Cell influencing factors

Meng S, Kaxiras E (2010) Electron and hole dynamics in dye-sensitized solar cells influencing factors and systematic trends. Nano Lett 10 1238-1247... 

Contraction of muscle follows an increase of Ca " in the muscle cell as a result of nerve stimulation. This initiates processes which cause the proteins myosin and actin to be drawn together making the cell shorter and thicker. The return of the Ca " to its storage site, the sarcoplasmic reticulum, by an active pump mechanism allows the contracted muscle to relax (27). Calcium ion, also a factor in the release of acetylcholine on stimulation of nerve cells, influences the permeabiUty of cell membranes activates enzymes, such as adenosine triphosphatase (ATPase), Hpase, and some proteolytic enzymes and facihtates intestinal absorption of vitamin B 2 [68-19-9] (28). 

It is of interest that proteins termed motility factors (55-70 kD) are secreted by fetal cells and some tumor cells. These proteins act as autocrine factors and stimulate rapid movement by these cells. Motility factors induce the formation of cell processes that are packed with actin filaments and have an increased number of receptors for the matrix proteins laminin and fibronectin. The latter enhance the ability of the cells to bind to the extracellular matrix. Thus, it is likely that motility factors influence the organization of the cytoskeleton through changes taking place at the cell surface (reviewed by Warn and Dowrick, 1989). 

Of probably greater importance is the effect of local concentration gradients. For example, analysis for a given constituent in the entire meat mass does not reflect the real concentration at a given point. For example, DNA is localized in the nuclei and lipid is localized predominantly in the adipose cells. Another factor of potential influence in reaction schemes for nitrite is the fact that polar-nonpolar interfaces are present as a result of structural compartmentalization. In an adipose cell, the lipid is contained as the body of the cell, but it is surrounded by a thin layer of sarcoplasmic protein. Therefore, large surface areas are involved. 

Additional genes and protein receptors are believed to be important in colorectal tumorigenesis. Cyclooxygenase 2 (COX-2), which is induced in colorectal cancer cells, influences apoptosis and other cellular functions in colon cells, and overexpression of the epidermal growth factor receptor (EGFR), a transmembrane glycoprotein involved... 

Kim CH, Broxmeyer HE. In vitro behavior of hematopoietic progenitor cells under the influence of chemoattractants stromal cell-derived factor-1, steel factor, and the bone marrow environment. Blood 1998 91(1) 100-110. 

Raff I am not aware of any example where a limit to cell growth has been demonstrated in vivo. Generally, if you increase the amount of cell growth factor available, cells will get bigger. Thus the levels of extracellular signals can influence cell size in an animal. 

A variety of substrate- and cell-attached factors influence neural development by regulating adhesion properties of cells (see Ch. 7). Interactions occur directly between cells or between a cell and the extracellular matrix (see Ch. 2). The molecules mediating these interactions have been implicated in regulating the specificity and timing of cell-cell adhesion and the consequences on cell morphology and physiology. Hence, they influence the ability of cells not only to migrate but to sort themselves out and to stabilize spatial relationships considered important for the process of differentiation. 

To illustrate the problem consider Fig. 20.13. The aim of the alarm system is to trigger at some minimum safe gap. However, there is a whole range of k-factor values that can occur for that minimum gap which depends on the operating conditions of the cell. For example, factors which influence cell k-factor are its brine temperature and concentration. So to ensure that the gap never reduces below the safe minimum the alarm point must be set at the highest k-factor value which can never be associated with that gap which is the point KA on the diagram. This alarm point will then only be accurate at one set of conditions for all others it will be wrong and will cause the alarm to trigger early when the gap is still above the safe minimum. 

Rate Influencing Factor Porous Catalyst Particle Catalyst Coated Surface Burning of a Droplet of Fuel Cells and Simple Living Creatures... 

The 5 untranslated region (5 UTR) is the region of the mRNA transcript that is located between the cap site and initiation codon. The linkage between methylated G residue and a 5 to 5 triphosphate bridge is known as the cap structure, which is essential for efficient initiation of protein synthesis. The 5 UTR is known to influence mRNA translation efficiency. In eukaryotic cells, initiation factors first interact with the 5 cap structure and prepare the mRNA by unwinding its secondary structure. An efficient 5 UTR is usually moderate in length, devoid of strong secondary structure, devoid of upstream initiation codons, and has AUG within an optimal context. 

Continued reduction or cessation in the formation of oxygen radicals (especially in the area of the mitochondria, nuclear membranes or microsomes) is eventually fatal to the cell. An uncontrolled increase in the cellular formation of superoxide dismutase (as is found in mental disease, trisomy 21, etc.) may also entail dangerous disturbances in the cellular oxygen balance. Moreover, a change in the physicochemical properties of superoxide dismutase under pathological conditions, which may lead to reduced enzyme activity and altered cell compartments, is being discussed as a further influencing factor. 

A previous paper (1) discussed the heat mass transfer and pressure drop contributions of two specific channel structures. The paper showed that the channel shape can significantly influence the catalyst performance by effectively canceling the high surface area with a low cell shape factor. This paper extends this discussion to several other shapes and defines, within these sets, the limits on performance that they could reach under the same coating and testing conditions. 

One recent area of intense research interest is the effects of various thymic factors on the production of soluble mediators (lymphokines) by T cells, most notably T cell growth factor [TCGF or interleukin-2 (IL-2)] and 7 interferon (IFN-7). Interleukin-2 is released by activated T cells and plays a pivotal role in sustaining both proliferative and cytotoxic immune responses. Interferon, on the other hand, augments T cell cytotoxic activity but exhibits antiproliferative effects. It has been demonstrated that Toj can increase IFN-7 production in vitro in human peripheral blood lymphocytes (Svedersky et al., 1982), whereas TF5, but not Taj, has a pronounced effect on increasing IL-2 production (Zatz et al., 1984a). Similar effects have been demonstrated with thymulin in animals (Palacios, 1983). Thus, it is possible that the variable effects of thymic hormones observed to date in human fiinctional assays may be related to differences in their ability to influence lymphokine production. 

Su, K., Stoller, T., Rocco, J., Zemsky, J., and Green, R. (1993). Pre-Golgi degradation of yeast prepro- -factor expressed in a mammalian cell. Influence of cell type-specific oligosaccharide processing on intracellular fate. J. Biol. Chem. 268, 14301-14309. 

Fibronectin and related cell adhesion proteins have been shown to mediate the attachment of many mammalian cells to natural and artificial substrata. Following a presentation of our current understanding of the molecular biology of cell adhesion, factors influencing the attachment and growth of cells on polymeric substrata are discussed. 

In general C diminishes with increasing cell concentration. Factors which increase foaminess diminish C and thus E and Sr too. Systematic investigations dealt with the influence of (i) the cultivation conditions, and (ii) the flotation equipment, construction and operational parameters. 

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