Background: Lung cancer has a dreadful prognosis and is the leading cause of cancer deaths in the world and in the UK. The UK survival rates are particularly poor when compared with survival in other countries in Europe. More than two-thirds of people with lung cancer in the UK are diagnosed at a late stage when curative treatment is no longer possible. Since lung cancer survival rates are higher with earlier diagnosis, there is need to diagnose cases earlier. This suggests a potential to examine and if possible, modify the care pathway for people with lung cancer to achieve earlier diagnosis. Aim: The overall aim of this thesis was to explore the patient characteristics and interactions in primary care before the diagnosis of lung cancer, as a means of identifying the features that are predictive of lung cancer and the potential for earlier diagnosis. To achieve this aim, it was necessary to investigate and validate the use of lung cancer data from The Health Improvement Network. Methods: The Health Improvement Network (THIN) database of United Kingdom general practice records, was used to identify and study the characteristics of cases of lung cancer in the UK. To ensure that THIN was a valid source of lung cancer information for research, a study was done to assess the completeness and representativeness of the lung cancer data in THIN by comparing the lung cancer patient characteristics, incidence and survival in THIN with the UK National Cancer Registry and the National Lung Cancer Audit Database. Experian's Mosaic Public Sector variable linked into THIN database was then used to identify detailed profiles of the UK sectors of society where lung cancer incidence was highest as a means of exploring the potential of using this geo-demographic tool to facilitate disease ascertainment. Two case-control datasets were developed from the database using the identified cases of lung cancer. The first dataset was matched on age, sex and general practice and it was used to carry out three studies in this thesis. The first study was a pilot study of methods to identify the socio-demographic and clinical features independently associated with lung cancer as well as to identify the timing of these clinical features before lung cancer was diagnosed. This was followed by two studies to examine separate hypotheses on the variation in lung cancer risk firstly between smokers of different socioeconomic status, then between smokers with and without a recorded history of depression, as socioeconomic deprivation and depression are both associated with increased prevalence of cigarette smoking. The second case-control dataset was matched only on practice and this dataset expanded on the methods from the pilot study to identify the socio-demographic factors including age and sex, as well as the early clinical features that are predictive of lung cancer. This was followed by a study which used the identified predictors to develop and validate a risk-prediction model for lung cancer. The model validation was carried out using another dataset of patients in a more recent version of THIN with records spanning a time period after the last date of records for patients used for the earlier studies in the thesis. Results: A study population of 12,135 patients with incident lung cancer were identified from the 1st of January 2000 to the 28th of July 2009. The overall incidence of lung cancer, median survival and general lung cancer patient characteristics in THIN were similar to other national lung cancer databases - The National Lung Cancer Audit Data and the UK National Lung Cancer Registry data from the Office of National Statistics. Mosaic™ classifications identified wider variations in lung cancer incidence than existing markers of socioeconomic deprivation and therefore allowed more detailed classifications of the UK sectors of society where lung cancer incidence was highest. For example the incidence rate in Mosaic Public Sector™ type I50 (Cared-for pensioners) was 31.2 times higher (IRR 31.2; 95% CI 21.9-44.5) than the incidence rate in Mosaic Public Sector™ type B10 (Upscale new owners). With regards to the risk of lung cancer among smokers from different socioeconomic groups, stratified analyses of the association between smoking and lung cancer by Townsend deprivation quintiles showed that the risks of lung cancer were similar in smokers of different socioeconomic status. Depression was associated with a 30% increased risk of lung cancer (odds ratio 1.30; 95% CI 1.24-1.38) which was completely explained by smoking. Cigarette smoking was more common and levels of consumption were higher among depressed compared to non-depressed individuals. Stratified analyses of the association between smoking and lung cancer by depression showed that there was no difference in lung cancer risk among depressed and non-depressed smokers. Socio-demographic features - age, sex, socioeconomic status and smoking, increase in the frequency of general practice consultations as well as early records of presentation for symptoms of cough, haemoptysis, dyspnoea, weight loss, lower respiratory tract infections, non-specific chest infections, chest pain, hoarseness, upper respiratory tract infections and Chronic Obstructive Pulmonary Disease (COPD) were found to be independently associated with lung cancer 4 to 12 months before diagnosis. A risk prediction model was developed with these variables, and on validation using an independent THIN dataset of 1,826,293 patients, the model performed well with an area under the curve statistic of 0.88. Conclusions: Routine electronic data in THIN are a valid source of lung cancer information for research. Mosaic™ identifies greater incidence differentials than standard area-level measures and as such could be used as a tool for public health programmes to ascertain future cases more effectively. Neither socioeconomic deprivation nor a history of depression increases an individuals' vulnerability to the carcinogenic effects of cigarette smoke. The increase in lung cancer risk among more deprived individuals and those with depression is largely explained by the greater cigarette consumption by these groups of people. Smoking cessation interventions targeted to these groups of people are needed to reduce the lung cancer-related health inequalities associated with deprivation and depression. A combination of patients' age, sex, socioeconomic characteristics, smoking status and early stage symptoms in general practice aid earlier identification of patients at increased risk of lung cancer. The model developed using these variables performed substantially better than the current NICE referral guidelines and all comparable models, being able to predict lung cancer early enough to make detection at a potentially curable stage feasible by allowing general practitioners to better risk-stratify their patients.

Hyperpolarized noble gas MRI using 3He and 129Xe has allowed void space imaging of the lungs for several years. Hyperpolarized 83Kr MRI has also been shown to provide an MRI contrast sensitive to the surface-to-volume ratio and chemistry of synthetic porous systems. Ex vivo animal models of pulmonary diseases and in vitro experiments were used in this thesis to examine three methodological advances allowing for the measurement of pulmonary physiological parameters using 129Xe and 83Kr. The 83Kr quadrupolar property was explored in a rat model of pulmonary surface-to-volume ratio degradation, i.e. emphysema. The surface quadrupolar relaxation (SQUARE) of the noble gas provided maps of the longitudinal relaxation in control and emphysematous rat lungs. The relaxation observations were regionally correlated to the histological measurements of the alveolar degradation. The 129Xe solubility in the lungs, blood, and more generally liquids, was the basis for the design of a new biosensor composed of a cryptophane cage tethered to a paramagnetic agent. The depolarization of the 129Xe atoms encapsulated by the cryptophane, followed by chemical exchange with the surrounding medium was investigated in vitro. This model biosensor will lead to a future switchable biosensor that will be deactivated by the enzymatic cleavage of the encapsulating cage and the paramagnetic agent. Finally, the 129Xe solubility was further utilised to study the gas transfer through ex vivo rat lungs after blood replacement by a perfluorocarbon emulsion. The large chemical shift separating the 129Xe peaks for the gas phase, the tissue and the perfluorocarbon emulsion, allowed for a selective excitation of each phase and the independent observation of their signal build-up after inhalation. This mechanism will be used as a biomarker for gas transfer impairment in animal models of pulmonary fibrosis.

Background: The United Kingdom (UK) has poor lung cancer survival rates compared to other countries, and this is partly explained by differences in early mortality. In order to diagnose lung cancer at an earlier stage in the UK there is a pressing need to understand the management process from the recognition of symptoms by people with lung cancer, through the initial interactions with primary care to the referral to secondary care and the choice of the subsequent treatment plan. Objectives: The aim of this thesis is to use mixed methods to identify some of the factors which may affect the diagnosis and prognosis in patients with lung cancer in the United Kingdom across the whole patient pathway. Methods: Prospectively collected clinical data were used in conjunction with qualitative methodology. Primary care records were obtained from The Health Improvement Network, alongside data from the National Lung Cancer Audit (NLCA), linked to Hospital Episode Statistics and Office for National Statistics datasets. Case-control and cohort studies were conducted using multivariable logistic regression to look at independent associations with early mortality, likelihood of receiving surgery and place of death. Survival analyses were performed using Kaplan Meier curves and Cox regression and validation studies used area under the receiver operating curves (AUC). The Framework approach was used to identify themes and sub-themes arising from focus group interviews. Results: Mixed methods were used to look at barriers to early diagnosis and attitudes towards lung cancer screening in a high risk population. A number of key practical and emotional barriers which may impact on screening uptake were identified, alongside the issue of smoking stigma and blame. Primary care data were used to look at predictors of early (0-90 day) mortality in the UK. Thirty per cent of patients with lung cancer died within 90 days of diagnosis. Increasing age, male sex, socioeconomic deprivation, rural versus urban location and current smoking were all independently associated with early death. Patients who had poorer prognosis did interact with primary care before diagnosis, suggesting missed opportunities to identify them earlier. NLCA data linked to organisational audit data highlighted inequities between Trusts, in particular with regards to variability in the workload of specialists and differences in access to diagnostic and therapeutic modalities. On site access to positron emission computed tomography, stereotactic ablative radiotherapy and video-assisted thoracoscopic lobectomy were independently associated with increased likelihood of receiving surgery for lung cancer. Records for patient who developed brain metastases following radical surgical treatment for lung cancer were reviewed. Those with more advanced disease stage, younger age and adenocarcinoma sub-type were more likely to develop metastases and modelling suggested that 71% may have been visible pre-operatively had magnetic resonance imaging of the brain been performed as part of the staging process. An internal and external validation was performed to assess the ability of two risk scoring systems to predict 90 day post-operative mortality. AUC values for internal and external validation of the NLCA score and validation of Thoracoscore were 0.68 (95% CI 0.63-0.72), 0.60 (95% CI 0.56-0.65) and 0.60 (95% CI 0.54-0.66) respectively. Post-hoc analysis was performed using NLCA records on 15554 surgical patients to derive summary tables for 30 and 90 day mortality, stratified by procedure type, age and performance status. Linked NLCA data were used to look at place of death from lung cancer. Thirty-five per cent of patients with lung cancer die in acute hospital beds, with male sex, old age (≥ 85 years), socioeconomic deprivation, WHO performance status 4 at diagnosis and emergency route to diagnosis all independently associated with increased likelihood of death in this setting. There is marked geographical variation in place of death, particularly with regard to provision of hospice services. Conclusions: The studies described in this thesis use prospectively collected data to provide a snapshot of different aspects of the lung cancer patient journey which may impact on prognosis, alongside qualitative methodology to try to determine reasons for diagnostic delay and attitudes towards screening programmes. There remain some important clinical questions about lung cancer care and outcomes which need to be looked at to provide a greater understanding of where the inequities in the lung cancer patient pathway in the UK lie and to try to address modifiable factors with an aim to improve outcomes.

Clinicians use several oxygen-based indices in intensive care units as surrogates to determine the condition of the patient’s lung and verify monitoring progress. Examples of these oxygen indices include the ratio of arterial oxygen tension to inspired oxygen fraction (PaO2/FiO2 ratio); arterial/alveolar oxygen tension ratio (PaO2/PAO2); alveolar–arterial oxygen tension difference (PA-aO2); respiratory index (RI= (PA-aO2)/PaO2), and content-based venous admixture (Qs/Qt). One of the issues with this approach is that these indices fail to take into consideration several additional external pulmonary physiological factors and, as such, these indices could potentially mislead clinicians. This thesis explores the nature of the oxygen-tension-based indices response and examined the effect that varying certain external pulmonary factors, such as FiO2, PaCO2, Hb, respiratory rate, oxygen consumption, cardiac output, and respiratory quotient, had on PaO2 using virtual subjects and patients’ data to quantify oxygenation defect through a combination of mathematics, different diseases, and pathophysiology. There were one or two approaches that could lead us to the answer, and many dead end routes. Eventually, the research produced a new index that was compared and validated using two approaches. First, on virtual subjects with lung pathologies that were commonly seen in the intensive care unit and then on real clinical data that was obtained from the intensive care unit. The results of these validation investigations indicated that the proposed index is more robust and resistant to variations in certain external pulmonary factors than the PaO2/FiO2 ratio. As such, there is a strong indication that it may help to improve the quality of patient care provided. The feasibility of manually calculating and applying this newly proposed index in the ICU is an issue that merits further exploration. Theoretically, if the newly proposed index was found to be practicable, it could improve the healthcare provided; reduce the cost of unnecessary blood work, and save time and effort. However, due to the time it takes to calculate crPaO2 manually, the use of medical technology and computer applications is desirable.

Thesis (MSc(Med)(Pharmacy) ) -- University of Limpopo, 2013. / Introduction: Primary Health Care (PHC) is regarded as the first level of contact with the National Health System with health care services provided mainly by nurses with varying competences. PHC is about interaction with people thus the quality of PHC depends extensively on the competence of the people who provide it. Therefore, the way health care personnel are trained and how capacity continues to be developed is of fundamental importance to PHC. Following the Alma-Ala Declaration, policies, such as the National Drug Policy (NDP) were developed in South Africa to guide health care services. The NDP resulted in the formulation of Standard Treatment Guidelines/Essential Medicine List (STGs/EML). Emphasis has been placed on all prescribers to strictly adhere to these guidelines when providing clinical patient care. Despite these developments reports still indicate that antibiotics are irrationally used when treating respiratory infections. It is therefore imperative that localised reasons for deviations from the STGs/EML when treating respiratory conditions are thoroughly investigated to facilitate relevant interventions. Objectives: The objectives of the study were to: (1) document the treatment prescribed to children up to 12 years of age for respiratory conditions, (2) assess adherence of the authorised prescribers to the 2008 PHC STGs/ EML and (3) determine factors impacting on deviations from the 2008 STGs/EML. Method: Twenty randomly selected PHC facilities in the district participated in the study. In each of the 20 selected PHC facilities, three prescribers were randomly selected for the structured interview and auditing of their prescription registers. Five prescriptions from each of the sampled prescription registers of the selected authorised prescribers, containing any of the children's respiratory conditions to be studied, were audited. A total of 15 prescriptions from each of the selected PHC facilities were audited. Descriptive statistics was used to xii analyse data and responses to categorical variables were summarised as frequency counts and percentages. Results were presented as tables, figures and graphs. Results: Pneumonia (39.7%) was found to be the most common respiratory condition seen at Umkhanyakude Health District followed by the common cold and influenza. Amoxicillin (52%) was the most often prescribed antibiotic for these respiratory conditions. Only 4% of prescribers showed full adherence to the 2008 PHC STGs/EML. While prescribers had a positive attitude towards the 2008 PHC STGs/EML, their sense of adherence, content understanding of these guidelines, as well as knowledge of medicine used for respiratory conditions, were exaggerated. Failure to accurately diagnose respiratory conditions and lack of implementation and monitoring strategies were also amongst the factors impacting on adherence. Conclusion: Adherence to the 2008 PHC STGs/EML for the treatment of respiratory conditions in children up to 12 years of age was found to be a challenge in Umkhanyakude PHC facilities with only four percent of prescribers adhering to these guidelines. The Umkhanyakude Health District Management team must consider employing multifaceted interventions from the recommendations of this study in order to improve adherence to the PHC STGs/EML. Recommendations: Strategies such as intensified monitoring and evaluation, improved supervision, targeted training and education together with compulsory in-service training are recommended to improve adherence to the STGs/EML in the Umkhanyakude Health District. Guideline implementation strategies with integrated approaches to guideline dissemination must also be strengthened.

Introduction: Lung cancer is the commonest cause of cancer related death in men and women in England. In 2004 the National Lung Cancer Audit (NLCA) was created, as a national non-mandatory contemporary dataset of clinical features of individuals with lung cancer in part to identify variations in clinical practice and outcomes. The main aims of this dissertation are to determine the validity and representativeness of this dataset and then to investigate what factors influence access to surgery and chemotherapy and subsequent survival. In addition I have taken the opportunity afforded by this large dataset to describe the natural history of lung cancer in young adults (20-40 years). Methods: In order to establish if the dataset was representative, I created a measure of case ascertainment at the level of an NHS Trust, and examined the distribution of patient features and outcomes for varying levels of case ascertainment. I have then quantified the impact of patient and NHS Trust level features on access to surgery in people with non-small cell lung cancer and access to chemotherapy in people with small cell lung cancer using multivariate logistic regression. I have also conducted a series of survival analyses using Cox regression. Results: I have found no evidence that patient features vary systematically according to levels of case ascertainment in the NLCA. Age, sex, performance status, stage and co-morbidity all influenced the likelihood of having surgery for people with non-small cell lung cancer. Those patients first seen in a thoracic surgical centre where more likely to receive surgery than patients seen at peripheral centres (adjusted OR 1.51, 95% CI 1.16, 1.97), and surgery had a significant benefit on mortality (adjusted HR 0.41, 95% CI 0.39, 0.44). Although the resection rate was higher for patients first seen at a surgical centre (17% v 12%) these patients did equally well after surgery suggesting they were not a higher risk group. Individuals with small cell lung cancer first seen in a hospital with a high participation in clinical trials, (>5% of expected lung cancer patients being entered into clinical trials), were more likely to receive chemotherapy (adjusted OR 1.42, 95% CI 1.06, 1.90). Chemotherapy was associated with an improvement in survival (adjusted HR 0.51, 95% CI 0.46, 0.56), and amongst those patients receiving chemotherapy, mortality was not affected by the trial status of the hospital where they were first seen. In limited stage small cell disease, those patients who had chemo-radiotherapy had an improved survival compared with those patients who received chemotherapy alone (adjusted HR 0.72, 95% CI 0.62, 0.84). This dataset of English patients with lung cancer contains one of the largest cohorts of young adults (20-40 years) with lung cancer (N=583). I have been able to demonstrate that the majority present with a good performance status (0 or 1 in 80% of those with PS recorded), but advanced (stage IV) disease at diagnosis (55% of those with stage recorded). Those who have surgery have a survival profile similar to their older counterparts. Conclusion: The National Lung Cancer Audit is a representative, contemporary cohort of people with lung cancer, which can provide valuable information for health service research in lung cancer. I have found evidence that there is variation in access to treatment based on the facilities or the performance of individual NHS Trusts. My results suggest that by improving access to thoracic surgery for those individuals with non-small cell lung cancer we may be able to raise the resection rate and improve five year survival. The pattern is similar for people with small cell lung cancer and access to chemotherapy. What this research cannot explain is the aetiology for this variation, and where in the diagnostic pathway changes need to be made to improve the active management and access to potentially curative regimes. As the audit matures with more detailed information on NHS Trust level care, further analyses will be possible to try and determine more clearly what explains these variations, and how we might intervene to reduce them.

Background: The hypothesis that paracetamol may increase the risk of asthma and other allergic disease has gained consistent support from epidemiological studies, but evidence from longitudinal cohort studies, particularly those looking at the timing and dose of exposure are lacking. Epidemiological studies have also reported an inverse relation between gastro-intestinal infections including Helicobacter pylori, commensal bacteria and geohelminths and asthma and allergic disease, however, data from longitudinal birth cohort study are scarce. This thesis has therefore investigated the effects of paracetamol, H. pylori and other gastro-intestinal infections on the incidence and prevalence of allergic diseases and sensitization in a low-income birth cohort in which confounding by social advantage and other medical interventions is unlikely to play a role. Methods: In 2005/6 a population based cohort of 1065 pregnant women from Butajira, Ethiopia was established, to whom 1006 live singleton babies were born, and these children have been followed-up from birth to age five. At ages one, three and five, the International Study of Asthma and Allergies in Children (ISAAC) questionnaires were administered to the mothers to obtain data on wheeze, eczema and rhinitis. Allergen skin tests to Dermatophagoides pteronyssinus and cockroach were performed at ages three and five. Data on child's use of paracetamol, and various early life putative risk factors, including levels of Der p 1 and Bla g 1 allergen in the child's bedding and symptoms of respiratory tract infections were also measured. Stool samples were collected at ages three and five for analysis of H. pylori antigen using a rapid test (Medimar immunocard), as well as for geohelminths (at ages one, three and five) and selected commensal bacteria (at age three). Multivariate logistic regression was used to determine the independent effects of various markers of paracetamol use on the incidence of each outcome between age one and five, as well as on prevalence at age five. Similar analyses were also carried out to determine the independent effects of H. pylori, geohelminths and commensals on the incidence and prevalence of each outcome. Results: Effects of paracetamol: Of the 1006 children in the cohort at birth, 863 children were successfully followed up at age five (94% of surviving mother-child dyads). Wheeze and eczema incidence between the ages of one and five were reported in 5.9% (40/676) and 5.8% (39/700) of children respectively, and rhinitis and sensitization incidence between ages three and five were found in 3.9% (31/798) and 2.0% (15/766) of children respectively. Paracetamol use in the first three years of life was common, with 18% reported use at age one but not three, 23% at age three but not one and 21% at both time points. Use in the first year of life was significantly associated with a dose-dependent increased risk of incident wheeze between ages one and three (fully adjusted ORs, 95% CI, 1.77; 0.96, 3.26 for 1-3 tablets and 6.78; 1.89, 24.39 for ≥ 4 tablets in past month versus never), but not eczema. The risk of incident wheeze, eczema, rhinitis and sensitization between ages three and five was increased in those exposed, significantly so for incident eczema (p=0.02) and borderline significant for rhinitis (p=0.07), with fully adjusted odds ratios (ORs), including for symptoms of respiratory tract infections, for persistent exposure (ages one and three) versus never of 3.82 (95% CI 1.36, 10.73) and 3.10 (1.00, 9.57) respectively. Borderline significant trends were also seen between paracetamol dose in the first three years of life and incident eczema and rhinitis, with adjusted ORs for heavy reported use compared to low of 1.59 (0.44, 5.74; p trend=0.06) and 2.31 (0.72, 7.46; p trend=0.07) respectively, but not with incident wheeze (fully adjusted OR=3.64; 1.34, 9.90, p trend=0.11). Cross-sectional analysis at age five resulted in significant positive dose-response effects of lifetime use (use at ages one, three and five) in relation to the prevalence of all outcomes. Effects of gastro-intestinal infection H. pylori infection was found in 17% of the children at age three but not five, 21% at age five but not three years, and 25% at both ages. In the longitudinal analysis, H. pylori infection at age three was significantly associated with a decreased risk of incident eczema between ages three and five years (adjusted OR, 95% CI, 0.31; 0.10, 0.94, p=0.02), but the associations with incident wheeze, rhinitis and sensitization were not significant. In cross-sectional analysis at age three, H. pylori infection was associated with a borderline significant reduced risk of eczema (adjusted OR, 95% CI, 0.49; 0.24, 1.01, p=0.05) and D. pteronyssinus sensitization (adjusted OR, 95% CI, 0.42; 0.17, 1.08, p=0.07), and a significant inverse association between current exposure to H. pylori, and any sensitization at age five (adjusted OR, 95% CI, 0.26; 0.07, 0.92, p=0.02). However, no significant associations were seen for wheeze and rhinitis. The prevalence and intensity of geohelminth infection (hookworm, Ascaris lumbricoides and Trichuris trichiura) were found to be low in this cohort, with only 4% of children infected at age one, 9% at age three and only 0.2% at both ages. The risk of new onset wheeze between ages one and three was lower in those infected at age one (3.6%) than uninfected (7.8%), but infection was insufficiently prevalent to compute estimates of effect. Exposure to geohelminth infections in the first three years of life was not significantly associated with the incidence of reported outcomes or sensitization. However, A. lumbricoides infection was associated with a borderline increased risk of incident eczema between ages three and five (adjusted OR, 95% CI, 2.86; 1.04, 7.86, p=0.07). Children at age three were commonly colonized with enterococci 38% (207/544), lactobacilli 31% (169/544) and bifidobacteria 19% (103/544). However, none of these commensal bacteria were associated significantly with either incidence or prevalence of allergic outcomes. Conclusions: This longitudinal study from a developing country birth cohort provides further support for an association between early life use of paracetamol and increased risk of wheeze and allergic disease, which is unlikely to be explained by aspirin avoidance, reverse causation or confounding by indication. Furthermore, among young children in this cohort, the study found novel evidence to support the hypothesis of a protective effect of H. pylori infection on the risk of allergic disease, but no evidence to support an etiological role for the microflora enterococci, lactobacilli or bifidobacteria. The power of the study to explore the role of geohelminth infection on wheeze and allergic disease was limited by few infected children, and therefore understanding on this particular relation has not been much further advanced.

Rationale: Current asthma guidelines recommend reducing inhaled corticosteroid (ICS) therapy dose by 50% in patients with mild to moderate asthma who have demonstrated three months of good symptom control however there is evidence to suggest that this does not occur. Objectives: We tested whether exhaled nitric oxide (FeNO) measurements or other clinical indices could be utilised to predict a safe reduction of ICS dose, without provoking loss of symptom control or exacerbation within 3 months. We also investigated relationships between airway inflammation and asthma symptoms in the mild to moderate asthma cohort. Methods: 191 patients with stable asthma were recruited from primary care. Patients had their FeNO level measured at baseline and then had their inhaled corticosteroid (ICS) dose reduced by 50%. FeNO measurements were reassessed seven days later. The primary outcomes were whether baseline FeNO or a change in FeNO following ICS dose reduction could predict asthma stability at 3 months. Results: 128/191 patients (67%) completed the ICS dose reduction successfully at three months. 63/191 patients (33%) suffered from either a loss of control or an exacerbation. Baseline FeNO, or change in FeNO (post step-down minus pre step-down) were not statistically significantly different between the two groups. Conclusion: 67% of patients with well-controlled asthma can safely reduce their ICS dose by half without suffering from a loss of control or exacerbation within three months; however neither baseline nor change in FeNO measurements or routine clinical indices can be used to predict which patients can or cannot successfully tolerate a reduction in ICS dose.

Asthma is characterised by airway remodelling and an increase in airway resistance. A greater understanding of the mechanisms involved in airway inflammation and airway hyper-responsiveness (AHR) may highlight therapeutic opportunities for asthma. This study initially aimed to optimise the preparation of precision cut lung slices (PCLS) in mouse and pig to investigate the influence of calcium (Ca2+) homeostasis on airway smooth muscle (ASM) contraction as a prelude to human studies. The PCLS technique was then applied to a murine model of allergic airway disease to explore the inflammatory process and pathogenesis of airway hyper-reactivity in sensitised mice. Initial experiments using murine and porcine airways validated the PCLS model and demonstrated the significance of release and refilling of Ca2+ from internal stores to induce and maintain an airway contraction. Results also highlight interesting species differences in agonist sensitivity, with the porcine system sharing similar pharmacology to human airways. Using a murine model of allergic airway disease, agonist induced contractile responses in peripheral airways were measured in vitro using the PCLS technique. BALB/c mice underwent initial sensitisation by intraperitoneal administration of ovalbumin, receiving a 3 day challenge with aerosolised OVA l% (vlv), for varying periods of up to 3 weeks for acute, mid-chronic and chronic sensitisation protocols. To investigate the influence of the inflammatory environment, naive murine lung slices were incubated with selected inflammatory mediators. OVA sensitisation led to progressive structural remodelling and AHR to methacholine (MCh) challenge. However, this hyperresponsiveness was decreased 48 hours post lung removal. Of the inflammatory mediators selected for lung slice incubation, IL-33 significantly increased AHR to MCh. IL-33 is a proinflammatory cytokine with transcriptional repressor properties, playing a role in initiating the TH2 inflammatory response. In lung slices prepared from IL-33 receptor (ST2) KO mice IL-33 was unable to sensitise the contractile response. These data suggest the inflammatory environment promotes AHR and disassociates this airway sensitivity from structural remodelling. These data suggest a key role for IL-33 in mediating AHR in this murine model. Investigation of the mechanisms involved in airway hyper-reactivity revealed mRNA expression of IL-33 and the IL-33 receptor (ST2) in soluble and membrane bound forms were significantly increased in the mid-chronic and chronic ovalbumin sensitised murine lung tissue. Further quantitative analysis in human lung showed expression of IL-33 in epithelial and ASM cells. The human ST2 receptor (also known as IL-IRL-l) was expressed in mast cells. Together these results suggest IL-33 is a sensor of tissue damage; indirectly inducing AHR through further inflammatory cell activation to target ASM. This study demonstrates IL-33's role as an inflammatory marker of asthma and suggests a novel therapeutic intervention by targeting of the ST2 receptor.

Idiopathic pulmonary fibrosis (IPF) is a fibrotic lung disease with no effective treatment. Myofibroblasts contribute to the pathology of IPF by secreting large amounts of extracellular matrix proteins such as alpha smooth muscle actin (α-SMA) and Collagen I (Col 1). Myofibroblasts have reduced Prostaglandin E2 (PGE2), a key anti-fibrotic mediator, due to diminished cyclooxygenase-2 (COX-2) expression. Primary fibroblasts isolated from lungs of IPF patients (F-IPF) expressed significantly less COX-2 in response to IL-1β and increased α-SMA and Col I compared with fibroblasts isolated from lungs of non-fibrotic patients (F-NL). COX-2 was gradually lost in F-NL treated with transforming growth factor-β (TGF-β1), a pro-fibrotic cytokine, whereas PGE2, and cAMP elevating agents increased IL-1β-induced COX-2 expression in F-IPF. Ras, a small G protein, has been shown to have a role in several fibrotic conditions. Farnesylthiosalicylic acid (FTS), a Ras inhibitor, increased IL-1β-induced COX-2 and prevented TGF-β1-induced reduction of COX-2. Previous studies suggest that COX-2 is epigenetically repressed. LBH589, a HDAC inhibitor, prevented TGF-β1-induced repressed COX-2 whereas BIX01294, a DNA lysine methyltransferase inhibitor, and RG108, a G9a histone methyltransferase inhibitor, both increased IL-1β-induced COX-2 in F-IPF. In conclusion, the gradual loss of PGE2/COX-2 anti-fibrotic mechanism during myofibroblast differentiation may contribute to the pathophysiology of pulmonary fibrosis and agents that increase cAMP levels, inhibit Ras or inhibit epigenetic repression of COX-2, may compensate for the lack of endogenous PGE2.