Bronchial responsiveness to inhaled methacholine was measured four to six days before fibreoptic bronchoscopy in 22 asthmatic patients (10 smokers) and 20 control subjects (12 smokers).The asthmatic patients had a baseline FEV, greater than 60% predicted and a PD20FEV, (provocative dose of methacholine causing a 20% fall in FEV,) of 0 006-3-7 mg. The 20 control subjects had normal pulmonary function and a PD20FEV, above the maximum cumulative dose of methacholine of 6-4 mg. Bronchoalveolar lavage of a middle lobe segment (lingula in four subjects) was performed with three sequential 60 ml aliquots of sterile saline. Cellular metabolic activity was stimulated with latex in aliquots of resuspended cells, and measured by means of luminol enhanced chemiluminescence to assess neutrophil activity and lucigenin enhanced chemiluminescence to assess macrophage activity. Mean absolute total cell counts were similar in the asthmatic and control groups but there were differences in differential cell counts, with a significant increase in eosinophil (p < 0 05) and lymphocyte (p < 0 05) counts in asthma. PD20FEV, was negatively correlated with percentage neutrophil counts (p < 0005). Luminol enhanced chemiluminescence/1000 neutrophils was increased about twofold in asthmatic subjects (p < 0 001), but was not correlated with PD20FEV1. Lucigenin enhanced chemiluminescence/1000 macrophages was increased nearly fourfold in asthmatic patients (p < 0-001) and showed a negative correlation with PD20FEV, (p < 0-01). The macrophage count was increased twofold in current smokers in both groups, but other cell numbers were not altered significantly. Smoking did not affect cellular metabolic activity in either group. This study supports the idea that an inflammatory process is present in the airways of those with asthma, and suggests a relation between bronchial responsiveness and both neutrophil numbers and macrophage activity.

(1975). Thorax, 30, 2-8. An analysis of skin prick test reactions in 656 asthmatic patients. Of 656 asthmatic patients referred specifically for allergy assessments, 544 (84%) gave positive immediate skin prick tests to at least one of 22 common allergens used routinely.Comparison of these skin test positive patients with the 102 (16%) who were skin test negative showed a number of significdnt differences. The majority of the skin test positive patients (52%) were less than 10 years old at the time of onset of the asthma, whereas, of the skin test negative patients, 56% were aged over 30 years at the time of onset. Seventy per cent reported rhinitis compared with 48% of the skin test negative patients, and 29% reported infantile eczema compared with 9%. Symptoms attributed to house dust, pollens, and animals were noted two to three times more frequently by the skin test positive patients, while corticosteroid drugs had been used more commonly by the skin test negative patients (45% compared with 35%).No significant differences were observed with the other factors studied, namely, history of urticaria or angio-oedema, family history of 'allergic' disease, and awareness of sensitivity to foods, aspirin or penicillin.Prick test reactions in the skin test positive patients were most commonly seen to house dust or the acarine mite, Dermatophagoides farinae (82%), followed by pollens (66%), animal danders (38%), foods (16%), Aspergillus fumigatus (16%), and other moulds (21%). There was a highly significant association of positive history with positive prick test for all allergens studied.Although the association between immediate wealing skin reactions and asthma has been recognized for many years (Coca and Cooke, 1923), the specificity of these tests, their relation to etiology, and their clinical significance has been in dispute. Rackemann (1947) suggested that the presence of positive skin reactions on routine prick testing with common inhalant and food allergens should place the asthmatic into the extrinsic (allergic) category where usually the onset of symptoms is early in life and the prognosis more favourable than in the intrinsic (nonallergic) category (Rackemann and Edwards, 1952;Rackemann, 1958).Raised serum IgE levels have been found in Present addresses: 1Department of Chest Diseases, United Oxford Hospitals

No abstract

Output from jet nebulisers is calibrated traditionally by weighing them before and after nebulisation, but the assumption that the weight difference is a close measure of aerosol generation could be invalidated by the concomitant process of evaporation. A method has been developed for measuring aerosol output directly by using a solute (fluoride) tracer and aerosol impaction, and this has been compared with the traditional weight loss method for two Wright, six Turbo, and four Micro-Cirrus jet nebulisers and two Microinhaler ultrasonic nebulisers. The weight loss method overestimated true aerosol output for all jet nebulisers. The mean aerosol content, expressed as a percentage of the total weight loss, varied from as little as 15% for the Wright jet nebulisers to 54% (range 45-61%) for the Turbo and Micro-Cirrus jet nebulisers under the operating conditions used. In contrast, there was no discrepancy between weight loss and aerosol output for the ultrasonic nebulisers. These findings, along with evidence of both concentrating and cooling effects from jet nebulisation, con Glass fibre filter onto which NaF laden aerosols impact jet nebuliser reservoir containing 1 % w/v NaF mm GF/A filters, through which air was drawn at 25 1/min. A higher flow rate and larger filter were used for the ultrasonic nebulisers because the filter could not be positioned as close to the source of nebulisation. After aerosol collection GF/A filters were removed and stored for later analysis. For flow rates of 15 1/min and above and for aerosols having a mass median diameter of 0 3 gm or more the collection efficiency of GF/A filters exceeds 99 9%.18 When a second filter was placed in series we detected no aerosol breakthrough.Analysis of aerosol output Total ionic strength adjustment buffer (TISAB; BDH Chemicals Ltd) was prepared as a 50% solution in distilled water, and 20 ml were added to each Whatman filter within 25 ml plastic Universal bottles. The bottles were then sealed and fluoride was allowed to desorb overnight. The recovery of fluoride from filters was complete (> 98%) and no fluoride was detected in unused filters. Fluoride analysis followed well established protocols.'9 Fluoride standards were prepared by microlitre injections of 5 0, 10-0, and 15-0 pl of 1 00% sodium fluoride into 20 ml aliquots of 50% TISAB buffer, resulting in 5-95E-5M, 1 19E'M, and 1 *78E'M fluoride solutions. Both standard and test solutions were equilibrated to 25°C in a water bath. Fluoride concentrations within the buffered solutions were then measured electrochemically with a fluoride specific ion electrode (Corning Ltd, Halstead) on a Corning 255 pH/ ion meter with a calomel reference electrode. This electrochemical system had a log-linear relation between concentration and activity (mV) from 10-'M to 10'M F. All solutions were continually agitated during analysis with an electromagnetic stirrer. An internal two point calibration was established with the 5 and 15 pl fluoride standards and its accuracy was checked with the 10 p1 standard....

No abstract