385 research outputs found

    Recursion Operator and Local and Nonlocal Symmetries of a New Modified KdV Equation

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    The recursion operator of a new modified KdV equation and its inverse are explicitly given. Acting the recursion operator and its inverse on the trivial symmetry 0 related to the identity transformation, the infinitely many local and nonlocal symmetries are obtained. Using a closed finite dimensional symmetry algebra with both local and nonlocal symmetries of the original model, some symmetry reductions and exact solutions are found

    Combining Transfer of TTF-1 and Pax-8 Gene: a Potential Strategy to Promote Radioiodine Therapy of Thyroid Carcinoma

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    Cotransfer of TTF-1 and Pax-8 gene to tumor cells, resulting in the reexpression of iodide metabolism-associated proteins, such as sodium iodide symporter (NIS), thyroglobulin (Tg), thyroperoxidase (TPO), offers the possibility of radioiodine therapy to non-iodide-concentrating tumor because the expression of iodide metabolism-associated proteins in thyroid are mediated by the thyroid transcription factors TTF-1 and Pax-8. The human TTF-1 and Pax-8 gene were transducted into the human thyroid carcinoma (K1 and F133) cells by the recombinant adenovirus, AdTTF-1 and AdPax-8. Reexpression of NIS mRNA and protein, but not TPO and Tg mRNA and protein, was detected in AdTTF-1-infected F133 cells, following with increasing radioiodine uptake (6.1~7.4 times), scarcely iodide organification and rapid iodide efflux (t1/2≈8 min in vitro, t1/2≈4.7 h in vivo).
In contrast, all of the reexpression of NIS, TPO and Tg mRNA and proteins in F133 cells were induced by the synergetic effect of TTF-1 and Pax-8. AdTTF-1 and AdPax-8 coinfected K1 and F133 cells could effectively accumulate radioiodine (6.6-7.5 times) and obviously retarded radioiodine retention (t1/2≈25-30 min in vitro, t1/2≈12 h in vivo) (p<0.05).
Accordingly, the effect of radioiodine therapy of TTF-1 and Pax-8 cotransducted K1 and
F133 cells (21-25% survival rate in vitro) was better than that of TTF-1-transducted cells
(40% survival rate in vitro) (p<0.05). These results indicate that single TTF-1 gene transfer may have limited efficacy of radioiodine therapy because of rapid radioiodine efflux. The cotransduction of TTF-1 and Pax-8 gene, with resulting NIS-mediated radioiodine accumulation and TPO and Tg-mediated radioiodine organification and intracellular retention, may lead to effective radioiodine therapy of thyroid carcinoma

    Akt-mediated signaling is induced by cytokines and cyclic adenosine monophosphate and suppresses hepatocyte inducible nitric oxide synthase expression independent of MAPK P44/42

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    AbstractCyclic AMP inhibits the expression of nitric oxide synthase (Harbrecht et al., 1995 [1]) in hepatocytes but the mechanism for this effect is incompletely understood. Cyclic AMP can activate several intracellular signaling pathways in hepatocytes including Protein Kinase A (PKA), cAMP regulated guanine nucleotide exchange factors (cAMP-GEFs), and calcium-mediated Protein Kinases. There is considerable overlap and cross-talk between many of these signaling pathways, however, and how these cascades regulate hepatocyte iNOS is not known. We hypothesized that Akt mediates the effect of cAMP on hepatocyte iNOS expression. Hepatocytes cultured with cytokines and dbcAMP increased Akt phosphorylation up to 2h of culture. Akt phosphorylation was inhibited by the PI3K inhibitor LY294002 (10μM), farnyltranferase inhibitor FTI-276, or transfection with a dominant negative Akt. The cyclic AMP-induced suppression of cytokine-stimulated iNOS was partially reversed by LY294002 and FTI-276. LY294002 also increased NFκB nucleus translocation by Western blot analysis in nuclear extracts. Cyclic AMP increased phosphorylation of Raf1 at serine 259 which was blocked by LY294002 and associated with decreased MAPK P44/42 phosphorylation. However, inhibition of MAPK P44/42 signaling with PD98059 failed to suppress cytokine-induced hepatocyte iNOS expression and did not enhance the inhibitory effect of dbcAMP on iNOS production. A constitutively active MAPK P44/42 plasmid had no effect on cytokine-stimulated NO production. These data demonstrate that dbcAMP regulates hepatocyte iNOS expression through an Akt-mediated signaling mechanism that is independent of MAPK P44/42

    Asymptotic lower bounds for Gallai-Ramsey functions and numbers

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    For two graphs G,HG,H and a positive integer kk, the \emph{Gallai-Ramsey number} grk(G,H){\rm gr}_k(G,H) is defined as the minimum number of vertices nn such that any kk-edge-coloring of KnK_n contains either a rainbow (all different colored) copy of GG or a monochromatic copy of HH. If GG and HH are both complete graphs, then we call it \emph{Gallai-Ramsey function} GRk(s,t){\rm GR}_k(s,t), which is the minimum number of vertices nn such that any kk-edge-coloring of KnK_n contains either a rainbow copy of KsK_s or a monochromatic copy of KtK_t. In this paper, we derive some lower bounds for Gallai-Ramsey functions and numbers by Lov\'{o}sz Local Lemma.Comment: 11 page

    Recursion Operator and Local and Nonlocal Symmetries of a New Modified KdV Equation

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    The recursion operator of a new modified KdV equation and its inverse are explicitly given. Acting the recursion operator and its inverse on the trivial symmetry 0 related to the identity transformation, the infinitely many local and nonlocal symmetries are obtained. Using a closed finite dimensional symmetry algebra with both local and nonlocal symmetries of the original model, some symmetry reductions and exact solutions are found

    Overexpression of Pear (Pyrus pyrifolia) CAD2 in Tomato Affects Lignin Content

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    PpCAD2 was originally isolated from the ‘Wangkumbae’ pear (Pyrus pyrifolia Nakai), and it encodes for cinnamyl alcohol dehydrogenase (CAD), which is a key enzyme in the lignin biosynthesis pathway. In order to verify the function of PpCAD2, transgenic tomato (Solanum lycopersicum) ‘Micro-Tom’ plants were generated using over-expression constructs via the agrobacterium-mediated transformation method. The results showed that the PpCAD2 over-expression transgenic tomato plant had a strong growth vigor. Furthermore, these PpCAD2 over-expression transgenic tomato plants contained a higher lignin content and CAD enzymatic activity in the stem, leaf and fruit pericarp tissues, and formed a greater number of vessel elements in the stem and leaf vein, compared to wild type tomato plants. This study clearly indicated that overexpressing PpCAD2 increased the lignin deposition of transgenic tomato plants, and thus validated the function of PpCAD2 in lignin biosynthesis
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