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2025
Viviani, Carlos Alessandro Bassi; Elias, Leonardo Abdala; Calil, Saide Jorge
Design and usability assessment of touchscreen interface in medical devices: a case study of a neonatal incubator Journal Article
Em: Res. Biomed. Eng., vol. 41, não 1, 2025, ISSN: 2446-4740.
@article{Viviani2025,
title = {Design and usability assessment of touchscreen interface in medical devices: a case study of a neonatal incubator},
author = {Carlos Alessandro Bassi Viviani and Leonardo Abdala Elias and Saide Jorge Calil},
doi = {10.1007/s42600-025-00401-x},
issn = {2446-4740},
year = {2025},
date = {2025-03-00},
journal = {Res. Biomed. Eng.},
volume = {41},
number = {1},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2024
Romariz, Simone A. A.; Sanabria, Viviam; da Silva, Karina Ribeiro; Quintella, Miguel L.; de Melo, Bruna A. G.; Porcionatto, Marimélia; de Almeida, Danilo Candido; Longo, Beatriz M.
High Concentrations of Cannabidiol Induce Neurotoxicity in Neurosphere Culture System Journal Article
Em: Neurotox Res, vol. 42, não 1, 2024, ISSN: 1476-3524.
@article{Romariz2024,
title = {High Concentrations of Cannabidiol Induce Neurotoxicity in Neurosphere Culture System},
author = {Simone A. A. Romariz and Viviam Sanabria and Karina Ribeiro da Silva and Miguel L. Quintella and Bruna A. G. de Melo and Marimélia Porcionatto and Danilo Candido de Almeida and Beatriz M. Longo},
doi = {10.1007/s12640-024-00692-5},
issn = {1476-3524},
year = {2024},
date = {2024-02-00},
journal = {Neurotox Res},
volume = {42},
number = {1},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
2023
da Costa, Ana Paula Marques; Brunetto, Sergio Querino; Onusic, Daniel Massaro; Ramos, Celso Dario
Teste de Pureza Radioquímica em Serviços de Medicina Nuclear: Calibrador de Doses Versus Contador Gama Tipo Poço Journal Article
Em: Revista Brasileira De Física Médica, vol. 12, iss. 2, pp. 30-38, 2023.
Resumo | Links | BibTeX | Tags:
@article{nokey,
title = {Teste de Pureza Radioquímica em Serviços de Medicina Nuclear: Calibrador de Doses Versus Contador Gama Tipo Poço},
author = {Ana Paula Marques da Costa and Sergio Querino Brunetto and Daniel Massaro Onusic and Celso Dario Ramos},
doi = {https://doi.org/10.29384/rbfm.2018.v12.n2.p30-38},
year = {2023},
date = {2023-12-20},
journal = {Revista Brasileira De Física Médica},
volume = {12},
issue = {2},
pages = {30-38},
abstract = {O uso do radionuclídeo tecnécio-99m ligado a diversos fármacos é de suma importância na medicina nuclear, devido às suas características físico-químicas e radiológicas. Dentro dos serviços, é necessário um controle de qualidade de marcação eficaz, confiável e reprodutível visando eficácia do procedimento para que não exista concentração indesejável do material radioativo em outros órgãos além daqueles de interesse, devido às falhas da marcação. Um dos controles empregados nos serviços de medicina nuclear brasileiros é conhecido como determinação da pureza radioquímica (DPR), feito pela técnica de cromatografia em papel (coluna ascendente) e as aferições das atividades presentes nas amostras são feitas no medidor de atividades conhecido, também, como calibrador de doses. Este equipamento é eficiente sob o ponto de vista de aferir as atividades das alíquotas de radiofármacos administradas aos pacientes, entretanto, para avaliar a DPR são utilizadas atividades da ordem de milionésimo das administradas aos pacientes e, nessa faixa de atividade, supõe-se que o equipamento necessita de caracterizações e condições específicas para garantir a eficácia deste controle. O método padrão ouro para a aferição da DPR utiliza o contador gama tipo poço, entretanto, no Brasil o número de serviços de medicina nuclear com este tipo de equipamento é pequeno. Assim, o trabalho visou comparar os valores de eficiência obtidos nestes dois equipamentos. Na comparação, utilizou-se do teste não paramétrico de Wilcoxon com valor de significância (p-value) de 0,05 e não se encontrou diferenças significativas entre as medidas feitas com os equipamentos. Foram também determinadas às condições confiáveis para a utilização do medidor de atividades nas faixas de atividade empregas na DPR e as condições para que a radiação de fundo (background) do equipamento seja mínima a fim de não interferir na quantificação do teste cromatográfico.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
O uso do radionuclídeo tecnécio-99m ligado a diversos fármacos é de suma importância na medicina nuclear, devido às suas características físico-químicas e radiológicas. Dentro dos serviços, é necessário um controle de qualidade de marcação eficaz, confiável e reprodutível visando eficácia do procedimento para que não exista concentração indesejável do material radioativo em outros órgãos além daqueles de interesse, devido às falhas da marcação. Um dos controles empregados nos serviços de medicina nuclear brasileiros é conhecido como determinação da pureza radioquímica (DPR), feito pela técnica de cromatografia em papel (coluna ascendente) e as aferições das atividades presentes nas amostras são feitas no medidor de atividades conhecido, também, como calibrador de doses. Este equipamento é eficiente sob o ponto de vista de aferir as atividades das alíquotas de radiofármacos administradas aos pacientes, entretanto, para avaliar a DPR são utilizadas atividades da ordem de milionésimo das administradas aos pacientes e, nessa faixa de atividade, supõe-se que o equipamento necessita de caracterizações e condições específicas para garantir a eficácia deste controle. O método padrão ouro para a aferição da DPR utiliza o contador gama tipo poço, entretanto, no Brasil o número de serviços de medicina nuclear com este tipo de equipamento é pequeno. Assim, o trabalho visou comparar os valores de eficiência obtidos nestes dois equipamentos. Na comparação, utilizou-se do teste não paramétrico de Wilcoxon com valor de significância (p-value) de 0,05 e não se encontrou diferenças significativas entre as medidas feitas com os equipamentos. Foram também determinadas às condições confiáveis para a utilização do medidor de atividades nas faixas de atividade empregas na DPR e as condições para que a radiação de fundo (background) do equipamento seja mínima a fim de não interferir na quantificação do teste cromatográfico.
de Souza, Edna Marina; Castellano, Gabriela; Costa, Eduardo Tavares
Em: Revista Brasileira De Física Médica, vol. 5, iss. 1, pp. 89–92, 2023.
Resumo | Links | BibTeX | Tags:
@article{nokey,
title = {Influence of brain region of interest location for apparent diffusion coefficient maps calculation for reference values to be used in the in vivo characterization of brain tumors in magnetic resonance images},
author = {Edna Marina de Souza and Gabriela Castellano and Eduardo Tavares Costa},
doi = {https://doi.org/10.29384/rbfm.2011.v5.n1.p89-92},
year = {2023},
date = {2023-10-27},
urldate = {2023-10-27},
journal = {Revista Brasileira De Física Médica},
volume = {5},
issue = {1},
pages = {89–92},
abstract = {In general, pathologic processes, such as neoplasic cell changes, tend to alter the magnitude of structural organization by destruction or reorganization of membranous elements or by a change in cellularity. These changes will also have an impact on proton mobility, which can be followed up by DWI (diffusion weighted magnetic resonance imaging). From DWI is obtained the ADC (apparent diffusion coefficient) map, which is a representation of the magnitude of water diffusion at the points of a given region of interest (ROI). The purpose of this study was to assess the variation of ADC values in different brain ROIs of normal subjects, using a computer tool previously developed. The aim of this assessment was to verify whether ADC values could be used to differentiate between normal subjects and patients with multiform glioblastoma (a high-grade glioma) and meningioma. ADC maps were calculated for 10 controls, 10 patients with glioblastoma and 10 with meningioma. For controls, mean ADC values were calculated for 10 different ROIs, located in the same places where the tumors were present in the patients. These values were then averaged over ROIs and over subjects, giving a mean ADC value of (8.65±0.98)x10-4 mm2 /s. The mean ADC values found for brain tumors were (5.03±0.67) x10-4 mm2 /s for meningioma and (2.83±0.45)x10-4 mm2 /s for glioblastoma. We concluded that the ROIs used for computing brain ADC values for controls were not essential for the estimation of normal reference ADC values to be used in the differentiation between these types of tumors and healthy brain tissue},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In general, pathologic processes, such as neoplasic cell changes, tend to alter the magnitude of structural organization by destruction or reorganization of membranous elements or by a change in cellularity. These changes will also have an impact on proton mobility, which can be followed up by DWI (diffusion weighted magnetic resonance imaging). From DWI is obtained the ADC (apparent diffusion coefficient) map, which is a representation of the magnitude of water diffusion at the points of a given region of interest (ROI). The purpose of this study was to assess the variation of ADC values in different brain ROIs of normal subjects, using a computer tool previously developed. The aim of this assessment was to verify whether ADC values could be used to differentiate between normal subjects and patients with multiform glioblastoma (a high-grade glioma) and meningioma. ADC maps were calculated for 10 controls, 10 patients with glioblastoma and 10 with meningioma. For controls, mean ADC values were calculated for 10 different ROIs, located in the same places where the tumors were present in the patients. These values were then averaged over ROIs and over subjects, giving a mean ADC value of (8.65±0.98)x10-4 mm2 /s. The mean ADC values found for brain tumors were (5.03±0.67) x10-4 mm2 /s for meningioma and (2.83±0.45)x10-4 mm2 /s for glioblastoma. We concluded that the ROIs used for computing brain ADC values for controls were not essential for the estimation of normal reference ADC values to be used in the differentiation between these types of tumors and healthy brain tissue
Vecchio, Alessandro Del; Germer, Carina Marconi; Kinfe, Thomas M; Nuccio, Stefano; Hug, François; Eskofier, Bjoern; Farina, Dario; Enoka, Roger M
The Forces Generated by Agonist Muscles during Isometric Contractions Arise from Motor Unit Synergies Journal Article
Em: J Neurosci, vol. 43, não 16, pp. 2860–2873, 2023, ISSN: 1529-2401.
Resumo | Links | BibTeX | Tags:
@article{pmid36922028,
title = {The Forces Generated by Agonist Muscles during Isometric Contractions Arise from Motor Unit Synergies},
author = {Alessandro Del Vecchio and Carina Marconi Germer and Thomas M Kinfe and Stefano Nuccio and François Hug and Bjoern Eskofier and Dario Farina and Roger M Enoka},
doi = {10.1523/JNEUROSCI.1265-22.2023},
issn = {1529-2401},
year = {2023},
date = {2023-04-01},
journal = {J Neurosci},
volume = {43},
number = {16},
pages = {2860--2873},
abstract = {The purpose of our study was to identify the low-dimensional latent components, defined hereafter as motor unit modes, underlying the discharge rates of the motor units in two knee extensors (vastus medialis and lateralis, eight men) and two hand muscles (first dorsal interossei and thenars, seven men and one woman) during submaximal isometric contractions. Factor analysis identified two independent motor unit modes that captured most of the covariance of the motor unit discharge rates. We found divergent distributions of the motor unit modes for the hand and vastii muscles. On average, 75% of the motor units for the thenar muscles and first dorsal interosseus were strongly correlated with the module for the muscle in which they resided. In contrast, we found a continuous distribution of motor unit modes spanning the two vastii muscle modules. The proportion of the muscle-specific motor unit modes was 60% for vastus medialis and 45% for vastus lateralis. The other motor units were either correlated with both muscle modules (shared inputs) or belonged to the module for the other muscle (15% for vastus lateralis). Moreover, coherence of the discharge rates between motor unit pools was explained by the presence of shared synaptic inputs. In simulations with 480 integrate-and-fire neurons, we demonstrate that factor analysis identifies the motor unit modes with high levels of accuracy. Our results indicate that correlated discharge rates of motor units that comprise motor unit modes arise from at least two independent sources of common input among the motor neurons innervating synergistic muscles. It has been suggested that the nervous system controls synergistic muscles by projecting common synaptic inputs to the engaged motor neurons. In our study, we reduced the dimensionality of the output produced by pools of synergistic motor neurons innervating the hand and thigh muscles during isometric contractions. We found two neural modules, each representing a different common input, that were each specific for one of the muscles. In the vastii muscles, we found a continuous distribution of motor unit modes spanning the two synergistic muscles. Some of the motor units from the homonymous vastii muscle were controlled by the dominant neural module of the other synergistic muscle. In contrast, we found two distinct neural modules for the hand muscles.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The purpose of our study was to identify the low-dimensional latent components, defined hereafter as motor unit modes, underlying the discharge rates of the motor units in two knee extensors (vastus medialis and lateralis, eight men) and two hand muscles (first dorsal interossei and thenars, seven men and one woman) during submaximal isometric contractions. Factor analysis identified two independent motor unit modes that captured most of the covariance of the motor unit discharge rates. We found divergent distributions of the motor unit modes for the hand and vastii muscles. On average, 75% of the motor units for the thenar muscles and first dorsal interosseus were strongly correlated with the module for the muscle in which they resided. In contrast, we found a continuous distribution of motor unit modes spanning the two vastii muscle modules. The proportion of the muscle-specific motor unit modes was 60% for vastus medialis and 45% for vastus lateralis. The other motor units were either correlated with both muscle modules (shared inputs) or belonged to the module for the other muscle (15% for vastus lateralis). Moreover, coherence of the discharge rates between motor unit pools was explained by the presence of shared synaptic inputs. In simulations with 480 integrate-and-fire neurons, we demonstrate that factor analysis identifies the motor unit modes with high levels of accuracy. Our results indicate that correlated discharge rates of motor units that comprise motor unit modes arise from at least two independent sources of common input among the motor neurons innervating synergistic muscles. It has been suggested that the nervous system controls synergistic muscles by projecting common synaptic inputs to the engaged motor neurons. In our study, we reduced the dimensionality of the output produced by pools of synergistic motor neurons innervating the hand and thigh muscles during isometric contractions. We found two neural modules, each representing a different common input, that were each specific for one of the muscles. In the vastii muscles, we found a continuous distribution of motor unit modes spanning the two synergistic muscles. Some of the motor units from the homonymous vastii muscle were controlled by the dominant neural module of the other synergistic muscle. In contrast, we found two distinct neural modules for the hand muscles.
Elias, Leonardo Abdala; Hur, Pilwon; Sieck, Gary C
Editorial: Towards an understanding of spinal and corticospinal pathways and mechanisms Miscellaneous
2023, ISSN: 1662-5161.
@misc{pmid37025971,
title = {Editorial: Towards an understanding of spinal and corticospinal pathways and mechanisms},
author = {Leonardo Abdala Elias and Pilwon Hur and Gary C Sieck},
doi = {10.3389/fnhum.2023.1181647},
issn = {1662-5161},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Front Hum Neurosci},
volume = {17},
pages = {1181647},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
2022
Rocha, Fernanda Paula; Giesbrecht, Mateus
Machine learning algorithms for dengue risk assessment: a case study for São Luís do Maranhão Journal Article
Em: Comp. Appl. Math., vol. 41, não 8, 2022, ISSN: 1807-0302.
@article{Rocha2022,
title = {Machine learning algorithms for dengue risk assessment: a case study for São Luís do Maranhão},
author = {Fernanda Paula Rocha and Mateus Giesbrecht},
doi = {10.1007/s40314-022-02101-z},
issn = {1807-0302},
year = {2022},
date = {2022-12-00},
journal = {Comp. Appl. Math.},
volume = {41},
number = {8},
publisher = {Springer Science and Business Media LLC},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
dos Santos Cruz, Jonathan; Fruett, Fabiano; da Rocha Lopes, Renato; Takaki, Fabio Luiz; de Andrade Tambascia, Claudia; de Lima, Eduardo Rodrigues; Giesbrecht, Mateus
Partial Discharges Monitoring for Electric Machines Diagnosis: A Review Journal Article
Em: Energies, vol. 15, não 21, 2022, ISSN: 1996-1073.
Resumo | Links | BibTeX | Tags:
@article{Cruz2022,
title = {Partial Discharges Monitoring for Electric Machines Diagnosis: A Review},
author = {Jonathan dos Santos Cruz and Fabiano Fruett and Renato da Rocha Lopes and Fabio Luiz Takaki and Claudia de Andrade Tambascia and Eduardo Rodrigues de Lima and Mateus Giesbrecht},
doi = {10.3390/en15217966},
issn = {1996-1073},
year = {2022},
date = {2022-11-00},
journal = {Energies},
volume = {15},
number = {21},
publisher = {MDPI AG},
abstract = {Online monitoring of Partial Discharges (PDs) in rotating electrical machines is an useful tool for machine prognosis, as it presents reduced costs compared to intrusive inspections and is associated with relevant problems. Although this monitoring method has been developed for almost 50 years, the recent advancements in processes automation and signal processing techniques allow improvements that are still being studied by academic and industrial researchers. To analyze the current context of PDs monitoring, this article presents a literature review based on concepts of PDs in rotating machines, data acquisition techniques, state-of-the art commercial equipment, and recent methodologies for detection and pattern recognition of PDs. The challenges identified in the literature that motivate the development of more reliable and robust PD monitoring systems are presented and discussed. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Alegria, Elvis Jara; Giesbrecht, Mateus; Bottura, Celso Pascoli
An associative-memory-based method for system nonlinearities recursive estimation Journal Article
Em: Automatica, vol. 142, 2022, ISSN: 0005-1098.
@article{Alegria2022,
title = {An associative-memory-based method for system nonlinearities recursive estimation},
author = {Elvis Jara Alegria and Mateus Giesbrecht and Celso Pascoli Bottura},
doi = {10.1016/j.automatica.2022.110343},
issn = {0005-1098},
year = {2022},
date = {2022-08-00},
journal = {Automatica},
volume = {142},
publisher = {Elsevier BV},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
de Melo, Bruna A. G.; Mundim, Mayara V.; Lemes, Robertha M. R.; Cruz, Elisa M.; Ribeiro, Tais N.; Santiago, Carolina F.; da Fonsêca, Jéssica H. L.; Benincasa, Julia C.; Stilhano, Roberta S.; Mantovani, Nathalia; Santana, Luiz C.; Durães‐Carvalho, Ricardo; Diaz, Ricardo S.; Janini, Luiz M. R.; Maricato, Juliana T.; Porcionatto, Marimelia A.
3D Bioprinted Neural‐Like Tissue as a Platform to Study Neurotropism of Mouse‐Adapted SARS‐CoV‐2 Journal Article
Em: Advanced Biology, vol. 6, não 8, 2022, ISSN: 2701-0198.
Resumo | Links | BibTeX | Tags:
@article{deMelo2022,
title = {3D Bioprinted Neural‐Like Tissue as a Platform to Study Neurotropism of Mouse‐Adapted SARS‐CoV‐2},
author = {Bruna A. G. de Melo and Mayara V. Mundim and Robertha M. R. Lemes and Elisa M. Cruz and Tais N. Ribeiro and Carolina F. Santiago and Jéssica H. L. da Fonsêca and Julia C. Benincasa and Roberta S. Stilhano and Nathalia Mantovani and Luiz C. Santana and Ricardo Durães‐Carvalho and Ricardo S. Diaz and Luiz M. R. Janini and Juliana T. Maricato and Marimelia A. Porcionatto},
doi = {10.1002/adbi.202200002},
issn = {2701-0198},
year = {2022},
date = {2022-08-00},
journal = {Advanced Biology},
volume = {6},
number = {8},
publisher = {Wiley},
abstract = {Abstract The effects of neuroinvasion by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) become clinically relevant due to the numerous neurological symptoms observed in Corona Virus Disease 2019 (COVID‐19) patients during infection and post‐COVID syndrome or long COVID. This study reports the biofabrication of a 3D bioprinted neural‐like tissue as a proof‐of‐concept platform for a more representative study of SARS‐CoV‐2 brain infection. Bioink is optimized regarding its biophysical properties and is mixed with murine neural cells to construct a 3D model of COVID‐19 infection. Aiming to increase the specificity to murine cells, SARS‐CoV‐2 is mouse‐adapted (MA‐SARS‐CoV‐2) in vitro, in a protocol first reported here. MA‐SARS‐CoV‐2 reveals mutations located at the Orf1a and Orf3a domains and is evolutionarily closer to the original Wuhan SARS‐CoV‐2 strain than SARS‐CoV‐2 used for adaptation. Remarkably, MA‐SARS‐CoV‐2 shows high specificity to murine cells, which present distinct responses when cultured in 2D and 3D systems, regarding cell morphology, neuroinflammation, and virus titration. MA‐SARS‐CoV‐2 represents a valuable tool in studies using animal models, and the 3D neural‐like tissue serves as a powerful in vitro platform for modeling brain infection, contributing to the development of antivirals and new treatments for COVID‐19. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lara, Jéssica Rodrigues; da Silva, Cristiano Rocha; de Lima, Felipe Fava; da Silva, Marcos Camargo; Kohn, André Fabio; Elias, Leonardo Abdala; Magalhães, Fernando Henrique
Effects of light finger touch on the regularity of center-of-pressure fluctuations during quiet bipedal and single-leg postural tasks Journal Article
Em: Gait Posture, vol. 96, pp. 203–209, 2022, ISSN: 1879-2219.
Resumo | Links | BibTeX | Tags:
@article{pmid35696826,
title = {Effects of light finger touch on the regularity of center-of-pressure fluctuations during quiet bipedal and single-leg postural tasks},
author = {Jéssica Rodrigues Lara and Cristiano Rocha da Silva and Felipe Fava de Lima and Marcos Camargo da Silva and André Fabio Kohn and Leonardo Abdala Elias and Fernando Henrique Magalhães},
doi = {10.1016/j.gaitpost.2022.05.036},
issn = {1879-2219},
year = {2022},
date = {2022-07-01},
journal = {Gait Posture},
volume = {96},
pages = {203--209},
abstract = {BACKGROUND: The use of extra sources of sensory information associated with light fingertip touch to enhance postural steadiness has been associated with increased attentional demands, whereas the regularity of center of pressure (COP) fluctuations has been interpreted as a marker of the amount of attention invested in posture control.
RESEARCH QUESTION: This study addressed whether increased attentional demands associated with postural tasks involving light finger touch might be reflected by measures of COP regularity.
METHODS: The experiments involved quiet bipedal stance (n = 8 participants) and single-legged stance (n = 14 participants). Each participant was instructed to stand as quietly as possible on a force plate, either touching an external rigid surface (applied force < 1 N, light touch condition), or not (no touch condition). Postural steadiness was assessed by traditional COP measurements (COP Area, RMS, and velocity), whereas the regularity of postural sway was based on estimates of the sample entropy (SaEn) of the COP time series.
RESULTS: Traditional parameters of postural sway and COP regularity (inversely related to SaEn COP measurements) were reduced during the touch conditions as compared to the no-touch conditions, for both bipedal quiet stance and single-legged stance. Decreased COP regularity with light touch was mainly reflected in the direction of the largest postural sway (i.e. in the sagittal plane for bipedal stance and in the frontal plane for single-legged stance).
SIGNIFICANCE: The present results suggest that actively touching an external surface with the fingertip, besides increasing postural steadiness, generated an externally oriented (presumably cognitive-dependent) focus of attention, so that participants invested less attention on the postural task per se (as suggested by increased SaEn), which might be associated with a more "automatic" control of posture.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
BACKGROUND: The use of extra sources of sensory information associated with light fingertip touch to enhance postural steadiness has been associated with increased attentional demands, whereas the regularity of center of pressure (COP) fluctuations has been interpreted as a marker of the amount of attention invested in posture control.
RESEARCH QUESTION: This study addressed whether increased attentional demands associated with postural tasks involving light finger touch might be reflected by measures of COP regularity.
METHODS: The experiments involved quiet bipedal stance (n = 8 participants) and single-legged stance (n = 14 participants). Each participant was instructed to stand as quietly as possible on a force plate, either touching an external rigid surface (applied force < 1 N, light touch condition), or not (no touch condition). Postural steadiness was assessed by traditional COP measurements (COP Area, RMS, and velocity), whereas the regularity of postural sway was based on estimates of the sample entropy (SaEn) of the COP time series.
RESULTS: Traditional parameters of postural sway and COP regularity (inversely related to SaEn COP measurements) were reduced during the touch conditions as compared to the no-touch conditions, for both bipedal quiet stance and single-legged stance. Decreased COP regularity with light touch was mainly reflected in the direction of the largest postural sway (i.e. in the sagittal plane for bipedal stance and in the frontal plane for single-legged stance).
SIGNIFICANCE: The present results suggest that actively touching an external surface with the fingertip, besides increasing postural steadiness, generated an externally oriented (presumably cognitive-dependent) focus of attention, so that participants invested less attention on the postural task per se (as suggested by increased SaEn), which might be associated with a more "automatic" control of posture.
RESEARCH QUESTION: This study addressed whether increased attentional demands associated with postural tasks involving light finger touch might be reflected by measures of COP regularity.
METHODS: The experiments involved quiet bipedal stance (n = 8 participants) and single-legged stance (n = 14 participants). Each participant was instructed to stand as quietly as possible on a force plate, either touching an external rigid surface (applied force < 1 N, light touch condition), or not (no touch condition). Postural steadiness was assessed by traditional COP measurements (COP Area, RMS, and velocity), whereas the regularity of postural sway was based on estimates of the sample entropy (SaEn) of the COP time series.
RESULTS: Traditional parameters of postural sway and COP regularity (inversely related to SaEn COP measurements) were reduced during the touch conditions as compared to the no-touch conditions, for both bipedal quiet stance and single-legged stance. Decreased COP regularity with light touch was mainly reflected in the direction of the largest postural sway (i.e. in the sagittal plane for bipedal stance and in the frontal plane for single-legged stance).
SIGNIFICANCE: The present results suggest that actively touching an external surface with the fingertip, besides increasing postural steadiness, generated an externally oriented (presumably cognitive-dependent) focus of attention, so that participants invested less attention on the postural task per se (as suggested by increased SaEn), which might be associated with a more "automatic" control of posture.
Dideriksen, Jakob; Elias, Leonardo Abdala; Zambalde, Ellen Pereira; Germer, Carina Marconi; Molinari, Ricardo Gonçalves; Negro, Francesco
Influence of central and peripheral motor unit properties on isometric muscle force entropy: A computer simulation study Journal Article
Em: J Biomech, vol. 139, pp. 110866, 2022, ISSN: 1873-2380.
Resumo | Links | BibTeX | Tags:
@article{pmid34802707,
title = {Influence of central and peripheral motor unit properties on isometric muscle force entropy: A computer simulation study},
author = {Jakob Dideriksen and Leonardo Abdala Elias and Ellen Pereira Zambalde and Carina Marconi Germer and Ricardo Gonçalves Molinari and Francesco Negro},
doi = {10.1016/j.jbiomech.2021.110866},
issn = {1873-2380},
year = {2022},
date = {2022-06-01},
journal = {J Biomech},
volume = {139},
pages = {110866},
abstract = {Approximate entropy of isometric force is a popular measure to characterize behavioral changes across muscle contraction conditions. The degree to which force entropy characterizes the randomness of the motor control strategy, however, is not known. In this study, we used a computational model to investigate the correlation between approximate entropy of the synaptic input to a motor neuron pool, the neural drive to muscle (cumulative spike train; CST), and the force. This comparison was made across several simulation conditions, that included different synaptic command signal bandwidths, motor neuron pool sizes, and muscle contractile properties. The results indicated that although force entropy to some degree reflects the entropy of the synaptic command to motor neurons, it is biased by changes in motor unit properties. As a consequence, there was a low correlation between approximate entropy of force and the motor neuron input signal across all simulation conditions (r = 0.13). Therefore, force entropy should only be used to compare motor control strategies across conditions where motor neuron properties can be assumed to be maintained. Instead, we recommend that the entropy of the descending motor commands should be estimated from CSTs comprising spike trains of multiple motor units.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Approximate entropy of isometric force is a popular measure to characterize behavioral changes across muscle contraction conditions. The degree to which force entropy characterizes the randomness of the motor control strategy, however, is not known. In this study, we used a computational model to investigate the correlation between approximate entropy of the synaptic input to a motor neuron pool, the neural drive to muscle (cumulative spike train; CST), and the force. This comparison was made across several simulation conditions, that included different synaptic command signal bandwidths, motor neuron pool sizes, and muscle contractile properties. The results indicated that although force entropy to some degree reflects the entropy of the synaptic command to motor neurons, it is biased by changes in motor unit properties. As a consequence, there was a low correlation between approximate entropy of force and the motor neuron input signal across all simulation conditions (r = 0.13). Therefore, force entropy should only be used to compare motor control strategies across conditions where motor neuron properties can be assumed to be maintained. Instead, we recommend that the entropy of the descending motor commands should be estimated from CSTs comprising spike trains of multiple motor units.
Oshiyama, Natália Ferreira; Pereira, Ana H M; Cardoso, Alisson C; Franchini, Kleber G; Bassani, José Wilson Magalhães; Bassani, Rosana Almada
Developmental differences in myocardial transmembrane Na transport: implications for excitability and Na handling Journal Article
Em: J Physiol, vol. 600, não 11, pp. 2651–2667, 2022, ISSN: 1469-7793.
Resumo | Links | BibTeX | Tags:
@article{pmid35489088,
title = {Developmental differences in myocardial transmembrane Na transport: implications for excitability and Na handling},
author = {Natália Ferreira Oshiyama and Ana H M Pereira and Alisson C Cardoso and Kleber G Franchini and José Wilson Magalhães Bassani and Rosana Almada Bassani},
doi = {10.1113/JP282661},
issn = {1469-7793},
year = {2022},
date = {2022-06-01},
urldate = {2022-06-01},
journal = {J Physiol},
volume = {600},
number = {11},
pages = {2651--2667},
abstract = {Little is currently known about possible developmental changes in myocardial Na handling, which may have impact on cell excitability and Ca content. Resting intracellular Na concentration ([Na ] ), measured in freshly isolated rat ventricular myocytes with CoroNa green, was not significantly different in neonates (3-5 days old) and adults, but electrical stimulation caused marked [Na ] rise only in neonates. Inhibition of L-type Ca current by CdCl abolished not only systolic Ca transients, but also activity-dependent intracellular Na accumulation in immature cells. This indicates that the main Na influx pathway during activity is the Na /Ca exchanger, rather than voltage-dependent Na current (I ), which was not affected by CdCl . In immature myocytes, I density was two-fold greater, inactivation was faster, and the current peak occurred at less negative transmembrane potential (E ) than in adults. Na channel steady-state activation and inactivation curves in neonates showed a rightward shift, which should increase channel availability at diastolic E , but also require greater depolarization for excitation, which was observed experimentally and reproduced in computer simulations. Ventricular mRNA levels of Na 1.1, Na 1.4 and Na 1.5 pore-forming isoforms were greater in neonate ventricles, while a decrease was seen for the β1 subunit. Both molecular and biophysical changes in the channel profile may contribute to the differences in I density and voltage-dependence, and also to the less negative threshold E , in neonates compared to adults. The apparently lower excitability in immature ventricle may confer protection against the development of spontaneous activity in this tissue. KEY POINTS: Previous studies showed that myocardial preparations from immature rats are less sensitive to electrical field stimulation than adult preparations. Freshly isolated ventricular myocytes from neonatal rats showed lower excitability than adult cells, e.g. less negative threshold membrane potential and greater membrane depolarization required for action potential triggering. In addition to differences in mRNA levels for Na channel isoforms and greater Na current (I ) density, Na channel voltage-dependence was shifted to the right in immature myocytes, which seems to be sufficient to decrease excitability, according to computer simulations. Only in neonatal myocytes did cyclic activity promote marked cytosolic Na accumulation, which was prevented by abolition of systolic Ca transients by blockade of Ca currents. Developmental changes in I may account for the difference in action potential initiation parameters, but not for cytosolic Na accumulation, which seems to be due mainly to Na /Ca exchanger-mediated Na influx.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Little is currently known about possible developmental changes in myocardial Na handling, which may have impact on cell excitability and Ca content. Resting intracellular Na concentration ([Na ] ), measured in freshly isolated rat ventricular myocytes with CoroNa green, was not significantly different in neonates (3-5 days old) and adults, but electrical stimulation caused marked [Na ] rise only in neonates. Inhibition of L-type Ca current by CdCl abolished not only systolic Ca transients, but also activity-dependent intracellular Na accumulation in immature cells. This indicates that the main Na influx pathway during activity is the Na /Ca exchanger, rather than voltage-dependent Na current (I ), which was not affected by CdCl . In immature myocytes, I density was two-fold greater, inactivation was faster, and the current peak occurred at less negative transmembrane potential (E ) than in adults. Na channel steady-state activation and inactivation curves in neonates showed a rightward shift, which should increase channel availability at diastolic E , but also require greater depolarization for excitation, which was observed experimentally and reproduced in computer simulations. Ventricular mRNA levels of Na 1.1, Na 1.4 and Na 1.5 pore-forming isoforms were greater in neonate ventricles, while a decrease was seen for the β1 subunit. Both molecular and biophysical changes in the channel profile may contribute to the differences in I density and voltage-dependence, and also to the less negative threshold E , in neonates compared to adults. The apparently lower excitability in immature ventricle may confer protection against the development of spontaneous activity in this tissue. KEY POINTS: Previous studies showed that myocardial preparations from immature rats are less sensitive to electrical field stimulation than adult preparations. Freshly isolated ventricular myocytes from neonatal rats showed lower excitability than adult cells, e.g. less negative threshold membrane potential and greater membrane depolarization required for action potential triggering. In addition to differences in mRNA levels for Na channel isoforms and greater Na current (I ) density, Na channel voltage-dependence was shifted to the right in immature myocytes, which seems to be sufficient to decrease excitability, according to computer simulations. Only in neonatal myocytes did cyclic activity promote marked cytosolic Na accumulation, which was prevented by abolition of systolic Ca transients by blockade of Ca currents. Developmental changes in I may account for the difference in action potential initiation parameters, but not for cytosolic Na accumulation, which seems to be due mainly to Na /Ca exchanger-mediated Na influx.
Mehrotra, Shreya; de Melo, Bruna Alice Gomes; Miscuglio, Mario; Kiaee, Kiavash; Shin, Su Ryon; Mandal, Biman B.
Em: Adv Healthcare Materials, vol. 11, não 6, 2022, ISSN: 2192-2659.
Resumo | Links | BibTeX | Tags:
@article{Mehrotra2022,
title = {Mimicking Native Heart Tissue Physiology and Pathology in Silk Fibroin Constructs through a Perfusion‐Based Dynamic Mechanical Stimulation Microdevice},
author = {Shreya Mehrotra and Bruna Alice Gomes de Melo and Mario Miscuglio and Kiavash Kiaee and Su Ryon Shin and Biman B. Mandal},
doi = {10.1002/adhm.202101678},
issn = {2192-2659},
year = {2022},
date = {2022-03-00},
journal = {Adv Healthcare Materials},
volume = {11},
number = {6},
publisher = {Wiley},
abstract = {Abstract In vitro cardiomyocyte (CM) maturation is an imperative step to replicate native heart tissue‐like structures as cardiac tissue grafts or as drug screening platforms. CMs are known to interpret biophysical cues such as stiffness, topography, external mechanical stimulation or dynamic perfusion load through mechanotransduction and change their behavior, organization, and maturation. In this regard, a silk‐based cardiac tissue (CT) coupled with a dynamic perfusion‐based mechanical stimulation platform (DMM) for achieving maturation and functionality in vitro is tried to be delivered. Silk fibroin (SF) is used to fabricate lamellar scaffolds to provide native tissue‐like anisotropic architecture and is found to be nonimmunogenic and biocompatible allowing cardiomyocyte attachment and growth in vitro. Further, the scaffolds display excellent mechanical properties by their ability to undergo cyclic compressions without any deformation when places in the DMM. Gradient compression strains (5% to 20%), mimicking the native physiological and pathological conditions, are applied to the cardiomyocyte culture seeded on lamellar silk scaffolds in the DMM. A strain‐dependent difference in cardiomyocyte maturation, gene expression, sarcomere elongation, and extracellular matrix formation is observed. These silk‐based CTs matured in the DMM can open up several avenues toward the development of host‐specific grafts and in vitro models for drug screening. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ribeiro, Rebecca Fernandes; Frencl, Victor Baptista; Elias, Leonardo Abdala; do Val, João Bosco Ribeiro
A Case Study on the Removal of Blinking Artifact in Electroencephalogram Signals via Stochastic Filtering Journal Article
Em: Journal of Control, Automation and Electrical Systems, vol. 33, pp. 1319–1328, 2022.
Resumo | Links | BibTeX | Tags:
@article{nokey,
title = {A Case Study on the Removal of Blinking Artifact in Electroencephalogram Signals via Stochastic Filtering},
author = {Rebecca Fernandes Ribeiro and Victor Baptista Frencl and Leonardo Abdala Elias and João Bosco Ribeiro do Val },
doi = {https://doi.org/10.1007/s40313-021-00890-y},
year = {2022},
date = {2022-01-12},
journal = {Journal of Control, Automation and Electrical Systems},
volume = {33},
pages = {1319–1328},
abstract = {The presence of physiological artifacts in electroencephalogram (EEG) signals is common and detrimental to experimental or clinical analysis. This paper presents a case study where we develop an algorithm based on stochastic filtering to remove blinking artifacts. For this case study, the dynamic system was defined by combining two autoregressive models, the first one represents the EEG signal, and the second one represents the blinking artifact. Some applications use stochastic methods to remove artifacts, so in this paper we apply the stochastic filtering via Kalman filter, that makes possible to remove blinking artifacts from single-channel EEG recordings, as long as the electrooculogram (EOG) signal was available. The method applies to a case study with actual artifacts and simulated artifacts for comparison. The measure of performance utilized is the estimated power spectral density (PSD). The results show that the proposed method could remove blinking artifacts without introducing significant distortions in the EEG signal.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The presence of physiological artifacts in electroencephalogram (EEG) signals is common and detrimental to experimental or clinical analysis. This paper presents a case study where we develop an algorithm based on stochastic filtering to remove blinking artifacts. For this case study, the dynamic system was defined by combining two autoregressive models, the first one represents the EEG signal, and the second one represents the blinking artifact. Some applications use stochastic methods to remove artifacts, so in this paper we apply the stochastic filtering via Kalman filter, that makes possible to remove blinking artifacts from single-channel EEG recordings, as long as the electrooculogram (EOG) signal was available. The method applies to a case study with actual artifacts and simulated artifacts for comparison. The measure of performance utilized is the estimated power spectral density (PSD). The results show that the proposed method could remove blinking artifacts without introducing significant distortions in the EEG signal.