Oxygen transfer reactions catalyzed by rhenium (VII) and rhenium (V) complexes

A new binuclear oxothiolatorhenium(V) compound, Re2O 2(MtP)3 (D1, mtp = 2-mercaptomethylthiophenol), was synthesized by reacting dirhenium(VII) heptoxide (Re2O 7) with H2mtp, and characterized spectroscopically and crystallographically. One Re-S bridge in D1 was opened, and sometimes D1 was monomerized, through ligand coordination. D1 was found to be an efficient catalyst for the oxidation of phosphines, triphenylarsine, triphenylantimony, sulfides and dimes by pyridine N-oxides, and unprecedently, by molecular oxygen. D1 also catalyzes the oxidation of phosphines by dimethylsulfoxide. The kinetics and mechanism for the oxidation of triarylphosphines by pyridine N-oxides and O2, as well as the relative reactivities of all substrates, were studied. The reaction was proposed to go through oxorhenium(VII) intermediates;Methyltrioxorhenium (MTO) catalyzes the two-step oxidation of thioketones by hydrogen peroxide to sulfines (thioketone Soxides) and to ketones releasing sulfur monoxide, which was trapped by a 1,3-diene. The kinetics and mechanism of both steps were studied. The substituted thiobenzophenones were found to attack the peroxo rhenium oxygen nucleophilically. The Hammett correlation of the second-order rate constants against the 2sigma values of the substituents is a straight line with a negative slope. Remarkably, a V-shaped Hammett plot was obtained for the oxidation of sulfines to ketones, with rate being accelerated with both electron-donating and withdrawing substituents. This suggests a mechanism for the sulfines in which the direction of the electron flow in the transition state changes with the electron demand of the substituents on the sulfines. The oxidation rate for the sulfine is less than 10 --3 times as fast as that of its parent thioketone. This makes the controlled oxidation of thioketones by the MTO/1 eq H2O 2 system a superior method for the synthesis of sulfines. A series of sulfines were synthesized in high yields with this method;The sulfur bridge of a binuclear platinum(I) complex, Pt2(mu-dppm) 2(mu-S)Cl2 (dppm = diphenylphosphinomethane), was oxidized step-wise to a sulfoxide, then sulfone by hydrogen peroxide catalyzed by MTO. The SO-bridged complex, Pt2(mu-dppm)2(mu-SO)Cl 2, was crystallographically characterized. The same compound was obtained by trapping the sulfur monoxide released from the oxidation of a sulfine by MTO/H2O2 with Pt2(mu-dppm)2Cl 2

Prevalence of the GJB2 IVS1+1G >A mutation in Chinese hearing loss patients with monoallelic pathogenic mutation in the coding region of GJB2

<p>Abstract</p> <p>Background</p> <p>Mutations in the GJB2 gene are the most common cause of nonsyndromic recessive hearing loss in China. In about 6% of Chinese patients with severe to profound sensorineural hearing impairment, only monoallelic <it>GJB2 </it>mutations known to be either recessive or of unclear pathogenicity have been identified. This paper reports the prevalence of the <it>GJB2 </it>IVS1+1G>A mutation in a population of Chinese hearing loss patients with monoallelic pathogenic mutation in the coding region of <it>GJB2</it>.</p> <p>Methods</p> <p>Two hundred and twelve patients, screened from 7133 cases of nonsyndromic hearing loss in China, with monoallelic mutation (mainly frameshift and nonsense mutation) in the coding region of <it>GJB2 </it>were examined for the <it>GJB2 </it>IVS1+1G>A mutation and mutations in the promoter region of this gene. Two hundred and sixty-two nonsyndromic hearing loss patients without <it>GJB2 </it>mutation and 105 controls with normal hearing were also tested for the <it>GJB2 </it>IVS1+1G>A mutation by sequencing.</p> <p>Results</p> <p>Four patients with monoallelic mutation in the coding region of <it>GJB2 </it>were found carrying the <it>GJB2 </it>IVS1+1G>A mutation on the opposite allele. One patient with the <it>GJB2 </it>c.235delC mutation carried one variant, -3175 C>T, in exon 1 of <it>GJB2</it>. Neither <it>GJB2 </it>IVS1+1G>A mutation nor any variant in exon 1 of <it>GJB2 </it>was found in the 262 nonsyndromic hearing loss patients without <it>GJB2 </it>mutation or in the 105 normal hearing controls.</p> <p>Conclusion</p> <p>Testing for the <it>GJB2 </it>IVS 1+1 G to A mutation explained deafness in 1.89% of Chinese <it>GJB2 </it>monoallelic patients, and it should be included in routine testing of patients with <it>GJB2 </it>monoallelic pathogenic mutation.</p

Topological orbit equivalence of locally compact Cantor minimal systems

Minimal homeomorphisms on the locally compact Cantor set are investigated. We prove that scaled dimension groups modulo infinitesimal subgroups determine topological orbit equivalence classes of locally compact Cantor minimal systems.･･

A Cell-Based β-Lactamase Reporter Gene Assay for the CREB Signaling Pathway

The Cyclic-AMP Response Element Binding (CREB) proteins comprise a family of transcription factors that stimulate or repress the expression of a wide variety of genes by binding to nucleotide sequences known as cAMP Response Elements. CREB-mediated transcription has been implicated in a wide variety of important physiological processes, including long-term memory, and enhancement of CREB signaling has been suggested as an attractive therapeutic strategy for human memory disorders. To identify small molecule compounds that enhance CREB pathway signaling, we have optimized and validated a cell-based β-lactamase reporter gene CREB pathway assay in 1536-well plate format. The LOPAC library of 1280 compounds was screened in triplicate in this assay on a quantitative high throughput screening (qHTS) platform. A variety of compounds which affect known members of the CREB pathway were identified as active, including twelve known phosphodiesterase (PDE) inhibitors, and forskolin, a known activator of adenylate cyclase, thus validating the assay’s performance. This qHTS platform assay will facilitate identification of novel small molecule CREB signaling enhancers, which will be useful for chemical genetic dissection of the CREB pathway and as starting points for potentially memory-enhancing therapeutics

Stability Analysis for a Fractional HIV Infection Model with Nonlinear Incidence

We introduce the fractional-order derivatives into an HIV infection model with nonlinear incidence and show that the established model in this paper possesses nonnegative solution, as desired in any population dynamics. We also deal with the stability of the infection-free equilibrium, the immune-absence equilibrium, and the immune-presence equilibrium. Numerical simulations are carried out to illustrate the results.Peer reviewe

Effects of Litchi chinensis fruit isolates on prostaglandin E2 and nitric oxide production in J774 murine macrophage cells

<p>Abstract</p> <p>Background</p> <p><it>Litchi chinensis </it>is regarded as one of the 'heating' fruits in China, which causes serious inflammation symptoms to people.</p> <p>Methods</p> <p>In the current study, the effects of isolates of litchi on prostaglandin E₂(PGE₂) and nitric oxide (NO) production in J774 murine macrophage cells were investigated.</p> <p>Results</p> <p>The AcOEt extract (EAE) of litchi was found effective on stimulating PGE₂production, and three compounds, benzyl alcohol, hydrobenzoin and 5-hydroxymethyl-2-furfurolaldehyde (5-HMF), were isolated and identified from the EAE. Benzyl alcohol caused markedly increase in PGE₂and NO production, compared with lipopolysaccharide (LPS) as positive control, and in a dose-dependent manner. Hydrobenzoin and 5-HMF were found in litchi for the first time, and both of them stimulated PGE₂and NO production moderately in a dose-dependent manner. Besides, regulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNA expression and NF-κB (p50) activation might be involved in mechanism of the stimulative process.</p> <p>Conclusion</p> <p>The study showed, some short molecular compounds in litchi play inflammatory effects on human.</p

Influence of viewing conditions on cross-media color matching

We investigated observer metamerism under a variety of viewing conditions, in a set of color-matching experiments using displays and printed color samples under specific light sources. A selection was made of light sources with different illuminances, spectral power distributions, and correlated color temperatures, as well as displays with different sets of primaries. A panel of 157 observers with normal color vision and ages between 20 and 59 years old performed 5465 visual color matches around 9 different color centers. The results from the simulated and real experiments were quite different. Specifically, the mean color difference from the mean changed with experimental viewing conditions, ranging from 0.73 to 1.64 CIELAB units (average 0.99 CIELAB units) in simulated experiments, and from 3.12 to 4.03 CIELAB units (average 3.55 CIELAB units) in real experiments. In real experiments, observers’ variability reduced for light sources with high illuminance and high correlated color temperature. Spectral power distributions affected observer metamerism, but the role played by the primaries of the two displays employed was unclear.National Natural Science Foundation of China (NNSFC), 61675029. Ministry of Economy and Competitiveness of the Government of Spain, co-financed by the European Regional Development Fund (ERDF) of the European Union, research project FIS2016-80983-P