Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Early atherosclerotic lesions in human aortas less than five hours postmortem were studied by light microscopy (20 cases) and electron microscopy (10 cases), to determine the morphological and cytochemical character of calcium deposition in the lesions. Routine and multiple special stains by light microscopy demonstrated atherosclerotic (intimal) calcium to be deposited as fine grains, ring-shaped droplets or small needle-shaped crystals, and medial calcium as fine grains or ring-shaped droplets. The calcium deposits were frequently associated with the PAS-positive basal lamina surrounding smooth muscle cells. In the intimal lesions the calcium deposits were often associated with fine granular lipid, while this association was much less frequent in the media. Calcium in atherosclerotic intima was generally not closely associated with elastic fibers but in the media was often deposited along or near elastic fibers. By electron microscopy the atherosclerotic lesions were composed of many smooth muscle cells (with or without lipid droplets), newly formed elastic fibers, amorphous ground substance, a few collagen fibrils and many membrane-limited matrix vesicle-like structures, 100-700 nm diameter. Many similar vesicles were present between the elastic laminae of the media. With the potassium pyroantimonate technique for demonstrating calcium, reaction products were most concentrated within these matrix vesicles but were also present in mitochondria of smooth muscle cells, within extracellular mitochondria-like structures, in pericellular basal lamina-like material and loosely dispersed in the interstitial ground substance. All elastic fibers were negative for calcium by this technique. The membrane of the matrix vesicle-like structures were cytochemically positive for alkaline phosphatase and adenosine triphosphatase. These studies suggest that calcification in human atherosclerosis and media is related to smooth muscle cell degeneration and that the major initial loci for calcium deposition are matrix vesicles from degraded cells, comparable to osteogenic calcification of cartilage.
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PMID:Calcification in atherosclerosis. I. Human studies. 294 18

Osteoporosis (OP) and atherosclerotic-cardiovascular diseases (and possibly dementia) constitute emerging age-related co-morbidity states that might share risk factors. Blood-born lipids, like LDL involved in atherosclerosis and apolipoprotein-E4 (ApoE4) involved in dementia, may also be implicated in development of OP. We examined osteoblast cell lines as a culture model for OP by exposure to lipoproteins. ApoE expression in Saos2 and U2OS osteoblasts was confirmed by PCR. ApoE4 did decrease cell counts relatively to ApoE3, especially in Saos2 cells in which it was less selective for cells with higher alkaline phosphatase (ALP, an osteoblast marker) activity than ApoE3. This associates with ApoE4, being a risk factor for both dementia and OP. Saos2, but not U2OS, showed a decrease in cell counts after 48 h exposure to native LDL (NLDL). Both cell lines had decreased cell counts already after 24 h when exposed to oxidized-LDL (OxLDL) for which Saos2 also showed a higher sensitivity than U2OS. Exposure of Saos2 to both, OxLDL at low concentration (5 microg/ml) and NLDL revealed a shrunken size cell fraction of 17-23% on the fluorescence-activated cell sorter (FACS) analysis. Such shrunken cell fraction was not seen when Saos2 cells were exposed to 50 microg/ml of OxLDL or to OxLDL combined with 10 nM dexamethasone (DEX, a stimulator of osteoprogenitor differentiation). DEX treatment has lysed the cells earlier than 24 h post exposure and has selected more resistant cells that did not show apoptotic shrinkage in the FACS analysis done after 24 h. We interpret this as a failure to detect the apoptotic cell fraction due to their lysis prior to the FACS analysis. Western blots performed at different time points (10 min, 30 min, 4 h, 24 h, and 48 h) under OxLDL + DEX revealed a fall in the positive regulator of pp60Src-kinase phosphotyrosine (pY)418 relative to the DEX controls during the first 4 h. This is consistent with DEX osteogenic induction, known to be negatively regulated by c-Src, although the pY418/pY529 ratios (negative/positive kinase regulation) fell only at the 10 min time point. Contrarily the pY418/pY529 ratio increased, relative to untreated controls, under 5 microg/ml and 50 microg/ml of NLDL at the 4 h time point and under 50 microg/ml NLDL only at the 10 min time point, being consistent with the ability of a higher dose of LDL to antagonize osteoblast differentiation. This could be even more acceptable if the NLDL would have become minimally oxidized during its long purification procedure. Under NLDL, the Bcl-2/Bax ratio was pro-apoptotic at 10 min, 30 min, and 4 h only under 50 microg/ml, whereas under OxLDL + DEX it was pro-apoptotic only after 4 h suggesting that additional pathways contribute to cell death. These results indicate that lipid effects on human osteoblast lines in culture may be used as a model to identify molecular targets shared between OP and atherosclerosis for intervention in this co-morbidity.
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PMID:Cell death in cultured human Saos2 osteoblasts exposed to low-density lipoprotein. 1293 55

Vascular calcification, long thought to result from passive degeneration, involves a complex, regulated process of biomineralization resembling osteogenesis. Evidence indicates that proteins controlling bone mineralization are also involved in the regulation of vascular calcification. Artery wall cells grown in culture are induced to become osteogenic by inflammatory and atherogenic stimuli. Furthermore, osteoclast-like cells are found in calcified atherosclerotic plaques, and active resorption of ectopic vascular calcification has been demonstrated. In general, soft tissue calcification arises in areas of chronic inflammation, possibly functioning as a barrier limiting the spread of the inflammatory stimulus. Atherosclerotic calcification may be one example of this process, in which oxidized lipids are the inflammatory stimulus. Calcification is widely used as a clinical indicator of atherosclerosis. It progresses nonlinearly with time, following a sigmoid-shaped curve. The relationship between calcification and clinical events likely relates to mechanical instability introduced by calcified plaque at its interface with softer, noncalcified plaque. In general, as calcification proceeds, interface surface area increases initially, but eventually decreases as plaques coalesce. This phenomenon may account for reports of less calcification in unstable plaque. Vascular calcification is exacerbated in certain clinical entities, including diabetes, menopause, and osteoporosis. Mechanisms linking them must be considered in clinical decisions. For example, treatments for osteoporosis may have unanticipated effects on vascular calcification; the converse also applies. Further understanding of processes governing vascular calcification may yield new therapeutic options for vascular disease.
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PMID:Vascular calcification: mechanisms and clinical ramifications. 1547 32

Vascular calcification often occurs with advancing age, atherosclerosis, various metabolic disorders such as diabetes mellitus and end-stage renal disease, or in rare genetic diseases, leading to serious clinical consequences. Such mineralization can occur at various sites (cardiac valves, arterial intima or media, capillaries), involve localized or diffuse widespread calcification, and result from numerous causes that provoke active inflammatory and osteogenic processes or disordered mineral homeostasis. Although valuable research has defined many key factors and cell types involved, surprising new insights continue to arise that deepen our understanding and suggest novel research directions or strategies for clinical intervention in calcific vasculopathies. One emerging area in vascular biology involves the RANKL/RANK/OPG system, molecules of the tumor necrosis factor-related family recently discovered to be critical regulators of immune and skeletal biology. Evidence is accumulating that such signals may be expressed, regulated, and function in vascular physiology and pathology in unique ways to promote endothelial cell survival, angiogenesis, monocyte or endothelial cell recruitment, and smooth muscle cell osteogenesis and calcification. Concerted research efforts are greatly needed to understand these potential roles, clarify whether RANKL (receptor activator of nuclear factor kappaB ligand) promotes and osteoprotegerin (OPG) protects against vascular calcification, define how OPG genetic polymorphisms relate to cardiovascular disease, and learn whether elevated serum OPG levels reflect endothelial dysfunction in patients. Overall, the RANKL/RANK/OPG system may mediate important and complex links between the vascular, skeletal, and immune systems. Thus, these molecules may play a central role in regulating the development of vascular calcification coincident with declines in skeletal mineralization with age, osteoporosis, or disease.
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PMID:Regulation of vascular calcification by osteoclast regulatory factors RANKL and osteoprotegerin. 1556 64

Vascular calcification, especially in coronary artery not only serves as a surrogate marker for atherosclerosis, but also predicts a higher risk of myocardial infarction and death. Its pathogenesis involves an active mineralization process by chondrogenic and osteogenic cells as well as a passive precipitation of minerals. Since atherosclerosis is a chronic vascular inflammation, plaque calcification is conceptualized as a chondrogenic and/or osteogenic process associated with chronic vascular inflammation.
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PMID:[Mechanism of vascular calcification]. 1557 69

Patients with diabetes have greatly elevated risks of atherosclerotic diseases such as coronary artery disease (CAD) and stroke. Vascular calcification in advanced atherosclerosis is a common feature in diabetic patients. In vitro and in vivo studies suggest that apoptosis and chondro/osteogenic differentiation of vascular wall cells such as smooth muscle cells may play important roles in the progression of vascular calcification. Diabetes may promote vascular calcification through the action of various factors including hyperglycemia, oxidative stress, tumor necrosis factor-alpha, and advanced glycation end products. Detection of coronary calcium by electron-beam computed tomography (EBCT) revealed clinical significance of vascular calcification and this technique may be a useful method to identify diabetic patients with increased risks of cardiovascular disease and stroke.
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PMID:[Significance of vascular calcification in diabetic patients with increased risks of cardiovascular disease and stroke]. 1577 91

The number of cells expressing antigen to osteonectin was appreciably increased in the blood of coronary patients, but no cells of this kind were detected in donors. The number of CD34+ stem cells in these patients virtually did not differ from that in normal subjects. A close relationship between atherosclerosis development and presence of stromal stem cells with osteogenic potential in the blood is hypothesized.
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PMID:Detection of circulating stromal stem cells with osteogenic potential in the blood of coronary patients by laser flow cytometry. 1602 25

Vascular calcification is often encountered in advanced atherosclerotic lesions and is a common consequence of aging. Calcification of the coronary arteries has been positively correlated with coronary atherosclerotic plaque burden, increased risk of myocardial infarction, and plaque instability. Chronic kidney disease (CKD) patients have two to five times more coronary artery calcification than healthy age-matched individuals. Vascular calcification is a strong prognostic marker of cardiovascular disease mortality in CKD patients. Vascular calcification has long been considered to be a passive, degenerative, and end-stage process of atherosclerosis and inflammation. However, recent evidence indicates that bone matrix proteins such as osteopontin, matrix Gla protein (MGP), and osteocalcin are expressed in calcified atherosclerotic lesions, and that calcium-regulating hormones such as vitamin D3 and parathyroid hormone-related protein regulate vascular calcification in in vitro vascular calcification models based on cultured aortic smooth muscle cells. These findings suggest that vascular calcification is an actively regulated process similar to osteogenesis, and that bone-associated proteins may be involved in the development of vascular calcification. The pathogenesis of vascular calcification in CKD is not well understood and is almost multifactorial. In CKD patients, several studies have found associations of both traditional risk factors, such as hypertension, hyperlipidemia, and diabetes, and uremic-specific risk factors with vascular calcification. Most patients with progressive CKD develop hyperphosphatemia. An elevated phosphate level is an important risk factor for the development of calcification and cardiovascular mortality in CKD patients. Thus, it is hypothesized that an important regulator of vascular calcification is the level of inorganic phosphate. In order to test this hypothesis, we characterized the response of human smooth muscle cell (HSMC) cultures to inorganic phosphate levels. Our findings indicate that inorganic phosphate directly regulates HSMC calcification through a sodium-dependent phosphate transporter mechanism. After treatment with elevated phosphate, there is a loss of smooth muscle lineage markers, such as alpha-actin and SM-22alpha, and a simultaneous gain of osteogenic markers such as cbfa-1 and osteocalcin. Elevated phosphate may directly stimulate HSMC to undergo phenotypic changes that predispose to calcification, and offer a novel explanation of the phenomenon of vascular calcification under hyperphosphatemic conditions. Furthermore, putative calcification inhibitory molecules have been identified using mouse mutational analyses, including MGP, beta-glucosidase, fetuin-A, and osteoprotegerin. Mutant mice deficient in these molecules present with enhanced cardiovascular calcification, demonstrating that specific molecules are normally important in suppressing vascular calcification. These findings suggest that the balance of inducers, such as phosphate, and inhibitors, such as MGP, fetuin-A, and others, are likely to control whether or not calcification occurs under pathological conditions.
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PMID:Vascular calcification in chronic kidney disease. 1650 29

During the onset and progression of atherosclerosis, the vascular smooth muscle cell (VSMC) phenotype changes from differentiated to dedifferentiated, and in some cases, this change is accompanied by osteogenic transition, resulting in vascular calcification. One characteristic of dedifferentiated VSMCs is the down-regulation of smooth muscle cell (SMC) marker gene expression. Bone morphogenetic proteins (BMPs), which are involved in the induction of osteogenic gene expression, are detected in calcified vasculature. In this study, we found that the BMP2-, BMP4-, and BMP6-induced expression of Msx transcription factors (Msx1 and Msx2) preceded the down-regulation of SMC marker expression in cultured differentiated VSMCs. Either Msx1 or Msx2 markedly reduced the myocardin-dependent promoter activities of SMC marker genes (SM22alpha and caldesmon). We further investigated interactions between Msx1 and myocardin/serum response factor (SRF)/CArG-box motif (cis element for SRF) using coimmunoprecipitation, gel-shift, and chromatin immunoprecipitation assays. Our results showed that Msx1 or Msx2 formed a ternary complex with SRF and myocardin and inhibited the binding of SRF or SRF/myocardin to the CArG-box motif, resulting in inhibition of their transcription.
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PMID:Bone morphogenetic protein-induced MSX1 and MSX2 inhibit myocardin-dependent smooth muscle gene transcription. 1703 Jun 28

Once thought to result from passive precipitation of calcium and phosphate, it now appears that vascular calcification is a consequence of tightly regulated processes that culminate in organized extracellular matrix deposition by osteoblast-like cells. These cells may be derived from stem cells (circulating or within the vessel wall) or differentiation of existing cells, such as smooth muscle cells (SMCs) or pericytes. Several factors induce this transition, including bone morphogenetic proteins, oxidant stress, high phosphate levels, parathyroid hormone fragments, and vitamin D. Once the osteogenic phenotype is induced, cells gain a distinctive molecular fingerprint, marked by the transcription factor core binding factor alpha1. Alternatively, loss of inhibitors of mineralization, such as matrix gamma-carboxyglutamic acid Gla protein, fetuin, and osteopontin, also contribute to vascular calcification. The normal balance between promotion and inhibition of calcification becomes dysregulated in chronic kidney disease, diabetes mellitus, atherosclerosis, and as a consequence of aging. Once the physiological determinants of calcification are perturbed, calcification may occur at several sites in the cardiovascular system, including the intima and media of vessels and cardiac valves. Here, calcification may occur through overlapping yet distinct molecular mechanisms, each with different clinical ramifications. A variety of imaging techniques are available to visualize vascular calcification, including fluoroscopy, echocardiography, intravascular ultrasound, and electron beam computed tomography. These imaging modalities vary in sensitivity and specificity, as well as clinical application. Through greater understanding of both the mechanism and clinical consequences of vascular calcification, future therapeutic strategies may be more effectively designed and applied.
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PMID:Vascular calcification: pathobiological mechanisms and clinical implications. 1709 33


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