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

Hypertension in chronic renal failure is usually due to excessive accumulation of salt and water. In some cases, sodium and volume depletion by dialysis fail to reduce the high BP, and plasma renin activity tends to be higher. We performed a semiquantitative analysis of the immunohistochemical distribution of renin in the kidneys of ten patients with end-stage renal disease and hypertension using a specific antihuman renin antibody and a peroxidase-antiperoxidase technique on paraffin sections of nephrectomy and/or autopsy specimens. In five cases with severe, dialysis-resistant hypertension, the degree of immunoreactivity was most striking, exceeding that found in renovascular hypertension and present in arterioles at a distance from the glomeruli. Three cases of advanced diabetic glomerulosclerosis consistently showed minimal immunoreactivity. We conclude that renin often can be detected immunologically in the kidney of patients with chronic renal failure and hypertension, but its pathophysiological role will require further study.
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PMID:Immunohistochemical localization of renin in end-stage kidneys. 304 41

In the present paper the neuronal systems of the medulla oblongata containing phenylethanolamine-N-methyltransferase- and neuropeptide Y-like immunoreactivity have been characterized in adult (3-month-old) and old (24-month-old) male rats. The phenylethanolamine-N-methyltransferase and neuropeptide Y-immunoreactive neurons have been visualized by means of immunocytochemistry (peroxidase-antiperoxidase technique) and analysed in a quantitative fashion by means of morphometrical (phenylethanolamine-N-methyltransferase- and neuropeptide Y-immunoreactive cell groups) and microdensitometrical (phenylethanolamine-N-methyltransferase-immunoreactive cell groups) approaches developed on the IBAS II image analyser (Zeiss-Kontron). During aging there is (a) a reduction in the area covered by the phenylethanolamine-N-methyltransferase-immunoreactive neuropil for both the C1 and C2 adrenaline cell groups; (b) a reduction in the area covered by the phenylethanolamine-N-methyltransferase-immunoreactive cell bodies, which is highly significant only for the C2 cell group; (c) a decrease in the area covered by the phenylethanolamine-N-methyltransferase-positive cell cluster for both C1 and C2 cell groups; (d) a decrease in the degree of phenylethanolamine-N-methyltransferase immunoreactivity present in the C1 and C2 cell groups; (e) a decay of neuropeptide Y immunoreactivity in the C1 and C2 groups, while the C3 group is unaffected by aging as evaluated by number of phenylethanolamine-N-methyltransferase- and neuropeptide Y-immunoreactive cell body profiles. These results indicate heterogeneities in the responses of the adrenaline-neuropeptide Y cell groups to the aging process. The possible functional consequences of aging-induced changes in the cardiovascular adrenergic neurons are discussed, especially in relation to development of hypertension.
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PMID:Morphometrical and microdensitometrical studies on phenylethanolamine-N-methyltransferase- and neuropeptide Y-immunoreactive neurons in the rostral medulla oblongata of the adult and old male rat. 317 85

The vascular extracellular matrix (ECM) plays an important role in the histopathology of cerebral microcirculation, but its characterization is still incomplete. For that reason we investigated paraffin-embedded and cryostat sections of intracerebral and meningeal vessels from eight normotensive and six hypertensive humans using monospecific affinity-purified polyclonal antibodies against human/monkey amino-terminal procollagen I + III peptide (P I P, P III P), collagen IV (7-S and NC1 domains), VI, and laminin (P 1 fragment) by applying peroxidase-antiperoxidase- and alkaline phosphatase-antialkaline phosphatase techniques. In normotensives, laminin and collagen IV were codistributed in the basal lamina of meningeal and intraparenchymal vessels. Collagen VI was only present in the adventitia of meningeal vessels and larger intraparenchymal arteries and veins, whereas it was absent from cortical vessels including capillaries. Intensive staining for collagen VI was observed in the choroid plexus, the superficial glia and sheath of cranial nerves. In hypertensives, the basement membrane constituents laminin and collagen IV appeared ubiquitously increased. Here, collagen VI was also deposited in the broadened vascular intima and media of larger arteries and in cortical vessels. In both groups collagen VI and P III P appeared to be codistributed. Our results indicate that significant qualitative change sin ECM of cerebral blood vessels are taking place during the development of hypertension, such as (1) an atypical deposition or an increase of collagen VI which by interconnecting collagen fibrils (I and III) might exert a stabilizing (sclerosing) function in the ECM, and (2) a thickening of vascular basement membranes caused by an accumulation of its major components laminin and collagen IV.
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PMID:Altered expression of collagen type VI in brain vessels of patients with chronic hypertension. A comparison with the distribution of collagen IV and procollagen III. 323 76

Acute hypertension may transiently open the blood-brain barrier (BBB). To determine whether such temporary exposure of the brain parenchyma to plasma constituents may lead to permanent morphological alterations, acute hypertension was induced by i.v. adrenaline in conscious rates given Evan's blue and horseradish peroxidase as tracers. The brain were perfused in situ 24 h later: 17 of 21 brains showed multifocal sites of extravasation of the tracers and of endogenous plasma albumin, fibrinogen and fibronectin identified by immunohistochemistry. The proteins spread locally in the parenchyma and were taken up by neurons. Within the leaking sites in the cortex, hippocampus, thalamus and basal ganglia some shrunken and grossly distorted acidophilic neurons were present. Focal areas of sponginess were observed in the subpial and subependymal zones. Thus, a transient opening of the BBB may lead to neuronal damage.
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PMID:Adrenaline-induced hypertension: morphological consequences of the blood-brain barrier disturbance. 341 76

This study examined physiological and histopathological changes in the cat produced by a new experimental fluid injury device. Spontaneously breathing (N = 14) and artificially ventilated (N = 45) cats were subjected to systemically varied magnitudes of fluid percussion brain injury. Within certain injury ranges, increasing magnitudes of fluid percussion injury produced increasing durations of apnea, as well as greater transient increases in mean arterial blood pressure, intracranial pressure and cerebral perfusion pressure. Acute increases in intracranial pressure may have been related to cerebral vasodilatation produced by the systemic hypertension following brain injury. Injuries associated with pressure transients greater than 10 atm ms produced concussive responses, including irreversible apnea in spontaneously breathing cats and temporary pupillary dilatation, increases in heart rate and mean arterial blood pressure in artificially ventilated cats. Injuries greater than 39 atm ms frequently produced histopathological and physiological indices of significant irreversible brain damage, including fixed and dilated pupils, systemic cardiovascular hypotension and deteriorating blood gases. Injury magnitudes less than 20 atm ms did not produce macroscopic evidence of histopathology, intermediate injury ranges produced increasing evidence of subarachnoid and petechial hemorrhage while injury levels greater than 40 atm ms frequently produced significant histopathology including massive hematomas. Injury greater than 10 atm ms resulted in opening of the blood-brain barrier, as assessed by extravasation of horseradish peroxidase. Injury greater than 19 atm ms produced suppression of EEG amplitudes which did not recover for up to 40 minutes after injury. These data provide detailed information on the physiological and histopathological consequences of fluid percussion injury in the cat and indicate that this modified fluid percussion apparatus can produce graded levels of brain injury similar to those previously reported for fluid percussion injury.
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PMID:A new model of concussive brain injury in the cat produced by extradural fluid volume loading: II. Physiological and neuropathological observations. 345 76

The effects of experimental subarachnoid hemorrhage (SAH) on the blood-arterial wall barrier in the major cerebral arteries were studied in 24 spontaneously hypertensive rats (SHR) and 13 Sprague-Dawley rats (SDR). Horseradish peroxidase (HRP) was given intravenously before killing the animals to assess the integrity of the barrier. In the acute experimental group, transient elevation of intracranial pressure (ICP) and systemic arterial pressure produced by cisternal injection of whole blood, saline solution, or Elliott's B solution resulted in extensive disturbance of the blood-arterial wall barrier. In the chronic group, only the cisternal injection of whole blood in SHR brought about an extensive and marked disturbance of the arterial permeability. These results suggest that: (a) early breakdown of the blood-arterial wall barrier seems to be due to a sudden rise in the ICP or arterial pressure; (b) in the chronic experiments, the subarachnoid clot is the most important factor responsible for the permeability changes; and (c) in the chronic SAH experiments, the blood-arterial wall barrier seems to be more vulnerable in SHR than in Sprague-Dawley rats. Due to the well-known similarities between SHRs and hypertensive human beings, patients with chronic hypertension should be considered at high risk after SAH for extensive blood-arterial wall barrier disturbances.
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PMID:Barrier disruption in the major cerebral arteries after experimental subarachnoid hemorrhage in spontaneously hypertensive and normotensive rats. 368 85

This study was undertaken to localize oligosaccharide residues on the endothelial luminal plasma membrane of cerebral vessels of normotensive animals and vessels permeable to horseradish peroxidase (HRP) in angiotensin-induced acute hypertension. Wistar-Furth rats were injected with HRP intravenously and hypertension was induced by an intravenous infusion of angiotensin amide. Animals were fixed 2.5, 10 and 15 min later and the HRP reaction product was demonstrated in brain slices, followed by lectin localization using the avidin-biotin-peroxidase method. Oligosaccharide residues demonstrable on the luminal plasma membrane of cerebral endothelium of normotensive controls and both permeable and nonpermeable vessels of hypertensive animals were: alpha-D-mannosyl, alpha-D-glucosyl, beta-N-acetylglucosaminyl, sialyl, beta-D-galactosyl, alpha-L-fucosyl and alpha-N-acetyl-D-galactosaminyl groups. Peanut agglutinin did not bind to the endothelium of normotensive controls or of nonpermeable vessels in hypertensive animals, but did bind to endothelium of vessels permeable to HRP 2.5 min after the onset of hypertension. At 10 min, the luminal plasma membrane of vessels regained their normal characteristics and peanut agglutinin binding was no longer demonstrable. Our studies suggest that increased cerebrovascular permeability to protein in acute hypertension is associated with loss of the terminal sialic acid groups on the luminal plasma membrane of permeable vessels. This results in the observed reduction of charge on the endothelium and an exposure of beta-D-gal-(1-3)-D-gal N-acetyl groups leads to binding of peanut agglutinin. Both alterations are rapidly reversible and no longer demonstrable 10 min after the onset of hypertension, when blood pressures reach resting levels and the blood-brain barrier is restored.
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PMID:Cerebral endothelial plasma membrane alterations in acute hypertension. 372 33

Cardiac rupture occurs in 10 per cent of patients who die with acute myocardial infarction, but the pathogenesis remains unclear. Twenty randomly selected patients with cardiac rupture were reviewed retrospectively at autopsy, and the findings were compared with those of 20 age- and sex-matched control subjects who had died of acute transmural myocardial infarction without rupture. The times from the onset of chest pain to death were similar in the two groups (5.7 +/- 5.8 days for patients with rupture versus 4.2 +/- 4.9 days for control subjects), and there were no differences in the incidences of systemic hypertension, diabetes mellitus, hypercholesterolemia, history of myocardial infarction, or angina pectoris. The severity of coronary atherosclerosis was different in the two groups, with 55 per cent of the patients with cardiac rupture having single-vessel disease and 70 per cent of the patients without cardiac rupture having disease in three vessels. Additionally, the incidence of thrombosis was greater in patients with cardiac rupture than in those without. The inflammatory cell response in each patient was quantitated microscopically (number and type of leukocytes) in ten high-power fields. The inflammatory response was greater in patients with cardiac rupture. The number of eosinophils in the inflammatory response was significantly (P less than 0.01) greater in hearts associated with cardiac rupture (29.5 +/- 4 per cent) than in control hearts (11.7 +/- 3.1 per cent). It is postulated that eosinophils rich in arylsulfatase B, peroxidase, glucuronidase, beta-glycerophosphatase, major basic protein, and eosinophilic cationic protein may further weaken the necrotic myocardium and, in part, determine whether acute myocardial infarction will eventually result in cardiac rupture.
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PMID:Association of eosinophils with cardiac rupture. 399 34

The site of action and the distribution of angiotensin II have been studied in the mouse. A comparison of the ratios of angiotensin-(14)C and inulin-(3)H at the time of the pressor effect reveals an extracellular pattern of distribution. Morphological studies were made using angiotensin coupled to exogenous enzymes which can be demonstrated histochemically. Coupling of angiotensin to horseradish peroxidase or cytochrome c, with glutaraldehyde or difluorodinitrodiphenylsulfone (FNPS) as the coupling agent, does not alter the pattern of its vasopressor response or that of its inactivation; nor are differences present between angiotensin and the angiotensin-enzyme complexes in the stimulation of in vitro tissue preparations. Dissociation of the complexes was shown not to occur in vitro, but the possibility of a serum factor splitting the complexes immediately after intravenous injection cannot be excluded. Since these complexes are localized on the endothelium and not on the smooth muscle at the time of maximum hypertension, the endothelium is proposed as the site of action for angiotensin.
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PMID:The cellular site of action of angiotensin. 432 16

The ultrastructure of retinal arterial vessels from rats with severe renal hypertension has been studied. The permeability of retinal vessels has also been examined by means of vascular labeling technics utilizing horseradish peroxidase and microperoxidase as tracer substances. Small retinal arteries and arterioles exhibit foci of smooth muscle necrosis characterized initially by fragmentation of medial smooth muscle cells, and subsequently by loss of myofilaments and release of free vesicles, vacuoles and other cytoplasmic organelles extracellularly. Evidence for increased permeability is observed occasionally in retinal capillaries and less frequently in arteries and arterioles. The enzymatic tracers penetrate the tight junctions of the endothelial cells and are found in the basement membranes adjacent to endothelial and smooth muscle cells, as well as in expanded extracellular spaces around the capillaries. The alterations in the ultrastructure and permeability of retinal vessels in experimental hypertension have been compared with that of visceral and cerebral cortical vessels.
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PMID:The cellular pathology of experimental hypertension. VI. Alterations in retinal vasculature. 508 Jul


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