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961.
Induction of Chromosome Aberrations and Delayed Genomic Instability by Photochemical Processes 总被引:1,自引:0,他引:1
Charles L. Limoli Joseph P. Day John F. Ward William F. Morgan 《Photochemistry and photobiology》1998,67(2):233-238
Exponentially growing cells cultured in medium containing bromodeoxyuridine, then exposed to UVA light in the presence of the dye Hoechst 33258, show significant levels of DNA strand breaks and base damage. This dye–bromodeoxyuridine–UVA photolysis treatment is markedly cytotoxic. We now demonstrate that exposure of cells to the agents used in photolysis leads directly to the formation of chromosome aberrations. Furthermore, we demonstrate that this photochemical treatment induces delayed chromosomal instability in clonal populations derived from single progenitor cells surviving photolysis. These results suggest that photolysis-induced DNA damage leads to chromosome rearrangements that could account for the observed cytotoxicity. Furthermore, in those cells surviving photolysis, the delayed effects of this treatment can be observed several generations after exposure and are manifested as compromised genomic integrity. 相似文献
962.
N.M.R. Spectroscopic Studies of 15N Labelled N-Phosphorylphosphazenes and Imidodiphosphoric Acid Derivatives 15N labelled compounds were prepared and investigated by means of 31P- and 15N-NMR spectroscopy. The chemical shift values δP and δN, and the coupling constants 1JPN and 2JPP are discussed and interpreted qualitatively by semiempirical quantumchemical calculations (CNDO/2) using POPLE 'S ΔE-model. 相似文献
963.
John Phillips 《Journal of Functional Analysis》1983,51(3):259-267
Let B be a unital C1-algebra and A = Γ(E) be the C1-algebra of sections of a bundle over the separable compact space X with fibre B and structure group Inn B. If B is the quotient of an AW1-algebra, then an exact sequence: 0 → Inn A → PInn A →ηH2(X, G), where PInn A is the group of pointwise inner automorphisms of A and G=H°(Z(B)^, ) is obtained. The map η is onto whenever A = C(X, B) and B is the quotient of a purely infinite AW1-algebra. An essential part of the analysis is the result that Ad: U(B) → Inn B is a fibre bundle if and only if the space of inner derivations of B is norm closed. These results extend and clarify previous joint work with I. Raeburn (Indiana Univ. Math. J.29 (1980), 799). 相似文献
964.
The reactions of [Co(η-C5H5)(L)I2] with Na[S2CNR2] (R = alkyl or phenyl) give [Co(η-C5H5)(I)(S2CNR2)] (I) when L = CO and [Co(η-C5H5)(L)(S2CNR2)]I (II) when L is a tertiary phosphine, phosphite or stibine, or organo-isocyanide ligand. In similar reactions [Co(η-C5H5)(CO)(C3F7)I] gives [Co(η-C5H5)(C3F7)(S2CNMe2)] and [Mn(η-MeC5H4)(CO)2(NO)]PF6 forms [Mn(η-MeC5H4)(NO)(S2CNR2)]. The iodide ligands in I may be displaced by L, to give II, or by other ligands such as [CN]?, [NCS]?, H2O or pyridine whilst SnCl2 converts it to SnCl2I. The iodide counter-anion in II may be replaced by others to give [BPh4]?, [Co(CO)4]? or [NO3]? salts. However [CN]? acts differently and displaces (PhO)3P from [Co(η-C5H5){P(OPh)3}(S2CNMe)]I to give [Co(η-C5H5)(CN)(S2CNMe2)] which may be alkylated reversibly by MeI and irreversibly by MeSO3F to [Co(η-C5H5)(CNMe)(S2CNMe2)]+ salts. Conductivity measurements suggest that solutions of I in donor solvents are partially ionized with the formation of [Co(η-C5H5)(solvent)(S2CNR2)]+ I? species. The IR and 1H NMR spectra of the various complexes are reported. They are consistent with pseudo-octahedral “pianostool” molecular structures in which the bidentate dithiocarbamate ligands are coordinated to the metal atoms through both sulphur atoms. 相似文献
965.
John Raymond O'Lear Larry Gene Wright John Nathan Louris R. Graham Cooks 《Journal of mass spectrometry : JMS》1987,22(6):348-358
A new scan is described which responds to ions that are intermediates in the dissociation of a mass-selected parent ion (mp) to give a mass-selected daughter ion (md). The scan gives a simple mass v. abundance output for ions which satisfy this condition. It is implemented here on a BEQQ hybrid mass spectrometer using, in sequence, collision-induced dissociation occurring at high energy in the first reaction region, and low-energy collisional activation in the collision quadrupole. The experiment provides information on reaction sequences not available from single scans of other types. In the several cases examined, it is demonstrated that, among many conceivable fragmentation routes connecting a parent ion with a particular fragment ion, only a few are significant. Examination of reaction intermediate spectra also appears to be a fruitful new approach to mechanistic questions, as illustrated by consideration of the behavior of several isomeric octanones. These new spectra also have analytical value: they show good signal-to-noise ratios and allow ready distinction between isobaric and isomeric ions. A comparison of the reaction intermediate spectrum with a daughter spectrum obtained by the B/E linked-scanning technique reveals the contributions of artifact peaks which result from poor parent ion mass resolution in the latter. Reaction intermediate spectra combine information from the daughter spectra of mp and the parent spectra of md and, as a specified portion of this data domain, have unique characteristics. 相似文献
966.
A series of 4-(2-keto-substituted)-3,4-dihydro-3-methyl-2H-1,3-benzoxazin-2-ones 1 (Table I) was synthesized by condensation of 3-alkyl-3,4-dihydro-4-hydroxy-2H-1,3-benzoxazin-2-ones 4 with ketones 5 having active alpha hydrogens. In the presence of alcoholic potassium borohydride, compounds 1 underwent reductive transacylation to give 1,3-oxazin-2-one derivatives 3 (Table III, a,b,c). When the other side of the ketone possessed substituents other than hydrogen, there were always also normal reduction products, i.e., secondary alcohols 2 (Table II) in addition to 3. 相似文献
967.
Summary The complexes M(acac)2(imidazole)2 (M = Co or NO and [M(acac)2B]n (M = Co, Ni or Zn; B = pyrazine or pyrimidine) have been prepared and their i.r. spectra determined over the 600–140 cm–1. range. The metal-oxygen and metal-nitrogen stretching frequencies, (M-O) and v(M-N), are assigned on the basis of the band shifts induced by deuteriation of the adducted base and by substitution of the metal ion. Three or fourv(M-O) bands are observed within the 600-200 cm–1 range. The twov(M-O) bands of higher frequency are considered to the coupled with internal ligand modes. TwovM-N) bands are observed within the 280–170 cm–1. range. The metal-ligand stretching frequencies are in good agreement with the values previously established for these vibrations in the [M(imidazole)6]2+ and Ni(acac)2(pyridine)2 complexes. 相似文献
968.
The main purpose of this paper is to present accurate infrared integrated intensities of liquid toluene, C6H5CH3, at 25 °C. Also presented are the decadic molar absorption coefficients, Em, the real and imaginary dielectric constants, ε′ and ε″, and the real and imaginary molar polarizabilities, ′m and ″m. Integrated intensities were determined as Cj, the area under bands in the spectrum, for all bands between 4800 and 440 cm−1. The contributions from the different bands were separated by fitting the spectrum with classical damped harmonic oscillator bands. The uncertainties in the integrated intensities of most bands are estimated to be 5–10%, with the uncertainties in very weak bands and in shoulders possibly up to 100%. The intensity that should be assigned to the fundamentals is more difficult to estimate due to Fermi resonance with overtone and combination bands, and a best estimate is given. The integrated intensities of the fundamental vibrations and the corresponding transition dipole moments are summarized and are compared with literature values for the gas. 相似文献
969.
We report the first high-frequency and -field electron paramagnetic resonance (HFEPR) study of a Mn(III) N-confused porphyrin (NCP) complex (NCP is also known as inverted porphyrin or 2-aza-21-carbaporphyrin). We have found a striking variation in the electronic properties of the S = 2 Mn(III) ion coordinated by NCP compared to other Mn(III) porphyrinoid complexes. Thus, inversion of a single pyrrole ring greatly changes the equatorial ligand field exerted and leads to large magnitudes of both the axial and rhombic zero-field splitting [respectively, D = -3.084(3) cm(-1), E = -0.608(3) cm(-1)], which are unprecedented in other Mn(III) porphyrinoids. 相似文献
970.
John L. Spouge 《Journal of statistical physics》1983,31(2):363-378
This paper gives the equilibrium distribution of polymer sizes for Flory'sA
g
RB
f–g model of polymerization. In this model, the polymers are composed of structural units withg functional groups of the typeA and (f-g) functional groups of the typeB. Reaction is subject to three conditions: (1) Functional groups of the typeA react only with those of typeB, and vice versa. (2) Intramolecular reactions do not occur [and therefore only branched-chain (noncyclic) polymers and formed]. (3) Subject to conditions (1) and (2), all functional groups are equally reactive. The derivation employs Stockmayer's statistical mechanical method (first used on Flory'sRA
f model), coupled with a recursion giving the number of distinct polymers which may be assembled fromk units of theA
g
RB
f–g type. We also give distributions for a limiting case of theA
g
RB
f–g model, the so-calledA
g
RB
model. This paper completes the solution of the Smoluchowski coagulation equation (monodisperse case) for the kernelsa
ij =A + B(i +j)+ Cij. The proof will be given in another publication. 相似文献