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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renal artery dissection is a rare complication of catheter arteriography. Predisposing factors include atherosclerosis and fibromuscular dysplasia. Optimum management requires aortographic documentation of the extent of vascular obstruction. Dissections causing incomplete obstruction of blood flow can be treated with systemic anticoagulation to prevent downstream thrombosis and should be followed with serial isotope blood flow studies and LDH measurements. Dissection causing complete vascular obstruction usually requires immediate surgery, although spontaneous reestablishment of flow may occur. The 3 patients discussed illustrate a spectrum of findings, including the acute development of renovascular hypertension.
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PMID:Renal artery dissection: a complication of catheter arteriography. 117 54

Experimental models of vascular injury have enhanced our understanding of the pathophysiological process leading to vascular obstruction in both spontaneous and accelerated atherosclerosis. Based on experimental findings, we present and discuss a pathological classification of vascular injury or damage and its role in the pathogenesis of various vascular diseases. In addition, these animal models have provided insights into the roles of platelets and lipid metabolism in the evolution and progression of atherosclerosis and have suggested potential therapeutic applications. Thus, based on studies in the pig models, antiplatelet agents have been shown for the first time to have a beneficial effect in preventing the formation and progression of coronary atherosclerotic lesions in humans. Similarly, our findings in high density lipoprotein plasma fractions regarding inhibition and even reversal of the process of atherosclerosis in a hypercholesterolemic rabbit model have added new insights to an explosive field of lipoprotein research and provided new avenues of therapeutic strategies. our in vivo and ex vivo pig models of an extracorporeal perfusion chamber mimicking the various coronary conditions have aided in the understanding of the pathophysiology of the acute coronary syndromes and intensified our search for the ideal antithrombotic regimen in these high-risk patients. Finally, a carotid pig model of balloon angioplasty, a dog model of saphenous vein grafting, and a pig model of heart transplantation not only have provided insights into the pathophysiological process of accelerated atherosclerosis but also are allowing development of new antithrombotic and antiproliferative approaches for the prevention of these accelerated vascular diseases. In summary, we are entering an exciting era in vascular research. Significant advances in our understanding of vascular injury or damage as well as the interactions of blood cells and lipids with the vascular wall have allowed us to formulate new experimental strategies with subsequent clinical application in the prevention and progression of these vascular diseases.
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PMID:Importance of experimental models for the development of clinical trials on thromboatherosclerosis. 164 25

In 1904, Marchand recognized the consistent association of fatty degeneration and vessel stiffening and introduced the term "atherosclerosis" to indicate this combination. Current research is focused principally on the lipid component, but there is evidence that both aspects are reversible. Atheromatous lipids add significantly to the volume of lesions and thus contribute to vascular obstruction and end-organ damage. Reversal of atherosis has been observed in all the major species used in atherosclerosis research; rabbits, swine, dogs, chicks, pigeons, and subhuman primates. Direct evidence for reversal in humans is based on angiographic trials and is less extensive. One femoral artery and one coronary artery trial indicate that the lesions can be stabilized. CLAS, the largest angiographic trial to date, indicates that coronary lesion reversal is possible. Clinical effects of sclerosis are more subtle, and there is little evidence that sclerosis alone leads to end-organ damage. However, it should be noted that atherosclerotic lesions producing end-organ damage invariably have a major fibrous component. Sclerotic vessels have reduced systolic expansion and abnormally rapid pulse wave propagation, which can be measured noninvasively. Primate studies indicate that sclerosis is induced by hypercholesterolemic diets and is reversible when these diets are withdrawn. Changes in sclerosis may be another useful indicator of the formation and reversal of lesions and may involve changes in EDRF. Future studies of atherosclerosis reversal should use a combination of measures to evaluate both atherosis and sclerosis.
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PMID:Reversal of atherosis and sclerosis. The two components of atherosclerosis. 264 53

Since vascular disease is always progressive and a perfect vascular prosthesis has yet to be developed, postoperative complications are almost inevitable. In this paper, case histories of those who had to have a second operation or, in other words, re-operated patients, have been examined to ascertain the current problems in vascular surgery. Of 176 vascular reconstructive operations performed between January 1, 1980, and December 31, 1986, 29 re-operations were performed on 19 patients (mean age: 64 years; 15: male). The incidence of late graft failures was 8.4% and, of these, anastomotic aneurysms seemed to be the most serious complication (3.1% incidence rate). Late graft failures included intimal hyperplasia, occurring within two years in five cases, and four cases of progressing atherosclerosis, which appeared three years after the initial operation. In all cases of anastomotic aneurysm, arterial wall failure, possibly combined with the changing of implanted grafts, was considered to be related to the false aneurysmal formation. Knitted Dacron demonstrated susceptibility to atherosclerotic progression, whereas the major fault of polytetrafluoroethylene (PTFE) grafts was the insufficiency of the anastomotic diameter. In conclusion, it was revealed that many factors can provoke late graft failure. Improvement of long-term patency seems to be achieved by a more increased understanding of the pathological meaning of these factors, along with the proper application of medical techniques suited to the causes of vascular obstruction.
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PMID:Pathological considerations of reoperative vascular patients. 296 40

Platelets are believed to play a role in the pathogenesis of atherosclerosis and of the vascular obstruction that causes the acute complications of coronary artery disease. Since specific behavioral patterns appear to be related to the development of coronary artery disease and since emotional stress may predispose an individual to acute cardiovascular ischemia, it was hypothesized that platelet activation by catecholamines might be involved in these events. To study emotional stress, plasma samples were obtained from 61 senior medical residents immediately before they were to speak in public. There were significant increases in the plasma concentrations of the platelet-secreted proteins platelet factor 4 and beta-thromboglobulin and epinephrine and norepinephrine immediately before speaking, which demonstrates that platelet activation and secretion occur in association with this type of emotional stress. Four trials were carried out to study the mechanism for this observed platelet secretion: (1) phenoxybenzamine, (2) propranolol, (3) 650 mg aspirin, and (4) 80 mg aspirin were given several hours before the public speaking engagement. Neither phenoxybenzamine nor propranolol in doses that blocked the hemodynamic effects of alpha 1- and beta 1-adrenergic stimulation modified platelet secretion. Aspirin also did not block platelet secretion, which suggests that platelets were not being stimulated through a cyclooxygenase-dependent pathway. This study provides direct evidence of platelet secretion in vivo in association with emotional stress, and underscores the potential importance of platelet activation and secretion in the acute events that occur in patients with vascular disease.
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PMID:Platelet activation and secretion associated with emotional stress. 298 76

The aim of this report is to describe the intracranial cerebrovascular abnormalities and clinical status of 8 children who had familial lipoprotein disorders and evidence of thromboembolic cerebrovascular disease. Six of the 8 children had low levels of plasma high density lipoprotein cholesterol, two had high triglyceride levels, and all came from kindreds characterized by familial lipoprotein abnormalities and premature cardio- and/or cerebrovascular atherosclerosis. Vascular occlusion, irregularities of the arterial lumen, beading, tortuosity, and evidence of collateralization were consistently noted. We speculate that cerebrovascular arteriosclerosis in pediatric ischemic stroke victims who have familial lipoprotein abnormalities may be related to lipoprotein-mediated endothelial damage and thrombosis formation, or to the failure to restore endothelial cells' integrity following damage. The apparent association of lipoproteins and strokes in children and their families merits further exploration, particularly when assessing cerebral angiograms in pediatric ischemic stroke victims. In children with unexplained ischemic cerebrovascular accidents, the diagnostic possibility of occlusive arteriosclerosis with thrombosis must be entertained.
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PMID:Cerebrovascular arteriopathy (arteriosclerosis) and ischemic childhood stroke. 708 Jan 31

Atherosclerosis is characterized by hypertrophy of the vascular media, intimal thickening and lipid-containing plaques. Atherosclerosis is a progressive systemic vascular disease which leads to impaired tissue perfusion due to vascular obstruction. In advanced stages it is often complicated by thrombosis. Recent research demonstrates that atherosclerosis is also a functional disease. In atherosclerosis and hypercholesterolemia, normal vasodilatation is impaired due to endothelial dysfunction. In addition, the ability of the vessel wall to reject adhering and aggregating platelets is deteriorated. Endothelial dysfunction in atherosclerosis is characterized by impaired formation of nitric oxide (NO), formerly known as endothelium-derived relaxing factor (EDRF). NO is continuously formed in the vascular endothelium and promotes tissue perfusion by relaxation of vascular smooth muscle. Endogenously formed NO may also protect against foam cell formation and media hypertrophy, i.e. against the structural component of atherosclerosis. In patients with ischaemic heart disease, the endothelial dysfunction leads to decreased ability to dilate the coronary vessels in response to several forms of physiological stimuli. Endothelial dysfunction in atherosclerosis is reversed by lipid-lowering therapeutic interventions.
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PMID:Nitric oxide (NO) in the cardiovascular system: role in atherosclerosis and hypercholesterolemia. 786 90

We tested the hypothesis that endothelial nitric oxide synthase (eNOS) modulates angiogenesis in two animal models in which therapeutic angiogenesis has been characterized as a compensatory response to tissue ischemia. We first administered L-arginine, previously shown to augment endogenous production of NO, to normal rabbits with operatively induced hindlimb ischemia. Angiogenesis in the ischemic hindlimb was significantly improved by dietary supplementation with L-arginine, compared to placebo-treated controls; angiographically evident vascularity in the ischemic limb, hemodynamic indices of limb perfusion, capillary density, and vasomotor reactivity in the collateral vessel-dependent ischemic limb were all improved by oral L-arginine supplementation. A murine model of operatively induced hindlimb ischemia was used to investigate the impact of targeted disruption of the gene encoding for ENOS on angiogenesis. Angiogenesis in the ischemic hindlimb was significantly impaired in eNOS-/- mice versus wild-type controls evaluated by either laser Doppler flow analysis or capillary density measurement. Impaired angiogenesis in eNOS-/- mice was not improved by administration of vascular endothelial growth factor (VEGF), suggesting that eNOS acts downstream from VEGF. Thus, (a) eNOS is a downstream mediator for in vivo angiogenesis, and (b) promoting eNOS activity by L-arginine supplementation accelerates in vivo angiogenesis. These findings suggest that defective endothelial NO synthesis may limit angiogenesis in patients with endothelial dysfunction related to atherosclerosis, and that oral L-arginine supplementation constitutes a potential therapeutic strategy for accelerating angiogenesis in patients with advanced vascular obstruction.
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PMID:Nitric oxide synthase modulates angiogenesis in response to tissue ischemia. 961 28

Atherothrombosis defines the occurrence of thrombosis on atherosclerotic lesions. Atherosclerosis is the most prevalent disease of our time and its thrombotic complications are responsible for an exceedingly high number of deaths and disabilities. Over the past few years, experimental investigation and clinical and pathologic observations have led to a better understanding of how a thrombus forms and also of its incidence in acute ischemic syndromes. A thrombus is usually found secondary to atherosclerotic plaque disruption. Mural thrombosis, also at the site of plaque rupture, is an important mechanism in the progression of atherosclerosis even when symptoms are absent. Because atherosclerosis is a silent and asymptomatic disease until complications arise with thrombosis producing clinical symptoms, it is necessary to have models that reproduce the human disease in its early stages. Unfortunately, not all the experimental models of vascular disease have human resemblance and validity. Knowledge of the disease process and of what an experimental animal model can offer is a milestone for a successful investigation. Experimental models of vascular disease have enhanced our understanding of the pathophysiological processes leading to vascular obstruction in both spontaneous and accelerated atherosclerosis and thrombosis. Animal models have provided insight into the role of platelets, lipids, renin-angiotensin system (RAS), cytokines and growth factors in the evolution and progression of atherosclerosis and have suggested potential therapeutic interventions. Significant advances in our understanding of the vascular biology and pathology of atherosclerosis and thrombosis, and of the interactions of blood cells, lipids and proteins with the vascular wall, have allowed us to formulate new experimental hypotheses and to test therapeutic strategies, either pharmacological or surgical.
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PMID:Atherosclerosis and thrombosis: lessons from animal models. 1148 25

Atherosclerosis is a major cause of morbidity and mortality in Western world. Vascular occlusion caused by atherosclerosis usually requires invasive treatment, such as surgical bypass or angioplasty. However, bypass graft failure and restenosis limit the usefulness of these procedures, with 20% of patients needing a new revascularisation procedure within 6 months of angioplasty. Numerous pharmacological agents have been investigated for the prevention of restenosis but none has shown undisputed efficacy in clinical medicine. Gene transfer offers a novel approach to the treatment of restenosis because of easy accessibility of vessels and already existing gene delivery methods. It can be used to overexpress therapeutically important proteins locally without high systemic toxicity, and the therapeutic effect can be targeted to a particular pathophysiological event. Promising results have been obtained from many pre-clinical experiments using therapeutic genes or oligonucleotides to prevent restenosis. Early clinical trials have shown that plasmid- and adenovirus-mediated vascular gene transfers can be conducted safely and are well tolerated. Ex vivo gene therapy with E2F-decoy succeeded in reducing graft occlusion rate after surgical bypass in a randomised, double-blind clinical trial. In the future, further development of gene delivery methods and vectors is needed to improve the efficacy and safety of gene therapy. Also, better knowledge of vascular biology at the molecular level is needed to find optimal strategies and gene combinations to treat restenosis. Provided that these difficulties can be solved, gene therapy offers an enormous potential for clinical medicine in the future.
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PMID:Gene therapy for restenosis: current status. 1210 21


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