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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 329 (1985), S. 222-226 
    ISSN: 1432-1912
    Keywords: Blood pressure ; Serotonin ; Sympathetic nerve activity ; Cross-circulation ; Central nervous system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The possible central regulation of cardiovascular system by serotoninergic neurones was investigated in rats by using a cross-circulated head preparation. Intracarotid injections of serotonin (5-HT, 0.1–10 μg) consistently produced neurally mediated vasodepression in the recipient body. Although intravenous injections of 5-HT (0.1–1 μg) caused similar depressor responses, larger doses (5–10 μg) caused biphasic responses, consisting of vasodepression followed by a sustained pressor response. Despite the biphasic blood pressure responses, sympathetic nerve activity was consistently reduced by the intravenous 5-HT. Bilateral vagotomy abolished the vasodepressor responses to intravenous injections of 5-HT (10 μg) and made the responses purely pressor, but the vasodepressor responses to intracarotid injections of 5-HT (10 μg) were largely unaffected. Following destruction of central noradrenergic neurones by intracerebroventricular injections of 6-hydroxydopamine, the vasodepressor responses to intracarotid 5-HT (1–10 μg), but not to the intravenous 5-HT, were significantly reduced. These results suggest that intravenous injections of 5-HT reduce nerve activity by affecting the reflex mechanism via the vagus nerves. On the other hand, the vasodepression and reduction of the nerve activity by the intracarotid injections appears to be of central origin, and the vasodepression could be mediated via noradrenergic mechanisms in the brain.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-2568
    Keywords: telomere ; telomerase ; telomerase RNA ; esophageal cancer ; cell line ; differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The telomere and the telomerase in human esophageal cancer are not yet completely understood. The regulatory mechanism of telomerase activity and telomere dynamics has drawn considerable attention. It is generally assumed that when telomerase has been activated, no further telomere shortening should ensue; however, a much more complex pattern of telomere dynamics may exist in telomerase-positive cancer cells. A novel human esophageal cancer cell line (KAN-ES) was established and characterized. Using KAN-ES and its serially passaged subclones up to the 55th generation, we determined the alteration of telomere length (TRF), telomerase activity (TA), telomerase RNA expression (hTR), population doubling time, karyotype, and cytokeratin 14 expression during the process of establishing a cancer cell line. We found that the TRF was maintained between 4.0 and 5.0 kb during the serial passages, despite sustained high TA (assessed by an in vitro TRAP assay). No close relationships were found among TRF, TA, and hTR expression. TA and telomere dynamics were not associated with cellular growth ability and differentiation. However, the number of population doublings showed significant correlations with both the TA and doubling times. In conclusion, these dissociations between telomere dynamics and TA support the existence of additional controls on TRF in cancer cells. KAN-ES and its restored subclones should prove a valuable resourse for esophageal cancer research.
    Type of Medium: Electronic Resource
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