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Effects of High-Intensity Interval Running Versus Cycling on Sclerostin, and Markers of Bone Turnover and Oxidative Stress in Young Men. Calcif Tissue Int 2019; 104:582-590. [PMID: 30671591 DOI: 10.1007/s00223-019-00524-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 12/31/2018] [Indexed: 01/23/2023]
Abstract
This study compared sclerostin's response to impact versus no-impact high-intensity interval exercise in young men and examined the association between exercise-induced changes in sclerostin and markers of bone turnover and oxidative stress. Twenty healthy men (22.3 ± 2.3 years) performed two high-intensity interval exercise trials (crossover design); running on treadmill and cycling on cycle ergometer. Trials consisted of eight 1 min running or cycling intervals at ≥ 90% of maximal heart rate, separated by 1 min passive recovery intervals. Blood samples were collected at rest (pre-exercise), and 5 min, 1 h, 24 h, and 48 h following each trial. Serum levels of sclerostin, cross-linked telopeptide of type I collagen (CTXI), procollagen type I amino-terminal propeptide (PINP), thiobarbituric acid reactive substances (TBARS), and protein carbonyls (PC) were measured. There was no significant time or exercise mode effect for PINP and PC. A significant time effect was found for sclerostin, CTXI, and TBARS with no significant exercise mode effect and no significant time-by-mode interaction. Sclerostin increased from pre- to 5 min post-exercise (47%, p < 0.05) and returned to baseline within 1 h following the exercise. CTXI increased from pre- to 5 min post-exercise (28%, p < 0.05), then gradually returned to baseline by 48 h. TBARS did not increase significantly from pre- to 5 min post-exercise but significantly decreased from 5 min to 48 h post-exercise. There were no significant correlations between exercise-induced changes in sclerostin and any other marker. In young men, sclerostin's response to high-intensity interval exercise is independent of impact and is not related to changes in bone turnover and oxidative stress markers.
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Abstract
We aimed to develop an in-depth understanding about factors that influence cardiac medication adherence among South Asian, Chinese, and European White cardiac patients. Sixty-four patients were purposively sampled from an ongoing study cohort. Interviews were audio-recorded and transcribed for analyses. Physicians’ culturally sensitive communication and patients’ motivation to live a symptom-free and longer life enhanced adherence. European Whites were motivated to enhance personal well-being and enjoy family life. South Asians’ medication adherence was influenced by the desire to fulfill the will of God and family responsibilities. The Chinese were motivated to avoid pain, illness, and death, and to obey a health care provider. The South Asians and Chinese wanted to ultimately reduce medication use. Previous positive experiences, family support, and establishing a routine also influenced medication adherence. Deterrents to adherence were essentially the reverse of the motivators/facilitators. This analysis represents an essential first step forward in developing ethno-culturally tailored interventions to optimize adherence.
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VaxCelerate: the use of MTBhsp70-avidin as an adjuvant to rapidly generate self-assembling vaccines with biotinylated, antigen-specific peptides targeting emerging pathogens. (VAC6P.941). THE JOURNAL OF IMMUNOLOGY 2014. [DOI: 10.4049/jimmunol.192.supp.140.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Abstract
Development of effective vaccines against emerging infectious diseases can take years to progress from pathogen isolation/identification to clinical approval. As a result, conventional approaches fail to produce field-ready vaccines before the EID has spread extensively. The VaxCelerate Project’s goal is to create a platform capable of generating and pre-clinically testing a new vaccine against specific pathogen targets in less than 120 days. A self-assembling vaccine, consisting of a fusion protein M. tuberculosis MTBhsp70 and avidin (MAV), is at the core of the approach. Mixing the MAV with biotinylated pathogen specific immunogenic peptides yields a self-assembled vaccine (SAV). To minimize the time required, we used a distributed R&D model involving experts in protein engineering, bioinformatics, peptide synthesis/design and GMP/GLP manufacturing and testing. This approach was first tested using ovalbumin in C57Bl/6 mice, Flu (H1N1) specific peptides, and ultimately a Lassa fever virus (LFV) specific vaccine in transgenic HLA DR3 mice. Using a GLP validated assay we demonstrated that the MAV assembled LFV induced significantly increased class II peptide specific interferon-CD4+ T cell responses in transgenic mice compared to peptide or MAV alone controls. The use of an identical design for each vaccine may facilitate accelerated regulatory review and by developing safety assessment tools that are more relevant to human vaccine responses than current preclinical models.
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Understanding the influence of urban- or rural-living on cardiac patients' decisions about diet and physical activity: descriptive decision modeling. Int J Nurs Stud 2013; 50:1513-23. [PMID: 23597917 DOI: 10.1016/j.ijnurstu.2013.03.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 02/23/2013] [Accepted: 03/05/2013] [Indexed: 11/24/2022]
Abstract
BACKGROUND It is challenging to assist people to attend to risk factors for coronary artery disease (CAD). There is potential for cultural elements associated with place of residence (i.e., urban- or rural-living) to have an effect on peoples' decision-making about managing CAD risk. AIM To better understand patient's decision-making processes regarding having a heart-healthy diet and engaging in regular physical activity (major CAD risk factors), and the potential influence of urban- or rural-living. METHODS Based on a previous series of qualitative interviews with 42 cardiac patients (21 urban-living, 21 rural-living), hierarchical decision-models regarding eating a heart-healthy diet and engaging in regular physical activity were developed, and a survey based on the decision-models generated. The models were then tested for 'fit' with another group of 42 cardiac patients, and were revised to make them more parsimonious. The final models were tested with a novel group of 647 CAD patients from Alberta, Canada (327 urban-living, 320 rural-living). The primary analysis was focused on determining the extent to which patients completing the survey fell in the correct behavioral group. Thereafter individual nodes were examined to determine decision-making constructs that were different between urban- and rural-living patients. RESULTS When tested, the models had overall accuracy of 93.5% for diet and 97.5% for physical activity. The most salient model nodes that led to differing behavioral outcomes reflected these constructs: perception of control over health; time, effort, or competing priorities; receipt of appropriate information; and appeal of the activity. CONCLUSIONS This information is potentially useful to assist healthcare providers to: (1) understand patients' decisions regarding their cardiac risk factor modification behavior, and (2) better direct conversations about risk factor modification and educational activities.
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Skeletal effects of zoledronic acid in an animal model of chronic kidney disease. Osteoporos Int 2013; 24:1471-81. [PMID: 22907737 PMCID: PMC4063946 DOI: 10.1007/s00198-012-2103-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Accepted: 07/10/2012] [Indexed: 01/23/2023]
Abstract
UNLABELLED Bisphosphonates reduce skeletal loss and fracture risk, but their use has been limited in patients with chronic kidney disease. This study shows skeletal benefits of zoledronic acid in an animal model of chronic kidney disease. INTRODUCTION Bisphosphonates are routinely used to reduce fractures but limited data exists concerning their efficacy in non-dialysis chronic kidney disease. The goal of this study was to test the hypothesis that zoledronic acid produces similar skeletal effects in normal animals and those with kidney disease. METHODS At 25 weeks of age, normal rats were treated with a single dose of saline vehicle or 100 μg/kg of zoledronic acid while animals with kidney disease (approximately 30% of normal kidney function) were treated with vehicle, low dose (20 μg/kg), or high dose (100 μg/kg) zoledronic acid, or calcium gluconate (3% in the drinking water). Skeletal properties were assessed 5 weeks later using micro-computed tomography, dynamic histomorphometry, and mechanical testing. RESULTS Animals with kidney disease had significantly higher trabecular bone remodeling compared to normal animals. Zoledronic acid significantly suppressed remodeling in both normal and diseased animals yet the remodeling response to zoledronic acid was no different in normal and animals with kidney disease. Animals with kidney disease had significantly lower cortical bone biomechanical properties; these were partially normalized by treatment. CONCLUSIONS Based on these results, we conclude that zoledronic acid produces similar amounts of remodeling suppression in animals with high turnover kidney disease as it does in normal animals, and has positive effects on select biomechanical properties that are similar in normal animals and those with chronic kidney disease.
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Combined Effect of Dietary Supplementation with Pressurized Whey and Exercise Training in Chronic Obstructive Pulmonary Disease: A Randomized, Controlled, Double-Blind Pilot Study. J Med Food 2010; 13:589-98. [DOI: 10.1089/jmf.2009.0142] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Muscle Atrophy and Hypertrophy Signaling in Patients with Chronic Obstructive Pulmonary Disease. Am J Respir Crit Care Med 2007; 176:261-9. [PMID: 17478621 DOI: 10.1164/rccm.200605-704oc] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
RATIONALE The molecular mechanisms of muscle atrophy in chronic obstructive pulmonary disease (COPD) are poorly understood. In wasted animals, muscle mass is regulated by several AKT-related signaling pathways. OBJECTIVES To measure the protein expression of AKT, forkhead box class O (FoxO)-1 and -3, atrogin-1, the phosphophrylated form of AKT, p70(S6K) glycogen synthase kinase-3beta (GSK-3beta), eukaryotic translation initiation factor 4E binding protein-1 (4E-BP1), and the mRNA expression of atrogin-1, muscle ring finger (MuRF) protein 1, and FoxO-1 and -3 in the quadriceps of 12 patients with COPD with muscle atrophy and 10 healthy control subjects. Five patients with COPD with preserved muscle mass were subsequently recruited and were compared with six patients with low muscle mass. METHODS Protein contents and mRNA expression were measured by Western blot and quantitative polymerase chain reaction, respectively. MEASUREMENTS AND MAIN RESULTS The levels of atrogin-1 and MuRF1 mRNA, and of phosphorylated AKT and 4E-BP1 and FoxO-1 proteins, were increased in patients with COPD with muscle atrophy compared with healthy control subjects, whereas atrogin-1, p70(S6K), GSK-3beta, and FoxO-3 protein levels were similar. Patients with COPD with muscle atrophy showed an increased expression of p70(S6K), GSK-3beta, and 4E-BP1 compared with patients with COPD with preserved muscle mass. CONCLUSIONS An increase in atrogin-1 and MuRF1 mRNA and FoxO-1 protein content was observed in the quadriceps of patients with COPD. The transcriptional regulation of atrogin-1 and MuRF1 may occur via FoxO-1, but independently of AKT. The overexpression of the muscle hypertrophic signaling pathways found in patients with COPD with muscle atrophy could represent an attempt to restore muscle mass.
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Susceptibility to Muscle Fatigue and Lung Mechanics in Chronic Obstructive Pulmonary Disease. CLIN INVEST MED 2007. [DOI: 10.25011/cim.v30i3.1721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Background: Contractile fatigue of the quadriceps occurs in a significant proportion of patients with COPD after constant-load cycling exercise. Dynamic hyperinflation, by altering cardiac output during exercise, could contribute to fatigue susceptibility in this population. The purpose of this study was to compare operational lung volumes during constant workrate exercise between COPD patients who do and those who do not develop contractile fatigue of the quadriceps (fatiguers vs non-fatiguers).
Methods: Sixty-two patients with COPD (FEV1: 46±16%) completed a constant-load cycling test at 80% of the peak workrate achieved during progressive cycle ergometry. Ventilatory parameters were monitored breath-by-breath, while inspiratory capacity maneuvers were obtained every other minute during constant-load cycling. Quadriceps twitch force was measured with magnetic stimulation of the femoral nerve before and after the test. Muscle fatigue was defined as a post-exercise reduction in quadriceps twitch force of more than 15% of the resting value.
Results: Forty patients (65%) developed muscle fatigue after constant-load cycling. No significant differences were found between fatiguers and non-fatiguers with respect to age, body mass index, resting lung function, peak oxygen consumption, and endurance time to constant-load exercise. Change in inspiratory capacity from rest to end-exercise (DIC) was similar between both subgroups (DIC: 0.56±0.32L vs 0.56±0.47L for fatiguers and non-fatiguers respectively, P=0.99).
Conclusion: Susceptibility to muscle fatigue could not be predicted by exercise duration or by the degree of dynamic hyperinflation in patients with COPD.
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Locus of Symptom Limitation and Exercise Response to Bronchodilation in Chronic Obstructive Pulmonary Disease. CLIN INVEST MED 2007. [DOI: 10.25011/cim.v30i3.1737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Background: We previously reported that the occurrence of contractile fatigue of the quadriceps during exercise in patients with COPD reduced the likelihood of acute bronchodilation to improve the endurance time to constant work rate exercise. The purpose of the present study was to assess whether the perception of dyspnea and leg fatigue during exercise could be used to predict the exercise response to acute bronchodilation in this population.
Methods: Sixty-eight patients with COPD performed either two constant work-rate cycling exercises or two endurance shuttle walking tests. These tests were preceded by nebulization of placebo or 500 mg ipratropium bromide. Changes in FEV1 and in the endurance time with bronchodilation were measured. The changes in quadriceps twitch force after exercise were evaluated. In addition, we assessed dyspnea and perception of leg fatigue on Borg scale as well as the locus of exercise limitation (dyspnea, leg fatigue, or both).
Results: The locus of symptom limitation was useful to predict the exercise response to bronchodilation; patients stopping exercise because of leg fatigue or due to a combination of dyspnea/leg fatigue showed a smaller improvement in endurance time to constant work rate exercise with bronchodilation compared with those stopping because of dyspnea. Subjective and objective evidences of fatigue were related: patients who stopped exercising because of leg fatigue showed a larger fall in quadriceps twitch force compared to patients who stopped for dyspnea.
Conclusion: The assessment of the locus of symptom limitation during constant work rate exercise is useful to predict the improvement in endurance time following acute bronchodilation in patients with COPD.
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Test de marche de six minutes versus marche navette d’endurance : sensibilité à la bronchodilatation dans la BPCO. Rev Mal Respir 2006. [DOI: 10.1016/s0761-8425(06)71620-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
BACKGROUND Alterations in skeletal muscle function are known to contribute to exercise intolerance in patients with chronic heart failure (CHF). OBJECTIVES To evaluate whether muscle isometric endurance can be objectively measured and whether it is related to skeletal muscle metabolism in CHF. METHODS Isometric endurance of the vastus lateralis, measured as time to fatigue (T(F)), was evaluated in 25 patients with CHF (55+/-8 years of age [mean +/- SD]) and 18 healthy subjects (HS) (62+/-6 years of age [mean +/- SD]). Median frequency of surface electromyography was obtained from spectral analysis using a fast Fourier transformation. Citrate synthase (CS), 3-hydroxyacyl-CoA dehydrogenase (HADH), hexokinase (HK) and phosphofructokinase (PFK) activities were determined from the right vastus lateralis muscle. RESULTS T(F) was lower in CHF patients than in HS (49+/-4 s and 80+/-7 s, respectively; P<0.01). Muscle fatigue was present at the end of the endurance test in both groups (median frequency breakpoint at mid-exercise for both groups [P<0.05]). CS (P<0.01) and HK (P<0.01) activities were lower in CHF patients than in HS, but PFK activity was higher (P<0.05). T(F) correlated significantly with CS (r=0.50), HADH (r=0.42), PFK (r=-0.47) and HK (r=0.41) activities and the PFK/CS ratio (r=-0.39) when both groups were considered, and with HADH (r=0.47) and PFK (r=-0.57) activities for the CHF group alone (all P<0.05). CONCLUSIONS These results suggest that isometric endurance of the vastus lateralis muscle is reduced in patients with CHF and that it is related to a reduced muscle oxidative capacity.
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Abstract
Contractile fatigue is associated with exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). Contractile fatigue may be assessed by quantifying the decline in strength after a fatiguing protocol but this may pose practical problems. The purpose of this study was to investigate the relationship between the decline in quadriceps strength, quadriceps electrical activity, perception of leg fatigue, and arterial lactate level in patients with COPD during constant work-rate cycling exercise. The decline in quadriceps strength was significantly associated with the decrease in electromyographic median frequency (r = 0.606), leg fatigue perception (r = 0.453), and arterial lactate level (r = 0.384). Using the receiver-operating-characteristic curve, it was found that a 4% decline in electromyographic median frequency had a 94% sensitivity and a 75% specificity to predict contractile fatigue. We conclude that contractile fatigue commonly occurs during cycling exercise in COPD. The electromyographic median frequency appears to be a valuable indirect marker to predict contractile leg fatigue.
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Abstract
RATIONALE There is no consensus regarding which exercise test to use to evaluate the functional impact of bronchodilators in patients with chronic obstructive pulmonary disease. OBJECTIVE AND METHODS Bronchodilator-induced changes in endurance time were evaluated during cycling and walking in 17 patients with chronic obstructive pulmonary disease who completed two cycle endurance tests and two endurance shuttle walks at 80% of peak capacity. Each endurance test was preceded by the nebulization of a placebo or 500 microg of ipratropium bromide using a randomized, double-blind, crossover design. Quadriceps twitch force was measured with magnetic stimulation of the femoral nerve before and after each endurance test. RESULTS Cycling endurance time did not improve significantly after bronchodilation despite a significant increase in FEV1 (delta endurance time ipratropium bromide - placebo: 51 +/- 255 s, p = 0.42). A similar change in FEV1 was associated with a significant improvement in walking endurance time (delta endurance time ipratropium bromide - placebo: 164 +/- 177 s, p < 0.01). A 22 +/- 17% fall in quadriceps twitch force was observed after cycling, whereas no significant change was seen after walking. CONCLUSION The endurance shuttle walk is a sensitive test to detect changes in exercise tolerance after bronchodilation. Differences in the occurrence of quadriceps muscle fatigue may explain, in part, the different responsiveness to change between cycling and walking.
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Abstract
Abnormal heart rate recovery (HRR) after exercise, a marker of cardiac autonomic dysfunction, is associated with poor prognosis in various populations. As chronic obstructive pulmonary disease (COPD) is associated with cardiac autonomic dysfunction, we tested the hypothesis that patients with COPD have a lower HRR than healthy people, and evaluated whether a delay in HRR is associated with an increased risk of mortality in COPD. The records of 147 COPD patients were reviewed (65.1+/-9.1 years, mean+/-sd, 42 women/105 men, forced expiratory volume in 1s (FEV1): 42+/-15% predicted) and compared to 25 healthy subjects (61.6+/-4.5 years, 5 women/20 men, FEV1: 100+/-14% predicted) during recovery after an exercise test. Heart rate was measured at peak exercise and at 1-min recovery, the difference between the two being defined as HRR (11+/-9 beats in COPD patients vs. 20+/-9 beats in healthy subjects, P < 0.0001). During a mean follow-up of 43.1+/-22.0 months, 32 patients died. Abnormal HRR (14 beats) was a strong predictor of mortality in COPD patients (adjusted hazard ratio: 5.12, 95% CI [1.54-17.00]). In conclusion, COPD patients have a lower HRR than healthy subjects, and have a worse prognosis when presenting abnormal HRR.
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Abstract
BACKGROUND Because oxidative stress affects muscle function, the underlying mechanism to explain exercise induced peripheral muscle oxidative stress in patients with chronic obstructive pulmonary disease (COPD) is clinically relevant. This study investigated whether chronic hypoxaemia in COPD worsens peripheral muscle oxidative stress and whether an abnormal muscle inflammatory process is associated with it. METHODS Nine chronically hypoxaemic and nine non-hypoxaemic patients performed repeated knee extensions until exhaustion. Biopsy specimens were taken from the vastus lateralis muscle before and 48 hours after exercise. Muscle oxidative stress was evaluated by lipid peroxidation (lipofuscin and thiobarbituric acid reactive substances (TBARs)) and oxidised proteins. Inflammation was evaluated by quantifying muscle neutrophil and tumour necrosis factor (TNF)-alpha levels. RESULTS When both groups were taken together, arterial oxygen pressure was positively correlated with quadriceps endurance time (n = 18, r = 0.57; p < 0.05). At rest, quadriceps lipofuscin inclusions were significantly greater in hypoxaemic patients than in non-hypoxaemic patients (2.9 (0.2) v 2.0 (0.3) inclusions/fibre; p < 0.05). Exercise induced a greater increase in muscle TBARs and oxidised proteins in hypoxaemic patients than in non-hypoxaemic patients (40.6 (9.1)% v 10.1 (5.8)% and 51.2 (11.9)% v 3.7 (12.2)%, respectively, both p = 0.01). Neutrophil levels were significantly higher in hypoxaemic patients than in non-hypoxaemic patients (53.1 (11.6) v 21.5 (11.2) counts per fibre x 10(-3); p < 0.05). Exercise did not alter muscle neutrophil levels in either group. Muscle TNF-alpha was not detected at baseline or after exercise. CONCLUSION Chronic hypoxaemia was associated with lower quadriceps endurance time and worsened muscle oxidative stress at rest and after exercise. Increased muscle neutrophil levels could be a source of the increased baseline oxidative damage. The involvement of a muscle inflammatory process in the exercise induced oxidative stress of patients with COPD remains to be shown.
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Contractile fatigue, muscle morphometry, and blood lactate in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2005; 171:1109-15. [PMID: 15735055 DOI: 10.1164/rccm.200408-1005oc] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We hypothesized that patients with chronic obstructive pulmonary disease developing contractile fatigue of the quadriceps during cycle exercise may have characteristic metabolic and muscle features that could increase their susceptibility to fatigue, thus differentiating them from those who do not develop fatigue. We examined, in 32 patients, the fiber-type proportion, enzymatic activities, and capillary density in the vastus lateralis and the arterial blood lactate level during constant work-rate cycling exercise. Contractile fatigue was defined as a postexercise fall in quadriceps twitch force greater than 15% of resting values. Twenty-two patients developed contractile fatigue after exercise. No significant differences were found between fatiguers and non-fatiguers for the endurance time, fiber-type proportion, and oxidative enzyme activities. The lactate dehydrogenase activity was significantly higher (p < 0.05) and muscle capillarization significantly reduced in fatiguers (p < 0.05). Compared with non-fatiguers, the arterial lactate level during exercise was significantly higher in fatiguers (p < 0.001). A significant relationship was found between the fall in quadriceps twitch force and lactate dehydrogenase activity, capillary/fiber ratio, and blood lactate level. We conclude that changes in muscle enzymatic profile and capillarization with a greater reliance on glycolytic metabolism during exercise are associated with contractile fatigue in patients with chronic obstructive pulmonary disease.
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MESH Headings
- Aged
- Capillaries/pathology
- Citrate (si)-Synthase/metabolism
- Exercise
- Humans
- L-Lactate Dehydrogenase/metabolism
- Lactic Acid/blood
- Male
- Middle Aged
- Muscle Fatigue
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Skeletal/pathology
- Muscle, Skeletal/blood supply
- Muscle, Skeletal/diagnostic imaging
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscle, Skeletal/physiopathology
- Pulmonary Disease, Chronic Obstructive/metabolism
- Pulmonary Disease, Chronic Obstructive/pathology
- Pulmonary Disease, Chronic Obstructive/physiopathology
- Radiography
- Rest
- Thigh
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COPD Results in a Reduction in UCP3 Long mRNA and UCP3 Protein Content in Types I and IIa Skeletal Muscle Fibers. ACTA ACUST UNITED AC 2004; 24:332-9. [PMID: 15602154 DOI: 10.1097/00008483-200409000-00009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Findings recently have shown coupling protein-3 (UCP3) content to be decreased in the skeletal muscle of patients with chronic obstructive pulmonary disease (COPD). Uncoupling protein-3 mRNA exists as two isoforms: long (UCP3L) and short (UCP3S). The UCP3 protein is expressed the least in oxidative and the most in glycolytic muscle fibers. Levels of UCP3 have been associated positively with intramyocellular triglyceride (IMTG) contents in conditions of altered fatty acid metabolism. As a source for muscle free fatty acid metabolism, IMTG is decreased in COPD. The current study completely characterized all the parameters of UCP3 expression (ie, UCP3L and UCP3S mRNA expression in whole muscle samples) and UCP3 protein content as well as IMTG content in the different fiber types in patients with COPD and healthy control subjects. METHODS Using real-time polymerase chain reaction, UCP3 gene expression was quantified. Skeletal muscle fiber type and UCP3 protein and IMTG content were measured using immunofluorescence and Oil red oil staining, respectively. RESULTS The findings showed that UCP3L mRNA expression was 44% lower (P < .005) in the patients with COPD than in the control subjects, whereas the UCP3S mRNA content was similar in the two groups. As compared with control subjects, UCP3 protein content was decreased by 89% and 83% and the IMTG content by 64% and 54%, respectively, in types I and IIa fibers (P < .0167) of patients with COPD, whereas they were unchanged in IIx fibers. CONCLUSIONS The reduced UCP3 and IMTG content in the more oxidative fibers may be linked to the altered muscle fatty acid metabolism associated with COPD. Further studies are required to determine the exact role and clinical relevance of the reduced UCP3 content in patients with COPD.
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Abstract
BACKGROUND Based on previously reported changes in muscle metabolism that could increase susceptibility to fatigue, we speculated that patients with chronic obstructive pulmonary disease (COPD) have reduced quadriceps endurance and that this will be correlated with the proportion of type I muscle fibres and with the activity of oxidative enzymes. METHODS The endurance of the quadriceps was evaluated during an isometric contraction in 29 patients with COPD (mean (SE) age 65 (1) years; forced expiratory volume in 1 second 37 (3)% predicted) and 18 healthy subjects of similar age. The electrical activity of the quadriceps was recorded during muscle contraction as an objective index of fatigue. The time at which the isometric contraction at 60% of maximal voluntary capacity could no longer be sustained was used to define time to fatigue (Tf). Needle biopsies of the quadriceps were performed in 16 subjects in both groups to evaluate possible relationships between Tf and markers of muscle oxidative metabolism (type I fibre proportion and citrate synthase activity). RESULTS Tf was lower in patients with COPD than in controls (42 (3) v 80 (7) seconds; mean difference 38 seconds (95% CI 25 to 50), p<0.001). Subjects in both groups had evidence of electrical muscle fatigue at the end of the endurance test. In both groups significant correlations were found between Tf and the proportion of type I fibres and citrate synthase activity. CONCLUSION Isometric endurance of the quadriceps muscle is reduced in patients with COPD and the muscle oxidative profile is significantly correlated with muscle endurance.
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Abstract
Although the influence of lung volume reduction surgery (LVRS) on incremental- and constant-power exercise is important in the evaluation of this procedure for patients with chronic obstructive pulmonary disease (COPD), it is rarely reported even in large randomised controlled trials. This report describes 39 patients with severe COPD ((mean +/- SE) forced expiratory volume in one second 32 +/- 2% pred, functional residual capacity 195 +/- 6% pred) who participated in a randomised controlled trial of LVRS and who completed incremental exercise tests at 6 months as well as endurance tests (constant power of 25 +/- 1 W) at 3, 9 and 12 months. Peak oxygen uptake (V'O2,pk) was similar between the treatment (n = 19) and control groups (n = 20) at baseline. After LVRS, the treatment group had a significantly greater V'O2,pk (mean difference (95% CI) 1.28 (0.07-2.50) mL x kg x min(-1)) and power (13 (6-20) W). The treatment group achieved a significantly greater minute ventilation (7.1 (2.9-11.3) L x min(-1)) with a greater tidal volume (0.16 (0.04-0.28) L). Baseline endurance was similar between groups. After surgery, there were significant between-group differences in endurance time, which were maintained at 12 months (7.3 (3.9-10.8) min). Lung volume reduction surgery is associated with an increase in exercise capacity and endurance, as compared with conventional medical treatment.
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Contractile leg fatigue after cycle exercise: a factor limiting exercise in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2003; 168:425-30. [PMID: 12714348 DOI: 10.1164/rccm.200208-856oc] [Citation(s) in RCA: 166] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We evaluated whether contractile fatigue of the quadriceps occurs after cycling exercise in patients with chronic obstructive pulmonary disease (COPD) and whether it could contribute to exercise limitation. Eighteen COPD patients performed two constant work-rate cycling exercises up to exhaustion. These tests were preceded by nebulization of placebo or 500 microg of ipratropium bromide. Muscle fatigue was defined as a postexercise reduction in quadriceps twitch force of more than 15% of the resting value. There was an increase in endurance time postipratropium compared with placebo nebulization (440 +/- 244 seconds vs. 322 +/- 188 seconds, p = 0.06). Nine patients developed contractile fatigue after placebo exercise. In these patients, ipratropium did not increase the endurance time (394 +/- 220 seconds with placebo vs. 400 +/- 119 seconds with ipratropium) despite an 11% improvement in FEV1. In the nine patients who did not fatigue after placebo exercise, endurance time increased from 249 +/- 124 seconds with placebo to 479 +/- 298 seconds with ipratropium (p < 0.05). There was a significant correlation between the improvement in endurance time with ipratropium and quadriceps twitch force at 10 minutes after placebo exercise (r = 0.59, p = 0.01). The occurrence of contractile fatigue during exercise may explain why bronchodilation fails to improve exercise tolerance in some COPD patients.
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Abstract
BACKGROUND The mechanisms leading to muscle wasting in patients with COPD are still uncertain. This study was undertaken to evaluate the relationships among circulating levels of catabolic factors (ie, interleukin [IL]-6 and cortisol), anabolic factors (ie, bioavailable testosterone [Tbio], dehydroepiandrosterone sulfate [DHEAS], and insulin-like growth factor [IGF]-I), and mid-thigh muscle cross-sectional area (MTCSA) in patients with COPD. METHODS Serum levels of the above factors were measured in 45 men with COPD (mean [+/- SEM] FEV(1), 43 +/- 3% predicted; mean age, 67 +/- 1 years) and 16 sedentary healthy men of similar age. MTCSA was quantified using CT scanning. Patients with COPD were subdivided into two groups according to the MTCSA (< 70 or >or= 70 cm(2)). RESULTS There was a greater prevalence of hypogonadism (ie, Tbio, < 2 nmol/L) in patients with COPD compared to control subjects (22% vs 0%, respectively). Patients with an MTCSA of < 70 cm(2) had significantly reduced levels of DHEAS compared to those in healthy subjects (p < 0.01). IL-6 levels were significantly higher in both subgroups of COPD patients compared to those in control subjects (p < 0.005). The cortisol/DHEAS, IL-6/DHEAS, IL-6/Tbio, and IL-6/IGF-I ratios were significantly greater in COPD patients with an MTCSA of < 70 cm(2) compared to those in control subjects (p < 0.05). The cortisol/DHEAS and IL-6/DHEAS ratios were also significantly greater in COPD patients with an MTCSA of < 70 cm(2) than in COPD patients with an MTCSA of >or= 70 cm(2) (p < 0.05). In a stepwise multiple regression analysis, the IL-6/DHEAS ratio explained 20% of the variance in MTCSA (p < 0.005). CONCLUSION Catabolic/anabolic disturbances were found in COPD patients leading to a shift toward catabolism and possibly to the development of peripheral muscle wasting.
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Exercise-induced quadriceps oxidative stress and peripheral muscle dysfunction in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2003; 167:1664-9. [PMID: 12672647 DOI: 10.1164/rccm.200209-1028oc] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Exercise-induced muscle oxidative stress may be involved in the myopathy associated with chronic obstructive pulmonary disease (COPD). This study was designed to look at whether local exercise induces muscle oxidative stress and whether this oxidative stress may be associated with the reduced muscle endurance in patients with COPD. Quadriceps endurance was measured in 12 patients with COPD (FEV1 = 0.96 +/- 0.14 SEM) and 10 healthy sedentary subjects by repeated knee extensions of the dominant leg. Biopsies of the vastus lateralis muscle were obtained before and 48 hours after exercise. Muscle oxidative stress was measured by lipid peroxidation and oxidized proteins. Muscle antioxidant was evaluated by peroxidase glutathion activity. Quadriceps endurance was significantly reduced in patients with COPD when compared with the healthy control subjects (p < 0.01). Forty-eight hours postexercise, only patients with COPD had a significant increase in muscle lipid peroxidation (p < 0.05) and oxidized proteins (p < 0.05), whereas increased peroxidase glutathion activity was only observed in control subjects (p < 0.05). Both increases in muscle lipid peroxidation and oxidized proteins were significantly and inversely correlated with quadriceps endurance capacity in COPD (p < 0.05). In summary, local exercise induced muscle oxidative stress in patients with COPD, whereas it failed to raise antioxidant activity. In these individuals, muscle oxidative stress was associated with a reduced quadriceps endurance.
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Influence of lung volume reduction surgery (LVRS) on health related quality of life in patients with chronic obstructive pulmonary disease. Thorax 2003; 58:405-10. [PMID: 12728160 PMCID: PMC1746667 DOI: 10.1136/thorax.58.5.405] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND The clinical value of LVRS has been questioned in the absence of trials comparing it with pulmonary rehabilitation, the prevailing standard of care in COPD. Patients with heterogeneous emphysema are more likely to benefit from volume reduction than those with homogeneous disease. Disease specific quality of life is a responsive interpretable outcome that enables health professionals to identify the magnitude of the effect of an intervention across several domains. METHODS Non-smoking patients aged <75 years with severe COPD (FEV(1) <40% predicted, FEV(1)/FVC <0.7), hyperinflation, and evidence of heterogeneity were randomised to surgical or control groups after pulmonary rehabilitation and monitored at 3 month intervals for 12 months with no crossover between the groups. The primary outcome was disease specific quality of life as measured by the Chronic Respiratory Questionnaire (CRQ). Treatment failure was defined as death or functional decline (fall of 1 unit in any two domains of the CRQ). Secondary outcomes included pulmonary function and exercise capacity. RESULTS LVRS resulted in significant between group differences in each domain of the CRQ at 12 months (change of 0.5 represents a small but important difference): dyspnoea 1.9 (95% confidence interval (CI) 1.3 to 2.6; p<0.0001); emotional function 1.5 (95% CI 0.9 to 2.1; p<0.0001); fatigue 2.0 (95% CI 1.4 to 2.6; p<0.0001); mastery 1.8 (95% CI 1.2 to 2.5; p<0.0001). In the control group one of 27 patients died and 16 experienced functional decline over 12 months. In the surgical group four of 28 patients died and three experienced functional decline (hazard ratio = 3.1 (95% CI 1.3 to 7.6; p=0.01). Between group improvements (p<0.05) in lung volumes, flow rates, and exercise were sustained at 12 months (RV -47% predicted (95% CI -71 to -23; p=0.0002); FEV(1) 0.3 l (95% CI 0.1 to 0. 5; p=0.0003); submaximal exercise 7.3 min (95% CI 3.9 to 10.8; p<0.0001); 6 minute walk 66 metres (95% CI 32 to 101; p=0.0002). CONCLUSIONS In COPD patients with heterogeneous emphysema, LVRS resulted in important benefits in disease specific quality of life compared with medical management, which were sustained at 12 months after treatment.
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Abstract
Peripheral muscle weakness is common in chronic obstructive pulmonary disease (COPD) but it is still under debate whether weakness is due to atrophy or contractile dysfunction. In vitro and in vivo contractile properties of the vastus lateralis muscle were studied in 16 patients with stable COPD (forced expiratory volume in one second 39 +/- 16% of predicted, age 67 +/- 4 yrs (mean +/- sD)) and nine sedentary control subjects. Isometric knee extensor strength was measured while mid-thigh muscle cross-sectional area (MTMCSA) was obtained using computed tomography. Muscle strips from the vastus lateralis obtained through open biopsy were rapidly suspended in an oxygenated Krebs-Ringer solution that was maintained at 35 degrees C with a pH of 7.40 to study their contractile properties. The isometric knee extensors strength/MTMCSA ratio was 0.50 +/- 0.08 versus 0.58 +/- 0.06 kg x cm(-2) for COPD and control subjects, respectively. The muscle bundle cross-sectional area (CSA) was 4.6 +/- 2.1 and 4.4 +/- 3.1 mm(-2), the length at which active tension was maximum was 15 +/- 4 and 15 +/- 3 mm, and maximal isometric peak forces normalised for CSA were 4.3 +/- 2.7 and 4.8 +/- 2.6 N x cm(-2) for COPD and control subjects, respectively. The force/frequency relationship tended to be shifted to the right in patients with COPD, meaning that a higher stimulation frequency was necessary to produce the same relative force. Patients with COPD had a lower proportion of type I fibre than controls (26 +/- 12% versus 39 +/- 11%) with reciprocal significant increase in type IIb fibre proportion (20+/-16% versus 8 +/- 4%). The proportion of type IIa fibres was similar between the two groups. These results suggest that the contractile properties of the vastus lateralis are preserved in patients with chronic obstructive pulmonary disease. Therefore, the reduction in the quadriceps strength in patients with chronic obstructive pulmonary disease cannot be explained on the basis of an alteration of the contractile apparatus.
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Midthigh muscle cross-sectional area is a better predictor of mortality than body mass index in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2002; 166:809-13. [PMID: 12231489 DOI: 10.1164/rccm.2107031] [Citation(s) in RCA: 553] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
This study was undertaken to test the hypothesis that a reduction in midthigh muscle cross-sectional area obtained by CT scan (MTCSA(CT)) is a better predictor of mortality in chronic obstructive pulmonary disease (COPD) than low body mass index (BMI). We also wished to evaluate whether anthropometric measurements could be used to estimate MTCSA(CT). One hundred forty-two patients with COPD (age = 65 +/- 9 years, mean +/- SD, 26 F, BMI = 26 +/- 6 kg/m(2), FEV(1) = 42 +/- 16% predicted) were recruited from September 1995 to April 2000 with a mean follow-up of 41 +/- 18 months. The primary end-point was all-cause mortality during the study period. A Cox proportional hazards regression model was used to predict mortality using the following independent variables: age, sex, daily use of corticosteroid, FEV(1), DL(CO), BMI, thigh circumference, MTCSA(CT), peak exercise workrate, Pa(O2), and Pa(CO2). Only MTCSA(CT) and FEV(1) were found to be significant predictors of mortality (p = 0.0008 and p = 0.01, respectively). A second analysis was also performed with FEV(1) and MTCSA(CT) dichotomized. Patients were divided into four subgroups based on FEV(1) (< or >or= 50% predicted) and MTCSA(CT) (< or >or= 70 cm(2)). Compared with patients with an FEV(1) >or= 50% predicted and a MTCSA(CT) >or= 70 cm(2), those with an FEV(1) < 50% predicted and a MTCSA(CT) >or= 70 cm(2) had a mortality odds ratio of 3.37 (95% confidence interval, 0.41-28.00), whereas patients with an FEV(1) < 50% predicted and a MTCSA(CT) < 70 cm(2) had a mortality odds ratio of 13.16 (95% confidence interval, 1.74-99.20). MTCSA(CT) could not be estimated with sufficient accuracy from anthropometric measurements. In summary, we found in this cohort of patients with COPD that (1) MTCSA(CT) was a better predictor of mortality than BMI, and (2) MTCSA had a strong impact on mortality in patients with an FEV(1) < 50% predicted. These findings suggest that the assessment of body composition may be useful in the clinical evaluation of these patients.
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Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease. Muscle Nerve 2002; 25:383-9. [PMID: 11870715 DOI: 10.1002/mus.10039] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exercise-induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (VO(2)) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross-sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber-type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO(2) and SaO(2), peak VO(2), and DeltaPaO(2) and DeltaSaO(2) during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.
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Abstract
Patients with chronic obstructive pulmonary disease (COPD) usually stop exercise before reaching physiological limits in terms of O(2) delivery and extraction. A plateau in lower limb O(2) uptake (VO(2)) and blood flow occurs despite progression of the imposed workload during cycling in some patients with COPD, suggesting that maximal capacity to transport O(2) had been reached and that it had been extracted in the peripheral exercising muscles. This study addresses this observation. Symptom-limited incremental cycle exercise was performed by 14 men [62 +/- 11 (SD) yr] with severe COPD (forced expiratory volume in 1 s = 35 +/- 7% of predicted value). Leg blood flow was measured at each exercise step with a thermodilution catheter inserted in the femoral vein. This value was multiplied by two to account for both working legs (Q(LEGS)). Arterial and femoral venous blood was sampled at each exercise step to measure blood gases. Leg O(2) consumption (VO(2LEGS)) was calculated according to the Fick equation. Total body VO(2) (VO(2TOT)) was measured from expired gas analysis, and tidal volume (VT) and minute ventilation (VE) were derived from the flow signal. In eight patients, VO(2LEGS) kept increasing in parallel with VO(2TOT) as external work rate was increasing. In six subjects, a plateau in VO(2LEGS) and Q(LEGS) occurred during exercise (increment of <3% between 2 consecutive increasing workloads) despite the increase in workload and VO(2TOT) [corresponding mean was 110 +/- 38 ml (11 +/- 4%)]. These six patients also exhibited a plateau in O(2) extraction during exercise. Peak exercise work rate was higher in the eight patients without a plateau than in the six with a plateau (51 +/- 10 vs. 40 +/- 13 W, P = 0.043). VT, VE, and dyspnea were significantly greater at submaximal exercise in patients of the plateau group compared with those of the nonplateau group. These results show that, in some patients with COPD, blood flow directed to peripheral muscles and O(2) extraction during exercise may be limited. We speculate that redistribution of cardiac output and O(2) from the lower limb exercising muscles to the ventilatory muscles is a possible mechanism.
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Abstract
Peripheral muscle dysfunction is a common systemic complication of moderate to severe COPD and may contribute to disability, handicap, and premature mortality. In contrast to the lung impairment, which is largely irreversible, peripheral muscle dysfunction is potentially remediable with exercise training, nutritional intervention, oxygen, and anabolic drugs. Therapeutic success is often incomplete, however, and a better understanding of the mechanisms involved in the development of peripheral muscle dysfunction in COPD is needed to help develop innovative and more effective therapeutic strategies.
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Oxidative enzyme activities of the vastus lateralis muscle and the functional status in patients with COPD. Thorax 2000; 55:848-53. [PMID: 10992537 PMCID: PMC1745616 DOI: 10.1136/thorax.55.10.848] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
BACKGROUND Enzymatic and histochemical abnormalities of the peripheral muscle may play a role in exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). A study was undertaken to measure the mitochondrial enzyme activity of the vastus lateralis muscle in patients with COPD and to evaluate the relationship between enzyme activities and functional status. METHODS Fifty seven patients with COPD of mean (SD) age 66 (7) years with forced expiratory volume in one second (FEV(1)) 39 (15)% predicted and peak oxygen uptake (VO(2)) of 14 (4) ml/min/kg and 15 normal subjects of similar age were included in the study. Each subject performed a stepwise exercise test up to maximal capacity during which five-breath averages of VO(2) were measured. Muscle specimens were obtained by percutaneous needle biopsy of the vastus lateralis muscle and the activity of two mitochondrial enzymes (citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH)) was measured. The functional status of the patients was classified according to peak VO(2). RESULTS CS and HADH activities were markedly reduced in patients with COPD compared with normal subjects (22.3 (2.7) versus 29.5 (7.3) micromol/min/g muscle (p<0.0001) and 5. 1 (2.0) versus 6.7 (1.9) micromol/min/g muscle (p<0.005), respectively). The activity of CS decreased progressively with the deterioration in the functional status while that of HADH was not related to functional status. Using a stepwise regression analysis, percentage predicted functional residual capacity (FRC), the activity of CS, oxygen desaturation during exercise, age, and inspiratory capacity (% pred) were found to be significant determinants of peak VO(2). The regression model explained 59% of the variance in peak VO(2) (p<0.0001). CONCLUSIONS The oxidative capacity of the vastus lateralis muscle is reduced in patients with moderate to severe COPD compared with normal subjects of similar age. In these individuals the activity of CS correlated significantly with peak exercise capacity and independently of lung function impairment.
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Abstract
PURPOSE The peak work rate (Wpeak) measured during a progressive stepwise exercise test is commonly used to select the target training intensity for an exercise training program. In healthy subjects, a greater Wpeak is achieved when a faster rate of increase in work rate is used, whereas VO2 peak is independent of the rate of increase in work rate. This effect might be even more pronounced in chronic obstructive pulmonary disease (COPD) patients, in whom the VO2 kinetics during exercise are slower compared with healthy subjects. METHODS To investigate this, we studied 10 COPD patients (9 M/1 F, age: 65+/-5 yr [mean +/- SD], FEV1: 33+/-8%). They underwent, on separate days, three stepwise exercise tests on an ergocycle. For each test, increments of 5, 10, or 20 W x min(-1) were used in random order; the investigator was blinded as to which increment was used. VO2, VCO2, heart rate (HR), minute ventilation (VE), breathlessness and leg fatigue at rest, at each work rate, and at maximal capacity were obtained. RESULTS Wpeak averaged 40+/-13, 53+/-14, and 66+/-19 W for the 5-, 10-, and 20-W protocol, respectively (P < 0.001), whereas VO2 peak was comparable at 0.96+/-0.16, 1.02+/-0.18, and 1.03+/-0.20 L x min(-1). As the rate of increase in work rate became faster, the VO2/work rate relationship shifted to the right. This is exemplified by the VO2 at 40 W, which averaged 0.98+/-0.06, 0.90+/-0.09, and 0.83+/-0.10 L x min(-1) for the 5-, 10-, and 20-W protocol, respectively (P < 0.05). Similar observations were made for the relationship between HR, VE, and symptom scores, and work rate. There was no significant differences in peak values for HR and VE, and symptoms scores. CONCLUSIONS We conclude that the work rate incremental rate influences the Wpeak achieved, whereas the peak values for VO2, HR, VE, and symptom scores remain comparable. These findings have practical implications for the exercise evaluation of patients with COPD.
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Feasibility and efficacy of home exercise training before lung volume reduction. JOURNAL OF CARDIOPULMONARY REHABILITATION 1999; 19:235-41. [PMID: 10453430 DOI: 10.1097/00008483-199907000-00004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Exercise training is recommended before lung volume reduction surgery (LVRS) in patients with emphysema. Unfortunately, many of these patients are referred from remote areas where there is no available rehabilitation program. The authors evaluated the feasibility and efficacy of a minimally supervised home-based exercise training program. METHODS Twenty-three emphysematous patients (age 61 +/- 6, forced expiratory volume in 1 second = 29 +/- 7% predicted [mean +/- SD]) were recruited from our LVRS program. Measurements of pulmonary function, maximal and submaximal exercise capacity, 6-minute walking distance (6-MWD), muscle strength, and quality of life with the Chronic Respiratory Questionnaire were obtained before and after training. Home-based exercise training program included muscle exercises and aerobic training, and started with detailed teaching while the follow-up was ensured through weekly phone calls and a diary filled by each patient. RESULTS Significant increases in 6-MWD (P < 0.001), quality of life (P < 0.005), peak work rate (P < 0.05), peak oxygen consumption (P < 0.05), endurance time (P < 0.005), and muscle strength were observed in the home-based exercise training program. CONCLUSIONS Home-based exercise training for patients in preparation for LVRS was feasible, and induced significant improvement in exercise tolerance and quality of life.
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Abstract
This study was designed to further characterize peripheral skeletal muscle alterations in patients with chronic obstructive pulmonary disease (COPD) and to evaluate the possible relationship between myosin heavy chain (MyoHC) isoform expression and exercise tolerance in these individuals. MyoHC composition from biopsy of the vastus lateralis muscle was examined in 12 COPD patients (forced expiratory volume in one second (FEV1)=31+/-9% predicted, peak oxygen consumption (V'O2)=15+/-4 mL x kg(-1) x min(-1)) and 10 age-matched normal male subjects (peak V'O2=20+/-5 mL x kg(-1) x min(-1)). The proportion of MyoHC type I was smaller in COPD than in normals (27+/-17% versus 41+/-9%, p<0.05) with an increase in MyoHC type IIa (51+/-15% versus 39+/-9%, p<0.05) and the proportion of MyoHC type IIx being comparable between both groups. A significant relationship was found between peak V'Oo2 mL x kg(-1) x min(-1) and FEV1 % pred (r=0.91, p<0.0001) and the percentage of MyoHC type I (r=0.61, p=0.016). In stepwise multiple regression, only FEV1 % pred was found to be a significant determinant of peak V'O2 (p<0.0001). This variable explained 83% of the total variance of peak V'O2. In summary, this study showed considerable modifications in the phenotypic expression of the myosin heavy chain in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease. An independent effect of myosin heavy chain expression on exercise capacity was not found. These results suggest that chronic inactivity and muscle deconditioning may not be the sole factors explaining peripheral muscle dysfunction in patients with chronic obstructive pulmonary disease.
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Chronic obstructive pulmonary disease: capillarity and fiber-type characteristics of skeletal muscle. JOURNAL OF CARDIOPULMONARY REHABILITATION 1998; 18:432-7. [PMID: 9857275 DOI: 10.1097/00008483-199811000-00005] [Citation(s) in RCA: 138] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The purpose of this investigation was to compare capillarity and fiber type proportions of the vastus lateralis muscle between patients with chronic obstructive pulmonary disease (COPD) and healthy subjects. METHODS Fifteen male subjects were included in the study (8 COPD: 61.0 +/- 1.8 years [mean +/- SEM]; forced expiratory volume in 1 second 42.0 +/- 2.1% predicted; 7 N: age 54.0 +/- 1.1). Subjects were submitted to a symptom-limited maximal exercise test on ergocycle. After a transcutaneous biopsy of the vastus lateralis muscle, sections were cut 8 to 10 microns thick and stained with the Andersen method for capillarity and Stevens method for fiber typing. RESULTS Patients with COPD had a decrease in peak oxygen consumption compared with healthy subjects (1.2 +/- 0.1 versus 3.0 +/- 0.2 L/min). Number of capillaries per square millimeter was lower in patients with COPD versus healthy subjects (92.6 +/- 16.1 and 213.3 +/- 33.5, P < 0.001); percentages of fiber types were 43.5 +/- 5.5% type I, 56.5 +/- 5.5% type II in COPD, and 56.7 +/- 3.4% type I, 43.2 +/- 3.4% type II in healthy subjects (P < 0.05). In addition, capillaries/fiber ratio was 0.83 +/- 0.05 in COPD, and 1.56 +/- 0.10 in healthy subjects (P < 0.001). CONCLUSION As expected, patients with COPD showed a decrease in exercise capacity. The muscle analysis results indicate that patients with COPD have a greater proportion of type II fibers and a much lower capillaries/fiber ratio than normal subjects. We conclude that COPD adversely affects fiber type and capillarization of the lower limbs. This could be partly caused by deconditioning in these patients.
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Abstract
Peripheral muscle weakness is commonly found in patients with chronic obstructive pulmonary disease (COPD) and may play a role in reducing exercise capacity. The purposes of this study were to evaluate, in patients with COPD: (1) the relationship between muscle strength and cross-sectional area (CSA), (2) the distribution of peripheral muscle weakness, and (3) the relationship between muscle strength and the severity of lung disease. Thirty-four patients with COPD and 16 normal subjects of similar age and body mass index were evaluated. Compared with normal subjects, the strength of three muscle groups (p < 0.05) and the right thigh muscle CSA, evaluated by computed tomography (83.4 +/- 16.4 versus 109.6 +/- 15.6 cm2, p < 0.0001), were reduced in COPD. The quadriceps strength/thigh muscle CSA ratio was similar for the two groups. The reduction in quadriceps strength was proportionally greater than that of the shoulder girdle muscles (p < 0.05). Similar observations were made whether or not patients had been exposed to systemic corticosteroids in the 6-mo period preceding the study, although there was a tendency for the quadriceps strength/thigh muscle CSA ratio to be lower in patients who had received corticosteroids. In COPD, quadriceps strength and muscle CSA correlated positively with the FEV1 expressed in percentage of predicted value (r = 0.55 and r = 0. 66, respectively, p < 0.0005). In summary, the strength/muscle cross-sectional area ratio was not different between the two groups, suggesting that weakness in COPD is due to muscle atrophy. In COPD, the distribution of peripheral muscle weakness and the correlation between quadriceps strength and the degree of airflow obstruction suggests that chronic inactivity and muscle deconditioning are important factors in the loss in muscle mass and strength.
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Reexamining the associate degree curriculum. Assessing the need for community concepts. NURSING AND HEALTH CARE PERSPECTIVES 1998; 19:158-65. [PMID: 10446556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Significant changes taking place in health care delivery in our community in Louisiana have led faculty to reexamine the associate degree nursing curriculum. We recognized the trend toward the decreased need for inpatient care and the greater need for outpatient care and home care in the community. In addition, we noted the need for nursing care to assist the elderly in the management of chronic illness and provide education on health promotion and disease prevention.
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Metabolic and hemodynamic responses of lower limb during exercise in patients with COPD. J Appl Physiol (1985) 1998; 84:1573-80. [PMID: 9572801 DOI: 10.1152/jappl.1998.84.5.1573] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Premature lactic acidosis during exercise in patients with chronic obstructive pulmonary disease (COPD) may play a role in exercise intolerance. In this study, we evaluated whether the early exercise-induced lactic acidosis in these individuals can be explained by changes in peripheral O2 delivery (O2). Measurements of leg blood flow by thermodilution and of arterial and femoral venous blood gases, pH, and lactate were obtained during a standard incremental exercise test to capacity in eight patients with severe COPD and in eight age-matched controls. No significant difference was found between the two groups in leg blood flow at rest or during exercise at the same power outputs. Blood lactate concentrations and lactate release from the lower limb were greater in COPD patients at all submaximal exercise levels (all P < 0.05). Leg D02 at a given power output was not significantly different between the two groups, and no significant correlation was found between this parameter and blood lactate concentrations. COPD patients had lower arterial and venous pH at submaximal exercise, and there was a significant positive correlation between venous pH at 40 W and the peak O2 uptake (r = 0.91, P < 0.0001). The correlation between venous pH and peak O2 uptake suggests that early muscle acidosis may be involved in early exercise termination in COPD patients. The early lactate release from the lower limb during exercise could not be accounted for by changes in peripheral O2. The present results point to skeletal muscle dysfunction as being responsible for the early onset of lactic acidosis in COPD.
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LOSS OF MUSCLE TISSUE AND SKELETAL MUSCLE ATROPHY IN PATIENTS WITH COPD. Med Sci Sports Exerc 1998. [DOI: 10.1097/00005768-199805001-00559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Intensity of training and physiologic adaptation in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1997; 155:555-61. [PMID: 9032194 DOI: 10.1164/ajrccm.155.2.9032194] [Citation(s) in RCA: 277] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The applicability of high-intensity training and the possibility of inducing physiologic adaptation to training are still uncertain in patients with severe chronic obstructive pulmonary disease (COPD). The purposes of this study were to evaluate the proportion of patients with moderate to severe COPD in whom high-intensity exercise training (30-min exercise session at 80% of baseline maximal power output [Wmax]) is feasible, and the response to training in these patients. We also sought to evaluate the possible influence of disease severity on the training intensity achieved and on the development of physiologic adaptation following endurance training. Forty-two patients with COPD (age = 66 +/- 7 yr, FEV1 = 38 +/- 13% predicted, [mean +/- SD]) were evaluated at baseline and after a 12-wk endurance training program. Each evaluation included a stepwise exercise test on an ergocycle up to the individual maximal capacity during which minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), and arterial lactic acid concentrations were measured. The training consisted of 25 to 30-min exercise sessions on a calibrated ergocycle three times a week, with a target training intensity at 80% of Wmax. The training intensity was adjusted with the objective of reaching the target intensity, but also to ensure that the cycling exercise could be maintained for the specified duration. The training intensity sustained for the duration of each exercise session averaged 24.5 +/- 12.6, 51.7 +/- 17.4, 63.8 +/- 22.4, and 60.4 +/- 22.7% of Wmax at Weeks 2, 4, 10, and 12, respectively. High-intensity training was achieved in zero, three, five, and five patients at Weeks 2, 4, 10, and 12, respectively. A significant increase in VO2max and Wmax occurred with training (p < 0.0002). This improvement in exercise capacity was accompanied by a 6% and 17% reduction in VE and in arterial lactic acid concentration for a given work rate, respectively (p < 0.0001), suggesting that physiologic adaptation to training occurred. The intensity of training achieved, in % Wmax, was not influenced by the initial VO2max, age, or FEV1. The effects of training were compared in patients with an FEV1 > or = 40% or < 40% predicted. Percent changes in VO2max, Wmax, and VE, were significant and of similar magnitude for both groups, whereas the decrease in arterial lactic acid for a given work rate reached statistical significance only in those patients with an FEV1 > or = 40% predicted. We conclude that although most patients were unable to achieve high-intensity training as defined in this study, significant improvement in their exercise capacity was obtained and physiologic adaptation to endurance training occurred. The training intensity expressed as a percent of the individual maximum exercise capacity, and the relative effectiveness of training, were not influenced by the severity of airflow obstruction.
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Skeletal muscle adaptation to endurance training in patients with chronic obstructive pulmonary disease. Am J Respir Crit Care Med 1996; 154:442-7. [PMID: 8756820 DOI: 10.1164/ajrccm.154.2.8756820] [Citation(s) in RCA: 295] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The purpose of this study was to evaluate the physiologic responses to endurance training in patients with moderate to severe airflow obstruction by specifically looking at changes in skeletal muscle enzymatic activities. Eleven patients (age = 65 +/- 7 yr, mean +/- SD, FEV1 = 36 +/- 11% of predicted value, range = 24 to 54%) were evaluated before and after an endurance training program. Each evaluation included a percutaneous biopsy of the vastus lateralis and a stepwise exercise test on an ergocycle up to his/her maximal capacity. VE, VO2, VcO2, and serial arterial lactic acid concentration were measured during the exercise test. The activity of two oxidative enzymes, citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HADH), and of three glycolytic enzymes, lactate dehydrogenase, hexokinase, and phosphofructokinase was determined. The training consisted of 30-min exercise sessions on a calibrated ergocycle, 3 times a week for 12 wk. The aerobic capacity was severely reduced at baseline (VO2max = 54 +/- 12% of predicted) and increased by 14% after training (p < 0.05). For an identical exercise workload, there was a significant reduction in VE (34.5 +/- 10.0 versus 31.9 +/- 9.0 L/min, p < 0.05) and in arterial lactic acid concentration (3.4 +/- 1.3 versus 2.8 +/- 0.9 mmol/L, p < 0.01) after training. The lactate threshold also increased after training (p < 0.01) while the activity of the three glycolytic enzymes was similar at the two evaluations. In contrast, the activity of CS and HADH increased significantly after training (22.3 +/- 3.5 versus 25.8 +/- 3.8 mumol/min/g muscle for CS, p < 0.05, and 5.5 +/- 2.9 versus 7.7 +/- 2.5 mumol/min/g for HADH, p < 0.01). A significant inverse relationship was found between the percent changes in the activity of CS and HADH, and the percent changes in arterial lactic acid during exercise (p = 0.01). We conclude that endurance training can reduce exercise-induced lactic acidosis and improve skeletal muscle oxidative capacity in patients with moderate to severe chronic obstructive pulmonary disease (COPD).
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Oxidative capacity of the skeletal muscle and lactic acid kinetics during exercise in normal subjects and in patients with COPD. Am J Respir Crit Care Med 1996; 153:288-93. [PMID: 8542131 DOI: 10.1164/ajrccm.153.1.8542131] [Citation(s) in RCA: 327] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Early lactic acidosis during exercise and abnormal skeletal muscle function have been reported in chronic obstructive pulmonary disease (COPD) but a possible relationship between these two abnormalities has not been evaluated. The purpose of this study was to compare and correlate the increase in arterial lactic acid (La) during exercise and the oxidative capacity of the skeletal muscle in nine COPD patients (age = 62 +/- 5 yr, mean +/- SD, FEV1 40 +/- 9% of predicted) and in nine normal subjects of similar age (54 +/- 3 yr). Following a transcutaneous biopsy of the vastus laterialis, each subject performed a stepwise exercise test on an ergocycle up to his or her maximal capacity during which 5-breath averages of oxygen consumption (Vo2), and serial La concentration measurements were obtained. From the muscle biopsy specimen, the activity of two oxidative enzymes, citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HADH), and of three glycolytic enzymes, lactate dehydrogenase, hexokinase, and phosphofructokinase were determined. The La/Vo2 relationship during exercise was fitted by an exponential function in the form La = a + bvo2, where be represents the shape of the relationship. The activity of the oxidative enzymes was significantly lower in COPD than in control subjects (22.8 +/- 3.3 versus 36.8 +/- 8.6 mumol/min/g muscle for CS, and 3.1 +/- 1.1 versus 5.5 +/- 1.4 mumol/min/g for HADH, p < 0.0005) and the increase in lactic acid was steeper in COPD (b = 4.3 +/- 2.0 versus 2.1 +/- 0.2 for normal subjects, p = 0.0005). A significant inverse relationship was found between CS, HADH, and b. No difference was found between the two groups for the glycolytic enzymes. We conclude that in COPD the increase in arterial La during exercise is excessive, the oxidative capacity of the skeletal muscle is reduced, and that these two results are interrelated.
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Evaluation of the emphysematous patient. CHEST SURGERY CLINICS OF NORTH AMERICA 1995; 5:635-57. [PMID: 8574554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Most of the patients with emphysema complain of dyspnea and become limited in their activities during the course of the disease. Dyspnea is probably due to the change in the configuration of the thorax which is secondary to hyperinflation. The investigation should include the radiologic quantification of the structural abnormalities of the lungs and the functional consequences of these changes. When volume reduction of the lung is considered, the effects of hyperinflation on the mechanic of breathing and the ventilatory response to exercise has to be investigated rigorously.
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Functional outcome of patients with chronic obstructive pulmonary disease and exercise hypercapnia. Eur Respir J 1995; 8:1339-44. [PMID: 7489801 DOI: 10.1183/09031936.95.08081339] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Chronic hypercapnia is associated with a poor prognosis in chronic obstructive pulmonary disease (COPD). Some patients are normocapnic at rest but retain CO2 during exercise. The significance of this abnormality on the course of the disease is unknown. Sixteen stable COPD patients (13 males and 3 females, aged 60 +/- 5 yrs, mean +/- SD) who had previously undergone pulmonary function tests and progressive exercise testing with arterial blood sampling at rest and maximal capacity, entered the study. At first evaluation (E1), subjects were normocapnic at rest (arterial carbon dioxide tension (Pa,CO2): 4.9-5.7 kPa, (37-43 mmHg)) and all presented exercise-induced hypercapnia (end-exercise Pa,CO2 > 5.7 kPa (43 mmHg) with a minimal 0.5 kPa (4 mmHg) increase from resting value). The subjects were re-evaluated 24-54 months later (34 +/- 8 months) (second evaluation (E2)). At E2, forced expiratory volume in one second (FEV1) had decreased from 42 +/- 13 to 38 +/- 15% of predicted values, and mean resting Pa,CO2 had increased from 5.2 +/- 0.3 to 5.7 + 0.4 kPa. Maximal exercise capacity (Wmax) decreased between E1 and E2 from 76 +/- 30 to 56 +/- 22 W. Even if Wmax was lower at E2, end-exercise, Pa,CO2 was higher than at E1 (6.6 +/- 0.8 vs 6.4 +/- 0.5 kPa). At E2, eight subjects presented resting hypercapnia (group H), whilst the others remained normocapnic (Group N). Group H subjects had higher Pa,CO2, at Wmax than Group N and lower Wmax than Group N at E2.(ABSTRACT TRUNCATED AT 250 WORDS)
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Discordance between cardiopulmonary physiology and physical therapy. Chest 1993; 104:656. [PMID: 8339685 DOI: 10.1378/chest.104.2.656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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Abstract
We report the case of a 40-year-old woman who presented with neurologic complications of lymphomatoid granulomatosis after an initial pulmonary presentation. After treatment failure with immunosuppressive therapy, she responded dramatically to cranial radiation therapy without prior surgery.
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Abstract
The effects of lung resection on exercise capacity and perception of symptoms were studied in 47 patients aged 39-73 (mean 58.3) years. Twenty had a pneumonectomy and 27 a lobectomy, all for lung cancer. Forced expiratory volume, maximal inspiratory and expiratory pressures, and progressive maximal one minute incremental cycle ergometer exercise performance were measured before and after surgery. Breathlessness and leg discomfort were assessed with a modified Borg scale (0-10). Mean FEV1 decreased from 79% (SD 22%) to 53% (11%) of the predicted value after pneumonectomy and from 89% (22%) to 74% (18%) after lobectomy. Exercise capacity, measured as the highest work load completed, Wmax, decreased from 78% (25%) to 58% (28%) predicted in the pneumonectomy group and from 77% (21%) to 67% (20%) in the lobectomy group. There was only a weak relation between changes in FEV1 and changes in Wmax (r = 0.54, r2 = 0.30). The slope of the relation between the intensity of dyspnoea and work load or the intensity of dyspnoea and ventilation increased significantly after pneumonectomy, but not after lobectomy. Leg discomfort increased more rapidly when related to work load after both pneumonectomy and lobectomy. After resection dyspnoea was rarely the only limiting factor at maximal exercise. It is concluded that (1) change in FEV1 is a poor predictor of change in exercise capacity after lung resection; (2) pneumonectomy results in a 25% decrease in Wmax and in an appreciable increase in dyspnoea during exercise; (3) lobectomy has little or no effect on Wmax or the intensity of postoperative dyspnoea; (4) after both pneumonectomy and lobectomy leg discomfort makes an important contribution to exercise limitation.
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In situ right ventricular thrombus secondary to heparin induced thrombocytopenia. Can J Cardiol 1989; 5:308-10. [PMID: 2790577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Heparin induced thrombocytopenia (HIT) is a relatively common complication of heparin therapy, occurring in approximately 5% of patients treated with this drug. HIT may be associated with diffuse arterial and venous thrombosis. The case of a patient without underlying heart disease who developed a right ventricular thrombus and recurrent pulmonary emboli in association with and possibly as a complication of HIT is reported. Ancrod was used as an alternative to heparin for the time required to obtain an effective oral anticoagulant effect. The patient recovered completely and has no residual right ventricular thrombus.
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[The usefulness of an exercise test on a treadmill shortly after a myocardial infarction]. CANADIAN MEDICAL ASSOCIATION JOURNAL 1982; 126:1300-5. [PMID: 7074458 PMCID: PMC1863336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A program of reconditioning through walking was prescribed for 130 patients following an exercise test on a treadmill 3 weeks after a myocardial infarction. At 8 and at 12 weeks the patients again underwent an exercise test. The protocol is safe and permits the detection of angina, arrhythmias and dyspnea during the exercise, thus avoiding delays in treatment. The heart rate and the systolic blood pressure were measured at the end of each stage of the test and after 3 minutes of recuperation. About 75% of the patients attained the target energy output of the two submaximal tests (4 and 7 mets at 3 and 8 weeks respectively); an output of 7 mets permits a patient to resume his or her usual daily activities. The results of the tests at 3 and 12 weeks (the latter a maximal test) showed that the probability of an aerobic capacity of 7 mets or greater at 12 weeks is 86% if the 3-week test is completed. Clinical observations alone did not have the same prognostic value 3 weeks after the infarction.
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In vitro and in vivo effects of ethanol on the formation of endoperoxide metabolites in rat platelets. Lipids 1981; 16:583-8. [PMID: 6792442 DOI: 10.1007/bf02534903] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Preincubation of rat platelet-rich plasma (PRP) with ethanol resulted in dose-dependent inhibition of the formation of endoperoxide metabolites (EPM) when the PRP was aggregated by collagen suspension. The inhibition was manifested at concentrations normally attainable in blood of rats or humans by tolerable amounts of ethanol ingestion. Paradoxically, chronic ingestion of ethanol caused enhanced synthesis of EPM in platelets, indicating that the inhibitory effect of ethanol would be temporary, and that it can be reversed as soon as ethanol is eliminated. The level of arachidonic acid in platelet phospholipids of rats fed the ethanol diet was not different from that of the control, indicating that availability of immediate precursor acid would not be a factor for the enhanced synthesis of EPM in the ethanol group. This result suggested that platelets from rats subjected to chronic ethanol ingestion become hyperactive in synthesizing EPM through an unknown mechanism. When citrated whole blood was incubated in the presence of collagen suspension, amounts of EPM synthesized in the ethanol group were not different from those of the control group, but this was due to significant reduction of platelet counts in the ethanol group. Whether the effect of ethanol on other tissues would be similar to that on platelets is unknown. It is tempting to speculate that some of the pathological changes resulting from alcoholism might be mediated through the effect of ethanol on EPM formation.
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Heparin inhibits the formation of endoperoxide metabolites in rat platelets: aspirin-like activity. PROSTAGLANDINS AND MEDICINE 1981; 6:341-4. [PMID: 7280114 DOI: 10.1016/0161-4630(81)90065-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Amounts of thromboxane A2 (TXA2) synthesized during the collagen-induced aggregation was much higher in citrated PRP than in heaprinized PRP implying that heparin might inhibit the synthesis of endoperoxide metabolites besides its anticoagulant action. Preincubation of citrated PRP with heparin resulted in dose dependent inhibition of the formation of TXA2 and PGE2. At the high concentration, heparin also inhibited the aggregation of citrated platelets induced by collagen indicating that heparin possesses aspirin-like activity. The significance of this finding is that the antithrombotic effect of heparin is probably due to not only its anticoagulant effect but also inhibition of the formation of arachidonic acid metabolites by platelets.
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