Hemolytic action of surface-active electrolytes

Hemolysis by surfactants--A review

An overview of the use of surfactants for erythrocyte lysis and their cell membrane action mechanisms is given. Erythrocyte membrane characteristics and its association with the cell cytoskeleton are presented in order to complete understanding of the erythrocyte membrane distortion. Cell homeostasis disturbances caused by surfactants might induce changes starting from shape modification to cell lysis. Two main mechanisms are hypothesized in literature which are osmotic lysis and lysis by solubilization even if the boundary between them is not clearly defined. Another specific mechanism based on the formation of membrane pores is suggested in the particular case of saponins. The lytic potency of a surfactant is related to its affinity for the membrane and the modification of the lipid membrane curvature. This is to be related to the surfactant shape defined by its hydrophobic and hydrophilic moieties but also by experimental conditions. As a consequence, prediction of the hemolytic potency of a given surfactant is challenging. Several studies are focused on the relation between surfactant erythrolytic potency and their physico-chemical parameters such as the critical micellar concentration (CMC), the hydrophile-lipophile balance (HLB), the surfactant membrane/water partition coefficient (K) or the packing parameter (P). The CMC is one of the most important factors considered even if a lytic activity cut-off effect points out that the only consideration of CMC not enough predictive. The relation K.CMC must be considered in addition to the CMC to predict the surfactant lytic capacity within the same family of non ionic surfactant. Those surfactant structure/lytic activity studies demonstrate the requirement to take into account a combination of physico-chemical parameters to understand and foresee surfactant lytic potency.

Antithrombogenic heparin-bound polyurethanes

Many kinds of heparin-bound polyurethanes have been developed. Polyurethanes are a family of elastomers displaying better blood-compatibility than other polymeric materials. It is useful to modify this material by heparinization. Several approaches to heparinization have been devised: 1) a general method of heparinization, applicable to all polymeric materials, 2) a heparinization method specific to polyurethanes, and 3) the design of heparinizable polyurethane derivatives. These three approaches are first explained in detail. Then, the antithrombogenic mechanism of the heparinized polymers is discussed. Finally, the interactions of the heparinized polymers with blood coagulation factors, plasma proteins, and platelets are discussed.

Flow microcalorimetry investigation of the influence of surfactants on a heterogeneous aerobic culture

The influence of various surfactants on the biological activity of a mixed aerobic culture has been investigated by using flow microcalorimetry. The response of the culture to the addition of homologous n-alkylcarboxylates (C2 to C16) and n-alkylpyridinium bromides (C11 to C14) has been examined under endogenous and substrate saturation conditions, and inhibitory concentrations (MIC or the concentration which decreased the initial activity (heat flux) of the culture by 50%) were determined for each state. Under both conditions, the n-alkylpyridinium bromides were found to be more toxic than the n-alkylcarboxylates of identical chain length, thus confirming that the head group of the amphiphiles plays an important role in the microbial toxicity of surfactants. The relationship observed between the concentration at which 50% of the activity is lost and the chain length of the surfactant further confirms that cellular toxicity is also dependent on surfactant hydrophobicity. In relation to the biodegradability of surfactants in mixed aerobic cultures, the low concentration effects of n-alkylcarboxylates on endogenous culture were investigated in some detail. There appear to be compounded indications that these surfactants are rapidly metabolized by the microorganisms of the mixed culture, at least for homologs lower than C10.

Effects of nonsteroidal antiinflammatory drugs on the proton exchange reaction between octanol and water: its correlation with their inhibitions of inflammation and prostaglandin synthesis

Effect of various antiinflammatory drugs on proton exchange between octanol OH and water after partition equilibrium between octanol and water at pH 7.4 was examined. These drugs accelerated the proton exchange reaction to different extents. The rate constant of the proton exchange induced by the drugs was well correlated with their biological potencies in inhibiting Carrageenan-induced edema and prostaglandin synthesis, suggesting that proton or electron movement in an apolar environment is very important for exhibition of these biological effects.

Interactions of surface-active alkyltrimethylammonium salts with the plasma membrane of Acanthamoeba castellanii

The interactions of three surface-active alkyltrimethylammonium salts (C12-C16) with the plasma membrane of Acanthamoeba castellanii were studied. The surfactants caused a release of K+ from the cells at premicellar concentrations. The lytic effectiveness of the surfactants increased with an increase in the length of the alkyl chain with about an order of magnitude for every two carbon atoms added to the alkyl chain. Binding studies with the C16 homologue revealed that at a concentration corresponding to 50% release of K+ there were about 1.9 x10(10) molecules bound per cell. At prelytic concentrations the surfactants stimulated phagocytosis and pinocytosis. The mode of action of the surfactants on the plasma membrane of Acanthamoeba castellanii is discussed and it is hypothesized that the stimulation of endocytosis is due to a "fluidizing" effect of the surfactants on the lipid bilayer of the plasma membrane.

The binding of CTAB, a cationic surfactant, to the rat erythrocyte membrane

The adsorption of CTAB (cetyltrimethylammonium bromide) to the rat erythrocyte membrane was studied by determining the electrophoretic mobility of erythrocytes treated with CTAB and by SDS polyacrylamide electrophoresis of membrane proteins from erythrocytes treated with 14C-CTAB. At low concentrations of CTAB there was only a small reduction in the electrophoretic mobility of the erythrocytes. At lytic concentrations the electrophoretic mobility of the erythrocytes was markedly reduced. Alterations at the cell surface were found to be a more likely reason for the reduction in the electrophoretic mobility than interactions between the surfactant and charged groups at the cell surface. Very small amounts of radioactivity were found to be associated with the protein and sialoglycoprotein bands of the polyacrylamide gels. It is suggested that the adsorption of CTAB to the rat erythrocyte membrane does not involve electrostatic interactions between the surfactant and negatively charged groups of the sialoglycoproteins and that membrane proteins do not play a major role in the lytic events.

The haemolytic effect of phallolysin

Phallolysin from the toadstool, Amanita phalloides, is a basic protein that causes direct haemolysis of red cells. The dose-response curve is steep; the pH optimum is in the weakly acid range. The rate of haemolysis increases with the concentration of the lysin, the optimal temperature is 20 degrees C. The percentage haemolysis-time curves are S-shaped. Haemolysis is of the non-osmotic type. Ca2+ is not required but inhibits haemolysis in a concentration-dependent fashion, as do Mg2+ and Zn2+. The red cell sensitivity of various animal species decreases in the following sequence:mouse greater than rabbit = guniea pig greater than rat greater than man greater than dog approximately or equal to pig greater than sheep = cattle. Red cells of cattle and sheep are largely resistant. Phallolysin is virtually not consumed on haemalysis: the amount of haemoglobin released increases with the number of red cells applied; on repeated addition of fresh red cells the haemolysate retains its full activity. Phallolysin is not inhibited by serum, albumin, cholesterol, lecithin, cephalin or sphingomyelin; inhibition by red cell ghosts of phallolysin haemolysis is considerably less than that of digitonin haemolysis. At sublytic concentrations phallolysin, unlike benzalkonium chloride, liberates practically no membrane lipids from human red cells. Surface activity of phallolysin does not exceed that of bovine serum albumin.-A saponin-like interaction with cholesterol as the basic mechanism of haemolysis can be disregarded. There is also no evidence suggesting a detergent-like effect.