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Biomedical subjects

R A Stockley

Publications and source records attributed to R A Stockley.

At least 55 records · Page 3Linked to original sources
PubMed2000

Validation of assays for inflammatory mediators in sputum.

Commercially available immune assays are being used with increasing frequency in the study of lung inflammation. However, their performance in complex biological fluids is rarely assessed. The authors wished to assess their reliability to determine whether the results obtained in sputum samples can be easily interpreted. The reproducibility of several such assays was therefore determined together with their ability to recover known amounts of pure reagent. Sputum sol phase was obtained from several patients with chronic lung disease and used together with the reagents in a series of "spiking" and dilutional experiments. Results confirmed that the enzyme assay for myeloperoxidase and the immune assays for interleukin-8, leukotriene B4 and secretory leukoproteinase inhibitor were all reproducible (intra-assay coefficient of variation 3.8-7.7%). Furthermore, each of these assays gave >85% recovery of a "spike" with pure reagent. However, the immune assay for myeloperoxidase (although reproducible) gave poor recovery and was dependent on the degree of sample dilution and elastase content. These studies confirm that the reliabilities of fluid phase measurements should be assessed before being widely applied to complex biological samples.

Bronchiectasis↗
PubMed2000

Airways inflammation in chronic bronchitis: the effects of smoking and alpha1-antitrypsin deficiency.

Airways inflammation in chronic bronchitis is thought predominantly to be a direct consequence of neutrophil recruitment and release of elastase in response to factors such as cigarette smoke. The aims of this study were to assess the role of smoking and determine whether the serum elastase inhibitor alpha1-antitrypsin (alpha1AT) influenced the process. Airways inflammation was compared between patients with chronic obstructive bronchitis with (n=39) and without (n=42) severe alpha1AT deficiency. The authors assessed the sputum concentration of the neutrophil chemoattractants interleukin-8 (IL-8) and leukotriene (LT)B4, myeloperoxidase (MPO) as a marker of neutrophil influx, neutrophil elastase activity and its natural inhibitors, alpha1AT and secretory leukoprotease inhibitor (SLPI). Finally serum alpha1AT was measured to determine the degree of protein leakage (sputum sol serum alpha1AT ratio). Compared to current smokers, the exsmokers had a lower concentration of the chemoattractant IL-8 (p<0.05) and a lower MPO concentration, although this failed to reach conventional statistical significance (p=0.06). Patients with alpha1AT deficiency had greater inflammation in the larger airways with increased LTB4 (p<0.005), MPO (p<0.001), neutrophil elastase activity (p<0.01), protein leak (p<0.001), and were found to have a lower anti-proteinase screen with both reduced sputum alpha1AT (p<0.001) and SLPI concentrations (p<0.05). The reduction in sputum interleukin-8 levels in exsmokers may decrease neutrophil influx and thus explain the slower rate of neutrophil mediated progression of lung disease compared to subjects who continue to smoke. Patients with alpha1-antitrypsin deficiency had greater inflammation suggesting that alpha1-antitrypsin plays an important role in protecting the larger airways from the inflammatory effects of elastase activity and may explain their more rapid progression of disease.

Adult↗
PubMed2000

Inflammation--role of the neutrophil and the eosinophil.

Neutrophils are regularly identified in the airway secretions of patients with smoking-related chronic bronchitis and in those with chronic obstructive pulmonary disease. The migration and activation of these cells plays a role that is central to the secondary bronchial defences against potential bacterial pathogens. Where these processes persist or are excessive, potent mediators derived from the neutrophil may cause a perpetuation of bronchial inflammation and result in bronchial epithelial damage and impairment of endobronchial defences. Recent evidence has suggested that the eosinophil may also be present in the airways of some patients with chronic bronchitis, although its role in bronchial inflammation is not yet clear. In this article we have reviewed the evidence relating to the roles of both the neutrophil and of the eosinophil in the airway inflammation of chronic bronchitis.

Bronchitis↗
PubMed2000

A case of Haemophilus parainfluenzae pneumonia.

A 41 year old woman presented with community acquired pneumonia (CAP) which failed to resolve following treatment with amoxycillin and cefaclor prior to referral. Quantitative culture of sputum revealed a pure growth of Haemophilus parainfluenzae and, following antibiotic susceptibility testing of the isolate, ciprofloxacin was prescribed resulting in resolution of the infection. Immunological investigations showed that the patient had a high titre of H parainfluenzae specific IgM. The combination of a pure growth of H parainfluenzae, a response to appropriate antimicrobial therapy, and the presence of a specific antibody response indicated that this organism had a pathogenic role in the patient's pneumonia and should be considered in the differential diagnosis of CAP.

Adult↗
PubMed2000

Physiological and radiological characterisation of patients diagnosed with chronic obstructive pulmonary disease in primary care.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is common although often poorly characterised, particularly in primary care. However, application of guidelines to the management of such patients needs a clear understanding of the phenotype. In particular, the British guidelines for the management of COPD recommend that the diagnosis is based on appropriate symptoms and evidence of airflow obstruction as determined by a forced expiratory volume in one second (FEV(1)) of <80% of the predicted value and an FEV(1)/VC ratio of <70%. METHODS: A study was undertaken of 110 patients aged 40-80 years who had presented to their general practitioner with an acute exacerbation of COPD. The episode was treated at home and, when patients had recovered to the stable state (two months later), they were characterised by full lung function tests and a high resolution computed tomographic (HRCT) scan of the chest. RESULTS: There was a wide range of impairment of FEV(1) which was in the normal range (>/=80%) in 30%, mildly impaired (60-79%) in 18%, moderately impaired (40-59%) in 33%, and severely impaired (<40%) in 19% of patients. A reduced FEV(1)/VC ratio was present in all patients with an FEV(1) of <80% predicted but also in 41% of those with an FEV(1) of >/=80% predicted. Only 5% of patients had a substantial bronchodilator response suggesting a diagnosis of asthma. Emphysema was present in 51% of patients and confined to the upper lobes in most (73% of these patients). HRCT evidence of bronchiectasis was noted in 29% of patients and was predominantly tubular; most (81%) were current or ex-smokers. A solitary pulmonary nodule was seen on 9% of scans and unsuspected lung malignancy was diagnosed in two patients. CONCLUSIONS: This study confirms that COPD in primary care is a heterogeneous condition. Some patients do not fulfil the proposed diagnostic criteria with FEV(1) of >/=80% predicted but they may nevertheless have airflow obstruction. Bronchiectasis is common in this group of patients, as is unsuspected malignancy. These findings should be considered when developing recommendations for the investigation and management of COPD in the community.

Adult↗
PubMed2000

New approaches to the management of COPD.

Airflow limitation in COPD is a result partially of bronchospasm, but it is also caused by a reduction in airway caliber, the number of small airways, airway collapse because of loss of connective tissue support, excess mucus in the airways, and edema of the airway wall. Structural changes also occur because of long-term destruction of interstitial connective tissue, including elastin. Therefore, in addition to the traditional aim of reversing bronchospasm with bronchodilators, disease-modifying approaches are being investigated. The enzyme neutrophil elastase is implicated in the induction of bronchial disease causing structural changes in lungs, impairment of mucociliary clearance, and impairment of host defenses. The precise mechanism pathway of neutrophil elastase is uncertain, but the effects of influencing the pathway in order to slow disease progression are being investigated. Oxidants may also have a role in the development of COPD, with increased levels activating airway cells and cytokine production.

Animals↗
PubMed2000

Bronchial inflammation: its relationship to colonizing microbial load and alpha(1)-antitrypsin deficiency.

Neutrophil elastase is capable of generating many of the features of chronic bronchial disease. In patients with COPD, airways inflammation with neutrophil recruitment and elastase release is positively correlated with colonizing bacterial load in the stable clinical state (p < 0.0005). In addition, alpha(1)-antitrypsin deficiency is associated with a greater neutrophil load, higher elastase activity, leukotriene-B(4) concentration, and serum protein leak than matched patients without deficiency (p < 0.005). These data confirm an effect of bronchial colonization on airways inflammation in COPD and indicate the role of alpha(1)-antitrypsin in its modulation.

Bacteria↗
PubMed2000

Relationship of sputum color to nature and outpatient management of acute exacerbations of COPD.

STUDY OBJECTIVES: To stratify COPD patients presenting with an acute exacerbation on the basis of sputum color and to relate this to the isolation and viable numbers of bacteria recovered on culture. DESIGN: Open, longitudinal study of sputum characteristics and acute-phase proteins. SETTING: Patients presenting to primary-care physicians in the United Kingdom. Patients were followed up as outpatients in specialist clinic. PATIENTS: One hundred twenty-one patients with acute exacerbations of COPD were assessed together with a single sputum sample on the day of presentation (89 of whom produced a satisfactory sputum sample for analysis). One hundred nine patients were assessed 2 months later when they had returned to their stable clinical state. INTERVENTIONS: The expectoration of green, purulent sputum was taken as the primary indication for antibiotic therapy, whereas white or clear sputum was not considered representative of a bacterial episode and the need for antibiotic therapy. RESULTS: A positive bacterial culture was obtained from 84% of patients sputum if it was purulent on presentation compared with only 38% if it was mucoid (p < 0.0001). When restudied in the stable clinical state, the incidence of a positive bacterial culture was similar for both groups (38% and 41%, respectively). C-reactive protein concentrations were significantly raised (p < 0.0001) if the sputum was purulent (median, 4.5 mg/L; interquartile range [IQR], 6. 2 to 35.8). In the stable clinical state, sputum color improved significantly in the group who presented with purulent sputum from a median color number of 4.0 (IQR, 4.0 to 5.0) to 3.0 (IQR, 2.0 to 4. 0; p < 0.0001), and this was associated with a fall in median C-reactive protein level to 2.7 mg/L (IQR, 1.0 to 6.6; p < 0.0001). CONCLUSIONS: The presence of green (purulent) sputum was 94.4% sensitive and 77.0% specific for the yield of a high bacterial load and indicates a clear subset of patient episodes identified at presentation that is likely to benefit most from antibiotic therapy. All patients who produced white (mucoid) sputum during the acute exacerbation improved without antibiotic therapy, and sputum characteristics remained the same even when the patients had returned to their stable clinical state.

Acute Disease↗
PubMed1999

Interaction between leukocyte elastase and elastin: quantitative and catalytic analyses.

Solubilization of elastin by human leukocyte elastase (HLE) cannot be analyzed by conventional kinetic methods because the biologically relevant substrate is insoluble and the concentration of enzyme-substrate complex has no physical meaning. We now report quantitative measurements of the binding and catalytic interaction between HLE and elastin permitted by analogy to receptor-ligand systems. Our results indicated that a limited and relatively constant number of enzyme binding sites were available on elastin, and that new sites became accessible as catalysis proceeded. The activation energies and solvent deuterium isotope effects were similar for catalysis of elastin and a soluble peptide substrate by HLE, yet the turnover number for HLE digestion of elastin was 200-2000-fold lower than that of HLE acting on soluble peptide substrates. Analysis of the binding of HLE to elastin at 0 degrees C, in the absence of significant catalytic activity, demonstrated two classes of binding sites (Kd=9.3x10(-9) M and 2.5x10(-7) M). The higher affinity sites accounted for only 6% of the total HLE binding capacity, but essentially all of the catalytic activity, and dissociation of HLE from these sites was minimal. Our studies suggest that interaction of HLE with elastin in vivo may be very persistent and permit progressive solubilization of this structurally important extracellular matrix component.

Binding Sites↗
PubMed1999

Chronic obstructive pulmonary disease, with and without alpha-1-antitrypsin deficiency: management practices in the U.K.

Alpha-1-antitrypsin deficiency is a common genetic defect associated with the development of severe and rapidly progressive lung disease. This study was undertaken to determine whether respiratory physicians manage patients with alpha-1-antitrypsin (AAT) deficiency differently from patients with chronic obstructive pulmonary disease (COPD) without alpha-1-antitrypsin deficiency. In addition we obtained physicians' views on who should be tested for AAT deficiency. A questionnaire was administered to 88 respiratory physicians based throughout the U.K. (44 in teaching hospitals). The main outcome measures were pulmonary function tests, radiological assessment, frequency of repeat testing, follow-up and screening protocol for alpha-1-antitrypsin deficiency. Subjects with homozygous (PiZ) AAT deficiency were more likely to: 1. have baseline and full pulmonary function testing including dynamic flow rates, static lung volumes, and gas transfer; 2. have more comprehensive assessment with high resolution computed tomography (HRCT) thorax and repeated radiological assessment (with annual chest radiography); 3. be followed-up routinely; and 4. have family members tested for alpha-1-antitrypsin deficiency. Testing remains limited for AAT deficiency and is mainly restricted to young patients with COPD. COPD assessment and management is influenced by the presence of AAT deficiency, which may reflect the poorer prognosis of such patients due to more rapid decline. Assessment and monitoring could be simplified to forced expired manoeuvres, although limited HRCT thorax and tests of gas transfer may prove more sensitive to progression of emphysema. Testing for AAT deficiency in the U.K. remains restricted, which will influence the detection rate for AAT deficiency. A wider policy of testing was advocated by the WHO will detect more patients and also influence our understanding of the natural history of the condition.

Adult↗
PubMed1999

Quality of life in elderly subjects with a diagnostic label of asthma from general practice registers.

The aim of this study was to assess health-related quality of life (QoL) in elderly subjects with a diagnostic label of asthma from a general practice population, and to determine the main contributory factors. Sixty people aged > or =70 yrs with a primary care diagnostic label of asthma, and 43 control subjects were recruited. Assessment of bronchodilator response, and oral steroid trials were conducted where possible. The main outcome measures were QoL scores for the Short Form (SF)-36 and the St George's Respiratory Questionnaire (SGRQ). In the asthma group, 29 subjects demonstrated a significant airway response to bronchodilators or steroids. Mean SF-36 scores were significantly worse in the total asthma group for components of physical function, physical role limitation, and general health, although psychological scores were similar. QoL remained worse than controls in those subjects with a significant bronchodilator response. Dyspnoea and depression accounted for 61% of the variance in the SGRQ, but forced expiratory volume in one second was not an independent variable. Quality of life is impaired in elderly people with a diagnosis of asthma, including those with demonstrable airway variability. Many older subjects with asthma note a variety of symptoms, highlighting the need for further research into the adequacy and efficacy of their treatment.

Aged↗
PubMed1999

The interrelationship of sputum inflammatory markers in patients with chronic bronchitis.

Many of the features of bronchial disease are believed to be caused by damage to the airways by elastase released by recruited neutrophils. There have been few studies of the mechanisms involved and the interrelationships between components of the inflammatory process. We studied secretions from patients with chronic bronchitis in the stable state. We assessed the presence of neutrophils by measuring myeloperoxidase (MPO) activity and active neutrophil elastase (NE). These results were compared with the chemoattractants interleukin-8 (IL-8) and leukotriene B(4) (LTB(4)), the bronchial inhibitor secretory leukoprotease inhibitor (SLPI), and protein leak (sputum/serum albumin ratio). MPO correlated with NE activity (r = 0.68, p < 0.001) and both IL-8 (r = 0.52, p < 0.001) and LTB(4) (r = 0.41, p < 0.001) indicating an association with the chemoattractants. Elastase activity correlated with IL-8 (r = 0.55, p < 0.001) and LTB(4) (r = 0.41, p < 0.001) but negatively with SLPI (r = -0.49, p < 0.001). NE also correlated positively with protein leak (r = 0.36, p < 0.001), suggesting a cause and effect. MPO and protein leak correlated negatively with FEV(1) (percentage of predicted) only in patients with chronic obstructive pulmonary disease (COPD) without alpha(1)-antitrypsin deficiency (r = -0.37, p < 0.001; r = -0.42, p < 0.01, respectively). These complex interactions provide a template for future studies with specific inhibitors or agonists which will clarify the role of individual factors.

Adult↗
PubMed1999

Evidence for excessive bronchial inflammation during an acute exacerbation of chronic obstructive pulmonary disease in patients with alpha(1)-antitrypsin deficiency (PiZ).

Patients with homozygous (PiZ) alpha(1)-antitrypsin (AAT) deficiency have not only low baseline serum AAT levels (approximately 10 to 15% normal) but also an attenuated acute phase response. They are susceptible to the development of premature emphysema but may also be particularly susceptible to lung damage during bacterial exacerbations when there will be a significant neutrophil influx. The purposes of the present study were to assess the inflammatory nature of acute bacterial exacerbations of chronic obstructive pulmonary disease (COPD) in subjects with AAT deficiency, to compare this with COPD patients without deficiency, and to monitor the inflammatory process and its resolution following appropriate antibacterial therapy. At the start of the exacerbation, patients with AAT deficiency had lower sputum AAT (p < 0.001) and secretory leukoprotease inhibitor (SLPI; p = 0.02) with higher elastase activity (p = 0.02) compared with COPD patients without deficiency. Both groups had a comparable acute phase response as assessed by C-reactive protein (CRP) but the AAT-deficient patients had a minimal rise in serum AAT (to < 6 microM). After treatment with antibiotics, in patients with AAT deficiency, there were significant changes in many sputum proteins including a rise in SLPI levels, and a reduction in myeloperoxidase (MPO) and elastase activity (p < 0. 005 for all measures); the sputum chemoattractants interleukin-8 (IL-8) and leukotriene B(4) (LTB(4)) fell (p < 0.01), and protein leak (sputum/serum albumin ratio) became lower (p < 0.01). The changes were rapid and within 3 d of the commencement of antibiotic therapy the biochemical markers had decreased significantly, but took a variable time thereafter to return to baseline values. In conclusion, patients with AAT deficiency had evidence of increased elastase activity at the start of the exacerbation when compared with nondeficient COPD patients which probably reflects a deficient antiproteinase screen (lower sputum AAT and SLPI). The increased bronchial inflammation at presentation resolved rapidly with 14 d of antibiotic therapy.

Acute Disease↗
PubMed1999

Neutrophils and protease/antiprotease imbalance.

An imbalance between neutrophil proteases and the surrounding antiproteases is critical in the normal functioning of the neutrophil. Enzyme activity is of importance in cell migration and may play a role in some beneficial aspects of host defense. However, when persistent or excessive this imbalance can be detrimental and (even in the absence of antiprotease deficiency) central to most of the pathogenic processes in COPD. Understanding of these complex relationships that alter a beneficial host defense response to a destructive one will be critical in the development of long-term therapeutic strategies. Stockley RA. Neutrophils and protease/antiprotease imbalance.

Humans↗
PubMed1998

The effect of interleukin-8 and granulocyte macrophage colony stimulating factor on the response of neutrophils to formyl methionyl leucyl phenylalanine.

Neutrophils isolated from patients with chronic bronchitis and emphysema have been shown to have enhanced responses to formyl peptides when assessed in vitro compared to age, sex matched controls. It is currently unclear whether the observed differences are due to a 'priming' effect by a second agent in vivo, or whether this is a primary difference in the neutrophils. We have studied the effects of interleukin-8, which is thought to be one of the major pro-inflammatory cytokines in chronic lung disease and granulocyte macrophage colony stimulating factor (GMCSF), in order to assess their effects on neutrophil chemotaxis and connective tissue degradation. In addition, we have assessed the effect of preincubation of these agents with neutrophils for 30 min followed by stimulation with F-Met-Leu-Phe (FMLP) to investigate any possible 'priming' effect that may be relevant to our clinical data. We report suppression of neutrophil chemotaxis to FMLP following incubation of the neutrophils with both IL-8 and GMCSF. However, we have observed an additive effect of IL-8 and FMLP for neutrophil degranulation leading to fibronectin degradation. The results suggest that IL-8 does not 'prime' neutrophils for subsequent FMLP stimulation as observed in vivo. Although the results for GMCSF were similar for the chemotactic response, the agent also had a synergistic effect on connective tissue degradation. However, it is concluded that neither agent could explain the enhanced neutrophil responses seen in our patients.

Chemotaxis↗
PubMed1998

Leukotriene B4.

Leukotriene B4 is a pro-inflammatory mediator synthesised in myeloid cells from arachidonic acid. Synthesis is catalysed by 5-lipoxygenase and leukotriene A4 hydrolase and is increased by inflammatory mediators including endotoxin, complement fragments, tumor necrosis factor and interleukins. A nuclear membrane protein, 5-lipoxygenase activating protein, is an essential co-factor for 5-lipoxygenase. Leukotriene B4 induces recruitment and activation of neutrophils, monocytes and eosinophils. It also stimulates the production of a number of proinflammatory cytokines and mediators indicating an ability to augment and prolong tissue inflammation. Elevated levels of leukotriene B4 have been found in a number of inflammatory diseases and levels are related to disease activity in some of these. Initial data from pharmacological inhibition studies support a role for leukotriene B4 in the pathogenesis of neutrophil mediated tissue damage, and treatments which reduce its production or block its effects may prove beneficial in neutrophil mediated inflammatory diseases.

Arachidonate 5-Lipoxygenase↗