Biomedical subjects

Jean Deschatrette

Publications and source records attributed to Jean Deschatrette.

3 recordsLinked to original sources

PubMed2006

Sinusoidal swinging dynamics of the telomere repair and cell growth activation functions of telomerase in rat liver cancer cells.

Telomerase is a multimolecular complex of reverse transcriptase, RNA template, and regulatory proteins. It has two known functions: catalysis of the addition of [TTAGGG] repeats to telomeric DNA and the activation of various genes controlling cell proliferation. The possible coordination of these two functions is a key issue in understanding the growth of cancer cells. We report long-term changes to this complex system, as shown by specific data analysis methods. We show that the dynamics of the two functions of telomerase are tightly linked, with a change in predominant function every 13-14 weeks. The conservative behavior of this dynamic system probably accounts for the persistent proliferation of cancer cells.

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PubMed2004

Deterministic dynamics control oscillations of bone marrow cell proliferation.

OBJECTIVE: The production of blood cells in vivo, both normal and tumoral, displays oscillatory dynamics. Many cells in long-term cultures also show large amplitude oscillations of proliferative rate. Therefore we examined the proliferation dynamics of mouse bone marrow cells (MBM) and their clonogenic progenitor production (BMP), in order to characterize these dynamics. METHODS: Five Dexter-type cultures of MBM cells and their clonogenic BMP production were examined for up to seven-months periods of time. The recorded time series exhibited a complex pattern of oscillations with variable amplitudes. We previously reported a method that allowed analysis of such nonlinear dynamics of hepatoma cell proliferation. We applied this method, based on the two-dimensional recurrent representation of data, to analyze the fluctuations of bone marrow cells proliferation. RESULTS: The proliferation rate of mouse bone marrow cells shows large amplitude oscillations every 2 to 3 weeks. Mathematical analysis revealed a deterministic mechanism that controls all proliferation local maxima of MBM cells. Dynamics for progenitor production resembled that of parental cells. This reflects a predominant negative feedback on bone marrow cell proliferation. CONCLUSION: These dynamics were opposite of that previously described for hepatoma cells where the dominant control is applied to the local minima (troughs of proliferation). Therefore, the complex system of cell proliferation is controlled by a bipolar mechanism, with a predominant dampening command depending on the cell type. We propose that the dominant dampening control of local maxima in bone marrow cells protects the stock of stem cells.

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PubMedDate not supplied

Reversal of hepatoma cells resistance to anticancer drugs is correlated to cell proliferation kinetics, telomere length and telomerase activity.

BACKGROUND: Clinical and experimental observations indicate that resistance to anticancer drugs may be spontaneously reversible over time. MATERIALS AND METHODS: This work is a mathematical and statistical analysis of the relationship, during a 9-month experiment, between the resistance of repeatedly re-seeded hepatoma cells to methotrexate (MTX) or to cisplatin (cisP) and untreated cell proliferation, telomere length and telomerase activity. RESULTS: All variables showed complex oscillations, as previously published. In this work, cell proliferation was modelized by the logistic model, and the proliferation rates (a-values) together with their variations (va-values) were calculated. CONCLUSION: Significant correlations were discovered between cell resistance to treatments and a-values, va-values, telomere length and telomerase activities. These results open new insights into the handling of chemotherapy in the treatment of cancers.

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