Desmosine as a biomarker of elastin degradation in COPD: current status and future directions.

Desmosine (DES) and isodesmosine (IDES) are two unusual, tetrafunctional, pyridinium ring-containing amino acids involved in elastin cross-linking. Being amino acids unique to mature, cross-linked elastin, they are useful for discriminating peptides derived from elastin breakdown from precursor elastin peptides. According to these features, DES and IDES have been extensively discussed as potentially attractive indicators of elevated lung elastic fibre turnover and markers of the effectiveness of agents with the potential to reduce elastin breakdown. In the present manuscript, immunology-based and separation methods for the evaluation of DES and IDES are discussed, along with studies reporting increased levels of urine excretion in chronic obstructive pulmonary disease (COPD) patients with and without alpha(1)-antitrypsin deficiency. The results of the application of DES and IDES as surrogate end-points in early clinical trials in COPD are also reported. Finally, recent advances in detection techniques, including liquid chromatography tandem mass spectrometry and high-performance capillary electrophoresis with laser-induced fluorescence, are discussed. These techniques allow detection of DES and IDES at very low concentration in body fluids other than urine, such as plasma or sputum, and will help the understanding of whether DES and IDES are potentially useful in monitoring therapeutic intervention in COPD.

Report of a workshop: quantitative computed tomography scanning in longitudinal studies of emphysema.

It has been reported that quantitative computed tomography (CT) scanning of the lungs showed decreased progression of emphysema in a randomised clinical trial in patients with severe alpha1-antitrypsin (alpha1-AT) deficiency receiving monthly intravenous augmentation therapy with human alpha1-AT. Comparable results were not obtained using rate of decline of forced expiratory volume in one second. Accordingly, the Alpha-1 Foundation convened a workshop to explore the feasibility of using quantitative CT data as a primary outcome variable in trials of drugs for treating alpha1-AT deficiency. This report reviews the following: the principles for the use of modern CT scanners for quantifying emphysema; the methods and data on validation by comparison with measurements of severity of emphysema in inflation-fixed specimens of lungs; and the possibility of decreasing radiation dosage from CT to make it safe and ethically possible to use CT in longitudinal studies. The workshop concluded that it is feasible, safe and ethically possible to use computed tomography in longitudinal studies of emphysema. It recommended that the primary end-point should be a significant shift in the 15th percentile of lung density.

Scanning tunneling microscopy and spectroscopy investigations of QCA molecules.

Quantum-dot cellular automata (QCA), a computation paradigm based on the Coulomb interactions between neighboring cells. The key idea is to represent binary information, not by the state of a current switch (transistor), but rather by the configuration of charge in a bistable cell. In its molecular realization, the QCA cell can be a single molecule. QCA is ideally suited for molecular implementation since it exploits the molecule's ability to contain charge, and does not rely on any current flow between the molecules. We have examined using an UHV-STM some of the QCA molecules like silicon phthalocyanines and Fe-Ru complexes on Au (111) and Si (111) surfaces, which are suitable candidates for the molecular QCA approach.

Urinary desmosine excretion in acute exacerbations of COPD: a preliminary report.

Desmosine (DES) is an elastin-derived, cross-link amino acid, which is not metabolized; hence, its urinary levels reflect elastin breakdown. We hypothesized that elastin degradation should increase as a result of increased lung inflammation during an acute exacerbation of COPD and should decrease after recovery. To test this hypothesis we measured DES in three urine samples from nine COPD subjects during the first 5 days of an acute exacerbation and at 2 months after recovery. We also measured forced expiratory volume in 1 sec (FEV1) to monitor the effects ofthe exacerbation on ventilatory function. The mean (SD) FEV1 was 45 (15)% predicted during the exacerbation and 57.8 (16)% predicted 2 months later (P=0.00001). The mean (SD) DES excretion was 25.3 (9) microg g(-1) creatinine at day 1;23.5 (9) at day 3 and 24 (9) at day 5 of the exacerbation. The mean (SD) urinary DES excretion 60 days after discharge was 20.9 (7) microg g(-1) creatinine (P=0.049) in comparison with the mean of the three acute-phase values. The size of the increase in desmosine excretion during exacerbation is small, 3.2 microg g(-1) creatinine or 16% of the recovery desmosine value. We conclude that there is a small but statistically significant increase in lung elastin breakdown in the body during an acute exacerbation of COPD.

XAFS and X-ray reflectivity study of III-V compound native oxide/GaAs interfaces.

Fluorescence-mode XAFS has been used to study the local environment about chosen atomic species such as Ga and As in bulk oxide Al(1-x)Ga(x)As (x=0.96) and at the interface between thin (300 A) oxidized Al(1-x)Ga(x)As (x=0.94) film and GaAs substrate in total external-reflection mode. X-ray reflectivity experiments have also been employed to investigate the density profile of the oxide film on a GaAs substrate revealing the density profile as a function of depth. It is important to find out how the As is incorporated at the interface, the interfacial strain, and related local structural parameters for understanding that may be central in developing high performance III-V MOSFET devices.

Limitations of randomized clinical trials for evaluating emerging operations: the case of lung volume reduction surgery.

Although unanswered questions remain, scores of observational studies and several small randomized clinical trials (RCTs) indicate that lung volume reduction surgery (LVRS) offers safe and effective palliation for a relatively well defined subset of patients with advanced emphysema. Nonetheless, Medicare and other insurers stopped reimbursement for the procedure. Subsequently, two multicenter RCTs on LVRS, the National Emphysema Treatment Trial (NETT) and the Overholt-BlueCross Emphysema Surgery Trial (OBEST), were launched with the stipulation that the procedure would not be paid for outside these trials. Thus access to LVRS has been denied to patients who could benefit but do not wish to participate in an RCT. Emerging operations, unlike new drugs or devices, pass through evolutionary changes and frequently fail to produce data that meet the scientific rigor required by randomized studies. In such a setting, the observational approach is more appropriate. Indeed, almost all operations in the present surgical armamentarium have been evaluated and have evolved through observational studies without the use of RCTs. By the time new operations are standardized and qualify for RCTs, benefits for certain patients may be demonstrated and randomization could involve unacceptable health hazards. Patients from this population should be offered the choice between participating in RCTs and having the operation outside the study. Imposition of financial restrictions that bars access to a therapy with known benefit is a questionable practice.

Short-term supplementation therapy does not affect elastin degradation in severe alpha(1)-antitrypsin deficiency. The American-Italian AATD Study Group.

We evaluated the ability of intravenous supplementation therapy with alpha(1)-antitrypsin (AAT) to reduce the rate of urinary excretion of desmosine (DES), a specific marker of elastin degradation, in eight men and four women with emphysema due to severe, congenital deficiency of AAT (range 17-69 mg/dl). Nine were former cigarette smokers, two were current smokers, and one reported never smoking; their mean age was 54 (SD 12) yr and their mean FEV(1) was 41 (18%) of predicted. Urinary DES was measured by isotope dilution and HPLC. Prior to the start of AAT supplementation, mean DES excretion was 13.0 (5.0) microg/g creatinine, 73% higher than in healthy nonsmokers. During 8 wk of supplementation therapy, mean urinary DES excretion was 13.0 (5.9) microg/g creatinine, unchanged from the baseline period (p = 0.85 by repeated measures ANOVA). We conclude that baseline levels of elastin degradation in emphysematous patients with severe AAT deficiency were abnormally high and that 8 wk of AAT supplementation therapy did not appreciably reduce the rate of elastin degradation. These findings raise the possibilities that protective levels of AAT in the lungs are insufficient or that elastin degradation in the lungs of these subjects is not dependent upon neutrophil elastase at this time.

Remodeling of alveolar walls after elastase treatment of hamsters. Results of elastin and collagen mRNA in situ hybridization.

Treatment of hamster lungs with porcine pancreatic elastase (PPE) causes emphysema and a decrease in lung elastin content, which returns to control level by Day 30. To explore the mechanism of alveolar wall remodeling after elastolytic injury, we examined the expression of elastin and alpha1(I) collagen mRNAs by in situ hybridization at 1, 2, 3, 5, 7, and 30 d after intratracheal PPE. The lungs of control animals displayed weak signals for elastin and alpha1(I) collagen mRNA in pleura, large arteries, veins, and airways. There was little or no signal in respiratory air space walls. Increased expression of elastin and alpha1(I) collagen mRNA began by Day 1 after PPE and reached an asymptote by Day 3 that was maintained by elastin until Day 7; expression of alpha1(I) collagen mRNA waned earlier. Elastin and, to a lesser extent, alpha1(I) collagen mRNA were heavily expressed in pleura, blood vessels, and airways. Analysis of serial sections showed elastin message was minimal in the walls of respiratory air spaces and when present, at 3, 5, and 7 d, was primarily found at the free margins of alveolar septa. Collagen message was very sparse in respiratory air space walls. By 30 d, elastin mRNA expression was reduced but still above control levels and emphysema was widespread and severe. Rank score of elastin mRNA expression in individual subpleural air spaces showed a positive correlation with air space size. In conclusion, most expression of elastin and alpha1(I) collagen mRNA occurs in the pleura, airway, and vascular walls. In respiratory air space walls, expression of elastin mRNAs occurs in damaged tissue at free septal margins.

Distribution of elastin in hamsters and the turnover rates of different elastin pools.

Desmosine (DES) and isodesmosine (IDES) concentration in the urine can be used as a noninvasive method of assessing degradation of mature elastin in normal and pathologic states. The present study was undertaken to determine the distribution of elastin among organs and tissues of normal hamsters, and to determine the turnover rates of two elastin-containing organs (lung, thoracic aorta) as a reflection of their contributions to DES and IDES excretion in the urine. Hamsters were metabolically labeled at 5 days of age with 14C-lysine and studied at 1.5, 4.5, 8, and 12 months of age. The aorta DES + IDES-associated radioactivity did not change significantly over the age span of 1.5-12 months. Lung DES + IDES-associated radioactivity decreased with a half-life of 420 days. Measurement of DES + IDES pools in other tissues, with relatively low concentrations of elastin, was carried out by the isotope dilution technique. At 12 months of age, the head and paws pool, skin, skeletal muscle, gastrointestinal tract, heart-liver-kidney-spleen pool, lungs, and thoracic aorta represented 37%, 28%, 13%, 11%, 6%, 4%, and 1%, respectively, of total body DES + IDES. The organs with the highest DES + IDES-specific radioactivity at 12 months were heart-liver-kidney-spleen, lung, and gastrointestinal tract, with 310, 217, and 217 dpm/nmol, respectively. Skin had the lowest specific radioactivity, with 90 dpm/nmol. The specific radioactivity of DES + IDES in urine was 62 dpm/nmol at 12 months, down from 251 dpm/nmol at 1.5 months. These data clearly indicate that non-lung tissues contain a high proportion of the total body DES + IDES and suggest that pathology in these other pools of DES + IDES could result in significant elevation of urinary DES + IDES. Nevertheless, the relatively high specific radioactivity of DES + IDES in lung elastin as compared with urine makes monitoring labeled urinary DES + IDES in this animal model a sensitive tool for assessing elastin degradation in experimental lung disease.

Tuberculosis then and now: a personal perspective on the last 50 years.

Rates of death from tuberculosis in the United States decreased from 194 per 100,000 persons in 1900 to 40 per 100,000 persons in 1945, in part because the epidemic of tuberculosis in the western world was running its course and in part because of public health initiatives and improved socioeconomic conditions. In 1945, 63,000 persons died of tuberculosis and 115,000 new cases of the disease emerged. Streptomycin and para-aminosalicylic acid had just been discovered; the discovery of isoniazid followed, in 1952. Sanitarium care, nonsurgical and surgical collapse therapy, and resectional surgery were in widespread use. By the middle of the 1950s, it was evident that bedrest did not add to the benefit produced by effective chemotherapy, and sanitariums began to close, a process that was completed by the 1970s. As mortality and morbidity due to tuberculosis rapidly decreased, the U.S. government decreased funding for tuberculosis and many states and cities downgraded their tuberculosis control programs. After 1984, the rate of new cases of tuberculosis, which had decreased to 9.4 per 100,000, began to increase and focal outbreaks of multidrug-resistant tuberculosis were reported. Noncompliance with drug therapy, homelessness, immigration to the United States from developing countries, and human immunodeficiency virus (HIV) infection were invoked as explanations. With the reinstitution of federal funding, improved case-finding and surveillance, and the practice of having patients receive therapy while under direct observation, the rate of new cases of tuberculosis decreased to 8.7 per 100,000 in 1995, the lowest rate since national surveillance was begun in 1953. However, at the end of the 20th century, the worldwide burden of tuberculosis, which is engrafted onto the pandemic of HIV infection, is enormous: an estimated 7.6 million new cases in developing countries and 400,000 new cases in industrial nations.

Urinary desmosine excretion in smokers with and without rapid decline of lung function: the Normative Aging Study.

It is hypothesized that smoking-related chronic obstructive pulmonary disease (COPD) results in part from excess lung elastin degradation. Taking advantage of spirometry performed over a 12-yr period at the Normative Aging Study, we conducted a nested case-control study of elastin and collagen degradation rates in current smokers with (n = 10) and without (n = 8) rapid decline of lung function, using a biochemical assay for urinary desmosine (DES), a specific marker for mature elastin degradation, and hydroxylysylpyridinoline (HP), a specific marker for mature fibrillar collagen degradation. Mean urinary excretion of DES in rapid decliners was 36% greater than in slow decliners (9.8 +/- 0.7 [mean +/- SE] versus 7.2 +/- 0.4 microg/g creatinine, p < 0.01); after adjustment for age and lean body mass (LBM), DES excretion in rapid decliners was 30% greater than in slow decliners (9.6 +/- 0.6 versus 7.4 +/- 0.7 microg/g creatinine, p = 0.06). Among rapid decliners, there was no difference in DES excretion between those with and those without computed tomogaphic evidence of emphysema. There was no significant difference between rapid and slow decliners in mean urinary excretion of HP (24.7 +/- 1.4 versus 21.6 +/- 1.8 nmol/mmol creatinine, p = 0.18). Among all subjects, rate of decline of FEV1 was significantly correlated with DES excretion (r = 0.61, p < 0.01). In a linear regression model adjusting for age and LBM, an increase in DES excretion of 1 microg/g creatinine was associated with an excess decline of FEV1 of 10.6 ml/yr (p = 0.04). This study provides further evidence in support of the elastase-antielastase hypothesis of the pathogenesis of COPD, and it suggests a role for elastin degradation in both emphysema and small airways disease. Moreover, it suggests that urinary DES excretion may be a useful biochemical marker for the study of interventions designed to prevent the development or progression of COPD.

Health-care technology assessment of surgical procedures: the case of reduction pneumoplasty for emphysema.

End-stage chronic obstructive pulmonary disease (COPD) is frequent in the practice of pulmonology. The recent report that reduction pneumoplasty results in lung function improvement in a high proportion of patients with emphysema has raised the question of how effectively the medical profession assesses the efficacy of new surgical procedures. Unlike drugs and devices, the introduction of new surgical procedures is not regulated. Technique changes rapidly for a period of time after new procedures are introduced. Peer review is done mainly by quality-improvement activities in the surgeon's hospital and by publication in peer-reviewed journals. Randomized clinical trials (RCT) are procedurally and ethically difficult to do and few have been done for new surgical procedures. Some trials have been problematic. For example, a controlled cooperative trial of radial keratotomy resulted in unsuccessful antitrust suits brought by physicians and patients alleging that third-party payers would not reimburse them for surgery. RCTs that have been done have tended to be reported long after the procedure has been incorporated into surgical practice. A RCT of reduction pneumoplasty would be impossible at this time because of rapid flux in surgical techniques. There might also be ethical problems because of the substantial improvement in lung function of many patients in the existing case series, a level of improvement seen with no other treatment than lung transplantation. It is proposed that a prospective, cooperative, consecutive-case, observational study (registry) of reduction pneumoplasty for emphysema could greatly speed the acquisition of information about the efficacy of this new procedure.

Reduction pneumoplasty for giant bullous emphysema. Implications for surgical treatment of nonbullous emphysema.

A review of the literature on reduction pneumoplasty for giant bullous emphysema was undertaken to identify current criteria for this surgical treatment and in the hope of obtaining insights into evaluating reduction pneumoplasty for nonbullous emphysema. Twenty-two retrospective case series, published since 1950, were retrieved by a computer search of the literature and a search of the Index Medicus prior to 1966. Reduction pneumoplasty is most effective when bullae are larger than one third of a hemithorax with evidence of compression of adjacent lung tissue and an FEV1 of less than 50% predicted; the presence of emphysema in nonbullous lung and the amount of compression are best judged by CT. The rationale for reduction pneumoplasty for nonbullous emphysema is supported by the similar early functional changes after reduction pneumoplasty for bullous and nonbullous-improvement of blood gas values and lung mechanics. A single study showing that decline of lung function after surgery for bullous emphysema was less in those who stopped smoking than in those who continued to smoke supports the need for preoperative and maintained smoking cessation in patients receiving reduction pneumoplasty. After 4 decades, the duration of improvement in lung function, whether worsening of emphysema occurs in remaining lung, and late morbidity and mortality after reduction pneumoplasty for bullous emphysema are not well defined. A registry with an unoperated-on comparison group could more rapidly accumulate such data after reduction pneumoplasty for nonbullous emphysema.