Medical educators' views on medical education reform

To determine whether medical educators perceive a need for change in medical student education, we analyzed data from a 1989 survey of 1369 respondents from all US schools of allopathic medicine. Except for basic sciences faculty, a majority of educators stated that "fundamental changes" are needed in medical student education in the United States. Nearly three fourths of deans and associated deans reported the need for "fundamental changes" or "thorough reform." At least 79% of educators voiced support for six specific reforms, such as rewarding teaching excellence and increasing clinical education in ambulatory and community settings. While slight majorities supported reducing class size and centralizing governance, substantial proportions stated that they would "work against" such reforms. Most educators reported that a broad base of support within the school would be essential for change. The survey suggests a restlessness among the leaders of medical education.

Use of antibodies in the study of protein structure and function in lung diseases

Proteins normally fold in a variety of three-dimensional structures. This variety of forms accounts for a multiplicity of functions. One of the major undertakings of modern biochemistry is to determine the structure of a given protein and in doing so learn about its function. Much of the effort in the field of protein chemistry is currently focused on defining areas or domains within the molecule that are responsible for its function. Antibodies specific for functional domains on a protein have been powerful tools in these studies and have provided a great deal of the current knowledge related to the location and function of well-defined structural areas within the protein molecules. The use of antibodies in the study of proteins has considerably advanced our knowledge of both the structure of proteins and their interaction with other molecules. In reviewing the use of antibodies for structure and/or function analysis, we have tried not only to review the techniques and applications involving antibodies but also to show how useful antibody reagents may be designed and prepared. In this review, some of the newer uses of antibodies in modern biology will be described, and a few illustrations of each will be provided.

Synthesis and secretion of high- and low-molecular-weight forms of the enzyme-releasing peptide (ERP) from the macrophage-like cell line THP-1

Neutrophil enzymes have been implicated as a source of lung injury in patients with the adult respiratory distress syndrome (ARDS) and with emphysema. We studied a human alveolar macrophage-derived peptide messenger, the enzyme-releasing peptide (ERP), which causes neutrophils to secrete their enzymes. The secretion and synthesis of ERP was studied in human alveolar macrophages and in the macrophage-like cell lines THP-1, HL-60, and U937. All four cell types secrete an ERP-like peptide. THP-1 cells secrete a higher concentration of the peptide than do macrophages. The secretion of ERP by THP-1 is suppressed by the protein synthesis inhibitors actinomycin D and cycloheximide. While the macrophages secrete ERP, they do not synthesize it. These studies suggest that ERP is synthesized by an alveolar macrophage precursor and stored in the mature macrophage for later release. 12-O-tetradecanoylphorbol-13-acetate (TPA) suppresses ERP secretion by THP-1 cells, but it does not modify secretion in macrophages. Escherichia coli-derived lipopolysaccharide and dimethyl sulfoxide do not modify secretion in either cell type. The THP-1 cells secrete a high- and low-mass-ratio (Mr) form of ERP-like proteins. The low Mr but not the high Mr form stimulates neutrophils to secrete their granule enzymes. We conclude that human alveolar macrophages secrete ERP but do not synthesize it. It is likely that ERP is made by an alveolar macrophage precursor in a high Mr form that is cleaved prior to secretion by the macrophages.

A controlled trial of colchicine to reduce the elastase load in the lungs of cigarette smokers with chronic obstructive pulmonary disease

Current data suggest that emphysema in smokers is caused at least in part by the unrestrained action of neutrophil elastase on pulmonary tissues. Since colchicine reduces the secretion of enzymes from stimulated neutrophils, we designed a clinical trial to determine if colchicine could reduce the elastase load in the lungs or several putative indicators of elastin destruction. We carried out a prospective, double-blind, randomized, and placebo-controlled clinical trial. Outpatients seeking treatment for chronic obstructive pulmonary disease at the University of Texas Health Center at Tyler who met specific criteria were recruited into the study. A group of 46 cigarette smokers between 45 and 75 yr of age with chronic obstructive pulmonary disease (COPD) were studied. Colchicine or placebo was given orally in disguised capsules, 0.6 mg three times per day. Volunteers were placed on a baseline bronchodilator regimen of Theodur orally and albuterol by inhalation. Blood, urine, and bronchoalveolar lavage fluids were obtained after 1 wk of stabilization. The patients were then randomized and treated for 14 days with colchicine, and the measurements were repeated. Modifications in plasma elastin peptides and neutrophil elastase-generated fibrinopeptide A, urinary desmosines, and bronchoalveolar lavage fluid neutrophils or neutrophil elastase were the indicators of success or failure of the treatment. Pre- and posttreatment measurements in each patient and the difference between colchicine-treated and placebo-treated groups were compared. There were no statistically significant differences in either of the two types of analyses in any of the variables. We conclude that variables related to elastase load in the lungs were not modified by colchicine treatment. If a drug can be identified that is successful in modifying one of these variables, it would then have to be tested in a large-scale clinical trial in which the rate of decline in the FEV1.0 or mortality would be measured. The data presented here may provide useful information about the variability of key measurements of elastase load in the lungs and the breakdown of elastin and may aid investigators in designing similar trials in the future.

Liberation of a neutrophil enzyme-releasing peptide from the surface of human alveolar macrophages

The human alveolar macrophage product, enzyme-releasing peptide (ERP), has a molecular mass of 8,000 Da, and releases azurophilic and specific granule constituents from neutrophils. A murine monoclonal anti-ERP antibody (12E10H), previously used to show a lack of antigenic identity between ERP and C5a, interleukin 1, tumor necrosis factor, and gamma-interferon, showed no cross-reactivity with interleukin 8. 12E10H and a fluorescein-labeled second antibody were used to visualize ERP on the macrophage surface. ERP was removed from alveolar macrophages by a 3-min incubation with 5 X 10(-7) M bovine pancreatic trypsin at 37 degrees C. The washed trypsinized cells could readhere to plastic and exclude trypan blue. Dilution of the trypsin-derived ERP released myeloperoxidase from cytochalasin-B-treated neutrophils dose dependently. The enzyme-releasing ability of the trypsin-derived material was removed by immunoprecipitation using antibody 12E10H bound to Staphylococcal protein A Sepharose 4B. The estimated molecular mass of the trypsin-derived ERP (by molecular sieve chromatography on HPLC) was approximately 8,500 Da. Other proteases (plasmin, thrombin, and cathepsin G) also released ERP from the cell surface, but the ERP was not an active secretagogue for neutrophils. However, macrophages cultured with protease inhibitors did not show decreased ERP accumulation in the medium. Our data indicate that ERP exists on the surface of human alveolar macrophages and can be released by proteases found within the lung environment in some disease states.

A modified bronchoalveolar lavage procedure that allows measurement of lung epithelial lining fluid volume

We replaced the standard serial bronchoalveolar lavage technique with a new "rewash" lavage procedure to allow estimation of the volume and protein concentration of the epithelial lining fluid (ELF) in anesthetized sheep. A bronchoscope 6.0 mm in diameter wedged in an airway was used to lavage a segment of lung with four cycles of instillation and aspiration of the lavage solution containing a radioactive tracer (technetium pertechnetate, 99mTcO4-). Errors caused by the fall in concentration of the tracer during the lavage were minimized by extrapolating the tracer concentration back to time zero when the lavage solution had mixed with the ELF, but had not had time to be affected by loss of the tracer or influx of fluid from the interstitium. In control sheep, the ELF of these lavaged segments had a mean volume of 1.6 +/- 1.0 ml and a mean protein concentration that was 26 +/- 19% of the protein concentration measured in the plasma. Increasing the left atrial pressure 19 +/- 5 cm H2O to cause "cardiac lung edema" had no significant effect on the ELF volume, but it increased the mean protein concentration to 57 +/- 30% of the plasma value (p less than 0.01). Lung injury caused by intravenous oleic acid caused lung edema, increased the mean ELF volume to 6.8 +/- 2.2 ml, and increased the mean ELF protein concentration to 86 +/- 26% of the plasma value (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Search for drugs that may reduce the load of neutrophil azurophilic granule enzymes in the lungs of patients with emphysema

Neutrophil elastase and myeloperoxidase probably play an important role in the development of pulmonary emphysema. We have analyzed drugs from the major classes of agents that alter neutrophil function to determine if there are drugs in use today that can reduce the load of neutrophil elastase or myeloperoxidase in the lungs of smokers. Eleven representative drugs were tested for their ability to inhibit chemotaxis and degranulation. None of the drugs inhibited chemotaxis in a dose-response fashion at concentrations achievable in human plasma. Sulfinpyrazone, phenylbutazone, and auranofin completely inhibited the release of azurophilic granules (myeloperoxidase) and tertiary granules (beta-D-glucuronidase) when formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) was used as the stimulant, and inhibited azurophilic granule release by 69%, 19%, and 64% respectively, but not tertiary granule release when macrophage-conditioned media was used as the stimulus. In conclusion, none of the drugs tested are inhibitors of chemotaxis; however, three are excellent inhibitors of azurophilic granule enzyme release. Of these three, sulfinpyrazone, a drug that is not currently used clinically for its antiinflammatory effects, is the least toxic and should be considered as a potential drug to reduce the elastase and myeloperoxidase load in the lungs of smokers who are developing emphysema.

Alveolar macrophages from patients with asbestos exposure release increased levels of leukotriene B4

The alveolar influx and subsequent activation of inflammatory cells such as neutrophils and eosinophils are believed to be important in the pathogenesis of many interstitial lung disorders, including asbestosis. Indices of lower respiratory tract abnormalities detected by bronchoalveolar lavage (BAL) were investigated in 93 asbestos-exposed workers as well as in smoking (n = 12) and nonsmoking (n = 10) control subjects. Patients with clinical asbestosis (n = 12) exhibited increases in both BAL neutrophils and BAL eosinophils, expressed as both percentage of total cells and total numbers, when compared to asbestos-exposed workers without asbestosis (n = 81) and control subjects. Significantly greater numbers of BAL neutrophils were also found in asbestos-exposed workers without asbestosis than in either smoking or nonsmoking control subjects. These abnormalities correlated significantly with in vitro BAL alveolar macrophage production of the potent leukocyte chemotaxin, leukotriene B4 (LTB4). For example, basal, unstimulated LTB4 production was 3.1 +/- 0.8 ng/10(6) alveolar macrophages for patients with asbestosis, 1.05 +/- 0.2 ng/10(6) cells in asbestos workers without asbestosis, 0.9 +/- 0.2 ng/10(6) cells in control nonsmokers, and 0.2 +/- 0.05 ng/10(6) cells in control smokers. Stimulated LTB4 release from BAL alveolar macrophages (A23187 or arachidonate) was even more pronounced in asbestos workers with or without asbestosis, suggesting an in vivo priming effect on alveolar macrophage synthesis of LTB4. Cell-free BAL supernatants from asbestos-exposed patients with or without asbestosis also contained significantly greater amounts of LTB4 than did those from control subjects, indicating enhanced in vivo production of this inflammatory mediator.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular genetics in pulmonary emphysema

A vast array of new methods in molecular genetics are providing insights into problems at the cell and molecular level. Their applications in lung disease is unbounded. However, they are only methods. They are the right methods for certain kinds of questions and the wrong methods for other kinds of questions.

A peptide from alveolar macrophages that releases neutrophil enzymes into the lungs in patients with the adult respiratory distress syndrome

A monoclonal antibody has been made to a peptide that is released by human alveolar macrophages. This enzyme-releasing peptide (ERP) causes neutrophils to secrete azurophilic granule enzymes. Normal subjects, patients with pulmonary fibrosis, and patients with sarcoidosis had similar concentrations of this peptide in their bronchoalveolar lavage fluids. However, patients with the adult respiratory distress syndrome (ARDS) had about 2.7 times higher concentrations in their lavage fluids. The enzyme-releasing activity in the lavage fluids was significantly correlated with 2 indices of the severity of the clinical illness in patients with ARDS, the APACHE score, and the chest radiograph score. The correlation was diminished or ablated by removing the peptide with the monoclonal antibody bound to staphylococcal Sepharose 4B. This peptide accounted for 62.08% (SD = 15.88%) of the enzyme-releasing activity in fluids from lungs of patients with ARDS and 86.39% (SD = 24.46%) of the activity in fluids from lungs of normal control subjects. Therefore, ERP is the major neutrophil enzyme-releasing agent in the bronchoalveolar lavage fluid from patients with ARDS and from normal persons. There was a significant correlation between the neutrophil enzyme-releasing activity and the ERP concentrations in BAL of patients with ARDS. These observations suggest that modulation of neutrophil function by ERP significantly controls the protease and peroxidase loads in the lungs of patients with ARDS.

A peptide secreted by human alveolar macrophages releases neutrophil granule contents

A monoclonal antibody was developed against an 8,000-kDa enzyme-releasing peptide (ERP) released from human alveolar macrophages. ERP was isolated on an immunoaffinity column containing the antibody bound to staphylococcal protein A-Sepharose. Release of ERP from the macrophages is not changed by plastic adherence, phagocytosis, calcium ionophore, or phorbol esters. The peptide was not antigenically similar to interferon-gamma, tumor necrosis factor, or interleukin 1 alpha or 1 beta. The release of constituents from azurophilic and specific granules was the main identified biologic function of ERP. ERP was a more effective secretagogue in the untreated neutrophils and f-met-leu-phe was more effective in the cytochalasin B-treated neutrophils. Absorption of ERP from macrophage-conditioned medium removed a small amount of the chemotactic activity; however, the immunopurified peptide was not chemotactic or chemokinetic for neutrophils, and at high concentrations, it suppressed base line chemokinesis. Treatment of washed macrophages with trypsin released active ERP of approximately the same m.w. of spontaneously secreted ERP. These studies showed that human alveolar macrophages release a peptide which is a secretagogue for human neutrophils under conditions which may be encountered in the lungs during certain disease states. Proteolytic enzymes which are free in the lungs may release the peptide and lead to the secretion of neutrophil enzymes.

A peptide secreted by human alveolar macrophages releases neutrophil granule contents

A monoclonal antibody was developed against an 8,000-kDa enzyme-releasing peptide (ERP) released from human alveolar macrophages. ERP was isolated on an immunoaffinity column containing the antibody bound to staphylococcal protein A-Sepharose. Release of ERP from the macrophages is not changed by plastic adherence, phagocytosis, calcium ionophore, or phorbol esters. The peptide was not antigenically similar to interferon-gamma, tumor necrosis factor, or interleukin 1 alpha or 1 beta. The release of constituents from azurophilic and specific granules was the main identified biologic function of ERP. ERP was a more effective secretagogue in the untreated neutrophils and f-met-leu-phe was more effective in the cytochalasin B-treated neutrophils. Absorption of ERP from macrophage-conditioned medium removed a small amount of the chemotactic activity; however, the immunopurified peptide was not chemotactic or chemokinetic for neutrophils, and at high concentrations, it suppressed base line chemokinesis. Treatment of washed macrophages with trypsin released active ERP of approximately the same m.w. of spontaneously secreted ERP. These studies showed that human alveolar macrophages release a peptide which is a secretagogue for human neutrophils under conditions which may be encountered in the lungs during certain disease states. Proteolytic enzymes which are free in the lungs may release the peptide and lead to the secretion of neutrophil enzymes.

Changing health policies and clinical laboratory services

Recent changes in Medicare financing policy and in state certificate of need (CON) policies have greatly altered the environment in which hospitals and physicians must operate. These policy changes likely will influence the development, adoption, and use of new technologies, including those employed in clinical laboratories. Some hospitals, particularly large academic health centers, are responding to the new incentives under Medicare prospective payment by (1) implementing integrated case mix and financial information systems, (2) monitoring and evaluating physician practice patterns, (3) improving the quality of analyses underlying their technology acquisition decisions, and (4) striving toward improved relations with medical staff. Clinical laboratories are also responding to these financial pressures through (1) more cautious adoption of new technologies, (2) selective automation of tests that reduce direct costs, (3) more prudent "make-or-buy" decisions regarding test performance sites, and (4) focused effort to improve turnaround times for inpatient testing and reporting.