Thyroxine deiodination associated with NADPH-dependent lipid peroxidation in a submicrosomal system

A lipoprotein present in trypsin-treated microsomes can be oxidized with formation of malondialdehyde in a system which contains NADPH, ferric ion-ADP complex, NADPH-cytochrome c reductase and a factor. This factor, a mixture of peptides, can be isolated from hepatic microsomes by trypsin digestion and successive gel filtration through Sephadex G-100 and G-25 columns. Lipid peroxidation in this system catalyzes the deiodination of thyroxine, as does NADPH-dependent lipid peroxidation in fresh hepatic microsomes. Thyroxine inhibits lipid peroxidation as it is deiodinated in this system.

Pathogenicity of an attenuated, temperature-sensitive mutant of western equine encephalitis virus induced by a chemical mutagen

To know the pathogenicity of the chemically induced, temperature-sensitive (ts) mutant of western equine encephalitis virus, designated tsNG39, the lethality for mice injected with tsNG39, virus yield, interferon production, and histological changes in the brains of these mice were examined in parallel with those of mice inoculated with the parent strain (PS). All of the mice injected intracranially with PS died within 3.5 days after injection irrespective of the inoculum size of virus, whereas the lethality of the mice inoculated with tsNG39 varied from 94.3 to 65.5% among groups of mice and this variation seemed to be correlated with the inoculum size of virus rather than with the maximum virus titer in the brain. By histological examination, two types of changes in the brain were distinguished, inflammatory and degenerative ones. Inflammatory changes were more prominent in the brains injected with tsNG39 than in those receiving PS. Degenerative changes were dominant in the brains injected with PS, but they were slight in the earlier phase of infection by tsNG39 became prominent only later. The degree of degenerative change was well correlated with both the virus titer in the mouse brain and the death pattern of mice injected with PS or tsNG39. Since degenerative changes are thought to be caused by the direct effect of injected virus, these results indicated that the factor responsible for the low virulence of tsNG39 was the slow viral growth in the brain.

Nonspecific elicitation of antibody-forming cells in the mouse spleen by bacterial lipopolysaccharide

Mechanisms of nonspecific elicitation of anti-sheep erythrocyte (SRBC) hemolytic antibody plaqueforming cells (PFC) in mouse spleens with an injection of bacterial endotoxin (lipopolysaccharide (LPS)) were studied in comparison with the genesis of naturally occurring "background" PFC in normal mouse spleens and of rapidly arising PFC in mouse spleens after immunization with SRBC. The cytokinetic pattern of anti-SRBC PFC response after an injection of LPS was quite different from that of the response elicited after immunization with SRBC. In addition, even though LPS nonspecifically elicited anti-SRBC PFC response in mice, LPS could not confer any immunological memory on mouse immunocytess for a "secondary-type" anti-SRBC PFC response to restimulation with LPS or SRBC. The administration of rabbit anti-mouse thymocyte immunoglobulin or anti-SRBC antiserum in mice markedly suppressed the PFC response after immunization with SRBC, but did not do so after stimulation with LPS. Neonatally thymectomized mice could still respond to stimulation with LPS, producing anti-SRBC PFC in their spleens. Injections of actinomycin D or cyclophosphamide into mice resulted in obvious reductions of the PFC responses elicited by either LPS or SRBC. However, injections of these immunosuppressive antisera or drugs did not affect the number of anti-SRBC PFC in normal mouse spleens. These results suggest that the genesis of anti-SRBC PFC developed under different conditions, i.e., background PFC, LPS-stimulated PFC, and antigen-stimulated PFC, are quite different from each other, and that the nonspecific elicitation of anti-SRBC PFC by LPS does not require the helper function of T lymphocytes. No obvious difference, however, was observed in the time of ontogenic maturation among these three different anti-SRBC PFC in the mouse spleens judging from when they were first manifested after birth.

Spectroscopic evidence for the generation of singlet oxygen in the reduced nicotinamide adenine dinucleotide phosphate-dependent microsomal lipid peroxidation system

In the presence of Fe3+-ADP and NADPH, washed rat liver microsomes at 37 degrees and at pH 7.5 emitted ultraweak light with the peroxidative cleavage of endogenous lipid. The main light-emitting species of this system was analyzed spectroscopically in the visible region and estimated to be singlet oxygen. The addition of superoxide dismutase or catalase did not inhibit the light emission significantly. It is unlikely therefore that superoxide anion and OH are involved in the generation of singlet oxygen in the present system.

Stimulation of phagocytic activity in the reticuloendothelial systems of mice by lipid A complexed with homologous or heterologous proteins

Heterologous proteins are more suitable carriers than homologous proteins for the expression of endotoxic activity of lipid A prepared from the lipopolysaccharides of Salmonella typhimurium SL1102 (Re form) to stimulate the reticuloendothelial system of mice.

Percutaneous absorption of drugs. IV. Percutaneous absorption of drugs from oily vehicles

The percutaneous absorption and retention of salicylic acid and carbinoxamine from four oily vehicles (liquid paraffin, oleic acid, hexadecyl alcohol, and isopropyl myristate) were studied by employing a recirculation apparatus. The absorption followed first-order kinetics, with the exception of the initial period. The vehicle that had a strong affinity to the drug showed a poor drug-releasing effect, and poor absorption and retention of drugs by the skin were observed. Higher absorption rate constants were observed for damaged skin than intact skin. The acceleration of absorption because of skin damage, however, was not so great from liquid paraffin as from the aqueous solution. The amount of drugs retained in the damaged skin declined following the initial increase.