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  • 1985-1989  (2)
  • Estrogen  (1)
  • Rarefaction and compression  (1)
  • somatomedins  (1)
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Material
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  • 1985-1989  (2)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Impaired estrogen-induced uterine insulin-like growth factor-I gene expression in the streptozotocin diabetic rat (1988)
    Springer
    Diabetologia 31 (1988), S. 842-847 
    Details
    ISSN: 1432-0428
    Keywords: Estrogen ; somatomedins ; streptozotocin ; diabetes ; uterine growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Circulating somatomedin-C/insulin-like growth factor-I levels are low in the diabetic rat and unresponsive to exogenous growth hormone. However, the nature of this defect in growth hormone action remains unclear and there is little data on insulin-like growth factor-I gene expression in response to other stimuli and in non-hepatic tissues where insulin-like growth factor-I may have important paracrine and/or autocrine actions. We have previously shown that 17-beta estradiol stimulates uterine insulin-like growth factor-I expression in the ovariectomised rat. In this report uterine and hepatic insulin-like growth factor-I gene expression have been examined in the streptozotocin-diabetic rat. Serum insulin-like growth factor-I concentrations were significantly reduced in diabetic rats compared to normal rats (0.72±0.08 vs 1.23±0.05U/ml, p〈0.0005) and hepatic insulin-like growth factor-I mRNA abundance was similarly reduced in diabetic rats to 49±5% of that seen in non-diabetic intact rats (p〈0.005). In contrast, uterine insulin-like growth factor-I mRNA abundance was not significantly reduced in diabetic rats compared to control rats (76±12%, p = NS). Although both diabetic and non-diabetic rats demonstrated a significant increase in uterine wet weight following a single injection of 17-beta estradiol the increase in uterine insulinlike growth factor-I expression was significantly less marked in diabetic rats. Acute administration of insulin together with estradiol had no significant effect on serum insulin-like growth factor-I concentrations or hepatic insulin-like growth factor-I mRNA abundance; however, the uterine insulin-like growth factor-I response was significantly (p〈0.01) augmented. The observations reported here demonstrate that hepatic insulin-like growth factor-I gene expression is markedly reduced in the diabetic rat and that the estradiol-induced uterine insulin-like growth factor-I response is significantly diminished, consistent with the hypothesis that there is a defect in insulin-like growth factor-I gene activation in the diabetic rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00277488
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    A mathematical analysis of small mammal populations (1987)
    Springer
    Journal of mathematical biology 25 (1987), S. 263-274 
    Details
    ISSN: 1432-1416
    Keywords: Population biology ; Nonlinear renewal theory ; Population waves: synchronization ; Rarefaction and compression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Populations of Microtus montanus, the montane vole, have been extensively studied. It is known that their reproductive activity is closely linked to the availability of the chemicals in growing plants. We use a mathematical model here to study how the length of the vegetative season and the natural reproduction rhythm of voles are involved in the long term dynamics of the population numbers. In particular, we use data obtained from Timpie Springs, Utah, and from Jackson Hole, Wyoming, to formulate a model. The novelty of this model is its use of littering curves that highlight the temporally discrete nature of vole reproduction. The model shows how the timing of the vegetative season can influence vole population sizes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00276436
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
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