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Biomedical subjects

E Pesonen

Publications and source records attributed to E Pesonen.

At least 37 records · Page 2Linked to original sources
PubMed1998

Treatment of missing data values in a neural network based decision support system for acute abdominal pain.

In this study different substitution methods for the replacement of missing data values were inspected for the use of these cases in a neural network based decision support system for acute appendicitis. The leucocyte count had the greatest number of missing values and was used in the analyses. Four different methods were compared: substituting means, random values, nearest neighbour and a neural network. There were great differences in the substituted leucocyte count values between different methods and only nearest neighbour and neural network agreed about most of the cases. The importance of the substitution method for the final diagnostic classification of the patients by the neural network based decision support system was found to be small.

Abdominal Pain↗
PubMed1998

Nitric oxide, oxygen, and prostacyclin in children with pulmonary hypertension.

OBJECTIVE: To test the vasodilatory response of the pulmonary vascular bed in children with pulmonary hypertension. DESIGN: Prospective dose response study in which the effects of inhaled nitric oxide (NO) are compared with those of oxygen and intravenous prostacyclin. PATIENTS AND INTERVENTIONS: The vasodilator test was performed in 20 patients in whom mean pulmonary artery pressure (PAPm) was > or = 40 mm Hg and /or pulmonary vascular resistance index was > or = 4 Um2. Haemodynamic effects of inhaled NO (20, 40, and 80 ppm) at a fractional inspired oxygen (FiO2) value of 0.3, pure oxygen, oxygen at FiO2 0.9-1.0 combined with NO as above or with intravenous prostacyclin at 10 and 20 ng/kg/min were measured. RESULT: NO decreased PAPm with a dose response from 20 to 40 ppm (mean change at 40 ppm-5.50, 95% confidence interval (CI) -7.98 to -3.02 mm Hg. Maximal decrease in the ratio of pulmonary to systemic vascular resistance was achieved with a combination of NO 80 ppm and oxygen (-0.18, 95% CI -0.26 to -0.10). Increase in the pulmonary flow index was greatest with pure oxygen in those with an intracardiac shunt (8.52, 95% CI -0.15 to 17.20 l/min/m2). Neither NO nor oxygen altered systemic arterial pressure but intravenous prostacyclin lowered systemic arterial pressure and resistance. CONCLUSIONS: NO selectively reduces pulmonary vascular resistance and pressure maximally at 40 ppm. Oxygen reduces pulmonary vascular resistance and NO potentiates this reduction without affecting the systemic circulation. Prostacyclin vasodilates the pulmonary and the systemic circulations.

Administration, Inhalation↗
PubMed1998

Diagnosis of acute appendicitis in two databases. Evaluation of different neighborhoods with an LVQ neural network.

The use of an artificial neural network system was studied in the diagnosis of acute abdominal pain, especially acute appendicitis, with patients from Finland and Germany. Separate Learning Vector Quantization (LVQ) neural networks were trained with a training set from each database and also with a combined database. Each neural network was evaluated separately with a test set of cases from each database. With the combined database different neighborhood methods were compared to find the optimal choice for this decision-making problem. The acute appendicitis cases of the Finnish test data set were classified well with all the networks, but the cases of the German test set were difficult to classify for the Finnish network. The use of larger neighborhoods increased the sensitivity of the classification by nearly 10%. The differences in the results of the Finnish and German databases suggest that there are differences in the data collection or patient populations between centers. Therefore, care must be taken when using decision-support systems which have been developed in other centers. Neural networks offer a method to evaluate differences between databases. With the use of larger neighborhoods, the effects of the differences on the accuracy of the classification can be partly diminished.

Abdominal Pain↗
PubMed1997

Epidemiology of idiopathic cardiomyopathies in children and adolescents. A nationwide study in Finland.

Although idiopathic cardiomyopathies are prognostically important and are a common indication for cardiac transplantation in all age groups, the incidence and age distribution of idiopathic cardiomyopathies in a well-defined pediatric population have been poorly characterized. A retrospective study was carried out in Finland in 1980-1991 to obtain information on the epidemiology of childhood cardiomyopathies. The medical records of all patients aged birth to 20 years with cardiomyopathy from the five university hospitals and 16 central hospitals covering the entire country were reviewed. Moreover, data on causes of death from the Finnish National Census Bureau were examined. Of the 808 potential cases screened, 118 infants, children, and adolescents, representing an average age-specific population of 1.4 million, were definitely identified as having idiopathic cardiomyopathy. The average annual occurrence of new cases was 0.65 per 100,000 population (95% confidence interval (CI) 0.53-0.79). If the 15 cases diagnosed only after death during the 12-year study period were included, the occurrence increased to 0.74 per 100,000 population per year. Fifty-six new cases of dilated cardiomyopathy and 40 new cases of hypertrophic cardiomyopathy were diagnosed during the study period, giving average annual occurrences of 0.34/100,000/year (95% CI 0.26-0.44) and 0.24/100,000/year (95% CI 0.17-0.33) for new cases of dilated and hypertrophic cardiomyopathies, respectively. At the end of 1991, the prevalence of dilated cardiomyopathy was 2.6/100,000 (95% CI 1.8-3.6) and that for hypertrophic cardiomyopathy was 2.9/100,000 (95% CI 2.0-4.0). The number of new cases of dilated cardiomyopathy per year increased over the study period, whereas the annual occurrence of hypertrophic cardiomyopathy remained relatively constant. Marked variability was seen in occurrence among the different age groups of children with dilated cardiomyopathy, suggesting that different pathophysiologic mechanisms, and possibly etiologies, may exist in different age groups.

Adolescent↗
PubMed1997

Cholesterol and carotid artery wall in children and adolescents with familial hypercholesterolaemia: a controlled study by ultrasound.

The carotid artery wall was studied with ultrasound in 23 children and adolescents with familial hypercholesterolaemia and in 23 age-matched healthy controls. The study revealed changes in the carotid artery wall related both to familial hypercholesterolaemia and to age. In the control subjects, the carotid artery wall became stiffer with age. In the patients with hypercholesterolaemia, no clear age-dependence was found, but wall stiffness correlated with total and low-density lipoprotein cholesterol. The intimal-medial wall thickness was associated with serum total cholesterol, low-density lipoprotein and triglyceride concentrations, and correlated inversely with the ratio of high-density lipoprotein to total cholesterol. Carotid artery wall properties seem to be associated with the degree of hypercholesterolaemia and the high-density lipoprotein-to-total cholesterol ratio even in children. In childhood and adolescence it is already possible, with ultrasound, to detect changes in the arterial wall related both to familial hypercholesterolaemia and to age.

Adolescent↗
PubMed1997

Is neural network better than statistical methods in diagnosis of acute appendicitis?

Three statistical classification methods: discriminant analysis, logistic regression analysis and cluster analysis were compared with the back-propagation neural network algorithm in the diagnosis of acute appendicitis. The differences in the classification accuracy, which were evaluated with the receiver operating characteristic (ROC) curve were small, though discriminant analysis and back-propagation showed slightly better results than the other methods. The agreement of the methods on the diagnosis increased the accuracy of the classification, so that the number of misclassified cases reduced. The back-propagation neural network offers a good choice for statistical classification methods, but it was not found to be better than them. The use of several methods and their agreement as the basis of the diagnosis seems to give the best results for this diagnostic classification problem.

Appendicitis↗
PubMed1996

Comparison of different neural network algorithms in the diagnosis of acute appendicitis.

Four different neural network algorithms, binary adaptive resonance theory (ART1), self-organizing map, learning vector quantization and back-propagation, were compared in the diagnosis of acute appendicitis with different parameter groups. The results show that supervised learning algorithms learning vector quantization and back-propagation were better than unsupervised algorithms in this medical decision making problem. The best results were obtained with the learning vector quantization. The self-organizing map algorithm showed good specificity, but this was in conjunction with lower sensitivity. The best parameter group was found to be the clinical signs. It seems beneficial to design a decision support system which uses these methods in the decision making process.

Adolescent↗
PubMed1996

Myocardial function in children and adolescents after therapy with anthracyclines and chest irradiation.

Cardiotoxicity is a potential adverse effect of anthracycline (A) therapy. Radiotherapy (XRT) may also cause a variety of cardiac complications. The purpose of the present study was to evaluate these cardiac side-effects in children and adolescents treated for cancer. We assessed the cardiac status of 91 patients, divided into three groups: Group A (n = 53) had anthracyclines at a mean cumulative dose of 410 mg/m2, group A+XRT (n = 26) had both chest irradiation (XRT) and A (mean 360 mg/m2), and group XRT (n = 12) had XRT alone. The patients differed from the controls in both systolic and diastolic indices of myocardial function. In echocardiography, the left ventricular (LV) contractility was abnormal in 32% in group A, in 50% in group A+XRT, and in 8% in group XRT. In radionuclide cineangiography, the LV ejection fraction was subnormal in 19% in group A, in 24% in group A+XRT, and in 1 patient in group XRT. A higher cumulative dose of A predicted decreased contractility. Treatment with A and/or XRT often leads to cardiotoxicity. Although in most cases this cardiotoxicity seems to be mild and subclinical, the long-term clinical sequelae merit further evaluation.

Adolescent↗
PubMed1996

Dynamics of the QT interval during and after exercise in healthy children.

The dynamics and homogeneity of the QT interval have been used as indicators of susceptibility to ventricular arrhythmias. We determined the relationship between QT intervals and heart rate during exercise testing and subsequent recovery in 18 healthy children. The QT intervals were measured to the apex (early QT), to the end (total QT), and from the apex to the end of the T wave (late QT) (inhomogeneity of repolarization) at heart rates from 60 by steps of 10 to 180 beats.min-1. Group mean total QT and early QT exhibited better linear correlations with heart rate (r 0.998 and 0.999) than with cardiac cycle length (r 0.954 and 0.959). The slope relating total QT to heart rate was -1.30 during exercise and -1.42 during recovery (P < 0.05). The corresponding slopes relating early QT to heart rate were -1.11 and -1.30 (P < 0.05). Late QT, as a proportion of total QT, increased at high heart rates. Rate correction using Bazett's method gave abnormal total QT values (> 440 ms) in 12 children (67%) whereas linear correction gave values below 440 ms only. In conclusion, the relationship between QT and heart rate is linear and differs during exercise and recovery. Inhomogeneity of repolarization increases at high heart rates. Linear correction of total QT and early QT intervals improves the evaluation of repolarization duration in exercise testing in children.

Adolescent↗
PubMed1996

Topography of intimal thickening in the left coronary artery of children compared with the topography of atherosclerosis.

BACKGROUND: Newborn children already have marked intimal thickenings in their coronary arteries. The magnitude of such thickenings increases with age and is associated with the coronary artery disease mortality of the grandparents. Topographies of such thickenings were investigated. METHODS: Cross-sections of the coronary arteries of 71 autopsied children were studied morphometrically at 200 microns intervals. A three-dimensional model was constructed from 16 serial sections by digitizing both the inner and the outer borders of the serial sections. A B-spline surface was constructed. RESULTS: The arterial media was thinner under large intimal thickening. In a three-dimensional model the luminal surface could be seen through the outer surface. Intimal thickening narrowed the coronary lumen. In a sagittal longitudinal cross-section along the course of the coronary artery, a hypothetical coronary "angiocardiogram' demonstrated a narrowing in the proximal coronary artery. CONCLUSIONS: Intimal thickenings that narrow the coronary artery lumen appear in the beginning of the left coronary artery in children, as does atherosclerosis in adults.

Adolescent↗
PubMed1996

Pulmonary artery pressure in term and preterm neonates.

Systolic pulmonary artery pressure (PAP) during the first 4 days after birth was determined in 41 healthy term and 46 preterm infants by measuring ductal Doppler flow velocity and systemic arterial pressure (SAP). Among preterm infants, 21 had respiratory distress syndrome (RDS) and 25 did not. Sequential indices within 96 h of age were presented respectively. At the ages of 2 and 12 h the ratio between pulmonary and systemic arterial pressure was significantly higher in term than in preterm infants without RDS (p < 0.05). At the age of 24 h, PAP to SAP ratio was similar in all study groups. Between 48 and 72 h, PAP to SAP ratio was significantly higher in preterm infants with RDS than in infants without RDS (p < 0.05). Our findings indicated that: (1) in healthy fullterm infants pulmonary artery pressure fell to subsystemic level during the first 12 h, indicating the critical time in circulatory transition; (2) prematurity did not affect ductal closure times significantly; and (3) RDS was associated with prolonged ductal patency and delayed postnatal circulatory adaptation characterized by pulmonary hypertension.

Blood Flow Velocity↗
PubMed1996

Origin of circulating group II phospholipase A2 in hepatocytes in a patient with epitheloid hemangioendothelioma of the liver.

The concentration of group II phospholipase A2 was measured in blood plasma samples before and after liver transplantation in a 27-year-old woman who suffered from a massive epitheloid hemangioendothelioma of the liver. The pretransplantation concentration of group II phospholipase A2 was 830 microg/L, which is markedly above the upper limit of the reference interval (10.8 microg/L). After the transplantation, there was a dramatic decrease in the group II phospholipase A2 level (33 microg/L on the first posttransplantation day). In situ hybridization of mRNA and immunohistochemistry revealed synthesis of group II phospholipase A2 in hepatocytes in non-neoplastic areas of the liver. Tumor cells did not contain group II phospholipase A2. The results indicate that group II phospholipase A2 circulating in blood plasma originates in hepatocytes.

Adult↗
PubMed1995

Early protein oxidation in the neonatal lung is related to development of chronic lung disease.

Free radical-mediated oxidation of proteins may impair their function and cause cellular damage. We studied pulmonary protein oxidation and its association with the development of chronic lung disease in 61 newborn infants (mean gestational age 31.1 +/- 4.0, range 24-41 weeks) requiring intensive care with oxygen therapy. Protein oxidation was quantified as protein carbonylation in tracheal aspirates recovered daily during the first week of life. Mean carbonyl concentration was 3.5 +/- 1.6 mumol/mg protein. Negative correlations existed between protein carbonylation during days 2-4 and gestational age (day 2: r = -0.37, p = 0.01; day 3: r = -0.48, p = 0.001; and day 4: r = -0.33, p = 0.03). Patients who developed bronchopulmonary dysplasia showed significantly higher protein carbonylation on days 1-6 (all p < 0.05). In multiple regression analysis explaining bronchopulmonary dysplasia, using gestational age, inspired oxygen on days 1-3 and protein carbonylation on day 3 as independent variables, only protein carbonylation remained significant. We conclude that immaturity is the most important factor explaining free radical-mediated pulmonary protein oxidation in newborn infants and that oxidation of proteins is related to the development of chronic lung disease.

Bronchopulmonary Dysplasia↗
PubMed1995

Cardiopulmonary evaluation of exercise tolerance after chest irradiation and anticancer chemotherapy in children and adolescents.

OBJECTIVE: The aim of the study was to evaluate the cardiopulmonary exercise tolerance in children and adolescents after chest irradiation and anticancer chemotherapy. METHODS: We studied 30 subjectively asymptomatic patients aged 8 to 25 years treated for pediatric malignancies with chest irradiation (XRT) +/- chemotherapy. The median interval since XRT was 7 (range, 2 to 13) years. The median XRT dose for mediastinum and/or lungs was 2550 (range, 1000 to 5100) cGy. The median cumulative dose of anthracyclines was 250 (range, 0 to 480) mg/m2. Cardiac function and exercise tolerance were evaluated by electrocardiography, echocardiography, radionuclide cineangiography, and exercise test with gas exchange analysis. RESULTS: The patients differed from normal controls in systolic indices of myocardial function. In echocardiography, the left ventricular contractility was abnormal in 14/30 patients. In radionuclide cineangiography, the left ventricular ejection fraction was subnormal in 6/30 patients, and in 9/30 patients the rise in ejection fraction during exercise was inadequate (< 5%). In exercise testing, the mean (+/- SD) maximum workload attained was 2.7 (+/- 0.7) watts/kg, and the mean (+/- SD) maximum oxygen consumption was 35.4 (+/- 9.7) mL/min/kg. Both variables were < 80% of predicted values in 11 patients. CONCLUSIONS: XRT and anticancer chemotherapy very often lead to late cardiopulmonary toxicity and impaired exercise tolerance. Although in most cases this toxicity seemed to be mild and subclinical, the long-term clinical sequels merit further evaluation.

Adolescent↗
PubMed1994

Increased incidence of bronchopulmonary dysplasia after antenatal administration of indomethacin to prevent preterm labor.

The aim of this randomized study was to compare the neonatal outcome in infants who have been exposed in utero to indomethacin with that in infants exposed to a beta-adrenergic agonist, nylidrin hydrochloride. Eighty pregnant women threatened with preterm labor between 24 and 34 weeks of gestation were enrolled in the study. An intravenous infusion of nylidrin or enterally administered indomethacin was given for a maximum of 72 hours. If preterm labor recurred, all parturient patients were treated with nylidrin. Indomethacin prolonged gestation significantly more than the beta-adrenergic agonist (6.6 weeks vs 4.5 weeks; p = 0.04). Ten of the forty-two infants exposed to indomethacin and 2 of the 45 infants exposed to nylidrin had bronchopulmonary dysplasia (24% vs 5%; p = 0.02). Among the 28 infants delivered within 120 hours after the start of treatment, the incidences of respiratory distress syndrome (82% vs 29%; p = 0.02), bronchopulmonary dysplasia (73% vs 6%; p = 0.0006), and necrotizing enterocolitis or focal intestinal perforation (27% vs 0%; p = 0.03) were higher among those exposed to indomethacin than among those exposed to nylidrin. We infer that administration of indomethacin to pregnant women threatened with premature labor is associated with an increased risk of bronchopulmonary dysplasia in their infants if delivery occurs early.

Adult↗
PubMed1994

Infection and intimal thickening: evidence from coronary arteries in children.

Post-mortem examination in children may reveal narrowing of coronary artery diameter by up to 60% due to intimal thickening. This is statistically associated with recent or intercurrent infection. Endothelial injury is known to be caused by septicaemia, for example, and endothelial injury initiates atherogenesis. Elevation of tumour necrosis factor alpha (TNF alpha) levels is a feature of both septicaemia and atheroma, and TNF alpha can damage endothelium, stimulate platelet-derived-growth-factor (PDGF) secretion and thereby promote vascular smooth muscle cell proliferation. Episodes of infection-related endothelial damage, leading to intimal thickening followed by partial regression, may start in infancy and contribute cumulatively to the development of coronary atheroma.

Child↗