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Todd J Anderson

Publications and source records attributed to Todd J Anderson.

At least 19 recordsLinked to original sources

Registry data evaluating the effectiveness of drug-eluting stents for the treatment of symptomatic in-stent restenosis.

BACKGROUND: In this new-era of drug-eluting stents (DES) the impact of symptomatic in-stent restenosis (ISR) is diminishing. However, world wide bare-metal stents remain widely used and therefore, it is imperative to establish a simple and effective form of treatment. The objective of this registry database was to evaluate the 'real-world' effectiveness of DES for the treatment of symptomatic bare-metal stent ISR. METHODS: All patients presenting with symptomatic ISR were evaluated between February 2003 and February 2005. Patients had 9-month angiographic follow-up with primary endpoint evaluation of binary restenosis (>50%). Secondary endpoints included in-segment late loss, target lesion revascularization (TLR) and the difference in late loss between sirolimus (n=23) and paciltaxel (n=36) eluting stents. RESULTS: Fifty eight patients with fifty nine ISR lesions were evaluated, 36% of patients had diabetes mellitus. All procedures were performed safely with no adverse peri-procedural events documented. At 9-month follow-up the median in-segment late loss was 0.24 mm (IQR 0.1, 0.53), with a binary restenosis rate of 17%. At long-term follow-up greater than 1 year, the incidence of TLR was 10%. No difference in the angiographic parameter of in-segment late loss was seen between the sirolimus and paclitaxel-eluting stents. CONCLUSIONS: In this cohort of patients with long-term angiographic and clinical follow-up, DES is an effective and safe treatment for symptomatic bare-metal stent ISR.

Antineoplastic Agents, Phytogenic↗

Effects of folinic acid on forearm blood flow in patients with end-stage renal disease.

BACKGROUND: Abnormalities of endothelial function are likely to contribute to the accelerated atherosclerotic risk in subjects with end-stage renal disease (ESRD). While folates can improve endothelial function, their role in ESRD has not been fully studied. The objective was to determine the acute and 12 week-effect of folinic acid on endothelium-dependent vasodilation in subjects with ESRD. METHODS: Forearm blood flow (FBF) was assessed by strain gauge plethysmography at baseline and after 12 weeks in 34 ESRD patients (57 +/- 14 years). Vascular function was assessed with acetylcholine (ACh), and sodium nitroprusside (SNP). Patients were randomized to receive folinic acid (50 mg i.v. once weekly) or a matching placebo. A subset of 25 subjects also received folinic acid (500 microg/min intra-arterially) or placebo to determine the acute effect on ACh and SNP mediated dilation at the time of the baseline vascular study. RESULTS: Folinic acid acutely improved the maximum change in ACh mediated FBF (10.0 +/- 2.4 to 12.8 +/- 2.2 ml/min/100 ml, P = 0.017), but did not change SNP responses. Chronic active therapy did not change ACh or SNP-mediated increases in FBF. Folinic acid resulted in a non-significant decrease in homocysteine (21 +/- 6 vs 28 +/- 18 micromol/l, P = 0.16) and diastolic blood pressure was significantly reduced (P = 0.05). CONCLUSIONS: The present study demonstrated that folinic acid acutely improved endothelium-dependent vasodilatation in patients with ESRD suggesting a direct vascular effect. Chronic treatment with folinic acid did not show benefit in endothelial function, but did lower diastolic blood pressure. Further work is required to determine the optimal regime to protect vascular health in subjects with ESRD.

Acetylcholine↗

Effect of percutaneous coronary intervention of nonacute total coronary artery occlusions on QT dispersion.

BACKGROUND: Myocardial ischemia is one of several potential causes of increased QT dispersion (QTd) in patients with nonacute total coronary artery occlusions (TCOs). We sought to assess the effect of percutaneous revascularization (PCI) of TCO on QTd and the relationship between QTd and long-term vessel patency. METHODS: Seventy patients enrolled in the TOSCA were analyzed. Patients were undergoing PCI of a TCO > 72 hours' duration. Two independent reviewers measured QTd from electrocardiograms done immediately before PCI (PRE), 12 to 18 hours after PCI (POST), and then at 6 months (6M). Follow-up angiography was performed at 6 months. RESULTS: Mean QTd decreased from PRE (77 +/- 29 milliseconds) to POST (66 +/- 26 milliseconds, P < .001) and 6M (65 +/- 25 milliseconds, P < .001). Patients with the same or longer QTd at 6 months compared with POST (POST < or = 6M) had significantly higher risk of failed target-vessel patency (odds ratio 10.3, 95% CI 1.24-84.8) than patients with QTd reduction at 6M versus POST values. CONCLUSION: Revascularization of TCO resulted in a decrease in QTd, which was sustained at 6M. This suggests that PCI to a TCO has a beneficial effect on stabilization of the underlying ischemic substrate. Furthermore, absence of QTd reduction at 6M versus POST was associated with increased risk of failed target-vessel patency.

Angioplasty, Balloon, Coronary↗

Sedentary lifestyle and antecedents of cardiovascular disease in young adults.

BACKGROUND: The aim of this study was to determine whether sedentary young individuals are characterized by reductions in determinants of vascular health and insulin sensitivity relative to their physically active, age-matched peers. METHODS: A total of 135 otherwise healthy young men (n = 68) and women (n = 67) <40 years of age (28 +/- 5 years) were studied in this investigation and stratified into three groups based on physical activity status: 1) sedentary (n = 73); 2) physically active (n = 24); and 3) endurance-trained (n = 38). Arterial compliance and flow-mediated dilation were determined by diastolic pulse contour wave analysis and echocardiographic imaging of the brachial artery respectively. Insulin sensitivity was estimated from the homeostasis model for insulin resistance and the 13C-glucose breath test. RESULTS: Both conduit (16.4 +/- 0.5 v 19.5 +/- 0.7 mL/mmHg x 10; P < .01) and resistant (8.5 +/- 0.3 v 10.7 +/- 0.5 mL/mmHg x 100; P < .01) artery compliance were significantly lower in sedentary subjects than in physically active or endurance-trained subjects, whereas flow-mediated dilation was not different between the groups. The HOMA(IR) was 2.5-fold higher in the sedentary group than in the endurance-trained group (P < .05). CONCLUSIONS: Sedentary individuals are characterized by reductions in both arterial compliance and insulin sensitivity relative to their endurance-trained peers, independent of changes in conventional risk factors for cardiovascular disease. These findings lend further support for the need for regular physical activity in the prevention of cardiovascular disease in individuals of all ages.

Adult↗

Arterial stiffness or endothelial dysfunction as a surrogate marker of vascular risk.

The understanding of the pathophysiology of atherosclerosis has advanced greatly in the past decade. Cardiovascular risk factors increase the likelihood of an adverse event by having a detrimental effect on the blood vessel wall. Abnormal interactions among cholesterol, inflammatory mediators, platelets and the vascular wall lead to atherogenesis and cardiac events. In an effort to better understand this process, develop surrogate end points for clinical trials and, ultimately, better risk stratify individuals, a variety of measures of arterial function have been studied. These include measures of endothelial health and arterial compliance. The current paper reviews the various techniques available for the study of vascular health. While not yet routinely used for clinical care, these measurements provide important insights into the pathophysiology and treatment of atherosclerosis.

Arteries↗

The effect of iron status on vascular health.

The effect of increased iron stores on the progression of atherosclerosis and endothelial health remains inconclusive. This study was designed to evaluate the relationship between hemochromatosis genotypes, serum ferritin levels and presymptomatic vascular abnormalities in a cohort of healthy subjects. Carotid intima-media thickness (CIMT) and brachial flow-mediated vasodilation (FMD) were assessed by high-resolution ultrasound in 907 male (47 +/- 10 years) participants enrolled in the Firefighters and their Endothelium (FATE) study. Analyses of the hemochromatosis C282Y, H63D and S65C alleles were simultaneously determined by a single nucleotide polymorphism (SNP) primer extension method. It was found that brachial FMD was not related to serum ferritin or hemochromatosis genotype status. The presence of a hemochromatosis-associated genotype (n = 18) or heterozygosity for the C282Y genotype (n = 98) was not associated with an increased mean CIMT. After adjustment for conventional risk factors, serum ferritin was also not associated with mean CIMT. In conclusion, neither ferritin nor a hemochromatosis genotype was related to brachial endothelial function or carotid atherosclerosis. The present study does not support the hypothesis that mild to moderately increased iron stores are associated with enhanced atherosclerosis risk.

Adult↗

A nonthiazolidinedione peroxisome proliferator-activated receptor gamma agonist reverses endothelial dysfunction in diabetic (db/db-/-) mice.

We have previously reported that endothelium-dependent relaxation to acetylcholine is impaired in small mesenteric arteries from spontaneously diabetic (db/db) mice. The objective of the present study was to examine the effects of treatment of the db/db and the insulin-resistant ob/ob mice with the PPARgamma agonist 2-(2-(4-phenoxy-2-propylphenoxy)ethyl)indole-5-acetic acid (COOH). In the db/db model, an 8-week treatment with COOH (30 mg/kg/day) reduced plasma glucose from 48.0 +/- 2.5 (untreated) to 12.6 +/- 1.1 mM. In contrast, plasma glucose was not elevated in untreated ob/ob mice. Relaxation of small mesenteric arteries mediated by acetylcholine was impaired in the untreated db/db diabetic mice (51.7 +/- 7.4% maximal relaxation, n = 6) but not in the ob/ob mice (70.8 +/- 8.6% maximal relaxation, n = 3). This impairment was reversed with COOH treatment (86.9 +/- 0.4% maximal relaxation, n = 5). Malondialdehyde was elevated in plasma from diabetic db/db mice (13.9 +/- 1.1 versus 12.0 +/- 0.7 micromol/ml); however, when normalized to total cholesterol, no significant differences in the ratio of lipid peroxidation in plasma were identified. Western blot analysis and quantitative polymerase chain reaction for eNOS was performed on the isolated mesenteric vessels and revealed no differences in the relative levels of eNOS expression in diabetic and control animals; in addition, treatment with COOH had no significant effect on eNOS levels in either group. In summary, endothelial dysfunction and hyperglycemia were completely normalized in COOH-treated db/db mice. In contrast, nonhyperglycemic ob/ob mice exhibited normal vasodilatory responses to acetylcholine and, consequently, COOH treatment had no effect on endothelial function.

Acetates↗

Relationship between carotid artery intima-media thickness and brachial artery flow-mediated dilation in middle-aged healthy men.

OBJECTIVES: We aimed to determine the relationship between carotid intima-media thickness (IMT) and brachial artery flow-mediated dilation (FMD) in healthy middle-age men. BACKGROUND: Carotid IMT and brachial artery FMD are frequently used as surrogate measures of subclinical atherosclerosis. Whereas carotid IMT identifies early structural abnormalities, brachial artery FMD, considered a bioassay of endothelial function, measures functional vascular integrity. The relationship between carotid IMT and brachial artery FMD has not been well studied. METHODS: We measured traditional risk factors, carotid IMT, and brachial artery FMD in 1,578 middle-aged men without known cardiovascular disease and analyzed the relationship between carotid IMT and brachial FMD. RESULTS: Carotid IMT correlated with age, systolic blood pressure, body mass index, fasting glucose, total and low-density lipoprotein (LDL) cholesterol, and with the overall Framingham risk score (p < 0.001 for all), whereas impaired brachial artery FMD correlated with systolic and diastolic blood pressure (p < 0.01). No relationship was observed between carotid IMT and brachial artery FMD for the entire cohort (r = -0.006, p = 0.82) and in subgroups defined by traditional risk factors or by quintiles of carotid IMT and brachial FMD. CONCLUSIONS: In middle-aged healthy men, there is no significant correlation between carotid IMT and brachial artery FMD. This finding suggests that these are unique, independent surrogates that measure different aspects and stages of early atherosclerosis. Further studies are needed to define their role in clinical research and in cardiovascular risk assessment.

Adult↗

Relation of Basal coronary nitric oxide activity to the burden of atherosclerosis.

Coronary disease or its risk factors has been reported to attenuate basal nitric oxide (NO) activity. Intravascular ultrasound was used in the present study to better understand this relation. Basal and stimulated NO activities were assessed in 53 stable subjects. Coronary diameter and velocity (0.014-inch Doppler wire) were measured at baseline and after intracoronary infusion of the NO synthase inhibitor N(G)-monomethyl-l-arginine, acetylcholine (10(-6) M), nitroglycerin (200 microg), and adenosine (24 microg). Intimal thickening was quantified with intravascular ultrasound. N(G)-monomethyl-l-arginine resulted in significant decreases in coronary blood flow (-14 +/- 48%), proximal coronary diameter (-10 +/- 18%), and distal coronary diameter (-10 +/- 9%, all p values <0.0001). Basal NO activity was unrelated to the presence of coronary disease as assessed by angiography and the burden of atherosclerosis as assessed by intravascular ultrasound. Conversely, stimulated NO activity correlated inversely with burden of coronary atherosclerosis (p <0.05). Basal NO activity is relatively preserved in patients who have moderate coronary disease and is not related to the degree of atherosclerosis as assessed by intravascular ultrasound. This is in contradistinction to the impairment of stimulated NO activity in the coronary circulation that characterizes atherosclerosis.

Adenosine↗

The relationship between soluble CD40 ligand levels and Framingham coronary heart disease risk score in healthy volunteers.

Elevated soluble CD40 ligand (sCD40L) levels are associated with an increased risk of cardiovascular events in patients with acute coronary syndromes and in middle-aged healthy women. However, the relationship between sCD40L and global risk assessment remains unclear. The present study was designed to examine the relationship between sCD40L and Framingham Coronary Heart Disease Risk Scores (FCRS) in healthy middle-aged men. The study population consisted of 400 active and retired male firefighters, with no previous history of cardiovascular disease, as part of the Firefighters and Their Endothelium (FATE) study. FCRS correlated poorly with sCD40L levels (p=0.14). Soluble CD40L concentrations correlated only with total (r=0.105; p=0.035) and LDL cholesterol (r=0.104; p=0.039), and CRP levels (r=0.11; p=0.03). Compared with participants with sCD40L levels <4.36 ng/mL (75th percentile), participants with sCD40L levels >4.36 ng/mL had higher total (p=0.016) and LDL cholesterol (p=0.018), CRP levels (p=0.034) and FCRS (p=0.012). Multivariate analysis revealed that CRP level was the only parameter that independently correlated with the sCD40L levels (p=0.032). This is the first study to evaluate the relationship between sCD40L levels and Framingham global risk assessment in a large cohort of otherwise healthy individuals. We demonstrate that sCD40L levels poorly correlate with both the individual components and the calculated FCRS. Long-term follow-up of the FATE study will shed light on whether the predictive value of sCD40L is independent of Framingham based global risk assessment.

Adult↗

Endothelial dysfunction in Type 2 diabetes correlates with deregulated expression of the tail-anchored membrane protein SLMAP.

The Type 2 diabetic db/db mouse experiences vascular dysfunction typified by changes in the contraction and relaxation profiles of small mesenteric arteries (SMAs). Contractions of SMAs from the db/db mouse to the alpha1-adrenoceptor agonist phenylephrine (PE) were significantly enhanced, and acetylcholine (ACh)-induced relaxations were significantly depressed. Drug treatment of db/db mice with a nonthiazolidinedione peroxisome prolifetor-activated receptor-gamma agonist and insulin sensitizing agent 2-[2-(4-phenoxy-2-propylphenoxy)ethyl]indole-5-acetic acid (COOH) completely prevented the changes in endothelium-dependent relaxation, but, with the discontinuation of therapy, endothelial dysfunction returned. Dysfunctional SMAs were found to specifically upregulate the expression of a 35-kDa isoform of sarcolemmal membrane-associated protein (SLMAP), which is a component of the excitation-contraction coupling apparatus and implicated in the regulation of membrane function in muscle cells. Real-time PCR revealed high SLMAP mRNA levels in the db/db microvasculature, which were markedly downregulated during COOH treatment but elevated again when drug therapy was discontinued. These data reveal that the microvasculature in db/db mice undergoes significant changes in vascular function with the endothelial component of vascular dysfunction specifically correlating with the overexpression of SLMAP. Thus changes in SLMAP expression may be an important indicator for microvascular disease associated with Type 2 diabetes.

Acetates↗

The vascular endothelium in diabetes: a practical target for drug treatment?

Vascular disease remains a major cause of morbidity and mortality in diabetes mellitus, in spite of recent improvements in outcome, some of which may be modulated by improved endothelial function. Therapeutic strategies aimed directly at preventing, or minimising the extent of, these sequelae are required as an adjunct to treatments directed at normalising the metabolic milieu. The microvasculature, and the endothelium in particular, are early contributors to vascular dysfunction, thus raising the question as to how best to specifically target the endothelium. However, the expansive nature of the microvasculature, the varying demands that tissues have in terms of blood flow, and the heterogeneity that exists amongst cell types in different sites raises potential problems as to the practicality of such an approach. Further-more, temporal and genetic factors in the genesis of diabetic microvascular dysfunction may impact on therapeutic strategies. It is suggested that a systematic approach is required to understand the heterogeneity of the microvasculature, with particular emphasis on relating differences in gene and protein expression with functional properties. Such an approach may then provide the necessary information to allow exploitation of endothelial cell heterogeneity for unique targeted interventions, as well as providing the necessary rationale for pharmacological interventions (both prophylactic and corrective) aimed at the endothelium as a whole.

Animals↗

Effects of the acyl coenzyme A:cholesterol acyltransferase inhibitor avasimibe on human atherosclerotic lesions.

BACKGROUND: Inhibition of the acyl coenzyme A:cholesterol acyltransferase (ACAT) enzyme may prevent excess accumulation of cholesteryl esters in macrophages. The ACAT inhibitor avasimibe was shown to reduce experimental atherosclerosis. This study was designed to investigate the effects of avasimibe on human coronary atherosclerosis. METHODS AND RESULTS: This randomized, double-blind, placebo-controlled trial assessed the effects of avasimibe at dosages of 50, 250, and 750 mg QD on the progression of coronary atherosclerosis as assessed by intravascular ultrasound (IVUS). All patients received background lipid-lowering therapy if necessary to reach a target baseline LDL level <125 mg/dL (3.2 mmol/L). IVUS and coronary angiography were performed at baseline and repeated after up to 24 months of treatment. Approximately equal percentages of patients across groups received concurrent statin therapy (87% to 89%). The mean total plaque volume at baseline was approximately 200 mm3, and the least squares mean change at end of treatment was 0.7 mm3 for placebo and 7.7, 4.1, and 4.8 mm3 for the avasimibe 50, 250, and 750 mg groups, respectively (adjusted P=0.17 [unadjusted P=0.057], 0.37, and 0.37, respectively). Percent atheroma volume increased by 0.4% with placebo and by 0.7%, 0.8%, and 1.0% in the respective avasimibe groups (P=NS). LDL cholesterol increased during the study by 1.7% with placebo but by 7.8%, 9.1%, and 10.9% in the respective avasimibe groups (P<0.05 in all groups). CONCLUSIONS: Avasimibe did not favorably alter coronary atherosclerosis as assessed by IVUS. This ACAT inhibitor also caused a mild increase in LDL cholesterol.

Acetamides↗

Coronary flow velocity reserve does not correlate with TIMI frame count in patients undergoing non-emergency percutaneous coronary intervention.

OBJECTIVES: The purpose of this research was to compare the Thrombolysis In Myocardial Infarction (TIMI) frame count (CTFC) with coronary flow velocity reserve (CFVR) in patients undergoing percutaneous coronary intervention (PCI). BACKGROUND: The relationship between CTFC and CFVR has not been adequately assessed in patients with coronary artery disease. METHODS: We studied 62 patients who underwent successful non-emergent PCI. All patients had Doppler evaluation of CFVR, CTFC, and quantitative coronary angiography. In an additional 17 patients, a frame count reserve was calculated as baseline CTFC/CTFC at peak hyperemia, induced by intracoronary adenosine after PCI. RESULTS: The CTFC decreased from 27 +/- 13 to 18 +/- 8, and CFVR increased from 1.5 +/- 0.4 to 2.6 +/- 0.7 (both p < 0.0001). The pre-PCI CTFC and the CFVR were closely related to minimal lumen diameter (p < 0.0001). After PCI, there was no correlation between CFVR and CTFC. In addition, no relationship was observed between CFVR and the frame count reserve. CONCLUSIONS: There was no significant correlation between CFVR and CTFC in patients undergoing coronary intervention. The relative utility of these measures in predicting outcomes in this setting requires further evaluation, but CTFC (or frame count reserve) does not appear to be an adequate surrogate measure of Doppler-derived CFVR.

Adenosine↗

Cross-sectional evaluation of brachial artery flow-mediated vasodilation and C-reactive protein in healthy individuals.

AIMS: The present study was designed to (a) examine the interrelationship between endothelial function and CRP in healthy individuals and (b) evaluate the relationship of each biomarker towards global Framingham risk scores. METHODS AND RESULTS: Brachial artery flow-mediated vasodilatation (FMD), CRP, and traditional cardiovascular risk factors were measured in the Firefighters and Their Endothelium (FATE) study, which recruited 1154 male participants (mean age 47.4+/-9.8 years) with no known history of cardiovascular disease. No relationship was observed between FMD and CRP (p = 0.96). FMD and the Framingham risk score tended to correlate but not significantly (p = 0.07). A lower FMD was related to a higher systolic and diastolic blood pressure (p < 0.001 and p = 0.002, respectively) in the univariate analysis, and higher systolic blood pressure (p = 0.001) in the multivariate analysis. Elevated CRP levels independently correlated most closely with overall Framingham risk score (r = 0.36, p < 0.001) and a weaker although statistically significant relationship was seen with individual traditional cardiovascular risk factors (p < 0.005). CONCLUSIONS: The current study provided evidence that brachial artery FMD had no relationship to CRP in a large cohort of healthy subjects. These observations suggest that the predictive value of CRP may be largely independent of abnormalities in endothelial function. The additive prognostic value of endothelial vasodilator testing remains to be established.

Blood Flow Velocity↗

The endothelium in health and disease: a discussion of the contribution of non-nitric oxide endothelium-derived vasoactive mediators to vascular homeostasis in normal vessels and in type II diabetes.

Endothelial dysfunction is considered as a major risk factor of cardiovascular complications of type I and types II diabetes. Impaired endothelium-dependent vasodilatation can be directly linked to a decreased synthesis of the endothelium-derived nitric oxide (NO) and/or an increase in the production of reactive oxygen species such as superoxide. Administration of tetrahydrobiopterin, an important co-factor for the enzyme nitric oxide synthase (NOS), has been demonstrated to enhance NO production in prehypertensive rats, restore endothelium-dependent vasodilatation in coronary arteries following reperfusion injury, aortae from streptozotocin-induced diabetic rats and in patients with hypercholesterolemia. Tetrahydrobiopterin supplementation has been shown to improve endothelium-dependent relaxation in normal individuals, patients with type II diabetes and in smokers. These findings from different animal models as well as in clinical trials lead to the hypothesis that tetrahydrobiopterin, or a precursor thereof, could be a new and an effective therapeutic approach for the improvement of endothelium function in pathophysiological conditions. In addition to NO, the endothelium also produces a variety of other vasoactive factors and a key question is: Is there also a link to changes in the synthesis/action of these other endothelium-derived factors to the cardiovascular complications associated with diabetes? Endothelium-derived hyperpolarizing factor, or EDHF, is thought to be an extremely important vasodilator substance notably in the resistance vasculature. Unfortunately, the nature and, indeed, the very existence of EDHF remains obscure. Potentially there are multiple EDHFs demonstrating vessel selectivity in their actions. However, until now, identity and properties of EDHF that determine the therapeutic potential of manipulating EDHF remains unknown. Here we briefly review the current status of EDHF and the link between EDHF and endothelial dysfunction associated with diabetes.

Animals↗

Endothelial function: ready for prime time?

The strategic location of the endothelium allows it to detect changes in hemodynamic forces and blood-borne signals, and to respond by releasing a number of autocrine and paracrine substances. The balanced release of these bioactive factors facilitates vascular homeostasis. If disrupted, endothelial cell dysfunction ensues. This predisposes the vessel wall to vasoconstriction, leukocyte adherence, platelet activation, thrombosis, vascular inflammation and atherosclerosis. Given the central role of the endothelium in the development and progression of atherosclerosis, endothelial function testing may serve as a useful biomarker of atherosclerotic disease. The present review highlights the current modalities used in assessing endothelial function, explores how endothelial function may serve as a biomarker for atherosclerosis, comments on the prognostic relevance of endothelial function and describes its use in the clinical setting.

Biomarkers↗