Alessandro Rappelli

Expression of natriuretic peptide receptors in human adipose and other tissues

To characterize natriuretic peptide receptor (NPr) gene expression in human tissues, we cloned portions of the cDNAs codifying for NPr with guanylyl cyclase activity (NPr-A and NPr-B) and without guanylyl cyclase activity (NPr-C). Total RNA was extracted from samples taken at surgery from normal human tissues. NPr-A and NPr-B cDNAs obtained from lung as well as NPr-C cDNA obtained from renal cortex were cloned, characterized, and used for comparative Northern analysis. NPr-A mRNA (≈4 kb) was most abundant in adipose tissue (8 patients) independently on the site of sampling, whereas it was ≈2.5-fold and 5-fold less abundant, respectively, in kidney (either renal cortex or papilla from 3 patients) and adrenal (4 patients), known target tissues of natriuretic peptides. NPr-C mRNAs (≈7.7 and 6.8 kb) had a similar tissue distribution but the highest levels were found in renal tissue and only very low expression levels were found in adrenals (~20-fold lower than renal cortex). The ratio of NPrA versus NPr-C mRNA levels were highest in adrenal and lowest in renal tissue. NPr-B mRNA (≈4 kb), which encodes the receptor for the C-type natriuretic peptide, had a different and wide tissue distribution, including expression in ileum and liver, with the highest levels in venous and prostatic tissue. These results indicate that, in humans, different patterns of NPr expression with different NPr-A/NPr-C mRNA level ratios, are present in known target tissues of natriuretic peptides. “Non-classic” target tissues, such as the adipose one, maximally expressed NPr-A and also NPr-C, suggesting that natriuretic peptides may have wider functional activities than those previously demonstrated.

Renin-angiotensin system, natriuretic peptides, obesity, metabolic syndrome, and hypertension: An integrated view in humans

The obesity pandemic is closely related to hypertension and metabolic syndrome. Visceral adipose tissue plays a key role in the metabolic and cardiovascular complications of being overweight. The pathophysiological link between visceral adiposity and cardiometabolic complications focuses on insulin sensitivity, sympathetic nervous system, renin–angiotensin–aldosterone system (RAAS) and, only recently, on cardiac natriuretic peptide system (CNPS). RAAS and CNPS are endogenous antagonistic systems on sodium balance, cardiovascular system, and metabolism. The circulating RAAS is dysregulated in obese patients, and adipose tissue has a full local renin–angiotensin system that is active at local and systemic level. Adipocyte biology and metabolism are influenced by local renin–angiotensin system, with angiotensin II acting as a ‘growth factor’ for adipocytes. CNPS induces natriuresis and diuresis, reduces blood pressure, and, moreover, has powerful lipolytic and lipomobilizing activity in humans but not in rodents. In obesity, lower plasmatic natriuretic peptides levels with increasing BMI, waist circumference, and metabolic syndrome have been documented. Thus, reduced CNPS effects coupled with increased RAAS activity have a central role in obesity and its deadly complications. We propose herein an integrated view of the dysregulation of these two antagonistic systems in human obesity complicated with hypertension, metabolic syndrome, and increased cardiovascular risk.

Plasma atrial natriuretic peptide and natriuretic peptide receptor gene expression in adipose tissue of normotensive and hypertensive obese patients

Objective Human and rat adipose tissue contain very high levels of natriuretic peptides clearance receptor messenger (m)RNA, and fasting inhibits its gene expression in adipose tissue. In this study we evaluated plasma atrial natriuretic peptide (ANP) and gene expression of biologically active type A natriuretic peptide receptor (NPr-A) and clearance natriuretic peptide receptor (NPr-C) in adipose tissue of obese hypertensive and obese normotensive patients. Design and methods We studied 27 untreated obese hypertensives, 26 obese normotensives (body mass index ≥ 30 kg/m2), 24 non-obese essential hypertensives and 23 lean healthy subjects (body mass index ≥ 25 kg/m2). Blood samples were withdrawn for ANP, plasma renin activity and aldosterone radio-immunoassays. Subcutaneous peri-umbilical adipose tissue samples were obtained, by needle aspiration, in 13 obese hypertensives and in 12 obese normotensives and used for RNA extraction. Then, complementary synthesis and semiquantitative polymerase chain reaction (PCR) with primers complementary to sequences of different exons of the genes encoding for NPr-A, NPr-C and β-actin, were performed. 32P-labeled PCR products were separated by electrophoresis, blotted onto nylon membranes, and the exposed autoradiographic films were analysed by densitometry. NPr signals were normalized by the β-actin expression level. Results Plasma ANP was lower in obese hypertensives than in obese normotensives (37.5 ± 7 versus 43.2 ± 6 pg/ml, P < 0.05), but was higher in non-obese hypertensives than in non-obese normotensives. In contrast, plasma renin activity and aldosterone were higher in the obese hypertensives. Although NPr-A and NPr-C expression were not statistically different between the two obese groups, the NPr-A: NPr-C mRNA ratios were significantly lower in obese hypertensives (P < 0.03). Conclusions Our data suggest that in obese hypertensives compared to obese normotensives, the lower NPr-A: NPr-C ratio might determine decreased biological activity and/or an increased clearance of natriuretic peptide in adipose tissue, suggesting that the natriuretic peptide and its receptor system may be important in obesity-related hypertension where ANP levels are lower.

Treatment of Isolated Systolic Hypertension: The SHELL Study Results

Objective: Our aim was to compare the effect of lacidipine and chlorthalidone on cardiovascular outcome as a primary parameter and blood pressure as a secondary in elderly patients with isolated systolic hypertension in a prospective study with an open design. Methods: 1882 males and females outpatients ≥60 years were randomly assigned to the administration of chlorthalidone 12.5 mg o.d. or lacidipine 4 mg o.d. Patients were recruited if sitting systolic blood pressure was ≥160 mmHg with a diastolic blood pressure equal or lower than 95 mmHg. Primary endpoint was a composite of cardiovascular and cerebrovascular events. Results: At randomization mean systolic blood pressure was 178.1 mmHg in the lacidipine and 178.2 mmHg in the chlorthalidone group, the corresponding mean diastolic values being 86.9 and 86.8 mmHg. In both lacidipine and chlorthalidone groups treatment caused a significant (p < 0.001) and marked systolic blood pressure reduction which was maintained throughout the treatment period with a significant (p < 0.001) and steady although less marked reduction in diastolic blood pressure as well. At the end of treatment period (median 32 months), the reduction was 36.8/8.1 mmHg (systolic/diastolic) in the chlorthalidone and 38.4/7.9 mmHg in the lacidipine group, the final on treatment blood pressures being 142.0/79.2 and 143.2/79.5 mmHg, respectively. Treatments were similarly effective in males and females and in age groups between 60 and 69 years (n = 763), 70 and 79 years (n = 744) and ≥80 years (n = 375). Similar reductions were obtained in a subgroup of patients (n = 209) followed in double-blind fashion for 1 year. The overall incidence of the primary endpoints was 9.3% with no significant between-group difference. Total mortality was also similar between groups. Conclusions: In elderly patients with isolated systolic hypertension, administration of lacidipine or chlorthalidone markedly reduced systolic blood pressure with no difference in the incidence of cardiovascular events and total mortality.

Tolerability of long-term treatment with lercanidipine versus amlodipine and lacidipine in elderly hypertensives

BACKGROUND Irrespective of their clinical relevance, side effects cannot be considered a negligible problem in antihypertensive therapy. The aim of this trial was to evaluate the tolerability profile of lercanidipine with that of two other calcium antagonists (amlodipine and lacidipine) in elderly hypertensives. METHODS In a multicenter, double-blind, parallel study 828 elderly (aged > or =60 years) hypertensives were randomized to lercanidipine 10 mg/day (n = 420), amlodipine 5 mg/day (n = 200), or lacidipine 2 mg/day (n = 208) (ratio 2:1:1). If blood pressure (BP) control was unsatisfactory (systolic BP/diastolic BP > or =140/90 mm Hg), the dose of the double-blind medication was doubled and, as a further step, enalapril or atenolol (plus diuretic, if needed) was added. Patients were treated for an average of 12 months. RESULTS Amlodipine patients had significantly (P <.001) higher rates of edema (19%) and of early study discontinuations due to edema (8.5%) compared with lercanidipine (9% and 2.1%) and lacidipine patients (4% and 1.4%). Similarly, edema-related symptoms (lower limb swelling and heaviness) occurred significantly (P <.01) more often with amlodipine (50% and 45%, respectively) than with lercanidipine (35% and 33%) and lacidipine (34% and 31%). Most edema cases occurred in the first 6 months, a between-treatment difference being evident since beginning of treatment. Other drug-related adverse events did not differ between treatments. Blood pressure was equally and effectively reduced in the three groups. CONCLUSIONS The two lipophilic dihydropyridine calcium antagonists, lercanidipine and lacidipine, have an antihypertensive effect comparable to that of amlodipine, but a better tolerability profile.

Low Calorie Diet Enhances Renal, Hemodynamic, and Humoral Effects of Exogenous Atrial Natriuretic Peptide in Obese Hypertensives

The expression of the natriuretic peptide clearance receptor is abundant in human and rat adipose tissue, where it is specifically inhibited by fasting. In obese hypertensives, plasma atrial natriuretic peptide (ANP) levels were found to be lower than in obese normotensives. Therefore, the increased adipose mass might influence ANP levels and/or its biological activity. The aim of the present study was to evaluate whether the humoral, hemodynamic, and renal effects of exogenous ANP in obese hypertensives might be enhanced by a very low calorie diet. Eight obese hypertensives received a bolus injection of ANP (0.6 mg/kg) after 2 weeks of a normal calorie/normal sodium diet, and blood pressure (BP), heart rate, ANP, cGMP, plasma renin activity, and aldosterone were evaluated for 2 hours before and after the injection. Diuresis and natriuresis were measured every 30 minutes. The patients then started a low calorie/normal sodium diet (510 kcal/150 mmol/d) for 4 days, and then the ANP injection protocol was repeated. The low calorie diet induced a slight weight loss (from 90.6+/-1.1 to 87. 7+/-1.2 kg; P<0.01), which was accompanied by increase of cGMP excretion (from 146.0+/-10.1 to 154.5+/-9.5 nmol/24 h; P<0.05) together with a reduction of BP (P<0.01 versus basal levels). ANP injection after diet was followed by an increase of ANP levels similar to that observed before diet, but plasma cGMP, diuresis, and natriuresis increased significantly only after diet. Similarly, the decrease of BP after ANP administration was significantly higher after diet (change in mean arterial pressure, -6.4+/-0.7 versus -4. 0+/-0.6 mm Hg; P<0.05) as well as that of aldosterone (P<0.01). These data show that a low calorie diet enhances the humoral, renal, and hemodynamic effects of ANP in obese hypertensives and confirm the importance of caloric intake in modulating the biological activity of ANP, suggesting that the natriuretic peptide system can play a role in the acute changes of natriuresis and diuresis associated with caloric restriction.

Angiotensin converting enzyme gene polymorphism and carotid atherosclerosis in a low-risk population

Objectives Angiotensin converting enzyme (ACE) insertion/deletion (l/D) polymorphism has been shown to be an independent risk factor for myocardial infarction and other cardiovascular diseases. The aim of the study was to investigate the relationship between ACE genotype and carotid atherosclerosis evaluated by ultrasonography. Patients and methods ACE l/D polymorphism was determined in 240 low-risk patients (mean age 53.6±7 years) in relation to traditional risk factors and the degree of carotid atherosclerosis. Intimal-medial thickness was measured at the level of the common carotid artery, bifurcation and internal carotid on both sides. Patients were defined as normal (n = 47, intimal-medial thickness <1.0mm), thickened (n = 56, intimal-medial thickness ±1.0 and ±1.3 mm in the thickest wall) or with an atherosclerotic plaque (n = 137, intimal-medial thickness >1.3 mm for at least one level of examination). Age, sex, body mass index, blood pressure levels and prevalence of other risk factors were similar in the three groups. I/D polymorphism was determined by polymerase chain reaction using specific primers and genomic DNA from leukocytes as template. Plasma ACE levels, plasma renin activity and plasma aldosterone were evaluated in all patients by standard procedures. Results No significant differences were found in humoral parameters, ACE, genotype distribution and the corresponding allele frequency among the three groups of patients. Only ACE plasma levels were significantly higher in the DD and ID genotypes compared with the II genotype (DD 14.27 ± 5.05 IU/ml, ID 12.70±4.31 IU/ml; II 8.04±3.45 IU/ml). The mean intimal-medial thickness was similar in all three genotypes. Conclusion Although ACE genotype has been shown to be related to coronary atherosclerosis, the present data do not indicate that the DD genotype is associated with carotid atherosclerosis. However, further studies of larger populations are needed to clarify whether genetic ACE polymorphism is associated with carotid atherosclerosis.

Allelic variants of natriuretic peptide receptor genes are associated with family history of hypertension and cardiovascular phenotype

Objective Abnormalities in the natriuretic peptide system could play a key role in the genesis of hypertension. We evaluated the associations between a family history of hypertension, cardiovascular phenotype and allelic variants of Npr1 and Npr3, two candidate genes that codify for natriuretic peptide receptors. Methods We genotyped 45 young normotensive subjects (19 males, 26.8 ± 3.7 years) with accurately assessed family history of hypertension (FH+) and 52 (26 males, 26.1 ± 3.1 years) without (FH−) for the known variants of Npr1 and Npr3 genes, and for a novel length difference (3C/4C) polymorphism at position 15129 in the 3′-untranslated region of the Npr1 gene. Blood pressure, echocardiography and plasma brain natriuretic peptide were assessed. Results Both the novel Npr1 3C allele (59 versus 33%, P < 0.001) and the 3C/3C genotype (31 versus 8%; P < 0.001) were significantly more frequent in FH+ than in FH−. The inverse distribution of the 4C/4C genotype suggested that a casual association was very unlikely. Moreover, the 3C/3C homozygous had significantly higher systolic blood pressure (121.1 ± 6.3 versus 115.6 ± 7.8 mmHg in 4C/4C; P < 0.05) and a longer left ventricular isovolumic relaxation time (67 ± 10 versus 61 ± 9 ms; P < 0.05). The Npr3 C(−55) allele variant was also more frequent in FH+ (88 versus 76%, P < 0.05), but was not associated with the cardiovascular phenotype. Conclusions The novel Npr1 gene 3C variant and the Npr3 gene C(−55) allele are associated with hypertensive family history. Moreover, the functional Npr1 3C variant, when homozygous, is also associated with higher systolic blood pressure and prolonged ventricular relaxation.

A Geriatric Emergency Service for Acutely Ill Elderly Patients : Pattern of Use and Comparison with a Conventional Emergency Department in Italy

The current disease‐oriented, episodic model of emergency care does not adequately address the complex needs of older adults presenting to emergency departments (EDs). Dedicated ED facilities with a specific organization (e.g., geriatric EDs (GEDs)) have been advocated. One of the few GED experiences in the world is described and its outcomes compared with those of a conventional ED (CED). In a secondary analysis of a prospective observational cohort of 200 acutely ill elderly patients presenting to two urban EDs in Ancona, Italy, identifiers and triage, clinical, and social data were collected and the following outcomes considered: early (30‐day) and late (6‐month) ED revisit, frequent ED return, hospital admission, and functional decline. Death, functional decline, any ED revisit and any hospital admission were also considered as a composite outcome. Odds ratios and 95% confidence intervals (CIs) were calculated. Overall, GED patients were older and frailer than CED patients. The two EDs did not differ in terms of early, late, or frequent ED return or in 6‐month hospital admission or functional decline. The mortality rate was slightly but significantly lower in the GED patients (hazard ratio=0.47, 95% CI=0.22–0.99, P=.047). The data suggest noninferiority and, indirectly, a slight superiority for the GED system in the acute care of elderly people, supporting the hypothesis that ED facilities specially designed for older adults may provide better care.

Reproducibility and Clinical Value of the Trough-to-Peak Ratio of the Antihypertensive Effect: Evidence From the Sample Study

The objectives of our study were to assess the reproducibility of the trough-to-peak ratio (T/P) and to see whether a high T/P is accompanied by more organ protection or vice versa. The study included 175 (mean+/-SD age, 51+/-9 years) subjects with mild-moderate essential hypertension who had echocardiographic evidence of left ventricular (LV) hypertrophy taken from the SAMPLE study (Study on Ambulatory Monitoring of Blood Pressure and Lisinopril Evaluation), an open-label multicenter study. The study included a 3-week washout pretreatment period, a 12-month treatment period with lisinopril (n=84) or lisinopril plus hydrochlorothiazide (n=91) once daily, and a 4-week placebo follow-up period. Results of 24-hour ambulatory blood pressure monitoring and echocardiographic determination of left ventricular mass index (LVMI) were obtained before and after 3 and 12 months of treatment. T/Ps were computed in each patient by dividing the systolic and diastolic blood pressure changes at trough (changes in the last 2 hours of the monitoring period) by those at peak (average of the 2 adjacent hours with the maximal blood pressure reduction between the 2nd and 8th hour from drug intake) after 3 and 12 months of treatment. Average 24-hour blood pressure was similarly reduced at 3 and 12 months. Trough blood pressure changes at 3 and 12 months were closely correlated, as were the corresponding peak blood pressure changes. However, the 3- and 12-month T/Ps correlated to a lesser degree (r<0.42). Furthermore, the reduction of LVMI induced by treatment was similarly correlated with the treatment-induced reduction in 24-hour average, trough, and peak blood pressures but not with the T/Ps. This was also evident when the contribution to LV hypertrophy regression by 24-hour blood pressure changes and T/Ps was assessed in a multivariate regression analysis. In patients with a T/P >/=0.5 or <0.5, the regression of LVMI was similar. In conclusion, peak and trough blood pressure changes are reproducible and predict the regression of LVMI induced by treatment as well as average 24-hour blood pressure. T/Ps are less reproducible, and their value does not predict regression of organ damage by antihypertensive treatment.