Silvia Maffei

Circulating levels of cardiac natriuretic peptides (ANP and BNP) measured by highly sensitive and specific immunoradiometric assays in normal subjects and in patients with different degrees of heart failure

Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels increase in patients with heart failure with the progression of clinical symptoms and with the deterioration of hemodynamics; consequently, assay methods for these peptides may be useful in the follow-up of cardiac patients. Non-competitive immunoradiometric assay (IRMA) methods for ANP or BNP do not generally require preliminary extraction and/or purification of the plasma sample, and so may be more suitable than competitive immunoradiometric assay (RIA) methods for the routinary assay of plasma peptide concentrations. We evaluated the analytical characteristics and clinical usefulness of two IRMAs for plasma ANP and BNP, to verify whether these methods may be considered suitable for the follow-up of patients with heart failure. Both methods are based on the solid-phase sandwich IRMA system, which uses two monoclonal antibodies prepared against two sterically remote epitopes of peptide molecule; the first antibody was coated on the beads solid-phase and the second was radiolabeled with 125I. Blood samples were collected from a brachial vein in ice-chilled disposable polypropylene tubes containing aprotinin and EDTA after the patient had rested for at least 20 min in the recumbent position. Plasma samples were immediately separated by centrifugation and stored at −20 C until assay. The IRMA methods showed a better sensitivity and a wider working range sensitivity (about 2 ng/l) than those of RIA methods. Moreover, the normal range found with these methods (ANP= 16.1±8.6 ng/l, 5.2±2.8 pmol/l, BNP= 8.6±8.2 ng/l, 2.5±2.4 pmol/l) was similar to that generally reported using the most accurate methods, such as the other IRMAs or RIAs, using a preliminary extraction and purification of plasma samples with chromatographic procedures. Our results obtained in patients with different degrees of heart failure indicate that plasma ANP and BNP increase with the progression of clinical symptoms (NYHA class) (ANOVA p<0.0001). Indeed, circulating levels of ANP (R=− 0.701, no.=86) and BNP (R=−0.745, no.=55) were significantly (p<0.0001) and negatively correlated with the left ventricular ejection fraction values. Furthermore, a close curvilinear regression (R= 0.960, no.= 215) was found between ANP and BNP values, because plasma BNP progressively increases more than plasma ANP in patients with different stages of heart failure. In conclusion, IRMA methods are preferable for the measurement of plasma ANP and BNP for experimental studies and routine assay because they are more practicable, sensitive and accurate than RIA procedures. Finally, BNP assay appears to be better than ANP for discriminating between normal subjects and patients with different degrees of heart failure.

The Circulating Levels of Cardiac Natriuretic Hormones in Healthy Adults: Effects of Age and Sex

Abstract In order to study the relationships between sex hormones, aging, and circulating levels of cardiac natriuretic peptides and to define reference values for atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) assays, we measured the plasma levels of cardiac natriuretic peptides in a large group of healthy adults divided according to age and sex. We studied 216 healthy subjects of both sexes (109 men and 107 women) with age ranging from 20 to 77 years (mean 43.2±14.8 years). All subjects were non-obese and had normal arterial blood pressure; they were free from acute diseases, including asymptomatic heart disease. Highly sensitive and specific IRMA methods were used to measure plasma ANP and BNP. The mean ANP value in healthy adult subjects of both sexes was 17.8±10.9 pg/ml with no significant difference between men (16.7±10.0 pg/ml) and women (18.8±11.7 pg/ml). The mean BNP value in healthy adult subjects of both sexes was 9.9±9.0 pg/ml with a significant difference (p<0.0001) between men (7.7±7.1 pg/ml) and women (12.2±10.2 pg/ml). There was a weak linear relationship between age and either ANP (r=0.350, p<0.0001) or BNP (r=0.254, p=0.0002) values. When the circulating levels of cardiac natriuretic hormones, and age and sex were analyzed by multiple stepwise regression analysis, both age and sex significantly and independently contributed to the regression. Our study indicates independent positive effects of aging and female sex hormones on ANP and BNP levels in healthy adult subjects. These effects should be taken into account in the calculation of appropriate reference values for cardiac natriuretic hormones.

Gender determinants of cardiovascular risk factors and diseases.

This article addresses the various aspects concerning gender dissimilarities in the cardiovascular system. It examines sex differences in the genetic susceptibility to cardiovascular disease (CVD) development or outcome: with the presence of either XX or XY chromosomes, every cell is sexually differentiated and there exist postpuberal differences between male and female cardiovascular systems. The main action mechanisms of sex steroid hormones are discussed, mainly as to testosterone (Te) in men and 17beta-estradiol (E2) and progesterone (Pro) in women. In women, susceptibility to CVD is known to increase in the postmenopausal period, when the ovarian hormone function expires. Some concepts of the sex-based differences in anatomy and physiology are also explained. Although they have the same structural elements, women and men use them in a different way to guarantee cardiovascular system homeostasis. Some examples of differences between men and women in pathological cardiovascular function are given. A further important issue regards the prevalence and role of cardiovascular risk factors in the two genders. Compared to boys of the same age, adolescent girls and premenopausal women have a more favorable risk profile: lower blood pressure (BP), less atherogenic lipid profile, and lower prevalence of cardiovascular risk factors. Women develop CVD later than men and diabetic women have a considerably higher mortality rate compared to men of the same age. Finally, there exist several clinically significant differences between men and women as to prevalence, presentation, management and outcome of CVD. Clinical peculiarities related to gender in presentation of some CVDs, such as coronary heart disease (CHD), stroke and heart failure, are described. We are absolutely convinced that only an accurate knowledge of the sex-specific pathophysiology may allow determination of the appropriate diagnostic instruments and to implement tailored treatments of CVD in men and women.

Determinants of oxidative stress related to gender: relevance of age and smoking habit.

Abstract Background: Magnitude and major causes of oxidative stress may be different between sexes, although limitedly addressed in clinical studies with controversial results. The present study aimed to determine whether any gender-related difference exists concerning oxidative stress in a population of 332 subjects of both sexes, in a wide age range, with and without cigarette smoking habit. Methods: The Oxidative-INDEX was calculated after evaluation of serum hydroperoxides (ROMs) and total antioxidant capacity (OXY) by means of commercial kits (d-ROMs and Oxy-adsorbent Tests, Diacron, Italy) subtracting the OXY standardized variable from the ROMs standardized variable. Results: The Oxidative-INDEX resulted higher in women with respect to men (p<0.001), in smokers (p<0.01) than in non-smokers, and correlated with cigarette number (p<0.01), age (p<0.001), and post-menopausal status (p<0.001). The multivariate analysis identified age, high blood pressure, and smoking habit as factors independently associated with the Oxidative-INDEX in men, whereas cigarette smoking and age represented the independent risk factors for an elevated oxidative stress status in women. Conclusions: Gender-based differences in oxidative stress levels may provide a biochemical basis for the epidemiologic differences in the disease susceptibility between sexes, and suggest different strategies for risk assessment, diagnosis, and treatment specifically targeted to men and women.

The ovarian cycle as a factor of variability in the laboratory screening for primary aldosteronism in women

Primary aldosteronism is increasingly investigated in hypertension being associated with an elevated cardiovascular risk. Aldosterone has been reported to increase in the luteal phase in normal women but to our knowledge the influence of the ovarian cycle on the first screening for primary aldosteronism (that is, on the levels of plasma aldosterone and its relationship to PRA levels) was never investigated. We measured hormonal levels during one cycle in 26 low-renin mild hypertensive outpatients. LH, FSH, 17 β-estradiol, progesterone, aldosterone and PRA were assayed at the seventh, fourteenth, twenty-first and twenty-eighth days of the cycle after 30 min of recumbency. Aldosterone and PRA increased from the seventh (follicular phase) to twenty-first day (luteal phase) from 11.2 to 17.8 ng 100 ml−1 and from 0.23 to 0.35 ng ml−1 h−1, respectively (both P=0.004) The proportion of patients with aldosterone >15 ng 100 ml−1 significantly increased from the follicular to the luteal phase, (8/26 vs 19/25, P=0.018); a similar increase was found for Aldosterone-PRA Ratio >30 combined with either a minimum PRA value of 0.5 ng ml−1 h−1 or aldosterone >15 ng 100 ml−1 (7/26 vs 16/25 and 7/26 vs 17/25 respectively, P<0.05). Aldosterone was positively related to PRA and progesterone. Higher aldosterone levels may be frequently encountered in the second part of the ovarian cycle in low-renin hypertensive women. This variability appears to be an important factor to be taken into account in the first-step laboratory screening for primary aldosteronism and should be considered in the process of standardization of the diagnostic work-up for this disease.

Age-related oxidative stress modulation by smoking habit and obesity.

OBJECTIVE To evaluate whether obesity and smoking habit may accelerate the age-related increase of oxidative stress. METHODS The Oxidative-INDEX, a score reflecting both oxidative and antioxidant counterparts, was estimated in 179 subjects (50 males, aged 16-79 years). RESULTS Oxidative stress results were elevated in obese and smoker subjects. Adjusted logistic regression analysis indicated obesity and smoking as independent variables for elevated Oxidative-INDEX (odds ratio=4.8 and 3.1, respectively). Oxidative-INDEX steadily rises at a mean rate of 5.3% (0.017 AU) per year in the overall population, showing twice and three times higher annual rate increase in smokers and obese subjects. CONCLUSION Our results suggest the pro-ageing effects of cigarette smoking and obesity by a more rapid and sharp elevation of the oxidative stress status.

Sex-related differences in association of oxidative stress status with coronary artery disease

OBJECTIVE To assess oxidative stress status in coronary artery disease (CAD) patients according to gender. DESIGN Case-controlled, observational, retrospective study. SETTING Clinical and research center. PATIENT(S) A total of 55 postmenopausal women and 108 men (mean age: 66 ± 9 years), including 72 patients with angiographically proven CAD (CAD(+), 19 women) and a group of 91 age-matched controls (CAD(-), 36 women). INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Oxidant/antioxidant balance as a global index (oxidative index) obtained using two commercial assays (d-ROMs and OXY Adsorbent Test, respectively) for estimation of levels of reactive oxygen metabolites and total antioxidant status. RESULT(S) There was a statistically significant difference in oxidative stress status between men and women who were CAD(-) (-0.424 ± 1.3 vs. 0.64 ± 1.1 arbitrary units, respectively), but the CAD(+) women had oxidative stress levels almost three times those of the CAD(+) men (2.45 ± 2.5 vs. 0.9 ± 1.6 arbitrary units, respectively). After adjustment in the multivariate model, age and oxidative stress status in women and diabetes and age in men remained as statistically significant predictors of positive CAD findings. CONCLUSION(S) Oxidative stress status was a powerful predictor of CAD in women. This result may have important implications for the differences between sexes in CAD physiopathology.

Hormone replacement therapy and cardioprotection: a new dawn? A statement of the Study Group on Cardiovascular Disease in Women of the Italian Society of Cardiology on hormone replacement therapy in postmenopausal women.

Cardiovascular disease is the leading cause of death in women in Western countries. Despite preventive strategies, in the past decades the incidence of cardiovascular events has shown a decline in men but a rise in women, matching the growth of the population of postmenopausal women. Several epidemiological findings suggest the causative pathophysiological role of ovarian hormone deficiency in the development of cardiovascular disease in women. Observational and randomized studies have suggested that hormone replacement therapy in early postmenopause could be beneficial from a cardiovascular point of view. Conversely, aging, time since menopause and presence of cardiovascular risk factors or cardiovascular disease may decrease its efficacy and increase the risk of cardiovascular events. It is plausible that the unfavorable effects of the estrogen/progestin combination used in the randomized studies are not related to the hormone preparation per se but rather to the use of hormones in the less receptive group of women, older and with cardiovascular risk factors. Clinical judgment, choice of the right dose and estrogen/progestin combination are of pivotal importance to maximize the beneficial effect of estrogen replacement therapy/hormone replacement therapy, especially if given within a reasonable time after the menopause to women who need the therapy for the relief of menopausal symptoms.

Circulating levels of cardiac natriuretic hormones measured in women during menstrual cycle

Alterations in fluid and electrolyte balance represent a common complaint by women during different stages of the menstrual cycle; however, conflicting results concerning the possible role of plasma Atrial Natriuretic Peptide (ANP) modifications during the menstrual cycle have been reported. This may be due to differences in assay methods or in the clinical protocol adopted. Moreover, possible variations in plasma Brain Natriuretic Peptide (BNP) levels during the menstrual cycle have not been studied. We measured the plasma levels of ANP and BNP by means of two highly sensitive and specific immunoradiometric assay (IRMA) methods in 19 normal women without premenstrual symptoms, in order to evaluate whether significant modifications of these hormones are present during the menstrual cycle. Because it is well-known that circulating levels of cardiac hormones show great variations in normal subjects due to their rapid plasma half lifes, blood samples were collected at 2.5-min intervals over a 15-min period on the 5th and 24th days of the cycle. The mean (±SD) values of ANP (follicular phase=15.1±8.7 pg/ml; luteal phase=14.8±9.5 pg/ml) and of BNP (follicular phase=13.0±15.0 pg/ml; luteal phase= 11.2±11.4 pg/ml) did not show significant variations during the menstrual cycle. Moreover, the variability of ANP values (CV=24.8±13.2%) was significantly higher (p=0.0318) than that of BNP values (CV=16.5±8.9%), and a significant correlation was found between the mean ANP and BNP values of the individual women studied (R=0.407, p=0.0437). The values of estradiol, progesterone, LH, FSH and prolactin did not correlate with the ANP or BNP values. In conclusion, our results indicate that circulating levels of cardiac hormones do not show any significant modifications during the menstrual cycle in healthy women.

Oxidative status and cardiovascular risk in women: Keeping pink at heart.

Although cardiovascular disease (CVD) has always been perceived as a pathology regarding essentially males, incidence and death from cardiovascular events dramatically increase after menopause in women. Obviously, while many aspects of CVD are similar in both sexes, it is now clear that there are significant differences as well. Exploration of these gender-related differences in CVD might provide a basis for the development of new strategies in the management of patients with CVD from a gender point of view. In particular, a growing amount of data suggested the possible major role of oxidative stress in female patients and the possibility to integrate this new biomarker in future study evaluating CVD risk in women.