Relationship between work rate and oxygen uptake in mitochondrial myopathy during ramp-incremental exercise

We determined the response characteristics and functional correlates of the dynamic relationship between the rate (Δ) of oxygen consumption ( O2) and the applied power output (work rate = WR) during ramp-incremental exercise in patients with mitochondrial myopathy (MM). Fourteen patients (7 males, age 35.4 ± 10.8 years) with biopsy-proven MM and 10 sedentary controls (6 males, age 29.0 ± 7.8 years) took a ramp-incremental cycle ergometer test for the determination of the O2 on-exercise mean response time (MRT) and the gas exchange threshold (GET). The ΔO2/ΔWR slope was calculated up to GET (S1), above GET (S2) and over the entire linear portion of the response (S T). Knee muscle endurance was measured by isokinetic dynamometry. As expected, peak O2 and muscle performance were lower in patients than controls (P O2/ΔWR than controls, especially the S2 component (6.8 ± 1.5 vs 10.3 ± 0.6 mL·min-1·W-1, respectively; P O2/ΔWR (S T) and muscle endurance, MRT-O2, GET and peak O2 in MM patients (P O2/ΔWR below 8 mL·min-1·W-1 had severely reduced peak O2 values (O2) had lower ΔO2/ΔWR (P O2/ΔWR) is typically reduced in patients with MM, being related to increased functional impairment and higher cardiopulmonary stress

Screening Of Miners And Millers At Decreasing Levels Of Asbestos Exposure: Comparison Of Chest Radiography And Thin-section Computed Tomography.

Chest radiography (CXR) is inferior to Thin-section computed tomography in the detection of asbestos related interstitial and pleural abnormalities. It remains unclear, however, whether these limitations are large enough to impair CXR´s ability in detecting the expected reduction in the frequency of these asbestos-related abnormalities (ARA) as exposure decreases. Clinical evaluation, CXR, Thin-section CT and spirometry were obtained in 1418 miners and millers who were exposed to progressively lower airborne concentrations of asbestos. They were separated into four groups according to the type, period and measurements of exposure and/or procedures for controlling exposure: Group I (1940-1966/tremolite and chrysotile, without measurements of exposure and procedures for controlling exposure); Group II (1967-1976/chrysotile only, without measurements of exposure and procedures for controlling exposure); Group III (1977-1980/chrysotile only, initiated measurements of exposure and procedures for controlling exposure) and Group IV (after 1981/chrysotile only, implemented measurements of exposure and a comprehensive procedures for controlling exposure). In all groups, CXR suggested more frequently interstitial abnormalities and less frequently pleural plaques than observed on Thin-section CT (p<0.050). The odds for asbestosis in groups of decreasing exposure diminished to greater extent at Thin-section CT than on CXR. Lung function was reduced in subjects who had pleural plaques evident only on Thin-section CT (p<0.050). In a longitudinal evaluation of 301 subjects without interstitial and pleural abnormalities on CXR and Thin-section CT in a previous evaluation, only Thin-section CT indicated that these ARA reduced as exposure decreased. CXR compared to Thin-section CT was associated with false-positives for interstitial abnormalities and false-negatives for pleural plaques, regardless of the intensity of asbestos exposure. Also, CXR led to a substantial misinformation of the effects of the progressively lower asbestos concentrations in the occurrence of asbestos-related diseases in miners and millers.10e011858

Characteristics of the study population separated by the criterion method (Thin-section CT).

<p>Data are frequency (%) or mean ± standard deviation.</p><p>*Smoking adjusted mean ± standard deviation.</p><p>^a p<0.050 comparing Asbestosis vs. Normal.</p><p>^b p<0.050 comparing Pleural plaques vs. Normal.</p><p>Characteristics of the study population separated by the criterion method (Thin-section CT).</p

Incidence rates of asbestosis and pleural plaques in groups of decreasing levels of asbestos exposure.

<p>Note that the marked reduction in incidence of both asbestosis and pleural plaques from Groups I to IV detected by Thin-section CT (TSCT) was not found in the CXR analysis.</p

Smoking-adjusted spirometric variables in patients who presented or not with pleural plaques on CXR and/or Thin-section CT in each group of exposure.

<p>Data are mean ± standard deviation.</p><p>*p<0.050 when comparing those CXR(-) Thin-section CT (+) versus CXR(-) Thin-section CT(-).</p><p>Smoking-adjusted spirometric variables in patients who presented or not with pleural plaques on CXR and/or Thin-section CT in each group of exposure.</p

Odds ratio (95% CI) for interstitial abnormalities and pleural plaques according to the specific imaging method (univariate analysis).

<p>Odds ratio (95% CI) for interstitial abnormalities and pleural plaques according to the specific imaging method (univariate analysis).</p