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1.  Diabetes Reduces Bone Marrow and Circulating Porcine Endothelial Progenitor Cells, an Effect Ameliorated by Atorvastatin and Independent of Cholesterol 
Bone marrow derived endothelial progenitor cells (EPCs) are early precursors of mature endothelial cells which replenish aging and damaged endothelial cells. The authors studied a diabetic swine model to determine if induction of DM adversely affects either bone marrow or circulating EPCs and whether a HMG-CoA reductase inhibitor (statin) improves development and recruitment of EPCs in the absence of cholesterol lowering. Streptozotocin was administered to Yorkshire pigs to induce DM. One month after induction, diabetic pigs were treated with atorvastatin (statin, n = 10), ezetimibe (n = 10) or untreated (n = 10) and evaluated for number of bone marrow and circulating EPCs and femoral artery endothelial function. There was no effect of either medication on cholesterol level. One month after induction of DM prior to administration of drugs, the number of bone marrow and circulating EPCs significantly decreased (P < 0.0001) compared to baseline. Three months after DM induction, the mean proportion of circulating EPCs significantly increased in the atorvastatin group, but not in the control or ezetimibe groups. The control group showed progressive reduction in percentage of flow mediated vasodilatation (no dilatation at 3 months) whereas the atorvastatin group and ezetimibe exhibited vasodilatation, 6% and 4% respectively. DM results in significant impairment of bone marrow and circulating EPCs as well as endothelial function. The effect is ameliorated, in part, by atorvastatin independent of its cholesterol lowering effect. These data suggest a model wherein accelerated atherosclerosis seen with DM may, in part, result from reduction in EPCs which may be ameliorated by treatment with a statin.
PMCID: PMC4221094  PMID: 19051240
diabetes mellitus; endothelium; endothelial progenitor cells; statin; inflammation; cytometry
2.  Evaluation of trans sodium crocetinate on safety and exercise performance in patients with peripheral artery disease and intermittent claudication 
Trans sodium crocetinate (TSC) is a synthetic carotenoid that improves the diffusion of oxygen in animal models of ischemia/hypoxia. This study evaluated multiple doses of TSC in patients with peripheral artery disease (PAD) and hypothesized that a preliminary dose–response relationship could be identified on peak walking time (PWT). Forty-eight patients with symptomatic PAD and an ankle–brachial index < 0.90 were included, while critical limb ischemia, recent revascularization, and exercise limited by symptoms other than claudication were exclusionary. Patients were randomized to placebo or eight dosing levels of TSC ranging from 0.25 mg/kg to 2.0 mg/kg given intravenously once daily for 5 days. Subjects were tested on a graded treadmill protocol to claudication-limited PWT with the change to Day 5 as primary. A cubic regression was fit to detect a pre-specified inverted U-shaped dose–response relationship (65% power). Patient-reported walking distance from the Walking Impairment Questionnaire was a secondary endpoint. Adverse events were not predominant on any drug dose relative to placebo. Changes in PWT demonstrated a cubic trend for dose (p = 0.07, r = 0.39, r2 = 0.15) with morphologic signals of benefit at doses above 1.00 mg/kg after both the first and fifth dosing days. Similar improvements occurred with the walking distance score at doses above 1.00 mg/ kg. In conclusion, TSC was safe and well tolerated at all doses. Notable signals of benefit were observed at higher doses for both PWT and patient-perceived walking distance. These results support a phase II study to define the optimal dose for longer-term therapy with TSC.
PMCID: PMC4182020  PMID: 22003000
claudication; dose–response relationship; drug; peripheral artery disease
3.  Personalized Cytomic Assessment of Vascular Health: Evaluation of the Vascular Health Profile in Diabetes Mellitus 
Cytometry. Part B, Clinical cytometry  2013;84(4):10.1002/cyto.b.21095.
An inexpensive and accurate blood test does not currently exist that can evaluate the cardiovascular health of a patient. This study evaluated a novel high dimensional flow cytometry approach in combination with cytometric fingerprinting (CF), to comprehensively enumerate differentially expressed subsets of pro-angiogenic circulating progenitor cells (CPCs), involved in the repair of vasculature, and microparticles (MPs), frequently involved in inflammation and thrombosis. CF enabled discovery of a unique pattern, involving both MPs and CPCs and generated a personalized signature of vascular health, the vascular health profile (VHP)
Levels of CPCs and MPs were measured with a broad panel of cell surface markers in a population with atherosclerosis and type 2 diabetes mellitus (DM) and age-similar Healthy controls (HC) using an unbiased computational approach, termed CF
Circulating hematopoietic stem and progenitor cell (CHSPCAng) levels were detected at significantly lower concentrations in DM (P< 0.001), whereas levels of seven phenotypically distinct MPs were present at significantly higher concentrations in DM patients and one MP subset was present at significantly lower concentration in DM patients. Collectively, the combination of CHSPCAng and MP levels was more informative than any one measure alone
This work provides the basis for a personalized cytomic vascular health profile that may be useful for a variety of applications including drug development, clinical risk assessment and companion diagnostics.
PMCID: PMC3812912  PMID: 23740755
circulating progenitor cell; microparticle; cytometric fingerprinting; type 2 diabetes mellitus; diagnostic testing
4.  Endothelial Function and Weight Loss: Comparison of Low-Carbohydrate and Low-Fat Diets 
Obesity (Silver Spring, Md.)  2013;21(3):504-509.
The effect of weight loss on obesity-associated endothelial dysfunction is not clear because of conflicting data, demonstrating both improvement and no change in endothelial function after weight loss in obese subjects.
A two-year prospective study (n=121) was conducted to examine: 1) the effect of obesity and weight loss (either a low-carbohydrate or and low-fat diet) on flow mediated vasodilatation (FMD), a measure of endothelial function.
Participants reduced body weight by 7.1±4.4%, 8.7±6.8% 7.1±7.8% and 4.1±7.7% at 3, 6, 12 and 24 months, respectively with no significant differences between the low-fat and low-carbohydrate groups. Endothelial function was inversely correlated with waist circumference, triglyceride level, and directly correlated with leptin in obese persons prior to weight loss. These weight losses did not confer any improvements in FMD. There were no differences between the low-fat and low-carbohydrate diets in FMD at any time point. At 6 months (r = 0.26, p = 0.04) and one year (r = 0.28, p = 0.03), there were positive correlations between change in FMD and change in leptin but not at two years.
There was no significant improvement in endothelial function after 7.1±7.8% weight loss at one year and 4.1±7.7% at two years, achieved by either a low carbohydrate or a low fat diet.
PMCID: PMC3630284  PMID: 23404949
Endothelium; Obesity; Leptin; Diet
5.  Peripheral artery disease, biomarkers, and darapladib 
American heart journal  2011;161(5):972-978.
Subjects with peripheral artery disease (PAD) are at increased risk of cardiovascular morbidity and mortality, perhaps in part, related to increased levels of inflammation, platelet activity, and lipids. We therefore sought to investigate the relationship between PAD and levels of inflammatory, platelet, and lipid biomarkers and the treatment effect of darapladib, a novel lipoprotein-associated phospholipase A2 (Lp-PLA2) inhibitor.
This is a post hoc analysis of the 959 patients with coronary disease or their risk equivalent receiving atorvastatin who were randomized to receive darapladib or placebo to examine the effects of an Lp-PLA2 inhibitor on the biomarkers of cardiovascular risk. We conducted an exploratory analysis evaluating the levels of biomarkers in subjects with PAD (n = 172) compared with those without PAD (n = 787).
After adjustment for age, sex, smoking, body mass index, and diabetes, subjects with PAD had greater levels of matrix metalloproteinase-9 (between group comparisons 22%, 95% confidence interval [10–31], P < .01), myeloperoxidase (12% [2–20], P = .01), interleukin-6 (13% [4–21], P = .01), adiponectin (17% [7–26], P < .01), intercellular adhesion molecule-1 (7% [2–11], P < .01), osteoprotegrin (6% [1–10], P = .02), CD40 ligand (15% [1–28], P = .04), high-sensitivity C-reactive protein (17% [1–31], P = .04), and triglycerides (11% [0.2–21], P = .05). No significant difference was detected for Lp-PLA2 activity, P-selectin, urinary 11-dehydrothroboxane B2, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol between subjects with and without PAD. Darapladib produced highly significant inhibition of Lp-PLA2 activity when compared with placebo at weeks 4 and 12 (P < .01) in patients with and without PAD.
Subjects with PAD had elevated levels of matrix metalloproteinase-9, myeloperoxidase, interleukin-6, adiponectin, intercellular adhesion molecule-1, osteoprotegrin, CD40 ligand, high-sensitivity C-reactive protein, and triglycerides compared with those without PAD. Darapladib, a novel Lp-PLA2 inhibitor, was equally effective in reducing Lp-PLA2 activity levels in subjects with and without PAD.
PMCID: PMC3750980  PMID: 21570531
6.  Relationship of Microparticles to Progenitor Cells as a Measure of Vascular Health in a Diabetic Population 
Quantitative measures are needed to identify diabetic patients at higher risk for CV events. Cell derived microparticles (MPs) are submicron membrane vesicles released from activated cells that are indicative of cell damage. Progenitor cells (PCs) including pro-angiogenic cells (PACs), often termed endothelial progenitor cells (EPCs), are mediators of reparative capacity. We examined whether the relationship of MPs to PCs/PACs could be used as an improved and clinically feasible index of vascular pathology.
Methods and Results
Plasma samples were collected from patients with early-stage (ES, Diagnosis<1yr) and long-term (LT, Diagnosis>5yrs,) type 2 diabetes and compared to age related healthy subjects (H). PC and MP subtypes were measured by a combination of flow cytometry and ELISA based methods. The ratio of pro-coagulant MPs/CD34+ PCs proved a valuable index to distinguish between subject groups (P=0.01). This index of compromised vascular function was highest in the LT group despite intensive statin therapy and was more informative than a range of soluble protein biomarkers.
This is the first report of a relationship between MPs and PCs in type 2 diabetes. This ratio may provide a quantitative and clinically feasible measurement of vascular dysfunction and cardiovascular risk in patients with diabetes.
PMCID: PMC3020670  PMID: 20544836
Endothelial; progenitor; vascular; diabetes; microparticles
7.  High Frequency Ultrasound for Evaluation of Intimal Thickness 
The measurement of carotid intima-medial thickness is a well validated measure of cardiovascular risk. Although atherosclerosis occurs in the intima, this arterial layer is not measured alone due to limitation in ultrasound resolution with standard frequency probes.
We evaluated the feasibility of using a 55-MHz ultrasound system with high resolution to measure intima thickness in several vascular territories compared to a “standard” frequency probe.
The intima and medial thickness was measured in the brachial, radial and tibial arteries in 10 healthy subjects and 5 subjects with peripheral arterial disease. The high frequency ultrasound probe showed superior resolution compared to the standard frequency probe allowing for measurement of intima separately from media.
The intima can be measured independently of media with a high degree of reproducibility using a high frequency probe. This technology may allow for early detection of cardiovascular risk and extend knowledge about the physiological changes in the early atherosclerotic development.
PMCID: PMC2762201  PMID: 19647399
8.  Carotid stenting for atherothrombosis 
Heart  2007;93(9):1147-1151.
PMCID: PMC1955039  PMID: 17699181
Inwardly-rectifying K+ (Kir) channels are responsible for maintaining membrane potentials in a variety of cell types including endothelial cells where they modulate endothelium-dependent vasorelaxation. The goal of this study is to determine the functional expression of Kir channels in porcine bone marrow-derived side population (BM-SP) cells that demonstrate phenotypes of endothelial progenitor cells (EPCs). We further asses the hypercholesterolemia sensitivity of Kir channels in BM-SP cells, which may play a key role in hypercholesterolemia-mediated regulation of EPCs.
To assess the effect of hypercholesterolemia on Kir channels in BM-SP, Kir currents were recorded in SP cells sorted from the bone marrow of healthy or hypercholesterolemic animals.
We found Kir channels constitute the major conductance in porcine bone marrow-derived side population (BM-SP) cells. These cells are defined by their efficiency of Hoechst dye efflux and have been reported to differentiate into multiple cell lineages including endothelium in vivo. We demonstrate here that porcine BM-SP cells differentiate to an endothelial lineage (CD31+, vWF+) supporting the hypothesis that these cells are endothelial progenitor cells. Also, BM-SP cells express Kir with biophysical properties recapitulating those in mature endothelial cells, but with a much higher current density. Flow cytometric (FACS) analysis indicated that the number of SP cells was unaffected by hypercholesterolemia. However, hypercholesterolemia significantly inhibited Kir channels in BM-SP cells.
We successfully demonstrate that BM side population cells represent an origin of endothelial progenitor cells. This study further shows, for the fist time, that the functional expression of Kir channels in bone marrow (BM) -derived SP. Moreover, we demonstrate that hypercholesterolemia condition significantly suppresses the Kir channels in BM-SP cells, suggesting that hypercholesterolemia-mediated regulation of Kir channels may be an important factor not only in dysfunction of mature endothelium but also in dysfunction of BM-SP cells.
PMCID: PMC2703014  PMID: 17482574
progenitor cells; endothelium; potassium channels; cholesterol; lipoproteins; flow; vasodilatation
10.  Effects of age and smoking on endothelial function assessed by quantitative cardiovascular magnetic resonance in the peripheral and central vasculature 
Both age and smoking promote endothelial dysfunction and impair vascular reactivity. Here, we tested this hypothesis by quantifying new cardiovascular magnetic resonance (CMR)-based biomarkers in smokers and nonsmokers.
Study population: young non-smokers (YNS: N = 45, mean age = 30.2 ± 0.7 years), young smokers (YS: N = 39 mean age 32.1 ± 0.7 years), older non-smokers (ONS: N = 45, mean age = 57.8 ± 0.6 years), and older smokers (OS: N = 40, mean age = 56.3 ± 0.6 years), all without overt cardiovascular disease. Vascular reactivity was evaluated following cuff-induced hyperemia via time-resolved blood flow velocity and oxygenation (SvO2) in the femoral artery and vein, respectively. SvO2 dynamics yielded washout time (time to minimum SvO2), resaturation rate (upslope) and maximum change from baseline (overshoot). Arterial parameters included pulse ratio (PR), hyperemic index (HI) and duration of hyperemia (TFF). Pulse-wave velocity (PWV) was assessed in aortic arch, thoracoabdominal aorta and iliofemoral arteries. Ultrasound-based carotid intimal-medial thickness (IMT) and brachial flow-mediated dilation were measured for comparison.
Age and smoking status were independent for all parameters. Smokers had reduced upslope (−28.4%, P < 0.001), increased washout time (+15.3%, P < 0.01), and reduced HI (−19.5%, P < 0.01). Among non-smokers, older subjects had lower upslope (−22.7%, P < 0.01) and overshoot (−29.4%, P < 0.01), elevated baseline pulse ratio (+14.9%, P < 0.01), central and peripheral PWV (all P < 0.05). Relative to YNS, YS had lower upslope (−23.6%, P < 0.01) and longer washout time (13.5%, P < 0.05). Relative to ONS, OS had lower upslope (−33.0%, P < 0.01). IMT was greater in ONS than in YNS (+45.6%, P < 0.001), and also in YS compared to YNS (+14.7%, P < 0.05).
Results suggest CMR biomarkers of endothelial function to be sensitive to age and smoking independent of each other.
PMCID: PMC4332734
Vascular reactivity; Oximetry; Velocimetry; Pulse wave velocity; Smoking; Aging; Cardiovascular magnetic resonance
12.  Therapeutic Angiogenesis in Critical Limb Ischemia 
Angiology  2012;64(6):466-480.
Critical limb ischemia (CLI) is a severe form of peripheral artery disease associated with high morbidity and mortality. The primary therapeutic goals in treating CLI are to reduce the risk of adverse cardiovascular events, relieve ischemic pain, heal ulcers, prevent major amputation, and improve quality of life (QoL) and survival. These goals may be achieved by medical therapy, endovascular intervention, open surgery, or amputation and require a multidisciplinary approach including pain management, wound care, risk factors reduction, and treatment of comorbidities. No-option patients are potential candidates for the novel angiogenic therapies. The application of genetic, molecular, and cellular-based modalities, the so-called therapeutic angiogenesis, in the treatment of arterial obstructive diseases has not shown consistent efficacy. This article summarizes the current status related to the management of patients with CLI and discusses the current findings of the emerging modalities for therapeutic angiogenesis.
PMCID: PMC3761355  PMID: 23129733
critical limb ischemia; medical therapy; surgical therapy; endovascular therapy; therapeutic angiogenesis; gene therapy; cell therapy
13.  Discordance between non-HDL-cholesterol and LDL-particle measurements: Results from the Multi-Ethnic Study of Atherosclerosis 
Atherosclerosis  2013;229(2):517-523.
Cardiovascular risk assessment incorporates measurement of atherogenic lipids such as non-HDL cholesterol (non-HDL-C). It remains uncertain under which circumstances atherogenic lipoprotein enumeration such as LDL particle number (LDL-P) differs from simultaneously acquired non-HDL-C.
Participants of the Multi-Ethnic Study of Atherosclerosis (MESA) were deemed LDL-P>non-HDL-C discordant if they exhibited higher LDL-P than expected for simultaneously measured non-HDL-C, given the observed distribution of both in MESA. Conversely, a lower LDL-P than would be suggested from non-HDL-C characterized LDL-P
Discordance was observed among 44% of subjects. LDL-P>non-HDL-C compared to LDL-P
Our results demonstrated that disagreement between LDL-P and non-HDL-C was common and significantly associated with several clinical characteristics. In the setting of discordance, LDL-P was more closely associated with CIMT and CAC than non-HDL-C, though observed differences were small.
PMCID: PMC4066302  PMID: 23591415
cholesterol; lipoproteins; risk assessment; LDL-particle number; apolipoprotein B
Atherosclerosis  2012;224(1):274-279.
The intraindividual variability of C-reactive protein (CRP) remains uncertain. Although guidelines suggest stability of serial CRP values comparable to that of cholesterol measures, several studies indicate greater fluctuations of CRP. We sought to compare the intraindividual variability of CRP with that of cholesterol measures using the Multi-Ethnic Study of Atherosclerosis (MESA).
CRP measurements were available in 760 MESA participants after exclusion of those with comorbidities or medications known to affect CRP or CRP≥10 mg/L. Serial values were available for 255 participants. The intraclass correlation coefficient (ICC) was quantified for CRP, total cholesterol (TC), and non-HDL-cholesterol (non-HDL-C) as the ratio of between-subject variance to the sum of between-subject and within-subject variance. Fluctuation between baseline and follow-up categories was calculated by cross-classifying participants according to baseline tertiles.
The multivariable-adjusted ICC of CRP was 0.62 (95% CI, 0.55–0.68), significantly lower than that of TC (0.75; 95% CI, 0.70–0.81; p=0.001 vs CRP) and non-HDL-C (0.76; 95% CI, 0.71–0.81; p=0.001 vs CRP). 51% of participants in the highest baseline CRP tertile had discordant values on follow-up, while 54% and 27% were discordant in the middle and lowest baseline CRP tertiles. Among participants with baseline CRP levels exceeding 3 mg/L, a clinical threshold for higher risk, 69% had subsequent measurements falling within a lower risk category.
In the MESA cohort, intraindividual variation of CRP was significantly greater than that for cholesterol measures. Our results suggest that further evaluation of CRP variability is needed in large prospective studies using shorter intervals between measurements.
PMCID: PMC4085141  PMID: 22846611
The New England journal of medicine  2013;369(24):2283-2293.
The clinical utility of genotype-guided (pharmacogenetically based) dosing of warfarin has been tested only in small clinical trials or observational studies, with equivocal results.
We randomly assigned 1015 patients to receive doses of warfarin during the first 5 days of therapy that were determined according to a dosing algorithm that included both clinical variables and genotype data or to one that included clinical variables only. All patients and clinicians were unaware of the dose of warfarin during the first 4 weeks of therapy. The primary outcome was the percentage of time that the international normalized ratio (INR) was in the therapeutic range from day 4 or 5 through day 28 of therapy.
At 4 weeks, the mean percentage of time in the therapeutic range was 45.2% in the genotype-guided group and 45.4% in the clinically guided group (adjusted mean difference, [genotype-guided group minus clinically guided group], −0.2; 95% confidence interval, −3.4 to 3.1; P=0.91). There also was no significant between-group difference among patients with a predicted dose difference between the two algorithms of 1 mg per day or more. There was, however, a significant interaction between dosing strategy and race (P=0.003). Among black patients, the mean percentage of time in the therapeutic range was less in the genotype-guided group than in the clinically guided group. The rates of the combined outcome of any INR of 4 or more, major bleeding, or thromboembolism did not differ significantly according to dosing strategy.
Genotype-guided dosing of warfarin did not improve anticoagulation control during the first 4 weeks of therapy. (Funded by the National Heart, Lung, and Blood Institute and others; COAG number, NCT00839657.)
PMCID: PMC3942158  PMID: 24251361
Psoriasis, especially when severe, is a risk factor for cardiometabolic disease beyond traditional risk factors. The mechanism of atherogenesis in psoriasis remains unknown. Cell membrane vesicles (ie, microparticles), released upon cell activation or apoptosis, have recently been associated with cardiometabolic disease and may play a pathogenic role. Microparticle levels, particularly from endothelial cells and platelets, are elevated in patients with cardiovascular disorders, metabolic syndrome, other inflammatory diseases, autoimmune conditions, and have been shown to be predictive of cardiovascular outcomes.
Methods and Results
Concentrations of microparticles with positive expression for any of 7 cell surface markers (Annexin V, CD3, CD31, CD41a, CD64, CD105, and CD144) were measured in blood samples from psoriasis patients (n=53) and control subjects without psoriasis (n=41). Platelet‐free plasma was separated from whole blood by one‐step centrifugation for microparticle analysis. Microparticles were fluorescently labeled and characterized by flow cytometry. Higher concentrations of CD105 (5.5/μL versus 2.5/μL, P<0.001), CD31 (31/μL versus 18/μL, P=0.002), CD41a (50/μL versus 22/μL, P<0.001), and CD64 (5.0/μL versus 4.1/μL, P=0.02) singly positive microparticles corresponding to endothelial cell‐, platelet‐, and monocyte/macrophage‐derived microparticles, respectively, were found in psoriasis patients compared with controls. These differences persisted after adjustment for traditional cardiometabolic risk factors including body mass index.
Increased microparticle concentrations, independent of cardiometabolic risk factors, in patients with psoriasis suggest that the presence of increased endothelial cell, platelet, and monocyte/macrophage activation with cell turnover may contribute to the heightened atherogenesis associated with psoriasis.
PMCID: PMC3959700  PMID: 24584739
atherosclerosis; inflammation; microparticles endothelium; platelets; psoriasis; risk factor
The Journal of pediatrics  2012;161(5):881-886.
To compare lipoprotein profiles of pre-diabetic to normoglycemic obese adolescents.
Study design
Cross-sectional study of 95 obese, pubertal adolescents (12–17 years), who underwent oral glucose tolerance test, lipid panel, and lipoprotein subclass particle analysis (NMR spectroscopy). Univariate and linear regression analyses compared pre-diabetic and normoglycemic groups.
22.1% (n=21) of adolescents had pre-diabetes. They were similar to normoglycemic adolescents (n=74) in age, race, BMI, standard lipids, total LDL-P, and total HDL-P. However, pre-diabetics had higher concentrations of small LDL-P (714.0±288.0 vs 537.7±266.5nmol/L, p=0.01) and smaller LDL-P size (20.73±0.41 vs 21.18±0.65nm, p=0.003), than normoglycemic youth. Pre-diabetics had higher small HDL-P (18.5±3.8 vs 16.6±3.9umol/L, p=0.046), lower large HDL-P (4.49±2.0 vs 6.32±2.6umol/L, p=0.004), and smaller HDL-P size (8.73±0.31 vs 9.01±0.39nm, p=0.003). After adjusting for demographics, Tanner stage, and BMI using multiple linear regression, all differences remained significant except for small HDL-P. After additional adjustment for HOMA-IR, only LDL-P size difference remained significant.
Obese pre-diabetic adolescents have a significantly more atherogenic lipoprotein profile compared with obese normoglycemic peers. Pre-diabetic adolescents may benefit from more aggressive interventions to decrease future cardiovascular risk.
PMCID: PMC3430826  PMID: 22622051
impaired fasting glucose; impaired glucose tolerance; type 2 diabetes mellitus; lipoprotein subclass particle analysis; cardiovascular risk; body mass index; pediatrics; lipids; abnormal glucose tolerance
To introduce a new, efficient method for vessel-wall imaging of carotid and peripheral arteries by means of a flow-sensitive 3D water-selective SSFP-echo pulse sequence.
Periodic applications of RF pulses will generate two transverse steady states, immediately after and before an RF pulse; the latter being referred to as the SSFP-echo. The SSFP-echo signal for water protons in blood is spoiled as a result of moving spins losing phase coherence in the presence of a gradient pulse along the flow direction. Bloch equation simulations were performed over a wide range of velocities to evaluate the flow sensitivity of the SSFP-echo signal. Vessel walls of carotid and femoral and popliteal arteries were imaged at 3 T. In two patients with peripheral artery disease the femoral arteries were imaged bilaterally to demonstrate method’s potential to visualize atherosclerotic plaques. The method was also evaluated as a means to measure femoral artery flow-mediated dilation (FMD) in response to cuff-induced ischemia in four subjects.
The SSFP-echo pulse sequence, which does not have a dedicated blood signal suppression preparation, achieved low blood signal permitting discrimination of the carotid and peripheral arterial walls with in-plane spatial resolution ranging from 0.5 to 0.69 mm and slice thickness of 2 to 3 mm, i.e. comparable to conventional 2D vessel-wall imaging techniques. The results of the simulations were in good agreement with analytical solution and observations for both vascular territories examined. Scan time ranged from 2.5 to 5 s per slice yielding a contrast-to-noise ratio between the vessel wall and lumen from 3.5 to 17. Mean femoral FMD in the four subjects was 9%, in good qualitative agreement with literature values.
Water-selective 3D SSFP-echo pulse sequence is a potential alternative to 2D vessel-wall imaging. The proposed method is fast, robust, applicable to a wide range of flow velocities, and straightforward to implement.
PMCID: PMC3819508  PMID: 24172037
American journal of nephrology  2012;36(4):342-347.
Despite the significant morbidity and mortality attributable to cardiovascular disease (CVD), risk stratification remains an important challenge in the chronic kidney disease(CKD) population. We examined the discriminative ability of non-invasive measures of atherosclerosis, including carotid intima-media thickness(cIMT), carotid plaque, coronary artery calcification(CAC) and ascending and descending thoracic aorta calcification(TCAC), and Framingham Risk Score (FRS) to predict self-reported prevalent CVD.
Methods and Results
Participants were enrolled in the cIMT ancillary study of the Chronic Renal Insufficiency Cohort(CRIC) Study and also had all of the above measures within an 18 month period. CVD was present in 21% of study participants. C-statistics were used to ascertain the discriminatory power of each measure of atherosclerosis. The study population (n=220) was 64% male; 51% black and 45% white. The proportion of individuals with estimated glomerular filtration rate ≥60, 45–59, 30–44, and <30ml/min/1.73m2 was 21%, 41%, 28%, and 11%, respectively. In multivariable analyses adjusting for demographic factors, we failed to find a difference between CAC, carotid plaque, and cIMT as predictors of self-reported prevalent CVD (c-statistic 0.70, 95% confidence interval [CI]: 0.62–0.78; c-statistic 0.68, 95% CI: 0.60–0.75, and c-statistic 0.64, CI: 0.56–0.72, respectively). CAC was statistically better than FRS. FRS was the weakest discriminator of self-reported prevalent CVD (c-statistic 0.58).
There was a significant burden of atherosclerosis among individuals with CKD, ascertained by several different imaging modalities. We were unable to find a difference in the ability of CAC, carotid plaque, and cIMT to predict self-reported prevalent CVD.
PMCID: PMC3538165  PMID: 23107930
carotid intima media thickness; coronary artery calcification; kidney; plaque
Personalized medicine refers to the application of an individual’s biological fingerprint – the comprehensive dataset of unique biological information – to optimize medical care. While the principle itself is straightforward, its implementation remains challenging. Advances in pharmacogenomics as well as functional assays of vascular biology now permit improved characterization of an individual’s response to medical therapy for vascular disease. This review describes novel strategies designed to permit tailoring of four major pharmacotherapeutic drug classes within vascular medicine: antiplatelet therapy, antihypertensive therapy, lipid-lowering therapy, and antithrombotic therapy. Translation to routine clinical practice awaits the results of ongoing randomized clinical trials comparing personalized approaches with standard of care management.
PMCID: PMC3761360  PMID: 22003003
anticoagulants; antihypertensive agents; aspirin; statins; vascular diseases; warfarin
Therapeutic angiogenesis utilizing genetic and cellular modalities in the treatment of arterial obstructive diseases continues to evolve. This is, in part, because the mechanism of vasculogenesis, angiogenesis, and arteriogenesis (the three processes by which the body responds to obstruction of large conduit arteries) is a complex process that is still under investigation. To date, the majority of human trials utilizing molecular, genetic, and cellular modalities for therapeutic angiogenesis in the treatment of peripheral artery disease (PAD) have not shown efficacy. Consequently, the current available knowledge is yet to be translated into novel therapeutic approaches for the treatment of PAD. The aim of this review is to discuss relevant scientific and clinical advances in therapeutic angiogenesis and their potential application in the treatment of ischemic diseases of the peripheral arteries. Additionally, this review article discusses past and recent developments, such as some unconventional approaches that have the potential to be applied as therapeutic targets. The article also includes advances in the delivery of genetic, cellular, and bioactive endothelial growth factors.
PMCID: PMC3760002  PMID: 22496126
cell therapy; gene therapy; neovascularization; peripheral artery disease; targeted delivery; therapeutic angiogenesis
Assessment of vascular disease has evolved from mere indirect and direct measurements of luminal stenosis to sophisticated imaging methods to depict millimeter structural changes of the vasculature. In the near future, the emergence of multimodal molecular imaging strategies may enable robust therapeutic and diagnostic (‘theragnostic’) approaches to vascular diseases that comprehensively consider structural, functional, biological and genomic characteristics of the disease in individualized risk assessment, early diagnosis and delivery of targeted interventions. This review presents a summary of recent preclinical and clinical developments in molecular imaging and theragnostic applications covering diverse atherosclerosis events such as endothelial activation, macrophage infammatory activity, plaque neovascularization and arterial thrombosis. The main focus is on molecular targets designed for imaging platforms commonly used in clinical medicine including magnetic resonance, computed tomography and positron emission tomography. A special emphasis is given to vascular ultrasound applications, considering the important role this imaging platform plays in the clinical and research practice of the vascular medicine specialty.
PMCID: PMC3750985  PMID: 21310769
atherosclerosis plaque; imaging based therapeutic delivery systems; molecular imaging; theragnostics; thrombosis; vascular ultrasound
The function of the peripheral microvascular may be interrogated by measuring perfusion, tissue oxygen concentration, or venous oxygen saturation (SvO2) recovery dynamics following induced ischemia. The purpose of this work is to develop and evaluate a magnetic resonance (MR) technique for simultaneous measurement of perfusion, SvO2, and skeletal muscle T2*.
Perfusion, Intravascular Venous Oxygen saturation, and T2* (PIVOT) is comprised of interleaved pulsed arterial spin labeling (PASL) and multi-echo gradient-recalled echo (GRE) sequences. During the PASL post-labeling delay, images are acquired with a multi-echo GRE to quantify SvO2 and T2* at a downstream slice location. Thus time-courses of perfusion, SvO2, and T2* are quantified simultaneously within a single scan. The new sequence was compared to separately measured PASL or multi-echo GRE data during reactive hyperemia in five young healthy subjects. To explore the impairment present in peripheral artery disease patients, five patients were evaluated with PIVOT.
Comparison of PIVOT-derived data to the standard techniques shows that there was no significant bias in any of the time-course-derived metrics. Preliminary data show that PAD patients exhibited alterations in perfusion, SvO2, and T2* time-courses compared to young healthy subjects.
Simultaneous quantification of perfusion, SvO2, and T2* is possible with PIVOT. Kinetics of perfusion, SvO2, and T2* during reactive hyperemia may help to provide insight into the function of the peripheral microvasculature in patients with PAD.
PMCID: PMC3765712  PMID: 23958293
Peripheral artery disease; Atherosclerosis; Microvascular function; Perfusion; Dynamic oximetry; T2*; BOLD; Reactive hyperemia; Skeletal muscle
Atherosclerosis  2010;213(2):586-591.
We sought to determine whether mean platelet volume (MPV) is associated with the prevalence of peripheral artery disease (PAD).
Platelets play a pivotal role in the pathogenesis of atherosclerosis and PAD. MPV, a measure of platelet size available in every blood count, is increasingly recognized as an important marker of platelet activity.
We analyzed data from 6354 participants aged 40 years and older from the 1999 to 2004 National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the US population. PAD was defined as an ankle brachial index ≤0.90 in either leg. Odds ratios and 95% confidence intervals were estimated by logistic regression.
The prevalence of PAD in the cohort was 5.7%. MPV was significantly associated with PAD prevalence (tertile 1 – 4.4%, tertile 2 – 6.1%, tertile 3 – 7.0%, P for trend = 0.003). After adjustment for age, sex, and race, the odds ratio of PAD comparing the highest tertile to the lowest tertile was 1.57 (95% confidence interval 1.15–2.13). After further adjustment for smoking status, hypertension, hypercholesterolemia, diabetes, glomerular filtration rate, body mass index, and platelet count the corresponding odds ratio was 1.58 (95% confidence interval 1.14–2.19). The addition of triglycerides, hemoglobin A1c, and C-reactive protein did not affect the results. The significant association between MPV and PAD was unchanged when MPV was used as a continuous variable.
Mean platelet volume is independently associated with PAD. These findings support the hypothesis that platelet size is an independent predictor of increased risk for PAD.
PMCID: PMC3739454  PMID: 20940069
Mean platelet volume; Platelets; Peripheral artery disease; Epidemiology
The American journal of cardiology  2012;110(1):136-141.
Patients with chronic kidney disease (CKD) have an increased risk of developing peripheral arterial disease (PAD). We examined the cross-sectional association between novel risk factors and prevalent PAD among patients with CKD. A total of 3,758 patients with an estimated glomerular filtration rate (eGFR) of 20-70 mL/min/1.73 m2 who participated in the chronic renal insufficiency cohort (CRIC) study were included in the current analysis. PAD was defined as an ankle-brachial index <0.9 or a history of arm or leg revascularization. After adjustment for age, sex, race, cigarette smoking, physical activity, history of hypertension and diabetes, pulse pressure, high-density lipoprotein cholesterol, eGFR, and CRIC clinical sites, several novel risk factors were significantly associated with PAD. For example, odds ratios (95% confidence intervals) for a one standard deviation higher level of risk factors were 1.18 (1.08–1.29) for log-transformed high sensitivity-C reactive protein, 1.18 (1.08–1.29) for white blood cell count, 1.15 (1.05–1.25) for fibrinogen, 1.13 (1.03–1.24) for uric acid, 1.14 (1.02–1.26) for hemoglobin A1c, 1.11 (1.00–1.23) for log-transformed homeostasis model assessment-insulin resistance, and 1.35 (1.18–1.55) for cystatin C. In conclusion, these data indicate that inflammation, prothrombotic state, oxidative stress, insulin resistance, and cystatin C were associated with an increased prevalence of PAD in patients with CKD. Further studies are warranted to examine the causal effect of these risk factors on PAD in CKD patients.
PMCID: PMC3586781  PMID: 22465315
peripheral arterial disease; novel risk factors; chronic kidney disease

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