Stimulation by amphotericin B of uridine transport, RNA synthesis and DNA synthesis in density-inhibited fibroblasts

Nine new colchicine-resistant, three vinblastine-resistant, two colchicine-sensitive and one colchicine-dependent mutant of Chlamydomonas reinhardii have been isolated. Some of the mutants have abnormal cell morphology in the absence of the drug. Some of the mutants have altered levels of resistance to puromycin and to caffeine, which may indicate that their phenotypes involve a non-specific permeability change. However, uptake of labelled colchicine is indistin-guishable from wild type in all of these mutants except two. The discrepancy between these two results is discussed. All the resistant mutants except one behave as if they have a single gene defect in crosses to wild type, although zygote germination is consistently very poor. Strains carrying certain pairs of resistance mutations are much more resistant than those carrying single mutations indicating that gene effects are additive. Recombination frequencies between some genes have been measured. The colchicine-sensitive mutations are thought not to be cell wall deficient mutations because of their appearance in the electron microscope, growth on low agar concentrations and their colony morphology. The colchicine-dependent strain had a very low viability even in the presence of optimal concentrations of colchicine.     

Syntheses of novel antitumor dihydroxanthone derivatives with inhibitory activity against DNA topoisomerase II.

A series of methoxycarbonyl group modified nidulalin A analogs were synthesized to improve stability against esterases. The amide derivatives showed cytotoxic activity along with inhibitory activity against DNA topoisomerase II. Among the analogs, amide 9a exhibited antitumor activity in Colon 26 murine tumor model.     

Antibodies to extractable nuclear antigens in graft-vs-host F1 mice as determined by immunoblotting: absence of anti-Sm antibody

Antibodies to extractable nuclear antigens (ENA) were determined in autoimmune graft-vs-host F1 (GVH F1) mice by the immunoblotting method. Major populations of anti-ENA known in human sera including anti-Sm were not detected. It is thus conceived that different kinds of ENA proteins may be recognized by human autoimmune and GVH F1 sera.     

Flow cytometric assay for phagocytosis of human monocytes mediated via Fc gamma-receptors and complement receptor CR1 (CD35).

We developed a simple flow cytometric assay for phagocytosis by human monocytes that is mediated via Fc gamma receptors and the complement receptor CR1 (CD35), using fluorescent latex beads carrying IgG and complement components C4b and C3b. To prepare fluorescent latex beads carrying IgG(BA), BSA-coated latex beads (B) were incubated with diluted rabbit anti-BSA IgG. To bind complement components, BA-particles were incubated with whole human serum pretreated with K-76 monocarboxylic acid (K-76COOH). K-76COOH inhibits the activities of C5 and factor I (12,13), resulting in the deposition of C1,4b,2a,3b on BA-particles (BAC1,4b,2a,3b). Further incubation of BAC1,4b,2a,3b with EDTA-GVB at 37 degrees C gave particles carrying IgG and C4b,C3b (BAC4b,3b). The C3 fragment, C3b, was confirmed to present on BAC1,4a,2a,3b particles by SDS-PAGE and immunoblot, and these particles were calculated to have approximately 25,000-30,000 C3b molecules per particle. To evaluate the particle attachment, the phagocytic assay was performed with 3 microM cytochalasin D treated cells. The percent cells with ingested particles and the number of ingested particles/100 cells for 60 min were estimated, being 5.1% and 5.4 for B, 12.3% and 26.7 for BA, 42.5% and 108.7 for BAC4b,3b, and 42.6% and 112.5 for BAC1,4b,2a,3b, respectively.