Platelet reactivity plays a role in the inflammatory process that favours graft vasculopathy and both Clopidogrel and Everolimus reduce platelet reactivity and graft vasculopathy in animal models. Our objective is to evaluate if, in heart transplant (HT) patients treated with clopidogrel, the use of Everolimus is associated with less platelet reactivity compared with treatment with Tacrolimus. We included 39 heart transplant patients treated with clopidogrel 75 mg, once daily. We compared platelet reactivity, using the vasodilator-stimulated phosphoprotein-P2Y12 Reactivity index (PRI), between 2 groups according to immunosuppressive treatment: 1) 20 patients with Everolimus and mycophenolate mofetil, 2) 19 patients with Tacrolimus and mycophenolate mofetil. We also compared them with 10 control patients treated with Clopidogrel but no immunosuppression. Data are expressed as least squares mean +/- standard error of mean (LSM±SEM) and analysis is performed using the general linear model. HT patients had a median of 67 years old and were a median of 8.8 years after HT. 74% males, 27% previous ischemic heart disease, 15% diabetics and 18% with graft vasculopathy. The median left ventricular ejection fraction was 62%. Median trough levels of the Everolimus group were 4.1 ng/mL and median trough levels of the tacrolimus group were 5.8 ng/mL. The PRI in the Everolimus group was 45.5±4.3%, in the Tacrolimus group of 40.4±4.8% and in the control group of 35.6±5.8%. There were no significant differences (see figure 1). PRI in patients with HT treated with Clopidogrel was not significantly different between patients treated with Everolimus and Tacrolimus. Patients with HT had a tendency to higher PRI compared to controls. The role of treatment with Clopidogrel in HT patients to prevent graft vasculopathy is still unclear.

According to the World wide Organization of the Health, the number of people infected with the Tri-panosoma Cruzi is considered between 16 and 18 million, causal agent of the Chagaspsila disease, and in 100 million the people exposed to the affectation risk. When concluding in 1983 a study longitudinal epidemiologist in patients with the disease evaluated every 3 years, the cardiac affectation: chronic Chagasic myocarditis (MCHC) increased from a 17% at the beginning of the study to a 49, 4% after 15 years. Previous studies of the variability of cardiac frequency in patients with the Chagaspsila disease, show alterations in the spectral indices of the HRV. We analyze the 24-hour heart rate by Holter recordings in 62 patients with ECG alterations (CH2), 32 patients without ECG alterations (CH1) who had positive serological findings for disease of Chagaspsila and 36 healthy subjects (control) matched for sex and age. We find a orthogonal base that is able to discriminate the groups from circadian profiles, control and CH2, and stratify the groups CH1.

An evolutionary distance is introduced in order to propose an efficient and feasible procedure for phylogeny studies. Our analysis are based on the strand asymmetry property of mitochondrial DNA, but can be applied to other genomes. Comparison of our results with those reported in conventional phylogenetic trees, gives confidence about our approximation. Our findings support the hypotheses about the origin of the skew and its dependence upon evolutionary pressures, and improves previous efforts on using the strand asymmetry property of genomes for phylogeny inference. For the evolutionary distance introduced here, we observe that the more adequate technique for tree reconstructions correspond to an average link method which employs a sequential clustering algorithm.

INTRODUCTION AND OBJECTIVES:Impairment of the autonomous nervous system in early stages of Chagas' disease is still a matter of debate, although multiple approaches (including heart rate response to orthostatism and the Valsalva maneuver, and spontaneous variability) have been used to ascertain its occurrence. The circadian profile of heart rate and its variability have not been investigated in patients with Chagas' disease.PATIENTS AND METHOD:We analyzed the 24-hour heart rate by Holter recordings in 63 patients with and without ECG alterations, who had positive serological findings for Chagas' disease. These results were compared with those in 22 healthy subjects matched for sex and age. Mean 24-hour heart rate and its circadian amplitude were analyzed with Cusum analysis and nocturnal dip. In a subgroup of 45 subjects (30 with Chagas' disease and 15 healthy controls), heart rate instantaneous variability (24-hour pNN50 and r-MSSD) and circadian amplitude were also calculated by Cusum analysis.RESULTS:24-hour and diurnal heart rates were lower in patients with Chagas' disease than in healthy subjects (P<.05). Circadian amplitude and dip were lower in patients, but these differences did not reach statistical significance. In the subgroup of 45 subjects, the reductions in instantaneous heart rate variability (pNN50 and r-MSSD) in Chagasic patients were small, and circadian amplitudes were preserved, when compared with healthy subjects.CONCLUSIONS:The lower heart rate in patients with Chagas' disease occurred only during diurnal activity, and instantaneous heart rate variability was preserved. These findings suggest an alteration in the sympathetic branch of the autonomous nervous system. The circadian heart rate profile, which has not been studied previously in patients with Chagas' disease, does not seem appreciably blunted in this stage of the disease.

El compromiso autonómico en las etapas iniciales de la enfermedad de Chagas es objeto de controversia, a pesar de haberse utilizado múltiples técnicas para su análisis: la frecuencia cardíaca durante el ortostatismo, la maniobra de Valsalva o la variabilidad espontánea de la frecuencia cardíaca. El perfil circadiano de la frecuencia cardíaca no ha sido estudiado a este respecto. Analizamos la frecuencia cardíaca en 24 h mediante registro Holter en 63 pacientes con serología positiva para enfermedad de Chagas, con y sin lesiones electrocardiográficas. Los resultados se compararon con los obtenidos en un grupo de 22 sujetos sanos, de edad y sexo equivalentes. Se analizó el promedio de frecuencia cardíaca de 24 h y su perfil circadiano utilizando el análisis de Cusum y la caída nocturna o «dip». En un subgrupo de 45 sujetos (30 chagásicos y 15 sanos) se calculó la variabilidad instantánea de la frecuencia cardíaca (pNN50 y r-MSSD) y la amplitud circadiana de esos parámetros utilizando el análisis de Cusum. La frecuencia cardíaca de 24 h y diurna fueron menores en los chagásicos que en los controles (p < 0,05). Los valores de «dip» y amplitud circadiana fueron menores en los chagásicos, pero no alcanzaron diferencias significativas. En el subgrupo de 45 sujetos se encontraron, en los pacientes chagásicos, escasas alteraciones de la variabilidad instantánea de la frecuencia cardíaca (pNN50 y r-MSSD), con preservación de sus amplitudes circadianas cuando se compararon con las de los sujetos sanos. La menor frecuencia cardíaca de los pacientes chagásicos durante la actividad, con preservación de su variabilidad instantánea, sugiere una alteración de la división simpática. El perfil circadiano de la frecuencia cardíaca de estos sujetos chagásicos, que no fue estudiado previamente, no muestra una clara atenuación en esta fase de la enfermedad. Impairment of the autonomous nervous system in early stages of Chagas' disease is still a matter of debate, although multiple approaches (including heart rate response to orthostatism and the Valsalva maneuver, and spontaneous variability) have been used to ascertain its occurrence. The circadian profile of heart rate and its variability have not been investigated in patients with Chagas' disease. We analyzed the 24-hour heart rate by Holter recordings in 63 patients with and without ECG alterations, who had positive serological findings for Chagas' disease. These results were compared with those in 22 healthy subjects matched for sex and age. Mean 24-hour heart rate and its circadian amplitude were analyzed with Cusum analysis and nocturnal dip. In a subgroup of 45 subjects (30 with Chagas' disease and 15 healthy controls), heart rate instantaneous variability (24-hour pNN50 and r-MSSD) and circadian amplitude were also calculated by Cusum analysis. 24-hour and diurnal heart rates were lower in patients with Chagas' disease than in healthy subjects (P<.05). Circadian amplitude and dip were lower in patients, but these differences did not reach statistical significance. In the subgroup of 45 subjects, the reductions in instantaneous heart rate variability (pNN50 and r-MSSD) in Chagasic patients were small, and circadian amplitudes were preserved, when compared with healthy subjects. The lower heart rate in patients with Chagas' disease occurred only during diurnal activity, and instantaneous heart rate variability was preserved. These findings suggest an alteration in the sympathetic branch of the autonomous nervous system. The circadian heart rate profile, which has not been studied previously in patients with Chagas' disease, does not seem appreciably blunted in this stage of the disease.

Networks of chaotic coupled maps are considered as string and language generators. It is shown that such networks can be used as encrypting systems where the cipher text contains information about the evolution of the network and also about the way to select the plain text symbols from the string associated with the network evolution. The secret key provides the network parameters, such as the coupling strengths.

INTRODUCTION AND OBJECTIVES:The application of nonlinear techniques allows the definition of early risk markers in patients with Chagas infection and without any evidence of cardiac involvement evaluated by standard diagnostic test. Nonlinear modeling techniques have proved to be effective in cardiac rhythm analysis, thereby justifying its use in Chagas' disease.PATIENTS AND METHOD:The routine noninvasive test and heart rate variability analysis were performed in Chagas' disease patients and in a group of healthy subjects. In a second phase we used nonlinear analysis in the evaluation of patients with Chagas infection and no evidence of heart disease, Chagasic patients with minimal electrocardiographic abnormalities and healthy controls.RESULTS:Twenty-four-hour electrocardiographic ambulatory monitoring and heart rate variability allowed us to establish differences between the healthy subjects and patients with Chagas infection without evidence of cardiac disease (p c 0.05 and p <0.005). In sharp contrast nonlinear analysis characterized 4 subgroups in Chagasic patients without cardiac involvement (sensitivity and specificity of 1 00%).CONCLUSIONS:Our findings suggest that nonlinear modeling techniques have a high sensitivity and specificity in the early detection of cardiac involvement and very early autonomic disturbance. We recommend that these techniques be applied to patients with high risk of cardiac disease other than Chagasic myocarditis. Our findings should be corroborated with studies in larger populations. We are currently developing a prospective study to this end.

Using a simple computational procedure, we examine DNA chains from different species in order to prove their nonlinear deterministic structures. This procedure applies a nonlinear modeling technique based upon quantitative comparison of the neighborhoods from similar DNA subsegments of size d. Our results reveal that noncoding regions exhibit a deterministic signature at sizes larger than a characteristic dimension d(c). Applications to evolutionary categories and recognition of different DNA regions are discussed.

We describe a computational procedure to encrypt a message, provided that the transmitter and the receiver dispose of identical, but otherwise not synchronized, chaotic dynamical systems. The technique is based upon the fact that the symbolic dynamics of these two systems can be used in order to sequentially construct data blocks which reproduce those from the input file.

A technique to discriminate complex signals associated with deterministic chaos from those of random origin is presented. The method applies a new, computationally efficient, prediction procedure based on the associative memory concept. This procedure was used as a method to model non-linear series. Its performance was analyzed for several time series, including simulated numerical data from the logistic map and from the Mackey-Glass delay equation. Also experimental data from a dripping faucet in a chaotic regime and from low-temperature thermal fluctuations of the voltage across a resistor are considered.