Arterial Calcium Content Research Articles

MicroRNA-145 and microRNA-486 are potential serum biomarkers for vascular calcification.

MicroRNAs (miRs) regulate vascular calcification (VC), and their quantification may contribute to suspicion of the presence of VC. The study was performed in four phases. Phase 1: miRs sequencing of rat calcified and non-calcified aortas. Phase 2: miRs with the highest rate of change, plus miR-145 [the most abundant miR in vascular smooth muscle cells (VSMCs)], were validated in aortas and serum from rats with and without VC. Phase 3: the selected miRs were analyzed in epigastric arteries from kidney donors and recipients, and serum samples from general population. Phase 4: VSMCs were exposed to different phosphorus concentrations, and miR-145 and miR-486 were overexpressed to investigate their role in VC. miR-145, miR-122-5p, miR-486 and miR-598-3p decreased in the rat calcified aortas, but only miR-145 and miR-486 were detected in serum. In human epigastric arteries, miR-145 and miR-486 were lower in kidney transplant recipients compared with donors. Both miRs inversely correlated with arterial calcium content and with VC (Kauppila index). In the general population, the severe VC was associated with the lowest serum levels of both miRs. The receiver operating characteristic curve showed that serum miR-145 was a good biomarker of VC. In VSMCs exposed to high phosphorus, calcium content, osteogenic markers (Runx2 and Osterix) increased, and the contractile marker (α-actin), miR-145 and miR-486 decreased. Overexpression of miR-145, and to a lesser extent miR-486, prevented the increase in calcium content induced by high phosphorus, the osteogenic differentiation and the loss of the contractile phenotype. miR-145 and miR-486 regulate the osteogenic differentiation of VSMCs, and their quantification in serum could serve as a marker of VC.

Prognostic value of coronary vascular dysfunction assessed by rubidium-82 PET/CT imaging in patients with resistant hypertension without overt coronary artery disease

PurposeThe identification of coronary vascular dysfunction may enhance risk stratification in patients with resistant hypertension (RH). We evaluated if impaired coronary vascular function, assessed by rubidium-82 (82Rb) positron emission tomography/computed tomography (PET/CT) imaging, is associated with increased cardiovascular risk in patients with hypertension without overt coronary artery disease (CAD).MethodsWe studied 517 hypertensive subjects, 26% with RH, without overt CAD, and with normal stress-rest myocardial perfusion imaging at 82Rb PET/CT. The outcome end points were cardiac death, nonfatal myocardial infarction, coronary revascularization, and admission for heart failure.ResultsOver a median of 38 months (interquartile range 26 to 50), 21 cardiac events (4.1% cumulative event rate) occurred. Patients with RH were older (p < 0.05) and had a higher prevalence of left ventricular hypertrophy (p < 0.001), a lower hyperemic myocardial blood flow (MBF), and myocardial perfusion reserve (MPR) (both p < 0.001) compared to those without. Conversely, coronary artery calcium content and baseline MBF were not different between patients with and without RH. At univariable Cox regression analysis, age, RH, left ventricular ejection fraction, coronary artery calcium score, and reduced MPR were significant predictors of events. At multivariable analysis, age, RH, and reduced MPR (all p < 0.05) were independent predictors of events. Patients with RH and reduced MPR had the highest risk of events and the major risk acceleration over time.ConclusionThe findings suggest that the assessment of coronary vascular function may enhance risk stratification in patients with hypertension.

Arterial tissue transcriptional profiles associate with tissue remodeling and cardiovascular phenotype in children with end-stage kidney disease

Chronic kidney disease (CKD) greatly increases the risk for cardiovascular disease (CVD). However, molecular mechanisms underlying CKD-induced arterial remodeling are largely unknown. We performed a systematic analysis of arterial biopsies from children with stage 5 predialysis CKD participating in the Cardiovascular Comorbidity in Children with Chronic Kidney Disease (4 C) study. For comparison, we studied biopsies from children without CKD, coronary bypass vessels from adults with atherosclerotic coronary heart disease without CKD and aortic sections of subtotally nephrectomized rats. In pediatric CKD patients, gene expression was correlated to the cardiovascular phenotype assessed by surrogate end-points. The arterial calcium content correlated with the intima-media thickness (IMT) of biopsied vessels from pediatric CKD patients, was markedly increased compared to biopsies from children without CKD and comparable to adult coronary bypass patients. Significant transcriptional changes included ECM components, pro-calcifying factors, and physiological calcification inhibitors; most were highly accordant with changes observed in adults with atherosclerosis and in uremic rats. Individual gene expression levels were significantly associated with the left ventricular mass index and carotid intima media thickness. Thus, inflammatory processes (TNF, IL-10), calcification inhibitors (CA2), the Wnt-pathway (FGF-2) and foremost, ECM components (HMGA1, VNN1, VCAN), impact pathobiological responses in arteries from children with CKD.

Pectoralis muscle area and mortality in smokers without airflow obstruction

BackgroundLow muscle mass is associated with increased mortality in the general population but its prognostic value in at-risk smokers, those without expiratory airflow obstruction, is unknown. We aimed to test the hypothesis that reduced muscle mass is associated with increased mortality in at-risk smokers.MethodsMeasures of both pectoralis and paravertebral erector spinae muscle cross-sectional area (PMA and PVMA, respectively) as well as emphysema on chest computed tomography (CT) scans were performed in 3705 current and former at-risk smokers (≥10 pack-years) aged 45–80 years enrolled into the COPDGene Study between 2008 and 2013. Vital status was ascertained through death certificate. The association between low muscle mass and mortality was assessed using Cox regression analysis.ResultsDuring a median of 6.5 years of follow-up, 212 (5.7%) at-risk smokers died. At-risk smokers in the lowest (vs. highest) sex-specific quartile of PMA but not PVMA had 84% higher risk of death in adjusted models for demographics, smoking, dyspnea, comorbidities, exercise capacity, lung function, emphysema on CT, and coronary artery calcium content (hazard ratio [HR] 1.85 95% Confidence interval [1.14–3.00] P = 0.01). Results were consistent when the PMA index (PMA/height2) was used instead of quartiles. The association between PMA and death was modified by smoking status (P = 0.04). Current smokers had a significantly increased risk of death (lowest vs. highest PMA quartile, HR 2.25 [1.25–4.03] P = 0.007) while former smokers did not.ConclusionsLow muscle mass as measured on chest CT scans is associated with increased mortality in current smokers without airflow obstruction.Trial registrationNCT00608764

Arterial Expression of the Calcium-Sensing Receptor Is Maintained by Physiological Pulsation and Protects against Calcification.

Vascular calcification (VC) is common in chronic kidney disease (CKD) and contributes to cardiovascular mortality. The calcium-sensing receptor (CaSR) is present in human artery, senses extracellular calcium and may directly modulate VC. Objective: to investigate the association between arterial cyclic strain, CaSR expression and VC. Methods and Results: human aortic smooth muscle cells (HAoSMC) were cultured under static or strained conditions, with exposure to CaSR agonists, the calcimimetic R568, and after CaSR silencing and over-expression. High extracellular calcium reduced CaSR expression and promoted osteochondrogenic transformation and calcium deposition. This was partially prevented by cyclic strain and exposure to R568. CaSR silencing enhanced calcification and osteochondrogenic transformation, whereas CaSR over-expression attenuated this procalcific response, demonstrating a central role for the CaSR in the response to cyclic strain and regulation of VC. In arterial explants from CKD patients (n = 11) and controls (n = 9), exposure to R568 did not significantly alter calcium deposition, osteochondrogenic markers or total artery calcium content. Conclusions: physiological mechanical strain is important for arterial homeostasis and may protect arteries from VC. The beneficial effects of cyclic strain may be mediated via the CaSR.

Disturbances in Bone Largely Predict Aortic Calcification in an Alternative Rat Model Developed to Study Both Vascular and Bone Pathology in Chronic Kidney Disease.

Because current rat models used to study chronic kidney disease (CKD)-related vascular calcification show consistent but excessive vascular calcification and chaotic, immeasurable, bone mineralization due to excessive bone turnover, they are not suited to study the bone-vascular axis in one and the same animal. Because vascular calcification and bone mineralization are closely related to each other, an animal model in which both pathologies can be studied concomitantly is highly needed. CKD-related vascular calcification in rats was induced by a 0.25% adenine/low vitamin K diet. To follow vascular calcification and bone pathology over time, rats were killed at weeks 4, 8, 10, 11, and 12. Both static and dynamic bone parameters were measured. Vascular calcification was quantified by histomorphometry and measurement of the arterial calcium content. Stable, severe CKD was induced along with hyperphosphatemia, hypocalcemia as well as increased serum PTH and FGF23. Calcification in the aorta and peripheral arteries was present from week 8 of CKD onward. Four and 8 weeks after CKD, static and dynamic bone parameters were measurable in all animals, thereby presenting typical features of hyperparathyroid bone disease. Multiple regression analysis showed that the eroded perimeter and mineral apposition rate in the bone were strong predictors for aortic calcification. This rat model presents a stable CKD, moderate vascular calcification, and quantifiable bone pathology after 8 weeks of CKD and is the first model that lends itself to study these main complications simultaneously in CKD in mechanistic and intervention studies.

The Association of Pericardial Fat with Coronary Artery Plaque Index at MR Imaging: The Multi-Ethnic Study of Atherosclerosis (MESA)

To determine the relationship of pericardial fat, which secretes proinflammatory markers that have been implicated in coronary atherosclerosis, with atherosclerotic plaque in an asymptomatic population-based cohort. In this institutional review board-approved study, all participants supplied written informed consent. One hundred eighty-three participants (89 women, 94 men; mean age, 61 years ± 9 [standard deviation]) from the community-based Multi-Ethnic Study of Atherosclerosis (MESA) were included. The coronary artery eccentricity (ratio of maximal to minimal coronary artery wall thickness) was determined by using magnetic resonance (MR) imaging and served as an index of plaque burden. The pericardial fat volume was determined by using computed tomography. Linear regression coefficient analysis was used to correlate pericardial fat volume with coronary artery wall thickness and plaque eccentricity. Pericardial fat volume correlated significantly with degree of plaque eccentricity (P < .05) in both men and women. After adjustments for body mass index (BMI) and waist circumference, traditional risk factors, C-reactive protein level, and coronary artery calcium content, the relationship between pericardial fat and plaque eccentricity remained significant in men (P < .01) but not in women. BMI and waist circumference correlated with degree of plaque eccentricity in the univariate model (P < .05) but not after adjustment for pericardial fat volume or traditional risk factors. Pericardial fat volume, rather than BMI and waist circumference, was more strongly related to plaque eccentricity as a measure of coronary atherosclerotic plaque burden. The results support the proposed role of pericardial fat in association with atherosclerosis.

Experimental vasoprotection by a novel erythrocyte-derived depressing factor in rats with arterial calcinosis

Erythrocyte-derived depressing factor (EDDF) shows significant protective effects on blood vessels from hypertensive rats, by regulating vascular reactivity, calcium homeostasis, DNA synthesis, and cell cycle progression in vascular smooth muscles (VSMCs). Arteries from hypertensive and aging people have high levels of accumulated calcium. However, in the life span of experimental animals commonly used, arterial calcium content does not reach cytotoxic levels observed in human. An overdose of vitamin D 3 results in a rapid arterial calcium overload. Using rats with arterial calcinosis and age- and gender-matched Wistar controls, we investigated whether EDDF has beneficial effect on blood vessels from animals with arterial calcinosis. Blood vessel functions were impaired in rats with arterial calcinosis, as indicated by decreased Ca 2+-ATPase activity, increased vasoconstrictor responses to alpha1 adrenoceptor agonist phenylephrine and increased ERK1/2 phosphorylation. Arterial calcium overload also impaired the morphological integrity of VSMCs. EDDF restored the abovementioned abnormalities caused by arterial calcinosis, and inhibited cell cycle progression of VSMCs induced by angiotensin II. In conclusion, EDDF may protect blood vessels from animals with arterial calcinosis, which is mediated by regulating calcium homeostasis, vascular reactivity and cell cycle progression as well as by improving morphological integrity of VSMCs.

Prospective Evaluation of the Role of Atherosclerosis on Cerebral Atrophy: Pilot Study

Our purpose was to study the association between atherosclerosis measured by arterial calcium on computed tomography (CT) and cerebral atrophy demonstrated by brain magnetic resonance imaging (MRI). IRB approved this prospective study. Twenty-one consecutive patients with acute stroke-like symptoms who are scheduled to have brain MRI were recruited on a voluntary basis. electrocardiogram (ECG)-gated helical CT scans were used to determine the arterial calcium as a reliable index of underlying atherosclerosis. Extracranial arterial calcium content was measured quantitatively by special software available in our CT scanner. Intracranial calcium was graded qualitatively. Brain MRI was independently evaluated to identify cortical, central atrophy, and ischemic changes. Relationship between CT demonstrated atherosclerosis and cerebral ischemic changes, brain atrophy patterns were evaluated both without and with adjustment for age and hypertension. Out of 21 patients 20 were included in final study group. There was no correlation between atherosclerotic calcium measures and cortical atrophy, ischemic findings. Both intracranial and extracranial atherosclerosis had partial correlation with central atrophy (R= 0.43 and 0.52, respectively). After adjustment for age, only intracranial atherosclerosis maintained a partial correlation with central atrophy (R= 0.41). However, this correlation did not reach a statistically significant level (P= .10). Intracranial atherosclerosis demonstrated a possible correlation with central atrophy.

Relationship Between Arterial Calcification and Bone Loss in a New Combined Model Rat by Ovariectomy and Vitamin D3 Plus Nicotine

Epidemiological studies have reported an association between arterial calcification and bone loss after menopause. However, the underlying mechanism of the association remains unclear. Therefore, to explore the possible mechanisms of the association, we tried to develop a new combined model rat of ovariectomy (OVX, an animal model of osteoporosis) and vitamin D(3) plus nicotine (VDN rat, an animal model of arterial calcification). We tested them by using sham-operated control rats (SC), OVX control rats (OC), and OVX plus VDN-treated rats (OVN). Dissections were performed twice at 4 (4SC, 4OC, and 4OVN) and 8 (8SC, 8OC, and 8OVN) weeks after treatment. 8OVN showed bone loss and arterial calcification, although 8OC showed only bone loss. Moreover, arterial calcium content was associated with indexes of bone loss at 8 weeks. Thus, the OVN rat is considered a good model to examine the relationship of the two disorders after menopause. Additionally, the arterial endothelin-1 (ET-1, a potent regulator of arterial calcification) levels increased in both 4OVN and 8OVN, and the level was associated with arterial calcium content at 8 weeks. Furthermore, the arterial endothelial nitric oxide synthase (eNOS) protein, which is an enzyme that produces nitric oxide (an antiatherosclerotic substance), was significantly reduced in only 8OVN. Estrogens affect the alterations of the eNOS and ET-1 proteins. Therefore, we suggest that impairment of the ET-1- and NO-producing system in arterial tissue during periods of rapid bone loss by estrogen deficiency might be a mechanism of the relationship between the two disorders seen in postmenopausal women.

Risk Factors for Development of Coronary Heart Disease in Patients with Acromegaly: A Five-Year Prospective Study

Data on coronary heart disease (CHD) are scanty and matter of argument in acromegalic patients. The objective of this study was to evaluate risk factors for development of CHD and the occurrence of cardiac events in acromegalic patients during a 5-yr prospective study. Ten-year likelihood for CHD development was estimated by the Framingham scoring system (FS); patients were stratified as having low (FS < 10), intermediate (>or= 10 FS < 20), or high (FS >or= 20) risk. Coronary artery calcium content was measured using the Agatston score (AS) in all patients; those with positive AS were submitted to myocardial single-photon emission computed tomography; cardiac events were recorded during a 5-yr follow-up period. Fifty-two consecutive patients (31 women, mean age 52 +/- 11 yr) with controlled or uncontrolled acromegaly were followed prospectively for 5 yr. Thirty-seven patients (71%) had low, 14 patients (27%) had intermediate, and one patient (2%) had high CHD risk. CHD risk was unrelated to acromegaly activity or the estimated duration of disease. Among patients with FS less than 10%, 24 had AS equal to 0, eight had AS of 1 or greater and less than 100, and five had AS 100 or greater and less than 300, respectively. Among patients with FS 10 or greater and less than 20%, nine had AS equal to 0, two had AS of one or greater and less than 100, one had AS of 100 or greater and less than 300, and two had AS of 300 or greater; a patient of the latter group, having AS of 400 or greater, increased his CHD risk from 11% to 20% or more. FS or AS did not differ in patients with controlled or uncontrolled acromegaly (P = 0.981). All patients with positive AS had no single photon emission computed tomography perfusion defects. During the 5-yr follow-up period no patient developed ischemic cardiac events. CHD risk in acromegalic patients, predicted by FS as in nonacromegalic subjects, is low; AS might have adjunctive role only in a subset of patients. However, most patients have systemic complications of acromegaly, which participate in the assessment of global CHD risk.

Regression of warfarin-induced medial elastocalcinosis by high intake of vitamin K in rats

AbstractArterial calcification (AC) is generally regarded as an independent risk factor for cardiovascular morbidity and mortality. Matrix Gla protein (MGP) is a potent inhibitor of AC, and its activity depends on vitamin K (VK). In rats, inactivation of MGP by treatment with the vitamin K antagonist warfarin leads to rapid calcification of the arteries. Here, we investigated whether preformed AC can be regressed by a VK-rich diet. Rats received a calcification-inducing diet containing both VK and warfarin (W&K). During a second 6-week period, animals were randomly assigned to receive either W&K (3.0 mg/g and 1.5 mg/g, subsequently), a diet containing a normal (5 µg/g) or high (100 µg/g) amount of VK (either K1 or K2). Increased aortic calcium concentration was observed in the group that continued to receive W&K and also in the group changed to the normal dose of VK and AC progressed. Both the VK-rich diets decreased the arterial calcium content by some 50%. In addition, arterial distensibility was restored by the VK-rich diet. Using MGP antibodies, local VK deficiency was demonstrated at sites of calcification. This is the first study in rats demonstrating that AC and the resulting decreased arterial distensibility are reversible by high-VK intake.

Vascular calcium overload produced by vitamin D3, in rats. Effect of treatment with SR 33805, a novel calcium entry blocker

The effect of SR 33805, a novel calcium entry blocker, on calcium overload was studied in six vascular beds in rat. Fantofarone, a parent compound, and verapamil were used as reference calcium entry blockers. Calcium overload induced with a single dose (300,000 IU, i.m. of vitamin D3) was measured by means of atomic absorption and histological techniques. From the time-course of calcium overload, a treatment period of 3 days was selected to determine the effects of drug treatment. The compounds were given orally twice a day in the following dose ranges: SR 33805 2-100 mg/kg, fantofarone 10-300 mg/kg, verapamil 100 mg/kg. SR 33805 significantly decreased the calcium content beginning at the dose of 2 mg/kg in the thoracic aorta, 5 mg/kg in the mesenteric artery and 30 mg/kg in the heart. Fantofarone and verapamil had the same effect at the dose of 100 mg/kg. Histological assessment of the heart revealed that lesions appearing in the tissue adjacent to the arteries were significantly diminished by treatment with SR 33805 at a dose which produced a significant decrease in the arterial calcium content. Thus, SR 33805 can inhibit both calcium overload and its deleterious consequences and its actions are evident at doses as low as 2 mg/kg.

Release of endogenous ATP from the caudal artery in rats with arteriosclerosis

Noradrenaline significantly increased (by a prazosin-sensitive mechanism) the overflow of ATP and its metabolites from the caudal arteries of rats treated with excess vitamin D 2 and a high-cholesterol diet (arteriosclerotic rats), although the amount of the overflow was smaller than that in the normal rats. The arteries from the arteriosclerotic rats showed a marked increase in the calcium content and there was a significant negative correlation between the noradrenaline-induced overflow of ATP and the arterial calcium content. These findings indicate that ATP release from arteriosclerotic rat caudal arteries mediated by α 1-adrenoceptors is impaired in proportion to the extent of arterial calcification.

Vascular Ca overload produced by vitamin D3 plus nicotine diminishes arterial distensibility in rats.

In humans, aging produces many structural changes in blood vessels, one of the most pronounced being arterial calcium overload. Simultaneously arteries become increasingly rigid. The slow evolution of the two processes renders it difficult to evaluate the importance of vascular calcium overload in the development of decreased compliance. To gain insight into this relationship, rapid vascular calcium overload was produced by treating young rats with vitamin D3 and nicotine. When rats were allowed 16 days or longer to recover from such treatment, analysis of plasma parameters revealed no overt toxicity, and growth rate was similar to that of controls. Pronounced calcium overload was seen primarily in compliance arteries. Changes in systemic arterial compliance, characteristic impedance, pulse-wave velocity, and carotid compliance all reflected a substantial increase in arterial rigidity. Linear regression analysis revealed significant correlations between the various indicators of arterial distensibility and arterial calcium content. In conclusion, treatment of young rats with vitamin D3 and nicotine may provide a suitable model with which to investigate how calcium overload is involved in the induration of compliance arteries.

Arterial calcinosis, chronic renal failure and calcium antagonism.

A progressive rise in arterial calcium content is the most characteristic age-associated alteration in the arterial wall and the decisive factor in arteriosclerotic degeneration. Experimental studies have demonstrated that calcium antagonists can prevent or retard the development of arterial calcinosis associated with vitamin D overload, hypertension or alloxan-induced diabetes. Although similar effects are more difficult to observe in humans, they have been demonstrated in patients with coronary artery disease and in patients with end-stage renal disease, which is characterised by an acceleration of the normal arterial aging process.

Differentiation Between Calcium-and Cholesterol-Dominated Types of Arteriosclerotic Lesions

In a series of animal studies we have clearly demonstrated since 1970 that calcium overload of the arterial wall is crucially involved in the pathogenesis of arteriosclerotic lesions. Following excessive calcium uptake, vascular stretch compliance and distensibility were lost together with structural integrity. Conversely, calcium antagonists that counteract abundant calcium uptake were found to prevent pathogenic mural calcium accumulation and damage. These effects were realized with light and electron microscopy as well as with measurements of calcium accumulation using atomic absorption spectrometry and radiocalcium. The experiments were carried out on rats exposed to various well-known risk factors such as nicotine, alloxan diabetes, high doses of vitamin D3, or dihydrotachysterol. Another particularly vasotoxic factor appeared to be hypertension, which develops in spontaneously hypertensive Okamoto rats (SHRs), in hypertensive NaCl-loaded salt-sensitive Dahl-S rats, and in rats with nephrogenic Goldblatt hypertension. Interestingly, aging arteries in animals and humans also exhibit, as a characteristic phenomenon, a steady increase in arterial calcium content. This natural age-dependent calcium accumulation is further enhanced in severe diabetics, heavy smokers, and hypertensive patients. However, the most excessive degree of toxic calcium overload, correlated with dramatic structural damage, occurred in human coronary artery plaques. Here, in "fatty streaks" (type I plaques according to World Health Organization classification), the mural calcium content exhibited a rise by 13 times above normal; in type II lesions (fibrous plaques), the increase in calcium was 24-fold; and in type III plaques, i.e., in "complicated lesions of stenosing character," calcium overload amounted to a value greater than 80 times above that found in healthy coronary segments.(ABSTRACT TRUNCATED AT 250 WORDS)