Ward Casscells

Influenza infection exerts prominent inflammatory and thrombotic effects on the atherosclerotic plaques of apolipoprotein E-deficient mice

Background—The role of infection in the development and complications of atherosclerosis has been the focus of much attention. We reported previously that influenza vaccination was associated with reduced risk of recurrent myocardial infarction. Here, we report the effect of influenza A virus on the apolipoprotein E–deficient (apoE−/−) mouse, an animal model of atherosclerosis. Methods and Results—Twenty-four apoE−/− mice >24 months old were injected with 1 LD50 (lethal dose 50) of influenza A virus. Ten wild-type C57BL/6 infected mice and 11 noninfected age-matched apoE−/− mice served as controls. Multiple aortic sections were studied histologically 3, 5, and 10 days later. The infected mice showed markedly increased intimal cellularity compared with the noninfected apoE−/− mice. No aortic abnormalities were seen in infected wild-type mice. Ten infected apoE−/− mice had a significant subendothelial infiltrate composed of a heterogeneous group of cells that stained positively for smooth muscle cell actin, F4/80 (macrophages), and CD3 (T lymphocytes). One case of subocclusive platelet and fibrin-rich thrombus was seen. Conclusions—This study shows that influenza infection promotes inflammation, smooth muscle cell proliferation, and fibrin deposition in atherosclerotic plaques.

pH Heterogeneity of human and rabbit atherosclerotic plaques; a new insight into detection of vulnerable plaque

BACKGROUND Atherosclerotic plaques are heterogeneous with respect to inflammation, calcification, vascularity, oxygen, and temperature. We hypothesized that they also vary in pH and measured pH in living human carotid endarterectomized atherosclerotic plaques (CEA), Watanabe heritable hyperlipidemic (WHHL) rabbit aortas and human umbilical arteries (HUA). METHODS AND RESULTS We measured pH of CEA of 48 patients, nine WHHL rabbit aortas and 11 HUA specimens (as controls) using a glass type microelectrode mounted on a micromanipulator in a 37 degrees C incubator. We also used single emission and also dual emission fluorescence ratio imaging microscopy employing pH-sensitive probes to confirm pH heterogeneity. Mean pH measured at 415 points of CEA was 7.55+/-0.32; at 275 points of WHHL rabbit aortas it was 7.40+/-0.43; and in 233 points of HUA it was 7.24+/-0.1. In CEA, pH of yellow (lipid-rich) areas was significantly lower than pH in calcified areas (7.15+/-0.01 vs. 7.73+/-0.01, P<0.0001). The coefficients of variation (heterogeneity) of pH in CEA, WHHL rabbit aortas, and HUA were 0.038+/-0.010, 0.039+/-0.007, and 0.009+/-0.003, respectively (P=0.0001). Fluorescence microscopic imaging confirmed pH heterogeneity in both humans and rabbits but not in HUA. In a variance components analysis 82% of the heterogeneity was due to the within-plaque variation and 2% was attributable to between-plaque variation. CONCLUSIONS Our findings support the hypothesis of pH heterogeneity in plaques, and suggest a possible role for detecting low pH in the detection of plaque vulnerability. The source of pH heterogeneity particularly acidic pH, its impact on the stability of plaques and its potential clinical utility in locating vulnerable plaques remain to be evaluated.

Myocyte Enhancer Binding Factor-2 Expression and Activity in Vascular Smooth Muscle Cells: Association With the Activated Phenotype

Proliferation and phenotypic modulation of smooth muscle cells (SMCs) are major components of the vessels response to injury in experimental models of restenosis. Some of the growth factors involved in restenosis have been identified, but to date little is known about the transcription factors that ultimately regulate this process. We examined the expression of the four members of the myocyte enhancer binding factor-2 (MEF2) family of transcription factors in cultured rat aortic SMCs (RASMCs) and a rat model of restenosis because of their known importance in regulating the differentiated phenotype of skeletal and cardiac muscle. In skeletal and cardiac muscle, the MEF2s are believed to be important for activating the expression of contractile protein and other muscle-specific genes. Therefore, we anticipated that the MEF2s would be expressed at high levels in medial SMCs that are producing contractile proteins and that they would be downregulated along with the contractile protein genes in neointimal SMCs. On the contrary, we observe that MEF2A, MEF2B, and MEF2D mRNAs are upregulated in the neointima, with the highest levels in the layer of cells nearest to the lumen, whereas MEF2C mRNA levels do not appreciably increase. Moreover, few cells in the media are making MEF2 proteins detectable by immunohistochemistry, whereas large numbers of neointimal cells are positive for all four MEF2s. These data suggest that the MEF2s are involved in the activated smooth muscle phenotype and not in the maintenance of contractile protein gene expression.

Endogenous and Exogenous Nitric Oxide Protect Against Intracoronary Thrombosis and Reocclusion After Thrombolysis

BACKGROUND Nitric oxide (NO), an endothelium-derived relaxing factor, plays an important role in regulating platelet activation. We evaluated the effect of NO in a canine model of intracoronary thrombosis, thrombolysis, and reocclusion. METHODS AND RESULTS Before thrombosis was induced, 34 anesthetized dogs were treated with a continuous intracoronary infusion of saline (n = 8); NG-nitro-L-arginine (L-NNA, n = 8), an inhibitor of NO synthetase; L-arginine (n = 7), the precursor for NO; or sodium nitroprusside (SNP, n = 11), an NO donor. Ten minutes after the infusion was begun, an electric current of 150 microA was applied to the endothelium of coronary arteries to induce thrombosis. Occlusive thrombi developed in all dogs in the saline group (38 +/- 4 minutes) and the L-NNA group (30 +/- 6 minutes), in 6 of 7 dogs in the L-arginine group (81 +/- 18 minutes), and in 6 of 11 dogs in the SNP group (102 +/- 21 minutes) (P < .01). The time to thrombus was prolonged by L-arginine (P < .05) and SNP (P < .01). After 3 hours of thrombus formation in coronary arteries, tissue plasminogen activator and heparin were administered intravenously. Thrombi were lysed in 4 (of 8) dogs in the saline group (71 +/- 8 minutes), in 4 (of 8) dogs in the L-NNA group (72 +/- 8 minutes), in 4 (of 6) dogs in the L-arginine group (50 +/- 14 minutes), and in 4 (of 6) dogs in the SNP group (49 +/- 11 minutes) (P > .05). After thrombolysis, coronary artery reocclusion developed in all reperfused dogs in the saline group (30 +/- 8 minutes) and in the L-NNA group (48 +/- 12 minutes), in 3 (of 4) reperfused dogs in the L-arginine group (123 +/- 26 minutes), and in 3 (of 4) reperfused dogs in the SNP group (128 +/- 19 minutes) (P < .01). The ex vivo platelet aggregation induced by collagen was inhibited after in vivo treatment with L-arginine or SNP. CONCLUSIONS Increasing NO production or giving an NO donor may inhibit platelet aggregation and delay intracoronary thrombus formation and reocclusion after thrombolysis.

Tissue pH determination for the detection of metabolically active, inflamed vulnerable plaques using near-infrared spectroscopy: an in-vitro feasibility study

Detection of vulnerable plaques as the underlying cause of myocardial infarction is at the center of attention in cardiology. We have previously shown that infiltration of inflammatory cells in atherosclerotic plaques renders these plaques relatively hot and acidic, with substantial plaque temperature and pH variation. The objective of this investigation was to determine whether near-infrared diffuse reflectance spectroscopy (NIRS) could be used to non-destructively measure the tissue pH in atherosclerotic plaques. NIRS and tissue pH electrode measurements were taken on freshly excised carotid plaques maintained under physiological conditions. The coefficient of determination between NIRS and the pH microelectrode measurement was 0.75 using 17 different areas. The estimated accuracy of the NIRS measurement was 0.09 pH units. These results demonstrate the feasibility of using NIRS tissue pH in freshly excised atherosclerotic plaques in light of marked pH heterogeneity and warrants future in-vivo investigations on pH measurement of atherosclerotic plaques.

Bush Administration and the Democratic Senate Wrestle With Health Care

As his administration approaches its 6-month mark, President Bush has filled his cabinet, survived a showdown with China over a spy plane, and seen his

Bush Administration and the New Senate Converge on Health Care

1.35 trillion tax cut passed by the House and Senate—just as the Republicans lost control of the Senate with the change of party by Senator James Jeffords of Vermont, who became an independent. Yet Bush and the new Senate Majority leader Tom Daschle (D-SD) agree that a patients’ bill of rights is a top priority. For Secretary of the Department of Health and Human Services (HHS), President Bush selected Wisconsin Governor Tommy Thompson, a conservative best known for successfully pruning the welfare roles in Wisconsin. Less well known is that, to do so, he offered innovative solutions for day care and health care for the former welfare recipients entering the work place. Thompson was known as a supporter of scientific research and a critic of governmental bureaucracy, particularly at HHS and its Health Care Financing Administration, now renamed the Centers for Medicare and Medicaid Services (CMS). In filling out his staff and agency directors, Thompson and the White House, advised by Senator Bill Frist, MD (R-TN), have considered hundreds of nominees (Disclosure: the author served on the Bush-Cheney Transition Committee). To run CMS, they tapped Thomas Scully, who was formerly in charge of Medicare and Medicaid budget oversight at the Office of Management and Budget under former President Bush, after which he served as Executive Director of the Federation of American Health Care Systems, the trade association for the Hospital Corporation of America, Tenet, and Humana. Scully is considered moderately conservative; several more passionate right-to-life candidates were given positions unrelated to health care. Scully is focusing now on encouraging health maintenance organizations (HMOs) to offer plans to Medicare beneficiaries and on making CMS more efficient …

SAI-16: pH and lactate imaging of atherosclerotic plaques: introducing a 3-french, 360-degree side-viewing, near-infrared spectroscopic catheter to monitor metabolic activity of atherosclerotic plaque

As his administration approaches its 6-month mark, President Bush has filled his cabinet, survived a showdown with China over a spy plane, and seen his

Near-infrared spectroscopic characterization of human advanced atherosclerotic plaques.

1.35 trillion tax cut passed by the House and Senate just as the Republicans lost control of the Senate with the change of party by Senator James Jeffords of Vermont, who became an independent. Yet both Bush and the new Senate Majority leader Tom Daschle (D-SD) agree that they ought to be able to agree on a patients’ bill of rights, and both have said it is a top priority. To date, the Bush Administration has moved cautiously on health policy. For Secretary of the Department of Health and Human Services (HHS), President Bush selected Wisconsin Governor Tommy Thompson, a conservative best known for successfully pruning the welfare roles in Wisconsin. Less well known is that, to do so, he offered innovative solutions for day care and health care for the former welfare recipients entering the work place. Thompson was known as a supporter of scientific research and a critic of governmental bureaucracy, particularly at HHS and its Health Care Financing Administration (HCFA). In filling out his staff and agency directors, Thompson and the White House, advised by Senator Bill Frist, MD (R-TN), have considered hundreds of nominees (Disclosure: the author served on the Bush-Cheney Transition Committee). To run HCFA, they tapped Thomas Scully, who was formerly in charge of Medicare and Medicaid budget oversight at the Office of Management and Budget under former President Bush, after which he served as Executive Director of the Federation of American Health Care Systems, the trade association for the Hospital Corporation of America, Tenet, and Humana. Scully is considered moderately conservative; several more passionate right-to-life candidates were given positions unrelated to health care. Scully is focusing now on …

Thermal detection of vulnerable plaque

hot plaques, BC showed a T resolution of 0.01°C capable of detecting T heterogeneity in various conditions of blood flow, plaque T, and luminal stenosis. We have tested this system in 5 inbred atherosclerotic dogs and 10 Watanabe rabbits. T heterogeneity was detected in all. By adding an ultrasound assembly to the BC, we are developing a combined ThermoElastography system, which, in its final prototype, will provide thermal, structural, and elasticity data for detecting plaques and determination of their functional status.