Combined effects of aerobiological pollutants, chemical pollutants and meteorological conditions on asthma admissions and A & E attendances in Derbyshire UK, 1993–96.

BACKGROUND: The effect of outdoor aeroallergen exposure in asthma may be enhanced by air pollutants, including ozone, nitrogen dioxide and particulates, and by certain weather conditions. It is not yet established whether these interactions are important in determining asthma morbidity at the population level. OBJECTIVE: We have investigated the joint effects of aeroallergens, rainfall, thunderstorms and outdoor air pollutants on daily asthma admissions and Accident and Emergency (A & E) attendance using routinely collected data between 1993 and 1996 from Derby in central England. METHODS: Daily counts during the aeroallergen season of grass and birch pollen, basidiospores, Didymella, Alternaria and Cladosporium, maximum 1 hour ozone and nitrogen dioxide and daily average black smoke measurements, all made in the vicinity of the city centre, were categorized in tertiles. Rainfall was classified as dry, light ( 2 mm). The modifying effect of outdoor pollutant levels, and rainfall or the occurrence of a thunderstorm, upon the effects of individual aeroallergens on asthma admissions and A & E attendance were investigated by fitting appropriate interactions in log linear autoregression models with adjustment for potential confounders. RESULTS: We found a significant interaction between the effects of grass pollen and weather conditions upon A & E attendance, such that the increase with grass pollen count was most marked on days of light rainfall (adjusted rate ratio for >/= 50 vs < 10 grains/m3 at lag 2 days = 2.1, 95% CI 1.4, 3.3). Asthma admissions increased with Cladosporium count. We found no statistically significant interactions between effects of any individual aeroallergen and outdoor air pollutant upon either measure of asthma morbidity. CONCLUSIONS: Rainfall and thunderstorms are important effect modifiers in the relation between grass pollen and measures of acute asthma morbidity. Interactions between ambient levels of aeroallergens and chemical pollutants in the Derby area do not play a major role in determining asthma admissions and A & E attendance.     

Thunderstorm‐related asthma: what happens and why

The fifth report issued by the Intergovernmental Panel on Climate Change forecasts that greenhouse gases will increase the global temperature as well as the frequency of extreme weather phenomena. An increasing body of evidence shows the occurrence of severe asthma epidemics during thunderstorms in the pollen season, in various geographical zones. The main hypotheses explaining association between thunderstorms and asthma claim that thunderstorms can concentrate pollen grains at ground level which may then release allergenic particles of respirable size in the atmosphere after their rupture by osmotic shock. During the first 20–30 min of a thunderstorm, patients suffering from pollen allergies may inhale a high concentration of the allergenic material that is dispersed into the atmosphere, which in turn can induce asthmatic reactions, often severe. Subjects without asthma symptoms, but affected by seasonal rhinitis can also experience an asthma attack. All subjects affected by pollen allergy should be alerted to the danger of being outdoors during a thunderstorm in the pollen season, as such events may be an important cause of severe exacerbations. In light of these observations, it is useful to predict thunderstorms and thus minimize thunderstorm‐related events.     

Identification of patterns of factors preceding severe or life‐threatening asthma exacerbations in a nationwide study

Background

Reducing near‐fatal asthma exacerbations is a critical problem in asthma management.

Objectives

To determine patterns of factors preceding asthma exacerbations in a real‐world setting.

Methods

In a nationwide prospective study of 190 patients who had experienced near‐fatal asthma exacerbation, cluster analysis was performed using asthma symptoms over the 2‐week period before admission.

Results

Three distinct clusters of symptoms were defined employing the self‐reporting of a visual analogue scale. Cluster A (42.1%): rapid worsening within 7.4 hours from moderate attack to admission, young to middle‐aged patients with low Body mass index and tendency to depression who had stopped anti‐asthma medications, smoked, and hypersensitive to environmental triggers and furred pets. Cluster B (40.0%): fairly rapid worsening within 48 hours, mostly middle‐aged and older, relatively good inhaled corticosteroid (ICS) or ICS/long‐acting beta‐agonist (LABA) compliance, and low perception of dyspnea. Cluster C (17.9%): slow worsening over 10 days before admission, high perception of dyspnea, smokers, and chronic daily mild‐moderate symptoms. There were no differences in overuse of short‐acting beta‐agonists, baseline asthma severity, or outcomes after admission for patients in these 3 clusters.

Conclusion

To reduce severe or life‐threatening asthma exacerbation, personalized asthma management plans should be considered for each cluster. Improvement of ICS and ICS/LABA compliance and cessation of smoking are important in cluster A. To compensate for low perception of dyspnea, asthma monitoring of peak expiratory flow rate and/or exhaled nitric oxide would be useful for patients in cluster B. Avoidance of environmental triggers, increase usual therapy, or new anti‐type 2 response‐targeted therapies should be considered for cluster C.     

The sex‐shift in single disease and multimorbid asthma and rhinitis during puberty ‐ a study by MeDALL

Background

Cross‐sectional studies suggested that allergy prevalence in childhood is higher in boys compared to girls, but it remains unclear whether this inequality changes after puberty. We examined the sex‐specific prevalence of asthma and rhinitis as single and as multimorbid diseases before and after puberty onset in longitudinal cohort data.

Methods

In six European population‐based birth cohorts of MeDALL, we assessed the outcomes: current rhinitis, current asthma, current allergic multimorbidity (ie, concurrent asthma and rhinitis), puberty status and allergic sensitization by specific serum antibodies (immunoglobulin E) against aero‐allergens. With generalized estimating equations, we analysed the effects of sex, age, puberty (yes/no) and possible confounders on the prevalence of asthma and rhinitis, and allergic multimorbidity in each cohort separately and performed individual participant data meta‐analysis.

Findings

We included data from 19 013 participants from birth to age 14‐20 years. Current rhinitis only affected girls less often than boys before and after puberty onset: adjusted odds ratio for females vs males 0.79 (95%‐confidence interval 0.73‐0.86) and 0.86 (0.79‐0.94), respectively (sex‐puberty interaction P = .089). Similarly, for current asthma only, females were less often affected than boys both before and after puberty onset: 0.71, 0.63‐0.81 and 0.81, 0.64‐1.02, respectively (sex‐puberty interaction P = .327). The prevalence of allergic multimorbidity showed the strongest sex effect before puberty onset (female‐male‐OR 0.55, 0.46‐0.64) and a considerable shift towards a sex‐balanced prevalence after puberty onset (0.89, 0.74‐1.04); sex‐puberty interaction: P < .001.

Interpretation

The male predominance in prevalence before puberty and the “sex‐shift” towards females after puberty onset were strongest in multimorbid patients who had asthma and rhinitis concurrently.     

Short course of grass allergen peptides immunotherapy over 3 weeks reduces seasonal symptoms in allergic rhinoconjunctivitis with/without asthma: A randomized,multicenter, double‐blind,placebo‐controlled trial

Background

Immunotherapy with peptide hydrolysates from Lolium perenne (LPP) is an alternative treatment for seasonal allergic rhinitis with or without asthma. The aim of this study was to assess the clinical efficacy and safety of a cumulative dose of 170 μg LPP administered subcutaneously over 3 weeks.

Methods

In a randomized, double‐blind, placebo‐controlled trial, 554 adults with grass pollen rhinoconjunctivitis were randomized (1:2 ratio) to receive 8 subcutaneous injections of placebo or 170 μg LPP administered in increasing doses in 4 visits over 3 weeks. The primary outcome was the combined symptom and medication score (CSMS) measured over the peak pollen season. Reactivity to conjunctival provocation test (CPT) and quality of life (QOL) was assessed as secondary endpoints.

Results

The mean reduction in CSMS in the LPP vs placebo group was ?15.5% (P = .041) during the peak period and ?17.9% (P = .029) over the entire pollen season. LPP‐treated group had a reduced reactivity to CPT (P < .001) and, during the pollen season, a lower rhinoconjunctivitis QOL global score (P = .005) compared with placebo group. Mostly mild and WAO grade 1 early systemic reaction (ESR) were observed ≤30 minutes in 10.5% of LPP‐treated patients, whereas 3 patients with a medical history of asthma (<1%) experienced a serious ESR that resolved with rescue medication.

Conclusion

Lolium perenne pollen peptides administered over 3 weeks before the grass pollen season significantly reduced seasonal symptoms and was generally safe and well‐tolerated.

     

Development of a pediatric asthma predictive index for hospitalization

Background

Variation in emergency department (ED) management for asthma exacerbation leads to disparities in care. Current asthma severity scores are insufficient to be used for hospitalization decisions.

Prevalence of pollen‐induced allergic rhinitis with high pollen exposure in grasslands of northern China

Background

The aim of this study was to investigate the prevalence of epidemiologic and physician‐diagnosed pollen‐induced AR (PiAR) in the grasslands of northern China and to study the impact of the intensity and time of pollen exposure on PiAR prevalence.

Methods

A multistage, clustered and proportionately stratified random sampling with a field interviewer‐administered survey study was performed together with skin prick tests (SPT) and measurements of the daily pollen count.

Results

A total of 6043 subjects completed the study, with a proportion of 32.4% epidemiologic AR and 18.5% PiAR. The prevalence was higher in males than females (19.6% vs 17.4%, P = .024), but no difference between the two major residential and ethnic groups (Han and Mongolian) was observed. Subjects from urban areas showed higher prevalence of PiAR than rural areas (23.1% vs 14.0%, P < .001). Most PiAR patients were sensitized to two or more pollens (79.4%) with artemisia, chenopodium, and humulus scandens being the most common pollen types, which were similarly found as the top three sensitizing pollen allergens by SPT. There were significant regional differences in the prevalence of epidemiologic AR (from 18.6% to 52.9%) and PiAR (from 10.5% to 31.4%) among the six areas investigated. PiAR symptoms were positively associated with pollen counts, temperature, and precipitation (P < .05), but negatively with wind speed and pressure P < .05).

Conclusion

Pollen‐induced AR (PiAR) prevalence in the investigated region is extremely high due to high seasonal pollen exposure, which was influenced by local environmental and climate conditions.     

Risk factors for asthma exacerbation in patients presenting to an emergency unit of a national referral hospital in Kampala,Uganda

Background

Asthma exacerbations are caused by a variety of risk factors. Reducing exposure to these risk factors improves the control of asthma and reduces medication needs. Knowledge of the particular risk factors is essential in formulating controlling and treatment protocols. This study set out to determine the risk factors for asthma exacerbations in patients presenting to the emergency unit of Mulago Hospital.

Methods

An unmatched case-control study involving 43 cases and 43 controls was conducted from November 2011 through February 2012. Asthma patients with exacerbations presenting to Mulago hospital''s emergency unit were chosen as cases. The controls were asthma patients recruited from the hospital''s outpatient department who had not had an exacerbation in the past 7 days. The study variables were age, sex, level of education, adherence to treatment, exercise, upper respiratory tract infections, household pets, smoking, strong emotions, exposure to in house wood or charcoal burning, weather, use of corticosteroids, beta-blockers and non-steroidal anti-inflammatory drugs. Univariate and multivariate statistical analysis was done using SPSS version 16 to identify independent risk factors for exacerbations.

Results

Lack of corticosteroid use (OR =22.109; 95% Confidence interval 6.952 to 70.315; p<0.001) and presence of upper respiratory tract infections (OR 4.516; CI 1.258–16.213; p=0.018) were significantly associated with exacerbations.

Conclusion

Lack of corticosteroid use and upper respiratory tract infections are associated with exacerbations in asthma patients presenting to the Emergency unit of Mulago Hospital     

Lack of effect of Timothy grass pollen sublingual immunotherapy tablet on birch pollen–induced allergic rhinoconjunctivitis in an environmental exposure unit

Background

Timothy grass pollen allergen extract tablets (Grastek) are standardized sublingual immunotherapy tablets (SLIT-T) approved for the treatment of grass pollen–induced allergic rhinitis (AR) and conjunctivitis. Many grass allergic patients are also cosensitized to birch pollen. Whether Timothy grass SLIT-T can confer symptomatic benefits for birch pollen–induced AR symptoms is unknown.

Dupilumab is effective in type 2-high asthma patients receiving high-dose inhaled corticosteroids at baseline

Background

Dupilumab blocks the shared receptor component for interleukin (IL)-4/IL-13, key drivers of type 2 inflammation. In phase 2b (NCT01854047) and phase 3 LIBERTY ASTHMA QUEST (NCT02414854), add-on dupilumab 200/300 mg every 2 weeks (q2w) reduced severe exacerbations, improved prebronchodilator (pre-BD) forced expiratory volume in 1 second (FEV₁) and quality of life measures, and it was generally well tolerated in patients with uncontrolled, persistent (phase 2b), or moderate-to-severe (phase 3) asthma.

Methods

In patients on high-dose inhaled corticosteroids (ICS) with type 2-high asthma (subgroups including baseline blood eosinophils ≥150/300 cells/µL and/or fractional exhaled nitric oxide [FeNO] ≥25 ppb), annualized severe exacerbation rates over the treatment period, changes from baseline in pre-BD FEV₁ and asthma control (5-item asthma control questionnaire [ACQ-5]) were analyzed.

Results

In high-dose ICS type 2-high subgroups, dupilumab 200/300 mg q2w vs placebo in the phase 2b (24 weeks) and phase 3 (52 weeks) studies significantly reduced severe exacerbations by 55%-69%/57%-60% (all P<.05) and 53%-69%/48%-66% (all P < .001), respectively, except in patients with ≥ 300 eosinophils/µL in phase 2b study (24%/50% (P = .52/0.15). Across subgroups, pre-BD FEV₁ improved by 0.18-0.22 L/0.19-0.24 L (all P < .05) and 0.23-0.36 L/0.15-0.25 L (all P < .01) and ACQ-5 scores were reduced by 0.46-0.55/0.47-0.85 (all P < .05) and 0.38-0.50/0.24-0.30 (all P < .05), respectively, except dupilumab 200 mg q2w in phase 2b in patients with FeNO ≥ 25 ppb (0.41; P = .09). Dupilumab was also effective in patients taking medium-dose ICS.

Conclusion

Dupilumab significantly reduced severe exacerbations and improved lung function and asthma control in patients with type 2-high asthma on high-dose ICS at baseline.

     

Late summer and fall (March-May) pollen allergy and respiratory disease in Northern New South Wales, Australia.

BACKGROUND: Many people in the subtropical Northern Rivers area of New South Wales, Australia, blame the pollen of Tibouchina tree, which flowers at the same time as ragweed, Bahia grass and Bermuda grass, for hayfever and asthma exacerbations during fall between March and May. OBJECTIVES: To determine whether Tibouchina pollen is allergenic. To determine whether airborne ragweed pollen is present in this region for sufficient length of time and concentration to cause fall respiratory symptoms, and to determine if Bahia grass and Bermuda grass are associated with fall respiratory symptoms. METHODS: Pollen and Alternaria spores were monitored using a Burkard 7-day spore trap. Two hundred and six volunteers in the Northern Rivers area filled in questionnaires before skin prick tests (SPT) were performed with a panel of skin testing extracts. RESULTS: One hundred fifty-three (74.3%) subjects were atopic and reacted to one or more aeroallergens. Seventy were SPT positive to ragweed, OR 3.36 (CI 1.03 to 12.15) and 11 to Tibouchina (OR incalculable). Fifty of the 70 ragweed-positive subjects had fall hayfever or exacerbations of hayfever and/or asthma, OR 23.4 (CI 8.90 to 64.00). Eleven subjects were SPT positive to Tibouchina extract. There was a statistical association between Bermuda grass and hayfever, but not asthma OR 13.44 (CI 1.85 to 27.04). CONCLUSIONS: Ragweed pollen was present for a sufficient length of time and concentration to sensitize and provoke fall hayfever and asthma exacerbations. Tibouchina pollen is an aeroallergen causing mild-to-moderate allergic symptoms in a few people. There is an association between Bahia grass and asthma in children, and between Bermuda grass and allergic rhinitis in adults.     

Impact of intranasal corticosteroids on asthma outcomes in allergic rhinitis: a meta‐analysis

Given the relationship between allergic rhinitis (AR) and asthma, it can be hypothesized that reducing inflammation in the upper airway with intranasal corticosteroid (INCS) medications may improve asthma outcomes. The goal of this study was to perform a systematic review with meta‐analysis of the efficacy of INCS medications on asthma outcomes in patients with AR and asthma. Asthma‐specific outcomes from randomized, controlled studies evaluating INCS medications in patients with AR were evaluated, including studies that compared INCS sprays to placebo, INCS sprays plus orally inhaled corticosteroids to orally inhaled corticosteroids alone, and nasally inhaled corticosteroids to placebo. Sufficient data for meta‐analysis were retrieved for 18 trials with a total of 2162 patients. Asthma outcomes included pulmonary function, bronchial reactivity, asthma symptom scores, asthma‐specific quality of life, and rescue medication use. The subgroup of studies comparing INCS spray to placebo had significant improvements in FEV1 (SMD = 0.31; 95% CI, 0.04–0.58), bronchial challenge (SMD = 0.46; 95% CI, 0.12–0.79), asthma symptom scores (SMD = −0.42; 95% CI, −0.53 to −0.30), and rescue medication use (SMD = −0.29; 95% CI, −0.58 to −0.01). Nasal inhalation of corticosteroids significantly improved morning and evening peak expiratory flow. There were no significant changes in asthma outcomes with the addition of INCS spray to orally inhaled corticosteroids. Thus, the results of this meta‐analysis demonstrated that intranasal corticosteroid medications significantly improve some asthma‐specific outcome measures in patients suffering from both AR and asthma. This effect was most pronounced with INCS sprays when patients were not on orally inhaled corticosteroids, or when corticosteroid medications were inhaled through the nose into the lungs. Overall, intranasal corticosteroid medications improve some asthma‐specific outcome measures in patients with both AR and asthma. Further research is needed to clarify the role of INCS sprays as asthma‐specific therapy, as well as the role of the nasal inhalation technique as a monotherapy in patients suffering from both asthma and AR.

     

Seasonal allergic symptoms and their relation to pollen exposure in south-east France

In order to evaluate the relationship between pollen exposure and prevalence of allergic respiratory symptoms, we performed a cross-sectional epidemiological study in 2 areas with contrasted exposure to cypress and grass pollens. The study population consisted of 5427 subjects 18 to 65-years-old representative of the general population. All answered an abridged version of the 1978 ATS questionnaire and a sample had a skin test evaluation including grass and cypress pollens. Prevalence of hay fever symptoms was equal to 31.5% and 14.1%, respectively, in exposed and less exposed community (P < 0.001). Prevalence of hay fever symptoms together with a positive skin test to pollen was also significantly higher in the exposed (13.6%) vs less exposed community (5.5%, P<0.001). In contrast, overall prevalence of asthma was equal to 4.5% and 3.4%, respectively. Prevalence of asthma with positive skin tests was also not statistically significant, equal to 2.5% and 1.9%, respectively. Thus, high exposure to pollen is a risk factor for developing hay fever but not asthma.     

Epidemic asthma and the role of the fungal mold Alternaria alternata

BACKGROUND: After July 29, 2002, an epidemic of asthma admissions was associated with a thunderstorm in the United Kingdom. OBJECTIVE: We sought to study the cause of epidemics of asthma associated with thunderstorms. METHODS: We performed a case-control study of 26 patients presenting to Cambridge University Hospital with asthma after the thunderstorm. Control subjects were 31 patients with summer seasonal asthma. Subjects underwent skin tests and specific IgE serology to inhaled aeroallergens. Meteorologic and aerobiologic data correlated with asthma admissions were analyzed. RESULTS: Twenty-three of 26 cases had IgE sensitization to Alternaria species. Eleven of 31 control subjects gave a history of asthma exacerbation during thunderstorms. Ten of these 11 control subjects were sensitive to Alternaria species on skin testing, but Alternaria species sensitivity was only identified in 4 of the 20 remaining control subjects who did not report thunderstorm-related asthma symptoms. The odds ratio of having epidemic thunderstorm-related asthma if sensitive to Alternaria species was 9.31 (95% CI, 2.305-37.601; P = .0008) and 63.966 (95% CI, 3.577-1143.9; P < .0001) if sensitive to Alternaria species, Cladosporium species, or both. Poisson regression analysis showed that counts of broken Alternaria species and Didymella and Cladosporium species were significantly correlated with each other and with asthma admissions. The thunderstorm was associated with increased levels of Alternaria, Cladosporium, and Didymella species. CONCLUSIONS: Alternaria alternata sensitivity is a compelling predictor of epidemic asthma in patients with seasonal asthma and grass pollen allergy and is likely to be the important factor in thunderstorm-related asthma. CLINICAL IMPLICATIONS: Alternaria species sensitization in asthmatic subjects with grass pollen sensitivity predicts susceptibility to thunderstorm-associated asthma.     

Airway inflammation in thunderstorm asthma.

BACKGROUND: Epidemics of acute asthma associated with thunderstorms occur intermittently worldwide, though airway inflammation during these acute episodes has not been characterized. The aim of this study was to characterize airway inflammation in thunderstorm asthma. METHODS: Cases were recruited after presentation to the emergency room with acute asthma immediately following a thunderstorm (n = 6). They were compared to two control groups: a group of atopic asthmatics that had presented with acute asthma to the emergency room prior to the thunderstorm (n = 12), and a second group of corticosteroid naive asthmatics who presented to the emergency room in the prior 12 months (n = 6). Subjects had spirometry, sputum induction and allergy skin tests acutely and at review 4 weeks later. RESULTS: Thunderstorm (TS) cases were more likely to have a history of hay fever and grass pollen allergy, and less likely to be on inhaled corticosteroids (ICS) prior to presentation. Cases and control groups had a similar degree of moderate to severe acute airway obstruction (P = 1.0). TS cases had elevated sputum eosinophils (14.8% of total cell count) compared to controls (1%, 2.6%, P < 0.01). TS cases had higher sputum eosinophil cationic protein (ECP; 11,686 ng/mL) compared to controls (1,883, 3,300, P = 0.02) acutely. TS cases had more cells positive for IL-5 (30%) compared to controls (1, 1.5%, P = 0.02). When adjusted for ICS use, TS cases had a risk ratio for elevated sputum eosinophils of 2.4 (1.23-4.69). CONCLUSION: Thunderstorm asthma is characterized by airway inflammation with IL-5-mediated sputum eosinophilia and eosinophil degranulation. These results are consistent with allergen exposure as the cause of the exacerbation, and are consistent with the thunderstorm-induced grass pollen deluge as the cause of epidemic asthma after thunderstorms.     

ILC2 frequency and activity are inhibited by glucocorticoid treatment via STAT pathway in patients with asthma

Background

Group 2 innate lymphoid cells (ILC2s) were closely associated with asthma. However, there were no perspective studies about the effects of glucocorticoid on ILC2s in asthma patients. Our objective was to perform a perspective study and evaluate the ILC2 activity after glucocorticoid therapy in asthma patients.

Methods

The asthma and asthma with allergic rhinitis patients were treated with glucocorticoid for 3 months. The circulating ILC2 levels were evaluated. The effects of glucocorticoid on ILC2s and possible signalling pathways were investigated in vitro.

Results

The patients were well‐controlled, and the high ILC2 levels were significantly decreased at 1 and 3 months after treatment. Peripheral blood monocytes from allergic patients produced dramatic IL‐5, IL‐13 and IL‐9 in response to IL‐25, IL‐33 plus IL‐2, and glucocorticoid significantly decreased their levels. Moreover, ILC2s were identified to be the predominant source of IL‐5, IL‐13 and IL‐9, and glucocorticoid treatment was able to reverse their high levels. STAT3, STAT5, STAT6, JAK3 and MEK signalling pathways were proved to be involved in regulating ILC2 activity under the glucocorticoid treatment.

Conclusion

The data suggested that glucocorticoid administration could be effective in treating asthma by regulating ILC2s via MEK/JAK‐STAT signalling pathways. This provides a new understanding of glucocorticoid application in regard to allergic diseases.     

Major grass pollen allergen Lol p 1 binds to diesel exhaust particles: implications for asthma and air pollution

Background Grass pollen allergens are known to be present in the atmosphere in a range of particle sizes from whole pollen grains (approx. 20 to 55 μim in diameter) to smaller size fractions < 2.5 μ (fine particles, PM2.5). These latter particles are within the respirable range and include allergen-containing starch granules released from within the grains into the atmosphere when grass pollen ruptures in rainfall and are associated with epidemics of thunderstorm asthma during the grass pollen season. The question arises whether grass pollen allergens can interact with other sources of fine particles, particularly those present during episodes of air pollution. Objective We propose the hypothesis that free grass pollen allergen molecules, derived from dead or burst grains and dispersed in microdroplets of water in aerosols, can bind to fine particles in polluted air. Methods We used diesel exhaust carbon particles (DECP) derived from the exhaust of a stationary diesel engine, natural highly purified Lol p 1, immunogold labelling with specific monoclonal antibodies and a high voltage transmission electron -microscopic imaging technique Results DECP are visualized as small carbon spheres, each 30–60 nm in diameter, forming fractal aggregates about 1–2μ in diameter. Here we test our hypothesis and show by in vitro experiments that the major grass pollen allergen, Lol p I. binds to one defined class of fine particles, DECP. Conclusion DECP are in the respirable size range, can bind to the major grass pollen allergen Lol p I under in vitro conditions and represent a possible mechanism by which allergens can become concentrated in polluted air and thus trigger attacks of asthma.     

Thunderstorm-related asthma – the epidemic of 24/25 June 1994

Background A large epidemic of asthma occurred following a thunderstorm in southern and central England on 24/25 June 1994. A collaborative study group was formed. Objectives To describe the epidemic and the meteorological, aerobiological and other environmental characteristics associated with it. Methods Collation of data from the Meteorological Office, the Pollen Research Unit, the Department of the Environtnent's Automatic Urban Network, from health surveillance by the Department of Health and the National Poisons Unit, from clinical experience in general practice and hospitals, and from an immunological study of some of the affected cases from north east London. Results The thunderstorm was a Mesoscale Convective System, an unusual and large form of storm with several centres and severe wind gusts. It occurred shortly after the peak grass pollen concentration in the London area. A sudden and extensive epidemic occurred within about an hour affecting possibly several thousand patients. Emergency services were stretched but the epidemic did not last long. Cases had high serum levels of IgE antibody to mixed grass pollen. Conclusion This study supports the view that patients with specific IgE to grass pollen are at risk of thunderstorm-related asthma. The details of the causal pathway from storm to asthma attack are not clear. Case-control and time series studies are being carried out.     

Epidemiological analysis and follow‐up of human rhinovirus infection in children with asthma exacerbation

To determine the prevalence of human rhinovirus (HRV) infection in children with acute asthma exacerbations, investigation of HRV viral load and severity of asthma exacerbations is also required. Nasopharyngeal aspirates and swabs were collected and assessed for respiratory viruses. HRV‐positive samples were sequenced to identify types and determine viral load. Outpatients with asthma exacerbations underwent follow‐up evaluations, their swabs were collected and clinical outcomes were recorded at their next clinic visit 4 weeks later. One hundred forty‐three inpatients and 131 outpatients, including 88 patients with asthma exacerbations and 43 controls with stable asthma were recruited. HRV‐A was mainly detected in September and February (45.5% and 33.3%, respectively), while HRV‐C was mainly detected in November and April (70.0% and 55.6%, respectively). HRV‐C was the primary type and was primarily found in inpatients with severe asthma exacerbations. HRV‐A viral load in the group of inpatients with severe exacerbations was higher than in the mild and moderate groups (P < 0.001 and P = 0.022). The HRV‐A viral load of both inpatients and outpatients was higher than that of HRV‐C (P < 0.001 and P = 0.036). The main genotypes were HRV‐C53 and HRV‐A20 among inpatients, and this genotype caused more severe clinical manifestations. HRV persisted for no more than 4 weeks, and their symptoms or signs of disease were well‐controlled well. HRV‐C was most frequently detected in asthma exacerbations. HRV‐A with high viral load led to severe asthma exacerbations.