Effect of Caloric Restriction on the Metabolism of Benzo[a]pyrene (BaP) and the Formation of BaP-DNA Adducts in Male Fischer 344 Rats

Abstract

The effect of caloric restriction (CR) on activities of xenobiotic metabolizing enzymes results in alterations in the metabolic activation of chemical carcinogens, with a resultant impact on DNA-carcinogen adduct formation. Using benzo[a]pyrene (BaP) as a model carcinogen, we have studied the effect of CR on the metabolic activation of BaP, in terms of both BaP metabolism and BaP-DNA adduct formation. Male Fischer 344 rats fed CR diets (60% of the food consumption of ad libitum?fed rats) showed higher activities of BaP metabolizing enzymes resulting in increases of BaP metabolism in vitro and BaP-DNA adduct formation in vivo. The results of the study of the effect of CR on the in vitro metabolism of BaP showed that CR increased the total BaP metabolism, as well as BaP-t-9, 10-diol and BaP-t-4, 5-diol formation. However, BaP-t-7, 8-diol, a proximate carcinogenic metabolite of BaP, was decreased by liver microsomes from CR-rats. Our results indicate that the effect of CR on metabolic activation of a chemical carcinogen was dependent upon the selected xenobiotic metabolizing enzymes whose activity may be significantly altered by CR.     

Solvothermal Synthesis,Crystal Structure and DNA Binding Studies of a 3D Supramolecular Complex {[Cu(phen)CN][Cu(phen)][Cu(CN)<Subscript>2</Subscript>]}<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> Assembled by Double Curvy Chains

A new cyano-bridged copper (I) complex {[Cu(phen)CN][Cu(phen)][Cu(CN)₂]} _n (1) (phen = 1,10-phenanthroline) was synthesized under the solvothermal conditions, and characterized by elemental analysis, FI-IR spectra and single-crystal X-ray diffraction. The structure analysis reveals that complex 1 contains two [Cu(phen)CN][Cu(phen)][Cu(CN)₂] subunits, being, respectively, constructed into two chains with different cyano backbones. The resulting chains offer a double curvy chain by Cu···Cu weak interactions and π–π stacking interactions. It is exciting that the double curvy chains adopt anti-parallel array and result in a novel 3D architecture through π–π stacking interactions. According to the supramolecular self-assembly of complex 1, four types of stacking mode of phenanthroline moieties are given and discussed. Absorption and fluorescence titration studies of complex 1 with calf thymus DNA are suggestive of the intercalation binding mode with a intrinsic binding constant of 7.52 × 10³ M⁻¹ and a linear Stern-Volmer quenching constant of 1.02 × 10⁵ M⁻¹.     

Influence of Zn-substitution on structural,morphological, electrical,and gas sensing properties of ZnxAl2O4 (x = 0.1 to 0.5) synthesized by a sol-gel auto-combustion method

The nanosphere decorated needle-like morphology of zinc-substituted aluminate having general formula Zn_xAl₂O₄ (x = 0.1, 0.2, 0.3, 0.4, and 0.5) (ZAN) samples were synthesized by a sol-gel auto-combustion method. The phase formation and stability temperature were confirmed by TG-DTA analysis. XRD study confirmed the formation of a cubic spinel structure of ZAN samples. The effect of Zn-substitution on structural and morphological properties of aluminate were investigated using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), and Energy dispersive X-ray analysis (EDAX). The D.C. electrical resistivity study of ZAN samples revealed that resistance decreased with increasing temperature confirmed semiconducting nature. Nanosphere existing on micro-needles of zinc-substituted aluminate gas sensor revealed sensing to several analyte gases such as H₂S, Cl₂, CH₃OH, SO₂, and NO₂ working at room temperature to 300 ^°C. The Zn_0·4Al₂O₄ compositional gas sensor produced the highest response at operating temperature 200 ^°C to 100 ppm H₂S. The results revealed that the prepared nanosphere decorated needles of the ZAN sensor was sensitive and selective to H₂S gas.     

Synthesis and electrochemical properties of layered Li[Li(1/3−x/3)CrxMn(2/3−2x/3)]O2 prepared by sol-gel method

The Li[Li_(1/3−x/3)Cr_xMn_(2/3−2x/3)]O₂ (0.15 ≤ x ≤ 0.3) cathode materials were synthesized by sol-gel process using aqueous solutions of metal acetates and citric acid as the chelating agent. The precipitate of metal citrate was dried in a vacuum oven for 10 h at 100 °C. After drying, the gel precursor was calcined at 300 °C for about 10 h. The resulted powder was ground and heated at 900 °C. The structural characterization was carried out by fitting the XRD data with Rietveld program. The samples exhibited a well defined layered structure and the unit cell parameters linearly increased with increasing chromium contents in Li[Li_(1/3−x/3)Cr_xMn_(2/3−2x/3)]O₂ Surface morphology was determined by SEM and HRTEM and it is found that the cathode material consisted of highly ordered single crystalline particles with layered-hexagonal structure. Test cells were assembled and cycled in the voltage range of 2.0-4.9 V with a current density of 7.947 mA/g. Electrode with (x = 0.2) delivered a high reversible capacity of around 280 mA h/g in cycling.     

Stabilisation of Au and Au in the same complex molecule by a tridentate phosphinodithiolate ligand. Structures of [AuLCl] and [AuL2Au] (L = {PhP(C6H3S-2-SiMe3-3)2})

The reaction of the organometallic complex [Au^III(damp-C^I,N)Cl₂] (damp-C,N⁻ = dimethylaminomethylphenyl) with PhP(C₆H₃SH-2-SiMe₃-3) ₂, H₂L, results in cleavage of the AuC bond and the formation of [Au^IIILCl] and [Au^IL₂Au^III] complexes. The square coordination environment of gold in [AuLCl] is noticeably distorted (maximum deviation from planarity: 0.326(1) Å) by the steric requirements of the tridentate chelating ligand, but the oxidation state ‘+3’ of the metal is retained. [Au^IL₂Au^III] contains gold atoms in both square-planar (Au^III) and linear (Au^I) coordination environments. The square-planar Au^III is bound by two trans-chelated PS units, and the two remaining thiolate groups provide the linear coordination of Au^I. The Au-Au distance is 2.919(1) Å, indicative of a weak bonding interaction.     

Synthesis of a poly(methyl methacrylate)‐b‐poly[2‐(N,N‐dimethylamino) ethyl methacrylate] block copolymer and its effects on the surface charges and pH‐responsive properties of poly(vinylidene fluoride) blend membranes

A poly(methyl methacrylate) (PMMA)‐b‐poly[2‐(N,N‐dimethylamino) ethyl methacrylate] (PDMAEMA) block copolymer was successfully synthesized by a reversible addition–fragmentation chain‐transfer method. The resulting copolymer was used to prepare poly(vinylidene fluoride) blend membranes via a phase‐inversion technique. The polymorphism, structure, and properties of the blend membranes were investigated by Fourier transform infrared spectrometry, scanning electron microscopy (SEM), ζ potential analysis, and filtration. The results indicate that PMMA‐b‐PDMAEMA could migrate onto the surface of the membrane during the coagulation process, and more of the β‐crystal phase appeared with the increase of the block copolymer in the membranes. The surface morphology and cross section of the membranes were also affected by the copolymer, as shown by SEM. The ζ‐potential results show that the surface charges of the membrane could be changed from positive to negative at an isoelectric point as the pH increased. The blend membrane also exhibited good pH sensitivity, and its water flux showed a great dependence on pH. The filtration experiment also indicated that the blend membrane had good hydrophilicity and antifouling properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40685.     

Crystallographic order and decomposition of [MnIII6CrIII]3+ single-molecule magnets deposited in submonolayers and monolayers on HOPG studied by means of molecular resolved atomic force microscopy (AFM) and Kelvin probe force microscopy in UHV

Monolayers and submonolayers of [Mn ^III ₆ Cr ^III ] ³⁺ single-molecule magnets (SMMs) adsorbed on highly oriented pyrolytic graphite (HOPG) using the droplet technique characterized by non-contact atomic force microscopy (nc-AFM) as well as by Kelvin probe force microscopy (KPFM) show island-like structures with heights resembling the height of the molecule. Furthermore, islands were found which revealed ordered 1D as well as 2D structures with periods close to the width of the SMMs. Along this, islands which show half the heights of intact SMMs were observed which are evidences for a decomposing process of the molecules during the preparation. Finally, models for the structure of the ordered SMM adsorbates are proposed to explain the observations.     

Characterisation of cellulose treated by the steam explosion method. Part 3: Effect of crystal forms (cellulose I,II and III) of original cellulose on changes in morphology,degree of polymerisaion,solubility and supermolecular structure by steam explosion

An attempt was made to clarify the effect of the crystal form of untreated cellulose on the morphological and structural changes of cellulose during steam explosion treatment (steam pressure P = 2.9MPa (T = 508K), treatment time t = 15-300 s). For this purpose, the crystal form of soft wood pulp (cellulose I) was converted by solid-to-solid transition, with minimal unavoidable change in other structural characteristics including morphology and average degree of polymerisation, into cellulose II or cellulose III. It was proved by both X-ray and solid-state cross-polarisation/magic-angle sample-spinning (CP/MAS) ¹³C NMR analyses that even a simple addition of water at room temperature brought about a significant structural change in the steam-untreated cellulose samples. The solubility towards 9.1 wt% aqueous sodium hydroxide, S_a, of the cellulose samples of crystal forms I and III could be improved from 31-33% up to almost 100% by selecting appropriate steam explosion conditions (for example, P = 2.9MPa, t = 30 s). Such a magnificent increase in S_a by the steam explosion treatment was not observed for the cellulose II sample, even under the rather severe conditions of the steam explosion treatment at which the cellulose III crystal was converted to a large extent to cellulose I, as confirmed by X-ray diffraction. X-ray diffraction analysis showed that crystallisation of samples with cellulose I or II crystal occurred to some extent during the steam explosion treatment. Contrary to this, the degree of breakdown of the intramolecular hydrogen bond O₃…O'₅, as estimated by CP/MAS ¹³C NMR analysis, significantly increased for cellulose I and I11 during the treatment. The decrease in the viscosity-average degree of polymerisation, P, observed for all treated samples can be roughly categorised into two or three steps of the first-order decomposition reaction with different reaction rates.