429 research outputs found
New ruthenium complexes of fullerene C-60&C-70
The new complexes [Ru(NO)(PPh3)](2)(eta(2)-C-m)(m=60 1 or 70 2) have been prepared by heating a solution of C-60(or C-70) with [Ru(NO)(2)(PPh3)(2)] in toluene. They have been characterized by elemental analysis, IR, UV/VIS, XPS, C-13 and P-31 NMR spectroscopy. The photovaltaic effect for the new compounds has been studied
The extraordinary evolutionary history of the reticuloendotheliosis viruses
The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVs—unequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events
Synthesis and characterization for C-70(OsO4Py2)(3) complex
The fullerene complex, C-70 (OsO4Py2)(3), was prepared by the reaction of C-70 With OsO4 and Py in methylbenzene at room temperature. The new complex was characterized by elemental analysis, IR and electronic spectra. The complex structure was supposed
Synthesis and redox study for complex C60Pt (CO) (Pph(3))
Fullerene and it's dervant have unique poperties on physics and chemistry. The main purpose of the synthesis of new type fullerene complexes is to exploit the applications of fullerene and it's dervant as functional materials. The method of ligand substituting was employed, by which, the fullerene complexe C60Pt(CO) (Pph(3)) has been perpared by the reaction of C-60 replacing the ligands CO and Pph(3) in Pt(CO)(2) (Pph(3))(2) under a nitrogen atmosphere and refluxing. The tide compound was characterized by elemental analysis, FT-IR, UV-vis, XPS. The results show that the structure of purposeful product is that the ligands CO and Pph(3) take up two coordination sites of the central metal, and C-60 take up another two sites in sigma-pi feeback pattern. The electron flowing power of the molecule is strong, because of super conjugation in the molecule. The complexe may have super poperties on photo-electricity and catalysis. The result of redox research indicates that the reduction potential of the complexe is more negative than that of pure C-60
Co-expression of RON and MET is a prognostic indicator for patients with transitional-cell carcinoma of the bladder
Recepteur d'Origine Nantais (RON) is a distinct receptor tyrosine kinase in the c-met proto-oncogene family. We examined the mutational and expression patterns of RON in eight human uroepithelial cell lines. Biological effects of RON overexpression on cancer cells were investigated in vitro, and the prognostic significance of RON and/or c-met protein (MET) expression was analysed in a bladder cancer cohort (n=183). There was no evidence of mutation in the kinase domain of RON. Overexpression of RON using an inducible Tet-off system induced increased cell proliferation, motility, and antiapoptosis. Immunohistochemical analysis showed that RON was overexpressed in 60 cases (32.8%) of primary tumours, with 14 (23.3%) showing a high level of expression. Recepteur d'Origine Nantais expression was positively associated with histological grading, larger size, nonpapillary contour, and tumour stage (all P<0.01). In addition, MET was overexpressed in 82 cases (44.8%). Co-expressed RON and MET was significantly associated with decreased overall survival (P=0.005) or metastasis-free survival (P=0.01) in 35 cases (19.1%). Recepteur d'Origine Nantais-associated signalling may play an important role in the progression of human bladder cancer. Evaluation of RON and MET expression status may identify a subset of bladder-cancer patients who require more intensive treatment
Efficient control of atmospheric sulfate production based on three formation regimes
The formation of sulfate (SO₄²⁻) in the atmosphere is linked chemically to its direct precursor, sulfur dioxide (SO₂), through several key oxidation paths for which nitrogen oxides or NO_x (NO and NO₂) play essential roles. Here we present a coherent description of the dependence of SO₄²⁻ formation on SO₂ and NO_x under haze-fog conditions, in which fog events are accompanied by high aerosol loadings and fog-water pH in the range of 4.7–6.9. Three SO₄²⁻ formation regimes emerge as defined by the role played by NO_x. In the low-NO_x regime, NO_x act as catalyst for HO_x, which is a major oxidant for SO₂, whereas in the high-NO_x regime, NO₂ is a sink for HO_x. Moreover, at highly elevated NO_x levels, a so-called NO₂-oxidant regime exists in which aqueous NO₂ serves as the dominant oxidant of SO₂. This regime also exists under clean fog conditions but is less prominent. Sensitivity calculations using an emission-driven box model show that the reduction of SO₄²⁻ is comparably sensitive to the reduction of SO₂ and NO_x emissions in the NO₂-oxidant regime, suggesting a co-reduction strategy. Formation of SO₄²⁻ is relatively insensitive to NO_x reduction in the low-NO_x regime, whereas reduction of NO_x actually leads to increased SO₄²⁻ production in the intermediate high-NO_x regime
RyRCa2+ Leak Limits Cardiac Ca2+ Window Current Overcoming the Tonic Effect of Calmodulin in Mice
Ca2+ mediates the functional coupling between L-type Ca2+ channel (LTCC) and sarcoplasmic reticulum (SR) Ca2+ release channel (ryanodine receptor, RyR), participating in key pathophysiological processes. This crosstalk manifests as the orthograde Ca2+-induced Ca2+-release (CICR) mechanism triggered by Ca2+ influx, but also as the retrograde Ca2+-dependent inactivation (CDI) of LTCC, which depends on both Ca2+ permeating through the LTCC itself and on SR Ca2+ release through the RyR. This latter effect has been suggested to rely on local rather than global Ca2+ signaling, which might parallel the nanodomain control of CDI carried out through calmodulin (CaM). Analyzing the CICR in catecholaminergic polymorphic ventricular tachycardia (CPVT) mice as a model of RyR-generated Ca2+ leak, we evidence here that increased occurrence of the discrete local SR Ca2+ releases through the RyRs (Ca2+ sparks) causea depolarizing shift in activation and a hyperpolarizing shift inisochronic inactivation of cardiac LTCC current resulting in the reduction of window current. Both increasing fast [Ca2+]i buffer capacity or depleting SR Ca2+ store blunted these changes, which could be reproduced in WT cells by RyRCa2+ leak induced with Ryanodol and CaM inhibition.Our results unveiled a new paradigm for CaM-dependent effect on LTCC gating and further the nanodomain Ca2+ control of LTCC, emphasizing the importance of spatio-temporal relationships between Ca2+ signals and CaM function
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