Adjuvant activity of synthetic 6-O-"mycoloyl"-N-acetylmuramyl-L-alanyl-D-isoglutamine and related compounds.

Adjuvant and antitumor activities of synthetic 6-O-"mycoloyl"-N-acetylmuramyl-L-alanyl-D-isoglutamine were examined. All the synthetic 6-O-corynomycoloyl-, 6-O-mocardomycoloyl-, and 6-O-mycoloyl-N-acetylmuramyl-L-alanyl-D-isoglutamine were active as adjuvants for cell-mediated immune responses. However, 6-O-mycoloyl-N-acetylmuramyl-L-alanyl-D-isoglutamine was less active as an adjuvant on circulating antibody formation. It was shown that pyrogenic activity of N-acetylmuramyldipeptide was reduced by 6-O-acylation with mycolic acid, but not with nocardomycolic or corynomycolic acid. Tumor-suppression activity was observed by the synthetic 6-O-mycoloyl-N-acetylmuramyl-L-alanyl-D-isoglutamine by using transplantable tumor in syngenic mice.     

Effect of serum amyloid P component level on transthyretin-derived amyloid deposition in a transgenic mouse model of familial amyloidotic polyneuropathy.

To elucidate the pathogenesis of amyloid deposition associated with familial amyloidotic polyneuropathy (FAP), we developed several transgenic mouse lines carrying the human mutant transthyretin (TTR) gene. We found that human TTR and mouse serum amyloid P component (SAP) are deposited as amyloid in tissues of these mouse lines. Because SAP is a major acute-phase reactant in mice, we asked whether repeated injections of Escherichia coli lipopolysaccharide (LPS) would enhance the amyloid deposition in one of these transgenic mouse lines. During the course of repeated LPS injections, serum levels of SAP in the transgenic mice remained between severalfold to about 50-fold higher than seen in the absence of stimulation. As no significant difference was detected in the onset, progression, and tissue distribution of TTR-derived amyloid (ATTR) deposition between the LPS-stimulated and unstimulated transgenic mice, the induction of SAP synthesis by acute inflammation probably does not affect the onset and extent of ATTR deposition.     

A new semiquantitative radiometric opsonin assay. Selective measurement of opsonizing capacity of the alternative pathway.

A new semiquantitative radiometric opsonin assay is described. It was found that the opsonin activity generated by incubating brewer's yeast, Saccharomyces cerevisiae, in medium containing less than 5% human serum was exclusively complement dependent. In contrast, C. albicans was effectively opsonized in the absence of complement. Antibodies and the early classical complement pathway did not contribute to the opsonization of S. cerevisiae and neither did C5-9. The brewer's yeast assay can therefore be used for measuring selectively the opsonizing capacity of the alternative pathway. Sera from approximately 7% of apparently healthy adult controls consistently failed to generate significant opsonin activity while 8 out of 26 patients with suspected immune deficiency of unknown cause were defective in this assay. All opsonin deficient sera so far tested had haemolytically normal alternative pathway and Factor B activity.     

Autoimmunity and glomerulonephritis in mice with targeted deletion of the serum amyloid P component gene: SAP deficiency or strain combination?

Human serum amyloid P component (SAP) binds avidly to DNA, chromatin and apoptotic cells in vitro and in vivo. 129/Sv x C57BL/6 mice with targeted deletion of the SAP gene spontaneously develop antinuclear autoantibodies and immune complex glomerulonephritis. SAP-deficient animals, created by backcrossing the 129/Sv SAP gene deletion into pure line C57BL/6 mice and studied here for the first time, also spontaneously developed broad spectrum antinuclear autoimmunity and proliferative immune complex glomerulonephritis but without proteinuria, renal failure, or increased morbidity or mortality. Mice hemizygous for the SAP gene deletion had an intermediate autoimmune phenotype. Injected apoptotic cells and isolated chromatin were more immunogenic in SAP(-/-) mice than in wild-type mice. In contrast, SAP-deficient pure line 129/Sv mice did not produce significant autoantibodies either spontaneously or when immunized with extrinsic chromatin or apoptotic cells, indicating that loss of tolerance is markedly strain dependent. However, SAP deficiency in C57BL/6 mice only marginally affected plasma clearance of exogenous chromatin and had no effect on distribution of exogenous nucleosomes between the liver and kidneys, which were the only tissue sites of catabolism. Furthermore, transgenic expression of human SAP in the C57BL/6 SAP knockout mice did not abrogate the autoimmune phenotype. This may reflect the different binding affinities of mouse and human SAP for nuclear autoantigens and/or the heterologous nature of transgenic human SAP in the mouse. Alternatively, the autoimmunity may be independent of SAP deficiency and caused by expression of 129/Sv chromosome 1 genes in the C57BL/6 background.     

Adjuvant Activity of 6-Amino-6-Deoxy-Muramyldipeptides and Their Acylamino Derivatives on the Induction of Delayed Hypersensitivity to Azobenzenearsonate-N-Acetyl-l-Tyrosine in Guinea Pigs

The 6-amino-6-deoxy-N-acetylmuramyldipeptides and their 6-acylamino derivatives were shown to be active as adjuvants on the induction of delayed-type hypersensitivity to azobenzenearsonate-N-acetyl-l-tyrosine in guinea pigs. However, 6-acylamino-6-deoxy-N-(acyl)muramyldipeptides were inactive as adjuvants.     

Electrophysiological analysis of rhythmic jaw movements in the freely moving mouse

Although rhythmic jaw movement in feeding has been studied in mammals, such as rats, rabbits and monkeys, the cellular and molecular mechanisms underlying it are not well understood. Transgenic and gene-targeting technologies enable direct control of the genetic makeup of the mouse, and have led to the development of a new category of reagents that have the potential to elucidate the cellular and molecular mechanisms of neural networks. The present study attempts to characterize rhythmic jaw movements in the mouse and to demonstrate its relevance to rhythmic jaw movements found in higher mammals using newly developed jaw-tracking systems and electromyograms of the masticatory muscles. The masticatory sequence of the mouse during feeding was classified into two stages, incision and chewing. Small and rapid (8 Hz) open-close jaw movements were observed during incision, while large and slow (5 Hz) open-close jaw movements were observed during chewing. Integrated electromyograms of the masseteric and digastric muscles were larger during chewing than those observed during incision. Licking behavior was associated with regular (8 Hz), small open-close jaw movements with smaller masseteric activity than those observed during mastication. Grooming showed variable patterns of jaw movement and electromyograms depending on the grooming site. These results suggest that there are neuronal mechanisms producing different frequencies of rhythmic jaw movements in the mouse, and we conclude that the mouse is useful for understanding rhythmic jaw movements in higher mammals.     

Role of BLNK in oxidative stress signaling in B cells

BLNK (B cell linker protein) represents a central linker protein that bridges the B cell receptor-associated kinases with a multitude of signaling pathways. In this study, we have investigated the role of BLNK in oxidative stress signaling in B cells. H2O2 treatment of B cells induced a rapid tyrosine phosphorylation of BLNK in a H2O2 dose-dependent manner, which was inhibited in Syk-deficient DT40 cells. Calcium mobilization in BLNK-deficient as well as Syk-deficient and phospholipase C (PLC)-gamma2-deficient cells after H2O2 treatment was completely abolished. These were derived from decreased inositol 1,4,5-trisphosphate generation through PLC-gamma2 in BLNK-deficient cells. Moreover, viability of BLNK-deficient as well as PLC-gamma2-deficient cells after exposure to low doses of H2O2 was dramatically enhanced compared with that of the wild-type cells. Furthermore, c-Jun N-terminal kinase activation following high doses of H2O2 stimulation, but not low doses of H2O2 stimulation, was abrogated in BLNK-deficient as well as Syk-deficient cells. These findings have led to the suggestion that BLNK is required for coupling Syk to PLC-gamma2, thereby accelerating cell apoptosis in B cells exposed to low doses of H2O2.     

Physical training and fasting erythrocyte activities of free radical scavenging enzyme systems in sedentary men

Summary Effects of 10 weeks of physical training on free radical scavenging enzyme systems in erythrocytes were investigated in 7 sedentary healthy male students. The training consisted of running over 5 km, 6 times/week. Their maximum oxygen uptake and 12 min walk-run performance increased significantly after training. Of the antioxidant enzyme systems examined in the erythrocytes, both catalase activity and concentration and total glutathione reductase (GR) activity also showed significant increases following the training. The erythrocyte GR activity coefficient also increased significantly. These results suggest that chronic aerobic exercise increases riboflavin requirements and has some positive effects on antioxidative processes.