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Biomedical subjects

C Lazzeri

Publications and source records attributed to C Lazzeri.

At least 19 recordsLinked to original sources

Cardiac autonomic tone during trandolapril-irbesartan low-dose combined therapy in hypertension: a pilot project.

Pharmacological and clinical studies on the effects of angiotensin-converting enzyme (ACE) inhibitors support the idea of a central role played Angiotensin II which is able to cause cardiovascular and renal diseases also independently of its blood pressure elevating effects. The present investigation was aimed at evaluating the effect(s) of three different pharmacological regimens on both blood pressure and sympathetic drive in uncomplicated essential hypertension, by means of blood pressure laboratory measurements and ambulatory monitoring, 24-h heart rate variability and plasma noradrenaline levels. Thus, an ACE-inhibitor monotherapy (trandolapril, 2 mg/day), an AT(1)-receptor antagonist monotherapy (irbesartan, 300 mg/day), their low-dose combination (0.5 mg/day plus 150 mg/day, respectively) and placebo were given, in a randomised, single-blind, crossover fashion for a period of 3 weeks each to 12 mild essential hypertensives. Power spectral analysis (short recordings) and noradrenaline measurements were also performed in the supine position and after a postural challenge (60 degrees head-up tilting test: HUT). The low-dose combination therapy induced the greatest reduction in LF component and in LF/HF ratio, both in the resting and tilted positions, as well as in blood pressure. However, the physiological autonomic response to HUT was maintained. Noradrenaline plasma levels were lower after the combined therapy than after each drug alone. Our data demonstrate that in mild and uncomplicated essential hypertension, the chronic low-dose combination therapy with an ACE-inhibitor and an AT(1)-antagonist is more effective than the recommended full-dose monotherapy with either drug in influencing the autonomic regulation of the heart, suggesting a relative reduction in sympathetic drive both at cardiac and systemic levels.

Adult↗

Cardiovascular function in pregnancy: effects of posture.

OBJECTIVE: To evaluate the cardiovascular response to active postural changes in pregnancy. DESIGN: Prospective study. SETTING: Outpatient Clinic, Fetal Maternity Unit. PARTICIPANTS: Sixteen healthy women referred prior to pregnancy. METHODS: Heart rate, arterial pressure, echocardiographic end-diastolic and end-systolic left ventricular volumes (Teichholz' s formula) were measured in the three months before pregnancy, at the end of the first and second trimester, at mid third trimester, and six months after delivery in the supine and standing position, in thirteen women (mean age 33, range 25-38 years). RESULTS: Cardiac output (supine position) significantly increased (28%): it reached its maximum at the second trimester, remained steadily elevated in the mid third trimester, and returned to baseline after delivery. Cardiac output increased during pregnancy also in the active orthostatic position, the percentage increase being greater (70%) since the standing pre-conception value was lower. The postural stress induced similar changes in heart rate, arterial pressure and left ventricular ejection fraction before, during and after pregnancy. However, the reduction in cardiac output associated with early standing attenuated significantly at the second trimester and it was absent at mid third trimester (F = 3.13, P = 0.021). This was due to the interplay between the significantly lesser increase in systemic vascular resistance, occurring since the first trimester, and the significantly lesser decrease in left ventricular end-diastolic volume which was observed in the mid third trimester. CONCLUSION: These data indicate that the elevated cardiac output is adequately maintained in pregnancy during the postural challenge, due to optimisation of the responses of preload and afterload.

Adult↗

Centrally mediated effects of bromocriptine on cardiac sympathovagal balance.

Bromocriptine, a dopamine agonist, is known to lower cardiovascular mortality in L-dopa-treated patients with Parkinson's disease, probably by reducing the cardiac sympathetic activity. We aimed at unmasking the central effects of bromocriptine on the heart by power spectrum analysis. Ten healthy subjects (aged 31+/-2 years) in supine and sitting positions were evaluated after the administration of bromocriptine (2.5 mg) alone and after pharmacological peripheral D(2)-like blockade by domperidone (20 mg). We calculated (autoregressive method) the following: the low-frequency (LF) component (an index of cardiac sympathetic tone), the high-frequency (HF) component (an index of cardiac vagal tone), and the LF/HF ratio (an index of cardiac sympathovagal balance). With subjects in the supine position, bromocriptine alone induced a significant increase in the LF component and the LF/HF ratio, together with a reduction in norepinephrine plasma levels and blood pressure values. These conflicting effects can be explained as the combined result of direct and indirect (reflex-mediated) actions of bromocriptine in vivo. No changes in cardiac autonomic drive were observed with subjects in the sitting position. After domperidone pretreatment, bromocriptine induced a reduction in the LF component and in the LF/HF ratio. The sitting position caused an increase in heart rate and in the LF/HF ratio. We demonstrated both peripheral and central effects of bromocriptine. In particular, pretreatment with a peripheral antagonist (domperidone) allowed us to unmask the central effect of bromocriptine on cardiac sympathetic drive.

Adult↗

Altered values of heart rate variability in patients with relapse of atrial fibrillation during the first week after electrical cardioversion: preliminary data.

BACKGROUND: It has not so far been elucidated whether the autonomic nervous system plays a role in the pathogenesis of atrial fibrillation relapse after electrical cardioversion. METHODS: In 40 consecutive patients with atrial fibrillation (22 males, 18 females, mean age 60 +/- 2 years) submitted to successful electrical cardioversion (external in 26 and low-energy internal in 14) we evaluated the heart rate variability (24-hour Holter recording) immediately after restoration of sinus rhythm in order to assess the cardiac sympatho-vagal drive. RESULTS: Patients with atrial fibrillation relapse within the first week of electrical cardioversion were characterized by a significantly higher low/high frequency ratio. CONCLUSIONS: Despite the heterogeneity of the studied population (concerning both the therapy and etiology of atrial fibrillation), our data strongly suggest that the evaluation of the low/high frequency ratio by means of power spectral analysis immediately after electrical cardioversion is a useful tool for the identification of those patients who are prone to atrial fibrillation recurrence. Our conclusions are supported by the finding of high positive and negative predictive values for the low/high frequency ratio both in the 24-hour period and during daytime.

Aged↗

[Arrhythmia risk stratification based on clinical and functional data].

The term "sudden death" indicates a natural and rapid death, an unexpected event in patients with high mortality rates such as those with heart failure. Sudden death in patients with heart failure is responsible for some of 40% of all deaths. A detailed clinical evaluation in patients with heart failure is extremely helpful for risk stratification. Although sex has been shown to have no prognostic relevance, heart failure due to coronary artery disease is associated with a higher mortality rate when compared to other etiologies. Left ventricular ejection fraction is the independent risk factor with the highest predictive value of survival. However, in patients with heart failure, except for the advanced stages, sudden death shows an incidence comparable with that of progressive pump failure. Like left ventricular ejection fraction, even the functional classifications of heart failure (such as NYHA) are to be considered as a non-specific marker of overall mortality. In fact, despite the close relation between advanced disease stages and a higher mortality rate, a large overlap has been demonstrated for the intermediate classes. The noninvasive assessment of oxygen consumption during cardiopulmonary exercise testing has been recognized as an independent risk factor and patients with a peak oxygen consumption < 10 ml/kg/min should be recommended for cardiac transplantation. In these patients no clear relation with an increased risk of sudden death has been demonstrated. In conclusion, the commonly employed clinical-functional indexes (left ventricular ejection fraction, functional classifications, peak oxygen consumption during cardiopulmonary testing) are significant predictors of overall mortality, however they are useless in the risk stratification for death due to fatal arrhythmias.

Arrhythmias, Cardiac↗

Regulation of TCL1 expression in B- and T-cell lymphomas and reactive lymphoid tissues.

Chromosomal rearrangements observed in T-cell prolymphocytic leukemia involve the translocation of one T-cell receptor gene to either chromosome 14q32 or Xq28, deregulating the expression of cellular protooncogenes of unknown function, such as TCL1 or its homologue, MTCP1. In the human hematopoietic system, TCL1 expression is predominantly observed in developing B lymphocytes, whereas its overexpression in T cells causes mature T-cell proliferation in transgenic mice. In this study, using a newly generated monoclonal antibody against recombinant TCL1 protein, we extended our analysis mainly by immunohistochemistry and also by fluorescence-activated cell sorting and Western blot to a large tumor lymphoma data bank including 194 cases of lymphoproliferative disorders of B- and T-cell origin as well as reactive lymphoid tissues. The results obtained show that in reactive lymphoid tissues, TCL1 is strongly expressed by a subset of mantle zone B lymphocytes and is expressed to a lesser extent by follicle center cells and by scattered interfollicular small lymphocytes. In B-cell neoplasia, TCL1 was expressed in the majority of the cases, including lymphoblastic lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, follicular lymphoma, Burkitt lymphoma, diffuse large B-cell lymphoma (60%), and primary cutaneous B cell lymphoma (55%). TCL1 expression was observed in both the cytoplasmic and nuclear compartments, as confirmed by Western blot analysis. Conversely, TCL1 was not expressed in Hodgkin/Reed-Sternberg cells, multiple myelomas, marginal zone B-cell lymphomas, CD30+ anaplastic large cell lymphoma, lymphoblastic T-cell lymphoma, peripheral T-cell lymphoma, and mycosis fungoides. These data indicate that TCL1 is expressed in more differentiated B cells, under both reactive and neoplastic conditions, from antigen committed B cells and in germinal center B cells and is down-regulated in the latest stage of B-cell differentiation.

Aged↗

Effects of low-dose adrenomedullin on cardiac function and systemic haemodynamics in man.

The cardiovascular effects of low-dose adrenomedullin (ADM, 1, 2 and 3 pmol kg-1 min-1 for 30 min each) were evaluated in six healthy subjects in a placebo controlled, cross-over study by determining cardiac volumes, systolic and diastolic function (echocardiography) and systemic haemodynamics before, during and after ADM or placebo. High-resolution ultrasound was used to evaluate changes in carotid artery distension. ADM caused a +85% increment in its plasma levels and significantly increased plasma cyclic adenyl monophosphate (cAMP). Compared with placebo, ADM induced significant decrements in left ventricular (LV) systolic diameter and systemic vascular resistance, and increments in LV posterior wall thickening, ejection fraction and cardiac index. Right and left atrial emptying fraction and carotid artery distention increased. LV diastolic function, heart rate, and plasma renin activity did not change, whereas packed cell volume increased. These results indicate that ADM influences cardiovascular function and systemic haemodynamics at physiological plasma levels in man mainly because of its vasodilating activity, leading to reduced afterload.

Adrenomedullin↗

24-hour heart rate variability in patients with vasovagal syncope.

Since alterations in the autonomic nervous system are thought to play a major role in the pathogenesis of vasovagal syncope, we characterized the chronic autonomic profile of 44 patients with syncope and 20 healthy subjects by means of heart rate variability using 24-hour Holter recordings (time- and frequency-domain indexes), and evaluated whether the different types of responses to tilting (vasodepressive versus cardioinhibitory) could be associated with different cardiac autonomic patterns. Twenty-three patients exhibited a positive response to tilting, which was vasodepressive in 11 patients and cardioinhibitory in 12 patients. All vasodepressive patients had a standard deviation of the averages of NN (SDANN) intervals in all 5-minute segments lower than 100 ms. Patients with vasodepressive syncope also had significantly lower values of RMSSD (the 24-hour square root of the mean of the sum of the squares of differences between adjacent normal RR intervals) than those with cardioinhibitory response, and lacked the day-night rhythm of the low frequency/high frequency ratio. However, only SDANN values correctly identified patients with vasodepressive response to tilting. We conclude that (1) the population of patients with vasovagal syncope is heterogeneous, (2) patients with vasodepressive syncope have a peculiar chronic autonomic profile as assessed by 24-hour heart rate variability analysis, and (3) the evaluation of the autonomic profile in 24-hour Holter recordings could be of value in the diagnosis of patients with syncope.

Adolescent↗

Cardiovascular effects of parathyroid hormone: a study in healthy subjects and normotensive patients with mild primary hyperparathyroidism.

The aim of the study was to evaluate: 1) the cardiovascular function and the autonomic drive to the heart in patients affected by primary hyperparathyroidism (pHPT) with no evidence of renal and cardiovascular complications; 2) the cardiovascular effects of acute administration of PTH in normal subjects. In 14 patients affected by mild asymptomatic pHPT echocardiographic assessment of cardiovascular function and of the mechanic properties of the brachial and carotid artery, heart rate variability and the dispersion of QT interval were performed before and 6 months after successful surgery. Twenty age- and sex-matched healthy subjects were included in the study. Five healthy volunteers underwent a single blind, placebo-controlled, random order, cross-over study with infusion of PTH (hPTH 1-34, 200 U in saline over 5 min) or placebo. Echocardiographic assessment of cardiovascular function, heart rate variability, and QT interval were performed between 20 and 25 min after the start of the infusion and repeated after 15 min of tilting at 60 degrees. In pHPT patients the echocardiographic parameters were normal; left ventricular isovolumetric relaxation time was always in the normal range, but significantly shorter than in control subjects, suggesting an increased sympathetic stimulation. Arterial diameters and thickness, blood pressure, and QT interval were not significantly different with respect to normal subjects and were unchanged 6 months after surgery. pHPT patients lacked the circadian rhythm of the low frequency to high frequency ratio, suggesting an increased sympathetic drive to the heart at nighttime. In normal subjects there were no significant differences in basal echocardiographic measurements during PTH infusion with respect to placebo and in the hemodynamic response to tilt. These results suggest that cardiovascular function is substantially normal in normotensive pHPT patients with mild hypercalcemia. A modulation of the adrenergic control of circulation seems to be associated with hypercalcemia and/or chronic PTH excess, but its biological relevance needs further investigations.

Adult↗

C-type natriuretic peptide does not affect plasma and urinary adrenomedullin in man.

To investigate whether C-type natriuretic peptide (CNP) at pathophysiological plasma levels stimulates the release of adrenomedullin (ADM) in man, six healthy subjects (three men and three women, mean age 35 +/- 3 years, range 33-40 years) received an intravenous infusion of synthetic human CNP-22 (2 pmol kg-1 min for 2 h), in a single-blind, placebo-controlled, random order, cross-over study, with measurements of the plasma levels of cyclic guanosine monophosphate (cGMP), ADM, renin and atrial natriuretic peptide (ANP), arterial pressure, heart rate, renal blood flow (para-aminohippurate clearance), glomerular filtration rate (creatinine clearance), and the urinary excretion rates of cGMP, ADM and sodium. Infusion of CNP induced increases in its own levels (from 1.17 +/- 0.11 up to 21.13 +/- 1.41 pmol l-1) without modifying the plasma levels of cGMP, ADM, renin and ANP, the urinary excretion rate of ADM and cGMP, renal haemodynamics and sodium excretion. These data indicate that circulating CNP is not involved in the regulation of ADM release, renal haemodynamics and sodium excretion in man.

Adrenomedullin↗

In vivo evidence that endogenous dopamine modulates sympathetic activity in man.

Dopamine receptors type 2 (D2)-like receptor blockers cause an increase in the norepinephrine response to intense physical exercise. However, during intense physical exercise, D2-like antagonists also cause an increase in the epinephrine response, which itself might cause an increase in plasma norepinephrine through the activation of beta2 presynaptic receptors. Therefore, we evaluated the effect of domperidone, a D2-like antagonist, on the norepinephrine response to physical exercise in 6 Addison patients (3 were adrenalectomized and 3 had adrenal tuberculosis). In these patients, the norepinephrine increase observed during exercise was significantly higher after the administration of domperidone than a placebo (F=4,328; P<0.001). Because peripheral plasma norepinephrine does not reflect the sympathetic tone to the heart accurately, we evaluated the effect of domperidone administration (20 mg orally) on the sympathovagal balance, which was measured by the ratio between the high- and low-frequency components of heart rate variability, in 9 normal volunteers in the supine and sitting positions. When compared with placebo, domperidone caused a significant increase in the low/high frequency ratio (P<0.05) in the sitting position without modifying basal and stimulated norepinephrine plasma levels or blood pressure. These data support a role for endogenous dopamine in modulating norepinephrine release by human sympathetic nerves in vivo.

Adrenal Gland Diseases↗

Effects of clonidine on power spectral analysis of heart rate variability in mild essential hypertension.

Patients with essential hypertension often show alterations of the autonomic nervous system. We evaluated the sympathetic and parasympathetic drive to the heart in 12 mildly hypertensive patients and 9 healthy subjects by power spectral analysis of heart rate variability. All subjects underwent measurements of RR interval, low (LF) and high frequency (HF) components of heart rate variability, LF/HF ratio and blood pressure in the resting and sitting positions, both before and after oral clonidine (300 microg), a central sympatholytic agent. In the supine position before clonidine, hypertensive patients had higher blood pressure and lower HF values than healthy subjects. Clonidine induced increases in RR interval and HF in both groups, while LF and LF/HF ratio decreased in healthy subjects, but not in hypertensive patients. On assuming the sitting position, both groups showed reductions in RR and HF and increments in LF and LF/HF. In healthy subjects, the response to the postural challenge was unaffected by clonidine. In contrast, hypertensive patients showed no changes in LF and LF/HF ratio, and a significantly lower decrease in HF. These differences were probably due to the existence of two subsets of patients, one exhibiting similar responses to clonidine as healthy subjects, and the other showing no appreciable response to the drug. These results suggest that hypertensive patients have an altered sympatho-vagal balance to the heart, which can be unmasked by clonidine. This phenomenon should be taken into account to achieve a better control of the overall cardiovascular risk of hypertensive patients.

Administration, Oral↗

Deregulated expression of TCL1 causes T cell leukemia in mice.

The TCL1 oncogene on human chromosome 14q32.1 is involved in the development of T cell leukemia in humans. These leukemias are classified either as T prolymphocytic leukemias, which occur very late in life, or as T chronic lymphocytic leukemias, which often arise in patients with ataxia telangiectasia (AT) at a young age. The TCL1 oncogene is activated in these leukemias by juxtaposition to the alpha or beta locus of the T cell receptor, caused by chromosomal translocations t(14:14)(q11:q32), t(7:14)(q35:q32), or by inversions inv(14)(q11:q32). To show that transcriptional alteration of TCL1 is causally involved in the generation of T cell neoplasia we have generated transgenic mice that carry the TCL1 gene under the transcriptional control of the p56(lck) promoter element. The lck-TCL1 transgenic mice developed mature T cell leukemias after a long latency period. Younger mice presented preleukemic T cell expansions expressing TCL1, and leukemias developed only at an older age. The phenotype of the murine leukemias is CD4-CD8+, in contrast to human leukemias, which are predominantly CD4+CD8-. These studies demonstrate that transcriptional activation of the TCL1 protooncogene can cause malignant transformation of T lymphocytes, indicating the role of TCL1 in the initiation of malignant transformation in T prolymphocytic leukemias and T chronic lymphocytic leukemias.

Animals↗

Effects of exercise on natriuretic peptides and cardiac function in man.

We evaluated cardiac function and the plasma levels of atrial (ANP) and brain (BNP) natriuretic peptides during bicycle (B) and hand-grip (HG) exercises in eight healthy males. Each test was preceded by a control protocol in resting conditions. Left ventricular (LV) function (echocardiography) was evaluated during both exercises. Atrial function was assessed only during HG. Plasma ANP significantly increased during B (+236%) and HG (+77%), while there was a significant trend towards higher plasma BNP levels during B (+41%) and HG (+30%) than during the corresponding control tests. Plasma ANP correlated with heart rate in both tests, with left atrial volume, pulmonary vein flow systolic fraction and mitral flow E/A ratio in HG; BNP in both test correlated with LV dimensions and function. These data suggest that during exercise the cardiac release of ANP and BNP is differently regulated and related to changes in left atrial and LV function, respectively.

Adult↗

Cardiac autonomic modulation and incidence of late potentials in essential hypertension: role of age, sex, ventricular mass and remodeling.

The influence of age, sex, left ventricular hypertrophy (LVH) and geometry on the autonomic activity to the heart was investigated in 96 hypertensive out-patients (53 men, mean age 53 +/- 9 years) and 39 healthy subjects (19 men, mean age 43 +/- 1 years). Using 24-h Holter recordings, time [the standard deviation of all RR intervals (SDNN) and the square root of the mean of the squared differences between adjacent normal RR intervals (RMSSD)] and power spectral analysis of RR intervals [Fast Fourier algorithm, low/high frequency (LF/HF) ratio] were calculated over 24 h, daytime (D) and nighttime (N) periods in all subjects. Signal averaged electrocardiogram was recorded in 50 patients to detect late potentials. Stepwise multiple linear regression analysis showed that the 24-h LF/HF ratio was influenced by age and sex, D-LF/HF by age and N-LF/HF by sex, a higher LF/HF ratio being found in younger patients and in men. These data suggest a more prominent sympathetic modulation of cardiac activity in these groups. No differences in RR period variations were observed between patients with or without LVH. Late potentials were observed in 10 patients, and did not correlate with any of the measured parameters.

Action Potentials↗

Different effects of atrial and C-type natriuretic peptide on the urinary excretion of endothelin-1 in man.

1. Following the observation that brain natriuretic peptide enhances the urinary excretion rate of endothelin-1, the relationship between natriuretic peptides and urinary endothelin-1 was further investigated. Six healthy volunteers received, on three different occasions, increasing doses of atrial or C-type natriuretic peptide (0, 2 and 4 pmol.min-1.kg-1 for 1 h each), or placebo.2. Atrial natriuretic peptide caused significant increases in the urinary excretion of cGMP, sodium and endothelin-1, without affecting plasma endothelin-1, renal plasma flow, glomerular filtration rate and urine flow rate. C-type natriuretic peptide did not modify any of these parameters. During atrial natriuretic peptide infusion, urinary endothelin-1 directly correlated with plasma atrial natriuretic peptide, urinary cGMP and sodium excretion.3. These results indicate that enhancement of the urinary excretion of endothelin-1 by natriuretic peptides is dose-dependent and somewhat related to their ability to bind to natriuretic peptide receptors A, activate guanylate cyclase and induce a natriuretic response.

Adult↗

Effects of acute clonidine administration on power spectral analysis of heart rate variability in healthy humans.

1. To investigate the relationship between the autonomic drive to the heart and heart rate variability, as evaluated by power spectral analysis, we studied the effect of clonidine (300 microg), a central sympatholytic agent, on heart rate variability. 2. Six healthy subjects (mean age 31 +/- 3 years) were studied in the supine and the sitting position (15 min each) on two different occasions, respectively, before and after clonidine administration. Using an autoregressive approach, the low frequency (LF) and the high frequency (HF) components of power spectral analysis were measured, and their ratio was calculated. Blood pressure was monitored throughout the study and plasma catecholamines were measured at the end of each period. 3. Before clonidine, assumption of the sitting position induced increases in LF, LF/HF ratio, blood pressure and plasma noradrenaline. Clonidine induced remarkable reductions in the normalized values of the LF component and the LF/HF ratio in both the resting and the sitting position (supine: LF = -68%, LF/HF ratio = -80%; sitting: LF = -23%, LF/HF ratio = -55%) without affecting the central frequencies of LF and HF components. Blood pressure and plasma catecholamines also significantly decreased after clonidine. 4. These results support the hypothesis that the LF component of HRV, expressed in normalized units, is an indicator of the sympathetic control of the heart. In addition, this component seems to be largely of central origin, because it is markedly reduced by the central sympatholytic action of clonidine.

Adult↗

Low-dose C-type natriuretic peptide does not affect cardiac and renal function in humans.

In experimental animals, C-type natriuretic peptide (CNP) has vasodilating, hypotensive, and natriuretic activities. The role of circulating CNP in the overall regulation of cardiac and renal function in humans is less defined, in both health and disease. We measured cardiac volumes, diastolic and systolic functions, systemic (Doppler echocardiography) and renal hemodynamics, intrarenal sodium handling (lithium clearance method), plasma and urinary cGMP, plasma renin concentration, and plasma aldosterone level in six healthy volunteers (mean age, 33+/-3 years) receiving CNP (2 and 4 pmol/kg per minute for 1 hour each) in a single-blind, placebo-controlled, random-order, crossover study. During CNP infusion, plasma CNP increased from 1.17+/-0.23 to 41.52+/-4.61 pmol/L (ie, 4- to 10-fold higher levels than those observed in disease states) without affecting plasma and urinary cGMP, cardiac volumes, dynamics of left and right heart filling, cardiac output, arterial pressure, renal hemodynamics, intrarenal sodium handling, sodium excretion, or plasma levels of renin and aldosterone. The finding that increments in plasma CNP within the pathophysiological range have no effects on systemic hemodynamics, renal function, or the renin-angiotensin system do not support the hypothesis that CNP may act as a circulating hormone in humans.

Adult↗