E. Björnsson

Exhaled nitric oxide and its relationship to airway responsiveness and atopy in asthma

Abstract Exhaled nitric oxide (NO) has attracted increasing interest as a non-invasive marker of airway inflammation. The purpose of this study was to determine whether exhaled nitric oxide in subjects with asthma varied according to their atopic status and to examine its correlation with airway hyperresponsiveness and lung function measurements. Forty patients with asthma and 13 controls participated in the study. Nitric oxide was measured on three occasions with intervals of at least 3 days, using a chemiluminescence method. Airway responsiveness was assessed with methacholine challenge and lung function measurements were made. All subjects recorded peak expiratory flow and kept a symptom diary during a 17-day period. There was no significant difference in lung function measurements, peak expiratory flow or symptom score between the two asthma groups. Atopic patients with asthma had a significantly higher mean amount of exhaled NO than non-atopic subjects with asthma (162 ± 68 vs. 113 ± 55 nl min −1 ; P = 0·03) and the control group (88 ± 52 nl min −1 ; P = 0·004). No significant difference was found in the amount of exhaled NO between non-atopic patients with asthma and the controls. In atopic subjects with asthma the mean exhaled NO was significantly correlated to the dose-response slope for methacholine ( r = −0·52; P = 0·02), while no such correlation was found in the non-atopic group. In conclusion; in this study, atopic subjects with asthma had higher levels of exhaled NO than non-atopic subjects. Atopic status should be taken into account when measuring levels of exhaled NO in subjects with asthma.

Different airway responsiveness profiles in atopic asthma, nonatopic asthma, and Sjögren's syndrome

Background: Different mechanisms may underlie bronchial hyperresponsiveness (BHR) in different diseases. The aim of this study was to investigate the bronchial responsiveness profile produced by three different challenge tests, methacholine, a direct simulus, and two indirect stimuli, adenosine 5′‐monophosphate (AMP) and cold air, in subjects with asthma and patients with Sjögrens syndrome.

Venom allergy in adult Swedes: A population study.

Hymenoptera allergies are a cause of considerable morbidity. However, deaths due to insect sting constitute a health hazard that can be minimized by effective therapy. We report the results of a study of 1815 men and women, aged 20–44 years and resident in three areas of Sweden. The prevalence of sensitization to the venom allergens of honeybees and wasps was assessed by RAST. Atopy and allergic diseases were considered possible risk factors for symptom development. Of the 1815 subjects, 1399 were randomly chosen from the general population. Of the random sample, 9.3% had specific bee or wasp IgE, 1.5% reported systemic reactions to bee or wasp stings, and 0.6% had both. Sensitization to bee or wasp correlated positively with atopy (odds ratio (OR) 2.0, confidence interval (CI) 1.4–2.8, P<0.0001), male sex (OR 1.8, CI 1.3–2.5, P<0.001), and age (OR 2.0, CI 1.4–2.8, P<0.01), and negatively to living in the northernmost of the three centers (OR 0.4, CI 0.3–0.7, P<0.001). Atopy was not found to be a risk factor for systemic reactions. We conclude that the prevalence of Hymenoptera allergy in Sweden is rather low when compared with other countries. Subjects with atopy seem to have an increased risk of becoming sensitized but do not develop systemic reactions more frequently than nonatopic subjects.

Eosinophil peroxidase : a new serum marker of atopy and bronchial hyper-responsiveness

Do markers of eosinophil activation differ in their ability to detect subjects with atopy or bronchial hyper-responsiveness (BHR)? Comparisons of serum levels of eosinophil peroxidase (S-EPO), of eosinophil cationic protein (S-ECP) and the blood eosinophil count (B-Eos) have been made between 154 subjects aged 20-44 years, participating in the European Community Respiratory Health Survey in Uppsala, Sweden. Subjects with atopy had significantly higher levels of S-EPO and S-ECP than those without atopy (P <0 center dot 001). Subjects with BHR had significantly higher levels of S-EPO (P <0 center dot 001) and B-Eos (P <0 center dot 01) than subjects without BHR. Persons reporting asthma-related symptoms had significantly higher levels of S-EPO and B-Eos than subjects without such symptoms (P <0 center dot 001 and P <0 center dot 01, respectively). Asthma symptom score correlated significantly to S-EPO (r = 0 center dot 26, P <0 center dot 01), S-ECP (r = 0 center dot 20, P <0 center dot 05) and B-Eos (r = 0 center dot 18, P <0 center dot 05). Finally, S-EPO was significantly more sensitive than S-ECP for detecting subjects with BHR (P <0 center dot 05) and significantly more sensitive than B-Eos for detecting both subjects with BHR and subjects with a combination of atopy and BHR (P <0 center dot 05). It is concluded that S-EPO is a promising marker with a higher sensitivity for BHR than S-ECP or B-Eos. Further studies are needed to define the value of S-EPO when following disease activity.

Inflammatory markers in acute exacerbations of obstructive pulmonary disease: predictive value in relation to smoking history.

The aim of this study was to investigate the relationship between the effect of emergency treatment and inflammatory markers in patients with acute exacerbations of obstructive pulmonary disease, especially with respect to smoking history. We investigated 50 unselected patients with acute bronchial obstruction. Blood, urine and sputum samples were taken and analysed for eosinophil and neutrophil markers. The patients were observed for at least 2 h and recordings of forced expiratory volume in 1 s (FEV1) were taken. They were re-examined after 1 and 4 weeks. The absolute levels of inflammatory markers did not differ significantly between non- or short-term smokers (< or = 5 pack-years) and long-term smokers (> 5 pack-years) with the exception of myeloperoxidase in serum (S-MPO), which was higher in long-term smokers. The patients with higher levels of eosinophil markers before emergency treatment experienced a greater improvement in lung function. In non- or short-term smokers this relationship was found in blood and urine, whereas in long-term smokers it was seen in sputum. No correlation was found between neutrophil markers and changes in lung function. We conclude that patients with obstructive pulmonary disease with acute exacerbations and high levels of eosinophil markers respond well to treatment.

Seasonal variation in serum eosinophilic cationic protein (S-ECP) in a general population sample

The aim of this investigation was to study the seasonal variation in the serum levels of eosinophil cationic protein (S-ECP). The study population comprised a general population sample of 379 individuals (range: 20-45 years) who were investigated with blood sample for the measurement of S-ECP, skin prick test and methacholine challenge. The examination took place between May and October 1991. Of the 379 subjects investigated, 137 (36%) were atopic. A significant seasonal variation in S-ECP was found in the group of birch-pollen-positive subjects (P < 0.05), but not in the non-atopic or birch-negative atopic group. The mean level of S-ECP in birch-positive subjects was about twice as high in June as in birch atopic subjects examined during other months. It is concluded that seasonal variation in birch-pollen-positive subjects must be taken into account when using S-ECP clinically or in epidemiological research.

Setting up an ambulatory sleep research unit

Obstructive sleep apnoea syndrome (OSAS) has been described as a public health problem comparable to smoking in its effects upon society. Being a treatable illness (1), the importance of early and accurate diagnosis of OSAS should be emphasized. Although many OSAS patients are seen by doctors on a regular basis (2), the syndrome is still largely unrecognized and undiagnosed (3). This may in part be caused by lack of training in sleep medicine or a general lack of awareness and also to the fact that the symptoms are nonspecific and have other possible causes. Patients are predominantly referred to a sleep clinic because they complain of excessive daytime sleepiness (EDS) or their partner complains about the noise of their snoring or expresses concern about witnessed apnoeas. Snoring is very common in the general population; 35–45% of men and 15%–28% of women report habitual snoring (4). EDS, like snoring, is common and a poor discriminator of the patient with OSAS. Of the general population without OSAS, 30%– 50% report moderate to severe sleepiness (5). Consequently, clinical assessment alone is not sufficient to make the diagnosis of OSAS. Even sleep experts have been reported to be wrong in 50% of cases when making the diagnosis on history and examination alone (6). Therefore, an objective measurement is always needed. Full polysomnography (PSG), while traditionally regarded as the gold standard for the diagnosis of OSAS, is time-consuming and expensive. Limited sleep studies quantify obstructive respiratory events without recording sleep. They are cheaper, less labourand time-intensive, and technically less challenging (7) and, generally, there is good correlation between the Apnea-hypopnea index (AHI) obtained from these devices and PSG. These systems are usually portable and can be used at home, which is appreciated by the patients (8). Still, the proper way of diagnosing sleep apnoea remains laborious. Many common clinical problems can be easily diagnosed at a single clinical visit or by a simple laboratory test. Conversely, waiting lists at sleep clinics seem a global problem. Flemons et al. assessed the waiting list for sleep studies in five different countries and found a variation between 2–60 months (9). The likelihood of increased funds to sleep clinics seems negligible as many hospitals in northern Europe are suffering cutbacks and downsizing. Therefore, the main issue in the management of sleep apnoea now is how to shorten the time to diagnosis and treatment (10). We describe the set-up of a simple sleep research unit at a private practice facility and the experience during a 4-year period.

Airway hyperresponsiveness, peak flow variability and inflammatory markers in non-asthmatic subjects with respiratory infections

Objective:  The aim of this study was to characterise non‐asthmatic subjects with asthma‐like symptoms during a common cold, particularly in relation to airway hyperresponsiveness (AHR).