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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Temporal bone changes are described in a 57-year-old man who had sudden onset of dizziness and unilateral deafness two months before death. The patient suffered from hypertension, and congestive and renal failure. At autopsy, subarachnoid hemorrhage with punctate cortical hemorrhages and arteriolar thickening involved the right superior cerebellar hemisphere. The pathological changes involved primarily the right cochlea, saccule and posterior ampulla, and were consistent with vascular embarrassment of the temporal bone of two months duration. The cochlea demonstrated total loss of the organ of Corti and severe degenerative changes of the stria vascularis, spiral ligament, outer sulcus cells and distal cochlear nerve fibers. The saccule demonstrated loss of its macula and nerve fibers. The posterior ampulla showed evidence of previous rupture of its membranous wall with fibrosis and beginning bone formation. Fresh hemorrhage, present in some areas of both temporal bones, was related to the patient's terminal subarachnoid hemorrhage.
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PMID:Sudden deafnfess of vascular origin: a human temporal bone study. 125 20

In spite of the relatively large amount of in vitro and in vivo data indicating that, in a number of ways, cerebral arteries are pharmacologically different from peripheral arteries, the mechanisms responsible for these differences are far from clear. An understanding of these mechanisms is particularly important for a rational approach to the treatment of disorders of the cerebral circulation including migraine, hypertension and the responses of cerebral vessels to subarachnoid haemorrhage. This review outlines electrophysiological data which are available from cerebrovascular smooth muscle cells, including the possibility that inwardly-rectifying potassium channels, active at potentials close to the resting membrane potential, are intimately involved in the changes in smooth muscle tone which couple blood flow to regional changes in nerve cell activity. The membrane potential changes in response to perivascular nerve stimulation, noradrenaline, 5-hydroxytryptamine and endothelium-derived hyperpolarizing factor are also described, together with the underlying membrane mechanisms and their relationship to smooth muscle contraction and relaxation.
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PMID:Electrophysiology of cerebral blood vessels. 130 95

Dissecting aneurysms of cerebral arteries are unusual causes of stroke. The carotid system is the commonest site of this pathology, the vertebral arteries are less involved and dissection of the basilar artery is rare. The authors report three cases of arterial dissection of the vertebrobasilar system, two of the vertebral arteries and one of the basilar artery. An extensive review of the literature is presented. The clinical picture of dissection of vertebrobasilar system was inespecific but pain was a prominent symptom, though had not occurred in the site of the arteries involved. The pain was suggestive of subarachnoid hemorrhage. Associated or risk factors were mild trauma, migraine and high blood pressure. The angiographic findings were suggestive, however just the "double lumen" has been considered pathognomonic. The prognosis is variable. It was benign in case 3, left sequela in case 2, and case 1 rebleed fatally.
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PMID:[Intracranial dissecting aneurysms of the posterior circulation: report of 3 cases and review of the literature]. 130 14

This paper reviews recent developments in the biochemistry, pharmacology and physiology of the L-arginine/nitric oxide pathway. Nitric oxide accounts for the biological activity of endothelium-derived relaxing factor (EDRF) and its continuous release plays a crucial role in the regulation of vascular tone and platelet activity. In the nervous system nitric oxide is a neurotransmitter. In the peripheral nervous system, nitroxergic nerves form a part of the non-adrenergic, non-cholinergic innervation of the visceral organs. In the immune system, nitric oxide generated by activated macrophages has tumoricidal and antimicrobial activities. Growing evidence suggests that the alterations in the formation of NO in various tissues contribute to the pathogenesis of various diseases, including hypertension, atherosclerosis, diabetes, subarachnoid hemorrhage and septic shock. Therefore, the improvements in our understanding of the regulation of L-arginine/nitric oxide pathway on the molecular level may lead to the development of new drugs.
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PMID:[Biological role of metabolic pathways from L-arginine to nitric oxide]. 134 93

Endothelins (ET-1, ET-2 and ET-3) are a family of 21 amino acid peptides produced by endothelial cells. They are thought to regulate the local vasomotor tone with endothelium-derived relaxing factors. ETs are the most potent vasoconstrictor substances yet identified and veins and renal vasculature are the most sensitive targets. They reduce cardiac output and have positive inotropic and chronotropic effects. ETs increase the secretion of atrial natriuretic peptide (ANP), aldosterone and catecholamines but reduce renal blood flow and glomerular filtration and they also have mitogenic properties. ETs bind to receptors (ETA and ETB), activate phospholipase C, modulate intracellular Ca2+ concentration and open Ca2+ channels. Vasoactive agents (adrenaline, angiotensin, vasopressin, thrombin, endotoxins) and hypoxia stimulate the release of ET and also ET gene expression. Raised concentrations of plasma ET have been found to occur in several clinical conditions such as hypertension, myocardial infarction, cardiogenic shock, pregnancy induced hypertension, arteriosclerosis, Raynaud's disease, subarachnoid haemorrhage, uraemia, ulcerative colitis, Crohn's disease and surgical operations suggesting that ETs have a role in several patophysiological processes.
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PMID:Endothelin peptides: biological activities, cellular signalling and clinical significance. 138 14

The literature on the association of intracranial aneurysms in autosomal dominant polycystic kidney disease (ADPKD) consists mainly of case reports and small series of patients. To provide a more-detailed description of this association and its frequency, the records of all ADPKD patients with saccular intracranial aneurysms, all ADPKD autopsy cases including brain examination, and sex- and age-matched autopsy cases without ADPKD seen at the Mayo Clinic between 1950 and 1989 and of all Rochester residents with a diagnosis of subarachnoid hemorrhage or ADPKD between 1945 and 1984 were reviewed. The presentation of the 41 patients (22 men and 19 women; mean age, 46.4 yr) with this association was subarachnoid hemorrhage in 33, transient ischemic attacks in 2, incidental angiographic or autopsy finding in 5, and discovery during angiographic screening in 1. Thirty-one, seven, and three patients harbored one, two, and three aneurysms, respectively, arising from the middle cerebral artery (N = 23), anterior communicating artery (N = 16), internal carotid artery (N = 11), and vertebral or basilar artery (N = 4). A family history of intracranial aneurysm, subarachnoid hemorrhage, or intracranial hemorrhage at an early age was present in 22% of the patients. Small aneurysms (less than 5 mm) were less likely to have ruptured or caused symptoms (P less than 0.04). There was a trend for hypertension to be associated with the severity of the subarachnoid hemorrhage. Aneurysmal rupture occurred before age 50 in 64% of patients. Of the 89 ADPKD autopsy cases with brain examination, 22.5% had intracranial aneurysms.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Saccular intracranial aneurysms in autosomal dominant polycystic kidney disease. 139 12

Sixty-seven patients (27.9%) between 16 and 45 years, out of 240 cases of stroke seen over 33 months were further studied with respect to stroke type, aetiological and social factors. The frequency of non-embolic cerebral infarction was 58.2%, cerebral embolism 7.5%; cerebral haemorrhage 17.9%; primary subarachnoid haemorrhage 11.9%. Hypertension was the commonest aetiological factor occurring in 35.8% of the cases. Cervical spine hyperflexion, stenosing carotid arteritis, cocaine ingestion, mitral valve prolapse, non-valvular atrial fibrillation and chorion cancer featured among other less frequent but important factors presenting different diagnostic problems. The frequency of unexplained stroke was under 12%. The authors suggest that previously encountered cervical spine trauma among young stroke cases represent underreporting and that the relationship between young age, grand-multiparity and non-valvular atrial fibrillation be further elucidated.
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PMID:Stroke at the prime of life: a study of Nigerian Africans between the ages of 16 and 45 years. 139 94

The dynamic relationships among mean flow velocity, its pulsatile amplitude (FVa), cortical cerebral blood flow (CBF), and cerebral perfusion pressure (CPP) were studied in normal rabbits and rabbits with subarachnoid hemorrhage using 8-MHz pulsed transcranial Doppler ultrasound and hydrogen clearance under conditions of systemic hypotension and intracranial hypertension. A two-slope relationship was observed between FVa and CPP with a break point that correlated closely with the lower limit of CBF autoregulation in each animal. Below this CPP break point, FVa varied directly with CPP, and above the break point FVa varied inversely with CPP. In this experimental model, an inverse correlation between FVa and CPP indicates intact CBF autoregulation, whereas loss of that correlation implies exhaustion of autoregulatory reserve. Simultaneous recording and computation of FVa, CPP, and the correlation coefficient between FVa and CPP may be a means of monitoring CBF autoregulation in clinical practice.
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PMID:Experimental aspects of cerebrospinal hemodynamics: the relationship between blood flow velocity waveform and cerebral autoregulation. 140 56

Epidemiologists compared data on 434 cases of fatal stroke which occurred between 1986-88 in England and Wales with data on 1268 living matched controls to determine the association between use of the newer, low dose oral contraceptives (OCs) and the risk of stroke. History of hypertension was significantly associated with a 9-fold rise in the risk of subarachnoid hemorrhage (p.001) and an 8-fold rise in the risk of any hemorrhagic stroke. History of preeclampsia was also significantly associated with subarachnoid hemorrhage (p.01) and any hemorrhagic stroke. Cigarette smoking had a 2.6-fold increased risk of subarachnoid hemorrhage (p.001). The epidemiologists found an estimated relative risk of subarachnoid hemorrhage related to current OC use to be only 1.1 and when they controlled for confounding factors it was still small and insignificant (1.3). The power of the study showed the lowest significant increased relative risk of subarachnoid hemorrhage related to OC use that epidemiologists could have detected with 90% certainty to be 1.6. When the epidemiologists controlled for confounding factors, the insignificant relative risk of occlusive stroke associated with OC use was 4.4 while the power of the study indicated it to be 28.4. This was consistent with other studies, but other studies found the association to be significant. These findings revealed a possible small increase in the risk of subarachnoid hemorrhage associated with OC use.
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PMID:Fatal stroke and use of oral contraceptives: findings from a case-control study. 141 30

The traditional role of twin studies has been to assess the relative role of genetic factors as a first step in defining the genetic architecture of complex traits. This has been based on the realization that monozygotic pairs (MZ) share all their genes, while dizygotic pairs (DZ) share 50% of their genes on average. Thus, greater similarity of MZ pairs compared to DZ pairs has been taken as prima facie evidence of the role of genetic factors. This is true provided the environmental similarity of MZ pairs is not greater than for DZ pairs for effects relevant to the trait in question. This first step in genetic studies was carried out long ago in many research areas, but not in others. More detailed knowledge of the genetic architecture of traits is then obtained by other means. In this paper, we give a brief overview of some results for metabolic diseases (ischaemic heart disease, hypertension, subarachnoid haemorrhage, NIDDM and IDDM) using the classical twin approach in a large, unselected population-based twin cohort. We also outline approaches to using twins that we believe will continue to be useful, particularly for the study of environmental effects.
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PMID:Twin studies in metabolic diseases. 141 22


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