Effects of convective drying assisted by ultrasound and osmotic solution on polyphenol, antioxidant and microstructure of murtilla (Ugni molinae Turcz) fruit.

The effects of pretreatment with ultrasound and an osmotic solution combined with hot air convection drying on the total polyphenol content (TPC), antioxidant activity and microstructural of murtilla skin fruit were evaluated. The effects of ultrasound frequency (0 and 130 kHz), osmotic solution concentration (0 and 70 °Brix) and time (60 or 120 min) on the TPC and the antioxidant activities as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC) assays were evaluated. The TPC and DPPH antioxidant activity decreased significantly (p < 0.05) when ultrasound was applied at 0 °Brix for 60 min. Higher FRAP activity was obtained upon treatment with ultrasound and an osmotic solution for 60 min. The ORAC values did not significantly differ based on the pretreatment methods but decreased when an osmotic solution was applied for 120 min without ultrasound. When ultrasound and the osmotic solution were applied, the skin cells of the dried murtilla fruit became more distorted, resulting in larger spaces between them and causing loss of shape. Although the application of pretreatment procedures before murtilla fruit drying did not positively affect the TPC, DPPH or ORAC individually, the application of a Global Standardized Response based on the followed by a mathematical model adjustment indicated that a 70 °Brix osmotic solution applied for 60 min was the best treatment for preparing murtilla fruit aiming a high antioxidant activity in dried product.

Development and testing of acoustically-matched hydrogel-based electrodes for simultaneous EMG-ultrasound detection.

In this manuscript we describe the development and testing of a bipolar electrode for the simultaneous acquisition of ultrasound (US) images and surface electromyograms (EMGs) from the same muscle region. The developed electrode (bEMG-US) consists of two circular sensing regions (20 mm diameter) with fixed inter-electrode distance (3.5 cm, center-to-center). Both the sensing regions and the external structure of the electrode are made of hydrogel layers separated by insulating materials. The electrical properties (i.e., impedance and noise of the electrode-skin interface) and the quality of EMGs detected with the developed electrodes during electrically elicited contractions were assessed and compared with those provided by commercially available EMG electrodes. The effect of the bEMG-US electrode on US images was evaluated by comparing images detected from the same muscle region with and without the electrode interposed between the US probe and the skin. Tests on five subjects showed that the electrode-skin impedance of bEMG-US electrodes was higher than that of conventional EMG electrodes (mean (range): 15.6 (8.5-21.1) kΩ vs. 8.2 (4.9-16.5) kΩ). Despite higher impedance values, both electrode systems provided comparable, electrode-skin noise levels (1.4 (1.1-1.7) µV vs. 1.3 (1.0-1.5) µV) and M waves (normalized mean square error: 2.6 (0.6-6.8)%). The quality of US images detected with and without the bEMG-US electrode between the US probe and the skin was comparable, as demonstrated by the low errors in the estimation of anatomical variables in the two experimental conditions (range: (0.37-2.35) deg for pennation angle and (-0.31-0.1) cm for muscle thickness). Results demonstrate that bEMG-US can be used to acquire concurrently EMGs and US images from the same muscle region with a negligible effect on the quality of the two detected signals, thus allowing for a simultaneous, multimodal evaluation of muscle activation.

Does the amplitude of biceps brachii M waves increase similarly in both limbs during staircase, electrically elicited contractions?

OBJECTIVE: Humans usually tend to control more finely muscle force production in dominant than non-dominant upper limbs. It is well established that motor unit recruitment is a key mechanism by which muscle force is controlled, and we hypothesized that a relatively smaller number of motor units may be recruited in muscles of dominant than non-dominant limbs for any given increase in synaptic input. Hence, we investigated peripheral properties of dominant and non-dominant biceps brachii through the analysis of M-wave responses to incremental electrical stimulation. APPROACH: Current pulses at progressively greater intensities were applied in the proximal region of biceps brachii of 16 subjects while surface electromyograms were recorded with a grid of electrodes in the distal region. M-wave amplitude was averaged across channels and normalized with respect to the maximum amplitude value, separately for each stimulation intensity and limb. Amplitude-current intensity curves were interpolated to provide an equal number of stimulation levels between limbs. Differences between dominant and non-dominant arms were assessed through the average increase in M-wave amplitude for consecutive stimulation intensities (increments). MAIN RESULTS: Wilcoxon's signed-rank test showed that increments in the M-wave amplitude were significantly smaller (p = 0.017) in dominant than non-dominant biceps brachii. SIGNIFICANCE: The results suggest that there was a more gradual recruitment of motor units in biceps brachii of dominant than non-dominant arms. This is in agreement with the hypothesis of a broader spectrum of motor unit recruitment thresholds in the dominant arm, which may contribute to a finer regulation of force production.

Physiological arousal accompanying postural responses to external perturbations after stroke.

OBJECTIVE: The purpose of this study was to examine simultaneously the level of physiological arousal and the postural response to external perturbations in people post-stroke compared to age-matched controls to build a more comprehensive understanding of the effect of stroke on postural control and balance self-efficacy. METHODS: Participants stood with each foot on separate force platforms. Ten applications of loads of 2% body weight at the hips perturbed the participant anteriorly under two conditions: investigator-triggered or self-triggered (total 20). Electrodermal activity (EDA; measurement of physiological arousal), electromyography (EMG) of the ankle plantarflexor muscles and anterior-posterior center of pressure measurements were taken pre-perturbation (anticipatory) and post-perturbation (response) and compared between the initial (first two) and final (last two) perturbations. RESULTS: Participants post-stroke demonstrated significantly higher levels of anticipatory EDA and anticipatory paretic plantarflexor EMG during both self- and investigator-triggered conditions compared to controls. Anticipatory EDA levels were higher in the final perturbations in participants post-stroke in both conditions, but not in controls. Habituation of the EDA responses post-perturbation was exhibited in the self-triggered perturbations in controls, but not in participants post-stroke. CONCLUSIONS: Physiological arousal and postural control strategies of controls revealed habituation in response to self-triggered perturbations, whereas this was not seen in participants post-stroke. SIGNIFICANCE: Understanding the physiological arousal response to challenges to standing balance post-stroke furthers our understanding of postural control mechanisms post-stroke.

Between-day reliability of triceps surae responses to standing perturbations in people post-stroke and healthy controls: A high-density surface EMG investigation.

The reliability of triceps surae electromyographic responses to standing perturbations in people after stroke and healthy controls is unknown. High-Density surface Electromyography (HDsEMG) is a technique that records electromyographic signals from different locations over a muscle, overcoming limitations of traditional surface EMG such as between-day differences in electrode placement. In this study, HDsEMG was used to measure responses from soleus (SOL, 18 channels) and medial and lateral gastrocnemius (MG and LG, 16 channels each) in 10 people after stroke and 10 controls. Timing and amplitude of the response were estimated for each channel of the grids. Intraclass Correlation Coefficient (ICC) and normalized Standard Error of Measurement (SEM%) were calculated for each channel individually (single-channel configuration) and on the median of each grid (all-channels configuration). Both timing (single-channel: ICC=0.75-0.96, SEM%=5.0-9.1; all-channels: ICC=0.85-0.97; SEM%=3.5-6.2%) and amplitude (single-channel: ICC=0.60-0.91, SEM%=25.1-46.6; ICC=0.73-0.95, SEM%=19.3-42.1) showed good-to-excellent reliability. HDsEMG provides reliable estimates of EMG responses to perturbations both in individuals after stroke and in healthy controls; reliability was marginally better for the all-channels compared to the single-channel configuration.

Do sweep rowers symmetrically activate their low back muscles during indoor rowing?

This study investigates whether sweep rowers activate their low back muscles asymmetrically when exercising on a rowing ergometer. Given that indoor rowing imposes equal loading demands to left and right back muscles, any side differences in activation are expected to reflect asymmetric adaptations resulting from sweep rowing. In addition to trunk kinematics, surface electromyograms (EMGs) were sampled from multiple skin locations along the lumbar spine of six elite, sweep rowers. The distribution of EMG amplitude along the spine was averaged across strokes and compared between sides. Key results indicate a significant effect of trunk side on EMG amplitude and on the low back region where EMG amplitude was greatest. Such side differences were unlikely because of trunk lateral inclination and rotation, which were smaller than 5° for all rowers tested. Moreover, asymmetries manifested differently between participants; there was not a clear predominance of greater EMG amplitude toward the right/left side in portside/starboard rowers. These results suggest that (a) even during indoor rowing, sweep rowers activate asymmetrically their low back muscles; (b) factors other than rowing side might be associated with low back asymmetries; (c) spatial distribution of surface EMG amplitude is sensitive to bilateral changes in back muscles' activation.

Effect of Temperature, Time, and Material Thickness on the Dehydration Process of Tomato.

This study aimed to evaluate the effects of temperature, time, and thickness of tomatoes fruits during adiabatic drying process. Dehydration, a simple and inexpensive process compared to other conservation methods, is widely used in the food industry in order to ensure a long shelf life for the product due to the low water activity. This study aimed to obtain the best processing conditions to avoid losses and keep product quality. Factorial design and surface response methodology were applied to fit predictive mathematical models. In the dehydration of tomatoes through the adiabatic process, temperature, time, and sample thickness, which greatly contribute to the physicochemical and sensory characteristics of the final product, were evaluated. The optimum drying conditions were 60°C with the lowest thickness level and shorter time.

Does the global temporal activation differ in triceps surae during standing balance?

One of the most important muscular groups which contribute to maintain standing balance is triceps surae. However, it is unclear whether the postural controllers of triceps surae, medial gastrocnemius (MG) and soleus (SOL), have different temporal patterns of activation during upright stance. This paper aimed at evaluating whether the global temporal activation in triceps surae differ among young subjects during standing balance. Nine male volunteers performed two tasks: standing quietly and with voluntary back and forward sways over their ankle. Electromyograms (EMGs) from soleus medial (MSOL) and lateral (LSOL) regions and from MG were sampled with linear arrays of surface electrodes. The percentage of muscle activation in time (i.e. temporal index) was computed for each muscle during upright standing. The results revealed that the medial portion of soleus muscle (MSOL) was activated continuously compared to the lateral portion of soleus (LSOL) and MG, which were activated intermittently. Therefore, the global temporal activation differed among the postural muscles of triceps surae during standing balance.

A novel system of electrodes transparent to ultrasound for simultaneous detection of myoelectric activity and B-mode ultrasound images of skeletal muscles.

Application of two-dimensional surface electrode arrays can provide a means of mapping motor unit action potentials on the skin surface above a muscle. The resulting muscle tissue displacement can be quantified, in a single plane, using ultrasound (US) imaging. Currently, however, it is not possible to simultaneously map spatio-temporal propagation of activation and resulting tissue strain. In this paper, we developed and tested a material that will enable concurrent measurement of two-dimensional surface electromyograms (EMGs) with US images. Specific protocols were designed to test the compatibility of this new electrode material, both with EMG recording and with US analysis. Key results indicate that, for this new electrode material, 1) the electrode-skin impedance is similar to that of arrays of electrodes reported in literature; 2) the reflection of US at the electrode-skin interface is negligible; 3) the likelihood of observing missing contacts, short-circuits, and artifacts in EMGs is not affected by the US probe; 4) movement of tissues sampled by US can be tracked accurately. We, therefore, conclude this approach will facilitate multimodal imaging of muscle to provide new spatio-temporal information regarding electromechanical function of muscle. This is relevant to basic physiology-biomechanics of active and passive force transmission through and between muscles, of motor unit spatio-temporal activity patterns, of their variation with architecture and task-related function, and of their adaptation with aging, training-exercise-disuse, neurological disease, and injury.

New data on the ecology and geographic distribution of Saguinus inustus Schwarz, 1951 (Primates, Callitrichidae).

Saguinus inustus (Schwarz, 1951) is one of the neotropical primates least studied. The distribution of the species ranges from the north of the Solimões River, between the Negro and Japurá Rivers in Brazil, and Guayabero-Guaviare Rivers in Colombia. Nevertheless, due to the low number of specimens collected from the lower Japurá and lower Negro Rivers areas, the geographic distribution is so far poorly delineated. In this study, field data was composed of sightings and the collection of specimens during a survey of mammal diversity in the Amana Sustainable Development Reserve (ASDR). For this survey, two 40-day expeditions were carried out in 2004. The first one occurred during the flooded season in June and July, and the second was during the peak of the dry season in October. Direct sightings were made through hiking along transects, navigation along water channels with a 30-hp speedboat, and gliding along flooded trails in the forest. New records of S. inustus were made in 11 different localities in ASDR. The study has confirmed the presence of the species in the Amanã area, carrying out the first records of the species in flooded forest habitats.

Estimation procedures affect the center of pressure frequency analysis.

Even though frequency analysis of body sway is widely applied in clinical studies, the lack of standardized procedures concerning power spectrum estimation may provide unreliable descriptors. Stabilometric tests were applied to 35 subjects (20-51 years, 54-95 kg, 1.6-1.9 m) and the power spectral density function was estimated for the anterior-posterior center of pressure time series. The median frequency was compared between power spectra estimated according to signal partitioning, sampling rate, test duration, and detrending methods. The median frequency reliability for different test durations was assessed using the intraclass correlation coefficient. When increasing number of segments, shortening test duration or applying linear detrending, the median frequency values increased significantly up to 137%. Even the shortest test duration provided reliable estimates as observed with the intraclass coefficient (0.74-0.89 confidence interval for a single 20-s test). Clinical assessment of balance may benefit from a standardized protocol for center of pressure spectral analysis that provides an adequate relationship between resolution and variance. An algorithm to estimate center of pressure power density spectrum is also proposed.

Estimation procedures affect the center of pressure frequency analysis

Even though frequency analysis of body sway is widely applied in clinical studies, the lack of standardized procedures concerning power spectrum estimation may provide unreliable descriptors. Stabilometric tests were applied to 35 subjects (20-51 years, 54-95 kg, 1.6-1.9 m) and the power spectral density function was estimated for the anterior-posterior center of pressure time series. The median frequency was compared between power spectra estimated according to signal partitioning, sampling rate, test duration, and detrending methods. The median frequency reliability for different test durations was assessed using the intraclass correlation coefficient. When increasing number of segments, shortening test duration or applying linear detrending, the median frequency values increased significantly up to 137%. Even the shortest test duration provided reliable estimates as observed with the intraclass coefficient (0.74-0.89 confidence interval for a single 20-s test). Clinical assessment of balance may benefit from a standardized protocol for center of pressure spectral analysis that provides an adequate relationship between resolution and variance. An algorithm to estimate center of pressure power density spectrum is also proposed.

Deformação relativa e frouxidão do tendão calcanear durante mobilização articular passiva através de ultra-sonografia por imagem / Strain and slackness of achilles tendon during passive joint mobilization via imaging ultrasonography

CONTEXTUALIZAÇÃO: O estudo do comportamento das propriedades mecânicas do tendão in vivo pode trazer avanços na avaliação do impacto de programas de intervenção para flexibilidade e força, nas áreas clínica e desportiva. OBJETIVO: O objetivo deste trabalho foi quantificar a deformação (strain) e a frouxidão (slackness) relativas do tendão calcanear, durante mobilização passiva para quatro ângulos articulares do tornozelo e dois do joelho. MATERIAIS E MÉTODOS: O deslocamento da junção miotendínea foi quantificado através de imagens ultra-sonográficas capturadas durante a mobilização passiva do tornozelo, com o auxílio de um eletrogoniômetro e um eletromiógrafo, para garantir as angulações requeridas e a inatividade muscular, respectivamente. RESULTADOS: Os valores de deformação relativa encontrados variaram de 4,28±2,37 a -0,94±1,58 por cento para o joelho estendido e de 2,38±1,63 a -2,32±2,16 por cento para o joelho fletido. CONCLUSÕES: Os valores encontrados ratificam os da literatura, demonstrando a participação do tendão calcanear na variação do comprimento da unidade músculo-tendão, durante movimentação passiva. Estes resultados sugerem que as propriedades mecânicas dos tecidos tendinosos afetam a relação entre o comprimento das fibras e o ângulo articular, até mesmo nesse tipo de movimento.

BACKGROUND: In vivo study of the mechanical behavior of tendons may bring advances in evaluating the impact of intervention programs for flexibility and strength, in clinical practice and sports. OBJECTIVE: The aim of this study was to quantify the relative strain and slackness of achilles tendons during passive mobilization, for four ankle joint angles and two knee angles. METHODS: The displacement of the muscle-tendon junction was quantified by means of ultrasound images acquired during passive ankle mobilization, with the aid of an electrogoniometer and an electromyograph to ensure the achievement of the required angles and muscle inactivity, respectively. RESULTS: The strain values ranged from 4.28 percent±2.37 to -0.94 percent±1.58 for the fully extended knee, and from 2.38 percent±1.63 to -2.32 percent±2.16 percent for the flexed knee. CONCLUSIONS: The values found in this study confirm those in the literature and demonstrate how the Achilles tendon participates in length changes in the muscle-tendon unit during passive movement. These results suggest that the mechanical properties of tendinous tissues affect the relationship between the length of muscle fibers and the joint angle, even during this type of movement.

Ultraviolet spectrophotometric evaluation of corn oil oxidative stability during microwave heating and oven test.

The effect of microwave heating on the oxidative stability of corn oil was determined by absorptivity in the UV spectrum and by peroxide and acid values. Oil samples with antioxidants BHA/BHT (1:1; 200 mg kg(-)(1)), with and without citric acid, were heated in a microwave oven (800 W, 2450 MHz) for 0-36 min. Absorptivity at 232 and 270 nm increased during microwave exposure. Control values of absorptivity at 232 nm increased from 3.568 to 12.874 after 36 min of heating. Peroxide value showed a significant difference in the initial stage of heating (0-6 min), but after this time, the peroxide value decreased due to the instability of hydroperoxides at high temperatures. Control 232 nm absorptivities after 6 days in the oven test were similar to those after 32-36 min of microwave heating. Effective antioxidants in the oven test did not show any protection during microwave heating. UV spectrophotometry is a suitable tool for microwave oxidation monitoring.

[Morphometric determination of changes in mastocyte population in cutaneous wound granulation tissue in hypothyroid and parotidectomized rats]. / Determinacão morfométrica da variacão da populacão mastocitária do tecido de granulacão de feridas cutâneas em ratos hipotireoídeos e parotidectomizados.

The authors have done a morphometric study by determination of mastocyte population of cutaneous wound's granulation tissue of parotidectomized rats and rats which were submitted to daily administration of 25 mg of 6-propyl-2-thiouracil (hypothyroid). The animals were sacrificed after four, eight and 12 post-operative days. The results analysis permitted to observe a statistically significant diminution of mastocyte population in the hypothyroid and parotidectomized animals granulation tissue in the fourth and 12th postsurgical days.