Rapid whole cell imaging reveals a calcium-APPL1-dynein nexus that regulates cohort trafficking of stimulated EGF receptors

The endosomal system provides rich signal processing capabilities for responses elicited by growth factor receptors and their ligands. At the single cell level, endosomal trafficking becomes a critical component of signal processing, as exemplified by the epidermal growth factor (EGF) receptors. Activated EGFRs are trafficked to the phosphatase-enriched peri-nuclear region (PNR), where they are dephosphorylated and degraded. The details of the mechanisms that govern the movements of stimulated EGFRs towards the PNR, are not completely known. Here, exploiting the advantages of lattice light-sheet microscopy, we show that EGFR activation by EGF triggers a transient calcium increase causing a whole-cell level redistribution of Adaptor Protein, Phosphotyrosine Interacting with PH Domain And Leucine Zipper 1 (APPL1) from pre-existing endosomes within one minute, the rebinding of liberated APPL1 directly to EGFR, and the dynein-dependent translocation of APPL1-EGF-bearing endosomes to the PNR within ten minutes. The cell spanning, fast acting network that we reveal integrates a cascade of events dedicated to the cohort movement of activated EGF receptors. Our findings support the intriguing proposal that certain endosomal pathways have shed some of the stochastic strategies of traditional trafficking and have evolved processes that provide the temporal predictability that typify canonical signaling.

Patient deprivation and perceived scan burden negatively impact the quality of whole-body MRI

AIM

To evaluate the association between the image quality of cancer staging whole-body magnetic resonance imaging (WB-MRI) and patient demographics, distress, and perceived scan burden.

MATERIALS AND METHODS

A sample of patients recruited prospectively to multicentre trials comparing WB-MRI with standard scans for staging lung and colorectal cancer were invited to complete two questionnaires. The baseline questionnaire, administered at recruitment, collated data on demographics, distress and co-morbidity. The follow-up questionnaire, completed after staging investigations, measured perceived WB-MRI scan burden (scored 1 low to 7 high). WB-MRI anatomical coverage, and technical quality was graded by a radiographic technician and grading combined to categorise the scan as "optimal", "sub-optimal" or "degraded". A radiologist categorised 30 scans to test interobserver agreement. Data were analysed using the chi-square, Fisher's exact, t-tests, and multinomial regression.

RESULTS

One hundred and fourteen patients were included in the study (53 lung, 61 colorectal; average age 65.3 years, SD=11.8; 66 men [57.9%]). Overall, 45.6% (n=52), scans were classified as "optimal" quality, 39.5% (n=45) "sub-optimal", and 14.9% (n=17) as "degraded". In adjusted analyses, greater deprivation level and higher patient-reported scan burden were both associated with a higher likelihood of having a sub-optimal versus an optimal scan (odds ratio [OR]: 4.465, 95% confidence interval [CI]: 1.454 to 13.709, p=0.009; OR: 1.987, CI: 1.153 to 3.425, p=0.013, respectively). None of the variables predicted the likelihood of having a degraded scan.

CONCLUSIONS

Deprivation and patients' perceived experience of the WB-MRI are related to image quality. Tailored protocols and individualised patient management before and during WB-MRI may improve image quality.

Factors responsible for delayed enrollment for anti-retroviral treatment

BACKGROUND

Late presentation followed by delayed diagnosis and further delayed initiation of anti-retroviral therapy (ART) increases the risk of opportunistic infections and neoplasms among the HIV infected patients. Furthermore, this leads to not only poor response to therapy but also early death among them.

METHODS

An institution based cross-sectional study was undertaken to identify the factor(s) responsible for delayed registration for initiation of therapy among the HIV infected patients with absolute CD4 count <250 cells/μL based on self reports. ART naïve adult HIV patients (age ≥18 years) with baseline CD4 count of <250 cells/μL were included in this study.

RESULTS

Most patients 95 (95%) were unaware of the available 'Integrated Counseling and Testing Centres'. Although 13 (13%) respondents had multiple reasons for delayed enrollment, majority 47 (47%) of the delays were due to the physician's failure to suspect and refer them for HIV testing at the earliest opportunity. Other causes include health seeking behavior 13 (13%), fear of stigma 5 (5%), depression 3 (3%), and lack of family support 6 (6%).

CONCLUSIONS

Even though delays in pre-ART enrollment have been realized since long, prevention efforts are poor, mostly due to the lack of understanding of the nature of the problem in its social context. Lack of clinical suspicion for HIV infection at the primary and secondary levels of health care still remains the most important reason for the delay. In order to prevent these delays in enrollments, intervention efforts need to be focused on not only the people infected with HIV but the primary health care providers as well, especially the practicing physicians.

Granulomatous mediastinal adenopathy: can endoscopic ultrasound-guided fine-needle aspiration differentiate between tuberculosis and sarcoidosis?

BACKGROUND AND STUDY AIMS

Mediastinal lymphadenopathy may indicate diseases such as tuberculosis or sarcoidosis, and it is often difficult to establish a diagnosis when standard medical work-up is inconclusive. In this study we investigated the diagnostic yield of endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) in the differentiation between tuberculosis and sarcoidosis.

PATIENTS AND METHODS

In this prospective study, 72 consecutive patients with mediastinal lymphadenopathy, negative endoscopic investigations including bronchoscopic procedures, and no radiological evidence of lung cancer or other malignancies on computed tomography were enrolled. EUS-FNA and subsequent cytology, microscopy for acid-fast bacilli, and culture were performed. At least 12 months' follow-up including further investigations was included to exclude tuberculosis.

RESULTS

Adequate samples were obtained from 71/72 patients (36 male; mean age 50.2 years). No complications occurred. The final diagnosis included 30 cases of sarcoidosis, 28 of tuberculosis, four malignancies, one abscess, and nine benign lymphadenopathies. The size of lymph nodes on EUS varied from 0.5 cm to 4.2 cm. Tuberculosis nodes were significantly smaller than those in sarcoidosis. Unrelated nodes were significantly smaller than in either tuberculosis or sarcoidosis. The sensitivity, specificity, and positive and negative predictive values of EUS - FNA for tuberculosis were 86 %, 100 %, 100 %, and 91 %, respectively; those for sarcoidosis were 100 %, 93 %, 91 %, and 100 %, respectively. For culture of tuberculosis, they were 71 %, 100 %, 100 %, and 84 %, respectively. EUS - FNA led to a definite diagnosis in 64/72 cases (89 %) that had not been previously diagnosed by routine methods.

CONCLUSION

EUS - FNA offers a high diagnostic yield for the differential diagnosis of tuberculosis and sarcoidosis that have not been diagnosed by conventional methods.

Obstructive lung disease in acute medical patients

OBJECTIVES

To determine the proportion of adult medical patients who have chronic obstructive pulmonary disease (COPD), using the Global initiative for Chronic Obstructive Lung Disease guidelines (GOLD), and its relation to vascular disease.

METHODS

This is a prospective cross-sectional study of adult patients admitted to acute medical wards. Interviewer administered questionnaire, anthropometric and spirometric measurements were done.

RESULTS

Spirometry was performed in 720 acute admissions [Mean (SD) age 50.0 (18.9) years, FEV1: 1.98 L (0.83), FEV1/FVC%: 75.1 (11.9)%; males 332 (46.1%), smokers 318 (44%); 43.2% had vascular disease]. Sixty-seven per cent of patients (480) had no airway disease including 35 (4.5%) with chronic cough and sputum with normal spirometry; 89 (12.4%) had asthma and 151 (20.9%) had COPD. Patients with COPD were significantly older [60.3 (16.6) years] than non-COPD patients [47.3 (18.5) years], p < 0.001 and had a greater number of pack years of smoking. A greater percentage of patients with COPD had vascular disease (52%) than the non-COPD patients (40.1%), p = 0.017). Multivariate analysis with vascular disease as outcome variable revealed relationships with older age (p < 0.001) and Indo-Trinidadian ethnicity (p = 0.015), but not with gender (p = 0.321) and smoking (p = 0.442). FEV1% as well as FEV1 showed a significant inverse relationship with vascular disease (p < 0.05).

CONCLUSIONS

The prevalence of COPD using GOLD guidelines in acute hospital admissions is 20.9%; 11.7% of admissions have chronic sputum or cough with normal spirometry. Vascular disease is more prevalent in those with COPD. Patients admitted to acute medical care with vascular disease may also have COPD.

MMP-9, TIMP-1 and inflammatory cells in sputum from COPD patients during exacerbation

Background

Irreversible airflow obstruction in Chronic Obstructive Pulmonary Disease (COPD) is thought to result from airway remodelling associated with aberrant inflammation. Patients who experience frequent episodes of acute deterioration in symptoms and lung function, termed exacerbations, experience a faster decline in their lung function, and thus over time greater disease severity However the mechanisms by which these episodes may contribute to decreased lung function are poorly understood.

This study has prospectively examined changes in sputum levels of inflammatory cells, MMP-9 and TIMP-1 during exacerbations comparing with paired samples taken prior to exacerbation.

Methods

Nineteen COPD patients ((median, [IQR]) age 69 [63 to 74], forced expiratory volume in one second (FEV1) 1.0 [0.9 to1.2], FEV1% predicted 37.6 [27.3 to 46.2]) provided sputa at exacerbation. Of these, 12 were paired with a samples collected when the patient was stable, a median 4 months [2 to 8 months] beforehand.

Results

MMP-9 levels increased from 10.5 μg/g [1.2 to 21.1] prior to exacerbation to 17.1 μg/g [9.3 to 48.7] during exacerbation (P < 0.01). TIMP-1 levels decreased from 3.5 μg/g [0.6 to 7.8] to 1.5 μg/g [0.3 to 4.9] (P = 0.16). MMP-9/TIMP-1 Molar ratio significantly increased from 0.6 [0.2 to 1.1] to 3.6 [2.0 to 25.3] (P < 0.05). Neutrophil, eosinophil and lymphocyte counts all showed significant increase during exacerbation compared to before (P < 0.05). Macrophage numbers remained level. MMP-9 levels during exacerbation showed highly significant correlation with both neutrophil and lymphocyte counts (Rho = 0.7, P < 0.01).

Conclusion

During exacerbation, increased inflammatory burden coincides with an imbalance of the proteinase MMP-9 and its cognate inhibitor TIMP-1. This may suggest a pathway connecting frequent exacerbations with lung function decline.

Effects of exacerbations and seasonality on exhaled nitric oxide in COPD

Exhaled nitric oxide (eNO) appears to be associated with airway inflammation seen in chronic obstructive pulmonary disease (COPD). The present authors studied the effects of exacerbation, season, temperature and pollution on eNO. eNO was measured seasonally and at exacerbations in 79 outpatients suffering from COPD (mean forced expiratory volume in one second=42%). The effects of exacerbation symptoms, physiological and environmental parameters were analysed. Stable eNO levels were correlated positively with arterial oxygen tension. Median levels were found to be lower in smokers (5.3 ppb) than in ex- or nonsmokers (6.8 ppb). Levels were higher during October to December (6.9 ppb) than in April to June (4.6 ppb). Levels were also higher during 68 exacerbations in 38 patients (7.4 ppb) than in stable conditions (5.4 ppb), independent of the effects of smoking. The rise in eNO was greater in exacerbations that were associated with colds, a sore throat or dyspnoea combined with a cold. In conclusion, exhaled nitric oxide levels were higher in colder weather and in the autumn, perhaps related to the increased prevalence of viral infection at this time of year. The levels were lower in more severe chronic obstructive pulmonary disease. Exhaled nitric oxide levels were raised at the onset of exacerbation, particularly in the presence of a cold.

Relationship between exacerbation frequency and lung function decline in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterised by both an accelerated decline in lung function and periods of acute deterioration in symptoms termed exacerbations. The aim of this study was to investigate whether these are related.

METHODS

Over 4 years, peak expiratory flow (PEF) and symptoms were measured at home daily by 109 patients with COPD (81 men; median (IQR) age 68.1 (63-74) years; arterial oxygen tension (PaO(2)) 9.00 (8.3-9.5) kPa, forced expiratory volume in 1 second (FEV(1)) 1.00 (0.7-1.3) l, forced vital capacity (FVC) 2.51 (1.9-3.0) l); of these, 32 (29 men) recorded daily FEV(1). Exacerbations were identified from symptoms and the effect of frequent or infrequent exacerbations (> or < 2.92 per year) on lung function decline was examined using cross sectional, random effects models.

RESULTS

The 109 patients experienced 757 exacerbations. Patients with frequent exacerbations had a significantly faster decline in FEV(1) and peak expiratory flow (PEF) of -40.1 ml/year (n=16) and -2.9 l/min/year (n=46) than infrequent exacerbators in whom FEV(1) changed by -32.1 ml/year (n=16) and PEF by -0.7 l/min/year (n=63). Frequent exacerbators also had a greater decline in FEV(1) if allowance was made for smoking status. Patients with frequent exacerbations were more often admitted to hospital with longer length of stay. Frequent exacerbations were a consistent feature within a patient, with their number positively correlated (between years 1 and 2, 2 and 3, 3 and 4).

CONCLUSIONS

These results suggest that the frequency of exacerbations contributes to long term decline in lung function of patients with moderate to severe COPD.

Roles of cytoskeleton and tyrosine receptor mediated signal transduction in the restitution of isolated guinea pig gastric mucosa

BACKGROUND

The immediate response of the GI-epithelium to a superficial injury is primarily directed to restore the disturbed epithelial continuity in a process called restitution. The involvement of both structural (cytoskeleton) and humoral (growth factors and cytokines) signal transduction systems in the process has been documented. Previously, in experimental circumstances the role of the two systems has been examined as two distinct units. Nevertheless, in normal conditions in vivo, the two systems are presumably acting simultaneously. This study investigates the functional roles of cytoskeleton and tyrosine receptor mediated signalling in the regulation of restitution.

METHODS

Guinea pig gastric mucosa was mounted in Ussing-chamber, injured with 1.25 M NaCl and subsequently perfused for 4 h. Simultaneously, the electrophysiological resistance of the tissue (R) was recorded. During the recovery, the tissue was exposed bilaterally either to modulators of cytoskeleton (cytochalasin B/lysophosphatidic acid) or of tyrosine receptor mediated signalling (genistein/epidermal growth factor + transforming growth factor-alpha). After the experiment, the tissue was analysed morphologically and the proliferative index (PI) was determined morphometrically.

RESULTS

Exposure of the tissue to cytochalasin caused a significant decrease of both restitution (tissue resistance) and proliferation (PI), whereas simultaneous treatment with EGF+ TGFalpha restored both restitution and proliferation. Correspondingly, exposure of the tissue to genistein during restitution impaired the process as well as induction of proliferation, while simultaneous exposure to lysophosphatidic acid restored the processes. Exposure of the tissue to EGF+ TGFalpha and lysophosphatidic acid simultaneously resulted in a mild, but insignificant additive inductions of both restitution and proliferation.

CONCLUSIONS

Restitution is controlled by both structural and humoral signalling systems. If one of the regulating systems fails, stimulation of the other restores the process. Simultaneous stimulation of both systems has a minor additive effect on both restitution and proliferation.

Respiratory viruses, symptoms, and inflammatory markers in acute exacerbations and stable chronic obstructive pulmonary disease

The effects of respiratory viral infection on the time course of chronic obstructive pulmonary disease (COPD) exacerbation were examined by monitoring changes in systemic inflammatory markers in stable COPD and at exacerbation. Eighty-three patients with COPD (mean [SD] age, 66.6 [7.1] yr, FEV(1), 1.06 [0.61] L) recorded daily peak expiratory flow rate and any increases in respiratory symptoms. Nasal samples and blood were taken for respiratory virus detection by culture, polymerase chain reaction, and serology, and plasma fibrinogen and serum interleukin-6 (IL-6) were determined at stable baseline and exacerbation. Sixty-four percent of exacerbations were associated with a cold occurring up to 18 d before exacerbation. Seventy-seven viruses (39 [58.2%] rhinoviruses) were detected in 66 (39.2%) of 168 COPD exacerbations in 53 (64%) patients. Viral exacerbations were associated with frequent exacerbators, colds with increased dyspnea, a higher total symptom count at presentation, a longer median symptom recovery period of 13 d, and a tendency toward higher plasma fibrinogen and serum IL-6 levels. Non-respiratory syncytial virus (RSV) respiratory viruses were detected in 11 (16%), and RSV in 16 (23.5%), of 68 stable COPD patients, with RSV detection associated with higher inflammatory marker levels. Respiratory virus infections are associated with more severe and frequent exacerbations, and may cause chronic infection in COPD. Prevention and early treatment of viral infections may lead to a decreased exacerbation frequency and morbidity associated with COPD.

Sputum and plasma endothelin-1 levels in exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Endothelin (ET)-l is a bronchoconstrictor peptide produced in the airways. It has been implicated in the pathogenesis of asthma and virally mediated airway inflammation and may play a role in exacerbations of chronic obstructive pulmonary disease (COPD).

METHODS

Seventy one patients with COPD were followed prospectively and sampled for plasma and sputum ET-1 levels when stable and during an exacerbation. Sputum was also examined for cytokines, human rhinovirus, and Chlamydia pneumoniae.

RESULTS

Plasma ET-1 levels were available for 67 patients with stable COPD (mean (SD) 0.58 (0.31) pg/ml); 28 pairs of stable-exacerbation plasma samples had a mean stable ET-1 level of 0.54 (0.30) pg/ml rising to 0.67 (0.35) pg/ml at exacerbation (mean difference 0.13, 95% confidence interval (CI) 0.04 to 0.21, p = 0.004). Plasma ET-1 levels in the 67 patients with stable COPD were inversely correlated with baseline forced expiratory volume in one second (FEV(1); r = -0. 29, p = 0.022) and forced vital capacity (FVC; r = -0.38, p = 0.002). The change in plasma ET-1 levels during an exacerbation correlated with the change in oxygen saturation (SaO(2); r = -0.41, p = 0.036). In 14 stable-exacerbation pairs of sputum samples median stable ET-1 levels were 5.37 (0.97-21.95) pg/ml rising to 34.68 (13.77-51.95) pg/ml during an exacerbation (mean difference 25.14, 95% CI 3.77 to 46.51, p = 0.028). This increase in sputum ET-1 levels correlated with the increase in plasma ET-1 levels (r = 0.917, p = 0.001) and sputum interleukin (IL)-6 levels (r = 0.718, p = 0.013).

CONCLUSIONS

Sputum levels of ET-1 rise in COPD patients during an exacerbation and this is reflected by a smaller rise in plasma ET-1 levels. ET-1 may have a role in mediating airway inflammatory changes during exacerbations of COPD.

Detection of rhinovirus in induced sputum at exacerbation of chronic obstructive pulmonary disease

Common colds are associated with exacerbations of chronic obstructive pulmonary disease (COPD). However, the role of the common cold virus (human rhinovirus) in the production of symptoms and lower airway inflammation at COPD exacerbation is unknown. Thirty three patients with moderate-to-severe COPD were seen at baseline, when the number of chest infections in the previous year was noted, and acutely at COPD exacerbation. Within 48 h after the onset of the exacerbation and at baseline, nasal aspirates and induced sputum were taken for rhinovirus reverse transcriptase polymerase chain reaction (RT-PCR) analysis and determination of cytokine levels. Symptoms, recorded on diary cards, were noted and forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) measured. At exacerbation, mean FEV1 and FVC fell significantly from baseline (p<0.001). Ten of 43 exacerbations were associated with rhinovirus infection, detected in induced sputum. In four of these, nasopharyngeal samples contained no detectable rhinovirus. All baseline samples were negative for rhinovirus. The simultaneous presence of increased nasal discharge/nasal congestion (in 26 of the 43 exacerbations) and increased sputum (29 exacerbations) was strongly associated with the presence of rhinovirus (odds ratio 6.15; p=0.036). Total symptom scores were greater for rhinovirus as compared to nonrhinovirus exacerbations (p=0.039). Median baseline sputum interleukin-6 levels rose from 90.2 to 140.3 pg x mL(-1) at exacerbation (p=0.005); the change was greater in the presence of rhinovirus infection (p=0.008). Rhinovirus infection can be detected at chronic obstructive pulmonary disease exacerbation. This is associated with elevation of lower airway interleukin-6 levels, which may mediate lower airway symptom expression during chronic obstructive pulmonary disease exacerbations.

Acute exacerbations of chronic obstructive pulmonary disease are accompanied by elevations of plasma fibrinogen and serum IL-6 levels

BACKGROUND

Respiratory tract infections may acutely increase risk from coronary heart disease (CHD), though the mechanisms have not been defined. Patients with chronic obstructive pulmonary disease (COPD) are prone to repeated exacerbations that are often associated with respiratory infections. These patients also have increased cardiovascular morbidity and mortality. We hypothesized that transient acute increases in plasma fibrinogen, an independent risk factor for CHD, could occur at COPD exacerbation (mediated through a rise in IL6) and thereby provide a mechanism linking respiratory infection to risk of coronary heart disease.

METHODS

93 COPD patients [mean (SD) age 66.8 (8.1) years] were followed regularly over one year, with daily diary card monitoring of respiratory symptoms and peak expiratory flow rate (PEFR); 67 patients [mean FEV1 1.06 (0.44) l, FVC 2.43 (0.79) l] were seen during 120 exacerbations. At each visit spirometry was measured and blood samples taken for plasma fibrinogen and Interleukin-6 (IL-6) levels.

RESULT

At baseline, the mean (SD) plasma fibrinogen was elevated at 3.9 (0.67) g/l in the 67 patients with exacerbations during the study and the median (IQR) IL-6 at 4.3 (2.4 to 6.8) pg/ml. Plasma fibrinogen increased by 0.36 (0.74) g/l at exacerbation (p <0.001). with IL-6 levels rising by 1.10 (-2.73 to 6.95) pg/ml (p = 0.008). There was a relation between the changes in fibrinogen at exacerbation and IL-6 levels (r = 0.348, p <0.001). Multiple regression revealed significantly greater rises in fibrinogen when exacerbations were associated with purulent sputum (b = 0.34 g/l; p = 0.03), increased cough (b = 0.31 g/l, p = 0.019) and symptomatic colds (b = 0.228; p = 0.024).

CONCLUSIONS

Plasma fibrinogen levels were elevated in stable patients with COPD and may contribute to the increased cardiovascular morbidity and mortality in these patients. COPD exacerbations increased serum IL-6 levels, leading to a rise in plasma fibrinogen. Thus acute rather than chronic infection may have a role in predisposing to coronary heart disease or stroke.

Penetrating neck injury: case report and evaluation of management

Greater urban violence has resulted in an increased incidence of penetrating neck trauma. Penetrating neck wounds can present difficult diagnostic and therapeutic dilemmas. The evaluation and management of such injuries, however, remains controversial. There is no universally accepted specific approach to the management of patients with penetrating neck injuries, with some surgeons advocating mandatory neck exploration whilst others believe in selective surgical intervention. We believe that an equal willingness for both conservative and surgical intervention as dictated by serial bedside evaluation with adequate radiological and endoscopic support can provide the clinician a safe and effective means of managing a potentially complex and lethal problem.

Time course and recovery of exacerbations in patients with chronic obstructive pulmonary disease

Although exacerbations of chronic obstructive pulmonary disease (COPD) are associated with symptomatic and physiological deterioration, little is known of the time course and duration of these changes. We have studied symptoms and lung function changes associated with COPD exacerbations to determine factors affecting recovery from exacerbation. A cohort of 101 patients with moderate to severe COPD (mean FEV(1) 41.9% predicted) were studied over a period of 2.5 yr and regularly followed when stable and during 504 exacerbations. Patients recorded daily morning peak expiratory flow rate (PEFR) and changes in respiratory symptoms on diary cards. A subgroup of 34 patients also recorded daily spirometry. Exacerbations were defined by major symptoms (increased dyspnea, increased sputum purulence, increased sputum volume) and minor symptoms. Before onset of exacerbation there was deterioration in the symptoms of dyspnea, sore throat, cough, and symptoms of a common cold (all p < 0.05), but not lung function. Larger falls in PEFR were associated with symptoms of increased dyspnea (p = 0.014), colds (p = 0.047), or increased wheeze (p = 0.009) at exacerbation. Median recovery times were 6 (interquartile range [IQR] 1 to 14) d for PEFR and 7 (IQR 4 to 14) d for daily total symptom score. Recovery of PEFR to baseline values was complete in only 75.2% of exacerbations at 35 d, whereas in 7.1% of exacerbations at 91 d PEFR recovery had not occurred. In the 404 exacerbations where recovery of PEFR to baseline values was complete at 91 d, increased dyspnea and colds at onset of exacerbation were associated with prolonged recovery times (p < 0.001 in both cases). Symptom changes during exacerbation do not closely reflect those of lung function, but their increase may predict exacerbation, with dyspnea or colds characterizing the more severe. Recovery is incomplete in a significant proportion of COPD exacerbations.

Relation of sputum inflammatory markers to symptoms and lung function changes in COPD exacerbations

BACKGROUND

Although it is presumed that exacerbations of chronic obstructive pulmonary disease (COPD) are associated with increased airway inflammation, there is little information available on inflammatory markers during an exacerbation and the relationship with severity or time course of recovery. A study was undertaken to investigate the sputum cell and cytokine characteristics of COPD when stable and during an exacerbation.

METHODS

Induced sputum samples from 57 patients with moderate to severe COPD were analysed (44 samples were taken during a stable period and 37 during an exacerbation). The patients recorded daily symptoms on diary cards. Cell counts and sputum levels of interleukin (IL)-6 and IL-8 were measured.

RESULTS

Patients with >/=3 exacerbations/year had higher median stable sputum levels of IL-6 (110 (95% CI 11 to 215) pg/ml) and IL-8 (6694 (95% CI 3120 to 11995) pg/ml) than those with </=2 exacerbations/year (22 (95% CI 12 to 93) and 1628 (95% CI 607 to 4812) pg/ml, respectively). Median IL-6 levels were increased during exacerbations compared with stable conditions. The levels of IL-6 during exacerbations were related to the presence of a cold and to the total cell count and eosinophil and lymphocyte numbers, while IL-8 was positively correlated with all sputum cell counts. Sputum cell counts and cytokine levels during an exacerbation did not predict the size and duration of lung function changes in the exacerbation.

CONCLUSIONS

Patients with more frequent exacerbations have higher baseline sputum cytokine levels, which may predict the frequency of future exacerbations.

Comparison of spontaneous and induced sputum for investigation of airway inflammation in chronic obstructive pulmonary disease

BACKGROUND

Although sputum induction is used as a technique to investigate lower airway inflammation in asthmatic subjects, advantages over spontaneous sputum in patients with chronic obstructive pulmonary disease (COPD) have not been investigated.

METHODS

Samples of spontaneous sputum and sputum induced with 3% hypertonic saline for 14 minutes were collected from 27 patients with chronic obstructive pulmonary disease (COPD) who usually produced spontaneous sputum. Spirometric indices and oxygen saturation (Sao2) were measured at seven minute intervals. The spontaneous, seven and 14 minute sputum samples were analysed for total and differential cell counts, cell viability, and interleukin 8 levels.

RESULTS

Analysis of the sputum revealed that median cell viability was higher in the seven minute (62.8%; p = 0.004) and 14 minute (65%; p = 0.001) induced sputum samples than in spontaneous sputum (41.2%). There was no significant difference in total and differential cell counts or in interleukin 8 levels between spontaneous and induced sputum. During the sputum induction procedure the mean (SD) fall in forced expiratory volume in one second (FEV1) was 0.098 (0.111) 1 (p < 0.001) and in forced vital capacity (FVC) was 0.247 (0.233) 1 (p < 0.001). There was a small but significant fall in Sao2 during sputum induction (p = 0.03).

CONCLUSIONS

Induced sputum contains a higher proportion of viable cells than spontaneous sputum. There are no significant differences between the sputum samples obtained at seven minutes and at 14 minutes of hypertonic saline nebulisation. Sputum induction is safe and well tolerated in patients with COPD.

Induction of proliferation in isolated guinea pig gastric epithelium during restitution after superficial injury

Immediate repair of the gastrointestinal epithelium after superficial injury is called restitution. It is based on the migration of the surviving mucoid neck cells over the area of injury. The involvement of growth factors in the process has been recently documented. They are known to enhance the process (ie, EGF, FGF, TGF-beta) and to activate the basolateral Na+-H+-antiport (EGF). They may exert their effect by activating intracellular tyrosine kinases or by inducing chemotaxis. Yet, their precise mechanism of action in the process is unknown. The aim of the present study was to investigate the effect of modulation of the signal transduction pathway on the occurrence of proliferative mucoid neck and foveolar cells in guinea pig gastric epithelium. Therefore guinea pig gastric epithelium was mounted in Ussing chambers in vitro and perfused 4 hr after superficial injury with 1.25 M NaCl. The potential difference over the epithelium and tissue resistance were recorded simultaneously. The tissue was exposed either to cycloheximide, genistein, or to 4-phorbol myristate 13-acetate (PMA) during the 4-hr recovery, and the expression of proliferative cells was assessed by staining the tissue for proliferative cells (Ki-67). The mean proliferative index of tissues subjected to NaCl injury was significantly higher than that of uninjured control tissues after 4 hr of restitution. Inhibition of the signaling pathway with genistein decreased the proliferative index significantly, while its stimulation with phorbol myristate increased it. Both electrophysiologic and morphologic restitution were sensitive to genistein, but not to PMA or cycloheximide. Superficial epithelial injury results in a significantly increased occurrence of proliferative cells in isolated guinea pig gastric epithelium. This endogenous activation of the tissue is sensitive to inhibition by tyrosine kinases and to stimulation by protein kinases. Electrophysiologic and morphologic recovery are also affected by the modulation of the signaling pathway. This suggests that it is involved in the immediate repair process.

Role of Na(+)-H(+)-antiport in restitution of isolated guinea pig gastric epithelium after superficial injury

In addition to its pHi regulatory function Na(+)-H(+)-antiport is also involved in volume regulation of epithelial cells, particularly in neutral conditions. It is also known that the antiport is activated after ligand binding following growth factor receptor activation. The aim of the present study was to evaluate the role of the antiport in restitution of gastric mucosa and whether its activity is dependent on the type of superficial injury. Therefore the fundic epithelium of guinea pig stomach was perfused in an Ussing chamber in neutral conditions. Na(+)-H(+)- and Cl(-)-HCO3(-)-antiports were inhibited with 1.0 mM amiloride, 1.0 mM SITS, or with HCO3- removal and Na(+)-K(+)-2Cl(2-)-cotransporter with 0.3 M furosemide during 4 hr of restitution after superficial injury induced either by 1.25 M NaCl or by 1.0% Triton. Luminal exposure of the epithelium to amiloride had no effect on restitution but serosal application abolished the process completely. The inhibitory effect of amiloride was similar after both NaCl and Triton injury. The inhibition of Cl(-)-HCO3(-)-antiport with SITS interfered with the process as well, while HCO3- removal had no significant inhibitory effect, nor did the inhibition of Na(+)-K(+)-2Cl(-)-cotransporter. The morphologic findings were in accordance with the electrophysiologic measurements in each pair of tissues. It is concluded that the Na(+)-H(+)-antiport is essential for the epithelial cells during restitution even in neutral conditions, but a functional Cl(-)-HCO3(-)-antiport is also required. The activity of Na(+)-H(+)-antiport is sensitive to basolateral amiloride and is necessary regardless of the type of chemical injury.