Pine dust, atopy and lung function: A cross-sectional study in sawmill workers.

An increased risk of asthma symptoms has previously been shown in 772 pine sawmill workers. The aim of the current study was to assess the association between dust exposure, lung function and atopy. Subjects with (n = 59) and without (n = 167) asthma symptoms were randomly selected from the previous survey. Lung function and atopy were determined using spirometry and skin-prick tests, respectively. Inhalable dust levels were measured on the same day. The geometric mean dust concentration was 0.52 mg x m(-3). Exposure to dry but not to green dust was associated with asthma symptoms. Green dust was associated with atopic sensitisation, particularly against outdoor allergens; no association was found for dry dust. Forced vital capacity, forced expiratory volume in one second and peak expiratory flow were significantly lower in workers exposed to high levels of green dust (-350 mL, -260 mL and -860 mL x s(-1), respectively) and dry dust (-230 mL, -190 mL and -850 mL x s(-1), respectively). These associations were observed both in subjects with and without asthma symptoms. No associations with cross-shift changes in lung function were found. Exposure to green pine sawdust may be a risk factor for atopy. Both green and dry dust were associated with obstructive as well as restrictive pulmonary effects.

Pollen counts in relation to the prevalence of allergic rhinoconjunctivitis, asthma and atopic eczema in the International Study of Asthma and Allergies in Childhood (ISAAC).

BACKGROUND: Although pollens are major allergens associated with allergic rhinoconjunctivitis and asthma, there is little information about the relative prevalence of these conditions in populations with different pollen exposures. OBJECTIVE: The purpose of this study was to investigate the relationship between pollen exposure and allergic symptoms among children in different countries. METHODS: An ecological analysis was conducted to see whether pollen exposure (pollen counts, and duration and severity of pollen seasons) is associated with symptoms of allergic rhinoconjunctivitis, asthma and atopic eczema in 28 centres within 11 countries (nine being in Europe). Data on the prevalence of symptoms in 13-14-year olds were based on the responses to the written questionnaires from the International Study of Asthma and Allergies in Childhood (ISAAC). The analysis was adjusted for gross national product and mean annual relative humidity. RESULTS: There was little relationship between pollen exposure and symptom prevalence, except for a significant inverse association between grass pollen counts and lifetime prevalence of the symptoms of allergic rhinitis (P=0.03). Almost all the regression coefficients were negative. The associations were even weaker and all non-significant when the analyses were conducted within countries, using a random intercept fixed slope model, but there was still no evidence of a positive association between pollen exposure and symptoms. CONCLUSION: There is a weak but consistent tendency for the prevalence of allergic symptoms to be inversely associated with pollen exposure. This finding accords with evidence from several countries, suggesting that the prevalence of hayfever and asthma tends to be lower in rural than in urban areas, and lowest among people living on farms. Exposure to allergenic pollen in early life does not appear to increase the risk of acquiring symptoms of respiratory allergy, and may even give some protection against them.

Antibiotic use in early childhood and the development of asthma.

BACKGROUND AND OBJECTIVE: Recent investigations have focused on the role of infections in infancy in promoting or protecting against the subsequent development of asthma. A related hypothesis concerns the possible role of medical responses to infections, including the widespread use of antibiotics. We chose children at Rudolf Steiner schools to test this latter hypothesis because a significant proportion of parents rejects the use of conventional treatments, including antibiotics. METHODS: Seventy-five per cent (n = 456) of parents of children aged 5-10 years attending Rudolf Steiner schools throughout New Zealand completed questionnaires which included questions on the use of antibiotics and a history of asthma and wheeze in their children. RESULTS: After controlling for potential confounders, antibiotic use was significantly associated with having a history of asthma (OR = 2.74, 95% CI: 1.10-6.85) or wheeze (OR = 1. 86, 95% CI: 1.06-3.26) but not with current wheeze (OR = 1.08, 95% CI: 0.54-2-16). The adjusted odds ratio for asthma was 4.05 (95% CI: 1.55-10.59) if antibiotics were used in the first year of life and 1. 64 (95% CI: 0.60-4.46) if antibiotics had been used only after the first year of life when compared with children who had never used antibiotics. The number of courses of antibiotics during the first year of life was also associated with increased odds ratios for asthma: 2.27 (95% CI: 1.14-4.51) for one to two courses and 4.02 (95% CI: 1.57-10.31) for three or more courses when compared with no antibiotic use in the first year of life. Although not significant, the association of antibiotics and hay fever (OR = 1.99 [95% CI: 0. 93-4.26]) was of a similar strength to the association of antibiotics with a history of wheeze. Antibiotics were not significantly associated with eczema (OR = 1.23 [95% CI: 0.71-2.13]). CONCLUSION: Antibiotic use in infancy may be associated with an increased risk of developing asthma. Further study is required to determine the reasons for this association.

Apolipoprotein E*3-Leiden transgenic mice as a test model for hypolipidaemic drugs.

Apolipoprotein (APO) E*3-Leiden mice with impaired chylomicron and VLDL (very low density lipoprotein) remnant metabolism display hyperlipidaemia and atherosclerosis. In the present study, these mice were used for testing the hypolipidaemic effect of two marketed agents, lovastatin (CAS 75330-75-5) and gemfibrozil (CAS 25812-30-0) as well as a novel compound, SB 204990 (the 5-ring lactone of +/-(3R*,5S*) 3-carboxy-11-(2,4-dichlorophenyl)-3,5-dihydroxyundecanoic acid, CAS 154566-12-8), a potent inhibitor of cholesterol and fatty acid synthesis at the level of ATP-citrate lyase. APOE*3-Leiden mice were fed a saturated fat and cholesterol-rich diet supplemented with either 0.05 or 0.1% w/w of lovastatin, 0.1 or 0.2% w/w of gemfibrozil or 0.1 or 0.2% w/w of SB 204990. Lovastatin showed a dose-related decrease in plasma cholesterol levels (up to -20%) due to a lowering of LDL and HDL (low density resp. high density lipoprotein)-cholesterol (-20 and -18%, respectively), while plasma triglyceride levels were unaffected. Gemfibrozil had no effect on plasma total cholesterol levels but gave significant dose-dependent decreases in plasma (VLDL) triglyceride levels (up to -53%). SB 204990 resulted in a dose-dependent reduction of plasma cholesterol (up to -29%) by lowering VLDL, LDL and HDL-cholesterol (-50, -20 and -20%, respectively). In addition, a strong dose dependent reduction of plasma (VLDL) triglycerides up to -43% was observed with this compound. Although the effects of gemfibrozil and SB 204990 were not simply explained by changes in a single determinant of VLDL metabolism--no effects of these drugs were seen on post-heparin plasma lipoprotein lipase activity, in vivo rate of VLDL synthesis or hepatic apoC-III mRNA levels--APOE*3-Leiden mice were found to give robust hypolipidaemic responses to these test compounds. The responsiveness to hypolipidaemic therapy combined with a clear relationship between aortic lesion size and plasma cholesterol exposure, as demonstrated previously, makes this mouse an attractive model for the testing of anti-atherosclerotic properties of hypolipidaemic drugs.

Risk factors for asthma symptoms in Kawerau children.

AIMS: To study risk factors for asthma prevalence in Kawerau children aged 8-13 years. METHODS: Questionnaires on asthma symptoms and risk factors were completed in 1992 by parents of 708 Kawerau schoolchildren aged 8-13 years, a response rate of 82.0%; for a subgroup of children, stored serum samples from a 1984 survey were also analysed. RESULTS: The overall prevalence of current wheeze (21.3%) was similar to that observed in other New Zealand surveys. The prevalence of current wheeze was elevated in males (odds ratio (OR) = 1.7, 95% CI 1.2-2.5), in those who had been passively exposed to cigarette smoke from the primary caregiver (OR = 1.4, 95% CI 1.0-2.1), in those who had had pets in the home at age 0-5 years (OR = 1.9, 95% CI 1.2-2.9) and in those with one or more birth parents with asthma (OR = 2.1, 95% CI 1.4-3.1); current wheeze was less common in those with older children living in the same household (for 2 or more older children in the same household, OR = 0.5, 95% CI 0.2-1.0). In a small nested case-control study it was found that current wheeze was more common in those with high levels of IgE (OR = 6.4, 95% CI 1.3-36.4) or low levels of selenium (OR = 3.1, 95% CI 0.9-11.8) in stored serum collected 8 years previously. There was no difference in the proportions with current wheeze, or with diagnosed asthma between Maori and European children, but Maori children were more likely to have current frequent nocturnal wheeze (OR = 2.2, 95% CI 1.0-5.1), current severe wheeze (OR = 1.8, 95% CI 0.8-3.7) or to have been admitted to hospital with asthma (OR = 2.4, 95% CI 1.2-4.8). Passive exposure to tobacco smoke was more common among Maori children, but this only partially accounted for the greater asthma severity in Maori children, and the lower prescribing of prophylactic medications in this group may also have contributed. CONCLUSIONS: Multiple factors were associated with asthma symptoms in children in this age-group, including a family history of asthma, male gender, environmental tobacco smoke, environmental allergen exposure, atopy, and low selenium status. Further studies are required to assess the relative contributions of these factors to the prevalence of asthma in New Zealand.

Reduced selenium in asthmatic subjects in New Zealand.

Selenium is an essential component of glutathione peroxidase, an enzyme that helps protect cells against oxidation damage and modulates the lipoxygenase pathway of arachidonic acid metabolism. Low selenium concentrations might therefore influence the inflammatory process in asthma by reducing the activity of glutathione peroxidase. Whole blood and plasma selenium concentrations and glutathione peroxidase activity have been measured in 56 asthmatic patients and 59 non-asthmatic control subjects in New Zealand, a country with a low dietary selenium intake and a high prevalence of asthma. When compared with control subjects the asthmatic patients had lower values for whole blood selenium concentrations (-4.9, 95% confidence interval -10.2 to 0.4 ng/ml) and glutathione peroxidase activity (-3.3, 95% CI -5.8 to -0.8 units/g Hb). There was a 1.9 and 5.8 fold increased risk of asthma in subjects with the lowest range of whole blood selenium concentration and glutathione peroxidase activity respectively (95% CI 0.6 to 5.6 and 1.6 to 21.2). Levels were lower in patients and control subjects without an atopic predisposition, but were not affected by prednisone use. Similar differences between the asthmatic and control subjects were not observed for selenium concentration or glutathione peroxidase activity measured in plasma, which reflects short term rather than long term selenium content. These findings are consistent with the hypothesis that low selenium concentrations may have a role in the pathogenesis of asthma in New Zealand.