Chemotactic networks

Katz LM, Bianco C (2003) West Nile vims. N Engl J Med 349 1873-1874 author reply 1873-1874 Kim CH (2005) The greater chemotactic network for lymphocyte trafficking chemokines and beyond. Curr Opin Hematol 12 298-304... 

Kim CH. The greater chemotactic network for lymphocyte trafficking chemokines and beyond. Curr Opin Hematol 2005 12(4) 298-304. 

Modeling Spatial and Temporal Dynamics of Chemotactic Networks... 

Since cellular immunity results in the release of chemotactic lymphocytes that in turn enhance phagocytosis, a deficiency in cellular immunity may also result in chronic infections. Cellular immunity is mediated by T cells, macrophages, and NK cells involved in complex compensatory networks and secondary changes. Immunosuppressive agents may act directly by lethality to T cells, or indirectly by blocking mitosis, lymphokine synthesis, lymphokine release, or membrane receptors to lymphokines. In addition, cellular immunity is involved in the production and release of interferon, a lymphokine that ultimately results in blockage of viral replication (Table 15.4). Viruses are particularly susceptible to cytolysis by T cells since they often attach to the surface of infected cells. Thus, immunosuppression of any of the components of cellular immunity may result in an increase in protozoan, fungal, and viral infections as well as opportunistic bacterial infections. 

Chemotactic behavior and the control of metabolism are examples of complex phenotypes with complicated networks and pathways of signaling and other proteins. In the case of metabolism, the rules describing complex, context-dependent processes depend dir ectly on thermodynamics and kinetics. Analyses of metabolic flux show the principle of distributed control governing the phenotype in mammalian and bacterial systems interacting with the environment, and explain the robust nature of these networks. 

Die output of individual flagellai motors in E. coli was measured as a function of the intracellular concentration of the chemotactic signaling protein. The concentration of this molecule, fused to GFP, was monitored with fluorescence coiielation spectroscopy. Motors from different bacteria exhibited an identical steep input-output relation, suggesting that they actively contribute to signal amplification in chemotaxis. Uiese experimental studies can be extended to quantitative in vivo studies of other biochemical networks. ... 

The chemotactic response of Dictyostelium cells, and certainly also of other amoeboid cells such as neutrophils, is superimposed on the spontaneous dynamics of the cytoskeleton, in particular of the actin system in the cell cortex. This system consists basically of a network of bundled actin filaments, which are continuously turned over by polymerization and depolymerization. In Dicty-ostelium the polymerization rates of actin filaments constituting the network are in the order of 3 pm/s, corresponding to the... 

At the onset of development, Dictyostelium cells start to produce and respond to the small molecular chemoattractant cAMP [146]. The details of the inner workings of the oscillatory cAMP-signaling network are not directly relevant to the description of the chemotactic response and will only be touched on briefly. In a field of cells, periodic cAMP waves emerge which coordinate the formation of centers towards which the cells move by chemotaxis. On the level of an individual cell, the... 

The role that chemokines play in the localization of blood or lymphatic-borne-T lymphocytes near lymph nodes is incompletely understood. Transgenic mice that lack expression of specific chemokines have not been illustrative, suggesting that the process is the result of stimulation by multiple chemokines with overlapping receptor affinity or that the essential chemokine-receptor complex has not yet been identified. Ligand and receptor redundancy is common in chemokine networks. However, after the T lymphocyte has responded to the complex array of chemotactic signals and arrived at the lymph node, the events by which it migrates through the endothelium into the lymph node itself are well characterized. 

Standiford TJ, Kunkel SL, Basha MA, Chensue SW, Lynch JP, Toews GB, West-wick J, Stiieter RM. Interleukin-8 gene expression by a pulmonary epithelial cell line a model for cytokine networks in the lung. J CUn Invest 1990 86 1945-1953. Warren KS. The granulomatous response. Immunol Rev 198 261 189-198. Stricter RM, Kunkel SL, ShoweU H, Remick DG, Phan SH, Ward PA, Marks RM. Endothelial cell gene expression of a neutrophil chemotactic factor by TNF, LPS, and lL-1. Science, 1989 243 1467-1469. 

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