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1.
Stroke ; 52(3): 811-820, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33567874

RESUMO

BACKGROUND AND PURPOSE: This study aimed to analyze the impact of baseline posterior circulation Acute Stroke Prognosis Early Computed Tomography Score (pc-ASPECTS) on the efficacy and safety of endovascular therapy (EVT) for patients with acute basilar artery occlusion. METHODS: The BASILAR was a nationwide prospective registry of consecutive patients with a symptomatic and radiologically confirmed acute basilar artery occlusion within 24 hours of symptom onset. We estimated the effect of standard medical therapy alone (SMT group) versus SMT plus EVT (EVT group) for patients with documented pc-ASPECTS on noncontrast CT, both as a categorical (0-4 versus 5-7 versus 8-10) and as a continuous variable. The primary outcomes included favorable functional outcomes (modified Rankin Scale ≤3) at 90 days and mortality within 90 days. RESULTS: In total, 823 cases were included: 468 with pc-ASPECTS 8 to 10 (SMT: 71; EVT: 397), 317 with pc-ASPECTS 5 to 7 (SMT: 85; EVT: 232), and 38 with pc-ASPECTS 0 to 4 (SMT: 13; EVT: 25). EVT was associated with higher rate of favorable outcomes (adjusted relative risk with 95% CI, 4.35 [1.30-14.48] and 3.20 [1.68-6.09]; respectively) and lower mortality (60.8% versus 77.6%, P=0.005 and 35.0% versus 66.2%, P<0.001; respectively) than SMT in the pc-ASPECTS 5 to 7 and 8 to 10 subgroups. Continuous benefit curves also showed the superior efficacy and safety of EVT over SMT in patients with pc-ASPECTS ≥5. Furthermore, the prognostic effect of onset to puncture time on favorable outcome with EVT was not significant after adjustment for pc-ASPECTS (adjusted odds ratio, 0.98 [95% CI, 0.94-1.02]). CONCLUSIONS: Patients of basilar artery occlusion with pc-ASPECTS ≥5 could benefit from EVT. The baseline pc-ASPECTS appears more important for decision making and predicting prognosis than time to EVT. Registration: URL: http://www.chictr.org.cn. Unique identifier: ChiCTR1800014759.


Assuntos
Artéria Basilar/diagnóstico por imagem , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/diagnóstico , Tomografia Computadorizada por Raios X/métodos , Idoso , Arteriopatias Oclusivas/complicações , Procedimentos Endovasculares/métodos , Humanos , Pessoa de Meia-Idade , Variações Dependentes do Observador , Prognóstico , Estudos Prospectivos , Sistema de Registros , Trombectomia/métodos , Resultado do Tratamento , Insuficiência Vertebrobasilar/complicações
2.
BMC Infect Dis ; 21(1): 141, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33535989

RESUMO

BACKGROUND: The impact of COVID-19 has been devastating on a global scale. The negative conversion time (NCT) of SARS-CoV-2 RNA is closely related to clinical manifestation and disease progression in COVID-19 patients. Our study aimed to predict factors associated with prolonged NCT of SARS-CoV-2 RNA in mild/moderate COVID-19 patients. METHODS: The clinical features, laboratory data and treatment outcomes of COVID-19 patients were retrospectively analyzed. Then univariate and multivariate analysis were used to screen out risk factors of influencing prolonged NCT of SARS-CoV-2 RNA. RESULTS: Thirty-two hospitalized mild/moderate COVID-19 patients were enrolled. The general clinical symptoms were cough (78.1%), fever (75%), diarrhea (68.8%), expectoration (56.3%), and nausea (37.5%). More than 40% of the patients had decreased erythrocyte, hemoglobin and leucocyte and 93.8% patients were detected in abnormalities of chest CT. The median NCT of SARS-CoV-2 RNA was 19.5 days (IQR: 14.25-25). Univariate analysis found fever, nausea, diarrhea and abnormalities in chest CTs were positively associated with prolonged NCT of viral RNA (P< 0.05). The multivariate Cox proportional hazard model revealed that fever [Exp (B), 0.284; 95% CI, 0.114-0.707; P<0.05] and nausea [Exp (B), 0.257; 95%CI, 0.096-0.689; P<0.05] were two significant independent factors. CONCLUSIONS: Fever and nausea were two significant independent factors in prolonged NCT of viral RNA in mild/moderate COVID-19 patients, which provided a useful references for disease progression and treatment of COVID-19.


Assuntos
COVID-19/diagnóstico , RNA Viral/metabolismo , SARS-CoV-2/genética , Adulto , COVID-19/complicações , COVID-19/patologia , COVID-19/virologia , Teste de Ácido Nucleico para COVID-19 , Tosse/etiologia , Diarreia/etiologia , Feminino , Febre/etiologia , Hospitalização , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Fatores de Risco , SARS-CoV-2/isolamento & purificação , Índice de Gravidade de Doença , Tórax/diagnóstico por imagem , Fatores de Tempo
3.
J Neurophysiol ; 122(1): 176-183, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31017842

RESUMO

Hyperexcitability of spinal motoneurons may contribute to muscular hypertonia after hemispheric stroke. The origins of this hyperexcitability are not clear, but we hypothesized that prolongation of the Ia excitatory postsynaptic potential (EPSP) in spastic motoneurons may be one potential mechanism, by enabling more effective temporal summation of Ia EPSPs, making action potential initiation easier. Thus, the purpose of this study is to quantify the time course of putative EPSPs in spinal motoneurons of chronic stroke survivors. To estimate the EPSP time course, a pair of low-intensity electrical stimuli was delivered sequentially to the median nerve in seven hemispheric stroke survivors and in six intact individuals, to induce an H-reflex response from the flexor carpi radialis muscle. H-reflex response probability was then used to quantify the time course of the underlying EPSPs in the motoneuron pool. A population EPSP estimate was then derived, based on the probability of evoking an H-reflex from the second test stimulus in the absence of a reflex response to the first conditioning stimulus. Our experimental results showed that in six of seven hemispheric stroke survivors, the apparent rate of decay of the population EPSP was markedly slower in spastic compared with contralateral (stroke) and intact motoneuron pools. There was no significant difference in EPSP time course between the contralateral side of stroke survivors and control subject muscles. We propose that one potential mechanism for hyperexcitability of spastic motoneurons in chronic stroke survivors may be associated with this prolongation of the Ia EPSP time course. Our subthreshold double-stimulation approach could provide a noninvasive tool for quantifying the time course of EPSPs in both healthy and pathological conditions. NEW & NOTEWORTHY Spastic motoneurons in stroke survivors showed a prolonged Ia excitatory postsynaptic potential (EPSP) time course compared with contralateral and intact motoneurons, suggesting that one potential mechanism for hyperexcitability of spastic motoneurons in chronic stroke survivors may be associated with this prolongation of the Ia EPSP time course.


Assuntos
Potenciais Pós-Sinápticos Excitadores , Neurônios Motores/fisiologia , Acidente Vascular Cerebral/fisiopatologia , Adulto , Idoso , Feminino , Reflexo H , Humanos , Masculino , Pessoa de Meia-Idade , Tempo de Reação
4.
Muscle Nerve ; 57(1): E85-E93, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28877550

RESUMO

INTRODUCTION: Muscle force generation involves recruitment and firing rate modulation of motor units (MUs). The control of MUs in producing multidirectional forces remains unclear. METHODS: We studied MU recruitment and firing properties, recorded from the first dorsal interosseous muscle, for 3 different directions of contraction: abduction; abduction/flexion combination; and flexion. RESULTS: MUs were recruited systematically at higher threshold force during flexion. Larger MUs were recruited and firing rates of MUs were lower during abduction. There was an orderly recruitment of MUs according to MU size regardless of contraction direction, obeying the "size principle." Firing rates of earlier-recruited MUs were consistently higher than later-recruited MUs, affirming the "onion-skin" property. DISCUSSION: Our findings suggest that the size principle and onion-skin organization together provide a general description of MU recruitment patterns and firing properties. The directional alternations of MU control properties likely reflect changes in neural drive to the muscle. Muscle Nerve 57: E85-E93, 2018.


Assuntos
Músculos do Dorso/fisiologia , Neurônios Motores/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Adolescente , Adulto , Músculos do Dorso/citologia , Eletromiografia , Feminino , Humanos , Contração Isométrica , Masculino , Contração Muscular/fisiologia , Recrutamento Neurofisiológico/fisiologia , Adulto Jovem
5.
J Neurophysiol ; 115(6): 2830-9, 2016 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-26984420

RESUMO

Synchronization between the firing times of simultaneously active motor units (MUs) is generally assumed to increase during fatiguing contractions. To date, however, estimates of MU synchronization have relied on indirect measures, derived from surface electromyographic (EMG) interference signals. This study used intramuscular coherence to investigate the correlation between MU discharges in the first dorsal interosseous muscle during and immediately following a submaximal fatiguing contraction, and after rest. Coherence between composite MU spike trains, derived from decomposed surface EMG, were examined in the delta (1-4 Hz), alpha (8-12 Hz), beta (15-30 Hz), and gamma (30-60 Hz) frequency band ranges. A significant increase in MU coherence was observed in the delta, alpha, and beta frequency bands postfatigue. In addition, wavelet coherence revealed a tendency for delta-, alpha-, and beta-band coherence to increase during the fatiguing contraction, with subjects exhibiting low initial coherence values displaying the greatest relative increase. This was accompanied by an increase in MU short-term synchronization and a decline in mean firing rate of the majority of MUs detected during the sustained contraction. A model of the motoneuron pool and surface EMG was used to investigate factors influencing the coherence estimate. Simulation results indicated that changes in motoneuron inhibition and firing rates alone could not directly account for increased beta-band coherence postfatigue. The observed increase is, therefore, more likely to arise from an increase in the strength of correlated inputs to MUs as the muscle fatigues.


Assuntos
Dedos/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Eletromiografia , Feminino , Humanos , Contração Isométrica/fisiologia , Masculino , Modelos Neurológicos , Periodicidade , Volição , Análise de Ondaletas
6.
J Fluoresc ; 26(2): 739-44, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26753758

RESUMO

Rapid and sensitive detection of heavy-metal ions in natural water environments worldwide is urgently needed because of their severe threats to human health. In the present work, monolayer graphite-like flake C3N4 (g-C3N4) materials were applied as a new fluorescent sensor for the detection of trace silver ion in aqueous solution. The thickness of synthesized g-C3N4 was 0.45 nm and obtained by exfoliating twice with ultrasonic. With the presence of ethylene diamine tetraacetic acid as a screening agent, the highly sensitive sensor reached a low detection limit of 52.3 nmol/L for silver (I) ion and there was no disturbance when silver (I) ion coexisted with other metal ions in water samples. Under the optimal conditions, the monolayer g-C3N4 was successfully used to detect trace silver (I) ion in different environmental water and drinking water samples.


Assuntos
Técnicas Biossensoriais/métodos , Colorimetria/métodos , Corantes Fluorescentes/química , Nitrilas/química , Prata/análise , Poluentes Químicos da Água/análise , Humanos
7.
J Sep Sci ; 39(8): 1533-41, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27106768

RESUMO

An aptamer with adenosine triphosphate as a ligand was immobilized onto the surface of a porous-polymer-coated fiber to obtain an aptamer-functionalized porous-polymer-coated solid-phase microextraction fiber. The fiber was observed with a crosslinked and porous morphological surface structure. It shows specific selectivity to adenosine triphosphate with a selectivity coefficient of 22.1 compared to the scrambled oligonucleotide functionalized fiber, and the selectivity factors over other analogues and reference compounds were from 6.1 to 77.5. When the fiber-based solid-phase microextraction was coupled with liquid chromatography and tandem mass spectrometry, detection limits of 2.7, 29, and 34 µg/L were achieved for adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate, respectively. The spiking recoveries of 77.6-91.9% were achieved for trace adenosine phosphates in human serum sample. Furthermore, the fibers showed high stability and good reusability and could be used over 50 times for the real serum sample pretreatment without remarkable performance reduction.


Assuntos
Nucleotídeos de Adenina/análise , Aptâmeros de Nucleotídeos/química , Microextração em Fase Sólida , Cromatografia Líquida , Humanos , Tamanho da Partícula , Polímeros/química , Porosidade , Propriedades de Superfície , Espectrometria de Massas em Tandem
8.
J Tradit Chin Med ; 36(6): 768-78, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-29949710

RESUMO

OBJECTIVE: To investigate the effect of low frequency electro-pulse acupuncture (EA) on blood glucose in rats with streptozotocin-induced type 2 diabetes, and the possible mechanism underlying the action. METHODS: Rat models were established with high fat feeding and intraperitoneal injection of streptozotocin (STZ) (30 mg/kg). Rats with a random blood glucose > 16.7 mmol/L and blood glucose at 2 h-point of oral glucose tolerance test (OGTT) > 11.1 mmol/L were included as diabetic rats, and randomly divided into model group, EA Weiwanxiashu (EX-B 3) group, EA Zusanli (ST 36) group, glimepiride group, and EA non-acupoint group (n = 12). EA (2 Hz continuous wave, 2 mA, 20 min/day, 6 days/week, 4 weeks) and intra-gastric administration of glimepiride were applied as interventions. With fasting blood glucose and OGTT tested at the end of the intervention, the study observed the patterns of hypoglycemic effects. For mechanism study, it observes hematoxylin and eosin staining and Masson staining of pancreas paraffin sections, protein expression of glucagon- like peptide 1 receptor (GLP-1R) in the pancreas and skeletal muscle, glucose transporter 4 (GLUT4) protein expression in skeletal muscle membrane, to detect whether EA controls blood glucose via regulation of GLP-1R. RESULTS: EA Weiwanxiashu (EX-B 3) significantly increased model rats' pancreas GLP-1R, and GLUT4 of skeletal muscle membrane; the therapy significantly decreased model rats' skeletal muscle GLP-1R, restored pancreas morphology, and reduced fasting blood glucose and insulin resistance indices. CONCLUSION: EA Weiwanxiashu (EX-B 3) alone has significant effect on glycemia. EA Weiwanxiashu (EX-B 3) plus glimepiride further strengthen the effect. The regulation of the GLP-1R in pancreas and skeletal muscle might be mechanism underpinning the effect.


Assuntos
Pontos de Acupuntura , Diabetes Mellitus Tipo 2/terapia , Eletroacupuntura , Animais , Glicemia/metabolismo , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Transportador de Glucose Tipo 4/genética , Transportador de Glucose Tipo 4/metabolismo , Frequência Cardíaca , Humanos , Resistência à Insulina , Masculino , Ratos , Ratos Sprague-Dawley , Estreptozocina/efeitos adversos
9.
J Neurophysiol ; 113(6): 1952-7, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25540228

RESUMO

Hyperexcitable motoneurons are likely to contribute to muscle hypertonia after a stroke injury; however, the origins of this hyperexcitability are not clear. One possibility is that the effective duration of the Ia excitatory postsynaptic potential (EPSP) is prolonged, increasing the potential for temporal summation of EPSPs, making action potential initiation easier. Accordingly, the purpose of this study was to quantify the time course of EPSPs in motoneurons of stroke survivors. The experimental protocol, which was based on parameters derived from simulation, involved sequential subthreshold electrical stimuli delivered to the median nerve of hemispheric stroke survivors. The resulting H-reflex responses were recorded in the flexor carpi radialis muscle. H-reflex response probability was then used to quantify the time course of the underlying EPSPs in the motoneuron pool. A population EPSP was estimated based on the probability of evoking an H reflex from the second electrical stimulus in the absence of a reflex response to the first stimulus. The accuracy of this time-course estimate was quantified using a computer simulation that explored a range of feasible EPSP parameters. Our experimental results showed that in all five hemispheric stroke survivors the rate of decay of the population EPSP was consistently slower in spastic compared with the contralateral motoneuron pools. We propose that one potential mechanism for hyperexcitability of motoneurons in spastic stroke survivors may be linked to this prolongation of the Ia EPSP time course. Our subthreshold double-stimulation approach also provides a noninvasive tool for quantifying the time course of EPSPs in both healthy and pathological conditions.


Assuntos
Potenciais Pós-Sinápticos Excitadores , Neurônios Motores/fisiologia , Espasticidade Muscular/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Idoso , Feminino , Reflexo H , Humanos , Masculino , Nervo Mediano/fisiopatologia , Pessoa de Meia-Idade
10.
J Neurophysiol ; 113(9): 3186-96, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25761952

RESUMO

The neuromuscular strategies employed to compensate for fatigue-induced muscle force deficits are not clearly understood. This study utilizes surface electromyography (sEMG) together with recordings of a population of individual motor unit action potentials (MUAPs) to investigate potential compensatory alterations in motor unit (MU) behavior immediately following a sustained fatiguing contraction and after a recovery period. EMG activity was recorded during abduction of the first dorsal interosseous in 12 subjects at 20% maximum voluntary contraction (MVC), before and directly after a 30% MVC fatiguing contraction to task failure, with additional 20% MVC contractions following a 10-min rest. The amplitude, duration and mean firing rate (MFR) of MUAPs extracted with a sEMG decomposition system were analyzed, together with sEMG root-mean-square (RMS) amplitude and median frequency (MPF). MUAP duration and amplitude increased immediately postfatigue and were correlated with changes to sEMG MPF and RMS, respectively. After 10 min, MUAP duration and sEMG MPF recovered to prefatigue values but MUAP amplitude and sEMG RMS remained elevated. MU MFR and recruitment thresholds decreased postfatigue and recovered following rest. The increase in MUAP and sEMG amplitude likely reflects recruitment of larger MUs, while recruitment compression is an additional compensatory strategy directly postfatigue. Recovery of MU MFR in parallel with MUAP duration suggests a possible role for metabolically sensitive afferents in MFR depression postfatigue. This study provides insight into fatigue-induced neuromuscular changes by examining the properties of a large population of concurrently recorded single MUs and outlines possible compensatory strategies involving alterations in MU recruitment and MFR.


Assuntos
Potenciais de Ação/fisiologia , Contração Isométrica/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Recrutamento Neurofisiológico/fisiologia , Análise de Variância , Eletromiografia , Feminino , Humanos , Masculino
11.
J Fluoresc ; 25(5): 1397-402, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26250058

RESUMO

In the present work, the CdTe quantum dots were covalently conjugated with permethylated-ß-cyclodextrin (OMe-ß-CD) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride as cross-linking reagent. The obtained functional quantum dots (OMe-ß-CD/QDs) showed highly luminescent, water solubility and photostability as well as good inclusion ability to malachite green. A sensitive fluorescence method was developed for the analysis of malachite green in different samples. The good linearity was 2.0 × 10(-7)-1.0 × 10(-5) mol/L and the limit of detect was 1.7 × 10(-8) mol/L. The recoveries for three environmental water samples were 92.0-108.2 % with relative standard deviation (RSD) of 0.24-1.87 %, while the recovery for the fish sample was 94.3 % with RSD of 1.04 %. The results showed that the present method was sensitive and convenient to determine malachite green in complex samples. Graphical Abstract The analytical mechanism of OMe-ß-CD/QDs and its linear response to MG.

12.
Luminescence ; 30(1): 18-25, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24833131

RESUMO

The determination of hormone-binding sites in plants is essential in understanding the mechanisms behind hormone function. Salicylic acid (SA) is an important plant hormone that regulates responses to biotic and abiotic stresses. In order to label SA-binding sites in plant tissues, a quantum dots (QDs) probe functionalized with a SA moiety was successfully synthesized by coupling CdSe QDs capped with 3-mercaptopropionic acid (MPA) to 4-amino-2-hydroxybenzoic acid (PAS), using 1-ethyl-3-(3-dimethyllaminopropyl) carbodiimide (EDC) as the coupling agent. The probe was then characterized by dynamic light scattering and transmission electron microscopy, as well as UV/vis and fluorescence spectrophotometry. The results confirmed the successful conjugation of PAS to CdSe QDs and revealed that the conjugates maintained the properties of the original QDs, with small core diameters and adequate dispersal in solution. The PAS-CdSe QDs were used to detect SA-binding sites in mung bean and Arabidopsis thaliana seedlings in vitro and in vivo. The PAS-CdSe QDs were effectively transported into plant tissues and specifically bound to SA receptors in vivo. In addition, the effects of the PAS-CdSe QDs on cytosolic Ca(2+) levels in the tips of A. thaliana seedlings were investigated. Both SA and PAS-CdSe QDs had similar effects on the trend in cytosolic-free Ca(2+) concentrations, suggesting that the PAS-CdSe QDs maintained the bioactivity of SA. To summarize, PAS-CdSe QDs have high potential as a fluorescent probe for the in vitro/in vivo labeling and imaging of SA receptors in plants.


Assuntos
Arabidopsis/química , Compostos de Cádmio/química , Pontos Quânticos , Ácido Salicílico/análise , Sementes/química , Compostos de Selênio/química , Sítios de Ligação , Compostos de Cádmio/síntese química , Compostos de Cádmio/isolamento & purificação , Tamanho da Partícula , Compostos de Selênio/síntese química , Compostos de Selênio/isolamento & purificação , Propriedades de Superfície
13.
J Neurophysiol ; 112(6): 1447-56, 2014 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24920018

RESUMO

Hemispheric brain injury resulting from a stroke is often accompanied by muscle weakness in limbs contralateral to the lesion. In the present study, we investigated whether weakness in contralesional hand muscle in stroke survivors is partially attributable to alterations in motor unit activation, including alterations in firing rate modulation range. The afterhyperpolarization (AHP) potential of a motoneuron is a primary determinant of motoneuron firing rate. We examined differences in AHP duration in motoneurons innervating paretic and less impaired (contralateral) limb muscles of hemiparetic stroke survivors as well as in control subjects. A novel surface EMG (sEMG) electrode was used to record motor units from the first dorsal interosseous muscle. The sEMG data were subsequently decomposed to derive single-motor unit events, which were then utilized to produce interval (ISI) histograms of the motoneuron discharges. A modified version of interval death rate (IDR) analysis was used to estimate AHP duration. Results from data analyses performed on both arms of 11 stroke subjects and in 7 age-matched control subjects suggest that AHP duration is significantly longer for motor units innervating paretic muscle compared with units in contralateral muscles and in units of intact subjects. These results were supported by a coefficient of variation (CV) analysis showing that paretic motor unit discharges have a lower CV than either contralateral or control units. This study suggests that after stroke biophysical changes occur at the motoneuron level, potentially contributing to lower firing rates and potentially leading to less efficient force production in paretic muscles.


Assuntos
Potenciais da Membrana , Neurônios Motores/fisiologia , Músculo Esquelético/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Potenciais de Ação , Idoso , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/inervação , Paresia/fisiopatologia , Acidente Vascular Cerebral/complicações
14.
IEEE J Biomed Health Inform ; 28(7): 3907-3917, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38568770

RESUMO

Existing electromyographic (EMG) based motor intent detection algorithms are typically user-specific, and a generic model that can quickly adapt to new users is highly desirable. However, establishing such a model remains a challenge due to high inter-person variability and external interference with EMG signals. In this study, we present a feature disentanglement approach, implemented by an autoencoder-like architecture, designed to decompose user-invariant, motor-task-sensitive high-level representations from user-sensitive, task-irrelevant representations in EMG amplitude features. Our method is user-generic and can be applied to unseen users for continuous multi-finger force predictions. We evaluated our approach on eight subjects, predicting the force of three fingers (index, middle, and ring-pinky) concurrently. We assessed the decoder's performance through a rigorous leave-one-subject-out validation. Our developed approach consistently outperformed both the conventional EMG amplitude method and a commonly used feature projection approach, principal component analysis (PCA), with a lower force prediction error (RMSE: 6.91 ± 0.45 % MVC; R2: 0.835 ± 0.026) and a higher finger classification accuracy (83.0 ± 4.5%). The comparison with the state-of-the-art neural networks further demonstrated the superior performance of our method in user-generic force predictions. Overall, our methods provide novel insights into the development of user-generic and accurate neural decoding for myoelectric control of assistive robotic hands.


Assuntos
Algoritmos , Eletromiografia , Dedos , Processamento de Sinais Assistido por Computador , Humanos , Eletromiografia/métodos , Dedos/fisiologia , Masculino , Adulto , Feminino , Adulto Jovem
15.
Comput Biol Med ; 173: 108384, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38554657

RESUMO

Reliable prediction of multi-finger forces is crucial for neural-machine interfaces. Various neural decoding methods have progressed substantially for accurate motor output predictions. However, most neural decoding methods are performed in a supervised manner, i.e., the finger forces are needed for model training, which may not be suitable in certain contexts, especially in scenarios involving individuals with an arm amputation. To address this issue, we developed an unsupervised neural decoding approach to predict multi-finger forces using spinal motoneuron firing information. We acquired high-density surface electromyogram (sEMG) signals of the finger extensor muscle when subjects performed single-finger and multi-finger tasks of isometric extensions. We first extracted motor units (MUs) from sEMG signals of the single-finger tasks. Because of inevitable finger muscle co-activation, MUs controlling the non-targeted fingers can also be recruited. To ensure an accurate finger force prediction, these MUs need to be teased out. To this end, we clustered the decomposed MUs based on inter-MU distances measured by the dynamic time warping technique, and we then labeled the MUs using the mean firing rate or the firing rate phase amplitude. We merged the clustered MUs related to the same target finger and assigned weights based on the consistency of the MUs being retained. As a result, compared with the supervised neural decoding approach and the conventional sEMG amplitude approach, our new approach can achieve a higher R2 (0.77 ± 0.036 vs. 0.71 ± 0.11 vs. 0.61 ± 0.09) and a lower root mean square error (5.16 ± 0.58 %MVC vs. 5.88 ± 1.34 %MVC vs. 7.56 ± 1.60 %MVC). Our findings can pave the way for the development of accurate and robust neural-machine interfaces, which can significantly enhance the experience during human-robotic hand interactions in diverse contexts.


Assuntos
Dedos , Mãos , Humanos , Dedos/fisiologia , Músculo Esquelético/fisiologia , Eletromiografia/métodos , Neurônios Motores/fisiologia
16.
Comput Biol Med ; 178: 108700, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38852400

RESUMO

Event-related potentials (ERPs) can quantify brain responses to reveal the neural mechanisms of sensory perception. However, ERPs often reflect nonlinear mixture responses to multiple sources of sensory stimuli, and an accurate separation of the response to each stimulus remains a challenge. This study aimed to separate the ERP into nonlinearly mixed source components specific to individual stimuli. We developed an unsupervised learning method based on clustering of manifold structures of mixture signals combined with channel optimization for signal source reconstruction using non-negative matrix factorization (NMF). Specifically, we first implemented manifold learning based on Local Tangent Space Alignment (LTSA) to extract the spatial manifold structure of multi-resolution sub-signals separated via wavelet packet transform. We then used fuzzy entropy to extract the dynamical process of the manifold structures and performed a k-means clustering to separate different sources. Lastly, we used NMF to obtain the optimal contributions of multiple channels to ensure accurate source reconstructions. We evaluated our developed approach using a simulated ERP dataset with known ground truth of two components of ERP mixture signals. Our results show that the correlation coefficient between the reconstructed source signal and the true source signal was 92.8 % and that the separation accuracy in ERP amplitude was 91.6 %. The results show that our unsupervised separation approach can accurately separate ERP signals from nonlinear mixture source components. The outcomes provide a promising way to isolate brain responses to multiple stimulus sources during multisensory perception.

17.
IEEE Trans Biomed Eng ; 71(6): 1831-1840, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38215325

RESUMO

OBJECTIVE: Dexterous control of robot hands requires a robust neural-machine interface capable of accurately decoding multiple finger movements. Existing studies primarily focus on single-finger movement or rely heavily on multi-finger data for decoder training, which requires large datasets and high computation demand. In this study, we investigated the feasibility of using limited single-finger surface electromyogram (sEMG) data to train a neural decoder capable of predicting the forces of unseen multi-finger combinations. METHODS: We developed a deep forest-based neural decoder to concurrently predict the extension and flexion forces of three fingers (index, middle, and ring-pinky). We trained the model using varying amounts of high-density EMG data in a limited condition (i.e., single-finger data). RESULTS: We showed that the deep forest decoder could achieve consistently commendable performance with 7.0% of force prediction errors and R2 value of 0.874, significantly surpassing the conventional EMG amplitude method and convolutional neural network approach. However, the deep forest decoder accuracy degraded when a smaller amount of data was used for training and when the testing data became noisy. CONCLUSION: The deep forest decoder shows accurate performance in multi-finger force prediction tasks. The efficiency aspect of the deep forest lies in the short training time and small volume of training data, which are two critical factors in current neural decoding applications. SIGNIFICANCE: This study offers insights into efficient and accurate neural decoder training for advanced robotic hand control, which has the potential for real-life applications during human-machine interactions.


Assuntos
Eletromiografia , Dedos , Redes Neurais de Computação , Humanos , Dedos/fisiologia , Eletromiografia/métodos , Masculino , Adulto , Feminino , Robótica/métodos , Adulto Jovem , Processamento de Sinais Assistido por Computador , Aprendizado Profundo
18.
IEEE Trans Biomed Eng ; PP2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38896507

RESUMO

OBJECTIVE: Hand impairment frequently occurs in individuals following a stroke. There is evidence of abnormal muscle co-activation that contributes to impaired control of finger independence. This study quantitatively analyzed hand muscle co-activation patterns of chronic stroke survivors. Systematically quantifying the degree of muscle co-activation patterns in stroke survivors can help us to better understand the mechanisms behind compromised finger independence and enables a more accurate assessment of hand impairment. METHODS: We analyzed muscle co-activation patterns both macroscopically and microscopically using high-density surface electromyographic (HD-sEMG) signals and decomposed motor unit signals from extrinsic and intrinsic flexor/extensor muscles. The muscle co-activation patterns between both sides of stroke survivors and neurologically intact controls were compared. RESULTS: We observed increased levels of co-activation in the affected sides of stroke survivors compared with their contralateral sides and the control groups, with a higher degree in the extrinsic muscles than the intrinsic muscles. The asymmetry in muscle co-activation between hands correlated with impaired finger force independence and clinical assessment scales. In the micro-level analysis of motor unit action potentials (MUAPs) distributions, we observed a notable increase in action potential spread of MUAPs in the individual affected extrinsic muscles, but the altered MUAP distribution did not correlate with clinical assessment scales. CONCLUSION: We systematically quantified abnormal muscle co-activation patterns in impaired finger independence after stroke. SIGNIFICANCE: With further development, the outcomes provide a comprehensive understanding of hand dexterity deficits in stroke survivors, which may provide guidance for targeted rehabilitation strategies and offer a potential for automated impairment evaluations.

19.
Am J Trop Med Hyg ; 110(2): 274-278, 2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38227961

RESUMO

Fonsecaea monophora is a species of Fonsecaea that belongs to Chaetothyriales. It is usually isolated from tropical and subtropical regions, causing reactive inflammation, skin abscesses, and pain. Cerebral infection caused by F. monophora is rare but often fatal. Diagnosing this disease at an early stage is difficult, and appropriate antifungal therapy is often delayed as a result. We report the case of a 53-year-old woman with type 2 diabetes who presented with a headache 2 months ago and progressive right-sided weakness of 1 month's duration. Magnetic resonance imaging revealed a space-occupying lesion in the left frontal lobe and corpus callosum. The cystic mass was removed by surgical intervention, and the identification of the sample based on sequencing of the internal transcribed spaced region in BLAST-N search showed that the sequences producing most significant alignments were F. monophora or similar (query cover 99%, E value 0.0, per ident 99.84). The patient was treated with a 3-month course of twice daily voriconazole, leading to complete recovery.


Assuntos
Feoifomicose Cerebral , Diabetes Mellitus Tipo 2 , Humanos , Feminino , Pessoa de Meia-Idade , Voriconazol/uso terapêutico , Antifúngicos/uso terapêutico , Feoifomicose Cerebral/diagnóstico por imagem , Feoifomicose Cerebral/tratamento farmacológico , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Imageamento por Ressonância Magnética
20.
Medicine (Baltimore) ; 103(2): e35722, 2024 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-38215110

RESUMO

OBJECTS: Human bladder cancer (BC) is the most common urogenital system malignancy. E2F transcription factors (E2Fs) have been reported to be involved in the growth of various cancers. However, the expression patterns, prognostic value and immune infiltration in the tumor microenvironment of the 8 E2Fs in BC have yet fully to be explored. METHODS AND STRATEGY: We investigated the differential expression of E2Fs in BC patients, the prognostic value and correlation with immune infiltration by analyzing a range of databases. RESULTS: We found that the mRNA expression levels of E2F1/2/3/4/5/7/8 were significantly higher in BC patients than that of control tissues. And the increased mRNA expression levels of all E2Fs were associated with tumor stage of BC. The survival analysis revealed that the elevated mRNA expression levels of E2F3/5/8 were significantly correlated with the overall survival (OS) of BC patients. And the genetic changes of E2Fs in BC patients were associated with shorter overall survival (OS) and progression-free survival (PFS). In addition, we revealed that the E2F3/5/8 expressions were closely correlated with tumor-infiltrating lymphocytes (TILs). CONCLUSIONS: E2F3/5/8 might serve as promising prognostic biomarkers and new therapeutic direction for BC patients.


Assuntos
Linfócitos do Interstício Tumoral , Neoplasias da Bexiga Urinária , Humanos , Prognóstico , Linfócitos do Interstício Tumoral/metabolismo , Neoplasias da Bexiga Urinária/genética , Neoplasias da Bexiga Urinária/patologia , RNA Mensageiro , Biomarcadores , Biomarcadores Tumorais/genética , Microambiente Tumoral , Fator de Transcrição E2F3/genética , Fator de Transcrição E2F3/metabolismo
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