Inhibitory Action of Serum Lecithin on the Hemolytic Activity of Serum Lysolecithin in Vitro

Mitigation of surfactant erythrocyte toxicity by egg phosphatidylcholine

Polyoxyethylene alkyl ether surfactants have been shown to have excellent penetration enhancing abilities although they are associated with a high level of local toxicity. We have compared the toxicity of a range of polyoxyethylene alkyl ethers (Brij 96, Brij 76, Brij 56, 10 lauryl ether and 9 lauryl ether) to an anionic surfactant (sodium dodecyl sulphate (SDS)), an ampholytic surfactant (lysophosphatidylcholine) and a cationic surfactant (tetradecyltrimethylammonium bromide (TTAB)), in the presence and absence of egg phosphatidylcholine. The toxicity of the surfactants or phospholipid/surfactant mixtures was assessed by measuring haemolytic activity. The test samples were incubated with a suspension of red blood cells for 30 min and Drabkin's reagent was used to indicate the amount of haemoglobin released. All of the polyoxyethylene alkyl ethers, SDS, TTAB and lysophosphatidylcholine exhibited haemolytic activity at concentrations between 0.10 and 0.25 mM. The addition of egg phosphatidylcholine reduced the toxicity for all of the surfactants, with the toxicity of Brij 96 being mitigated to a greater extent than the toxicity of the other polyoxyethylene surfactants examined. The rate of haemolysis induced by Brij 96 or 10 lauryl ether was also reduced by increasing concentrations of phosphatidylcholine. As the phosphatidylcholine content of a mixed surfactant system comprising egg phosphatidylcholine: Brij 96 was replaced by lysophosphatidylcholine and fatty acid, the haemolytic action of the mixture increased markedly. The results from this study show that the toxicity of surfactants to erythrocytes can be mitigated by the addition of egg phosphatidylcholine. Synthetic surfactants combined with phosphatidylcholine may generate drug delivery systems worthy of more extensive investigation.

The mitigating effects of phosphatidylcholines on bile salt- and lysophosphatidylcholine-induced membrane damage

The effects, at pH 7.0, of a series of 0.2 mM phosphatidylcholines (PC), namely dicaproyl-PC (DCPC), didecanoyl-PC (DDPC), dilauroyl-PC (DLaPC), dimyristoyl-PC (DMPC), dipalmitoyl-PC (DPPC), dioleoyl-PC (DOPC) and dilinoleoyl-PC (DLPC) and a series of 0.2 mM fatty acid salts (namely sodium myristate, palmitate, stearate, oleate and linoleate) upon the erythrocyte haemolysis induced by 2 mM sodium taurodeoxycholate (STDC) were determined. The influence of egg PC and dihexadecyl phosphate (DHDP) concentration upon the haemolysis induced by 1.4 mM sodium deoxycholate (SDC), 2 mM STDC and 0.1 mM lysophosphatidylcholine (LPC) were also established. A bile salt:egg PC mole ratio of 0.5 virtually abolished the haemolysis induced by SDC and STDC, whereas the same ratio of LPC:egg PC only reduced haemolysis from 65 to 40% (maximum haemolysis). DHDP had no effect on the haemolytic action of SDC or STDC. The salts of the fatty acids were non-haemolytic, and when mixed with STDC did not affect the level of haemolysis induced by the bile salt. In contrast, DDPC and DLaPC enhanced the haemolysis of STDC and DCPC had no effect, whereas DMPC, DPPC, DSPC, DOPC, DLPC and egg PC all reduced haemolysis. Maximum reduction was determined for DMPC and egg PC. The mixed micelle preparation temperature (either room or 60 degrees C) and temperature of incubation (either 20 degrees C for 30 min or 37 degrees C for 5 min) had only minor effects on the net haemolysis induced by STDC. These findings may be of significance in understanding the aetiology of certain gastrointestinal diseases and in determining whether mixed bile salt micelles have a role as drug penetration enhancers.

Pathophysiology of acute obstructive cholecystitis: implications for non-operative management

Recent research suggests that disturbances in gallbladder mucosal functions are important in the initiation of acute cholecystitis and its progression. Prostaglandins have pathophysiological significance and prostaglandin synthesis inhibitors such as indomethacin inhibit fluid secretion by gallbladder mucosa, reduce distension and relieve pain. Nerves in the gallbladder wall are involved in disturbed mucosal function, and the benefits of opiates may derive from reduction of active fluid secretion in the inflamed and obstructed gallbladder as well as from central analgesic effects.

Lysolecithin affects the viscosity, permeability, and peptic susceptibility of gastric mucin

The effect of lysolecithin and lecithin on gastric mucin viscosity, permeability to hydrogen ion, and degradation by pepsin was investigated. Preincubation with lysolecithin produced a marked decrease in the glycoprotein viscosity. This decrease was concentration-dependent and at 10 mM lysolecithin reached a value of 74%. A 25% increase in mucin viscosity was obtained with 10 mM lecithin. Permeability measurements showed that 10 mM lecithin increased the retardation ability of the glycoprotein to hydrogen ion by 11%, whereas a 12% decrease in the retardation capacity of the glycoprotein was obtained with 10 mM lysolecithin. The results of peptic activity assay indicated that whereas lecithin had no effect on the rate of mucin proteolysis, the lysolecithin exerted significant (75%) stimulatory effect. The results suggest that lysolecithin in the stomach weakens the integrity of the protective mucus layer by promoting peptic degradation, reducing the ability to resist acid penetration, and decreasing viscosity of its mucin component.

Studies on the pre-alpha-lipoprotein of human serum. I. characterization of an albumin-containing lipoprotein

In this study an albumin-containing lipoprotein is isolated by column affinity chromatography and electrophoresis. Its electrophoretic mobility is faster than that of albumin in agarose gel. Immunologically it reacts with anti-albumin and anti-apolipoprotein-A-I. No reaction is obtained against antibodies to any of the other previously known lipoportein families: Apo-AII, Apo-B, Lp(a), Apo-C, LpX, Apo-D or Apo-E ('the arginine rich peptide'). It differs from purified albumin in having higher amounts of glycine, serine and glutamic acid. Moreover, the molecular weight is estimated to 80,000 as compared to 67,000 for albumin.

[Changes of erythrocyte membrane lipids in ethanol induced hyperlipidemia (Zieve's syndrome) (author's transl)]

In 11 patients with alcohol-induced hyperlipemia, of whom 6 showed a Zieve Syndrome increased phospholipids, triglycerides and total cholesterol were found in the red cells stromal. The gasliquid chromatographic analysis of the phospholipid fatty acids showed increased contents of saturated and monounsaturated fatty acids C 16-C 18 smaller contents of longchain highly unsaturated fatty acids. The changes in the fatty acid pattern mainly occurred in patients with Zieve Syndrome and could be important for the mechanism of the hemolytic anemia. Theses findings could be in connexion with vitamin E deficiency.

The haemolytic activity of sols containing progesterone solubilized by phosphatidylcholine and lysophosphatidylcholine

Lysis of rat erythrocytes by aqueous dispersions containing lysophosphatidylcholine (lpc), phosphatidylcholine (pc) and progesterone has been studied. The haemolytic activity of lpc was reduced by saturating it with progesterone; mixed lpc-pc micelles owed their lytic activity to the lpc alone. Cholesterol solubilized together with progesterone by lpc greatly reduced the lytic activity of the lpc, and when solubilized with progesterone by a 1:1 mixture of lpc and pc, prevented haemolysis. Triolein also inhibited the haemolytic properties of the sols.