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In the present work, the difference between arrival times of photoplethysmographic (PPG) pulses from two different sites of the arterial tree (PTTD) is calculated. As the PTTD is considered to be related with arterial pulse wave velocity, an evaluation of it''s usefulness to identify states of acute mental stress is performed. A subset of fourteen healthy volunteers undergoing a stress protocol was analysed and a statistical test was carried out to evaluate the validity of the proposed method. The results showed that the standard deviation of the PTTD had sufficient statistical capacity to discern between states of stress and relaxation. Furthermore, a generalised descending trend of the mean PTTD can be seen from relaxation to stress.

The Heart Rate Variability (HRV) is a noninvasive tool to evaluate the activity of the autonomic nervous system. To study the HRV, different mathematical representations can be used. The selection of a representation might have an effect on the evaluation of the mechanisms that modulate the Heart Rate (HR). One of these mechanisms is the Respiratory Sinus Arrhythmia (RSA), i.e. an increased HR during inhalation and a decreased HR during exhalation. Different methods exist to quantify the RSA. A common approach is to calculate the power in the High Frequency (HF, 0.15 - 0.4 Hz) band of the spectrum of the HRV representation. More recently proposed methods use the respiratory signals to estimate the strength of the RSA.This paper studies the effect of the HRV representations on the quantification of the RSA. To this end, an experiment is used in which the sympathetic and parasympathetic branches of the autonomic nervous system are selectively blocked. Three different HRV representations are considered. Afterwards, the strength of the RSA is estimated using three approaches, namely the spectral content in the HF band of the HRV representations, orthogonal subspace projections and a time-frequency representation.The results suggest that the selection of an HRV representation does not have a significant impact on the RSA estimates in a healthy population.

This paper proposes a methodology to extract both linear and nonlinear respiratory influences from the heart rate variability (HRV), by decomposing the HRV into a respiratory and a residual component. This methodology is based on least-squares support vector machines (LS-SVM) formulated for nonlinear function estimation. From this decomposition, a better estimation of the respiratory sinus arrhythmia (RSA) and the sympathovagal balance (SB) can be achieved. These estimates are first analyzed during autonomic blockade and an orthostatic maneuver, and then compared against the classical HRV and a model that considers only linear interactions. Results are evaluated using surrogate data analysis and they indicate that the classical HRV and the linear model underestimate the cardiorespiratory interactions. Moreover, the linear and nonlinear interactions appear to be mediated by different control mechanisms. These findings will allow to better assess the ANS and to improve the understanding of the interactions within the cardiorespiratory system.

Intrauterine Growth Restriction (IUGR) and premature birth are associated with higher risk of cardiovascular diseases throughout adulthood. The aim of this study was to evaluate the influence of these factors in ventricular electrical remodeling in preadolescents. Electrocardiography was performed in a cohort of 33-IUGR, 32-preterm with appropriate weight and 60 controls. Depolarization and repolarization processes were studied by means of the surface ECG, including loops and angles corresponding to QRS and T-waves. The angles between the dominant vector of QRS and the frontal plane XY were different among the study groups: controls [20.03°(10.11°-28.64°)], preterm [25.48°(19.79°-33.56°)], and IUGR [27.77°(16.59°-33.23°)]. When compared to controls, IUGR subjects also presented wider angles between the difference of QRS and T-wave dominant vectors and the XY-plane [5.28°±12.15° vs 0.49°±14.15°, p

Radical action against social disadvantage is highly consequential but has been far less studied than moderate collective action. But who supports such extreme actions and why? In two studies, we examine the relation between group identification and suppo

El término " condicionalmente esencial " (o semiesencial), aplicado inicialmente a los aminoácidos, se utiliza de forma generalizada para otros nutrientes. Un nutriente condicionalmente esencial es un compuesto producido usualmente en cantidades adecuadas por síntesis endógena pero que se requiere de forma exógena bajo determinadas circunstancias. Así, la arginina, la glutamina, la cisteína, la glicina, la prolina y la tirosina son aminoácidos semiesenciales. Entre los derivados de aminoácidos, la carnitina, la colina, y las poliaminas tienen también el carácter de compuestos condicionalmente esenciales. Asimismo, los nucleótidos de la dieta se consideran compuestos semiesenciales debido a que algunos tejidos de rápido crecimiento como el intestino, la médula ósea y los linfocitos utilizan preferentemente bases púricas y pirimidínicas preformadas para la síntesis de ácidos nucleicos. Esta revisión se dedica al estudio de nutrientes condicionalmente esenciales de naturaleza nitrogenada y con interés en nutrición hospitalaria. Entre ellos destacan la arginina, implicada en las funciones endotelial, inmunitaria, gastrointestinal y renal, la reproducción, el desarrollo neonatal, la curación de heridas y la tumorigénesis; la glutamina, necesaria para el mantenimiento de la integridad intestinal y con efectos beneficiosos en estados catabólicos como la sepsis, la infección, el trauma y el cáncer; y los nucleótidos, involucrados en el crecimiento y la diferenciación celular, y con efectos sobre el metabolismo lipídico, la microbiota intestinal y el sistema inmunitario. The term "conditionally essential" (or semi-essential), initially applied to amino acids, has been generalized to other nutrients. A conditionally essential nutrient is a compound usually produced in adequate amounts by endogenous synthesis but that is exogenously required under certain circumstances. Thus, arginine, glutamine, cysteine, glycine, carnitine, choline, and polyamines are conditionally essential compounds. In addition, dietary nucleotides are considered semi-essential since some rapidly growing tissues such as the gut, bone marrow, and lymphocytes, preferentially use preformed purine and pyrimidine bases for nucleic acid synthesis. This review discusses the study of conditionally essential nitrogenous nutrients of interest in clinical nutrition. Among them we highlight arginine, involved in endothelial, immune, gastrointestinal, and renal functions, in reproduction, neonatal development, wound healing, and tumorigenesis; glutamine, necessary for maintaining bowel integrity, and with beneficial effects on catabolic states such as sepsis, infection, trauma, and cancer; and nucleotides, implicated in cell growth and differentiation, and with various effects on lipid metabolism, intestinal microbiota, and immune system.

El término " condicionalmente esencial " (o semiesencial), aplicado inicialmente a los aminoácidos, se utiliza de forma generalizada para otros nutrientes. Un nutriente condicionalmente esencial es un compuesto producido usualmente en cantidades adecuadas por síntesis endógena pero que se requiere de forma exógena bajo determinadas circunstancias. Así, la arginina, la glutamina, la cisteína, la glicina, la prolina y la tirosina son aminoácidos semiesenciales. Entre los derivados de aminoácidos, la carnitina, la colina, y las poliaminas tienen también el carácter de compuestos condicionalmente esenciales. Asimismo, los nucleótidos de la dieta se consideran compuestos semiesenciales debido a que algunos tejidos de rápido crecimiento como el intestino, la médula ósea y los linfocitos utilizan preferentemente bases púricas y pirimidínicas preformadas para la síntesis de ácidos nucleicos. Esta revisión se dedica al estudio de nutrientes condicionalmente esenciales de naturaleza nitrogenada y con interés en nutrición hospitalaria. Entre ellos destacan la arginina, implicada en las funciones endotelial, inmunitaria, gastrointestinal y renal, la reproducción, el desarrollo neonatal, la curación de heridas y la tumorigénesis; la glutamina, necesaria para el mantenimiento de la integridad intestinal y con efectos beneficiosos en estados catabólicos como la sepsis, la infección, el trauma y el cáncer; y los nucleótidos, involucrados en el crecimiento y la diferenciación celular, y con efectos sobre el metabolismo lipídico, la microbiota intestinal y el sistema inmunitario.

Obstructive sleep apnoea (OSA) causes, among other things, intermittent blood oxygen desaturations, increasing the sympathetic tone. Yet the effect of desaturations on heart rate variability (HRV), a simple and noninvasive method for assessing sympathovagal balance, has not been comprehensively studied. We aimed to study whether desaturation severity affects the immediate HRV.MethodsWe retrospectively analysed the electrocardiography signals in 5-min segments (n=39 132) recorded during clinical polysomnographies of 642 patients with suspected OSA. HRV parameters were calculated for each segment. The segments were pooled into severity groups based on the desaturation severity (i.e.the integrated area under the blood oxygen saturation curve) and the respiratory event rate within the segment. Covariate-adjusted regression analyses were performed to investigate possible confounding effects.ResultsWith increasing respiratory event rate, the normalised high-frequency band power (HFNU) decreased from 0.517 to 0.364 (p