Lytic effect of heparin on liposomes: possible mechanism of lysis of red blood cells by heparin

Low power laser protects human erythrocytes In an In vitro model of artificial heart-lung machines

The protective effect of the low power helium-neon (He-Ne) laser against the damage of human erythrocytes in whole blood was examined in a perfusion model using an artificial heart-lung machine. Preserved human whole blood was diluted and perfused in 2 closed circuits with a double roller pump. The laser irradiated one of the circuits (laser group), and none the other (control group). In the laser group, erythrocyte deformability and erythrocyte adenosine triphosphate (ATP) levels were significantly higher, and free hemoglobin levels were significantly lower than those in the control group. Subsequent morphological findings by means of scanning electron microscope were consistent with these results. Low power He-Ne laser protected human erythrocytes in the preserved diluted whole blood from the damage caused by experimental artificial heart-lung machines. The clinical application of low power laser treatment for extracorporeal circulation is suggested.

Effects of intraperitoneal administration of free and liposome-entrapped doxorubicin on rat peritoneal exudate cell populations

In the present paper effects of i.p. treatment with free or liposome-entrapped doxorubicin (DXR) on rat peritoneal exudate cell (PEC) populations were examined. Two types of DXR-liposomes were used: one type consisting of egg-phosphatidylcholine/phosphatidylserine/cholesterol (molar ratio 10/1/4, mean size approx. 0.3 micron) and the other type of distearoylphosphatidylcholine/dipalmitoylglycerol/cholesterol (molar ratio 10/1/10, mean size approx. 0.8 micron). Dramatically fewer PEC could be recovered from rats given free DXR or DXR-liposomes i.p. (10 mg DXR/kg body weight) 24 h before sacrifice than from control rats. Also the ratio of leukocyte species was modified by treatment with DXR, in free or liposomal form; in both cases the relative number of macrophages tended to increase. HPLC determination of the amount of DXR associated with monolayers obtained by seeding PEC harvested after a single i.p. dose of free DXR or liposomal DXR suggests that peritoneal macrophages are not particularly active in endocytosing DXR-liposomes. It was observed that the peritoneal macrophages phagocytosed DXR-containing granules from degranulating mast cells after both i.p. treatment with free DXR and DXR-liposomes. Decreased yields of PEC following i.p. treatment with free or liposomal DXR as well as an involvement of mast cells in the processing of both free DXR and liposome-encapsulated DXR in the peritoneal cavity may have important consequences for approaches to i.p. chemotherapy.

Complexing of heparin with phosphatidylcholine. A possible supramolecular assembly of plasma heparin

In a series of attempts to reveal plasma heparin, we found that high ionic strength and modification of protein amino groups were not effective in extracting endogenous heparin (or, indeed, a large percentage of exogenous labelled heparin), whereas delipidation in the presence of 4M-guanidinium chloride gave high yields, indicating that plasma heparin may be assembled with compounds other than proteins, in a form making it inaccessible to water and ions. During the extraction of lipids, a paradoxical entry of heparin into the organic phase was observed. Detergents, including sodium dodecyl sulphate, did not shift heparin into the aqueous phase, whereas repeated chloroform/methanol extraction did so. Using purified compounds we were able to reproduce in vitro both the scavenging of heparin from water as well as the formation of heparin-phosphatidylcholine complexes soluble in organic solvents. Evidence for complexing of heparin with phosphatidylcholine was also obtained by electrophoretic and ultracentrifugation assays. The quaternary-ammonium-containing phosphatidylcholine was the more effective phospholipid in binding heparin; anionic phospholipids did not bind. Only heparin-like glycosaminoglycans bound phosphatidylcholine, but less-sulphated compounds (heparan sulphate and dermatan sulphate) were weaker ligands. Gel-filtration experiments showed that heparin was not bound to liposome vesicles, but that a measurable percentage of the phospholipids was stripped off from vesicles and was found in the form of a complex separable from liposomes by gel filtration. The molecular basis as well as the biological role of the interaction of heparin with major membrane phospholipids are discussed.