Domestic risk factors for wheeze in urban and rural Ethiopian children

BACKGROUND

To identify which environmental exposures underpin the emergence of asthma epidemics, we need to study epidemics as they appear, as is now happening in the Jimma region of Ethiopia. We have previously studied risk factors for asthma in adults in Jimma and have now completed a survey of young children.

AIM

To establish the prevalence of asthma in urban and rural children in Jimma, and to identify locally important risk factors.

DESIGN

Cross-sectional survey.

METHODS

All children aged 1-5 years living in Jimma town and three surrounding rural regions were identified. Data were collected using an interviewer-led questionnaire, and consenting children had skin prick tests to house dust mite and cockroach.

RESULTS

We surveyed 7155 children, of whom 3623 (51%) were female and 4285 (60%) lived in the urban area. The prevalence of wheeze in the last year was 3.4%, and was lower in the rural area (OR 0.47; 95%CI 0.34-0.66). In the urban area, the main risk factors for wheeze were a longer duration of breastfeeding, use of kerosene, and environmental tobacco smoke, while living with animals was protective. In rural children, the main risk factors were a positive skin prick test and living with animals.

DISCUSSION

The prevalence of wheeze in children in the Jimma region is low, particularly in rural children. In addition to having an impact on disease prevalence, place of residence also appears to modify the impact of environmental risk factors for wheeze.

Oral magnesium and vitamin C supplements in asthma: a parallel group randomized placebo-controlled trial

BACKGROUND

Epidemiological studies suggest that higher intakes of dietary vitamin C and magnesium may be associated with a reduced risk of asthma.

OBJECTIVE

To determine whether vitamin C or magnesium supplements improve the clinical control of asthma in primary care patients.

METHODS

A randomized, placebo-controlled, double-blind parallel group trial of 16 weeks supplementation with 1 g/day vitamin C, 450 mg/day magnesium chelate or matched placebo. Three hundred patients aged 18-60 years with physician-diagnosed asthma, controlled with at least one dose of an inhaled corticosteroid daily, were recruited from 24 primary care practices in Nottingham, UK. The main outcome measures were change in forced expiratory volume in 1 s, forced vital capacity, airway responsiveness to methacholine, mean morning and evening peak flow, symptom scores and bronchodilator use, both individually and as a combined summary statistic.

RESULTS

There was no evidence of any beneficial effect of either supplement on any outcome measure of asthma control in the primary intention-to-treat analysis, or in an analysis restricted to participants who completed the study.

CONCLUSIONS

Regular dietary supplementation with vitamin C or magnesium adds no clinical benefit to current standard therapy of asthma in primary care patients.

Effects of volatile organic compounds, damp, and other environmental exposures in the home on wheezing illness in children

BACKGROUND

The effects of indoor exposure to volatile organic compounds (VOCs), including formaldehyde, on respiratory health are not clearly understood. The aim of this study was to determine the independent effects of VOCs and other common environmental exposures in the home on the risk and severity of persistent wheezing illness in children.

METHODS

Total volatile organic compounds, formaldehyde, nitrogen dioxide, damp (on a four category scale of % wood moisture equivalent), and environmental tobacco smoke (from salivary cotinine) were measured objectively in the homes of 193 children with persistent wheezing illness and 223 controls aged 9-11 years in Nottingham, UK.

RESULTS

The risk of wheezing illness was significantly increased only in relation to damp (odds ratio (OR) per increasing category=1.32 (95% confidence interval (CI), 1.00 to 1.75)), and was unrelated to the other exposures measured. Among cases, formaldehyde and damp were associated with more frequent nocturnal symptoms (OR per increasing quartile and category, respectively, 1.45 (1.06 to 1.98) and 1.97 (1.10 to 3.53)), significantly more so in atopic cases, but there was no effect of total volatile organic compounds, nitrogen dioxide, or cotinine.

CONCLUSIONS

Domestic volatile organic compounds are not a major determinant of risk or severity of childhood wheezing illness, though formaldehyde may increase symptom severity. Indoor damp increases both the risk and severity of childhood wheezing illness.

Lymphangioleiomyomatosis: a case-control study of perinatal and early life events

BACKGROUND

Lymphangioleiomyomatosis (LAM), a rare disease affecting women, is caused by somatic mutations in the tuberous sclerosis complex genes.

METHODS

A case-control questionnaire study was carried out examining parental and family history, prenatal events, and early life events to try to shed light on the aetiology of the condition. Forty five patients identified from a national LAM register completed a questionnaire and 31 were compared with 117 age and sex matched control subjects using conditional logistic regression.

RESULTS

No differences were found in perinatal events, childhood infections, and parental or family history, except that patients were more likely to be an only child (odds ratio (OR) 4.3 (95% confidence interval (CI), 1.5 to 11.8)) and have a relative with uterine fibroids (OR 4.2 (1.4 to 13)). Patients with LAM had had fewer pregnancies and fewer children but no differences in miscarriage rates. A non-matched analysis using all 45 cases and 117 controls gave similar results.

CONCLUSIONS

No features in the family history, perinatal events, or early life events were detected that were associated with having LAM. Being more likely to be an only child and having an increased family history of uterine fibroids may, if confirmed, indicate some differences in reproductive function within the families of affected individuals.

Respiratory symptoms in patients with treated hypothyroidism and inflammatory bowel disease

BACKGROUND

Patients with idiopathic chronic cough and unexplained airflow obstruction in non-smokers have been shown to have an increased prevalence of hypothyroidism and other organ specific autoimmune disorders. Whether patients with hypothyroidism have an increased prevalence of respiratory symptoms is unknown.

METHODS

The prevalence of respiratory symptoms was assessed in 124 patients with treated hypothyroidism recruited from primary and secondary care, 64 outpatients with inflammatory bowel disease, and 1346 control adults recruited randomly from the electoral register in a case-control study. Respiratory symptoms and smoking history were assessed by a respiratory symptom questionnaire.

RESULTS

After adjustment for age, sex and smoking, symptoms of breathlessness and sputum production were more prevalent in both patient populations than in controls (odds ratios for hypothyroidism and inflammatory bowel disease; breathlessness: 3.1 (95% CI 2.1 to 4.6) and 3.4 (95% CI 2.0 to 6.0), respectively; sputum production: 2.7 (95% CI 1.6 to 4.5) and 2.5 (95% CI 1.2 to 5.0), respectively). Cough during the day and night was significantly more prevalent in patients with hypothyroidism (1.8 (95% CI 1.2 to 2.9)) and approached significance in those with inflammatory bowel disease (1.8 (95% CI 1.0 to 3.4)). Wheeze and nocturnal cough were no more prevalent in either disease population than in controls.

CONCLUSION

There is a significantly increased prevalence of respiratory symptoms in patients with hypothyroidism or inflammatory bowel disease compared with controls recruited from the general population. Further work is required to determine whether similar differences are seen in comparison with hospital based controls. These findings support the hypothesis that there is a link between autoimmune hypothyroidism and respiratory disease.

Defining community acquired pneumonia severity on presentation to hospital: an international derivation and validation study

BACKGROUND

In the assessment of severity in community acquired pneumonia (CAP), the modified British Thoracic Society (mBTS) rule identifies patients with severe pneumonia but not patients who might be suitable for home management. A multicentre study was conducted to derive and validate a practical severity assessment model for stratifying adults hospitalised with CAP into different management groups.

METHODS

Data from three prospective studies of CAP conducted in the UK, New Zealand, and the Netherlands were combined. A derivation cohort comprising 80% of the data was used to develop the model. Prognostic variables were identified using multiple logistic regression with 30 day mortality as the outcome measure. The final model was tested against the validation cohort.

RESULTS

1068 patients were studied (mean age 64 years, 51.5% male, 30 day mortality 9%). Age >/=65 years (OR 3.5, 95% CI 1.6 to 8.0) and albumin <30 g/dl (OR 4.7, 95% CI 2.5 to 8.7) were independently associated with mortality over and above the mBTS rule (OR 5.2, 95% CI 2.7 to 10). A six point score, one point for each of Confusion, Urea >7 mmol/l, Respiratory rate >/=30/min, low systolic(<90 mm Hg) or diastolic (</=60 mm Hg) Blood pressure), age >/=65 years (CURB-65 score) based on information available at initial hospital assessment, enabled patients to be stratified according to increasing risk of mortality: score 0, 0.7%; score 1, 3.2%; score 2, 3%; score 3, 17%; score 4, 41.5% and score 5, 57%. The validation cohort confirmed a similar pattern.

CONCLUSIONS

A simple six point score based on confusion, urea, respiratory rate, blood pressure, and age can be used to stratify patients with CAP into different management groups.

Relationship between FEV1 reduction and respiratory symptoms in the general population

Obstructive airways diseases typically present with dyspnoea, cough and wheeze, and are defined by a reduced forced expiratory volume in one second (FEV1/forced vital capacity (FVC) ratio. Traditionally, however, the severity of chronic obstructive pulmonary disease is graded by the FEV1 % predicted rather than the FEV1/FVC ratio, whilst other potentially valid measures of FEV1 impairment, such as the absolute difference of FEV1 from predicted or the absolute level of FEV1, tend not to be used. The authors have therefore explored the relationship between these different measures of FEV1 impairment and chronic respiratory symptoms in a general population sample. FEV1 and FVC were measured and questionnaire data were obtained on cough, wheeze, shortness of breath and general self-reported breathing trouble in a cross-sectional survey of 2,633 adults aged 18-70 yrs from a district of Nottingham, UK. Odds ratios for each symptom were calculated for declining levels of absolute FEV1, FEV1 % pred, absolute difference of FEV1 from predicted, and FEV1/FVC ratio. They were plotted to display the shape and strength of these relationships before and after adjustment for each other measure. The odds of symptoms increased with declining levels of all FEV1 measures, particularly for wheeze and general breathing trouble. Although this study was not sufficiently powerful to detect significant differences between measures, these relationships were consistently strongest, before and after adjustment, for FEV1 % pred, particularly below a threshold of approximately 75%. The authors conclude that forced expiratory volume in one second % predicted appears to be the measure of airflow impairment most closely associated with chronic respiratory symptoms in the general population.

Living near a main road and the risk of wheezing illness in children

The effect of road vehicle traffic pollution on asthma is still not clearly understood. However, any effect is likely to be most marked among those who live within 150 m of a main road, because this is the distance within which concentrations of primary vehicle traffic pollutants are raised above ambient background levels. We have investigated the relation between proximity of the family home to the nearest main road, estimated objectively using geographical information system software, and the risk of wheeze in the past year in a case-control sample of 6,147 primary schoolchildren (age 4 to 11 yr) and a random cross-sectional sample of 3,709 secondary schoolchildren (age 11 to 16 yr) in Nottingham, United Kingdom. Among children living within 150 m of a main road, the risk of wheeze increased with increasing proximity by an odds ratio (OR) of 1.08 (95% confidence interval [CI] 1.00 to 1.16) per 30-m increment in primary schoolchildren, and 1.16 (1.02 to 1.32) in secondary schoolchildren. Most of the increased risk was localized to within 90 m of the roadside. Among primary schoolchildren, effects were stronger in girls than boys (p(interaction) = 0.02). Living within approximately 90 m of a main road is associated with a proximity-related increase in the risk of wheezing illness in children.

Analysis of 1,3-Dichloropropene for Control of Meloidogyne spp. in a Tobacco Pest Management System

1,3-Dichloropropene (1,3-D) and nonfumigant nematicides were evaluated for control of Meloidogyne spp. and soil and foliar insects in a tobacco pest management system. In a field with a high Meloidogyne spp. population density (root gall index 4.0 to 4.5 on a 0 to 10 scale in untreated controls), tobacco yields and crop values increased (482 kg/ha and $1,784/ha for 1, 3-D; 326 kg/ha and $1,206/ha for fenamiphos; 252 kg/ha and $933/ha for ethoprop) with nematicide application over an untreated control. In fields with a low population density of Meloidogyne arenaria or M. incognita (root gall index 2.3 to 2.5 in untreated controls), yields ranged from 1,714 to 2,027 kg/ha and were not altered by fumigant or nonfumigant nematicide application. Carbofuran, a soil-applied nonfumigant nematicide/insecticide, reduced the number of foliar insecticide applications required to keep insect populations below treatment threshold (3.8 vs. 4.5, respectively, for treated vs. untreated). Carbofuran reduced the cost ($23/ha) of foliar insecticide treatments when compared to an untreated control. Although nonfumigant nematicides provided some soil and foliar insect control, the cost of using a fumigant plus a lower insecticidal rate of a soil insecticide/nematicide was comparable to the least expensive non-fumigant nematicide when the cost of foliar insecticide applications was included in the cost estimates. Savings in foliar insecticide cost by use of soil-applied nonfumigant nematicide/insecticides were small ($23/ha) in comparison to potential value reductions by root-knot nematodes when the nonfumigant nematicides fenamiphos or ethoprop ($578/ha and $851/ha, respectively) were used instead of 1,3-D.

Airway responsiveness and peak flow variability in the diagnosis of asthma for epidemiological studies

Airway responsiveness and variability in peak expiratory flow (PEF) are widely used as objective diagnostic measures of asthma, but it is not clear how these variables should be calculated or adjusted to obtain the highest diagnostic validity for physician-diagnosed asthma in the community. Data from a community-based sample of 1,513 adults has been used. Airway responsiveness to methacholine and 7-day PEF data were obtained in 1991, asthma and respiratory symptoms were diagnosed by questionnaires in 1991 and 1999. Airway responsiveness was expressed as the provocative dose causing a 20% fall in forced expiratory volume in one second (PD20), two-point and least-squares regression slopes. PEF variability was expressed as daily amplitude, weekly standard deviation and mean of the two lowest readings. Continuous measures were adjusted for measures of baseline airway calibre by linear regression. Measures of airway responsiveness had greater sensitivity for specificity for self-reported diagnosed asthma than expressions of PEF variability, before and after adjustment for airway calibre. Diagnostic validity was substantially better in adults aged <50 yrs; PD20 provided the best sensitivity for specificity (61% for 95% at 8.3 micromol). In those aged > or =50 yrs, no measure was closely related to diagnosed asthma. In younger age groups, provocative dose causing a 20% fall in forced expiratory volume in one second provides a valuable objective measure of asthma for epidemiological studies, but is unable to distinguish between asthma and chronic obstructive pulmonary disease in older people.

Crop Rotation and Nematicides for Management of Mixed Populations of Meloidogyne spp. on Tobacco

The effects of crop rotation and the nematicides 1,3-dichloropropene (1,3-D), ethoprop, and fenamiphos on the relative frequency of Meloidogyne incognita race 3, M. arenaria race 2, and M. javanica and tobacco yields on a sandy loam soil were determined. Cropping sequences altered the species composition and population densities of Meloidogyne spp. Meloidogyne arenaria and M. incognita predominated when cotton, corn, sorghum, or rye-fallow preceded tobacco. Meloidogyne javanica and M. arenaria predominated when tobacco preceded tobacco. Sorghum, cotton, corn, or rye-fallow preceding tobacco enhanced yields compared to tobacco preceding tobacco in plots containing mixtures of Meloidogyne species. Sorghum supported minimal reproduction of any Meloidogyne spp. Application of 1,3-D increased tobacco yields and reduced root galling when compared to untreated controls. Both fenamiphos and ethoprop treatments were less effective than 1,3-D in controlling Meloidogyne spp. or increasing yields. A rotation crop x nematicide interaction was not observed. In continuous tobacco, use of the M. incognita-resistant tobacco cv. Coker 176 increased tobacco yields when compared to the M. incognita-susceptible cv. Coker 319 when 1,3-D was not applied.

Increased risk of allergy associated with the use of kerosene fuel in the home

Allergic diseases are becoming increasingly prevalent in developing countries, consistent with an environmental etiology associated with affluence or urbanization. We have tested the hypothesis that the risk of allergy is increased by the use of non-biomass fuels (kerosene, gas or electricity) in the home, using data from a survey of the urban population of Jimma, Ethiopia. Questionnaire data on allergic symptoms, domestic fuel use and lifestyle factors were collected from 9844 adults and children, and allergen skin sensitization measured in a subsample of 2372. Use of any non-biomass fuel was reported by 959 individuals (10%), usually in combination with biomass fuel, and was significantly associated with an increased risk of allergic sensitization (age, sex and socio-economic status adjusted odds ratio (95% confidence interval) = 1.78 [1.06 to 2.97]) and wheeze (1.56 [1.07 to 2.26]), rhinitis (2.06 [1.46 to 2.91]) and eczema (2.82 [1.61 to 4.96]) relative to use of biomass fuel only. These effects were predominantly due to kerosene, which was significantly related to all outcomes, and gas, which was strongly related to allergic sensitization. Our findings suggest that domestic combustion of refined fossil fuels increases the risk of allergic sensitization and symptoms, and may have contributed to the increasing prevalence of allergic disease.

Siblings, multiple births, and the incidence of allergic disease: a birth cohort study using the West Midlands general practice research database

BACKGROUND

The presence of older siblings reduces the risk of developing hay fever, eczema and atopy, but findings for asthma have been inconsistent. Whether twins have a reduced risk of allergic disease is also unclear. We have investigated these questions in a birth cohort analysis of the West Midlands General Practice Research Database (GPRD).

METHODS

Our birth cohort included 29,238 children. The incidence of allergic disease was examined according to the number of siblings, multiple births, and parental allergic disease and smoking habit using Cox regression.

RESULTS

There was a dose related decrease in the incidence of eczema and hay fever with increasing number of older siblings (hazard ratio for children with three or more older siblings compared with none 0.70 (95% CI 0.64 to 0.76) for eczema and 0.67 (95% CI 0.52 to 0.86) for hay fever). In contrast, the presence of older siblings increased the incidence of asthma (HR 1.17, 95% CI 1.06 to 1.29), although this effect was strongly dependent on age of diagnosis. For children diagnosed over the age of 2 years the presence of older siblings was protective (HR 0.66, 95% CI 0.52 to 0.82), while below this age the reverse was true (HR 1.38, 95% CI 1.24 to 1.54). Members of a multiple birth had a reduced incidence of all three allergic diseases. Birth order and multiple birth effects were independent of sex, maternal age, consulting behaviour, and parental allergy and smoking habit.

CONCLUSIONS

The presence of older siblings and being a member of a multiple birth appears to protect against the development of eczema, hay fever, and asthma diagnosed after the age of 2. In contrast, the presence of older siblings increases the incidence of early asthma.

Adverse effects of oral corticosteroids in relation to dose in patients with lung disease

BACKGROUND

The adverse effects of oral corticosteroids are widely recognised but there are few quantitative data on which to base advice to patients. In a two part cross sectional study we compared adverse effects in patients with lung disease taking oral corticosteroids and control subjects and related the adverse effects to corticosteroid dose in the patient group.

METHODS

Data on oral corticosteroid use, lifestyle, fractures, and other possible adverse effects were collected by questionnaire and compared between a community based cohort of patients taking continuous or frequent intermittent oral corticosteroids for asthma, chronic obstructive pulmonary disease, or alveolitis and age and sex matched control subjects. Dose related effects were explored in the corticosteroid group using cumulative dose quartiles and multiple logistic regression.

RESULTS

A total of 367 patients (> or = 50 years, 48% female) and 734 control subjects completed the questionnaire. The cumulative incidence of fractures since the time of diagnosis was 23% for patients taking oral corticosteroids and 15% in the control group (odds ratio (OR) 1.8; 95% confidence interval (CI) 1.3 to 2.6). Patients were more likely to have had a fracture of the vertebrae (OR 10; 95% CI 2.9 to 34), hip (OR 6; 95% CI 1.2 to 30), and ribs or sternum (OR 3.2, 95% CI 1.6 to 6.6) than control subjects. They also reported a significant increase in cataracts, use of antacids, muscle weakness, back pain, bruising, oral candidiasis, and having fewer teeth. The effects of oral corticosteroids were dose related: the odds ratio for patients in the highest compared with the lowest cumulative dose quartile (median prednisolone dose 61 g versus 5 g) ranged from 2 for all fractures to 9 for vertebral fractures and bruising.

CONCLUSIONS

By quantifying the morbidity associated with the use of oral corticosteroids, this study should help to rationalise their long term use.

Association of specific allergen sensitization with socioeconomic factors and allergic disease in a population of Boston women

BACKGROUND

Socioeconomic differences in allergic disease prevalence have been reported; asthma has been associated with poverty in the United States and hay fever and eczema with relative affluence elsewhere. It is not yet established to what degree such differences in disease prevalence reflect patterns of sensitization and specific allergen sensitivities.

OBJECTIVE

We analyzed specific and total IgE measurements in a sample of 458 women, enriched for allergic disease, from the metropolitan Boston area to establish the relation of allergen sensitization to markers of socioeconomic status (SES) and to the prevalence and socioeconomic pattern of allergic disease in this community.

METHODS

Total and specific IgE antibodies were measured with the UNICAP System; self-reported allergic disease, household income, education, and race-ethnicity were ascertained with a questionnaire; and a further marker of poverty (percentage living below the poverty level) in the women's area of residence was established on the basis of zip codes. Analysis was performed with SAS statistical software.

RESULTS

Markers of low SES were univariately associated with increases in total IgE, number of allergen sensitizations, and levels of specific IgE. Socioeconomic differences in sensitization to cockroach (35% vs 6% in the highest and lowest poverty areas), animal (44% vs 26%), and ragweed (49% vs 23%) allergens were most marked. Sensitization primarily to indoor inhalant allergens (not ragweed or ryegrass) were associated with an increased risk of asthma, even after adjustment for SES.

CONCLUSION

We have demonstrated a socioeconomic gradient in sensitization that concords with increased rates of asthma in less affluent communities in this population.

Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

We present measurements of time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurement uses a data sample of 23x10(6) Upsilon(4S)-->BbarB decays collected by the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we find events in which one neutral B meson is fully reconstructed in a CP eigenstate containing charmonium and the flavor of the other neutral B meson is determined from its decay products. The amplitude of the CP-violating asymmetry, which in the standard model is proportional to sin2beta, is derived from the decay time distributions in such events. The result is sin2beta = 0.34+/-0.20 (stat)+/-0.05 (syst).

Processes involved in the development of latent fingerprints using the cyanoacrylate fuming method

Chemical processes involved in the development of latent fingerprints using the cyanoacrylate fuming method have been studied. Two major types of latent prints have been investigated-clean and oily prints. Scanning electron microscopy (SEM) has been used as a tool for determining the morphology of the polymer developed separately on clean and oily prints after cyanoacrylate fuming. A correlation between the chemical composition of an aged latent fingerprint, prior to development, and the quality of a developed fingerprint has been observed in the morphology. The moisture in the print prior to fuming has been found to be more important than the moisture in the air during fuming for the development of a useful latent print. In addition, the amount of time required to develop a high quality latent print has been found to be within 2 min. The cyanoacrylate polymerization process is extremely rapid. When heat is used to accelerate the fuming process, typically a period of 2 min is required to develop the print. The optimum development time depends upon the concentration of cyanoacrylate vapors within the enclosure.

Tactile illusion perception in patients with central pain

OBJECTIVE

To evaluate lemniscal pathways in patients with central pain (CP) by use of a novel tactile illusion (TI)-producing technique.

PATIENTS AND METHODS

Somatosensory (SS) and TI testing was performed on the unaffected and affected wrists of 27 patients with unilateral central nervous system injury and unilateral CP. Data on TI testing-naive control subjects were used to adjust for a learning effect.

RESULTS

Testing in CP patients with cervical and brainstem injuries revealed predominantly unchanged or decreased SS perception on the affected side compared with the unaffected side. The majority of cervical- and brainstem-injured subjects with CP had improved TI performance on the affected side compared with the unaffected side. All the thalamic-injured and most of the suprathalamic-injured CP patients had altered SS testing with either decreased or increased SS perception noted. In these same CP patients the majority had reduced TI perception on the affected side compared with the unaffected side. Unexpectedly, perseveration of numbers was noted in patients with Dejerine-Roussy syndrome, and expanded TI testing was performed to better define this observation.

CONCLUSION

Cervical spinal cord-injured CP patients may have improved TI perception, whereas the majority of patients with supraspinal injuries and CP have reduced SS and TI perception. A unique sensory phenomenon of TI perseveration was observed in some patients with Dejerine-Roussy syndrome.

The relation between peripheral blood leukocyte counts and respiratory symptoms, atopy, lung function, and airway responsiveness in adults

STUDY OBJECTIVES

Eosinophils and neutrophils play major roles, respectively, in the pathogenesis of asthma and COPD, and it is well recognized that levels of these cells in peripheral blood are increased in relation to their pulmonary involvement. However, the relation between peripheral blood cell counts of the other major leukocyte groups and these lung diseases or markers of allergy or airflow obstruction is less clear. We have therefore investigated the association between peripheral blood levels of eosinophils, neutrophils, basophils, monocytes, and lymphocytes and the occurrence of chronic respiratory symptoms, atopy, lung function, and bronchial hyperresponsiveness, and the modifying effect of age, in adults.

DESIGN

A cross-sectional general population study.

SETTING

Data on > 2,000 British adults, who originally participated in a study of diet and lung health, were analyzed using multiple linear and logistic regression to adjust for potential confounders, including age, sex, and smoking history.

RESULTS

We found that, like eosinophils, the peripheral basophil count was increased in relation to asthma and associated symptoms, and to airway hyperreactivity and increased total IgE, but differed from eosinophils in that basophils were unrelated to atopy. Monocytes were predominantly associated with symptoms indicative of obstructive airway disease, in similar relation to neutrophils, but both of these leukocyte counts were also increased in asthma patients in older age groups. Lymphocyte counts were unrelated to any objective or subjective marker of disease.

CONCLUSIONS

If peripheral blood cell counts reflect pulmonary involvement of these leukocyte groups, basophils and monocytes may play a distinct role in the pathogenesis of allergic and nonallergic respiratory disease.

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) or heavy (> 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.

Urea modifies the permeability of the mammalian urothelium

PURPOSE

This study investigated the effects of mucosal (urine side) and serosal (blood side) urea on the permeability properties of the in vitro mammalian urinary bladder epithelium.

MATERIALS AND METHODS

The permeability properties of the rabbit urinary bladder epithelium were studied in modified Ussing chambers using electrophysiological techniques.

RESULTS

Addition of two molar urea to the mucosal solution did not cause a significant change in the short circuit current (Isc, a measure of the ion transport capacity of the epithelium), or the transepithelial conductance (Gt, a measure of the ability of ions to diffuse across the epithelium). In contrast, addition of 0.5 M urea to the serosal solution caused an increase in Gt of approximately 35 microS/cm.2 as well as an increase in Isc over a 5 minute period. The site of the conductance increase by short-term serosal urea was at the apical membrane and not at the tight junctions. The urea-induced conductance completely reversed upon removal of urea, was non-selective, and the magnitude was voltage dependent. Long term serosal urea (greater than 30 minutes) resulted in an irreversible increase in transepithelial conductance. Mucosal urea altered the time course but not the magnitude of the serosal urea-induced conductance.

CONCLUSIONS

The ion permeability of the mammalian urinary bladder is increased by serosal urea. At short times the increase is at the apical membrane, while at long times the increase is at the tight junctions. The presence of mucosal urea slows the loss of urothelial barrier function caused by serosal urea.