刺激性ガスおよび粉塵吸入による生体の反応に関する実験的研究 : 気道粘膜の反応について

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The development of modern industries has brought the regional integration of the correlated ones and the establishment of the mammoth cities resulting from the increase in the population engaging in those industries. In addition, such development in and around the established cities has exerted the significant influences not only on the economic but also on the environmental conditions of inhabitants in the cities and those outskirts. Among the substances constituting air pollution, coexistence of organic dusts and irritant gases such as sulfur dioxide gas should be recognized as an inducing fatter affecting health of the inhabitants in those areas. The increase in the respiratory disorder such as chronic bronchitis or asthma might be interpreted as the manifestation of the combined actions of predisposition, induced by organic dusts and others, and rising effets of irritant gases to the respiratory organs. The results obtained from the investigation reported here provide an clear evidence to the above mentioned interpretation. Guinea pigs in germfree and conventional conditions were used as the experimental animals. The former was evaluated as the essential tools for the investigations concerning the effects of air pollutants on living things in order to simplify the experimental conditions. Also, the quite unique way has been adapted to observe the interaction between sulfur dioxide gas and organic dust (skimmed cow milk powder), i.e. the silica particles were taken as an indicator of the phenomena of intaking and movement of physical extraneous particles into the epithelia and within the tissues, because silica impedes moderately the function of living tissues. The results obtained from the investigations were asbelow: Inhalation of the 40 ppm SO_2 gas induced the inflammation in the trachea of germfree and conventional animals. The inflammation in the trachea of the germfree animals was stronger than the conventional ones. None of the silica particle could be found in the trachea of the conventional guinea pigs after the inhalation of silica containing air. But when the silica particles were inhaled sequentially or simultaneously with the exposure of SO_2 gas, the particles were found in the tracheal epithelial cells and in the submucous layers. The emigration cell reactions in moderate degree could be found in the particle invased areas. The sensitization state of the animal with the organic dust was emphasized after an exposure to SO_2 gas. After getting sensitized, antigen-antibody reaction was induced in the respiratory organ of animals, when they encountered again the organic dust. The silica particles were found in the tracheal epithelial cells and in the submucous layer of the conventional guinea pig after the inhalation of 30 minutes with the mixture of skimmed milk powder and silica particles, when they had been sensitized with the combined inhalation of the milk powder and SO_2 gas two months before. There could not be observed in unsensitized animals such severe inflammatory cellular reactions in the trachea that found in sensitized ones. The particular phenomenon observed in the trachea of the germfree guinea pigs exposed to the silica particles was the invasion of the particles into the epithelial cells and submucous layers. The large amount of silica particles could also be found in the paratracheal lymphnode of the germfree animals after the silica inhalation of 30 minutes. There observed a decreasing tendency in the amount of silica particles invased in the epithelial cells as the frequency of silica inhalation chances were increasing. The intruding phenomenon of silica particles was also observed in new born guinea pigs except in those more than 24 hours after birth. The existence of silica particles, not in the intercellular space but in the epithelial cells, was ascertained by electron-microscopy and phasem-icroscopy carried out in parallel. The preventive functions of the tracheal epithelial cells against foreign particle invasion, including the removing functions of cilia, seemed to be increased by the so-called "training effect" of gases and dusts in inert degrees of respective concentrations. But the sulfur dioxide gas of 40 ppm impeded the preventive functions of the mucous membrane in conventional animals, involved in removing the extraneous substances and checking the foreign particles intrude into the epithelia and subepithelial tissues.
千葉大学の論文

刺激性ガスおよび粉塵吸入による生体の反応に関する実験的研究 : 気道粘膜の反応について

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