PubMed Health⌕ Search

Biomedical subjects

N Alessandri

Publications and source records attributed to N Alessandri.

At least 19 recordsLinked to original sources
PubMed2005

Cortisol circadian rhythm and 24-hour Holter arterial pressure in OSAS patients.

Obstructive sleep apnea syndrome (OSAS) is a syndrome in which the principal symptom is apnea during sleep. Hypoxia in OSAS is a stress condition, which when prolonged in time, could alter hypothalamo-hypophysial-suprarenal control and the cortisol cicadian rhythm. We studied 28 patients with OSAS (30-60 years old), 20 female and 8 male. We calculated the OSAS class according to the Simmons classification. Twenty of the 28 patients maintained unmodified cortisol circadian rhythms, while 8 had cortisol levels more elevated in late and nocturnal hours. Holter monitoring showed arterial hypertension in 8 of the 28 patients (the same patients with cortisol circadian rhythm alteration). Our data seem to indicate that when the OSAS patients lack cortisol circadian rhythm they are having arterial hypertension.

Adult↗
PubMed2001

ET-1 levels in cardioischemic patients undergoing atrial pacing.

Atrial pacing (AP) procedure was carried out in 11 cardioischemic patients to reproduce tachycardia-induced myocardial ischemia. Six control subjects underwent the same procedure until the maximum pacing rate was reached. During the procedure, endothelin-1 (ET-1) and plasma lactate levels were measured in the coronary sinus and in the aortic root. In all the patients, atrial pacing provoked electrocardiographic signs and metabolic evidence of myocardial ischemia and a significant decrease (p<0.001) in left ventricular ejection fraction. At AP-induced ischemia, coronary sinus (17.31 +/- 4.20 pg/mL) and arterial (9.60 +/- 3.31 pg/mL) ET-1 plasma levels were significantly different (p<0.001) in the patients. On the contrary, at maximum pacing rate, no significant difference (p=0.186) emerged between coronary sinus (9.72 +/- 1.09 pg/mL) and arterial (8.95 +/- 0.75 pg/mL) plasma ET-1 levels in the control group. These results suggest that, in cardioischemic patients, tachycardia can induce the coronary endothelium to release significant amounts of ET-1.

Adult↗
PubMed2001

Rheumatic fever recurrence: a possible cause of restenosis after percutaneous mitral valvuloplasty.

BACKGROUND: We evaluated the occurrence of a rapid process of restenosis after percutaneous mitral valvuloplasty (PMV), initiated by the recurrence of acute rheumatic fever. Restenosis after PMV has been mainly related to a high echocardiographic score (> or = 8) indicating a severely compromised mitral valve apparatus. METHODS: From 1986 to 1996, 120 patients underwent PMV by the transseptal approach at our Institution. The mean follow-up time was 58 +/- 32 months (range 3 months to 9 years). RESULTS: Restenosis occurred in 10 patients (8.3%): in 4 restenosis was found within a relatively short period of time (1 to 3 months) following a documented recurrence of acute rheumatic fever; in the other 6 patients there was a gradual loss of the initial gain in the mitral valve area. CONCLUSIONS: These data suggest two potential mechanisms of restenosis: 1) a more common slow process, due to turbulent flow-trauma on the mitral valve; 2) a rapid process that relates to valvulitis consequent to a recurrence of acute rheumatic fever. In consideration of the second possibility, after PMV prophylactic treatment may be warranted at least in those patients who are at high risk of streptococcal infection.

Adolescent↗
PubMed2000

Mitral prolapse. A heart anomaly in a clinical neuroendocrine context.

Mitral valve prolapse was identified as a separate nosological entity by Barlow in 1963. A characteristic of this cardiac anomaly is blood reflux into the left atrium during the systole owing to the lack of adhesion between valve flaps. The presence of symptoms linked to neuroendocrine dysfunctions or to the autonomic nervous system lead to the onset of the pathology known as mitral valve prolapse syndrome (MVPs). It is usually diagnosed by chance in asymptomatic patients during routine tests. MVPs includes complex alterations to the neurovegetative system and a high clinical incidence of neuropsychiatric symptoms, like anxiety and panic attacks. A neuroendocrine mechanism thought to underlie panic attacks was recently proposed based on a biological model. In general, the cardiovascular anomaly manifested by patients with MVPs could be defined in neuroendocrine-constitutional terms.

Humans↗
PubMed1999

Enoximone coupled to very low dose dobutamine echocardiography detects myocardial viability in akinetic and dyskinetic post-myocardial infarcted areas.

Dobutamine and enoximone stimulate independently inotropic reserve by increasing intracellular cyclic adenosine monophosphate. The potential of enoximone (0.75 mg/kg body weight over 10 minutes) followed by very low dose (2.5 microg/kg/min) dobutamine echocardiography to predict recovery of ventricular function in akinetic and dyskinetic postinfarcted areas was studied. We enrolled 22 patients with previous Q-wave myocardial infarction and regional wall motion abnormalities related to left anterior descending arterial disease, left ventricular ejection fraction <40%, and all scheduled for myocardial revascularization. A 10 microg/kg/min dobutamine test was performed 48 hours before the study protocol. Test images obtained at peak of pharmacodynamic effects were compared with those obtained at 4 months after myocardial revascularization. We used a 16-segment ventricular model and a 5-grade scoring system. Resting regional myocardial dysfunction graded > or =2 was present in 267 of 352 segments evaluated. Contractile reserve (decrease in resting wall motion score > or =2 grades) at peak effect of enoximone infusion was present in 34 of 112 severely hypokinetic, 42 of 117 akinetic, and 14 of 38 dyskinetic segments. The inotropic reserve evaluated after very low dose dobutamine was observed in 34 of 112 severely hypokinetic, 49 of 117 akinetic, and 20 of 38 dyskinetic segments. After revascularization, recovery of function was observed in 31 of 112 severely hypokinetic, 49 of 117 akinetic, and 21 of 38 dyskinetic segments. Overall, there was a significant correlation between absolute score changes of segments which were abnormal at baseline (n = 267) to enoximone peak effects (r = 0.49, p <0.001) to predict absolute changes after revascularization; after dobutamine there was progress toward identity (r = 0.62, p <0.001) and the difference was significant among correlation slopes of dobutamine alone, enoximone alone, and enoximone plus very low dose dobutamine echocardiograophy (0.45+/-0.04, 0.51+/-0.04, and 0.63+/-0.04, respectively, F = 5.25, p = 0.005). Therefore, enoximone followed by very low dose dobutamine may assess myocardial viability of postinfarcted akinetic and dyskinetic areas. This test may be useful when evaluating patients with more severe cardiac failure and/or life-threatening arrhythmias.

Adult↗
PubMed1999

Pharmacological properties of trimebutine and N-monodesmethyltrimebutine.

Trimebutine [2-dimethylamino-2-phenylbutyl-3,4,5-trimethoxybenzoate hydrogen maleate (TMB)] has been demonstrated to be active for relieving abdominal pain in humans. To better understand its mechanism of action, we have tested TMB; nor-TMB, its main metabolite in humans; and their respective stereoisomers for their affinity toward sodium channels labeled by [3H]batrachotoxin, their effect on sodium, potassium, and calcium currents in rat dorsal root ganglia neurons, and their effect on veratridine-induced glutamate release from rat spinal cord slices. TMB has also been tested in an animal model of local anesthesia. TMB (Ki = 2.66 +/- 0.15 microM) and nor-TMB (Ki = 0.73 +/- 0.02 microM) displaced [3H]batrachotoxin from its binding site with affinities similar to that of bupivacaine (Ki = 7.1 +/- 0.9 microM). nor-TMB was found to block veratridine-induced glutamate release with an IC50 value of 8.5 microM, which is very similar to that of bupivacaine (IC50 = 8.2 microM); the effect of TMB was limited to 50% inhibition at 100 microM. TMB and nor-TMB blocked sodium currents in sensory neurons from rat dorsal root ganglia (IC50 = 0.83 +/- 0.09 and 1.23 +/- 0.19 microM, respectively), whereas no effect was observed on calcium currents at the same concentrations. A limited effect was observed on potassium currents (IC50 = 23 +/- 6 at 10 microM) for TMB. In vivo, when tested in the rabbit corneal reflex, TMB displayed a local anesthetic activity 17-fold more potent than that of lidocaine.

Animals↗
PubMed1998

Plasma atrial natriuretic hormone in hyperthyroidism.

In 22 hyperthyroid patients, atrial natriuretic hormone (ANH) levels (71.91 +/- 21.03 pg/ml), measured during a 3-h-Holter, were found to be significantly higher (p < 0.001) than those in 20 age-matched normal subjects (37.22 +/- 8.73 pg/ml). We have demonstrated that the presence of tachiarrhythmias does not influence ANH release. The positive and significant correlation of FT3 with both ANH and heart rate confirms the hypothesis of a direct action of thyroid hormones on ANH release.

Adult↗
PubMed1997

A potassium-channel toxin from the sea anemone Bunodosoma granulifera, an inhibitor for Kv1 channels. Revision of the amino acid sequence, disulfide-bridge assignment, chemical synthesis, and biological activity.

The potassium channel toxin secreted by the sea anemone Bunodosoma granulifera (BgK) is a 37-amino-acid peptide containing three disulfide bridges. Because a synthetic peptide corresponding to the reported sequence of BgK was found not to fold properly, the sequence was determined again. The new sequence differed from the previous one in the C-terminal tetrapeptide, which contains two cysteines involved in disulfide bridging. The revised sequence is: V C R D W F K E T A C R H A K S L G N C R T S Q K Y R A N C A K T C E L C. The toxin BgK was synthesized according to the new sequence and folded successfully. Disulfide bridges were assigned by peptide mapping on both natural and synthetic forms to be between Cys2-Cys37, Cys11-Cys30 and Cys20-Cys34. The toxin contains a C-terminal free carboxylate as shown by comparing the native toxin with two synthetic peptides containing the C-terminus in either the carboxylate or carboxamido form. Synthetic BgK inhibits binding of 125I-alpha-dendrotoxin to rat brain synaptosomal membranes, similarly to natural BgK (nanomolar range). No activity was observed on maxi-K+ channels incorporated into planar lipid bilayers. The ability of BgK to block voltage-dependent K+ channels was determined from recordings of whole cell currents in Xenopus oocytes injected with cRNA encoding three cloned Kv1 channels (Kv1.1, Kv1.2, Kv1.3) and one Kv3 (Kv3.1) channel. The Shaker-related Kv1 channels are equally affected by BgK, while the Shaw-related channel Kv3.1 is insensitive up to 0.125 microM toxin. Indeed, half blockage of the current through the three Kv1 channels tested occurred in the same concentration range (Kd = 6 nM for Kv1.1, 15 nM for Kv1.2, 10 nM for Kv1.3). The specificity of BgK for the Shaker-related K+ channels indicates that BgK is able to discriminate a large group of neuronal Kv1 channels in situ. The sequence, the disulfide bridge pattern, the secondary structure and the biological activity of BgK demonstrated that the sea anemone toxins, i.e. BgK, ShK and Kaliseptine, constitute novel molecular probes useful for investigating K+ channel properties.

Amino Acid Sequence↗
PubMed1995

[Wall elasticity of the ascending aorta in ischemic heart disease].

M-mode echocardiography was used to examine in male subjects the physical properties of the ascending aorta, 3 cm above the valvular plane. Subjects were divided into three groups based on age, lifestyle and presence or absence of vascular disease: Group A (10 recruited military young men, age 20.87 +/- 0.834 years) in good health; Group B (14 senior competitive athletes, age 49.92 +/- 8.17 years); Group C (10 patients with effort-angina, age 53.1 +/- 11.18 years). We observed that: the inner diastolic diameter of the ascending aorta was different between Group A and B (p < 0.001) and between Group A and C (p < 0.001), and it increased with aging (r = 0.7) whereas no relationship to body surface was seen (r = 0.3); the elasticity-stiffness parameters (aortic wall distensibility, aortic wall stress, wall stiffness index, wall elasticity index and modulus) of major vessels in senior athletes (Group B), were not different (p > 0.05) from military young men (Group A), although they were significantly lower (p < 0.001) in Group C patients; wall elasticity was lower in Group C patients (versus both Group A and B). Altered compliance might be the consequence of vessel structural changes and may contribute to reduce blood flow to the coronary arteries. Our data suggest that sports activity has beneficial effects; physical characteristics of great vessels do not show age-related changes.

Adult↗
PubMed1993

Clinical significance of small left-to-right shunts after percutaneous mitral valvuloplasty.

Left-to-right shunt after percutaneous mitral valvuloplasty was evaluated by contrast echocardiography in 29 patients at 24 hours and at 1, 3, 6, and 9 months after the procedure. The patients were divided into two groups: in group A (13 patients) the double-balloon technique was used; in group B (16 patients) the Inoue single-balloon technique was used. The two groups were comparable in terms of age, gender, and mitral valve area before and after percutaneous mitral valvuloplasty. A left-to-right shunt was detected in all patients 24 hours after the procedure. At 1 month follow-up the shunt was present in 12 patients of group A (92%) and in 13 of group B (81%) with a statistically significant difference (p < 0.001). At 3 months the values were 7 (54%) in group A and 6 (37.5%) in group B (p < 0.05); at 6 months the values were 3 (23%) in group A and 3 (19%) in group B (NS). At 9 months a left-to-right shunt was no longer detectable in any of the patients in either group. The disappearance of the shunt could be related to a healing process of the atrial septal injury that occurs within a few months after percutaneous mitral valvuloplasty. This process seems to be more rapid in group B patients, probably because of the smaller lesion that is produced in the atrial septum by the passage of the Inoue balloon.

Adult↗
PubMed1993

Automatic analysis of high resolution atrial activation in mitral valve stenosis.

High resolution P-waves of 28 patients having a mean age of 45 years and affected by isolated mitral valve stenosis (nine of whom showed paroxysmal atrial fibrillation) have been compared with those obtained from 30 healthy subjects about 35 years old. Our primary aim was to characterize the signal-averaged P-wave in mitral valve stenosis. Parameters which differed between the two groups in time domain analysis were the P-wave duration, the abscissa of the maximum positive voltage amplitude, the peak-to-peak amplitude and the integrated voltage-time product, which turned out to be greater in the patient class than in the healthy set; furthermore, in the frequency domain analysis, amplitudes in the range from 37 to 60 Hz were greater in healthy subjects than in patients. A successive analysis carried out to predict those patients with mitral valve stenosis who are at risk of developing paroxysmal atrial fibrillation showed that the P-wave duration and the amplitudes (in the range 60-106 Hz) were the most distinctive parameters, but, unfortunately, without any significant difference with respect to those of patients with mitral valve stenosis alone. Finally, some correlations between the age, the P-wave duration and the left atrial diameter of patients, were revealed to exist only in patients affected by episodes of atrial fibrillation.

Adult↗
PubMed1993

[The acute and 24-hour modifications to the atrial natriuretic factor in patients who have undergone mitral valvuloplasty. The hemodynamic and echocardiographic correlations].

BACKGROUND: The recent introduction of percutaneous transvenous mitral valvuloplasty (PTMV) for the treatment of mitral stenosis (MS) has provided a unique human model for the study of short-term changes in ANF secretion before and after a reduction in left atrial pressure. This study was designed to investigate the effect of a short-term reduction in left atrial pressure and volume, as determined by echocardiographic study, on ANF and other neurohumoral factor plasma levels (renin and aldosterone). MATERIALS AND METHODS: 10 patients in III FC NYHA, with normal sinus rhythm and MS underwent PTMV. Hemodynamic parameters were measured immediately before and after (20-30 minutes) PTMV. Plasma levels of ANF, aldosterone and plasma renin activity (PRA) were obtained before (24 h) and after (2 h and 24 h) valvuloplasty; echocardiographic left atrial size before (24 h) and 24 h after PTMV. RESULTS: Immediately after PTMV mean left atrial (LA) pressure decreased from 22.3 +/- 6.8 mmHg to 10.0 +/- 2.4 mmHg (p < 0.01); mitral valve area (MVA) increased from 0.99 +/- 0.28 cm2 to 2.17 +/- 0.26 cm2 (p < 0.01). 24 hours after PTMV on echocardiography, LA systolic volume decreased from 59.5 +/- 16.9 cm3 to 42.3 +/- 8.3 cm3 (p < 0.01), LA diastolic volume from 82.6 +/- 15.8 cm3 to 66.5 +/- 12.6 cm3 (p < 0.01), and LA diameter from 48.1 +/- 7.5 mm to 39.2 +/- 4.4 mm (p < 0.01). ANF plasma levels before PTMV were 64.0 +/- 36.9 fmol/ml; 2 and 24 hours after PTMV they fell to 34.2 +/- 21.6 fmol/ml (p < 0.01) and to 20.3 +/- 21.0 fmol/ml (p < 0.01), respectively. PRA values were 15.7 +/- 13.2 ng/ml/h before PTMV; 2 and 24 hours after PTMV they increased to 17.5 +/- 23.2 ng/ml/h (NS) and to 22.3 +/- 16.8 ng/ml/h (p < 0.01). The aldosterone plasma levels were 43.2 +/- 27.9 ng/dl before PTMV and 47.3 +/- 35.8 ng/dl (NS) and 45.3 +/- 28.0 ng/dl (NS) 2 and 24 hours after PTMV. CONCLUSIONS: These results indicate that LA "de-stretching" due to the MVA increase and LA pressure decrease, leads to an abrupt reduction of ANF secretion. According to other studies, PRA increases immediately after PTMV, with a further increase 24 hours after PTMV.

Adult↗
PubMed1990

Hypertrophic obstructive cardiomyopathy and infective endocarditis: a report of seven cases and a review of the literature.

Seven cases of infective endocarditis (IE) in patients with hypertrophic obstructive cardiomyopathy (HOCM) are presented in this report. The previous literature is critically reviewed, and the following points are discussed: (a) IE complicates HOCM in 5-9% of cases; (b) anatomical and haemodynamic alterations of HOCM cause microtraumas on heart valves and the endocardium; the resulting endocardial lesions represent sites for bacterial seeding as well as other congenital or acquired heart disease; (c) prognosis is worse in patients with IE associated with HOCM than in patients with IE alone or associated with congenital heart disease; (d) the most frequently isolated organisms are saprophytes; (e) most patients were exposed to bacteraemias before the onset of IE.

Adolescent↗
PubMed1990

Late potentials in idiopathic dilated cardiomyopathy.

Twenty-five patients with idiopathic dilated cardiomiopathy were investigated in order to evaluate the role of late ventricular potentials as possible markers of ventricular tachycardia or sudden cardiac death. Holter monitoring showed ventricular tachycardia in 9 patients (group A) all of whom had late ventricular potentials, (mean +/- SD length 37.22 +/- 15.83 ms and mean +/- SD voltage 5.62 +/- 2.78 microV). Mean +/- SD ejection fraction in this group was 20 +/- 9.39%. In 16 patients (group B), without ventricular tachycardia, means +/- SD ejection fraction 27.5 +/- 8.17%; late ventricular potentials were recorded in 2 patients. During the follow-up period (means +/- SD 11.53 +/- 7.19 months), 3 patients underwent heart transplantation, 2 patients underwent pace-maker implantation and 2 patients from the ventricular tachycardia group died one from sudden cardiac death and the other from progressive heart failure. No significant differences were found in the ejection fraction either between the ventricular tachycardia and the non-ventricular tachycardia group, or between the late ventricular potentials and the non-late ventricular potential groups. Negative data were also obtained when we tried to find a correlation between the ejection fraction and late ventricular potential length and/or voltage. Good results were observed with regard to sensitivity (100%), specificity (87%) and predictive accuracy (81%) but follow-up data did not specify a definite prognostic value for late ventricular potentials. The Authors conclude that late ventricular potentials are markers of patients with idiopathic dilated cardiomyopathy who are prone to ventricular tachycardia. However, the role of late ventricular potentials in sudden cardiac death is still uncertain.

Adolescent↗
PubMed1989

Effects of uncomplicated coronary artery bypass graft surgery on global and regional left ventricular function at rest. Study by equilibrium radionuclide angiocardiography.

To evaluate the effects of uncomplicated revascularization surgery on resting global and regional left ventricular function we studied 34 patients, enrolled consecutively, by radionuclide angiocardiography. After surgery, we found no significant change in global left ventricular ejection fraction; this was true even in the subgroup of 14 patients who developed paradoxical septal motion. This finding indicates that the development of paradoxical septal motion after uncomplicated cardiac surgery does not compromise global left ventricular function. Both in the subgroup of patients with paradoxical septal motion and in the subgroup without paradoxical septal motion regional ejection fraction calculations showed the same postoperative pattern consisting of increase of the proximal and distal posterolateral regional ejection fraction, increase in the inferoapical regional ejection fraction and unchanged proximal and distal septal regional ejection fraction. In our patients paradoxical septal motion is not due to pericardial effusion, conduction disturbance, septal ischemia or infarction. Our data suggest that the anteromedial translation of the entire heart during systole, due to surgical removal of constraints, may account for both the false improvement of posterolateral and inferoapical regional wall motion and the development of paradoxical septal motion.

Adult↗
PubMed1989

Heart transplant rejection detected by signal averaged QRS analysis. Preliminary results.

Detailed QRS wave analysis from the limb leads of the surface high resolution electrocardiograms recorded in five cyclosporine-treated heart transplant recipients gave good correlation with the corresponding results of endomyocardial biopsy. That is when the result of the biopsies has identified the presence of rejection, a concomitant (p = 0.001) variation in some parameters of the QRS has been observed. The reproducibility of such parameters (established by means of the correlation coefficient r) gave r values ranging from 0.6 up to 0.93. The correlation regarded parameters analyzed both in time and frequency domain. Biopsy results were divided into two classes on the basis of the presence or absence of rejection. The most significant parameters obtained from high-frequency (25-300 Hz) ECGs within a few hours of each biopsy were: a) the total high-frequency voltage amplitude Vt of the QRS and the voltage amplitude of its initial Vi and middle thirds Vm; b) the peak voltage amplitude Vp of the QRS; c) the QRS duration L; d) the integrated voltage time product I of the QRS; e) three mean voltage amplitudes V5, V6, V7, of the power spectral density constructed on the basis of the 512-point fast Fourier transform applied on each recording. The above mentioned parameters appear to be useful in predicting the biopsy result in terms of the presence or absence of rejection.

Adolescent↗