摘要:

BackgroundThe formation of new blood vessels is an important process in embryonic development and in physiological repair processes. Abnormalities in blood vessel growth have been associated with various pathologies.Hypertension and impaired vascular growthThe basic observation underlying the hypothesis that essential hypertension is based on an impaired capacity for vascular growth is the nature of the structural alterations of microvascular beds in essential hypertension. Recent advances in understanding the molecular and cellular mechanisms of vascular growth suggest that the remodeling of individual vessels and vascular networks in hypertension may be a pathological variant of the formation of mature networks.Pathogenesis of impaired vascular growthGenetic and fetal influences appear to have significant effects in determining impaired vascular development as an early cause of essential hypertension.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo determine whether long-term very vigorous endurance training prevents hypertension.DesignCohort study of master orienteering runners and controls.SettingFinland.Subjects and methodsIn 1995, a health questionnaire was completed by 264 male orienteering runners (response rate 90.4%) who had been top-ranked in competitions among men aged 35–59 years in 1984, and by 388 similarly aged male controls (response rate 87.1%) who were healthy at the age of 20 years and free of overt ischemic heart disease in 1985.Main outcome measureSelf-report of medication for hypertension.ResultsIn the endurance athlete group, the crude prevalence (8.7%) of subjects who had used medication for hypertension was less than a third of that in the control group (27.8%). Even after adjusting for age and body mass index, the difference between the groups was still significant (odds ratio for athletes 0.43, 95% confidence interval 0.25–0.76).ConclusionsLong-term vigorous endurance training is associated with a low prevalence of hypertension. Some of the effect can be explained by a lower body mass, but exercise seems to induce a lower rate of hypertension by other mechanisms than by decreasing body weight.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundSeveral cross-sectional studies have reported a positive association between plasma fibrinogen levels and prevalent hypertension. Other studies have reported a positive association between hypertension and whole-blood or plasma viscosity, to which fibrinogen contributes. To our knowledge, there has been no prospective study of fibrinogen and incident hypertension.Subjects and methodsWe measured plasma fibrinogen levels in a population-based cohort study of middle-aged adults and related it to the occurrence of incident hypertension (systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg or use of antihypertensive medication) over 6 years.ResultsThere was a moderately strong positive association between fibrinogen levels and prevalent hypertension in both men and women, with the odds of hypertension elevated by 50% for the highest fibrinogen quartile versus the lowest. Among 7884 participants at risk, 1609 developed hypertension over 6 years. Adjusted for age, race, field center and baseline systolic blood pressure, the odds ratio of incident hypertension in relation to fibrinogen quartiles was 1.0, 1.07, 1.21 and 1.43 in men (P= 0.003 for trend) and 1.0, 0.92, 0.99 and 0.99 in women (P= 0.89 for trend). After adjustment for other risk factors, the odds ratios were 1.0, 1.03, 1.15 and 1.29 (P= 0.045 for trend) in men and remained nonsignificant in women.ConclusionsDespite a moderately strong positive association between fibrinogen levels and prevalent hypertension in both sexes, there was only a weak positive association between fibrinogen levels and incident hypertension in men and no association in women. Whether an elevated fibrinogen level is a risk factor for, or a consequence of, hypertension remains unclear.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveClinic blood pressure values are known to change according to seasonal influences. We therefore examined home and 24 h ambulatory blood pressure values to determine whether these measurements are also affected by the seasons.Design and methodsIn 2051 subjects of the Pressione Arteriose Monitorate E Loro Associazioni (PAMELA) study, we measured clinic (sphygmomanometric measurements), home (semi-automatic device) and ambulatory (Spacelabs 90207) systolic blood pressure, diastolic blood pressure and heart rate. Because the overall sample was evenly distributed over each month (except August), we were able to make a cross-sectional determination of whether the values differed between seasons. The corresponding heart rates were also evaluated.ResultsAs expected, summer was associated with the lowest clinic blood pressure and winter with the highest, and this was the case also for home and 24 h average blood pressure, although seasonal differences in the latter were less pronounced. Seasonal clinic, home and ambulatory blood pressure patterns were similar for normotensive subjects (n = 1152), untreated hypertensives (n = 540) and treated hypertensives (n = 359). Heart rate values did not differ by season.ConclusionsSeasonal influences on blood pressure are not limited to conventional measurements but characterize daily values as well. These effects are visible in both normal and elevated blood pressure values, regardless of the effect of antihypertensive drugs. This has implications both for the clinician and for studies aimed at evaluating the effects of antihypertensive treatment.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectivesTo study carotid and femoral intima–media thicknesses and diameters in relation to age, sex, morphologic status and blood pressure.ParticipantsThe subjects were 369 men and women (aged 10–54 years) from the Stanislas cohort, with no known cardiovascular disease.Methodsintima–media thicknesses and diameters were measured by B-mode ultrasonography. The effects of sex, age, smoking, anthropometric variables, cholesterol and blood pressure were studied using bivariate and regression analysis.ResultsCarotid and femoral intima–media thicknesses were not affected by age nor by sex up to 18 years of age. Thereafter, they increased sharply in men and remained higher than in women. Values were correlated with systolic blood pressure only in men, and with fat-free mass in children and young adults only at the femoral site. Smoking, body mass index and fat mass were associated with intima–media thicknesses only in adults. Carotid diameter was little affected by age during childhood and in adults. Femoral diameter increased up to the age of 18 in both sexes and remained unaffected by age thereafter. This increase was more pronounced in boys, and so values became consistently greater in males aged over 14 years. Carotid diameter was correlated with body mass index or fat mass whereas femoral diameter was correlated with weight or fat-freemass in children and men. The opposite was observed in women.ConclusionSex differences occur before adolescence for arterial diameter, but only at an adult age for intima–media thickness. In young subjects, carotid geometry seems to be influenced by blood pressure and excess body weight, while femoral artery geometry seems to be related to blood pressure and body growth.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveThe purpose of this study was to assess the role of transforming growth factor (TGF)-β1in the development of diabetes-associated mesenteric vascular hypertrophy and in the antitrophic effect of angiotensin converting enzyme inhibitors.Design and methodsStreptozotocin-induced diabetic and control Sprague–Dawley rats were randomly allocated to treatment with the angiotensin converting enzyme inhibitor ramipril or to no treatment and were killed 1 or 3 weeks after the streptozotocin injection. Blood was collected and mesenteric vessels removed. Mesenteric vascular weight was measured and TGF-β1and α1(type IV) collagen messenger (m)RNA levels were analysed by Northern analysis. Immunohistochemical analyses for TGF-β1and type IV collagen were also performed.ResultsThe diabetic rats had increased mesenteric vessel weight at 3 weeks but not at 1 week and a concomitant rise in mesenteric TGF-β1and in α1(type IV) collagen mRNA levels. Ramipril treatment attenuated mesenteric vessel hypertrophy and prevented the increase in TGF-β1and α1(type IV) collagen mRNA levels after 3 weeks of diabetes. The immunohistochemical analysis revealed that diabetes was associated with increased TGF-β1and type IV collagen protein and extracellular matrix accumulation in mesenteric vessels, and this increase was reduced by ramipril treatment.ConclusionsThese results support the concept that TGF-β is involved in the changes associated with diabetic vascular disease, and suggest a mechanism by which angiotensin converting enzyme inhibitors exert their antitrophic effects.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo determine whether the abnormal vascular responses observed in salt-sensitive hypertension are caused by an impairment in vascular nitric oxide function.DesignIsometric tension was measured in aortic rings isolated from Dahl salt-sensitive and salt-resistant rats fed a regular-salt (0.4% NaCl) or a high-salt (8% NaCl) diet, with and without inhibition of endogenous nitric oxide synthesis.Methods and resultsSystolic arterial pressure, measured weekly by the tail-cuff method, increased markedly in DS rats with a high-salt diet but did not increase in the other groups. In aortic rings, norepinephrine evoked dose-dependent contractions which were significantly increased in rings from DS rats with a high-salt diet. Pretreatment with Nω-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, increased the norepinephrine-induced contraction in all groups and abolished differences in contractile responses between high-salt DS rats and the other groups. Acetylcholine induced endothelium-dependent relaxation, which was significantly depressed in high-salt DS rats. L-NAME attenuated the acetylcholine-induced relaxation in all groups and abolished the difference in relaxation response between high-salt DS rats and the other groups. Sodium nitroprusside-induced relaxation was significantly depressed in high-salt DS rats.ConclusionsVascular hypercontractile responses to norepinephrine in DS hypertensive rats can, in part, be explained by an impairment in endothelial nitric oxide production.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BackgroundThe relative contribution of the various hemodynamic and metabolic mechanisms leading to endothelial dysfunction may be different in specific vascular diseases. Since shear stress is one of the main mechanical stimuli of endothelial cells, the aim of this study was to investigate its contribution to endothelial dysfunction in two distinct vascular diseases, hypertension and type II diabetes.Subjects and methodsWe measured the radial artery diameter at baseline, after ischemic vasodilation and after nitroglycerin vasodilation in 16 untreated patients with high blood pressure, in 15 type II normotensive diabetic patients and in 17 healthy controls. Wall shear stress was evaluated by simultaneous measurements of whole blood viscosity and blood flow velocity.ResultsIn diabetic patients, whole blood viscosity was significantly higher whereas wall shear stress was similar compared to controls. In hypertensive patients, whole blood viscosity was higher and wall shear stress was lower than in controls. Endothelium-dependent vasodilation was impaired in both hypertensive and diabetic patients (P< 0.01) after adjustment for age, sex, body mass index and postnitroglycerin vasodilation. When adjustments were made for maximal systolic shear stress, endothelium-dependent vasodilation remained lower in the diabetic patients (P< 0.01), but not in those with high blood pressure compared to controls.ConclusionsIn hypertension, endothelium-dependent vasodilation is mainly due to a chronic decrease in shear stress (the most important physiological stimulus of the endothelial cells) with no major intrinsic endothelial cell dysfunction. In contrast, in diabetics, the lower endothelium-dependent vasodilation was not the result of an altered shear stress.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

AimMutations of the 11β-hydroxysteroid dehydrogenase type 2(11β-HSD2)gene cause the syndrome of apparent mineralocorticoid excess, a rare autosomal recessive form of hypertension. We therefore investigated the question of whether variants of the11β-HSD2gene can contribute to genetic susceptibility to essential hypertension.Subjects and methodsWe performed a linkage study in 162 French hypertensive sibships using the affected sib-pair method on 347 sibling pairs and a polymorphic microsatellite marker that we identified in a 30 kb cosmid clone containing the11β-HSD2gene. The coding sequence, introns 2–4 and 350 bp of the 5′-flanking region of the11β-HSD2gene were screened for polymorphisms by polymerase chain reaction/single-strand conformation polymorphism, and a single polymorphism,Glu178/Glu(G534A), was identified in exon 3, which did not change the encoded amino acid sequence. A case–control study was conducted on 370 hypertensive subjects with a positive family history of hypertension and 783 French subjects with hypertension with or without a family history of hypertension, compared with 313 normotensive control subjects, all of whom were analyzed for the newly identified bi-allelic polymorphism.ResultsStatistical analyses using the affected sib-pair method did not show significant linkage between the11β-HSD2microsatellite marker and hypertension. Furthermore, no positive association with hypertension was found with theGlu178/Glu(G534A) polymorphism.ConclusionOur data do not suggest that variants of the11β-HSD2gene contribute substantially to essential hypertension in Caucasians.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ObjectiveTo determine the value of the supine heart rate as a marker of sympathetic tone by assessing, in a large group of subjects, the relationships between this parameter and two other indices of sympathetic activity, plasma norepinephrine and sympathetic nerve traffic.Patients and methodsWe studied 243 subjects aged 50.0 ± 12.1 years (mean ± SD). Of these, 38 were normotensive healthy controls, 113 subjects had untreated essential hypertension, 27 were obese normotensives and 65 had congestive heart failure. In each subject, over a 10 min supine period, we measured mean arterial pressure (Finapres), heart rate (electrocardiogram), venous plasma norepinephrine (high-performance liquid chromatography) and efferent postganglionic muscle sympathetic nerve activity (microneurography at a peroneal nerve).ResultsIn the whole study group, supine heart rate was correlated with both plasma norepinephrine (r= 0.32,P< 0.0001) and muscle sympathetic nerve activity (r= 0.38,P< 0.0001). This was also the case in the normotensive obese subjects and the heart failure subjects considered separately. Heart rate values were greater in the obese and the heart failure patients than in controls (75.1 ± 13.0 and 78.2 ± 13.0 versus 69.2 ± 11.6 beats/min;P< 0.05 andP< 0.001, respectively), as were plasma norepinephrine (362.7 ± 202 and 400.3 ± 217 versus 230.4 ± 126 pg/ml;P< 0.01 andP< 0.001, respectively) and muscle sympathetic nerve activity (44.1 ± 14.7 and 55.3 ± 14.3 versus 27.8 ± 11.0 bursts/min;P< 0.001 for both). In contrast, in the essential hypertensive subjects, no significant relationship was found between these three indices of sympathetic activity. Furthermore, in the hypertensives, the heart rate was not increased, at variance with the sympathetic nerve traffic, which was greater than in controls (36.2 ± 10.0 versus 27.8 ± 11.0 bursts/min,P< 0.001).ConclusionsThese data suggest that the supine heart rate can be regarded as a marker of intersubject differences in sympathetic tone, and that this is the case both in the general population and in those with cardiovascular diseases. Its value for this purpose is limited, however, and the limitations may be more evident in essential hypertension than in conditions such as obesity and heart failure.

ISSN:0263-6352    

出版商:OVID    

年代:1998

数据来源: OVID