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Regulation of vascular calcification by osteoclast regulatory factors RANKL and osteoprotegerin.

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.

Animals↗

Spatial heterogeneity of endothelial phenotypes correlates with side-specific vulnerability to calcification in normal porcine aortic valves.

Calcific aortic valve sclerosis involves inflammatory processes and occurs preferentially on the aortic side of endothelialized valve leaflets. Although the endothelium is recognized to play critical roles in focal vascular sclerosis, the contributions of valvular endothelial phenotypes to aortic valve sclerosis and side-specific susceptibility to calcification are poorly understood. Using RNA amplification and cDNA microarrays, we identified 584 genes as differentially expressed in situ by the endothelium on the aortic side versus ventricular side of normal adult pig aortic valves. These differential transcriptional profiles, representative of the steady state in vivo, identify globally distinct endothelial phenotypes on opposite sides of the aortic valve. Several over-represented biological classifications with putative relevance to endothelial regulation of valvular homeostasis and aortic-side vulnerability to calcification were identified among the differentially expressed genes. Of note, multiple inhibitors of cardiovascular calcification were significantly less expressed by endothelium on the disease-prone aortic side of the valve, suggesting side-specific permissiveness to calcification. However, coexisting putative protective mechanisms were also expressed. Specifically, enhanced antioxidative gene expression and the lack of differential expression of proinflammatory molecules on the aortic side may protect against inflammation and lesion initiation in the normal valve. These data implicate the endothelium in regulating valvular calcification and suggest that spatial heterogeneity of valvular endothelial phenotypes may contribute to the focal susceptibility for lesion development.

Animals↗

Angiogenesis and pericytes in the initiation of ectopic calcification.

Ectopic calcification of blood vessels, heart valves, and skeletal muscle is a major clinical problem. There is now good evidence that angiogenesis is associated with ectopic calcification in these tissues and that it is necessary, but not sufficient, for calcification to occur. Angiogenesis may regulate ectopic calcification in several ways. First, many angiogenic factors are now known to exert both direct and indirect effects on bone and cartilage formation. Second, cytokines released by endothelial cells can induce the differentiation of osteoprogenitor cells. Third, the new blood vessels provide oxygen and nutrients to support the growing bone. Finally, the new blood vessels can serve as a conduit for osteoprogenitor cells. These osteoprogenitor cells may be derived from the circulation or from pericytes that are present in the neovessels themselves. Indeed, there is now compelling evidence that pericytes can differentiate into osteoblasts and chondrocytes both in vitro and in vivo. Other vascular cells, including adventitial myofibroblasts, calcifying vascular cells, smooth muscle cells, and valvular interstitial cells, have also been shown to exhibit multilineage potential in vitro. Although these cells share many properties with pericytes, the precise relationship between them is not known. Furthermore, it still remains to be determined whether all or some of these cells contribute to the ectopic calcification observed in vivo. A better understanding of the underlying mechanisms that link angiogenesis, pericytes, and ectopic calcification should provide a basis for development of therapeutic strategies to treat or arrest this clinically significant condition.

Animals↗

Relationship of clinical presentation and calcification of culprit coronary artery stenoses.

Coronary artery calcification is increased in the presence of atherosclerosis. However, there is great variability in the calcification of individual coronary stenoses, and the clinical significance of this finding remains unknown. We tested the hypothesis that culprit lesions associated with myocardial infarction or unstable angina are less calcified than are stenoses associated with stable angina. The study consisted of 78 patients who underwent intravascular ultrasound imaging of culprit stenoses after the placement of a stent. Seventeen patients presented with stable angina; 43, with unstable angina; and 18, with myocardial infarction. The extent of coronary calcification was measured by the angle of its arc and was quantified with a computer-based protractor. The arc of calcium was measured in the stented area at the point of maximal calcification and also as an average of the calcification found at proximal, middle, and distal stent segments. The maximal arc of calcium decreased progressively from patients with stable angina (91+/-10 degrees ) to those with unstable angina (59+/-8 degrees ) and to those with myocardial infarction (49+/-11 degrees, P=0.014). Similarly, the average arc of calcium was greatest (32+/-7 degrees ) in patients with stable angina, less (15+/-4 degrees ) in patients with unstable angina, and least (10+/-5 degrees ) in patients with acute myocardial infarction (P=0.014). These associations remained significant after adjustment for other factors that potentially affect arterial calcification. Acute coronary syndromes are associated with a relative lack of calcium in the culprit stenoses compared with stenoses of patients with stable angina. These findings have implications for the understanding of the biology of acute coronary syndromes as well as for the identification of coronary stenoses by methods that rely solely on the presence of calcium.

Angina Pectoris↗

Localization of experimental calcification in rabbit blood vessels with particular reference to hemodynamics.

An observational study was made of the localization of experimental calcification of blood vessels induced by hypervitaminosis D in 15 stock rabbits, in 10 rabbits with arteriovenous fistulae, and in 6 rabbits with experimental saccular aneurysms. An arteriotomy and a phlebotomy were performed on several animals from each group. The pulmonary trunk, aorta, common carotid arteries, and external jugular veins were dissected and stained with silver nitrate to demonstrate calcification macroscopically. The first major bifurcation from 37 renal arteries from these animals was examined by the serial section technique to localize calcification about the arterial forks histologically. There was evidence that early calcification was flow related with a predilection for sites where atrophic lesions occur. Proliferative lesions in which matrix vesicles are abundant exhibited no such predisposition. It was concluded that matrix vesicles do not appear to be susceptible to vitamin D calcification. The topography of the experimental calcification differed from that of diet-induced lipid deposition.

Animals↗

Coronary artery calcification detected by CT: clinical significance and angiographic correlates.

Cardiac computed tomography (CT) to detect coronary calcification was performed on 161 patients undergoing coronary angiography for proven or suspected coronary artery disease. Among 108 patients in whom coronary calcifications was identified, 90% had significant coronary stenosis angiographically (greater than 75% stenosis), and 80% of 121 patients with significant coronary stenosis showed calcification by CT. The relationship between the calcification site and the significance in stenosis of each vessel was determined. Calcification was present in 133 arteries among 205 stenotic coronary arteries (sensitivity = 65%) as compared with 59 of 439 entire arteries with normal coronary angiograms (specificity = 87%). In the younger age group the sensitivity of calcification for stenosis of each coronary artery was lower and the specificity and predictive value were generally higher than those in the elderly group. These results demonstrate that CT is a valuable procedure for detecting coronary arterial disease, since this examination is easy to conduct, noninvasive, and widely applicable for screening a large population.

Adult↗

Time course of osteopontin, osteocalcin, and osteonectin accumulation and calcification after acute vessel wall injury.

Although mineral deposits have long been described to be a prominent feature of atherosclerosis, the mechanisms of arterial calcification are not well understood. However, accumulation of the non-collagenous matrix bone-associated proteins, osteopontin, osteocalcin, and osteonectin, has been demonstrated in atheromatous plaques. The aim of this study was to evaluate the role of these proteins in arterial calcification and, more precisely, during the initiation of this process. A model of rapid aortic calcification was developed in rabbits by an oversized balloon angioplasty. Calcification was followed using von Kossa staining and osteopontin, osteocalcin, and osteonectin were identified using immunohistochemistry. The aortic injury was rapidly followed by calcified deposits that appeared in the media as soon as 2 days after injury and then accumulated in zipper-like structures. Osteonectin was not detected in calcified deposits at any time after injury. In contrast, osteopontin and osteocalcin were detected in 8- and 14-day calcified structures, respectively, but not in the very early 2-day mineral deposits. These results suggest that these matrix proteins, osteopontin, osteocalcin, and osteonectin, are not involved in the initiation step of the aortic calcification process and that the former two might play a role in the regulation of arterial calcification.

Angioplasty, Balloon↗

Clustered breast calcifications.

In a consecutive series, clustered breast calcifications were classified according to their radiographic appearance. Rounded and 'cloudy' calcifications, and calcifications showing sedimentation were virtually always associated with benign disorders. All other types of clustered calcifications implied a substantial risk of carcinoma. Furthermore, calcifications appearing or increasing during an observation period (median 24 months) implied a larger risk than those remaining unchanged. Guidelines for the management of patients with clustered breast calcifications are given.

Adult↗

Calcifications, narrowing and rugosities of the leg arteries in diabetic patients.

The large arteries in the leg were examined at angiography in 47 insulin dependent diabetics. Arterial lumen size and the short- and long-range variation as well as intima and linear media calcifications were evaluated quantitatively. Significant correlations were obtained between the duration of diabetes on the one hand and media calcification and uniform narrowing of femoral, crural and foot arteries, as well as increased short-range lumen variation on the other hand. Statistically, the narrowing of the femoral artery and the increased short-range, small-scale variation of its lumen were closely related, whereas media calcifications per se appeared unrelated to the lumen size, locally as well as globally. A high degree of concordance was found among the femoral, crural and foot arteries with respect to both the presence of linear media calcifications and their severity. Spotty intima calcifications were clearly associated with irregular arterial narrowing, but were dependent on age and not on the duration of diabetes. It is suggested that the uniform media calcification, narrowing of the arteries and short-range, small-scale variations of the lumina are expressions of a specific diabetic macroangiopathy.

Adult↗

Influence of polyethylene glycol graftings on the in vitro degradation and calcification of bovine pericardium.

Calcification is a frequent cause of the clinical failure of bio-prosthetic heart valves fabricated from glutaraldehyde pretreated bovine pericardium (GATBP). This article reports on various chemical techniques for grafting polyethylene glycol (PEG) on bovine pericardium, their biostability, and calcification. The process of calcification profile was studied by in vitro experiments via the incubation of pericardial samples in a metastable solution of calcium phosphate. The calcification profile of PEG-modified bovine pericardium through glutaraldehyde linkages was significantly reduced compared to other methods of grafting. The mechanical property of these PEG-modified tissues after enzyme (collagenase) digestion and calcification were also investigated. PEG grafting of BP via glutaraldehyde or hexamethylene diisocyanate had shown better mechanical stability compared to other grafting methods used. In conclusion, it seems that the surface modification of bovine pericardium through high molecular weight PEGs via glutaraldehyde linkages may provide new ways of controlling tissue biodegradation and calcification.

Animals↗

Extracorporeal shock wave therapy for calcific and noncalcific tendonitis of the rotator cuff: a systematic review.

The authors conducted a systematic review to assess the effectiveness of extracorporeal shock wave therapy (ESWT) for the treatment of calcific and noncalcific tendonitis of the rotator cuff. Conservative treatment for rotator cuff tendonitis includes physiotherapy, nonsteroidal antiinflammatory drugs, and corticosteroid injections. If symptoms persist with conservative treatment, surgery is often considered. Extracorporeal shock wave therapy has been suggested as a treatment alternative for chronic rotator cuff tendonitis, which may decrease the need for surgery. Articles for this review were identified by electronically searching Medline, EMBASE, Cumulative Index to Nursing & Allied Health Literature (CINAHL), and Evidence Based Medicine (EBM) and hand-screening references. Two reviewers selected the trials that met the inclusion criteria, extracted the data, and assessed the methodological quality of the selected trials. Finally, the strength of scientific evidence was appraised. Evidence was classified as strong, moderate, limited, or conflicting. Sixteen trials met the inclusion criteria. There were only five randomized, controlled trials and all involved chronic (>/=3 months) conditions, three for calcific tendonitis and two for noncalcific tendonitis. For randomized, controlled trials, two (40%) were of high quality, one (33%) for calcific tendonitis and one (50%) for noncalcific tendonitis. The 11 nonrandomized trials included nine that involved calcific tendonitis and two that involved both calcific and noncalcific tendonitis. Common problem areas were sample size, randomization, blinding, treatment provider bias, and outcome measures. There is moderate evidence that high-energy ESWT is effective in treating chronic calcific rotator cuff tendonitis when the shock waves are focused at the calcified deposit. There is moderate evidence that low-energy ESWT is not effective for treating chronic noncalcific rotator cuff tendonitis, although this conclusion is based on only one high-quality study, which was underpowered. High-quality randomized, controlled trials are needed with larger sample sizes, better randomization and blinding, and better outcome measures.

Calcinosis↗

The influence of osteophytes and aortic calcification on spinal mineral density in postmenopausal women.

The assessment of vertebral bone mineral density (BMD) in the anterio-posterior projection has become widely used in the management and prevention of osteoporosis. Recently, it has been demonstrated that the presence of spinal osteophytes has a major impact on measured BMD in men, thus casting doubt on the value of these BMD measurements. We have assessed the impact of osteophytic and aortic calcification on spinal and femoral BMD measurements in 130 normal postmenopausal women, aged 45-71 yr. Lateral lumbar spine radiographs were obtained in all subjects and graded separately (0-3) for osteophytes and aortic calcification. Both forms of calcification increased with age, and BMD of all sites was correlated positively with body weight and negatively with age. The correlation coefficients between BMD and calcification scores were nonsignificant. Multiple regression analysis, including weight, age, and calcification scores, demonstrated a small but significant effect of osteophyte score on lumbar BMD (partial r2 = 0.04; P = 0.012) and a similar trend for Ward's triangle and the trochanteric region (partial r2 = 0.02; P less than 0.06). The aortic calcification score remained nonsignificant. It is concluded that the influence of spinal osteophytes on lumbar BMD in postmenopausal women is substantially less than that in men and is, therefore, unlikely to interfere with BMD estimation in most subjects. The relationship between proximal femoral BMD and osteophyte score suggests a real relationship between skeletal density and degenerative joint disease, as has been demonstrated by others.

Aged↗

Cerebroretinal microangiopathy with calcifications and cysts.

BACKGROUND: Extensive cerebral calcifications and leukoencephalopathy have been reported in two rare disorders Coats plus and leukoencephalopathy with calcifications and cysts. In the latter, a progressive formation of parenchymal brain cysts is a special feature, whereas Coats plus is characterized by intrauterine growth retardation, bilateral retinal telangiectasias and exudations (Coats disease), sparse hair, and dysplastic nails without cyst formation. METHODS: We identified 13 patients, including two pairs of siblings, with extensive cerebral calcifications and leukoencephalopathy. We reviewed clinical, ophthalmologic, radiologic and neuropathologic data of seven deceased patients and studied five patients prospectively. RESULTS: Eleven patients were small for gestational age; the other symptoms emerged from infancy to adolescence. All patients had neurologic symptoms including seizures, spasticity, dystonia, ataxia, and cognitive decline. Progressive intracerebral calcifications involved deep gray nuclei, brainstem, cerebral and cerebellar white matter, and dentate nuclei and were accompanied by diffuse white matter signal changes and, in five patients, cerebral cysts. Eleven patients had retinal telangiectasias or angiomas. Additional features were skeletal and hematologic abnormalities, intestinal bleeding, and poor growth. Neuropathologic examination showed extensive calcinosis and abnormal small vessels with thickened, hyalinized wall and reduced lumen. CONCLUSIONS: Our data suggest that Coats plus syndrome and leukoencephalopathy with calcifications and cysts belong to the same spectrum. The primary abnormality seems to be an obliterative cerebral angiopathy involving small vessels, leading to dystrophic calcifications via slow necrosis and finally to formation of cysts and secondary white matter abnormalities.

Adolescent↗

Pineal Tumors: clinical diagnosis, with special emphasis on the significance of pineal calcification.

The clinical presentations, findings of neuroradiological examinations, laboratory findings, pathological diagnoses, methods of treatment, and results of follow-up of 43 cases of pineal tumor collected at the Nagoya University Hospital from 1958 to 1979 are reviewed. The definitions of calcification of the pineal body and of pineal tumor are given. There is a significant difference in the incidence of calcification of the pineal body between pineal teratomas and pineal germinomas. Although there is a 100% rate of calcification of the pineal body in cases of pineal germinoma, the rate is very low in cases of pineal teratoma; calcification appears in only a small percentage of the cases of teratoma mixed with germinoma or embryonal carcinoma, or both. In male patients with suprasellar germinoma, there is a high frequency of an associated pineal calcification. No pineal calcification is seen in cases of basal ganglia germinoma. The computed tomographic (CT) findings of pineal teratoma and germinoma are characteristic. CT scanning is superior for early diagnosis of suprasellar and basal ganglia germinomas.

Adolescent↗

A mammographic dilemma: calcification or haemosiderin as a cause of opacities? Validation of a new digital diagnostic tool.

Core biopsies of an area of microcalcification demonstrated large collections of macrophages containing haemosiderin, with evidence of minimal microcalcification on H&E staining. Algorithms were developed that were capable of differentiating with high accuracy those signs due to calcification, using quantitative measurements such as the apparent volume composition of calcium. Using the linear attenuation coefficients of calcification and assuming an ellipsoid model for the 3-dimensional shape of calcification, we computed the relative calcification volume for each region of interest. The difference in the linear attenuation coefficients of iron and calcification allowed the two to be differentiated on a mammogram based on this measure of relative calcification volume.

Breast↗

Heterotopic calcification as a late radiation effect: report of 15 cases.

The LENT-SOMA scoring system for reporting late tissue effects following therapeutic radiation does not include heterotopic calcification as an end-point. Here we report on 15 long-term radiotherapy survivors with significant heterotopic calcifications. In all cases heterotopic calcification was linked to other radiation sequelae, e.g. ulceration, bone necrosis, nerve damage and fibrosis. The median time interval between radiotherapy and the occurrence of heterotopic calcification was 19 years (range 2-31 years). All patients received doses in excess of 40 Gy; overlap of adjacent fields played a role in some cases. It appears that heterotopic calcification can be regarded as end-stage damage following high dose radiotherapy. Heterotopic calcification in conjunction with local tissue breakdown is highly suggestive of previous radiation treatment.

Adult↗

Enhanced coronary calcification determined by electron beam CT is strongly related to endothelial dysfunction in patients with suspected coronary artery disease.

BACKGROUND: Coronary artery calcification determined by electron beam CT (EBCT) is strongly associated with total plaque burden but is not related to systemic vascular inflammation. AIMS: We sought to test the hypothesis that enhanced coronary artery calcification, a marker of atherosclerosis and plaque burden, was related to endothelial dysfunction in patients with suspected coronary artery disease (CAD). METHODS AND RESULTS: One hundred twenty-four subjects with suspected CAD were enrolled. Coronary artery calcification was detected by EBCT. A noninvasive method of brachial ultrasound was used to measure endothelium-dependent flow-mediated vasodilation (FMD) and endothelium-independent nitroglycerin-mediated vasodilation (NMD). Serum high-sensitivity C-reactive protein (hsCRP) and monocyte chemoattractant protein-1 (MCP-1) levels were also determined. Of the 124 patients, the calcium scores ranged from 0 to 4,394. All subjects were classified into three groups according to coronary calcium scores: group 1, score 0 (n = 26); group 2, scores 1 to 199 (n = 50); group 3, scores > or = 200 (n = 48). There was an inverse association between the degree of coronary artery calcification and the endothelium-dependent FMD in the three groups (6.9 +/- 0.6% vs 5.3 +/- 0.3% vs 3.7 +/- 0.3%, respectively; p < 0.001) but not the endothelium-independent NMD. Besides, no significant difference in serum levels of hsCRP and MCP-1 were found among the three groups. However, both the serum levels of hsCRP and MCP-1 were correlated significantly with endothelium-dependent FMD (r = - 0.211, p = 0.019; and r = - 0.188, p = 0.037, respectively). By multivariate analysis, enhanced coronary calcification was a strong independent predictor of endothelial dysfunction (p < 0.001). CONCLUSION: Enhanced coronary artery calcification strongly predicted endothelial dysfunction in patients with suspected CAD. Also, serum levels of hsCRP and MCP-1 were significantly correlated with endothelial function. These findings suggested that both calcium deposition and inflammation were involved in endothelial dysfunction.

Aged↗

[Spontaneous calcification in F344/Slc and F344/JCL rats].

F344/Slc and F344/JCL rats 2 years of age were histologically examined for the incidence and distribution of calcification. In the male rats of both strains, calcification was observed in the testis, lung, brain, kidney, heart, aorta, cornea, prostate and seminal vesicle respectively. In the female F344/JCL rats, calcification appeared in the kidney, lung, cornea, brain, stomach, ovary and heart. Among these of both sexes, the lung was one of the most affected organs for calcification. On the other hand, calcification in the kidney was more severe and frequent in the females than in the males, suggesting that the sex may be one of enhancing factors for calcification.

Animals↗