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  • 1990-1994  (2)
  • 1960-1964
  • Cholecystitis  (1)
  • Maternal toxicity  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Solitary versus multiple cholesterol gallbladder stones (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. 423-434 
    Details
    ISSN: 1432-1440
    Keywords: Cholecystolithiasis ; Supersaturation ; Gallstones ; Cholesterol ; Cholecystitis ; Occlusion of the cystic duct
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The development and growth pattern of solitary and multiple cholesterol gallbladder stones was defined using cholecystography in a prospective study of 48 patients whose initial cholecystograms indicated a stone-free gallbladder and who developed gallstones within the subsequent 5 years. Radiological observations performed over 365 patient-years were complemented by macroscopic examination, radiograms, scanning electron microscopy, and chemical analysis of gallstones from these and other patients obtained at cholecystectomy. Solitary gallstones were found to develop after a precursor phase of over 2 years during which free-floating crystal laminae of cholesterol formed. These laminae subsequently aggregated loosely and underwent external compaction and internal remodeling by movement of cholesterol molecules to form compact spheroids. A single lamina was observed to function as a nucleus for the development of a solitary stone shaped as an ellipsoid. About 10% of solitary stones were found to have a solitary pigment stone in their center. In contrast, multiple cholesterol gallstones formed without a precursor phase. Innumerable, very thin cholesterol crystals appeared which very abruptly aggregated to form spheres of up to 1 mm in diameter. Within 3 months a second aggregation took place in which these spheres coalesced to form mulberry stones. Mulberry stones in turn were transformed either to faceted stones (if many were present in the gallbladder) or to barrel stones (if few were present) over a period of 3 years. It is proposed that temporary occlusion of the cystic duct leads to supersaturation of bile with calcium bilirubinate and/or calcium carbonate which in turn promotes deposition of either or both of these calcium salts on the surface of single or multiple gallstones. For multiple gallstones, this process or the deposition of additional cholesterol crystals seals the gallstone surface and is followed by metamorphosis of the stone center.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00180054
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Studies on the prenatal toxicity of toluene in rabbits following inhalation exposure and proposal of a pregnancy guidance value (1992)
    Springer
    Archives of toxicology 66 (1992), S. 373-381 
    Details
    ISSN: 1432-0738
    Keywords: Toluene ; Maternal toxicity ; Embryotoxicity ; Teratogenicity ; Rabbit ; Inhalation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Prenatal toxicity of toluene was determined in two separate studies by inhalation exposure of Himalayan rabbits. In the first study 15 artificially inseminated females per group were exposed to 30, 100, or 300 ppm and in the second study 20 artificially inseminated females per group inhaled 100 or 500 ppm. In each case the rabbits were exposed for 6 hours per day from day 6 post-insemination (p. i.) to day 18 p. i. The respective controls inhaled conditioned clean air under the same exposure conditions. No signs of maternal toxicity were observed. All data obtained on gestational parameters were found to be within the variation range reported for this rabbit strain. The fetal external, soft tissue and skeletal findings were seen in toluene exposed fetuses in a frequency similar to the corresponding and/or historical controls. Differences observed between the groups were not concentration dependent and were considered incidental rather than compound related. Therefore, toluene was not embryotoxic, fetotoxic, or teratogenic for rabbits exposed during the period of organogenesis. The highest concentration tested under these conditions (500 ppm) was found to be a no-observable-adverse-effect level (NOAEL) for both the adult and the fetal Himalayan rabbit. Based on these and previous results of animal studies of prenatal toxicity, a safety or uncertainty factor approach is considered for setting limits of exposure for women at workplaces. A pregnancy guidance value of 20 ppm is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02035125
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    Paper (German National Licenses)
    Fulltext
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