Consequence of boar edible tissue consumption on urinary profiles of nandrolone metabolites. II. Identification and quantification of 19-norsteroids responsible for 19-norandrosterone and 19-noretiocholanolone excretion in human urine

In previous work (Le Bizec et al., Rapid Commun. Mass Spectrom. 2000; 14: 1058), it was demonstrated that a boar meal intake could lead to possible false accusations of abuse of 17beta-nortestosterone in antidoping control. The aim of the present study was to identify and quantify endogenous 19-norsteroids in boar edible tissue at concentrations that can alter the steroid urinary profile in humans, and lead to excretion of 19-norandrosterone (19-NA) and 19-noretiocholanolone (19-NE). The samples were analysed in two laboratories. The methodologies used for extraction and detection (GC/MS(EI) and LC/MS/MS(APCI+)) are compared and discussed. 19-Norandrostenedione (NAED), 17beta- and 17alpha-nortestosterone (bNT, aNT), and 17beta- and 17alpha-testosterone (bT, aT) were quantified. The largest concentrations of NAED and bNT were observed in testicles (83 and 172 microg/kg), liver (17 and 63 microg/kg) and kidney (45 and 38 microg/kg). A correlation between the bNT and NAED content of a typical meal prepared with boar parts and the excreted concentrations of 19-NA and 19-NE in human urine was demonstrated.     

Frequency-dependent linear response of superconducting systems

We present a density functional scheme for calculating the frequency-dependent linear response of superconductors. The central result is a set of integral equations determining the linear response of the normal and anomalous densities to external perturbations. Analytic solutions of these integral equations are obtained for homogeneous systems with separable effective interactions. For inhomogeneous superconductors, the formalism leads to a scheme for calculating the critical temperature without explicitly solving the gap equation. © 1995 John Wiley & Sons, Inc.     

Asymmetric polymethine dyes based on thiazolo[3,2-a]quinoxalinium salts

Asymmetric carbocyanine dyes, the solutions of which are characterized by the presence of several absorption bands in the visible and near-IR regions, were synthesized from 4,5-dimethyl-1-oxo-2-phenyl-1,5-dihydrothiazolo[3,2-a]quinoxalin-3-ium perchlorate. Their deep color is due both to a more effective length of the condensed heterocyclic system and to the strong interaction of the electronic transitions, localized on the polymethine chain and on the heterocyclic ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1113–1116, August, 1992.     

Vegetable tanning substances. Dependence of the tanning properties of extracts on their composition

Information is given on vegetable tanning substances, their classification, distribution in the plant world, and structure, and the dependence of their tanning properties on their composition, and also on methods of enriching tanning extracts. The review of literature sources includes publications from 1950 to 1989.A. S. Sadykov Institute of Bioorganic Chemistry, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 293–307, May–June, 1990.     

Knoevenagel condensation of 2-carbethoxycyclohexanone and malononitrile: Synthesis of 4-cyano-3-ethoxy-1-hydroxy-5,6,7,8-tetrahydroisoquinoline,an isomer of the abnormal product

The structure of the abnormal product 1a formed in the Knoevenagel condensation of 2-carbethoxycyclohexanone and malononitrile has been further confirmed. Oxidation of the tetrahydroisoquinoline 3b using Na₂Cr₂O-AcOH-H₂SO₄ gave the keto isoquinoline 3d and the isoquinoline-1-carboxylic acid 5a. The acid chloride of 5a was condensed with diethyl ethoxymagnesiomalonate to afford after decarbethoxylation the methyl ketone 5d which on Baeyer-Villiger oxidation gave a mixture of the acetate 1g and the title compound 1b. The unambiguous synthesis of 1b confirms the structure assigned earlier to the title compound also formed during the partial hydrolysis of the diethoxy compound 1c. Condensation of 2-acetylcyclohexane-1,3-dione with malononitrile gave the quinoline derivative 4c which on ethylation yielded the ketoquinoline 4d. The present studies have confirmed that the quinoline compound 4a is also formed in the condensation of 2-acetylcyclohexanone and cyanoacetamide.     

Preparation of some complexes of the type (C6H5)3P[(CH3)2AsCH2CH(R)CH2As(CH3)2] M(CO)3 (M = Mo or W,R = H or C(CH3)3)

The title compounds, which contain six-membered chelate rings locked in the chair conformation, have been prepared by the reaction of (C₆H₅)₃P with the appropriate tetracarbonyl derivative in refluxing mesitylene.     

Pharmaceutical counterfeiting

Pharmaceutical counterfeiting is becoming a serious problem both in developed and developing countries. This paper considers the extent of the problem and provides several examples of drugs which have been counterfeited. Additionally, the effects of counterfeit products on consumers, health care providers, drug manufacturers and governments are discussed. Several of the currently used methods of detection are described and these include near-infrared spectroscopy, Raman spectroscopy, isotopic characterization, tensiography, chromatographic and mass spectrometric approaches. Finally, anti-counterfeiting measures such as the use of holograms, tracers and taggants and electronic tracking are summarized.     

Invariant manifolds of singularly perturbed ordinary differential equations

For singularly perturbed systems of ODE's satisfying a certain stability assumption the existence of an asymptotically stable (unstable) invariant manifold is proved. This invariant manifold is -close to the so-called reduced manifold of such a system. As an illustrative example a 3-dimensional autonomous system describing a model in biochemistry is considered.

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Zusammenfassung Für singulär gestörte Differentialgleichungssysteme, die einer gewissen Stabilitätsbedingung genügen, wird die Existenz einer asymptotisch stabilen (instabilen) invarianten Mannigfaltigkeit nachgewiesen, die in einer -Umgebung der sogenannten reduzierten Mannigfaltigkeit eines solchen Systems liegt. Als Anschauungsbeispiel wird ein dreidimensionales autonomes System betrachtet, welches ein biochemisches Modell beschreibt.

     

Stability and length of computations in the variational-difference method

The article considers a stable algorithm for computing the matrix and the righthand side of a variational-difference system of equations for one-dimensional nonsingular problems with a differential operator of order 2k. Since usually such systems are O(h^–2k) conditioned, an error in the coefficients in general leads to an asymptotic error O(h^–2k) in the solution of the system. A matrix subspace is identified in which an error leads to an error C in the solution of the system (in the energy norm) the constant C is independent of h), and then an algorithm is proposed which leaves the matrix computation error in this subspace. An approximate solution is represented as a sequence (a word) of elementary arithmetic operations, and a bound on the computation length is derived. A measure of the computation length is a nonnegative functional defined on the set of words of some alphabet which has certain desirable properties. Particular instances of this functional include the number of operations, the weighted average number of macroinstructions of different types, the computation time, etc.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 80, pp. 5–29, 1978.