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61.
Maitrot A Lucas MF Doncarli C Farina D 《Medical & biological engineering & computing》2005,43(4):487-492
In the study, an efficient method to perform supervised classification of surface electromyogram (EMG) signals is proposed.
The method is based on the choice of a relevant representation space and its optimisation with respect to a training set.
As EMG signals are the summation of compact-support waveforms (the motor unit action potentials), a natural tool for their
representation is the discrete dyadic wavelet transform. The feature space was thus built from the marginals of a discrete
wavelet decomposition. The mother wavelet was designed to minimise the probability of classification error estimated on the
learning set (supervised classification). As a representative example, the method was applied to simulate surface EMG signals
generated by motor units with different degrees of short-term synchronisation. The proposed approach was able to distinguish
surface EMG signals with degrees of synchronisation that differed by 10%, with a misclassification rate of 8%. The performance
of a spectral-based classification (error rate approximately 33%) and of the classification with Daubechies wavelet (21%)
was significantly poorer than with the proposed wavelet optimisation. The method can be used for a number of different application
fields of surface EMG classification, as the feature space is adapted to the characteristics of the signal that discriminate
between classes.
An erratum to this article is available at . 相似文献
62.
Chouvarda I Maglaveras N Boufidou A Mohlas S Louridas G 《Medical & biological engineering & computing》2003,41(6):609-617
Non-stationary analysis of electrocardiograms (ECGs) using Wigner-Ville distribution is presented. Analysis was performed
on subjects with acute myocardial infarction who had undergone thrombolysis, in Holter recordings of lead V1. The distinction
between successfully and non-successfully thrombolysed patients was evaluated, based on time-frequency features of the Wigner-Ville
transformed ECGs at the sixth hour after lysis. Characteristic parameters were extracted from time-frequency areas, and linear
discriminant analysis was performed on these parameters, leading to a prediction index to distinguish the two classes. Thirteen
features were found statistically significant by t-test and were used for the classification with linear modelling. Out of
these features, four corresponded to frequencies lower than 25 Hz and higher than 50 Hz for, roughly, the QRS complex, five
features corresponded to all the frequency bands of, roughly, the ST area, and the last four features corresponded to the
T-wave. The feature-vector used in linear modelling was iteratively generated, and the iterative prediction found all 18 features
significant. The iterative method resulted in better classification than that of the standard statistical procedure (3.8%
error against 18.1% with the classic method). The evolution of the prediction index with time for the first 12 h was different
for the successfully and non-successfully thrombolysed groups. Specifically, in the successful thrombolysis group, oscillations
and variation with time were more obvious, indicating a possible difference in the dynamics of the cardiac system. 相似文献
63.
Müller T Ball T Kristeva-Feige R Mergner T Timmer J 《Medical & biological engineering & computing》2000,38(1):62-67
The aim is to describe a general approach to determining important electrode positions when measured electro-encephalogram
signals are used for classification. The approach is exemplified in the frame of the brain-computer interface, which crucially
depends on the classification of different brain states. To classify two brain states, e.g. planning of movement of right
and left index fingers, three different approaches are compared: classification using a physiologically motivated set of four
electrodes, a set determined by principal component analysis and electrodes determined by spatial pattern analysis. Spatial
pattern analysis enhances the classification rate significantly from 61.3±1.8% (with four electrodes) to 71.8±1.4%, whereas
the classification rate using principal component analysis is significantly lower (65.2±1.4%). Most of the 61 electrodes used
have no influence on the classification rate, so that, in future experiments, the setup can be simplified drastically to six
to eight electrodes without loss of information. 相似文献
64.
Gaëlle Dzangué-Tchoupou Kuberaka Mariampillai Loïs Bolko Damien Amelin Wladimir Mauhin Aurélien Corneau Catherine Blanc Yves Allenbach Olivier Benveniste 《Autoimmunity reviews》2019,18(4):325-333
Background
Myositis is a heterogeneous group of muscular auto-immune diseases with clinical and pathological criteria that allow the classification of patients into different sub-groups. Inclusion body myositis is the most frequent myositis above fifty years of age. Diagnosing inclusion body myositis requires expertise and is challenging. Little is known concerning the pathogenic mechanisms of this disease in which conventional suppressive-immune therapies are inefficacious.Objectives
Our aim was to deepen our understanding of the immune mechanisms involved in inclusion body myositis and identify specific biomarkers.Methods
Using a panel of thirty-six markers and mass cytometry, we performed deep immune profiling of peripheral blood cells from inclusion body myositis patients and healthy donors, divided into two cohorts: test and validation cohorts. Potential biomarkers were compared to myositis controls (anti-Jo1-, anti-3-hydroxyl-3-methylglutaryl CoA reductase-, and anti-signal recognition particle-positive patients).Results
Unsupervised analyses revealed substantial changes only within CD8+ cells. We observed an increase in the frequency of CD8+ cells that expressed high levels of T-bet, and containing mainly both effector and terminally differentiated memory cells. The senescent marker CD57 was overexpressed in CD8+T-bet+ cells of inclusion body myositis patients. As expected, senescent CD8+T-bet+ CD57+ cells of both patients and healthy donors were CD28nullCD27nullCD127null. Surprisingly, non-senescent CD8+T-bet+ CD57- cells in inclusion body myositis patients expressed lower levels of CD28, CD27, and CD127, and expressed higher levels of CD38 and HLA-DR compared to healthy donors. Using classification and regression trees alongside receiver operating characteristics curves, we identified and validated a frequency of CD8+T-bet+ cells >51.5% as a diagnostic biomarker specific to inclusion body myositis, compared to myositis control patients, with a sensitivity of 94.4%, a specificity of 88.5%, and an area under the curve of 0.97.Conclusion
Using a panel of thirty-six markers by mass cytometry, we identify an activated cell population (CD8+T-bet+ CD57- CD28lowCD27lowCD127low CD38+ HLA-DR+) which could play a role in the physiopathology of inclusion body myositis, and identify CD8+T-bet+ cells as a predominant biomarker of this disease. 相似文献65.
股骨上端形态曲线的测量、参数化与统计分析 总被引:1,自引:1,他引:1
通过对84根完好的中国人成人股骨标本进行正位和侧位两个方向的X线摄影,得到股骨正、侧两方位的X光片。对X光片上股骨上端髓腔内侧形态进行描绘,将描绘好的图像输入计算机,由计算机进行图像预处理后提取其曲线形态数据,并将形态数据参数化,从而得到可比较的、能准确表现股骨形态的量化数据,为股骨形态的分类分析和系列型人工髋关节的参数设计打下基础。 相似文献
66.
Vijay Gayam Venu M. Konala Srikanth Naramala Pavani Reddy Garlapati Mohamed A. Merghani Nirajan Regmi Mamtha Balla Sreedhar Adapa 《Journal of medical virology》2020,92(10):2181-2187
Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is spreading at a rapid pace, and the World Health Organization declared it as pandemic on 11 March 2020. Mycoplasma pneumoniae is an "atypical" bacterial pathogen commonly known to cause respiratory illness in humans. The coinfection from SARS-CoV-2 and mycoplasma pneumonia is rarely reported in the literature to the best of our knowledge. We present a study in which 6 of 350 patients confirmed with COVID-19 were also diagnosed with M. pneumoniae infection. In this study, we described the clinical characteristics of patients with coinfection. Common symptoms at the onset of illness included fever (six [100%] patients); five (83.3%) patients had a cough, shortness of breath, and fatigue. The other symptoms were myalgia (66.6%), gastrointestinal symptoms (33.3%-50%), and altered mental status (16.7%). The laboratory parameters include lymphopenia, elevated erythrocyte sedimentation rate, C-reactive protein, lactate dehydrogenase, interleukin-6, serum ferritin, and D-dimer in all six (100%) patients. The chest X-ray at presentation showed bilateral infiltrates in all the patients (100%). We also described electrocardiogram findings, complications, and treatment during hospitalization in detail. One patient died during the hospital course. 相似文献
67.
Arámbula Cosío F Márquez Flores JA Padilla Castañeda MA Solano S Tato P 《Medical & biological engineering & computing》2005,43(5):672-677
An automatic colour image segmentation and cell counting software system has been developed for immunocytochemical analysis
of stained tissue samples. The system was designed to count the total number of positive and negative cells in tissue samples
treated with cytokine DNA probes from pigs naturally parasitised with Taenia solium metacestodes, using in situ hybridisation.
A reaction index was calculated as the ratio of the number of cells with a positive reaction to the total number of cells
(positives plus negatives) for each of five different probes. The objectives of automatic counting were to improve the reproducibility
of the analysis and reduce the processing time of large image batches. A fast KNN classifier was used for colour segmentation.
Watershed segmentation combined with edge detection was used to isolate individual cells that were then automatically labelled,
using the results of the corresponding colour segmented image. Validation was performed on 122 non-training digital images
with a total of 1069 positive cells and 1459 negative cells, with the following results: a mean true positive rate of 90.2%
for positive cells and a mean true positive rate of 85.4% for negative cells. The corresponding mean false positive rates
were 9.6% and 6.6%. The mean reaction index error of the automatic analysis was 5.35%. The processing of each digital image
took 10 s on a Pentium IV PC. 相似文献
68.
69.
Claes Lundsteen Beth Bjerregaard Erik Granum John Philip Kim Philip 《Clinical genetics》1980,17(3):183-190
70.
The prognosis of non small cell lung cancer (NSCLC) invading the diaphragm is poor, probably due to the richness of the lymphatic drainage of the diaphragm. The aim of this study was to determine mediastinal lymphatic efferents from the diaphragm. The diaphragms of 20 adult cadavers (77-104 years) were injected with a dye (modified Gerota's medium) to permit the lymph vessels to be catheterised and then dissected. Each stage of the dissection was described and photographed: 23 injections on the right and 25 on the left. Diaphragmatic lymph vessels passed to one of three lymph centres: posterior (paraaortic nodes, n = 16), anterior (juxtasternal nodes, n = 16) and mediastinal (visceral nodes, n = 16). From these lymph centres arose ascending lymph pathways: posteriorly to the thoracic duct (8/16), anteriorly along the internal thoracic vessels (10/16) and in the mediastinum to the peritracheobronchial nodes (6/10). Lymphatics from the diaphragm are abundant and drain towards mediastinal node lymph centres connecting to the blood stream via the thoracic duct. These lymph pathways are common with those of the pulmonary segments. Poor prognosis of NSCLC invading the diaphragm may be explained by the common lymphatic drainage of both the lung and diaphragm. 相似文献