The role of alterations in membrane lipid composition in enabling physiological adaptation of organisms to their physical environment.

During the last 16 years an increasing number of studies have indicated a new diagnostic marker of alcohol abuse, unrelated to any of the conventional markers of alcoholism. This marker, now called carbohydrate-deficient transferrin, consists mainly of one or two isoforms of transferrin that are deficient in their terminal trisaccharides. Such isoforms have so far been detected by methods based on charge, i.e., isoelectric focusing, chromatofocusing, and anion-exchange chromatography of various designs combined with immunological detection techniques. This transferrin abnormality measures an accumulated effect of alcohol consumption, appearing after regular intake of 50-80 g of ethanol/day for at least one week and normalizing slowly during abstinence (half-life = about 15 days). To summarize all studies to date, approximately 2500 individuals have been examined, with a total clinical sensitivity of 82% and a specificity of 97%. False-positive results have only occasionally been reported: in a few patients with severe liver disease, usually primary biliary cirrhosis and chronic active hepatitis; in patients with genetic D variants of transferrin; and in patients with (and some carriers of) a recently identified inborn error of glycoprotein metabolism. The mechanism behind the transferrin abnormality is unknown but an acetaldehyde-mediated inhibition of glycosyl transfer has been suggested. Carbohydrate-deficient transferrin may thus offer a new possibility of diagnosing alcohol-related disorders. Its measurement is little affected by other conditions and, contrary to conventional markers of alcohol abuse, is apparently largely independent of concomitant liver disease.

Carbohydrate-deficient transferrin in serum: a new marker of potentially harmful alcohol consumption reviewed.

Publisher Summary This chapter reviews the effects of alcohols on microorganisms. Alcohols are ubiquitous small molecules, which are produced both chemically and as products of microbial fermentation. Accumulation of alcohols in the microbial environment represents a form of environmental stress, analogous to extremes in pH value and temperature. The chapter discusses the action of ethanol and other alcohols on microorganisms, explains several important mechanisms of action. Alcohols have been employed for many years both as a disinfectant and as a preservative. Concentrations of ethanol above 15% result in immediate inactivation of most vegetative organisms, with spores being considerably more resistant. Low concentrations of ethanol also render bacteria more sensitive to inactivation by ionizing radiation and by lipophilic acids. The chapter concludes that the basic actions of alcohols on both eukaryotic and prokaryotic organisms share the same general principles. These effects appear to be dominated by the physicochemical properties of alcohols rather than involving specific receptors. All hydrophobic and electrostatic interactions in the cytosolic and envelope components of cells can potentially be affected. These include membranes, conformations of enzymes and macromolecules, activity coefficients of metabolites, permitivity, ionization potentials, pK values of functional groups, and pH value.

Effects of Alcohols on Micro-Organisms

Lecithin bilayers. Density measurement and molecular interactions

Ethanol, at pharmacologically relevant concentrations of 20 to 100 mM, stimulates gamma-aminobutyric (GABA) receptor-mediated uptake of 36Cl-labeled chlorine into isolated brain vesicles. One drug that acts at GABA-benzodiazepine receptors, the imidazobenzodiazepine Ro15-4513, has been found to be a potent antagonist of ethanol-stimulated 36Cl- uptake into brain vesicles, but it fails to antagonize either pentobarbital- or muscimol-stimulated 36Cl- uptake. Pretreatment of rats with Ro15-4513 blocks the anticonflict activity of low doses of ethanol (but not pentobarbital) as well as the behavioral intoxication observed with higher doses of ethanol. The effects of Ro15-4513 in antagonizing ethanol-stimulated 36Cl- uptake and behavior are completely blocked by benzodiazepine receptor antagonists. However, other benzodiazepine receptor inverse agonists fail to antagonize the actions of ethanol in vitro or in vivo, suggesting a novel interaction of Ro15-4513 with the GABA receptor-coupled chloride ion channel complex. The identification of a selective benzodiazepine antagonist of ethanol-stimulated 36Cl- uptake in vitro that blocks the anxiolytic and intoxicating actions of ethanol suggests that many of the neuropharmacologic actions of ethanol may be mediated via central GABA receptors.

http://science.sciencemag.org/content/sci/234/4781/1243.full.pdf

A selective imidazobenzodiazepine antagonist of ethanol in the rat

Ethanol in vitro increased the fluidity of spin-labeled membranes from normal mice. Membranes from mice that had been subjected to long-term ethanol treatment were relatively resistant to this fluidizing effect. The data suggest that the membranes themselves had adapted to the drug, a novel form of drug tolerance.

https://science.sciencemag.org/content/sci/196/4290/684.full.pdf

Drug tolerance in biomembranes: a spin label study of the effects of ethanol

Increased cholesterol content of erythrocyte and brain membranes in ethanol-tolerant mice

Disordering of brain and erythrocyte membranes by ethanol in vitro was measured by ESR using 5-doxylstearic acid as spin label. Synaptosomal plasma membranes and erythrocyte membranes were isolated from two lines of mice developed, by selective breeding, for differential sensitivity to hypnotic effects of ethanol. Membranes taken from alcohol-sensitive "long-sleep" mice were more strongly disordered by ethanol in vitro than were membranes from alcohol-resistant "short-sleep" mice. Furthermore, within a population of genetically heterogeneous mice, the most ethanol-sensitive animals had the most ethanol-sensitive synaptosomal plasma membranes. In vivo sensitivity of the individual mice was evaluated by measuring brain ethanol levels at a precise behavioral end point, recovery from ataxia. The data extend our previous observations of correlations between in vitro and in vivo effects of ethanol and suggest that membrane disordering may be a primary mechanism of acute effects of ethanol.

Ethanol disordering of spin-labeled mouse brain membranes: correlation with genetically determined ethanol sensitivity of mice.

Several workers have shown that phase transition-related changes in membrane lipids have a profound effect on membrane-solvated protein function. This phase transition temperature dependence has been explained as resulting from the formation of lateral phase separations within the membrane bilayer. The present study demonstrates that a clinical concentration of an inhalation anesthetic produces changes in both the phase transition temperature of pure lipid bilayers and the lateral phase separation temperature of mixed dipalmitoyl- and dimyristoylphosphatidylcholine bilayers of a magnitude sufficient to influence protein function. It is further shown that pressure is able to antagonize the effect of the anesthetic on these transition temperatures. It is proposed that anesthetic action within nerve membranes may be the result of changes in the lateral phase separation-controlled environment of the membrane-solvated proteins essential to nerve function.

https://www.pnas.org/content/pnas/72/1/210.full.pdf

The antagonistic effect of an inhalation anesthetic and high pressure on the phase diagram of mixed dipalmitoyl-dimyristoylphosphatidylcholine bilayers

Pressure-induced elevation of phase transition temperature in dipalmitoylphosphatidylcholine bilayers: An electron spin resonance measurement of the enthalpy of phase transition

Jane H. Chin

Papers

Drug tolerance in biomembranes: a spin label study of the effects of ethanol

Increased cholesterol content of erythrocyte and brain membranes in ethanol-tolerant mice

Ethanol disordering of spin-labeled mouse brain membranes: correlation with genetically determined ethanol sensitivity of mice.

The antagonistic effect of an inhalation anesthetic and high pressure on the phase diagram of mixed dipalmitoyl-dimyristoylphosphatidylcholine bilayers

Pressure-induced elevation of phase transition temperature in dipalmitoylphosphatidylcholine bilayers: An electron spin resonance measurement of the enthalpy of phase transition