ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundNeointimal formation causes restenosis after intracoronary stent placement. Endovascular radiation delivered via a stent has been shown to reduce neointimal formation after placement in porcine and rabbit iliac arteries. The objective of this study was to evaluate the dose-related effects of a beta-particle-emitting radioactive stent in a porcine coronary restenosis model.Methods and ResultsThirty-seven swine underwent placement of 35 nonradioactive and 39beta-particle-emitting stents with activity levels of 23.0, 14.0, 6.0, 3.0, 1.0, 0.5, and 0.15 micro Ci of32Phosphorus. Treatment effect was assessed by histological analysis 28 days after stent placement. Neointimal and medial smooth muscle cell density were inversely related to increasing stent activity. The neointima of the high-activity (3.0- to 23.0-micro Ci) stents consisted of fibrin, erythrocytes, occasional inflammatory cells, and smooth muscle cells with partial endothelialization of the luminal surface. In the 1.0-micro Ci stents, the neointima was expanded and consisted of smooth muscle cells and a proteoglycan-rich matrix. The neointima of the low-activity (0.15- and 0.5-micro Ci) stents was composed of smooth muscle cells and matrix with complete endothelialization of the luminal surface. At low and high stent activities, there was a reduction in neointimal area (low, 1.63 +/- 0.67 mm2and high, 1.73 +/- 0.97 mm sup 2 versus control, 2.40 +/- 0.87 mm2) and percent area stenosis (low, 26 +/- 7% and high, 26 +/- 12%) compared with control stents (37 +/- 12%, P less or equal to .01). The 1.0-micro Ci stents, however, had greater neointimal formation (4.67 +/- 1.50 mm2) and more luminal narrowing (64 +/- 16%) than the control stents (P < .0001).ConclusionsThe differential response to the doses of continuous beta-particle irradiation used in this experimental model suggests a complex biological interaction of endovascular radiation and vascular repair after stent placement. Further study is required to determine the clinical potential for this therapy to prevent stent restenosis. (Circulation. 1996;94:2364-2368.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundThere is accumulating experimental, epidemiological, and clinical evidence of an association between antioxidant vitamin intake and reduced risk of coronary heart disease. Using data from the Cholesterol Lowering Atherosclerosis Study (CLAS), we explored the association of self-selected supplementary antioxidant vitamin intake on the rate of progression of early preintrusive atherosclerosis.Methods and ResultsCLAS was an arterial imaging trial in which nonsmoking 40- to 59-year-old men with previous coronary artery bypass graft surgery were randomized to colestipol/niacin plus diet or placebo plus diet. The rate of progression of early preintrusive atherosclerosis was determined in 146 subjects using high-resolution B-mode ultrasound quantification of the distal common carotid artery far wall intima-media thickness (IMT). From the nutritional supplement database, 22 subjects had an on-trial average supplementary vitamin E intake of greater or equal to 100 IU per day (high users) and 29 subjects had an average on-trial supplementary vitamin C intake of greater or equal to 250 mg per day (high users). Within the placebo group, less carotid IMT progression was found for high supplementary vitamin E users when compared with low vitamin E users (0.008 versus 0.023 mm/y, P=.03). No effect of vitamin E within the drug group was found. No effect of vitamin C within the drug or placebo group was found.ConclusionsSupplementary vitamin E intake appears to be effective in reducing the progression of atherosclerosis in subjects not treated with lipid-lowering drugs while the process is still confined to the arterial wall (early preintrusive atherosclerosis). (Circulation. 1996;94:2369-2372.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundElevated levels of C-reactive protein (CRP) are associated with an unfavorable clinical outcome in patients with unstable angina. To determine whether ischemia-reperfusion injury causes this acute-phase response, we studied the temporal relation between plasma levels of CRP and ischemic episodes in 48 patients with unstable angina and 20 control patients with active variant angina, in which severe myocardial ischemia is caused by occlusive coronary artery spasm.Methods and Results10 minutes.ConclusionsThe normal levels of CRP in variant angina, despite a significantly larger number of ischemic episodes and greater total ischemic burden, and the failure of CRP values to increase in unstable angina indicate that transient myocardial ischemia, within the range of duration observed, does not itself stimulate an appreciable acute-phase response. (Circulation. 1996;94:2373-2380.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundThe association of serum lipids with coronary heart disease has been studied extensively in middle-aged men and, to a lesser extent, in similar women. Less well defined are lipid variables predictive of CHD in individuals of age greater or equal to 60 years.Methods and ResultsThe Systolic Hypertension in the Elderly Program recruited 4736 persons (mean age, 72 years; 14% were black; and 43% were men). Mean systolic and diastolic blood pressures were 170 and 77 mm Hg, respectively. Baseline mean total cholesterol was 6.11 mmol/L (236 mg/dL); HDL cholesterol, 1.39 mmol/L (54 mg/dL); and non-HDL cholesterol, 4.72 mmol/L (182 mg/dL). Triglyceride levels were 1.62 mmol/L (144 mg/dL) for fasting participants and 1.78 mmol/L for the total group. LDL cholesterol, estimated in fasting samples with triglycerides of < 4.52 mmol/L, averaged 3.98 mmol/L (154 mg/dL). Mean follow-up was 4.5 years. In multivariate Cox regression analyses, baseline total, non-HDL, and LDL cholesterol levels and the ratios of total, non-HDL, and LDL to HDL cholesterol were significantly related to CHD incidence. HDL cholesterol and triglycerides were not significant in these analyses. In fasting participants with triglyceride levels of <4.52 mmol/L, a 1.03 mmol/L (40 mg/dL) higher baseline total, non-HDL, or LDL cholesterol was associated with a 30% to 35% higher CHD event rate.ConclusionsThe results of this study support the concept that serum lipids are CHD risk factors in older Americans. (Circulation. 1996;94:2381-2388.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundThrombin plays an important role in the pathogenesis of acute coronary thrombosis. We studied the effects of a direct thrombin inhibitor, recombinant desulfatohirudin, and heparin on plasma levels (at 0, 4, 12, and 24 hours) of fibrinopeptide A (FPA), which reflects thrombin action, and prothrombin fragment F1.2, which reflects thrombin generation, in patients with unstable angina.Methods and ResultsPatients were randomized to one of two doses of heparin (n = 50) (target activated partial thromboplastin time, 65 to 90 seconds or 90 to 110 seconds) or one of four doses of r-hirudin (n = 113) (0.05, 0.10, 0.20, or 0.30 mg [centered dot] kg sup -1 [centered dot] h sup -1 by infusion). r-Hirudin induced a dose-dependent decline in plasma FPA. At 24 hours, FPA levels with 0.1- to 0.3-mg [centered dot] kg sup -1 [centered dot] h sup -1 r-hirudin regimens were significantly lower than with 0.05 mg [centered dot] kg sup -1 [centered dot] h sup -1 r-hirudin; levels with 0.1- to 0.2-mg [centered dot] kg sup -1 [centered dot] h sup -1 r-hirudin regimens were lower than with both heparin regimens. Plasma F1.2 did not decline significantly during therapy with heparin or hirudin except at 0.3 mg [centered dot] kg sup -1 [centered dot] h sup -1 hirudin. At 24 hours, they were higher with the 0.05-mg [centered dot] kg sup -1 [centered dot] h sup -1 r-hirudin regimen than with other regimens. For comparable levels of thrombin generation (F1.2 levels), FPA levels were higher in heparin patients than in hirudin patients. For the same FPA values, the corresponding F1.2 values were higher in the hirudin group.ConclusionsOur findings provide evidence for distinct in vivo effects of the two agents and suggest that r-hirudin is a relatively more potent inhibitor of thrombin action but a less effective inhibitor of thrombin generation than heparin. The lower FPA levels in hirudin patients may reflect its ability to inactivate clot-bound thrombin. The relative clinical efficacies of the two agents need to be defined by clinical trials in progress. (Circulation. 1996;94:2389-2395.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

BackgroundAlthough a specific etiology for Takayasu arteritis has not been found, the bulk of evidence favors an autoimmune mechanism. We examined the sera of 19 patients with Takayasu arteritis for antineutrophil cytoplasmic antibodies (ANCA), antinuclear antibodies (ANA), anti-DNA antibodies, antibodies to extractable nuclear antigens (ENA), anti-Ro antibodies, anticardiolipin antibodies, circulating immune complexes, and anti-endothelial cell antibodies (AECA).Methods and ResultsWe used enzyme-linked immunoassays, immunofluorescence, counterimmunoelectrophoresis, fluorescent-activated cell sorter (FACS) analysis, and confocal microscopy. We found that although no patient had positive ANCA, ANA, anti-DNA antibodies, ENA antibodies, anti-Ro antibodies, or anticardiolipin antibodies, 18 of the 19 patients had AECA. The AECA titers of the patients were 2561 +/- 1458 compared with 126 +/- 15 arbitrary units in a normal group of control subjects (P < .001). To verify the specificity of AECA, we performed cytofluorimetry on human endothelial cells with the sera from patients and control subjects. Two entirely separate patterns of fluorescence intensity were identified. We next performed immunocytochemistry and confocal microscopy with human endothelial cells subjected to patients' sera and to sera from normal subjects. The cells subjected to sera from patients with Takayasu arteritis demonstrated specific immunofluorescent staining of their plasma membrane and cytosol.ConclusionsAECA are frequently present in patients with Takayasu arteritis. They may play a role in the pathogenesis. Furthermore, they may be useful as an additional diagnostic tool. (Circulation. 1996;94:2396-2401.)

ISSN:0009-7322    

出版商:OVID    

年代:1996

数据来源: OVID