Effects of low-dose X-irradiation on mouse-brain aggregation cultures

Biochemical and morphological differentiation in reaggregating mouse-brain cell cultures after low-dose radiation (0.5 Gy) in vitro was studied. Cells were irradiated on culture day 2, corresponding to embryonic day 15-16, and different glial and neuronal markers were followed through development to postnatal day 40. The shape and size of irradiated aggregates were more irregular and smaller compared with controls. Total amounts of DNA and protein were significantly lower in irradiated aggregates than in controls between days 8 and 20. After 30 days in culture activities of the glial markers glutamine synthetase (GS) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) were lower in X-irradiated aggregates than in controls. However, after 40 days the CNP activity in irradiated aggregates increased to levels above those of the controls. Irradiated and control aggregates did not differ significantly in neuronal marker enzyme activities, i.e. choline acetyltransferase (ChAT), acetylcholine esterase (AChE) and glutamic acid decarboxylase (GAD) measured on a per mg protein basis. On days 20 and 30 the amount of nerve growth factor (NGF) was two-fold higher in irradiated aggregates compared with non-irradiated ones, suggesting that, after irradiation, surviving cells in culture were induced to produce more NGF. After 40 days the amount of NGF in irradiated aggregates had decreased to the level found in the control aggregates

Exposure to Airborne Mould in School Environments and Nasal Patency in Children

Mould in schools has been associated with increased upper airway obstruction in adults. In this study, we investigated the relationship between school indoor mould spore exposure and nasal patency in children. Airborne mould samples were collected in 32 classrooms from 4 primary schools during both summer and winter using a single-stage Anderson sampler. Nasal patency was measured in 275 children in summer and 200 children in winter using acoustic rhinometry. Various mould species were isolated but the most common species found inside the classrooms were Alternaria, Aspergillus niger, Cladosporium spp. and Penicillium spp. In the univariate analyses, significant negative correlations were found between exposure to various mould species, particularly Alternaria, and rhinometric measures in the children. In multivariate analyses, exposure to Alternaria was associated with both decreased mean nasal cross-sectional area (p=0.001) and decreased nasal volume (p=0.026). Decreased nasal patency was also associated with exposure to A. niger (p=0.034) and Penicillium(p=0.043) in the classrooms. The findings of this study suggest that exposure to airborne mould, particularly Alternaria, in school environments may affect the upper airways of children

Reference values for acoustic rhinometry in children from 4 to 13 years old

BACKGROUND: Despite a growing number of studies using acoustic rhinometry (AR) in children, no reference material exists that incorporates the entire age and height interval of preschool children up to puberty for a range of rhinometric variables. The aim of this study is to provide a reference range for nasal volumes and minimum cross-sectional areas (MCAs) in healthy nondecongested children aged 4-13 years old. METHODS: Two hundred fifty-six primary school children (mean, 7.95 years; range, 3.8-13.1 years; 123 boys/133 girls) were measured by AR. Variables were MCA (first, second, and absolute minimum) and nasal volumes from 0 to 4 cm (Vol0-4), 0 to 5 cm (Vol0-5), 1 to 4 cm (Vol1-4), and 2 to 5 cm (Vol2-5) into the nasal cavity. Height and weight were measured and atopic status was determined by skin-prick test. Age and current and past respiratory health were recorded from a questionnaire. RESULTS: In multiple linear regression models height was the main predictor for all AR variables although weight also was a significant predictor of MCAs. There was no association between any AR variables with sex, atopy, or hay fever but children with current wheeze (within last 12 months) and asthma had decreased nasal patency. CONCLUSION: This article presents the most extensive current reference material for AR in nondecongested prepubescent healthy children. The presented reference material will facilitate the interpretation and evaluation of future and present epidemiologic studies based on AR in children