Gene-centric meta-analysis in 87,736 individuals of European ancestry identifies multiple blood-pressure-related loci

Blood pressure (BP) is a heritable risk factor for cardiovascular disease. To investigate genetic associations with systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP), we genotyped ~50,000 SNPs in up to 87,736 individuals of European ancestry and combined these in a meta-analysis. We replicated findings in an independent set of 68,368 individuals of European ancestry. Our analyses identified 11 previously undescribed associations in independent loci containing 31 genes including PDE1A, HLA-DQB1, CDK6, PRKAG2, VCL, H19, NUCB2, RELA, HOXC@ complex, FBN1, and NFAT5 at the Bonferroni-corrected array-wide significance threshold (p < 6 × 10(-7)) and confirmed 27 previously reported associations. Bioinformatic analysis of the 11 loci provided support for a putative role in hypertension of several genes, such as CDK6 and NUCB2. Analysis of potential pharmacological targets in databases of small molecules showed that ten of the genes are predicted to be a target for small molecules. In summary, we identified previously unknown loci associated with BP. Our findings extend our understanding of genes involved in BP regulation, which may provide new targets for therapeutic intervention or drug response stratification.

The value of ambulatory blood pressure in older adults: the Dublin outcome study

BACKGROUND

ambulatory blood pressure (ABPM) appears to be a more accurate predictor of cardiovascular outcome than blood pressure (BP) measured in the clinic setting in younger adults.

OBJECTIVES

the purpose of this study was to determine if ABPM predicted total and cardiovascular mortality independently of clinic BP and other cardiovascular risk factors in those aged 65 years and over.

METHODS

one thousand one hundred and forty-four individuals aged 65 and over referred to a single BP clinic had 24-h ABP measurement and clinic measurement at baseline off treatment. There were 385 deaths (of which 246 were cardiovascular) during a mean follow-up period of 6.7 years.

RESULTS

with adjustment for gender, age, risk indices and also for clinic BP, a higher mean value of ABPM was an independent predictor of cardiovascular mortality. The relative hazard ratio for each 10-mmHg rise in systolic blood pressure (SBP) was 1.10 (1.06-1.18, P < 0.001) for daytime and 1.18 (1.11-1.25, P < 0.001) for night-time SBP. The hazard ratios for each 5-mmHg rise in diastolic blood pressure (DBP) were 1.05 (1.00-1.10, P = NS) for daytime and 1.09 (1.04-1.14, P < 0.001) for night-time diastolic pressure. The hazard ratios for night-time ABPM remained significant after adjustment for daytime ABPM.

CONCLUSIONS

ambulatory measurement of BP is superior to clinic measurement in predicting cardiovascular mortality in elderly subjects. Night-time BP is the strongest predictor of outcome in this age group.

Renin gene polymorphisms and haplotypes, blood pressure, and responses to renin-angiotensin system inhibition

Renin catalyzes the rate-limiting step of the renin-angiotensin system. A T allele variant at position -5312 within a distal enhancer region has been reported to increase in vitro renin gene transcription. Among 387 White bank employees, ambulatory blood pressures were higher in 133 -5312T allele carriers than in 254 CC homozygotes-mean differences [99% confidence interval] between carriers and homozygotes for daytime and night-time systolic/diastolic pressure were 2.5[0.4,4.6]/1.7[0.2,3.2] and 2.4[0.5,4.4]/1.5[0.1,2.9] respectively. Ambulatory pressure estimates for the only common renin haplotype including the -5312T variant (-5312T, 5090C, 5912A, 9479A, 10194G), were statistically significantly higher than estimates for all other haplotypes. Among 259 White hypertensive participants in a randomized double-blind clinical trial comparing a renin antagonist, aliskiren, with an angiotensin receptor blocker, losartan, plasma renin activity did not differ with renin -5312C/T genotype. Nocturnal blood pressure reductions with losartan 100 mg daily were significantly greater in -5312T allele carriers than in CC homozygotes (mean[standard error]; -12.9[3.7]/-7.9[2.4] versus -7.1[2.5]/-4.2[1.6]) whereas with aliskiren 150 and 300 mg daily, lesser reductions were observed in -5312T allele carriers than in CC homozygotes (-5.4[2.0]/-4.1[1.3] versus -10.1[1.4]/-6.5[1.1]; P<0.03 for treatmentxgenotype interaction for night-time systolic and diastolic pressures). Hence, the -5312 renin C/T enhancer polymorphism does contribute to blood pressure variation in Whites and also appears to predict responses to inhibition of the renin-angiotensin system. These findings suggest that genotyping at this locus may aid in the identification of susceptibility to hypertension and in the selection of optimal therapy for individual hypertensive patients.

OASIS-HT: design of a pharmacogenomic dose-finding study

Experimental evidence and observations in humans strongly support an interactive role of mutated α-adducin, sodium (Na+)/potassium (K+)-adenosine triphosphatase (ATPase) activity and endogenous ouabain in Na+ homeostasis and the pathogenesis of hypertension. The Ouabain and Adducin for Specific Intervention on Sodium in HyperTension (OASIS-HT) trial is an early Phase II dose-finding study, which will be conducted across 39 European centers. Following a run-in period of 4 weeks without treatment, eligible patients will be randomized to one of five oral doses of rostafuroxin consisting of 0.05, 0.15, 0.5, 1.5, or 5.0 mg/day. Each dose will be compared to a placebo in a double-blind crossover experiment with balanced randomization. Treatment will be initiated with the active drug and continued with placebo or vice versa. Each double-blind period will last 5 weeks. The primary end point is the reduction in systolic blood pressure defined as the average of three clinic readings with the patient in the sitting position. Secondary end points include the reduction in diastolic blood pressure on clinic measurement, the decrease in the 24-h blood pressure, and the incidence of end points related to safety. Secondary objectives are to investigate the dependence of the blood pressure-lowering activity on the plasma concentration of endogenous ouabain and the genetic variation of the enzymes involved in the metabolism of this hormone, and the adducin cytoskeleton proteins. Eligible patients will have Grade I or II systolic hypertension without associated conditions and no more than two additional risk factors. In conclusion, OASIS-HT is a combination of five concurrent crossover studies, one for each dose of rostafuroxin to be studied. To our knowledge, OASIS-HT is the first Phase II dose-finding study in which a genetic hypothesis is driving primary and secondary end points.

Antihypertensive treatment based on home or office blood pressure--the THOP trial

OBJECTIVE AND METHODS

In this randomized clinical trial, conducted in 400 hypertensive patients [sitting diastolic blood pressure (DBP) >95 mmHg], blood pressure-lowering therapy was adjusted in a stepwise manner, either on the basis of the self-measured DBP at home or on the basis of conventional DBP measured at the doctor's office.

RESULTS

Therapy guided by home blood pressure instead of office blood pressure led to less intensive drug treatment and marginally lower costs, but also to less blood pressure control with no differences in left ventricular mass. Self-measurement helped to identify patients with white-coat hypertension.

CONCLUSIONS

The present findings support a stepwise strategy for the evaluation of blood pressure, in which self-measurement and ambulatory monitoring are complementary to conventional office blood pressure measurement.

Effect of hydrostatic pressure gradients and Na2EDTA on permeability of human Schlemm's canal cell monolayers

PURPOSE

Elevated intraocular pressure in those with glaucoma appears to be a function of increased resistance to movement of aqueous humor through the conventional outflow pathway. The majority of resistance in both normal and glaucomatous eyes is generated in the region between the juxtacanalicular trabecular meshwork and the inner wall of Schlemm's canal. To accommodate transient elevations in pressure, we hypothesize that conventional outflow increases rapidly due to changes in complexity of intercellular junctions between cells of the inner wall of Schlemm's canal.

METHODS

To test this hypothesis we examined specifically the effects of hydrostatic pressure gradients and the calcium chelator, Na2EDTA, on permeability of cultured human Schlemm's canal cell monolayers in isolation. Human Schlemm's Canal cells were isolated, cultured and then seeded onto permeable supports and maintained in culture to allow intercellular junctions to mature. With a minimum net transendothelial electrical resistance of 10 Ohm cm2, cells were placed into an Ussing-type chamber and hydraulic conductivity was calculated from pressure and flow measurements that were continuously recorded. Simultaneously, transendothelial electrical resistance was measured manually at fixed intervals. In parallel experiments, cell margins were monitored in real time by videomicroscopy.

RESULTS

During the baseline measurement period when cells were exposed to pressure but not Na2EDTA, hydraulic conductivity was constant but transendothelial electrical resistance decreased continuously at rate of 0.24 Ohm cm2/minute. After Na2EDTA treatment, no significant change in transendothelial electrical resistance was measured while, hydraulic conductivity of Schlemm's Canal monolayers increased significantly by 125%; corresponding to noticeable intercellular separations. Restoration of cell-cell contact was observed by videomicroscopy 30 minutes following washout of Na2EDTA and functionally after 2 hours.

CONCLUSIONS

Responses of Schlemm's Canal cells to pressure and calcium chelators in vitro are consistent with a role for calcium sensitive junctions in outflow resistance in vivo.

Systolic blood pressure variability as a risk factor for stroke and cardiovascular mortality in the elderly hypertensive population

OBJECTIVE

To investigate whether baseline systolic blood pressure variability was a risk factor for stroke, cardiovascular mortality or cardiac events during the Syst-Eur trial.

DESIGN

The Syst-Eur study was a randomized, double-blind, placebo-controlled trial, powered to detect differences in stroke rate between participants on active antihypertensive treatment and placebo. Systolic blood pressure variability measurements were made on 744 participants at the start of the trial. Systolic blood pressure variability was calculated over three time frames: 24 h, daytime and night-time. The placebo and active treatment subgroups were analysed separately using an intention-to-treat principle, adjusting for confounding factors using a multiple Cox regression model.

PARTICIPANTS

An elderly hypertensive European population.

MAIN OUTCOME MEASURES

Stroke, cardiac events (fatal and non-fatal heart failure, fatal and non-fatal myocardial infarction and sudden death) and cardiovascular mortality (death attributed to stroke, heart failure, myocardial infarction, sudden death, pulmonary embolus, peripheral vascular disease and aortic dissection).

RESULTS

The risk of stroke increased by 80% (95% confidence interval: 17-176%) for every 5 mmHg increase in night-time systolic blood pressure variability in the placebo group. Risk of cardiovascular mortality and cardiac events was not significantly altered. Daytime variability readings did not predict outcome. Antihypertensive treatment did not affect systolic blood pressure variability over the median 4.4-year follow-up.

CONCLUSION

In the placebo group, but not the active treatment group, increased night-time systolic blood pressure variability on admission to the Syst-Eur trial was an independent risk factor for stroke during the trial.

Antihypertensive treatment based on blood pressure measurement at home or in the physician's office: a randomized controlled trial

CONTEXT

Self-measurement of blood pressure is increasingly used in clinical practice, but how it affects the treatment of hypertension requires further study.

OBJECTIVE

To compare use of blood pressure (BP) measurements taken in physicians' offices and at home in the treatment of patients with hypertension.

DESIGN, SETTING, AND PARTICIPANTS

Blinded randomized controlled trial conducted from March 1997 to April 2002 at 56 primary care practices and 3 hospital-based outpatient clinics in Belgium and 1 specialized hypertension clinic in Dublin, Ireland. Four hundred participants with a diastolic BP (DBP) of 95 mm Hg or more as measured at physicians' offices were enrolled and followed up for 1 year.

INTERVENTIONS

Antihypertensive drug treatment was adjusted in a stepwise fashion based on either the self-measured DBP at home (average of 6 measurements per day during 1 week; n = 203) or the average of 3 sitting DBP readings at the physician's office (n = 197). If the DBP guiding treatment was above (>89 mm Hg), at (80-89 mm Hg), or below (<80 mm Hg) target, a physician blinded to randomization intensified antihypertensive treatment, left it unchanged, or reduced it, respectively.

MEAN OUTCOME MEASURES

Office and home BP levels, 24-hour ambulatory BP, intensity of drug treatment, electrocardiographic and echocardiographic left ventricular mass, symptoms reported by questionnaire, and costs of treatment.

RESULTS

At the end of the study (median follow-up, 350 days; interquartile range, 326-409 days), more home BP than office BP patients had stopped antihypertensive drug treatment (25.6% vs 11.3%; P<.001) with no significant difference in the proportions of patients progressing to multiple-drug treatment (38.7% vs 45.1%; P =.14). The final office, home, and 24-hour ambulatory BP measurements were higher (P<.001) in the home BP group than in the office BP group. The mean baseline-adjusted systolic/diastolic differences between the home and office BP groups averaged 6.8/3.5 mm Hg, 4.9/2.9 mm Hg, and 4.9/2.9 mm Hg, respectively. Left ventricular mass and reported symptoms were similar in the 2 groups. Costs per 100 patients followed up for 1 month were only slightly lower in the home BP group (3875 vs 3522 [4921 dollars vs 4473 dollars]; P =.04).

CONCLUSIONS

Adjustment of antihypertensive treatment based on home BP instead of office BP led to less intensive drug treatment and marginally lower costs but also to less BP control, with no differences in general well-being or left ventricular mass. Self-measurement allowed identification of patients with white-coat hypertension. Our findings support a stepwise strategy for the evaluation of BP in which self-measurement and ambulatory monitoring are complementary to conventional office measurement and highlight the need for prospective outcome studies to establish the normal range of home-measured BP.

Cardiovascular risk in white-coat and sustained hypertensive patients

We compared cardiovascular outcome between patients with white-coat and sustained hypertension who had previously participated in the Ambulatory Blood Pressure Monitoring and Treatment of Hypertension (APTH) trial. Baseline characteristics, including office and ambulatory blood pressure (BP), were measured during the 2-month run-in period of the APTH trial. During follow-up, information on the occurrence of major cardiovascular events (death, myocardial infarction, stroke and heart failure), achieved office BP and treatment status was obtained. At entry, 326 patients had sustained hypertension (daytime ambulatory BP > or = 140 mmHg systolic and/or > or = 90 mmHg diastolic) and 93 had daytime ambulatory BP below these limits and were classified as white-coat hypertensives. During 2088 patient-years of follow-up (median follow-up 5.3 years), all major cardiovascular events (n = 22) occurred in the patients with sustained hypertension (rate 12.7 per 1000 patient-years, p = 0.02 for between-group difference). Furthermore, multiple Cox regression confirmed that after adjustment for important covariables, daytime ambulatory BP--but not office BP at entry--significantly and independently predicted cardiovascular outcome. After additional adjustment for office BP, daytime ambulatory BP still predicted the occurrence of major cardiovascular events. Although white-coat hypertension was less frequently associated with antihypertensive drug treatment during follow-up, it carried a significantly better prognosis than sustained hypertension.

Predictive value of clinic and ambulatory heart rate for mortality in elderly subjects with systolic hypertension

OBJECTIVE

To examine the association of clinic and ambulatory heart rate with total, cardiovascular, and noncardiovascular death in a cohort of elderly subjects with isolated systolic hypertension from the Systolic Hypertension in Europe Trial.

METHODS

A total of 4682 patients participated, whose untreated blood pressure on conventional measurement at baseline was 160 to 219 mm Hg systolic and lower than 95 mm Hg diastolic. Clinic heart rate was the mean of 6 readings during 3 visits. Ambulatory heart rate was recorded with a portable intermittent technique in 807 subjects.

RESULTS

Raised baseline clinic heart rate was positively associated with a worse prognosis for total, cardiovascular, and noncardiovascular mortality among the 2293 men and women taking placebo. Subjects with heart rates higher than 79 beats/min (bpm) (top quintile) had a 1.89 times greater risk of mortality than subjects with heart rate lower than or equal to 79 bpm (95% confidence interval, 1.33-2.68 bpm). In a Cox regression analysis, predictors of time to death were heart rate (P<.001), age (P<.001), serum creatinine level (P =.001), presence of diabetes (P =.002), previous cardiovascular disease (P =.01), triglyceride readings (P =.02), smoking (P =.04), and elevated systolic blood pressure (P =.05), while total cholesterol level was found to be nonsignificant in the model. In the ambulatory monitoring subgroup, clinic and ambulatory heart rates predicted noncardiovascular but not cardiovascular mortality. However, in a Cox regression analysis in which clinic and ambulatory heart rates were included, a significant association with noncardiovascular mortality was found only for clinic heart rate (P =.004). In the active treatment group, the weak predictive power of clinic heart rate for mortality disappeared after adjustment for confounders.

CONCLUSIONS

In untreated older patients with isolated systolic hypertension, a clinic heart rate greater than 79 bpm was a significant predictor of all-cause, cardiovascular, and noncardiovascular mortality. Ambulatory heart rate did not add prognostic information to that provided by clinic heart rate.

Ambulatory pulse pressure as predictor of outcome in older patients with systolic hypertension

We enrolled 808 older patients with isolated systolic hypertension (160 to 219/71 <95 mm Hg) to investigate whether ambulatory measurement of pulse pressure and mean pressure can refine risk stratification. The patients (> or =60 years) were randomized to nitrendipine (10 to 40 mg/day) with the possible addition of enalapril (5 to 20 mg/day) or hydrochlorothiazide (12.5 to 25 mg/day) or to matching placebos. At baseline, pulse pressure and mean pressure were determined from six conventional blood pressure (BP) readings and from 24-h ambulatory recordings. With adjustment for significant covariables, we computed mutually adjusted relative hazard rates associated with 10 mm Hg increases in pulse pressure or mean pressure. In the placebo group, the 24-h and nighttime pulse pressures consistently predicted total and cardiovascular mortality, all cardiovascular events, stroke, and cardiac events. Daytime pulse pressure predicted cardiovascular mortality, all cardiovascular end points, and stroke. The hazard rates for 10 mm Hg increases in pulse pressure ranged from 1.25 to 1.68. Conventionally measured pulse pressure predicted only cardiovascular mortality with a hazard rate of 1.35. In the active treatment group compared with the placebo patients, the relation between outcome and ambulatory pulse pressure was attenuated to a nonsignificant level. Mean pressure determined from ambulatory or conventional BP measurements was not associated with poorer prognosis. In conclusion, in older patients with isolated systolic hypertension higher pulse pressure estimated by 24-h ambulatory monitoring was a better predictor of adverse outcomes than conventional pulse pressure, whereas conventional and ambulatory mean pressures were not correlated with a worse outcome.

Localization of myocilin to the golgi apparatus in Schlemm's canal cells

PURPOSE

Biochemical and genetic evidence suggests that overexpression of or mutations in myocilin within the cells of the aqueous humor outflow pathway play a significant role in the development of steroid-induced and several other open-angle glaucomas. As a baseline to understanding the normal and pathologic function of myocilin, we determined the subcellular localization of myocilin in steroid-treated human Schlemm's canal endothelial (SC) cells.

METHODS

SC cells were grown to confluence, treated with dexamethasone for 10 days, and then stained using antibodies against myocilin, tubulin, or beta-COP (a specific golgi protein) or vital stains for endoplasmic reticulum (ER) and golgi. Brefeldin A (BFA) and nocodazol (NZ) were used to disrupt the golgi or microtubules.

RESULTS

The authors found that myocilin staining was (a) always centered around the centrosome, (b) very similar to the pattern seen with NBD-ceramide, (c) was disrupted in characteristic ways by BFA and NZ and (d) showed extensive colocalization with beta-COP.

CONCLUSIONS

Results indicate that myocilin is localized to the golgi in SC cells. Such localization is consistent with myocilin being processed for secretion but is also consistent with sequence analysis and other data that suggest that myocilin or myocilin mutations might be targeted to the cytoplasmic face of the golgi, and under some circumstances play a role in or interfere with golgi or vesicle function. How such interference could eventually lead to open angle glaucoma is discussed.

Modern approaches to blood pressure measurement

BACKGROUND

Blood pressure (BP) is usually measured by conventional sphygmomanometry. Although apparently simple, this procedure is fraught with many potential sources of error. This review focuses on two alternative techniques of BP measurement: ambulatory monitoring and self measurement.

REVIEW

BP values obtained by ambulatory monitoring or self measurement are characterised by high reproducibility, are not subject to digit preference or observer bias, and minimise the transient rise of the blood pressure in response to the surroundings of the clinic or the presence of the observer, the so called white coat effect. For ambulatory monitoring, the upper limits of systolic/diastolic normotension in adults include 130/80 mm Hg for the 24 hour BP and 135/85 and 120/70 mm Hg for the daytime BP and night time BP, respectively. For the the self measured BP these thresholds include 135/85 mm Hg. Automated BP measurement is most useful to identify patients with white coat hypertension. Whether or not white coat hypertension predisposes to sustained hypertension remains debated. However, outcome is better correlated with the ambulatory BP than with the conventional BP. In patients with white coat hypertension, antihypertensive drugs lower the BP in the clinic, but not the ambulatory BP, and also do not improve prognosis. Ambulatory BP monitoring is also better than conventional BP measurement in assessing the effects of treatment. Ambulatory BP monitoring is necessary to diagnose nocturnal hypertension and is especially indicated in patients with borderline hypertension, elderly patients, pregnant women, patients with treatment resistant hypertension, and also in patients with symptoms suggestive of hypotension.

CONCLUSIONS

The newer techniques of BP measurement are now well established in clinical research, for diagnosis in clinical practice, and will increasingly make their appearance in occupational and environmental medicine.

n-ethylmaleimide and ethacrynic acid inhibit kinesin binding to microtubules in a motility assay

Treatment of proteins in vitro with sulfhydryl (SH)-reactive compounds has been used successfully to determine protein regions critical for normal function. To probe structure-function relationships in the microtubule (MT) motor kinesin, the motor was treated with two SH reactive compounds, n-ethylmaleimide and ethacrynic acid, and its function was assayed by motility and co-sedimentation techniques. In the motility assay, treatment of kinesin either before or after adsorption to the glass surfaces of a flow cell was found to inhibit the ability of coverslip-bound kinesin to bind to MTs. Inactivation of MT binding was slow, required high molar excess of the SH-reactive drug, and was very sensitive to temperature. Inhibition of MT binding occurred well after complete modification of kinesin light chain, but paralleled modification of the kinesin heavy chain. The results point to a model in which one critical cysteine per kinesin heavy chain is relatively inaccessible to solvent. Surprisingly, when the interaction between modified kinesin and MTs was examined by a co-sedimentation assay, kinesin retained the ability to bind MTs. These contrasting results may be due to conformational differences in the kinesin molecule that exist in the two assays.

How calcium causes microtubule depolymerization

The effects of calcium (Ca) were assessed using video-enhanced differential interference contrast light microscopy on individual microtubules in vitro. Phosphocellulose-purified (PC) and microtubule associated protein (MAP)-containing preparations of porcine brain tubulin were assembled in a flow chamber onto sperm axoneme fragments and the pattern of growth and shortening of the microtubules was observed. Tubulin plus Ca was then added to the chamber and observation continued. Ca promoted the disassembly of microtubules by specifically promoting the catastrophe reaction in both PC- and MAP-containing microtubules, without an appreciable change in elongation rate. The effect on catastrophe frequency increased very rapidly above 0.5 mM free Ca, implying a possible cooperative effect. The rescue rate remained very high after Ca addition in MAP-containing microtubules, and the shortening rate was unchanged, while in phosphocellulose-purified microtubules, rescue appeared to be decreased by Ca addition and shortening rates increased 4 to 6-fold. These results illustrate that Ca can directly destabilize growing microtubule ends without changing the effective concentration of free tubulin, and that this effect can be seen even against the background of the profound differences in dynamics conferred by the microtubule-associated proteins. Considered within models of the GTP cap, the results imply that high Ca may act to increase the rate of GTP hydrolysis within the cap.

Arterial hypotension: prevalence of low blood pressure in the general population using ambulatory blood pressure monitoring

BACKGROUND

Chronic constitutional hypotension has been described in a proportion of the population, and has a symptom complex ascribed to it. The true prevalence of low blood pressure in the normal population has not been defined.

AIM OF STUDY

This study was undertaken to determine the prevalence of low blood pressure states, as measured using ambulatory blood pressure monitoring, in a general population cohort, and to determine the association between low blood pressure and clinical and demographic variables.

PATIENT POPULATION

The population enrolled were a cohort of mainly urban dwelling Irish subjects, either employees or spouses of employees of a major national bank.

METHODS

Subjects had an ambulatory blood pressure monitor fitted between 09.00 and 12.00 and wore the monitor for 24 hours. The subjects also filled out a detailed lifestyle questionnaire, and kept an activity diary. Blood was drawn for serum electrolyte estimation.

RESULTS

A total of 254 subjects were included, 49% of whom demonstrated hypotensive events. Hypotensive means and individual hypotensive values were more frequently found in women, and occurred in a group of individuals with a distinct body habitus, specifically thin subjects, with a lower creatinine suggesting a smaller muscle mass. Hypotensive events in these subjects were associated with a low risk cardiovascular profile, in that subjects who displayed these events had a lower blood pressure, a lower weight and were less likely to have a positive family history of hypertension or vascular disease.

CONCLUSION

Hypotension is common in the general population and is associated with a distinct body habitus. It carries a generally benign cardiovascular risk factor profile.

Predicting cardiovascular risk using conventional vs ambulatory blood pressure in older patients with systolic hypertension. Systolic Hypertension in Europe Trial Investigators

CONTEXT

The clinical use of ambulatory blood pressure (BP) monitoring requires further validation in prospective outcome studies.

OBJECTIVE

To compare the prognostic significance of conventional and ambulatory BP measurement in older patients with isolated systolic hypertension.

DESIGN

Substudy to the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) Trial, started in October 1988 with follow up to February 1999. The conventional BP at randomization was the mean of 6 readings (2 measurements in the sitting position at 3 visits 1 month apart). The baseline ambulatory BP was recorded with a noninvasive intermittent technique.

SETTING

Family practices and outpatient clinics at primary and secondary referral hospitals.

PARTICIPANTS

A total of 808 older (aged > or =60 years) patients whose untreated BP level on conventional measurement at baseline was 160 to 219 mm Hg systolic and less than 95 mm Hg diastolic.

INTERVENTIONS

For the overall study, patients were randomized to nitrendipine (n = 415; 10-40 mg/d) with the possible addition of enalapril (5-20 mg/d) and/or hydrochlorothiazide (12.5-25.0 mg/d) or to matching placebos (n = 393).

MAIN OUTCOME MEASURES

Total and cardiovascular mortality, all cardiovascular end points, fatal and nonfatal stroke, and fatal and nonfatal cardiac end points.

RESULTS

After adjusting for sex, age, previous cardiovascular complications, smoking, and residence in western Europe, a 10-mm Hg higher conventional systolic BP at randomization was not associated with a worse prognosis, whereas in the placebo group, a 10-mm Hg higher 24-hour BP was associated with an increased relative hazard rate (HR) of most outcome measures (eg, HR, 1.23 [95% confidence interval [CI], 1.00-1.50] for total mortality and 1.34 [95% CI, 1.03-1.75] for cardiovascular mortality). In the placebo group, the nighttime systolic BP (12 AM-6 AM) more accurately predicted end points than the daytime level. Cardiovascular risk increased with a higher night-to-day ratio of systolic BP independent of the 24-hour BP (10% increase in night-to-day ratio; HR for all cardiovascular end points, 1.41; 95% CI, 1.03-1.94). At randomization, the cardiovascular risk conferred by a conventional systolic BP of 160 mm Hg was similar to that associated with a 24-hour daytime or nighttime systolic BP of 142 mm Hg (95% CI, 128-156 mm Hg), 145 mm Hg (95% CI, 126-164 mm Hg) or 132 mm Hg (95% CI, 120-145 mm Hg), respectively. In the active treatment group, systolic BP at randomization did not significantly predict cardiovascular risk, regardless of the technique of BP measurement.

CONCLUSIONS

In untreated older patients with isolated systolic hypertension, ambulatory systolic BP was a significant predictor of cardiovascular risk over and above conventional BP.

Development of diagnostic thresholds for automated measurement of blood pressures in adults

In clinical medicine, blood pressure is usually measured by conventional sphygmomanometry. Although it seems simple at first sight, this procedure is fraught with potential sources of error, which may arise from the subject, the observer, the sphygmomanometer or the overall application of the technique. Automated techniques of blood pressure measurement, such as ambulatory monitoring and self-measurement, reduce the limitations of conventional sphygmomanometry. However, the diagnostic thresholds applicable for conventional sphygmomanometry cannot be extrapolated to automated measurements. During the past 10 years criteria for normality have gradually been developed for ambulatory blood pressure (ABP) monitoring of adults. First, the distribution of the ABP in normotensive subjects and untreated hypertensive patients who had initially been recruited and classified on the basis of their conventional blood pressure was studied. Second, authors of various epidemiological studies investigated the distributions of the conventional blood pressure and the ABP in the population at large. Third, authors of several reports attempted to validate the preliminary thresholds for ambulatory monitoring by correlating the ABP to left ventricular hypertrophy, other intermediary signs of target-organ damage or the incidence of cardiovascular morbidity or mortality. Finally, clinical trials should be mounted to prove that it is beneficial to patients as well as cost-effective to diagnose and treat hypertension on the basis of ambulatory monitoring rather than solely under the guidance of conventional sphygmomanometry. For measurements of systolic/diastolic ABP in adults, the proposed upper limits of normotension are 130/80 mmHg for the 24h blood pressure and 135/85 and 120/70 mmHg for the daytime and night-time blood pressures, respectively; for the self-measured blood pressure 135/85 mmHg might be the upper limit of normality. With regard to ABP monitoring, a large database already supports the proposed diagnostic thresholds in terms of their associations with left ventricular hypertrophy and with the incidence of cardiovascular complications; the evidence to validate the thresholds for the self-recorded blood pressure, to a large extent, must still be collected. In conclusion, the newer techniques of blood pressure measurement are now well established in the diagnosis and management of adult subjects with hypertension.

Is elevation of clinic blood pressure in patients with white coat hypertension who have normal ambulatory blood pressure associated with target organ changes?

BACKGROUND

The issue as to whether white coat hypertension is a pathologically significant entity, with associated target organ changes, or that the condition carries the same risk for target organ involvement as normotension, is undecided. Previous studies which have shown pathological correlates between white coat hypertension and target organ damage have not controlled for the most obvious confounder, mean 24 h blood pressure (BP).

METHODS AND RESULTS

In this study we retrospectively identified 33 age and sex-matched pairs, one group with normal BP, the other with white coat hypertension. The white coat hypertensive group showed significantly greater left ventricular mass indexed for body surface area than normal controls (99.0 g/m2 vs 78.3 g/m2, P < 0.001). The population was then further matched for 24-h mean BP (20 pairs), and was again compared for cardiac muscle changes. The significantly increased left ventricular mass index in the white coat population remained after controlling for 24-h mean BP (101.1 g/m2 vs 81.0 g/m2, P < 0.021).

CONCLUSION

White coat hypertension is indeed associated with a larger left ventricular muscle mass than normotensives and these changes are independent of the actual 24-h BP load, and may reflect increased BP lability, sympathetic nervous system derangement, or a genetic propensity in people with white coat hypertension to stress-related hypertensive reactions, as part of a pre-hypertensive state.

Tyrphostins disrupt stress fibers and cellular attachments in endothelial monolayers

Endothelial permeability, which plays a critical role in many physiologic and pathologic processes, depends on the integrity of intercellular and cell-substrate attachments and the actin cytoskeleton. The proteins located at the cytoplasmic face of adherens and focal contact junctions are rich in sites of tyrosine phosphorylation. To better understand the role of tyrosine phosphorylation in regulating endothelial cell shape, actin stress fibers, and cell junctions, we treated confluent calf pulmonary artery endothelial cells with 14 different tyrphostins, a class of specific tyrosine kinase inhibitors. Using immunofluorescence microscopy to assess cell shape, phosphotyrosine levels, actin stress fibers, and focal contact and junctional proteins, we found that the effects of the tyrphostins could be grouped into three categories. Four tyrphostins had no discernible effect on stress fibers or cell attachments. Seven tyrphostins produced cell retraction with concomitant disruption of both stress fibers and cell-substrate attachments. One member of this group, tyrphostin 25, showed greater specificity for cell-cell junctions than the others, causing cell separation without significantly affecting actin stress fibers or focal contacts. The third group of tyrphostins had the opposite effect, completely disrupting stress fibers and focal contacts without causing cell separation. The ability of specific tyrphostins to disrupt cell-cell or cell-substrate attachments and/or actin stress fibers implies that a certain steady-state level of tyrosine phosphorylation is necessary to maintain these structures and that there may be independent tyrosine kinase signaling pathways controlling them. Comparison of the phosphotyrosinated proteins affected by each group of tyrphostins should provide a useful new approach toward understanding the regulation of endothelial cell-cell and cell-substrate junctions.

Ambulatory blood pressure monitoring and postprandial hypotension in elderly patients with isolated systolic hypertension. Systolic Hypertension in Europe (SYST-EUR) Trial Investigators

The present analysis was undertaken to evaluate postprandial (PP) changes in blood pressure (BP) assessed with ambulatory BP monitoring (ABPM) in elderly subjects with isolated systolic hypertension (ISH) on conventional measurement. A total of 530 patients (335 women and 195 men, aged 60-100 years, median 70 years) who performed an ABPM during the placebo run-in period of the Syst-Eur trial were included into the analysis. The PP changes in BP and heart rate (HR) were calculated by subtracting the mean systolic BP (SBP), diastolic BP (DBP) and HR in the 2 h preceding the main meal from the corresponding means covering the 2 h after the meal. The reproducibility of the postprandial fall in BP and heart rate (PPH) was assessed by contrasting the first and second ABPM in a subgroup of 147 patients who performed two ABPM's during the placebo run-in period. The mean SBP and DBP decreased and reached the nadir 2 h after the main meal while HR did not change. When PPH was assessed by comparing BP in the 2 h before and after the meal, both SBP and DBP decreased significantly (respectively -6.6 mm Hg, -5.4 mm Hg; P < 0.001). In 67.6% of all patients a decrease in SBP was observed and in 24.1% it exceeded 16 mm Hg. The corresponding values for DBP were 71.3% and 24.5% (DBP decreased more than 12 mm Hg). A greater fall in DBP was associated with a greater decrease in HR (r = 0.20, P < 0.001), while changes in SBP and HR were not interrelated. Regression analysis did not identify any significant covariate of PPH. Group means of PPH could be reproduced without significant changes in their values, but the within-subject reproducibility of the PP changes was low. There were no differences in PPH according to the place of residence of the patients. In conclusion, the descriptive analysis of the meal-induced changes in ABPM in elderly subjects with ISH showed that in every day circumstances most of them experience falls in both SBP and DBP within 2 h after the meal.

A mechanism for trabecular meshwork cell retraction: ethacrynic acid initiates the dephosphorylation of focal adhesion proteins

Ethacrynic acid (ECA) increases aqueous humor outflow facility in human and animal model systems, and causes cellular retraction in cultured trabecular meshwork (TM) cells. ECA-induced retraction, a possible correlate to the opening of spaces in the outflow pathway in vivo, takes place coincident with disruption of cell-cell attachments and actin stress fibers. Tyrosine phosphorylated proteins are located predominantly where actin filaments terminate at sites of cell-to-cell and cell-to-substrate adhesion, and are understood to regulate cellular adhesions and filamentous (F) actin organization in many cell types. In the present study we investigated whether ECA might affect cell adhesions and F-actin in TM cells by altering levels of phosphotyrosine. We analysed levels of phosphotyrosine in cultured human TM and calf pulmonary artery endothelial cells after exposure to ECA. Using immunoflourescence microscopy and antibodies to phosphotyrosinated proteins we found a rapid decrease in phosphotyrosine levels at the focal contacts of cells treated with ECA. Immunoblots of whole cell extracts showed a decrease in phosphotyrosine predominantly in a band running at about 120 kD, with a more subtle decrease in a band about 65 kD. Reprobing the blot with antibodies to pp120 focal adhesion kinase (FAK) or paxillin indicated that the 120 kD band was FAK and the 65 kD band was likely paxillin. Immunoprecipitation of FAK or paxillin and probing the resulting blot with antibodies to phosphotyrosine confirmed that these proteins were rapidly dephosphorylated after ECA addition. Loss of FAK and paxillin proteins in cells was then confirmed using immunofluorescence microscopy. Dephosphorylation of these proteins was detected before the onset of retraction, stress fiber disruption, or complete disruption of focal adhesions. A pure microtubule inhibitor (colchicine), did not cause stress fiber disruption or decrease focal adhesion phosphorylation. We postulate that dephosphorylation of FAK and paxillin by ECA disrupts signaling pathways that normally maintain the stability of the actin cytoskeleton and cellular adhesions, and that this action leads both to cell shape change in culture, and to facility changes in vivo.

Antihypertensive treatment based on conventional or ambulatory blood pressure measurement. A randomized controlled trial. Ambulatory Blood Pressure Monitoring and Treatment of Hypertension Investigators

CONTEXT

Ambulatory blood pressure (ABP) monitoring is used increasingly in clinical practice, but how it affects treatment of blood pressure has not been determined.

OBJECTIVE

To compare conventional blood pressure (CBP) measurement and ABP measurement in the management of hypertensive patients.

DESIGN

Multicenter, randomized, parallel-group trial.

SETTING

Family practices and outpatient clinics at regional and university hospitals.

PARTICIPANTS

A total of 419 patients (> or =18 years), whose untreated diastolic blood pressure (DBP) on CBP measurement averaged 95 mm Hg or higher, randomized to CBP or ABP arms.

INTERVENTIONS

Antihypertensive drug treatment was adjusted in a stepwise fashion based on either the average daytime (from 10 AM to 8 PM) ambulatory DBP (n=213) or the average of 3 sitting DBP readings (n=206). If the DBP guiding treatment was above (>89 mm Hg), at (80-89 mm Hg), or below (<80 mm Hg) target, 1 physician blinded to the patients' randomization intensified antihypertensive treatment, left it unchanged, or reduced it, respectively.

MAIN OUTCOME MEASURES

The CBP and ABP levels, intensity of drug treatment, electrocardiographic and echocardiographic left ventricular mass, symptoms reported by questionnaire, and cost.

RESULTS

At the end of the study (median follow-up, 182 days; 5th to 95th percentile interval, 85-258 days), more ABP than CBP patients had stopped antihypertensive drug treatment (26.3% vs 7.3%; P<.001), and fewer ABP patients had progressed to sustained multiple-drug treatment (27.2% vs 42.7%; P<.001). The final CBP and 24-hour ABP averaged 144.1/89.9 mm Hg and 129.4/79.5 mm Hg in the ABP group and 140.3/89.6 mm Hg and 128.0/79.1 mm Hg in the CBP group. Left ventricular mass and reported symptoms were similar in the 2 groups. The potential savings in the ABP group in terms of less intensive drug treatment and fewer physician visits were offset by the costs of ABP monitoring.

CONCLUSIONS

Adjustment of antihypertensive treatment based on ABP monitoring instead of CBP measurement led to less intensive drug treatment with preservation of blood pressure control, general well-being, and inhibition of left ventricular enlargement but did not reduce the overall costs of antihypertensive treatment.

Randomised double-blind comparison of placebo and active treatment for older patients with isolated systolic hypertension. The Systolic Hypertension in Europe (Syst-Eur) Trial Investigators

BACKGROUND

Isolated systolic hypertension occurs in about 15% of people aged 60 years or older. In 1989, the European Working Party on High Blood Pressure in the Elderly investigated whether active treatment could reduce cardiovascular complications of isolated systolic hypertension. Fatal and non-fatal stroke combined was the primary endpoint.

METHODS

All patients (> 60 years) were initially started on masked placebo. At three run-in visits 1 month apart, their average sitting systolic blood pressure was 160-219 mm Hg with a diastolic blood pressure lower than 95 mm Hg. After stratification for centre, sex, and previous cardiovascular complications, 4695 patients were randomly assigned to nitrendipine 10-40 mg daily, with the possible addition of enalapril 5-20 mg daily and hydrochlorothiazide 12.5-25.0 mg daily, or matching placebos. Patients withdrawing from double-blind treatment were still followed up. We compared occurrence of major endpoints by intention to treat.

FINDINGS

At a median of 2 years' follow-up, sitting systolic and diastolic blood pressures had fallen by 13 mm Hg and 2 mm Hg in the placebo group (n = 2297) and by 23 mm Hg and 7 mm Hg in the active treatment group (n = 2398). The between-group differences were systolic 10.1 mm Hg (95% CI 8.8-11.4) and diastolic, 4.5 mm Hg (3.9-5.1). Active treatment reduced the total rate of stroke from 13.7 to 7.9 endpoints per 1000 patient-years (42% reduction; p = 0.003). Non-fatal stroke decreased by 44% (p = 0.007). In the active treatment group, all fatal and non-fatal cardiac endpoints, including sudden death, declined by 26% (p = 0.03). Non-fatal cardiac endpoints decreased by 33% (p = 0.03) and all fatal and non-fatal cardiovascular endpoints by 31% (p < 0.001). Cardiovascular mortality was slightly lower on active treatment (-27%, p = 0.07), but all-cause mortality was not influenced (-14%; p = 0.22).

INTERPRETATION

Among elderly patients with isolated systolic hypertension, antihypertensive drug treatment starting with nitrendipine reduces the rate of cardiovascular complications. Treatment of 1000 patients for 5 years with this type of regimen may prevent 29 strokes or 53 major cardiovascular endpoints.

Determining the trough-to-peak ratio in parallel-group trials. Systolic Hypertension in Europe (SYST-EUR) Trial Investigators

We explored how in parallel-group trials interindividual variability, correction for placebo effects, and smoothing of blood pressure profiles can be handled in measuring the trough-to-peak ratio in 244 individuals with isolated systolic hypertension (> or = 60 years) enrolled in the placebo-controlled Systolic Hypertension in europe Trial. Net treatment effects were computed by subtracting the mean changes from baseline during placebo (n = 133) from those during active treatment (n = 111). At entry, systolic/diastolic pressures averaged 176/86 mm Hg in the clinic and 149/80 mm Hg on 24-hour ambulatory monitoring. With corrections applied for baseline and placebo, nitrendipine (10 to 40 mg/d), with the possible addition of enalapril (5 to 20 mg/d) and/or hydrochlorothiazide (12.5 to 25 mg/d), reduced (P < .001) these blood pressure values by 16.6/7.3 and 9.8/4.7 mm Hg, respectively. The net trough-to-peak ratios were first determined from blood pressure profiles (12 hours) with 1-hour precision, synchronized by the morning and evening doses of the double-blind medication. According to the usual approach, disregarding interindividual variability, the systolic/diastolic net trough-to-peak ratios were 0.46/0.40 in the morning and 0.77/0.99 in the evening. In individual subjects, the baseline-adjusted trough-to-peak ratios were nonnormally distributed. We therefore used a nonparametric technique to calculate the net trough-to-peak ratios from the results in individual subjects. In the morning, these ratios averaged 0.25 systolic (95% confidence interval, 0.09 to 0.41) and 0.15 diastolic (95% confidence interval, 0.00 to 0.31) and in the evening, 0.19 and 0.36 (95% confidence intervals, 0.00 to 0.38 and 0.14 to 0.56), respectively. When the blood pressure profiles were smoothed by substituting the 1-hour averages by moving or fixed 2-hour averages or by Fourier modeling, the trough-to-peak ratios remained unchanged after the morning dose (0.20/0.13, 0.20/0.14, and 0.16/0.21, respectively) but tended to increase in the evening (0.32/0.38, 0.28/0.40, and 0.48/0.49). In conclusion, the parallel-group analysis proposed makes it possible for one to correct the trough-to-peak ratio for baseline as well as placebo, to account for interindividual variability, and to calculate a confidence interval for the net trough-to-peak ratio. Accounting for interindividual variability reduces the trough-to-peak ratio. Smoothing affects the individualized net trough-to-peak ratios in an unpredictable way and should therefore be avoided.

Ethacrynic acid disrupts steady state microtubules in vitro

PURPOSE

Ethacrynic acid (ECA) has been shown to increase facility of aqueous outflow in whole eyes and perfused anterior segments, to open up spaces between cells in the trabecular meshwork and inner wall of Schlemm's canal, and to cause separation and retraction of trabecular meshwork and endothelial cells in culture. One mechanism by which ECA has been proposed to act in cells is via disruption of microtubules, leading to cell retraction. Although it is known that ECA can inhibit de novo assembly of microtubules from tubulin subunits in vitro, we wanted to determine, as a better correlate to the proposed effect of ECA in cells, whether ECA could disrupt microtubule polymers that had reached steady state. We also wanted to determine whether calcium ion could enhance this process.

METHODS

We therefore assembled purified and crude porcine brain tubulin to steady state at 37 degrees C and then added ECA and/or calcium. Reaction kinetics were followed spectrophotometrically.

RESULTS

We found that ECA effectively disrupted assembled microtubules in vitro. Although 0.8-1.0 mM ECA was required to produce a half-maximal effect in pure tubulin microtubules and 0.2-0.3 mM ECA was necessary with crude microtubule protein, significant disassembly also occurred in the 0.01-0.2 mM range. Calcium had a greater maximal effect than ECA, and was more potent on a molar basis, showing half maximal effect between 2 and 12 microM free calcium ion. Combination experiments showed that ECA did not act synergistically with calcium to increase microtubule disassembly.

CONCLUSIONS

Our results are consistent with the proposed disruptive action of ECA on the assembled microtubules of outflow pathway cells, but do not support a rise in intracellular calcium as being an added factor.

Induction of apoptosis by diethylstilbestrol in hormone-insensitive prostate cancer cells

BACKGROUND

Diethylstillbestrol (DES) and diethylstilbestrol diphosphate (DESdP) are effective agents for the treatment of advanced prostate cancers. Tumor-inhibiting effects of DES and DESdP are presumed secondary to suppression of androgen production in vivo. Little is known, however, about the direct cellular mechanisms of the tumor inhibition. Estrogens have been reported not only to stimulate growth but also to disrupt microtubule formation in prostate cancer cells.

PURPOSE

The study was designed to examine and compare mechanisms of in vitro growth inhibition of DES and DESdP in human androgen-insensitive prostate cancer cells (DU145, 1-LN, and PC-3) and human androgen-sensitive prostate cancer cells (LNCaP) and to examine estrogen receptor modulation of such effects.

METHODS

The cytotoxic effects of DES and DESdP were examined in vitro by use of a standard microculture tetrazolium assay to quantitate numbers of viable cells. Immunofluorescence microscopy, DNA fragmentation analysis, and fluorescence flow cytometry were used to investigate microtubules, the induction of apoptosis, and changes in cell cycle distribution. The degree of estrogen receptor positivity of untreated and treated cells was determined by immunohistochemistry and quantitative image analysis.

RESULTS

LD50 levels (the dose at which 50% of cells are no longer viable) in the concentration range of 19-25 microM were observed for both DES and DESdP in all cell lines examined. DESdP-induced growth inhibition was found to be dependent on heat-labile phosphatases present in fetal calf serum. DES-induced cytotoxicity was not affected by the presence of 17 beta-estradiol, and it was not dependent on the presence of estrogen receptor. Estrogen receptor-positive cells and estrogen receptor-negative cells were equally responsive to DES. PC-3 cells stained with fluorescent anti-tubulin, phalloidin (actin stain), and 4',6-diamidino-2-phenylindole (DNA stain) showed no inhibition of microtubules or actin filaments but revealed the presence of apoptotic bodies in the nuclei. Fluorescence flow cytometry of nuclear DNA content of propidium iodide-stained nuclei from androgen-insensitive prostate cancer cells treated with 15 or 30 microM DES or DESdP revealed an increase in relative numbers of hypodiploid (apoptotic) nuclei, a depletion of G1- and S-phase cells, and an accumulation of cells in G2/M phase. Conversely, androgen-sensitive cells contained a lower percentage of hypodiploid nuclei but no accumulation of cells in G2/M phase.

CONCLUSIONS

Direct cytotoxic effects of DES in prostate cancer cells are estrogen receptor independent and do not involve disruption of microtubule architecture but do involve the promotion of cell cycle arrest and apoptosis. These are the first data confirming direct cytotoxic effects of DES and DESdP in prostate cancer cells via an apoptotic mechanism. IMPLICATIONS. These results suggest that DES and DESdP have potential value as agents against androgen-insensitive prostate neoplasms through induction of an apoptotic cascade.

Surgical principles and planning for the rheumatoid hand and wrist

Each surgical procedure available for the rheumatoid hand has a score card. The most indicated and necessary procedures include: extensor tenosynovectomy and Darrach for the impending or already ruptured extensor tendons; flexor tenosynovectomy and carpal tunnel release for the patient with impaired median nerve function; stabilization of the deformed unstable thumb with MP or IP arthrodesis; and flexor tenosynovectomy in the palm and finger of a motivated patient with significant disparity between active and passive motion. Relative indications for surgery include arthrodesis for the unstable wrist; MP arthroplasty for the fixed MP volar and ulnar subluxation with inability to open the hand; synovectomy for the occasional patient with painful boggy synovitis of the MP or PIP joint; and reconstruction of the fixed swan neck deformity with relatively good PIP joints. Both MP and PIP joints can and should be operated on at the same time. Extensive wrist surgery, that is, tenosynovectomy and Darrach or arthrodesis, should not be performed at the same time as MP arthroplasty. Try to do the "winner operations" first.

Dexamethasone inhibits trabecular cell retraction

Glucocorticosteroids such as dexamethasone (Dex) are known to cause an increased resistance to aqueous outflow in the intact and cultured eye. We investigated whether Dex treatment of cultured endothelial or trabecular meshwork (TM) cells might interfere with the cell separations and retraction induced by the facility-enhancing agents ethacrynic acid (ECA), cytochalasin B and the calcium chelator EGTA. Our hypothesis was that Dex-induced changes in the response of our model cells in vitro might serve as a paradigm for those produced in the cells of the outflow pathway, perhaps through influencing the changing dimensions of the pathway for aqueous humor through the juxtacanalicular tissue and/or inner wall of Schlemm's canal. We treated calf pulmonary artery endothelial (CPAE) and human and porcine TM cells with Dex (1-100 microns, 1-9 days), and then assessed monolayer and cytoskeletal integrity by immunofluorescence microscopy for tubulin and direct fluorescence staining for F-actin after exposure to the agents named above. We found that Dex-pretreated CPAE and TM cells gradually (over 5-7 days) became refractory to the effects of both ECA and EGTA, but not to cytochalasin B. Despite the preservation of general cell shape and attachment after ECA in Dex-treated cells, microtubule disruption still took place as in controls. Dex-treated cells also demonstrated a reorganization of filamentous actin staining after ECA and EGTA. Combination experiments of ECA and EGTA in Dex-treated cells suggested that the Dex effects were due to a greater strength of cell-to-cell and cell-to-substrate attachment, possibly due to interference with the normal cellular signaling required for coordinated cellular retraction and junctional disruption.

Ambulatory monitoring uncorrected for placebo overestimates long-term antihypertensive action. Systolic Hypertension in Europe (SYST-EUR) Trial Investigators

This study compares blood pressure (BP) changes during active antihypertensive treatment and placebo as assessed by conventional and ambulatory BP measurement. Older patients (> or = 60 years, n=337) with isolated systolic hypertension by conventional sphygmomanometry at the clinic were randomized to placebo or active treatment consisting of nitrendipine (10 to 40 mg/d), with the possible addition of enalapril (5 to 20 mg/d) and/or hydrochlorothiazide (12.5 to 25 mg/d). At baseline, clinic systolic/diastolic BP averaged 175/86 mm Hg and 24-hour and daytime ambulatory BPs averaged 148/80 and 154/85 mm Hg, respectively. After 13 months (median) of active treatment, clinic BP had dropped by 22.7/7.0 mm Hg and 24-hour and daytime BPs by 10.5/4.5 and 9.7/4.3 mm Hg, respectively (P<.001 for all). However, clinic (9.8/1.6 mm Hg), 24-hour (2.1/1.1 mm Hg), and daytime (2.9/1.0 mm Hg) BPs decreased also during placebo (P<.05, except for daytime diastolic BP); these decreases represented 43%/23%, 20%/24%, and 30%/23% of the corresponding BP fall during active treatment. After subtraction of placebo effects, the net BP reductions during active treatment averaged only 12.9/5.4, 8.3/3.4, and 6.8/3.2 mm Hg for clinic, 24-hour, and daytime BPs, respectively. The effect of active treatment was also subject to diurnal variation (P<.05). Changes during placebo in hourly systolic and diastolic BP means amounted to (median) 21% (range, -1% to 42%) and 25% (-3% to 72%), respectively, of the corresponding changes during active treatment. In conclusion, expressed in millimeters of mercury, the effect of antihypertensive treatment on BP is larger with conventional than with ambulatory measurement. Regardless of whether BP is measured by conventional sphygmomanometry or ambulatory monitoring, a substantial proportion of the long-term BP changes observed during active treatment may be attributed to placebo effects. Thus, ambulatory monitoring uncorrected for placebo or control observations, like conventional sphygmomanometry, overestimates BP responses in clinical trials of long duration.

The trough-to-peak ratio as an instrument to evaluate antihypertensive drugs. The APTH Investigators. Ambulatory Blood Pressure and Treatment of Hypertension Trial

The U.S. Food and Drug Administration designed the trough-to-peak ratio as an instrument for the evaluation of long-acting antihypertensive drugs, but the ratios are usually reported without accounting for interindividual variability. This study investigated how the trough-to-peak ratio would be affected by interindividual and intraindividual variability and by smoothing of the diurnal blood pressure profiles. The ambulatory blood pressure was recorded on placebo in 143 hypertensive patients (diastolic pressure on conventional measurement > 95 mm Hg). After 2 months, the recordings were repeated on 10 mg (n = 66) or 20 mg (n = 77) lisinopril given once daily between 7 and 11 PM. The baseline-adjusted trough-to-peak ratios were determined from diurnal blood pressure profiles with 1-hour precision. Lisinopril reduced (+/- SD) the 24-hour pressure by 16 +/- 17 mm Hg for systolic and 10 +/- 10 mm Hg for diastolic (P < .001). According to the usual approach, disregarding interindividual variability, the trough-to-peak ratio was 0.72 for systolic pressure and 0.67 for diastolic pressure. In the 143 patients the ratios were not normally distributed. They were the same on both lisinopril doses. When interindividual variability was accounted for, the median trough-to-peak ratio was 0.34 (P5 to P95 interval, -0.46 to 0.87) for systolic pressure and 0.26 (-0.44 to 0.84) for diastolic pressure. In 66 patients examined twice on 10 mg lisinopril at a median interval of 32 days, the trough-to-peak ratios were characterized by large intraindividual variability.(ABSTRACT TRUNCATED AT 250 WORDS)

A method of quantifying retinal microvascular alterations associated with blood pressure and age

OBJECTIVE

To find an objective, sensitive method for quantifying microvascular alterations associated with level of blood pressure and age.

DESIGN

A prospective cross-sectional study.

SUBJECTS AND METHODS

Seventy-four previously untreated hypertensive patients, referred to a hospital outpatients department, and 26 normotensive volunteers participated. Twenty-four-hour ambulatory blood pressure monitoring and bilateral fundal photography were performed. The fundal photographs were projected on a screen such that the optic disc filled a circle of radius 5 cm. Microvessels crossing the border of a concentric circle of radius 20 cm were identified as arteriolar or venular, counted and their luminal diameters measured.

MAIN OUTCOME MEASURES

Arteriolar and venular numbers, mean diameters and vascularities (arteriolar and venular vascularities defined as the sum of arteriolar and venular diameters, respectively).

RESULTS

The technique was reproducible. As blood pressure increased, arteriolar vascularity declined and venular vascularity increased. These associations resulted in a strong inverse correlation between blood pressure level and the ratio arteriolar vascularity: venular vascularity (r = 0.48, P < 0.001). Arteriolar number declined with increasing diastolic blood pressure (r = 0.22, P < 0.05). Mean arteriolar diameter appeared to have a U-shaped relationship with diastolic blood pressure levels (r = 0.27, P < 0.05). Venular dilation was associated with increasing blood pressure levels (r = 0.22, P < 0.05). Mean arteriolar and venular diameters declined significantly with age (r = 0.33 and 0.26, respectively; P < 0.01) and there was no association between arteriolar vascularity:venular vascularity ratio and age.

CONCLUSIONS

The method detected disparate retinal microvascular alterations with age and blood pressure. The arteriolar vascularity:venular vascularity ratio shows promise as a non-invasive, prognostic and therapeutic guide in hypertension.

Clinical trials with ambulatory blood pressure monitoring: fewer patients needed? Syst-Eur Investigators

We have tested the concept that fewer patients are needed in trials of antihypertensive treatment if blood pressure is measured by ambulatory monitoring rather than by conventional sphygmomanometry. 233 patients (> or = 60 years old) with isolated systolic hypertension were randomly allocated placebo (n = 119) or active treatment (n = 114). Blood pressure measurements were compared by Wilcoxon's test and blood pressure profiles by ANOVA. With either method of measurement, the same number of patients (40 in each treatment group) was required to show a reduction after 1 year in clinic (13/8 mm Hg) or average blood pressure over 24 h (9/5 mm Hg). To detect that the decrease in systolic pressure was not steadily maintained through the day, 40 patients in each treatment group were needed for blood pressure profiles made up of 4-hourly or 2-hourly means and 60 for profiles of 1-hourly means. For diastolic pressure, the corresponding numbers were 80, 100, and more than the number of available patients, respectively. We conclude that parallel-group trials focusing on the average blood pressure over 24 h, rather than on conventionally measured blood pressure, cannot economise on sample size. Moreover, trials studying the full course of blood pressure throughout the day, require more--not fewer--patients than studies of only the conventional or average 24 h blood pressure.

Ambulatory pressure decreases on long-term placebo treatment in older patients with isolated systolic hypertension. Syst-Eur Investigators

OBJECTIVE

This long-term study investigated the widely accepted hypothesis that ambulatory pressure does not decrease in patients given placebo.

METHODS

One hundred and twelve older (> or = 60 years) outpatients with isolated systolic hypertension were recruited. Treatment consisted of a placebo during a 3-month baseline period and long-term follow-up.

RESULTS

At baseline, on placebo treatment, clinic systolic/diastolic (SBP/DBP) blood pressure (+/- SD) averaged 176 +/- 12/86 +/- 7 mmHg and 24-h SBP/DBP 151 +/- 15/81 +/- 10 mmHg. These pressures were unaltered in 51 patients in whom the baseline measurements were repeated after a further month on placebo. After the 112 patients had received placebo for 1 year (median), clinic SBP/DBP fell by 6.6 +/- 15.9 (P < 0.001)/1.4 +/- 7.4 (P = 0.06)mmHg and 24-h SBP by 2.4 +/- 10.7 mmHg (P < 0.05), whereas 24-h DBP did not change significantly. The 24-h SBP decreased more with higher baseline level and longer follow-up (5-21 months).

CONCLUSIONS

These findings in older patients with isolated systolic hypertension suggest that in long-term studies the ambulatory pressure may slightly but significantly decrease on a placebo. Like those using conventional sphygmomanometry, long-term studies using non-invasive ambulatory monitoring require a placebo-controlled design.

A consistent reference frame for ambulatory blood pressure monitoring is found in different populations

This study investigated the consistency of a reference frame for ambulatory pressure monitoring, which using various approaches was determined in two different populations. The two reference groups were 718 subjects randomly selected from the population and 895 bank employees. The reference values derived in these two groups were subsequently tested in 591 untreated hypertensive patients. The ambulatory pressures equivalent to a conventional pressure of 140 mmHg systolic and 90 mmHg diastolic were calculated by regression analysis in all subjects. In addition, in subjects who were normotensive by conventional sphygmomanometry, the mean +2 and +3 standard deviations and the 90th, 95th and 99th percentiles of the ambulatory measurements were determined. The distributions of the ambulatory measurements were similar in the two reference groups and the aforementioned parameters therefore agreed within 4 mmHg in the two populations. There was considerable overlap in the ambulatory pressures between the two reference groups and the hypertensive patients. Classification of the patients according to the means +3 standard deviations and the regression limits gave the same results because in both reference groups these boundaries approximated to each other within 1 mmHg. For the 24 h pressures in the population sample these boundaries were 140 mmHg systolic and 88 mmHg diastolic. Of the patients with systolic hypertension (> or = 160 mmHg on conventional measurement), 39% had a 24 h systolic pressure of < 140 mmHg and of those with diastolic hypertension (> or = 95 mmHg), 44% had a 24 h diastolic pressure of < 88 mmHg; if the corresponding boundaries derived in the bank employees (143/90 mmHg) were applied, these proportions were 47% and 44%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Short report: ambulatory blood pressure in normotensive compared with hypertensive subjects. The Ad-Hoc Working Group

OBJECTIVE

To delineate more precisely an operational threshold for making clinical decisions based on ambulatory blood pressure (ABP) measurement by studying the ABP in subjects who were diagnosed as either normotensive or hypertensive by conventional blood pressure (CBP) measurement.

SUBJECTS

Twenty-four research groups recruited 7069 subjects. Of these, 4577 were normotensive (CBP < or = 140/90 mmHg), 719 were borderline hypertensive (systolic CBP 141-159 mmHg or diastolic CBP 91-94 mmHg) and 1773 were definitely hypertensive. Of the subjects in the last of these categories, 1324 had systolic hypertension (systolic CBP > or = 160 mmHg) and 1310 had diastolic hypertension (diastolic CBP > or = 95 mmHg). Hypertension had been diagnosed from the mean of two to nine (median two) CBP measurements obtained at one to three (median two) visits.

RESULTS

The 95th centiles of the 24-h ABP distributions in the normotensive subjects were (systolic and diastolic, respectively) 133 and 82 mmHg. Of the subjects with systolic hypertension, 24% had 24-h systolic ABP < 133 mmHg. Similarly, 30% of those with diastolic hypertension had 24-h diastolic ABP < 82 mmHg. The probability that hypertensive subjects had 24-h ABP below these thresholds tended to increase with age and was two- to fourfold greater if the CBP of the subject had been measured at only one visit and if fewer than three CBP measurements had been averaged for establishing the diagnosis of hypertension. By contrast, for each 10-mmHg increment in systolic CBP, this probability decreased by 54% for 24-h systolic ABP and by 26% for 24-h diastolic ABP, and for each 5-mmHg increment in diastolic CBP it decreased by 6 and 9%, respectively.

CONCLUSIONS

The ABP distributions of the normotensive subjects included in the present international database were not materially different from those in previous reports in the literature. One-fifth to more than one-third of hypertensive subjects had an ABP which was below the 95th centile of the ABP of normotensive subjects, but this proportion decreased if the hypertensive subjects had shown a higher CBP upon repeated measurement. The prognostic implications of elevated CBP in the presence of normal ABP remain to be determined.

Twenty-four hour blood pressure monitoring in the Syst-Eur trial

This article describes the objectives and protocol of a study on ambulatory blood pressure in elderly patients with isolated systolic hypertension. This study constitutes an optional side-project to the Syst-Eur trial. The multicentre Syst-Eur trial investigates whether antihypertensive treatment of elderly patients with isolated systolic hypertension will influence the incidence of stroke. Secondary endpoints include cardiovascular events, such as myocardial infarction. The main objective of the side-project is to investigate whether ambulatory blood pressure monitoring will improve the prediction of cardiovascular complications based on blood pressure measurement in the clinic. The side-project also provides the opportunity to evaluate the diurnal profile of blood pressure in elderly patients with isolated systolic hypertension randomized to placebo or active antihypertensive treatment.