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Biomedical subjects

C A Pickering

Publications and source records attributed to C A Pickering.

At least 37 records · Page 2Linked to original sources
PubMed1996

Domestic allergens in public places. II: Dog (Can f1) and cockroach (Bla g 2) allergens in dust and mite, cat, dog and cockroach allergens in the air in public buildings.

BACKGROUND: Sensitization and exposure to indoor allergens are the major risk factors for asthma. It is possible that significant exposure to domestic allergens occurs outside the home. OBJECTIVES: To investigate the levels of Can f 1 and Bla g 2 in the dust from carpeted floors and upholstered seats in public buildings and public transport and the airborne concentrations of Der p 1, Fel d 1, Can f 1 and Bla g 2 in schools and offices. METHODS: Can f 1 and Bla g 2 were measured in the dust collected by vacuuming a 1 m2 area of carpet, as well as upholstered seats in five schools, six hotels, four cinemas, six pubs, three buses and two trains. Dust was also collected from the bedroom carpet, living room carpet, mattress and sofa in 20 homes with and 20 homes without a dog in the same area. Personal airborne sampling (2 L/min) was conducted for 8 h in offices (n = 16) and classrooms (n = 9). In addition, airborne samples in schools were collected using a high volume pump (60 L/min) for 1 h in three classrooms immediately after the children vacated the school. Can f 1, Bla g 2, Der p 1 and Fel d 1 were assayed using a two-site monoclonal antibody-based ELISA. RESULTS: Can f 1 was detected in all dust samples from public places, ranging from 0.2 to 52.5 micrograms/g. Significantly higher levels were found in upholstered seats (geometric mean--GM 9.4 micrograms/g) than in carpets (GM 1.5 micrograms/g; P < 0.001), and levels of Can f 1 > 10 micrograms/g were found in 40% of upholstered seats in public places. Can f 1 was significantly higher in upholstered seats in public places than in sofas in homes without a dog (GM 1.8 micrograms/g; P < 0.001). Detectable levels of Bla g 2 were found in all of the schools (GM 2.4 U/g, range 0.8-4.4 U/g). Bla g 2 concentration greater than 2U/g (provisional threshold level representing risk of sensitization) was measured in 65% of the classrooms sampled. Der p 1 and Bla g 2 were below the detection limit in all airborne samples. However, airborne Fel d 1 and Can f 1 were detected in schools and offices, albeit in low concentrations. CONCLUSIONS: Upholstered seats from public places constitute a reservoir for the accumulation of dog allergen, and a source of exposure to Can f 1 inside public buildings or on public transport. Exposure to cockroach allergens in schools may be important for cockroach sensitized asthmatic children.

Air Pollution, Indoor↗
PubMed1995

Effects of air pollution on symptoms and peak expiratory flow measurements in subjects with obstructive airways disease.

BACKGROUND: Evidence from laboratory studies suggests that air pollution can produce bronchoconstriction and respiratory symptoms in selected subjects, but the relevance of these findings to exposure to natural pollution is unclear. This study was performed to determine whether air pollution at typical levels found in the UK has demonstrable effects on respiratory function and symptoms in subjects with airways disease. METHODS: Seventy five adult patients with diagnoses of asthma or chronic obstructive pulmonary disease (COPD) were studied for a period of four weeks during which they kept records of their peak expiratory flow (PEF) rates, symptoms (wheeze, dyspnoea, cough, throat and eye irritation), and bronchodilator use. Thirty six patients in whom the provocative dose of methacholine causing a 20% fall in FEV1 was below 12.25 mumol were classified as reactors. Ambient air pollution was measured with absorption spectroscopy. RESULTS: There were modest but significant increases in PEF variability, bronchodilator use, and wheeze with increasing sulphur dioxide levels; bronchodilator use, dyspnoea, eye irritation, and minimum PEF readings were related to ozone levels. In the subgroup of reactors falls in mean and minimum peak flow and increases in wheeze, dyspnoea, and bronchodilator use were associated with increases in levels of both sulphur dioxide and ozone. Some associations were seen with pollution levels on the same day, but for others the pollution effects appeared to be delayed by 24 or 48 hours. Pollution levels did not breach the WHO guide levels during the course of the study. CONCLUSIONS: Increases in environmental levels of ozone and sulphur dioxide are associated with adverse changes in peak flow measurements and both ocular and respiratory symptoms in subjects with obstructive airways disease. Although the peak flow and symptom changes were modest, they occurred at pollution levels below current WHO guide levels.

Adult↗
PubMed1994

Domiciliary air filtration units, symptoms and lung function in atopic asthmatics.

Air infiltration units (AFUs) incorporating a high efficiency particulate air filter are theoretically able to remove almost all potential airborne allergens. This may have implications for subjects with allergic lower respiratory disease. AFUs were placed in the living room of 12 atopic asthmatics, and the internal filters were inserted and removed in a double-blind fashion. No difference in subjective symptom scoring, spirometry or bronchial reactivity was demonstrated. Peak expiratory flow rate (PEFR) variability was significantly improved from baseline readings, and there was a trend towards higher mean PEFRs when the filters were present in the AFU. Trends towards lower levels of airborne micro-organisms were also demonstrated when the filters were present, however no effect upon total airborne dust and airborne Der pI could be demonstrated.

Air Conditioning↗
PubMed1994

Ocular and nasal irritation in operatives in Lancashire cotton and synthetic fibre mills.

OBJECTIVES: To document the prevalence of work related ocular (eyeWRI) and nasal (noseWRI) irritation in workers in spinning mills of cotton and synthetic textile fibres and to relate the prevalence of symptoms to atopy, byssinotic symptoms, work history, and measured dust concentrations in the personal breathing zone and work area. METHODS: A cross sectional study of 1048 cotton workers and 404 synthetic fibre workers was performed. A respiratory questionnaire was given to 1452 workers (95% of the total available population). Atopy was judged by skin prick tests to three common allergens. Work area cotton dust sampling (WAdust) was carried out according to EH25 guidelines in nine of the 11 spinning mills included in the study. Personal breathing zone dust concentrations were assessed with the IOM sampler to derive total dust exposure (PTdust) and a concentration calculated after the removal of fly (Pless). RESULTS: 3.7% of all operatives complained of symptoms of byssinosis, 253 (17.5%) complained of eyeWRI and 165 (11%) of noseWRI. These symptoms did not relate to atopy or byssinosis, or correlate univariately with any measure of cotton dust exposure (noseWRI v WAdust r = 0.153, PTdust r = 0.118, eyeWRI v WAdust r = 0.029, PTdust r = 0.052). Both of these symptoms on logistic regression analysis were related to being of white origin (P < 0.001), female sex (P < 0.001), and younger age (P < 0.001). With regression analysis, there was a negative relation between dust concentration and prevalence of symptoms. CONCLUSION: Work related ocular and nasal irritation are the most common symptoms complained of by cotton textile workers. There was no relation between these symptoms and atopy, byssinosis, or dust concentration. It is likely that they relate to as yet unidentified agents unrelated to concentration of cotton dust.

Adult↗
PubMed1994

Respiratory symptoms and dust exposure in Lancashire cotton and man-made fiber mill operatives.

A cross-sectional study of work-related symptoms and cotton dust exposure was made in 404 man-made fiber and 1,048 cotton operatives in Lancashire spinning mills; 39 cotton-exposed operatives (3.7%) had symptoms of byssinosis. This was associated on regression analysis with cumulative lifetime cotton dust exposure (p < 0.001), total years spent carding (p < 0.001), and currently working in the carding area (p = 0.0041). Smoking habit did not differ significantly between byssinotic and nonbyssinotic workers. Other work-related symptoms were common: chronic bronchitis (CB) and persistent cough. The prevalence of CB correlated positively with dust exposure (r = 0.59). Cotton dust sampling was performed in the work area (SDPRES) and personal breathing zone (PD1). A retrospective estimate of lifetime cotton dust exposure based on SDPRES correlated best with the prevalence of byssinosis (r = 0.797), although correlations with PD1 (r = 0.709) and SDPRES (r = 0.594) were also significant.

Adult↗
PubMed1993

Double-blind trial of steroid tapering in acute asthma.

It is customary to tail off the dose of oral steroids after treatment of an acute exacerbation of asthma; the main reason for this practice is to avoid rebound asthma. We have carried out a randomised double-blind study to find out whether a tapering course of oral prednisolone has any advantage over an abruptly terminated course of prednisolone for an episode of acute asthma requiring hospital admission. We studied 35 patients admitted to hospital with acute asthma; their mean peak expiratory flow rate (PEFR) on admission was 173 L/min and their mean age was 32 years (range 18-55); all were using inhaled steroids on discharge (mean dose 908 micrograms daily). Each patient received 40 mg enteric-coated prednisolone daily for 10 days followed by a tapering course of either prednisolone 5 mg tablets (active taper) or identical placebo tablets (placebo taper), reducing from 7 tablets on day 11 to no tablets by day 18. The primary outcome measure was the PEFR on waking. Both groups responded well to treatment by day 10 (mean morning PEFR: active taper group 396 L/min, placebo taper group 391 L/min). There was no further significant change in PEFR in either group during the 7 days of active or placebo tapering or during the following 10 days (repeated measures analysis of variance, active vs placebo, p = 0.82). The groups were also similar in terms of secondary outcome measures--symptom scores, PEFR after morning bronchodilator treatment, evening PEFR, and treatment failures. This study suggests that steroid tapering is unnecessary in acute asthma; a personal asthma management plan with a reserve course of prednisolone may be more appropriate.

Acute Disease↗
PubMed1993

Concentrations of the domestic house dust mite allergen Der p I after treatment with solidified benzyl benzoate (Acarosan) or liquid nitrogen.

BACKGROUND: Various methods of killing the house dust mite to reduce exposure to allergen are being promoted even though complete data on their effects on allergen concentrations are not available. A study was designed to measure the concentrations of the main house dust mite allergen Der pI in homes treated with either solidified benzyl benzoate (Acarosan) or liquid nitrogen. METHODS: Der pI concentrations were measured in dust collected from mattresses, bedroom carpets, and living room carpets in 10 houses treated with Acarosan and 10 houses treated with liquid nitrogen. Samples were collected before the treatment (in July 1990) and three and six months afterwards (October 1990 and January 1991). Forty untreated houses were concurrently sampled as controls. RESULTS: Der pI concentrations were similar in the three groups at baseline. No significant fall was seen in either of the two treated groups three or six months after treatment. Concentrations in the control houses increased significantly--twofold to threefold in dust sampled from mattresses and bedroom carpets between baseline and October 1990. This increase was not seen in either of the treated groups of houses, but there was no significant difference in the Derp pI concentrations in these houses and the control houses from any site at any time point. CONCLUSIONS: Neither Acarosan nor liquid nitrogen reduced the concentrations of Der pI for as long as six months after application. A small effect was probably present as the rise seen in control houses in the three month samples was not found in the treated houses. This effect, however, is likely to be of little clinical importance and also to be transient as the trend was lost by six months.

Allergens↗
PubMed1992

An investigation of the relationship between microbial and particulate indoor air pollution and the sick building syndrome.

The sick building syndrome has been the subject of research for approximately 10 years. Although it is often suggested that symptoms in office workers are due to circulating micro-organisms or particles, epidemiological studies investigating the relationship between them have been lacking. This cross-sectional study has combined medical and aerobiological assessments of offices in Great Britain and has found that, although airborne particulates and micro-organisms are unlikely to be the sole cause of the sick building syndrome, positive associations between symptom prevalence rates and levels of airborne viable bacteria and fungi within groups of buildings with similar ventilation systems, suggest a possible causal link that should be explored.

Air Microbiology↗
PubMed1992

A study of the performance and comparability of the sampling response to cotton dust of work area and personal sampling techniques.

In order to compare and contrast the sampling response to cotton dust of two forms of dust sampling 85 work areas were identified over a 2-year period for investigation in eight Lancashire spinning mills. Three hundred and five work area dust samples were undertaken and 252 personal dust samples were performed. Operatives who spent a minimum of 80% of their working shift in the area in which work area sampling was also performed were selected for personal sampling. Work area dust exposures have recently shown an upward trend, with highest concentrations occurring in the ring spinning room (median 1.15 mg m-3, range 0.82-2.06). Personal dust samples showed a reduction in dust exposures as cotton processing progressed, from a high in the opening room (median value of 6.24 mg m-3, range 1.0-41.5) to a minimum of 1.02 mg m-3 (range 0.30-0.93) in the winding room. The ratio of measured personal sampling dust exposure to work area sampling exposure was used to compare the relative performance of the two techniques. This ratio was highest in the early processes. There was a 7.8-fold difference in measurement between the two techniques in the opening processes, falling to 4.9 in carding and 4.2 in the other card-room processes. However in ring spinning the ratio was only 1.4, suggesting a degree of comparability in the methods at this stage of processing. The value rose to 2.5 for the last stage (winding). Respiratory disease is known to occur predominantly in the early stages of processing (opening and carding) where high dust concentrations are found using the personal technique. These data support the use of personal sampling for setting exposure limits to cotton dust in preference to the current recommended method using work area sampling techniques, which may significantly underestimate dust exposure in the high risk work areas and is outdated.

Dust↗
PubMed1992

Absence of seasonal variation in concentrations of the house dust mite allergen Der p1 in south Manchester homes.

BACKGROUND: House dust mite numbers and the concentration of its main allergen, Der p1, depend on ambient temperature and humidity and have been reported to show a seasonal variation in homes in the United States. A study was designed to find out whether Der p1 concentrations vary with the seasons in dust collected from homes in north west England. METHODS: The concentration of Der p1 was measured in dust, collected every three months from April 1990 to April 1991, from mattresses and from bedroom and living room carpets in 40 houses in the south Manchester area. Twenty four hour recordings of indoor relative humidity were made in 20 houses during the sampling day. RESULTS: Mean concentrations of Der p1 from all three sources rose two to three fold in October. This was in contrast to the 1000 fold variation in concentrations of Der p1 present between houses within each season's sample and less than the 10 fold change considered to be of clinical importance. The autumn increase was paralleled by a rise in humidity. There was no statistical correlation, however, between Der p1 concentrations and relative humidity, house type, ventilation, or double glazing. CONCLUSIONS: The results suggest that seasonal variations in exposure to Der p1 exposure in north west England are small and unlikely to be of major clinical importance. The temperature and humidity data showed that the indoor environment remained relatively constant and conducive to mite growth throughout the year.

Allergens↗
PubMed1992

Lung function, bronchial reactivity, atopic status, and dust exposure in Lancashire cotton mill operatives.

A total of 645 cotton mill operatives were administered a respiratory questionnaire. Of these, 85 (13.2%) complained of one or more work-related respiratory symptoms: 23 (3.6%) had byssinosis and the remaining 62 had symptoms not conforming to byssinosis (nonbyssinotic symptomatics, NBS). All byssinotic, 56 NBS, and 84 matched asymptomatic operatives underwent pulmonary function testing (FEV1 and FVC), skin testing to common allergens, and histamine bronchial challenge. Work area and personal breathing zone cotton dust concentrations were assessed, and a cumulative cotton dust exposure index was calculated for each individual. Byssinotic, NBS, and asymptomatic operatives all had reduced FEV1; observed mean liters (95% CI); predicted mean: byssinosis, 2.36 (2.09 to 2.63), 3.02; NBS, 2.94 (2.71 to 3.17), 3.29; and asymptomatic, 3.12 (2.95 to 3.29), 3.31. Only byssinotic subjects had evidence of impaired FVC: 3.31 (2.97 to 3.65), 3.69. The majority of byssinotic operatives (18 of 23) had bronchial hyperreactivity (BHR) in comparison with 21 of 56 NBS and 14 of 84 asymptomatic operatives. Mean log PD20 (95% CI) values were significantly lower in the byssinotic group -0.72 (-1.42, -0.02) than in NBS 0.57 (0.08, 1.06) and asymptomatic subjects 0.57 (-0.26, 1.39). The distribution of atopy did not differ significantly between groups, and lung function did not differ significantly between atopic and nonatopic subjects. The cumulative cotton dust exposure index was the only dust parameter to be significantly greater in those with BHR (mean mg-yr/m3 [95% CI] 14.13 [13.1 to 15.1]) than those with normal reactivity [5.35 (3.9 to 6.8)].

Adult↗