Highly Enantioselective Catalytic Alkynylation of Quinolones: Substrate Scope, Mechanistic Studies, and Applications in the Syntheses of Chiral -Heterocyclic Alkaloids and Diamines.

The alkynylation of 4-siloxyquinolinium triflates has been achieved under the influence of copper bis(oxazoline) catalysis. The identification of the optimal bis(oxazoline) ligand was informed through a computational approach that enabled the dihydroquinoline products to be produced with up to 96% enantiomeric excess. The conversions of the dihydroquinoline products to biologically relevant and diverse targets are reported.

Correction: Dearomatization of benzopyrylium triflates with sulfoxonium ylides.

Correction for 'Dearomatization of benzopyrylium triflates with sulfoxonium ylides' by Alexandria N. Leveille , , 2022, , 12600-12603, https://doi.org/10.

Dearomatization of benzopyrylium triflates with sulfoxonium ylides.

Benzopyrylium triflates react with sulfoxonium ylides to give rise to cyclopropanated products in up to 90% yield as a single diastereomer. The cyclopropanated products can easily undergo acid-mediated ring-expansion to afford benzo[]oxepines. Control over the absolute stereochemistry of the process is possible when the reaction is executed under the influence of a suitable anion-binding catalyst.

Natural cell-mediated immunity in the rabbit.

Susceptibility and resistance to tumors represent the interplay of many factors. One factor felt to govern the development of tumors is natural killer and natural cytotoxic cellular activity. The constitutional resistance of rabbits to spontaneous tumor development raises questions regarding the activity of natural cell-mediated immunity in this species.

Determinants of the ability of malignant fibroma virus to induce immune dysfunction and tumor dissemination in vivo.

The relationship of virus-induced immunological dysfunction and tumor dissemination was studied using two related tumor-causing leporipoxviruses: malignant fibroma virus (MV) and Shope fibroma virus (SFV). Recombinant viruses, produced by transferring MV's 10.7 kb BamHI C fragment to SFV, replicate in lymphocytes and suppress lymphocyte function in vitro.

Laminin receptor expression on murine tumor cells: correlation with sensitivity to natural cell-mediated cytotoxicity.

Previous studies have identified a relationship between the presence of cell surface laminin receptors on murine tumor cells and sensitivity to killing by natural killer (NK) cells. On the basis of these observations, we suggested that laminin and laminin receptors may function to facilitate the interaction of NK-sensitive murine target cells with NK cells. Our original studies were conducted with a number of genetically unrelated tumor cell lines.

Treatment of mice with anti-asialo-GM1 antibody or poly-I:C: effects on metastasis dissociable from modulation of macrophage antitumor activity.

Treatment of C57BL/6J mice with poly-I:C or antibodies to asialo-GM1 enhances and depresses respectively natural killer (NK) cell activity while inversely altering lung metastasis, suggesting a critical role for these cells in controlling tumor formation. We assessed the effect of these treatments on antitumor activity mediated by macrophage (M phi) populations likely to be important in lung metastasis. Alveolar and lung interstitial M phi were asialo-GM1 positive (98%) and were sensitive to in vitro treatment with the antibody plus complement; however, treatment of mice with antibodies to asialo-GM1 failed to alter their tumoricidal activity in vitro.

Laminin production by murine melanoma cells: possible involvement in cell motility.

Three lines of B16 melanoma cells (B16-F1, B16-F10 and B16-BL6) were examined for motility in the micropore filter assay and for synthesis in culture of the basal lamina glycoprotein laminin. All three lines synthesized laminin as judged by the incorporation of [35S]methionine into immunoreactive laminin and secreted (or shed) laminin into the culture medium as indicated by biosynthetic labeling studies and enzyme-linked immunosorbent assays. Immunoreactive laminin was also seen on the surface of the cells as indicated by immunofluorescence staining and by complement-mediated killing.

In vitro and in vivo interaction between murine fibrosarcoma cells and natural killer cells.

Murine fibrosarcoma cells were examined for sensitivity to killing by natural killer (NK) and natural cytotoxic lymphocytes from mouse spleens. These tumor cell lines were sensitive to killing by effector cells which were nonadherent to plastic or nylon wool, Thy-1 negative, asialo-GM1 negative, and present in the spleens of beige mice, nude mice, and A/J mice, as well as in the spleens of normal syngeneic and allogeneic control mice. This indicates that the cytotoxic effects were due to natural cytotoxic lymphocytes rather than to NK lymphocytes, T-cells, or macrophages.

Laminin inhibits the recognition of tumor target cells by murine natural killer (NK) and natural cytotoxic (NC) lymphocytes.

Tumor cells sensitive to lysis by murine natural killer (NK) or natural cytotoxic (NC) cells were shown to bind laminin. They bound 125I-labeled laminin in a time- and concentration-dependent manner, and binding of the radioactive laminin was inhibited by excess cold laminin. In the presence of laminin, cell-cell aggregation occurred.

Expression of a laminin-like substance on the surface of murine natural killer (NK) lymphocytes and its role in NK recognition of tumor target cells.

We have identified a structure on the surface of murine NK cells that is immunochemically cross-reactive with laminin. Treatment of normal CBA/J spleen cells with monospecific anti-laminin serum plus complement completely eliminated NK cytolytic activity against YAC-1 or RL male 1 target cells. In the absence of added complement, spleen cells preincubated with anti-laminin serum were also reduced in their cytolytic activity due to a reduced capacity to bind to the target cells.