PubMed Health⌕ Search

Biomedical subjects

A Boni

Publications and source records attributed to A Boni.

15 recordsLinked to original sources
PubMed2000

Digital VLSI algorithms and architectures for support vector machines.

In this paper, we propose some very simple algorithms and architectures for a digital VLSI implementation of Support Vector Machines. We discuss the main aspects concerning the realization of the learning phase of SVMs, with special attention on the effects of fixed-point math for computing and storing the parameters of the network. Some experiments on two classification problems are described that show the efficiency of the proposed methods in reaching optimal solutions with reasonable hardware requirements.

Algorithms↗
PubMed2000

[The evaluation of the appropriateness of instrumental exams in cardiology. The case of echocardiography].

BACKGROUND: The aim of this study was to evaluate the appropriateness and utility rates of echocardiograms performed in 309 patients in an outpatient clinical setting. METHODS: Data were collected by means of a questionnaire filled in by the cardiologists who performed the examinations. Appropriateness was evaluated according to international guidelines and scored as class I: appropriate, class II: doubtful appropriateness, class III: inappropriate; the exam was deemed useful if it was able to influence the clinical decision-making; normalcy rate was also checked. The relationship between both the referring physicians and motivation of the exam and its appropriateness, and the relationship between appropriateness and both the normalcy rate and utility of the exam were assessed. RESULTS: An echocardiogram was requested by the cardiologist in 46% of patients; the more common reasons for the exam were arterial hypertension (26%), cardiac murmur (18%), palpitations (15%), and known coronary artery disease (10%). The echocardiogram was appropriate (class I) in 25% of patients, doubtfully appropriate (class II) in 39% of patients and inappropriate (class III) in 36% of patients. The appropriateness rate between the cardiologists was similar to that of other prescribing clinicians (p = NS). The highest class III rate was found in patients with hypertension, while the highest class I rate was found in patients with a cardiac murmur (p < 0.01). Normalcy rate was lower in class I than in class II and III exams (p < 0.001). The utility rate was higher in class I (76%) than in class II (13%) and III (< 1%) exams (p < 0.01). CONCLUSIONS: International guidelines can be used effectively and safely to identify (not to prescribe) the useless echocardiograms.

Chi-Square Distribution↗
PubMed1998

Acute hemodynamic effects of endogenous adenosine in patients with chronic heart failure.

OBJECTIVE: The objective of this study was to assess the acute hemodynamic effects of endogenous adenosine accumulation in patients with chronic heart failure. Exogenously administered adenosine has been shown to reduce pulmonary vascular resistance and to increase cardiac index in normal subjects and in patients with pulmonary hypertension or end-stage biventricular heart failure. Endogenous adenosine accumulation can be provoked by dipyridamole. METHODS AND RESULTS: Ultra-low-dose dipyridamole (0.07 mg/kg/min for 4 minutes) was administered in 20 patients with either symptomatic idiopathic (n = 12) or ischemic (n = 8) dilated cardiomyopathy and reduced left ventricular ejection fraction (mean 25%+/-5%). Hemodynamic variables were measured before and within 1 minute from the end of dipyridamole infusion. After dipyridamole administration, a mild but significant increase in heart rate (4.5%; p = 0.03) and reduction in mean blood pressure (6.8%; p < 0.001) without changes in right atrial pressure (p = NS) were detected. Dipyridamole increased cardiac output by 26.6% (p < 0.001), cardiac index by 24% (p < 0.001), and stroke volume by 19.8% (p < 0.001), with concomitant 24.6% reduction of systemic vascular resistance (p < 0.001). Moreover, dipyridamole reduced mean pulmonary artery pressure by 8.3% (p < 0.01) and pulmonary vascular resistance by 33.3% (p = 0.001), without changes in pulmonary wedge pressure (p = NS). A significant correlation between percent decrease from baseline in pulmonary and systemic vascular resistance (r = 0.66; p = 0.002) was found after administration of dipyridamole. CONCLUSIONS: Endogenous adenosine accumulation induced by ultra-low-dose dipyridamole infusion acutely improves the hemodynamic profile, decreasing pulmonary and, to a lower extent, systemic vascular resistance and increasing cardiac index in patients with severe chronic heart failure.

Adenosine↗
PubMed1998

[Echocardiographic evaluation of left ventricular diastolic function in patients with dilated cardiomyopathy: correlation among doppler, hemodynamic and clinical findings].

In order to evaluate the prognostic implications of either transmitral filling parameters and pulmonary artery capillary pressure, 35 patients (23 men, age 63 +/- 13 years, +/- SD) with idiopathic (n = 19) or ischemic (n = 16) dilated cardiomyopathy (NYHA class II-IV) underwent Doppler echocardiography and right cardiac catheterization. None of them had atrial fibrillation, severe mitralic valvular disease, a advanced atrial-ventricular heart block, or was pace-maker implanted. Two groups of patients were identified on the basis of status symptoms: Group 1 (n = 12; NYHA class IIa-IIb), Group 2 (n = 23; NYHA class III-IV). As to diastolic parameters, the 2 groups significantly differed in peak E velocity (p < 0.001), deceleration time (p < 0.001), E/A ratio (p = 0.0004), E wave duration (p < 0.05) and isovolumetric time relaxation (p < 0.05). A restrictive-type transmitralic filling (high mitral E wave velocity, low mitral A wave velocity, low deceleration time), was found in 4 (33%) patients of Group 1 and in 20 (86%) patients of Group 2. Group 2 patients had significantly higher pulmonary artery capillary pressure (p < 0.001) than Group 1 patients. During the follow-up (18 +/- 6 months; from 8 to 22 months), 6 patients experienced cardiac death (4 died of sudden death and 2 for congestive heart failure), 1 patient underwent cardiac transplantation, and 6 patients had deterioration of status symptoms. All of the 7 major cardiac events and 3 out of 6 deteriorations of status symptoms occurred in patients of Group 2. With a Cox analysis, deceleration time (beta-0.096, SE = 0.03, p < 0.005), pulmonary artery capillary pressure (beta-0.027, SE = 0.01, p < 0.001), and left ventricular ejection fraction (beta-0.098, SE = 0.32, p < 0.006) were predictive of major cardiac events. The univariate prognostic predictors were found to be: E/A ratio (r = 0.72, p < 0.05), deceleration time (r = -0.90, p < 0.05), and isovolumetric time relaxation (r = -0.74, p < 0.05). Assessment of transmitral filling by Doppler echocardiography is a simple, reproducible and noninvasive method, providing effective functional and prognostic information on patients with dilated cardiomyopathy. The correlation found between several transmitral filling parameters and pulmonary artery capillary pressure provides an accurate noninvasive estimation of hemodynamics in these patients.

Aged↗
PubMed1996

Compound heterozygosity for a structural apolipoprotein A-I variant, apo A-I(L141R)Pisa, and an apolipoprotein A-I null allele in patients with absence of HDL cholesterol, corneal opacifications, and coronary heart disease.

BACKGROUND: The concentration of HDL cholesterol is inversely correlated with the risk of coronary heart disease (CHD). Some rare mutations in the apolipoprotein (apo) A-I gene are associated with low levels of HDL cholesterol. Their association with cardiovascular risk is controversial. METHODS AND RESULTS: We studied the molecular defects underlying corneal opacities and absence of HDL cholesterol in three brothers and a sister. In a family study, the importance of these defects for lipid metabolism and manifestation of coronary heart disease was investigated. The frequency of these apo A-I defects was assessed by genotype and phenotype analysis of 477 DNA- and plasma samples, respectively, from the population. The four patients were compound heterozygotes for a null allele and a missense mutation in the apo A-I gene that leads to a leucine-->arginine substitution at residue 141 [apo A-I(L141R)Pisa]. Heterozygotes for either the null allele or the structural variant had half-normal concentrations of HDL cholesterol and apo A-I compared with unaffected family members. Apo A-I(L141R)Pisa was detected in one more unrelated subject. Coronary angiography of the four compound heterozygotes revealed the presence of CHD in all male patients, whose ages ranged between 45 and 52 years. They presented with additional risk factors, including elevated LDL cholesterol levels, obesity, and arterial hypertension. Despite complete HDL deficiency and hypercholesterolemia, CHD was absent in the 51-year-old premenopausal sister. CONCLUSIONS: Apo A-I deficiency may lead to premature atherosclerosis if present in conjunction with additional cardiovascular risk factors.

Adolescent↗
PubMed1991

The reservoir-pusher in breast reconstructive surgery.

This paper describes a surgical instrument designed for the subcutaneous insertion of the Becker expander reservoir. The instrument has proven to be particularly easy to use, and it has several safety features for avoiding rupture of the reservoir and the linkup tube.

Breast↗
PubMed1977

Cathepsin D agglutinators in rheumatoid arthritis. I. Increased CDA titers in serum and synovial fluid of patients with seropositive RA.

The incidence and titer of cathepsin D agglutinators (CDA) were significantly higher in seropositive rheumatoid arthritis (RA) sera than in the sera of healthy blood donors or of patients with other rheumatic diseases, including seronegative RA. A significant elevation was also found in synovial fluid (SF) samples from seropositive RA patients. CDA in the SF tended to be increased when compared with the corresponding serum. The levels of CDA correlated positively with those of rheumatoid factors (RF) when the latter were determined with IgG anti-CD Ripley-coated erythrocytes, but not when they were determined by the Waaler-Rose or latex tests. The increased CDA titers do not seem to be the result of significant amounts of IgM agglutinators or of the presence of IgM-RF. These findings suggest the existence of a link between the formation of RF and CDA, but the nature of this link cannot be fully explained.

Agglutinins↗