Urinary analysis of 8-oxoguanine, 8-oxoguanosine, fapy-guanine and 8-oxo-2'-deoxyguanosine by high-performance liquid chromatography-electrospray tandem mass spectrometry as a measure of oxidative stress

A sensitive and specific assay aimed at measuring the oxidized nucleic acids, 8-oxoguanine (8-oxoGua), fapy-guanine (Fapy-Gua), 8-oxoguanosine (8-oxoGuo), 8-oxo-2'-deoxyguanosine (8-oxodG) has been developed by coupling reversed phase liquid chromatography (HPLC) with electrospray tandem mass spectrometry detection (MS/MS) and isotope dilution. The HPLC-MS/MS approach with multiple reaction monitoring (MRM) allowed for the sensitive determination of 8-oxoGua, Fapy-Gua, 8-oxoGuo, and 8-oxodG in human urine samples. There is no sample preparation needed except for the addition of buffer and (13)C- and (15)N-labeled internal standards to the urine prior to sample injection into the HPLC-MS/MS system. This method was tested in urine samples from non-smokers, smokers, non-smokers with chronic kidney disease (CKD) and smokers with CKD, to assess the level of oxidative damage to nucleic acids. Markers of both RNA and DNA damage were significantly increased in the smokers with and without CKD compared to their respective control subjects. These findings suggest that a highly specific and sensitive analytical method such as isotope dilution HPLC-MS/MS may represent a valuable tool for the measurement of oxidative stress in human subjects.     

The Uncertainty of Fluxes

In the ordinary quantum Maxwell theory of a free electromagnetic field, formulated on a curved 3-manifold, we observe that magnetic and electric fluxes cannot be simultaneously measured. This uncertainty principle reflects torsion: fluxes modulo torsion can be simultaneously measured. We also develop the Hamilton theory of self-dual fields, noting that they are quantized by Pontrjagin self-dual cohomology theories and that the quantum Hilbert space is -graded, so typically contains both bosonic and fermionic states. Significantly, these ideas apply to the Ramond-Ramond field in string theory, showing that its K-theory class cannot be measured.     

Some Remarks on p-Adic Analytic Groups

A theorem of Maranda [1, Section 30] states that if F is a finitegroup, p is a prime and p^e exactly divides |F|, then a Z_pF-latticeM is determined up to isomorphism by its finite quotient M/p^e+1M.If M is a free Z_p-module of rank d, this is equivalent to sayingthat representations of F in GL_d(Z_p) are determined up to equivalenceby their images modulo p^e+1. 1991 Mathematics Subject Classification20E18, 22E20.     

Some Polynuclear Coordination Compounds Precursors of Chromites Synthesis,Physicochemical Characterization and Thermal Stability

The polynuclear coordination compounds LnCr(tartrate)₃·nH₂O where Ln(III)=La-Er, obtained through a precipitation method, were characterized on the basis of elemental analysis, their electronic and vibrational spectra and magnetic susceptibility measurements. The possibility of obtaining chromites through the transformations of the polynuclear coordination compounds in the solid state was considered. The thermal decompositions of these compounds, studied by TG and DTA methods, were found to follow an almost uniform pattern. The decompositions occurred in six-eight steps. The first two steps involved dehydration, and the third the transformation of tartrate anions to oxalate, followed by conversion to carbonate and oxocarbonate intermediates. The final product in each case was LnCrO₃. A non-isothermal kinetic analysis of the first decomposition steps was performed, the most probable decomposition mechanism being selected and the kinetic parameters evaluated. The final products of the transformations were characterized. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the Apparent Compensation Effect Observed for Two Consecutive Reactions

A critical analysis is presented of the use of an overall single rate reaction equation instead of the true rate equation corresponding to a complex process consisting of two consecutive reactions. In accordance with this approximation, which is often used in the kinetic analysis of systems in which several reactions take place, the overall process is described by apparent activation parameters (the apparent activation energy E_ap and the apparent pre-exponential factor A_ap) and an apparent conversion function. The theoretical isotherms (α=α(t), where α is the conversion degree and t is time) were simulated for a system in which two consecutive reactions occur. In this case, the apparent activation parameters depend on (a) the considered range of temperature; and (b) the temperature for a given conversion degree. It is shown that the apparent activation parameters are correlated by the compensation effect relationship: ln A_ap = α^* + β^*E_ap where α^* and β^* are the linear regression parameters. The possibility of using the apparent kinetic parameters to predict the isotherms α=α(t) for temperatures lower than those for which these parameters were evaluated is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Water-soluble magnetic nanoparticles with biologically active stabilizers

We present the results of the interaction of iron oxide nanoparticles with some biologically active surfactants, namely, oleic acid and cytotoxic alkanolamine derivatives. Physico-chemical properties, as magnetization, magnetite concentration and particle diameter, of the prepared magnetic samples were studied. The nanoparticle size of 11 nm for toluene magnetic fluid determined by TEM is in good agreement with the data obtained by the method of magnetogranulometry. In vitro cytotoxic effect of water-soluble nanoparticles with different iron oxide:oleic acid molar ratio were revealed against human fibrosarcoma and mouse hepatoma cells. In vivo results using a sarcoma mouse model showed observable antitumor action.     

Homology stability for classical regular semisimple varieties

We use techniques from homotopy theory, in particular the connection between configuration spaces and iterated loop spaces, to give geometric explanations of stability results for the cohomology of the varieties of regular semisimple elements in the simple complex Lie algebras of classical type A, B or C, as well as in the group . We show that the cohomology spaces of stable versions of these varieties have an algebraic stucture, which identifies them as “free Poisson algebras” with suitable degree shifts. Using this, we are able to give explicit formulae for the corresponding Poincaré series, which lead to power series identities by comparison with earlier work. The cases of type B and C involve ideas from equivariant homotopy theory. Our results may be interpreted in terms of the actions of a Weyl group on its coinvariant algebra (i.e. the coordinate ring of the affine space on which it acts, modulo the invariants of positive degree; this space coincides with the cohomology ring of the flag variety of the associated Lie group) and on the cohomology of its associated complex discriminant variety. Received August 31, 1998; in final form August 1, 1999 / Published online October 30, 2000     

Development of a hybrid-fuzzy air temperature controller for a supersonic combustion test facility

 Hydrogen gas is burned in air to raise and maintain the stagnation temperature of a supersonic combustion test facility to a desired setpoint. In order to reach the desired operating conditions for stagnation temperature, there are three phases to the hydrogen control; H₂ ignition at facility start-up, H₂ ramp-up while the facility is ramped-up, and H₂ iteration to achieve the desired temperature setpoint. Each phase incorporates a different type of control. Fuzzy logic is used to design a computer based supervisory controller that recognizes the different phases of operation and chooses the appropriate control method. Received: 28 November 1999/Accepted: 2 November 2000     

Geometric applications of posets

We show the power of posets in computational geometry by solving several problems posed on a set S of n points in the plane: (1) find the n − k − 1 rectilinear farthest neighbors (or, equivalently, k nearest neighbors) to every point of S (extendable to higher dimensions), (2) enumerate the k largest (smallest) rectilinear distances in decreasing (increasing) order among the points of S, (3) given a distance δ > 0, report all the pairs of points that belong to S and are of rectilinear distance δ or more (less), covering k ≥ n/2 points of S by rectilinear (4) and circular (5) concentric rings, and (6) given a number k ≥ n/2 decide whether a query rectangle contains k points or less.