B220

1.Independent regulation of IgM, IgD, and Ia antigen expression in cultured immature B lymphocytes/PMID 3485174; The Journal of experimental medicine 1986 Apr; 163(4):938-51/Name matches: phorbol ester b-220
Abstract:Long-term cultured bone marrow cells were characterized with respect to a number of B and pre-B cell markers. Cells expressing ThB, B-220, and IgM were found within cultures set up according to the procedure of Whitlock and Witte. This culture system was modified by placing sorted pre-B cells (ThB+, IgM-) from bone marrow in culture with previously-established bone marrow adherent layers. These cultures commenced growth without the lag associated with the Whitlock cultures. These cultured nonadherent cells show a high frequency of IgM+ cells, but do not express either IgD or Ia, and we refer to them as immature B cells. Cells with a similar phenotype (IgM+, Ia-, IgD-) are found within the spleens of young but not adult mice. The phorbol ester PMA induces expression of IgD on the cultured immature B cells, but has no effect on Ia expression. This suggests that the processing of H chain RNA transcripts may be affected by protein kinase C. These results demonstrate that the appearance of IgM, IgD, and Ia are independently controlled in long-term cultured B-lineage cells.

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2.1H-NMR studies of the interaction between a self-complementary deoxyoligonucleotide duplex and indolo[2,3-b]quinoxaline derivatives active against herpes virus/PMID 2029893; European journal of biochemistry 1991 May; 197(3):597-604/Name matches: ellipticine 2-3-dimethyl-6-(2-dimethylaminoethyl)6h-indolo-(2,3-b)quinoxaline
Abstract:1H NMR has been used to study the interactions of ellipticine and the ellipticine analogues 2-3-dimethyl-6-(2-dimethylaminoethyl)6H-indolo-[2,3-b]quinoxaline and 6-(2-dimethylaminoethyl)6H-indolo-[2,3-b]quinoxaline with the self-complementary decadeoxyribonucleotide d(CGCGATCGCG)2. The Watson-Crick H-bonded imino proton resonances were studied. The drugs were shown to bind to the duplex by intercalation involving slow exchange kinetics for the imino proton resonances on the NMR time scale (500 MHz). Ellipticine and the 2,3-dimethyl analogue were found not to show strong base preferences, while the other analogue was found to have a preferred primary binding site between the A.T base pairs with a probable minor secondary binding site between the A.T and adjacent G.C base pairs. The new drug-shifted imino proton resonances were assigned through saturation transfer experiments. The base-specific interactions were accompanied by drug-induced non-uniform broadening of the resonances (due to intermediate chemical exchange kinetics), in the spectral region of the non-exchangeable aromatic and sugar H1' proton resonances of the oligonucleotide at 25 degrees C.

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3.Protection against 12-O-tetradecanoylphorbol-13-acetate induced skin-hyperplasia and tumor promotion, in a two-stage carcinogenesis mouse model, by the 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-[2,3-b]quinoxaline analogue of ellipticine/PMID 10528995; Chemico-biological interactions 1999 Sep; 122(2):89-106/Name matches: ellipticine 2,3-dimethyl-6-(2-dimethylaminoethyl)-6h-indolo-(2,3-b)quinoxaline; b-220
Abstract:The effects of topical applications of 2,3-dimethyl-6(2-dimethylaminoethyl)-6H-indolo-[2,3-b]quinoxaline (B-220), on 12-O-tetradecanoylphorbol-13-acetate (TPA) or benzoylperoxide (BPO) induced promotion of skin tumors and hyperplasia were studied in female SENCAR mice. Papillomas were induced by initiation with 7,12-dimethylbenz[a]anthracene (DMBA), followed by promotion biweekly with TPA or BPO. Administration of B-220 1 h before TPA promotion resulted in a prolonged latency period of tumor appearance and a significantly reduced (up to 15% of positive controls) papilloma yield at 20 weeks. Moreover, if B-220 treatment was terminated after 20 weeks and TPA treatment continued, papilloma development resumed indicating that initiated tumor cells were still present but were unable to grow with B-220 present. If B-220 pretreatment was not given during the first 10 weeks of TPA promotion, incidence at 20 weeks was not reduced but tumor multiplicity was still decreased. In addition a marked reduction of the TPA induced sustained epidermal hyperplasia was observed in the long term experiment. Neither the inflammatory response nor the increase in the number of apoptotic cells seen in short term experiment after a single TPA treatment were inhibited by B-220. B-220 administration before BPO promotion had no effect on the appearance of BPO induced papillomas or epidermal hyperplasia, suggesting that TPA and BPO promote tumor formation via at least partially different mechanisms. In experiments where B-220 was applied topically 1 h before DMBA initiation, little or no effect was seen. No morphological changes in mouse skin due to long term exposure (two times/week, 39 weeks) to B-220 were found. In conclusion, we present evidence that B-220 is a potent inhibitor of mouse skin tumor promotion by TPA, but has little effect on the initiation step or the survival of initiated cells.