Cell membrane functions

The possibility of active transport of substances across membranes had first been pointed out in the middle of the nineteenth century by the physiologist Emil Heinrich du Bois-Reymond, a German of Swiss descent. The ability to accomplish active transport of ions and uncharged molecules in the direction of increasing electrochemical potentials is one of the most important features of cell membrane function. The law of independent ionic migration as a rule is violated in active transport. 

Generalized disruption of cell membrane function in fishes by anthracene (McCloskey and Oris 1993)... 

Solarization process increases soil temperatures up to levels lethal to many plant pathogens and pests and, therefore, direct thermal inactivation is the most important and normally expected mechanism. Some studies on the biochemical bases of sensitivity of organisms to high temperatures hypothesized that heat sensitivity is related to small differences in cell macromolecules, leading to a lethal increase of intra-molecular hydrogen, ionic, and disulfide bonds (Brock 1978). Sundarum (1986) suggested a reduced cell membrane function beyond an upper limit fluidity... 

Mechanisms by which ozone might interfere with bactericidal function include an alteration in cell-membrane function that produces a loss in phagocytic ability and is perhaps mediated by lipid peroxides and a decrease in the ability of veolar macrophages to kill phagocytized bacteria. Leukocytes in general appear to have a multiplicity of mechanisms for destroying ingested bacteria. 

Daptomycin (15 Cubicin ) Daptomycin (15) Lipopeptide NP Microbial Antibacterial Disrupts multiple aspects of bacterial cell membrane function 211-225... 

Alternatives to FDG for detecting viable myocardium are based on myocardial leak of creatine phos-phokinase, inosine, inorganic phosphate [100-103] due to impaired cell membrane function induced by ischemia and/or necrosis. Therefore, the use of a potassium analogue reflecting myocardial cellular membrane function and the myocardial potassium space represents an alternative for a quantitative assessment of... 

Mechanism of Action. Terbinafine inhibits a specific enzyme (squalene epoxidase) that is responsible for sterol synthesis in the fungal cell membrane. This action impairs cell wall synthesis, with subsequent loss of cell membrane function and integrity. Inhibition of this enzyme causes squalene to accumulate in the fungal cell, which can also impair cell function and lead to death of the fungus. 

The presenee of the positively-eharged nitrogen atom in the hybrid molecule provides for the antioxidant adherenee to the surface of a cell membrane and its fixation in a eertain place by means of the lipophilic long-chained alkyl fragment Ri. Sueh a stmcture ensures the targeted use of the antioxidant and favors the inhibition of pathological processes in eell, e.g. intensification of LPO and disorders of cell membranes functions. 

Trichothecenes inhibit synthesis of protein, RNA and DNA as well as mitochondrial and electron transport chain function stimulate lipid peroxidation alter cell membrane function induce apoptosis modulate immune responses activate mitogen-activated protein kinases (MAPKs) and induce gene expression of numerous chemokines and cytokines and alter neurotransmitter levels. 

Some biological effects may be mediated by reaction of the epoxy groups of trichothecenes with sulfhydryl groups on enzymes and binding of certain trichothecenes to membrane components. T-2 toxin rapidly affected glucose, nucleotide and amino acid transporters as well as calcium/ potassium channel activities in vitro indicating alteration of cell membrane functions independent of protein synthesis inhibition (Brunner and Morris, 1988). In pigs, DAS was... 

Bunner, D.L., Morris, E.R. (1988). Alteration of multiple cell membrane functions in L-6 myoblasts by T-2 toxin an important mechanism of action. Toxicol. Appl. Pharmacol. 92 113-21. 

Other disorders of red cells include problems of cell membrane functioning, e.g., hereditary spherocytosis. 

Trans-Isomers and Cancer A study conducted in postmenopausal women suggested an association between risk of breast cancer and the level of hydrogenated oil derived mono-frawi-fatty acids was stored in the adipose tissue (221). It was also found that frawi-fatty acid might cause colorectal neoplasia by interfering with the cell membrane function or eicosanoid metabolism (222). Increased adenoma prevalence was associated with the consumption of sweetened baked goods, oils, and condiments. 

The mechanism of proximal tubule toxicity following administration of mercuric chloride has been extensively studied. However, the key sequence of events leading to cell death remains to be determined with certainty. Mercuric ions induce mitochondrial toxicity, alter cell membrane function, disrupt cell calcium homeostasis and cause changes in membrane phospholipid composition. Binding of mercuric ions to enzymatic sulfhydryl groups and ischemia-induced mitochondrial toxicity have been proposed as the basic mechanisms leading to these cellular effects and ultimately to cell death. 

W. S. Park and Y. S. Chang, Effects of Decreased Cerebral Perfusion Pressure on Cerebral Hemodynamics, Brain Cell Membrane Function, and Energy Metabolism During the Early Phase of Experimental Escherichia coli Meningitis in the Newborn Piglet, Neurological Res., 21(3), 345-367... 

Disruption of cell membrane function Azole and polyene antifungal agents... 

Drug molecules act as a spacer in such a structure causing a destabilisation of the lipid mosaic. The modification of the fluidity of the model membrane is an important factor for cell membranes functions (Figure 21). 

The importance of lipid mesomorphic tendencies on cell membrane function has also been suggested by studies in which the lipid composition of cells has been varied. Such experiments are problematic because cells maintain regulatory apparatus that makes it difficult to alter the biomembrane lipid composition in a controlled manner. Furthermore, for eukaryotes, it is hard to obtain the pure membrane fractions of a single organelle membrane such as are required for meaningful determinations of the lipid compositions of particular membranes. In the case of bacteria, it is difficult to obtain pure plasma membrane fractions without cell wall contamination. However, my-coplasmas with only a single plasma membrane allow unambiguous determination of the overall plasma membrane composition. 

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