Hongoquercins A and B, new sesquiterpenoid antibiotics: isolation, structure elucidation, and antibacterial activity.

Two new sesquiterpenoid antibiotics, hongoquercins A and B, were isolated from the extracts of an unidentified fungus. The structures of both metabolites were determined by spectroscopic analysis. They are related to a class of compounds commonly found in brown algae and dictyoceratid sponges. Hongoquercin A exhibited moderate activity against gram-positive bacteria.

Glycothiohexide alpha, a novel antibiotic produced by "Sebekia" sp., LL-14E605. II. Isolation and physical-chemical characterization.

Glycothiohexide alpha was recovered from the fermentation broth of a "Sebekia" sp. by mixed solvent extraction, selective precipitation and adsorption chromatography on Diaion HP-20. The amount of glycothiohexide alpha present in the crude preparation was enriched by photolysis. Purification of glycothiohexide alpha was accomplished by repetitive countercurrent chromatography.

Modulation of anti-tumor cytotoxicity of cultured mast cells by metabolic inhibitors.

IL-3-dependent, murine mast cell lines derived from embryonic yolk sac precursors display a tumoricidal activity that is blocked by antibodies against tumor necrosis factor-alpha, indicating that this cytokine is the major mediator involved in the cytotoxic activity of the cultured mast cell lines. Further, cholera toxin strongly inhibits the cytotoxic activity of mast cells as well as their IL-3-induced DNA synthesis response but not IgE-mediated serotonin release. Cyclosporin A diminished cytotoxicity and serotonin release, but not DNA synthesis. Actinomycin D markedly suppressed the cytotoxicity of one mast cell line but only slightly suppressed that of another, whereas the IL-3-induced proliferation of both mast cell lines was strongly inhibited. Thus, our studies indicate that the cytotoxic function of mast cells is relatively independent of their degranulation and proliferation and may utilize different signalling pathways.

Calicheamicins, a novel family of antitumor antibiotics. 3. Isolation, purification and characterization of calicheamicins beta 1Br, gamma 1Br, alpha 2I, alpha 3I, beta 1I, gamma 1I and delta 1I.

Novel antitumor antibiotics, calicheamicins beta 1Br, gamma 1Br, alpha 2I, alpha 3I, beta 1I, gamma 1I and delta 1I were recovered from the fermentation broth of Micromonospora echinospora ssp. calichensis by solvent extraction, selective precipitation, normal phase, reversed phase and partition chromatography. The individual components were characterized by their UV, IR, 1H and 13C NMR spectral data.

Transplantation of cultured thymic fragments: results in nude mice. V. Reconstitution with xenogeneic (rat) thymic tissue.

Transplantation of F344 rat cultured thymic fragments was able to restore immune function to nude mice. Approximately half of such animals displayed increased lifespan (7-8 months). These mice were also capable of rejecting allogeneic mouse skin and rat skin from a strain (Buffalo) unrelated to the thymus donor; however, they were incapable of rejecting rat skin from the thymus donor strain. Proliferative responses to T-cell mitogens were restored. Proliferative responses to alloantigens and xenoantigens in mixed leucocyte cultures were also restored and showed the same patterns of specific reactivity and non-reactivity as in skin graft rejection. The ability to make antibody responses to specific antigens was also restored, but the responsiveness was more variable than for cell-mediated responses. Some mice were able to make antibody to rabbit serum proteins; however, fewer mice made antibody to ovalbumin. The inability to respond to ovalbumin may be due to the fact that F344 rats are low responders to this protein. These results suggest that cultured xenogeneic thymus is effective in restoring two major differentiation functions of the normal thymus gland: development of specific antigen responsiveness and non-responsiveness.

Transplantation of cultured thymic fragments: results in nude mice. IV. Effect of amount of thymic tissue.

Nude mice were transplanted with varying amounts of cultured thymic fragments equivalent to tissue derived from less than 1, 1 or 3 thymuses. All amounts of tissue preserved life, restored skin graft rejection, thymus-dependent allotolerance, anti-sheep erythrocyte antibody responses and serum IgG1 levels to near normal values. Serum IgA levels, IgE and hemagglutinating responses to ovalbumin as well as mitogen proliferation were shown to be more dependent upon the mass of thymus transplanted. In some cases, allogeneic CTF transplantation results showed a greater mass effect, but this was apparent only when less than 1 thymus equivalent was used. These data correlate well with the heterogeneity of the DiGeorge syndrome and variable results seen with human CTF transplantation.

Suppression of reaginic antibody (IgE) formation in mice by treatment with anti-mu antiserum.

Neonatally initiated injection of anti-mu antiserum in mice has been shown to suppress the formation of reaginic antibodies in response to infection with the intestinal nematode, Nippostrongylus brasiliensis. This observation supports the hypothesis that IgE-producing cells arise from IgM-bearing precursors.