Asthma and allergy development: contrasting influences of yeasts and other fungal exposures

BACKGROUND

Infancy is a developmental stage with heightened susceptibility to environmental influences on the risk of chronic childhood disease. Few birth cohort studies have detailed measures of fungal diversity data in infants' bedrooms, limiting the potential to measure long-term associations of these complex exposures with development of asthma or allergy.

OBJECTIVE

We evaluated the relation of home fungal levels in infancy to repeated measures of wheeze and development of asthma and rhinitis by age 13, and sensitization by age 12 years.

METHODS

In the Epidemiology of Home Allergens and Asthma prospective birth cohort study, we recruited 408 children with family history of allergic disease or asthma. When children were aged 2-3 months, we measured culturable fungi in bedroom air and dust, and in outdoor air. Main outcomes included ascertainment of symptoms/disease onset by questionnaire from birth through age 13. We estimated hazard ratios and, for wheeze and sensitization, odds ratios for an interquartile increase in log-transformed fungal concentrations, adjusting for other outcome predictors and potential confounders.

RESULTS

Elevated levels of yeasts in bedroom floor dust were associated with reduced: i) wheeze at any age; ii) fungal sensitization; and iii) asthma development by age 13 (hazard ratio (HR) = 0.86; 95% confidence interval (CI), [0.75 to 0.98]). Outdoor airborne Cladosporium and dustborne Aspergillus predicted increased rhinitis. Risk of fungal sensitization by age 12, in response to environmental Alternaria and Aspergillus, was elevated in children with a maternal history of fungal sensitization.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite the irritant and allergenic properties of fungi, early-life elevated dust yeast exposures or their components may be protective against allergy and asthma in children at risk for these outcomes. Ascertainment of fungal components associated with immunoprotective effects may have therapeutic relevance for asthma.

Wheeze in infancy: protection associated with yeasts in house dust contrasts with increased risk associated with yeasts in indoor air and other fungal taxa

BACKGROUND

While fungal exposures are assumed to provoke wheeze through irritant or allergenic mechanisms, little is known about the differential effects of indoor and outdoor fungi on early-life wheeze.

METHODS

In a Boston prospective birth cohort of 499 at-risk infants, culturable fungi in bedroom air and dust and outdoor air were measured at the age of 2-3 months. Wheeze was determined using bimonthly telephone questionnaires. Odds ratios were estimated for an interquartile increase in fungal natural log-transformed concentrations, adjusting for predictors of wheeze and potential confounders.

RESULTS

Increased odds of 'any wheeze' (≥1 vs 0 episodes) by age one were positively associated with indoor dust Alternaria [odds ratio (OR) = 1.83; 95% confidence interval (CI), 1.07-3.14], Penicillium [OR = 1.18; (0.98-1.43)], and Cladosporium [OR = 1.47; (1.16-1.85)]; indoor air Penicillium [OR = 1.26; (0.92-1.74)]; and outdoor air Cladosporium [OR = 1.68; (1.04-2.72)]. In contrast, indoor dust yeasts were protective [OR = 0.78; (0.66-0.93)]. 'Frequent wheeze' (≥2 vs <2 episodes) by age one was borderline associated with dust yeasts [OR = 0.86; (0.70-1.04)] and indoor air yeasts [OR = 1.53; (0.93-2.53)]. Alternaria concentration was associated with any wheeze for children with maternal mold sensitization [OR = 9.16; (1.37-61.22)], but not for those without maternal mold sensitization [OR = 1.32; (0.79-2.20)].

CONCLUSIONS

While wheeze rates were higher with exposures to fungal taxa considered to be irritant or allergenic in sensitive subjects, yeasts in the home had a strong protective association with wheeze in infancy. Molecular microbiologic studies may elucidate specific components of innate microbiologic stimulants that lead to contrasting effects on wheeze development.

Characterization of metalworking fluid exposure indices for a study of acute respiratory effects

Although metalworking fluids have been widely used throughout industry for decades, occupational exposures to metalworking fluid aerosols and their constituents have not been well characterized. This article describes an exposure assessment for a study of metalworking fluid aerosols and acute respiratory effects. This exposure assessment was unique in its inclusion of multiple exposure measures relevant to a complex environment, and extensive personal sampling for bacteria and endotoxin. The specific objectives were to: (1) obtain indices of personal exposure to metalworking fluid aerosols in an automotive transmission plant, either directly (by sampling) or indirectly (by estimation), and (2) identify and adjust for sources of error in exposure/dose measures, where possible. No prior studies have characterized personal exposures to metalworking fluid aerosols so extensively. Exposure data were obtained during a pilot phase and three principal rounds of data collection over a 15-month period in conjunction with spirometric testing. Subjects worked in one of two machining departments, Case and Valve Body, or in a comparison department, Final Assembly. The primary exposure measures for this study were thoracic fraction particulate, thoracic fraction bacteria (viable plus non-viable), and total endotoxin. Mean personal air concentrations of thoracic particulate across all study rounds were 0.13 mg/m3 in Final Assembly, 0.32 mg/m3 in Valve Body, and 0.56 mg/m3 in Case. Average personal exposures to thoracic fraction bacteria were 0.38 bacteria/cc in Final Assembly, 0.87 bacteria/cc in Valve Body, and 2.66 bacteria/cc in Case. Average personal endotoxin measurements, collected in Round 3 of the study, were 16.4 endotoxin units (EU)/m3 in Assembly, 34.7 EU/m3 in Valve Body, and 234 EU/m3 in Case. Sump fluid contained on the order of 10(8) bacteria/ml, and 10(4)-10(5) EU/ml. Air concentrations of thoracic particulate, thoracic bacteria, and total endotoxin were highly correlated in metalworking operations. Thus, reducing airborne particulate levels should also reduce ambient bacteria and endotoxin, which are suspect agents of respiratory impairment. The elevated endotoxin levels in Final Assembly were unexpected, and suggest an independent source of endotoxin contamination in this department.

The effect of serial dilution error on calibration inference in immunoassay

A common practice in immunoassay is the use of sequential dilutions of an initial stock solution of the antigen of interest to obtain standard samples in a desired concentration range. Nonlinear, heteroscedastic regression models are a common framework for analysis, and the usual methods for fitting the model assume that measured responses on the standards are independent. However, the dilution procedure introduces a propagation of random measurement error that may invalidate this assumption. We demonstrate that failure to account for serial dilution error in calibration inference on unknown samples leads to serious inaccuracy of assessments of assay precision such as confidence intervals and precision profiles. Techniques for taking serial dilution error into account based on data from multiple assay runs are discussed and are shown to yield valid calibration inferences.

Quantification of ergosterol and 3-hydroxy fatty acids in settled house dust by gas chromatography-mass spectrometry: comparison with fungal culture and determination of endotoxin by a Limulus amebocyte lysate assay

Ergosterol and 3-hydroxy fatty acids, chemical markers for fungal biomass and the endotoxin of gram-negative bacteria, respectively, may be useful in studies of health effects of organic dusts, including domestic house dust. This paper reports a method for the combined determination of ergosterol and 3-hydroxy fatty acids in a single dust sample and a comparison of these chemical biomarkers determined by gas chromatography-mass spectrometry with results from fungal culture and Limulus assay. Analyses of replicate house dust samples resulted in correlations of 0.91 (ergosterol in six replicates; P < 0.01) and 0.94 (3-hydroxy fatty acids in nine replicates; P < 0.001). The amounts of ergosterol (range, 2 to 16.5 ng/mg of dust) correlated with those of total culturable fungi (range, 6 to 1,400 CFU/mg of dust) in 17 samples, (r = 0.65; P < 0.005). The amounts of endotoxin (range, 11 to 243 endotoxin units/mg of dust) measured with a modified chromogenic Limulus assay correlated with those of lipopolysaccharide (LPS) determined from 3-hydroxy fatty acid analysis of 15 samples. The correlation coefficient depended on the chain lengths of 3-hydroxy acids used to compute the LPS content. The correlation was high (r = 0.88 +/- 0.01; P < 0.001) when fatty acid chains of 10 to 14 carbon atoms were included; the correlation was much lower when hydroxy acids of 16- or 18-carbon chains were included. In conclusion, the results of the described extraction and analysis procedure for ergosterol and 3-hydroxy fatty acids are reproducible, and the results can be correlated with fungal culture and endotoxin activity of organic dust samples.

Acute respiratory effects on workers exposed to metalworking fluid aerosols in an automotive transmission plant

Exposure to metalworking fluids has been linked to modest cross-shift reductions in FEV1 and occupational asthma. To identify responsible agents, we measured personal exposures to thoracic particulate (TP), viable plus nonviable thoracic bacteria (BAC), and vapor phase nicotine (VPN) (as a surrogate for tobacco particulate) among 83 machinists exposed to soluble oils and 46 dry assemblers working in an automotive transmission machining plant using biocides infrequently. The participants completed interviews and performed pre- and postshift spirometry on Monday and Thursday of the same week in each of three rounds of data collection (June 1992, January 1993, June 1993). Generalized estimating equations were used to combine information across rounds in multiple regression models of cross-shift and cross-week changes in forced expiratory volume, I second (FEV1) and forced vital capacity (FVC). Mean seniority was 19 years among machinists. Mean personal TP levels were 0.41 mg/m3 in machinists and 0.13 mg/m3 in assemblers. Six of the 83 machinists and none of the 46 assemblers experienced a greater than 19% cross-shift decrement in FEV1 or FVC at least once (p = .07). In regression models using either TP or BAC, among subjects with lower baseline (Monday preshift) FEV1/FVC ratios, increasing exposure was significantly associated with increasing cross-shift decrements in FEV1 and FVC in linear models, and with increased likelihood of a 10% or greater cross-shift decrement in FEV1 or FVC in logistic models. Adjustment of TP for VPN did not affect models significantly. We conclude that clinically important cross-shift decrements in pulmonary function are associated with exposure to metalworking fluid aerosols within a high-seniority population.

Fungus spores, air pollutants, and other determinants of peak expiratory flow rate in children

The impact of summertime haze episodes on daily variations in symptoms and peak expiratory flow rates (PEFRs) was examined in a study of 108 children living in State College, Pennsylvania, during the summer of 1991. Twice daily, each child recorded symptoms, PEFRs and hours spent outdoors. Environmental measurements included daily 12- and 24-hour averages for meteorologic and air pollutant variables and 24-hour average fungus spore concentrations. A 10,000-spore/m3 increment in Cladosporium spore concentration was associated with a deficit in morning PEFR (-1.0 liters/minute, 95% confidence interval (CI) -1.9 to -0.2). A 60-spore/m3 increment in Epicoccum spore concentration was associated with increased incidence of morning cough (odds ratio (OR) = 1.8, 95% CI 1.0-3.2) and a deficit in morning PEFR (-1.5 liters/minute, 95% CI -2.8 to -0.2). Fungi spore counts were not associated with respirable particle mass. A 125-nmol/m3 increment in 12-hour daytime particle-strong acidity was associated with a deficit in evening PEFR (-0.5 liters/minute, 95% CI -1.2 to 0.2) and increased incidence of cold episodes that evening or the subsequent morning (OR = 1.35, 95% CI 1.14-1.61). A 20-microgram/m3 increment in 24-hour respirable particles lagged by 24 hours was associated with a deficit in evening PEFR (-0.5 liters/minute 95% CI -1.4 to 0.4) and increased incidence of cough episodes that evening or the subsequent morning (OR = 1.37, 95% CI 1.13-1.66). These results confirm the acute effects of summertime particulate air pollution and suggest that aeroallergens have independent effects on respiratory symptoms and PEFR in children.

Bioaerosols: prevalence and health effects in the indoor environment

Assessing the role of bioaerosols in residence-related symptoms involves (1) determining that symptoms are related to the residence by medical examination and careful questioning, (2) connecting reported symptoms with known or hypothesized effects of bioaerosols, (3) examining the residence for bioaerosol risk factors such as overcrowding/poor ventilation, inappropriate outdoor air intrusion, and dampness/standing water, (4) and finally, if no obvious risk factors are present, air sampling. Air sampling should always be a last resort and should use a reliable volumetric method. Particulate samplers, such as the Burkard personal spore trap, are inexpensive alternatives to viable particle samplers and will provide data on most organisms implicated in hypersensitivity diseases. Interpretation of residential bioaerosol sample data requires both qualitative and quantitative comparison with adjacent outdoor air and examination of aerosol changes related to domestic activities. Recommendations that should lead to a decrease in indoor bioaerosols include the use of air conditioning to allow limitation of outdoor aerosols, prevention of dampness or moisture intrusion, and discouraging the use of humidifying devices other than steam. Bioaerosol assessment in the workplace is often more complex than for residences. Because the symptomatic subjects are not in charge of the environment, such situations often lead to difficult employee/management relations and occasionally to litigation. It is essential that each step in workplace bioaerosol assessment be defensible and that the best possible methods are used. The approach is similar to the approach used for residences, but on a larger scale. Symptom assessment must include stress and ergonomic factors. Air sampling, if this is necessary, must usually be extensive with controls for ventilation rates, occupancy, and spatial variation.

Epicoccum allergy: skin reaction patterns and spore/mycelium disparities recognized by IgG and IgE ELISA inhibition

Comparable degrees of skin reactivity were observed towards spore and mycelium extracts from two isolates of Epicoccum and to one preparation of Alternaria in 35 rural and 120 university patients. The best experimental extracts detected Epicoccum sensitivity in 70% of the group tested while the commercial extract detected sensitivity in only 6%. Skin reaction correlations were greatest within isolates (eg, spore-A/mycelium-A), then for specific fungus parts (eg, spore-A/spore-B), then between isolates and parts (spore-A/mycelium-B). High correlations were found between individual IgG and IgE ELISA values for all antigens using serum from Epicoccum skin-reactive patients. ELISA inhibition results suggested that significant cross-reactivity exists between Epicoccum and Alternaria antigens recognized by IgG but not by IgE. ELISA inhibition cross-reaction patterns among Epicoccum antigens were comparable to skin reactions while IgG patterns showed little variability. Further characterization of spore/mycelium and interstrain recognition patterns among different immunoglobulin isotypes will be necessary before complete standardization of extracts from different parts of fungi will be possible. The use of spore material for skin testing and treatment of Epicoccum sensitivity appears to be both premature and unnecessary at this time.

Antihypertensive effect of transplant of rat kidney or its unclipping. Hemodynamic effects and control mechanisms

The acute transplantation of a normal kidney into a recipient rat with Goldblatt one-kidney, one clip hypertension (1K1C) results in a blood pressure (BP) fall toward but not below normal levels within 1 hour. Removal of the clip in a 1K1C hypertensive rat also normalizes the BP rapidly. These changes are not mediated by external fluid loss and occur after indomethacin pretreatment, but are associated with a fall in cardiac output. The mechanism of release of a depressor secretion from the kidney transplant appears to be under barostatic control. Thus, transplanting a kidney into a hypertensive recipient caused a prompt BP decline, whereas transplanting an SHR kidney into a hypertensive recipient did not lower the BP. The prompt BP fall seen after unclipping also indicates that abrupt exposure of the kidney to a high perfusion pressure initiates the release of some depressor agent. When the recipient rat was made hypertensive by injecting renin, the kidney transplant did not lower the BP. When angiotensin in subpressor dose was infused into the renal artery of the kidney transplant, the BP of the recipient did not fall, whereas infusion of norepinephrine in equiconstrictor doses did not prevent the depressor response. These experiments suggest that, in addition to a barostatic stimulus for depressor release, angiotensin acts as a specific inhibitor.

Vagotomy for peptic oesophageal stricture

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Duodenal reflux and pyloric surgery

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Selective proximal vagotomy

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Recurrent ulceration after vagotomy and drainage with electrical stimulation test, 1957-69

Between 1957 and 1969 700 patients with duodenal ulceration were treated by selective vagotomy and simple drainage using the electrical stimulation test to achieve complete nerve section. Ten of these patients have been re-admitted to the hospital with further ulceration, one with a lesser curve gastric ulcer and nine with recurrent duodenal disease. The first patient had gastric retention and has apparently been cured by gastrojejunostomy to improve antral drainage. The remaining nine cases were found to have incomplete nerve section, and, of these, seven have been treated and apparently cured by completion of the incomplete vagotomy, again using the electrical stimulation test.

Four-year to eight-year results of vagotomy and simple drainage for benign lesser curve gastric ulcer

The results of vagotomy and simple drainage for recurrent benign lesser curve gastric ulcer are recorded. Seventy-two consecutive cases were treated from 1962 to 1965. The follow-up is therefore from five to eight years. In only two cases did the ulcer fail to heal and remain healed. Four years after operation both these had persistent ulceration and persistent gastric retention. Both have apparently been cured by gastrojejunostomy done to improve gastric drainage.

Selective vagotomy without drainage for gastric ulcer

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Selective vagotomy without drainage. An interim report

The results of surgical treatment for duodenal ulcer were compared in two groups of patients-51 who had undergone selective vagotomy without drainage and 17 who had had selective vagotomy and pyloroplasty. It is suggested that in the absence of organic pyloric or duodenal stenosis the former method seems both preferable and desirable, since postoperativley dumping does not occur and there is a steady improvement in gastric emptying.

Present position of the electrical stimulation test

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Bilateral selective vagotomy in prevention of post-vagotomy diarrhoea

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The aetiology of benign lesser curve gastric ulcer: vagotomy and pyloroplasty in its treatment

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