An Ultrasound Imaging Based Observer for Estimating NMES-Induced Muscle Fatigue: Theory and Simulation

2020 ◽  
Author(s):  
Zhiyu Sheng ◽  
Kang Kim ◽  
Nitin Sharma
Keyword(s):  
Muscle Fatigue ◽  
Neuromuscular Electrical Stimulation ◽  
Principal Component Regression ◽  
Force Production ◽  
Principal Component ◽  
Skeletal Muscle Function ◽  
Intermittent Feedback ◽  
Recorded Data ◽  
Muscle Force Production ◽  
Neuroprosthetic Devices

Abstract Neuroprosthetic devices that use transcutaneous neuromuscular electrical stimulation (NMES) are potential interventions to restore skeletal muscle function in people with neurological disorders. As commonly noted, how to assess the NMES-induced muscle fatigue is a critical problem. This is because the capability of fatigue assessment is a necessary precursor for optimally modulating the NMES dosage to improve the control performance of a neuroprosthesis and ensure user’s safety. To effectively estimate the NMES-induced muscle fatigue, this paper proposes a novel state observer that combines a mathematical predictive fatigue model and intermittent feedback from ultrasound-derived strain images. The strain images quantify muscle contractility during NMES. Principal component regression (PCR) is used to derive a relationship between the strain images and instantaneous muscle force production. Lyapunov stability analysis was performed to obtain the convergence property of the designed observer. A globally uniformly ultimately bounded (GUUB) result was obtained. Simulations based on pre-recorded data from a human experiment were also conducted to demonstrate the performance of the designed observer.

Acute effects of hydrogen peroxide on skeletal muscle microvascular oxygenation from rest to contractions

2011 ◽  
Vol 110 (5) ◽  
pp. 1290-1298 ◽  
Author(s):  
Daniel M. Hirai ◽  
Steven W. Copp ◽  
Peter J. Schwagerl ◽  
Timothy I. Musch ◽  
David C. Poole
Keyword(s):  
Skeletal Muscle ◽  
Hydrogen Peroxide ◽  
Muscle Function ◽  
Force Production ◽  
Sprague Dawley ◽  
Skeletal Muscle Function ◽  
Mean Response Time ◽  
Sprague Dawley Rats ◽  
Muscle Force Production ◽  
Microvascular Oxygenation

Reactive oxygen species, such as hydrogen peroxide (H2O2), exert a critical regulatory role on skeletal muscle function. Whether acute increases in H2O2 modulate muscle microvascular O2 delivery-utilization (Q̇o2/V̇o2) matching [i.e., microvascular partial pressure of O2 (PmvO2)] at rest and following the onset of contractions is unknown. The hypothesis was tested that H2O2 treatment (exogenous H2O2) would enhance PmvO2 and slow PmvO2 kinetics during contractions compared with control. Anesthetized, healthy young Sprague-Dawley rats had their spinotrapezius muscles either exposed for measurement of blood flow (and therefore Q̇o2), V̇o2, and PmvO2, or exteriorized for measurement of force production. Electrically stimulated twitch contractions (1 Hz, ∼7 V, 2-ms pulse duration, 3 min) were evoked following acute superfusion with Krebs-Henseleit (control) and H2O2 (100 μM). Relative to control, H2O2 treatment elicited disproportionate increases in Q̇o2 and V̇o2 that elevated PmvO2 at rest and throughout contractions and slowed overall PmvO2 kinetics (i.e., ∼85% slower mean response time; P < 0.05). Accordingly, H2O2 resulted in ∼33% greater overall PmvO2, as assessed by the area under the PmvO2 curve ( P < 0.05). Muscle force production was not altered with H2O2 treatment ( P > 0.05), evidencing reduced economy during contractions (∼40% decrease in the force/V̇o2 relationship; P < 0.05). These findings indicate that, although increasing the driving force for blood-myocyte O2 flux (i.e., PmvO2), transient elevations in H2O2 impair skeletal muscle function (i.e., reduced economy during contractions), which mechanistically may underlie, in part, the reduced exercise tolerance in conditions associated with oxidative stress.

Low-Frequency Fatigue in Isolated Skeletal Muscles and the Effects of Methylxanthines

1982 ◽  
Vol 63 (2) ◽  
pp. 161-167 ◽  
Author(s):  
D. A. Jones ◽  
S. Howell ◽  
C. Roussos ◽  
R. H. T. Edwards
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fatigue ◽  
Contractile Activity ◽  
Effective Means ◽  
Low Frequency ◽  
Force Production ◽  
Human Muscle ◽  
Low Frequencies ◽  
Skeletal Muscle Fatigue ◽  
Muscle Force Production

1. A form of skeletal muscle fatigue was examined with isolated animal and human muscle preparations. The possibility that methylxanthines could overcome this was investigated. 2. Prolonged contractile activity resulted in a long-lasting impairment of force generation at low frequencies of stimulation at times when the force at higher frequencies had substantially recovered. This was seen with both fast-twitch and slow-twitch animal muscles and with samples of isolated human muscle. 3. The decrease in low-frequency force was due to a decrease in twitch amplitude, suggesting damage to the processes involved in excitation-contraction coupling. 4. Caffeine and theophylline at concentrations of 1 mmol/l rapidly and completely reversed the effects of this form of fatigue in both animal and human muscle preparations. 5. Agents that potentiate muscle force production could be an effective means of counteracting the effects of an important form of skeletal muscle fatigue, but a clinically useful compound would need to be more potent than the methylxanthines currently in use.

Pemanfaatan CFSRv2 untuk Statistical Downscaling menggunakan Principal Component Regression dan Partial Least Square

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Khairunnisa Khairunnisa ◽  
Rizka Pitri ◽  
Victor P Butar-Butar ◽  
Agus M Soleh
Keyword(s):  
Statistical Downscaling ◽  
General Circulation ◽  
Principal Component Regression ◽  
Circulation Model ◽  
Principal Component ◽  
Meteorological Station ◽  
Grid Size ◽  
Partial Least Square ◽  
Least Square ◽  
Output Data

This research used CFSRv2 data as output data general circulation model. CFSRv2 involves some variables data with high correlation, so in this research is using principal component regression (PCR) and partial least square (PLS) to solve the multicollinearity occurring in CFSRv2 data. This research aims to determine the best model between PCR and PLS to estimate rainfall at Bandung geophysical station, Bogor climatology station, Citeko meteorological station, and Jatiwangi meteorological station by comparing RMSEP value and correlation value. Size used was 3×3, 4×4, 5×5, 6×6, 7×7, 8×8, 9×9, and 11×11 that was located between (-40) N - (-90) S and 1050 E -1100 E with a grid size of 0.5×0.5 The PLS model was the best model used in stastistical downscaling in this research than PCR model because of the PLS model obtained the lower RMSEP value and the higher correlation value. The best domain and RMSEP value for Bandung geophysical station, Bogor climatology station, Citeko meteorological station, and Jatiwangi meteorological station is 9 × 9 with 100.06, 6 × 6 with 194.3, 8 × 8 with 117.6, and 6 × 6 with 108.2, respectively.

scholarly journals Application of Derivative, Derivative Ratio, and Multivariate Spectral Analysis and Thin-Layer Chomatography-Densitometry for Determination of a Ternary Mixture Containing Drotaverine Hydrochloride, Caffeine, and Paracetamol

2007 ◽  
Vol 90 (2) ◽  
pp. 391-404 ◽  
Author(s):  
Fadia H Metwally ◽  
Yasser S El-Saharty ◽  
Mohamed Refaat ◽  
Sonia Z El-Khateeb
Keyword(s):  
Thin Layer ◽  
Least Squares ◽  
Ternary Mixture ◽  
Principal Component Regression ◽  
Pharmaceutical Preparations ◽  
Principal Component ◽  
Standard Addition ◽  
Drotaverine Hydrochloride ◽  
Assay Precision

Abstract New selective, precise, and accurate methods are described for the determination of a ternary mixture containing drotaverine hydrochloride (I), caffeine (II), and paracetamol (III). The first method uses the first (D1) and third (D3) derivative spectrophotometry at 331 and 315 nm for the determination of (I) and (III), respectively, without interference from (II). The second method depends on the simultaneous use of the first derivative of the ratio spectra (DD1) with measurement at 312.4 nm for determination of (I) using the spectrum of 40 μg/mL (III) as a divisor or measurement at 286.4 and 304 nm after using the spectrum of 4 μg/mL (I) as a divisor for the determination of (II) and (III), respectively. In the third method, the predictive abilities of the classical least-squares, principal component regression, and partial least-squares were examined for the simultaneous determination of the ternary mixture. The last method depends on thin-layer chromatography-densitometry after separation of the mixture on silica gel plates using ethyl acetatechloroformmethanol (16 + 3 + 1, v/v/v) as the mobile phase. The spots were scanned at 281, 272, and 248 nm for the determination of (I), (II), and (III), respectively. Regression analysis showed good correlation in the selected ranges with excellent percentage recoveries. The chemical variables affecting the analytical performance of the methodology were studied and optimized. The methods showed no significant interferences from excipients. Intraday and interday assay precision and accuracy values were within regulatory limits. The suggested procedures were checked using laboratory-prepared mixtures and were successfully applied for the analysis of their pharmaceutical preparations. The validity of the proposed methods was further assessed by applying a standard addition technique. The results obtained by applying the proposed methods were statistically analyzed and compared with those obtained by the manufacturer's method.

scholarly journals Principal component regression in GAMLSS applied to Greek–German government bond yield spreads

2021 ◽  
pp. 1471082X2110229
Author(s):  
D. Stasinopoulos Mikis ◽  
A. Rigby Robert ◽  
Georgikopoulos Nikolaos ◽  
De Bastiani Fernanda
Keyword(s):  
Additive Model ◽  
Principal Component Regression ◽  
Principal Component ◽  
Complex Nature ◽  
Government Bond ◽  
German Government ◽  
Yield Spreads ◽  
Explanatory Variables ◽  
Interaction Terms ◽  
Bond Yield

A solution to the problem of having to deal with a large number of interrelated explanatory variables within a generalized additive model for location, scale and shape (GAMLSS) is given here using as an example the Greek–German government bond yield spreads from 25 April 2005 to 31 March 2010. Those were turbulent financial years, and in order to capture the spreads behaviour, a model has to be able to deal with the complex nature of the financial indicators used to predict the spreads. Fitting a model, using principal components regression of both main and first order interaction terms, for all the parameters of the assumed distribution of the response variable seems to produce promising results.

scholarly journals Full spectrum and genetic algorithm-selected spectrum-based chemometric methods for simultaneous determination of azilsartan medoxomil, chlorthalidone, and azilsartan: Development, validation, and application on commercial dosage form

2021 ◽  
Vol 19 (1) ◽  
pp. 205-213
Author(s):  
Hany W. Darwish ◽  
Abdulrahman A. Al Majed ◽  
Ibrahim A. Al-Suwaidan ◽  
Ibrahim A. Darwish ◽  
Ahmed H. Bakheit ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Simultaneous Determination ◽  
Predictive Power ◽  
Principal Component Regression ◽  
Selection Procedure ◽  
Principal Component ◽  
Chemometric Methods ◽  
Full Spectrum ◽  
Azilsartan Medoxomil

Abstract Five various chemometric methods were established for the simultaneous determination of azilsartan medoxomil (AZM) and chlorthalidone in the presence of azilsartan which is the core impurity of AZM. The full spectrum-based chemometric techniques, namely partial least squares (PLS), principal component regression, and artificial neural networks (ANN), were among the applied methods. Besides, the ANN and PLS were the other two methods that were extended by genetic algorithm procedure (GA-PLS and GA-ANN) as a wavelength selection procedure. The models were developed by applying a multilevel multifactor experimental design. The predictive power of the suggested models was evaluated through a validation set containing nine mixtures with different ratios of the three analytes. For the analysis of Edarbyclor® tablets, all the proposed procedures were applied and the best results were achieved in the case of ANN, GA-ANN, and GA-PLS methods. The findings of the three methods were revealed as the quantitative tool for the analysis of the three components without any intrusion from the co-formulated excipient and without prior separation procedures. Moreover, the GA impact on strengthening the predictive power of ANN- and PLS-based models was also highlighted.

scholarly journals Fourteen days of smoking cessation improves muscle fatigue resistance and reverses markers of systemic inflammation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Z. Darabseh ◽  
Thomas M. Maden-Wilkinson ◽  
George Welbourne ◽  
Rob C. I. Wüst ◽  
Nessar Ahmed ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Skeletal Muscle ◽  
Smoking Cessation ◽  
Muscle Fatigue ◽  
Fatigue Resistance ◽  
Systemic Inflammation ◽  
Muscle Function ◽  
Low Grade ◽  
Skeletal Muscle Function ◽  
Tnf Α

AbstractCigarette smoking has a negative effect on respiratory and skeletal muscle function and is a risk factor for various chronic diseases. To assess the effects of 14 days of smoking cessation on respiratory and skeletal muscle function, markers of inflammation and oxidative stress in humans. Spirometry, skeletal muscle function, circulating carboxyhaemoglobin levels, advanced glycation end products (AGEs), markers of oxidative stress and serum cytokines were measured in 38 non-smokers, and in 48 cigarette smokers at baseline and after 14 days of smoking cessation. Peak expiratory flow (p = 0.004) and forced expiratory volume in 1 s/forced vital capacity (p = 0.037) were lower in smokers compared to non-smokers but did not change significantly after smoking cessation. Smoking cessation increased skeletal muscle fatigue resistance (p < 0.001). Haemoglobin content, haematocrit, carboxyhaemoglobin, total AGEs, malondialdehyde, TNF-α, IL-2, IL-4, IL-6 and IL-10 (p < 0.05) levels were higher, and total antioxidant status (TAS), IL-12p70 and eosinophil numbers were lower (p < 0.05) in smokers. IL-4, IL-6, IL-10 and IL-12p70 had returned towards levels seen in non-smokers after 14 days smoking cessation (p < 0.05), and IL-2 and TNF-α showed a similar pattern but had not yet fully returned to levels seen in non-smokers. Haemoglobin, haematocrit, eosinophil count, AGEs, MDA and TAS did not significantly change with smoking cessation. Two weeks of smoking cessation was accompanied with an improved muscle fatigue resistance and a reduction in low-grade systemic inflammation in smokers.

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