Clinical research in chronic obstructive pulmonary disease: needs and opportunities

Early changes of lung function and structure in an elastase model of emphysema--a hyperpolarized 3He MRI study

Early changes of lung function and structure were studied in the presence of an elastase-induced model of emphysema in 35 Sprague-Dawley rats at mild (5 U/100 g) and moderate (10 U/100 g) severities. Lung ventilation was measured on a regional basis (at a planar resolution of 3.2 mm) by hyperpolarized 3He MRI at 5 and 10 wk after model induction. Subsequent to imaging, average alveolar diameter was measured from histological slices taken from the centers of each lobe. Changes of mean fractional ventilation, mean linear intercept, and intrasubject heterogeneity of ventilation were studied during disease progression. Mean fractional ventilation was significantly different between healthy controls (0.23 +/- 0.04) and emphysematous animals at both time points in the 10-unit group (0.06 +/- 0.02 and 0.12 +/- 0.05, respectively). Changes in average alveolar diameter were not statistically observable until the 10th wk between healthy (37 +/- 10 microm) and emphysematous rats (73 +/- 25 and 95 +/- 31 microm, for 5 and 10 units, respectively). Assessment of function-structure correlation suggested that the majority of the decline in fractional ventilation occurred in the first 5 wk, while enlargement of alveolar diameters appeared primarily between the 5th and 10th wk. A thresholding metric, based on the 20th percentile of fractional ventilation over the entire lung, was utilized to detect the onset of the disease with confidence, independent of whether the regional ventilation measurements were normalized with respect to the delivered tidal volume and estimated functional residual capacity of each individual rat.

Risk indexes for exacerbations and hospitalizations due to COPD

OBJECTIVE

The ability to predict exacerbations in patients with COPD might permit more rational use of preventive interventions. Our objective was to develop risk indexes for exacerbations and hospitalizations due to exacerbations that might be applied to the individual patient.

METHODS

Spirometry, demographics, and medical history were obtained at baseline in 1,829 patients with moderate-to-very severe COPD who entered a trial of inhaled tiotropium. Information about exacerbations and hospitalizations due to exacerbation was collected during the 6-month follow-up period. Analyses of first outcomes were modeled using univariable and multivariable Cox proportional hazards regressions.

RESULTS

During follow-up, 551 patients had at least one exacerbation and 151 patients had at least one hospitalization due to exacerbation. In the multivariable model for exacerbation, older age, percentage of predicted FEV(1), duration of COPD, a productive cough, antibiotic or systemic corticosteroid use for COPD in the prior year, hospitalization for COPD in the prior year, and theophylline use at baseline predicted a higher risk. In the multivariable model for hospitalization, older age, percentage of predicted FEV(1), unscheduled clinic/emergency department visits for COPD in the prior year, any cardiovascular comorbidity, and prednisone use at baseline were associated with greater risk. Both the exacerbation and the hospitalization models provided moderately good discrimination, the validated concordance indexes being 0.66 and 0.73, respectively. Methods for calculating risk in individual patients are provided.

CONCLUSIONS

Spirometry along with a few questions directed to the patient are strongly predictive of exacerbations and related hospitalizations over the ensuing 6 months.

Pathobiology of cigarette smoke-induced chronic obstructive pulmonary disease

Chronic obstructive pulmonary diseases (COPD), comprised of pulmonary emphysema, chronic bronchitis, and structural and inflammatory changes of small airways, is a leading cause of morbidity and mortality in the world. A better understanding of the pathobiology of COPD is critical for the developing of novel therapies, as the majority of patients with the disease have little therapeutic options at the present time. The pathobiology of COPD encompasses multiple injurious processes including inflammation (excessive or inappropriate innate and adaptive immunity), cellular apoptosis, altered cellular and molecular alveolar maintenance program, abnormal cell repair, extracellular matrix destruction (protease and anti-protease imbalance), and oxidative stress (oxidant and antioxidant imbalance). These processes are triggered by urban and rural air pollutants and active and/or passive cigarette smoke and modified by cellular senescence and infection. A series of receptor-mediated signal transduction pathways are activated by reactive oxygen species and tobacco components, resulting in impairment of a variety of cell signaling and cytokine networks, subsequently leading to chronic airway responses with mucus production, airway remodeling, and alveolar destruction. The authors provide an updated insight into the molecular and cellular pathobiology of COPD based on human and/or animal data.

The challenges of chronic obstructive pulmonary diseases (COPD)--a perspective

Chronic Obstructive Pulmonary Disease (COPD) is an inflammatory disease, primarily caused by cigarette smoke, which will soon become the third leading cause of death globally. Despite the importance of the problem, our real understanding of the biological underpinnings of COPD remains incomplete. Consequently, our first-line therapies, while helpful, are not yet as effective as they need to be. In this review, we will focus on these challenges and more, including the role of impaired tissue repair and adaptive immunity in disease pathogenesis, determining who may be at risk, describing COPD phenotypes and potential biomarkers. New ideas for chronic disease management and prevention of exacerbations will also be discussed. While much remains to be accomplished, meeting these challenges will bring rewards because what we learn will have implications for the understanding and treatment of chronic inflammatory diseases beyond COPD.

Clinical efficacy of OM-85 BV in COPD and chronic bronchitis: a systematic review

OM-85 BV is an immunomodulatory agent used for prevention of exacerbations in persons with chronic lung disease. We conducted a systematic review of OM-85 BV to evaluate its efficacy and safety. A systematic search for relevant articles was performed. Studies were included if they involved persons with chronic obstructive pulmonary disease or chronic bronchitis and were randomized to OM-85 BV or placebo. Investigators extracted data on study design, participant characteristics, and clinical outcomes. Thirteen trials involving 2066 individuals met inclusion criteria. Three trials enrolled an older, more homogenous population with chronic obstructive pulmonary disease. Utilizing quantitative pooled analysis in these studies, with one or more acute exacerbations as the endpoint, we found a non-statistically significant trend in favor of OM-85 BV [relative risk 0.83, 95% confidence interval 0.65-1.05]. Ten trials enrolled a heterogeneous population with chronic bronchitis. In these trials, exacerbation rates were less with OM-85 BV in 4 of 9 trials reporting this outcome. Varied results in the outcomes of hospitalization, symptom scores, and antibiotic or steroid use were found across studies. Withdrawals and adverse events were similar between OM-85 BV and placebo. While OM-85 BV is used to prevent exacerbations in persons with chronic lung disease, consistent evidence across multiple important outcomes does not exist to clearly demonstrate clinical benefit. Further randomized controlled trials enrolling large numbers of persons with well-defined COPD are necessary to confirm the effectiveness of this agent.

Prevalence and risk factors for chronic obstructive pulmonary disease according to symptoms and spirometry

The burden of COPD is quite high and its prevalence is increasing. Few data are available from Latin America. There is no consensus on what criteria should be the gold standard for the definition of this disease. A population-based study was carried out in a southern Brazilian city, including adults aged 40-69 years. The aim was to measure the prevalence of COPD according to several criteria. From the 1,046 subjects chosen from a multiple-stage sampling protocol, a sub-sample of 234 subjects was systematically selected to undergo spirometry. Percentages of COPD according to different criteria were: chronic bronchitis by questionnaire (7.8%); GOLD stage 0 (7.3%); fixed ratio (15.2%); GOLD stage II (9.9%); ERS (27.7%). The relationship among the three lung functional measurements showed that around 70% of all subjects had negative results with all three criteria, and around 10% were positive according to all three. Utilization of symptom-based or spirometry definitions of COPD provide different prevalence estimates. Use of different spirometric criteria also resulted in different percentages of COPD. According to spirometry, COPD was higher among men, elderly, those with low education and ex-smokers. On the other hand, current smokers were more likely to present symptoms of chronic bronchitis. The fixed ratio criterion is recommended when population-specific reference curves are not available, while the GOLD definition is recommended to evaluate severity of COPD.

["EXACO": four year follow-up of exacerbations in a cohort of patients with COPD]

EXACO is a French prospective observational epidemiological study. Chest physicians will enrol 1200 patients who will be followed up for 4 years. The aims of the study are to describe the exacerbations in COPD patients at different levels of severity and to confirm the existence of a sub-group of patients defined as frequent exacerbators. The clinical characteristics associated with this profile and the decline of FEV1 will be evaluated. A validation of the VSRQ scale will be performed. The data will be collected from chest physicians and by phone calls to the patients every three months.

Autologous transplantation of adipose tissue-derived stromal cells ameliorates pulmonary emphysema

Adipose tissue is a useful tool for management of most complex cardiothoracic problems, including the reinforcement of damaged lungs, and adipose tissue-derived stromal cells (ASCs) have been suggested to secrete hepatocyte growth factor (HGF), a multipotent regenerative factor that contributes to the repair process after lung injury. The goal of this study was to demonstrate the therapeutic impact of autologous transplantation of ASCs through HGF supplementation for the enhancement of alveolar repair in a rat model of emphysema. ASCs were isolated from inguinal subcutaneous fat pads and characterized by flow cytometry. Cultured ASC were found to secrete significantly larger amounts of HGF (15 112 +/- 1628 pg per 10(6) cells) than other angiogenic factors. Transplantation of ASCs into elastase-treated emphysema models induced a significant increase in endogenous HGF expression in lung tissues with a small amount of increase in other organs, with the high levels lasting for up to 4 weeks after transplantation. Further, alveolar and vascular regeneration were significantly enhanced via inhibition of alveolar cell apoptosis, enhancement of epithelial cell proliferation and promotion of angiogenesis in pulmonary vasculature, leading to restoration of pulmonary function affected by emphysema. These data suggest that autologous ASC cell therapy may have a therapeutic potential for pulmonary emphysema, through inducing HGF expression selectively in injured lung tissues.

COPD: racial disparities in susceptibility, treatment, and outcomes

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States and mortality continues to increase particularly among African Americans. Although this increase may be caused by changing smoking habits, some studies suggest that African Americans may be more susceptible to tobacco smoke than whites. Unlike other respiratory diseases for which there are significant published data on racial and ethnic disparities in disease outcomes, such information is notably lacking in the COPD literature. This article examines the available data concerning racial disparities in COPD susceptibility and care.

Quantitative Thin-Section CT Analysis of the Enlargement and Coalescence of Low-Attenuation Clusters in Patients with Emphysema

BACKGROUND

The analysis of the number and size of low-attenuation clusters has been adopted as quantitative computed tomography (CT) analysis of emphysema; however, a detailed examination has not been made on the relation between the number of various cluster sizes and the extent of emphysema.

OBJECTIVE

The aim of this study was to evaluate the relationship between the size and number of clusters on CT scans in patients with emphysema.

METHODS

This retrospective study included 31 emphysema patients. The number (LAN) and mean size (LAS) of clusters below -950 HU, and relative low-attenuation area below -950 HU (RA950) were calculated using an image-processing program. The size of clusters was divided into 3 categories, and the number in each size category was obtained as follows: small (sLAN 0.4-8 mm(2)), medium (mLAN 8.4-40 mm(2)), and large (lLAN >40 mm(2)). The relationships between the RA950 and sLAN, mLAN, or lLAN were evaluated. Patients were divided according to the extent of RA950 (>25% = severe emphysema, <25% = mild emphysema), and the relations between RA950 and LAN, and between RA950 and sLAN, mLAN, or lLAN were evaluated.

RESULTS

The sLAN decreased as RA950 increased (r = -0.477), whereas mLAN and lLAN increased (r = 0.421, and r = 0.819). In severe emphysema, sLAN and mLAN decreased as RA950 increased (r = -0.722, and r = -0.698). In mild emphysema, mLAN and lLAN increased as RA950 increased (r = 0.732, and r = 0.972).

CONCLUSIONS

The degree of the coalescence of the clusters depends on the size of clusters and the extent of emphysema. Quantitative CT analyses of clusters are helpful to elucidate the pathophysiology and progressive nature of emphysema.

Depression, anxiety and health status after hospitalisation for COPD: a multicentre study in the Nordic countries

Patients with chronic obstructive pulmonary disease (COPD) often report anxiety, depression and poor health status, not least if they experience repeated hospitalisations due to acute exacerbations. The aim of this study was to analyse the interrelationships between health status, anxiety, depression and physical status in COPD patients being discharged after hospitalisation. This was a prospective study of 416 patients in five university hospitals in each of the Nordic countries. Data included demographic information, lung function and co-morbidity. The Hospital Anxiety and Depression Scale and St. George's Respiratory Questionnaire (SGRQ) were applied to all patients. Both anxiety and depression were common among these patients. Anxiety was more common in women than in men (47% vs. 34%, P=0.009) and current smokers had a higher prevalence of both anxiety (54% vs. 37%) and depression (43% vs. 23%) than non-smokers (P<0.01). In general, the studied COPD patients had poor health status, especially those with anxiety, depression or both. Psychological status was independently related to all dimensions of SGRQ. Higher GOLD stages were significantly associated with increasing impairment in health status. In conclusion this multicentre study showed that anxiety and depression are common in patients with COPD, and, furthermore, that patients with psychological disorders have poor health status. Screening for depression and anxiety may help to identify patients with poor quality of life and an urgent need for intervention in order to improve their health status.

Use of Peak Oxygen Consumption in Predicting Physical Function and Quality of Life in COPD Patients

OBJECTIVE

To determine whether peak oxygen consumption (Vo(2)peak) adds to the power of FEV(1) in predicting physical function and quality of life in COPD patients.

DESIGN

Single-center cross-sectional study.

METHODS

Subjects included 291 COPD patients who completed pulmonary function testing, a graded exercise test, a 6-min walk, and stair climb test to assess physical function; a questionnaire assessing self-reported physical function; and a disease-specific, health-related quality-of-life questionnaire. Hierarchical multiple regression analysis was used to determine the contribution of Vo(2)peak in predicting physical function and quality of life after accounting for FEV(1).

RESULTS

After accounting for FEV(1), Vo(2)peak added significantly to the prediction of 6-min walk distance (R(2) increased by 0.395 [p < 0.005]); stair climb time (R(2) increased by 0.262 [p < 0.005]); self-reported function (R(2) increased by 0.109 [p < 0.005]); and health-related quality-of-life domain of mastery (R(2) increased by 0.044 [p < 0.005]). Only Vo(2)peak was found to significantly predict the health-related quality-of-life domain of fatigue (R(2) = 0.094 [p < 0.005]).

CONCLUSION

After controlling for FEV(1), Vo(2)peak adds significantly to the prediction of physical function and health-related quality-of-life domain of mastery in COPD patients. These results provide additional support for the use of Vo(2)peak in the multidimensional assessment of COPD patients.

Continuous oxygen monitoring--a better way to prescribe long-term oxygen therapy

STUDY OBJECTIVE

The purpose of this study was to determine if an oxygen prescription based on continuous oximetry monitoring, would result in an increased percentage of time spent within an SpO2 level between 88% and 92%.

METHODS

We conducted a prospective, cohort study in an outpatient, pulmonary setting in a tertiary care referral center, on 17 patients with stable chronic obstructive pulmonary disease (COPD) who had previously been prescribed long-term oxygen therapy. The patients were monitored for approximately 24h with a portable oximeter that recorded SpO2 and EKG readings. During the initial 24h of monitoring, the patients were on their previous oxygen prescription. Their oxygen prescription was then altered based on a predetermined protocol described below. The patients were then monitored for an additional 24h.

RESULTS

Sixteen patients completed the study. Based on the initial continuous oximetry, the median oxygen prescription was reduced from 2.5 to 1.2 L/min (P < 0.001). The oxygen prescription during exercise, rest, and sleep decreased from 3.0 +/- 0.9 to 1.8 +/- 1.3 L/min (P < 0.001), 2.2+/-0.4 to 0.8 +/- 0.7 L/min (P < 0.001), and 2.2 +/- 0.4 to 0.9 +/- 0.8 L/min (P < 0.001) respectively. After the oxygen prescription was adjusted, the percentage of the time that the SpO2 was between 88 and 92% increased from 24.8 +/- 21.7% to 52.8 +/- 25.0% (P = 0.001), but the percentage of time that the SpO2 was below 88% did not change significantly (2.8 +/- 6.1% to 4.3 +/- 8.1%).

CONCLUSIONS

This study demonstrates that an oxygen prescription based on continuous oximetry monitoring results in (1) a significant increase in the percentage of time that the SpO2 is between 88% and 92%, (2) a significant decrease in the amount of oxygen prescribed, (3) a slight increase in the amount of time that the SpO2 is below 88% that was not statistically significant.

It Takes My Breath Away END-STAGE COPD

End-stage chronic obstructive pulmonary disease (COPD) is a progressive illness without a cure. Because of its unpredictable trajectory, prognosis is difficult as, even in end-stage disease, patients may experience exacerbations and stabilization. There are many symptoms to manage until ultimately, respiratory function is severely compromised. Home care nurses provide much of the care at home and can make a difference in promoting advanced care planning and optimal comfort. This article reviews COPD, the management of subsequent symptoms, and the role of the home care nurse.

Doxycycline modulates nitric oxide production in murine lung epithelial cells

Many effective therapeutic agents exhibit effects that are different from their intended primary mode of action. Antibiotics such as doxycycline and erythromycin A are no exception. They also display anti-inflammatory activity. Using LA4 murine lung alveolar epithelial cells, effects of doxycycline and erythromycin A on inducible NO synthase (iNOS) NO production as well as iNOS protein and mRNA production were investigated. Induction of iNOS was accomplished by treatment with cytomix (TNF-alpha, IL-1beta, and IFN-gamma each at 5 ng/ml). Production of NO or iNOS was not detected in controls with or without erythromycin A. In the presence of cytomix, erythromycin A did not decrease NO, nitrite, iNOS protein, or mRNA production. In contrast, doxycycline caused a dose-dependent decrease in NO, nitrite, iNOS protein, and mRNA production in cytomix-treated cells. Doxycycline at 30 mug/ml produced a 90% decrease in nitrite and NO production and a 52% decrease in iNOS mRNA transcription compared with cytomix treatment alone. Actinomycin D treatment suggests that doxycycline decreases stability of iNOS mRNA in cytomix-treated cells. To determine a mechanism for the decrease in iNOS expression, NF-kappaB and AP-1 transcription regulatory systems and p38 MAPK were examined. Doxycycline treatment gave no statistically significant change in NF-kappaB activation but did decrease p38 MAPK protein in cytomix-treated cells by 50%, suggesting that p38 MAPK may be responsible for stabilization of iNOS mRNA. These results demonstrate that doxycycline decreases NO production from iNOS by destabilization of iNOS mRNA via decreased expression of p38 MAPK.

Identification of P311 as a potential gene regulating alveolar generation

Smoking-related destructive lung diseases such as chronic obstructive pulmonary disease (COPD) and emphysema are a major cause of morbidity and mortality worldwide. The immediate cause of emphysema is the obliteration of alveoli that are key functional units of the lungs where gas exchange takes place. Alveolar generation/regeneration under normal and pathologic conditions is a poorly understood process, but may hold the key to treatment of human emphysema. We used suppression subtractive hybridization to identify genes that may control alveolar generation during periods of pre- and postnatal active alveolar development. P311, a putative neuronal protein originally identified for its high expression in late-stage embryonic brain, was highly differentially expressed during periods of active distal lung morphogenesis. Quantitative real-time RT-PCR showed that the expression of P311 is developmentally regulated, with peak levels occurring during saccular and alveolar formation. Intriguingly, P311 gene expression was significantly decreased in lungs of individuals with emphysema compared with control subjects. Consistent with a role for this gene in alveolar formation, inhibition of alveolization by dexamethasone treatment in vivo resulted in decreased expression of P311. Together our data suggest that P311 expression is tightly regulated during the critical periods of alveolar formation, and that under pathologic conditions, its relative absence may contribute to failure of alveolar regeneration and lead to the development of human emphysema.

Neurohumoral activation as a link to systemic manifestations of chronic lung disease

COPD is a major cause of death and disability worldwide. Treatment of COPD improves lung function but is unlikely to slow the steady downhill course of the disease or reduce mortality. In COPD, numerous abnormalities can be found outside the lung. These include systemic inflammation, cachexia, and skeletal muscle dysfunction. Thus, COPD has been called a systemic disease. Convincing data demonstrate that COPD causes neurohumoral activation. By precedents derived from chronic heart failure and other diseases characterized by neurohumoral activation, we propose that the negative consequences of neurohumoral activation, namely inflammation, cachexia, effects on ventilation, and skeletal muscle dysfunction, give rise to a self-perpetuating cycle that contributes to the pathogenesis of COPD, and which may involve respiratory muscle dysfunction as well as systemic inflammation. This concept may further help explain the increased cardiovascular morbidity and mortality in COPD patients. Currently, little is known about the effect of treatments directed at neurohumoral activation and COPD. As this aspect of COPD becomes better understood, new insights may direct novel therapeutic approaches.

Physician and patient perceptions in COPD: the COPD Resource Network Needs Assessment Survey

PURPOSE

Chronic obstructive pulmonary disease (COPD), the fourth leading cause of death in the United States, has received disproportionately little attention from physicians and institutions. National data are lacking on patient and physician perceptions of and patterns of care for COPD.

METHODS

Linked surveys were administered to national samples of patients with COPD, primary care physicians, and pulmonologists to evaluate perceptions of COPD severity and quality of life, attitudes about COPD, health insurance barriers to COPD care, sources of information, and knowledge about COPD diagnosis and treatment.

RESULTS

Overall, 1023 patients with COPD and 1051 primary care physicians and pulmonologists responded to the surveys. Despite experiencing significant symptoms and high health care use, the majority of patients were satisfied with their care. Eighty-eight percent of physicians agreed with the statement that COPD is a "self-inflicted" disease, and more than one third were nihilistic about the treatment of patients who continued to smoke. Patients and physicians reported that insurance problems impeded access to therapies. Patients were generally uninformed about COPD; 54% of primary care physicians were aware of any COPD guidelines. Both patient and physician surveys demonstrated continued confusion about the diagnosis of COPD and treatment choices. There was frequent use of regular oral steroids despite demonstrated lack of efficacy and under-use of pulmonary rehabilitation despite proven efficacy.

CONCLUSIONS

Patients with COPD have a high prevalence of activity limitations. Although most physicians believed that proper treatment can slow progression, inadequate knowledge and poor adherence to practice guidelines, together with insurance impediments, negatively impact COPD care.

Decreased expression of TGF-beta type II receptor in bronchial glands of smokers with COPD

BACKGROUND

The role of transforming growth factor-beta1 (TGF-beta1) in chronic obstructive pulmonary disease is still controversial, but it has been proposed that it may protect from mucus hypersecretion since it is able to downregulate mucin production. A study was undertaken to investigate the expression of TGF-beta1 and its type II receptor (TGF-beta RII) in the bronchial glands of smokers with COPD.

METHODS

The expression of TGF-beta(1) and TGF-beta RII were examined immunohistochemically in the bronchial glands of 24 smokers undergoing lung resection for solitary peripheral nodules: 12 with airflow limitation (smokers with COPD) and 12 with normal lung function.

RESULTS

The expression of TGF-beta1 in bronchial glands was similar in the two groups of subjects while that of TGF-beta RII was lower in smokers with COPD than in smokers with normal lung function (p=0.004). TGF-beta RII expression was inversely correlated with the values of Reid's index, a measure of gland size (p=0.02, r=-0.50).

CONCLUSIONS

In the bronchial glands of smokers with COPD there is decreased expression of TGF-beta RII which is associated with bronchial gland enlargement. These findings support the view that the absence of TGF-beta signalling may induce structural changes in the bronchial glands which, in turn, may promote mucus hypersecretion.

Knowledge about asthma and COPD: associations with sick leave, health complaints, functional limitations, adaptation, and perceived control

We sought to investigate associations between knowledge about the disease and sick leave, health complaints, functional limitations, adaptation and perceived control. Patients with asthma (n = 101) and COPD (n = 64) underwent lung function tests and completed questionnaires. In addition, all were asked the question: 'what is the diagnosis of your disease?', with the response categories: 'asthma' and 'COPD (chronic bronchitis or emphysema)'. Thirty-five percent of the asthma patients and 30% of the COPD patients did not know their correct diagnosis. Sick leave was not associated with knowledge about the disease in asthma and COPD. In asthma, much knowledge about management of the disease was associated with better adaptation (P = 0.01) and less perceived control over health by external factors (P = 0.02). Knowing the correct diagnosis was associated with less control over health by powerful others (P = 0.02). For COPD, more knowledge about management of the disease was associated with better adaptation (P = 0.02) and less control over health by internal factors (P = 0.01). Knowing the correct diagnosis was associated with less control over dyspnea at work (P = 0.01).

Markers of disease severity in chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES

Diagnosis and assessment of treatment effect in chronic obstructive pulmonary disease (COPD) have relied primarily on the examination of a complex set of symptoms and the use of spirometry. However, these methods require long periods of assessment to determine whether patients show clinically relevant improvements after intervention. We therefore wanted to determine how existing clinical and laboratory measures change with COPD severity and identify disease markers that can serve as better endpoints for diagnosis and assessment of COPD progression and treatment effect.

METHODS

Using standard COPD keywords and terms, we searched PubMed, ISI Web of Science, and Cochrane Review databases for retrospective and prospective clinical studies published since 1966. We identified 652 studies (n = 146,255) from 1978 to September 2003 based on the availability of spirometric and demographic data, investigation of possible markers, absence of acute exacerbations and co-morbidities, and the withdrawal of standard COPD medication. Central tendencies and dispersions of subject baseline measures were collected according to study sample size, smoking status, and mild, moderate and severe COPD stages. A fixed effect meta-analysis was then conducted on each measure at various disease stages.

RESULTS

Arterial oxygen tension, sputum neutrophils and IL-8, and serum TNF-alpha and C-Reactive Protein showed a trend toward separation between COPD stages. Other measures such as pack-years and St George's Respiratory Questionnaire only distinguished between disease and disease-free states.

CONCLUSIONS

We observed little separation between disease stages for many measures used in COPD diagnosis and clinical trials. This demonstrates the poor sensitivity of such endpoints to define a patient's clinical status and to quantify treatment effect. Therefore, we recommend that longitudinal studies and disease modelling be the primary methods for assessing whether potential markers of disease progression can be used for COPD diagnosis and clinical trials.

Using hierarchical clustering methods to classify motor activities of COPD patients from wearable sensor data

Background

Advances in miniature sensor technology have led to the development of wearable systems that allow one to monitor motor activities in the field. A variety of classifiers have been proposed in the past, but little has been done toward developing systematic approaches to assess the feasibility of discriminating the motor tasks of interest and to guide the choice of the classifier architecture.

Methods

A technique is introduced to address this problem according to a hierarchical framework and its use is demonstrated for the application of detecting motor activities in patients with chronic obstructive pulmonary disease (COPD) undergoing pulmonary rehabilitation. Accelerometers were used to collect data for 10 different classes of activity. Features were extracted to capture essential properties of the data set and reduce the dimensionality of the problem at hand. Cluster measures were utilized to find natural groupings in the data set and then construct a hierarchy of the relationships between clusters to guide the process of merging clusters that are too similar to distinguish reliably. It provides a means to assess whether the benefits of merging for performance of a classifier outweigh the loss of resolution incurred through merging.

Results

Analysis of the COPD data set demonstrated that motor tasks related to ambulation can be reliably discriminated from tasks performed in a seated position with the legs in motion or stationary using two features derived from one accelerometer. Classifying motor tasks within the category of activities related to ambulation requires more advanced techniques. While in certain cases all the tasks could be accurately classified, in others merging clusters associated with different motor tasks was necessary. When merging clusters, it was found that the proposed method could lead to more than 12% improvement in classifier accuracy while retaining resolution of 4 tasks.

Conclusion

Hierarchical clustering methods are relevant to developing classifiers of motor activities from data recorded using wearable systems. They allow users to assess feasibility of a classification problem and choose architectures that maximize accuracy. By relying on this approach, the clinical importance of discriminating motor tasks can be easily taken into consideration while designing the classifier.

Adrenomedullin regenerates alveoli and vasculature in elastase-induced pulmonary emphysema in mice

RATIONALE

Adrenomedullin, a potent vasodilator peptide, regulates cell growth and survival. However, whether adrenomedullin contributes to lung regeneration remains unknown.

OBJECTIVES

To investigate whether adrenomedullin influences the kinetics of bone marrow cells, and whether adrenomedullin promotes regeneration of alveoli and vasculature and thereby improves lung structure and function in elastase-induced emphysema in mice.

METHODS

Adrenomedullin or vehicle was randomly administered to C57BL/6 mice for 5 days. We counted the numbers of mononuclear cells and stem cell antigen-1-positive cells in circulating blood. After intratracheal injection of elastase or saline, mice were randomized to receive continuous infusion of adrenomedullin or vehicle for 14 days. Functional and histologic analyses were performed 28 days after treatment.

RESULTS

Twenty-eight days after elastase injection, destruction of the alveolar walls was observed. However, adrenomedullin infusion significantly inhibited the increase in lung volume, static lung compliance, and mean linear intercept in mice given elastase. Adrenomedullin increased the numbers of mononuclear cells and stem cell antigen-1-positive cells in circulating blood. Adrenomedullin significantly increased the number of bone marrow-derived cells incorporated into the elastase-treated lung. Some of these cells were positive for cytokeratin or von Willebrand factor. Infusion of adrenomedullin after the establishment of emphysema also had beneficial effects on lung structure and function. In vitro, addition of adrenomedullin attenuates elastase-induced cell death in alveolar epithelial cells and endothelial cells.

CONCLUSIONS

Adrenomedullin improved elastase-induced emphysema at least in part through mobilization of bone marrow cells and the direct protective effects on alveolar epithelial cells and endothelial cells.

NO2-induced airway inflammation is associated with progressive airflow limitation and development of emphysema-like lesions in C57BL/6 mice

The major features of chronic obstructive pulmonary disease (COPD) comprise a not fully reversible airflow limitation associated with an abnormal inflammatory response, increased mucus production and development of emphysema-like lesions. Animal models that closely mimic these alterations represent an important issue for the investigation of pathophysiological mechanisms. Since most animal models in this area have focused on specific aspects of the disease, we aimed to investigate whether exposure of C57BL/6 mice to nitrogen dioxide (NO2) may cause a more complex phenotype covering several of the characteristics of the human disease. Therefore, mice were exposed to NO2 for 14h each day for up to 25 days. Initial dose response experiments revealed the induction of a significant inflammatory response at a dose of 20 ppm NO2. Mice developed progressive airway inflammation together with a focal inflammation of the lung parenchyma characterized by a predominant influx of neutrophils and macrophages. In addition, goblet cell hyperplasia was detected in the central airways and increased collagen deposition was found in the lung parenchyma. NO2-exposed mice developed emphysema-like lesions as indicated by a significantly increased mean linear intercept as compared to control mice. Finally, the assessment of lung functional parameters revealed the development of progressive airway obstruction over time. In conclusion, our data provide evidence that the inflammatory response to NO2 exposure is associated with increased mucus production, development of airspace enlargement and progressive airway obstruction. Thus, NO2-exposed mice may serve as a model to investigate pathophysiological mechanisms that contribute to the development of human COPD.

Interventions to prevent chronic obstructive pulmonary disease exacerbations

Exacerbations of chronic obstructive pulmonary disease (COPD) have a profound effect on the patient's health status and decline in lung function; they also impose a significant burden on healthcare resource utilization. Prevention and treatment of exacerbations is listed by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) as among the major objectives of COPD management, and it is therefore an important outcome measure when studying any new agent. This article discusses pharmacologic therapy and other measures for preventing exacerbations and hospitalizations due to exacerbations of COPD.

The prediction of small airway dimensions using computed tomography

Chronic obstructive pulmonary disease is characterized by destruction of the lung parenchyma and/or small airway narrowing. To determine whether the dimensions of relatively large airways assessed using computed tomography (CT) reflect small airway dimensions measured histologically, we assessed these variables in nonobstructed or mild to moderately obstructed patients having lobar resection for a peripheral tumor. For both CT and histology, the square root of the airway wall area (Aaw) was plotted versus lumen perimeter to estimate wall thickness. The wall area percentage was calculated as wall area/lumen area + wall area x 100. Although CT overestimated Aaw, the slopes of the relationships between the square root of Aaw and internal perimeter (Pi) measured with both techniques were related (CT slope = 0.2059 histology slope + 0.1701, R2 = 0.32, p < 0.01). The mean wall area percentage measured by CT for airways with a Pi of greater than 0.75 cm predicted the mean dimensions of the small airways with an internal diameter of 1.27 mm (R2 = 0.57, p < 0.01). We conclude that CT measurements of airways with a Pi of 0.75 cm or more could be used to estimate the dimensions of the small conducting airways, which are the site of airway obstruction in chronic obstructive pulmonary disease.

A Lung Tissue Bank for Gene Expression Studies in Chronic Obstructive Pulmonary Disease

A bank of surgically resected human lung tissues frozen at -70 degrees C after being inflated with support medium for cutting frozen tissue and a separate group inflated with fixative and embedded in paraffin has been established for studies of chronic obstructive pulmonary disease. The present report concerns the quality of RNA that can be extracted from these frozen and fixed tissue samples and from cells obtained from them by laser capture microdissection. The results show that the RNA yield was 257+/-183 ng/mg and 77+/-56 ng/mg from randomly selected frozen and paraffin-embedded tissue, respectively. Intact 18S and 28S rRNA subunits were present in 11/23 frozen and 2/6 paraffin-embedded specimens. The 375-bp actin and 296-bp glyceraldehdye 3-phosphate dehydrogenase targets were amplified by reverse transcription-PCR from both sources and the 983-bp glyceraldehdye 3-phosphate dehydrogenase and 499-bp nonhousekeeping integrin-linked kinase targets from frozen tissue. The minimal amount of RNA required for reverse transcription-PCR of 296-bp glyceraldehdye 3-phosphate dehydrogenase target was 29 pg from frozen tissue when RNA subunits were present and 144 pg when these subunits were absent compared to 0.8 ng from paraffin-embedded tissue. Ten laser pulses were required to laser capture sufficient cells from frozen tissue to detect amplification of the 375-bp actin target while more pulses were required for equivalent amplification from paraffin-embedded tissue. Storage time had no detectable effect on RNA quality. We conclude that both frozen and paraffin-embedded tissues as well as laser-captured cells are suitable for gene expression studies but frozen tissue offered greater sensitivity.

Factors Associated With Outcomes of Acute Exacerbations of Chronic Obstructive Pulmonary Disease

The purpose of this article is to provide a general review of the current literature on the factors associated with the outcomes of hospitalizations, survival and health-related quality of life in acute exacerbations of chronic obstructive pulmonary disease (AECOPD), highlighting the limitations and the complexities in interpretation of the results of current studies. There is no consensus definition for AECOPD; onsets may be difficult to define and the determination of duration elusive. The prevalence of acute exacerbations of COPD (AECOPD) in the community appears to be underestimated as exacerbations are underreported by patients and their doctors. Hospitalization for COPD is due mainly to severe AECOPDs which drive the cost of care. There are few longitudinal epidemiological studies on factors associated with hospitalizations for AECOPD. The results of current studies do not allow clear differentiation between associations that are predictors of event, the consequences of the event, or indicators of severity. Strategies to reduce severe exacerbations of COPD include pharmacological treatment, vaccinations, pulmonary rehabilitation, and home care programs. The optimal strategy for the reduction of hospitalization in COPD remains unclear. Long-term interventional studies are needed to provide clearer information for the prevention of exacerbations and hospitalizations in COPD.

Influence of calibration on densitometric studies of emphysema progression using computed tomography

The fundamental importance of calibration for any measuring device is indisputable, but computed tomography (CT) calibration in longitudinal lung densitometry studies is largely unexplored. Although the validity of CT as a measure of emphysema has been confirmed in cross-sectional studies, there are limited data on long-term reproducibility, and this is critically important for validating its use as an outcome measure in therapeutic trials. A general understanding of the strengths and pitfalls of CT densitometry is critical for physicians reviewing the published literature using this methodology. In our study of 57 patients with alpha-1 antitrypsin deficiency (phenotype PiZ), progression of voxel index determined from three successive annual scans acquired with a fully calibrated scanner was intimately associated with changes in CT air densitometry, sampled from patient images. Images were therefore reanalyzed, using a correction technique validated in phantom studies that adjusted for changes in measured air density, and the reliability of the voxel index as a measure of emphysema progression was improved. Comparison of adjusted voxel index thresholds indicated the optimum threshold was -950 Hounsfield units. Internal air calibration is therefore critical in longitudinal and multicenter lung densitometry studies of emphysema and incorporation of a correction factor is essential for quantitative image analysis.

Extracellular regulated kinase/mitogen activated protein kinase is up-regulated in pulmonary emphysema and mediates matrix metalloproteinase-1 induction by cigarette smoke

The interstitial collagenase matrix metalloprotein-ase-1 (MMP-1) is up-regulated in the lung during pulmonary emphysema. The mechanisms underlying this aberrant expression are poorly understood. Although cigarette smoking is the predominant cause of emphysema, only 15-20% of smokers develop the disease. To define the signaling pathways activated by smoke and to identify molecules responsible for emphysema-associated MMP-1 expression, we performed several in vitro and in vivo experiments. In this study, we showed that cigarette smoke directly induced MMP-1 mRNA and protein expression and increased the collagenolytic activity of human airway cells. Treatment with various chemical kinase inhibitors revealed that this response was dependent on the extracellular regulated kinase-1/2 (ERK) mitogen activated protein kinase pathway. Cigarette smoke increased phosphorylation of residues Thr-202 and Tyr-204 of ERK in airway lining cells and alveolar macrophages in mice at 10 days and 6 months of exposure. Moreover, analysis of lung tissues from emphysema patients revealed significantly increased ERK activity compared with lungs of control subjects. This ERK activity was evident in airway lining and alveolar cells. The identification of active ERK in the lungs of emphysema patients and the finding that induction of MMP-1 by cigarette smoke in pulmonary epithelial cells is ERK-dependent reveal a molecular mechanism and potential therapeutic target for excessive matrix remodeling in smokers who develop emphysema.