Investigating lung responses with functional hyperpolarized xenon-129 MRI in an ex vivo rat model of asthma

PURPOSE

Asthma is a disease of increasing worldwide importance that calls for new investigative methods. Ex vivo lung tissue is being increasingly used to study functional respiratory parameters independent of confounding systemic considerations but also to reduce animal numbers and associated research costs. In this work, a straightforward laboratory method is advanced to probe dynamic changes in gas inhalation patterns by using an ex vivo small animal ovalbumin (OVA) model of human asthma.

METHODS

Hyperpolarized (hp) (129) Xe was actively inhaled by the excised lungs exposed to a constant pressure differential that mimicked negative pleural cavity pressure. The method enabled hp (129) Xe MRI of airway responsiveness to intravenous methacholine (MCh) and airway challenge reversal through salbutamol.

RESULTS

Significant differences were demonstrated between control and OVA challenged animals on global lung hp (129) Xe gas inhalation with P < 0.05 at MCh dosages above 460 μg. Spatial mapping of the regional hp gas distribution revealed an approximately three-fold increase in heterogeneity for the asthma model organs.

CONCLUSION

The experimental results from this proof of concept work suggest that the ex vivo hp noble gas imaging arrangement and the applied image analysis methodology may be useful as an adjunct to current diagnostic techniques. Magn Reson Med 76:1224-1235, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Step 4: stick or twist? A review of asthma therapy

Many people with asthma do not achieve disease control, despite bronchodilators and inhaled corticosteroid therapy. People with uncontrolled asthma are at higher risk of an asthma attack and death, with mortality rates estimated at 1000 deaths/year in England and Wales. The recent National Review of Asthma Deaths (NRAD) report, ‘Why asthma still kills’, recommended that patients at step 4 or 5 of the British Thoracic Society/Scottish Intercollegiate Guidelines Network (BTS/SIGN) guidance must be referred to a specialist asthma service. This article reviews the 2014 evidence base for therapy of asthma patients at BTS/SIGN step 4 of the treatment cascade, in response to key findings of the NRAD report and lack of preferred treatment option at this step.

Assessment of a rapid liquid-based cytology method for measuring sputum cell counts

Differential sputum cell counting is not widely available despite proven clinical utility in the management of asthma. We compared eosinophil counts obtained using liquid-based cytology (LBC), a routine histopathological processing method, and the current standard method. Eosinophil counts obtained using LBC were a strong predictor of sputum eosinophilia (≥3%) determined by the standard method suggesting LBC could be used in the management of asthma.

Hyperpolarized 83Kr magnetic resonance imaging of alveolar degradation in a rat model of emphysema

Hyperpolarized ⁸³Kr surface quadrupolar relaxation (SQUARE) generates MRI contrast that was previously shown to correlate with surface-to-volume ratios in porous model surface systems. The underlying physics of SQUARE contrast is conceptually different from any other current MRI methodology as the method uses the nuclear electric properties of the spin I = 9/2 isotope ⁸³Kr. To explore the usage of this non-radioactive isotope for pulmonary pathophysiology, MRI SQUARE contrast was acquired in excised rat lungs obtained from an elastase-induced model of emphysema. A significant ⁸³Kr T₁ relaxation time increase in the SQUARE contrast was found in the elastase-treated lungs compared with the baseline data from control lungs. The SQUARE contrast suggests a reduction in pulmonary surface-to-volume ratio in the emphysema model that was validated by histology. The finding supports usage of ⁸³Kr SQUARE as a new biomarker for surface-to-volume ratio changes in emphysema.

The utility of exhaled nitric oxide in patients with suspected asthma

The value of FENO measurements in patients with symptoms suggestive of asthma is unclear. We performed an observational study to assess the ability of FENO to diagnose asthma and to predict response to inhaled corticosteroids (ICS). Our findings suggest FENO is not useful for asthma diagnosis but is accurate at predicting ICS response.

Using venous blood gas analysis in the assessment of COPD exacerbations: a prospective cohort study

Introduction

Identifying acute hypercapnic respiratory failure is crucial in the initial management of acute exacerbations of COPD. Guidelines recommend obtaining arterial blood samples but these are more difficult to obtain than venous. We assessed whether blood gas values derived from venous blood could replace arterial at initial assessment.

Methods

Patients requiring hospital treatment for an exacerbation of COPD had paired arterial and venous samples taken. Bland–Altman analyses were performed to assess agreement between arterial and venous pH, CO₂ and . The relationship between SpO₂ and SaO₂ was assessed. The number of attempts and pain scores for each sample were measured.

Results

234 patients were studied. There was good agreement between arterial and venous measures of pH and (mean difference 0.03 and −0.04, limits of agreement −0.05 to 0.11 and −2.90 to 2.82, respectively), and between SaO₂ and SpO₂ (in patients with an SpO₂ of >80%). Arterial sampling required more attempts and was more painful than venous (mean pain score 4 (IQR 2–5) and 1 (IQR 0–2), respectively, p<0.001).

Conclusions

Arterial sampling is more difficult and more painful than venous sampling. There is good agreement between pH and values derived from venous and arterial blood, and between pulse oximetry and arterial blood gas oxygen saturations. These agreements could allow the initial assessment of COPD exacerbations to be based on venous blood gas analysis and pulse oximetry, simplifying the care pathway and improving the patient experience.

Clinical and inflammatory characteristics of the European U-BIOPRED adult severe asthma cohort

U-BIOPRED is a European Union consortium of 20 academic institutions, 11 pharmaceutical companies and six patient organisations with the objective of improving the understanding of asthma disease mechanisms using a systems biology approach.This cross-sectional assessment of adults with severe asthma, mild/moderate asthma and healthy controls from 11 European countries consisted of analyses of patient-reported outcomes, lung function, blood and airway inflammatory measurements.Patients with severe asthma (nonsmokers, n=311; smokers/ex-smokers, n=110) had more symptoms and exacerbations compared to patients with mild/moderate disease (n=88) (2.5 exacerbations versus 0.4 in the preceding 12 months; p<0.001), with worse quality of life, and higher levels of anxiety and depression. They also had a higher incidence of nasal polyps and gastro-oesophageal reflux with lower lung function. Sputum eosinophil count was higher in severe asthma compared to mild/moderate asthma (median count 2.99% versus 1.05%; p=0.004) despite treatment with higher doses of inhaled and/or oral corticosteroids.Consistent with other severe asthma cohorts, U-BIOPRED is characterised by poor symptom control, increased comorbidity and airway inflammation, despite high levels of treatment. It is well suited to identify asthma phenotypes using the array of "omic" datasets that are at the core of this systems medicine approach.

Defining and managing risk in asthma

Asthma attacks are a major global source of morbidity and cost. The incidence and impact of asthma attacks have not improved despite widespread adoption of effective universal treatment guidelines. Consequently, there is increasing interest in managing asthma based on specific assessments of both current symptoms and future risk. In this review, we consider 'risk' in asthma, and how it might be assessed from the patient's history and objective measurements. We also discuss the potential for encouraging shared decision-making and improving medical consensus through explicit communication of risk and highlight the potential opportunities and challenges in risk assessment to improve asthma management through individualised treatment strategies.

Pulmonary MRI contrast using Surface Quadrupolar Relaxation (SQUARE) of hyperpolarized (83)Kr

Hyperpolarized (83)Kr has previously been demonstrated to enable MRI contrast that is sensitive to the chemical composition of the surface in a porous model system. Methodological advances have lead to a substantial increase in the (83)Kr hyperpolarization and the resulting signal intensity. Using the improved methodology for spin exchange optical pumping of isotopically enriched (83)Kr, internal anatomical details of ex vivo rodent lung were resolved with hyperpolarized (83)Kr MRI after krypton inhalation. Different (83)Kr relaxation times were found between the main bronchi and the parenchymal regions in ex vivo rat lungs. The T1 weighted hyperpolarized (83)Kr MRI provided a first demonstration of surface quadrupolar relaxation (SQUARE) pulmonary MRI contrast.

Cryogenics free production of hyperpolarized 129Xe and 83Kr for biomedical MRI applications

As an alternative to cryogenic gas handling, hyperpolarized (hp) gas mixtures were extracted directly from the spin exchange optical pumping (SEOP) process through expansion followed by compression to ambient pressure for biomedical MRI applications. The omission of cryogenic gas separation generally requires the usage of high xenon or krypton concentrations at low SEOP gas pressures to generate hp (129)Xe or hp (83)Kr with sufficient MR signal intensity for imaging applications. Two different extraction schemes for the hp gasses were explored with focus on the preservation of the nuclear spin polarization. It was found that an extraction scheme based on an inflatable, pressure controlled balloon is sufficient for hp (129)Xe handling, while (83)Kr can efficiently be extracted through a single cycle piston pump. The extraction methods were tested for ex vivo MRI applications with excised rat lungs. Precise mixing of the hp gases with oxygen, which may be of interest for potential in vivo applications, was accomplished during the extraction process using a piston pump. The (83)Kr bulk gas phase T1 relaxation in the mixtures containing more than approximately 1% O2 was found to be slower than that of (129)Xe in corresponding mixtures. The experimental setup also facilitated (129)Xe T1 relaxation measurements as a function of O2 concentration within excised lungs.

Validating excised rodent lungs for functional hyperpolarized xenon-129 MRI

Ex vivo rodent lung models are explored for physiological measurements of respiratory function with hyperpolarized (hp) (129)Xe MRI. It is shown that excised lung models allow for simplification of the technical challenges involved and provide valuable physiological insights that are not feasible using in vivo MRI protocols. A custom designed breathing apparatus enables MR images of gas distribution on increasing ventilation volumes of actively inhaled hp (129)Xe. Straightforward hp (129)Xe MRI protocols provide residual lung volume (RV) data and permit for spatially resolved tracking of small hp (129)Xe probe volumes during the inhalation cycle. Hp (129)Xe MRI of lung function in the excised organ demonstrates the persistence of post mortem airway responsiveness to intravenous methacholine challenges. The presented methodology enables physiology of lung function in health and disease without additional regulatory approval requirements and reduces the technical and logistical challenges with hp gas MRI experiments. The post mortem lung functional data can augment histological measurements and should be of interest for drug development studies.

What drives the 'August effect'? A observational study of the effect of junior doctor changeover on out of hours work

Objective

To investigate whether measurements of junior doctor on-call workload and performance can clarify the mechanisms underlying the increase in morbidity and mortality seen after junior doctor changeover: the ‘August effect’.

Design

Quantitative retrospective observational study of routinely collected data on junior doctor workload.

Setting

Two large teaching hospitals in England.

Participants

Task level data from a wireless out of hours system (n = 29,885 requests) used by medical staff, nurses, and allied health professionals.

Main outcome measures

Number and type of tasks requested by nurses, time to completion of tasks by junior doctors.

Results

There was no overall change in the number of tasks requested by nurses out of hours around the August changeover (median requests per hour 15 before and 14 after, p = 0.46). However, the number of tasks classified as urgent was greater (p = 0.016) equating to five more urgent tasks per day. After changeover, doctors took less time to complete tasks overall due to a reduction in time taken for routine tasks (median 74 vs. 66 min; p = 3.9 × 10⁻⁹).

Conclusion

This study suggests that the ‘August effect’ is not due to new junior doctors completing tasks more slowly or having a greater workload. Further studies are required to investigate the causes of the increased number of urgent tasks seen, but likely factors are errors, omissions, and poor prioritization. Thus, improved training and quality control has the potential to address this increased duration of unresolved patient risk. The study also highlights the potential of newer technologies to facilitate quantitative study of clinical activity.

Off-line breath acetone analysis in critical illness

Analysis of breath acetone could be useful in the Intensive Care Unit (ICU) setting to monitor evidence of starvation and metabolic stress. The aims of this study were to examine the relationship between acetone concentrations in breath and blood in critical illness, to explore any changes in breath acetone concentration over time and correlate these with clinical features. Consecutive patients, ventilated on controlled modes in a mixed ICU, with stress hyperglycaemia requiring insulin therapy and/or new pulmonary infiltrates on chest radiograph were recruited. Once daily, triplicate end-tidal breath samples were collected and analysed off-line by selected ion flow tube mass spectrometry (SIFT-MS). Thirty-two patients were recruited (20 males), median age 61.5 years (range 26-85 years). The median breath acetone concentration of all samples was 853 ppb (range 162-11 375 ppb) collected over a median of 3 days (range 1-8). There was a trend towards a reduction in breath acetone concentration over time. Relationships were seen between breath acetone and arterial acetone (rs = 0.64, p < 0.0001) and arterial beta-hydroxybutyrate (rs = 0.52, p < 0.0001) concentrations. Changes in breath acetone concentration over time corresponded to changes in arterial acetone concentration. Some patients remained ketotic despite insulin therapy and normal arterial glucose concentrations. This is the first study to look at breath acetone concentration in ICU patients for up to 8 days. Breath acetone concentration may be used as a surrogate for arterial acetone concentration, which may in future have a role in the modulation of insulin and feeding in critical illness.

Breathing exercises for asthma: a randomised controlled trial

BACKGROUND

The effect of breathing modification techniques on asthma symptoms and objective disease control is uncertain.

METHODS

A prospective, parallel group, single-blind, randomised controlled trial comparing breathing training with asthma education (to control for non-specific effects of clinician attention) was performed. Subjects with asthma with impaired health status managed in primary care were randomised to receive three sessions of either physiotherapist-supervised breathing training (n = 94) or asthma nurse-delivered asthma education (n = 89). The main outcome was Asthma Quality of Life Questionnaire (AQLQ) score, with secondary outcomes including spirometry, bronchial hyper-responsiveness, exhaled nitric oxide, induced sputum eosinophil count and Asthma Control Questionnaire (ACQ), Hospital Anxiety and Depression (HAD) and hyperventilation (Nijmegen) questionnaire scores.

RESULTS

One month after the intervention there were similar improvements in AQLQ scores from baseline in both groups but at 6 months there was a significant between-group difference favouring breathing training (0.38 units, 95% CI 0.08 to 0.68). At the 6-month assessment there were significant between-group differences favouring breathing training in HAD anxiety (1.1, 95% CI 0.2 to 1.9), HAD depression (0.8, 95% CI 0.1 to 1.4) and Nijmegen (3.2, 95% CI 1.0 to 5.4) scores, with trends to improved ACQ (0.2, 95% CI 0.0 to 0.4). No significant between-group differences were seen at 1 month. Breathing training was not associated with significant changes in airways physiology, inflammation or hyper-responsiveness.

CONCLUSION

Breathing training resulted in improvements in asthma-specific health status and other patient-centred measures but not in asthma pathophysiology. Such exercises may help patients whose quality of life is impaired by asthma, but they are unlikely to reduce the need for anti-inflammatory medication.

Association between neutrophilic airway inflammation and airflow limitation in adults with asthma

BACKGROUND

There is debate about the mechanisms of persistent airflow limitation in patients with asthma. Chronic inflammation is assumed to be important, although there is limited and contradictory information about the relationship between airway inflammation and postbronchodilator FEV1.

METHODS

We have assessed the cross-sectional relationship between prebronchodilator and postbronchodilator FEV1 and measures of airway inflammation after allowing for the effects of potential confounding factors. Multivariate analysis was performed on data collected from 1,197 consecutive patients with asthma seen at the respiratory outpatient clinic at Glenfield Hospital between 1997 and 2004. Relationships between induced sputum total neutrophil and differential eosinophil cell counts, and prebronchodilator and postbronchodilator lung function were examined.

RESULTS

Sputum total neutrophil but not differential eosinophil count was associated with lower postbronchodilator FEV1. Both differential eosinophil and total neutrophil count were associated with lower prebronchodilator FEV1. These effects were independent after adjustment for age, smoking, ethnicity, asthma duration, and inhaled corticosteroid use. A 10-fold increase in neutrophil count was associated with a 92 mL reduction (95% confidence interval, 29 to 158; p = 0.007) in postbronchodilator FEV1.

CONCLUSIONS

In this large heterogeneous population of adults with asthma, we have shown that prebronchodilator FEV1 is associated with neutrophilic and eosinophilic airway inflammation, whereas sputum total neutrophil counts alone are associated with postbronchodilator FEV1. This supports the hypothesis that neutrophilic airway inflammation has a role in the progression of persistent airflow limitation in asthma and raises the possibility that this progression and the development of COPD share a common mechanism.

The use of exhaled nitric oxide to guide asthma management: a randomized controlled trial

RATIONALE

Current asthma guidelines recommend adjusting antiinflammatory treatment on the basis of the results of lung function tests and symptom assessment, neither of which are closely associated with airway inflammation.

OBJECTIVES

We tested the hypothesis that titrating corticosteroid dose using the concentration of exhaled nitric oxide in exhaled breath (Fe(NO)) results in fewer asthma exacerbations and more efficient use of corticosteroids, when compared with traditional management.

METHODS

One hundred eighteen participants with a primary care diagnosis of asthma were randomized to a single-blind trial of corticosteroid therapy based on either Fe(NO) measurements (n = 58) or British Thoracic Society guidelines (n = 60). Participants were assessed monthly for 4 months and then every 2 months for a further 8 months. The primary outcome was the number of severe asthma exacerbations. Analyses were by intention to treat.

MEASUREMENTS AND MAIN RESULTS

The estimated mean (SD) exacerbation frequency was 0.33 per patient per year (0.69) in the Fe(NO) group and 0.42 (0.79) in the control group (mean difference, -21%; 95% confidence interval [CI], -57 to 43%; p = 0.43). Overall the Fe(NO) group used 11% more inhaled corticosteroid (95% CI, -17 to 42%; p = 0.40), although the final daily dose of inhaled corticosteroid was lower in the Fe(NO) group (557 vs. 895 microg; mean difference, 338 microg; 95% CI, -640 to -37; p = 0.028).

CONCLUSIONS

An asthma treatment strategy based on the measurement of exhaled nitric oxide did not result in a large reduction in asthma exacerbations or in the total amount of inhaled corticosteroid therapy used over 12 mo, when compared with current asthma guidelines. Clinical trial registered with www.controlled-trials.com (ISRCTN08067387).

Pathological features and inhaled corticosteroid response of eosinophilic and non-eosinophilic asthma

BACKGROUND

Non-eosinophilic asthma is a potentially important clinicopathological phenotype since there is evidence that it responds poorly to inhaled corticosteroid therapy. However, little is known about the underlying airway immunopathology and there are no data from placebo-controlled studies examining the effect of inhaled corticosteroids.

METHODS

Airway immunopathology was investigated using induced sputum, bronchial biopsies, bronchial wash and bronchoalveolar lavage in 12 patients with symptomatic eosinophilic asthma, 11 patients with non-eosinophilic asthma and 10 healthy controls. The patients with non-eosinophilic asthma and 6 different patients with eosinophilic asthma entered a randomised, double-blind, placebo-controlled crossover study in which the effects of inhaled mometasone 400 microg once daily for 8 weeks on airway responsiveness and asthma quality of life were investigated.

RESULTS

Patients with non-eosinophilic asthma had absence of eosinophils in the mucosa (median 4.4 cells/mm(2) vs 23 cells/mm(2) in eosinophilic asthma and 0 cells/mm(2) in normal controls; p = 0.03) and normal subepithelial layer thickness (5.8 microm vs 10.3 microm in eosinophilic asthma and 5.1 microm in controls, p = 0.002). Non-eosinophilic and eosinophilic asthma groups had increased mast cell numbers in the airway smooth muscle compared with normal controls (9 vs 8 vs 0 cells/mm(2), p = 0.016). Compared with placebo, 8 weeks of treatment with inhaled mometasone led to less improvement in methacholine PC(20) (0.5 vs 5.5 doubling concentrations, 95% CI of difference 1.1 to 9.1; p = 0.018) and asthma quality of life (0.2 vs 1.0 points, 95% CI of difference 0.27 to 1.43; p = 0.008).

CONCLUSIONS

Non-eosinophilic asthma represents a pathologically distinct disease phenotype which is characterised by the absence of airway eosinophilia, normal subepithelial layer thickness and a poor short-term response to treatment with inhaled corticosteroids.

Phase 1 trial of the antiangiogenic peptide ATN-161 (Ac-PHSCN-NH(2)), a beta integrin antagonist, in patients with solid tumours

To evaluate the toxicity, pharmacological and biological properties of ATN-161, a five –amino-acid peptide derived from the synergy region of fibronectin, adult patients with advanced solid tumours were enrolled in eight sequential dose cohorts (0.1–16 mg kg⁻¹), receiving ATN-161 administered as a 10-min infusion thrice weekly. Pharmacokinetic sampling of blood and urine over 7 h was performed on Day 1. Twenty-six patients received from 1 to 14 4-week cycles of treatment. The total number of cycles administered to all patients was 86, without dose-limiting toxicities. At dose levels above 0.5 mg kg⁻¹, mean total clearance and volume of distribution showed dose-independent pharmacokinetics (PKs). At 8.0 and 16.0 mg kg⁻¹, clearance of ATN-161 was reduced, suggesting saturable PKs. Dose escalation was halted at 16 mg kg⁻¹ when drug exposure (area under the curve) exceeded that associated with efficacy in animal models. There were no objective responses. Six patients received more than four cycles of treatment (>112 days). Three patients received 10 or more cycles (⩾280 days). ATN-161 was well tolerated at all dose levels. Approximately, 1/3 of the patients in the study manifested prolonged stable disease. These findings suggest that ATN-161 should be investigated further as an antiangiogenic and antimetastatic cancer agent alone or with chemotherapy.

Evidence of a role of tumor necrosis factor alpha in refractory asthma

BACKGROUND

The development of tumor necrosis factor alpha (TNF-alpha) antagonists has made it feasible to investigate the role of this cytokine in refractory asthma.

METHODS

We measured markers of TNF-alpha activity on peripheral-blood monocytes in 10 patients with refractory asthma, 10 patients with mild-to-moderate asthma, and 10 control subjects. We also investigated the effects of treatment with the soluble TNF-alpha receptor etanercept (25 mg twice weekly) in the patients with refractory asthma in a placebo-controlled, double-blind, crossover pilot study.

RESULTS

As compared with patients with mild-to-moderate asthma and controls, patients with refractory asthma had increased expression of membrane-bound TNF-alpha, TNF-alpha receptor 1, and TNF-alpha-converting enzyme by peripheral-blood monocytes. In the clinical trial, as compared with placebo, 10 weeks of treatment with etanercept was associated with a significant increase in the concentration of methacholine required to provoke a 20 percent decrease in the forced expiratory volume in one second (FEV1) (mean difference in doubling concentration changes between etanercept and placebo, 3.5; 95 percent confidence interval, 0.07 to 7.0; P=0.05), an improvement in the asthma-related quality-of-life score (by 0.85 point; 95 percent confidence interval, 0.16 to 1.54 on a 7-point scale; P=0.02), and a 0.32-liter increase in post-bronchodilator FEV1 (95 percent confidence interval, 0.08 to 0.55; P=0.01).

CONCLUSIONS

Patients with refractory asthma have evidence of up-regulation of the TNF-alpha axis. (ClinicalTrials.gov number, NCT00276029.).

The use of exhaled nitric oxide concentration to identify eosinophilic airway inflammation: an observational study in adults with asthma

BACKGROUND

Assessment of eosinophilic airway inflammation may be helpful in the management of asthma. Nitric oxide (NO) has potential advantages as a tool to monitor airway inflammation although little is known about the relationship between NO and eosinophilic airway inflammation and the factors which influence it.

METHODS

We set out to define the relationship between exhaled NO and the sputum eosinophil count, identify the exhaled NO concentration that best identified a sputum eosinophil count >3% and investigate the impact of several potential confounding factors in 566 consecutive patients with varying severity of asthma. Finally we examined the ability of exhaled NO concentrations measured at differing exhalation flows to identify the presence of a sputum eosinophilia.

RESULTS

We found a significant positive relationship between exhaled NO and sputum eosinophil count (R(2)=0.26, P<0.001) which was best described using a non-linear model. There were no clinically important confounding factors to this model. In non-smokers an exhaled NO concentration of >8.3 p.p.b. at 250 mL/s gave 71% sensitivity and 72% specificity for identifying a sputum eosinophil count of >3%.

CONCLUSIONS

This value of exhaled NO would seem to be the best for identifying significant eosinophilic airway inflammation. It is applicable to a wide range of non-smoking patients with asthma; exhalation flow does not alter the ability of exhaled NO concentration to detect a sputum eosinophilia.

Asthma exacerbations: prevention is better than cure

Poorly controlled asthma is currently treated by adding or removing asthma medication in a stepwise fashion to try and improve symptoms and maintain lung function. It is becoming apparent that asthma exacerbations are independent of asthma control and severity, and that the simple method of using rescue courses of corticosteroids to treat an asthma exacerbation can be bettered by aiming to prevent its occurrence. New tools that can predict and prevent exacerbations are now becoming available. This article discusses these tools and takes a more detailed look at new treatment regimes being used.

2-Aryl indole NK1 receptor antagonists: optimisation of indole substitution

The synthesis and biological evaluation of a series of 2-aryl indoles with high affinity for the human neurokinin-1 (hNK1) receptor are reported, concentrating on optimisation of the indole substitution.

Two-chain high molecular weight kininogen induces endothelial cell apoptosis and inhibits angiogenesis: partial activity within domain 5

We previously reported that the binding of two-chain high molecular weight kininogen (HKa) to endothelial cells may occur through interactions with endothelial urokinase receptors. Since the binding of urokinase to urokinase receptors activates signaling responses and may stimulate mitogenesis, we assessed the effect of HKa binding on endothelial cell proliferation. Unexpectedly, HKa inhibited proliferation in response to several growth factors, with 50% inhibition caused by approximately 10 nM HKa. This activity was Zn(2+) dependent and not shared by either single-chain high molecular weight kininogen (HK) or low molecular weight kininogen. HKa selectively inhibited the proliferation of human umbilical vein and dermal microvascular endothelial cells, but did not affect that of umbilical vein or human aortic smooth muscle cells, trophoblasts, fibroblasts, or carcinoma cells. Inhibition of endothelial proliferation by HKa was associated with endothelial cell apoptosis and unaffected by antibodies that block the binding of HK or HKa to any of their known endothelial receptors. Recombinant HK domain 5 displayed activity similar to that of HKa. In vivo, HKa inhibited neovascularization of subcutaneously implanted Matrigel plugs, as well as rat corneal angiogenesis. These results demonstrate that HKa is a novel inhibitor of angiogenesis, whose activity is dependent on the unique conformation of the two-chain molecule.

Randomised, placebo-controlled study of vigabatrin as first-line treatment of infantile spasms

PURPOSE

Vigabatrin (VGB) has been shown to be an effective drug in the treatment of infantile spasms (West syndrome) in predominantly retrospective and open but also in prospective studies. This prospective, randomised, and placebo-controlled trial of VGB in infantile spasms was considered to be justified and feasible to confirm or refute these previous findings.

METHODS

Forty children with newly diagnosed infantile spasms received either VGB or placebo for 5 days in a double blind, placebo-controlled, parallel-group study, after which all the infants continuing in the study were treated openly with VGB for a minimum of 24 weeks.

RESULTS

Compared with baseline, at the end of the double-blind phase, the patients treated with VGB had a 78% (95% confidence interval, 55-89%) reduction in spasms compared with 26% (-56-65%) in the group treated with placebo (p = 0.020). Seven VGB-treated patients and two placebo-treated patients were spasm free on the final day of the double-blind period (p = 0.063). At the end of the study, 15 children (38% of the original 40 patients or 42% of the 36 patients who entered the open phase) were spasm free with VGB monotherapy. No patient withdrew from the study because of an adverse event.

CONCLUSIONS

This unique randomized, placebo-controlled study is the first to demonstrate the efficacy of a specific drug in the treatment of West syndrome and supports the results of previously published open and prospective trials. It further confirms that VGB could be considered as the drug of first choice in treating infantile spasms.

Analysis of method-comparison data

Method-comparison studies, in which new 'candidate' techniques are compared with an established 'gold standard', feature commonly in optometric research. Investigators often analyse their findings using least squares regression, Pearson's product-moment correlation coefficient and the paired t-test. We describe more appropriate methods which include: the 'limits of agreement', the intraclass correlation coefficient, and Deming's method for estimating a straight line fit. Comparisons between methods are made with the aid of a computer simulation. Computer program listings are provided to assist in implementing the analyses.

Retinopathy of prematurity: a prospective study. Review at six months

A cohort of infants of birthweight < or = 1700 g studied prospectively for retinopathy of prematurity (ROP) has been reviewed at 6 months corrected age and the findings related to the neonatal data. The overall incidence of strabismus was 6.4% (30/468), rising from 3.1% (7/229) without ROP to 29.2% (7/24) with stage 3. Strabismus and fusional ability were significantly related to presence and severity of ROP, and abnormal neonatal cranial ultrasound findings. Binocular visual acuity was measured in 340 infants between 20 and 40 weeks corrected age. Eight were subnormal, all due to neurological problems. For the remainder, despite falling within the normal range, there was a significant trend (p < 0.001) for lower acuities with increasing ROP severity. Cycloplegic refraction on 387 infants revealed, with increasing ROP severity: 1, a significant trend towards myopia; 2, increased magnitude of astigmatism; 3, alteration of the astigmatic axis; 4, increased incidence of anisometropia. For the first three categories there was an insignificant trend between no ROP and stage 2, reaching significance only between stage 2 and 3. The predominant axis of astigmatism in infants without ROP was between 60 degrees and 120 degrees, but with ROP there was a significant trend away from this direction.

Natural history of retinopathy of prematurity: a prospective study

The natural history of retinopathy of prematurity (ROP) has been studied prospectively in 572 infants < or = 1,700 g birthweight using a protocol designed specifically to investigate the subtle features of this condition. Acute ROP developed in 50.9%. All ROP stages 1 and 2 underwent complete resolution and of the 27 (4.7%) infants with stage 3/4 disease, cicatricial sequelae developed in six. Incidence and severity increased with decreasing birthweight and gestational age. Onset was not confined to the temporal retina but exhibited a predilection to start first in the nasal retina of the most immature neonate. The vertical retinal regions were relatively spared. Retinal arteriolar tortuosity developed around three months postnatally and was related to ROP severity but not its presence. The age at onset and rate of progression of retinopathy were largely determined by the stage of development but were also modified by systemic and local factors. The relevance of these findings to ROP screening is discussed.

Light and retinopathy of prematurity: does retinal location offer a clue?

Nursery illumination has been implicated in the pathogenesis of retinopathy of prematurity (ROP), although the results of recent studies are conflicting. The data base for this article is a prospective ROP study on 607 infants of birth weight less than or equal to 1700 g including 35 larger siblings from multiple births when 1 infant fulfilled the birth weight criteria. Retinopathy commences preferentially in the nasal retina of the most immature neonate and is less likely to develop, or its onset is delayed, in the superior and inferior regions. These findings cannot be fully accounted for by regional vascular and neuroanatomical variations. Radiometric and physiological evidence suggests that the very immature neonate, most at risk of developing severe ROP, receives the greatest retinal irradiance. Furthermore, ROP commences in the areas of the retina receiving the highest light dose, and its onset is either retarded or inhibited in the darker retinal regions. Further studies are required to determine whether early exposure to light is a factor in the development of ROP. If a causal relationship is proven, here at least is one modality that can easily and immediately be controlled.

Time-related variation in normal automated static perimetry

The effects of phase of eye test and order of eye examined were investigated in 38 normal subjects using a customized 30-point central threshold program of the Humphrey Field Analyzer 640. This program, designed to be completed within 5 minutes, was successively repeated three times for each eye (i.e., three phases for each eye) at two visits separated by an interval of approximately 2 weeks. Both global and pointwise group mean sensitivity decreased in a time-related manner, deterioration being greater for the second eye at each visit, for both 200 ms and 100 ms stimulus durations.

Patent ductus arteriosus and cerebral circulation in preterm infants

The diagnosis of patent ductus arteriosus (PDA) was determined by Doppler examinations of the descending aorta and/or main trunk of the pulmonary artery in a cohort of 120 preterm infants. 55 per cent of the infants had Doppler echocardiographic evidence of ductal patency on the first day of life and this proportion fell to 30 per cent on the second day and 21 per cent on the third day. The incidence remained constant for the rest of the first week. Infants with PDA were significantly more likely to develop periventricular leukomalacia (PVL) than infants without PDA, but the incidence of periventricular haemorrhage was not increased. The cerebral haemodynamic effects of ductal patency were evaluated. Infants with PVL were found to have a significantly higher incidence of retrograde flow in the anterior cerebral artery during diastole, but the study was unable to demonstrate any significant difference in cerebral blood flow velocity between the infants with and without PDA.

Topical use of indomethacin on the day of cataract surgery

The use of topical indomethacin in the prevention of surgically induced miosis has been documented. However, in these previous prospective trials this prostaglandin synthetase inhibitor was administered the day before surgery. With the frequency of 'day case' cataract surgery increasing, an efficient preoperative mydriatic regimen is important. In this study we considered the use of topical indomethacin as an addition to a regimen already implemented. One hundred and fourteen eyes underwent intercapsular cataract surgery, of which 64 were randomised to receive topical aqueous indomethacin one hour beforehand, and 50 eyes, which did not receive indomethacin formed the comparison group. Topical indomethacin reduced the miosis which occurs during cataract surgery whether performed under local or general anaesthesia. The operating time was shorter for eyes with less surgically induced miosis.

The effect of delayed pushing in the second stage of labor with continuous lumbar epidural analgesia

We studied primigravid women in spontaneous labor at term and given epidural analgesia. Two hundred such women giving birth in 1983 were compared with similar groups who gave birth in 1985 and 1987 after the introduction of 'delayed pushing' into our labor ward protocol. Four hundred controls were obtained in 1983 and 1985 by selecting from the labor ward register the next normal primigravid woman in spontaneous labor without epidural analgesia. The assisted delivery rate was significantly higher in all three epidural groups than in the controls (p less than 0.001). Among epidural labors, there was no significant difference between 1983 and 1987 in the incidence of rotational or non-rotational forceps, or of cesarean section. In each epidural group, women who waited more than 60 min were less likely to experience a normal spontaneous delivery than were those who did not (p less than 0.001 in 1983; p = 0.006 in 1985 p = 0.035 in 1987). We conclude that to delay pushing beyond 60 min confers no benefit regarding mode of delivery.

A multivariate analysis of preoperative risk factors in patients with common bile duct stones. Implications for treatment

A multivariate analysis of 30 preoperative risk factors was undertaken in 248 patients who underwent surgery alone for common bile duct (CBD) stones and in 190 patients who had endoscopic sphincterotomy (ES), 77 of whom subsequently also had surgery. Independently significant risk factors in those undergoing surgery were the serum bilirubin level, the use of preoperative ES, and the presence of medical risk factors; in patients undergoing ES, only the serum bilirubin and albumin, but not medical risk factors, were of independent significance. The major implications of this study are, first, that high-risk patients should be treated by ES without subsequent surgery, and second, that "fit patients should be treated by surgery alone without routine preoperative ES.

Epidemiology of retinopathy of prematurity

The incidence and severity of retinopathy of prematurity (ROP) were studied prospectively in a geographically defined area of the East Midlands. Over 23 months, 505 infants weighing 1700 g or less at birth to mothers resident in this area were studied. Acute ROP developed in 248 (49.1%) and there was a significant association between short gestation and low birthweight and greater severity. Most acute ROP underwent complete resolution; only stage 3/4 disease did not and cicatricial sequelae subsequently developed in 5 infants, 23.8% of this group. No infant was blind because of ROP. Black infants had shorter gestations yet were less likely to have any stage of ROP. Although Asians were not smaller than their caucasian counterparts, severe (stage 3/4) ROP was more likely (14.1% vs 2.7% for caucasians); this difference was largely due to their better survival. Since 505 of the available 547 infants in this geographically defined area were examined, it was possible to calculate the incidence of acute and cicatricial ROP on a community population basis. There are dangers in attempting to deduce the incidence of acute ROP from infrequent eye examinations, and in comparing community and hospital-based reports.

Predicting future treatment of diabetes mellitus from characteristics available at presentation

This study was designed to identify the clinical features of a newly diagnosed diabetic patient that are most useful in deciding treatment. A secondary aim was to formulate a statistical model for predicting subsequent treatment. The following features were considered in 289 patients: age, sex, severity and duration of symptoms, degree and duration of weight loss, glycosuria, ketonuria, blood glucose concentration, body mass index (BMI), and family history of diabetes. Three treatment groups, 6 months after diagnosis, were defined: diet alone, diet with oral hypoglycaemic agent(s), and insulin-treated. Univariate analysis showed that symptom severity, glycosuria, ketonuria, glucose concentration, weight loss, and BMI were significantly different between the three groups. Age and rate of weight loss were significantly different between the insulin-treated and non-insulin-treated groups. Multivariate analysis gave a model to calculate the probability of requiring each of the three treatments given certain characteristics. A second cohort of 174 patients was used to assess the accuracy of the model. The model predicted the actual treatment at 6 months correctly in 72%.

Vision and visual acuity in an elderly population

The data for this paper were collected during a two-year study of the elderly in the market town of Melton Mowbray. The data show that typically, persons aged 75 years and older have poor uncorrected vision (6/36 Snellen acuity), but good corrected acuity, 73.8 per cent gaining 6/12 binocular Snellen acuity or better. Over 88 per cent were able to read N8 typesize or better, under test conditions. Those with low uncorrected vision were the most likely to possess spectacles.

Refraction and refractive errors in an elderly population

The data for this paper were collected during a two-year study of the elderly in the market town of Melton Mowbray. The randomly selected subjects, aged 76 years of age and older, were found to be on average +1.33 D hypermetropic and the average cylinder power was 0.82 D. The mean refractive error was found to be +1.5 D with 0.5 negative cylinder at between 85 and 90 degrees. Of all the subjects, 30 per cent had significant anisometropia.

Amblyopia--factors influencing age of presentation

In the 47 months from September, 1981, 1531 new cases of amblyopia were identified in the ophthalmic clinics of Leicestershire. Amblyopia was due to strabismus in 689 (45%), combined strabismus and anisometropia in 540 (35%), anisometropia alone in 252 (17%), and form deprivation in 50 (3%). The median age at presentation for strabismic amblyopia (3.64 years) was significantly lower than for combined strabismus and anisometropia (4.68 years) and anisometropia (6.27 years). Boys presented later than girls, as did Asians compared with Caucasians. Only 38 (15%) of children with a visual defect without strabismus (anisometropia) were identified before the age of 5 years. The major reason for this late identification is the lack of a reliable single test for preschool vision assessment.

The histopathology and staging of carcinoma of the ampulla of Vater

Review of 26 resected ampullary carcinomas revealed intestinal type adenocarcinoma in all but one and overtly papillary carcinoma in only one case. Co-existing adenoma of the ampulla was present in 11 cases, over half of which were low-grade carcinomas. Flat duct epithelial dysplasia was present in a further eight cases, the adenocarcinoma in only two of these being well differentiated. The estimated 5 year survival rate, overall, was 52% and, with well differentiated adenocarcinoma, 75%. We recommend a new staging system, based on extent of local and lymph node spread: I = invasion confined to wall of common bile duct; II = infiltration of duodenal or retroperitoneal tissues, excluding pancreas; III = infiltration of pancreas; IV = metastasis to nearby lymph nodes. Long-term survival correlates inversely with stage, both by univariate analysis and independently of grade, so that a simple scoring system, based on a combination of both grade and stage, is an excellent predictor of the long-term outcome, defining two groups, with 5 year survival rates of 79% and 0% (P less than 0.001).

Clinical risk factors and periventricular leucomalacia

Two hundred infants of below 1501 g at birth were regularly examined with real time ultrasound using a 7.5 MHz transducer. Abnormalities were categorized as periventricular haemorrhage (PVH) (n = 107) or periventricular leucomalacia (PVL), with or without PVH (n = 52). Of the group with PVL, 25 had the appearances of prolonged flare without cavitation. Prospective assessments of up to 50 potential clinical risk factors were made wherever possible on each infant including stratification of all blood gas and systolic blood pressure data. Multivariate logistic regression analyses confirmed a strong correlation between immaturity and PVH but this was not found in cases of PVL. Independent variables associated with PVL included pneumothorax, maximum bilirubin concentration, surgery, and the proportion of time the infant's PaCO2 remained above 7 kPa. There was a very strong inverse correlation between anaemia and PVL. Systolic blood pressure data were carefully analysed and there was no relation between either hypotension or antepartum haemorrhage and the development of PVL.