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  • SAGE Publications  (3)
  • English  (3)
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  • SAGE Publications  (3)
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  • English  (3)
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  • 1
    In: Toxicologic Pathology, SAGE Publications, Vol. 31, No. 3 ( 2003-04), p. 340-347
    Abstract: The nasal cavity is an important target organ for toxicity, and many chemicals induce site-specific lesions in this region. The factors responsible for this site-selectivity have not been unequivocally identified, but probably include regional dosimetry and bioactivation. The purpose of this study was to map, in 3 dimensions, the lesions induced by β- β'-iminodipropionitrile (IDPN), methyl iodide (MeI) and methyl methacrylate (MMA) in the rat nasal cavity. Animals were administered IDPN (150 mg/kg, IP) or exposed via inhalation to MeI (100 ppm, 2 hours) or MMA (400 ppm, 4 hours) and sacrificed after 24 hours. Heads were decalcified, step-sections (1 every 400 μm) cut and stained, and the severity of the epithelial lesion graded as mild (vacuolation and pyknosis), moderate (undulation and mild stripping), or marked (complete stripping). These grades were mapped onto a 3D-model of a rat nasal cavity using the KS400 imaging system (Imaging Associates, Thame, UK). Despite the different routes of exposure the lesions induced by the 3 compounds had very similar distributions, predominantly affecting the dorsal-medial aspects of the ethmoturbinates and, in the case of MMA, the organ of Rodolfo Masera. These results suggest that, with these chemicals, local bioactivation plays a more important role than dosimetry in determining lesion distribution.
    Type of Medium: Online Resource
    ISSN: 0192-6233 , 1533-1601
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2003
    detail.hit.zdb_id: 2056753-4
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  • 2
    In: Toxicologic Pathology, SAGE Publications, Vol. 31, No. 3 ( 2003-04), p. 332-339
    Abstract: A variety of chemicals induce site-specific lesions in the rodent nasal cavity. In order to explore the reasons for this site-selectivity, methodology for (a) creation of a 3-dimensional (3D) model of a rat nasal cavity, and (b) mapping of semiquantitative data onto the model has been developed. The head of a rat was fixed, decalcified, step-sectioned (every 100 μm) and stained with hematoxylin and eosin. Digital images of the sections were optically captured, and a KS400 image analysis system (Imaging Associates, Thame, Oxford, UK), attached to a standard personal computer, was used to align adjacent images and reconstruct the series in 3D. The final model was anatomically correct, and could be rotated in any plane and manipulated to display individual internal structures. The spatial localization of a glutathione S-transferase (rGSTM1, previously known as GST 3-3) within this model was investigated using immunohistochemistry. Step sections (every 400 μm) were stained, analyzed by imaging densitometry, and the results for the stained regions within the nasal cavity divided into 4 grades representing high to low expression of rGSTM1. The data was mapped onto the 3D model and showed that the highest expression of this enzyme was in the central regions of the nasal cavity at the transition between respiratory and olfactory epithelia. This methodology will allow investigation of the relationship between the in situ localization of bioactivating and detoxifying enzyme systems and the site-specificity of nasal lesions.
    Type of Medium: Online Resource
    ISSN: 0192-6233 , 1533-1601
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2003
    detail.hit.zdb_id: 2056753-4
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  • 3
    Online Resource
    Online Resource
    SAGE Publications ; 1998
    In:  Toxicologic Pathology Vol. 26, No. 1 ( 1998-01), p. 18-25
    In: Toxicologic Pathology, SAGE Publications, Vol. 26, No. 1 ( 1998-01), p. 18-25
    Abstract: The kidney possesses most of the common xenobiotic metabolizing enzymes, and is thus able to make an important contribution to the body's metabolism of drugs and foreign compounds. An overview of the renal localization, catalytic activity, developmental regulation, induction, and sex and species differences for the key enzymes involved in phase I and phase II of xenobiotic metabolism is presented. In general, the catalytic activities of the various renal enzymes are lower than those of the liver, although there are exceptions, such as the enzymes involved in the processing of glutathione conjugates to their mercapturic acids. Xenobiotic metabolizing enzymes are not evenly distributed along the nephron; cytochromes P-450 and those enzymes involved in the conjugation of glutathione, glucuronic acid, or sulfate are primarily localized in the proximal tubules. However, some isozymes of cytochrome(s) P-450 and glutathione S-transferases are selectively localized in cells of the thick ascending limb and distal tubules, whereas prostaglandin H synthase is concentrated in the collecting ducts in the medulla. Thus, the proximal tubule, the principal site of xenobiotic biotransformation, is particularly susceptible to chemical insult, and the localization of prostaglandin synthase in the inner medulla and papilla may be a contributary factor to the toxicity produced by chemicals in this part of the nephron. Many of the enzymes discussed, in addition to metabolizing foreign compounds, have important endogenous functions in the kidney, such as the regulation of salt and water balance and the synthesis of vitamin D.
    Type of Medium: Online Resource
    ISSN: 0192-6233 , 1533-1601
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1998
    detail.hit.zdb_id: 2056753-4
    Location Call Number Limitation Availability
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