Carlos Julio Tierra-Criollo

Biochemical analysis of human breast tissues using Fourier-transform Raman spectroscopy

We employ Fourier-transform Raman spectroscopy to study normal and tumoral human breast tissues, including several subtypes of cancers. We analyzed 194 Raman spectra from breast tissues that were separated into 9 groups according to their corresponding histopathological diagnosis. The assignment of the relevant Raman bands enabled us to connect the several kinds of breast tissues (normal and pathological) to their corresponding biochemical moieties alterations and distinguish among 7 groups: normal breast, fibrocystic condition, duct carcinoma in situ, duct carcinoma in situ with necrosis, infiltrating duct carcinoma not otherwise specified, colloid infiltrating duct carcinoma, and invasive lobular carcinomas. We were able to establish the biochemical basis for each spectrum, relating the observed peaks to specific biomolecules that play a special role in the carcinogenesis process. This work is very useful for the premature optical diagnosis of a broad range of breast pathologies. We noticed that we were not able to differentiate inflammatory and medullary duct carcinomas from infiltrating duct carcinoma not otherwise specified.

Objective response detection in an electroencephalogram during somatosensory stimulation.

AbstractTechniques for objective response detection aim to identify the presence of evoked potentials based purely on statistical principles. They have been shown to be potentially more sensitive than the conventional approach of subjective evaluation by experienced clinicians and could be of great clinical use. Three such techniques to detect changes in an electroencephalogram (EEG) synchronous with the stimuli, namely, magnitude-squared coherence (MSC), the phase-synchrony measure (PSM) and the spectral F test (SFT) were applied to EEG signals of 12 normal subjects under conventional somatosensory pulse stimulation to the tibial nerve. The SFT, which uses only the power spectrum, showed the poorest performance, while the PSM, based only on the phase spectrum, gave results almost as good as those of the MSC, which uses both phase and power spectra. With the latter two techniques, stimulus responses were evident in the frequency range of 20–80 Hz in all subjects after 200 stimuli (5 Hz stimulus frequency), whereas for visual recognition at least 500 stimuli are usually applied. Based on these results and on simulations, the phase-based techniques appear promising for the automated detection and monitoring of somatosensory evoked potentials.

Magnitude squared of coherence to detect imaginary movement

This work investigates the Magnitude Squared of Coherence (MSC) for detection of Event Related Potentials (ERPs) related to left-hand index finger movement. Initially, ERP presence was examined in different brain areas. To accomplish that, 20 EEG channels were used, positioned according to the 10–20 international system. The grand average, resulting from 10 normal subjects showed, as expected, responses at frontal, central, and parietal areas, particularly evident at the central area (C3, C4, Cz). The MSC, applied to movement imagination related EEG signals, detected a consistent response in frequencies around 0.3–1 Hz (delta band), mainly at central area (C3, Cz, and C4). Ability differences in control imagination among subjects produced different detection performance. Some subjects needed up to 45 events for a detectable response, while for some others only 10 events proved sufficient. Some subjects also required two or three experimental sessions in order to achieve detectable responses. For one subject, response detection was not possible at all. However, due to brain plasticity, it is plausible to expect that training sessions (to practice movement imagination) improve signal-noise ratio and lead to better detection using MSC. Results are sufficiently encouraging as to suggest further exploration of MSC for future BCI application.

Influence of 4 interfaces in the assessment of maximal respiratory pressures.

BACKGROUND: The measurement of maximal respiratory pressure (MRP) is a procedure widely used in clinical practice to evaluate respiratory muscle strength through the maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax). Its clinical applications include diagnostic procedures and evaluating responses to interventions. However, there is great variability in the equipment and measurement procedures. Understanding the impacts of the characteristics of different interfaces can augment the repeatability of this method and help to establish widely applicable predictive equations. The aim of this study was to evaluate the influence of 4 different interfaces on a subjects capacity to generate MRP and the impact of these interfaces on the repeatability of these measurements. METHODS: Fifty healthy subjects (mean ± SD age 26.36 ± 4.89 y) with normal spirometry were evaluated. MRP was measured by a digital manometer connected to 4 interfaces using different combinations of mouthpieces and tubes. The following variables were analyzed: maximum mean pressure, peak pressure, plateau pressure, and plateau variation. Analysis of variance for repeated measures or a Friedman test was used to compare the 4 interfaces, with P < .008 after Bonferroni adjustment considered significant. RESULTS: There was no significant difference between the 4 interfaces with respect to maximum mean pressure, peak pressure, plateau pressure, or plateau variation for PImax (P ≥ .49) or PEmax (P ≥ .11), nor did the number of tests performed to fulfill the criteria of repeatability for PImax (P = .69) or PEmax (P = .47) differ among the 4 interfaces. CONCLUSIONS: PImax and PEmax values seem not to be influenced by the different interfaces studied, suggesting that patient comfort and availability of interfaces can be considered.

Caracterização da variabilidade de freqüência cardíaca e sensibilidade do barorreflexo em indivíduos sedentários e atletas do sexo masculino

ABSTRACTCharacterization of heart rate variability and baroreflexsensitivity in sedentary individuals and male athletesIntroduction: The capacity to vary the heart rate representsimportant physiologic role in the daily life. The variations of the RRintervals is dependent of biological modulators as the autonomicnervous system. Those variations constitute the heart rate vari-ability (HRV). Methods: 10 athletes (Atl) and 10 sedentary (Sed)male individuals (20-35 age) were submitted to digital electrocar-diography, in rest, before, during and after the maneuver. The va-lues of RR were analyzed (software Matlab 6.1 ), in the time doma-in. Results: Both Sed and Atl presented mean heart rate of 73.5bpm ± 2,5 and 51 bpm ± 2,4, respectively. Related to the RR inter-vals, the group of Sed presented average of 826.58 bad ± 5.3 andthe group Atl, 1189.18 ± 6.9. The return time of sympathetic sys-tem after the maneuver was 72 ± 12 s (Sed) 37 ± 6 s (Atl). Thereturn time of parasympathetic system was 80 ± 11 s (Sed) and40 ± 8 s (Atl). The pNN50 was of 10 ± 3,3 (Sed) and 42,10 ± 6,9(Atl). The value of RR variation above the average of the wholesign was 343 ± 40 (Sed) and 175 ± 39 (Atl). The RR variation be-low the average of the whole sign was 281 ± 27 (Sed) and 425 ±26 (Atl).

Efeitos de diferentes esforços de luta de judô na atividade enzimática, atividade elétrica muscular e parâmetros biomecânicos de atletas de elite

El entrenamiento deportivo provoca adaptaciones neuromusculares y alteraciones metabolicas que buscan una actuacion durante la competicion. En las competencias de judo, el numero de luchas a que los atletas se someten asi como la duracion respectiva y los intervalos son al azar, factores estos que influencian en la actuacion y en el entrenamiento. El estudio presente investigo la hipotesis de que las duraciones diferentes de luchas, 90s 180s y 300s, podrian influir en la actividad enzimatico, electrico muscular y la produccion del pico del cambio. Antes y despues de cada lucha, fueron obtenidas las muestras sanguineas de los atletas, tan pronto despues de que los mismos lograron cinco reducciones dinamicas (90o/s) con el uso de un dinamometro isocinetico (Biodex Sistema 3). Simultaneamente se consignaron la senal electromiografica de los musculos agonistas, antagonistas y sinergica de los movimientos estimados. El estudio no verifico si hubo una alteracion en el torque. Las enzimas AST y ALT presentaran aumento en la actividad, en las luchas de 90s (p = 0,0033/p = 0,00059), 180s (p = 0,0044/p = 0,0033) y 300s (p = 0,0044/p = 0,0033). Un aumento (p = 0,0180) de la actividad de CK despues de que la lucha de 300s fue verificada. LDH disminuyo despues de la lucha de 90s (p = 0,0392). En el analisis intermuscular se observo despues de la lucha 90s un aumento de la senal electromiografica del agonista (p = 0,005), en la lucha 180s un aumento de la del antagonista (p = 0,0129) y en la lucha 300s una disminucion (p = 0,0137) de la actividad del musculo agonista. Fue observado, ademas, que los esfuerzos de la lucha de 300s podrian haber inducido lesiones en el tejido muscular caracterizado por una elevacion de CK plasmatico, aunque la lesion no ha sido bastante para descubrir la fatiga a traves de la dinamometria isocinetica. Ha mostrado que el protocolo propuesto era bastante para determinar las alteraciones enzimaticas y eletromiograficas, mientras hace pensar en las adaptaciones metabolicas y neurologicas que ocurren por la tension de las luchas del judo.

Low-frequency oscillations in human tibial somatosensory evoked potentials

Oscillatory cerebral electric activity has been related to sensorial and perceptual-cognitive functions. The aim of this work is to investigate low frequency oscillations (<300 Hz), particularly within the gamma band (30-110 Hz), during tibial stimulation. Twenty-one volunteers were subjected to 5 Hz stimulation by current pulses of 0.2 ms duration and the minimum intensity to provoke involuntary twitch. EEG signals without (spontaneously) and during stimulation were recorded at primary somatosensory area. A time-frequency analysis indicated the effect of the stimulus artifact in the somatosensory evoked potential (SEP) frequencies up to 5 ms after the stimulus. The oscillations up to 100 Hz presented the highest relative power contribution (approximately 99%) for the SEP and showed difference (p<0.01) from the frequencies of the spontaneously EEG average. Moreover, the range 30-58 Hz was identified as the band with the highest contribution for the tibial SEP morphology (p<0.0001).

An open-source, FireWire camera-based, Labview-controlled image acquisition system for automated, dynamic pupillometry and blink detection

The dynamic, accurate measurement of pupil size is extremely valuable for studying a large number of neuronal functions and dysfunctions. Despite tremendous and well-documented progress in image processing techniques for estimating pupil parameters, comparatively little work has been reported on practical hardware issues involved in designing image acquisition systems for pupil analysis. Here, we describe and validate the basic features of such a system which is based on a relatively compact, off-the-shelf, low-cost FireWire digital camera. We successfully implemented two configurable modes of video record: a continuous mode and an event-triggered mode. The interoperability of the whole system is guaranteed by a set of modular software components hosted on a personal computer and written in Labview. An offline analysis suite of image processing algorithms for automatically estimating pupillary and eyelid parameters were assessed using data obtained in human subjects. Our benchmark results show that such measurements can be done in a temporally precise way at a sampling frequency of up to 120 Hz and with an estimated maximum spatial resolution of 0.03 mm. Our software is made available free of charge to the scientific community, allowing end users to either use the software as is or modify it to suit their own needs.

The addition of functional task-oriented mental practice to conventional physical therapy improves motor skills in daily functions after stroke

Background Mental practice (MP) is a cognitive strategy which may improve the acquisition of motor skills and functional performance of athletes and individuals with neurological injuries. Objective To determine whether an individualized, specific functional task-oriented MP, when added to conventional physical therapy (PT), promoted better learning of motor skills in daily functions in individuals with chronic stroke (13±6.5 months post-stroke). Method Nine individuals with stable mild and moderate upper limb impairments participated, by employing an A1-B-A2 single-case design. Phases A1 and A2 included one month of conventional PT, and phase B the addition of MP training to PT. The motor activity log (MAL-Brazil) was used to assess the amount of use (AOU) and quality of movement (QOM) of the paretic upper limb; the revised motor imagery questionnaire (MIQ-RS) to assess the abilities in kinesthetic and visual motor imagery; the Minnesota manual dexterity test to assess manual dexterity; and gait speed to assess mobility. Results After phase A1, no significant changes were observed for any of the outcome measures. However, after phase B, significant improvements were observed for the MAL, AOU and QOM scores (p<0.0001), and MIQ-RS kinesthetic and visual scores (p=0.003; p=0.007, respectively). The significant gains in manual dexterity (p=0.002) and gait speed (p=0.019) were maintained after phase A2. Conclusions Specific functional task-oriented MP, when added to conventional PT, led to improvements in motor imagery abilities combined with increases in the AOU and QOM in daily functions, manual dexterity, and gait speed.

Evidências preliminares da efetividade do treinamento cognitivo para melhorar a inteligência de crianças escolares

The present research intends to verify the effectiveness of a cognitive training (CT) to foster intelligence of school Brazilian children from different intellectual levels. Sixteen fourth-grade boys (M = 8.75 years; SD = .44) took part in this study and were randomly selected to the training group (TG) or control group (CG). In the pre and posttest, all children were assessed using measures with measures of fluid, crystallized intelligence, and school achievement. For the training program we used working memory task for a period of two months. Results: no statically significant difference was found between both groups at posttest in none of the measures used. However, after training, there was a reduction of the differences between GC and GF on measures of fluid intelligence. In the case of Raven, the difference between CG and GE (favorable to GC) dropped from d = .126 to .058. In the TNVRI test, the initial difference in favor of CG (d = .177) became negative (d = -.384), therefore in favor of GE. This small benefit was not observed in tests of school knowledge, where GC had the biggest gains in the post-test assessment. The results are partially supported in the literature. However, studies with a larger sample, more training sessions and longer interval between post-tests to verify the generality of these findings.