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  • 1,25(OH)2D3  (1)
  • 45Calcium  (1)
  • Ausscheidung  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Studies of the calcium accretion rate of bone during immobilization in intact and thyroparathyroidectomized adult rats (1977)
    Springer
    Calcified tissue international 22 (1977), S. 41-47 
    Details
    ISSN: 1432-0827
    Keywords: 45Calcium ; Immobilization ; Osteoporosis ; Parathyroid glands ; Thyroparathyroidectomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract In order to study the role played by the thyroid and the parathyroid glands in the development of osteoporosis induced by immobilization, 153 male adult Sprague-Dawley rats allocated in two groups were used. The animals of one group were thyroparathyroidectomized; those of the other group were left intact. Each group was then divided into two subgroups; in one the right hind leg of the animals were immobilized by an elastic adhesive bandage. The animals were observed for varying periods of time up to 16 weeks. Studies of bone mass and45Ca accretion rate of the right and left femur and tibia were performed in all animals. The results indicate that disuse osteoporosis occurs in rats in the virtual absence of the thyroid and parathyroid glands. The bone loss of the immobilized femur and tibia was less pronounced in thyroparathyroidectomized rats compared to intact rats. The uptake of45Ca in bone treated by immobilization as compared to the non-immobilized bone was found to be increased to the same proportion in thyroparathyroidectomized and in intact rats. The calcium-accretion rate of non-immobilized bone was lower in thyroparathyroidectomized than in intact rats. The observations indicate that in the rat the parathyroid and thyroid hormones influence the rate of bone turnover and thereby the rate of development of disuse osteoporosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02010345
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  • 2
    Electronic Resource
    Electronic Resource
    Effects of 1,25(OH)2D3 on bone tissue in the rabbit: Studies on fracture healing, disuse osteoporosis, and prednisone osteoporosis (1984)
    Springer
    Calcified tissue international 36 (1984), S. 591-595 
    Details
    ISSN: 1432-0827
    Keywords: Fracture ; (Glucocorticoid ; 1,25(OH)2D3 ; Osteoporosis ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A closed tibial fracture, which was controlled by an intramedullary stainless steel pin, was created in 16 rabbits. Eight rabbits were treated with 75 ng of 1,25(OH)2D3 daily as subcutaneous (s.c.) injections. After three weeks, the fractured tibia resisted a force of 101,7±21.0 Newtons in the control group and 57.3±8.0 Newtons in animals given 1,25(OH)2D3 (m±SE,P〈0.05). In another group of eight rabbits, the left hindleg was immobilized in a plastic splint. Four rabbits were given 75 ng of 1,25(OH)2D3/day s.c. and the effect of immobilization was studied on the calcaneus. Bone ash/cm3 of the calcaneus on the immobilized side was decreased by 11±2% in control rabbits and by 20±2% in the group treated with 1,25(OH)2D3 indicating a more advanced immobilization osteoporosis (m±SE,P〈0.05), which was also demonstrated by studies of bone density. Eighteen rabbits were used in a study of the effects of 1,25(OH)2D3 on the development of prednisolone osteoporosis. The dose of prednisolone was 2.5 mg per day, given by the oral route. After four months, the density of the femur was 1.53±0.02 g/cm2 in control rabbits and 1.42±0.01 in prednisolonetreated animals (P〈0.01). In rabbits additionally given 1,25(OH)2D3, the mean value for bone density was further lowered (n.s.). It appears that 1,25(OH)2D3 exaggerates disuse osteoporosis and prednisolone osteoporosis and impairs fracture healing in rabbits. These results differ from what has been shown earlier with 1,25(OH)2D3 treatment in the rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405372
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  • 3
    Electronic Resource
    Electronic Resource
    Metabolism of pentachlorophenol (1974)
    Springer
    Archives of toxicology 32 (1974), S. 271-281 
    Details
    ISSN: 1432-0738
    Keywords: Pentachlorophenol ; Excretion ; Metabolism ; Tetrachlorohydroquinone ; β-glucuronidase ; Pentachlorphenol ; Ausscheidung ; Metabolismus ; Tetrachlorhydrochinon ; β-Glucuronidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Ausscheidung von 14C-Pentachlorphenol im Harn von Ratten und Mäusen wurde nach oraler und intraperitonealer Verabreichung in Dosen von 10 bis 25 mg/kg untersucht. 41 bis 43% der ausgeschiedenen Aktivität waren unverändertes Pentachlorphenol. Mittels kombinierter Gaschromatographie und Massenspektroskopie konnte ein Metabolit, der 5 bzw. 24% der ausgeschiedenen Aktivität bei Ratten bzw. Mäusen ausmacht, als Tetrachlorhydrochinon identifiziert werden. Das Vorhandensein von Glucuronsäure-Konjugaten ließ sich nicht durch enzymatische Hydrolyse nachweisen, da Tetrachlorhydrochinon ein starker β-Glucuronidase-Hemmer (I50 = 1,6 bis 2,0×10−6M) ist. Kochen des Harns mit HCl wandelte die gesamte ausgeschiedene Aktivität in Pentachlorphenol und Tetrachlorhydrochinon um. Davon entfielen 43 (Ratten) bzw. 46% (Mäuse) auf Tetrachlorhydrochinon. Tetrachlorhydrochinon konnte auch im Harn von Arbeitern nachgewiesen werden, die beruflich mit Pentachlorphenol in Kontakt kommen.
    Notes: Abstract Excretion of pentachlorophenol-14C in the urine of rats and mice after oral and intraperitoneal administration (10 to 25 mg/kg) was studied. 41 to 43% of the excretion activity was found to be present as unchanged pentachlorophenol. By means of gas chromatography-mass spectrometry, one metabolite was identified as tetrachlorohydroquinone, representing 5 and 24% of the excreted activity in rats and mice, respectively. Conjugation with glucuronic acid could not be demonstrated by enzymatic hydrolysis since tetrachlorohydroquinone was found to be a potent inhibitor of β-glucuronidase, the I50 being 1.6 to 2.0×10−6 M. Boiling the urine with hydrochloric acid was shown to convert all of the excreted activity to pentachlorophenol and tetrachlorohydroquinone, the latter representing 43 and 46% in rats and mice, respectively. Tetrachlorohydroquinone was found in the urine of workers occupationally exposed to pentachlorophenol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330109
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    Paper (German National Licenses)
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