Scielo RSS <![CDATA[Research on Biomedical Engineering]]> vol. 34 num. 2 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Analysis of laser therapy effects in <em>Sporothrix schenckii</em> inactivation <em>in vivo</em>]]> Abstract Introduction Sporotrichosis is a common disease in tropical regions, caused by the fungus Sporothrix schenckii, affecting mainly rural workers and in direct contact with animals. Although treatment by indiscriminate use of oral antifungal drugs gives rise resistant isolates, leading to therapeutic failures and no remission of the disease. To evaluate the effectiveness of red low-power laser photobiomodulation in inactivation of S. schenckii infection induced in rodents. Methods Subcutaneously inoculation (2x103 S. schenckii/ml, 0.2 ml suspension) in the left footpad, in 27 mice divided into: control (n = 6, inoculated, without irradiation): early stage (not inoculated) = 1th biopsy; intermediate (9 weeks of evolution) = 2nd biopsy; final (21 weeks of evolution) = 3th biopsy. Treated (n = 21, inoculated and irradiated): early (13 weeks of evolution, 4 weeks after first irradiation) = 4th biopsy, intermediate (17 weeks of evolution, 8 weeks after first irradiation) = 5th biopsy, final (21 weeks of evolution, 12 weeks after first irradiation) = 6th biopsy. Serial irradiation with biopsies occurred every 30 days during each month, for three months. At the end of testing, the mice were euthanized, and histological analyzes of biopsies were performed. Results Each laser treatment session showed an inactivation of S. schenckii in treated animals compared to controls, with a regression of pseudoepitheliomatous hyperplasia, chronic inflammation, neutrophils, granulomas, giant mononuclear cells and steroid corpuscles. Conclusion The laser photobiomodulation was effective on S. schenckii inactivation, appearing to be an interesting therapeutic option in infections caused by this organism. <![CDATA[Peripheral device to quantify grip and pinch capacity of children]]> Abstract Introduction Grip and pinch movements are important to perform daily activities and to manipulate objects. In this paper we describe the development and evaluation of a peripheral device to quantify cylindrical grip, pulp-to-pulp pinch, pulp-to-side pinch strength and range of motion of children. Methods Three objects were selected: a door handle, a switch, and a key, which were instrumented with force sensing resistors to analyse the strength. Potentiometers were used to verify the range of motion and micro switches to assure the correct position of the fingers during the movement execution. Thirty volunteers (8.77 ± 1.28), both male and female, were selected to test the peripheral device functionality. Results The results determined the minimum necessary strength values for the object activation and maximum displacement, in which the values are 2.5N, 40°; 2.7N, 55°; and 2.8N, 100%, for door handle object, key object, and switch object, respectively. In the functionally tests, volunteers have shown a superior strength for activating each object and 73.33% of them have completed the range movement in the key object, 86.67% in the switch object, and 93.33% in the door handle object. Conclusion The developed peripheral device enabled the measurement of range and static and dynamic strength of grip and pinch movements of children. <![CDATA[Preliminary results of cervical impedance measurements]]> AbstractIntroduction: In this work, we report the development and initial tests of a measuring system that is used to measure the cervical electrical impedance with the purpose of assessing cervical ripening. The objective is to offer a system that provides real-time information about the cervical electrical impedance and, indirectly, of the cervical ripening with the aim of preventing premature birth. Methods Probes were developed and initial tests were performed. The probes used had electrodes that are far apart, with the assumption that in such cases deeper layers of the cervical tissue are measured. Results Preliminary measurements were performed in a single session on a non-gravid uterus, using as excitation signal a sinusoidal wave with frequency varying from 3 kHz to 100 kHz. Results indicate, as expected, that the magnitude of the impedance is inversely proportional to the frequency, indicating capacitive impedance. Conclusion Preliminary results were very encouraging. However, further measurements must be performed to correlate the impedance to the cervical ripening. <![CDATA[Development of radiofrequency ablation device for surgical hepatocellular carcinoma treatment in agreement with Brazilian standards]]> Abstract Introduction Many studies have been carried out on the main causes of hepatocellular carcinoma (HCC) to identify suitable diagnosis methods and treatments to combat the disease. However, high equipment costs and the lack of hepatic-ablation technologies manufactured in Brazil encourage the design and implementation of a solution based on normative principles. Methods The analysis and description of equipment features were the first steps in defining the design requirements and constraints. Equipment functionalities were evaluated with three assays set by NBR-IEC 60601-2-2. Results The assays of output control adjustment accuracy, output control adjustment monotonicity, and signal quality evaluation using the crest factor (CF) for the equipment showed thresholds superior to the aforementioned standard. Conclusion State-of-the-art studies have contributed the equipment construction. The construction process was validated by assays to ensure the equipment functionality with raw materials at acceptable costs. The test results showed the superiority of the equipment in relation to the assays proposed by the standard NBR-IEC 60601-2-2. However, to convert the prototype into a commercial product, other analyses are necessary. <![CDATA[Alternative class III distributed polysomnography system]]> Abstract Introduction Impairment of sleep quality directly increases the risk of heart attack, obesity, and stroke, among other conditions, which makes polysomnography (PSG) an important public health tool. However, the inherent problems with PSG render the correct diagnosis of sleep diseases a difficult task. As a novel alternative to the class II PSG system, this work presents a distributed system composed of three modules, which together are capable of the simultaneous monitoring of environmental variables and patient signals. This system could reduce the distress of a PSG exam in certain cases, dismiss the need for an overnight sleep in a healthcare/sleep centre, and facilitate self-setup and internet-based diagnosis. Methods Hardware and software capable of synchronously monitoring, processing and logging into a µSD card environmental parameters (temperature, humidity, visible light intensity and audible noise level) and directly measured patient signals (electrocardiogram, electrooculogram, and body and limb posture) were designed and implemented. Results A novel alternative to the class III PSG system was demonstrated with independent boards capable of operating for more than 16 hours powered by a 750 mAh/3.7 V battery with 0.003% data loss during preliminary PSG exams. Additionally, a computer-based library capable of reading, decoding, estimating respiration through ECG, and calculating the heart rate was developed and described. Conclusion This article contributes to PSG research through the development of a new PSG system and the improvement of patient comfort. All software and hardware developed are fully open source and available on GitHub. <![CDATA[Quantitative MRI data in Multiple Sclerosis patients: a pattern recognition study]]> Abstract Introduction Multiple Sclerosis (MS) is a neurodegenerative disease characterized by inflammatory demyelination in the central nervous system. Quantitative Magnetic Resonance Imaging (qMRI) enables a detailed characterization of brain tissue, but generates a large number of numerical results. In this study, we elucidated the main qMRI techniques and the brain regions that allow the identification of MS patients from neuroimaging data and pattern recognition techniques. Methods The data came from the combination of computational tools of image processing and neuroimaging acquired in a 3 Tesla scanner using different techniques: Diffusion, T2 Relaxometry, Magnetization Transfer Ratio (MTR) and Structural Morphometry. Data from 126 brain regions of 203 healthy individuals and 124 MS patients were separated into two groups and processed in a data-mining program using the k-nearest-neighbor (KNN) algorithm. Results The most relevant anatomical structures in the classification procedure were: corpus callosum, precuneus, left cerebellum and fusiform. Among the quantitative techniques the most relevant was the MTR, being indicated for longitudinal studies of this disease. KNN with 5 neighbors and pre-selected attributes had a better performance with an area under the ROC curve (97.3%) and accuracy (95.7%). A restricted classification considering only brain regions previously reported in the literature as affected by MS brought slightly lower scores, area: 97.1% and accuracy: 93.2%. Conclusion The use of standard recognition techniques from quantitative neuroimaging techniques has confirmed that the white matter of the brain is the most affected tissue by MS following a global pattern with greater involvement of the left hemisphere. <![CDATA[Photoacoustic-based thermal image formation and optimization using an evolutionary genetic algorithm]]> Abstract Introduction For improved efficiency and security in heat application during hyperthermia, it is important to monitor tissue temperature during treatments. Photoacoustic (PA) pressure wave amplitude has a temperature dependence given by the Gruenesein parameter. Consequently, changes in PA signal amplitude carry information about temperature variation in tissue. Therefore, PA has been proposed as an imaging technique to monitor temperature during hyperthermia. However, no studies have compared the performance of different algorithms to generate PA-based thermal images. Methods Here, four methods to estimate variations in PA signal amplitude for thermal image formation were investigated: peak-to-peak, integral of the modulus, autocorrelation of the maximum value, and energy of the signal. Changes in PA signal amplitude were evaluated using a 1-D window moving across the entire image. PA images were acquired for temperatures ranging from 36oC to 41oC using a phantom immersed in a temperature controlled thermal bath. Results The results demonstrated that imaging processing parameters and methods involved in tracking variations in PA signal amplitude drastically affected the sensitivity and accuracy of thermal images formation. The sensitivity fluctuated more than 20% across the different methods and parameters used. After optimizing the parameters to generate the thermal images using an evolutionary genetic algorithm (GA), the percentage of pixels within the acceptable error was improved, in average, by 7.5%. Conclusion Optimization of processing parameters using GA could increase the accuracy of measurement for this experimental setup and improve quality of PA-based thermal images. <![CDATA[Mean scatterer space estimation from ultrasound signals combining singular spectral analysis and entropy]]> AbstractIntroduction: Ultrasound (US) is a nonionizing radiation capable of real time imaging at low cost. Its most attractive application is quantitative tissue characterization with the objective of differentiating normal tissues from diseased tissues. In this study, an automated method using singular spectrum analysis (SSA) to estimate the mean scatterer space (MSS) of US signals is proposed. Methods Entropy was used to determine the optimal number of components for the SSA. Subsequently, this number was compared with the results using a fixed number of components. A method based on the spectrum of the original signal was also used for comparison. The method was evaluated by using 24,000 simulated US signals, i.e., echoes and jitters backscattered from samples with different ratios of regular-to-irregular structure, as well as with 152 signals obtained from a phantom made of nylon wires. Results For the simulated signals, the proposed method for estimating the MSS presented results similar to the other methods that were tested. However, the magnitude-of-the-spectrum method loses the phase information, and hence, does not allow the characterization of irregular structures. For the signals recorded from the phantom, the methods using SSA and entropy achieved better results. Conclusion In this study, the combination of SSA with entropy to estimate the MSS of a periodic or quasi-periodic medium was proposed. The proposed method achieved similar or better results compared with two other methods found in the scientific literature. The novelty of the proposed method is the application of entropy as a quantitative criterion for selecting the SSA periodic components, allowing it to become independent of heuristic criteria. <![CDATA[AACVOX: mobile application for augmentative alternative communication to help people with speech disorder and motor impairment]]> AbstractIntroduction: Communication is a fundamental element for the development of human beings, promoting their coexistence in society. However, changes in muscle tone, associated with cerebral palsy (CP), among other conditions, cause phono-articulatory dysfunctions hindering speech capabilities. Although there are resources for augmentative and alternative communication (AAC), most of them do not completely satisfy the needs of individuals with motor impairment. Therefore, this study proposes a tool based on mobile technology for AAC, which can be adapted to the characteristics of the motor limitations of CP users. Methods Mobile system development was conducted employing user-centered design and development methods. Functions were developed allowing the communication of phrases through pictographic resources and a mechanism of speech synthesis, that can be customized according to specific communication needs. To validate this system, 20 CP volunteers with speech difficulties and motor impairment were recruited from two institutions in the State of São Paulo, Brazil. They operated the system following a pre-defined test protocol, and they answered a system usability scale (SUS) questionnaire, to rate the ease of learning, memorization, efficiency, occurrence of runtime errors, and the level of user satisfaction. Results The results showed a score of 85.85 ± 2.28 above the average SUS scale, for each one of the quality components assessed by the volunteers. Conclusion The developed software is user-friendly, representing a new option for AAC, and is customized according to the communication needs of people with speech disorder and motor impairment. <![CDATA[Perspectives on the modeling of the neuromusculoskeletal system to investigate the influence of neurodegenerative diseases on sensorimotor control]]> Abstract Introduction The understanding of the neurophysiological mechanisms underlying movement control can be much furthered using computational models of the neuromusculoskeletal system. Biologically based multi-scale neuromusculoskeletal models have a great potential to provide new theories and explanations related to mechanisms behind muscle force generation at the molecular, cellular, synaptic, and systems levels. Albeit some efforts have been made to investigate how neurodegenerative diseases alter the dynamics of individual elements of the neuromuscular system, such diseases have not been analyzed from a systems viewpoint using multi-scale models. Overview and Perspectives This perspective article synthesizes what has been done in terms of multi-scale neuromuscular development and points to a few directions where such models could be extended so that they can be useful in the future to discover early predictors of neurodegenerative diseases, as well as to propose new quantitative clinical neurophysiology approaches to follow the course of improvements associated with different therapies (drugs or others). Concluding Remarks Therefore, this article will present how existing biologically based multi-scale models of the neuromusculoskeletal system could be expanded and adapted for clinical applications. It will point to mechanisms operating at different levels that would be relevant to be considered during model development, along with implications for interpreting experimental results from neurological patients.