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  • 1
    ISSN: 1432-0738
    Keywords: Key words Piperonyl butoxide ; Diet restriction ; Atrophy of lympho-hematopoietic tissues ; Immunohistochemistry of T/B lymphocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Changes observed in lympho-hematopoietic organs in rats given piperonyl butoxide may be attributable either to direct toxic effects or to undernutrition. Male F344 rats were therefore fed diet containing 2.5% piperonyl butoxide or subjected to a 64% restriction of food intake for 2 weeks. Marked inhibition of body weight gain, decreased white blood cell count, depletion of T/B lymphocytes in lymphoid tissues, hypoplasia of the bone marrow, and decreased proliferating cell nuclear antigen (PCNA) labeling indices in these tissues were seen in both dietary restriction and 2.5% piperonyl butoxide groups. The depletion of T lymphocytes in the thymus and spleen was stronger in the 2.5% piperonyl butoxide group, as indicated by PCNA labeling indices and image analysis of T lymphocyte areas of the spleen, however, the toxicological profile observed for the chemically treated group was essentially the same as for animals on the restricted diet. These results suggest that the lympho-hematopoietic findings in rats receiving 2.5% piperonyl butoxide are probably due to undernutrition resulting from a reduced food intake.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0738
    Keywords: Key words Thyroid carcinogenesis ; Vitamin A ; Thiourea ; UDP-GT ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mechanisms underlying enhanced cell proliferation in thyroid proliferative lesions of rats simultaneously treated with large amounts of vitamin A (VA) and thiourea (TU) were investigated. Male F344 animals were initiated with N-bis(2-hydroxypropyl)nitrosamine (2800 mg/kg body weight, single s.c. injection). Starting 1 week later, groups received water containing 0.2% TU (TU group), diet containing 0.1% VA (VA group), both 0.2% TU and 0.1% VA (TU + VA group) or tap water/basal diet without supplement (control group) for 10 weeks. The serum levels of triiodothyronine (T3) and thyroxine (T4) were decreased and the thyroid stimulating hormone (TSH) levels were elevated in the TU and TU + VA groups, with the degree of change being significantly greater in the combined treatment group. The induction of P450 isoenzymes by TU was not enhanced by VA supplementation, but uridine diphosphate glucuronosyltransferase (UDP-GT) activity in the liver was significantly increased in the TU + VA group compared to the TU group. Thyroid weights were increased in both the TU and TU + VA groups, this being more pronounced with VA supplementation. Thyroid follicular cell hyperplasias and neoplasias were induced to similar extents in both TU treated groups, but their cell proliferation appeared to be increased by the VA supplementation. The results of the present study suggest that enhanced cell proliferation is due to increased TSH stimulation, resulting from the decrease in serum T3/T4 levels brought about by induction of liver UDP-GT activity with the combined action of TU + VA as well as inhibition by TU of thyroid hormone synthesis in the thyroid.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0738
    Keywords: Key words CdCl2 ; Chronic toxicity ; Body burden ; of Cd ; Renal toxicity ; Liver toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We wished to clarify the relationship between the sensitivity to induce hepato-renal toxicity and the level of cadmium (Cd) in the organs of rats exposed to minimum to large amounts of cadmium chloride (CdCl2). For this purpose, groups of female Sprague-Dawley (SD) rats, each consisting of 24 animals, were fed diet containing CdCl2 at concentrations of 0, 8, 40, 200, and 600 ppm for 2, 4, and 8 months from 5 weeks of age. All surviving rats given 600 ppm Cd were killed at 4␣months because of deterioration of their general condition. Animals of this group showed anemia and decreased hematopoiesis in the bone marrow, in addition to reduction of cancellous bone in their femurs. Hepatotoxicity was observed after 2 months in the groups treated with 200 ppm. By 4 months, the rats in the 600 ppm group had developed periportal liver cell necrosis. Renal toxicity characterized by degeneration of proximal tubular epithelia was apparent in the groups treated with 200 ppm from 2 months, becoming more prominent in the high-dose rats at 4 months. Hepatic accumulation of Cd increased linearly with the duration of treatment. In contrast, the concentration of Cd in the renal cortex of rats treated with 600 ppm reached a plateau level of ∼250 μg/g within the first 2 months. The renal concentration of Cd in the 200 ppm group when renal toxic lesions were first detected at 2 months ranged from 104 to 244 μg/g. No renal lesions were observed in the 40 ppm group after 8 months, despite the presence of 91–183 μg/g of Cd in the kidneys. The results thus suggest that renal toxicity would not be induced by treatment with minimum amounts of CdCl2 for periods longer than 8 months, although accumulation of Cd might gradually progress. A further 2-year feeding study of CdCl2 and Cd-polluted rice is now in progress.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Food and Chemical Toxicology 32 (1994), S. 1101-1106 
    ISSN: 0278-6915
    Keywords: [abr] PAH; polycyclic aromatic hydrocarbon
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of cancer research and clinical oncology 109 (1985), S. 178-182 
    ISSN: 1432-1335
    Keywords: N-Methyl-N-nitrosourea (MNU) ; F344/DuCrj rat ; ACI/N rat ; Neurogenic tumor ; Organspecific carcinogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Male and female F344 rats were continuously administered N-methyl-N-nitrosourea (MNU) in their drinking water at concentrations of 200 or 100 ppm, and both sexes of ACI/N rats were given MNU at a concentration of 200 ppm. By the 42nd week of the experiment, high incidences of brain/spinal cord tumors were observed in both strains of rats. Histologically, many of them were astrocytomas or anaplastic astrocytomas. In addition, malignant neurinomas were also detected in the spinal nerve roots and trigeminal nerves, although their incidences were rather low. There was no difference in the type and incidence of these neurogenic tumors between the two strains of rats. Tumors of the tongue and esophagus were mainly observed in the high-dose group of F344 rats and those of the glandular stomach were observed in the low-dose group of F344 rats. In ACI/N rats, tumors of the heart and renal pelvis were detected. The organ-specific carcinogenicity of MNU in these two strains of rats was compared with that of MNU in Donryu rats. It was demonstrated that organ specificity of MNU given orally was influenced not only by the strain of rats but also by the dose level.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1335
    Keywords: Renal dysplasia ; N-nitrosobis(2-oxopropyl)amine ; Ethinylestradiol ; Hamsters ; NOR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The modulating effects of female sex hormones, ethinylestradiol and levonorgestrel, on the development of renal proliferative lesions after initiation withN-nitrosobis(2-oxopropyl)amine (BOP) were investigated. Three groups of female Syrian golden hamsters, each comprising 30 animals, were given four weekly s.c. injections of BOP (10 mg/kg body weight) and then fed diet containing 1 ppm ethinylestradiol (group 1: BOP/EE), diet containing 10 ppm levonorgestrel (group 2) or basal diet (group 3) for the next 27 weeks. As hormone controls, two groups of 20 female hamsters each received diet containing 1 ppm ethynylestradiol (group 4) and 10 ppm levonorgestrel (group 5) from week 3 for 27 weeks without the prior initiation treatment. The severity of diffuse anisokarya, characterized by varied nuclear size and the incidence of dysplasias of the proximal tubular epithelia induced by BOP, were significantly increased in the BOP/EE group, indicating the promoting effects of the hormone. In the renal dysplastic lesions (smallcluster, cystic, clear-cell and acidophilic cell types), adenomas and nephroblastomas, increases in the numbers of argyrophilic proteins associated with nucleolar organizer regions (NOR) in the nucleus, suggesting a high proliferative activity, were seen in dysplasia of acidophilic cell types and adenomas. In addition, the number of bizarre NOR per nucleus was significantly higher in adenomas than in dysplasias and highest in nephroblastomas. This morphological change in NOR should therefore be a useful parameter for the diagnosis of malignancy of renal tumors.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-0533
    Keywords: Experimental glioma model ; Ethyl-nitrosourea (ENU) ; F344 rat ; Geminal neuroepithelium ; Neuronal differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Brain tumors induced by transplacental application of ethyl-nitrosourea (ENU) in F344 rats were immunohistochemically demonstrated to consist of undifferentiated cells, astriocyte-like cells, oligodendroglia-like cells, and two distinct types of vimentin-expressing cell groupings termed as perivascular small cell nests (PSCNs) and large cell nests (LCNs). Co-distribution of vimentin and glial fibrillary acidic protein (GFAP) was sparsely ovserved in the astrocyte-like cells, which suggested an immature glial phenotype. PCSNs contained cells expressing GFAP, neuron-specific enolase (NSE), β-tubulin isotype III, and low-affinity nerve growth factor receptors (LNGFRs). LCNs contained cells showing a neuronal phenotype with expression of low- and middle-molecular mass neurofilament proteins (NF-L and-M) as well as NSE, β-tubulin isotype III and LNGFR. Double-labelling immunohistochemistry revealed the NF-L-expression in LNGFR-positive LCN-forming cells. Oligodendroglia-like cells and their intercellular neuropil-like structures expressed β-tubulin isotype III, synaptophysin and NSE, in addition to the expressions of vimentin and GFAP. Electron microscopically, synapse-like structures were formed between these oligodendroglia-like cells and their dendritic processes. Topographically, bidirectional cell transitions from PSCNs to astrocytes and LCNs were indicated. The present study strongly suggests that so-called ENU-induced “gliomas” originate from pluripotent germinal neuroepithelium. Furthermore, LNGFR expression may be responsible for acquisition of neuronal phenotype in these tumors.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0533
    Keywords: Key words: Experimental glioma model – Ethyl nitrosourea (ENU) – F344 rat – Germinal neuroepithelium – Neuronal differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Brain tumors induced by transplacental application of ethyl-nitrosourea (ENU) in F344 rats were immunohistochemically demonstrated to consist of undifferentiated cells, astriocyte-like cells, oligodendroglia-like cells, and two distinct types of vimentin-expressing cell groupings termed as perivascular small cell nests (PSCNs) and large cell nests (LCNs). Co-distribution of vimentin and glial fibrillary acidic protein (GFAP) was sparsely observed in the astrocyte-like cells, which suggested an immature glial phenotype. PCSNs contained cells expressing GFAP, neuron-specific enolase (NSE), β-tubulin isotype III, and low-affinity nerve growth factor receptors (LNGFRs). LCNs contained cells showing a neuronal phenotype with expression of low- and middle-molecular mass neurofilament proteins (NF-L and -M) as well as NSE, β-tubulin isotype III and LNGFR. Double-labelling immunohistochemistry revealed the NF-L-expression in LNGFR-positive LCN-forming cells. Oligodendroglia-like cells and their intercellular neuropil-like structures expressed β-tubulin isotype III, synaptophysin and NSE, in addition to the expressions of vimentin and GFAP. Electron microscopically, synapse-like structures were formed between these oligodendroglia-like cells and their dendritic processes. Topographically, bidirectional cell transitions from PSCNs to astrocytes and LCNs were indicated. The present study strongly suggests that so-called ENU-induced "gliomas" originate from pluripotent germinal neuroepithelium. Furthermore, LNGFR expression may be responsible for acquisition of neuronal phenotype in these tumors.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1920
    Keywords: Key words Diaschisis ; Pontine infarct ; Cerebral blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Remote cerebral hypoperfusion associated with pontine lesions is rare. We describe a patient who showed transient ipsilateral hypoperfusion in the thalamus and cerebral cortex after a pontine infarct. This resolved within 8 days after onset. Anatomical considerations strongly suggested involvement of the cerebellothalamocortical pathway in this case.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1920
    Keywords: Diaschisis ; Pontine infarct ; Cerebral blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Remote cerebral hypoperfusion associated with pontine lesions is rare. We describe a patient who showed transient ipsilateral hypoperfusion in the thalamus and cerebral cortex after a pontine infarct. This resolved within 8 days after onset. Anatomical considerations strongly suggested involvement of the cerebellothalamocortical pathway in this case.
    Type of Medium: Electronic Resource
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