Quadriceps strength assessed by magnetic stimulation of femoral nerve in patients with chronic obstructive pulmonary disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Skeletal muscle dysfunction is one of important systemic manifestations of chronic obstructive pulmonary disease (COPD) and is associated with mortality in patients with COPD, thus quantifying its strength is of great clinical interest and of particular value. Quadriceps maximal volitional contraction (MVC) is often used for the routine measurements of this muscle's strength; while twitch tension (TwQ) evoked by magnetic stimulation of the femoral nerve has been employed for measurement of quadriceps strength non-volitionally. We aimed to investigate the prevalence and severity of skeletal muscle dysfunction in COPD patients by measurement of quadriceps strength with volitional and non-volitional techniques, and to probe into some methodological issues.</p><p><b>METHODS</b>We recruited 71 COPD patients and 60 control subjects. Quadriceps strength was measured with both maximality of TwQ and MVC force. The reproducibility for TwQ and MVC was investigated using within-occasion variability from three repeated maneuvers.</p><p><b>RESULTS</b>Maximal TwQ was achieved in 121 participants at a mean of 90% of the stimulator's maximum output. The mean maximality of TwQ was decrease by about 44% - 47% in COPD patients as compared with controls (P < 0.05), so was MVC. There was a significant correlation between quadriceps TwQ and MVC, and the mean ratio of TwQ/MVC was 0.29 in controls and 0.33 in patients. The coefficient of variation showed that TwQ yielded lower within-occasion variability than MVC in both groups.</p><p><b>CONCLUSIONS</b>Quadriceps strength is commonly and substantially impaired in patients with COPD, in terms of MVC as well as TwQ. The magnetic stimulation of the femoral nerve presents a higher reproducibility and is a better technique for measurement of quadriceps strength for the general population, especially for those who are too unwell to perform a full MVC; while it may not be applied to subjects who are over-weighted.</p>

Expressions of tumor necrosis factor-converting enzyme and ErbB3 in rats with chronic obstructive pulmonary disease / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Chronic obstructive pulmonary disease (COPD) is associated not only with airway inflammation characterized by mucin hypersecretion but also with systemic inflammation. Tumor necrosis factor alpha (TNF-alpha) is found to take part in systemic inflammation, and ErbB3 plays an important role in mucin hypersecretion of COPD. Since TNF-alpha converting enzyme (TACE) is involved in the activation of both TNF-alpha and ErbB3, we established rat models of COPD to investigate the expressions of TACE, TNF-alpha and ErbB3 and to explore the correlations among TACE, TNF-alpha and ErbB3 respectively.</p><p><b>METHODS</b>Thirty Wistar male rats were randomly divided into COPD group (group C, n = 10), saline solution parallel group (group P, n = 8), and normal control group (group N, n = 8). Group C was challenged with passive cigarette smoking and intratracheal instillation of lipopolysaccharide. Six weeks later pulmonary functions were tested, bronchoalveolar fluid and arterial blood gases were assayed, and histopathological evaluations were performed in turn. The expressions of TACE, TNF-alpha and ErbB3 in lungs of all rats were determined histochemically.</p><p><b>RESULTS</b>The expressions of TACE, TNF-alpha and ErbB3 were significantly higher in group C than in group N (P < 0.01). The contents of TNF-alpha in serum (P < 0.01) and bronchoalveolar lavage fluid (BALF) (P < 0.01) were elevated more significantly in group C than in group N. A positive correlation existed between TACE and TNF-alpha (r = 0.784, P < 0.01) and between TACE and ErbB3 (r = 0.526, P < 0.01) respectively.</p><p><b>CONCLUSIONS</b>TNF-alpha and ErbB3 are involved in the pathogenesis of COPD. TACE contributes to the progress of COPD indirectly through the function of TNF-alpha and ErbB3.</p>