Biomedical subjects
Publications and source records attributed to J D Hatcher.
Dust samples were collected inside high-capacity cotton gins with the personal, stationary personal, and the vertical elutriator cotton dust samplers. Dust particles collected on the filters were sized with a particle measurement computer system. Particle-distribution data revealed that gin dust contains a high percentage of dust particles larger than 20 micrometers in diameter.
In cats anesthetized with alpha-chloralose, the activities of aortic and carotid chemoreceptor nerves were measured during a control period and during anemia where the hematocrit was lowered in steps by dextran-for-blood exchange. With anemia there was a sustained nonlinear increase in firing of aortic chemoreceptors. There was a greater firing of aortic chemoreceptors for a given lowering of hematocrit from an initial low blood hematocrit than for a similar decrease in hematocrit from an initial high blood hematocrit. Tonic carotid chemoreceptor firing was independent of blood hematocrit and was only transiently increased at the time of dextran-for-blood exchange. The lack of effect of anemia on carotid chemoreceptor activity appeared to be due to sympathetic nerve activity. Section of the sympathetic nerves to the carotid chemoreceptors resulted in an increase in carotid chemoreceptor afferent activity during anemia in a manner similar to the increase in aortic chemoreceptor activity.
The influence of cotton dust inhalation on pulmonary leukocyte recruitment has been examined in rats and guinea pigs in an attempt to develop an animal model which can be used to assess the relative pulmonary toxicity of dusts from various varieties of cotton. Statistically significant increases in leukocyte populations in the lungs occur as the result of dust inhalation. Although the response is not influenced by the sex or age of the test animal, species differences do occur; guinea pigs are more sensitive to the effects of exposure than rats. Also, the exposure regimen tends to influence the degree of the response, with intermittent exposure producing fewer cells than continuous exposure for the same period of time. Future investigations will use the information gathered here to employ the most appropriate animal species as a tool to screen varieties of cotton, and thereby to rank them according to their potential to aggravate or to initiate certain pulmonary pathologies.
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Cotton dust particle distribution in respiratory airways was measured to determine if specific size particles of the heterogeneous dust are concentrated as a function of airway diameter. Previously reported work indicated that the fine particles are responsible for the decrement in pulmonary function which occurs subsequent to cotton dust inhalation. After recovery, particles were sized and counted microscopically. Significant increases in fine particles (5-7 mu) were found in all airways of exposed animals as compared with controls. These particles become more concentrated as the airway diameter decreased. Histamine determinations were made in mice lungs after the animals were exposed to cotton dust for various periods of time to see if such treatment could be correlated with elevations in the concentrations of this biogenic amine. Lung histamine increased as exposure time to cotton dust increased. It is concluded that the lung histamine release occurring after cotton dust inhalation is related to some property of the fine particles of the heterogeneous dust.