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  • 1
    ISSN: 1432-0533
    Keywords: Cytosine arabinoside ; Mice ; Microcephaly ; Cerebral cortex ; Hippocampus ; Abnormal cytoarchitecture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Pregnant mice were treated with cytosine arabinoside on days 13.5 and 14.5 of pregnancy. Brains of the offspring were studied histologically. The matrix layer of the embryonic brains was extensively destroyed 12h after the injection of cytosine arabinoside, but regenerated partially on day 17 of gestation. In the cerebral cortex of 1-, 3-, and 5-day-old treated mice, abnormal clusters of young neurons were found on the surface of the developing cerebral cortex. Some clusters still had a supply of immature neurons from the remnants of the regenerated matrix layer. After 20 days, the clusters became gradually indistinct, although some vestigial groups of neurons were observed even after 120 days. In the hippocampus of young mice, the pyramidal cells decreased in number and were disarranged. Heterotopic pyramidal cell masses were found in the stratum radiatum and in the molecular layer of the dentate gyrus. Apical dendrites of pyramidal cells exhibited abnormal arborization. It was demonstrated by3H-thymidine autoradiography that young neurons in the abnormal clusters in the cerebral cortex were those produced in the matrix layer regenerated after the destructive change by cytosine arabinoside.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 59 (1983), S. 41-47 
    ISSN: 1432-0533
    Keywords: Cytosine arabinoside ; Cerebellum ; External granular layer ; Purkinje cell ; Heterotopic granule cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was undertaken to elucidate the relationship between the time of destruction of the external granular layer and subsequent cerebellar abnormalities. Mice were injected s. c. with 30 mg/kg body weight (b. wt.) of cytosine arabinoside on days 2, 3, and 4, on days, 4, 5, and 6, on days 7, 8, and 9, and on days 10, 11, and 12, and designated as group I, II, III, and IV, respectively. In group I, disarrangement of Purkinje cells and heterotopic granule cells in the molecular layer were observed on all lobes of cerebellum. Heterotopic granule cells were seen on all lobes in group II, whereas disarrangement of Purkinje cells was observed only in the region from the anterior to middle lobes. In group III, heterotopic granule cells were limited to the area from anterior to middle lobes, but there was no disarrangement of Purkinje cells. Group IV cerebellum did not show abnormal cytoarchitecture. Golgi-Cox studies showed abnormal arborization of Purkinje cells in each experimental group. They were arbitrarily classified into inverted Purkinje cells, lying Purkinje cells, T-shaped Purkinje cells, and poorly arborized Purkinje cells. The earlier the postnatal treatment the more severe were the abnormalities of Purkinje cell dendrite. According to the electron-microscopic study, some glomerular synaptic complexes, which are normally confined to the internal granular layer, were observed even in the molecular layer in groups I, II, and III. Some of the Purkinje cell dentritic spines did not make synapses with parallel fibers in any of the experimental groups. The results indicate that severity of abnormal arborization of Purkinje cells is dependent on the period of destruction of the external granular layer. Formation of heterotopic granule cells was dependent on the destruction of the external granular layer up to day 10 after birth.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 7 (1986), S. 395-404 
    ISSN: 0197-8462
    Keywords: hair receptors ; afferent impulses ; neurophysiology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: There are two possible mechanisms of effects of large electric fields on animals, one caused by the electric field at the body surface and the other caused by the electric current induced inside the body. The purpose of the present experiments was to investigate the former possibility by recording action potentials from afferent fibers innervating various sensory receptors in the cat's hindlimb. Cat hairs were attracted to the upper electrode when exposed to DC electric fields of 180 kV/m or greater, and action potentials were evoked in the afferent fibers innervating G1, G2, and down hair receptors. No action potentials were evoked in afferent fibers innervating type I, type II, field receptors, muscle spindles, or joint receptors. These results indicate that a strong DC electric field induced movement of the hairs, eventually evoked excitation of the hair receptors, but that other receptors located under the skin were not influenced by electric field exposure.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 10 (1989), S. 319-327 
    ISSN: 0197-8462
    Keywords: hairy and hairless skin ; relative permittivity of hair ; AC electric field ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The threshold intensity for detection of an AC electric field was studied in human subjects at several different temperatures and humidities. The dorsum and palm of the hand were exposed to fields, representing hairy and hairless skin, in order to clarify whether hair movement is critical for field detection. Experiments were carried out on human subjects (seven men and four women) during hot humid weather of July-August and dry cool air of October-November. Threshold values obtained in the summer were 30-65 kV/m for the hairy skin on the dorsum of the hand, while for the hairless skin on the palm the threshold was 〉 115 kV/m (highest field available due to limitations of the power supply). During the fall, the threshold was much higher than during the summer. We sought possible reasons for the difference and found that humidity was the main factor. Relative permittivity of woman's hair was then estimated by measuring capacitance of the hairs under dry (35% RH) and wet (85% RH) conditions at 20 °C. The values of relative permittivity obtained under these two conditions differed by several times the average. The differences in detection thresholds may be attributable to the different relative permittivities of the hairs under dry and wet conditions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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