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  • 1
    ISSN: 1530-0358
    Keywords: Endoanal ; Magnetic resonance imaging ; Vector volume ; Manometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: This study compared conventional water-perfused and vector volume anal manometry in female patients with neurogenic fecal incontinence and chronic anal fissure and in healthy female volunteers. We used endoanal magnetic resonance (MR) imaging to measure internal and external sphincter lengths and thicknesses and contrasted these with the manometric findings in the different anorectal conditions. METHODS: One hundred thirty-three female subjects were studied over an eight-month period, including 33 control volunteers, 83 patients with neurogenic fecal incontinence, and 17 patients with chronic anal fissure. Conventional manometry was contrasted with automated vector volume-derived parameters. Endoanal magnetic resonance images were obtained using a previously described internal coil with a 0.5 T Asset™ scanner measuring quadrantal internal sphincter thickness and averaged coronal internal and external sphincter lengths. RESULTS: There was a statistically significant relationship between parameters measured by conventional manometry and those variables derived from vector volume manometry at rest and squeeze. There was no difference in sectorial vector-derived pressures within any anorectal condition and no correlation between quadrantal internal sphincter thickness measurements and sectorial pressures at rest. Patients with chronic anal fissure and neurogenic fecal incontinence had constitutionally shorter superficial and subcutaneous external sphincters than healthy control subjects (P〈0.001). CONCLUSIONS: There is no association between manometric findings and morphologic sphincter measurement; however, the shorter distal external sphincter in patients with fissure might render the lower anal canal relatively unsupported after internal sphincterotomy in the female patient.
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  • 2
    ISSN: 1530-0358
    Keywords: Rectal cancer ; Transrectal ultrasonography ; Computerized tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: The preoperative assessment of rectal cancer wall invasion and regional lymph node metastasis is essential for the planning of optimal therapy. This study was done to determine the accuracy and clinical usefulness of transrectal ultrasonography, pelvic computed tomography, and magnetic resonance imaging in preoperative staging. METHODS: A total of 89 patients with rectal cancer were examined with transrectal ultrasonography (n=89), pelvic computed tomography (n=69), and magnetic resonance imaging with endorectal coil (n=73). The results obtained by these diagnostic modalities were compared with the histopathologic staging of specimens. RESULTS: In staging depth of invasion, the overall accuracy was 81.1 percent (72/89) by transrectal ultrasonography, 65.2 percent (45/69) by computed tomography, and 81 percent (59/73) by magnetic resonance imaging. Overstaging was 10 percent (9/89) by transrectal ultrasonography, 17.4 percent (12/69) by computed tomography, and 11 percent (8/73) by magnetic resonance imaging; and understaging was 8 of 89 (8.9 percent) by transrectal ultrasonography, 12 of 69 (17.4 percent) by computed tomography, and 6 of 73 (8 percent) by magnetic resonance imaging. In staging lymph node metastasis, the overall accuracy rate was 54 of 85 (63.5 percent) in transrectal ultrasonography, 39 of 69 (56.5 percent) in computed tomography, and 46 of 73 (63 percent) in magnetic resonance imaging. The sensitivity was 24 of 45 (53.3 percent) in transrectal ultrasonography, 14 of 25 (56 percent) in computed tomography, and 33 of 42 (78.5 percent) in magnetic resonance imaging; and specificity was 30 of 40 (75.0 percent) in transrectal ultrasonography, 25 of 44 (56.8 percent) in computed tomography, and 13 of 31 (41.9 percent) in magnetic resonance imaging. The accuracy in detection of positive lateral pelvic lymph nodes under magnetic resonance imaging (n=8) was 12.5 percent. The accuracy in detection of posterior vaginal wall invasion was 100 percent in transrectal ultrasonography (n=7) and 100 percent in magnetic resonance imaging (n=3), but 28.5 percent in computed tomography (n=7). CONCLUSIONS: Both transrectal ultrasonography and magnetic resonance imaging with endorectal coil exhibited similar accuracy and were superior to conventional computed tomography in preoperative assessment of depth of invasion and adjacent organ invasion. Because transrectal ultrasonography is a safer and more cost-effective modality than magnetic resonance imaging, transrectal ultrasonography is an appropriate method for preoperative staging of rectal cancer. Further efforts will be needed to provide a better staging of lymph node involvement.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Trauma und Berufskrankheit 1 (1999), S. S92 
    ISSN: 1436-6274
    Keywords: Schlüsselwörter Wachstumsalter ; MRI ; Beckenfraktur ; Wirbelsäulenfraktur ; Key words Childhood ; Magnetic resonance imaging ; Pelvic fracture ; Spinal injury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract According to the literature, from 1950 to 1995 the overall risk for children of sustaining a fracture of the spinal column or the pelvic ring doubled, the main reason being the increasing incidence of high-energy trauma caused by newly popular sporting activities such as skateboarding, inline skating and mountain biking. Nonetheless, even specialized pediatric level I trauma centers in Europe and the United States of America report an incidence of below 5% for severe spinal injuries and fractures of the pelvis. Although these specific injury patters are seen relatively infrequently, whenever present they are still highly indicative of high-velocity injury mechanisms, frequently revealing a combination of injuries – each of which would be serious in itself – involving the body cavities and the soft tissues of the trunk an extremities. In summary, spinal cord injuries and pelvic ring fractures are rare but can be serious: cervical and spinal cord injuries without radiological abnormality appear to be more frequent than in adults, and the availability of nuclear magnetic imaging technologies has helped in the diagnosis of unsuspected cord injury in children. In addition, retrospective analysis of purely nonoperative management of highly unstable C-type injuries of the spine and the pelvic ring reveal some unsatisfactory results, so that specifically for these injury morphologies the alternative of an operative strategy might be considered. The purpose of this presentation is to discuss various injury patterns in which an operative concept could be considered, particularly for a multiply injured child.
    Notes: Zusammenfassung Verletzungen des Rückenmarks und Sprengungen des knöchernen Beckenrings liegen im Kindesalter auch im Krankengut spezialisierter Zentren unter 5%. Besonders beachtenswert erscheint hierbei, daß Rückenmark- und besonders Halswirbelsäulenverletzungen v. a. beim Kind häufig keine ossäre Mitbeteiligung der Wirbelsäule zeigen und erst durch kernspintomographische Diagnostik erfaßt werden können. Desgleichen zeigt sich bei der retrospektiven Auswertung, daß ein pauschales, rein konservatives Management aller Verletzungstypen, d. h. v.a. der sog. C-Verletzungstypen an der Wirbelsäule und am Becken, z. T. unbefriedigende Behandlungsergebnisse zeigt und daher zunehmend bei bestimmten, im weiteren näher besprochenen Verletzungskonstellationen ein eher operatives Grundkonzept diskutiert wird. Neue Erkenntnisse zur Diagnostik und Therapie der Wirbelsäulen- und Beckenverletzung beim Kind liegen insofern vor, als 1. neuere epidemiologische Erhebungen heute eine präzisere, d. h. nicht nur empirisch gesicherte Unterscheidung der selten von eher regelmäßig anzutreffenden Verletzungstypen und Frakturmorphologien erlauben, 2. durch vergleichsweise „neue“ Sportarten wie „Scate-boarding“ und „Mountain-biking“ ganz generell eine statistisch belegte Zunahme von Hochrasanztraumen und komplexen Verletzungsmustern beim Kind beobachtet werden kann sowie 3. generell v.a. beim mehrfachverletzten Kind heute eine eher aggressivere Gangart, d. h. ein in bestimmten Einzelaspekten eher operatives Versorgungskonzept angestrebt wird. Gegenstand der vorliegenden Arbeit sind 1. eine Analyse der als besonders bedeutsam erkannten Verletzungsformen sowie 2. eine Darstellung der heute in Veränderung begriffenen Behandlungskonzepte v.a. beim mehrfachverletzten Kind.
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  • 4
    ISSN: 1436-2813
    Keywords: thyroid tumor ; apoptosis ; TUNEL ; MIB-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To clarify the growth mechanisms of thyroid tumors, we examined apoptotic cells in 61 thyroid tumors, consiting of 14 adenomas, 35 papillary carcinomas, 4 follicular carcinomas, and 8 undifferentiated carcinomas, using terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate digoxigenin-nick end labeling (TUNEL). The proliferative activity was also evaluated immunohistochemically using the monoclonal antibody to Ki-67 antigen (MIB-1) in the same tumors. The apoptotic index (AI) was expressed as a percentage of the TUNEL-positive cells in the tumor cells, and a proliferation index (PI), being the percentage of Ki-67 positive cells, was calculated for each tumor. The overall level of AI was very low in all histotypes of the thyroid tumors analyzed, the mean AI being 0.5±0.4 in adenoma, 0.4±0.3 in differentiated carcinoma, and 1.8±1.5 in undifferentiated carcinoma. The PI in the thyroid tumor subtypes was significantly lower in adenoma and differentiated carcinoma, at 0.5 ±0.7 and 1.1±0.7, respectively, than that in undifferentiated carcinoma at 14.5±3.7 (P〈0.05). There was no correlation between clinicopathological factors and AI or PI in differentiated thyroid carcinoma. Our findings suggest that apoptosis occurs infrequently in thyroid tumors, and that proliferative activity markedly differs according to the thyroid tumor subtypes. Moreover, the ratio between proliferating cells and apoptotic cells may reflect thyroid tumor progression.
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  • 5
    ISSN: 1436-2813
    Keywords: Key Words: thyroid tumor ; apoptosis ; TUNEL ; MIB-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: P 〈 0.05). There was no correlation between clinicopathological factors and AI or PI in differentiated thyroid carcinoma. Our findings suggest that apoptosis occurs infrequently in thyroid tumors, and that proliferative activity markedly differs according to the thyroid tumor subtypes. Moreover, the ratio between proliferating cells and apoptotic cells may reflect thyroid tumor progression.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 203-206 
    ISSN: 1572-8854
    Keywords: Manganese(III) ; Schiff base ; hydrogen bonding ; crystal structure ; Jahn-Teller distortion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The manganese complex, (Mn2(III)(salpa)2Cl2(H2O)2], has been prepared and its structure determined using x-ray crystallography. The dimer is a di-μ2-alkoxo complex which is a six-coordinate manganese dimer with unsupported alkoxide bridges and a rare example of a chloride- and water-containing manganese dimer. The complex crystallizes in the monoclinic space group P21/c with a = 9.315(5), b = 11.130(4), c = 11.637(5) Å, β = 104.33(3)°, V = 1169.0(9) Å3, and Z = 2. The structure comprises discrete binuclear clusters in which the metal atoms are bridged by two alkoxo oxygens of the salpa2− ligands. The Mn—O and Mn—N distances are in good agreement with those found for other manganese(III) Schiff base complexes. The Mn—Cl and Mn—O3 distances are 2.585(2) and 2.371(2) Å, respectively, and the Mn ··· Mn distance is 3.001(1) Å. In the crystal, there are two types of hydrogen bonding between the H2O molecule and the Cl atom with Cl ··· H(H2O) distance of 2.33(6) (intramolecule: −1 + x, y, −1 + z) and 2.68(6) Å (intermolecule: −1 + x, 0.5−y, −0.5 + z).
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 243-246 
    ISSN: 1572-8854
    Keywords: Thorium ; dimethoxyethane ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The molecular structure of ThBr4(DME)2 (DME = 1,2-dimethoxyethane), the first structurally characterized thorium complex containing a simple bidentate ether ligand, is described. The eight-coordinate complex presents a distorted dodecahedral geometry, with Th—Br and Th—O bond lengths in the ranges 2.8516(13)–2.8712(13) Å and 2.564(8)–2.620(8) Å, respectively. ThBr4(DME)2 is monoclinic, space group P21/n, a = 7.672(1), b = 14.581(1), c = 15.847(2) Å, β = 102.24(1)°, V = 1732.4(3) Å3, and Z = 4.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 295-298 
    ISSN: 1572-8854
    Keywords: Copper ; crystal structure ; synthesis ; Schiff base ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title complex Cu(C8H7O2N)2(OH2) crystallized in the orthorhombic space group, Pbca with unit cell parameters: a = 15.242(2), b = 11.782(4), c = 17.946(4) Å, and Z = 8. Two nitrogen atoms, two phenolic oxygen atoms of the ligand, and one water molecule are coordinated with copper to form a distorted tetragonal pyramidal polyhedron.
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  • 9
    ISSN: 1572-8854
    Keywords: Europium ; terbium ; betaine ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three dimeric lanthanide(III) complexes, [Eu2(bet)8(H2O)4](CIO4)6 (1), [Tb2(bet)8(H2O)4](ClO4)6 (2), and [Eu2(bet)4(H2O)8] Cl6·6H2O (3) (bet = Me3N+CH2COO−, trimethyl-aminoacetate), have been prepared and structurally characterized by X-ray crystallography. Complex 1 crystallizes in the monoclinic space group P21/c, with a = 11.7807(8), b = 27.757(5), c = 11.7980(8) Å, β = 99.500(4)°, V = 3805.1(8) Å3, and Z = 2. Complex 2 is isomorphous to complex 1, crystallizing in the monoclinic space group P21/c, with a = 11.7769(14), b = 27.725(3), c = 11.795(5) Å, β = 99.668(14)°, V = 3797(2) Å3, and Z = 2. Complex 3 crystallizes in the orthorhombic space group Pbca, with a = 12.5664(8), b = 17.8645(9), c = 22.2573(8) Å, V = 4996.6(4) Å3 and Z = 4. Both complexes 1 and 2 comprise quadruply carboxylate-O,O′-bridged [M2(bet)4]6+ dimeric cores (M = Eu, Tb), and each metal ion is further coordinated by two terminal aqua ligands and two monodentate bet carboxylates to form a distorted square-antiprismatic coordination geometry. Complex 3 also has a [Eu2(bet)4]6+ core, in which two bet ligands act in the η1:η1:μ2 bridging fashion, and the other two bet ligands in the less common η2:η1:μ2 bridging fashion, namely bridging-chelate mode. Each europium(III) ion in complex 3 is further coordinated by four water molecules to complete a monocapped square antiprism.
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  • 10
    ISSN: 1572-8854
    Keywords: crystal structure ; copper(II) complexes ; dinuclear complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A chemical Janus, binuclear copper(II) complexes, {[Cu(TPA)Cl][Cu(BPA)Cl]}(ClO4)2 (TPA = Tris(2-pyridylmethyl) amine, BPA = bis-(2-pyridylmethyl)amine) containing two different ligands has been synthesized and characterized by X-ray single crystal analysis. Crystal data: triclinic, space group P1$sm, a = 12.529(3), b = 12.655(3), c = 13.458(3) Å, α = 70.48(3), β = 67.40(3), γ = 75.81(3)°, D x = 1.648 mg m−3, and Z = 2. The molecular structure shows that the binuclear copper complex consists of two positive cation and two perchlorate anions. The positive cations moieties have different ligands. Cu(1) is coordinated by four nitrogen atoms from TPA and one chloride atom, forming a square-pyramidal geometry, whereas the coordinate number of Cu(2) is four, three of which are from BPA, one from chloride. There are two weak bonds between the Cl(2a) ion and the Cu(2) ion (2.844 Å) and the distance of Cu(2)=O(13) is 2.750(9) Å.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 513-521 
    ISSN: 1572-8854
    Keywords: nanotechnology ; molecular devices ; triptycene ; crown ether ; crystal structure ; thallium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The incorporation of 9,10-triptycene unit in a crown ether is examined from a structural perspective. Insertion of a triptycene group into 18-crown-6 stretches the crown into an ellipse, as seen in structures presented here of 9,10-triptyceno-22-crown-6 and its thallium complex. Symmetric addition of two triptycene groups into 18-crown-6 results in the sterically congested bis(9,10-triptyceno)-26-crown-6, whose crown cavity is filled with the π-clouds of two arene groups. The larger bis(9,10-triptyceno)-32-crown-8 is more sterically relaxed. The structures of these bis(triptyceno)crown ether molecules are the first with two triptycene groups simultaneously linked through their 9 and 10 positions, thereby forming a simple molecular gearing mechanism. The compound 9,10-triptyceno-22-crown-6 (1) crystallizes in the orthorhombic space group Pbca with a = 10.7962(7), b = 15.826(3), c = 31.147(5) Å, V = 5321.8(12) Å3, and Z = 8; its complex with TlNO3 (Tl-1) crystallizes in the monoclinic space group P21/c with a = 8.1884(14), b = 19.552(2), c = 20.575(4) Å, β = 97.062(8)°, V = 3269.2(9) Å3, and Z = 4; bis(9,10-triptyceno)-26-crown-6 (2) crystallizes in the triclinic space group P $$\bar 1$$ with a = 8.6488(11), b = 10.7718(12), c = 12.3324(12) Å, α = 111.58(1), β = 100.55(1), γ = 106.43(1)°, V = 970.3(5) Å3, and Z = 1; and bis(9,10-triptyceno)-32-crown-8 (3) crystallizes in the orthorhombic space group Pna21 with a = 20.186(3), b = 8.558(2), c = 25.623(2) Å, V = 4426.2(14) Å3, and Z = 4.
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 555-560 
    ISSN: 1572-8854
    Keywords: alkylammonium chloroantimonates(III) ; hydrogen bonds ; disorder ; lone electron pair ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of [(CH3)3NH]2Sb3Cl11 (space group P21/n; a = 10.374(2), b = 23.723(5), c = 11.884(2) Å, β = 113.46(3)°; V = 2682.9(9) Å3) consists of a structurally novel [Sb3Cl2− 11] anion and two crystallographically nonequivalent trimethylammonium cations. The anion is composed of three deformed octahedra in the asymmetric part of the unit cell. The octahedra are connected with each other by edges and corners forming a characteristic polyanionic layer. Trimethylammonium cations, one ordered and one disordered, are connected to the inorganic sublattice by N—H· · ·Cl hydrogen bonds.
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  • 13
    ISSN: 1572-8854
    Keywords: crystal structure ; complexes ; pteridine ; lumazine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single-crystal X-ray diffraction studies have been performed on the complex cis-diaqua-bis(1,3-dimethylpteridine-2,4(1H,3H)-dione-O4,N5) copper(II) perchlorate monohydrate, [Cu(DLM)2(H2O)2](ClO4)2 · H2O. This compound crystallizes in the orthorhombic system, P212121 space group, Z = 4 with a = 8.749(1) Å, b = 14.213(1) Å, c = 21.200(2) Å, and V = 2636.2(4) Å3. The metal ion is surrounded in octahedral geometry by two mutually quasi-perpendicular N5,O4-coordinated lumazine chelators with the O4 atoms trans and the N5 atoms cis. The polyhedron is completed by two cis-coordinated water molecules. The absolute configuration of the complex can be described, following Bailar's nomenclature, as the enantiomer Λ of the stereoisomer 4M. A three-dimensional hydrogen-bond network is defined by water molecules, perchlorate anions, and the O2 of the pteridine A.
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  • 14
    ISSN: 1572-8854
    Keywords: dodecanuclear heterobimetallic ; molybdenum-copper cluster ; cage ; μ6-S ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex (Ph4P)2[Mo2S2O2(S2)(S4)] reacts with CuBr to give the dodecanuclear heterobimetallic Mo—Cu—S cage cluster: (Ph4P)2[{Mo2Cu2O2S2(S2)2}3(μ6-S)] (1), which crystallizes in the triclinic space group P1¯, a = 14.445(5), b = 15.396(5), c = 18.858(5) Å, α = 103.12(3), β = 101.93(2), γ = 113.92(3)°, and V = 3517(2) Å3 for Z = 2. The anion 1 can be described as a cage with S2− at the center binding to six Cu atoms; the cage has two big windows each composed of a puckered Cu3S6 9-membered ring.
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  • 15
    ISSN: 1572-8854
    Keywords: copper(II) complexes ; 2,6-diacetylpyridine derivative ; open-chain ligand ; crystal structure ; trigonal-bipyramidal geometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound was obtained by a template synthesis from 2,6-diacetylpyridine, ethylhydrazinoacetate and CuCl2·2H2O (molar ratio 1:2:1, in methanol), and its structure has been determined by single-crystal X-ray diffraction: monoclinic space group P21/c, a = 13.906(5), b = 18.199(6), c = 16.641(6) Å, β = 107.18(3)°, and z = 4. The ligand was found to be tridentate in a trigonal-bipyramidal coordination geometry with two chloride ligands. There are two independent complex molecules, one of which is hydrogen bonded to the water of crystallization.
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 629-633 
    ISSN: 1572-8854
    Keywords: heterometallic polymeric cluster ; polythiometalate ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex (NH4)2 WS4 reacts with AgNO3 and La(NO3)3 · 6H2O in a mixture of DEF/DMF (DEF—N,N′-diethylformamide), to give a new heterometallic square-chain polythiometalate {[W4Ag5S16]2 · [La(DEF)2(DMF)6] · [La(DEF)4(DMF)4]}n (1). 1 crystallizes in the monoclinic space group P2/c, a = 19.5534(8), b = 16.9552(6), c = 22.3479(9) Å, β = 106.053(1)°, V = 7120.1(5) Å3, and Z = 2. The anion polymeric chain of 1 can be regarded as an octanuclear cyclic cluster of [W4Ag4S16]4− fragments linked through Ag+ ions. The polymeric chain is extended through the parallel edges of the square unit. The mean W—Ag distance is 2.963(16) Å. The La3+ cations are coordinated by different solvent molecules, the average La—O bond of these large trivalent cations is 2.47(1) Å.
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  • 17
    ISSN: 1572-8854
    Keywords: oxabicyclo[3.2.1]octadiene ; absolute configuration ; asymmetric synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound under investigation crystallizes in the noncentrosymmetric orthorhombic space group P212121 with a = 7.9358(11), b = 11.0532(13), c = 29.2425(43) Å, volume = 2565.0(6) Å3, and Z = 4. The C23H34O8Si molecule contains three chiral centers (one of which is of known configuration, based upon an (R)-pantolactone auxillary group). We have determined the absolute configuration of this species (via the anomalous dispersion of Si relative to C and O) and show that it is consistent with the known configuration of the (R)-pantolactone moiety.
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  • 18
    ISSN: 1572-8854
    Keywords: oxabicyclo[3.2.1]octadiene ; absolute configuration ; asymmetric synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound under investigation crystallizes in the noncentrosymmetric monoclinic space group P21 with a = 9.1798(23), b = 6.6606(18), c = 17.6591(41) Å, β = 94.342(20)° and Z = 2. The C20H30O6Si molecule contains three chiral centers (one of which is of known configuration, based upon an (R)-pantolactone auxiliary group). We have determined the absolute configuration of this species (via the anomalous dispersion of Si relative to C and O) and show that it is consistent with the known configuration of the (R)-pantolactone moiety
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  • 19
    ISSN: 1572-8854
    Keywords: 2,2′-biimidazole ; diester ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 1,1,′-Di(ethylpropionato)-2,2′-biimidazole, C16H22N4O4, crystallizes from ice-cold ethanol in the space group P $$\bar 1$$ , with a = 4.6742(9), b = 9.1119(13), c = 10.175(2) Å, α = 96.22(1), β = 96.29(2), γ = 97.53(1)°, and Z = 1. The molecule crystallizes with coplanar rings and the substituents assume a trans conformation with a center of inversion between the bridging carbon atoms.
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  • 20
    ISSN: 1572-8854
    Keywords: Hg coordination ; crystal structure ; organomercury derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the title compound, Hg[S2P(OPri)2]2, has been determined by single-crystal X-ray diffraction. The compound crystallizes in the centrosymmetric P21/c space group with a = 11.800(1), b = 8.925(2), c = 22.167(2) Å, β = 94.988(7)°, and Z = 4. The same compound has been previously reported but the structure is described there in the space group C2/c. In both cases, one phosphorodithioate moiety acts as a chelating group and the other as a bridging group between neighboring mercury atoms (related to one another by the twofold screw axis), giving rise to an infinite polymer along the direction of the b axis. It turns out that in spite of the difference in space group symmetry, the structures are remarkable similar in that they are formed from infinite polymers of similar geometry. The coordination around the Hg ion shows, however, significant differences, mainly for the bridging Hg—S(4) bond length, which is 0.16 Å smaller than that previously reported.
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  • 21
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    Journal of chemical crystallography 29 (1999), S. 329-333 
    ISSN: 1572-8854
    Keywords: Carbene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Base-promoted reaction of 11-methylenepentacyclo[5.4.0.02,6.03,10.05, 9]undecan-8-one (5) with diethyl diazomethylphosphonate when performed in the presence of excess cyclohexene, resulted in the formation of the corresponding cycloalkylidenecarbene, 6, which subsequently was trapped in situ to afford 8-methylene-11-(7′-bicyclo[4.1.0]heptylidene)pentacyclo-[5.4.0.02, 6.03, 10.05, 9]undecane (7, obtained in 44% yield as a mixture of exo, endo isomers). Subsequent reaction of 7 with dichlorocarbene (generated under phase transfer catalytic conditions) produced the corresponding mono- and di-:CCl2 adducts [i.e., 8 (64% yield) and 9 (5% yield), respectively]. The structure of 9 was established unequivocally via application of single crystal X-ray analysis: Triclinic, P1¯, a = 6.276(2), b = 8.700(2), c = 18.550(3) Å, α = 76.52(3), β = 87.59(3), γ = 70.88(4)° Z = 2; D calc 1.486 g cm−3.
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  • 22
    ISSN: 1572-8854
    Keywords: crystal structure ; manganese complex ; disubsituted oxamide ; addition compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structure of the addition compound, Mn(phen)3(PMoxdH2)(ClO4)2 was established by X-ray crystallography, where PMoxdH2 is N,N′-bi(2-pyridylmethyl)-oxamide. Six nitrogen atoms of the three 1,10-phenanthroline bind to the manganese ion and the oxygen atom of PMoxdH2 is uncoordinated. The addition compound crystallizes in the monoclinic space group C2/c, with lattice parameters a = 23.780(6), b = 11.948(5), c = 18.466(6) Å, β = 117.38(3)°, V = 4659(3) Å3, and Z = 4.
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  • 23
    ISSN: 1572-8854
    Keywords: pyrazolyl derivative ; substituted cyclopentane ; substituted cyclohexane ; crystal structure ; bidentate ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The species 1,1-di(pyrazol-1-yl)cyclohexane, C12H16N4, crystallizes in the monoclinic space group P21/c with a = 8.340(2), b = 14.281(5), c = 10.153(3) Å, β = 106.86(2)°, and Z = 4. The cyclohexane moiety has the chair conformation. The congener, 1,1-di(pyrazol-1-yl)cyclopentane, C11H14N4, while not isomorphous, also crystallizes in space group P21/c with a = 14.350(2), b = 6.776(1), c = 11.043(2) Å, β = 100.68(1)°, and Z = 4. The cyclopentane ring has a conformation in which four carbon atoms are essentially coplanar, while the fifth (that with the two pyrazolyl substituents) lies 0.63 Å from this plane, resulting in a bend of 41.3° across the C(2)···C(5) vector. The hydrogen atoms in each structure were located directly and their coordinates refined.
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  • 24
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    Journal of chemical crystallography 29 (1999), S. 719-723 
    ISSN: 1572-8854
    Keywords: synthesis ; crystal structure ; independent molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The x-ray crystal structure of 4,5-(cis-cyclohexylenedithio)-1,3-dithiole-2-one has been determined. Yellow block shaped crystals of C9H10OS4 crystallize in the space group P $${\bar 1}$$ with cell dimensions a = 8.872(4), b = 9.330(8), c = 14.333(12) Å, α = 95.23(7), β = 91.09(5), γ = 107.60(5)°, V = 1124.8(14) Å3, and Z = 4. This compound has two S---S contacts [3.574, 3.610 Å] shorter than 3.70 Å and the usual disordered ethylene moiety [C(3)—C(8)] of the six-membered ring is fixed by the cis-cyclohexylene subsitituent. This means that it may be a new precursor for conducting and strong near-IR absorbing nickel-dithiolenes. Also, it provides the first example of polymorphism of the dmit derivatives and contains two independent molecules I and II in the asymmetric unit.
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  • 25
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    Journal of chemical crystallography 29 (1999), S. 725-727 
    ISSN: 1572-8854
    Keywords: 2-thiouracil derivatives ; crystal structure ; S-methyl-thiouracil ; hydrogen bonding ; structural methylation and metallation effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-S-Methylthiouracil crystallizes in the triclinic space group P $${\bar 1}$$ with unit cell dimensions a = 5.508(4), b = 7.175(3), c = 8.522(2) Å, α = 80.83(2), β = 80.43(3), γ = 76.86(3)°, and Z = 2. The molecule exists in the crystal in the lactam form and is essentially planar. The molecular packing consists of molecules linked in centrosymmetric hydrogen-bonded pairs. The effects of methylation and subsequent metallation on the 2-thiouracil structure are discussed.
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  • 26
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    Journal of chemical crystallography 29 (1999), S. 797-802 
    ISSN: 1572-8854
    Keywords: synthesis ; crystal structure ; Cu(I) complex ; μ-oxo-bis(2,9-dimethyl-1,10-phenanthroline) ; luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis and crystal structure of a luminescent dinuclear Cu(I) complex as the BF− 4 salt from toluene and methanol containing triphenylphosphine and μ-oxo-bis(2,9-dimethyl-1,10-phenanthroline) is described. The coordination geometry about the Cu(I) center is distorted tetrahedral. An unusual feature of the structure is a pseudo-inversion center located near the oxygen atom at approximately 0.51, 0.26, 0.25, such that all of the atoms except for the oxygen are related by a pseudo-inversion center to another atom in the same molecule, as well as by crystallographic inversion to the other molecule in the unit cell. The complex displays luminescence from an MLCT band in fluid solution and emission from both a metal-centered charge-transfer and intraligand (phenanthroline) state at 77K in a chloroform snow. Crystal data: triclinic, P $$\bar 1$$ , a = 15.163(2), b = 16.985(2), c = 18.731(2) Å, α = 106.458(9), β = 91.416(8), γ = 102.557(9)°, V = 4496(1) Å3, and Z = 2.
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  • 27
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    Journal of chemical crystallography 29 (1999), S. 729-733 
    ISSN: 1572-8854
    Keywords: crystal structure ; yttrium complexes ; isothiocyanate complexes ; octahedral coordination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The structural analysis of [(n-C4H9)4N]3[Y(NCS)6] (I) using single-crystal diffraction data and full-matrix least squares refinement has been carried out. The hexaisothiocyanate complex crystallizes in the centrosymmetric triclinic space group P $${\bar 1}$$ (No. 2) with unit cell constants of a = 12.431(1), b = 12.866(1), c = 22.750(2) Å, α = 90.78(1), β = 92.05(1), γ = 96.67(1)°, and Z = 2. The molecular unit consists of three separate cationic tetra-n-butylammonium groups and an independent hexakisisothiocyanatoyttrate anionic group in which the six thiocyanate ligands are octahedrally coordinated through the N atom to the Y central ion. Selected bond distances and angles are presented as well as the synthesis and peripheral studies of (I).
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  • 28
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    Journal of chemical crystallography 29 (1999), S. 793-796 
    ISSN: 1572-8854
    Keywords: copper complex ; crystal structure ; dibenzoylmethane complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Bis(dibenzoylmethane)copper Cu(dbm)2 has been synthesized and its structure determined by x-ray diffraction. It crystallizes in the monoclinic system, space group C2/c, with a = 25.936(3), b = 5.9806(8), c = 16.4908(16) Å, β = 114.998(8)°, Z = 4, and V = 2318.3(4) Å3. The Cu atom is located at a symmetry center and surrounded by four O atoms from two dbm molecules to form a plane square coordination environment. On the a–c plane the molecules are orderly arranged to result in a layered structure, and parallel to crystallographic b-axis they form a molecular column due to the effect of aromatic stacking.
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  • 29
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    Journal of chemical crystallography 29 (1999), S. 809-812 
    ISSN: 1572-8854
    Keywords: tungsten(II) ; dibromo ; carbonyl ; diphenylcyclohexylphosphine ; but-2-yne ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [WBr2(Co)(PPh2Cy)2(η2-MeC2Me)]·CH2Cl2 (Cy = cyclohexyl) crystallizes in the monoclinic space group, P21/n, with a = 10.606(12), b = 23.11(3), c = 18.19(2) Å, β = 106.070(10) Dcalc = 1.610g cm−3 for Z = 4. The tungsten coordination geometry can best be considered as a distorted octahedron, with the but-2-yne ligand occupying one coordination site, which has a trans-Br(2) group. The equatorial plane is made up of trans-PPh2Cy groups, with the bromo and carbonyl ligands occupying the other two sites.
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  • 30
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    Journal of chemical crystallography 29 (1999), S. 837-839 
    ISSN: 1572-8854
    Keywords: acyclonucleoside analog ; 6-(phenyl selenyl) uracil derivative ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound, 1-(ethoxymethyl)-6-(phenylselenyl)-5-ethyl uracil, crystallizes in the monoclinic space group P21/n with unit cell parameters a = 5.304(1), b = 21.261(4), c = 13.996(4) Å, β = 94.30(2)°, and Z = 4. The acyclic chain C1′, O4′, C4′, C5′ is in fully extended form and nearly perpendicular to the uracil base. The molecules are held together by van der Waal's forces.
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  • 31
    ISSN: 1572-8854
    Keywords: mercury halides ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The synthesis, characterization and single crystal X-ray structure of three compounds of general formula HgI2R (R = phen[1], dmph [2] and bpy[3]) are presented. The crystal data for the three compounds are: [1], triclinic, space group P $$\bar 1$$ (#2) a = 7.902(2), b = 9.479(2), c = 10.002(2) Å, α = 91.45(2), β = 111.34(2), γ = 100.82(2)° [2]: monoclinic, space group C2/c (#15) a = 15.670(3), b = 11.640(2), c = 9.730(2) Å, β = 114.57(3)° [3]: triclinic, space group P1¯ (#2) a = 9.472(1), b = 9.507(1), c = 9.023(1) Å, α = 98.46(1), β = 102.89(1), γ = 119.62(1)°. Compounds [1] and [2] are monomers, with highly distorted tetrahedral environments around Hg. In [3], instead, there is a significant intermolecular I···Hg interaction leading to the formation of softly bound dimers linking two pentacoordinated cations. The structure is compared with related ones in the literature.
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  • 32
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    Journal of chemical crystallography 29 (1999), S. 907-911 
    ISSN: 1572-8854
    Keywords: tungsten(II) ; Iodo ; carbonyl ; cis-bis(diphenylphosphino)ethene ; but-2-yne ; cationic ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex [WI(CO)(cis-dppen)(η2-MeC2Me)2]I·CH2Cl2(1) is prepared as a by-product from the reaction of equimolar quantities of [WI2(CO)(NCMe)(η2-MeC2Me)2] and cisdppen {dppen = bis(diphenylphosphino)ethene}. Complex 1, [WI(CO)(cis-dppen)(η2-MeC2Me)2]I·CH2Cl2 crystallizes in the triclinic space group $${\text{P}}\bar 1$$ with a = 11.189(13), b = 12.331(14), c = 15.395(17) Å, α = 83.61(1), β = 86.06(1), γ = 64.48(1)°, U = 1904 Å3, and Z = 2. The metal environment in the cation can best be considered as a distorted octahedron with the two but-2-yne groups taking up individual sites trans to phosphorus atoms of the dppen ligand. The coordination sphere is completed by mutually trans-carbonyl and iodide groups.
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  • 33
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    Journal of chemical crystallography 29 (1999), S. 955-959 
    ISSN: 1572-8854
    Keywords: crystal structure ; intramolecular hydrogen bond ; 4-(1,4-dimethoxy-2-naphthyl)-4-hydroxycyclohexanone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Intramolecular hydrogen bonding in the solid state is reported for the title compound and its ethylene ketal. The title compound crystallizes in the triclinic space group, $$P\bar 1$$ with a = 9.590(3), b = 9.620(3), c = 9.844(2) Å, α = 97.67(2), β = 105.25(2), γ = 115.47(2), and Z = 2. The ethylene ketal crystallizes in the monoclinic space group, P21/c, with a = 7.230(2), b = 22.639(3), c = 10.839(2) Å, β = 101.47(2), and Z = 4. The intramolecular hydrogen bond length of 1.79 Å is the same for the ketone and ketal, but the O—H---O valence angle is 144° for the ketone and 165° for the ketal.
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  • 34
    ISSN: 1572-8854
    Keywords: neotame ; crystal structure ; methanol solvate ; thermal analysis ; powder X-ray diffractometry ; 13C solid-state nuclear magnetic resonance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the methanol solvate (empirical formula: 2C20H30N2O5·3CH3OH) of a new dipeptide sweetener, neotame (N-(3,3-dimethylbutyl)-L-α-aspartyl-L-phenylalanine 1-methyl ester), has been determined. Crystal data: a = 9.8989(1), b = 18.1331(1), c = 27.5725(1) Å, orthorhombic, space group P212121, with Z = 4. Each unit cell includes 8 neotame and 12 methanol molecules. Disorder exists in one neotame molecule and one methanol molecule. The crystals were characterized by the following techniques: hot-stage microscopy (HSM), Karl-Fischer titrimetry (KFT), powder X-ray diffractometry (PXRD), differential scanning calorimetry (DSC), thermogravimetry (TGA), 13C solid-state nuclear magnetic resonance (SSNMR) spectroscopy. Under HSM at a heating rate of 10°C/min in silicone oil, the sample melts at 64–84°C and liberates bubbles at 71–86°C. DSC in open pans shows two overlapping endotherms at 56 and 71°C, probably due to melting and desolvation, respectively. TGA in open pans shows 5.9% weight loss due to desolvation below 70°C. Under house vacuum (23 mm Hg) over phosphorus pentoxide at 23°C, the methanol solvate produces pure amorphous anhydrate, which converts to crystalline neotame monohydrate in the presence of moisture.
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  • 35
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    Journal of chemical crystallography 29 (1999), S. 977-982 
    ISSN: 1572-8854
    Keywords: cyano allyl radical ; thermal arrangement ; crystal structure ; isomer ; NMR, MM2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation, separation, crystal structure and 1H NMR spectra are reported for the two geometrical isomers of 1,1′-bi-3-cyanocyclohex-2-enylidene. The E-isomer crystallized as thin plates in the monoclinic space group P21/n with a = 5.3980(5), b = 7.0757(7), c = 15.300(2) Å, β = 94.571(2)°, and Z = 2. The structure has symmetry C2h. The Z-isomer crystallized as needles in the triclinic space group P1¯ with a = 7.0790(6), b = 11.3155(9),c = 15.386(1) Å, α = 104.943° β = 90.164(2)°, γ = 99.494(2)°, and Z = 4. The compound crystallized with two molecules per asymmetric unit. In C6D6, 1H NMR signals of the 2-vinyl protons appear almost identical. However, in a mixture of C6D6 and pyridine-d 5, the 2-vinyl protons can be distinguished. The structures compare favorably with MM2 calculations.
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  • 36
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    Journal of chemical crystallography 29 (1999), S. 1009-1013 
    ISSN: 1572-8854
    Keywords: crystal structure ; nickel complex ; xanthosine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The complex [Ni(XsH−1)2(H2O)4]·6H2O (XsH−1: xanthosinate) was isolated from the reaction of nickel carbonate with xanthosine in aqueous solution. The octahedral coordination is supported by the reflectance measurements. Single-crystal X-ray diffraction studies show that the crystals belong to the triclinic P1 space group, with a = 7.152(1), b = 8.830(1),c = 13.783(1) Å, α = 82.024(1)°, β = 86.155(1)°, γ = 70.900(1)°, and D = 1.643 mg/m3, forZ = 1. Nickel is six coordinate with four water molecules, and two N7 atoms from xanthosinato ligands. A complicated hydrogen-bonding network is present, all possible donors taking part in it.
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  • 37
    ISSN: 1572-8854
    Keywords: manganese ; pyridine-2-thiolate ; bis(diphenylphosphino)methane ; carbonyl ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The dimeric complex [Mn2(μ-pyS)2(CO)6] (1) reacted with 2 M equivalents of both PPh3 and PHPh2 to give the respective monomeric phosphine complexes [Mn(pyS)(L)(CO)3][L = PPh3 (2) and PHPh2 (3)]; with 4 M equivalents of dppm, it yielded the complex [Mn(pyS)(η1-dppm)2(CO)2](4). An X-ray structure determination of 4 shows that it crystallizes in the monoclinic space group P21/n with a = 11.027(3), b = 24.984(7), c = 18.379(5) Å, β = 99.870(8)°, V = 4988(2) Å3, and Z = 4. The complex has an octahedral geometry with the chelating pyS ligand and two CO groups occupying the equatorial sites and the two monodentate dppm ligands lying in the trans positions.
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  • 38
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    Journal of chemical crystallography 29 (1999), S. 1037-1041 
    ISSN: 1572-8854
    Keywords: crystal structure ; imidazolidine ; triazene ; bis-triazene ; methoxy substituent ; π-π stacking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine (1) has been determined by single crystal X-ray diffraction analysis. This novel bis-triazene assumes a close-to planar structure with the aryltriazene moieties aligned in diametrically opposed directions, unlike many other previously reported bis-triazenes, which assume a folded structure. The structure of 1 is compared with the closely related, non-cyclic bis-triazene analogue (2), and also compared with the structure of the simple mono-triazene (3). Crystal data: 1 C17H20N6O2, monoclinic, space group C2/c, a = 34.948(3), b = 5.925(5), c = 8.1225(6) Å, β = 100.8420(10)°, and V = 1652.0(2) Å3, for Z = 4.
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  • 39
    ISSN: 1572-8854
    Keywords: crystal structure ; tritylaziridine ; acrylate ; spectroscopic features
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 2-{(R)-1-Hydroxy-1-[(2S)-1-tritylaziridin-2-y1] methy1}acrylate is described. Crystal data: C26H25NO3, orthorhombic, space group P212121, a = 9.6954(5), b = 13.1458(5), c = 16.7885(7) Å, V = 2139.8(2) Å3, Z = 4. The (R,S) diastereomer shows an intramolecular hydrogen bonding N···H—O under formation of a five-membered ring with N···O distance of 2.664 Å. IR, 1H NMR and 13C NMR data are discussed. The 1H NMR of the (R,S) diastereomer shows a singlet- whereas the (S,S) diastereomer exhibits a doublet-pattern for the hydroxyl proton.
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  • 40
    ISSN: 1572-8854
    Keywords: absolute configuration ; asymmetric synthesis ; azabicyclo[3.2.1]octadiene ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallized in space group P21 with a = 12.647(8), b = 14.542(4), c = 17.077(16) Å, β = 97.51(6)°, and D calc = 1.143 mg/m3 for Z = 4. There are two chemically-equivalent C27H41NO8Si molecules in the crystallographic asymmetric unit. Each contains three chiral centers, one of known absolute configuration based upon the (R)-pantolactone,—CH*—CMe2—CH2—O—CO—, moiety. The structural study was greatly complicated by disorder of an —OSiMe2(t-Bu) group in one molecule.
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  • 41
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    Journal of chemical crystallography 29 (1999), S. 1081-1084 
    ISSN: 1572-8854
    Keywords: cobalt(II) ; bipyridine ; maleato ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Preparation of the mononuclear cobalt(II) complex, [Co(bipy)(maleato) (H2O)3]·H2O (1) where bipy = 2,2′-bipyridine, were accomplished by reaction of an aqueous solution containing sodium maleate and an ethanolic solution of Co(NO3)2·6H2O and bipy. The crystal structure of complex (1) was determined by X-ray crystallography. The complex crystallizes in the monoclinic space group P21/n with a = 9.477(3), b = 7.660(2), c =23.526 (3) Å, β = 97.64(2)°, V = 1692.6(6) Å3, and Z = 4. The structure consists of discrete mononuclear cobalt molecules. The cobalt atom is six-coordinate and presents a slightly distorted octahedral geometry, which consists of the two imine N atoms of bipy, a terminal carboxylate O atom from maleato ligand, and a water O atom in the basal plane with Co—N bond distances of 2.116(2) and 2.124(3) Å and Co—O distances of 2.075(2) and 2.088(2) Å, respectively. The relatively shorter Co—O distances are due to the trans effect of the bipy ligand. The octahedral coordination is completed the other two water molecules. The coordinate and the lattice water molecules were identified by TG study.
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  • 42
    ISSN: 1572-8854
    Keywords: Rubidium nitroprusside monohydrate ; crystal structure ; properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of rubidium nitroprusside monohydrate, Rb2[Fe(CN)5NO] · H2O, has been determined from X-ray diffraction data and refined using direct and Fourier methods to R = 0.066 and Rw = 0.075, employing 1894 independent reflections with I 〉 3 (I). The substance crystallizes in the monoclinic space group C2/c (C 6 2h), with a = 13.987(2), b = 10.241(1), c = 18.151(1) Å, β = 110.94°, and Z = 8. Anions are located at C 1 sites, one per asymmetric unit, and are slightly distorted octahedra. TGA, DTA, FTIR, and FTIR Raman results were interpreted on the basis of the formula of the compound, its crystal structure, and the behavior of other nitroprussides.
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  • 43
    ISSN: 1572-8854
    Keywords: crystal structure ; methyl propiolate ; sulfenic acid ; vinyl sulfoxide ; leinamycin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Evidence for the formation of unstable sulfenic acids (RSOH) as reaction intermediates is commonly provided by trapping these compounds with methyl propiolate. The crystal structure of a vinyl sulfoxide derived from the trapping of a sulfenic acid with methyl propiolate is reported here. The title compound C12H12O5S crystallized in the triclinic space group,P1¯ with unit cell parameters: a = 6.1600(4), b = 9.7286(7), c = 11.3698(8) Å, α = 112.024(1), β = 94.662(1), γ = 95.429(1)°, and Z = 2.
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  • 44
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    Journal of chemical crystallography 29 (1999), S. 1137-1139 
    ISSN: 1572-8854
    Keywords: acyclic nucleoside analog ; acyclovir ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound 9[1-(2-hydroxy ethoxy)-3-hydroxy propyl] guanine crystalizes in the tetragonal system, space group P41212 with a = 11.106 (1), c = 20.558 (2) Å, and Z = 8. The acyclic chain C1′¯O1′¯C4′¯C5′¯O5′ is in the extended configuration and the glycosidic torsion angle (C4¯N9¯C1′¯O1′) is 125.1 (8)°. The molecules are held together by Van der Waal's forces.
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  • 45
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    Journal of chemical crystallography 29 (1999), S. 1205-1210 
    ISSN: 1572-8854
    Keywords: organic sulfate ; crystal structure ; DTA/TG/DSC ; vibrational spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract [1-(2-ammoniumethyl) piperazinium] sulfate denoted PIPS has a monoclinic unit cell. The parameters are: a = 6.6521(3), b = 7.8756(5), c = 19.197(1) Å, β = 94.43(1)° and the space group is P21/n. The preparation, thermal analysis, and IR spectrometric investigation are described. The PIPS structure exhibits a complex three-dimensional network of H-bonds connecting all its components.
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  • 46
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    Journal of chemical crystallography 29 (1999), S. 1265-1269 
    ISSN: 1572-8854
    Keywords: crystal structure ; corticosteroid ; de-oxy corticosterone-21-hemisuccinate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Synthetic glucocorticoid de-oxy corticosterone-21-hemisuccinate crystallizes in the monoclinic space group C2, with a = 21.896(2), b = 7.596(3) and c = 14.291(3) Å, Z = 4. Ring A is a distorted half chair, ring B and C are in the chair configuration and ring D is in the 14α-half chair configuration. The ring junctions B/C and C/D are both trans. The molecule as a whole is slightly convex towards the β-side, with an angle of 18.4(2)° between the C(10)--C(19) and C(13)--C(18) vectors. In addition to packing and stacking interaction, intermolecular hydrogen bonding plays an important role in structural association. The X-ray structure determination of the title compound was undertaken to study its high binding affinity to serum protein like globulin.
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  • 47
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    Journal of chemical crystallography 29 (1999), S. 1291-1293 
    ISSN: 1572-8854
    Keywords: crystal structure ; pyrazolo[3,4-d]pyrimidine ; fungicidal activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 1-phenyl-3-methylthio-4-imino-5-allyl-pyrazolo[3,4-d]pyrimidine, C15H15N5S, has been synthesized and characterized by x-ray diffraction: orthorhombic, space group Pbca, with a = 17.3480(9), b = 8.5022(5), c = 19.8132(11) Å. Z = 8, V = 2922.4(3) Å3. The compound shows a fully delocalized pyrazolo[3,4-d]pyrimidine system with a sp2 hybridization of the N(4) atom.
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  • 48
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    Journal of chemical crystallography 29 (1999), S. 199-201 
    ISSN: 1572-8854
    Keywords: Manganese (II) ; phenanthroline ; polymeric complex ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new polymeric manganese(II) complex, [Mn(II)(phen)(ClCH2COO)2]n, was obtained from the reaction of Mn(ClCH2COO)2 with phen and its structure was determined by x-ray crystallography. The complex crystallizes in the monoclinic system, space group C2/c with a = 19.706(4), b = 11.381(3), c = 7.482(3) Å, β = 94.01(3)°, V = 1674.0(8) Å3, and Z = 4. The structure consists of an infinite chain. The manganese atom is located on a twofold axis and presents a distorted octahedral coordination sphere, which consists of the two N atoms of a phen ligand (Mn—N = 2.304(2) Å) and four carboxylato ligands. The Mn···Mn distance within the chain is 4.53 Å, and the carboxylato bridges present a syn-anti conformation.
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  • 49
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    Journal of chemical crystallography 29 (1999), S. 1255-1259 
    ISSN: 1572-8854
    Keywords: crown ether ; crystal structure ; lariat ; sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A dibenzo-14-crown-4 ether with a novel monooxyacetone sidearm is prepared and its structure with sodium perrhenate is determined. The structure crystallizes in P21/c with cell dimensions: a = 8.107(2) Å, b = 28.138(3) Å, c = 10.293(2) Å, and β = 104.173(9)°; giving a volume of 2276.6(7) Å3. This structure is compared to other sodium complexes of dibenzo-14-crown-4 lariat ethers and is found to be the only one with intramolecular bonding between the sidearm and the cation. Possible reasons for this observation are discussed.
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  • 50
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    Journal of chemical crystallography 29 (1999), S. 1271-1275 
    ISSN: 1572-8854
    Keywords: crystal structure ; pregnen ; progestin ; 4-pregnen-21-ol-3,20-dione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Synthetic steroid de-oxy corticosterone (4-pregnen-21-ol-3,20-dione) crystallizes in the monoclinic space group P21, with a = 11.706(2); b = 11.171(3), c = 13.966(3) Å, and β = 100.94(2)°, Z = 4. Ring A tends to acquire the conformation of a half-boat, rings B and C are in the chair configuration, and ring D is a 13β, 14α-half-chair. The ring junctions B/C and C/D are both trans, whereas the ring junction A/B is quasi-trans. The molecule as a whole is slightly convex toward the β-side, with an angle of 16.01(0.36)° between the C10--C19 and C13--C18 vectors. Molecular packing and stacking interactions play the major role in structural association. Cohesion of the crystal is due to van der Waals interactions.
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  • 51
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    Journal of chemical crystallography 29 (1999), S. 565-569 
    ISSN: 1572-8854
    Keywords: orotic acid complex ; crystal structure ; copper(II) complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The compound [(C5H2N2O4)Cu(H2O)2]n has been synthesized and its structure determined at room temperature. The primary coordination sphere at the Cu ion is square planar with the orotate dianion coordinating at the metal through heterocyclic nitrogen atom and adjacent oxygen of the carboxylate group, the remaining coordination sites are occupied by two water molecules. The orotate dianion is tricoordinated to one copper via N1 and one oxygen of the carboxylato group and to another copper atom via the other oxygen of the carboxylato group. The coordination at copper is extended to five by the other oxygen of the carboxylate group of another orotate molecule. Thus, the molecules are associated to form chains, the carboxylato group acting as a bridge between the metal ions, the orotato-group being tridentate. The title compound crystallizes in the monoclinic space group. P21/n1 with a = 9.515(5), b = 6.925(2), c = 11.861(6) Å, β = 95.285(9)°, D calc = 2.17 g cm−3, and z = 4.
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  • 52
    ISSN: 1572-8854
    Keywords: pseudo-square pyramidal Cu(II) complex ; trans-4-styrylpyridine ; crystal structure ; IR, electronic, and EPR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Single crystals of the title Cu(II) complex, [Cu(stpy)4(ONO2)(ONO2)′] [stpy = trans-4-styryl-pyridine] have been prepared and characterized by elemental and thermal analyses, IR, electronic and EPR spectral measurements, and X-ray crystal structure determination. The complex crystallizes in the monoclinic space group P21/c with unit-cell parameters, a = 12.985(2), b = 22.865(8), c = 17.024(10) Å, β = 112.29(3)°, and Z = 4. The structure consists of discrete monomeric units of [Cu(stpy)4(ONO2)(ONO2)′]. The equatorial positions of the Cu(II) polyhedron are occupied by nitrogen atoms of the four stpy ligands and the axial positions by the oxygens of two unidentate nitrate anions. One of these oxygens is at rather longer distance [2.609(3) Å] and may be considered to be semicoordinated. If this semibond is ignored, the coordination geometry lies closer to an idealized square pyramid than to the trigonal bipyramid geometry. IR spectra reveal nitrogen coordination from stpy and asymmetry in the monodentate oxygen binding of the two nitrate ligands. The optical reflectance band at 600 nm suggests pseudo-square-based pyramidal geometry around Cu(II). Well-resolved Cu(II) hyperfine features in the EPR spectra reveal the absence of exchange interactions between adjacent copper centers. Optical and EPR spectra of a methanolic solution of the complex indicate solvent interactions. Thermogravimetric analysis shows the complex to be stable up to 175°C.
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  • 53
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    Journal of chemical crystallography 29 (1999), S. 475-480 
    ISSN: 1572-8854
    Keywords: crystal structure ; ab initio calculations ; conjugation ; phosphabutadienes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal and molecular structure of 1-phenyl-1-dimethylamino-4,4-bis(trimethylsilyl)-2-aza-3λ3-phosphabutadiene-1,3, Me2N(Ph)C=N—P=C(SiMe3)2 (1), has been determined. Crystal data: triclinic, P1¯, a = 8.975(4), b = 10.001(5), c = 12.440(6) Å, α = 79.04(4), β = 77.98(4), γ = 73.07(4)°, V = 1034.7 Å3, Z = 2, and D c = 1.08 g cm−3. The main geometrical parameters of 1 as well as ab initio (HF/6-31+G**) calculations of the model systems show no clear evidence of high efficiency of the π(C=N)—π (P=C) conjugation.
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  • 54
    ISSN: 1572-8854
    Keywords: contrast agents ; crystal structure ; ortho ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 1-(4-Bromobenzyl)-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane, C13H15BrO3, has been synthesized from 4-bromophenylacetic acid chloride via the oxetan ester (3-methyl-3-oxetanyl)methyl-2-(4-bromophenyl)acetate. The crystal structure of the title compound has been determined at low temperature (120 K), by X-ray diffraction methods. This compound crystallizes in the monoclinic space group P21/n (No. 14), Z = 4, with lattice parametersa = 6.019(5), b = 20.990(5), c = 9.915(2) Å, and β = 101.29(1)°.
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  • 55
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    Journal of chemical crystallography 29 (1999), S. 561-564 
    ISSN: 1572-8854
    Keywords: crystal structure ; Raman spectrum ; silver azide ; azide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Silver nitrate reacts with sodium azide to give white powdery silver azide, which can be crystallized in aqueous ammonia. The compound belongs to orthorhombic space group Ibam with a = 5.600(1), b = 5.980(6), c = 5.998(1) Å, and Z = 4. The layer-type structure is constructed from edge-sharing regular rectangles, each composed of silver atoms at its vertices with an enclosed azide anion in a tilted orientation. The linear and asymmetrical structure of the azide anion in crystalline silver azide has been confirmed by its Raman spectrum.
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  • 56
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    Journal of chemical crystallography 29 (1999), S. 845-848 
    ISSN: 1572-8854
    Keywords: crystal structure ; centrosymmetric ; aminoadamantane derivative ; antiviral ; dispiro compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Adamantan-1-ammonium 1-adamantanecarboxylate, C21H33NO2 (I) is a novel dispiro-type compound. Aminoadamantane derivatives, in which the spiro carbon atoms are part of heterocyclic rings, are of potential interest as biological active substances and antiviral agents. Complex (I) crystallizes in the centrosymmetric space group C2/c (No. 15) with eight molecules in the unit cell with a = 25.227(4), b = 6.527(1), c = 22.489(4) Å, and β = 90.75(1)°. The two spiro units are a 1-adamantylammonium cation and a 1-adamantane carbonyloxy anion. The complex units are stabilized by a network of intermolecular carbonyloxy-to-amine hydrogen bonding and van der Waals cohesive forces. Germane bond lengths are: C—N = 1.479(9) and C—O (mean) = 1.25(2) Å.
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  • 57
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    Journal of chemical crystallography 29 (1999), S. 891-899 
    ISSN: 1572-8854
    Keywords: cyclohexaphosphates ; organometallic compound ; crystal growth ; X-ray diffraction ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Three new cyclohexaphosphates with general formula M0.5((C6H5CH2)2NH2)5P6O18·H2O (M=Co, Cu, Cd) are reported. They crystallize with monoclinic unit-cells and are isotropic. We have determined their structure from the salt M=Co. This later exhibits the following unit-cell parameters: a = 22.739(5), b = 17.682(3), c = 18.342(3) Å, β = 91.22(1)°, Z = 4,P21/n, V = 7373 Å3, and Dx = 1.373 g cm−3. The atomic arrangement can be described as layers containing P6O18 ring anions and CoO6 octahedra spreading in the (101) planes and intercalated by the dibenzylammonium groups and the water molecules. Synthesis and characterization by X-ray diffraction, IR absorption, and TA are described.
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  • 58
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    Journal of chemical crystallography 29 (1999), S. 1107-1110 
    ISSN: 1572-8854
    Keywords: crystal structure ; ytterbium ; lanthanide ; coordination complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The preparation and structural characterization of [YbI2(DME)2] are reported. The complex crystallizes in the triclinic space group P 1¯: a = 13.0094 (10), b=14.504(3), c = 14.668 (3) Å, α = 115.281(10) β = 106.74(2), γ = 105.97(2)°. The metal center of the complex exhibits a distorted pentagonal bipyramidal coordination geometry which involves a rare example of a monodentate DME ligand.
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  • 59
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    Journal of chemical crystallography 29 (1999), S. 1127-1132 
    ISSN: 1572-8854
    Keywords: crystal structure ; phenyl-substituted cyclopentenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structures of two stereoisomers of tetraphenyl- and pentaphenyl-substituted cyclopentenes 1 and 2 have been determined by X-ray analysis. An envelope conformation 1E has been ascertained for the cis isomer 1a, whereas the cis, cis isomer 2a, which crystallizes in two different space groups, P1¯ and P21/n, displays a twisted 2T1 conformation. The phenyl substituents are all tilted with respect to the cyclopentene ring in both structures. Compound 1a crystallizes in the space group P21/a with a = 18.553(3), b = 6.006(2), c = 19.355(5), β = 102.67(4)°, and V = 2104.2(g) Å3 for Z = 4; compound 2a I crystallizes in P21/n with a = 10.064(2), b = 20.756(5), c = 12.245(3) Å, β = 95.21(2)°, and V = 2547(1) Å3 for Z = 4; compound 2aII crystallizes in P1¯ with a = 10.117(3), b = 11.750(2), c = 12.359(2) Å, α = 111.25(2), β = 94.84(2), γ = 108.78(2)°, and V = 1262.3(6) Å3 for Z = 2.
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  • 60
    ISSN: 1572-8854
    Keywords: copper (II) ; histamine ; self-assembly ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract A new monomeric copper (II) complex with histamine (him), [Cu(II)(him)2(No3)2], has been prepared by the reaction of Cu(NO3)2 with histaminium dichloride and its structure was determined by x-ray crystallography. The complex crystallizes in the triclinic system, space group $$P\bar 1$$ with a = 5.7238(4), b = 8.7094(7), c = 9.2481(11) Å, α = 69.693(8), β = 73.242(7), γ = 71.050(7)°, V = 400.84(6) Å3, and Z = 1. The structure consists of discrete [Cu(II)(him)2(NO3)2] molecules in which the metal atom is centrosymmetrically coordinated by two histamine ligands forming an equatorial plane with Cu–N(imidazole ring) being 2.032(2) and Cu–N(NH2 group) being 2.023(2) Å. Two O atoms from nitrate anions coordinate on the elongated axial positions with Cu–O being 2.549(2) Å. In the crystal structure, the molecules are organized by hydrogen bonds forming a two-dimensional network.
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  • 61
    ISSN: 1572-8854
    Keywords: xanthenol ; complex ; crystal structure ; H-bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound 14-hydroxy-14-phenyldibenzo[a,j]xanthene 1 formed a (1:1) complex with diethyl ether. 1,4-Dioxane was also enclathrated, but with a variable stoichiometric ratio. Single crystal X-ray crystallography was used to elucidate the crystal structure of the 1·diethyl ether complex. Crystals are orthorhombic with space group P212121, a = 8.532(3), b = 15.040(4), c = 18.491(5) Å, V = 2373(1) Å3, d c = 1.256 g/cm3, and Z = 4. Host and guest molecules were found to associate via hydrogen bonds, with the guest molecules residing in undulating channels lined by host molecules.
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  • 62
    ISSN: 1572-8854
    Keywords: copper(II) ; Schiff base ; polymidazole ; crystal structure ; properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The square-planar complex [Cu(MIMH)(CH3CO2)](ClO4) (1) (MIMH = [(4-methylimidazol-5-yl)methylene]histamine) was prepared and structurally characterized. Complex 1 crystallizes in the monoclinic space group P21/n with a = 10.5331(10), b = 12.6177(10), c = 12.9773(10) Å, β = 107.710(10)°, V = 1643.0(2) Å3, and Z = 4. Single-crystal X-ray analysis reveals that the copper(II) atom in 1 has a distorted square-planar environment defined by three nitrogen atoms from the Schiff base ligand and one oxygen atom from the acetate group. The Cu—N bond lengths range from 1.950(3) to 2.015(3) Å and the Cu—O(1) bond length is 1.952(2) Å. The electronic spectra of 1 in aqueous solutions indicates that 1 forms adducts of square-pyramidal geometry with H2O. Cyclic voltammetry of 1 in DMF solution shows that there is some degradation of 1 upon reduction.
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  • 63
    ISSN: 1572-8854
    Keywords: pyrazolyl derivative ; substituted pentane ; crystal structure ; bidentate ligand
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The title compound crystallizes in the centrosymmetric space group C2/c with a = 14.4005(23), b = 7.0494(12), c = 11.2462(20) Å, β = 101.572(13)° and Z = 4; the molecule lies on a crystallographic C 2 axis. Hydrogen atoms were both located and refined.
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  • 64
    ISSN: 1572-8854
    Keywords: crystal structure ; Frentizole ; immunomodulator ; structure-function relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Crystals of Frentizole (from ethanol/water) are monoclinic, space group P21/c, with a = 11.187(4), b = 7.392(2), c = 32.727(6) Å, β = 92.77(2)°, Z = 8, D o = 1.47 g/cm3, and D c = 1.472 g/cm3. There are two independent molecules in the crystallographic asymmetric unit with very different conformations. In molecule A the urea group is in the plane of the benzothiazole ring (0.9°) whereas in molecule B the dihedral angle between them is 4.4°. The dihedral angle between the planes of the phenyl group and the benzothiazole ring are ±157° and ±12°, respectively, in the two molecules. The molecules are linked by a pair of N–H···N hydrogen bonds involving the urea nitrogen and two other N–H···N bonds involving the urea nitrogen and the nitrogen of the benzothiazole group.
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  • 65
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    Journal of chemical crystallography 29 (1999), S. 355-358 
    ISSN: 1572-8854
    Keywords: Quinestrol ; sex steroid ; alkyne ; crystal structure ; solvent inclusion ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of the synthetic sex steroid quinestrol (3-O-cyclopentyl-17α-ethynylestradiol) as crystallized from ethanolic solution is determined. The asymmetric unit contains two steroid and one ethanol molecules. The conformation of the two steroid molecules differs in the orientation of the cyclopentane ring. The cocrystallized ethanol molecule facilitates formation of cooperative O—H···O hydrogen bonding. The title compound crystallizes in the monoclinic space group P21, with a = 13.950(6), b = 6.5945(8), c = 25.403(8) Å, β = 104.78(4)°, and D calc = 1.136 g cm−1 for Z = 4.
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  • 66
    ISSN: 1572-8862
    Keywords: Cluster core M6E8 ; structural characteristics ; crystal structure ; hexacobalt cluster complex ; phosphine ; sulfide bridging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Two new members of the hexanuclear series [Co6S8(PR3)6] n+, complexes [Co6S8(PMe2Ph)6](ClO4) (1) and [Co6S8P(OMe)3 6] (2), have been synthesizes and characterized by X-ray diffraction analyses. Their formation process was postulated to go through trinuclear μ3--S bridged moieties. The structural characteristics of the M6E8P6 skeleton of a whole series of [M6E8(PR3)6] n+ (M=Co, Cr, Fe, Mo; E=S, Se, Te) complexes are presented in terms of atomic distances and core volumes.
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  • 67
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    Journal of neural transmission 106 (1999), S. 1-21 
    ISSN: 1435-1463
    Keywords: Keywords: Paraquat ; Parkinson's disease ; transcription factor ; AP-1 ; apoptosis ; cycloheximide ; genistein ; SOD ; catalase ; oxidative stress.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. Drugs and certain environmental toxins may be responsible for the pathogenesis of Parkinson's disease. We have used paraquat as a model toxin for this study since paraquat has been shown to make its way to the nerve terminals and cause cell death of dopamine neurons by oxidative injury. We have shown by the electrophoretic mobility shift assay that paraquat, together with low concentrations of chelated iron (Fe++/DETAPAC), induced the activation of transcription factor AP-1 binding activity to DNA. Under similar conditions we also found by both a DNA laddering assay procedure and by terminal deoxynucleotidyl transferase assay (TUNEL assay) that paraquat also induces apoptotic cell death. Interestingly, both apoptotic cell death and AP-1/DNA binding activity induced by paraquat were blocked by cyclohexamide and genistein, indicating that both the AP-1/DNA binding activation and apoptosis induced by paraquat are closely related. Moreover, cells were also protected from paraquat toxicity in the presence of antioxidant defense enzymes SOD and catalase. The results support the hypothesis that oxidative stress may be contributing to the apoptotic cell death of dopaminergic neurons, leading to the manifestation of Parkinson's disease. Since paraquat was an important herbicide in the mid 20th Century, our results have the important implication that exposure to environmental toxins such as paraquat may induce Parkinson's disease.
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  • 68
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    Italian journal of neurological sciences 20 (1999), S. 55-58 
    ISSN: 1126-5442
    Keywords: Key words Rhombencephalopathy ; Radionecrosis ; Magnetic resonance imaging ; Hyperbaric oxygen ; Heparin ; Buspirone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the case of a patient who underwent radiotherapy of the neck because of an epidermoid carcinoma in Rosenmüller's fossa. Eleven months later, T1-weighted brain magnetic resonance imaging (MRI) revealed a bulbo-pontine lesion, and the clinical course and sequential MRI results led to a diagnosis of radionecrosis-induced rhombencephalopathy. At a distance of more than three years, the lesion is no longer visible on MRI images but the severe neurological deficits remain. The clinical picture has not been improved by treatment with prednisone, hyperbaric oxygen, symptomatic therapies or anticoagulants.
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  • 69
    ISSN: 1126-5442
    Keywords: Key words Hepatolenticular degeneration ; Affective disorders ; Magnetic resonance imaging ; Antidepressive agents ; Interpersonal psychotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a case of Wilson's disease with late psychiatric onset. Major depressive disorder was the first clinical manifestation at the age of 38 years. After pharmacotherapy with antidepressive agents, a manic episode was oberseved. Extrapyramidal hand tremor and micrography were the first neurological signs. Emotional lability occurred during worsening of extrapyramidal signs. Diagnosis was based on urinary and serum copper levels, ceruloplasmin serum level, Kayser-Fleischer ring, and liver biopsy that detected cirrhosis. Magnetic resonance imaging revealed basal ganglia hyperintensity on T1-weighted images, and hypodensity in the central part and hyperintensity in the peripheral part of the lentiform nucleus on 72-weighted images. Hyperintensity on T2-weighted images was also observed in the dorsal part of the midbrain. 123I-iodobenzamide single photon emission computed tomography (IBZM-SPECT) detected a normal distribution of the drug in the brain, with better signal in the right side and deficit of D2-dopaminergic receptors in the basal ganglia, Abnormal manganese erythrocyte level was observed. Treatment was based on penicillamine, zinc salts, low-copper diet, antidepressant agents, interpersonal psychotherapy and neurorehabilitation.
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  • 70
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    Emergency radiology 6 (1999), S. 282-289 
    ISSN: 1438-1435
    Keywords: Key words Radiology ; Computed tomography ; Magnetic resonance imaging ; Soft-tissue sign ; Arm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract More modern imaging techniques allow us to supplement the information available on soft-tissue signs seen on radiographs. This improves our diagnostic capability, as demonstrated here in the upper extremity.
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  • 71
    ISSN: 1438-1435
    Keywords: Key words Spinal cord ; Birth injury ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We present the acute MR findings in an infant with a complicated traumatic delivery, asphyxia, spinal cord injury, and a radiographically apparent cervical spine fracture-dislocation. MRI including diffusion-weighted imaging allowed early characterization and localization of the extent of spinal cord injury.
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  • 72
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    Neurosurgical review 22 (1999), S. 112-116 
    ISSN: 1437-2320
    Keywords: Key words Ganglioma ; Brain tumor ; Magnetic resonance imaging ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The authors present the case of a 33-year-old patient with a bifocal ganglioglioma located in the right superior temporal gyrus. He had a history of tonic–clonic seizures and developed intermittent nausea and vertigo later on. Magnetic resonance imaging showed two distinct, small lesions in the right temporal lobe. Both tumors were removed microsurgically with ultrasound guidance. Intraoperatively, two distinct tumors were found. Histological diagnosis of both tumors was of ganglioglioma WHO II. Postoperatively, the patient was free of symptoms. Bifocal occurrence or the coincidence of two distinct gangliogliomas is a very uncommon finding. So far, it has not yet been reported in benign gangliogliomas.
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  • 73
    ISSN: 1437-2320
    Keywords: Key words Cerebellopontine angle ; Constructive interference in steady-state imaging ; Diffusion-weighted imaging ; Epidermoid tumor ; Magnetic resonance imaging ; Surgical treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe the usefulness of three-dimen-sional Fourier transformation-constructive interference in steady-state (CISS) imaging and diffusion-weighted imaging (DWI) in the pre- and postoperative magnetic resonance imaging evaluation of intracranial epidermoid tumors. Two surgically proven epidermoid tumors in the cerebellopontine (CP) angle were not identified in conventional T1- and T2-weighted images because of a signal intensity similar to that of cerebrospinal fluid (CSF). CISS images clearly demonstrated displacement of the cranial nerves and a shift caused by a lesion in the cistern, but the signal intensity of the tumor by CISS was not sufficiently different from that of CSF to demonstrate the tumor directly. Using DWI, the tumor in the cistern was shown clearly by its increased signal intensity. Together, CISS and DWI compensated for each other's disadvantages, and this combination was useful in guiding surgical treatment of epidermoid tumors in the CP cistern.
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  • 74
    ISSN: 1437-2320
    Keywords: Key words Brain tumor ; Cerebral hydatidosis ; Chitinoma ; Echinococcosis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Solitary brain affection is rare in echinococcosis. We report the case of a 35-year-old woman presenting with symptomatic grand-mal epilepsy due to a right frontal, partially cystic space-occupying lesion. Pre-operative computed tomography and magnetic resonance imaging (MRI) suggested a cystic astrocytoma. However, histological examination yielded the diagnosis of a `chitinoma', a rare subtype of solid cerebral hydatid disease (echinococcosis). It mimicked a primary brain tumor and, therefore, posed a diagnostic problem. We present the – to our knowledge – first MRI scans in a case of a histologically proven chitinoma.
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  • 75
    ISSN: 1572-8773
    Keywords: cadmium ; apoptosis ; RT-PCR ; p53 gene expression ; testes ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Reverse transcription (RT) PCR technique was used to investigate the mechanism of apoptosis induced by Cd and the change of its related genes in testes and prostate of rats. Adult male rats were given a single (s.c.) injection of CdC l2 0, 2.5, 5.0, 10 μmol/kg. 48 h and 72 h after administration of Cd, animals were sacrificed. The results indicated that Cd can induce apoptosis in testes via p53-independent pathway. No apoptosis occurred in prostate in any of the Cd-exposed groups. There was a clearly negative relationship in testes between p53 gene expression and Cd exposure and this dose-response relationship was observed both at 48 h and 72 h. There was a very small increase of this gene expression in the dorsolateral lobe of the prostate in Cd exposed groups. The other apoptosis related gene, bcl-x, was not detectable in either control or Cd-exposed group in testes and dorsal prostate. Although the MT-I gene was expressed in testes or dorsal prostate both in control and exposed groups, no overexpression of MT-I gene was found after administration of Cd . The expression of MT-I in the ventral prostate was not detected in the control group, but a weak expression was found after Cd exposure. Since p53 is a tumo r suppressor gene which can inhibit tumorigenesis, the consequence of a Cd-induced decrease of p53 in testes may have a relation to the known risk of Cd tumorigenesis in this tissue.
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  • 76
    ISSN: 1569-8041
    Keywords: AML ; apoptosis ; etoposide ; γ-GCS ; glutathione ; oxidative stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Etoposide mediates its cytotoxicity by inducing apoptosis. Thus, mechanisms which regulate apoptosis should also affect drug resistance. Oxidants and antioxidants have been shown to participate in the regulation of apoptosis. We were interested in studying whether responsiveness of acute myeloblastic leukemia (AML) cells to etoposide is mediated by oxidative stress and glutathione levels. Patients and methods: Two subclones of the OCI/AML-2 cell line which are etoposide-sensitive (ES), and etoposide-resistant (ER), were established by the authors at the University of Oulu, and used as models. Assays for apoptosis included externalization of phosphatidylserine (as evidenced by annexin V binding), and caspase activation as indicated by cleavage of poly(ADP-ribose)polymerase (Western blotting). Peroxide formation was analyzed by flow cytometry. Glutathione and gamma-glutamylcysteine synthetase (γ-GCS) levels were determined spectrophotometrically and by Western blotting, respectively. Results: Etoposide-induced apoptosis was evident 12 hours after treatment in the ES subclone, but was apparent in the ER subclone only after 24 hours. The basal glutathione and γ-GCS levels were higher in the ER than the ES subclone. Etoposide increased peroxide formation in both subclones after 12-hour exposure. Significant depletion of glutathione was observed in the ES subclone during etoposide exposure, while glutathione levels were maintained in the ER subclone. In neither of the subclones was induction of γ-GCS observed during 24-hour exposure to etoposide. Furthermore, the catalytic subunit of γ-GCS was cleaved during apoptosis, concurrent with depletion of intracellular glutathione. When glutathione was depleted by treatment with buthionine sulfoximine, a direct inhibitor of γ-GCS, the sensitivity to etoposide was increased, particularly in the ER subclone. Conclusions: The results underline the significance of glutathione biosynthesis in the responsiveness of AML cells to etoposide. The molecular mechanisms mediating glutathione depletion during etoposide exposure might include the cleavage of the catalytic subunit of γ-GCS.
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  • 77
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    Annals of oncology 10 (1999), S. 495-503 
    ISSN: 1569-8041
    Keywords: antisense ; apoptosis ; bcl-2 ; lymphoma ; leukaemia ; phase I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
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  • 78
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    Annals of oncology 10 (1999), S. 1011-1021 
    ISSN: 1569-8041
    Keywords: apoptosis ; chemosensitivity ; cytotoxicity ; p53
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Although hematologic malignancies and some solid tumors such as germ cell tumors and pediatric malignancies can be cured by cytotoxic treatment, the most prevalent solid tumors are relatively resistant to these interventions. Apoptosis is involved in the cell kill of anticancer drugs and p53 is believed to be of principal importance in this process. However p53 also plays a role in cell cycle arrest and DNA repair, cellular processes that can decrease the sensitivity to chemotherapy. Therefore, p53 may play a dual role after exposure to cytotoxic treatment, activating either mechanisms that lead to apoptosis or launching processes directing to DNA repair and survival of the cell. Design: In this article, we review in details the p53functions involved in the mediation of chemosensitivity. The preclinical and clinical data published in the recent years about the relation between p53 and chemosensitivity are discussed and the potential pitfalls associated to most of these studies, and that may account for the contradictory results produced so far are also mentioned.
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  • 79
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    Annals of oncology 10 (1999), S. 31-38 
    ISSN: 1569-8041
    Keywords: apoptosis ; lanreotide treatment ; neuroendocrine gastrointestinal tumors ; octreotide ; somatostatin analogs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neuroendocrine gastrointestinal tumors express somatostatin receptors (ssts) in 80%–90% of cases and somatostatin analogs have become increasingly important in the management of these patients. Most of the presently available somatostatin analogs (octreotide, RC-160, and lanreotide) bind to the sst2 and sst5, and in higher doses to sst3 of the ssts 1–5 described. Clinical improvement during somatostatin analog therapy is mainly mediated via a direct inhibitory effect on hormone production from the tumors, seen in 30%–70% of the patients. Also indirect non-tumor mediated effects on peripheral target organs contribute to the subjective improvement, achieved in 30%–70% of patients. Recently, significant improvement of quality of life has been demonstrated with long-acting depot formulations. There is little or no effect on tumor growth during octreotide therapy; tumor shrinkage has been reported in 10%–20% of patients, but stabilization of tumor growth can be achieved in about half of the patients with a duration of 8–16 months. Recently, induction of apoptosis has been described with high doses of lanreotide (12 mg/d). Eventually, however, all patients escape from somatostatin analog therapy with regard both to hormonal production and tumor growth, and the mechanism behind the tachyphylaxis is not yet known. Studies of optimal dosage and modes of administration, development of new slow release formulations, the potential value of high-dose somatostatin analog therapy and novel somatostatin receptor subtype specific analogs are important directions for the use of somatostatin analogs in the future. In addition, assessment of somatostatin receptor status for each patient and studies of tumor biology, e.g., inhibition of exocytosis, antiproliferative effects and induction of apoptosis during treatment will help to optimize treatment and provide new insights into mechanisms of action of somatostatin analogs.
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  • 80
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Intrazerebrale Blutung ; Magnetresonanztomographie ; Hämosiderin ; Key words Intracerebral hematome ; Magnetic resonance imaging ; Hemosiderin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Increased use of gradient echo T2*- weighted gradient echo sequences in magnetic resonance imaging (MRI) of patients suffering from primary ICH called attention to foci of signal loss which were suggested to represent remnants of cerebral microbleeds. In a post mortem correlative MR and histopathological study we provide support for this notion. We found areas of signal loss on gradient echo T2*-weighted sequences in 7 out of 11 brains of patients who had died of intracerebral hematoma. Histopathologically, these areas represented hemosiderin deposits indicating previous extravasation of blood. To provide data about the prevalence of these MRI findings in a healthy elderly population a subgroup of participants of the Austrian Stroke Prevention Study was analyzed. We detected foci of signal loss on gradient echo T2*-weighted sequences in 18 out of 280 volunteers (6,4%). MR-based evidence of previous microbleeds may indicate a potentially higher risk of suffering from intracerebral bleeding which could have therapeutic implications for the treatment of acute stroke and for secondary prevention. This hypothesis will have to be tested in future prospective trials.
    Notes: Zusammenfassung Vermehrte Anwendung T2*-gewichteter Gradienten-Echo-Sequenzen bei Magnetresonanztomographie- (MRT-) Untersuchungen von Patienten nach einem intrazerebralen Hämatom machte auf kleine, hypointense Areale aufmerksam, von denen bisher nur angenommen wurde, daß sie abgelaufene Mikroblutungen darstellen. In einer Post-mortem-Studie mit MRT und vergleichenden histopathologischen Untersuchungen zeigen wir Daten, die diese Hypothese stützen. Bei 7 von 11 Patienten, die an primärem intrazerebralem Hämatom verstorben waren, fanden sich hypointense Areale in T2*-Gradienten-Echo-Sequenzen. Histopathologisch zeigten diese Areale Hämosiderin-Ablagerungen, welche auf abgelaufene Blutungen hinweisen. Um Aussagen über die Prävalenz dieser MRT-Befunde in einem Kollektiv klinisch unauffälliger Probanden mittleren Alters machen zu können, wurden Teilnehmer derÖsterreichischen Schlaganfall-Vorsorge-Studie untersucht. Bei 18 von 280 Probanden (6,4%) fanden sich Signalhypointensitäten in T2*-Gradienten-Echo-Sequenzen. Der MR-tomographische Nachweis abgelaufener Mikroblutungen könnte ein Hinweis auf ein erhöhtes zerebrales Blutungsrisiko sein, was therapeutische Konsequenzen für die primäre Therapie und Sekundärprophylaxe beim Schlaganfall haben könnte. Hierzu sind noch weitere prospektive Studien notwendig.
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  • 81
    ISSN: 1433-0458
    Keywords: Schlüsselwörter Schädelbasis ; Innerer Gehörgang ; Tumor ; Hämangiom ; Kernspintomographie ; Computertomographie ; Key words Skull-base tumors ; Internal auditory meatus ; Hemangiomas ; Magnetic resonance imaging ; Computed tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Hemangiomas of the skull base are rare neoplasms and are easily misdiagnosed as acoustic neuromas when occurring in the internal auditory canal. Among these tumors, ossifying hemangiomas are characterized histologically be newly formed bone tissue within their substance. We describe a 26-year old female patient who presented with left-sided sensorineural hearing loss and tinnitus. T2-weighted magnetic resonance imaging demonstrated a bright space-occupying lesion of the internal auditory canal with extension to the geniculate ganglion. Bony erosions of the internal auditory canal were proved by high-resolution computed tomography. A hemangioma was suspected preoperatively and was resected via a middle cranial fossa approach. Histologically, new bone formations were found in a cavernous hemangioma. In general, radiologic findings can suggest a hemangioma of the internal auditory canal and help to differentiate it from acoustic neuroma. Based on the histological findings of intratumoral bone formation, the hemangioma in our patient was classified as an ossifying hemangioma. However, reactive bone formation at the borders of a tumor in the internal auditory canal can also be mistaken as new intratumoral bone formation.
    Notes: Zusammenfassung Hämangiome der Schädelbasis sind insgesamt seltene Tumoren, die im Bereich des inneren Gehörgangs insbesondere mit dem wesentlich häufigeren Akustikusneurinom verwechselt werden können. Das ossifizierende Hämangiom repräsentiert eine Sonderform in der Gruppe der Hämangiome und ist histopathologisch durch intratumorale Knochenneubildungen gekennzeichnet. Es wird von einem kavernösen Hämangiom des linken inneren Gehörgangs bei einer 26jährigen Patientin berichtet, welches zu einer progredienten sensorineuralen Hörminderung und Tinnitus geführt hatte. Bei T2-gewichteter kernspintomographischer Darstellung einer signalreichen Neubildung im inneren Gehörgang mit computertomographisch evidenten Knochendestruktionen am Gehörgangsboden war präoperativ die Abgrenzung von einem Akustikusneurinom möglich. Über einen transtemporalen Zugang konnte die vaskuläre Neubildung reseziert werden. Histopathologisch waren Knochenneubildungen in einem kavernösen Hämangiom zu erkennen. Die radiologischen Befunde ermöglichen präoperativ die Abgrenzung eines Hämangioms vom Akustikusneurinom. Aufgrund des Nachweises von Knochenneubildungen in den histologischen Schnittpräparaten des Tumors ist die Einordnung des kavernösen Hämangioms als ossifizierendes Hämangiom naheliegend. Neben der Wertung der histologisch nachgewiesenen Knochenneubildungen als intratumorale Ereignisse muß auch an die Möglichkeit einer in den Schnittpräparaten vorgetäuschten intratumoralen Knochenneubildung durch den Anschnitt reaktiver Knochenneubildungen am destruierten Gehörgangboden gedacht werden.
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  • 82
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    Der Nervenarzt 70 (1999), S. 679-687 
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Perfluorcarbon-Emulsionen ; Perfluorcarbone ; Neuroprotektion ; Ischämie ; Reperfusionsschaden ; Kernspintomographie ; Tumorversorgung ; Key words Perfluorocarbon emulsions ; Perfluorochemicals ; Cerebral protection ; Ischemia ; Reperfusion injury ; Magnetic resonance imaging ; Tumor oxygenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary For the ussage as blood substitutes perfluorocarbons (PFC) have been developed as artificial oxygen carriers. In addition they may have potency for protective use in ischemic tissue. Formulation improvement achieved higher oxygen carrying capacity and better compatibility than the first generation of PFC. Preclinical studies have been performed in animal heart and brain. Former and progressed emulsification for intravascular use have been investigated for infarction and reperfusion injury. This investigations are reviewed and the potencies for the use of PFC in neurology, neurosurgery, diagnostics today and in the future are emphasized.
    Notes: Zusammenfassung Perfluorcarbone (PFC) sind künstliche Sauerstoffträger, die ursprünglich als Blutersatzstoffe entwickelt wurden. Auf Grund ihrer spezifischen Eigenschaften ist darüber hinaus ihr Einsatz bei ischämischen Perfusionsstörungen von potentiellen Nutzen. Neuere Perfluorcarbonpräparationen verfügen über eine höhere Sauerstofftransportkapazität und sind mit weniger Nebenwirkungen behaftet als die PFC der ersten Generation. Ältere und neuere PFC-Emulsionen, die für die intravaskuläre Applikation geeignet sind, wurden und werden im Tierversuch für den Einsatz in ischämischen Gebieten des Herzens und des Gehirns untersucht. In dieser Arbeit werden präklinische Studien bei Infarkten und Reperfusionsschaden beschrieben und potentielle Nutzungsmöglichkeiten dieser Substanzgruppe für diese Indikationsstellung diskutiert.
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  • 83
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Intrakranielle Blutung ; Magnetresonanztomographie ; T2*-gewichtete Gradienten-Echo-Sequenz ; Hypertensive zerebrale Mikroangiopathie ; Zerebrale Amyloidangiopathie ; Zerebrale Kavernome ; Key words Intracerebral hemorrhage ; Magnetic resonance imaging ; Cerebral amyloid angiopathy ; Hypertensive cerebral microangiopathy ; Cerebral cavernoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary In four patients presenting with acute nontraumatic intracerebral or intraspinal hemorrhage, T2*-weighted gradient-echo MRI showed numerous residual hemosiderin deposits due to old intracerebral hemorrhages that were missed on initial CT and spin-echo MRI. The demonstration of additional chronic bleedings and their anatomical distribution provided important diagnostic information. In a hypertensive patient, the hemosiderin deposits were most pronounced within deep brain structures suggesting hypertensive cerebral microangiopathy. In a second patient, the cortico-subcortical distribution of the hemorrhages was typical of cerebral amyloid angiopathy. In a third patient, the diffuse distribution including spinal bleeding, the marked calcification, and the characteristic appearance on spin-echo MRI were consistent with multiple cavernomas. In another patient with cerebral and spinal hemorrhage, T2*-weighted gradient-echo MRI revealed new subclinical hemorrhages during follow-up. Based on these findings, we recommend that T2*-weighted gradient-echo MRI of the brain should be performed in all patients with acute intracranial and spinal bleedings.
    Notes: Zusammenfassung Bei 4 Patienten mit akuten intrazerebralen oder intramedullären Blutungen konnte die T2*-gewichtete Gradienten-Echo-Magnetresonanztomographie (“Häm”-Sequenz) multiple intrakranielle Hämosiderinablagerungen als Beleg für in der Vergangenheit abgelaufene Hirnblutungen nachweisen. Diese klinisch stummen Blutungen waren sowohl der Computertomographie als auch der Spin-Echo-Magnetresonanztomographie entgangen. Bei 3 Patienten ermöglichte das Verteilungsmuster der als Signalauslöschungen dargestellten Hämosiderinablagerungen eine bessere Eingrenzung der Blutungsursache. Bei einem Patienten mit arterieller Hypertonie legten die vorwiegend in den tieferen Hirnstrukturen lokalisierten Blutungen eine hypertensive zerebrale Mikroangiopathie nahe. Bei einem Patienten mit rezidivierenden Lobärhämatomen sprach die kortikosubkortikale Lokalisation der Blutungen für das Vorliegen einer zerebralen Amyloidangiopathie. Bei einer Patientin mit spinaler Blutung stellten wir aufgrund des diffusen Verteilungsmusters, der starken Verkalkungstendenz und des heterogenen Signalverhaltens der Blutungsherde in der Spin-Echo-Magnetresonanztomographie die Diagnose multipler zerebrospinaler Kavernome. Bei einem Patienten mit zerebralen und spinalen Blutungen erlaubte die “Häm”-Sequenz keine diagnostische Einordnung, erwies sich aber als sensitives Instrument in der Verlaufskontrolle. Bei allen Patienten mit spontaner intrazerebraler oder intraspinaler Blutung sollte im Rahmen der bildgebenden Diagnostik eine “Häm”-Sequenz durchgeführt werden.
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  • 84
    ISSN: 1437-9813
    Keywords: Key words Cholangiography ; Choledochal cyst ; Cholestasis ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance cholangiopancreaticography (MRCP) was used to visualize the biliary tract in two children, aged 7 weeks and 10 years, with a choledochal cyst. MRCP was successful in both cases and the findings were confirmed by intraoperative cholangiography.
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  • 85
    ISSN: 1432-2161
    Keywords: Key words Joint ; Knee ; Anatomy ; Magnetic resonance imaging ; Posteromedial corner ; Intra-articular contrast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Objective. The objective of this study was to illustrate the magnetic resonance (MR) image appearance of the structures of the posteromedial ”corner” of the knee with particular emphasis on the anatomy and differentiation between the medial collateral ligament and the posterior oblique ligament. Design. Six cadaveric knee specimens underwent MR imaging, before and following instillation of intra-articular contrast material. The knees were sectioned in the axial, coronal, and coronal oblique planes and the gross morphology of the posteromedial corner and surrounding structures was studied and correlated with the MR images. Patients. The human cadaveric specimens were from two female and four male patients (age at death, 72–86 years; average, 78 years). Results and conclusions. The contrast-enhanced sequences and the coronal oblique images allowed for improved visualization of the structures.
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  • 86
    ISSN: 1432-2161
    Keywords: Key words Bone tumor ; Chondrosarcoma ; CT ; Magnetic resonance imaging ; Tumor of the ankle ; Tumor of the foot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The foot is an uncommon location for chondrosarcoma. The presentation, diagnosis, pathological findings, surgical treatment and follow-up of three patients with chondrosarcoma in this rare location are presented. Though nonspecific, MR imaging findings were of aid in the diagnosis and treatment planning of these patients. If the diagnosis of this tumor is rapidly made, a tumor excision instead of limb amputation may be sufficient treatment at surgery.
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  • 87
    ISSN: 1436-2813
    Keywords: Key Words: nitric oxide ; DNA damage ; apoptosis ; tumor necrosis factor-α ; mitochondrial respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: S -nitroso-N-acetylpenicillamine protected cul-tured L929 cells from apoptosis induced by tumor necrosis factor-α (TNF-α) plus actinomycin D, as determined by the detection of DNA fragmentation and morphological changes. NO also prevented an enhancement of the production of reactive oxygen intermediates by TNF-α plus actinomycin D, as assessed by the oxidation of dihydrorhodamine 123 and hydroethidine. Because the inhibition of mitochondrial respiration by rotenone or antimycin A suppressed the increased oxidation of both dihydrorhodamine 123 and hydroethidine, it was suggested that TNF-α accelerated the leakage of reactive oxygen intermediates from the mitochondrial electron transport system. Polarography showed that NO reversibly inhibited mitochondrial respiration at either complexes I–III, II–III, or IV, thus suggesting the inhibition of cytochrome oxidase. Taken together, these findings indicate that the decreased mitochondrial formation of reactive oxygen intermediates in the presence of NO might have a protective effect against TNF-α plus actinomycin D-induced apoptosis.
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  • 88
    ISSN: 1436-2813
    Keywords: angiogenesis ; p53 ; apoptosis ; lung adenocarcinoma ; hematogenous metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to clarify which factors are important as predictors not only of patient survival but also of hematogenic metastasis in 15 patients with stage I lung adenocarcinoma who underwent curative operation. The relationship between tumor angiogenesis, apoptosis, and p53 oncogene was also studied. A total of 15 patients were divided into two groups: surviving group (n=7) and nonsurviving (metastasis) group (n=8). We studied the medical charts, operative records, pathologic reports, and tumor specimens taken at surgical resection. We measured the apoptotic index using the ApopTag kit and the intratumoral microvessel count using an anti-CD34 monoclonal antibody. In addition, immunohistochemical staining for the expression of p53 was conducted simultaneously. The clinicopathological characteristics, including age, sex, tumor size (pT), and histological differentiation, were not significantly different between the surviving and the nonsurviving group. The microvessel count was significantly higher in nonsurviving group than in the surviving group. The apoptotic index and the expression of p53 was not significantly different between the two groups. An inverse correlation between the apoptotic index and microvessel count, and a positive correlation between the expression of p53 and microvessel count, were observed. Angiogenesis may be an important prognostic factor in patients with stage I lung adenocarcinoma.
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  • 89
    ISSN: 1436-2813
    Keywords: Key Words: angiogenesis ; p53 ; apoptosis ; lung adenocarcinoma ; hematogenous metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: n = 7) and nonsurviving (metastasis) group (n = 8). We studied the medical charts, operative records, pathologic reports, and tumor specimens taken at surgical resection. We measured the apoptotic index using the ApopTag kit and the intratumoral microvessel count using an anti-CD34 monoclonal antibody. In addition, immunohistochemical staining for the expression of p53 was conducted simultaneously. The clinicopathological characteristics, including age, sex, tumor size (pT), and histological differentiation, were not significantly different between the surviving and the nonsurviving group. The microvessel count was significantly higher in nonsurviving group than in the surviving group. The apoptotic index and the expression of p53 was not significantly different between the two groups. An inverse correlation between the apoptotic index and microvessel count, and a positive correlation between the expression of p53 and microvessel count, were observed. Angiogenesis may be an important prognostic factor in patients with stage I lung adenocarcinoma.
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  • 90
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    Diabetologia 42 (1999), S. 711-718 
    ISSN: 1432-0428
    Keywords: Keywords Malnutrition ; ageing ; beta-cell mass ; apoptosis ; glucose tolerance.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. In a recently developed rat model, maternal food restriction from day 15 of pregnancy until weaning induced low birth weight and a 70 % reduction of beta-cell mass in the offspring at day 21 after birth. Subsequent renutrition from weaning was insufficient to fully restore beta-cell mass in young adult rats. The aim of this study is to investigate the long-term consequences of early malnutrition on beta-cell mass and function. Methods. Oral glucose tolerance tests were done in 3- and 12-month-old animals and beta-cell mass and apoptosis were determined by morphometrical measurements on pancreatic sections. The specific impact of postnatal malnutrition was studied by comparing control animals (C group) with animals malnourished during their fetal life only (R/C group), and animals malnourished during fetal life and until weaning (R group). Results. In 3-month-old R/C animals beta-cell mass reached 8.0 ± 1.5 mg with no further increase until 12 months (8.1 ± 1.5 mg), compared with 9.3 ± 1.9 mg in control rats. Twelve-month-old R/C animals showed normal plasma insulin responses and borderline glucose tolerance. In R animals, apoptosis reached 1.9 ± 0.4 % of the beta cells at 3 months, compared with 0.7 ± 0.5 % in control rats, and beta-cell mass did not increase between 3 and 12 months (4.7 ± 0.8 mg at 12 months). In aged control and R animals, apoptosis affected 8 % of the beta cells. At 12 months only, R animals showed profound insulinopenia and marked glucose intolerance. Conclusion/interpretation. In conclusion, perinatal malnutrition profoundly impairs the programming of beta-cell development. In animals with decreased beta-cell mass the additional demand placed by ageing on the beta cells entails glucose intolerance since beta-cell mass does not expand and apoptosis is increased. [Diabetologia (1999) 42: 711–718]
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  • 91
    ISSN: 1432-0428
    Keywords: Keywords Type I diabetes ; interferon-γ ; transgenic mice ; apoptosis ; insulin secretion ; tumour necrosis factor.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Aims/hypothesis. To examine whether interferon-γ destroys islet beta cells directly or indirectly through lymphocyte activation, or whether direct action of interferon-γ on beta cells by itself induces diabetes without insulitis. Methods. To avoid possible nonspecific breakdown of beta cells by transgenic overexpression of interferon-γ by the insulin promoter, we generated transgenic mice expressing interferon-γ under the control of rat glucagon promoter (RGP-IFN-γ-Tg mice). Results. The absence of insulitis in RGP-IFN-γ-Tg mice enabled us to investigate the direct effects of paracrine interferon-γ. In RGP-IFN-γ-Tg mice, serum concentrations of interferon-γ and tumour necrosis factor-α (TNF-α) were 50 and 6 times higher than those in their littermates, respectively, and glucose-responsive insulin secretion decreased to one-half the level of that in the littermates. Transgenic interferon-γ induced remodelling of beta cells where apoptosis of many beta cells was compensated by their vigorous regeneration and diabetes did not occur in most of the RGP-IFN-γ-Tg mice. Conclusion/interpretation. Interferon-γ alone is insufficient for the complete destruction of beta cells in vivo, and factors other than interferon-γ including activated lymphocytes or other cytokines, are necessary in addition to interferon-γ for the development of Type I (insulin-dependent) diabetes mellitus. [Diabetologia (1999) 42: 566–573]
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  • 92
    ISSN: 1432-0428
    Keywords: Keywords Nicotinamide ; cytokine ; islet ; insulin ; apoptosis ; diabetes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nicotinamide intervention trials are presently undertaken to prevent Type I (insulin-dependent) diabetes in high risk subjects. They are based on studies in rodents reporting nicotinamide protection against beta-cell injury in vitro and in vivo. This study examines whether nicotinamide can protect human beta cells in vitro. At concentrations (2 and 5 mmol/l) to protect rat beta cells against necrosis by streptozotocin or hydrogen peroxide, nicotinamide prevents hydrogen peroxide-induced necrosis of human beta cells. As with rat beta cells, nicotinamide fails to protect human beta cells against apoptosis induced by a combination of the cytokines interleukin-1β , interferon-γ and tumour necrosis factor-α. In rat beta cells, nicotinamide (2 to 20 mmol/l) was also found to induce apoptosis, in particular during the days following its protection against necrosis; this cytotoxic effect was not observed with human beta cells. These data demonstrate that nicotinamide can protect human beta cells against radical-induced necrosis, but not against cytokine-induced apoptosis. This effect is not associated with a delayed apoptosis as in rat beta cells. [Diabetologia (1999) 42: 55–59]
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  • 93
    ISSN: 1126-5442
    Keywords: Key words Carbon monoxide poisoning ; Delayed neurologic sequelae ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The clinical and neuroradiological outcome of carbon monoxide (CO) intoxication was evaluated prospectively in 30 patients over a follow-up period of 3 years. Among the patients studied, 22 had been acutely exposed to CO while 8 were chronically exposed. One month after CO poisoning, 12 of the 22 patients with acute intoxication showed magnetic resonance imaging (MRI) abnormalities: 6 also had neurological sequelae and 6 were asymptomatic. The remaining 10 patients showed neither MRI abnormalities nor neurological sequelae. During the 3-year follow-up, 4 of the patients with both MRI abnormalities and neurological sequelae improved in both clinical features and MRI findings. One of the 6 asymptomatic patients with MRI abnormalities developed a progressive cognitive impairment 2 months after acute intoxication, with a concomitant severe worsening of the MRI lesions. Among the 10 patients with neither MRI abnormalities nor neurological sequelae, only 1 developed neurological sequelae after a clear period of 4 months. In the group of patients who experienced chronic CO intoxication, only 1 presented with a neuropsychiatric syndrome which improved at follow-up. Brain MRI showed white matter lesions which remained unchanged at control scan after 1 year. In conclusion, we observed that some patients with severe CO poisoning and neurological sequelae may fully regain normal functions after approximately 1 year. The presence of MRI lesions 1 month after CO poisoning did not accurately predict the subsequent outcome. The observation of a clear period longer than the usual 2–40 day interval in 2 patients should be considered for careful planning of follow-up and for prognosis in CO-poisoned patients.
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  • 94
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    Italian journal of neurological sciences 20 (1999), S. 183-186 
    ISSN: 1126-5442
    Keywords: Key words Behçet's disease ; Optic neuropathy ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Orbital magnetic resonance imaging demonstrated increased signal of the optic nerve in short time inversion recovery (STIR) images of two young women with unilateral visual blurring. In both, recurrent oral and genital ulcerations and papulopustular lesions appeared within the next 14–15 months, respectively, allowing a diagnosis of Behçet's disease. Optic neuropathy may be an early manifestation of Behçt's disease and clinical follow-up is crucial for its diagnosis.
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  • 95
    ISSN: 1432-1327
    Keywords: Key words Contrast agents ; Gadolinium complexes ; Magnetic resonance imaging ; Relaxivity ; Tetraazamacrocycles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The ligand DOTASA was designed and synthesized in the aim of obtaining a kinetically and thermodynamically stable Gd(III) chelate which, through its uncoordinated carboxylate function, will provide an efficient pathway to couple the complex to bio- or macromolecules without affecting the coordination pattern of DOTA. Furthermore, it allows us to study the influence of an extra carboxylate arm on the parameters determining proton relaxivity in comparison to the commercial agent [Gd(DOTA)(H2O)]–. A combined variable-temperature 17O NMR, EPR and nuclear magnetic relaxation dispersion study on the Gd(III) chelate resulted in k 298 ex=(6.3±0.2)×106 s–1 for the water exchange rate and τ298 R=125±2 ps for the rotational correlation time. The slight increase in both k 298 ex and τ298 R, as compared to those for [Gd(DOTA)(H2O)]–, is attributed to the presence of the extra negative charge. The longer rotational correlation time results in a proton relaxivity of 5.03 mM–1 s–1 for [Gd(DOTASA)(H2O)]2–, which is approximately 30% higher than that for [Gd(DOTA)(H2O)]–. The increased water exchange rate of [Gd(DOTASA)(H2O)]2– has no consequence for proton relaxivity since this latter is exclusively limited by fast rotation for both complexes. However, for slowly rotating macromolecular agents, which contain a covalently coupled DOTASA unit instead of a coupled DOTA, this increased exchange rate will have a significant positive effect.
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  • 96
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    Experimental brain research 124 (1999), S. 271-272 
    ISSN: 1432-1106
    Keywords: Key words Brain ; Magnetic resonance imaging ; Microemboli ; Microischemia ; N-tert-butyl-α-phenylnitrone ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Dementia due to cerebral ischemic lesions is relatively common in the elderly. Since many of these lesions are probably caused by emboli, studying emboli-induced cerebral lesions in rabbits should, hopefully, provide information that is useful when searching for a means of preventing and treating vascular dementia in humans. Using magnetic resonance imaging we have found that N-tert-butyl-α-phenyl-nitrone (a free radical scavenger) reduced the number of emboli-induced cerebral microinfarctions in the rabbit cortex but did not have any impact on the number of infarctions found in the subcortical structures. The results suggest that significant amount of free radicals are produced in the ischemic foci located in the cortex, but not in the ischemic foci located in the subcortical structures. This finding may be of importance when considering treatments for cerebral ischemia in humans.
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  • 97
    ISSN: 1432-1084
    Keywords: Key words: Liver ; diseases ; Peliosis ; Computed tomography ; Angiography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Peliosis hepatis is an uncommon liver condition characterized by blood-filled cavities. We report the CT, angiographic and MR features of a case of peliosis hepatis with no obvious etiology and spontaneously regressing hemorrhagic necrosis. Helical CT showed multiple peripheral low-density regions with foci of spontaneous high density suggesting the presence of blood component. On MR imaging, the multiple peripheral lesions were hypointense on T1-weighted and hyperdense on T2-weighted images, with bright foci on all sequences suggesting subacute blood. Angiography showed no evidence of tumor or vascular malformation; multiple nodular vascular lesions filling in the parenchymal phase and persisting in the venous phase suggested blood-filled cavities. Pathological examination showed blood-filled spaces with no endothelial lining, characteristic of the parenchymal type of peliosis. Knowledge of the imaging features of hemorrhagic necrosis due to peliosis hepatis is important since it can be responsive to antibiotic therapy. Furthermore, differentiating hemorrhagic necrosis from hepatic abscess avoids dangerous and sometimes fatal percutaneous drainage.
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  • 98
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    Neuroradiology 41 (1999), S. 729-731 
    ISSN: 1432-1920
    Keywords: Key words DIDMOAD syndrome ; Wolfram syndrome ; substantia nigra ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Wolfram syndrome (DIDMOAD) is a rare diffuse neurodegenerative disorder characterised by diabetes insipidus, diabetes mellitus, optic atrophy, deafness, and a wide variety of abnormalities of the central nervous system, urinary tract and endocrine glands. It may be familial or sporadic. Reported features on MRI of the brain are absence of the physiological high signal of the posterior lobe of the pituitary, shrinkage of optic nerves, chiasm and tracts, atrophy of the hypothalamic region, brain stem, cerebellum, and cerebral cortex. We report a 12-year-old girl with a 5-year history without brain stem, cerebellar or cerebral atrophy. MRI showed an unusual feature: a focus of high signal on PD- and T2-weighted images in the right substantia nigra. This is consistent with previously reported neuropathological post-mortem studies, but has never been reported in vivo.
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  • 99
    ISSN: 1432-1920
    Keywords: Key words Parkinson's disease ; Differential diagnosis ; Magnetic resonance imaging ; Signal intensity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A reduction in signal in the basal ganglia on T2-weighted images is said to correlate with a poor response to L-DOPA and may help to identify patients with nonidiopathic parkinsonism. Our aim in this prospective study was to use the contrast-to-noise ratio of the MRI signal on T2-weighted images in various parts of the basal ganglia in 43 patients with de novo parkinsonism. Signal intensity measurements were compared to the response to the dopamine agonist apomorphine and dopamine-D2 receptor binding obtained by 3-iodo-6-methoxybenzamine single-photon emission computed tomography (IBZM-SPECT). A reduced contrast-to-noise ratio in the putamen correlated significantly with a negative response to apomorphine and reduced striatal IBZM binding. No additional signal intensity measurement correlated with response to apomorphine or specific IBZM binding. However, there was a considerable overlap of contrast-to-noise ratios between patients with a positive or negative response to apomorphine or normal and reduced IBZM binding. We suggest that semiquantitative assessment of signal intensity in the putamen shows a significant reduction in patients with probably nonidiopathic parkinsonism compared with patients with probably idiopathic parkinsonism. However, this method does not exclude idiopathic parkinsonism in a given patient.
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  • 100
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    Neuroradiology 41 (1999), S. 140-143 
    ISSN: 1432-1920
    Keywords: Key words Haemangiomas ; head and neck ; Magnetic resonance imaging ; Magnetic resonance angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the clinical effectiveness of contrast-enhanced three-dimensional (3D) magnetic resonance angiography (MRA) for diagnosing head and neck haemangiomas. We studied six patients using a magnetization prepared rapid acquisition gradient-echo (MP-RAGE) sequence on a 1.5-T system. Conventional T1- and T2-weighted and contrast-enhanced images were also obtained. The images were compared with histological findings. In four cavernous haemangiomas, a mass was partially visible as an enhancing lesion on the early phase of MRA, and was completely visible as a larger enhancing lesion in the late phase, showing slow blood flow. In two capillary haemangiomas, a mass was completely visible in the early phase showing fast flow. In all patients, MRA clearly showed both the haemangiomas and the external carotid artery branches. MRA allowed assessment of the relationship between the haemangiomas and the feeding arteries, and of the haemodynamics.
    Type of Medium: Electronic Resource
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