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Biomedical subjects

D E Gardner

Publications and source records attributed to D E Gardner.

At least 73 records · Page 4Linked to original sources
PubMed1976

Time--dose response for nitrogen dioxide exposure in an infectivity model system.

The concentration of NO2 in polluted atmosphere is subject to wide variation, according to peak traffic load, industrial productivity, intensity of sunlight and meteorological conditions. Normally NO2 has a low basal concentration with superimposed spikes when the above conditions are optimal for its production. Thus, it is important to determine the relative importance of a short-term, relatively high concentration of NO2 versus exposure for longer periods of minimal dose levels. This problem was approached experimentally by measuring the effect of NO2 on an animal's resistance to the induction of bacterial pneumonia. The data collected indicate that: (1) in short-term dose-response studies using the same Ct (concentration x time) product of 7, the actual concentration exerts a greater influence on NO2 effect than does the duration of exposure; (2) when concentration is held constant and the time increased, the average difference in mortality from controls can be seen after only 1 hr exposure to 3.5 ppm and after 3 weeks of exposure to 0.5 ppm; and (3) the relative mean survival time at 3.5 ppm for 1 hr was 18--36 hr less than that of the control animals.

Animals↗
PubMed1975

Effect of trace metals on phagocytosis by alveolar macrophages.

Experiments were performed to measure the effect of trace metals on a vital function of the alveolar macrophage (AM), phagocytosis. Since certain trace metals were found to reduce the viability of AMs, a technique was developed to permit examination of live cells only for phagocytosis. Evidence is presented that Ni(2+) selectively altered the phagocytic activity of AMs at concentrations lower than those which caused cell death. It is further shown that a level of VO(3) (-) that caused extensive lysis and death did not reduce phagocytosis in surviving cells. The effects of Cd(2+), Cr(3+), and Mn(2+) on AMs were also examined.

Animals↗
PubMed1975

Effect of nickel chloride on primary antibody production in the spleen.

Mice immunized intraperitoneally with sheep erythrocytes were treated with nickel chloride, a common particulate air pollutant. Primary antibody production in the spleen was examined using a hemolytic plaque technique. A negative linear dose-response relationship (p is less than 0.05) was observed between the logarithm of (plaques/10(6) cells) and the nickel concentration administered. Mice injected with 3.09 mug Ni2+/g body weight displayed lymphocyte function similar to that of control mice. However, injection of 9.26-12.34 mug Ni2+/g caused significant immunosupression (p is less than 0.05).

Animals↗
PubMed1975

Motorized exercise wheel for exposure of small animals to environmental pollutants.

For environmental inhalation studies a motorized exercise wheel was designed for small laboratory animals. Mice or hamsters were separated in individual enclosures, and each animal was required to perform the same exercise. The wheel was driven by a common barbecue spit motor, the speed of which may be varied by a standard variable transformer, from 1-6 revolutions per min. This unit can be adapted for a variety of laboratory applications.

Animals↗
PubMed1973

Technique for differentiating particles that are cell-associated or ingested by macrophages.

Phagocytosis is a two-step process involving attachment and ingestion of particulate material. It is often difficult to determine under a light microscope whether the particles are actually ingested or are merely attached to the cell. A more accurate, easy to perform technique with the use of xylene has been developed for determining the difference between the attachment and ingestion of polystyrene latex spheres. The xylene treatment dissolves the extracellular spheres, leaving only the intracellular spheres to be counted by the experimenter to obtain a more accurate phagocytic index. This technique also allows an investigator to get an ingestion index, an attachment index, or both.

Animals↗