I Although the majority of deaths resulting from exposure to sulfur mustard (HD) have been due to pulmonary dysfunction, there are no detailed accounts of the pathogenesis of HDinduced lesions in the respiratory tract. Accordingly, we investigated the early changes within the trachea and lungs of rats following inhalation exposure to HD. Anesthetized rats were exposed by intratracheal intubation to vaporized H D (0.35 mg in 100 wl absolute ethanol) or ethanol alone for 50 min. Animals were euthanatized at 0, 1, 4, 6, 12, 18, and 24 li postexposure (PE), and their respiratory tracts were prepared for histological and ultrastructural examination. In rats exposed to HD, multifocal, petechial hemorrhages were grossly evident on tlie pleural surface of the lung at 6 h PE. Atelectasis and edema of the accessory lobe occurred at 12-18 h PE. Histologically, lesions in the respiratory tract were confined primarify to the trachea, bronchi and targer bronchioles. It, HD-exposed rats, there was a progressive depletion of the bronchiolar-associated lymphoid tissue (BALTI, with necrosis of the lymphoid cells as early as 12 h PE. Necrosis and sloughing of the tracheal and bronchial epithelia at 6-12 h PE was followed by the formation of fibrinous pseudomembranes within the bronchi. Necrosis and separation of airway epithelia occurred at the mucosaUsubmucosal interface. Pseudomembranes formed almost exclusively in deepitlielialized areas overlying tlie BALT. Cartilaginous lesions, characterized by necrosis of individual chondrocytes, were evident at I2 li PE. Pulmonary edema and occasional alveolar hemorrhage occurred from I8 to 24 li PE. Small bronchioles and alveoli were relatively unaffected, and only a few inflammatory cells were observed at any time.
PweuWomonas aerugi*osa is widely known for two distinctive properties: the production of the blue pigment, pyocyanin, and the ability to lyse or to inhibit the growth of other bacteria. Little attempt has been made to determine the relation between the two, and although pyocyanin and its derivative, a-oxyphenazine, have been shown to have inhibitory powers (Hettche, 1932; Schoental, 1941), the emphasis has been on antibiotic substances other than the pigments. Hettche has stated, in fact, that no parallelism exists between pigment production and the formation of these other antibiotics, and Gaby (1946) concluded that they were best produced by strains of the organism which formed no pyocyanin at all. These workers, however, paid little attention to the nature of the culture medium and its possible effect on both properties. Studies of the pigments of P. aeruginosa have appeared in the literature with some regularity since Fordos extracted pyocyanin from surgical dressings in 1860. It is interesting that the isolation of the organism itself (Gessard, 1882) was done in an attempt to "verify the parasitic origin of the phenomenon" (i.e., the blue color of pus and dressings) "by M. Pasteur's method of cultures." In addition to pyocyanin, at least four other colored substances are associated with this species: a fluorescent compound, yellow by transmitted light, blue-green by reflected light (Jordan, 1899); pyorubin, a red pigment which is apparently not formed by all strains (Meader et al., 1925); a-oxyphenazine or hemipyocyanin, a yellow breakdown product of pyocyanin (Wrede and Strack, 1924); and a dark brown substance formed in some old cultures, possibly a derivative of the fluorescent pigment. Of all these, pyocyanin alone has been assigned a useful role in the physiology of the organism. It is easily oxidized and reduced in cultures, and acts in conjunction with the cytochrome system of the cells to increase respiration (Friedheim and Michaelis, 1931; Friedheim, 1931). The antagonistic power of the organism was shown by Bouchard (1889), when he demonstrated that rabbits injected with anthrax bacilli could be prevented from developing the disease by inoculation with the "blue pus bacillus." Emmerich and Low (1899), using a culture filtrate to prevent anthrax, believed that the active substance was an enzyme, and named it pyocyanase. The enzyme theory was short lived, as lipoidal, heat-stable extracts were found to be effective (Raubitschek and Russ, 1909), but the name has persisted. Hettche (1934) separated this material into neutral fat, phosphatide, and a mixture of fatty acids, and attributed most of the inhibitory activity to the unsaturated fatty acids. Schoental (1941) obtained, in addition to pyocyanin and a-oxyphenazine, a pale 109
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.