Dr-MUSIC: An Effective Device for Investigating Multisensory Mechanisms during Development with EEG recordings.

From birth, we are continuously exposed to multisensory stimuli that we learn to select and integrate during development to perceive a coherent world. To date, there are no optimal solutions to investigate how auditory, visual and tactile signals are integrated during EEG recording in infants and children. The present work aims to introduce Dr-MUSIC, a novel multisensory device with EEG-compatible timing and an attractive design for children. It is composed of audio, visual, and tactile stimulators arranged in the form of a couple of chubby dragons that can simultaneously provide selectable uni-, bi-, or tri-modal information. We first validated the system's EEG compatibility in 8 adults by implementing an audio-tactile oddball task during a high-density EEG recording. Then, we replicated the same task in a couple of toddlers to validate the device's usability for young children. The results suggest that the system can be effectively used for setting new experimental protocols to understand the neural basis of multisensory integration in the first years of life.Clinical Relevance- The amusing design and the possibility of changing the stimulation's characteristics (i.e., light, sound, and vibrotactile features) make it attractive in children with and without sensory impairments. Therefore, Dr-MUSIC could be used to investigate multisensory development and related neural correlates in typical and atypical children to design new early rehabilitation protocols.

Fractal signatures of the COVID-19 spread.

Recent quantitative approaches for studying several aspects of urban life and infrastructure have shown that scale properties allow the understanding of many features of urban infrastructure and of human activity in cities. In this paper, we show that COVID-19 virus contamination follows a similar pattern in different regions of the world. The superlinear power-law behavior for the number of contamination cases as a function of the city population, with exponent ß of the order of 1.15 is always obtained. Due to the strong indication that scaling is a determinant feature of covid-19 spread, we propose an epidemiological model that embodies a fractal structure, allowing a more detailed description of the observed data about the virus spread in different countries and regions. The hypothesis that fractal structures can be formed in cities as well as in larger networks is tested, indicating that indeed self-similarity may be found in networks connecting several cities.

Protective effect of quercetin against in vitro erythrocyte rheology alterations produced by arsenic.

Humans are exposed to heavy metals such as arsenic (As), through contaminated food and drinking water. The effect of As on RBC membrane is one of the most important biological effects. In a previous work, we have studied the AsVin vitro effect on erythrocytes biophysical properties discovering alterations regarding aggregability deformability, cell morphology, membrane fluidity and osmotic response. We have also observed that the presence of the metal produces an oxidative stress in RBCs that might be the origin of rheological impairment. In the present work we analyzed RBCs rheological properties associated with membrane fluidity and lipid peroxidation in presence of As and quercetin (Qc). From our results we can conclude that RBCs treatment with Qc is efficient to prevent the impairment of the mechanical properties of the cell membrane produced by the As, through oxygen reactive agents in the membrane structure, mainly on the lipids. This protective effect is observed in the preservation of the erythrocytes rheological properties and consequently in the maintenance of an appropriate blood flow, specially in the small vessels in the peripheral circulation.

Arsenic intoxication, a hemorheologic view.

Arsenic (As) is a toxic semi-metal of wide distribution in nature. People living in regions where drinking water contains large quantities of arsenic, have an unusually high likelihood of developing blood-vessel diseases, but little is known about the mechanisms involved, i.e. the blood rheologic alterations that would contribute to the circulatory obstruction. Erythrocytes are the main target cells for arsenic compounds systemically absorbed and their cell membrane is the first place against the toxic. In this paper we have examined the in vitro effect of arsenic (As(V)) on the rheologic properties of human erythrocytes in relation with membrane fluidity and internal microviscosity. According to our present results, As(V) treatment produces oxidative degradation of membrane lipids and alteration of internal microviscosity. These red blood cells (RBCs) membrane and cytoplasmic structural damage consequently alters RBCs rheologic properties: an alteration of the RBCs discoid shape to stomatocytes, a diminution of erythrocyte deformability and an enhancement of osmotic fragility and cell aggregability. These effects impaired blood fluid behaviour that contribute to obstruct peripheral circulation and provides anemia, both clinic evidences typical of arsenic cronic intoxication.

In vitro effect of aluminium upon erythrocyte membrane properties.

The link between aluminium (Al(III)) and a range of disorders in organisms (plants and animals including human beings) has been stated in diverse studies. As regards as human beings in particular, there are numerous studies on this metal's toxicity in relation to pathological processes. Only few references to the metal's effect upon cell rheological properties can be found. In this study, we present evidence for alterations in the rheological properties of cells as consequence of the Al(III)'s interaction with human red blood cell membrane. Al(III) could damage membrane functions of the red blood cell by favouring lipid peroxidation reactions due to the presence of Fe(II) as an initiator. The metal's effect on lipid bilayer, and probably on the cytoskeleton as well, would constitute the cause for the impaired erythrocyte rheology.

Study of intrinsic flow properties at the normal pregnancy second trimester.

During normal pregnancy the cardiovascular system undergoes extensive changes. In a previous work we demonstrated the role of the haemorheological profile as predictor of hypertensive gestational disorders through a retrospective study. In an attempt to clarify the rheological characteristics during normal gestation, blood and plasma viscosity, erythrocyte deformability and aggregation, and plasma fibrinogen levels were measured at second trimester of pregnancy. The interrelationships of different haemorheologic parameters, were analysed by Pearson correlation coefficient. The results showed decreased erythrocyte deformability, and increased plasma viscosity and erythrocyte aggregation due to increased fibrinogen in pregnant women. Despite these modifications blood viscosity did not increase, but there was a decrease in relative blood viscosity, therefore, a profile in accordance, from the haemorheological point of view, with the classical concept stating that haemodilution is of the utmost importance to maintain an adequate microcirculation in the uteroplacental unit during normal gestation.

Proposal of a haemorheological profile for early detection of hypertensive gestational disorders.

The objective of this study was to emphasise the potential power of simple and inexpensive haemorheological tests as predictors of hypertensive gestational disorders through a retrospective study. Blood samples of 195 primigravids with gestational age 18-23 weeks were studied. For data processing pregnant women were allocated into 3 groups, based on difference of SBP and DBP values measured at first and last consultation, and presence of proteinuria and oedema: Normotensive pregnants (n=149), hypertensive pregnants; n=26 and preeclamptic pregnants; n=20. Whole blood viscosity, plasma viscosity, erythrocyte rigidity and aggregability, haemoglobin, hematocrit, total protein, albumin and fibrinogen were assayed. Increased relative viscosity (eta(r)) (p<0.01), decreased erythrocyte deformability (p<0.05), lower O(2) release (p<0.01) and birth weight (p<0.01), showed a negative correlation with filterability index in preeclamptics. There was a decrease of erythrocyte deformability in hypertensive women. Erythrocyte deformability and blood viscosity could be an early indicator in preeclamptics, and erythrocyte deformability in hypertensive ones, therefore they could be considered alert factors in order to decide a thorough control in these patients to prevent further complications.

Test-retest reliability of the dot test of visuospatial working memory in patients with schizophrenia and controls.

To determine the test-retest reliability of the Dot Test of Visuospatial Working Memory, this task was administered to 29 patients with schizophrenia and 19 normal controls on two consecutive days. The test involved "copying" trials followed by "delay" recall trials. For "copying" trials, subjects saw a dot and then drew it on a blank sheet of paper. For "delay" trials, subjects drew the dot following a 10-, 20-, or 30-s delay. The distance between the stimulus and the drawn dot was measured for each trial. The composite score, termed "working memory deficit," is calculated by subtracting the average of the copying trials from the average of the delay trials. Pearson correlations revealed that overall performance in each group was comparable for days 1 and 2. Intra-class correlations of "working memory deficit" on days 1 and 2 were moderate in patients and controls, suggesting that task performance for each subject was similar on the testing days. Test-retest reliability tended to be higher for 10-s delay performance in patients and controls than for longer delay periods. Further analyses suggested that there was no significant learning effect on the task from day 1 to day 2 for either group on any measure. The Dot Test of Visuospatial Working Memory, especially the composite score, has moderate test-retest reliability and is a valuable tool that can be used to assess working memory functions in studies using a repeated-measures design.

Kinetic model for erythrocyte aggregation.

It is well known that light transmission through blood is the most widely utilized method for the study of erythrocyte aggregation. The curves obtained had been considered empirically as exponential functions. In consequence, the process becomes characterized by an only parameter that varies with all the process factors without discrimination. In the present paper a mathematical model for RBC aggregation process is deduced in accordance with von Smoluchowski's theory about the kinetics of colloidal particles agglomeration. The equation fitted the experimental pattern of the RBC suspension optical transmittance closely and contained two parameters that estimate the most important characteristics of the aggregation process separately, i.e., (1) average size of rouleaux at equilibrium and (2) aggregation rate. The evaluation of the method was assessed by some factors affecting erythrocyte aggregation, such as temperature, plasma dilutions, Dextran 500, Dextran 70 and PVP 360, at different media concentrations, cellular membrane alteration by the alkylating agent TCEA, and decrease of medium osmolarity. Results were interpreted considering the process characteristics estimated by the parameters, and there were also compared with similar studies carried out by other authors with other methods. This analysis allowed us to conclude that the equation proposed is reliable and useful to study erythrocyte aggregation.

Red blood cell shape as a function of medium's ionic strength and pH.

Glycocalyx, the characteristic first line of interaction between membrane and environment, can be visualized as a polyelectrolyte anchored to a bending-resistant matrix. This structure has an amazing resemblance with the ionized monolayers, in which, the cohesion among hydrocarbon chains is counteracted by the repulsion among similarly charged ionic heads, and thus the balance determines the curvature of the membrane. Likewise, it could be assumed that in biological membranes, repulsion among similarly charged groups in the glycocalyx could generate different curving trends. Hence, the factors directly influencing the electrostatic interaction among surface charged groups were studied, assessing the effect of the medium's ionic strength (mu) and pH, in an extensive range of values around the physiological one. The results point out mu variations inducing different shapes, depending on whether mu values were lower or higher than the physiological ones; which could be explained by the polyelectrolyte theory. The occurrence of more invaginated shapes as the medium's pH decreases, and the opposite event, when the pH increases, could be attributed to the coupling between the dissociation of the glycocalyx ionic groups and the H+ concentration. The behavior of the cells with reduced surface charges (by neuraminidase degradation) supports the hypothesis that the observed mu and the pH effect on erythrocyte shape could be mediated by glycocalyx charged groups.