Drug Exposure and Risk of Microscopic Colitis: A Systematic Review and Meta-Analysis.

Background And Objectives: Microscopic colitis (MC) is a chronic inflammatory bowel disease characterized by watery diarrhoea and a normal radiological and endoscopic appearance. Concern regarding a potential association between drug exposure and MC has recently emerged. We sought to systematically review and summarize the evidence for the potential association.

ADHD, stimulant medication use, and the risk of fracture: a systematic review and meta-analysis.

Unlabelled: We performed a meta-analysis to quantify the relationships among a diagnosis of attention-deficit/hyperactivity disorder (ADHD), the use of stimulant medication, and the risk of fracture. There was a significant positive association between ADHD and the risk of fracture. However, stimulant ADHD medication therapy appears to be associated with a reduced risk of fracture in patients with ADHD.

Culturable Endophytes Diversity Isolated from and the Genetic Basis for Their Bioactivity.

Paeonia ostii is known for its excellent medicinal values as Chinese traditional plant. To date, the diversity of culturable endophytes associated with P. ostii is in its initial phase of exploration.

Theoretical study of the decomposition mechanisms and kinetics of the ingredients RDX in composition B.

RDX as a component in composition B (TNT + RDX) was first studied by us on its mechanism and kinetics of decomposition reactions in this paper. We have pointed out three possible pathways and found a new low-energy process of its decomposition. The N-N bond cleavage in composition B has higher dissociation energies than the monomer, but it is also the initial step.

[Determination of components in chromium-containing refractory with X-ray fluorescence spectrometry].

Components like SiO2, Al2 O3, Fe2O3, CaO, MgO and Cr2 O3 dominate the performance of chromium-containing amorphous refractory. That's still a hard task for product evaluation and quality control for amorphous refractory due to various component content, less available standard product and difficulty in fusion bead preparation. In the present study, series calibration standards were made from reagents and marked standards depend upon the content of components in real samples.

First-principles study of energetic complexes (II): (5-cyanotetrazolato-N2) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues.

First-principles methods using the TPSS density functional level of theory with the basis set 6-31G** were applied to study (5-cyanotetrazolato-N(2)) pentaammine cobalt (III) perchlorate (CP) and Ni, Fe and Zn analogues in the gas phase. The optimized lowest-energy geometry of CP was calculated from reported experimental structural data using the TPSS method. The calculated values are in good agreement with those measured by X-ray diffraction.

Theoretical study on the reactions of the cyclic trinitrogen radical toward oxygen and water.

Recently, the detection of the neutral simplest all-nitrogen ring, cyclic-N(3) radical, has been realized via various techniques, which has led to numerous studies on its structures, energetics, and spectroscopy. In particular, it has been postulated as a possible building block of high energy density materials. Yet, its intermolecular reactivity is poorly understood.

Molecularly imprinted monolith in-tube solid-phase microextraction coupled with HPLC/UV detection for determination of 8-hydroxy-2'-deoxyguanosine in urine.

Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) has been widely used as a biomarker of oxidative DNA damage. Measurements of 8-OHdG in urinary samples are challenging owing to the low level of 8-OHdG and the complex matrix. In this study, a novel molecularly imprinted polymer (MIP) monolithic column was synthesized with guanosine as a dummy template which was used as the medium for in-tube solid-phase microextraction (SPME).

Gaseous reaction mechanism between two H(2)CN radicals.

The self-recombination of the methylene amidogen radical (H(2)CN) is known to be fast and should play an important role in determining the concentration of H(2)CN radicals in both combustion and astrophysical processes. The rate constants of H(2)CN + H(2)CN have been determined by previous experiments, whereas its detailed evolution process and product distribution are still unclear. In this work, by means of quantum chemical and master equation calculations, we for the first time explored theoretically the potential energy surface and kinetics of the H(2)CN + H(2)CN reaction.

Theoretical studies on the tautomerism and intramolecular hydrogen shifts of 5-amino-tetrazole in the gas phase.

The tautomerism and intramolecular hydrogen shifts of 5-amino-tetrazole in the gas phase were studied in the present work. The minimum energy path (MEP) information of 5-amino-tetrazole was obtained at the CCSD(T)/6-311G**//MP2/6-311G** level of theory. The six possible tautomers of 1H, 4H-5-imino-tetrazole (a), 1H-5-amino-tetrazole (b), 2H-5-amino-tetrazole (c), 1H, 2H-5-imino-tetrazole (d), the mesoionic form (e) and 2H, 4H-5-imino-tetrazole (f) were investigated.

Theoretical study on reaction mechanism of fulminic acid HCNO with CN radical.

The HCNO + CN reaction is one potentially important process during the NO-reburning process for the reduction of NOx pollutants from fossil fuel combustion emissions. To compare with the recent experimental study, we performed the first theoretical potential energy surface investigation on the mechanism of HCNO + CN at the G3B3 and CCSD(T)/aug-cc-pVTZ levels based on the B3LYP/6-311++G(d,p) structures, covering various entrance, isomerization, and decomposition channels. The results indicate that the most favorable channel is to barrierlessly form the entrance isomer L1c NCCHNO followed by successive ring closure and concerted CC and NO bond rupture to generate the product P1 HCN + NCO.

The mechanism and kinetics of decomposition of 5-aminotetrazole.

The pathway and ab initio direct kinetics of the decomposition 5-aminotetrazole (5-ATZ) to HN(3) and NH(2)CN was investigated. Reactant, products and transition state were optimized with MP2 and B3LYP methods using 6-311G** and aug-cc-pVDZ basis sets. The intrinsic reaction coordinate curve of the reaction was calculated using the MP2 method with 6-311G** basis set.

Theoretical study on the methyl radical with chlorinated methyl radicals CH(3-n)Cln (n = 1, 2, 3) and CCl2.

Radical-radical reactions involving chlorinated methyl radicals are particularly important in the mechanism of combustion of chlorinated hydrocarbons. Yet, they are usually difficult to study experimentally. In this paper, four chloride-related radical-radical reactions, i.

An ignored but most favorable channel for NCO+C2H2 reaction.

The NCO+C(2)H(2) reaction has been considered as a prototype for understanding the chemical reactivity of the isocyanate radical towards unsaturated hydrocarbons in fuel-rich combustion. It has also been proposed to provide an effective route for formation of oxazole-containing compounds in organic synthesis, and might have potential applications in interstellar processes. Unfortunately, this reaction has met mechanistic controversy both between experiments and between experiments and theoretical calculations.

[Effects of PprI and RecX on antioxidant activity of Deinococcus radiodurans].

Effects of mutations of Pprl (Dr0167) and RecX (Dr1310), which are relative to radioresistance, on reactive oxygen species scavenging activities in Deinococcus radiodurans were investigated using gene mutation, chemiluminescence measurement and enzyme activity analysis. Their possible regulating functions on the activities of antioxidant enzymes was evaluated. Results show that mutant that lacks PprI is remarkably sensitive to reactive oxygen species and its enzyme activities of catalase and superoxide dismutase decrease significantly.

[Construction of the recQ double mutants and analysis of adversity in Deinococcus radiodurans].

As a subfamily member of SF1 superfamily, the RecO helicases are highly conserved in evolution and are required for maintaining genome stability in all organisms. Loss of RecO helicase function leads to a breakdown in the maintenance of genome integrity, in particular hyper-recombination. Named after the recQ gene of Escherichia coli, lower eukaryotic species generally only contain a single RecQ family representative; for example, Sgsl in the budding yeast, Saccharomyces cerevisiae, and Rqhl in the fission yeast, Schizosaccharomyces pombe.

[Geometric active contour model with color and intensity priors for medical image segmentation].

A new algorithm using the geometric active contour model with the fusion of color and intensity priors to segment medical images is presented in this paper. The prior knowledge used here are firstly defined in different color spaces and represented as thresholds searched by the genetic algorithm. Then the prior knowledge is merged into active contour model with its contour evolution by the level set technique.

Direct dynamics study on the hydrogen abstraction reaction CH2O + HO2 --> CHO + H2O2.

We present a direct ab initio dynamics study on the hydrogen abstraction reaction CH2O + HO2 --> CHO + H2O2, which is predicted to have four possible reaction channels caused by different attacking orientations of HO2 radical to CH2O. The structures and frequencies at the stationary points and the points along the minimum energy paths (MEPs) of the four reaction channels are calculated at the B3LYP/cc-pVTZ level of theory. Energetic information of stationary points and the points along the MEPs is further refined by means of some single-point multilevel energy calculations (HL).

The reaction of the aminoboranylidene-iminoborane isomerization: a CASSCF direct dynamics study.

The barrier and the potential-energy surface of the isomerization from aminoboranylidene (BNH2) to iminoborane (HBNH) have been studied using complete active space self-consistent field (CASSCF) with the 6-31 + G(d, p) basis set and higher-level energy methods. The rate constants of the isomerization reaction are reported by employing the direct ab initio dynamics method. The geometries of all the stationary points were optimized using the B3LYP and CCSD methods with the cc-pVTZ and cc-pVQZ basis sets.