1. |
- Alvarez-Madrazo, S., et al.
(author)
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Common Polymorphisms in the CYP11B1 and CYP11B2 Genes: Evidence for a Digenic Influence on Hypertension
- 2013
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In: Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0194-911X .- 1524-4563. ; 61:1, s. 232-239
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Journal article (peer-reviewed)abstract
- The locus encompassing the corticosteroidogenic genes CYP11B2 and CYP11B1 is of potential importance in essential hypertension. We analyzed the association of polymorphisms at this locus with risk of essential hypertension, using 2 white case-control collections for discovery (n = 3340) and confirmation (n = 2929). Single-marker and haplotype analyses were performed, with the CYP11B2 Intron 2 Conversion polymorphism showing strongest association with hypertension in both cohorts and in combined analysis (odds ratio = 1.16, P = 8.54x10(-5)). The CYP11B1 ACA haplotype associated with increased risk of hypertension relative to the alternative, GTC (odds ratio = 1.11; P = 7.4x10(-3)), whereas the CYP11B2 TWtC haplotype seemed protective relative to the contrasting CConvT (odds ratio = 0.88, P = 2.2x10(-3)). Analysis spanning the whole CYP11B1/CYP11B2 locus showed that haplotypes associated with raised risk of hypertension tend to coexist. Functional analysis of heterozygous human adrenal tissue demonstrated decreased CYP11B2 expression and increased CYP11B1 expression for those alleles associating with reduced risk of hypertension. These results confirm the hypertensive influence of this locus, with data suggesting a complex digenic mechanism whereby altered relative CYP11B1 and CYP11B2 gene expression could have a chronic effect on enzyme activity and corticosteroid synthesis.
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2. |
- Asayama, Kei, et al.
(author)
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Setting Thresholds to Varying Blood Pressure Monitoring Intervals Differentially Affects Risk Estimates Associated With White-Coat and Masked Hypertension in the Population
- 2014
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In: Hypertension. - 0194-911X .- 1524-4563. ; 64:5, s. 935-942
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Journal article (peer-reviewed)abstract
- Outcome-driven recommendations about time intervals during which ambulatory blood pressure should be measured to diagnose white-coat or masked hypertension are lacking. We cross-classified 8237 untreated participants (mean age, 50.7 years; 48.4% women) enrolled in 12 population studies, using >= 140/>= 90, >= 130/>= 80, >= 135/>= 85, and >= 120/>= 70 mm Hg as hypertension thresholds for conventional, 24-hour, daytime, and nighttime blood pressure. White-coat hypertension was hypertension on conventional measurement with ambulatory normotension, the opposite condition being masked hypertension. Intervals used for classification of participants were daytime, nighttime, and 24 hours, first considered separately, and next combined as 24 hours plus daytime or plus nighttime, or plus both. Depending on time intervals chosen, white-coat and masked hypertension frequencies ranged from 6.3% to 12.5% and from 9.7% to 19.6%, respectively. During 91 046 person-years, 729 participants experienced a cardiovascular event. In multivariable analyses with normotension during all intervals of the day as reference, hazard ratios associated with white-coat hypertension progressively weakened considering daytime only (1.38; P=0.033), nighttime only (1.43; P=0.0074), 24 hours only (1.21; P=0.20), 24 hours plus daytime (1.24; P=0.18), 24 hours plus nighttime (1.15; P=0.39), and 24 hours plus daytime and nighttime (1.16; P=0.41). The hazard ratios comparing masked hypertension with normotension were all significant (P<0.0001), ranging from 1.76 to 2.03. In conclusion, identification of truly low-risk white-coat hypertension requires setting thresholds simultaneously to 24 hours, daytime, and nighttime blood pressure. Although any time interval suffices to diagnose masked hypertension, as proposed in current guidelines, full 24-hour recordings remain standard in clinical practice.
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3. |
- Bakris, George L, et al.
(author)
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Divergent results using clinic and ambulatory blood pressures report of a darusentan-resistant hypertension trial
- 2010
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In: Hypertension. - 0194-911X .- 1524-4563. ; 56:5, s. 824-830
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Journal article (peer-reviewed)abstract
- Patients with resistant hypertension are at increased risk for cardiovascular events. The addition of new treatments to existing therapies will help achieve blood pressure (BP) goals in more resistant hypertension patients. In the current trial, 849 patients with resistant hypertension receiving ≥3 antihypertensive drugs, including a diuretic, at optimized doses were randomized to the selective endothelin A receptor antagonist darusentan, placebo, or the central α-2 agonist guanfacine. The coprimary end points of the study were changes from baseline to week 14 in trough, sitting systolic BP, and diastolic BP measured in the clinic. Decreases from baseline to week 14 in systolic BP for darusentan (−15±14 mm Hg) were greater than for guanfacine (−12±13 mm Hg; P<0.05) but not greater than placebo (−14±14 mm Hg). Darusentan, however, reduced mean 24-hour systolic BP (−9±12 mm Hg) more than placebo (−2±12 mm Hg) or guanfacine (−4±12 mm Hg) after 14 weeks of treatment (P<0.001 for each comparison). The most frequent adverse event associated with darusentan was fluid retention/edema at 28% versus 12% in each of the other groups. More patients withdrew because of adverse events on darusentan as compared with placebo or guanfacine. We conclude that darusentan provided greater reduction in systolic BP in resistant hypertension patients as assessed by ambulatory BP monitoring, in spite of not meeting its coprimary end points. The results of this trial highlight the importance of ambulatory BP monitoring in the design of hypertension clinical studies.
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4. |
- Barnes, J. N., et al.
(author)
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Aging enhances autonomic support of blood pressure in women
- 2014
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In: Hypertension. - 0194-911X .- 1524-4563. ; 63:2, s. 303-308
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Journal article (peer-reviewed)abstract
- The autonomic nervous system plays a central role in both acute and chronic blood pressure regulation in humans. The activity of the sympathetic branch of the autonomic nervous system is positively associated with peripheral resistance, an important determinant of mean arterial pressure in men. In contrast, there is no association between sympathetic nerve activity and peripheral resistance in women before menopause, yet a positive association after menopause. We hypothesized that autonomic support of blood pressure is higher after menopause in women. We examined the effect of ganglionic blockade on arterial blood pressure and how this relates to baseline muscle sympathetic nerve activity in 12 young (25±1 years) and 12 older postmenopausal (61±2 years) women. The women were studied before and during autonomic blockade using trimethaphan camsylate. At baseline, muscle sympathetic nerve activity burst frequency and burst incidence were higher in the older women (33±3 versus 15±1 bursts/min; 57±5 versus 25±2 bursts/100 heartbeats, respectively; P<0.05). Muscle sympathetic nerve activity bursts were abolished by trimethaphan within minutes. Older women had a greater decrease in mean arterial pressure (-29±2 versus-9±2 mm Hg; P<0.01) and total peripheral resistance (-10±1 versus-5±1 mm Hg/L per minute; P<0.01) during trimethaphan. Baseline muscle sympathetic nerve activity was associated with the decrease in mean arterial pressure during trimethaphan (r=-0.74; P<0.05). In summary, our results suggest that autonomic support of blood pressure is greater in older women compared with young women and that elevated sympathetic nerve activity in older women contributes importantly to the increased incidence of hypertension after menopause. © 2013 American Heart Association, Inc.
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5. |
- Boggia, Jose, et al.
(author)
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Ambulatory Blood Pressure Monitoring in 9357 Subjects From 11 Populations Highlights Missed Opportunities for Cardiovascular Prevention in Women
- 2011
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In: Hypertension. - 0194-911X .- 1524-4563. ; 57:3, s. 397-405
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Journal article (peer-reviewed)abstract
- To analyze sex-specific relative and absolute risks associated with blood pressure (BP), we performed conventional and 24-hour ambulatory BP measurements in 9357 subjects (mean age, 52.8 years; 47% women) recruited from 11 populations. We computed standardized multivariable-adjusted hazard ratios for associations between outcome and systolic BP. During a course of 11.2 years (median), 1245 participants died, 472 of cardiovascular causes. The number of fatal combined with nonfatal events was 1080, 525, and 458 for cardiovascular and cardiac events and for stroke, respectively. In women and men alike, systolic BP predicted outcome, irrespective of the type of BP measurement. Women compared with men were at lower risk (hazard ratios for death and all cardiovascular events=0.66 and 0.62, respectively; P<0.001). However, the relation of all cardiovascular events with 24-hour BP (P=0.020) and the relations of total mortality (P=0.023) and all cardiovascular (P=0.0013), cerebrovascular (P=0.045), and cardiac (P=0.034) events with nighttime BP were steeper in women than in men. Consequently, per a 1-SD decrease, the proportion of potentially preventable events was higher in women than in men for all cardiovascular events (35.9% vs 24.2%) in relation to 24-hour systolic BP (1-SD, 13.4 mm Hg) and for all-cause mortality (23.1% vs 12.3%) and cardiovascular (35.1% vs 19.4%), cerebrovascular (38.3% vs 25.9%), and cardiac (31.0% vs 16.0%) events in relation to systolic nighttime BP (1-SD, 14.1 mm Hg). In conclusion, although absolute risks associated with systolic BP were lower in women than men, our results reveal a vast and largely unused potential for cardiovascular prevention by BP-lowering treatment in women.
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6. |
- Boggia, Jose, et al.
(author)
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Risk Stratification by 24-Hour Ambulatory Blood Pressure and Estimated Glomerular Filtration Rate in 5322 Subjects From 11 Populations
- 2013
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In: Hypertension. - 0194-911X .- 1524-4563. ; 61:1, s. 18-
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Journal article (peer-reviewed)abstract
- No previous study addressed whether in the general population estimated glomerular filtration rate (eGFR [Chronic Kidney Disease Epidemiology Collaboration formula]) adds to the prediction of cardiovascular outcome over and beyond ambulatory blood pressure. We recorded health outcomes in 5322 subjects (median age, 51.8 years; 43.1% women) randomly recruited from 11 populations, who had baseline measurements of 24-hour ambulatory blood pressure (ABP(24)) and eGFR. We computed hazard ratios using multivariable-adjusted Cox regression. Median follow-up was 9.3 years. In fully adjusted models, which included both ABP(24) and eGFR, ABP(24) predicted (P <= 0.008) both total (513 deaths) and cardiovascular (206) mortality; eGFR only predicted cardiovascular mortality (P=0.012). Furthermore, ABP(24) predicted (P <= 0.0056) fatal combined with nonfatal events as a result of all cardiovascular causes (555 events), cardiac disease (335 events), or stroke (218 events), whereas eGFR only predicted the composite cardiovascular end point and stroke (P <= 0.035). The interaction terms between ABP(24) and eGFR were all nonsignificant (P >= 0.082). For cardiovascular mortality, the composite cardiovascular end point, and stroke, ABP(24) added 0.35%, 1.17%, and 1.00% to the risk already explained by cohort, sex, age, body mass index, smoking and drinking, previous cardiovascular disease, diabetes mellitus, and antihypertensive drug treatment. Adding eGFR explained an additional 0.13%, 0.09%, and 0.14%, respectively. Sensitivity analyses stratified for ethnicity, sex, and the presence of hypertension or chronic kidney disease (eGFR <60mL/min per 1.73 m(2)) were confirmatory. In conclusion, in the general population, eGFR predicts fewer end points than ABP(24). Relative to ABP(24), eGFR is as an additive, not a multiplicative, risk factor and refines risk stratification 2-to14-fold less.
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7. |
- Carlsson, Axel C, et al.
(author)
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Association Between Circulating Endostatin, Hypertension Duration, and Hypertensive Target-Organ Damage
- 2013
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In: Hypertension. - : Lippincott Williams & Wilkins. - 0194-911X .- 1524-4563. ; 62:6, s. 1146-1151
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Journal article (peer-reviewed)abstract
- Our aim is to study associations between circulating endostatin, hypertension duration, and hypertensive target-organ damage. Long-term hypertension induces cardiovascular and renal remodeling. Circulating endostatin, a biologically active derivate of collagen XVIII, has been suggested to be a relevant marker for extracellular matrix turnover and remodeling in various diseases. However, the role of endostatin in hypertension and hypertensive target-organ damage is unclear. Serum endostatin was measured in 2 independent community-based cohorts: the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS; women 51%; n=812; mean age, 75 years) and the Uppsala Longitudinal Study of Adult Men (ULSAM; n=785; mean age, 77.6 years). Retrospective data on blood pressure measurements and antihypertensive medication (PIVUS >5 years, ULSAM >27 years), and cross-sectional data on echocardiographic left ventricular mass, endothelial function (endothelium-dependent vasodilation assessed by the invasive forearm model), and urinary albumin/creatinine ratio were available. In PIVUS, participants with 5 years of history of hypertension portrayed 0.42 SD (95% confidence interval, 0.23-0.61; P<0.001) higher serum endostatin, compared with that of normotensives. This association was replicated in ULSAM, in which participants with 27 years hypertension duration had the highest endostatin (0.57 SD higher; 95% confidence interval, 0.35-0.80; P<0.001). In addition, higher endostatin was associated with higher left ventricular mass, worsened endothelial function, and higher urinary albumin/creatinine ratio (P<0.03 for all) in participants with prevalent hypertension. Circulating endostatin is associated with the duration of hypertension, and vascular, myocardial, and renal indices of hypertensive target-organ damage. Further studies are warranted to assess the prognostic role of endostatin in individuals with hypertension.
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8. |
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9. |
- Carlström, Mattias, et al.
(author)
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Superoxide Dismutase 1 Limits Renal Microvascular Remodeling and Attenuates Arteriole and Blood Pressure Responses to Angiotensin II via Modulation of Nitric Oxide Bioavailability
- 2010
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In: Hypertension. - 0194-911X .- 1524-4563. ; 56:5, s. 907-913
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Journal article (peer-reviewed)abstract
- Oxidative stress is associated with vascular remodeling and increased preglomerular resistance that are both implicated in the pathogenesis of renal and cardiovascular disease. Angiotensin II induces superoxide production, which is metabolized by superoxide dismutase (SOD) or scavenged by NO. We investigated the hypothesis that SOD1 regulates renal microvascular remodeling, blood pressure, and arteriolar responsiveness and sensitivity to angiotensin II using SOD1-transgenic (SOD1-tg) and SOD1-knockout (SOD1-ko) mice. Blood pressure, measured telemetrically, rose more abruptly during prolonged angiotensin II infusion in SOD1-ko mice. The afferent arteriole media: lumen ratios were reduced in SOD1-tg and increased in SOD1-ko mice. Afferent arterioles from nontreated wild types had graded contraction to angiotensin II (sensitivity: 10(-9) mol/L; responsiveness: 40%). Angiotensin II contractions were less sensitive (10(-8) mol/L) and responsive (14%) in SOD1-tg but more sensitive (10(-13) mol/L) and responsive (89%) in SOD1-ko mice. Arterioles from SOD1-ko had 4-fold increased superoxide formation with angiotensin II at 10(-9) mol/L. N-G-nitro-L-arginine methyl ester reduced arteriole diameter of SOD1-tg and enhanced angiotensin II sensitivity and responsiveness of wild-type and SOD1-tg mice to the level of SOD1-ko mice. SOD mimetic treatment with Tempol increased arteriole diameter and normalized the enhanced sensitivity and responsiveness to angiotensin II of SOD1-ko mice but did not affect wild-type or SOD1-tg mice. Neither SOD1 deficiency nor overexpression was associated with changes in nitrate/nitrite excretion or renal mRNA expression of NO synthase, NADPH oxidase, or SOD2/SOD3 isoforms and angiotensin II receptors. In conclusion, SOD1 limits afferent arteriole remodeling and reduces sensitivity and responsiveness to angiotensin II by reducing superoxide and maintaining NO bioavailability. This may prevent an early and exaggerated blood pressure response to angiotensin II.
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10. |
- Conen, David, et al.
(author)
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Age-Specific Differences Between Conventional and Ambulatory Daytime Blood Pressure Values
- 2014
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In: Hypertension. - 0194-911X .- 1524-4563. ; 64:5, s. 1073-1079
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Journal article (peer-reviewed)abstract
- Mean daytime ambulatory blood pressure (BP) values are considered to be lower than conventional BP values, but data on this relation among younger individuals <50 years are scarce. Conventional and 24-hour ambulatory BP were measured in 9550 individuals not taking antihypertensive treatment from 13 population-based cohorts. We compared individual differences between daytime ambulatory and conventional BP according to 10-year age categories. Age-specific prevalences of white coat and masked hypertension were calculated. Among individuals aged 18 to 30, 30 to 40, and 40 to 50 years, mean daytime BP was significantly higher than the corresponding conventional BP (6.0, 5.2, and 4.7 mm Hg for systolic; 2.5, 2.7, and 1.7 mm Hg for diastolic BP; all P<0.0001). In individuals aged 60 to 70 and >= 70 years, conventional BP was significantly higher than daytime ambulatory BP (5.0 and 13.0 mm Hg for systolic; 2.0 and 4.2 mm Hg for diastolic BP; all P<0.0001). The prevalence of white coat hypertension exponentially increased from 2.2% to 19.5% from those aged 18 to 30 years to those aged >= 70 years, with little variation between men and women (8.0% versus 6.1%; P=0.0003). Masked hypertension was more prevalent among men (21.1% versus 11.4%; P<0.0001). The age-specific prevalences of masked hypertension were 18.2%, 27.3%, 27.8%, 20.1%, 13.6%, and 10.2% among men and 9.0%, 9.9%, 12.2%, 11.9%, 14.7%, and 12.1% among women. In conclusion, this large collaborative analysis showed that the relation between daytime ambulatory and conventional BP strongly varies by age. These findings may have implications for diagnosing hypertension and its subtypes in clinical practice.
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11. |
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12. |
- Finckenberg, Piet, et al.
(author)
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Caloric restriction ameliorates angiotensin II-induced mitochondrial remodeling and cardiac hypertrophy
- 2012
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In: Hypertension. - : Lippincott Williams & Wilkins. - 0194-911X .- 1524-4563. ; 59:1, s. 76-84
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Journal article (peer-reviewed)abstract
- Angiotensin II-induced cardiac damage is associated with oxidative stress-dependent mitochondrial dysfunction. Caloric restriction (CR), a dietary regimen that increases mitochondrial activity and cellular stress resistance, could provide protection. We tested that hypothesis in double transgenic rats harboring human renin and angiotensinogen genes (dTGRs). CR (60% of energy intake for 4 weeks) decreased mortality in dTGRs. CR ameliorated angiotensin II-induced cardiomyocyte hypertrophy, vascular inflammation, cardiac damage and fibrosis, cardiomyocyte apoptosis, and cardiac atrial natriuretic peptide mRNA overexpression. The effects were blood pressure independent and were linked to increased endoplasmic reticulum stress, autophagy, serum adiponectin level, and 5' AMP-activated protein kinase phosphorylation. CR decreased cardiac p38 phosphorylation, nitrotyrosine expression, and serum insulin-like growth factor 1 levels. Mitochondria from dTGR hearts showed clustered mitochondrial patterns, decreased numbers, and volume fractions but increased trans-sectional areas. All of these effects were reduced in CR dTGRs. Mitochondrial proteomic profiling identified 43 dTGR proteins and 42 Sprague-Dawley proteins, of which 29 proteins were in common in response to CR. We identified 7 proteins in CR dTGRs that were not found in control dTGRs. In contrast, 6 mitochondrial proteins were identified from dTGRs that were not detected in any other group. Gene ontology annotations with the Panther protein classification system revealed downregulation of cytoskeletal proteins and enzyme modulators and upregulation of oxidoreductase activity in dTGRs. CR provides powerful, blood pressure-independent, protection against angiotensin II-induced mitochondrial remodeling and cardiac hypertrophy. The findings support the notion of modulating cardiac bioenergetics to ameliorate angiotensin II-induced cardiovascular complications.
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13. |
- Franklin, Stanley S., et al.
(author)
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Masked Hypertension in Diabetes Mellitus Treatment Implications for Clinical Practice
- 2013
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In: Hypertension. - 0194-911X .- 1524-4563. ; 61:5, s. 964-
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Journal article (peer-reviewed)abstract
- Although distinguishing features of masked hypertension in diabetics are well known, the significance of antihypertensive treatment on clinical practice decisions has not been fully explored. We analyzed 9691 subjects from the population-based 11-country International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcomes. Prevalence of masked hypertension in untreated normotensive participants was higher (P<0.0001) among 229 diabetics (29.3%, n=67) than among 5486 nondiabetics (18.8%, n=1031). Over a median of 11.0 years of follow-up, the adjusted risk for a composite cardiovascular end point in untreated diabetic-masked hypertensives tended to be higher than in normotensives (hazard rate [HR], 1.96; 95% confidence interval [CI], 0.97-3.97; P=0.059), similar to untreated stage 1 hypertensives (HR, 1.07; CI, 0.58-1.98; P=0.82), but less than stage 2 hypertensives (HR, 0.53; CI, 0.29-0.99; P=0.048). In contrast, cardiovascular risk was not significantly different in antihypertensive-treated diabetic-masked hypertensives, as compared with the normotensive comparator group (HR, 1.13; CI, 0.54-2.35; P=0.75), stage 1 hypertensives (HR, 0.91; CI, 0.49-1.69; P=0.76), and stage 2 hypertensives (HR, 0.65; CI, 0.35-1.20; P=0.17). In the untreated diabetic-masked hypertensive population, mean conventional systolic/diastolic blood pressure was 129.2 +/- 8.0/76.0 +/- 7.3 mm Hg, and mean daytime systolic/diastolic blood pressure 141.5 +/- 9.1/83.7 +/- 6.5 mm Hg. In conclusion, masked hypertension occurred in 29% of untreated diabetics, had comparable cardiovascular risk as stage 1 hypertension, and would require considerable reduction in conventional blood pressure to reach daytime ambulatory treatment goal. Importantly, many hypertensive diabetics when receiving antihypertensive therapy can present with normalized conventional and elevated ambulatory blood pressure that mimics masked hypertension.
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14. |
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15. |
- Franklin, Stanley S., et al.
(author)
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Significance of White-Coat Hypertension in Older Persons With Isolated Systolic Hypertension : A Meta-Analysis Using the International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes Population
- 2012
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In: Hypertension. - 0194-911X .- 1524-4563. ; 59:3, s. 564-571
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Journal article (peer-reviewed)abstract
- The significance of white-coat hypertension in older persons with isolated systolic hypertension remains poorly understood. We analyzed subjects from the population-based 11-country International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes database who had daytime ambulatory blood pressure (BP; ABP) and conventional BP (CBP) measurements. After excluding persons with diastolic hypertension by CBP (>= 90 mm Hg) or by daytime ABP (>= 85 mm Hg), a history of cardiovascular disease, and persons<18 years of age, the present analysis totaled 7295 persons, of whom 1593 had isolated systolic hypertension. During a median follow-up of 10.6 years, there was a total of 655 fatal and nonfatal cardiovascular events. The analyses were stratified by treatment status. In untreated subjects, those with white-coat hypertension (CBP >= 140/<90 mm Hg and ABP<135/<85 mm Hg) and subjects with normal BP (CBP<140/<90 mm Hg and ABP<135/<85 mm Hg) were at similar risk (adjusted hazard rate: 1.17 [95% CI: 0.87-1.57]; P=0.29). Furthermore, in treated subjects with isolated systolic hypertension, the cardiovascular risk was similar in elevated conventional and normal daytime systolic BP as compared with those with normal conventional and normal daytime BPs (adjusted hazard rate: 1.10 [95% CI: 0.79-1.53]; P = 0.57). However, both treated isolated systolic hypertension subjects with white-coat hypertension (adjusted hazard rate: 2.00; [95% CI: 1.43-2.79]; P<0.0001) and treated subjects with normal BP (adjusted hazard rate: 1.98 [95% CI: 1.49-2.62]; P<0.0001) were at higher risk as compared with untreated normotensive subjects. In conclusion, subjects with sustained hypertension who have their ABP normalized on antihypertensive therapy but with residual white-coat effect by CBP measurement have an entity that we have termed, "treated normalized hypertension." Therefore, one should be cautious in applying the term "white-coat hypertension" to persons receiving antihypertensive treatment.
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16. |
- Friederich-Persson, M., et al.
(author)
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Kidney Hypoxia, Attributable to Increased Oxygen Consumption, Induces Nephropathy Independently of Hyperglycemia and Oxidative Stress
- 2013
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In: Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0194-911X .- 1524-4563. ; 62:5, s. 914-919
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Journal article (peer-reviewed)abstract
- Diabetic nephropathy is strongly associated with both increased oxidative stress and kidney tissue hypoxia. The increased oxidative stress causes increased kidney oxygen consumption resulting in kidney tissue hypoxia. To date, it has been difficult to determine the role of kidney hypoxia, per se, for the development of nephropathy. We tested the hypothesis that kidney hypoxia, without confounding factors such as hyperglycemia or elevated oxidative stress, results in nephropathy. To induce kidney hypoxia, dinitrophenol (30 mg per day per kg bodyweight by gavage), a mitochondrial uncoupler that increases oxygen consumption and causes kidney hypoxia, was administered for 30 consecutive days to rats. Thereafter, glomerular filtration rate, renal blood flow, kidney oxygen consumption, kidney oxygen tension, kidney concentrations of glucose and glycogen, markers of oxidative stress, urinary protein excretion, and histological findings were determined and compared with vehicle-treated controls. Dinitrophenol did not affect arterial blood pressure, renal blood flow, glomerular filtration rate, blood glucose, or markers of oxidative stress but increased kidney oxygen consumption, and reduced cortical and medullary concentrations of glucose and glycogen, and resulted in intrarenal tissue hypoxia. Furthermore, dinitrophenol treatment increased urinary protein excretion, kidney vimentin expression, and infiltration of inflammatory cells. In conclusion, increased mitochondrial oxygen consumption results in kidney hypoxia and subsequent nephropathy. Importantly, these results demonstrate that kidney tissue hypoxia, per se, without confounding hyperglycemia or oxidative stress, may be sufficient to initiate the development of nephropathy and therefore demonstrate a new interventional target for treating kidney disease.
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17. |
- Friederich-Persson, Malou, et al.
(author)
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Kidney Hypoxia, Attributable to Increased Oxygen Consumption, Induces Nephropathy Independently of Hyperglycemia and Oxidative Stress
- 2013
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In: Hypertension. - : American Heart Association. - 0194-911X .- 1524-4563. ; 62:5, s. 914-919
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Journal article (peer-reviewed)abstract
- Diabetic nephropathy is strongly associated with both increased oxidative stress and kidney tissue hypoxia. The increased oxidative stress causes increased kidney oxygen consumption resulting in kidney tissue hypoxia. To date, it has been difficult to determine the role of kidney hypoxia, per se, for the development of nephropathy. We tested the hypothesis that kidney hypoxia, without confounding factors such as hyperglycemia or elevated oxidative stress, results in nephropathy. To induce kidney hypoxia, dinitrophenol (30 mg per day per kg bodyweight by gavage), a mitochondrial uncoupler that increases oxygen consumption and causes kidney hypoxia, was administered for 30 consecutive days to rats. Thereafter, glomerular filtration rate, renal blood flow, kidney oxygen consumption, kidney oxygen tension, kidney concentrations of glucose and glycogen, markers of oxidative stress, urinary protein excretion, and histological findings were determined and compared with vehicle-treated controls. Dinitrophenol did not affect arterial blood pressure, renal blood flow, glomerular filtration rate, blood glucose, or markers of oxidative stress but increased kidney oxygen consumption, and reduced cortical and medullary concentrations of glucose and glycogen, and resulted in intrarenal tissue hypoxia. Furthermore, dinitrophenol treatment increased urinary protein excretion, kidney vimentin expression, and infiltration of inflammatory cells. In conclusion, increased mitochondrial oxygen consumption results in kidney hypoxia and subsequent nephropathy. Importantly, these results demonstrate that kidney tissue hypoxia, per se, without confounding hyperglycemia or oxidative stress, may be sufficient to initiate the development of nephropathy and therefore demonstrate a new interventional target for treating kidney disease.
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18. |
- Graham, Lesley A, et al.
(author)
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Validation of Uromodulin as a Candidate Gene for Human Essential Hypertension
- 2014
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In: Hypertension. - 0194-911X .- 1524-4563. ; 63:3, s. 551-558
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Journal article (peer-reviewed)abstract
- A recent genome-wide association study identified a locus on chromosome 16 in the promoter region of the uromodulin (UMOD) gene that is associated with hypertension. Here, we examined the hypertension signal with functional studies in Umod knockout (KO) mice. Systolic blood pressure was significantly lower in KO versus wild-type (WT) mice under basal conditions (KO: 116.6±0.3 mm Hg versus WT: 136.2±0.4 mm Hg; P<0.0001). Administration of 2% NaCl did not alter systolic blood pressure in KO mice, whereas it increased in WT mice by ≈33%, P<0.001. The average 24-hour urinary sodium excretion in the KO was greater than that of WT mice (P<0.001). Chronic renal function curves demonstrate a leftward shift in KO mice, suggesting that the relationship between UMOD and blood pressure is affected by sodium. Creatinine clearance was increased during salt loading with 2% NaCl in the KO mice, leading to augmented filtered Na(+) excretion and further Na(+) loss. The difference in sodium uptake that exists between WT and KO strains was explored at the molecular level. Urinary tumor necrosis factor-α levels were significantly higher in KO mice compared with WT mice (P<0.0001). Stimulation of primary thick ascending limb of the loop of Henle cells with exogenous tumor necrosis factor-α caused a reduction in NKCC2A expression (P<0.001) with a concurrent rise in the levels of UMOD mRNA (P<0.001). Collectively, we demonstrate that UMOD regulates sodium uptake in the thick ascending limb of the loop of Henle by modulating the effect of tumor necrosis factor-α on NKCC2A expression, making UMOD an important determinant of blood pressure control.
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19. |
- Gu, Yu-Mei, et al.
(author)
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Outcome-Driven Thresholds for Ambulatory Pulse Pressure in 9938 Participants Recruited From 11 Populations
- 2014
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In: Hypertension. - 0194-911X .- 1524-4563. ; 63:2, s. 229-237
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Journal article (peer-reviewed)abstract
- Evidence-based thresholds for risk stratification based on pulse pressure (PP) are currently unavailable. To derive outcome-driven thresholds for the 24-hour ambulatory PP, we analyzed 9938 participants randomly recruited from 11 populations (47.3% women). After age stratification (<60 versus >= 60 years) and using average risk as reference, we computed multivariable-adjusted hazard ratios (IIRs) to assess risk by tenths of the PP distribution or risk associated with stepwise increasing (+1 mm Hg) PP levels. All adjustments included mean arterial pressure. Among 6028 younger participants (68 853 person-years), the risk of cardiovascular (HR, 1.58; P=0.011) or cardiac (HR, 1.52; P=0.056) events increased only in the top PP tenth (mean, 60.6 mm Hg). Using stepwise increasing PP levels, the lower boundary of the 95% confidence interval of the successive thresholds did not cross unity. Among 3910 older participants (39 923 person-years), risk increased (P <= 0.028) in the top PP tenth (mean, 76.1 mm Hg). HRs were 1.30 and 1.62 for total and cardiovascular mortality, and 1.52, 1.69, and 1.40 for all cardiovascular, cardiac, and cerebrovascular events. The lower boundary of the 95% confidence interval of the HRs associated with stepwise increasing PP levels crossed unity at 64 mm Hg. While accounting for all covariables, the top tenth of PP contributed less than 0.3% (generalized R-2 statistic) to the overall risk among the elderly. Thus, in randomly recruited people, ambulatory PP does not add to risk stratification below age 60; in the elderly, PP is a weak risk factor with levels below 64 mm Hg probably being innocuous.
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20. |
- Hansen, Tine W., et al.
(author)
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Prognostic value of reading-to-reading blood pressure variability over 24 hours in 8938 subjects from 11 populations
- 2010
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In: Hypertension. - 0194-911X .- 1524-4563. ; 55:4, s. 1049-1057
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Journal article (peer-reviewed)abstract
- In previous studies, of which several were underpowered, the relation between cardiovascular outcome and blood pressure (BP) variability was inconsistent. We followed health outcomes in 8938 subjects (mean age: 53.0 years; 46.8% women) randomly recruited from 11 populations. At baseline, we assessed BP variability from the SD and average real variability in 24-hour ambulatory BP recordings. We computed standardized hazard ratios (HRs) while stratifying by cohort and adjusting for 24-hour BP and other risk factors. Over 11.3 years (median), 1242 deaths (487 cardiovascular) occurred, and 1049, 577, 421, and 457 participants experienced a fatal or nonfatal cardiovascular, cardiac, or coronary event or a stroke. Higher diastolic average real variability in 24-hour ambulatory BP recordings predicted (Por=1.07) with the exception of cardiac and coronary events (HR: or=0.58). Higher systolic average real variability in 24-hour ambulatory BP recordings predicted (P<0.05) total (HR: 1.11) and cardiovascular (HR: 1.16) mortality and all fatal combined with nonfatal end points (HR: >or=1.07), with the exception of cardiac and coronary events (HR: or=0.54). SD predicted only total and cardiovascular mortality. While accounting for the 24-hour BP level, average real variability in 24-hour ambulatory BP recordings added <1% to the prediction of a cardiovascular event. Sensitivity analyses considering ethnicity, sex, age, previous cardiovascular disease, antihypertensive treatment, number of BP readings per recording, or the night:day BP ratio were confirmatory. In conclusion, in a large population cohort, which provided sufficient statistical power, BP variability assessed from 24-hour ambulatory recordings did not contribute much to risk stratification over and beyond 24-hour BP.
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- Joas, Erik, 1983, et al.
(author)
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Blood Pressure Trajectories From Midlife to Late Life in Relation to Dementia in Women Followed for 37 Years
- 2012
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In: Hypertension. - 0194-911X .- 1524-4563. ; 59:4, s. 796-801
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Journal article (peer-reviewed)abstract
- Abstract. Higher midlife blood pressure increases risk for dementia. To further understand the relation between blood pressure and dementia, it is necessary to examine evolution of blood pressure from midlife to late life. We examined blood pressure trajectories using linear mixed models in a representative sample of middle aged women (N1462) who were followed from 1968–1969 until 2005–2006 with comprehensive medical and neuropsychiatric examinations. Dementia was diagnosed according to established criteria. Among those not treated with antihypertensives, higher systolic blood pressure at baseline but not blood pressure trajectories from 1968 to 1992 was associated with dementia and Alzheimer disease. Those with history of antihypertensive treatment had higher baseline systolic blood pressure than those who were never treated. In this group, those who developed dementia and Alzheimer disease had lower baseline systolic blood pressure and steeper increase in systolic blood pressure from 1968 to 1992 than those who did not. A steeper decline in systolic blood pressure during the later part of the study was observed in those who developed dementia regardless of antihypertensive treatment. The latter association was attenuated or disappeared when adjusting for body mass index. The association between blood pressure and dementia is complex and influenced by antihypertensive treatment. The findings emphasize the importance of detecting increased blood pressure in midlife and controlling blood pressure in those treated. Whether the trajectory of blood pressure is a risk factor or part of the clinical course of dementia needs to be elucidated.
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- Komolova, M., et al.
(author)
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Altered Vascular Resistance Properties and Acute Pressure-Natriuresis Mechanism in Neonatal and Weaning Spontaneously Hypertensive Rats
- 2012
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In: Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0194-911X .- 1524-4563. ; 59:5
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Journal article (peer-reviewed)abstract
- Although it has been extensively scrutinized, the factor(s) involved in the initiation and development of hypertension in spontaneously hypertensive rats (SHRs) remains unresolved. The objective of the present study was to determine whether, early in development, the causal mechanism(s) for the development of hypertension in young SHRs involves an integration of 2 processes, specifically an upregulation of structurally based vascular resistance properties and a rightward shift in the hemodynamic component of pressure-natriuresis. Mean arterial pressure was determined in conscious 4-week old SHRs and Wistar-Kyoto rats via previously implanted aortic catheters. Structurally based hindlimb vascular resistance properties were assessed in 2- and 4-week old SHRs and Wistar-Kyoto rats. Renal interstitial hydrostatic pressure was measured after short-term manipulations of renal arterial pressure (RAP) in 4-week old, anesthetized rats, Although mean arterial pressure in conscious SHRs (113 +/- 5 mmHg) and Wistar-Kyoto rats (110 +/- 6 mmHg) was not significantly different at 4 weeks of age, SHRs at 2 and 4 weeks of age already had increases in structurally based vascular resistance properties of approximate to 30% above age- and weight-matched Wistar-Kyoto rats, Furthermore, the acute RAP-renal interstitial hydrostatic pressure relationship was found to be linear in both strains, and the temporal coupling of the stimulus to response was rapid; that is, renal interstitial hydrostatic pressure responses to changes in RAP were <2 s. Although the slope of the RAP-renal interstitial hydrostatic pressure relationship was not significantly different between strains, the relationship was significantly shifted (18%) to higher RAPs in SHRs. These results suggest that alterations in both vascular structure and renal function in young SHRs occur before elevations in mean arterial pressure. (Hypertension. 2012;59:979-984.) circle Online Data Supplement
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- Laszlo, Krisztina D., et al.
(author)
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Psychosocial Stress Related to the Loss of a Close Relative the Year Before or During Pregnancy and Risk of Preeclampsia
- 2013
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In: Hypertension. - 0194-911X .- 1524-4563. ; 62:1, s. 183-189
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Journal article (peer-reviewed)abstract
- The role of stress in the pathogenesis of preeclampsia has only been investigated in a few studies, and the findings are not conclusive. We analyzed whether maternal bereavement shortly before or during pregnancy is associated with an increased risk of preeclampsia. We conducted a cohort study of singleton births in Denmark during 1978-2008 and in Sweden during 1973-2006 (n=4 122 490) by linking national population-based registers. Mothers were considered exposed to bereavement if they lost a parent, a sibling, a partner, or a child the year before or during pregnancy (n=124 553). The risk of preeclampsia was slightly increased for women who lost a close relative during the 6 months before conception (odds ratio [OR], 1.14; 95% confidence interval [CI], 1.06-1.23) or during the first trimester of pregnancy (OR, 1.15; 95% CI, 1.03-1.29). Exposure during these periods tended to be more closely related to early preeclampsia (delivery before 34 weeks of gestation; OR, 1.37; 95% CI, 1.12-1.67) than to late preeclampsia (OR, 1.13; 95% CI, 1.06-1.20). The strongest association was observed between loss of a child and early preeclampsia when the exposure window was from 6 months before pregnancy until start of second trimester (OR, 4.03; 95% CI, 2.46-6.61). Our results related to timing of exposure suggest that severe stress may influence early placentation. However, the public health implications of our findings are limited in populations with a low prevalence of severe stress exposures.
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