Yulia Iossifova

House dust (1-3)-β-D-glucan and wheezing in infants

Background:  (1–3)‐β‐d‐glucan is a fungal cell wall component, suspected to cause respiratory symptoms in adults. However, very little is known on the possible health effects of (1–3)‐β‐d‐glucan during infancy. We examined the association between (1–3)‐β‐d‐glucan exposure and the prevalence of allergen sensitization and wheezing during the first year of life in a birth cohort of 574 infants born to atopic parents. Endotoxin exposure was included as a possible confounder.

Mold exposure during infancy as a predictor of potential asthma development

BACKGROUND Exposure to mold has been associated with exacerbation of asthma symptoms in children. OBJECTIVE To report how the presence of visible mold and exposure to (1-3)-beta-D-glucan in infancy affects the risk of asthma at the age of 3 years as defined by an Asthma Predictive Index (API). METHODS Visible mold was evaluated by means of home inspection. (1-3)-beta-D-glucan levels were measured in settled dust. Children were considered to be at high risk for asthma at later ages if they reported recurrent wheezing at the age of 3 years and met at least 1 of 3 major or 2 of 3 minor API criteria. RESULTS Children aged 3 years with high visible mold in the home during infancy were 7 times more likely to have a positive API than were those with no visible mold (adjusted odds ratio [aOR], 7.1; 95% confidence interval [CI], 2.2-12.6). In contrast, at low (1-3)-beta-D-glucan levels (< 22 microg/g), children were at increased risk of a positive API (aOR, 3.4; 95% CI, 0.5-23.5), whereas those with high (1-3)-beta-D-glucan levels (> 133 microg/g) were at decreased risk (aOR, 0.6; 95% CI, 0.2-1.6). Of the other covariates, mothers smoking was the strongest significant risk factor for the future development of asthma based on a positive API (aOR, 4.4; 95% CI, 1.7-11.6). CONCLUSIONS The presence of high visible mold and mothers smoking during infancy were the strongest risk factors for a positive API at the age of 3 years, suggesting an increased risk of asthma. High (1-3)-beta-D-glucan exposure seems to have an opposite effect on API than does visible mold.

Relative moldiness index as predictor of childhood respiratory illness.

The results of a traditional visual mold inspection were compared to a mold evaluation based on the Relative Moldiness Index (RMI). The RMI is calculated from mold-specific quantitative PCR (MSQPCR) measurements of the concentration of 36 species of molds in floor dust samples. These two prospective mold evaluations were used to classify the mold condition in 271 homes of infants. Later, the development of respiratory illness was measured in the infants living in these homes and the predictive value of each classification system was evaluated.The binary classification of homes as either moldy or non-moldy by on-site visual home inspection was not predictive of the development of respiratory illness (wheeze and/or rhinitis) (P=0.27). Conversely, a method developed and validated in this paper, using the RMI index fit to a logistic function, can be used to predict the occurrence of illness in homes and allows stake-holders the choice among various levels of risk.

Exposure Matrices of Endotoxin, (1→3)-Β-D-Glucan, Fungi, and Dust Mite Allergens in Flood-Affected Homes Of New Orleans

This study examined: (i) biocontaminant levels in flooded homes of New Orleans two years after the flooding; (ii) seasonal changes in biocontaminant levels, and (iii) correlations between biocontaminant levels obtained by different environmental monitoring methods. Endotoxin, (1→3)-β-d-glucan, fungal spores, and dust mite allergens were measured in 35 homes during summer and winter. A combination of dust sampling, aerosolization-based microbial source assessment, and long-term inhalable bioaerosol sampling aided in understanding exposure matrices. On average, endotoxin found in the aerosolized fraction accounted for <2% of that measured in the floor dust, suggesting that vacuuming could overestimate inhalation exposures. In contrast, the (1→3)-β-d-glucan levels in the floor dust and aerosolized fractions were mostly comparable, and 25% of the homes showed aerosolizable levels even higher than the dust-borne levels. The seasonal patterns for endotoxin in dust and the aerosolizable fraction were different from those found for (1→3)-β-d-glucan, reflecting the temperature and humidity effects on bacterial and fungal contamination. While the concentration of airborne endotoxin followed the same seasonal trend as endotoxin aerosolized from surfaces, no significant seasonal difference was identified for the concentrations of airborne (1→3)-β-d-glucan and fungal spores. This was attributed to the difference in the particle size; smaller endotoxin-containing particles can remain airborne for longer time than larger fungal spores or (1→3)-β-d-glucan-containing particles. It is also possible that fungal aerosolization in home environments did not reach its full potential. Detectable dust mite allergens were found only in dust samples, and more commonly in occupied homes. Levels of endotoxin, (1→3)-β-d-glucan, and fungi in air had decreased during the two-year period following the flooding as compared to immediate measurements; however, the dust-borne endotoxin and (1→3)-β-d-glucan levels remained elevated. No conclusive correlations were found between the three environmental monitoring methods. The findings support the use of multiple methods when assessing exposure to microbial contaminants.

Effect of Gaseous Chlorine Dioxide on Indoor Microbial Contaminants

Abstract Traditional and modern techniques for bioaerosol enumeration were used to evaluate the relative efficiency of gaseous chlorine dioxide (ClO2) in reducing the indoor microbial contamination under field and laboratory conditions. The field study was performed in a highly microbially contaminated house, which had had an undetected roof leak for an extended period of time and exhibited large areas of visible microbial growth. Air concentrations of culturable fungi and bacteria, total fungi determined by microscopic count and polymerase chain reaction (PCR) assays, endotoxin, and (1→3)-β-D-glucan were determined before and after the house was tented and treated with ClO2. The laboratory study was designed to evaluate the efficiency of ClO2 treatment against known concentrations of spores of Aspergillus versicolor and Stachybotrys chartarum on filter paper (surrogate for surface treatment). These species are commonly found in damp indoor environments and were detected in the field study. Upon analysis of the environmental data from the treated house, it was found that the culturable bacteria and fungi as well as total count of fungi (as determined by microscopic count and PCR) were decreased at least 85% after the ClO2 application. However, microscopic analyses of tape samples collected from surfaces after treatment showed that the fungal structures were still present on surfaces. There was no statistically significant change in airborne endotoxin and (1→3)-β-D-glucan concentration in the field study. The laboratory study supported these results and showed a nonsignificant increase in the concentration of (1→3)-β-D-glucan after ClO2 treatment.

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.

A New Field-Compatible Methodology for the Collection and Analysis of Fungal Fragments

A field-compatible collection system was developed and tested for the collection and analysis of fungal fragments. The new collection system consists of two types of Sharp-Cut cyclone samplers (PM 2.5 and PM 1.0 ) and an after-filter. Fungal particles are collected into three size fractions: (1) spores ( > 2.5 μ m); (2) a fragment-spore mixture (1.0–2.5 μ m); and (3) submicrometer-sized fragments ( < 1.0 μ m). The system was laboratory-tested using polystyrene latex (PSL) particles and particulate matter aerosolized from sporulating Aspergillus versicolor and Stachybotrys chartarum cultures. In addition to the particle count measured with direct-reading instruments, the (1 → 3)- β -D-glucan content in each size fraction was determined with the Limulus Amebocyte Lysate (LAL) assay. Experiments conducted with PSL particles showed that the 50% cut-off values of the two cyclone samplers under the test conditions were 2.25 μ m and 1.05 μ m, respectively. No particle bounce onto the after-filter was observed when the total particle number entering the collection system was kept below 1.6 × 10 8 . The (1 → 3)- β -D-glucan assay of samples aerosolized from both fungal species suggested that surface area is an important factor for determining the (1 → 3)- β -D-glucan content in the entire size-range of particles. In conclusion, the new methodology is a promising tool for separating and analyzing fungal fragment samples.

Effectiveness of controlled workplace interventions in reducing lower back disorders

Background: Researchers have conducted interventions, based on several different risk factors, designed to minimize the prevalence or incidence of lower back disorders in different occupational settings. However, results have been inconsistent for the observed effectiveness of the intervention methods. Objectives: To assess the effectiveness of controlled workplace interventions in preventing the (re)occurrence of lower back disorders (LBDs) in a manufacturing setting. Methods: An electronic and manual literature search was conducted. The methodological quality of the studies was assessed on five categories and a meta-analysis was performed to identify the direction and size of the effect. Because the studies were homogeneous (Q = 0.63), the meta-OR was calculated using the fixed-effect model. Results: The literature survey identified four studies that met the inclusion criteria. These studies possessed a marginal to moderate methodological quality (mean quality score 0.78 of 2.0, SD = 0.22). The meta-OR revealed a statistically insignificant reduction in work-related LBD prevalence (meta-OR = 0.77; 90% CI 0.55–1.07). Conclusions: Due to the statistical insignificance of the meta-OR and the relatively low methodological quality of studies, no definite conclusions can be drawn. More rigorous research with high quality standards is required.