Based on dynamical systems theory, we propose a mechanism for cell differentiation with regulation of populations of each cell type by taking simple cell models with gene expression dynamics. By incorporating several interaction kinetics, we found that the cell models with a single intracellular positive-feedback loop exhibit a cell fate switching, with a change in the total number of cells. The number of a given cell type or the population ratio of each cell type is preserved against the change in the total number of cells, depending on the form of cell-cell interaction. The differentiation is a result of
bifurcation of cell states via the intercellular Selleck Ro 61-8048 interactions, while the population regulation is explained
by self-consistent determination of the bifurcation parameter through cell-cell interactions. The relevance of this mechanism to development and differentiation in several multicellular systems is discussed. (C) 2008 Elsevier Ltd. All rights reserved.”
“The increasing incidence of melanoma and the lack of effective therapy have prompted the development of new vectors, more specific to the pigmented tumor, for early detection and treatment. Targeted agents have to exhibit a rapid, high tumor uptake, long tumor retention and rapid clearance from nontarget organs. This PSI-7977 joint work presents results obtained with a new melanoma targeting agent, [I-125]-N-(4-dipropylaminobutyl)-4-iodobenzamide or [I-125]BZ18. After labeling with a high specific
activity, the biodistribution of the compound was investigated in two animal models, the mouse and the sheep. Melanotic tumor retention was observed lasting several days. We visualized the internalization of the agent inside the melanosomes by secondary ion mass spectroscopy imaging, we measured the affinity constants of [I-125] BZ18 on a synthetic melanin model and we demonstrated a radiotoxic effect of this labeled agent on B16F0 melanoma cell Culture due to its cellular Rolziracetam internalization.
From this work, [I-125]BZ 18 appeared a promising rnelanorna targeting agent in the nuclear medicine field. (C) 2008 Elsevier Inc. All rights reserved.”
“A previously introduced degenerate diffusion-reaction model of biofilm growth and disinfection is extended to account for convective transport of oxygen and disinfectants in an aqueous environment. To achieve this in a computationally efficient manner we employ a thin-film approximation to the (Navier)-Stokes equations that can be solved analytically. In numerical experiments, we investigate how the convective transport of nutrients and disinfectants due to bulk flow hydrodynamics affects the balance between growth and disinfection processes. It is found that the development of biofilms can be significantly affected by the flow field even at extremely low Reynolds numbers.