Search

Coordination polymers of transition metal ions are fascinating and important to coordination chemistry. One of the ligands known to form particularly interesting coordination polymers is 3,3′,5,5′-tetramethyl-4,4′-bipyrazole (Me4bpzH2). Group 11 metal(I) ion coordination polymers, other than those of copper(I), are relatively easy to handle because of their low reactivity towards dioxygen and moisture. However, the known silver(I) coordination polymers often have poor solubility in common solvents and so cannot be easily analyzed in solution. By using a tetramethyl substituted bipyrazole ligand, we have synthesized more soluble silver(I) complexes that contain the trifluoromethyl group in the coordinated ions CF3CO2− and CF3SO3− in [Ag(CF3CO2)(Me4bpzH2)] and [Ag(CF3SO3)(Me4bpzH2)]. We determined both structures by single-crystal X-ray analysis at low temperatures and compared them in detail. Moreover, we investigated the solution behavior of these coordination polymers by 1H-NMR, IR, Raman, UV–Vis spectroscopies, and their low-temperature, solid-state photoluminescence. The high-energy band at ~330 nm corresponded to ligand-centered (bipyrazole) fluorescence, and the low-energy band at ~400 nm to ligand-centered phosphorescence resulting from the heavy atom effect. [ABSTRACT FROM AUTHOR]

We have identified a myeloid cell‐specific enhancer in the 5′ flanking region of the Xenopus tropicalis myeloperoxidase gene. Transgenic reporter analysis using Xenopus laevis revealed that the expression of GFP was detected in the tail fin macrophages of a swimming tadpole, and the distributions of the GFP‐positive and XL‐2 (a pan‐marker for leukocytes)‐positive cells were mostly overlapping. The GFP‐positive cells in the liver of the transgenic tadpole were localized in the same areas where the myeloid cells were present. Isolation of leukocytes from the peripheral blood cells followed by flow cytometric analysis revealed that the GFP‐positive fraction was specifically enriched in neutrophils with lobulated nuclei. Furthermore, the macrophages purified from the peritoneal cavity were also GFP‐positive. In summary, a transgenic frog line in which the myeloid cells are labeled with GFP provides a useful tool to elucidate the physiological role of myeloid cells of multiple origins in the embryo. [ABSTRACT FROM AUTHOR]

Coordination polymers of transition metal ions are fascinating and important to coordination chemistry. One of the ligands known to form particularly interesting coordination polymers is 3,3',5,5'-tetramethyl-4,4'-bipyrazole (Me 4 bpzH 2 ). Group 11 metal(I) ion coordination polymers, other than those of copper(I), are relatively easy to handle because of their low reactivity towards dioxygen and moisture. However, the known silver(I) coordination polymers often have poor solubility in common solvents and so cannot be easily analyzed in solution. By using a tetramethyl substituted bipyrazole ligand, we have synthesized more soluble silver(I) complexes that contain the trifluoromethyl group in the coordinated ions CF 3 CO 2 - and CF 3 SO 3 - in [Ag(CF 3 CO 2 )(Me 4 bpzH 2 )] and [Ag(CF 3 SO 3 )(Me 4 bpzH 2 )] . We determined both structures by single-crystal X-ray analysis at low temperatures and compared them in detail. Moreover, we investigated the solution behavior of these coordination polymers by 1 H-NMR, IR, Raman, UV-Vis spectroscopies, and their low-temperature, solid-state photoluminescence. The high-energy band at ~330 nm corresponded to ligand-centered (bipyrazole) fluorescence, and the low-energy band at ~400 nm to ligand-centered phosphorescence resulting from the heavy atom effect.

The levels and types of immune responses are determined dependent on the extent of pathogen invasion, reactions to antigens mediated by macrophage-dendritic cells, T cells and antibodies. Recently, accumulating evidence suggests that B cells also play an important role in the regulation of immune responses. Here we have made a review to present a role of B cells in determining the level of immune responses and discussed about the clinical significance of B cell-targeted therapy in patients with autoimmune diseases. Type 1 diabetes is a T cell-mediated autoimmune disease characterized by the destruction of insulin-producing pancreatic beta cells. We and other groups have elucidated that B cells play a critical role in the development of insulitis and diabetes, as B-cell-deficient NOD mice are protected from developing type 1 diabetes. B cells are essential for the T cell receptor clonotype spreading of islet-infiltrating T cells, indicating that B cells may play a role in determining the level of immune responses by antigen presentation to antigen specific T cells. There are now numerous case reports and small series of clinical trials regarding rituximab therapy in autoimmune diseases, such as refractory autoimmune hemolytic anemia, IgM antibody-associated polyneuropathy, systemic lupus erythematosus and rheumatoid arthritis. Rituximab is a genetically engineered chimeric anti-CD 20 monoclonal antibody that is approved for the treatment of lymphoma. CD20 is a B-cell surface antigen that is expressed only on pre- B and mature B cells. Thus, rituximab causes a selective transient depletion of the CD20+ B -cell subpopulation. Rationale and strategy for targeting B cells in the treatment of autoimmune diseases consist of the inhibition of antigen-presentation and co-stimulation that induces T cell expansion and activation. Further careful mechanistic studies are required to develop therapies in patients with autoimmune diseases.