Ljiljana Bjelakovic

Artificial neural networks based prediction of cerebral palsy in infants with central coordination disturbance.

BACKGROUND In a previous study we demonstrated that heart variability parameters (HRV) could be helpful clinically as well as a prognostic tool in infants with central coordination disturbance (CCD). In recent years, outcome predictions using artificial neural networks (ANN) have been developed in many areas of health care research, but there are no published studies considered ANN models for prediction of cerebral palsy (CP) development. OBJECTIVE To compare the results of an ANN analysis with results of regression analysis, using the same data set and the same clinical and HRV parameters. METHODS The study included 35 infants with CCD and 37 healthy age and sex-matched controls. Time-domain HRV indices were analyzed from 24h electrocardiography recordings. Clinical parameters and selected time domain HRV parameters are used to predict CP by logistic regression, and then an ANN analysis was applied to the same data set. Input variables were age, gender, postural responses, heart rate parameters (minimum, maximum and average), and time domain parameters of HRV (SDNN, SDANN and RMSSD). For each of one the pairs of ANN and clinical predictors, the area under the receiver operating characteristic (ROC) curves with test accuracy parameters were calculated and compared. RESULTS In the observed dataset, ANN model overall correctly classified all infants, compared with 86.11% correct classification for the logistic regression model, and compared with 67.65% and 77.14% for SDANN and SDNN respectively. CONCLUSIONS ANN model, based on clinical and HRV data can predict development of CP in patients with CCD with accuracy greater than 90%. Our results strongly indicate that a well-validated ANN may have a role in the clinical prediction of CP in infants with CCD.

Heart rate variability in infants with central coordination disturbance.

Despite a remarkable medical progress in the field of Developmental Medicine and Child Neurology, early identification of infants at risk for permanent motor disabilities still presents challenge for both clinicians and researchers. As an indicator of cardiac autonomic control, it was shown that heart rate variability (HRV) might reflect not only sympathetic or parasympathetic activity but also functional integrity of the central nervous system (CNS). Furthermore a pattern of HRV was demonstrated to correlate with motor developmental outcome in high risk infants. The purpose of this study was to analyze the clinical usefulness as well as predictive value of time-domain HRV parameters in infants with central coordination disturbance. The study included 35 infants with central coordination disturbance and 37 healthy age and sex-matched controls. Time-domain HRV indices were analyzed from 24-h electrocardiography recordings. We found significantly lower values of SDNN, SDANN and RMSSD parameters in infants with central coordination disturbance compared to controls. Additionally, logistic regression analyses demonstrated independent predictive value of parameters SDNN and SDANN in infants who subsequently developed cerebral palsy (CP). By performing receiver operating characteristic (ROC) analyses, the optimal cut-off value of SDNN<=48ms predicted CP with a sensitivity of 68.7% (95% CI 41.4-88.9) and specificity of 84.2% (95 CI 60.4-96.4) while the optimal cut-off value of SDANN<=41ms predicted CP with a sensitivity of 87.5% (95% CI 61.6-98.1) and specificity of 57.9% (95 CI 33.5-79.7). We are in opinion that time domain HRV analysis could be helpful clinically as well as a prognostic tool in infants with central coordination disturbance.

Heart Rate Variability in Children with Exercise-Induced Idiopathic Ventricular Arrhythmias

Ventricular arrhythmias (VAs) are common pediatric rhythm disorders requiring comprehensive laboratory evaluation. Although usually idiopathic, implying a benign character and favorable prognosis, the initial clinical approach is still not established in all cases. Considering their prognostic significance, exercise-induced (precipitated or aggravated) VAs usually require additional diagnostics, treatment, and follow-up. A number of reports have presented experimental and clinical evidence that increased sympathetic activity can initiate, or at least facilitate, VAs. Recent data highlight the relationship between exercise-induced idiopathic VAs (IVAs) and the long-term risk of cardiovascular death. The aim of this study was to assess the utility of heart rate variability (HRV) analysis as a noninvasive method for estimating autonomic nervous activity in children with exercise-induced IVAs. The study included 42 children with IVAs, who were divided into two groups: children with exercise-induced (precipitated or aggravated) IVAs and children with exercised-suppressed IVAs. Time-domain HRV parameters were analyzed from 24-h ambulatory electrocardiography recordings, and the majority of children underwent an exercise stress test using the McMaster protocol. The results of this study showed no significant changes in parasympathetic index, i.e., the square root of the mean of the sum of the squares of the differences between adjacent NN intervals (the length between two successive heartbeats) between the groups examined. On the other hand, we observed diminished time-domain values for the standard deviation of all adjacent NN intervals, as well as diminished time-domain values for standard deviation of the averages of NN intervals in all 5-min segments in the group of children with exercise-induced IVAs, implicating increased sympathetic activity in such individuals. HRV analysis could be a helpful diagnostic method, giving useful information regarding cardiac autonomic control in some children with exercise-induced IVAs.

Heart rate variability in children with idiopathic ventricular tachycardia

Idiopathic ventricular tachycardia (IVT) is a rare arrhythmia in children. A great deal of uncertainty and numerous questions still remain regarding the extent of investigation, therapy, and long-term prognosis for children with IVT. The existence of subclinical cardiac disease, as well as of autonomic dysfunction in patients with ventricular arrhythmias, has been well documented. A number of experimental and clinical studies have suggested that imbalances within the cardiac autonomic system’s activity may be crucial in the generation of ventricular tachycardia, irrespective of the presence of cardiovascular pathological substrate. Heart rate variability (HRV) analysis provides a useful method for measuring the autonomic activity. This study evaluates HRV in children with IVT. The study included 31 children with ventricular arrhythmia who were divided into two groups: (1) patients with frequent ventricular extrasystoles (VES) and (2) patients with IVT. The control group comprised 23 healthy children without pathological findings on 24-h ECG Holter. Twenty-four-hour ambulatory electrocardiography recordings were obtained, and the time-domain variables were calculated. HRV was compared to age-related normal values. It was observed that the overall heart rate variability is diminished in children with IVT. We recommend HRV analysis of any child with IVT. Quantification of the autonomic nervous system activity using time domain analyses may be a helpful diagnostic tool in the clinical assessment and initial evaluation of these children.

Is folic acid supplementation to food benefit or risk for human health

Abstract The need for sufficient quantities of folic acid for normal embryogenesis and fetal development is well known. Women of childbearing age must be sure to have an adequate intake of folic acid periconceptionally prior to and during pregnancy. Folate plays an essential role in the biosynthesis of RNA and DNA, phospholipid and neurostransmitters synthesis, using S-adenosylmethionine (SAM) as the primary methyl group donor. In some countries, the knowledge that folic acid is preventable for the reduction of the risk for neural tube defects (NTD) and in lowering the high amount of homocysteine (Hcy) led to the recommendation that all women capable of becoming pregnant should consume 400 µg of folic acid daily. Later, in 1998, folic acid fortification of all enriched cereal grain product flour was implemented in some countries. In addition to careful monitoring of adverse effects, the studies are warranted in order to determine the potentially positive and deleterious effects of folic acid fortification and supplementation on the human health or human diseases. To further understand the metabolic action of folates we asked ourselves the question: Is the intake of a sufficient amount of this vitamin a benefit or risk for human health?

Heart rate recovery time in metabolically healthy and metabolically unhealthy obese children

ABSTRACT Background: Autonomic dysfunction is an emerging non-traditional cardiovascular risk factor that correlates with obesity, components of metabolic syndrome, as well as cardiorespiratory fitness. As a simple and validated index of autonomic balance, heart rate recovery (HRR) has been reported as a useful biomarker for predicting cardiovascular morbidity and mortality. Objectives: The aim of this study was to compare HRR in metabolically healthy vs. metabolically unhealthy obese children. Methods: A total of 56 obese children of whom 31 had metabolic syndrome were examined. All the participants underwent the multistage submaximal cycle ergometer test and HRR was determined one minute after the test. Results: The HRR was significantly lower (18.9 ± 3.7) in a group of metabolically unhealthy obese children compared to metabolically healthy obese children (24 ± 4.1) p < 0.001. Logistic regression analysis showed that reduction in HRR was also influenced by higher BMI. Conclusion: Our findings implicate the presence of the autonomic dysfunction as reflected by impaired heart rate recovery (HRR) in obese children with metabolic syndrome.

ANTIOXIDANTS AND THEIR IMPORTANCE DURING MUSCULAR EXERCISE: A REVIEW

Physiological levels of reactive oxygen species, as an essential part of the homeostatic milieu, are required for normal functioning of skeletal muscle. High levels of reactive oxygen species promote contractile dysfunction resulting in muscle weakness and fatigue, oxidative stress, apoptosis and necrosis of muscle cells. It is known that both resting and contracting skeletal muscles produce reactive oxygen species and reactive nitrogen species. The first suggestion that physical exercise results in free radical-mediated damage to tissues appeared in 1978. The newest researches investigate the mechanisms by which oxidants influence skeletal muscle contractile properties and explore how to protect muscle from oxidant-mediated dysfunction. Principal antioxidant enzymes include superoxide dismutase, glutathione peroxidase, and catalase. Numerous non-enzymatic antioxidants exist in cells within skeletal muscle fibers, the most abundant of which include glutathione, bilirubin, α-Lipoic acid , uric acid, and ubiquinones, or coenzyme Q (CoQ) andflavonoids. Dietary antioxidants are vitamins C- L ascorbic acid , vitamin A, retinol and their provitamins, carotenoids (especially β-carotene), vitamins E, tocopherol (especially a-tocoferol ), folic acid or folates. The usage of endogenous enzymatic and non-enzymatic antioxidants protects muscle from strong damaging effects caused by free radicals during acute exercise or longer term physical exercise. Scientific researches now confirm that the long-term use of antioxidants is safe and effective. The actual recommendation for physically active individuals is to ingest a diet rich in antioxidants.

Echocardiographic evaluation of left ventricular outflow tract hemodynamics in healthy children with anomalous left ventricular band.

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