nitrogen-dioxide and Streptococcal-Infections

The nitrogen dioxide (NO2) diurnal cycle found in urban communities usually consists of a low basal concentration upon which are superimposed higher concentration peaks or spikes of short duration. Various components of this environmental exposure mode were examined to assess effects of urban exposure profiles on susceptibility to infectious pulmonary disease. Mice were exposed to NO2 peaks of 4.5 ppm for 1, 3.5, or 7 h, challenged with Streptococcus sp. either immediately or 18 h postexposure, and then observed for mortality. When the streptococcal challenges were immediately after NO2 exposure, the mortality rate was directly related to the length of peak exposure, whether or not a basal exposure was used, and all peak lengths significantly increased mortality. When the challenge was delayed for 18 h after the peak exposure, spiked exposures of 3.5 and 7 h increased mortality to the same degree. If a 1-h peak exposure to 4.5 ppm was superimposed twice daily upon a continuous basal NO2 concentration of 1.5 ppm, there was a suggestive trend toward increased mortality near the end of the second week of exposure when challenge occurred immediately after the morning spike. Studies were also conducted to examine interactions with ozone (O3) and NO2, since urban air typically contains both of these oxidants. Using various combinations of basal and spiked exposure levels of NO2 and O3, synergistic results were obtained for streptococcal-induced mortality.

Topics: Air Pollutants; Animals; Disease Models, Animal; Disease Susceptibility; Female; Humans; Mice; Nitrogen Dioxide; Ozone; Streptococcal Infections; Urban Population

A mechanized wheel was constructed for use in evaluating the interaction of exercise and gaseous pollutants such as O3 and NO2. Immediately after the pollutant exposure, both exercised and nonexercised female mice (CD-1) were combined with controls, challenged with an aerosol of viable Streptococcus pyogenes (group C), and then observed over a 15-d period for incidence of mortality. Exposure to O3 at 196 micrograms/m3 (0.1 ppm) or 590 micrograms/m3 (0.3 ppm) while exercising yielded mortality rates that were significantly higher than those observed in the O3 groups that were not exercised. With exposure to NO2 at 5640 micrograms/m3 (3 ppm), exercise produced a significant enhancement in mortality over the other treatment groups. These studies show that exercise can affect the mortality observed in this model system and indicate the need for establishing safe exposure levels of pollutants as a function of the activity level of the exposed population.

Topics: Air Pollutants; Animals; Female; Mice; Nitrogen Dioxide; Ozone; Physical Exertion; Streptococcal Infections; Streptococcus pyogenes

Exposures to various mixtures of nitrogen dioxide (NO2) and ozone (O3) reduced the resistance of mice to streptococcal pneumonia as evidenced by increased mortality rates and shortened survival time. Daily 3-h exposures (5 d/wk) for 2--6 mo to an air pollutant mixture consisting of 940 microgram/m3 (0.5 ppm) NO2 and 196 microgram/m3 (0.1 ppm) O3 were most effective in reducing the resistance to infection. The decrease in resistance to the infection occurred sooner than the mice continued to be exposed to the air pollutants instead of clean air for 14 d after the respiratory challenge with Streptococcus pyogenes aerosol. After 3 mo of exposure to the pollutant mixture, there was some decrease in the ability of mice to clear inhalated streptococci from their lungs. At the same time the total cell count in the fluid lavaged from the lungs of mice was markedly reduced, as were the viability and phagocytic activity of the alveolar macrophages. Exposure to the pollutants combined with challenge with Streptococcus aerosol resulted in marked morphological changes in lung tissues as seen by scanning electron microscopy.

Topics: Animals; Female; Lung; Mice; Nitrogen Dioxide; Ozone; Pneumonia; Streptococcal Infections; Streptococcus pyogenes; Time Factors

Topics: Animals; Female; Klebsiella Infections; Klebsiella pneumoniae; Lung; Mice; Mice, Inbred Strains; Nitrogen Dioxide; Ozone; Streptococcal Infections; Time Factors

Topics: Air Pollutants; Animals; Benzene; Central Nervous System; Chronaxy; Disease Models, Animal; Environment, Controlled; Environmental Exposure; Female; Leukocytes; Male; Mice; Nitrogen Dioxide; Rats; Streptococcal Infections; Sulfur Dioxide; Time Factors

Topics: Air Pollutants; Animals; Benzene; Chronaxy; Disease Models, Animal; Environment, Controlled; Environmental Exposure; Female; Leukocytes; Male; Mice; Nitrogen Dioxide; Rats; Streptococcal Infections; Time Factors