Palmitoyl-VP3(110--121) (PVP3) is a synthetic lipopeptide derivative of a continuous epitope from the VP3 capsid protein of hepatitis A virus, and it is highly immunogenic in vivo. We have investigated the interaction of PVP3 with lipid model membranes of varying surface charge. Binding of PVP3 to anionic vesicles of PC/SM/PE/PS; (PC) 1-palmitoyl-2-oleoyl-phosphatidylcholine, (SM) sphingomyelin, (PE) 1,2-dipalmitoyl-phosphatidylethanolamine and (PS) L-alpha-phosphatidyl-L-serine, a composition that mimics the lipid component of natural membranes, was determined by tryptophan fluorescence and quenching experiments. In addition, and given the anionic net charge of the lipopeptide, binding to zwitterionic (PC/SM/PE) and cationic PC/SM/PE/DOTAP (DOTAP) 1,2-dioleoyl-3-trimethylammonium-propane mixtures was also determined. PVP3 binds to all three types of vesicles, but it adopts different forms depending on the electrical charge of the interface. This conclusion is supported by the insertion of PVP3 into lipid monolayers of the same charges spread at the air-water interface. The bound lipopeptide has membrane-destabilizing effects in all three vesicle compositions, as demonstrated by leakage of vesicle contents, whereas lipid mixing only occurs in cationic liposomes. Our results provide useful information for the design of a liposomal system that promotes a direct delivery of the membrane-incorporated immunogen to the immunocompetent cells, potentially increasing the immune response from the host.

Capsid↗

PubMedDate not supplied

Successful treatment of long QT syndrome-induced ventricular tachycardia with esmolol.

Esmolol is a cardioselective beta-blocker with very rapid onset of action and short half-life due to its metabolism by blood-borne esterases. This unique profile among currently available beta-blockers renders esmolol highly useful in critical care situations. However, published experience with the use of esmolol in critically ill children is scant. The case of a 4-year-old boy with secondary long QT syndrome and ventricular tachycardia successfully treated with esmolol is presented.

Adrenergic beta-Antagonists↗

PubMedDate not supplied

Disulphide bonds are a requirement for adsorption of cephalosporins on the red cell membrane.

The authors studied the behavior of red cells (RBCs), treated with 2-aminoethylisothiouronium bromide (AET), against 100 serums containing cephalothin antibodies and 27 serums with cephapirin antibodies. None of the serums reacted with cephalosporin-coated RBCs that had been exposed previously to AET. The possibility of the Kell system acting as a receptor for cephalosporins was excluded. The authors discuss the significance of cysteine disulphide bonds and the tertiary or quaternary structure of red cell membrane proteins in the binding of cephalosporins to RBCs.

Adsorption↗

PubMedDate not supplied