Cell membranes, properties

Samson, G., and Visser, S. S. (1989). Surface-active effects of humic acids on potato cell membrane properties. Soil Biol. Biochem. 21,343-347. 

Hu, W., Jones, P. D., De Coen, W., Newsted, J. L., Giesy, J. P. Alterations in cell membrane properties caused by perfluorinated compounds. Comp. Biochem. Physiol C Pharmacol, 135C 77-88 (2003). 

Intermingled with the neurons in the brain are a variety of other cell types. The most common of these satellite cells are glial cells. These make up virtually about one half of the total volume of the brain and exist in several forms such as astrocytes, oligodendrocytes, and Schwann cells. Membrane properties of glial cells exhibit fundamental differences from neurons, the chief difference being their passive nature. Unlike neurons, most glial cells are not excitable and do not fire action potentials. Membrane potential measurements of... 

V.Z.Lankin, Lipid peroxides and atherosclerosis. Hypothesis the role of cholesterol and free radical lipid peroxidation in altering cell membrane properties during hyprecholesterolemia and atherosclerosis, Kardiologiia (Cardiology) 20 (1980) 42-48. [Article in Russian]... 

Current research is focusing on excitatory and inhibitory neurotransmitters, secondary messengers, neuroendocrines, and neuropeptides. Areas of receptor research include subtypes of central and peripheral GABA receptors, and dopamine receptor subtypes. Cell membrane properties and ion channels for sodium potassium and calcium are also being investigated. 

Hence, physiologically active BSs (HBR and BB) activated protein synthesis in wheat leaves, increased stress resistance of the protein synthesizing system and modified cell membrane properties. 

In summary, we found significantly lower phase angle values for Nigerian children with SCD compared with healthy controls. These decreases could be due to the presence of a malnourished state or to specific alterations in cell membrane properties, such as lipid content. We propose that impedance analysis, specifically the determination of phase angle, could be used to monitor any interventions such as fatty acid supplementation aimed at addressing the abnormalities in cell membranes that occur in SCD. 

The primary site of action is postulated to be the Hpid matrix of cell membranes. The Hpid properties which are said to be altered vary from theory to theory and include enhancing membrane fluidity volume expansion melting of gel phases increasing membrane thickness, surface tension, and lateral surface pressure and encouraging the formation of polar dislocations (10,11). Most theories postulate that changes in the Hpids influence the activities of cmcial membrane proteins such as ion channels. The Hpid theories suffer from an important drawback at clinically used concentrations, the effects of inhalational anesthetics on Hpid bilayers are very small and essentially undetectable (6,12,13). 

Polyethers. Antibiotics within this family contain a number of cycHc ether and ketal units and have a carboxyHc acid group. They form complexes with mono- and divalent cations that ate soluble ia aoapolar organic solvents. They iateract with bacterial cell membranes and allow cations to pass through the membranes causiag cell death. Because of this property they have been classified as ionophores. Monensia, lasalocid, and maduramicia are examples of polyethers that are used commercially as anticoccidial agents ia poultry and as growth promotants ia mmiaants. 

A chemical must have certain physicochemical properties to elicit an endocrine disrupting effect. For example, the ability to enter the body and to cross the cell membrane into the cellular medium requires a degree of lipophilicity. Fipophilic potentials may be compared by reference to the chemical s octanol-water coefficient (usually expressed as log K ). This property, together with molecular size and chemical structure, has an important influence on the bioacciimiilation... 

Ren, X. Springer, T. E. and Gottesfeld, S. (1998). Direct Methanol Fuel Cell Transport Properties of the Polymer Electrolyte Membrane and Cell Performance. Vol. 98-27. Proc. 2nd International Symposium on Proton Conducting Membrane Euel Cells. Pennington, NJ Electrochemical Society. 

Due to their physicochemical properties trace amines can pass the cell membrane to a limited extent by passive diffusion, with the more lipophilic PEA and TRP crossing membranes more readily than the more polar amines TYR. and OCT. In spite of these features, trace amines show a heterogeneous tissue distribution in the vertebrate brain, and for TYR. and OCT storage in synaptic vesicles as well as activity-dependent release have been demonstrated. So far, trace amines have always been found co-localized with monoamine neurotransmitters, and there is no evidence for neurons or synapses exclusively containing trace amines. 

Fluorescein absorbance is sensitive to pH. This property is utilized to measure cytosolic pH changes. Fluorescein derivatives that contain esters on the carboxyl groups have been constructed. These compounds partition through the cell membrane and, once inside the cell, the esters are cleaved by nonspecific esterases in the cytosol, leaving free carboxyl groups thus the probe cannot diffuse out of the cell (or at least does so slowly). Commonly used derivatives are 6-carboxyfluorescein (21-23) and the more recently developed probe 2, 7 -bis(2-carboxyethyl)-5(and-6)-carboxyfluorescein (13, 24,25). 

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