Bo Segerstedt

Pulmonary Epithelial Integrity in Children: Relationship to Ambient Ozone Exposure and Swimming Pool Attendance

Airway irritants such as ozone are known to impair lung function and induce airway inflammation. Clara cell protein (CC16) is a small anti-inflammatory protein secreted by the nonciliated bronchiolar Clara cells. CC16 in serum has been proposed as a noninvasive and sensitive marker of lung epithelial injury. In this study, we used lung function and serum CC16 concentration to examine the pulmonary responses to ambient O3 exposure and swimming pool attendance. The measurements were made on 57 children 10–11 years of age before and after outdoor exercise for 2 hr. Individual O3 exposure was estimated as the total exposure dose between 0700 hr until the second blood sample was obtained (mean O3 concentration/m3 × hours). The maximal 1-hr value was 118 μg/m3 (59 ppb), and the individual exposure dose ranged between 352 and 914 μg/m3hr. These O3 levels did not cause any significant changes in mean serum CC16 concentrations before or after outdoor exercise, nor was any decrease in lung function detected. However, children who regularly visited chlorinated indoor swimming pools had significantly lower CC16 levels in serum than did nonswimming children both before and after exercise (respectively, 57 ± 2.4 and 53 ± 1.7 μg/L vs. 8.2 ± 2.8 and 8.0 ± 2.6 μg/L; p < 0.002). These results indicate that repeated exposure to chlorination by-products in the air of indoor swimming pools has adverse effects on the Clara cell function in children. A possible relation between such damage to Clara cells and pulmonary morbidity (e.g., asthma) should be further investigated.

On ordinary ridge regression in generalized linear models

In this paper it is shown that an ill-conditioned data matrix has similar effects on the parameter estimator when estimating generalized linear models as when estimating linear regression models. A ...

Daily air pollution levels and acute asthma in southern Sweden

This study aimed to investigate the association between daily air pollution levels and the occurrence of acute respiratory signs and symptoms among people with asthma or asthma-like problems. Thirty eight subjects in the southern Swedish city of Landskrona kept a daily diary for 10 weeks. The daily prevalence of symptoms, supplementary bronchodilator use and peak flow deviations were compared with measurements of environmental nitrogen dioxide (NO2), sulphur dioxide, temperature and humidity in the city. The occurrence of severe asthma, both during the day and during the evening, was significantly positively associated with the concurrent 24 h average concentration of NO2, which never exceeded 72 microg x m(-3). A correlation of borderline significance was found between the use of on-demand medication and the NO2 level. However, peak flow deviations were not associated with air pollution or weather conditions, which may be explained by the beneficial effect of bronchodilators used by 28 of the subjects. The results of this study confirm those of some earlier studies and suggest that aggravation of asthma is related to daily variations in air quality, as indicated by relatively low ambient concentrations of nitrogen dioxide. These results also indicate that it may be appropriate to examine severe asthma symptoms separately.

On the conditioning problem in generalized linear models

When weights are assigned to a data matrix, as in the iterative least squares estimator of a generalized linear model, the condition of the data matrix is changed. In this paper a geometrical appro ...

Effects of contrast media on renal graft function and survival after cerebral angiography of cadaveric donors

The effects of intravascularly administered ionic contrast media on renal graft function and survival were retrospectively evaluated in 211 recipients of cadaveric renal transplants. The renal grafts were explanted from the donors within 24 hours (mean 16 hours) after cerebral angiography. There were no differences in renal function or graft survival between those exposed and those not exposed to contrast media before nephrectomy.

Health Effects from Road Dust

TAB3-PD-12 Whether coarse particles dominating road dust influence health or not is a question in the matter of measures of priority (remedial measures), among others. Within this project, we inves ...

Short-Term Effects of Air Pollution on Daily Emergency Visits for Asthma and Copd At Hospitals in Stockholm

A large number of studies have analysed air pollution effects on hospital admissions for respiratory diseases. Not so many have dealt with effects on emergency room visits. We have studied the asso ...