Glutathione-S-transferase P1, early exposure to mould in relation to respiratory and allergic health outcomes in children from six birth cohorts. A meta-analysis.

BACKGROUND: There are conflicting study results regarding the association of exposure to visible mould and fungal components in house dust with respiratory and allergic diseases in children. It has been suggested that functional polymorphisms of the GSTP1 gene may influence the risk for allergic disorders through an impaired defence against oxidant injury. METHODS: We examined in six birth cohorts of over 14 000 children whether the association between early exposure to reported mould at home in relation to respiratory and allergic diseases is modified by a single nucleotide polymorphism of the GSTP1 gene. RESULTS: We observed a positive association of mould exposure with nasal symptoms (2-10 year) aOR: 1.19 (1.02-11.38). Further, there was a borderline significant increased risk of rhinoconjunctivitis (6-8 year) in children homozygous for the minor allele Val/Val, aOR: 1.25 (0.98-1.60). In stratified analyses, subjects homozygous for the minor allele and exposed to mould at home were at increased risk for early wheezing aOR: 1.34 (1.03-1.75), whereas the major allele may confer susceptibility for later nasal outcomes, (6-8 year) aOR: 1.20 (1.00-1.45) and (2-10 year) aOR: 1.30 (1.04-1.61), respectively. For none of the health outcomes studied, we found gene by environment interactions. CONCLUSION: A genetic influence of the GSTP1 gene cannot be ruled out, but the magnitude of the effect is a matter of further research. In conclusion, the interplay between gene and environments is complex and remains subject of further study.

Intense hypoxic cycle exercise does not alter lung density in competitive male cyclists.

We tested the hypothesis that intense short duration hypoxic exercise would result in an increase in extravascular lung water (EVLW), as evidenced by an increase in lung density. Using computed tomography (CT), baseline lung density was obtained in eight highly trained male cyclists (mean +/- SD: age = 28 +/- 8 years; height = 180 +/- 9 cm; mass = 71.6 +/- 8.2 kg; VO2max= 65.0 +/- 5.2 ml kg min(-1)). Subjects then completed an intense hypoxic exercise challenge on a cycle ergometer and metabolic data, HR and %S(p)O2 were recorded throughout. While breathing 15% O2, subjects performed five 3 km cycling intervals (mean power, 286 +/- 20 W; HR = 91 +/- 4% HRmax) separated by 5 min of recovery. From a resting hypoxic S(p)O2 of 92 +/- 4%, subjects further desaturated during exercise to 76 +/- 3%. CT scans were repeated 76 +/- 10 min (range 63-88 min) following the completion of exercise. There was no change in lung density from pre (0.18 +/- 0.02 g ml(-1)) to post-exercise (0.18 +/- 0.04 g ml(-1)). The substantial reduction in S(p)O2 may be explained by a number of potential mechanisms, including decreased pulmonary diffusion capacity, alveolar hypoventilation, reduced red cell transit time, ventilation/perfusion inequality or a temperature and pH induced rightward-shift in the oxyhaemoglobin dissociation curve. Alternatively, the integrity of the blood gas barrier may have been disrupted without any measurable increase in lung density.

The effect of temperature on swimming performance and oxygen consumption in adult sockeye (Oncorhynchus nerka) and coho (O. kisutch) salmon stocks.

Our knowledge of the swimming capabilities and metabolic rates of adult salmon, and particularly the influence of temperature on them, is extremely limited, and yet this information is critical to understanding the remarkable upstream migrations that these fish can make. To remedy this situation, we examined the effects of temperature on swimming performance and metabolic rates of 107 adult fish taken from three stocks of sockeye salmon Oncorhynchus nerka and one stock of coho salmon O. kisutch at various field and laboratory locations, using large, portable, swim tunnels. The salmon stocks were selected because of differences in their ambient water temperature (ranging from 5 degrees C to 20 degrees C) and the total distance of their in-river migrations (ranging from approximately 100 km for coastal stocks to approximately 1100 km for interior stocks). As anticipated, differences in routine metabolic rate observed among salmon stocks were largely explained by an exponential dependence on ambient water temperature. However, the relationship between water temperature and maximum oxygen consumption (MO2max), i.e. the MO2 measured at the critical swimming speed (Ucrit), revealed temperature optima for MO2max that were stock-specific. These temperature optima were very similar to the average ambient water temperatures for the natal stream of a given stock. Furthermore, at a comparable water temperature, the salmon stocks that experienced a long and energetically costly in-river migration were characterized by a higher MO2max, a higher scope for activity, a higher Ucrit and, in some cases, a higher cost of transport, relative to the coastal salmon stocks that experience a short in-river migration. We conclude that high-caliber respirometry can be performed in a field setting and that stock-specific differences in swimming performance of adult salmon may be important for understanding upstream migration energetics and abilities.