Search results for "Cytotoxic"
showing 10 items of 1673 documents
The CD38-Positive and CD38-Negative Subsets of CD34(high)-Positive Primary Acute Myeloid Leukemia Blasts Differ Considerably in the Expression of Imm…
2008
Abstract Acute myeloid leukemia (AML) is thought to arise from a rare putative ‘leukemic stem cell’ that is capable of self-renewal and formation of leukemic blasts. Serial xenotransplantation studies in immunodeficient mice have shown that this leukemia-initiating cell resides at very low numbers within CD34(high)-positive CD38-negative AML cells. Thus, immunotherapeutic approaches successfully eradicating this cell compartment should result in cure from disease. The objective of our study was to characterize the immune phenotype of the CD38-negative and CD38-positive subsets of primary CD34(high)-positive AML blasts ex vivo. We obtained therapeutic leukapheresis products from 17 AML patie…
EFFECT OF M-LOCUS DEPENDENT T-CELL PROLIFERATION UPON THE INDUCTION OF ANTI H-2 CYTOTOXIC T EFFECTOR CELLS
1975
SUMMARY The influence of M-locus dependent T cell proliferation on the induction of anti H-2 cytotoxic T lymphocytes (CTL) was tested in an in vitro murine cytotoxic allograft model. BALB/c (or CBA/H) derived responder cells (H-2d or H-2k) were cultured together with either C57BL derived fibroblasts or C57BL derived (H-2b), U.V. light irradiated, splenic lymphocytes. These stimulator cells lack functionally active lymphocyte activating determinants (LADs), but display serologically defined (SD) H-2 antigenic specificities. The cytotoxic anti SD-activity obtained was weak. Under certain experimental conditions, the addition of stimulator cells which are H-2 identical to the responder cells b…
Ophiobolin Sesterterpenoids and Pyrrolidine Alkaloids from the Sponge-Derived Fungus Aspergillus ustus
2011
Chemical examination of the fungus Aspergillus ustus isolated from the Mediterranean sponge Suberites domuncula yielded the five new ophiobolin-type sesterterpenoids 1–5 and the two new pyrrolidine alkaloids 6 and 7, together with the known compound aurantiamine and cerebroside D. The structures of the new compounds were unambiguously elucidated on the basis of extensive spectroscopic-data analysis (1D- and 2D-NMR, MS, and UV) and comparison with literature data. All compounds were evaluated for their cytotoxicity against murine lymphoma cell line L5178Y.
Cytotoxicity of fagaramide derivative and canthin-6-one from Zanthoxylum (Rutaceae) species against multidrug resistant leukemia cells
2019
In our continuous search for cytotoxic compounds from the genus Zanthoxylum, chromatographic separation of the MeOH/CH2Cl2 (1:1) extract of Z. chalybeum yielded one new alkamide; 4-(isoprenyloxy)-3-methoxy-3,4-deoxymethylenedioxyfagaramide (1) and a known one; fagaramide (2). Similarly, from the MeOH/CH2Cl2 (1:1) extract of the stem bark of Z. parachanthum four known compounds; canthin-6-one (3), dihydrochelerythrine (4), lupeol (5) and sesamin (6) were isolated. Characterization of the structures of these compounds was achieved using spectroscopic techniques (NMR and MS). Using resazurin reduction assay 1, 3 and 6 displayed moderate cytotoxicity with IC50 values below 50 μM against the dru…
Antigen dose-dependent suppression of murine IgE responses is mediated by CD4−CD8− double-negative T cells
2010
Background The IgE response against protein antigens is profoundly influenced by the dose used for sensitization. Objective The aim of the study was to identify immune cells that are involved in antigen dose-dependent regulation of IgE formation. Methods Wild-type mice as well as T helper (Th)1-deficient IL-12p40(-/-) and IFN-gamma(-/-) mice were immunized by repeated intraperitoneal injection of either low doses (K01 mice) or high doses (K100 mice) of keyhole limpet haemocyanin adsorbed to aluminium hydroxide. Splenocytes of immunized mice were restimulated in vitro and antigen-dependent T cell proliferation and cytokine production were measured. The frequency of regulatory T cell subsets …
Squaraine Dyes for Photodynamic Therapy: Mechanism of Cytotoxicity and DNA Damage Induced by Halogenated Squaraine Dyes Plus Light (>600 nm)¶
2004
Halogenated squaraine dyes 1 and 2 possess favorable photophysical and in vitro photobiological properties that make these new class of molecules interesting for photodynamic therapeutic applications. For a better understanding of the mechanism of their photobiological activity, we have analyzed the DNA damage and the cytotoxicity induced by these photosensitizers in mammalian cells and cell-free systems in the presence and absence of various additives and scavengers. Both photoactivated squaraines were found to be similar efficient in inducing single-strand breaks (SSB) in cell-free DNA when compared with the cellular DNA. Superoxide dismutase and catalase did not show any influence. Howev…
New bioactive alkaloids from the marine sponge Stylissa sp.
2012
Abstract Chemical investigation of the Indonesian marine sponge Stylissa species, which was collected at 2008 from Derawan Islands, Berau, NE Kalimantan, Indonesia offered four new brominated alkaloids, including 12-N-methyl stevensine (1), 12-N-methyl-2-debromostevensine (2), 3-debromolatonduine B methyl ester (3), 3-debromolatonduine A (4) together with eight known alkaloids identified as Z-hymenialdisine, Z-debromohymenialdisine, Stevensine, 2-debromostevensine, 3-bromoaldizine, 3,4-dibromopyrrole-2-carbamide, latonduine A, and latonduine B methyl ester (5–12), respectively. The structures of all isolated compounds were unambiguously elucidated based on extensive 1D and 2D NMR spectrosco…
ChemInform Abstract: Design, Synthesis, DNA-Binding and Cytotoxicity Evaluation of New Potential Combilexines.
2010
Combilexines, compounds in which a DNA intercalator is linked to a minor groove binding component, interact with the DNA in a sequence specific manner to yield in most cases compounds with anticancer activity. A series of new compounds closely related to netropsin in which the two components were linked by an amide group was synthesised as potential combilexines. As some of these compounds showed cytotoxic activity in vitro, an attempt was made to rationalise their mechanism of action. The DNA binding characteristics of the carboxamides were evaluated by thermal denaturation experiments and by ethidium bromide displacement assay. Their ability to inhibit the topoisomerase I was also determi…
Neo-clerodane diterpenoids from Conyza pyrrhopappa Sch.Bip. ex A.Rich
2019
Two hitherto unknown neo-clerodane-type diterpenoids along with twelve known compounds have been isolated from Conyza pyrrhopappa Sch.Bip. ex A.Rich, a medicinal plant traditionally used across tropical Africa to relieve fever. The structures of isolates have been elucidated by a combination of spectroscopic techniques. The crude extract and the isolated compounds were evaluated in the Hela-S3 cell line and in a panel of microorganisms (bacteria and fungi) at concentrations up to 50 µg/mL. The new compounds were inactive while the pentamethylated flavonoids showed low to significant activity against the cancer cell line used. However, none of the samples showed any activity against the test…
Cytotoxic alkaloids from the root of Zanthoxylum paracanthum (mildbr) Kokwaro
2021
Chemical investigation of the root of Zanthoxylum paracanthum afforded 1 new alkamide derivative, (2E,4E)-6-oxo-N-isobutyldeca-2,4-dienamide (1) together with 10 known congeners including one pheno...