Biomedical subjects

Christoph Wagner

Publications and source records attributed to Christoph Wagner.

10 recordsLinked to original sources

PubMed2005

Risk factors for the intermediate outcome of morbid obesity after laparoscopically placed adjustable gastric banding.

BACKGROUND: The overall long-term results of medical treatment for morbid obesity are poor. Surgery is the only treatment option to obtain long-term weight reduction. Analysis of risk factors for treatment success of laparoscopically placed gastric banding (LGB) has not been available until now. METHODS: Prospective study with 99 patients with LGB between January 1997 and July 2003. The parameters assessed as risk factors included onset of obesity, feeling of postprandial satiety, and initial body mass index (BMI). RESULTS: Median follow-up was 36 months (3 to 72). Independent prognostic factors of excess body weight reduction (>25%) were for the first postoperative year: onset of obesity as an adolescent (relative risk [RR] 0.21), an initial BMI <45 kg/m(2) (RR 4.76), and a BMI between 45.1 and 50 kg/m(2) (RR 3.23). After the second year, independent prognostic factors were as follows: feeling of postprandial satiety (RR 5.26) and an initial BMI <45 kg/m(2) (RR 3.03). CONCLUSION: LGB is suitable to achieve intermediate weight reduction in patients with morbid obesity. To obtain the best results, patients should be treated before they achieve a BMI >45 kg/m(2). Additionally a postprandial feeling of satiety after LGB is mandatory for good long-term results.

Adult↗

PubMed2004

Reaction properties of the trans-hyponitrite complex [Ru2(CO)4(mu-H)(mu-PBu(t)2)(mu-Ph2PCH2PPh2)(mu-eta2-ONNO)].

The protonation of [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNO)] (1) with HBF(4) occurs at the oxygen of the noncoordinating side of the trans-hyponitrite ligand to give [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOH)][BF(4)] (2) in good yield. The monoprotonated hyponitrite in 2 is deprotonated easily by strong bases to regenerate 1. Furthermore, 1 reacts with the methylating reagent [Me(3)O][BF(4)] to afford [Ru(2)(CO)(4)(mu-H)(mu-PBu(t)()(2))(mu-dppm)(mu-eta(2)-ONNOMe)][BF(4)] (3). The molecular structures of 2 and 3 have been determined crystallographically, and the structure of 2 is discussed with the results of the DFT/B3LYP calculations on the model complex [Ru(2)(CO)(4)(mu-H)(mu-PH(2))(mu-H(2)PCH(2)PH(2))(mu-eta(2)-ONNOH)](+) (2a). Moreover, the thermolysis of 2 in ethanol affords [Ru(2)(CO)(4)(mu-H)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)][BF(4)] (4) in high yield, and the deprotonation of 4 by DBU in THF yields the novel complex [Ru(2)(CO)(4)(mu-OH)(mu-PBu(t)()(2))(mu-dppm)] (5).

Borates↗

PubMed2004

Protonated nucleobase ligands: synthesis, structure and characterization of 9-methyladeninium hexachloroplatinate and pentachloro(9-methyladeninium)platinum(IV).

Na(2)[PtCl(6)] was found to react with (9-MeAH)Cl(.)H(2)O (2) (9-MeA=9-methyladenine) in aqueous solution yielding (9-MeAH)(2)[PtCl(6)](.)2H(2)O (3). The same compound was obtained from hexachloroplatinic acid and 9-methyladenine. Performing this reaction at 60 degrees C, complex formation took place yielding the 9-methyladeninium complex [PtCl(5)(9-MeAH)](.)2H(2)O (4a). An analogous complex, [PtCl(5)(9-MeAH)](.)1/2(18C6)(.)H(2)O (4b, 18C6=crown ether 18-crown-6), was formed in the reaction of aquapentachloroplatinic acid (H(3)O)[PtCl(5)(H(2)O)](.)2(18C6)(.)6H(2)O (1) with 9-methyladenine in 1:1 ratio. All complexes were isolated in moderate to good yields as yellow powder (4b) and crystals (3, 4a), respectively. They were fully characterized by microanalysis, IR and NMR ((1)H, (13)C, (195)Pt) spectroscopies, and in part (2, 3, 4a) also by single-crystal X-ray diffraction analysis. Molecular structure of complex 4a exhibited that the 9-methyladeninium ligand is N1 protonated and coordinated through N7 to platinum(IV).

Adenine↗

PubMed2003

Ferromagnetism in a dinuclear nickel(II) complex containing triethylenetetramine and tricyanomethanide.

Triethylenetetramine (L(4)) was used as a tetradentate blocking ligand that, after complexation with Ni(II), leaves two sites ready for ligation with tricyanomethanide. The formed binuclear complex [L(4)Ni(NCC(CN)CN)(2)NiL(4)](ClO(4))(2) exhibits a ferromagnetic coupling with J/hc = +0.15 cm(-1) and g(Ni) = 2.126; below 16 K, a ferromagnetic ordering is evidenced by ac magnetic susceptibility (both in-phase and out-of-phase), magnetization, field-cooled magnetization, and zero-field-cooled magnetization measurements.

Journal Article↗

PubMed2003

Information theoretical optimization for optical range sensors.

Most of the known optical range sensors require a large amount of two-dimensional raw data from which the three-dimensional (3D) data are decoded and so are associated with considerable cost. The cost arises from expensive hardware as well as from the time necessary to acquire the images. We will address the question of how one can acquire maximum shape information with a minimum amount of image raw data, in terms of information theory. It is shown that one can greatly reduce the amount of raw data needed by proper optical redundancy reduction. Through these considerations, a 3D sensor is introduced, which needs only a single color (red-green-blue) raw image and still delivers data with only approximately 2-microm longitudinal measurement uncertainty.

Journal Article↗

PubMed2003

Low-dimensional compounds containing cyano groups. VI. A unique two- and one-dimensional structure in amminebis(1,4-diaminobutane)tetrakis[dicyanoargentato(I)]dicopper(II) dihydrate.

The title compound, [Cu(2)(C(4)H(12)N(2))(2)(Ag(CN)(2))(4)(NH(3))].2H(2)O or [Ag(4)Cu(2)(CN)(8)(C(4)H(12)N(2))(2)(NH(3))].2H(2)O, contains two crystallographically different Cu(II) atoms lying on twofold axes. The first Cu atom is hexacoordinated in the form of an elongated tetragonal bipyramid and is part of a plane in which Cu atoms are connected by two bridging diaminobutane molecules [Cu-N = 2.033 (4) A] and two dicyanoargentate anions [Cu-N = 2.622 (6) A]. The ammine ligand stands perpendicular to this plane [Cu-N = 2.011 (6) A] in a trans position to it. Another [Ag(CN)(2)](-) anion connects the hexacoordinated Cu atom [Cu-N = 1.997 (8) A] with the second Cu atom [Cu-N = 2.026 (7) A], which is pentacoordinated in the form of a slightly distorted trigonal bipyramid by two monodentate dicyanoargetate anions [Cu-N = 2.040 (5) A]. The axial positions are occupied by two bridging diaminobutane molecules [Cu-N = 2.011 (4) A] that connect the Cu atoms into chains parallel to the above plane. The water molecules remain uncoordinated and thus a unique combination of two- and one-dimensional structures is formed.

Journal Article↗

PubMed2003

Low-dimensional compounds containing cyano groups. VII. (Dicyanamido-kappaN1)bis(1,10-phenanthroline-kappa2N,N')copper(II) trifluoromethanesulfonate.

The title compound, [Cu(C(2)N(3))(C(12)H(8)N(2))(2)](CF(3)SO(3)), is formed by discrete [Cu(phen)(2)(N(CN)(2)))](+) complex cations (phen is 1,10-phenanthroline) and uncoordinated CF(3)SO(3)(-) anions. The Cu centre is five-coordinated in the form of a distorted trigonal bipyramid to two phen molecules and one dicyanamide ligand, which is coordinated through one nitrile N atom in the equatorial plane at a distance of 1.990 (2) A. The two axial Cu-N distances are similar (mean 1.993 A) and are substantially shorter than the two equatorial Cu-N bonds (mean 2.125 A).

Journal Article↗

PubMed2002

Synthesis and use of alpha-silyl-substituted alpha-hydroxyacetic acids.

[reaction: see text] Rhodium-catalyzed oxygen transfer was used to generate benzyl 2-silyl-2-oxoacetates in good yields. The hydrogenation of these compounds led to chiral alpha-silyl-substituted alpha-hydroxyacetic acids. Resolution by means of HPLC using a chiral stationary phase afforded an enantiomerically pure representative of this class of compounds, which was successfully applied as a chiral ligand in an asymmetric aldol-type reaction.

Biological Factors↗

PubMed2002

Low-dimensional compounds containing cyano groups. II. catena-Poly[[(2,2'-bipyridine-kappa(2)N:N')(dicyanamido-kappa N)copper(II)]-mu-dicyanamido-kappa(2)N:N'].

The crystal structure of the title compound, [Cu(C(2)N(3))(2)(C(10)H(8)N(2))](n), is formed by neutral zigzag chains of the [-NC-N-CN-Cu[(bpy)N(CN)(2)]-NC-N-CN-] type running along the c axis (bpy is 2,2'-bipyridine). The Cu atoms in the chains are pentacoordinated in the form of a distorted tetragonal pyramid, with a CuN(5) chromophore. The coordination sites are occupied by two N atoms of one bpy molecule in the basal plane [Cu-N 2.018 (4) and 2.025 (2) A] and by three terminal N atoms of two dicyanamide ligands. One of the dicyanamide ligands is coordinated in a monodentate fashion through a nitrile N atom in the basal plane [Cu-N 1.963 (4) A]. The second acts as an end-to-end bridging ligand to a neighbouring Cu atom and is coordinated by one nitrile N atom in the basal plane [Cu-N 2.001 (2) A], while the second nitrile N atom occupies the apical position [Cu-N 2.159 (2) A] and originates from the bridge connecting another Cu atom. The shortest intrachain Cu.Cu distance is 8.212 (1) A, as a consequence of the large bridging ligand, whereas the minimum interchain distance between Cu atoms is only 5.77 (7) A, because of the interdigitation of the chains.

Journal Article↗

PubMed2002

Low-dimensional compounds containing cyano groups. I. catena-Poly[dicyanoargentato(I)-kappaN]bis(4-methylpyridine-kappaN)copper(II)]-mu-dicyanoargentato(I)-kappa2N:N'].

The structure of the title compound, [Cu(C(6)H(7)N)(2)(Ag(CN)(2)(2)](n), is made up of neutral zigzag chains of [-NC-Ag-CN-Cu(4-Mepy)(2)(Ag(CN)(2))-NC-Ag-CN-] (4-Mepy is 4-methylpyridine). Neighbouring chains are linked by weak argentophilic interactions, with Ag.Ag distances of 3.2322 (12) A. The Cu atom, which lies on a twofold rotation axis, is pentacoordinated by one monodentate Ag(CN)(2)(-) anion [Cu-N 1.985 (3) A], the atoms of which lie on the same rotation axis, and by bridging dicyanoargentate anions [2 x Cu-N 2.0827 (19) A], with Ag atoms on inversion centres. The coordination polyhedron is completed by two 4-Mepy molecules [2 x Cu-N 2.038 (2) A], which occupy the axial positions of a distorted trigonal bipyramid.

Journal Article↗