[Correlation between pulmonary quantitative CT measurement indicators and respiratory symptoms in patients with chronic obstructive pulmonary disease in stable stage].

Objective: To explore the correlation between pulmonary quantitative CT measurement indicators and respiratory symptoms in patients with stable chronic obstructive pulmonary disease (COPD). Methods: A total of 186 patients with COPD in stable stage who visited in the outpatient department of Beijing Hospital from March 2021 to February 2022 were prospectively included. Demographic data, respiratory symptoms and lung function were collected. The original DICOM data of high-resolution CT (HRCT) were processed using the FACT medical imaging information system and the pulmonary emphysema index pixel index-950 (PI-950) and the airway wall thickness (4-6 T) and the percentage of airway area (4-6 WA%) of the 4-6 generation bronchi which represent the segmental and subsegmental bronchi were measured automatically. According to the modified British medical research council dyspnea scale (mMRC, 0-1 point for low score group, 2-4 points for high score group), chronic obstructive pulmonary disease assessment test (CAT, score<10 points for low score group,≥10 points for high score group), cough, expectoration and wheezing (asymptomatic group and symptomatic group), they were divided into two groups as dependent variables. The relationship between imaging parameters and the above symptoms was evaluated using a logistic regression model. Results: The study ultimately included 186 patients who met the inclusion criteria, including 162 males and 24 females, aged (68.9±9.3) years old. There were 83 patients in the high mMRC group, 120 patients in the high CAT group, 146 patients in the cough group, 154 patients in the expectoration group, and 65 patients in the wheezing group. The age and emphysema parameter PI-950 in the high score group of mMRC were higher than those in the low score group, while the percentage of the forced expiratory volume in 1 second (FEV1) predicted value (FEV1 pred) after medication, the percentage of carbon monoxide diffusion volume (DLCO) predicted value (DLCO pred), and the percentage of the maximum midexpiratory flow (MMEF) predicted value (MMEF pred) after medication were lower than those in the low score group (all P<0.05). The age of the high CAT group was higher than that of the low score group, while FEV1 pred and MMEF pred after medication were lower than those of the low score group (all P<0.05). The proportion of males, patients with smoking history, and smoking index in the cough group were higher than those in the non cough group, while the 4 WA% was lower than that in the non cough group (all P<0.05). The proportion of males, patients with smoking history, smoking index, and PI-950 in the expectoration group were higher than those in the non expectoration group, while FEV1 pred after medication and 4 WA% were lower than those in the non expectoration group (all P<0.05). The 5 WA% and 6 WA% of the wheezing group were higher than those of the non wheezing group, while MMEF pred after medication was lower than that of the non wheezing group (all P<0.05). Multivariate logistic regression analysis showed that after adjusting for demographic characteristics, smoking, combined diseases, lung function and other confounding factors, for every 10% increase in PI-950, the likelihood of developing more severe dyspnea for the patients (high score group according to mMRC) increased by 67.3% (OR=1.673, 95%CI: 1.052-2.658); Every 10% increase in 6WA% increased the likelihood of wheezing by 3.189 times (OR=4.189, 95%CI: 1.070-16.395). No correlation was found between various imaging indicators and cough, expectoration, and CAT scores (P>0.05). Conclusion: Quantitative CT measurement indicators in stable COPD patients can explain the presence and severity of respiratory symptoms, the pulmonary emphysema indicator is associated with dyspnea, and the percentage of proximal airway wall area is associated with wheezing.

[Prevalence, patterns and prognosis of multimorbidity among middle-aged and elderly inpatients with chronic obstructive pulmonary disease].

Objective: To explore the characteristics, patterns of multimorbidity and the impact on quality of life and the prognosis of middle-aged and elderly patients with chronic obstructive pulmonary disease (COPD). Methods: This is a cross-sectional study. From January 2012 to December 2021, 939 middle-aged and elderly COPD patients hospitalized in Beijing Hospital were selected by the convenient sampling method. The basic data of patients and the date of 16 common chronic diseases were collected. Patterns of multimorbidity were depicted by cluster analysis. Generalized linear regression model and logistic regression were used to evaluate the multimorbidity patterns and their prognosis. Results: At least one multimorbidity existed among 93.40% of COPD patients, and the median number of multimorbidity was 3. The top five multimorbidity among the patients were hypertension (57.93%, 544/939), coronary heart disease (33.76%,317/939), heart failure (31.95%,300/939), hyperlipidemia (31.63%,297/939) and arrhythmia (27.37%,257/939). Four multimorbidity patterns were identified, cardiometabolic and metabolic multimorbidity, kidney disease multimorbidity, respiratory-digestive-tumor multimorbidity and other multimorbidity. Cardiometabolic and metabolic multimorbidity was most common (590/939, 62.83%). Compared with non-cardiometabolic and metabolic multimorbidity, the incharge ADL score of patients with this multimorbidity decreased by 7 points (95%CI:-11.22- -3.34), Correspondingly, patients with kidney disease multimorbidity decreased by 14 points (95%CI:-24.12- -3.30) on the incharge score. The presence or absence of kidney disease multimorbidity had the greatest impact on discharge score, which was reduced by 12 points in comparison with patients without this multimorbidity (95%CI:-22.43- -2.40). ICU admission is mostly affected by the presence of cardiometabolic and metabolic multimorbidity (OR=2.44, 95%CI: 1.51-3.92) and kidney disease multimorbidity (OR=2.58, 95%CI: 1.01-6.60). The risk of death is the highest for cardiometabolic and metabolic multimorbidity (OR=2.24, 95%CI: 1.19-4.21). Conclusion: Multimorbidity is common in COPD patients. The most common pattern is cardiometabolic and metabolic multimorbidity. Cardiometabolic and metabolic multimorbidity and kidney disease multimorbidity significantly affect the quality of life and often associate with a poor prognosis.

[Progress on the mechanism and application of adipose-derived stem cells in promoting wound repair].

Chronic refractory wounds and scars caused by abnormal wound repair seriously damage the health of patients and affect their quality of life. At present, there is a lack of simple but effective and economical treatment methods. Adipose-derived stem cells (ASCs), as a kind of mesenchymal stem cells with multi-directional differentiation potential, have been confirmed by several in vivo and in vitro studies to promote wound healing by promoting epithelialization, angiogenesis, immunoregulation, antioxidant properties, and other mechanisms. ASCs and their derivatives have been used in the treatment of refractory wounds caused by burns, diabetic, and radiation injuries with good results achieved. Their potential to become new materials for wound repair has also been confirmed. This paper reviewed the mechanism and clinical application of ASCs in promoting wound repair, and looked into its research direction and prospects.

[Electronic cigarette use-associated lung injury: a case report and literature review].

Objective: To improve the clinical recognition of electronic cigarette or vaping product use-associated lung injury. Methods: A 67 year old patient with lung injury induced by e-cigarette was reported. The concentrations of vitamin E acetate (VEA) and tetrahydrocannabinol (Δ9-THC) in BALF were measured by UHPLC-MS/MS. A literature review was performed with"Vaping-Associated Lung Injury""vape","e-cigarette","electronic cigarette","EVALI","electronic nicotine device","lung","injury","case"as Mesh terms in PubMed. Results: There were 208 cases reported in the literature, 71.6% of whom were male, and 28.4% were female, with a median age of 27 years (17-67 years), while 2 patients (1%) were over 60 years old. The median time of using e-cigarette was 90 days (2 weeks-3 years). Of the 208 patients, the most common symptoms were dyspnea, fever, chest pain, hemoptysis, and gastrointestinal symptoms such as nausea, abdominal pain or diarrhea. The most common manifestation of chest CT was bilateral ground glass opacity (n=119, 57.2%). A total of 70 patients received bronchoscopy and BALF, which showed that the ratio of macrophages was (49.5±29.8)%, neutrophil (34.7±28.7)%, lymphocytes (10.1±7.4)%, and eosinophils (2.4±3.6)%. The "foamy" alveolar macrophages were positive in 65 cases (92.9%).A total of 132 patients (63.5%) were treated with antibiotics, and 162 patients (77.9%) were treated with glucocorticoids. The initial dose of methylprednisolone was 40 mg and the maximum was 500 mg. 48 patients (23.1%) were mechanically ventilated and 10 patients (4.8%) were treated with extracorporeal membrane oxygenation (ECMO). Of the 208 patients, 202(97.1%) patients improved and 6 (2.9%) died. Conclusion: Our case and reported cases should alert physicians to the clinical presentation of vaping-associated lung injury for early diagnosis and prompt management. It is suggested that the standardized management of e-cigarette should be strengthened to avoid similar situation of e-cigarette-related lung injury in China. Additional work is needed to characterize the pathophysiology of this disease.

[A prospective multi-center clinical investigation of HIV-negative pulmonary cryptococcosis in China].

Objective: To investigate the current status of the diagnosis and treatment of pulmonary cryptococcosis in respiratory medicine and improve the understanding of the clinical characteristics of HIV-negative pulmonary cryptococcosis in China. Methods: A prospective multi-center open cohort study was designed to screen for pulmonary cryptococcosis in the general wards and intensive care units of the Department of Respiratory Diseases in 22 hospitals. The HIV-negative patients with positive cryptococcal etiological diagnosis based on smear culture, antigen detection and histopathology were enrolled in the study. The clinical data of enrolled patients were collected and analyzed. Results: A total of 457 cases of pulmonary cryptococcosis were enrolled, among which 3.28% (15/457) were disseminated infections. The case fatality rate was 0.88% (4/457). The majority of the cases were diagnosed by histopathological examinations (74.40%, 340/457) and cryptococcus antigen detection (37.64%, 172/457). Patients with pulmonary cryptococcosis accounted for 2.04‰ (457/223 748) of the total hospitalized patients in the Department of Respiratory Diseases during the same period, and the ratio was the highest in south and east China. Meanwhile, 70.24% (321/457) of the patients had no underlying diseases, while 87.75% (401/457) were found to have immunocompetent status. Cough and expectoration were the most common clinical symptoms in patients with pulmonary cryptococcosis. However, 25.16% (115/457) of the patients had no clinical symptom or physical signs. In terms of imaging features on pulmonary CT, multiple pulmonary lesions were more common than isolated lesions, and there were more subpleural lesions than perihilar or medial lesions. Morphologically, most of the lesions were middle-sized nodules (1-5 cm) or small-sized nodules (3 mm to 1 cm). The sensitivity of serum cryptococcus antigen test was 71.99% (203/282). Moreover, antigen-positive patients differed from antigen-negative patients in terms of basic immune status, clinical symptoms, imaging features and infection types. Meanwhile, immunocompromised patients differed from immunocompetent patients in terms of clinical symptoms, physical signs, infection-related inflammation indicator levels, imaging features, serum cryptococcus antigen positive rate and prognosis. Conclusions: The majority of cases of HIV-negative pulmonary cryptococcosis in China had no underlying disease or immunocompromised status, and the overrall prognosis was favorable. However, early diagnosis of HIV-negative pulmonary cryptococcosis remains challenging due to the complicated manifestations of the disease.

[Experts consensus for the diagnosis, treatment, and prevention of coronavirus disease 2019 in the elderly].

Coronavirus disease 2019 (COVID-19) can cause great damage to the elderly patients and lead to high mortality. The clinical presentations and auxiliary examinations of the elderly patients with COVID-19 are atypical, due to the physiological ageing deterioration and basal pathological state. The treatment strategy for the elderly patients has its own characteristics and treatment protocol should be considered accordingly. To improve the diagnosis, treatment, and prevention of COVID-19 in the elderly, the Expert Committee of Geriatric Respiratory and Critical Care Medicine, China Society of Geriatrics established the "Expert consensus for the diagnosis, treatment, and prevention of coronavirus disease 2019 in the elderly" . We focused on the clinical characteristics and key points for better treatment and prevention of COVID-19 in the elderly. (1) For diagnosis, atypical clinical presentation of COVID-19 in the elderly should be emphasized, which may be complicated by underlying disease. (2) For treatment, strategy of multiple disciplinary team (mainly the respiratory and critical care medicine) should be adopted and multiple systemic functions should be considered. (3) For prevention, health care model about integrated management of acute and chronic diseases, in and out of hospital should be applied.

[Analysis of 12 cases of exogenous lipoid pneumonia confirmed by pathology].

Objective: To study the etiological, clinical, radiological, diagnostic, therapeutic, and prognostic manifestations of exogenous lipoid pneumonia (ELP), and therefore to improve the diagnosis and treatment of this disease. Methods: The clinical data of 12 cases of ELP confirmed by pathology were retrospectively analyzed. Results: The patients consisted of 9 males and 3 females, with an average age of 73.8 years (range, 44 to 100 years). The underlying diseases were variable, including diseases affecting the general condition (multiple organ failure, chronic heart and renal insufficiency, pemphigoid, etc) and conditions with increased risk of aspiration (sequelae of cerebrovascular disease, Alzheimer's disease, advanced stage of nasopharyngeal carcinoma, paralytic ileus, etc). The 12 cases were all caused by Inhalation of mineral oil. Common symptoms included cough, sputum production and dyspnea. ELP had no special physical signs. Inflammation indexes, such as white blood cell, neutrophil percentage, ESR, C reactive protein, procalcitonin, D-Dimer, and blood lipid levels were usually normal. Radiological features of ELP mainly included consolidation, mass or nodules, with a little ground-glass opacity. Some patients had ventilation and/or diffusion dysfunction. The diagnostic methods included CT-guided percutaneous lung biopsy, thoracoscopy, thoracotomy or autopsy. Histopathological findings showed accumulation of large foamy macrophages in the alveolar spaces, with a few lipid deposition and polykaryocytes. The main treatment of ELP was cessation of lipid material contact. One case died of ELP, 6 died of other coexisting diseases, and the rest 6 improved with treatment and were discharged. The survival patients were all stable during a follow-up of 2-4.5 years. Conclusions: ELP was rare and its clinical manifestation was atypical. Its radiological manifestations were indistinguishable from pneumonia, lung cancer, interstitial lung diseases, etc. Pathological examination was the gold standard for diagnosis, and the preferred means of sampling was bronchoscopy. In cases whose diagnosis could not be confirmed by BALF, CT-guided percutaneous lung biopsy might be considered. The most important treatment is cessation of lipid material contact. The prognosis is good.

[Value of forced expiratory volume in 6 seconds (FEV(6)) in the evaluation of pulmonary function in Chinese elderly males].

Objective: To evaluate the value of forced expiratory volume in 6 seconds (FEV(6)) in the evaluation of pulmonary function in Chinese elderly males. Methods: Pulmonary function tests of elderly who had received regular physical examination in Beijing Hospital from July 2003 to April 2015 were analyzed on subjects with the following characteristics: aged 60 years or older, completion of bronchial dilation test and able to exhale for at least six seconds. The included subjects were divided into 2 groups: 60-<80 years group and ≥80 years group. The association of FEV(6) with forced vital capacity (FVC), FEV(1)/FEV(6) with FEV(1)/FVC, the diagnostic efficiency and influencing factor of FEV(6) and FEV(1)/FEV(6) were analyzed; the value of FEV(6) in the evaluation of pulmonary function in the study population was evaluated. Results: A total of 475 elderly men aged 60 years or older were enrolled, with a mean age of (77.13±9.53) years. Totally there were 269 subjects in 60-<80 years group, which accounted for 56.6%; 206 subjects were in ≥80 years group, which accounted for 43.4%. There were 292 subjects with irreversible airflow obstruction, accounting for 61.5%. In all the included subjects, FEV(6) was significantly correlated with FVC and post-bronchodilator FEV(1)/FEV(6) was significantly correlated with post-bronchodilator FEV(1)/FVC(r=0.971, 0.978; both P<0.001), which were similar in 60-<80 years group and ≥80 years group (r=0.967, 0.974 and r=0.955, 0.967; all P<0.001). FEV(1)/FEV(6) showed excellent accuracy in diagnosing airflow obstruction[area under curve (AUC)=0.990(95%CI: 0.983-0.996); P<0.001]. Using FEV(1)/FVC<0.70 as a reference, FEV(1)/FEV(6)<0.73 had the best sensitivity (0.952) and specificity (0.945), and there was excellent agreement between the two diagnostic cutoffs (κ=0.891; P<0.001). When difference between before and after bronchial dilation test was analyzed, no correlation was observed between FEV(6) improvement and the improvement of forced expiratory time (r=0.089; P=0.053), but FVC improvement was significantly correlated with the improvement of forced expiratory time (r=0.460; P<0.001). Similar results were also found in subjects with irreversible airflow obstruction. Subjects with FEV(1)/FEV(6)≥0.70 and FEV(1)/FVC<0.70 were categorized as pulmonary function middle group, a total of 73 cases, which included 20 cases ≥80 years old. The proportion of middle group among ≥80 years group was significantly less than that of the 60-<80 years group (χ(2)=8.958; P=0.003). In pulmonary function middle group, FEV(1)/FEV(6) or FEV(1)/FVC had no correlation with inspiratory capacity or residual volume/total lung capacity (all P>0.05). Conclusions: FEV(6) and FEV(1)/FEV(6) are strongly correlated with FVC and FEV(1)/FVC, and there is excellent agreement between FEV(1)/FEV(6) and FEV(1)/FVC. FEV(6) is simple, easy to operate and with less influencing factors, which can be used as a valid alternative for FVC in diagnosing airflow obstruction in elderly males.

[Study of the clinical phenotype of symptomatic chronic airways disease by hierarchical cluster analysis and two-step cluster analyses].

OBJECTIVE: To study the distinct clinical phenotype of chronic airway diseases by hierarchical cluster analysis and two-step cluster analysis. METHODS: A population sample of adult patients in Donghuamen community, Dongcheng district and Qinghe community, Haidian district, Beijing from April 2012 to January 2015, who had wheeze within the last 12 months, underwent detailed investigation, including a clinical questionnaire, pulmonary function tests, total serum IgE levels, blood eosinophil level and a peak flow diary. Nine variables were chosen as evaluating parameters, including pre-salbutamol forced expired volume in one second(FEV1)/forced vital capacity(FVC) ratio, pre-salbutamol FEV1, percentage of post-salbutamol change in FEV1, residual capacity, diffusing capacity of the lung for carbon monoxide/alveolar volume adjusted for haemoglobin level, peak expiratory flow(PEF) variability, serum IgE level, cumulative tobacco cigarette consumption (pack-years) and respiratory symptoms (cough and expectoration). Subjects' different clinical phenotype by hierarchical cluster analysis and two-step cluster analysis was identified. RESULTS: (1) Four clusters were identified by hierarchical cluster analysis. Cluster 1 was chronic bronchitis in smokers with normal pulmonary function. Cluster 2 was chronic bronchitis or mild chronic obstructive pulmonary disease (COPD) patients with mild airflow limitation. Cluster 3 included COPD patients with heavy smoking, poor quality of life and severe airflow limitation. Cluster 4 recognized atopic patients with mild airflow limitation, elevated serum IgE and clinical features of asthma. Significant differences were revealed regarding pre-salbutamol FEV1/FVC%, pre-salbutamol FEV1% pred, post-salbutamol change in FEV1%, maximal mid-expiratory flow curve(MMEF)% pred, carbon monoxide diffusing capacity per liter of alveolar(DLCO)/(VA)% pred, residual volume(RV)% pred, total serum IgE level, smoking history (pack-years), St.George's respiratory questionnaire(SGRQ) score, acute exacerbation in the past one year, PEF variability and allergic dermatitis (P<0.05). (2) Four clusters were also identified by two-step cluster analysis as followings, cluster 1, COPD patients with moderate to severe airflow limitation; cluster 2, asthma and COPD patients with heavy smoking, airflow limitation and increased airways reversibility; cluster 3, patients having less smoking and normal pulmonary function with wheezing but no chronic cough; cluster 4, chronic bronchitis patients with normal pulmonary function and chronic cough. Significant differences were revealed regarding gender distribution, respiratory symptoms, pre-salbutamol FEV1/FVC%, pre-salbutamol FEV1% pred, post-salbutamol change in FEV1%, MMEF% pred, DLCO/VA% pred, RV% pred, PEF variability, total serum IgE level, cumulative tobacco cigarette consumption (pack-years), and SGRQ score (P<0.05). CONCLUSION: By different cluster analyses, distinct clinical phenotypes of chronic airway diseases are identified. Thus, individualized treatments may guide doctors to provide based on different phenotypes.

Clinical research on dendritic cell vaccines to prevent postoperative recurrence and metastasis of liver cancer.

We aimed to evaluate dendritic cell (DC) tumor vaccines for preventing liver cancer recurrence and metastasis. DCs were induced from mononuclear cells in the peripheral blood with recombinant human granulocyte macrophage colony stimulating factor (rhGM-CSF) and recombinant human interleukin 4 (rhIL-4), followed by sensitization with lysis of autologous liver cancer cells. One hundred and sixty patients with hepatocellular carcinoma were randomly divided into two groups of 80. One group was treated postoperatively with six cycles of the DC tumor vaccine. The other group was treated postoperatively with six cycles of FOLFOX 6, beginning 1 week after surgery. After treatment with DC tumor vaccines, the levels of CD3+, CD4+, and CD8+, the ratio of CD4+ to CD8+ DC, and the serum levels of IL-12 and IFN-γ were significantly increased both in comparison to the pre-treatment levels (P < 0.001) and to the chemotherapy group (P < 0.001). After a postoperative follow-up of 18 months, the metastatic recurrence rate in the DC tumor vaccine group was significantly lower than that in the chemotherapy group (17.50 vs 48.75%, P < 0.005), and the survival rate of the patients in the DC tumor vaccine group was higher than that of the chemotherapy treatment group (86.25 vs 52.50%, P < 0.005). Treatment with DC tumor vaccines was safe and feasible. It can enhance the immunity of the patients, reduce the rates of metastasis and recurrence, and improve survival rates. This is a promising treatment for the prevention of postoperative recurrence in patients with liver cancer.

CpG ODN 1826 enhances radiosensitivity of the human lung cancer cell line A549 in a rat model.

This study investigated the effects of CpG ODN1826 plus radiotherapy (RT) on tumor growth and angiogenesis of subcutaneous tumor in a rat model. Four treatment groups were tested in which rats were injected with 100 µL CpG ODN1826 (1 µg/µL) or 100 µL vehicle, with and without exposure to 8 Gy after 2 h. At 7 days after inoculation of lung cancer cells, drugs were injected in the tumor and radiation was administered over 5 days, after which the rate of tumor inhibition was calculated. Expression of VEGF-C in tumor tissue was seen in 10, 50, 80, and 100% of tumors in the CpG ODN1826 + RT, CpG ODN1826, vehicle + RT, and vehicle alone groups, respectively, while positive expression of NRP-1 was seen in 10, 40, 90, and 100% of tumors. The decreases in expression of VEGF-C mRNA in the CpG ODN1826 + RT and CpG ODN1826 groups compared with the NS + RT and NS groups were significant (P < 0.01), as were the decreases in NRP-1 mRNA in the CpG ODN1826 + RT group compared with the CpG ODN1826 group (P < 0.01). Thus, CpG ODN1826 can significantly inhibit tumor growth in a rat model, the mechanism of which may be related to inhibition of the expression of VEGF-C and NRP-1, which have an inhibitory effect on angiogenesis.

Analysis of motor unit firing patterns in patients with central or peripheral lesions using singular-value decomposition.

We applied the singular value decomposition (SVD) method to study single motor unit firing patterns. Two projects were carried out: (1) a computer simulation study to confirm the meanings of two SVD parameters, the eigenvalue corresponding to the positive-slope eigenvector (PEV) and that corresponding to the negative-slope eigenvector (NEV); and (2) a clinical study for which electromyographic (EMG) recordings were made from first dorsal interosseous muscle in patients with stroke, myopathies, or neuropathies and in healthy control subjects. Results of computer simulation reveal that the NEV reflects the amount of instantaneous firing variability, whereas the PEV/NEV (P/N) ratio exhibits the relative effect of a trend in the firing pattern. In human studies, the P/N ratio of stroke patients was significantly higher than that of the controls, whereas their NEV was comparable. By contrast, in the myopathy and neuropathy groups, the NEV increased significantly, whereas the P/N ratio did not. These results suggest that the SVD method decomposes the motor unit (MU) firing variation into two components and that the mechanism for increased firing variability is different for supraspinal and spinal-infraspinal lesions.

Multielectrode surface EMG for noninvasive estimation of motor unit size.

To noninvasively estimate the motor unit size, we present a novel surface electromyographic (EMG) measurement system consisting of a surface multielectrode with four-pin electrodes and a pair of surface-disk electrodes. Surface motor unit action potentials (MUAPs) were recorded with the multielectrode, in the so-called multielectrode surface EMG (MSEMG), which was spatially filtered to localize the sensing area and reduce the noise. In addition, a modified decomposition algorithm, considering the geometrical configuration of the multielectrode, was designed to identify the individual MUAPs in the measured MSEMG. The identified MUAP was subsequently used as the triggering source for the EMG signals recorded by the surface-disk electrodes. From a pool of 34 subjects with neuromuscular diseases and 14 normal subjects, the median amplitudes of surface-disk EMG after spike-triggered averaging, called MSEMG-MUAP, correlated well (r = 0.82, P < 0.0001) with those of macro EMG. Moreover, the MSEMG-MUAP recording during a ramp force contraction exhibited the common size principle phenomenon during motor unit recruitment. The results of this study demonstrate that the MSEMG-MUAP measurement is a feasible approach for estimating the motor unit size from the skin surface.

Spatio-temporal representation of multichannel EMG firing patterns and its clinical applications.

Analyzing motor unit (MU) activity is essential for studying the neurological dysfunction of upper motor neuron disorders (UMND). This study employs multichannel surface electromyographic (EMG) signals, as recorded from the upper arm during elbow flexion and extension, to analyze the temporal changes and spatial distribution of the dominant firing rate. To estimate the dominant firing rate, the autoregressive (AR) spectrum analysis method is utilized to detect the peaks and poles of the AR model, of the surface EMG spectrum below 40 Hz. The temporal changes in firing rates are also observed by using the spectrogram representation of low-frequency EMG spectra. The EMG spectrogram facilitates examination of the time-varying characteristics of firing rates and recruitment of MUs from surface EMG signal. The low-frequency spectra of multichannel EMG are then represented in a polar form to visualize the spatial distribution of firing patterns across muscles. Via spatio-temporal representation techniques, this study provides a viable approach of observing both the spatial and temporal patterns of MU activities in normal subjects and patients with UMND, including cerebrovascular disease and Parkinson's disease.

Effect of body position on isometric arm lifting strength.

The purpose of this study was to examine the influence of three different body positions on isometric arm lifting strength. Thirty students aged between 20 and 27 years volunteered as subjects for the study. A force Evaluation and Testing System (FET 5000) was used to measure the arm lifting strength in the supine, sitting, and standing positions. Average force of each body position was determined by the mean of two trials. At the same time, electromyographic activity of bilateral biceps brachii muscles was measured during maximal voluntary isometric arm lifting. Repeated measures analysis of variance was used to analyze the effects of body positions on the amount of average force value and integrated electromyographic (IEMG) values during isometric arm lifting. The results showed that the highest mean lifting strength was recorded in the sitting position for both males and females. Significant difference in arm lifting strength was found between each body position. Differences in force were elicited more easily between the female and male subjects. However, the average IEMG values were not significantly correlated with the force produced in arm lifting. Nevertheless, this study supports the conclusion that body position did influence the production of isometric elbow flexors strength. We conclude, therefore, that body position must be considered during rehabilitation of upper extremities.