Cell contraction

RatL, Status of Gasificatiou Demoustratiou Plants, Froc. 2d Annu. Fuel Cells Contract Review Mtg., DOE/METC-909(y6112, p. 91. 

The potent antidiuretic hormone AVP orchestrates the regulation of free water absorption, body fluid osmolality, cell contraction, blood volume, and blood pressure through stimulation of three G-protein-coupled receptor subtypes Vi-vascular types a and b, V2-renal, and V3-pituitary. Increased AVP secretion is the trademark of several pathophysiological disorders, including heart failure, impaired renal function, liver cirrhosis, and SIADH. As a consequence, these patients experience excess water retention or inadequate free-water excretion, which results in the dilution of sodium concentrations, frequently manifesting as clinical hyponatremia (serum sodium concentration <135mmol/L). This electrolyte imbalance increases mortality rates by 60-fold. Selective antagonism of the AVP V2 receptor promotes water... 

More quantitatively, it appears to a first approximation that the unit cell contraction of a compound containing Mn2+, Co2+, Ni2+, or Fe2+, relative to the isomorphous Mg+2 compound, is a linear function of the Ax of the metal-ligand bond if we neglect selenides and tellurides. Inclusion of these more covalent compounds indicates a greater dependence on Ax. 

Figs. 2 and 4 show that the cell contraction is almost the same for Mn2+ and Co2+ as covalency increases from fluorides to iodides or sulfides (thus the total 3d + 4s covalence is identical for both). However, the covalence of the 3d orbitals is 2 to 3 times smaller for Mn2+ (see Figs. 14a and 14b). Therefore Mn2+—X covalence results mostly from spin transfer to empty 4 s orbitals, unlike Co2+. This agrees with the conclusion of Rimmer (1964). 

In addition to the displacement of caldesmon, smooth muscle cell contraction requires kinase-induced phosphorylation of myosin. Smooth muscle has a unique type of myosin filament called p-light chains which are the target (substrate) for MLCK, but MLCK is only active when complexed with CaCM. Myosin light chain phosphatase reverses the PKA-mediated process and when cytosolic calcium ion concentration falls, CDM is released from CaCM and re-associates with the actin. The central role of calcium-calmodulin in smooth muscle contraction is shown in Figure 7.4. 

Rath, Status of Gasification Demonstration Plants, Froc. 2d Anna. Fuel Cells Contract Review Mtg., DOE/METG-9090/6112, p. 91. jCoal Gasification Guidebook Status, Applications, and Technologies, Electric Power Research Institute, EPRITR-102034,1993, p. 5-28. Ibid.,p. 5-58. 

Histamine-induced edema results from the action of the amine on Hi receptors in the vessels of the microcirculation, especially the postcapillary vessels. The effect is associated with the separation of the endothelial cells, which permits the transudation of fluid and molecules as large as small proteins into the perivascular tissue. This effect is responsible for urticaria (hives), which signals the release of histamine in the skin. Studies of endothelial cells suggest that actin and myosin within these cells contract, resulting in separation of the endothelial cells and increased permeability. 

Blocks outflow of K through K channels. This promotes CH2CH =CHC=CH muscle cell contraction and prolongs the release of neurotransmitters. 

In many cells that respond to extracellular signals, Ca2+ serves as a second messenger that triggers intracellular responses, such as exocytosis in neurons and endocrine cells, contraction in muscle, and cytoslceletal rearrangement during amoeboid movement. Normally, cytosolic [Ca2+] is kept very low (<10-7 m) by the action of Ca2+ pumps in the ER, mitochondria, and plasma membrane. Hormonal, neural, or other stimuli cause either an influx of Ca2+ into the cell through specific... 

The preparation of pure silica MCM-48, using cationic gemini surfactants, followed by a controlled extraction of the surfactant results in materials that have a more narrow pore size distribution than the ones in which the surfactant is removed by calcination. Since no calcination is needed, there is no unit cell contraction and the extraction surfactant can be recrystallized and re-used. 

Oinuma, I., Katoh, H., Harada, A., and Negishi, M. (2003). Direct interaction of Rndl with Plexin-Bl regulates PDZ-RhoGEF-mediated Rho activation by Plexin-Bl and induces cell contraction in COS-7 cells. J. Biol. Chem. 278, 25671-25677. 

A quartz crystal sensor chip was bonded with a microfluidic glass chip for acoustic wave detection (see Figure 7.46). The sensor was operated in the thickness-shear mode (TSM). This has allowed rat heart muscle cell contraction to be studied based on the measurement of the resonant frequency changes [133]. 

Li, P.C.H., Wang, W.J., Parameswaran, M., An acoustic wave sensor incorporated with a microfluidic chip for analyzing muscle cell contraction. Analyst 2003, 128, 225-231. 

In addition to organelles, the cell cytoplasm contains actin filaments that make up the cellular cytoskeleton that controls shape. Myosin and a-actinin are also found in the cytoplasm and are believed to be involved in cell contraction. Other filaments including intermediate filaments, tubulin, calmodulin, and spectrin form networks within the cytoplasm that modify cell and organelle mobility and shape. 

In general, the zeolite-Y crystallographic unit cell contracts with the removal of framework aluminium and this parameter is therefore a rough measure of acid-site... 

Smooth-muscle-cell contraction of the bronchi, narrowing the lumen of the bronchi. This... 

Calciiun is involved in the initiation of smooth muscle and cardiac cell contraction and in the propagation of the cardiac impulse. Actions on cardiac pacemaker cells and conducting tissue are described in Chapter 24. 

Vascular smooth muscle cells. Contraction of these cells requires an influx of calcium across the cell membrane. This occurs through ion chaimels... 

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