Cells and Their Membranes

Ahir, A, Guo, L, Hussain, AA, and Marshall, J, 2002. Expression of metalloproteinases from human retinal pigment epithelial cells and their effects on the hydraulic conductivity of Bruch s membrane. Invest Ophthalmol Vis Sci 43, 458-465. 

Formation of Na+, K+-ATPase carrier molecules in the basolateral membrane of the tubular epithelial cells (promotes extrusion of Na+ ions from the cells and their movement into plasma by way of peritubular capillaries enhances the concentration gradient for passive diffusion through Na+ channels in the luminal membrane)... 

The steps of apoptosis are distinct from those of necrosis which is a nonprogramed form of cell death in response to injury, in which the cell swells and bursts, causing inflammation. Apoptosing cells form a tight sphere and their membranes undulate, resulting in bulges that form blebs. The nuclear membrane breaks, and endonucleases clip chromosomes where the DNA is exposed from protective proteins. This occurs at 180-base... 

Another family of cell adhesion molecules, the integrins, are the components of plasma membranes responsible for maintaining the link between cells and their extracellular associations. This link is not only mechanical but allows communication. 

Most direct toxins entering the alveoli primarily affect Type I cells and their associated capillary endothelial cells. After acute injury, the epithelium and/or underlying capillary endothelial cells may swell and disrupt, distort, or lose their connections with others, leaving large areas of basement membrane uncovered. This allows fluid to move into the alveolar lumen from capillaries, with subsequent pulmonary edema. 

PDZ domains were first identified in proteins of postsynaptic cells and their designation comes from their occurrence in the proteins PSD-95, DlgA and ZO-1 (see Saras and Heldin, 1996). In the meantime, PDZ domains have been found in many other proteins, particularly in proteins that form structures in the cell membrane (e.g. in ion channels) and in signal proteins (review Craven and Brett, 1997). PDZ domains recognize short peptide sequences with a C-terminal hydrophobic residue and a free carboxyl group, such as the E(S/T)DV motif at the C terminus of certain subunits of ion channels. 

Stratum basale is a single layer composed of stem cells and their derivative cells. It is attached to the basement membrane by hemidesmo-somes.48 The cells in this layer are columnar or cuboidal in shape and characterized by large nuclei (high nuclear-cytoplasmic ratio) and keratin filaments (tonofilaments). The basal layer contains keratins K14 and K15, melanocytes (which are pigment-forming cells), Langerhans... 

Parenchymal cells (PC), or hepatocytes, originate from epithelial cells and represent most of the total number of liver cells (65%). Because of their relatively large size, hepatocytes are microscopically clearly visible after staining liver sections with hematoxylin and eosin (HE). Also, the hepatocytes store glycogen, which can be identified histochemically with periodic acid-Schiff (PAS) reagent. The hepatocytes are primarily responsible for the uptake of endogenous products and xenobiotics at the sinusoidal membrane of the cell and their subsequent metabolism and excretion into bile by means of the canalicular membrane. 

In experimental stroke, the zone of dense ischemia leads to the rapid exhaustion of substrates, particularly oxygen and glucose. The impaired energy yield cannot maintain the ion pumps so that cells loose their membrane potential (anoxic depolarization of glia and neurons). As a consequence, volt-... 

The activities of many enzymes are affected by fluorides (5) or by ozone (03) and peroxyacetyl nitrate (PAN) (6). Cells and their constituents, such as mitochondria, chloroplasts, or cell membranes, are structurally or functionally abnormal after exposure to many pollutants (7, 8, 9). With leaves, the most commonly reported event is the appearance of lesions (10,11,12), but altered gaseous exchange (13) and levels of metabolites (14) have also been found. Many of the events associated with plants can be classified as a change in their size or shape or as an accumulation of a pollutant when it is fluoride (15) or a metal (16, 17). 

Spicule formation takes place within the intracellular environment. The spicules, however, are much larger than individual cells. This is achieved by many cells fusing their membranes to enclose an extended space (called a syncytium) (Fig. 1.9). Spicule formation takes place inside a membrane delineated vacuole within this space [70, 71]. The size and the shape of the syncytium constantly increase and change during growth of the spicule [72, 73]. In fact, a freeze-fracture TEM study of the relation between the membrane and the growing spicule shows that the membrane is always juxtaposed to the spicule surface. There is thus no bulk solution within which the spicule forms [74], Thus spicule... 

Filtration. Filtration can include filter presses, rotary drum vacuum filters (RDVF), belt filters, and variations on synthetic membrane filtration equipment, such as filter cartridges, pancake filters, or plate and frame filter presses. These processes typically operate in a batch mode when the filter chamber is filled up or the vacuum drum cake is exhausted, a new batch must be started. This type of filtration is also called dead-end filtration because the only fluid flow is through the membrane itself. Due to the small size of cells and their compressible nature, typical cell cakes have low permeability and filter aids, such as diatomaceous earths, perlite, or other mined materials are added to overcome this limitation. Moreover, the presence of high solids and viscous polymeric fermentation byproducts can limit filtration fluxes without the use of filter aids. 

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