Calcified atherosclerotic plaque and bone mineral density in type 2 diabetes: the diabetes heart study

The relationship between bone health and type of intracranial internal carotid calcifications in patients with ischemic stroke

INTRODUCTION

Vascular calcifications, primarily in the aorta and its proximal branches, are commonly observed among subjects with impaired bone health. In this study, we sought to determine if a comparable association holds true for the calcifications in the intracranial internal carotid arteries (IICA), in general and also for particular calcification patterns.

METHODS

A consecutive series of ischemic stroke patients were prospectively enrolled into the study, where computed tomography angiography source images were used to determine the presence and type of IICA calcifications, and dual-energy X-ray absorptiometry was used to determine the bone mineral density in the left femoral neck region. IICA calcifications were categorized as none, intimal, medial, and mixed types based on previously validated classification schemes. Their relationships with femoral bone T-scores were evaluated by bivariate and multivariate analyses.

RESULTS

Femoral neck T-score was highest among patients without any vascular calcifications (n=65), when compared to the bone density measures among patients with any type of calcification (n=185) (p<0.001). After adjustment for age, gender, vascular risk factors, and serum biomarkers related to bone health, the T-score remained significantly associated only with the pattern of intimal calcification [OR 0.63 (0.42 - 0.95), p=0.028].

CONCLUSIONS

Our findings suggest that the intracranial vasculature, in particular the internal carotid arteries, is not immune to the interplay between suboptimal bone health and vascular calcifications. This association was most robust for an intimal type of IICA calcification pattern, while no such relationship could be demonstrated for other types of vascular calcifications.

Diabetes and the Microvasculature of the Bone and Marrow

PURPOSE OF REVIEW

The purpose of this review is to highlight the evidence of microvascular dysfunction in bone and marrow and its relation to poor skeletal outcomes in diabetes mellitus.

RECENT FINDINGS

Diabetes mellitus is characterized by chronic hyperglycemia, which may lead to microangiopathy and macroangiopathy. Micro- and macroangiopathy have been diagnosed in Type 1 and Type 2 diabetes, coinciding with osteopenia, osteoporosis, enhanced fracture risk and delayed fracture healing. Microangiopathy has been reported in the skeleton, correlating with reduced blood flow and perfusion, vasomotor dysfunction, microvascular rarefaction, reduced angiogenic capabilities, and augmented vascular permeability. Microangiopathy within the skeleton may be detrimental to bone and manifest as, among other clinical abnormalities, reduced mass, enhanced fracture risk, and delayed fracture healing. More investigations are required to elucidate the various mechanisms by which diabetic microvascular dysfunction impacts the skeleton.

Impaired intracellular calcium homeostasis enhances protein O-GlcNAcylation and promotes vascular calcification and stiffness in diabetes

Vascular calcification is accelerated in patients with diabetes mellitus and increases risk of cardiovascular events and mortality. Vascular smooth muscle cells (VSMC) play a key role in regulating vascular tone and contribute significantly to the development of diabetic vasculopathy. In this study, the function of stromal interaction molecule 1 (STIM1), an important regulator for intracellular calcium homeostasis, in diabetic vascular calcification was investigated, and the underlying molecular mechanisms were uncovered. A SMC-specific STIM1 deletion mouse model (STIM1Δ/Δ) was generated by breeding the STIM1 floxed mice (STIM1f/f) with SM22α-Cre transgenic mice. Using aortic arteries from the STIM1Δ/Δ mice and their STIM1f/f littermates, we found that SMC-specific STIM1 deletion induced calcification of aortic arteries cultured in osteogenic media ex vivo. Furthermore, STIM1 deficiency promoted osteogenic differentiation and calcification of VSMC from the STIM1Δ/Δ mice. In the low-dose streptozotocin (STZ)-induced mouse model of diabetes, SMC-specific STIM1 deletion markedly enhanced STZ-induced vascular calcification and stiffness in the STIM1Δ/Δ mice. The diabetic mice with SMC-specific STIM1 ablation also exhibited increased aortic expression of the key osteogenic transcription factor, Runx2, and protein O-GlcNAcylation, an important post-translational modulation that we have reported to promote vascular calcification and stiffness in diabetes. Consistently, elevation of O-GlcNAcylation was demonstrated in aortic arteries and VSMC from the STIM1Δ/Δ mice. Inhibition of O-GlcNAcylation with a pharmacological inhibitor abolished STIM1 deficiency-induced VSMC calcification, supporting a critical role of O-GlcNAcylation in mediating STIM1 deficiency-induced VSMC calcification. Mechanistically, we identified that STIM1 deficiency resulted in impaired calcium homeostasis, which activated calcium signaling and increased endoplasmic reticulum (ER) stress in VSMC, while inhibition of ER stress attenuated STIM1-induced elevation of protein O-GlcNAcylation. In conclusion, the study has demonstrated a causative role of SMC-expressed STIM1 in regulating vascular calcification and stiffness in diabetes. We have further identified a novel mechanisms underlying STIM1 deficiency-induced impairment of calcium homeostasis and ER stress in upregulation of protein O-GlcNAcylation in VSMC, which promotes VSMC osteogenic differentiation and calcification in diabetes.

Deletion of Smooth Muscle O-GlcNAc Transferase Prevents Development of Atherosclerosis in Western Diet-Fed Hyperglycemic ApoE-/- Mice In Vivo

Accumulating evidence highlights protein O-GlcNAcylation as a putative pathogenic contributor of diabetic vascular complications. We previously reported that elevated protein O-GlcNAcylation correlates with increased atherosclerotic lesion formation and VSMC proliferation in response to hyperglycemia. However, the role of O-GlcNAc transferase (OGT), regulator of O-GlcNAc signaling, in the evolution of diabetic atherosclerosis remains elusive. The goal of this study was to determine whether smooth muscle OGT (smOGT) plays a direct role in hyperglycemia-induced atherosclerotic lesion formation and SMC de-differentiation. Using tamoxifen-inducible Myh11-CreERT2 and Ogtfl/fl mice, we generated smOGTWT and smOGTKO mice, with and without ApoE-null backgrounds. Following STZ-induced hyperglycemia, smOGTWT and smOGTKO mice were kept on a standard laboratory diet for the study duration. In a parallel study, smOGTWTApoE-/- and smOGTKOApoE-/- were initiated on Western diet at 8-wks-age. Animals harvested at 14-16-wks-age were used for plasma and tissue collection. Loss of smOGT augmented SM contractile marker expression in aortic vessels of STZ-induced hyperglycemic smOGTKO mice. Consistently, smOGT deletion attenuated atherosclerotic lesion lipid burden (Oil red O), plaque area (H&E), leukocyte (CD45) and smooth muscle cell (ACTA2) abundance in Western diet-fed hyperglycemic smOGTKOApoE-/- mice. This was accompanied by increased SM contractile markers and reduced inflammatory and proliferative marker expression. Further, smOGT deletion attenuated YY1 and SRF expression (transcriptional regulators of SM contractile genes) in hyperglycemic smOGTKOApoE-/- and smOGTKO mice. These data uncover an athero-protective outcome of smOGT loss-of-function and suggest a direct regulatory role of OGT-mediated O-GlcNAcylation in VSMC de-differentiation in hyperglycemia.

Multiethnic Genome-Wide Association Study of Subclinical Atherosclerosis in Individuals With Type 2 Diabetes

BACKGROUND

Coronary artery calcification (CAC) and carotid artery intima-media thickness (cIMT) are measures of subclinical atherosclerosis in asymptomatic individuals and strong risk factors for cardiovascular disease. Type 2 diabetes (T2D) is an independent cardiovascular disease risk factor that accelerates atherosclerosis.

METHODS

We performed meta-analyses of genome-wide association studies in up to 2500 T2D individuals of European ancestry (EA) and 1590 T2D individuals of African ancestry with or without exclusion of prevalent cardiovascular disease, for CAC measured by cardiac computed tomography, and 3608 individuals of EA and 838 individuals of African ancestry with T2D for cIMT measured by ultrasonography within the CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) Consortium.

RESULTS

We replicated 2 loci (rs9369640 and rs9349379 near PHACTR1 and rs10757278 near CDKN2B) for CAC and one locus for cIMT (rs7412 and rs445925 near APOE-APOC1) that were previously reported in the general EA populations. We identified one novel CAC locus (rs8000449 near CSNK1A1L/LINC00547/POSTN at 13q13.3) at P=2.0×10-8 in EA. No additional loci were identified with the meta-analyses of EA and African ancestry. The expression quantitative trait loci analysis with nearby expressed genes derived from arterial wall and metabolic tissues from the Genotype-Tissue Expression project pinpoints POSTN, encoding a matricellular protein involved in bone formation and bone matrix organization, as the potential candidate gene at this locus. In addition, we found significant associations (P<3.1×10-4) for 3 previously reported coronary artery disease loci for these subclinical atherosclerotic phenotypes (rs2891168 near CDKN2B-AS1 and rs11170820 near FLJ12825 for CAC, and rs7412 near APOE for cIMT).

CONCLUSIONS

Our results provide potential biological mechanisms that could link CAC and cIMT to increased cardiovascular disease risk in individuals with T2D.

Ascending Aortic Calcification as a Potential Predictor for Low Bone Mineral Density: A Pilot Study

BACKGROUND

Identifying the factors related to low bone mineral density (BMD) can have significant implications for preventing hip fractures. The correlation between ascending aortic calcification and BMD has never been reported. Therefore, the purpose of the current study is to confirm the hypothesis that ascending aortic calcification can be used as a predictive factor for low BMD and to find a radiographic sign to show it.

METHOD

Plain film and computed tomography (CT) images of the thorax were obtained from 91 patients with hip fractures. Using the images, the calcification line of the ascending aorta adjacent to the aortic arch was evaluated. A prominent calcification line confirmed by both plain film and CT was classified as +2. A line which was ambiguous on plain film but confirmed by CT was classified as +1. Cases with no calcification were categorized as 0 (control). We compared the classified score with the BMD and calculated the kappa coefficient to measure intraobserver reliabilities for this radiographic finding.

RESULTS

Twenty-eight patients showed a +2 line, twenty-four patients showed a +1 line, and thirty-nine patients showed 0 lines. The median BMD of each group was 0.37 for the +2 line, 0.45 for the +1 line, and 0.51 for the 0 line. The BMD for the +2 group was significantly lower than the others. The kappa coefficient was approximately 0.6 (p < 0.01).

CONCLUSION

The imaging finding of calcification of the ascending aorta might be considered as a potential surrogate marker of low BMD. In such subjects, BMD might be ordered for the confirmation of diagnosis of osteoporosis. Mini-Abstract. The Aortic Arch Tail Sign, a calcification line on the ascending aorta, was relevant to low BMD in the current study. BMD can be ordered for the confirmation of diagnosis of osteoporosis in a subject incidentally found to have ascending aorta calcification on X-ray or CT.

The association between low bone mineral density and coronary artery calcification in osteoporotic and non-osteoporotic patients in a tertiary center in Saudi Arabia

BACKGROUND

Cardiovascular disease (CVD) and osteoporosis are major health-care concerns worldwide. The evidence is contradictory on whether a relationship exists between low bone mineral density (BMD) determined by dual-energy absorptiometry (DXA scan) and coronary artery calcification (CAC) measured by computed tomography. Currently, there are no data on patients from Saudi Arabia.

OBJECTIVE

Examine the relationship between CAC and BMD in both genders and study the influence of traditional coronary artery disease (CAD) risk factors and osteoporosis.

DESIGN

Retrospective, cross-sectional, analytical.

SETTING

Single tertiary care center.

PATIENTS AND METHODS

We searched radiology databases for patients who underwent both DXA and CAC score scanning within six months of each other. The inclusion criterion was an absence of any history of CAD.

MAIN OUTCOME MEASURE

Association between osteoporosis and CAC.

SAMPLE SIZE

195 (34 osteoporosic, 161 normal BMD or osteopenic) RESULTS: Most of the study population (57.4%) were females. The mean age of all patients was 63.6 (10.1) years. Participants with CAC scores of 0 were significantly younger than those who had CAC scores >0. The presence of diabetes mellitus, hypertension, and hypercholesterolemia was higher in patients with CAC scores >0. CAC score and other CAD risk factors were not significantly different between the osteoporotic and nonosteoporotic groups, except for body mass index. A high CAC score (>100) was present in 28%, 20%, 11%, and 30% of participants with no osteoporosis, osteoporosis of the lumbar spine, osteoporosis of the femoral neck, and participants with osteoporosis of both the lumbar spine and femoral neck, respectively (P=.762), suggesting there is no association between CAC and the presence of osteoporosis.

CONCLUSIONS

Osteoporosis is not associated with higher CAC scores in Saudi Arabia and CAD risk factors are not significantly prevalent in osteoporosis. It appears that CAC and osteoporosis are independent age-related diseases that share common risk factors.

LIMITATIONS

Single-center, retrospective.

CONFLICT OF INTEREST

None.

The relationship between atherosclerosis and bone mineral density in patients with type 2 diabetes depends on vascular calcifications and sex

It is unknown whether a relationship exists between bone mineral density (BMD) and atherosclerosis with or without vascular calcification. In our study, a negative correlation between carotid atherosclerosis and BMD was found in female T2DM patients with vascular calcification, but not in those without calcification and males.

INTRODUCTION

Atherosclerosis is considered associated with low bone mineral density (BMD). However, most previous studies focus on patients with arterial atherosclerosis with vascular calcification. It is still unknown whether a relationship exists between atherosclerosis and BMD in patients without calcification. It is also unknown if sex plays a role in this relationship.

METHODS

We performed a retrospective cross-sectional study, which included 1459 type 2 diabetes mellitus (T2DM) patients (648 males ≥ 50 years old, and 811 postmenopausal females). They were assigned to three groups: group 1 (patients without carotid plaques and without carotid calcification), group 2 (patients with carotid plaques but without carotid calcification), and group 3 (patients with carotid plaques and with carotid calcification). Clinical characteristics and BMD were compared. The relationship between atherosclerosis and BMD was determined by binary logistic regression analysis. Statistical analysis was performed using SPSS 25.0.

RESULTS

Significant differences were only observed in women. The percentage of osteoporosis was higher in group 3 (43.64%) than in groups 1 (34.82%) and 2 (32.14%) (P = 0.016). Low BMD was found in the lumbar (P = 0.032), hip (P < 0.001), and femoral neck (P < 0.001). The odds ratio for osteoporosis increased significantly in a score-dependent manner in postmenopausal female patients with calcified atherosclerosis, but not in uncalcified patients. In men, no differences or relationships were identified.

CONCLUSION

A negative correlation between carotid atherosclerosis and BMD was found in female T2DM patients with vascular calcification, but not in those without calcification. A similar relationship was not observed in male patients with or without calcification. Thus, the relationship between atherosclerosis and bone mineral density in patients with type 2 diabetes depends on vascular calcifications and sex.

Relationship of volumetric bone mineral density by quantitative computed tomography with abdominal aortic calcification

OBJECTIVE

This multicenter study aimed to evaluate the association between volumetric bone mineral density (vBMD) and abdominal aortic calcification (AAC) in a Chinese population.

METHODS

Quantitative computed tomography (QCT) and Agatston score (AS) were used to measure vBMD and AAC, respectively, in 3457 participants during 2013-2017. The association between vBMD and AAC was assessed using multivariate regression analysis, adjusted for age, residence, education, body mass index, and other cardiovascular risk factors.

RESULTS

The mean age of women and men was 61.4 and 62.7 years, respectively. In total, 30.4% of women and 37.7% of men were found to have AAC. After full adjustment, higher vBMD was associated with lower AAC score (β, -0.095; 95% confidence interval [CI], -0.167 to -0.024; P = 0.0087) and lower AAC prevalence (odds ratio [OR], 0.873; 95% CI, 0.824 to 0.924; P < 0.0001) in men. Inverse trends were also observed in the association of vBMD quartile with AAC severity (lowest vs highest quartile; β = 0.235; 95% CI, 0.011 to 0.459; P_trend < 0.0001) and AAC prevalence (lowest vs highest quartile; OR = 1.329; 95% CI, 1.087 to 1.625; P_trend < 0.0001) in men. However, no significant result was obtained in women, except for the association between quartiles of vBMD and AAC score.

CONCLUSIONS

In our study, vBMD was inversely associated with AAC among men independent of age and shared risk factors. However, the association was not significant among women.

Regulatory Effects of O-GlcNAcylation in Vascular Smooth Muscle Cells on Diabetic Vasculopathy

Vascular complications from uncontrolled hyperglycemia are the leading cause of death in patients with diabetes mellitus. Previous reports have shown a strong correlation between hyperglycemia and vascular calcification, which increases mortality and morbidity in individuals with diabetes. However, the precise underlying molecular mechanisms of hyperglycemia-induced vascular calcification remain largely unknown. Transdifferentiation of vascular smooth muscle cells (VSMC) into osteoblast-like cells is a known culprit underlying the development of vascular calcification in the diabetic vasculature. Pathological conditions such as high glucose levels and oxidative stress are linked to enhanced osteogenic differentiation of VSMC both in vivo and in vitro. It has been demonstrated that increased expression of runt-related transcription factor 2 (Runx2), a bone-related transcription factor, in VSMC is necessary and sufficient for the induction of VSMC calcification. Addition of a single O-linked β-N-acetylglucosamine (O-GlcNAc) moiety to the serine/threonine residues of target proteins (O-GlcNAcylation) has been observed in the arteries of diabetic patients, as well as in animal models in association with the enhanced expression of Runx2 and aggravated vascular calcification. O-GlcNAcylation is a dynamic and tightly regulated process, that is mediated by 2 enzymes, O-GlcNAc transferase and O-GlcNAcase. Glucose is metabolized into UDP-β-D-N-acetylglucosamine, an active sugar donor of O-GlcNAcylation via the hexosamine biosynthetic pathway. Overall increases in the O-GlcNAcylation of cellular proteins have been closely associated with cardiovascular complications of diabetes. In this review, the authors provide molecular insights into cardiovascular complications, including diabetic vasculopathy, that feature increased O-GlcNAcylation in people with diabetes.

Feasibility of Opportunistic Screening for Low Thoracic Bone Mineral Density in Patients Referred for Routine Cardiac CT

Despite being a frequent and treatable disease, osteoporosis remains under-diagnosed worldwide. Our study aim was to characterize the bone mineral density (BMD) status in a group of patients with symptoms suggestive of coronary artery disease (CAD) with low/intermediate risk profile undergoing routine cardiac computed tomography (CT) to rule out CAD. This cross-sectional study used prospectively acquired data from a large consecutively included cohort. Participants were referred for cardiac CT based on symptoms of CAD. Quantitative CT (QCT) dedicated software was used to obtain BMD measurements in 3 vertebrae starting from the level of the left main coronary artery. We used the American College of Radiology cut-off values for lumbar spine QCT to categorize patients into very low (<80 mg/cm3), low (80-120 mg/cm3), or normal BMD (>120 mg/cm3). Analyses included 1487 patients. Mean age was 57 years (range 40-80), and 52% were women. The number of patients with very low BMD was 105 women (14%, 105/773) and 74 men (10%, 74/714). The majority of patients with very low BMD was not previously diagnosed with osteoporosis (87%) and received no anti-osteoporotic treatment (90%). Opportunistic screening in patients referred for cardiac CT revealed a substantial number of patients with very low BMD. The majority of these patients was not previously diagnosed with osteoporosis and received no anti-osteoporotic treatment. Identification of these patients could facilitate initiation of anti-osteoporotic treatment and reduce the occurrence of osteoporosis-related complications.

Bone mass density and bone metabolism marker are associated with progression of carotid and cardiac calcified plaque in Chinese elderly population

Osteoporosis and cardiovascular diseases often coexist in the same elderly individuals. Does this suggest some potential correlation between the two diseases? Low bone mass and change of bone biomarker are associated with a higher risk of carotid and cardiac calcification plaques.

INTRODUCTION

Bone mineral density (BMD) and bone metabolism marker may contribute to the progression of carotid and cardiac arterial calcifications. The aim of this study was to investigate whether low bone mass and the change of bone biomarker are associated with the prevalence of calcified atherosclerotic plaque in elderly Chinese.

METHODS

We conducted a five-year prospective study. BMD was measured by dual-energy X-ray absorptiometry scanning. Carotid and cardiac computed tomography angiography (CTA) was conducted using a 64-multidetector row scanner to assess carotid and cardiac arterial plaque at baseline and during follow-up.

RESULTS

Of 1571 community residents over 60 years of age, 184 (11.7%) subjects developed carotid calcified plaque, 510 (32.5%) subjects developed cardiac calcified plaque and 97 (6.2%) subjects developed co-existence calcified plaques in carotid and cardiac arteries. After adjustment for age and all relevant confounders, Q1, Q2 quartile of BMD, and osteoprotegerin (OPG), osteocalcin (OC), and C-terminal cross-linked telopeptide of type I collagen (CTX) were associated with increased risk of calcified plaques.

CONCLUSION

This study suggested that lower BMD and change of bone metabolism biomarker were associated with a higher risk of carotid and cardiac calcified plaque development.

Metabolic Stress and Cardiovascular Disease in Diabetes Mellitus: The Role of Protein O-GlcNAc Modification

Mammalian cells metabolize glucose primarily for energy production, biomass synthesis, and posttranslational glycosylation; and maintaining glucose metabolic homeostasis is essential for normal physiology of cells. Impaired glucose homeostasis leads to hyperglycemia, a hallmark of diabetes mellitus. Chronically increased glucose in diabetes mellitus promotes pathological changes accompanied by impaired cellular function and tissue damage, which facilitates the development of cardiovascular complications, the major cause of morbidity and mortality of patients with diabetes mellitus. Emerging roles of glucose metabolism via the hexosamine biosynthesis pathway (HBP) and increased protein modification via O-linked β-N-acetylglucosamine (O-GlcNAcylation) have been demonstrated in diabetes mellitus and implicated in the development of diabetic cardiovascular complications. This review will discuss the biological outcomes of the glucose metabolism via the hexosamine biogenesis pathway and protein O-GlcNAcylation in regulating cellular homeostasis, and highlight the regulations and contributions of elevated O-GlcNAcylation to the pathogenesis of diabetic cardiovascular disease.

Bone Mineral Density of the Radius Predicts All-Cause Mortality in Patients With Type 2 Diabetes: Diabetes Heart Study

This study aimed to determine the association between areal and volumetric bone mineral density (BMD) with all-cause mortality in patients with type 2 diabetes (T2D). Associations between BMD and all-cause mortality were examined in 576 women and 517 men with T2D in the Diabetes Heart Study. Volumetric BMD in the thoracic and lumbar spine was measured with quantitative computed tomography. Areal BMD (aBMD) in the lumbar spine, total hip, femoral neck, ultradistal radius, mid radius, and whole body was measured using dual X-ray absorptiometry. Association of BMD with all-cause mortality was determined using sequential models, stratified by sex: (1) unadjusted; (2) adjusted for age, race, smoking, alcohol, estrogen use; (3) model 2 plus history of cardiovascular disease, hypertension, and coronary artery calcification; (4) model 3 plus lean mass; and (5) model 3 plus fat mass. At baseline, mean age was 61.2 years for women and 62.7 years for men. At mean 11.0 ± 3.7 years' follow-up, 221 (36.4%) women and 238 (43.6%) men were deceased. In women, BMD at all skeletal sites (except spine aBMD and whole body aBMD) was inversely associated with all-cause mortality in the unadjusted model. These associations remained significant in the mid radius (hazard ratio per standard deviation  = 0.79; p = 0.0057) and distal radius (hazard ratio per standard deviation  = 0.76; p = 0.0056) after adjusting for all covariates, including lean mass. In men, volumetric BMD measurements but not aBMD were inversely associated with mortality and only in the unadjusted model. In this longitudinal study, lower baseline aBMD in the radius was associated with increased all-cause mortality in women with T2D, but not men, independent of other risk factors for death.

Associations of coronary artery calcified plaque density with mortality in type 2 diabetes: the Diabetes Heart Study

Background

Coronary artery calcified plaque (CAC) is strongly predictive of cardiovascular disease (CVD) events and mortality, both in general populations and individuals with type 2 diabetes at high risk for CVD. CAC is typically reported as an Agatston score, which is weighted for increased plaque density. However, the role of CAC density in CVD risk prediction, independently and with CAC volume, remains unclear.

Methods

We examined the role of CAC density in individuals with type 2 diabetes from the family-based Diabetes Heart Study and the African American-Diabetes Heart Study. CAC density was calculated as mass divided by volume, and associations with incident all-cause and CVD mortality [median follow-up 10.2 years European Americans (n = 902, n = 286 deceased), 5.2 years African Americans (n = 552, n = 93 deceased)] were examined using Cox proportional hazards models, independently and in models adjusted for CAC volume.

Results

In European Americans, CAC density, like Agatston score and volume, was consistently associated with increased risk of all-cause and CVD mortality (p ≤ 0.002) in models adjusted for age, sex, statin use, total cholesterol, HDL, systolic blood pressure, high blood pressure medication use, and current smoking. However, these associations were no longer significant when models were additionally adjusted for CAC volume. CAC density was not significantly associated with mortality, either alone or adjusted for CAC volume, in African Americans.

Conclusions

CAC density is not associated with mortality independent from CAC volume in European Americans and African Americans with type 2 diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0714-z) contains supplementary material, which is available to authorized users.

Ghrelin attenuates vascular calcification in diabetic patients with amputation

Vascular calcification is established to be a critical factor in diabetes mellitus, which causes cardiovascular and amputation complication of diabetic patients. OPG/RANKL/RANK axis serves as a regulatory role in vascular calcification. Ghrelin, an endogenous ligand of growth hormone secretagogue receptor (GHSR), has been reported to exhibit potent cardiovascular protective effects. However, the role of ghrelin in the regulation of diabetic vascular calcification is still elusive. Here, we reported the role of ghrelin and its relationship with OPG/RANKL/RANK system in patients with diabetic foot amputation. In vivo and in vitro investigations were performed. Sixty type 2 diabetic patients with foot amputation were enrolled in vivo investigation, and they were divided into three groups through Doppler ultrasound: mild stenosis group (n=20), moderate stenosis group (n=20), and severe stenosis/occlusion group (n=20). Morphological analysis results showed diffused calcium depositions in the anterior tibial artery of diabetic amputees. Compared with the mild and moderate stenosis group, the severe stenosis/occlusion group had more spotty calcium depositions in atherosclerotic plaques. Western blot analysis indicated the expressions of osteoprotegerin (OPG) and ghrelin were downregulated, while the expression of receptor activator of nuclear factor kappa B ligand (RANKL) was upregulated with the vascular stenosis aggravation. Pearson correlation analysis revealed a negative correlation between calcium content and ghrelin levels (r=-0.58, P<0.001), as well as the ghrelin levels and sRANKL levels (r=-0.57, P<0.001). Meanwhile, OPG levels were positively correlated with ghrelin levels (r=0.63, P<0.001). From in vitro investigation, we found that the high-glucose (HG), high-lipid (HL), and β-glycerophosphate (β-GP) considerably increased the total calcium content, ALP activity, and expression of osteogenic markers in vascular smooth muscle cells (VSMCs). Ghrelin blunted calcification in a dose-dependent manner. In addition, ghrelin upregulated OPG expression and downregulated RANKL expression in VSMC calcification when anti-OPG antibody and RANKL were performed. Collectively, we therefore conclude serum ghrelin level may be a predictor of diabetic vascular calcification. The possible mechanism may be related with OPG/RANKL signal.

Coronary Artery Calcium Score and Bone Metabolism: A Pilot Study in Postmenopausal Women

Background

Since 1991 many studies evaluated the link between cardiovascular diseases and osteoporosis, two age-related conditions, but the main common pathologic pathway has not been determined yet. The histological similarity between arterial calcified plaque and bone matrix and involvement of similar cells and mediators provide a special field of research. Therefore in the present study, we aimed to evaluate the relationship between coronary artery calcium score (CACS) as a surrogate marker of atherosclerosis and bone mediators and parameters in postmenopausal women.

Methods

Eleven postmenopausal women who had CACS higher than 80 were enrolled into the study and underwent bone densitometry. In addition, their serum and urine samples were taken for measuring osteoprotegerin, osteocalcin, and β cross laps. Patients' 10-year probability of fracture was calculated by the World Health Organization fracture-risk assessment tool (FRAX).

Results

The regression analysis of our results showed the association between CACS and OC (std β=0.66, 95% confidence interval [CI] 5.47-72.27, P=0.027), femoral bone density (std β=−0.6, 95% CI -6864.34-14.27, P=0.05) and T-score (std β=−0.6, 95% CI −773.08-1.28, P=0.05) which remained significant after adjustment for age, weight, years since menopause and body mass index. No association was found between CACS and osteoprotegerin, spinal bone density and FRAX score.

Conclusions

In conclusion, this pilot study with small sample size showed the potential association between CACS and osteocalcin, femoral bone density and T-score. However, the relationship between CACS and osteoprotegerin, receptor activator of nuclear factor-kappa B ligand, FRAX score and other bone parameters remain to be clarified in larger sample size studies.

The Association between Bone Quality and Atherosclerosis: Results from Two Large Population-Based Studies

OBJECTIVE

It is highly debated whether associations between osteoporosis and atherosclerosis are independent of cardiovascular risk factors. We aimed to explore the associations between quantitative ultrasound (QUS) parameters at the heel with the carotid artery intima-media thickness (IMT), the presence of carotid artery plaques, and the ankle-brachial index (ABI).

METHODS

The study population comprised 5680 men and women aged 20-93 years from two population-based cohort studies: Study of Health in Pomerania (SHIP) and SHIP-Trend. QUS measurements were performed at the heel. The extracranial carotid arteries were examined with B-mode ultrasonography. ABI was measured in a subgroup of 3853 participants. Analyses of variance and linear and logistic regression models were calculated and adjusted for major cardiovascular risk factors.

RESULTS

Men but not women had significantly increased odds for carotid artery plaques with decreasing QUS parameters independent of diabetes mellitus, dyslipidemia, and hypertension. Beyond this, the QUS parameters were not significantly associated with IMT or ABI in fully adjusted models.

CONCLUSIONS

Our data argue against an independent role of bone metabolism in atherosclerotic changes in women. Yet, in men, associations with advanced atherosclerosis, exist. Thus, men presenting with clinical signs of osteoporosis may be at increased risk for atherosclerotic disease.

Bone Mineral Density and Progression of Subclinical Atherosclerosis in African-Americans With Type 2 Diabetes

CONTEXT

Relative to European Americans, calcified atherosclerotic plaque (CP) is less prevalent and severe in African-Americans (AAs).

OBJECTIVE

Predictors of progression of CP in the aorta, carotid, and coronary arteries were examined in AAs over a mean 5.3 ± 1.4-year interval.

DESIGN

This is the African American-Diabetes Heart Study.

SETTING

A type 2 diabetes (T2D)-affected cohort was included.

PARTICIPANTS

A total of 300 unrelated AAs with T2D; 50% female, mean age 55 ± 9 years, baseline hemoglobin A1c 8.1 ± 1.8% was included.

MAIN OUTCOME MEASURES

Glycemic control, renal parameters, vitamin D, and computed tomography-derived measures of adiposity, vascular CP, and volumetric bone mineral density (vBMD) in lumbar and thoracic vertebrae were obtained at baseline and follow-up.

RESULTS

CP increased in incidence and quantity/mass in all three vascular beds over the 5-year study (P < .0001). Lower baseline lumbar and thoracic vBMD were associated with progression of abdominal aorta CP (P < .008), but not progression of carotid or coronary artery CP. Lower baseline estimated glomerular filtration rate was associated with progression of carotid artery CP (P = .0004), and higher baseline pericardial adipose volume was associated with progression of coronary artery (P = .001) and aorta (P = .0006) CP independent of body mass index. There was a trend for an inverse relationship between change in thoracic vBMD and change in aortic CP (P = .05).

CONCLUSIONS

In this longitudinal study, lower baseline thoracic and lumbar vBMD and estimated glomerular filtration rate and higher pericardial adipose volumes were associated with increases in CP in AAs with T2D. Changes in these variables and baseline levels and/or changes in glycemic control, albuminuria, and vitamin D were not significantly associated with progression of CP.

Redox signaling in cardiovascular pathophysiology: A focus on hydrogen peroxide and vascular smooth muscle cells

Oxidative stress represents excessive intracellular levels of reactive oxygen species (ROS), which plays a major role in the pathogenesis of cardiovascular disease. Besides having a critical impact on the development and progression of vascular pathologies including atherosclerosis and diabetic vasculopathy, oxidative stress also regulates physiological signaling processes. As a cell permeable ROS generated by cellular metabolism involved in intracellular signaling, hydrogen peroxide (H₂O₂) exerts tremendous impact on cardiovascular pathophysiology. Under pathological conditions, increased oxidase activities and/or impaired antioxidant systems results in uncontrolled production of ROS. In a pro-oxidant environment, vascular smooth muscle cells (VSMC) undergo phenotypic changes which can lead to the development of vascular dysfunction such as vascular inflammation and calcification. Investigations are ongoing to elucidate the mechanisms for cardiovascular disorders induced by oxidative stress. This review mainly focuses on the role of H₂O₂ in regulating physiological and pathological signals in VSMC.

Plasma FGF23 and Calcified Atherosclerotic Plaque in African Americans with Type 2 Diabetes Mellitus

BACKGROUND

Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone implicated in disorders of serum phosphorus concentration and vitamin D. The role of FGF23 in vascular calcification remains controversial.

METHODS

Relationships between FGF23 and coronary artery calcified atherosclerotic plaque (CAC), aortoiliac calcified plaque (CP), carotid artery CP, volumetric bone mineral density (vBMD), albuminuria, and estimated glomerular filtration rate (eGFR) were determined in 545 African Americans with type 2 diabetes (T2D) and preserved kidney function in African American-Diabetes Heart Study participants. Generalized linear models were fitted to test associations between FGF23 and cardiovascular, bone, and renal phenotypes, and change in measurements over time, adjusting for age, gender, African ancestry proportion, body mass index, diabetes duration, hemoglobin A1c, blood pressure, renin-angiotensin-system inhibitors, statins, calcium supplements, serum calcium, and serum phosphate.

RESULTS

The sample was 56.7% female with a mean (SD) age of 55.6 (9.6) years, diabetes duration of 10.3 (8.2) years, eGFR 90.9 (22.1) ml/min/1.73 m2, urine albumin:creatinine ratio (UACR) 151 (588) (median 13) mg/g, plasma FGF23 161 (157) RU/ml, and CAC 637 (1,179) mg. In fully adjusted models, FGF23 was negatively associated with eGFR (p < 0.0001) and positively associated with UACR (p < 0.0001) and CAC (p = 0.0006), but not with carotid CP or aortic CP. Baseline FGF23 concentration did not associate with changes in vBMD or CAC after a mean of 5.1 years follow-up.

CONCLUSIONS

Plasma FGF23 concentrations were independently associated with subclinical coronary artery disease, albuminuria, and kidney function in the understudied African American population with T2D. Findings support relationships between FGF23 and vascular calcification, but not between FGF23 and bone mineral density, in African Americans lacking advanced nephropathy.

Vitamin D Associations With Renal, Bone, and Cardiovascular Phenotypes: African American-Diabetes Heart Study

CONTEXT

Vitamin D binding protein (DBP) is an important determinant of bioavailable vitamin D (BAVD) and may provide clues to racial variation in osteoporosis and atherosclerosis.

OBJECTIVE

The objective was to assess relationships between DBP, BAVD, 25-hydroxyvitamin D (25OHD), and 1,25 di-hydroxyvitamin D (1,25OH2D) with kidney, bone, adipose, and atherosclerosis phenotypes in African Americans with type 2 diabetes.

DESIGN

Cross-sectional (N = 545) and longitudinal (N = 288; mean 5.1 ± 0.9-year follow-up) relationships between vitamin D concentrations with renal phenotypes, vertebral bone mineral density, aorto-iliac, coronary artery, and carotid artery calcified plaque (CP), and adipose tissue volumes were studied.

SETTING

African American-Diabetes Heart Study.

PATIENTS

Participants were 56.7% female with mean ± standard deviation (sd) age 55.6 ± 9.6 years, diabetes duration 10.3 ± 8.2 years, and eGFR 90.9 ± 22.1 ml/min/1.73 m(2).

INTERVENTIONS

None.

MAIN OUTCOMES AND MEASURES

Associations tested between vitamin D and the previously mentioned phenotypes adjusting for age, sex, African ancestry proportion, diabetes duration, statins, smoking, changes in estimated glomerular filtration rate, body mass index, hemoglobin A1c, and blood pressure.

RESULTS

1,25OH2D was inversely associated with change in coronary artery CP (parameter estimate [β] -0.005, standard error [SE] 0.002; P = .037), with a trend for change in carotid artery CP (β -0.007, SE 0.004; P = .074). Further adjustment for renin-aldosterone-system blockade revealed inverse association between 1,25OH2D and change in albuminuria (β -0.004, SE 0.002; P = .037). DBP, BAVD, and 25OHD did not associate significantly with changes in albuminuria, CP, or bone mineral density. BAVD was inversely associated with visceral, subcutaneous, intermuscular, and pericardial adipose volumes.

CONCLUSIONS

In contrast to BAVD and 25OHD, only 1,25OH2D levels were significantly and inversely associated with changes in subclinical atherosclerosis and albuminuria in African Americans, suggesting potential beneficial effects.

An update on diabetes related skeletal fragility

There are several mechanisms by which diabetes could affect bone mass and strength. These mechanisms include insulin deficiency; hyperglycemia; the accumulation of advanced glycation end products that may influence collagen characteristics; marrow adiposity and bone inflammation. Furthermore, associated diabetic complications and treatment with thaizolidinediones may also increase risk of fracturing. The following article provides its readers with an update on the latest information pertaining to diabetes related bone skeletal fragility. In the authors' opinion, future studies are needed in order to clarify the impact of different aspects of diabetes metabolism, glycemic control, and specific treatments for diabetes on bone. Given that dual energy x-ray absorptiometry is a poor predictor of bone morbidity in this group of patients, there is a need to explore novel approaches for assessing bone quality. It is important that we develop a better understanding of how diabetes affects bone in order to improve our ability to protect bone health and prevent fractures in the growing population of adults with diabetes.

Prediction of mortality using a multi-bed vascular calcification score in the Diabetes Heart Study

Background

Vascular calcified plaque, a measure of subclinical cardiovascular disease (CVD), is unlikely to be limited to a single vascular bed in patients with multiple risk factors. Consideration of vascular calcified plaque as a global phenomenon may allow for a more accurate assessment of the CVD burden. The aim of this study was to examine the utility of a combined vascular calcified plaque score in the prediction of mortality.

Methods

Vascular calcified plaque scores from the coronary, carotid, and abdominal aortic vascular beds and a derived multi-bed score were examined for associations with all-cause and CVD-mortality in 699 European-American type 2 diabetes (T2D) affected individuals from the Diabetes Heart Study. The ability of calcified plaque to improve prediction beyond Framingham risk factors was assessed.

Results

Over 8.4 ± 2.3 years (mean ± standard deviation) of follow-up, 156 (22.3%) participants were deceased, 74 (10.6%) from CVD causes. All calcified plaque scores were significantly associated with all-cause (HR: 1.4-1.8; p < 1x10⁻⁵) and CVD-mortality (HR: 1.5-1.9; p < 1×10⁻⁴) following adjustment for Framingham risk factors. Associations were strongest for coronary calcified plaque. Improvement in prediction of outcome beyond Framingham risk factors was greatest using coronary calcified plaque for all-cause mortality (AUC: 0.720 to 0.757, p = 0.004) and the multi-bed score for CVD mortality (AUC: 0.731 to 0.767, p = 0.008).

Conclusions

Although coronary calcified plaque and the multi-bed score were the strongest predictors of all-cause mortality and CVD-mortality respectively in this T2D-affected sample, carotid and abdominal aortic calcified plaque scores also significantly improved prediction of outcome beyond traditional risk factors and should not be discounted as risk stratification tools.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-014-0160-5) contains supplementary material, which is available to authorized users.

Relationship of Dickkopf1 (DKK1) with cardiovascular disease and bone metabolism in Caucasian type 2 diabetes mellitus

Objectives

Dickkopf-1 (DKK1) is a potent inhibitor of Wnt signalling, which exerts anabolic effects on bone and also takes part in the regulation of vascular cells. Our aims were to evaluate serum DKK1 in type 2 diabetes (T2DM) patients and to analyze its relationships with cardiovascular disease (CVD). We also evaluated the relationship between DKK1 and bone metabolism.

Design

We conducted a cross-sectional study in which we measured serum DKK1 (ELISA, Biomedica) in 126 subjects: 72 patients with T2DM and 54 non-diabetic subjects. We analysed its relationship with clinical CVD, preclinical CVD expressed as carotid intima media thickness (IMT), and bone metabolism.

Results

T2DM patients with CVD (P = 0,026) and abnormal carotid IMT (P = 0,038) had higher DKK1 concentrations. DKK1 was related to the presence of CVD in T2DM, independently of the presence of risk factors for atherosclerosis. Therefore, for each increase of 28 pg/ml of serum DKK1 there was a 6,2% increase in the risk of CVD in T2DM patients. The ROC curve analysis to evaluate the usefulness of DKK1 as a marker for high risk of CVD showed an area under the curve of 0,667 (95% CI: 0,538–0,795; P = 0,016). In addition, there was a positive correlation between serum DKK1 and spine bone mineral density in the total sample (r = 0,183; P = 0,048).

Conclusion

In summary, circulating DKK1 levels are higher in T2DM with CVD and are associated with an abnormal carotid IMT in this cross-sectional study. DKK1 may be involved in vascular disease of T2DM patients.

Quantitative analysis of abdominal aortic calcification in CKD patients without dialysis therapy by use of the Agatston score

BACKGROUND/AIM

The aim of the present study was to quantitatively examine factors associated with aortic calcification in non-dialysis CKD patients.

METHODS

We quantitatively investigated aortic calcification from the renal artery to the bifurcation in 149 non-dialysis CKD patients (58±16 years; 96 males and 53 females, 48 diabetics; eGFR 40.3 ± 29.3 ml/min), and measured Agatston scores using multi-slice computed tomography.

RESULT

Of 149 patients, aortic calcification was present in 117. In patients with aortic calcification, age (p<0.001), C-reactive protein (p<0.001), and intact-PTH (p < 0.001) were significantly higher, estimated glomerular filtration rate (eGFR) was significantly lower (p<0.001), and diabetes was observed more often (p<0.05). In regards to the degree of aortic calcification, the Agatston scores correlated significantly and positively with age (ρ=0.438, p<0.001) and serum phosphate (ρ=0.208, p=0.024), and correlated significantly but negatively with e-GFR (ρ=-0.353, p<0.001). In multiple regression analysis, eGFR was associated significantly and independently with the log [Agatston score] (β=-0.346, p<0.01), after adjustment for several confounders including serum phosphate and the presence of diabetes.

CONCLUSIONS

Hyperphospatemia, chronic inflammation, diabetes, and decreased GFR are associated significantly with the presence of aortic calcification in non-dialysis CKD patients. Decreased eGFR was associated significantly and independently with the quantitative degree of aortic calcification.

Association of volumetric bone mineral density with abdominal aortic calcification in African ancestry men

SUMMARY

We tested for association between cortical and trabecular volumetric bone mineral density (vBMD) with abdominal aortic calcification (AAC) prevalence in 278 Afro-Caribbean men. AAC was present in 68.3 % of the men. Greater cortical, but not trabecular, vBMD was associated with significantly decreased odds of AAC independent of traditional risk factors.

INTRODUCTION

The aim of this study is to assess the prevalence and correlates of AAC in a sample of 278 Afro-Caribbean men (mean age 56) and to test for a largely unexplored association between cortical and trabecular vBMD with AAC prevalence.

METHODS

Men were recruited consecutively as part of an ongoing prospective cohort study of body composition in men aged 40+. For this analysis, AAC was assessed by computed tomography of the abdomen from L3 to S1. Aortic calcium was scored using the Agatston method, and prevalence was defined as a score ≥10 to rule out false positives. Men also had BMD assessed using peripheral quantitative computed tomography at 4 % (trabecular vBMD) and 33 % (cortical vBMD) of the radius and tibia.

RESULTS

Abdominal aortic calcification was present in 68.3 % of the men. Significant independent predictors of AAC prevalence were increased age, increased BMI, hypertension, and current smoking. Age was the strongest predictor, with each SD (7.8 year) increase in age conferring 2.7 times increased odds of having AAC (P < 0.0001). A one SD greater cortical, but not trabecular, vBMD was associated with a significant decreased odds of AAC prevalence independent of other traditional risk factors (OR 0.65; 95 % CI 0.45-0.92).

CONCLUSIONS

Cortical vBMD is inversely associated with AAC presence. This finding suggests that there may be shared physiology between cortical bone compartment remodeling and vascular calcification.

Activation of AKT by O-linked N-acetylglucosamine induces vascular calcification in diabetes mellitus

RATIONALE

Vascular calcification is a serious cardiovascular complication that contributes to the increased morbidity and mortality of patients with diabetes mellitus. Hyperglycemia, a hallmark of diabetes mellitus, is associated with increased vascular calcification and increased modification of proteins by O-linked N-acetylglucosamine (O-GlcNAcylation).

OBJECTIVE

We sought to determine the role of protein O-GlcNAcylation in regulating vascular calcification and the underlying mechanisms.

METHODS AND RESULTS

Low-dose streptozotocin-induced diabetic mice exhibited increased aortic O-GlcNAcylation and vascular calcification, which was also associated with impaired aortic compliance in mice. Elevation of O-GlcNAcylation by administration of Thiamet-G, a potent inhibitor for O-GlcNAcase that removes O-GlcNAcylation, further accelerated vascular calcification and worsened aortic compliance of diabetic mice in vivo. Increased O-GlcNAcylation, either by Thiamet-G or O-GlcNAcase knockdown, promoted calcification of primary mouse vascular smooth muscle cells. Increased O-GlcNAcylation in diabetic arteries or in the O-GlcNAcase knockdown vascular smooth muscle cell upregulated expression of the osteogenic transcription factor Runx2 and enhanced activation of AKT. O-GlcNAcylation of AKT at two new sites, T430 and T479, promoted AKT phosphorylation, which in turn enhanced vascular smooth muscle cell calcification. Site-directed mutation of AKT at T430 and T479 decreased O-GlcNAcylation, inhibited phosphorylation of AKT at S473 and binding of mammalian target of rapamycin complex 2 to AKT, and subsequently blocked Runx2 transactivity and vascular smooth muscle cell calcification.

CONCLUSIONS

O-GlcNAcylation of AKT at 2 new sites enhanced AKT phosphorylation and activation, thus promoting vascular calcification. Our studies have identified a novel causative effect of O-GlcNAcylation in regulating vascular calcification in diabetes mellitus and uncovered a key molecular mechanism underlying O-GlcNAcylation-mediated activation of AKT.

Sclerostin is positively associated with bone mineral density in men and women and negatively associated with carotid calcified atherosclerotic plaque in men from the African American-Diabetes Heart Study

CONTEXT

Bone mineral density (BMD) and calcified atherosclerotic plaque (CP) demonstrate inverse relationships. Sclerostin, an endogenous regulator of the Wnt pathway and bone formation, has been associated with impaired osteoblast activation and may play a role in vascular calcification.

OBJECTIVE

Our objective was to assess the relationships between sclerostin, BMD, and CP.

DESIGN

Generalized linear models were fitted to test for associations between sclerostin, volumetric BMD (vBMD), and CP.

PARTICIPANTS

A targeted population of 450 unrelated African Americans (AAs) with type 2 diabetes (T2D) was 56% female with mean/SD/median age of 55.4/9.5/55.0 years and a diabetes duration of 10.3/8.2/8.0 years.

MAIN OUTCOME MEASURES

Plasma sclerostin, computed tomography-derived thoracic and lumbar vertebrae trabecular vBMD, coronary artery, carotid artery, and aortoiliac CP were measured.

RESULTS

Plasma sclerostin was 1119/401/1040 pg/mL, thoracic vBMD was 206.3/52.4/204.8 mg/cm3, lumbar vBMD was 180.7/47.0/179.0 mg/cm3, coronary artery CP score was 284/648/13, carotid artery CP score was 46/132/0, and aortoiliac CP score was 1613/2910/282. Sclerostin levels were higher in men than women (P<.0001). Before and after adjusting for age, sex, body mass index, blood pressure, smoking, hemoglobin A1c, and low-density lipoprotein-cholesterol, plasma sclerostin levels were positively associated with thoracic and lumbar vertebrae vBMD (P<.0001). Sex-stratified analyses verified significant relationships in both men and women (both P<.001). Sclerostin was not associated with CP except for an inverse relationship with carotid CP in men (fully adjusted model, P=.03).

CONCLUSIONS

In this cross-sectional study of AA men and women with T2D, circulating sclerostin was positively associated with vBMD in the spine in both sexes and inversely associated with carotid artery CP in men. Sclerostin may play a role in skeletal mineral metabolism in AA but fails to explain inverse relationships between BMD and CP.

The influence of subclinical cardiovascular disease and related risk factors on cognition in type 2 diabetes mellitus: The DHS-Mind study

We hypothesized that measures of coronary artery calcified plaque (CAC) collected at baseline from the Diabetes Heart Study (DHS) would explain associations between cognition and diabetes collected at follow-up approximately 7 years later. The DHS is a sibling study of cardiovascular disease (CVD) in a cohort with a high prevalence of type 2 diabetes (~80%). Associations between baseline CAC and cognitive performance were tested using generalized estimating equations and mixed effects models to adjust for familial relationships. Diabetes status was associated (p<0.05) with poorer performance on tests of verbal memory, processing speed, and semantic fluency adjusting for age, sex, education, and hypertension status. As hypothesized, including CAC in the statistical model attenuated this association. Additionally, CAC and fasting glucose predicted performance in tasks not associated with diabetes status in this study (Stroop Task, Phonemic Fluency). These results confirm work attributing the heterogeneity of cognitive outcomes in type 2 diabetes to subclinical risk factors that combine to affect different aspects of brain function. Importantly, these results imply that risk factor intervention should begin before comorbidities, particularly CVD, become clinically apparent.

Osteoporosis and atherosclerosis: a post-mortem MDCT study of an elderly cohort

OBJECTIVES

To evaluate how far fracture status and bone mineral density (BMD) correlate with the vascular calcification score (CS).

METHODS

On 29 complete human cadavers (17 female, 12 male; mean age at death was 85.57 years), multi-detector computed tomography was performed to assess the spine fracture status (fracture vs non-fracture [FX vs non-FX]) and CS of the coronary arteries (Coro-CS), the aorta (Aorta-CS) and the pelvic vessels (Iliac-CS). Quantitative computed tomography of the lumbar spine was performed to estimate overall BMD (osteoporotic [BMD <80 mg/cm(3)] vs non-osteoporotic [BMD ≥ 80 mg/cm(3)]).

RESULTS

Gender-specific differences in statistical significance were only observed for Aorta-CS and Iliac-CS but not for Coro-CS. When comparing the osteoporotic with the non-osteoporotic group, statistically significant differences were only found for Iliac-CS (P < 0.05); however, linear regression analysis showed none of the CSs to significantly correlate with BMD.

CONCLUSIONS

In our small post-mortem elderly population, statistically significant associations of fracture status and BMD with CS were only observed between the osteoporotic and non-osteoporotic groups for the pelvic vessels but not for the coronary arteries and the aorta.

KEY POINTS

• Gender-specific differences were observed for aortic and iliac calcification score (CS). • There was no difference in coronary CS between females and males. • Only iliac CS was different in osteoporotic and non-osteoporotic subjects. • In linear regression analysis, CS showed no correlation with BMD. • In univariate analysis, gender was a BMD and iliac CS confounder.

Relationships between serum adiponectin and bone density, adiposity and calcified atherosclerotic plaque in the African American-Diabetes Heart Study

CONTEXT

Adiposity, bone mineral density (BMD), and calcified atherosclerotic plaque (CP) exhibit complex interrelationships that are not well understood. Adipokines vary in relation to changes in body composition and may play roles in regulation of BMD and risk of cardiovascular disease.

OBJECTIVE

Our objective was to examine the relationship between serum adiponectin and quantitative computed tomography-derived measures of volumetric BMD (vBMD) in thoracic and lumbar vertebrae, adipose tissue volumes, and CP in coronary, carotid, and infrarenal aortoiliac arteries. Generalized linear models were fitted to test for associations between adiponectin and measured phenotypes.

PARTICIPANTS

A total of 479 unrelated African Americans with type 2 diabetes, 57% female with a mean ± SD (median) age of 55.6 ± 9.5 (55.0) years and diabetes duration of 10.3 ± 8.2 (8.0) years.

RESULTS

Serum adiponectin was 8.26 ± 7.41 (6.10) μg/mL, coronary artery CP mass score was 280 ± 634 (14), carotid artery CP was 47 ± 133 (0), and aortoiliac CP was 1616 ± 2864 (319). Women had significantly higher body mass index and serum adiponectin and lower coronary and carotid artery calcium than males (all P < .05). Before and after adjusting for age, sex, body mass index, mean arterial pressure, smoking status, hemoglobin A1c, thiazolidinedione use, and low-density lipoprotein-cholesterol, adiponectin was inversely associated with thoracic and lumbar vertebral vBMD [parameter estimates (PEs) of -0.06 and -0.021, respectively; both P < .0005], visceral adipose tissue (PE -0.02; P < 0.0001), and C-reactive protein (PE -0.07; P < .0001) and positively associated with intermuscular adipose tissue (PE 0.01; P = .03). After covariate adjustment, significant associations were not observed between adiponectin and CP in any vascular bed (P > .1).

CONCLUSION

Serum adiponectin levels were inversely associated with cross-sectional measures of thoracic and lumbar vertebral vBMD, inflammation, and visceral adiposity in African Americans but not with vascular CP after adjustment for covariates. The data support a regulatory/signaling role for adiponectin in the modulation of bone density.

Measurement of phantomless thoracic bone mineral density on coronary artery calcium CT scans acquired with various CT scanner models

PURPOSE

To determine the accuracy and precision of thoracic phantomless bone mineral density (BMD) measurements obtained on coronary artery calcium (CAC) computed tomography (CT) scans by using a variety of commercially available CT scanners.

MATERIALS AND METHODS

The institutional review board approved this Health Insurance Portability and Accountability Act-compliant study. A total of 4126 asymptomatic subjects (2022 [49%] men, 2104 [51%] women; mean age, 63.7 years ± 11.8 [standard deviation]) underwent CAC CT with the use of a quantitative CT calibration phantom for evaluation of subclinical atherosclerosis. Two hundred eighty subjects also underwent CT of the chest, abdomen, and pelvis (C7 through L5). Mean BMD of three consecutive thoracic vertebrae (in the T7-T10 range) was measured in all 4126 subjects. Individual calibration factors for each phantom insert and a general calibration factor for the spine were determined for each CT scanner model. The study population was then divided into three subgroups: All calibration factors were generated from group 1 (n = 1536) and were applied and tested in group 2 (n = 1587), and effects of various image acquisition parameters were assessed in group 3 (n = 1003). Accuracy (bias) and precision of thoracic phantomless BMD measurements across 14 CT scanner models from five manufacturers were determined.

RESULTS

Phantomless BMD values correlated highly with standard phantom-based quantitative CT BMD values (r = 0.987, P < .001). Bias was 3.9% ± 1.4 for phantomless BMD measurements, and the mean coefficient of variation for the general calibration factor was 4.9% ± 2.4.

CONCLUSION

Phantomless BMD can be measured accurately on CAC CT scans acquired with a variety of CT scanners without additional radiation exposure.

Plasma Dickkopf1 (DKK1) concentrations negatively associate with atherosclerotic calcified plaque in African-Americans with type 2 diabetes

BACKGROUND

Bone mineral density (BMD) and atherosclerotic arterial calcified plaque (CP) demonstrate inverse relationships through unknown mechanisms. Dickkopf-1 (DKK1) is an endogenous inhibitor of bone formation, and serum DKK1 has been associated with impaired osteoblast activation and susceptibility to bone loss. Plasma DKK1, BMD in the spine, and CP in three arterial beds were assessed in African-Americans (AAs) to determine relationships of serum DKK1 with atherosclerotic vascular calcification.

METHODS

Plasma DKK1, computed tomography-derived trabecular volumetric BMD (vBMD) in thoracic and lumbar vertebrae, and coronary artery, carotid artery, and aortoiliac CP were measured in 450 unrelated AAs with type 2 diabetes. Generalized linear models were fitted to test for associations between DKK1, vBMD, and CP.

RESULTS

Participants were 56% female with mean/SD/median age of 55.4/9.5/55.0 yr, diabetes duration of 10.3/8.2/8.0 yr, plasma DKK1 of 481.6/271.8/417 pg/ml, coronary artery CP mass score of 284/648/13, carotid artery CP mass score of 46/132/0, and aortoiliac CP mass score of 1613/2910/282. Adjusting for age, sex, body mass index, mean arterial blood pressure, smoking, hemoglobin A(1c), and low-density lipoprotein-cholesterol, DKK1 was inversely associated with coronary artery and aortoiliac CP [parameter estimates -0.0011 (P = 0.0137) and -0.0010 (P = 0.0214), respectively], with a trend for carotid artery CP (P = 0.1404). No associations were observed between DKK1 and vBMD in the thoracic or lumbar vertebrae.

CONCLUSIONS

Plasma DKK1 levels were inversely associated with coronary artery and aortoiliac CP, but not vBMD, in this cross-sectional study of AAs with type 2 diabetes. DKK1 may play a role in vascular mineral metabolism in this clinical setting.

Admixture mapping of coronary artery calcified plaque in African Americans with type 2 diabetes mellitus

BACKGROUND

The presence and severity of coronary artery calcified plaque (CAC) differs markedly between individuals of African and European descent, suggesting that admixture mapping may be informative for identifying genetic variants associated with subclinical cardiovascular disease.

METHODS AND RESULTS

Admixture mapping of CAC was performed in 1040 unrelated African Americans with type 2 diabetes mellitus from the African American-Diabetes Heart Study, Multi-Ethnic Study of Atherosclerosis and Family Heart Study using the Illumina custom ancestry informative marker panel. All cohorts obtained computed tomography scanning of the coronary arteries using identical protocols. For each ancestry informative marker, the probability of inheriting 0, 1, and 2 copies of a European-derived allele was determined. Linkage analysis was performed by testing for association between each ancestry informative marker using these probabilities and CAC, accounting for global ancestry, age, sex, and study. Markers on 1p32.3 in the GLIS1 gene (rs6663966, logarithm of odds [LOD]=3.7), 1q32.1 near CHIT1 (rs7530895, LOD=3.1), 4q21.2 near PRKG2 (rs1212373, LOD=3.0), and 11q25 in the OPCML gene (rs6590705, LOD=3.4) had statistically significant LOD scores, whereas markers on 8q22.2 (rs6994682, LOD=2.7), 9p21.2 (rs439314, LOD=2.7), and 13p32.1 (rs7492028, LOD=2.8) manifested suggestive evidence of linkage. These regions were uniformly characterized by higher levels of European ancestry associating with higher levels or odds of CAC. Findings were replicated in 1350 African Americans without diabetes mellitus and 2497 diabetic European Americans from Multi-Ethnic Study of Atherosclerosis and the Diabetes Heart Study.

CONCLUSIONS

Fine mapping these regions will likely identify novel genetic variants that contribute to CAC and clarify racial differences in susceptibility to subclinical cardiovascular disease.

Effect of race and genetics on vitamin D metabolism, bone and vascular health

The pathophysiology of chronic kidney disease-mineral and bone disorder accounts for an inverse relationship between bone mineralization and vascular calcification in progressive nephropathy. Inverse associations between bone mineral density (BMD) and calcified atherosclerotic plaque are also observed in individuals of European and African ancestry without nephropathy, suggesting a mechanistic link between these processes that is independent of kidney disease. Despite lower dietary calcium intake and serum 25-hydroxyvitamin D (25(OH)D) concentrations, African Americans have higher BMD and develop osteoporosis less frequently than do European Americans. Moreover, despite having more risk factors for cardiovascular disease, African Americans have a lower incidence and severity of calcified atherosclerotic plaque formation than do European Americans. Strikingly, evidence is now revealing that serum 25(OH)D and/or 1,25 dihydroxyvitamin D levels associate positively with atherosclerosis but negatively with BMD in African Americans; by contrast, vitamin D levels associate negatively with atherosclerosis and positively with BMD in individuals of European ancestry. Biologic phenomena, therefore, seem to contribute to population-specific differences in vitamin D metabolism, bone and vascular health. Genetic and mechanistic approaches used to explore these differences should further our understanding of bone-blood vessel relationships and explain how African ancestry protects from osteoporosis and calcified atherosclerotic plaque, provided that access of African Americans to health care is equivalent to individuals of European ethnic origin. Ultimately, in our opinion, a new mechanistic understanding of the relationships between bone mineralization and vascular calcification will produce novel approaches for disease prevention in aging populations.

Arterial stiffness, vascular calcification and bone metabolism in chronic kidney disease

Patients with chronic kidney disease (CKD) have an extremely poor cardiovascular outcome. Arterial stiffness, a strong independent predictor of survival in CKD, is connected to arterial media calcification. A huge number of different factors contribute to the increased arterial calcification and stiffening in CKD, a process which is in parallel with impaired bone metabolism. This coincidence was demonstrated to be part of the direct inhibition of calcification in the vessels, which is a counterbalancing effect but also leads to low bone turnover. Due to the growing evidence, the definition of “CKD mineral bone disorder” was created recently, underlining the strong connection of the two phenomena. In this review, we aim to demonstrate the mechanisms leading to increased arterial stiffness and the up-to date data of the bone-vascular axis in CKD. We overview a list of the different factors, including inhibitors of bone metabolism like osteoprotegerin, fetuin-A, pyrophosphates, matrix Gla protein, osteopontin, fibroblast growth factor 23 and bone morphogenic protein, which seem to play role in the progression of vascular calcification and we evaluate their connection to impaired arterial stiffness in the mirror of recent scientific results.

Relationships between calcified atherosclerotic plaque and bone mineral density in African Americans with type 2 diabetes

Inverse relationships have been reported between bone mineral density (BMD) and calcified atherosclerotic plaque (CP). This suggests these processes may be related. We examined relationships between BMD and CP in 753 African Americans with type 2 diabetes from 664 families, accounting for the effects of modifiable cardiovascular disease (CVD) risk factors. Association analyses were performed using generalized estimating equations (GEEs) to assess cross-sectional relationships between computed tomography-determined measures of thoracic and lumbar vertebral volumetric BMD (vBMD) and CP in the coronary and carotid arteries and infrarenal aorta. Significant inverse associations were seen between thoracic and lumbar vBMD and CP in all three vascular beds in unadjusted analyses. A fully adjusted model accounting for age, sex, body mass index, systolic blood pressure, low-density lipoprotein cholesterol, C-reactive protein, hemoglobin A(1c), smoking, and hormone-replacement therapy revealed significant inverse associations between thoracic vBMD and CP in coronary and carotid arteries and aorta, whereas lumbar vBMD was associated with CP in coronary artery and aorta. Inverse associations exist between vertebral BMD and calcified atherosclerotic plaque in African-American men and women with type 2 diabetes. This relationship was independent of conventional CVD risk factors and supports the hypothesis that bone metabolism and atherosclerotic plaque mineralization are related processes.

Association between coronary artery calcification using low-dose MDCT coronary angiography and bone mineral density in middle-aged men and women

Six hundred sixty-one participants who had at least one cardiac risk factor but were without known coronary heart disease underwent low-dose multidetector computed tomography coronary angiography (MDCT-CA) and dual-energy X-ray absorptiometry. The association between presence of subclinical coronary calcified plaque and low bone mineral density for the middle-aged individual was not significant after multivariate adjustment.

INTRODUCTION

Results of previous clinical studies assessing the relationship between osteoporosis and coronary calcification are inconsistent. This study aimed to evaluate the association between subclinical coronary calcification and osteoporosis in middle-aged men, premenopausal women, and postmenopausal women by using low-dose MDCT-CA and bone mineral density (BMD).

METHODS

This study enrolled 661 participants with at least one cardiac risk factor but without known coronary artery disease (CAD). All subjects underwent low-dose MDCT-CA and dual-energy X-ray absorptiometry on the same day.

RESULTS

The mean age was 52.2 years for men, 44.8 years for premenopausal women, and 59.1 years for postmenopausal women. The prevalence of calcified plaques between men with normal BMD and low BMD at lumbar spine were significantly different (P=0.042). The prevalence of mixed plaque and calcified plaque between pre- and postmenopausal women with normal BMD and low BMD at lumbar spine and femoral neck were not significantly different (P>0.05). Possible association between lumbar spine, femoral neck, and total proximal femur BMD and the presence of CAP was evaluated for men, premenopausal women, and postmenopausal women using multivariate logistic regression analysis: results were not significant (P>0.05).

CONCLUSION

Our study demonstrates that the association between the presence of subclinical coronary calcification and low BMD among middle-aged men and women was not significant after controlling for age and other risk factors for CAD and osteoporosis.

Ghrelin inhibits insulin resistance induced by glucotoxicity and lipotoxicity in cardiomyocyte

Ghrelin has wide effects on cardiovascular and endocrine system. The aims of this study are to investigate the direct damage effect of high glucose and high palmitate on cardiomyocyte, and to study the effect of ghrelin on insulin resistance induced by glucotoxicity/lipotoxicity in cardiomyocyte and the possible mechanism underlying the cardioprotective activities of ghrelin. The changes of [(3)H]-2-deoxy-d-glucose ((3)H-G) intake rates were detected by isotope tracer method and the gene expressions in insulin signal transduction pathway were detected by real-time PCR and Western blot assay. The (3)H-G intake rate significantly reduced in high glucose (25mmol/l) or high palmitate (0.5mmol/l) treated primary rat ventricular myocytes. After the treatment of ghrelin (10(-7)mol/l), the (3)H-G intake rate recovered to the normal level. In addition, the phosphorylation of AKT occurred in 10min and was the highest in 30min after the stimulation with ghrelin, which can be blocked by phosphoinositide 3-kinase (PI3K) inhibitor, LY2940002. Ghrelin also increased the mRNA levels of glucose transporter 4 (GLUT4), peroxisome proliferators (PPARr) and AMP activated protein kinase (AMPK) genes in insulin signal transduction pathway. These results indicate that the direct damage of high glucose and high palmitate on cardiomyocyte might be through insulin resistance (IR). Ghrelin can inhibit gluco/lipotoxicity induced insulin resistance by PI3K/AKT pathway. This may provide a clue for therapy for myocardial disease in diabetes mellitus.

Coronary arterial calcification and thoracic spine mineral density in early menopause

OBJECTIVES

Cardiovascular disease and osteoporosis increase in women after menopause. While aortic calcification is associated with bone loss in women, a similar relationship for coronary arterial calcification (CAC), a risk factor for coronary artery disease in women, is less clear. This study was designed to examine the relationship between CAC and volumetric bone mineral density (vBMD) in women (n=137) who were within a median of 18 months past their last menses at screening for the Kronos Early Estrogen Prevention Study (KEEPS).

METHODS

CAC was measured using 64-slice computed tomography; vBMD was measured from these images using the Spine Cancer Assessment program. Concentrations of osteocalcin, bone alkaline phosphatase, tartrate-resident acid phosphatase-5b and osteopontin as bone matrix protein in serum and plasma were evaluated by ELISA.

RESULTS

CAC scores ranged from 0 to 327.6 Agatston Units (AU); 113 women had a score of 0 AU, 20 had a CAC score between 0 and 50 AU, and four had a CAC score>50 AU. Although not statistically significant, there was a trend toward decreasing central density of thoracic T9 with increasing CAC. On average, levels of markers of bone turnover were within the normal range but did not correlate with age or with months past menopause.

CONCLUSIONS

Clinically significant CAC and spine vBMD are quantifiable from the same scans within the first 3 years of menopause. Additional work is needed to determine how these measurements change with increasing age or with estrogenic treatments.

Review of the Diabetes Heart Study (DHS) family of studies: a comprehensively examined sample for genetic and epidemiological studies of type 2 diabetes and its complications

The Diabetes Heart Study (DHS) is a genetic and epidemiological study of 1,443 European American and African American participants from 564 families with multiple cases of type 2 diabetes. Initially, participants were comprehensively examined for measures of subclinical cardiovascular disease (CVD) including computed tomography measurement of vascular calcified plaque, ultrasound imaging of carotid artery wall thickness, and electrocardiographic intervals. Subsequent studies have investigated the relationship between bone mineral density and vascular calcification, measures of adiposity, and biomarkers. Ongoing studies are carrying out an extensive evaluation of cerebrovascular disease using magnetic resonance imaging and cognitive assessment. A second, parallel study, the African American DHS, has expanded the sample of African Americans to investigate marked racial differences in subclinical CVD between European Americans and African Americans. Studies in development will evaluate the impact of social stress during the lifecourse on CVD risk, and the prevalence of gastroparesis in this diabetes enriched sample. In addition, the ongoing high mortality rate in DHS participants provides novel insights into the increased risks for type 2 diabetes affected individuals. A comprehensive genetic analysis of the sample is underway using the genome-wide association study (GWAS) approach. Data from this GWAS survey will complement prior family-based linkage data in the analysis of genetic contributors to the wide range of traits in the sample. To our knowledge the DHS family of studies has created the most comprehensively examined sample of individuals with type 2 diabetes yet available, and represents a unique resource for the study people with type 2 diabetes. The aim of this review is to provide a collective overview of the major results from the DHS family of studies, and relate them to the larger body of biomedical investigations of diabetes and its complications.

Vascular calcifications and renal osteodystrophy in chronic hemodialysis patients: what is the relationship between them?

INTRODUCTION

Vascular calcifications (VCs) and renal osteodystrophy (ROD) are frequently seen together and represent the major causes of morbidity and mortality in hemodialysis (HD) patients. Some studies suggest a pathogenic link between them, but there is no consensus as yet regarding this issue. The main objective of our study was to establish whether there is any relation between VCs and ROD in our HD patients. We evaluated the prevalence of VCs and ROD and the relationship between VCs and some clinical and biochemical characteristics of HD patients.

METHODS

We examined radiological signs of VCs and ROD on hands and pelvis bone radiographs in 81 chronic HD patients, and we calculated a VC score on this basis.

RESULTS

We found a significant relation between radiological signs of ROD and those of VC (P = 0.019). The patients with ROD had a higher mean VC score (P = 0.02). By linear regression, the VC score correlated directly with serum calcium (Ca), phosphorus (P), intact parathyroid hormone (iPTH) and CaxP product and inversely with serum albumin. The logistic regression model revealed that ROD, male gender and treatment with calcium salts were predictive of VCs development. There were no associations between VCs and age, HD vintage, diabetes, dialysate Ca concentration, vitamin D treatment, spKt/V, URR and C-reactive protein (CRP) levels.

CONCLUSION

There seems to be a pathogenetic link between bone and artery diseases in chronic HD patients. Both VCs and ROD have a high prevalence. ROD, male gender and treatment with calcium salts are risk factors for VCs.

Vitamin d, adiposity, and calcified atherosclerotic plaque in african-americans

CONTEXT

Inverse associations are reported between circulating 25-hydroxyvitamin D and visceral adiposity. The effects of vitamin D levels on atherosclerosis are unknown.

OBJECTIVE

The objective of this study was to test for relationships between vitamin D, adiposity, bone density, and atherosclerosis in African-Americans.

DESIGN

Circulating 25-hydroxyvitamin D, 1,25 dihydroxyvitamin D, intact PTH, C-reactive protein and computed tomography-derived calcified atherosclerotic plaque (CP), bone density, and fat volumes were measured.

SETTING

Examinations were performed at a single outpatient general clinical research center visit.

SUBJECTS

Three hundred forty African-Americans with type 2 diabetes were evaluated. Mean +/- SD age was 55.6 +/- 9.6 yr, diabetes duration 10.6 +/- 8.3 yr, glomerular filtration rate 1.6 +/- 0.5 ml/sec, body mass index 35.6 +/- 8.7 kg/m(2), and 25-hydroxyvitamin D concentration 50.4 +/- 30.5 nmol/liter.

MAIN OUTCOME MEASURE

Biomarkers were tested for association with pericardial, visceral, im, and sc adipose tissues; thoracic and lumbar vertebral bone density; and aorta, coronary, and carotid artery CP.

RESULTS

Adjusting for age, gender, body mass index, glycosylated hemoglobin, and glomerular filtration rate, 25-hydroxyvitamin D was negatively associated with visceral adiposity (P = 0.009) and positively associated with carotid artery CP and aorta CP (P = 0.013 and 0.014, respectively) but not with coronary artery CP or bone density.

CONCLUSIONS

We confirmed an inverse association between vitamin D and visceral adiposity in African-Americans with diabetes. In addition, positive associations exist between 25-hydroxyvitamin D and aorta and carotid artery CP in African-Americans. The effects of supplementing vitamin D to raise the serum 25-hydroxyvitamin D level on atherosclerosis in African-Americans are unknown. Prospective trials are needed to determine the cardiovascular effects of supplemental vitamin D in this ethnic group.

Bone morphogenetic protein 7 (BMP7) gene polymorphisms are associated with inverse relationships between vascular calcification and BMD: the Diabetes Heart Study

Inverse relationships have been observed between BMD and vascular calcification (VC), suggesting an underlying metabolic pathway linking these processes. Bone morphogenetic proteins (BMPs) are potential candidate genes that may mediate this relationship. Four single nucleotide polymorphisms (SNPs) in the BMP2 gene, 2 SNPs in BMP4, and 16 SNPs in BMP7 were tested for association with measures of VC using CT (coronary and carotid arteries, abdominal aorta), and BMD was measured using DXA (lumbar spine, hip, and distal radius) and quantitative CT (QCT; thoracic and lumbar spine) in 920 European Americans from 374 Diabetes Heart Study families: 762 with type 2 diabetes. Variance components quantitative trait locus association analysis was computed using SOLAR software, and a bivariate principal component analysis (PCA) assessed for genetic relationships between BMD and VC. Association was observed between several measures of BMD and BMP7 rs17404303 (thoracic spine QCT p = 0.03; lumbar spine QCT p = 0.02; hip DXA p = 0.06, dominant models). In addition, 6 of 16 BMP7 SNPs showed significant and opposing effects on the bivariate PCA for VC and BMD (two-sided exact test, p = 0.0143). Polymorphisms in BMP7 are associated with inverse relationships between bone mineralization and VC in the coronary, carotid, and abdominal aorta in a diabetes-enriched cohort of European Americans.

Comparing coronary artery calcium and thoracic aorta calcium for prediction of all-cause mortality and cardiovascular events on low-dose non-gated computed tomography in a high-risk population of heavy smokers

BACKGROUND

Coronary artery calcium (CAC) and thoracic aorta calcium (TAC) can be detected simultaneously on low-dose, non-gated computed tomography (CT) scans. CAC has been shown to predict cardiovascular (CVD) and coronary (CHD) events. A comparable association between TAC and CVD events has yet to be established, but TAC could be a more reproducible alternative to CAC in low-dose, non-gated CT. This study compared CAC and TAC as independent predictors of all-cause mortality and cardiovascular events in a population of heavy smokers using low-dose, non-gated CT.

METHODS

Within the NELSON study, a population-based lung cancer screening trial, the CT screen group consisted of 7557 heavy smokers aged 50-75 years. Using a case-cohort study design, CAC and TAC scores were calculated in a total of 958 asymptomatic subjects who were followed up for all-cause death, and CVD, CHD and non-cardiac events (stroke, aortic aneurysm, peripheral arterial occlusive disease). We used Cox proportional-hazard regression to compute hazard ratios (HRs) with adjustment for traditional cardiovascular risk factors.

RESULTS

A close association between the prevalence of TAC and increasing levels of CAC was established (p<0.001). Increasing CAC and TAC risk categories were associated with all-cause mortality (p for trend=0.01 and 0.001, respectively) and CVD events (p for trend <0.001 and 0.03, respectively). Compared with the lowest quartile (reference category), multivariate-adjusted HRs across categories of CAC were higher (all-cause mortality, HR: 9.13 for highest quartile; CVD events, HR: 4.46 for highest quartile) than of TAC scores (HR: 5.45 and HR: 2.25, respectively). However, TAC is associated with non-coronary events (HR: 4.69 for highest quartile, p for trend=0.01) and CAC was not (HR: 3.06 for highest quartile, p for trend=0.40).

CONCLUSIONS

CAC was found to be a stronger predictor than TAC of all-cause mortality and CVD events in a high-risk population of heavy smokers scored on low-dose, non-gated CT. TAC, however, is stronger associated with non-cardiac events than CAC and could prove to be a preferred marker for these events.