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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of mathematical biology 25 (1987), S. 275-288 
    ISSN: 1432-1416
    Keywords: Chemical mass recruitment ; Quality recruitment ; Damping ; Ants ; Delayed differential equation ; Functional differential equation ; Monotonicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract Ant species on a “high evolutionary level” have evolved chemical recruitment systems such as mass recruitment or quality recruitment. The recruitment process from the nest to a food source may be damped by crowding effects at the source. For four patterns of behavior (mass/quality recruitment; with/without damping) we study mathematical models for the time development of the quantity of food at the source. Each of the models can be reduced to a second order time-delayed differential equation which will be studied in the equivalent form of a first order (nonlinear) functional differential equation. We discuss the complete exploitation of a given source. In case of mass recruitment there possibly remains a threshold quantity of food not worth exploiting. However, every source will be exploited completely (in finite time) provided that the volatility of the trail pheromone is small compared with the exploitation activities of the colony and the distance from the nest to the source. In addition, for the damped models the “capacity” of the crowded source must be large compared with the initial quantity of food offered. The efficiency of the exploitation activities of some species allows conclusions on their evolutionary development.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 133 (1995), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In the present study, we investigated the expression of the tumour suppressor protein p53 in 1 primary and 43 metastatic malignant melanomas by immunohistochernistry, and correlated the findings with clinicopathological parameters such as histological melanoma subtype, thickness of primary melanomas (Breslow thickness) and patient outcome.In primary melanomas, the polyclonal anti-p5 3 antibody CM-1 detected immunoreactivity in 70% of the lesions, predominantly in the cytoplasm. Signals were observed in this cellular compartment in 57% of the melanomas, whereas in 32% nuclear p53 over-expression was detected. Immunohis-tochemistry, using the monoclonal antibody DO-1, revealed lower staining frequencies. However, both antibodies showed congruent results in approximately 80% of the cases. Overall, immuno-reactivity was observed in 73% of superficial spreading melanomas, but only in 52% of lentigo maligna melanomas. This difference (P〈0.001) was mainly due to a lower frequency of cytoplasmic immunoreactivity (P〈0.002). There was no difference with respect to cytoplasmic and nuclear immunoreactivity between thin (〈1 mm thickness) and thicker primary melanomas. Staining frequencies detected in metastatic lesions seemed to be lower than in primary tumours. In 103 primary melanomas, follow-up data for at least 5 years were available. In 71% (54 of 76) of the primary melanomas which did not recur, and in 78% (21 of 27) of tumours with subsequent metastases, p53 over-expression was detected by CM-1. However, this difference was not statistically significant.The results of the present study indicate that immunoreactivity to anti-p53 antibodies is a common observation in malignant melanomas, with staining signals predominantly found in the cytoplasm of cells. The observation of similar staining frequencies in thin, thick and metastatic lesions indicates that p53 over-expression is an early event in the pathogenesis of malignant melanoma. However, the immunohistochemical detection of p53 in primary melanomas is not related to prognosis.
    Type of Medium: Electronic Resource
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