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

A new model was developed to study endothelial regeneration and the effects of endothelial denudation in large arteries. Complete endothelial loss was produced in a sharply defined, unbranched segment of the rat common carotid artery by brief drying with a gentle stream of air along the lumen of the vessel. Platelets became attached to the denuded surface, but no polymorphonuclear or mononuclear leukocytic adherence or infiltration was observed. Regeneration occurred by the ingrowth, from each end of the denuded segment, of sheets of rapidly dividing endothelial cells. Endothelial replacement was complete by 7 to 10 days after drying. It was also noted that, by 14 days after drying, a striking myointimal thickening developed in the central region of the denuded segment. This central region was the last area to be covered with new endothelium; while still denuded, the region showed edema and signs of cellular proliferation in the innermost medial layer. The myointimal thickening consisted of smooth muscle-like cells in a fibroelastic stroma in the deeper zones, and a layer of rounded, relatively undifferentiated cells in the superficial zones. Progressive regression and condensation of the thickening was observed between 14 days and 3 months. In this model, the clear demarcation and completeness of endothelial denudation in the arterial segment allow study of the over-all process of endothelial replacement, avoiding the confusion imposed by islands of residual endothelium or contributions from branch vessels. The results suggest that the new endothelium in this situation is derived from each end of the segment. In addition, because the method of inducing denudation does not cause significant damage to the underlying media (as shown by the absence of inflammatory cell attachment or infiltration), the model offers a unique opportunity to study the relationship between endothelial loss and changes in the vessel wall. The correlation between the duration of endothelial denudation and the extent of myointimal thickening suggests that sustained insudation of certain, as yet undefined, factors from the lumen may provoke cellular proliferation in the arterial wall. Further investigation of this model should provide information relevant to the pathogenesis of the fibromuscular thickenings of human atherosclerosis.
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PMID:Endothelial regeneration in the rat carotid artery and the significance of endothelial denudation in the pathogenesis of myointimal thickening. 112 13

The available data on the adrenergic influences on lipoprotein metabolism are reviewed. It is clear that the influences are complex. It appears that adrenergic stimuli act at multiple sites in the lipoprotein metabolic pathways. This explains in part, the confusion in interpreting the literature. Based on the effects of alpha- and beta-adrenergic blocker administration in animals and humans, it is clear that the net effect of alpha 1-receptor stimulation is a decrease in HDL cholesterol and an increase in LDL cholesterol and VLDL triglyceride. On the other hand, beta-receptor stimulation will result in a net reduction of LDL and an increase in HDL. Further studies to elucidate the exact mechanism of action by the adrenergic stimuli on lipoprotein metabolism should provide insights into the relationship between the adrenergic nervous system and atherosclerosis and an enhanced understanding of the mechanisms by which antihypertensive-adrenergic mechanisms--alpha 1-Inhibition--Atherosclerosis--Serum lipids.
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PMID:Regulation of lipoprotein metabolism by adrenergic mechanisms. 244 36

The question whether initial antihypertensive treatment with a beta-blocker prevents hypertensive complications better than initial treatment with a non-betablocker, mainly diuretic based treatment, has been studied in recent large-scale studies like the Medical Research Council (MRC) trial, the International Prospective Primary Prevention Study in Hypertension (IPPPSH), the Heart Attack Primary Prevention in Hypertension (HAPPHY) study and the Metoprolol Atherosclerosis Prevention in Hypertensives (MAPHY) study. The first three studies were unable to find a more beneficial effect of beta-blockers than of thiazide diuretics. The MAPHY study, however, found a lower total mortality, in the metoprolol treated group than in the diuretic treated. As the HAPPHY and MAPHY studies share a substantial part of patient-years and number of deaths, these diverging results have evoked confusion and debate. This paper presents the main results of both studies and discusses the possible reasons for the different outcome.
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PMID:Beta-blockers and diuretics. The HAPPHY and MAPHY studies. 257 34

Dramatic advances have been made over the last decade in understanding the role of low-density lipoprotein (LDL) in atherosclerotic cardiovascular diseases and how to manage elevated levels of LDL cholesterol. Understanding the role of high-density lipoprotein (HDL) and how to intervene therapeutically in HDL action offers the possibility of even greater benefits. Epidemiologic studies have shown a strong inverse relation between HDL cholesterol and the risk of coronary artery disease (CAD). Whereas several subfractions of HDL can be identified, none convincingly offers better predictive value than total HDL cholesterol. Apolipoprotein A-I, the major apolipoprotein of HDL, also is inversely related to atherosclerotic risk. Unfortunately, measurements of HDL cholesterol or apolipoprotein A-I are considerably less precise and less accurate than measurements of total or LDL cholesterol. The biologic phenomena responsible for these epidemiologic relations are not yet clear. Moreover, several apparently contradictory observations and puzzling exceptions to the simplistic inverse relation of HDL cholesterol to CAD suggested by epidemiologic studies have created considerable confusion. The current confusion is not likely to be resolved until HDL metabolism and the cellular and molecular events responsible for the apparent protective effects of HDL are better understood. One current hypothesis that could explain the protective effects of HDL is that it mediates reverse cholesterol transport, the process by which cholesterol is removed from sites of deposition and delivered to the liver for excretion. From the standpoint of current therapy, each intervention that changes HDL cholesterol levels must be evaluated individually, on its own merit, in light of its effect on atherosclerosis and coronary events rather than on alterations in HDL cholesterol levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:High-density lipoprotein cholesterol levels as a marker of reverse cholesterol transport. 267 25

The origins of historical terms, such as "Arc of Riolan" and "marginal artery of Drummond" are traced herein with emphasis on the inherent confusion caused when these terms are used. Basic mesenteric anatomy is briefly mentioned and pathologic anatomy with its altered direction of blood flow induced by atherosclerosis is stressed. The significance of the meandering mesenteric artery as the main collateral vessel between the superior and inferior mesenteric artery is emphasized along with preoperative and intraoperative ways to ascertain whether or not the origin of this latter vessel can be safely ligated. Specific operations, such as abdominal aortic aneurysmorrhaphy and sigmoid colectomy, which can potentially interfere with blood flow in the meandering mesenteric artery, are discussed in an attempt to prevent postoperative necrosis of any portion of the intestine that may have deficient mesenteric blood flow.
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PMID:Collateral mesenteric circulation. 355 67

Complete evaluation of older patients with mental changes always leaves us with a certain percentage whose condition can only be attributed to atherosclerosis. Little is being done for these patients because this generalized stenosis of the brain does not reverse with any known treatment. This writer has treated many such patients with hyperbaric oxygen (HBO), and presents this case history, along with regional cerebral blood flow (rCBF) studies, showing the type of changes which frequently occur. This case initially presented with symptoms of gross mental confusion, memory loss, both recent and remote, irrational speech and occasional violence. Although prior complete evaluations were concluded with no recommended treatment, the initial series of HBO treatment resulted in a well-functioning patient. This was maintained for four years with intermittent HBO. The patient then presented with acute stroke, total disorientation and confusion. He again became functional with HBO. A discussion of the mechanisms of HBO which might account for the changes is given.
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PMID:Generalized small-vessel stenosis in the brain. A case history of a patient treated with monoplace hyperbaric oxygen at 1.5 to 2 ATA. 688 86

A comparison of the major cerebral arteries between humans and rats shows many similarities, including anomalies in their general organization, the structure of these vessels at the light and electron microscope levels and their morphological changes associated with cerebral vascular diseases. The general organization of the major cerebral arteries shows the following main differences between humans and rats. In rats, the internal carotid arteries have become an integral part of the circle of Willis. In the anterior cerebral arteries, a common variation in humans is the underdevelopment of one of the two arteries, whereas in rats, buttonhole-like structures are common in one or both arteries. The anterior communicating artery present in humans is absent in rats. The olfactory artery is prominent in rats, but absent in humans. The posterior communicating artery in humans is the most variable component of the circle of Willis, being asymmetric in its origin, diameters and branches. Similarly, the posterior cerebral arteries in rats often exhibit asymmetrical origin from the basilar artery. There was some confusion in the literature regarding the name of the posterior cerebral arteries in rats, but this was caused mainly by misquotations and incorrect interpretations of the papers. In humans, most aneurysms occur in the anterior half of the circle of Willis, and the incidence is higher in females than males; the middle cerebral artery is most often the one to become occluded, and the vertebral arteries are common sites for thrombosis. The various channels that constitute collateral circulation in humans provide a margin of safety, so that in case of cerebral occlusion due to thrombosis, atherosclerosis, or vasospasm related to hemorrhage, blood supply to the affected area can be maintained through these collaterals. Collateral circulation is also present in rats. However, in rats, information on the presence of various types of aneurysms, their location and frequency in normal and experimental models of hypertension and stroke is still lacking. Cerebral arteries from humans and rats are characterized by the absence of external elastic lamina, as compared with systemic arteries. A type of multipolar cell resembling the interstitial cell of Cajal is present in the cerebral arteries of humans. Its function is unknown. Earlier reports of cerebral valves have been shown to represent intimal cushions near the branching points of the cerebral arteries. Intravascular bridges present in human cerebral arteries, have not been reported in rats. Finally, the presence of vascular remodeling, as found in the cerebral arterioles of hypertensive rats, remains to be established in the cerebral arterioles of human hypertensives.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Morphology of cerebral arteries. 763 Sep 27

The high coronary heart disease morbidity and mortality and the economic costs have led to intensive prevention efforts in Switzerland, where the management of multiple risk factors plays a prominent role. An important risk factor is hypercholesterolemia, one of the main causes in the development of human atherosclerosis. However, the eminence of this risk factor is not yet sufficiently established in the awareness of many physicians. Inappropriate public discussions of the problem have caused confusion among patients and physicians. Therefore, the purpose of the Cholesterin Informations Program of the Swiss Heart Foundation is to work out a far-reaching and objective information strategy for experts and the general population, based on scientific knowledge, as a contribution to promoting the health of the Swiss population.
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PMID:[Cholesterol: blood level and control by Swiss physicians]. 770 84

A 50-year-old man was admitted to our hospital, because of weakness in his right leg. On admission, he had generalized hyperreflexia and positive Babinski signs bilaterally. After admission, weakness in his left leg and confusion developed. A cerebrospinal fluid examination revealed increases in cell counts and protein but was negative for malignant cells. Blood chemistry was normal except for elevated LDH. A bone marrow biopsy yielded lymphoma cells. Successive T2-weighted cranial MRI showed a progressively expanding high signal area in the right parieto-occipital lobe. His confusional state improved after chemotherapy; however, two months later another cranial CT showed multiple enhanced mass lesions. The patient died 20 months after the onset of illness. Postmortem examination revealed widespread intravascular aggregates of malignant lymphomatous cells in the cerebrum, lungs and kidney, as well as multiple infarcts without atherosclerosis in the cerebrum. These pathological findings are compatible with those of intravascular malignant lymphomatosis. In addition, extravascularly expanding tumor cells formed multiple nodular lesions in the cerebral hemisphere. An immunohistochemical study showed that the tumor cells were positive for B-cell marker L26. Intracranial lymphomatous mass lesion rarely occurs in cases of intravascular malignant lymphomatosis. In the present case, tumor cells were presumably restricted to intravascular spaces, occluded them and resulted in ischemic lesions in the cerebrum in the early phase, but they expanded extravascularly and developed mass lesions in the terminal stages. In conclusion, intravascular malignant lymphomatosis is considered to be phenotypes of malignant lymphoma. This is the first case of intravascular malignant lymphomatosis associated with intracranial lymphomatous mass lesions in Japan.
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PMID:[An autopsy case of intravascular malignant lymphomatosis with intracranial lymphomatous mass lesions]. 778 Dec 32

In any discussion of lipids and heart disease it is beneficial from the outset to recognise that at least three different pathological processes may be involved. The first of these is atherosclerosis which involves the deposition of "fat" in the coronary vessels, another is thrombogenesis which describes the formation of blood clots in the coronary vessels, and the third is arrhythmia which refers to disorders in the beating of the heart which may become sufficiently serious to cause sudden cardiac death (SCD). Also it is this disturbance in the rhythmic beating of the heart which is responsible for much of the mortality from 'heart attacks' which occur 'outside-of-hospital' in societies like U.S.A., U.K. and Australia. It is this latter condition of cardiac arrhythmia which is the major concern of this review. Because it is often difficult to differentiate the role of lipids in 'heart disease' in man, it has frequently been assumed that all dietary fatty acids have similar effects on the different processes involved, and many unwarranted generalisations have been made which have led to conflicts of opinion amongst physicians and confusion in the lay public. From the animal studies discussed in this review, it is apparent that dietary fatty acids have an important role to play in determining the vulnerability of the myocardium to develop serious ventricular fibrillation (VF) and potentially lethal cardiac arrhythmia. In general, diets rich in saturated fatty acids promote a state of myocardial vulnerability, whilst diets rich in PUFA significantly diminish the probability of developing lethal disorders in cardiac rhythm when the heart is placed under pharmacological (or emotional) stress, or deprived of sufficient blood flow and supply of oxygen. Very recent experiments with the monounsaturated fatty acid (MUFA) oleic acid clearly demonstrate that, at least in rats subjected to ligation of their coronary artery, this acid is not 'neutral' as has been suggested by some for its role in atherosclerosis, but in fact is indistinguishable from saturated fatty acids in its effect in promoting arrhythmia during either regional ischaemia or reperfusion arrhythmia in this animal model of SCD.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Lipids and cardiac arrhythmia. 787 Jul 38


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