Publications by authors named "MH Keelan"

Background: Neointimal hyperplasia following percutaneous transluminal coronary angioplasty (PTCA) is one of the major components of the process of restenosis. We evaluated the long-term impact of local delivery of c-myc neutrally charged antisense oligonucleotides (Resten-NG) upon neointimal formation following PTCA in a rabbit model.

Methods: PTCA was performed in the iliac arteries of 10 New Zealand white rabbits at 8 atm for 30 s, three times.

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Background: Neointimal hyperplasia after PTCA is an important component of restenosis.

Methods And Results: Cultures of rabbit endothelial cells and smooth muscle cells (SMCs) were irradiated with different doses of nonablative infrared (1064-nm) radiation. Normalized viability index detected with nondestructive Alamar Blue assay and direct cell count were studied.

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Myointimal hyperplasia after percutaneous transluminal coronary angioplasty (PTCA) is a key component of the process of restenosis. The c-myc is a critical cell-cycle division protein involved in the formation of neointima. We evaluated the long-term impact of local delivery of c-myc neutrally charged antisense oligonucleotides (Resten-NG) on myointimal hyperplasia after PTCA in a rabbit model.

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Background And Objective: Numerous reports suggest that low-power laser irradiation (LPLI) is capable of affecting cellular processes in the absence of significant thermal effect. The objective of the present study was to determine the effect of LPLI on secretion of vascular endothelial growth factor (VEGF) and proliferation of human endothelial cells (EC) in vitro.

Study Design/materials And Methods: Cell cultures were irradiated with single different doses of LPLI (Laser irradiance from 0.

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Background And Objective: A high restenosis rate remains a limiting factor for percutaneous transluminal coronary angioplasty and stenting. The objective of this study was to evaluate the effect of intravascular red laser therapy (IRLT) on restenosis after stenting procedures in de novo lesions.

Study Design/materials And Methods: A total of 68 consecutive patients were treated with IRLT in conjunction with coronary stenting procedures.

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Background And Objective: Several reports suggest that low power red laser light (LPRLL) is capable of affecting cellular processes in the absence of significant thermal effect. The objective of the present study was to determine the effect of LPRLL on proliferation of fetal cardiomyocytes in vitro and on the expression of proangiogenic genes, transforming growth factor-beta (TGF-beta), and vascular endothelial growth factor (VEGF).

Study Design/materials And Methods: All cell cultures were irradiated with single-dose LPRLL using a He-Ne continuous wave laser (632 nm) with different doses.

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A high restenosis rate remains a limiting factor for coronary angioplasty and stenting. Recently, use of intravascular red light therapy (IRLT) has been shown to be effective in different animal models and in humans in reducing the restenosis rate. Sixty-eight patients were treated with IRLT in conjunction with coronary stenting procedures.

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Recently, intravascular low-power red laser light (LPRLL) therapy has been proposed for the prevention of postangioplasty restenosis due to the observed inhibition of experimental neointimal formation. The objective of this study was to determine the impact of endoluminal LPRLL on vascular levels of inducible nitric oxide synthase (iNOS) and cyclic guanosine monophosphate (cGMP) to help define the mechanism of this effect. Eight atherosclerotic male adult New Zealand White rabbits weighing 4-6 kg were used in these studies.

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Objectives: The objectives of this study were 1) to improve the attachment of reimplanted endothelial cells (EC) using a fibrin glue, and 2) to assess the impact of endothelial reseeding on restenosis eight weeks after balloon angioplasty.

Background: A possible mechanism contributing to restenosis after balloon angioplasty is the loss of the EC lining. Previous attempts to reseed EC had little effect due to rapid loss of the seeded cells.

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Direct revascularization of critical ischemia of the limb is often unsuccessful due to the anatomic extent and distribution of arterial occlusive disease, and no pharmacologic treatment has proved effective in treating this condition. Patients with ischemic limb may eventually require amputation and may develop serious morbidity and mortality. The goal of limb salvage in these patients has stimulated research into alternative treatment methods, including angiogenesis.

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BACKGROUND: It is believed that restenosis following coronary interventions is the result of endothelial denudation that leads to thrombus formation, vascular remodeling, and smooth muscle cell proliferation. We previously demonstrated that low power red laser light (LPRLL) irradiation enhances endothelial cell growth in vitro and in vivo and reduces restenosis in a small animal model. The present study investigated the effectiveness of intravascular LPRLL therapy in the reduction of restenosis following stenting in a porcine model.

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OBJECTIVES: The present study sought to investigate the safety and efficacy of a new fibrin sealant using percutaneous delivery techniques. BACKGROUND: The femoral approach has become the preferred means of access for percutaneous diagnostic and interventional procedures. Control of access site bleeding following catheterization, however, remains a significant problem in interventional cardiology.

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The objective of our study was to investigate the influence of different stent materials on endothelialization in vitro. Using the non-destructive Alamar Blue assay and scanning electron microscopy, we compared long-term growth and morphology of vascular cells on disks of three prospective stent materials, i.e.

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Critical ischemia of the limbs or myocardium is frequently accompanied by diffuse distal vascular disease making it unapproachable by conventional revascularization techniques. Pharmacological treatment is available for coronary artery disease but there has been no effective medical therapy for advanced ischemia of the limbs. In the search for alternative treatments for patients with diffuse distal disease, recent developments in vascular biology have directed attention towards use of vascular growth factors.

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Objectives: This study evaluated the long-term impact of endoluminal low power red laser light (LPRLL) on restenosis in an atherosclerotic rabbit model.

Background: Despite widespread application of balloon angioplasty for treatment of coronary artery disease, restenosis limits its clinical benefits. Restenosis is a complex process and may be partly attributed to the inability of the vascular endothelium to regenerate and cover the denuded area at the site of arterial injury.

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This study prospectively determined the feasibility and accuracy of prehospital thrombolytic therapy candidate selection by base station emergency physicians. During a 6-month period, paramedics acquired and transmitted prehospital 12-lead electrocardiograms (ECGs) and then applied a thrombolytic therapy contraindication checklist. Emergency physicians interpreted prehospital ECGs and prospectively selected candidates for thrombolytic therapy.

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Four patients with acute anterior wall myocardial infarction showing spontaneous and marked improvement in systolic left ventricular function are described. All 4 patients showed abnormal Q waves and severe wall motion abnormalities soon after acute infarction. In all 4 patients, at least some regeneration of R-wave forces occurred and the regional wall motion in the involved area of the left ventricle improved dramatically without coronary angioplasty or surgical revascularization during the intervening period.

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Chest pain that is associated with hyperventilation is often considered to be benign and noncardiac in nature. While not commonly recognized, hyperventilation can provoke coronary vasospasm. We report a man who presented with hyperventilation and developed myocardial infarction.

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We hypothesized that a process leading to an acute increase in cardiac size would change the relationship between intrapericardial pressure and fluid volume during cardiac tamponade, resulting in a change in the time of onset of right ventricular diastolic collapse (RVDC) as seen on the two-dimensional echocardiogram. Five spontaneously breathing dogs were instrumented to measure ascending aortic and right atrial blood pressures and intrapericardial pressure (IPP). A hydraulic occluder was placed around the proximal descending thoracic aorta.

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Tricuspid valve injury is a rare complication of transvenous pacemaker placement. We report such an injury in an elderly patient with cardiac amyloidosis. Because serious complications may result from such an injury, tricuspid valve perforation should be considered, along with the more common causes of new murmurs, in patients with pacemakers.

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Although coronary artery bypass surgery is beneficial to patients with severe coronary artery disease, its role in preventing the recurrence of prehospital cardiac arrest in patients is not clear. In this article, we report on the long-term follow-up of 49 survivors of prehospital coronary arrest who had coronary artery bypass surgery. Prior to their prehospital cardiac arrest, 14% of the patients had a history of unstable angina.

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The clinical, hemodynamic, surgical, and pathologic findings in 30 patients who required mitral valvular surgery and who had a preoperative diagnosis of mitral valve prolapse were reviewed. The mean age of the patients was 59.5 years; 28 patients were over 45 years of age and 10 were over 60 years.

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