T. Reponen

Comparison of Two Analytical Methods for Detecting (1-3)- -D-Glucan in Pure Fungal Cultures and in Home Dust Samples

There are two methods available for the analysis of (1-3)- -D-glucan: the Limulus Amebocyte Lysate assay (LAL) and the inhibition Enzyme Immunoassay (EIA). The aim of this study was to compare the accuracy and specificity of these two methods in detecting eight alpha and beta-glucan standards, and their sensitivity for the analysis of (1-3)- - D-glucan content of common indoor fungal species and indoor dust samples. The results show that the LAL assay is more accurate, specific, and sensitive in measuring linear and branched  -D-glucans than the EIA. The greatest LAL-analyzed (1-3)-� -D-glucan content per spore (241 pg/spore) was found with E. nigrum, which also had the largest spore size (28 μm). The biomass-normalized (1-3)-� -D-glucan content of fungal spores from pure cultures was within similar range with the two assays but no correlation was found between the results from the two assays. In contrast, there was a significant correlation between the EIA and LAL-measured (1-3)-� -D-glucan concentrations (� g/m 2 of floor area) in field dust sam- ples.

Use of (1‐3)‐β‐d‐glucan concentrations in dust as a surrogate method for estimating specific fungal exposures

UNLABELLED Indoor exposure to fungi has been associated with respiratory symptoms,often attributed to their cell wall component, (1-3)-beta-D-glucan. Performing(1-3)-beta-D-glucan analysis is less time consuming and labor intensive than cultivation or microscopic counting of fungal spores. This has prompted many to use(1-3)-beta-D-glucan as a surrogate for fungal exposure. The aim of this study was to examine which indoor fungal species are major contributors to the (1-3)-beta-D-glucan concentration in field dust samples. We used the quantitative polymerase chain reaction (QPCR) method to analyze 36 indoor fungal species in 297 indoor dust samples. These samples were also simultaneously analyzed for (1-3)-beta-D-glucan concentration using the endpoint chromogenic Limulus Amebocyte lysate assay. Linear regression analysis, followed by factor analysis and structural equation modeling, were utilized in order to identify fungal species that mostly contribute to the (1-3)-beta-D-glucan concentration in field dust samples. The study revealed that Cladosporium and Aspergillus genera, as well as Epicoccum nigrum, Penicillium brevicompactum and Wallemia sebi were the most important contributors to the (1-3)-beta-D-glucan content of these home dust samples. The species that contributed most to the (1-3)-beta-D-glucan concentration were also the most prevalent in indoor environments. However, Alternaria alternata, a common fungal species in indoor dust, did not seem to be a significant source of (1-3)-beta-D-glucan. PRACTICAL IMPLICATIONS This study revealed that the (1-3)-beta-D-glucan content of different fungal species varies widely. (1-3)-beta-D-glucan inhouse dust from the Greater Cincinnati area may be a good marker for some fungal species of the Cladosporium and Aspergillus genera. In contrast, Alternaria alternata did not contribute much to the (1-3)-beta-D-glucan load. Therefore, (1-3)-beta-D-glucan concentration in field samples as a surrogate for total fungal exposure should be used with caution.

Optimum Predictors of Childhood Asthma: Persistent Wheeze or the Asthma Predictive Index?

BACKGROUND The Asthma Predictive Index (API) and persistent wheezing phenotypes are associated with childhood asthma, but previous studies have not assessed their ability to predict objectively confirmed asthma. OBJECTIVE To determine whether the University of Cincinnati API Index (ucAPI) and/or persistent wheezing at age 3 can accurately predict objectively confirmed asthma at age 7. METHODS Data from the Cincinnati Childhood Allergy and Air Pollution Study, a high-risk prospective birth cohort, was used. Asthma was defined as parent-reported or physician-diagnosed asthma objectively confirmed by a change in FEV1 of ≥12% after bronchodilator or a positive methacholine challenge (PC20 ≤ 4 mg/mL); or as prior treatment with daily asthma controller medication(s). Multivariate logistic regression was used to investigate the relationship between confirmed asthma at age 7 and a positive ucAPI (adapted and modified from prior published API definitions) and persistent wheezing at age 3. RESULTS At age 7, 103 of 589 children (17.5%) satisfied the criteria for asthma. Confirmed asthma at age 7 was significantly associated with a positive ucAPI (adjusted odds ratio [aOR] 13.3 [95% CI, 7.0-25.2]; P < .01) and the persistent wheezing phenotype (aOR 9.8 [95% CI, 4.9-19.5]; P < .01) at age 3. Allergic persistent wheezing was associated with a significantly higher risk of asthma (aOR 10.4 [95% CI, 4.1-26.0]; P < .01) than nonallergic persistent wheezing (aOR 5.4 [95% CI, 2.04-14.06]; P < .01). CONCLUSION Both a positive ucAPI and persistent wheeze at age 3 were associated with objectively confirmed asthma at age 7; however, the highest risk was associated with ucAPI. These results demonstrate the ucAPI as a clinically useful tool for predicting future asthma in school-age children.