Pharmacoepigenetics of hypertension: genome-wide methylation analysis of responsiveness to four classes of antihypertensive drugs using a double-blind crossover study design

Essential hypertension remains the leading risk factor of global disease burden, but its treatment goals are often not met. We investigated whether DNA methylation is associated with antihypertensive responses to a diuretic, a beta-blocker, a calcium channel blocker or an angiotensin receptor antagonist. In addition, since we previously showed an SNP at the transcription start site (TSS) of the catecholamine biosynthesis-related ACY3 gene to associate with blood pressure (BP) response to beta-blockers, we specifically analysed the association of methylation sites close to the ACY3 TSS with BP responses to beta-blockers. We conducted an epigenome-wide association study between leukocyte DNA methylation and BP responses to antihypertensive monotherapies in two hypertensive Finnish cohorts: the GENRES (https://clinicaltrials.gov/ct2/show/NCT03276598; amlodipine 5 mg, bisoprolol 5 mg, hydrochlorothiazide 25 mg, or losartan 50 mg daily) and the LIFE-Fin studies (https://clinicaltrials.gov/ct2/show/NCT00338260; atenolol 50 mg or losartan 50 mg daily). The monotherapy groups consisted of approximately 200 individuals each. We identified 64 methylation sites to suggestively associate (P < 1E-5) with either systolic or diastolic BP responses to a particular study drug in GENRES. These associations did not replicate in LIFE-Fin . Three methylation sites close to the ACY3 TSS were associated with systolic BP responses to bisoprolol in GENRES but not genome-wide significantly (P < 0.05). No robust associations between DNA methylation and BP responses to four different antihypertensive drugs were identified. However, the findings on the methylation sites close to the ACY3 TSS may support the role of ACY3 genetic and epigenetic variation in BP response to bisoprolol.

Effects of Randomized Controlled Infancy-Onset Dietary Intervention on Leukocyte Telomere Length-The Special Turku Coronary Risk Factor Intervention Project (STRIP)

Reduced telomere length (TL) is a biological marker of aging. A high inter-individual variation in TL exists already in childhood, which is partly explained by genetics, but also by lifestyle factors. We examined the influence of a 20-year dietary/lifestyle intervention on TL attrition from childhood to early adulthood. The study comprised participants of the longitudinal randomized Special Turku Coronary Risk Factor Intervention Project (STRIP) conducted between 1990 and 2011. Healthy 7-month-old children were randomized to the intervention group (n = 540) receiving dietary counseling mainly focused on dietary fat quality and to the control group (n = 522). Leukocyte TL was measured using the Southern blot method from whole blood samples collected twice: at a mean age of 7.5 and 19.8 years (n = 232; intervention n = 108, control n = 124). Yearly TL attrition rate was calculated. The participants of the intervention group had slower yearly TL attrition rate compared to the controls (intervention: mean = −7.5 bp/year, SD = 24.4 vs. control: mean = −15.0 bp/year, SD = 30.3; age, sex and baseline TL adjusted β = 0.007, SE = 0.004, p = 0.040). The result became stronger after additional adjustments for dietary fat quality and fiber intake, serum lipid and insulin concentrations, systolic blood pressure, physical activity and smoking (β = 0.013, SE = 0.005, p = 0.009). A long-term intervention focused mainly on dietary fat quality may affect the yearly TL attrition rate in healthy children/adolescents.

Leukocyte telomere length is inversely associated with arterial wave reflection in 566 normotensive and never-treated hypertensive subjects

Telomeres are short segments in chromosome ends, the length of which is reduced during cell lifecycles. We examined the association of mean leukocyte telomere length (LTL) and short telomere proportion (STP) with hemodynamic variables in normotensive and never-treated hypertensive volunteers (n=566, 19-72 years). STP and mean LTL were determined using Southern blotting, and supine hemodynamics recorded using continuous tonometric pulse wave analysis and whole-body impedance cardiography. The analyses were adjusted for age, body mass index (BMI), alcohol use, smoking, plasma chemistry, and estimated glomerular filtration rate (eGFR). In univariate analyses, mean LTL and STP both correlated with age, BMI, eGFR, aortic blood pressure, augmentation index, and pulse wave velocity (p<0.05 for all). Mean LTL also correlated with systemic vascular resistance (p<0.05). In linear regression analyses of all hemodynamic variables, mean LTL was only an independent explanatory factor for augmentation index (Beta -0.006, p=0.032), while STP was not an explanatory factor for any of the hemodynamic variables, in contrast to age, BMI and several cardiovascular risk factors. To conclude, augmentation index was predominantly related with chronological aging, but also with mean LTL, suggesting that this variable of central wave reflection is a modest marker of vascular biological aging.

Genome-Wide Meta-Analysis of Blood Pressure Response to β1-Blockers: Results From ICAPS (International Consortium of Antihypertensive Pharmacogenomics Studies)

BackgroundThere exists a wide interindividual variability in blood pressure (BP) response to β₁-blockers. To identify the genetic determinants of this variability, we performed a pharmacogenomic genome-wide meta-analysis of genetic variants influencing β₁-blocker BP response.Methods and ResultsGenome-wide association analysis for systolic BP and diastolic BP response to β₁-blockers from 5 randomized clinical trials consisting of 1254 patients with hypertension of European ancestry were combined in meta-analysis and single nucleotide polymorphisms (SNPs) with P<10^-4 were tested for replication in 2 independent randomized clinical trials of β₁-blocker-treated patients of European ancestry (n=1552). Regions harboring the replicated SNPs were validated in a β₁-blocker-treated black cohort from 2 randomized clinical trials (n=315). A missense SNP rs28404156 in BST1 was associated with systolic BP response to β₁-blockers in the discovery meta-analysis (P=9.33×10^-5, β=-3.21 mm Hg) and replicated at Bonferroni significance (P=1.85×10^-4, β=-4.86 mm Hg) in the replication meta-analysis with combined meta-analysis approaching genome-wide significance (P=2.18×10^-7). This SNP in BST1 is in linkage disequilibrium with several SNPs with putative regulatory functions in nearby genes, including CD38, FBXL5, and FGFBP1, all of which have been implicated in BP regulation. SNPs in this genetic region were also associated with BP response in the black cohort.ConclusionsData from randomized clinical trials of 8 European ancestry and 2 black cohorts support the assumption that BST1 containing locus on chromosome 4 is associated with β₁-blocker BP response. Given the previous associations of this region with BP, this is a strong candidate region for future functional studies and potential use in precision medicine approaches for BP management and risk prediction.

Effect of hydrochlorothiazide on serum uric acid concentration: a genome-wide association study

AIM

To recognize genetic associations of hydrochlorothiazide-induced change in serum uric acid (SUA) concentration.

PATIENTS & METHODS

We conducted a genome-wide association study on hydrochlorothiazide-induced change in SUA in 214 Finnish men from the GENRES study. Replication analyses were performed in 465 Finns from the LIFE study.

RESULTS

In GENRES, we identified 31 loci associated with hydrochlorothiazide-induced change in SUA at p < 5 × 10^-5. rs1002976 near VEGFC associated with the change in GENRES and in LIFE. rs950569 near BRINP3 associated with the change in SUA in GENRES and LIFE. The analysis of previously reported SNPs and candidate genes provided some proof for PADI4 and ABCC4.

CONCLUSION

We report genetic markers that may predict the increase in SUA concentration during thiazide treatment.

Replicated evidence for aminoacylase 3 and nephrin gene variations to predict antihypertensive drug responses

Aim: To replicate the genome-wide associations of the antihypertensive effects of bisoprolol and losartan in GENRES, using the Finnish patients of LIFE study. Patients & methods: We analyzed association of four SNPs with atenolol and three SNPs with losartan response in 927 Finnish LIFE patients (467 for atenolol and 460 for losartan). Results: rs2514036, a variation at a transcription start site of ACY3, was associated with blood pressure response to atenolol in men in LIFE. Response to bisoprolol was correlated to baseline plasma levels of N-acetylphenylalanine and phenylalanine (ACY3 substrate and end product, respectively) in GENRES study. NPHS1 variation rs3814995 was associated with losartan effect in LIFE. Conclusion: We provide support for two pharmacogenomic markers for beta-blockers and angiotensin receptor antagonists.

Leucocyte telomere length in age-related macular degeneration

PURPOSE

To evaluate the association between telomere length and age-related macular degeneration (AMD).

METHODS

Circulating leucocyte telomere length and the proportion of telomeres <5 kb were analysed in blood DNA samples taken from 121 patients with exudative AMD (83%), large drusen (14%) or central geographic atrophy (3%). Controls consisted of 77 age-matched subjects without AMD. The AMD status was assessed by a masked analysis of fundus photographs or angiographs. Telomere length was measured by Southern blotting.

RESULTS

Mean (SD) telomere length was 7.76 kb (0.68) in AMD patients and 7.83 (0.69) in controls (p = 0.485). The corresponding proportions of telomeres <5 kb were 10.60 (2.76) and 10.05 (2.64) (p = 0.197). In this material, there was no correlation between telomere length and age, gender or smoking status. There were no differences between the major AMD risk single-nucleotide polymorphisms (SNPs) of the CFH, HTRA1 or C3 genes, expect for somewhat longer telomeres in controls with the C3 risk SNP. There were no differences in telomere length between patients with drusen or exudative AMD.

CONCLUSIONS

Telomere length is not associated with exudative AMD or high-risk drusen.

Telomere length and cardiovascular aging

Telomeres are located at the end of chromosomes. They are composed of repetitive TTAGGG tandem repeats and associated proteins of crucial importance for telomere function. Telomeric DNA is shortened by each cell division until a critical length is achieved and the cell enters senescence and eventually apoptosis. Telomeres are therefore considered a 'biological clock' of the cell. Telomerase adds nucleotides to telomeric DNA thereby contributing to telomere maintenance, genomic stability, functions, and proliferative capacity of the cell. In certain rare forms of progeria, point mutations within the telomere lead to accelerated telomere attrition and premature aging. Endogenous factors causing telomere shortening are aging, inflammation, and oxidative stress. Leukocyte telomere length (LTL) shortening is inhibited by estrogen and endogenous antioxidants. Accelerated telomere attrition is associated with cardiovascular risk factors such as age, gender, obesity, smoking, sedentary life-style, excess alcohol intake, and even mental stress. Cardiovascular (CV) diseases and CV aging are usually but not invariably associated with shorter telomeres than in healthy subjects. LTL appears to be a biomarker of CV aging, reflecting the cumulative burden of endogenous and exogenous factors negatively affecting LTL. Whether accelerated telomere shortening is cause or consequence of CV aging and disease is not clear.

Telomere length and progression of diabetic nephropathy in patients with type 1 diabetes

OBJECTIVES

To determine whether short telomere length of blood leucocytes from patients with type 1 diabetes is associated with or predictive of progression of diabetic nephropathy.

DESIGN AND METHODS

Two consecutive DNA samples were obtained from 132 patients from the nationwide Finnish Diabetic Nephropathy Study with type 1 diabetes. Control DNA samples were taken from 44 healthy blood donors. Telomere length was measured by Southern blot. Patients were divided into three groups according to their urinary albumin excretion rate (AER): 48 patients with normoalbuminuria (AER < 20 microg min(-1)); seven patients with microalbuminuria (AER > or = 20 microg min(-1) <200 microg min(-1)) and 77 patients with macroalbuminuria (AER > or = 200 microg min(-1)). Progression was defined as a change in albuminuria to a higher level.

RESULTS

Progression occurred in 21 patients. Progressors had shorter mean telomere length (8.1 +/- 0.7 kb, mean +/- SD; P = 0.017) and higher percentage of short telomeres (32.0 +/- 8%, P = 0.002) than nonprogressors (8.5 +/- 0.7 kb and 27 +/- 7.2%, respectively). Thus, both shorter telomeres (HR = 0.190, 95%CI 0.065-0.558, P = 0.0025) and higher proportion of short telomeres (HR = 1.115, 1.039-1.195, P =0.0023) were independent predictors of diabetic nephropathy. Telomere length was not associated with the degree of albuminuria and was not different in patients with type 1 diabetes compared with healthy controls.

CONCLUSIONS

Short telomeres are independent predictors of progression of diabetic nephropathy in patients with type 1 diabetes.

Predictors of cardiovascular events in patients with hypertension and left ventricular hypertrophy: the Losartan Intervention for Endpoint reduction in hypertension study

OBJECTIVE

We assessed readily available patient characteristics, including albuminuria (not included in traditional cardiovascular risk scores), as predictors of cardiovascular events in hypertension with left ventricular hypertrophy (LVH) and developed risk algorithms/scores for outcomes.

METHODS

The Losartan Intervention For Endpoint reduction in hypertension (LIFE) study compared effects of losartan-based versus atenolol-based therapy on cardiovascular events in 9193 patients with hypertension and LVH. Univariate and multivariate analyses identified baseline variables with significant impact on development of the primary composite endpoint (cardiovascular death, stroke and myocardial infarction) and its components. Multivariate analysis used a Cox regression model with stepwise selection process. Risk scores were developed from coefficients of risk factors from the multivariate analysis, validated internally using naïve and jack-knife procedures, checked for discrimination and calibration, and compared with Framingham coronary heart disease and other risk scores.

RESULTS

LIFE risk scores showed increasing endpoint rates with increasing quintile (first to fifth quintile, composite endpoint 2.8-26.7%, cardiovascular death 0.5-14.4%, stroke 1.2-11.3%, myocardial infarction 1.4-8.1%) and were confirmed with a jack-knife approach that adjusts for potentially optimistic bias. The Framingham coronary heart disease and other risk scores overestimated risk in lower risk patients and underestimated risk in higher risk patients, except for myocardial infarction.

CONCLUSION

A number of patient characteristics predicted cardiovascular events in patients with hypertension and LVH. Risk scores developed from these patient characteristics, including albuminuria, strongly predicted outcomes and may improve risk assessment of patients with hypertension and LVH and planning of clinical trials.

Raised Plasma Concentrations of Endothelin-1 and -3 in Marmosets with Acute Aortic Stenosis: No Relation to the Renin-angiotensin System

Plasma levels of endothelin (ET), plasma renin activity (PRA) and angiotensin II (Ang II) were measured in anaesthetized marmosets exposed to acute aortic stenosis proximal to the renal arteries. In vehicle experiments, ET rose from 5 +/- 2 to 38 +/- 4 pg ml-1, PRA from 5 +/- 2 to 99 +/- 21 ng ml-1 h-1 and Ang II from 21 +/- 4 to 213 +/- 76 pg ml-1. Administration of renin inhibitor and angiotensin converting enzyme inhibitor reduced PRA and Ang II to control levels, while the plasma levels of ET increased further (51 +/- 10 and 71 +/- 16 pg ml-1, respectively). During aortic stenosis the two isoforms ET-1 and ET-3 appeared in the circulation, while in conscious control animals only ET-1 was found. It is concluded that the increased plasma levels of ET in our primate model could not be ascribed to the increased circulating levels of PRA and Ang II.

Endothelin Converting Enzyme (ECE) Activity in Normal Pregnancy and Preeclampsia

OBJECTIVE

Enhanced production of endothelin-1, due to endothelial cell dysfunction has been considered to be the cause of increased plasma levels of endothelin-1 in preeclampsia. The present study was aimed at analyzing endothelin-converting-enzyme activity, (which reflect the production rate of endothelin-1 (ET-1) from big endothelin-1 (big ET-1)), big endothelin-1, and endothelin-1 concentrations from women with preeclampsia compared to normal pregnant women. Moreover, we analyzed plasma levels of these substances longitudinally throughout normal pregnancy.

STUDY DESIGN

Twenty-nine pregnant healthy women were recruited to the study. Blood samples were obtained at 18, 28, and 38 weeks gestation and six weeks postpartum. Twenty-seven women with preeclampsia were included. Blood samples were taken at diagnosis (average 35 weeks gestation; range 27-39 weeks) and six weeks postpartum. Endothelin-1 was analyzed by enzyme linked immunoassay (ELISA) and big-ET-1 by radioimmunoassay (RIA). Endothelin-converting-enzyme activity was measured using big endothelin-1 as a substrate and thiorphan as an inhibitor of serum neutral endopeptidase. The amount of endothelin-1 generated during one hour was measured by RIA. Mean +/- SEM is given.

RESULTS

In normal pregnancy endothelin-1 concentrations at 38 weeks and postpartum were increased by 30% (p < 0.01) and 50% (p < 0.001), respectively compared with the second trimester values. Endothelin-converting-enzyme activity did not change. At diagnosis endothelin-1 was higher in women with preeclampsia than in the controls at 38 weeks (0.96 +/- 0.07 vs. 0.64 +/- 0.06 pmol/L; p < 0.001). Likewise, endothelin-converting-enzyme activity was higher in the preeclampsia group (222 +/- 15 vs. 172 +/- 8 pmol ET/ml/h; p < 0.01). This difference remained at six weeks postpartum.

CONCLUSION

Our findings imply enhanced ET-1 production in preeclampsia. The elevated endothelin-converting-enzyme activity postpartum may indicate an inherent endothelial dysfunction predisposing to preeclampsia or that preeclampsia may cause irreversible changes in endothelial function.

Phosphate binding by a myeloma protein

A patient with IgG kappa myeloma had markedly elevated serum phosphate concentrations but no clinical features of hyperphosphataemia. The hyperphosphataemia was due to a high phosphate per protein unit than normal IgG.

Plasma atrial natriuretic peptide in cardiac transplant recipients. A prospective study

Cardiac transplantation in 10 patients with congestive heart failure resulted in reduction of high plasma concentrations of atrial natriuretic peptide (ANP), preoperatively five-fold above normal, to a level two-fold above normal, which was maintained throughout a 12-week follow-up period. Cardiac function was normalized in all patients. Transient increases in plasma ANP, in four cardiac recipients 3-10-fold their basal levels, could neither be related to rejection episodes nor to cardiac dysfunction, but rather to signs of fluid and sodium retention. High plasma ANP levels in cardiac transplant recipients suggest that the capacity to secrete ANP is preserved in the transplanted heart.

Erythropoietin and renin substrate in cerebellar haemangioblastoma

We examined eight cerebellar haemangioblastoma tumours from eight patients, aged 16-63 years, 5 females and 3 males. Preoperative haemoglobin values exceeded 180 g/l in four patients, and 150 g/l in four. All high Hb values were normalized upon surgical removal of the tumours. All tumours contained scattered cells which stained positively with antisera against pure human urinary erythropoietin and plasma renin substrate. We conclude that cerebellar haemangioblastomas produce immunoreactive erythropoietin, which shares common antigenic determinants with renin substrate.

The syndrome of inappropriate secretion of antidiuretic hormone. A case report

A 72-year-old woman with the syndrome of inappropriate secretion of antidiuretic hormone of unknown cause during more than one year of observation is reported. Plasma vasopressin levels were excessively elevated, even during a water load test. Her serum electrolyte abnormalities and general state were ameliorated after fluid restriction. During treatment with demeclocycline the patient was able to increase fluid without deterioration.

Competitive inhibitor binding assay (CIBA) of ACE inhibitors

We describe a new principle for measuring concentrations of pharmacologically active captopril or other angiotensin-converting enzyme (ACE) inhibitors in blood. Serum is incubated with 125-I-labeled ACE inhibitor (substance 351A, a lisinopril analogue, Merck Sharp & Dohme) in a nonequilibrated system, in which label and ACE inhibitor compete for binding to added serum ACE. Free label is separated by adsorption to coated charcoal. Concentration of captopril or other ACE inhibitor is calculated from a standard curve. Results in healthy volunteers showed rapid absorption of captopril with maximal concentration of active drug within 1 h, and fast disappearance within 2.5 h. Stability of captopril was improved by immediate 1:100 dilution of blood samples with assay buffer. In spite of this precaution, analysis should be performed within two days to avoid loss of active drug due to polymerization and protein binding. Samples of other tested ACE inhibitors can be frozen and later analyzed at convenience. The new principle is simple, sensitive, and specific.

Blood pressure and renin during treatment with pindolol

Beta-receptor blocking drugs are known to decrease BP and plasma renin activity (PRA) in hypertensive patients. We treated 31 hypertensive patients with the beta-receptor blocking drug, pindolol, for 3 months. During the first month (mean daily dose 10 mg) and the second month (mean daily dose 14.2 mg) BP and PRA decreased. During the third month of pindolol therapy (mean daily dose 19.0 mg) 16 patients had an unexpected rise of BP towards control levels and PRA levels rose, too. The remaining 15 patients maintained a good antihypertensive drug effect and suppression of PRA. Pretreatment PRA was not related to BP reduction. The change in diastolic BP was not significantly related to that in PRA. The results indicate that low doses of pindolol,10-15 mg daily, will suffice in mild essential hypertension. An increasing frequency of partial drug resistance may be a result of unnecessarily high doses of pindolol.

A long-term follow-up of patients with essential hypertension treated with captopril

Seventy-four patients from four short-term studies of captopril in mild-moderate essential hypertension continued in a cooperative long-term efficacy and tolerance program. The duration of observation is 2- greater than 4 years, the total treatment time being 2434 months. No development of resistance to therapy was observed. The total daily dose of captopril has been gradually decreased and in 20 patients changed from t.i.d. to b.i.d. regime. The drug has been well tolerated and only few and mild side-effects have been observed after the initial titration period. The drop-outs (n = 19) were mostly due to non-medical causes (n = 14). Except for one case of proteinuria, no laboratory abnormalities were detected and there were no signs of long-term toxicity.

Systemic manifestations and enzyme studies in sarcoidosis with neurologic involvement

The dissemination and activity of systemic disease was evaluated retrospectively in 50 patients with neurosarcoidosis, 24 of whom presented with neurologic symptoms. During follow-up, five patients never developed detectable systemic disease. In 26 patients, sarcoidosis had previously been diagnosed, but in 11 (42%) of them the neurologic symptoms were initially not connected with this disease. During follow-up, extraneural features were those of sarcoidosis in general. However, 23 patients (46%) had normal chest X-ray on admission to neurologic examinations. Fourteen (35%) of 40 examined patients had ocular changes, 13 (33%) of 39 hypercalciuria and 13 (26%) of 50 skin manifestations. Serum angiotensin converting enzyme (ACE) was elevated in only 31% of the patients. Measureable amounts of ACE were recorded in the cerebrospinal fluid from 13 of 17 examined patients. During follow-up the activity of neurosarcoidosis seemed to be linked to the course of systemic disease in general.

Antidiuretic hormone and atrial natriuretic peptide in congestive heart failure

Plasma concentrations of antidiuretic hormone (ADH) were measured in 8 patients with congestive heart failure (CHF) of NYHA functional class III-IV, before and during treatment with captopril, 6.25-25.0 mg t.i.d., added to their drug regimen. Before captopril treatment, plasma ADH was high, 2.5 times the upper limit of normal reference values. During treatment with captopril, plasma ADH levels were normalized, and remained so throughout the study, for at least 6 months. Plasma levels of angiotensin II were also reduced to a normal level. Reduction of plasma ADH during captopril treatment in CHF may partly depend on reduced angiotensin II formation, and may be beneficial by improving water balance. Atrial natriuretic peptide (ANP), was measured by radioimmunoassay in 17 patients with CHF. The highest levels were measured in the most severe CHF cases, and intermediate high values on NYHA functional class I-II patients. Plasma ANP concentrations in control patients (n = 18) without cardiac diseases ranged between 0 and 30 pg/ml. In two patients with paroxysmal supraventricular tachycardia, associated with transient polyuria, high plasma ANP concentrations were noticed during tachycardic episodes. Thus, ANP appears to be a circulating hormone in humans, and is released into the blood in clinical conditions associated with raised preload and atrial wall stretch.

Thyroid hormones affect serum angiotensin I converting enzyme levels

Serum angiotensin I converting enzyme (ACE) was measured in 10 patients with Graves' disease and 2 with thyroiditis during different stages of the diseases. The effect of thyroxine on serum ACE levels was also recorded in 12 patients with thyroid cancer, who were on thyroxine suppression. Serum ACE levels correlated positively with clinically assessed thyroid function and peripheral thyroid hormone levels, especially during hyper- or hypofunction. ACE was measured both with an enzyme kinetic and a new, quantitative inhibitor binding assay. The methods gave similar results, which indicates that ACE increments during thyroid hyperfunction were quantitative, and not a result of increased enzyme activity. Serum ACE increments associated with high lysozyme concentrations are signs of immunologic activation or proliferation of monocytic cells. In this study there was no correlation between the two enzymes, which may indicate either increased synthesis or possibly shedding of ACE from endothelial cells or delayed metabolic clearance of this enzyme. Serum ACE measurements may provide a useful tool for assessing thyroid function and the effect of thyroxine treatment.

Sustained antihypertensive effect of captopril combined with diuretics and beta-adrenergic blocking drugs in patients with resistant hypertension

Ten patients with severe hypertension and unsatisfactory blood pressure control during combined therapy with beta-adrenergic blocking drugs, diuretics, and vasodilators were treated with gradually increasing doses of captopril. Vasodilators were discontinued 24 hours prior to captopril administration. Six patients had essential, two renal, and two renovascular hypertension. Mild renal impairment was observed in four patients. Captopril effectively decreased blood pressure for 3 hours in all patients after the first dose. The antihypertensive effect appeared to be triphasic and was sustained in all but one patient during 12 months of observation. Captopril doses of 25-75 mg t.i.d. were sufficient to achieve acceptable blood pressure control (RR less than or equal to 160/100 mmHg) when given in the above mentioned combination. Side-effects were few and tolerable and discontinuation of captopril was not required.

Long-term 1,25-dihydroxycholecalciferol treatment in renal failure

1,25-Dihydroxycholecalciferol (1,25-DHCC) was administered to four patients on maintenance hemodialysis and to four patients with renal failure not requiring hemodialysis. Secondary hyperparathyroidism was found in both groups of patients. Before initiation of 1,25-DHCC treatment both groups had serum 1,25-DHCC levels below the normal range (33.1 +/- 15.3 pg/ml). During the treatment period, serum 1,25-DHCC concentrations were normalized. Parathormone concentration in serum decreased in both groups during the observation period. Serum calcium concentration was normalized in patients with renal failure and within the upper normal range in patients on maintenance hemodialysis. Bone biopsy and densitometry, of the radius showed a trend towards normalization of bone during the treatment period, while X-ray studies showed no clear effect of 1,25-DHCC treatment. This study shows that changes in bone mineralization can be reversed by normalization of 1,25-DHCC.

Renin-angiotensin system revisited

New components and functions of the renin-angiotensin system (RAS) are still being unravelled. The classical RAS as it looked in the middle 1970s consisted of circulating renin, acting on angiotensinogen to produce angiotensin I, which in turn was converted into angiotensin II (Ang II) by angiotensin-converting enzyme (ACE). Ang II, still considered the main effector of RAS was believed to act only as a circulating hormone via angiotensin receptors, AT1 and AT2. Since then, an expanded view of RAS has gradually emerged. Local tissue RAS systems have been identified in most organs. Recently, evidence for an intracellular RAS has been reported. The new expanded view of RAS therefore covers both endocrine, paracrine and intracrine functions. Other peptides of RAS have been shown to have biological actions; angiotensin 2-8 heptapeptide (Ang III) has actions similar to those of Ang II. Further, the angiotensin 3-8 hexapeptide (Ang IV) exerts its actions via insulin-regulated amino peptidase receptors. Finally, angiotensin 1-7 (Ang 1-7) acts via mas receptors. The discovery of another ACE2 was an important complement to this picture. The recent discovery of renin receptors has made our view of RAS unexpectedly complex and multilayered. The importance of RAS in cardiovascular disease has been demonstrated by the clinical benefits of ACE inhibitors and AT1 receptor blockers. Great expectations are now generated by the introduction of renin inhibitors. Indeed, RAS regulates much more and diverse physiological functions than previously believed.

Blood pressure reduction and antihypertensive medication use in the losartan intervention for endpoint reduction in hypertension (LIFE) study in patients with hypertension and left ventricular hypertrophy

OBJECTIVE

To compare blood pressure response and antihypertensive medication use visit-by-visit from baseline in patients receiving losartan-based or atenolol-based therapy in the LIFE study.

RESEARCH DESIGN

LIFE was a randomized, double-blind trial comparing losartan-based and atenolol-based treatment regimens on the primary composite endpoint of death, myocardial infarction (MI), or stroke in 9193 patients aged 55-80 years with hypertension and left ventricular hypertrophy. Systolic and diastolic, pulse, and mean arterial pressures, blood pressure responder rates, distribution of open-label antihypertensive agents utilized, and the proportion of patients on randomized treatment were determined for each group at each clinic visit over a follow-up period of at least 4 years.

RESULTS

Overall blood pressure reductions were comparable in the losartan-based and atenolol-based treatment groups. The mean reductions in sitting trough systolic and diastolic blood pressures from baseline to the end of follow-up (or last visit before a primary endpoint event) were 30.2/16.6 mmHg in the losartan group and 29.1/16.8 mmHg in the atenolol group. The time-averaged difference in overall mean arterial pressure was similar between groups. The proportion of patients on individual dose combinations varied visit by visit but was generally comparable between groups. During the entire study, 56% (2579/4605) of losartan-treated patients received at least one dose of the combination of losartan 100 mg plus hydrochlorothiazide 12.5 mg and 51% of atenolol-treated patients received 100 mg of atenolol plus hydrochlorothiazide 12.5 mg at some time during the study.

CONCLUSIONS

Differences in blood pressure or distribution of add-on medications between treatment groups were not evident in the LIFE trial and, thus, cannot account for the observed outcome difference in the primary endpoint of risk reduction of the composite of cardiovascular death, stroke and MI favoring losartan.

Atorvastatin inhibits angiotensin-converting enzyme induction in differentiating human macrophages

Statins are effective drugs in the prevention of cardiovascular disease. Recent studies suggested that statins have additional beneficial effects on the vascular wall independent of their cholesterol-lowering effects. We investigated whether atorvastatin influences angiotensin-converting enzyme (ACE) production in differentiating human macrophages. Human peripheral blood monocytes (PBM) were isolated from fresh buffy coats. The cells were allowed to differentiate for 0-8 days in macrophage serum-free medium with 5 ng/ml granulocyte-macrophage colony-stimulating factor. Atorvastatin (0.005-0.5 microM), mevalonate (200-400 microM), geranylgeranyl pyrophosphate (1.25-2.5 microM), and/or farnesylpyrophosphate (FPP; 1.25-2.5 microM) was added on the second day of differentiation and then every other day. After incubation time, the ACE amount in intact macrophages was measured. ACE amount in PBM was low. A marked time-dependent ACE induction was noticed during differentiation of monocytes to macrophages. Atorvastatin treatment inhibited ACE induction during differentiation. In the presence of mevalonate, atorvastatin failed to downregulate ACE production. Cotreatment of the cells with atorvastatin and FPP reversed the suppressive effect of atorvastatin on ACE. In conclusion, atorvastatin inhibited ACE upregulation, normally occurring in differentiating human macrophages. This effect was mediated via the mevalonate pathway, and inhibition of FPP was probably involved. The finding that atorvastatin inhibited ACE upregulation may represent a novel pleiotropic action and an additional beneficial effect of statins in treatment of cardiovascular disease.