jyotindu; Sonkar, Samrat; Sharma, Vivek; Chatterjee, Samar; Srivastava, Vikash; Khanna, Shiv Pankaj

2014-04-01

383

Methodology for fully automated segmentation and plaque characterization in intracoronary optical coherence tomography images.  

PubMed

Optical coherence tomography (OCT) is a light-based intracoronary imaging modality that provides high-resolution cross-sectional images of the luminal and plaque morphology. Currently, the segmentation of OCT images and identification of the composition of plaque are mainly performed manually by expert observers. However, this process is laborious and time consuming and its accuracy relies on the expertise of the observer. To address these limitations, we present a methodology that is able to process the OCT data in a fully automated fashion. The proposed methodology is able to detect the lumen borders in the OCT frames, identify the plaque region, and detect four tissue types: calcium (CA), lipid tissue (LT), fibrous tissue (FT), and mixed tissue (MT). The efficiency of the developed methodology was evaluated using annotations from 27 OCT pullbacks acquired from 22 patients. High Pearson's correlation coefficients were obtained between the output of the developed methodology and the manual annotations (from 0.96 to 0.99), while no significant bias with good limits of agreement was shown in the Bland-Altman analysis. The overlapping areas ratio between experts' annotations and methodology in detecting CA, LT, FT, and MT was 0.81, 0.71, 0.87, and 0.81, respectively. PMID:24525828

Athanasiou, Lambros S; Bourantas, Christos V; Rigas, George; Sakellarios, Antonis I; Exarchos, Themis P; Siogkas, Panagiotis K; Ricciardi, Andrea; Naka, Katerina K; Papafaklis, Michail I; Michalis, Lampros K; Prati, Francesco; Fotiadis, Dimitrios I

2014-02-01

384

Epithelial cell pro-inflammatory cytokine response differs across dental plaque bacterial species  

PubMed Central

Aim The dental plaque is comprised of numerous bacterial species which may or may not be pathogenic. Human gingival epithelial cells (HGECs) respond to perturbation by various bacteria of the dental plaque by production of different levels of inflammatory cytokines which is a putative reflection of their virulence. The aim of the current study was to determine responses in terms of IL-1?, IL-6, IL-8 and IL-10 secretion induced by Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Streptococcus gordonii in order to gauge their virulence potential. Materials and Methods HGECs were challenged with the four bacterial species, live or heat-killed, at various MOIs (multiplicity of infection) and the elicited IL-1?, IL-6, IL-8 and IL-10 responses were assayed by ELISA. Results Primary HGECs challenged with live P. gingivalis produced high levels of IL-1?, while challenge with live A. actinomycetemcomitans gave high levels of IL-8. The opportunistic pathogen F. nucleatum induces the highest levels of pro-inflammatory cytokines, while the commensal S. gordonii is the least stimulatory. Conclusion We conclude that various dental plaque biofilm bacteria induce different cytokine response profiles in primary human gingival epithelial cells that may reflect their individual virulence or commensal status.

Stathopoulou, Panagiota G.; Benakanakere, Manjunatha R.; Galicia, Johnah C.; Kinane, Denis F.

2010-01-01

385

Altered microglial response to A? plaques in APPPS1-21 mice heterozygous for TREM2  

PubMed Central

Background Recent genome-wide association studies linked variants in TREM2 to a strong increase in the odds of developing Alzheimer’s disease. The mechanism by which TREM2 influences the susceptibility to Alzheimer’s disease is currently unknown. TREM2 is expressed by microglia and is thought to regulate phagocytic and inflammatory microglial responses to brain pathology. Given that a single allele of variant TREM2, likely resulting in a loss of function, conferred an increased risk of developing Alzheimer’s disease, we tested whether loss of one functional trem2 allele would affect A? plaque deposition or the microglial response to A? pathology in APPPS1-21 mice. Results There was no significant difference in A? deposition in 3-month old or 7-month old APPPS1-21 mice expressing one or two copies of trem2. However, 3-month old mice with one copy of trem2 exhibited a marked decrease in the number and size of plaque-associated microglia. While there were no statistically significant differences in cytokine levels or markers of microglial activation in 3- or 7-month old animals, there were trends towards decreased expression of NOS2, C1qa, and IL1a in 3-month old TREM2+/? vs. TREM2+/+ mice. Conclusions Loss of a single copy of trem2 had no effect on A? pathology, but altered the morphological phenotype of plaque-associated microglia. These data suggest that TREM2 is important for the microglial response to A? deposition but that a 50% decrease inTREM2 expression does not affect A? plaque burden.

2014-01-01

386

The Development and Potential of Acoustic Radiation Force Impulse (ARFI) Imaging for Carotid Artery Plaque Characterization  

PubMed Central

Stroke is the third leading cause of death and long-term disability in the U.S. Currently, surgical intervention decisions in asymptomatic patients are based upon the degree of carotid artery stenosis. While there is a clear benefit of endarterectomy for patients with severe (>70%) stenosis, in those with high/moderate (50–69%) stenosis the evidence is less clear. Evidence suggests ischemic stroke is associated less with calcified and fibrous plaques than with those containing softer tissue, especially when this it is accompanied by a thin fibrous cap. A reliable mechanism for the identification of individuals with atherosclerotic plaques which confer the highest risk for stroke is fundamental to the selection of patients for vascular interventions. Acoustic Radiation Force Impulse (ARFI) imaging is a new ultrasonic-based imaging method that characterizes the mechanical properties of tissue by measuring displacement resulting from applied short duration acoustic radiation force. These displacements provide information about the local mechanical properties of tissue and can differentiate between soft and hard areas. Because arterial walls, soft tissue, atheromas, and calcifications have a wide range in their stiffness properties, they represent excellent candidates for ARFI imaging. We present information from early phantom experiments and excised human limb studies to in vivo carotid artery scans and provide evidence for the ability of ARFI to provide high quality images which highlight mechanical differences in tissue stiffness not readily apparent in matched B-mode images. This allows ARFI to identify soft from hard plaques and differentiate characteristics associated with plaque vulnerability or stability.

Allen, Jason D.; Ham, Katherine L.; Dumont, Douglas M.; Sileshi, Bantayehu; Trahey, Gregg E.; Dahl, Jeremy J.

2012-01-01

387

Microglial cells are the driving force in fibrillar plaque formation, whereas astrocytes are a leading factor in plaque degradation  

Microsoft Academic Search

Ultrastructural three-dimensional reconstruction of human classical plaques in different stages of development shows that\\u000a microglial cells are the major factor driving plaque formation by fibrillar amyloid-? (A?) deposition. The amount of fibrillar\\u000a A? released by microglial cells and the area of direct contact between amyloid and neuron determine the extent of dystrophic\\u000a changes in neuronal processes and synapses. The volume

Jerzy Wegiel; Kuo-Chiang Wang; Michal Tarnawski; Boleslaw Lach

2000-01-01

388

Recurrent uterine rupture after hysterescopic resection of the uterine septum  

PubMed Central

INTRODUCTION Uterine rupture after hysteroscopic septum resection is a rare complication, and its frequency is reported to be approximately 1–2.7%. Uterine perforation and monopolar resection during hysteroscopy are well-known risk factors for subsequent uterine rupture during pregnancy. PRESENTATION OF CASE We present a case of recurrent uterine ruptures during consecutive pregnancies in a patient who had undergone hysteroscopic septum resection for recurrent pregnancy loss. DISCUSSION Recurrent uterine rupture due to hysteroscopic septum resection in pregnancy is a very rare condition. In the present case we noted that the first two uterine ruptures resulted from uterine contractions; however, the third rupture occurred spontaneously and earlier in gestation. As each uterine rupture occurred earlier than the rupture in the previous gestation, a history of uterine rupture during pregnancy should raise provider suspicion about the possibility of earlier uterine rupture recurrence. CONCLUSION Uterine rupture may occur in pregnancies after hysteroscopic resection of the uterine septum. However, if a patient has a history of uterine rupture during previous pregnancies, the risk of uterine rupture may increase for earlier gestational ages in subsequent pregnancies. The patient must be informed about both the risks of uterine rupture during pregnancy after hysteroscopic septum resection and that recurrent ruptures may occur at earlier gestational weeks than during previous pregnancies.

Ergenoglu, Mete; Yeniel, Ahmet Ozgur; Y?ld?r?m, Nuri; Akdemir, Ali; Yucebilgin, Sait

2012-01-01

389

Differential X-ray phase contrast tomography of Alzheimer plaques in mouse models: perspectives for drug development and clinical imaging techniques  

NASA Astrophysics Data System (ADS)

Alzheimer's disease (AD) is a looming threat on an ever-ageing population, with devastating effects on the human intellect. A particular characteristic lesion — the extracellular amyloid plaque — accumulates in the brain of AD patients during the course of the disease, and could therefore be used to monitor the progression of the disease, years before the first neurological symptoms appear. In addition, strategies for drug intervention in AD are often based on amyloid reduction, since amyloid plaques are hypothesized to be involved in a chain of reactions leading to the death of neurons. Developments in both fields would benefit from a microscopic technique that is capable of single plaque imaging, ideally in 3D. While such a non-destructive, single-plaque imaging technique does not yet exist for humans, it has been recently shown that synchrotron based differential X-ray phase contrast imaging can be used to visualize individual plaques at ?m resolution in mouse models of AD ex-vivo. This method, which relies on a grating interferometer to measure refraction angles induced by fluctuations in the refractive index, yields a precise three-dimensional distribution of single plaques. These data could not only improve the understanding of the evolution of AD or the effectiveness of drugs, but could also help to improve reliable markers for current and future non-invasive clinical imaging techniques. In particular, validation of PET markers with small animal models could be rapidly carried out by co-registration of PET and DPC signals.

Pinzer, B. R.; Cacquevel, M.; Modregger, P.; Thuering, T.; Stampanoni, M.

2013-05-01

390

A direct vulnerable atherosclerotic plaque elasticity reconstruction method based on an original material-finite element formulation: theoretical framework.  

PubMed

The peak cap stress (PCS) amplitude is recognized as a biomechanical predictor of vulnerable plaque (VP) rupture. However, quantifying PCS in vivo remains a challenge since the stress depends on the plaque mechanical properties. In response, an iterative material finite element (FE) elasticity reconstruction method using strain measurements has been implemented for the solution of these inverse problems. Although this approach could resolve the mechanical characterization of VPs, it suffers from major limitations since (i) it is not adapted to characterize VPs exhibiting high material discontinuities between inclusions, and (ii) does not permit real time elasticity reconstruction for clinical use. The present theoretical study was therefore designed to develop a direct material-FE algorithm for elasticity reconstruction problems which accounts for material heterogeneities. We originally modified and adapted the extended FE method (Xfem), used mainly in crack analysis, to model material heterogeneities. This new algorithm was successfully applied to six coronary lesions of patients imaged in vivo with intravascular ultrasound. The results demonstrated that the mean relative absolute errors of the reconstructed Young's moduli obtained for the arterial wall, fibrosis, necrotic core, and calcified regions of the VPs decreased from 95.3 ± 15.56%, 98.85 ± 72.42%, 103.29 ± 111.86% and 95.3 ± 10.49%, respectively, to values smaller than 2.6 × 10(-8) ± 5.7 × 10(-8)% (i.e. close to the exact solutions) when including modified-Xfem method into our direct elasticity reconstruction method. PMID:24240392

Bouvier, Adeline; Deleaval, Flavien; Doyley, Marvin M; Yazdani, Saami K; Finet, Gérard; Le Floc'h, Simon; Cloutier, Guy; Pettigrew, Roderic I; Ohayon, Jacques

2013-12-01

391

Antibacterial effect of taurolidine (2%) on established dental plaque biofilm.  

PubMed

Preliminary data have suggested that taurolidine may bear promising disinfectant properties for the therapy of bacterial infections. However, at present, the potential antibacterial effect of taurolidine on the supragingival plaque biofilm is unknown. To evaluate the antibacterial effect of taurolidine on the supragingival plaque biofilm using the vital fluorescence technique and to compare it with the effect of NaCl and chlorhexidine (CHX), 18 subjects had to refrain from all mechanical and chemical hygiene measures for 24 h. A voluminous supragingival plaque sample was taken from the buccal surfaces of the lower molars and wiped on an objective slide. The sample was then divided into three equal parts and mounted with one of the three test or control preparations (a) NaCl, (b) taurolidine 2% and (c) CHX 0.2%. After a reaction time of 2 min, the test solutions were sucked of. Subsequently, the plaque biofilm was stained with fluorescence dye and vitality of the plaque flora was evaluated under the fluorescence microscope (VF%). Plaque samples treated with NaCl showed a mean VF of 82.42?±?6.04%. Taurolidine affected mean VF with 47.57?±?16.60% significantly (p?plaque biofilm which was, however, not as pronounced as that of CHX. PMID:21360105

Arweiler, Nicole Birgit; Auschill, Thorsten Mathias; Sculean, Anton

2012-04-01

392

Survival of human dental plaque flora in various transport media.  

PubMed

Dental plaque samples from (i) subjects with no apparent oral disease, (ii) mentally retarded subjects with periodontal disease, and (iii) subjects with active caries were collected in three transport media viz. a dithiothreitol poised balanced mineral salt solution designated as reduced transport fluid (RTF), VMG II, and modified Stuart medium (SBL). The samples were dispersed by sonic treatment, diluted in the respective medium in which they were collected, and cultured on MM10 sucrose agar. The efficiency of the transport media in the survival of dental plaque flora was determined by comparing the quantitative recovery (expressed as percentage of the initial viable count) from the specimens stored for various lengths of time. The data showed a great variation in the recovery of the oral bacterial flora from the plaque samples. VMG II and SBL served better than RTF as storage media for non-disease-associated dental plaque cultured under strict anaerobic conditions. Recoveries of bacteria from periodontal plaque specimens stored in RTF were higher than SBL and VMG II under identical conditions. The organisms present in the carious plaque samples appeared to survive much better in RTF and VMG II than in SBL as determined by conventional anaerobic culturing technique. However, VMG II showed a higher recovery of organisms from these specimens with an increase in the storage period, suggesting multiplication of the plaque flora. RTF did not allow the growth of oral bacterial flora under all experimental conditions. On the basis of the relative performance of these media it is suggested that RTF is a satisfactory medium for the transport of oral bacteria present in the samples. PMID:4628799

Syed, S A; Loesche, W J

1972-10-01

393

Survival of Human Dental Plaque Flora in Various Transport Media  

PubMed Central

Dental plaque samples from (i) subjects with no apparent oral disease, (ii) mentally retarded subjects with periodontal disease, and (iii) subjects with active caries were collected in three transport media viz. a dithiothreitol poised balanced mineral salt solution designated as reduced transport fluid (RTF), VMG II, and modified Stuart medium (SBL). The samples were dispersed by sonic treatment, diluted in the respective medium in which they were collected, and cultured on MM10 sucrose agar. The efficiency of the transport media in the survival of dental plaque flora was determined by comparing the quantitative recovery (expressed as percentage of the initial viable count) from the specimens stored for various lengths of time. The data showed a great variation in the recovery of the oral bacterial flora from the plaque samples. VMG II and SBL served better than RTF as storage media for non-disease-associated dental plaque cultured under strict anaerobic conditions. Recoveries of bacteria from periodontal plaque specimens stored in RTF were higher than SBL and VMG II under identical conditions. The organisms present in the carious plaque samples appeared to survive much better in RTF and VMG II than in SBL as determined by conventional anaerobic culturing technique. However, VMG II showed a higher recovery of organisms from these specimens with an increase in the storage period, suggesting multiplication of the plaque flora. RTF did not allow the growth of oral bacterial flora under all experimental conditions. On the basis of the relative performance of these media it is suggested that RTF is a satisfactory medium for the transport of oral bacteria present in the samples.

Syed, Salam A.; Loesche, Walter J.

1972-01-01

394

Association between Variations in Coagulation System Genes and Carotid Plaque  

PubMed Central

Objective Genetic variation in coagulation and fibrinolysis may affect the development of subclinical atherosclerosis modifying the risk of stroke and cardiovascular disease. However, data on the relationship between subclinical atherosclerosis and genes involved in the coagulation system are sparse. The objective of this study is to examine the association between single nucleotide polymorphisms (SNPs) in coagulation system genes and subclinical carotid plaque phenotypes. Methods From the Genetic Determinants of Subclinical Carotid Disease study, 287 Dominicans were examined for carotid plaque presence, thickness, and surface irregularity by high-resolution B-mode carotid ultrasound. Logistic regression was used to test for association between 101 SNPs in 23 coagulation system genes and plaque phenotypes while controlling for age, sex, smoking, hypertension, dyslipidemia, and diabetes. Within gene haplotypes and interactions between genes were examined. A follow-up of SNPs in moderate to high (r2>0.25) linkage disequilibrium (LD) with those implicated in the discovery analysis (p?0.01) was performed in an independent sample of 301 Dominicans. Results The prevalence of carotid plaque (47% discovery; 46% follow-up) as well as the mean age (65±8 discovery; 65±9 follow-up) of the participants was similar in both datasets. Two genes (vWF and THBS1) were associated (p?0.01) with plaque size and surface irregularity. In followup, 5 SNPs in vWF were associated (p?0.05) with plaque size. SERPINE1 was an additional gene of interest in the haplotype and interaction analyses. Conclusions Variation in the vWF, THBS1, and SERPINE1 gene may play an important role in the pathogenesis of atherosclerotic plaque.

Della-Morte, David; Beecham, Ashley; Dong, Chuanhui; Wang, Liyong; McClendon, Mark S.; Gardener, Hannah; Blanton, Susan H.; Sacco, Ralph L.; Rundek, Tatjana

2012-01-01

395

The role of lipoprotein-associated phospholipase A2 on cardiovascular disease risk assessment and plaque rupture: a clinical review  

Microsoft Academic Search

During the last several last decades, reduction in lipids has been the main focus to decrease the risk of coronary heart disease (CHD). Several lines of evidence, however, have indicated that lipids account only for the <50% of variability in cardiovascular risk in the United States. Therefore, for better identification of people at high cardiovascular risk, a more effective and

Kota J. Reddy; Manmeet Singh; Joey R. Bangit; Richard R. Batsell

2009-01-01

396

Production of water drops and corona due to rupture of air bubbles at water surface under a positive dc electric field  

Microsoft Academic Search

The behavior of the surface of water after rupture of an air bubble under a positive dc electric field has been investigated, and the electric current of the corona discharge which occurs from the ruptured surface has been measured. A high-speed camera has revealed that fine droplets are subsequently ejected from the tip of the water jet formed by the

Toshiyuki Sugimoto; Yoshio Higashiyama

2001-01-01