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  • 1
    Electronic Resource
    Electronic Resource
    Doxorubicin induces male germ cell apoptosis in rats (1999)
    Springer
    Archives of toxicology 73 (1999), S. 274-281 
    Details
    ISSN: 1432-0738
    Keywords: Key words Doxorubicin ; Apoptosis ; Testicular toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To clarify whether apoptosis is involved in doxorubicin (DXR)-induced testicular toxicity and to identify the target germ cell type, adult Sprague-Dawley rats were treated with a single intravenous dose of DXR (8 or 12 mg/kg) and euthanized at 3, 6, 12, 24, and 48 h subsequently. Histologically, germ cell degeneration was first found 6 h after dosing in meiotically dividing spermatocytes and early round spermatids of seminiferous tubules at stage I, and subsequently observed in spermatogonia at stages I–VI showing ultrastructural characteristics of apoptosis. Coincident with the appearance of morphological changes, degenerating germ cells were shown to be undergoing apoptosis as revealed by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). The frequency of TUNEL-labeled germ cells increased in a stage- and cell type-specific manner, the peak of frequency gradually progressing from stage I of seminiferous tubules to later stages with time after dosing, suggesting that the damaged germ cells, especially spermatogonia, gradually underwent the processes leading to apoptosis. DNA laddering on gel electrophoresis was apparent 24 and 48 h after dosing. The results demonstrate that apoptosis plays an important role in the induction of testicular toxicity caused by DXR with meiotically dividing spermatocytes and type A and intermediate spermatogonia as highly vulnerable target cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050617
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  • 2
    Electronic Resource
    Electronic Resource
    The relationship between decrease in Cx32 and induction of P450 isozymes in the early phase of clofibrate hepatocarcinogenesis in the rat (1999)
    Springer
    Archives of toxicology 73 (1999), S. 373-380 
    Details
    ISSN: 1432-0738
    Keywords: Key words Clofibrate ; Connexin ; Liver ; Promotion ; P450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To examine the relationship between the decrease in connexin 32 (Cx32) and induction of P450 isozymes in the early phase of clofibrate hepatocarcinogenesis, a total of 20 male F344 rats were initiated with a single intraperitoneal injection of 150 mg/kg of diethylnitrosamine (DEN) or given the saline vehicle alone and starting 2 weeks later given diet containing 0.18, 0.09, and 0% clofibrate for 6 weeks. All animals were subjected to two-thirds partial hepatectomy at week 3 and killed at week 8. Absolute and relative (ratios to body weight) liver weights were significantly increased in the DEN + clofibrate groups compared with the DEN-alone group. Diffuse hepatocellular hypertrophy with granular cytoplasmic eosinophilia characterized by a marked increase in peroxisomes and smooth endoplasmic reticulum, was observed in the clofibrate treated rats. Induction of cytochrome P450 (CYP) 4A1 and 2B1/2 was noted in the DEN + clofibrate groups, this being most marked in the CYP 2B1 case. Immunohistochemically, positive immunostaining for anti-CYP 4A1 and CYP 2B1 were observed diffusely and centrilobularly, respectively. The numbers and areas of Cx32-positive spots per hepatocyte in the centrilobular areas in the treated rats were significantly decreased in an essentially dose-dependent manner, but no changes were observed in periportal areas. The numbers and areas of foci positive for glutathione S-transferase placental form (GST-P) were decreased in a dose dependent manner in the clofibrate treated groups. These results suggest that the CYP 2B1/2 induction and Cx32 decrease in centrilobular hepatocytes, similarly to those thought to be involved in the hepatic promotion mechanism of phenobarbital, may also play important roles in clofibrate actions in the liver, in addition to its causation of oxidative DNA injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050676
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  • 3
    Electronic Resource
    Electronic Resource
    Repeated dose (28 days) oral toxicity study of flutamide in rats, based on the draft protocol for the `Enhanced OECD Test Guideline 407' for screening for endocrine-disrupting chemicals (2000)
    Springer
    Archives of toxicology 74 (2000), S. 127-132 
    Details
    ISSN: 1432-0738
    Keywords: Key words Flutamide ; Androgen antagonist ; Rat ; Enhanced OECD Test Guideline 407 ; Endocrine disrupters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In association with the international validation project to establish a test protocol for the `Enhanced OECD Test Guideline 407', we performed a preliminary 28-day, repeated-dose toxicity study of flutamide, a non-steroidal androgen antagonist, and assessed the sensitivity of a list of parameters for detecting endocrine-related effects of endocrine-disrupting chemicals (EDCs). Seven-week-old CD(SD)IGS rats were divided into four groups, each consisting of 10 males and 10 females, and administered flutamide once daily by oral gavage at doses of 0 (control), 0.25, 1 and 4 mg/kg body weight/day. Male rats were killed 1 day after the 28th administration. Female rats were killed on the day they entered the diestrus stage in the estrous cycle following the last treatment. Male rats receiving flutamide at dose levels of 1 and 4 mg/kg showed lobular atrophy of the mammary gland and a decrease in epididymal weight. In addition, 4 mg/kg flutamide-treated males exhibited raised serum testosterone and estradiol levels and decreased weight of the accessory sex glands. In females, a slight prolongation of the estrous cycle was also observed in the 4 mg/kg flutamide-treated group. No dose-related changes could be detected by haematology, serum biochemistry and sperm analysis. Thus, among the parameters tested in the present experimental system, the weight of endocrine-linked organs and their histopathological assessment, serum hormone levels, and estrous cycle stage allowed the detection of endocrine-related effects of flutamide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050664
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  • 4
    Electronic Resource
    Electronic Resource
    Time course of ultrastructural changes and immunoelectron microscopic localization of neurocalcin in motor endplates of the lumbrical muscles of rats given a single administration of 2,5-di(tert-butyl)-1,4-hydroquinone (2000)
    Springer
    Acta neuropathologica 99 (2000), S. 109-116 
    Details
    ISSN: 1432-0533
    Keywords: Key words 2,5-Di(tert-butyl)-1,4-hydroquinone (DTBHQ) ; Wistar rat ; Motor endplate ; Lumbrical ¶muscle ; Neurocalcin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A time-course study of ultrastructural changes and immunoelectron microscopic localization of neurocalcin was performed on motor endplates of the lumbrical muscles of female Wistar rats given a single oral administration of 2,5-di(tert-butyl)-1,4-hydroquinone (DTBHQ) at a dose of 120 mg/kg. Toxic signs such as salivation and muscle weakness of the hind legs appeared from 3 h after DTBHQ administration. No remarkable macroscopic or light microscopic changes were noted in the lumbrical muscles of the treated rats. At the ultrastructural level, neurotoxicity characterized by a decreases or loss of synaptic vesicles and mitochondria was observed after 24 h and at the 1-week time point, nerve endings had disappeared in some of the motor endplates, while many neurite nerve endings suggestive of early stage regeneration were apparent. After 6 weeks, newly formed reinnervated endplates were observed. Immunoelectron microscopically, the synaptic vesicle membranes were heavily labeled for neurocalcin in the control rats, but not at 24 h after DTBHQ treatment. Synaptic vesicle membranes in the DTBHQ group were weakly labeled at 1 week, but strongly at 6 weeks. The results strongly suggest that DTBHQ targets the motor endplates in the rat lumbrical muscles, causing depletion of neurocalcin in the synaptic vesicles followed by their loss.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007413
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    Paper (German National Licenses)
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