Suchergebnisse

The increasing use of alcohol as an alternative fuel to gasoline or diesel can increase emission of formaldehyde, an organic gas that is irritant to the mucous membranes. the respiratory system is the major target of air pollutants and its major defense mechanism depends on the continuous activity of the cilia and the resulting constant transportation of mucous secretion. the present study was designed to evaluate the effects of formaldehyde on the ciliated epithelium through a relative large dose range around the threshold limit value adopted by the Brazilian legislation, namely 1.6 ppm (1.25 to 5 ppm). for this pur pose, the isolated frog palate preparation was used as the target of toxic injury. Four groups of frog palates were exposed to diluted Ringer solution (control, N = 8) and formaldehyde diluted in Ringer solution at three different concentrations (1.25, 2.5 and 5.0 ppm, N = 10 for each group). Mucociliary clearance and ciliary beat frequency decreased significantly in contact with formaldehyde at the concentrations of 2.5 and 5.0 ppm after 60 min of exposure (P <0.05). We conclude that relatively low concentrations of formaldehyde, which is even below the Brazilian threshold limit value, are sufficient to cause short-term mucociliary impairment. ; USP, Fac Med, Dept Patol, Lab Poluicao Atmosfer Exptl, BR-01246903 São Paulo, Brazil ; USP, Fac Med, Disciplina Pneumol, Dept Cardiopneumol, BR-01246903 São Paulo, Brazil ; USP, Fac Med, Serv Clin Geral, Div Clin Med,Hosp Clin, BR-01246903 São Paulo, Brazil ; Universidade Federal de São Paulo, Programa Pos Grad Reabilitacao, São Paulo, Brazil ; Universidade Federal de São Paulo, Programa Pos Grad Reabilitacao, São Paulo, Brazil ; Web of Science

Thermal stress has a negative effect on the cognitive performance of military personnel and industry workers exposed to extreme environments. However, no studies have investigated the effects of environmental thermal stress on the cognitive functions of older adults. We carried out a controlled trial with 68 healthy older adults (mean age 73.3 years, 69 % female), each of whom has been assessed twice on the same day with selected tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Repeated sessions were conducted with air temperatures set at 24 °C and 32 °C in a balanced order. Our primary analyses did not show significant differences when comparing the cognitive performance of the total sample under the two experimental temperatures. However, interaction analysis has shown that humidity levels modify the effect of temperature on cognitive outcomes. The subgroup exposed to relative humidity greater than the median value (57.8 %) presented worse cognitive performance in the heat session when compared to the control session. Reported exercising frequency explained individual vulnerability to heat stress. Volunteers with lower levels of physical activity (<4 times per week) were more likely to present worsened cognitive performance under heat stress. In a fully adjusted linear regression model, the performance under heat stress remained associated with relative humidity (β = −0.21; p = 0.007) and frequency of exercising (β = 0.18; p = 0.020). Our results indicate that heat stress may have detrimental effects on the cognitive functioning of some subgroups of older adults and under particular circumstances. Further research is needed for exploring a variety of potentially influential factors.