ZIB

1

Digitale Medien

Use of vector volume manometry and endoanal magnetic resonance imaging in the adult female for assessment of anal sphincter dysfunction (1999)

Zbar, Andrew P. ; Kmiot, Witold A. ; Aslam, Mohammed ; [weitere]

Springer

Diseases of the colon & rectum 42 (1999), S. 1411-1418

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ISSN: 1530-0358

Schlagwort(e): Endoanal ; Magnetic resonance imaging ; Vector volume ; Manometry

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02235038

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Digitale Medien

Gemcitabine-Induced Programmed Cell Death (Apoptosis) of Human Pancreatic Carcinoma Is Determined by Bcl-2 Content (1999)

Bold, Richard J. ; Chandra, Joya ; McConkey, David J.

Springer

Annals of surgical oncology 6 (1999), S. 279-285

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ISSN: 1534-4681

Schlagwort(e): Gemcitabine ; bcl-2 ; Pancreatic cancer ; Apoptosis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Background: Gemcitabine is a new nucleoside analogue that produces a clinical response in 30% of patients with unresectable pancreatic carcinoma. The cytotoxic effects of many chemotherapeutic agents occur through induction of programmed cell death (apoptosis), which is controlled by the bcl-2 gene family. We determined whether induction of apoptosis by gemcitabine in pancreatic carcinoma is associated with cellular Bcl-2 content. Methods: Four pancreatic carcinoma cell lines (MIA-PaCa-2, AsPC-1, Panc-1, and Panc-48) were screened by Western blotting for Bcl-2 protein expression. Dose-response relationships for the cytotoxic effects of gemcitabine were determined using methylthiotetrazole assays, and induction of apoptosis was confirmed by fluorescence-activated cell sorting analysis. MIA-PaCa-2 cells transfected with human bcl-2 were also analyzed for gemcitabine-induced apoptosis. Results: Pancreatic cancer cell lines expressed varying amounts of Bcl-2, and the 50% lethal dose for gemcitabine-induced apoptosis was correlated with Bcl-2 content. Furthermore, Bcl-2 overexpression was associated with a significant increase in the 50% lethal dose for gemcitabine-induced apoptosis. Conclusions: Cellular Bcl-2 content was directly correlated with the cytotoxicity of gemcitabine in pancreatic carcinoma. Therefore, routine immunohistochemical analyses may be useful in predicting gemcitabine efficacy, and patients who would likely not benefit could be spared gemcitabine administration. Furthermore, the effectiveness of gemcitabine and other chemotherapeutic agents may be increased by gene therapy-mediated alteration of bcl-2 gene family members.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s10434-999-0279-x

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Digitale Medien

Comparative study of transrectal ultrasonography, pelvic computerized tomography, and magnetic resonance imaging in preoperative staging of rectal cancer (1999)

Kim, Nam Kyu ; Kim, Myung Jin ; Yun, Seong Hyeon ; [weitere]

Springer

Diseases of the colon & rectum 42 (1999), S. 770-775

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ISSN: 1530-0358

Schlagwort(e): Rectal cancer ; Transrectal ultrasonography ; Computerized tomography ; Magnetic resonance imaging

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02236933

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4

Digitale Medien

Wirbelsäulen- und Beckenfrakturen im Wachstumsalter (1999)

Friedl, H. P. ; Götze, B. ; Czermak, B. ; [weitere]

Springer

Trauma und Berufskrankheit 1 (1999), S. S92

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ISSN: 1436-6274

Schlagwort(e): Schlüsselwörter Wachstumsalter ; MRI ; Beckenfraktur ; Wirbelsäulenfraktur ; Key words Childhood ; Magnetic resonance imaging ; Pelvic fracture ; Spinal injury

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: 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.

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/PL00014858

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5

Digitale Medien

Compensatory responses of Samea multiplicalis larvae when fed leaves of different fertilization levels of the aquatic weed Pistia stratiotes (1999)

Wheeler, G.S. ; Halpern, M.D.

Springer

Entomologia experimentalis et applicata 92 (1999), S. 205-216

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ISSN: 1570-7458

Schlagwort(e): Samea multiplicalis ; Spodoptera pectinicornis ; Pistia stratiotes ; waterlettuce ; nitrogen utilization efficiency ; compensatory feeding ; nitrogen ; biological control of weeds

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Compensatory responses of caterpillars fed low quality food include increased consumption and utilization of essential nutrients. Information about an insect's responses to nutritional challenges from their host plants could benefit weed biological control efforts in the selection and establishment of new agents. The target weed, Pistia stratiotes L. (Araceae) is a floating aquatic plant that has relatively low nitrogen levels which are further diluted with high water content. Efforts to establish the insect Spodoptera pectinicornis (Hampson) (Lepidoptera: Noctuidae) for biological control of P. stratiotes could benefit by examining the nutritional responses of a similar widely established lepidopteran species, Samea multiplicalis (Guenèe) (Lepidoptera: Pyralidae). Larvae of this species were fed leaves of P. stratiotes plants that had been fertilized (NPK) at high and low rates. The leaves of the fertilized plants had a 4.3-fold increase in nitrogen (dry weight) and a 1.6-fold increase in water content. The results suggest that no compensatory increases occurred in larvae fed leaves from the low fertilized plants as no changes were found in fresh mass consumption or nitrogen utilization efficiency. Consequently, development time from second-third instars to pupation was delayed about 3 days compared with larvae fed the high nitrogen leaves. Furthermore, consumption of nitrogen was only 30% and its accumulation into larval tissues was only 60% compared with the larvae fed the high fertilized leaves. The resulting larvae had both a final biomass and a growth rate that were reduced by 40%. Regardless of plant fertilizer level, the larvae fed at a rate 5–10 times greater than that of similar lepidopteran species consuming either low or high quality diets, suggesting that the S. multiplicalis larvae may be functioning at their biological limit for ingesting food.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1003771512722

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6

Digitale Medien

Plant quality or quantity? Host exploitation strategies in three Chrysomelidae species associated with Asteraceae host plants (1999)

Obermaier, Elisabeth ; Zwölfer, Helmut

Springer

Entomologia experimentalis et applicata 92 (1999), S. 165-177

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ISSN: 1570-7458

Schlagwort(e): Chrysomelidae ; herbivory ; Asteraceae ; life history ; nitrogen ; plant quality ; season

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Phytophagous insects which feed on the leaves of herbaceous host plants have to adapt their life histories to the fact that protein nitrogen is usually highest in growing tissues in spring. We monitored field populations of larvae and adults of three chrysomelid species (Galeruca tanaceti (L.) (main host Achillea millefolium (L.) Yarrow), Cassida rubiginosa (Mueller) (main host Cirsium arvense (L.) Scop.) and Oreina luctuosa (Suffrian) (host Centaurea scabiosa (L.)) together with the amount of protein nitrogen of their food resources and host plant biomass. As expected, the development of host quality, measured as concentration of protein nitrogen, and host plant biomass showed inverse trends during the season. The euryphagous G. tanaceti attacks Achillea early and profits from high nitrogen concentrations in the leaves. Occasional overexploitations of local populations of Achillea are compensated by the capacity to move to other host species. In C. rubiginosa, a species with a host range restricted to the Cardueae, the main larval feeding activity is postponed to a period when the nitrogen content of the host leaves had dropped to 50% of its initial value, but when host plant biomass had increased by 30%. In the monophagous O. luctuosa the larval development is synchronized with a still later phase of host phenology, at which the nitrogen content is below 50% but plant biomass has reached its maximum. There seem to be selection factors, which oppose the use of high quality food in spring and which force the latter two species to postpone their larval development to a later time in the year. This could be caused by numerous factors like, for example, mean daytime temperature. Later in the season the larvae have to cope with the low quality of their host plants. They have, however, the advantage of large quantities of food available. A laboratory study with adults and mature larvae of O. luctuosa shows that this species can overcome low levels of protein nitrogen either by selecting younger leaves with higher nitrogen concentrations or by increasing the daily food consumption rate (RCR) on leaves with a low level of nitrogen and by a prolongation of the feeding period. In this way the larvae compensate the effect of lower daily growth rates (RGR) and a lower food conversion index (ECI) on poor food quality: Regardless of the level of protein nitrogen there was no statistically significant difference in total gain of weight during the third-instar feeding period and in the weight at the end of the third larval stage. The three investigated chrysomelids show that there exists a broad spectrum of adaptations to overcome the dilemma of variable food quality.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1003709622409

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7

Digitale Medien

Crystal structure of [Mn2(III)(salpa)2Cl2(H2O)2] (H2salpa = 1-(salicylaldeneamino)-3-hydroxypropane) (1999)

Zhang, Cun-Gen ; Sun, Jie ; Kong, Xiang-Fu ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 203-206

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ISSN: 1572-8854

Schlagwort(e): Manganese(III) ; Schiff base ; hydrogen bonding ; crystal structure ; Jahn-Teller distortion

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009526312170

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8

Digitale Medien

Molecular structure of ThBr4(DME)2 (DME = 1,2-dimethoxyethane) (1999)

Rabinovich, Daniel ; Scott, Brian L. ; Nielsen, Jon B. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 243-246

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ISSN: 1572-8854

Schlagwort(e): Thorium ; dimethoxyethane ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009542715804

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9

Digitale Medien

Synthesis and crystal structure of the copper(II) complex with novel Schiff base ligand: Cu(C8H7O2N)2(OH2) (1999)

Kong, Deyuan ; Xie, Yuli ; Xie, Yuyuan ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 295-298

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ISSN: 1572-8854

Schlagwort(e): Copper ; crystal structure ; synthesis ; Schiff base ligand

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009569701034

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10

Digitale Medien

Synthesis and crystal structures of quadruply carboxylate-bridged dimeric lanthanide(III) complexes of betaine (1999)

Yang, Guang ; Chen, Hui-An ; Zhou, Zhong-Yuan ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 309-316

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ISSN: 1572-8854

Schlagwort(e): Europium ; terbium ; betaine ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009573801943

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Digitale Medien

Copper, a chemical Janus: two copper(II) complexes with different ligand in one single crystal (1999)

Yan, Shiping ; Li, Chunhui ; Cheng, Peng ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1085-1088

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; copper(II) complexes ; dinuclear complexes

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009549506565

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12

Digitale Medien

Molecular gears: Structures of (9,10-triptyceno) crown ethers (1999)

Bryan, Jeffrey C. ; Sachleben, Richard A. ; Gakh, Andrei A. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 513-521

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ISSN: 1572-8854

Schlagwort(e): nanotechnology ; molecular devices ; triptycene ; crown ether ; crystal structure ; thallium

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009535632237

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The structure of bis(trimethylammonium) undecachlorotriantimonate(III) [(CH3)3NH]2Sb3Cl11 containing a novel antimony(III) anion (1999)

Bujak, Maciej ; Zaleski, Jacek

Springer

Journal of chemical crystallography 29 (1999), S. 555-560

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ISSN: 1572-8854

Schlagwort(e): alkylammonium chloroantimonates(III) ; hydrogen bonds ; disorder ; lone electron pair ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009592618124

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Crystal structure of the Λ-[4M] enantiomer of cis-diaqua-bis(1,3-dimethylpteridine-2,4(1H,3H)-dione-N5,O4) copper(II) perchlorate monohydrate (1999)

Hueso-Ureña, Francisco ; Jiménez-Pulido, Sonia B. ; Moreno-Carretero, Miguel N. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 571-574

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; complexes ; pteridine ; lumazine

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009548803103

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Synthesis and characterization of the dodecanuclear heterobimetallic Mo—Cu—S cage cluster: (Ph4P)2[{Mo2Cu2O2S2(S2)2}3(μ6-S)] (1999)

Lin, Ping ; Wu, Xintao ; Chen, Ling ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 581-586

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ISSN: 1572-8854

Schlagwort(e): dodecanuclear heterobimetallic ; molybdenum-copper cluster ; cage ; μ6-S ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009552904012

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Crystal and molecular structure of five coordinate copper(II) complex with 2,6-bis[1-(methoxycarbonylmethyl–hydrazono)ethyl] pyridine (1999)

Andjelković, K. ; Tellgren, R. ; Niketić, S.R. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 575-580

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ISSN: 1572-8854

Schlagwort(e): copper(II) complexes ; 2,6-diacetylpyridine derivative ; open-chain ligand ; crystal structure ; trigonal-bipyramidal geometry

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009500919942

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Synthesis and crystal structure of the heterometallic square-chain polythiometalate: {[W4Ag5S16]2 · [La(DEF)2(DMF)6][La(DEF)4(DMF)4]}n (1999)

Ling, Chen ; Xintao, Wu ; Ping, Lin

Springer

Journal of chemical crystallography 29 (1999), S. 629-633

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ISSN: 1572-8854

Schlagwort(e): heterometallic polymeric cluster ; polythiometalate ; synthesis ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009517423576

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Absolute configuration of C23H34O8Si, the product of an asymmetric synthesis involving the Rh(II) catalyzed reaction of a chiral vinyldiazomethane with methyl-2-methyl-3-furoate (1999)

Churchill, Melvyn Rowen ; Churchill, David George ; Ahmed, Gulzar ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 707-711

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ISSN: 1572-8854

Schlagwort(e): oxabicyclo[3.2.1]octadiene ; absolute configuration ; asymmetric synthesis ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009532106081

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Absolute configuration of C20H30O6Si, a species with a (1R,5R)-8-oxabicyclo[3.2.1]octa-2,6-diene core produced selectivity by the rhodium(II) octanoate catalyzed decomposition of a chiral vinyldiazomethane in the presence of furan (1999)

Churchill, Melvyn Rowen ; Churchill, David George ; Ahmed, Gulzar ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 713-717

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ISSN: 1572-8854

Schlagwort(e): oxabicyclo[3.2.1]octadiene ; absolute configuration ; asymmetric synthesis ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009584122919

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Synthesis and crystal structure of 1,1′-di(ethylpropionato)-2,2′-biimidazole, a macromolecular precursor (1999)

Barnett, W. Mark ; Baughman, Russell G. ; Collier, Harvest L. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 765-768

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ISSN: 1572-8854

Schlagwort(e): 2,2′-biimidazole ; diester ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009535501461

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The crystal and molecular structure of mercury(II) bis(isopropyl)dithiophosphate, Hg[S2P(OPri)2]2, revisited: new comments about its supramolecular self-organization (1999)

Casas, José S. ; Castellano, Eduardo E. ; Ellena, Javier ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 831-836

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ISSN: 1572-8854

Schlagwort(e): Hg coordination ; crystal structure ; organomercury derivatives

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009508122842

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Generation and intermolecular trapping of a cage-annulated cycloalkylidenecarbene (1999)

Bott, Simon G. ; Marchand, Alan P. ; Dong, Eric Zhiming

Springer

Journal of chemical crystallography 29 (1999), S. 329-333

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ISSN: 1572-8854

Schlagwort(e): Carbene ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009530019690

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Crystal structure of the addition compound of N,N′-bi(2-pyridylmethyl)-oxamide and complex of manganese with 1,10-phenanthroline (1999)

Liu, Bin ; Wang, Hong-Mei ; Yan, Shi-Ping ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 623-627

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; manganese complex ; disubsituted oxamide ; addition compound

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009565306738

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Synthesis and crystal structures of two potential gem-di(pyrazolyl)cycloalkane ligands, 1,1-di(pyrazol-1-yl)cyclohexane [C6H10(C3N2H3)2] and 1,1-di(pyrazol-1-yl)cyclopentane [C5H8(C3N2H3)2] (1999)

Churchill, Melvyn Rowen ; Churchill, David George ; Huynh, My Hang Vo ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 659-665

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ISSN: 1572-8854

Schlagwort(e): pyrazolyl derivative ; substituted cyclopentane ; substituted cyclohexane ; crystal structure ; bidentate ligand

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009515602446

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Synthesis and crystal structure of 4,5-(cis-cyclohexylenedithio)-1,3-dithiole-2-one (1999)

Bai, Jun-Feng ; Zuo, Jing-Lin ; Shi, Fa-Nian ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 719-723

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ISSN: 1572-8854

Schlagwort(e): synthesis ; crystal structure ; independent molecules

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009536206989

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The crystal and molecular structure of 2-S-methylthiouracil (1999)

Casas, J.S. ; Castellano, E.E. ; García-Tasende, M.S. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 725-727

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ISSN: 1572-8854

Schlagwort(e): 2-thiouracil derivatives ; crystal structure ; S-methyl-thiouracil ; hydrogen bonding ; structural methylation and metallation effects

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009588223827

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27

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Crystal structure and emission study of [(PPh3)2Cu(dmp)-O-(dmp)Cu(PPh3)2]2+ (dmp = 2,9-dimethyl-1,10-phenanthroline) (1999)

Lu, Juan ; Whittlesey, Bruce ; Casadonte, Dominick J.

Springer

Journal of chemical crystallography 29 (1999), S. 797-802

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ISSN: 1572-8854

Schlagwort(e): synthesis ; crystal structure ; Cu(I) complex ; μ-oxo-bis(2,9-dimethyl-1,10-phenanthroline) ; luminescence

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009595720117

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Structural analysis of tris(tetra-n-butylammonium) hexakisisothiocyanatoyttrate(III) (1999)

Kautz, Jason A. ; Mullica, Donald F. ; Farmer, J. Matt

Springer

Journal of chemical crystallography 29 (1999), S. 729-733

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; yttrium complexes ; isothiocyanate complexes ; octahedral coordination

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009540307898

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Synthesis and structure of bis(dibenzoylmethane)copper(II) (1999)

Ma, Bao-Qing ; Gao, Song ; Wang, Zhe-Ming ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 793-796

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ISSN: 1572-8854

Schlagwort(e): copper complex ; crystal structure ; dibenzoylmethane complex

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009543703278

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Crystal structure of [WBr2(CO)(PPh2Cy)2(η2-MeC2Me)]·CH2Cl2 (Cy = cyclohexyl) (1999)

Baker, Paul K. ; Drew, Michael G.B. ; Meehan, Margaret M.

Springer

Journal of chemical crystallography 29 (1999), S. 809-812

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ISSN: 1572-8854

Schlagwort(e): tungsten(II) ; dibromo ; carbonyl ; diphenylcyclohexylphosphine ; but-2-yne ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009599821025

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1-(Ethoxymethyl)-6-(phenylselenyl)-5-ethyl uracil: a nucleoside analog (1999)

Mazumder, G. ; De, M. ; Mukhopadhyay, A. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 837-839

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ISSN: 1572-8854

Schlagwort(e): acyclonucleoside analog ; 6-(phenyl selenyl) uracil derivative ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009560106913

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Mercury(II) halide complexes with N-donor organic ligands: crystal and molecular structure of HgI2R, R = 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, bipyridine (1999)

Freire, Eleonora ; Baggio, Sergio ; Baggio, Ricardo ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 825-830

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ISSN: 1572-8854

Schlagwort(e): mercury halides ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009556006004

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Synthesis and crystal structure of [WI(CO)(cis-dppen) η2-MeC2Me)2]I·CH2Cl2 {cis-dppen = bis(diphenylphosphino)ethene} (1999)

Baker, Paul K. ; Drew, Michael G.B. ; Latif, Latifah A.

Springer

Journal of chemical crystallography 29 (1999), S. 907-911

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ISSN: 1572-8854

Schlagwort(e): tungsten(II) ; Iodo ; carbonyl ; cis-bis(diphenylphosphino)ethene ; but-2-yne ; cationic ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009526012075

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4-(1,4-Dimethoxy-2-naphthyl)-4- hydroxycyclohexanone and its ethylene ketal (1999)

Wiedenfeld, David ; Xiao, Wu ; Gravelle, Philip W.

Springer

Journal of chemical crystallography 29 (1999), S. 955-959

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; intramolecular hydrogen bond ; 4-(1,4-dimethoxy-2-naphthyl)-4-hydroxycyclohexanone

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009538414801

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Crystal structure and physical characterization of neotame methanol solvate (1999)

Dong, Zedong ; Young, Victor G. ; Padden, Brian E. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 967-975

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ISSN: 1572-8854

Schlagwort(e): neotame ; crystal structure ; methanol solvate ; thermal analysis ; powder X-ray diffractometry ; 13C solid-state nuclear magnetic resonance spectroscopy

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009542515709

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A study of two geometric isomers of 1,1′-bi-3-cyanocyclohex-2-enylidene (1999)

Wang, Yonghui ; Doering, W.v.E. ; Staples, Richard J.

Springer

Journal of chemical crystallography 29 (1999), S. 977-982

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ISSN: 1572-8854

Schlagwort(e): cyano allyl radical ; thermal arrangement ; crystal structure ; isomer ; NMR, MM2

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009594532547

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X-ray crystal structure of tetraaquabis (xanthosinato)nickel(II) hexahydrate (1999)

Barrios, Francisca ; Salas, Juan M. ; Sánchez, M. Purificación ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1009-1013

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; nickel complex ; xanthosine

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009568616134

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Reactions of [Mn2(μ-pyS)2(CO)6] (pySH=pyridine-2-thiol) with triphenylphosphine (PPh3), diphenylphosphine (PHPh2) and bis(diphenylphosphino)methane (dppm): X-ray crystal structure of [Mn(pyS)(η1-dppm)2(CO)2] (1999)

Islam, Manwarul ; Johns, Caroline A. ; Kabir, Shariff E. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1001-1007

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ISSN: 1572-8854

Schlagwort(e): manganese ; pyridine-2-thiolate ; bis(diphenylphosphino)methane ; carbonyl ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009516632064

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Crystal structure of 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine (1999)

Biradha, Kumar ; Jenkins, Hilary ; Peori, M. Brad ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1037-1041

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; imidazolidine ; triazene ; bis-triazene ; methoxy substituent ; π-π stacking

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009529002022

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Crystal structure of 2-{(R)-1-hydroxy-1-[(2S)-1-tritylaziridin-2-yl] methyl}acrylate and spectroscopic properties of the (R,S) and (S,S) stereoisomers (1999)

Moers, Frans G. ; Nayak, Sandip K. ; de Gelder, René ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1053-1056

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; tritylaziridine ; acrylate ; spectroscopic features

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009585119769

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Absolute configuration of C27H41NO8Si, the diastereoselective product of the rhodium(II) octanoate catalyzed decomposition of a chiral vinyldiazomethane in the presence of 2-acetylpyrrole: A structural study rendered difficult by disorder of a “heavy” atom (1999)

Churchill, Melvyn Rowen ; Churchill, David George ; Matasi, Julius J. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1061-1066

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ISSN: 1572-8854

Schlagwort(e): absolute configuration ; asymmetric synthesis ; azabicyclo[3.2.1]octadiene ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009589220678

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Crystal structure of [Co(bipy)(maleato) (H2O)3]·H2O (bipy = 2,2′-bipyridine) (1999)

Zhang, Cun-Gen ; Leng, Yong-Jun ; Ma, Zi-Feng ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1081-1084

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ISSN: 1572-8854

Schlagwort(e): cobalt(II) ; bipyridine ; maleato ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009597422495

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Crystal and molecular structure determination, TGA, DTA, and infrared and Raman spectra of rubidium nitroprusside monohydrate, Rb2[Fe(CN)5NO]·H2O (1999)

Soria, D.B. ; Piro, O.E. ; Castellano, E.E. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 75-80

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ISSN: 1572-8854

Schlagwort(e): Rubidium nitroprusside monohydrate ; crystal structure ; properties

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009575415668

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Crystal structure of methyl trans-3-[(2-(methoxycarbonyl)phenyl)sulfinyl]acrylate: a product resulting from trapping of a sulfenic acid by methyl propiolate (1999)

Mitra, Kaushik ; Barnes, Charles L. ; Gates, Kent S.

Springer

Journal of chemical crystallography 29 (1999), S. 1133-1136

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; methyl propiolate ; sulfenic acid ; vinyl sulfoxide ; leinamycin

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009518127038

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9[1-(2-Hydroxy ethoxy)-3-hydroxy propyl] guanine: a nucleoside analog (1999)

Mazumder, G. ; De, M. ; Mukhopadhyay, A. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1137-1139

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ISSN: 1572-8854

Schlagwort(e): acyclic nucleoside analog ; acyclovir ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009570111108

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Structure, thermal behavior, and IR investigation of a new organic sulfate (1999)

Guerfel, Taha ; Bdiri, Mohamed ; Jouini, Amor

Springer

Journal of chemical crystallography 29 (1999), S. 1205-1210

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ISSN: 1572-8854

Schlagwort(e): organic sulfate ; crystal structure ; DTA/TG/DSC ; vibrational spectra

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009559718165

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Structure of de-oxy corticosterone-21-hemisuccinate (1999)

Dey, Raja ; Roychowdhury, Sandhya ; Roychowdhury, P.

Springer

Journal of chemical crystallography 29 (1999), S. 1265-1269

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; corticosteroid ; de-oxy corticosterone-21-hemisuccinate

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009504923424

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Synthesis and crystal structure of 1-phenyl-3-methylthio-4-imino-5-allyl-pyrazolo[3,4-d]pyrimidine (1999)

Chen, Weiqiang ; Weng, Linhong ; Jin, Guiyu

Springer

Journal of chemical crystallography 29 (1999), S. 1291-1293

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; pyrazolo[3,4-d]pyrimidine ; fungicidal activity

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009565209312

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Crystal structure of [Mn(II)(phen)(ClCH2COO)2]n (phen = 1,10−phenanthroline) (1999)

Zhang, Cun-Gen ; Sun, Jie ; Kong, Xiang-Fu ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 199-201

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ISSN: 1572-8854

Schlagwort(e): Manganese (II) ; phenanthroline ; polymeric complex ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009574128099

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Synthesis of a new dibenzo-14-crown-4 lariat ether and structure of its sodium perrhenate complex (1999)

Bryan, Jeffrey C. ; Sachleben, Richard A.

Springer

Journal of chemical crystallography 29 (1999), S. 1255-1259

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ISSN: 1572-8854

Schlagwort(e): crown ether ; crystal structure ; lariat ; sodium

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009552806586

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Structure of de-oxy corticosterone (4-pregnen-21-ol-3,20-dione) (1999)

Dey, Raja ; Roychowdhury, Sandhya ; Roychowdhury, P. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1271-1275

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; pregnen ; progestin ; 4-pregnen-21-ol-3,20-dione

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009556907495

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Polymeric copper(II)-orotato complexes, [(C5H2N2O4)Cu(H2O)2]n (1999)

Ha, Tam T.B. ; Larsonneur-Galibert, Anne Marie ; Castan, Paule ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 565-569

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ISSN: 1572-8854

Schlagwort(e): orotic acid complex ; crystal structure ; copper(II) complex

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009596719033

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X-ray crystal structure and spectroscopy of a pseudo-square pyramidal Cu(II) complex, trans-dinitratotetrakis (trans-4-styrylpyridine)copper(II) (1999)

Karunakaran, Chandran ; Thomas, K.R. Justin ; Shunmugasundaram, Arunachalam ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 413-420

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ISSN: 1572-8854

Schlagwort(e): pseudo-square pyramidal Cu(II) complex ; trans-4-styrylpyridine ; crystal structure ; IR, electronic, and EPR spectra

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009510910121

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Molecular structure of 1-phenyl-1-dimethylamino-4,4-bis(trimethylsilyl)-2-aza-3λ3-phosphabutadiene-1,3 (1999)

Chernega, Alexander N. ; Rusanov, Eduard B. ; Povolotskii, Mark I.

Springer

Journal of chemical crystallography 29 (1999), S. 475-480

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; ab initio calculations ; conjugation ; phosphabutadienes

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009527413755

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Synthesis and crystal structure of 1-(4-bromobenzyl)-4-methyl-2,6,7-trioxabicyclo[2.2.2]octane (1999)

Løiten, Marianne Sveaas ; Gløgård, Christian ; Klaveness, Jo ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 493-496

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ISSN: 1572-8854

Schlagwort(e): contrast agents ; crystal structure ; ortho ester

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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)°.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009531514664

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Structure refinement and Raman spectrum of silver azide (1999)

Guo, Guo-Cong ; Wang, Quan-Ming ; Mak, Thomas C.W.

Springer

Journal of chemical crystallography 29 (1999), S. 561-564

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; Raman spectrum ; silver azide ; azide

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009544702195

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Structure of adamantan-1-ammonium 1-adamantanecarboxylate (1999)

Mullica, Donald F. ; Scott, T. Gordon ; Farmer, J. Matt ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 845-848

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; centrosymmetric ; aminoadamantane derivative ; antiviral ; dispiro compound

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009564307821

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Structural characterization of a series of cyclohexaphosphates: M0.5((C6H5CH2)2NH2)5P6O18·H2O (M = Co, Cu, Cd) (1999)

Abid, S. ; Rzaigui, M. ; Bagieu-Beucher, M.

Springer

Journal of chemical crystallography 29 (1999), S. 891-899

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ISSN: 1572-8854

Schlagwort(e): cyclohexaphosphates ; organometallic compound ; crystal growth ; X-ray diffraction ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009521911166

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The structural characterization of YbI2(DME)3 (1999)

Hibbs, David E. ; Jones, Cameron ; Richards, Anne F.

Springer

Journal of chemical crystallography 29 (1999), S. 1107-1110

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; ytterbium ; lanthanide ; coordination complex

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009557708382

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Crystal structure of phenyl-substituted cyclopentenes (1999)

Benetollo, Franco ; Busetti, Vilma ; Marcuzzi, Franco

Springer

Journal of chemical crystallography 29 (1999), S. 1127-1132

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; phenyl-substituted cyclopentenes

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009566010200

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61

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Self-assembly in transition metal complexes: structural characterization of a copper histamine nitrate [Cu(II)(him)2(NO3)2] (1999)

Zhang, Cun-Gen ; Duan, Chun-Ying ; Hu, Qiao ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1153-1155

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ISSN: 1572-8854

Schlagwort(e): copper (II) ; histamine ; self-assembly ; crystal structure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009574230460

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62

Digitale Medien

14-Hydroxy-14-phenyldibenzo[a,j]xanthene as a lattice host: crystal and molecular structure of its (1:1) complex with diethyl ether (1999)

Barton, Benita ; Caira, Mino R. ; McCleland, Cedric W. ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 1179-1186

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ISSN: 1572-8854

Schlagwort(e): xanthenol ; complex ; crystal structure ; H-bonding

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009599432277

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63

Digitale Medien

Synthesis, crystal structure and properties of square-planar acetato{[(4-methylimidazol-5-yl)methylene]histamine} copper(II) perchlorate (1999)

Long, La-Sheng ; Tong, Ye-Xiang ; Chen, Xiao-Ming ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 409-412

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ISSN: 1572-8854

Schlagwort(e): copper(II) ; Schiff base ; polymidazole ; crystal structure ; properties

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009558826050

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64

Digitale Medien

Crystal and molecular structure of the symmetrical bidentate ligand 3,3-di(1-pyrazolyl)pentane, CH3CH2C(C3H3N2)2CH2CH3 (1999)

Churchill, Melvyn Rowen ; Churchill, David George ; Huynh, My Hang Vo ; [weitere]

Springer

Journal of chemical crystallography 29 (1999), S. 463-467

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ISSN: 1572-8854

Schlagwort(e): pyrazolyl derivative ; substituted pentane ; crystal structure ; bidentate ligand

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009523312846

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65

Digitale Medien

Crystal structure and conformation of frentizole, [1-(6-methoxy-2-benzothiazolyl)-3-phenylurea, an antiviral agent and an immunosuppressive drug (1999)

Rooth, Walter ; Srikrishnan, Thamarapu

Springer

Journal of chemical crystallography 29 (1999), S. 1187-1192

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ISSN: 1572-8854

Schlagwort(e): crystal structure ; Frentizole ; immunomodulator ; structure-function relationship

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009551516348

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66

Digitale Medien

Crystal structure of quinestrol hemiethanolate (1999)

Steiner, Thomas

Springer

Journal of chemical crystallography 29 (1999), S. 355-358

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ISSN: 1572-8854

Schlagwort(e): Quinestrol ; sex steroid ; alkyne ; crystal structure ; solvent inclusion ; hydrogen bonding

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1009590305578

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67

Digitale Medien

Integrity and Structural Characteristics of the M6E8 (E=S, Se, Te) Cluster Core: Syntheses and Structures of [Co6S8(PR3)6] n+ (R=Me2Ph, n=1; R=OMe, n=0) (1999)

Kang, Bei-Sheng ; Wen, Ting-Bin ; Yu, Xiang-Yang ; [weitere]

Springer

Journal of cluster science 10 (1999), S. 429-443

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ISSN: 1572-8862

Schlagwort(e): Cluster core M6E8 ; structural characteristics ; crystal structure ; hexacobalt cluster complex ; phosphine ; sulfide bridging

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau , Physik

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1022681127451

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68

Digitale Medien

Radiation-induced rhombencephalopathy (1999)

Cirafisi, C. ; Verderame, F.

Springer

Italian journal of neurological sciences 20 (1999), S. 55-58

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ISSN: 1126-5442

Schlagwort(e): Key words Rhombencephalopathy ; Radionecrosis ; Magnetic resonance imaging ; Hyperbaric oxygen ; Heparin ; Buspirone

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s100720050011

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69

Digitale Medien

Psychiatric symptoms as late onset of Wilson's disease: neuroradiological findings, clinical features and treatment (1999)

Keller, R. ; Torta, R. ; Lagget, M. ; [weitere]

Springer

Italian journal of neurological sciences 20 (1999), S. 49-54

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ISSN: 1126-5442

Schlagwort(e): Key words Hepatolenticular degeneration ; Affective disorders ; Magnetic resonance imaging ; Antidepressive agents ; Interpersonal psychotherapy

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s100720050010

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70

Digitale Medien

Soft-tissue signs of the upper extremity revisited: radiologic and magnetic resonance imaging correlation (1999)

Yu, J. S.

Springer

Emergency radiology 6 (1999), S. 282-289

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ISSN: 1438-1435

Schlagwort(e): Key words Radiology ; Computed tomography ; Magnetic resonance imaging ; Soft-tissue sign ; Arm

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101400050069

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71

Digitale Medien

MR imaging of a severe cervical fracture-dislocation after traumatic delivery (1999)

Fordham, L. A. ; Bell, James ; Chung, Charles J. ; [weitere]

Springer

Emergency radiology 6 (1999), S. 143-145

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ISSN: 1438-1435

Schlagwort(e): Key words Spinal cord ; Birth injury ; Magnetic resonance imaging

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101400050040

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72

Digitale Medien

Bifocal temporal ganglioglioma (1999)

Paduch, Thomas ; Baborie, Atikullah ; Krauss, J. K.

Springer

Neurosurgical review 22 (1999), S. 112-116

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ISSN: 1437-2320

Schlagwort(e): Key words Ganglioma ; Brain tumor ; Magnetic resonance imaging ; Epilepsy

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101430050042

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73

Digitale Medien

Combining steady-state constructive interference and diffusion-weighted magnetic resonance imaging in the surgical treatment of epidermoid tumors (1999)

Murakami, Nobuya ; Matsushima, Toshio ; Kuba, Hiroshi ; [weitere]

Springer

Neurosurgical review 22 (1999), S. 159-162

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ISSN: 1437-2320

Schlagwort(e): Key words Cerebellopontine angle ; Constructive interference in steady-state imaging ; Diffusion-weighted imaging ; Epidermoid tumor ; Magnetic resonance imaging ; Surgical treatment

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101430050055

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74

Digitale Medien

Solid cerebral echinococcosis mimicking a primary brain tumor (1999)

Nanassis, Kimon ; Alexiadou-Rudolf, C. ; Tsitsopoulos, Philippos ; [weitere]

Springer

Neurosurgical review 22 (1999), S. 58-61

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ISSN: 1437-2320

Schlagwort(e): Key words Brain tumor ; Cerebral hydatidosis ; Chitinoma ; Echinococcosis ; Magnetic resonance imaging

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101430050011

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75

Digitale Medien

FTIR spectroscopic evidence of formation of geminal dinitrogen species during the low-temperature N2 adsorption on NaY zeolites (1999)

Hadjiivanov, Konstantin ; Knözinger, Helmut

Springer

Catalysis letters 58 (1999), S. 21-26

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ISSN: 1572-879X

Schlagwort(e): adsorption ; adsorption isotherms ; dinitrogen ; FTIR spectroscopy ; geminal species ; NaY ; nitrogen ; zeolites

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract Adsorption of N2 on NaY zeolites at 85 K and equilibrium pressures higher than 1 kPa results in the formation of geminal dinitrogen complexes characterized by an IR band at 2333.5 cm−1 (2255.4 cm−1 after adsorption of 15N2). With decreasing equilibrium pressure the complexes tend to loose one N2 ligand, thus forming linear species characterized by an IR band at 2336.8 cm−1 (2258.7 cm−1 after adsorption of 15N2). All species disappear completely after evacuation. Co-adsorption of N2 and CO revealed that the dinitrogen complexes are formed on Na+ cations. The changes in the concentrations of the linear and geminal N2 species with the changes in the equilibrium pressure are excellently described by equations of adsorption isotherms proposed earlier for mono- and di-carbonyls.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1019040825491

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76

Digitale Medien

Pure and Binary Gas Adsorption Equilibria and Kinetics of Methane and Nitrogen on 4A Zeolite by Isotope Exchange Technique (1999)

Mohr, R.J. ; Vorkapic, D. ; Rao, M.B. ; [weitere]

Springer

Adsorption 5 (1999), S. 145-158

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ISSN: 1572-8757

Schlagwort(e): kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Physik , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1008917308002

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77

Digitale Medien

Effects of retinol on follicular porcine thyrocytes in culture (1999)

Fröhlich, E. ; Wahl, Richard

Springer

Journal of molecular medicine 77 (1999), S. 189-192

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ISSN: 1432-1440

Schlagwort(e): Key words Thyroid ; Cell culture ; Retinoids ; Apoptosis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Retinoids influence proliferation and differentiation in transformed thyroid cell lines. Retinoids are able to damage cells by destabilizing lysosomal membranes and induce apoptosis in certain cell lines. In normal thyrocytes retinol modulates iodine metabolism. At concentrations higher than 50×10–6 M retinoids are cytotoxic for normal (not transformed) thyroid cells. The mechanism of this cytotoxicity is unknown. We studied the effect of 7–80×10–6 M retinol on porcine follicular thyrocytes in culture. In order to differentiate between membrane-destabilizing effects and apoptosis we investigated cultures after incubation with retinol by light- and electron-microscopy and by labeling of potential nicks in the DNA helix by terminal deoxynucleotidyltransferase-dUTP mediated DNA nick end labeling. We conclude that the observed cytotoxicity is caused mainly by the induction of apoptosis.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001090050334

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78

Digitale Medien

Molecular pathogenesis of chronic lymphocytic leukemia: factors and signaling pathways regulating cell growth and survival (1999)

Meinhardt, Gerold ; Wendtner Clemens-M. ; Hallek, M.

Springer

Journal of molecular medicine 77 (1999), S. 282-293

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ISSN: 1432-1440

Schlagwort(e): Key words Chronic lymphocytic leukemia ; Apoptosis ; Cell growth ; Signaling ; Review

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Chronic lymphocytic leukemia is a malignant disease characterized by clonal expansion of relatively mature B-lymphocytes with a high percentage of cells arrested in the nonproliferative G0/G1 cell cycle phase. Possibly reflecting the clinical heterogeneity observed in patients, various signaling pathways may become affected during the initiation and course of this disease. This review discusses frequent alterations concerning proliferative, differentiation-inducing, and apoptotic pathways elucidated in the recent years that have improved our understanding of this disease.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001090050351

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79

Digitale Medien

Analysis of otolith chemistry in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS (1999)

Patterson, H. M. ; Thorrold, S. R. ; Shenker, J.M.

Springer

Coral reefs 18 (1999), S. 171-178

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ISSN: 1432-0975

Schlagwort(e): Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Geologie und Paläontologie

Notizen: Abstract We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s003380050176

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Digitale Medien

Effects of doxorubicin, mitomycin C, and ethanol on Hep-G2 cells in vitro (1999)

Castañeda, F. ; Kinne, R. K. H.

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 1-8

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ISSN: 1432-1335

Schlagwort(e): Key words Cell proliferation ; Apoptosis ; Cell death ; Cultured cells ; Hepatocellular carcinoma

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract There are conflicting results for experiments aimed at determining whether anticancer drug therapy of human hepatocellular carcinoma prolongs the survival rate effectively. The purpose of this study was to assess the effect of low concentrations of doxorubicin, mitomycin C, and ethanol on cell replication (cell number and proliferation), and cell apoptosis of cultured human hepatocellular carcinoma (Hep-G2) cells. After 1 day of exposure doxorubicin inhibited cell replication initially by 72%, but a partial recovery of the cell number was observed. Mitomycin C inhibited to the same extent but without recovery. Ethanol reduced the cell number even further, the maximum inhibition (12 days after exposure) being 96.4%. After 3 days of exposure all three agents stopped cell replication at a level of 2%–4% of the control (P 〈 0.001). Cell apoptosis was activated most strikingly by mitomycin C (5 μg/ml) after 1 day of exposure and by ethanol (150 μl/ml) after 3 days of exposure. Two-way repeated-measures analysis of variance showed statistically significant differences, with ethanol being the most significant followed by mitomycin C doxorubicin, and the control (P 〈 0.01). Thus, a low dose of ethanol combined with an exposure time of up to 3 days appears to be an effective regimen to control growth of human hepatocellular carcinoma cells in vitro. The strong induction of apoptosis by ethanol might be of additional benefit for a local application in vivo.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050235

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81

Digitale Medien

Basic fibroblast growth factor potentiates cisplatinum-induced cytotoxicity in MCF-7 human breast cancer cells (1999)

Fenig, E. ; Livnat, T. ; Sharkon-Polak, S. ; [weitere]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 556-562

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ISSN: 1432-1335

Schlagwort(e): Key words Basic fibroblast growth factor ; Cisplatinum ; Apoptosis ; Bcl-2 ; MCF-7

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Basic fibroblast growth factor (bFGF) is a classical mitogen in fibroblasts and endothelial cells. Our previous studies have demonstrated that bFGF inhibits the growth of MCF-7 human breast cancer cells. The aim of the present study was to examine the effect of bFGF on cis-diamminedichloroplatinum(cisplatin)-induced cytotoxicity in MCF-7 breast cancer cells as compared to normal endothelial cells. MCF-7/NCF cells transduced with a vector expressing the bFGF gene and overexpressing its product, and MCF-7/N2 cells transduced with the backbone vector were incubated with a combination of bFGF and cisplatin for 5 days; results were compared with those obtained with bovine aortic endothelial cells. Cell proliferation was assessed with the sulforhodamine B colorimetric cytotoxicity assay. Apoptosis was quantitatively determined by flow-cytometric analysis for DNA damage and the apoptotic death assay for DNA fragmentation, and qualitatively by electron microscopy. Reverse transcriptase/polymerase chain reaction analysis and an enzyme immunoassay were used to determine the mRNA and protein level, respectively, of the anti-apoptotic bcl-2 gene product. We found that bFGF enhanced cisplatin-induced cytotoxicity in MCF-7 breast cancer sublines. bFGF enhanced proliferation of normal endothelial cells and did not increase cisplatin-induced cytotoxicity. This effect was accompanied by down-regulation of the anti-apoptotic protooncogene bcl-2 and the enhancement of cisplatin-induced apoptosis. We suggest that the improved understanding of the role of bFGF in the differential modulation of the response of breast cancer and normal endothelial cells to chemotherapy may enable active intervention to alter the therapeutic ratio favorably in breast cancer patients.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050316

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82

Digitale Medien

Induction of apoptosis in metastatic foci from human gastric cancer xenografts in nude mice and reduction of circulating tumor cells in blood by 5-FU and 1-hexylcarbamoyl-5-fluorouracil (1999)

Nakanishi, Hayao ; Abe, Atsushi ; Inada, Ken-ichi ; [weitere]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 660-668

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ISSN: 1432-1335

Schlagwort(e): Keywords Chemosensitivity ; Human gastric carcinoma ; Micrometastasis ; Apoptosis ; Circulating tumor cells ; Fluoropyrimidine

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Antimetastatic effects of 5-FU and its derivative, 1-hexylcarbamoyl-5-fluorouracil (HCFU) on human gastric cancer micrometastasis and their mode of action were evaluated, using a spontaneous lung metastasis model (HY-1) in nude mice. Metastases were first detected in the lung from 4 weeks after subcutaneous transplantation, growing intravascularly and forming micrometastases at 100% incidence by 6 weeks after implantation. Lung metastasis in mice bearing subcutaneous tumors was significantly inhibited by HCFU at doses of 100–150 mg kg−1 day−1 without severe toxic side-effects, when orally administered three times per week either from week 4 or week 6 to 9 weeks after implantation. Spontaneous lung metastasis was also inhibited by the administration of 5-FU, but to lesser extent than with HCFU at equimolar low doses. Apoptosis within primary tumors and lung metastatic foci, as detected by the terminal-deoxynucleotidyltransferase-mediated dUTP nick-end labeling method, was found to be significantly enhanced by HCFU as well as 5-FU administration at doses of more than 100 mg kg−1 day−1 and 50 mg kg−1 day−1 respectively. However, proliferating activity of the metastatic foci, as evaluated by MIB-1 immunostaining, was not significantly suppressed by HCFU or 5-FU treatment. Furthermore, polymerase chain reaction analysis using human specific primers for the β-globin gene, which proved to be capable of detecting 10 tumor cells/ml mouse blood, revealed that circulating tumor cells in the peripheral blood of mice bearing primary tumors were reduced by HCFU or 5-FU administration. These results indicate that circulating tumor cells in blood and micrometastases in the lung are sensitive to these chemotherapeutic agents, and suggest that the anti-metastatic effect of these agents is mediated, at least in part, by enhanced apoptosis rather than by inhibition of cell proliferation.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050331

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83

Digitale Medien

The role of insulin-like growth factor I and its receptor in cell growth, transformation, apoptosis, and chemoresistance in solid tumors (1999)

Grothey, A. ; Voigt, W. ; Schöber, C. ; [weitere]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 166-173

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ISSN: 1432-1335

Schlagwort(e): Key wordsIGF ; Apoptosis ; Transformation ; Chemosensitivity ; Signaling

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Insulin-like growth factor I (IGF-I) exerts pleiotropic effects on mammalian cells via stimulation of its receptor (IGF-IR), a receptor tyrosine kinase. In vivo, IGF-I acts both as a local tissue growth factor and as a circulating hormone. In oncological research, IGF-I has received increased attention as the activated IGF-I/IGF-IR system displays mitogeneic, transforming, and anti-apoptotic properties in various cell types by stimulating distinct intracellular signaling pathways. Recent data suggest that the anti-apoptotic effect of IGF-I may mediate decreased sensitivity to chemotherapeutic drugs in vitro and in vivo. Thus, targeting the IGF-I/IGF-IR system could serve as an approach to overcome clinical drug resistance in certain tumors.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050259

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84

Digitale Medien

Subnuclear distribution of DNA topoisomerase I and Bax protein in normal and xeroderma pigmentosum fibroblasts after irradiation with UV light and c rays or treatment with topotecan (1999)

Thielmann, Heinz Walter ; Popanda, Odilia ; Staab, Hans-Jürgen

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 193-208

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ISSN: 1432-1335

Schlagwort(e): Key words Immunohistochemistry ; DNA repair ; Radiation-inducible response ; Apoptosis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Immunohistochemical methods were used to determine abundance and subnuclear distribution of DNA topoisomerase I and the Bax protein in normal and excision-repair-deficient xeroderma pigmentosum (XP) fibroblasts after irradiation of cells with γ rays or UV light, or exposure to the topoisomerase I inhibitor topotecan. DNA topoisomerase I and Bax were monitored using antisera raised against the human proteins. In addition, topoisomerases IIα and IIβ were made visible with specific antibodies. In untreated cells, DNA topoisomerase I was found to occur in the cytoplasm and in nucleoli. Irradiation with γ rays (2–12 Gy) or UV light (0.3–1.2 mW/cm2) changed the staining pattern in nuclei such that a multitude of small topoisomerase-I-rich centers occurred, which were evenly distributed over the karyoplasm. Simultaneously nucleoli disintegrated. Treatment of fibroblasts with topotecan (6–100 μM concentrations) resulted in similar alterations although the changes were much more pronounced. Combinations of topotecan and γ irradiation caused additive effects. We conclude that the increase in the number of topoisomerase-I-positive spots and the high fluorescence intensity of the latter may reflect three biological processes: (i) enhanced transcriptional activity (e.g. of DNA damage response genes), (ii) tagging of damaged DNA sites for repair, or (iii) initiation of apoptosis. In separate assays using normal and XP cells, a dose-dependent increase in protein reacting with Bax antibody was observed in nuclei, following treatment with γ rays or topotecan. In addition, topotecan induced a netlike arrangement of this Bax protein in nuclei. The meshes of the net structure resembled vesicles. DNA staining with 4′,6-diamidino-2-phenylindole dihydrochloride revealed that the vesicle-type structures contained DNA. Upon further incubation with topotecan, cells showing the netlike Bax arrangement eventually died. We conclude that topotecan-induced changes made visible by nuclear Bax protein are associated with apoptosis. XP cells, when treated with topotecan, responded more readily than normal cells with both an increase in nuclear Bax protein and rearrangement of Bax, indicating that UV repair functions may be required to process DNA damage inflicted by topotecan. Monitoring of DNA topoisomerases IIα and IIβ in γ-irradiated cells with antibodies revealed a dramatic increase in the IIα form and a redistribution of the IIβ form representing fragmentation of nucleoli.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050263

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85

Digitale Medien

The influence of the p53 gene on the in vitro chemosensitivity of colorectal cancer cells (1999)

Zheng, Minhua ; Wang, Hao ; Zhang, Haobo ; [weitere]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 357-360

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ISSN: 1432-1335

Schlagwort(e): Key words Colorectal neoplasms ; Apoptosis ; Chemosensitivity ; p53 gene

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Purpose : The p53 gene is considered one of the most important in the control of apoptosis, and its mutations have a close relationship with chemosensitivity. The aim of this work was to investigate the role of p53 in the apoptosis of colorectal cancer cells in vitro, induced by 5-fluorouracil (5-FU) and hydroxy-camptothecin (HCPT). Methods : A total of 39 colorectal cancer samples from patients were treated in vitro with 5-FU (10 μg/ml), 5-FU (10 μg/ml) + leucovorin (5 μg/ml), HCPT (0.1 μg/ml) and HCPT (0.1 μg/ml) + Salvia mitorrhiza (6 μl), using an in situ terminal deoxynucleotidyltransferase assay to detect chemosensitivity. p53 gene mutations from tumor DNA were detected, after amplification by the polymerase chain reaction of exons 5–8, by non-radioactive single-strand conformation polymorphism. Results : p53 gene mutations were observed in 43.6% (17/39) of colorectal carcinomas, when the terminal deoxynucleotidyltransferase assay was used to detect the tumor apoptotic rate. Cells with mutated p53 had lower chemosensitivity than those without (p 〈 0.01). Conclusion : Routine assessment of p53 status may be helpful in selecting patients with the wild-type p53 gene, who have a predictably better response to chemotherapy.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050286

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86

Digitale Medien

Inhibition of epidermal-growth-factor-receptor-dependent signalling by tyrphostins A25 and AG1478 blocks growth and induces apoptosis in colorectal tumor cells in vitro (1999)

Partik, Gerda ; Hochegger, Karin ; Schörkhuber, Michaela ; [weitere]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 379-388

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ISSN: 1432-1335

Schlagwort(e): Key words EGF receptor signalling ; Tyrphostin ; Apoptosis ; Colon cancer

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Growth effects of tyrphostins A25 and AG1478 on colorectal tumor cells were studied to explore therapeutic potential. Cell number, DNA synthesis and apoptotic index were measured as growth parameters and cell-death-associated proteins Bcl-2 and Bak and protein phosphorylation were analyzed. Both tyrphostins inhibited DNA synthesis and induced apoptosis in tumor cell cultures with different patterns of activity. A25 displayed strong selectivity for the cell lines expressing high levels of epidermal growth factor (EGF), HT29/HI1 and SW480. Inhibition of DNA synthesis was efficient in all cells except T84, and the apoptotic index increased two- to fivefold. By contrast, AG1478 was highly effective in all cell lines. In addition, it caused cell loss in VACO235 adenoma cells at concentrations lower than those necessary to inhibit BrdU incorporation, reflecting preferential retention of cells actively synthesizing DNA. Induction of apoptosis was more efficient with AG1478 than with A25 (tenfold in VACO235). Insulin-like growth factor (IGF1) did not rescue cells exposed to A25 or to high concentrations of AG1478, but was effective with suboptimal amounts of AG1478. Both compounds inhibited phosphorylation of the EGF receptor as well as additional proteins. AG1478 induced expression of Bak and down-regulated Bcl-2. In summary, tyrphostins may provide alternatives for colorectal tumor treatment. Their broader range of activities and the lower susceptibility to interactions with IGF1 can be an advantage over receptor antibodies.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050290

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Digitale Medien

Growth inhibition of experimental pancreatic cancers and sustained reduction in epidermal growth factor receptors during therapy with hormonal peptide analogs (1999)

Szepesházi, Karoly ; Halmos, Gabor ; Schally, Andrew V. ; [weitere]

Springer

Journal of cancer research and clinical oncology 125 (1999), S. 444-452

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ISSN: 1432-1335

Schlagwort(e): Key words Experimental pancreatic cancer ; Hormonal therapy ; Bombesin antagonist ; Somatostatin analog ; LH-RH antagonist ; EGF receptor ; Apoptosis ; AgNOR

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Reduction in receptors for epidermal growth factor (EGF) in cancers appears to be one of the principal mechanisms through which peptide hormone analogs can inhibit tumor growth. In this study, hamsters with nitrosamine-induced pancreatic cancers were treated for 8 weeks with bombesin/gastrin-releasing peptide (GRP) antagonist RC-3095, somatostatin analog RC-160 or the luteinizing hormone-releasing hormone antagonist Cetrorelix, using sustained delivery systems releasing 20, 35 and 20 μg analog/ day respectively. To establish the pattern of changes in the number and affinity of EGF receptors on tumors, groups of animals were sacrificed at regular intervals during therapy. Chronic treatment with RC-3095 or Cetrorelix resulted in an early (day 10) and sustained reduction (71% or 69% respectively) in EGF receptors on pancreatic tumors. In contrast, RC-160 decreased receptor concentration by 60% only after 20 days. Among the histological characteristics of proliferation, the decrease in argyrophilic nucleolar organizer regions, but not apoptotic and mitotic indices, showed a correlation with the fall in EGF receptors. The concentration of the receptors returned to the control level 4 days after cessation of chronic treatment with RC-3095. The effect of single injections of RC-3095, RC-160 and Cetrorelix on EGF receptors was also investigated. RC-160 decreased the number of EGF receptors on pancreatic cancers by 31% 3 h after administration, but the receptors had returned to normal level at 6 h. RC-3095 and Cetrorelix caused a 67% and 59% decline, respectively, in EGF receptors only 6 h after injection and the concentration of receptors remained low for 24 h. Thus, the pattern of down-regulation of EGF receptors in pancreatic cancers appears to depend on the peptide used for therapy. Since the antitumor effect may be the result of the fall in EGF receptors in cancers, information on the time course of changes in these receptors during treatment with these analogs may lead to an improvement in therapeutic regimens.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s004320050301

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88

Digitale Medien

Charakterisierung der Lymphozytensubpopulationen bei Patienten mit Ataxia teleangiectatica (1999)

Kappenhagen, Nicola ; Royer, Nathalie ; Scheuplein, Meike ; [weitere]

Springer

Monatsschrift Kinderheilkunde 147 (1999), S. 927-931

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ISSN: 1433-0474

Schlagwort(e): Schlüsselwörter Ataxia teleangiectatica ; Immunfunktionsstörung ; Lymphozytensubpopulationen ; Apoptose ; CD45RO ; CD45RA ; Key words Ataxia teleangiectasia ; Immunodeficiency ; Lymphocyte subset ; Apoptosis ; CD45RO ; CD45RA

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: Summary Background: Can a characterisation of the lymphocyte subset in patients with ataxia teleangiectasia offer an explanation for the cellular defect of their immunfunction? Methods: In ten patients with ataxia teleangiectasia and a corresponding control group of individuals of similar age and sex, immunophenotyping was carried out by means of flow cytometric analysis and the use of monoclonal antibodies. Results: Patients with ataxia teleangiectasia showed a reduction of the number of T-cells with a decrease in the T-helper cell subset (CD3: 990/µl, p〈0.0005 and CD4: 568/µl, p〈0.0005). The number of B-cells was low (CD19: 39/µl, p〈0.005). Moreover, there was an increase in highly activated T-lymphocytes which can be seen from a higher percentage of the HLA-DR- and CD45RO-expression in patients with ataxia teleangiectasia compared to the individuals of the control group (HLA-DR: 57%, p〈0.0005 and CD45RO: 82%, p〈0.001). At the same time, the expression of CD95 (Fas/AP01) was clearly increased (CD95: 74%, p〈0.001). Interpretation: The lymphocyte subset of the patients suffering from ataxia teleangiectasia shows a significant decrease of the B- and T-cell subsets. The reduced number of T-helper cells – caused by a CD45RA-cell loss – leads to a change in the relation „RA/RO”. It is possible that there is a link between the imbalance of „RA/RO”, the increase of highly activated T-lymphocytes and the higher expression of CD95 (Fas/APO1).

Notizen: Zusammenfassung Fragestellung: Können durch eine Charakterisierung der Lymphozytensubpopulationen bei Patienten mit Ataxia teleangiectatica Rückschlüsse auf den zellulären Defekt der Immunfunktionsstörung gezogen werden? Methodik: Mit Hilfe der Durchflußzytometrie und des Einsatzes monoklonaler Antikörper führten wir eine Immunophänotypisierung bei jeweils 10 Patienten mit Ataxia teleangiectatica und eines bezüglich des Alters und des Geschlechts gleichverteilten Kontrollkollektivs durch. Ergebnisse: Die Patienten mit Ataxia teleangiectatica zeigten verminderte T-Zell-Zahlen mit Abnahme der T-Helferzell-Subpopulationen (CD3: 990/µl, p〈0,0005 und CD4: 568/µl, p〈0,0005). Auch die B-Zell-Zahl war erniedrigt (CD19: 39/µl, p〈0,005). Die T-Lymphozyten befanden sich darüber hinaus vermehrt im aktivierten Zustand, erkennbar an einer prozentual erhöhten HLA-DR- und CD45RO-Expression (HLA-DR: 57%, p〈0,0005 und CD45RO: 82%, p〈0,001) sowie an einer Verschiebung der Relation „RA/RO” zugunsten der „RO”-Expression. Gleichzeitig war die Expression von CD95 (Fas/APO1) deutlich gesteigert (CD95: 74%, p〈0,001). Schlußfolgerung: Die Veränderungen der Lymphozytensubpopulationen zeigen bei den Patienten mit Ataxia teleangiectatica eine verminderte B- und T-Zell-Zahl. Die CD4-Lymphopenie – verursacht durch einen CD45RA-Zellverlust – bedingt eine Verschiebung der Relation „RA/RO”. Möglicherweise besteht ein Zusammenhang zwischen der Störung der Homöostase „RA/RO” und dem erhöhten Aktivierungsgrad der Zellen sowie der vermehrten CD95(Fas/APO1)-Expression.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001120050519

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89

Digitale Medien

Hinweis auf zerebrale Mikroblutungen in der MRT Vergleichende histologische Befunde und mögliche klinische Bedeutung (1999)

Roob, Gudrun ; Kleinert, R. ; Seifert, T. ; [weitere]

Springer

Der Nervenarzt 70 (1999), S. 1082-1087

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ISSN: 1433-0407

Schlagwort(e): Schlüsselwörter Intrazerebrale Blutung ; Magnetresonanztomographie ; Hämosiderin ; Key words Intracerebral hematome ; Magnetic resonance imaging ; Hemosiderin

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: 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.

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001150050542

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90

Digitale Medien

Knochenneubildungen in einer seltenen Raumforderung des inneren Gehörgangs (1999)

Relic, A. ; Schick, B. ; Kronsbein, H. ; [weitere]

Springer

HNO 47 (1999), S. 563-568

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ISSN: 1433-0458

Schlagwort(e): Schlüsselwörter Schädelbasis ; Innerer Gehörgang ; Tumor ; Hämangiom ; Kernspintomographie ; Computertomographie ; Key words Skull-base tumors ; Internal auditory meatus ; Hemangiomas ; Magnetic resonance imaging ; Computed tomography

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: 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.

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001060050425

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91

Digitale Medien

Zerebrale Effekte von Perfluorcarbonen (1999)

Rebel, A. ; Frietsch, T. ; Quintel, M. ; [weitere]

Springer

Der Nervenarzt 70 (1999), S. 679-687

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ISSN: 1433-0407

Schlagwort(e): Schlüsselwörter Perfluorcarbon-Emulsionen ; Perfluorcarbone ; Neuroprotektion ; Ischämie ; Reperfusionsschaden ; Kernspintomographie ; Tumorversorgung ; Key words Perfluorocarbon emulsions ; Perfluorochemicals ; Cerebral protection ; Ischemia ; Reperfusion injury ; Magnetic resonance imaging ; Tumor oxygenation

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: 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.

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001150050497

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92

Digitale Medien

Die “Häm”-Sequenz (T2*-gewichtete Gradienten-Echo-Magnetresonanztomograpie¶Stellenwert in der Differentialdiagnose spontaner intrazerebraler Blutungen (1999)

Siebner, H.R. ; Gräfin von Einsiedel, H. ; Wilhelm, T. ; [weitere]

Springer

Der Nervenarzt 70 (1999), S. 714-722

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ISSN: 1433-0407

Schlagwort(e): 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

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Beschreibung / Inhaltsverzeichnis: 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.

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001150050500

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93

Digitale Medien

Oxidation of lipoprotein in injury and repair of obstructive nephropathy (1999)

Saborio, P. ; Ward, K. ; Chan, W. ; [weitere]

Springer

Clinical and experimental nephrology 3 (1999), S. 254-260

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ISSN: 1437-7799

Schlagwort(e): Key words Low density lipoprotein ; Apoptosis ; Malondialdehyde ; TGFβ1 ; Unilateral ureteral obstruction

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Background. To test the hypothesis that oxidized low density lipoprotein (oLDL) is involved in the renal injury of obstructive nephropathy, male Sprague-Dawley rats weighing 125–150 g were used. Methods. Three days after arrival, the rats were randomly assigned to undergo: (1) sham operation, (2) left unilateral ureteral obstruction (UUO), or (3) reversal of the unilateral ureteral obstruction (R-UUO). Seven days after the reversal operation or 10 days after the sham or UUO procedure, all animals were killed by exsanguination under anesthesia, with blood taken from the abdominal aorta. LDL was prepared by gradient ultracentrifugation and used immedi-ately after isolation. Rat mesangial cells were utilized with an LDL concentration of 100 μg/ml/protein in the media. After 72 h, cell survival was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) method. Cell survival was determined by comparing the optical density between the control wells and the experimental wells. In order to investigate the mechanisms of injury and repair of obstructive nephropathy, data for kidney apoptosis, malondialdehyde (MDA), and transforming growth factor β1 (TGFβ1) mRNA were obtained in the sham-operated, UUO, and R-UUO groups. Results. Our results showed that LDL malondialdehyde during UUO was increased 87% over baseline values (P 〈 0.005). With R-UUO, the oxidized LDL dropped 23% from the peak values during UUO (P 〈 0.005), but was still different from that of the baseline values (P 〈 0.025). Rat mesangial cell survival, after 72 h exposure to oLDL, inversely correlated to oLDL cytotoxicity and showed a 14% drop during UUO compared with sham-operated animals (P 〈 0.01). Cell survival increased 11% after R-UUO (P 〈 0.02) and was not different from control values (P = NS). The apoptotic counts by the TUNEL (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labelling) technique showed significant increases during UUO and a noticeable reduction after R-UUO. Conclusion. Our data support the proposition that UUO stimulates oxidation of LDL. The cytotoxicity of oLDL plays a significant role in the injury of UUO. A decrease in cytotoxicity was associated with the repair in R-UUO. Our observations that apoptosis follows this same pattern, point to the importance of apoptosis in the injury and repair of obstructive nephropathy. Future studies to interrupt these processes of injury may lead to novel treatment modalities in reversing the injury and hastening the repair of obstructive nephropathy.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101570050044

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94

Digitale Medien

Apoptosis and bcl-2 oncogene expression in Wilms' tumor (1999)

Tanaka, K. ; Granata, C. ; Wang, Y. ; [weitere]

Springer

Pediatric surgery international 15 (1999), S. 243-247

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ISSN: 1437-9813

Schlagwort(e): Key words Wilms' tumo ; Apoptosis ; Bcl-2

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Wilms' tumor (WT) usually has a good outcome, although a poor prognosis is often related to more advanced stages and anaplastic features. Apoptosis occurs with variable frequency in malignant tumors, and may have a role in reducing their growth rate. The bcl-2 proto-oncogene inhibits apoptosis, and the consequent increase in the number of cells may play a role in the development of tumors. The aim of this study was to analyze the role of apoptosis and bcl-2 expression in WT. Twenty-six resected WT specimens were studied; 12 patients had stage I tumor, 4 stage II, 5 stage III, 3 stage IV, and 2 stage V. Twenty-three tumors were classified as favorable histology (FH) and 3 as unfavorable (UH). The mean follow-up was 34 months; 22 patients were alive and 4 were dead (2 with FH: 1 stage III and 1 stage IV, and 2 with UH stages 4). Apoptosis was detected by the in-situ end-labelling technique; bcl-2 expression was detected by immunohistochemistry. An apoptotic index (AI) was calculated as the ratio of apoptotic to normal cells in each specimen. The AI was lower in higher tumor stages, with a significant difference between stages I and IV (P 〈 0.05). In cases with UH, Al was lower than in tumors with FH (P 〈 0.01). The AI was also lower in patients who died than in those who survived (P 〈 0.01). In all specimens no correlation between AI and bcl-2 expression was observed. Progression to advanced stages of WT and a poor prognosis f anaplastic tumors may be linked with disruption of the mechanisms that control apoptosis. Bcl-2 does not play a role as a regulator of apoptosis in WT, other oncogenes and tumor-suppression genes may be more involved in inhibiting apoptosis in WT.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s003830050567

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95

Digitale Medien

Effect of cell plating density and extracellular matrix protein on cell growth of epithelial rests of Malassez in vitro (1999)

Nishimura, Michiko ; Abiko, Y. ; Mitamura, Jiro ; [weitere]

Springer

Medical electron microscopy 32 (1999), S. 127-132

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ISSN: 1437-773X

Schlagwort(e): Key words Epithelial rest of Malassez ; Cell ; cell interaction ; Extracellular matrix ; In vitro ; Apoptosis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract The present study investigated how cell plating density and extracellular matrix protein influence cell survival of epithelial rests of Malassez (ERM) in vitro. ERM cells were plated on culture dishes coated with laminin (LM), type IV collagen (type IV), or fibronectin (FN), or on noncoated dishes, (Non) at a cell density of 2 × 104–1 × 105/ml in a nonserum culture medium. XTT assays were performed to calculate the number of cells attached on the substrata after 6, 24, 48, and 72 h. Mean cell numbers were calculated, and significant differences were determined using ANOVA. When epithelial cells were cultured on various matrices at a cell density of less than 2 × 104/ml, the cells did not grow and then fell into apoptotic cell death, which was confirmed by transmission electron microscopy. The cell number was significantly increased in cells plated on FN compared to those on Non at a cell density of 4 × 104/ml–8 × 104/ml. These results suggest that both extracellular matrix proteins and cell–cell interactions may contribute to prevent apoptosis of ERM in vitro. Cell–cell interactions may be a more important factor than exogenous extracellular matrix proteins for the survival of ERM cells in vitro.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s007950050019

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96

Digitale Medien

Effect of anticancer agents on Fas-mediated cytotoxicity against bladder cancer cells (1999)

Mizutani, Y. ; Yoshida, Osamu

Springer

Journal of infection and chemotherapy 5 (1999), S. 139-143

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ISSN: 1437-7780

Schlagwort(e): Key words Fas ; ADR ; Bladder cancer ; Synergy ; Apoptosis

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Fas and Fas ligand play an important role in cytotoxic T lymphocyte-mediated cytotoxicity. Like Fas ligand, anti-Fas monoclonal antibody (mAb) induces apoptosis of cells expressing Fas and mimics tumor necrosis factor-α (TNF-α) in its cytotoxic activity, but not in regard to other TNF-α-mediated activities. Since combination treatment with TNF-α and some anticancer chemotherapeutic agents results in synergistic cytotoxicity against various cancer cells, anti-Fas mAb may also synergize with anticancer agents in exerting cytotoxicity. The present study examined this hypothesis using bladder cancer cells. Cytotoxicity was examined by a 1-day microculture tetrazolium dye assay. Treatment of T24 cells with anti-Fas mAb in combination with mitomycin C, methotrexate, or 5-fluorouracil did not overcome their resistance to these agents. However, combination treatment with anti-Fas mAb and adriamycin (ADR) resulted in a synergistic cytotoxic effect on T24 cells, three other bladder cancer lines, and fresh bladder cancer cells derived from four patients. Treatment with ADR enhanced the expression of Fas on T24 cells. The expression of P-glycoprotein was not affected by the antibody-mediated sensitization. This study showed that combination treatment of bladder cancer cells with anti-Fas mAb and ADR can overcome their resistance and that the upregulation of Fas expression by ADR may play a role in the enhanced cytotoxicity.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101560050023

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97

Digitale Medien

Expression of Fas and Bcl-2 proteins and induction of apoptosis in human hepatocellular carcinoma cell lines (1999)

Seki, S. ; Kitada, Takuya ; Sakaguchi, Hiroki ; [weitere]

Springer

Medical electron microscopy 32 (1999), S. 199-203

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ISSN: 1437-773X

Schlagwort(e): Key words Hepatocellular carcinoma ; Apoptosis ; Fas protein ; Bcl-2 protein

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Because the induction of apoptosis in cancer cells is very important in clinical management, it is useful to examine the association with the Fas–Fas ligand pathway and Bcl-2 protein family in apoptosis. We morphologically examined the expression of Fas and Bcl-2 proteins and induction of apoptosis by anti-Fas in four human hepatocellular carcinoma cell lines, PLC/PRF/5, Huh-6, and Huh-7, as well as OCUH-16, which was originally established in our university. Fas protein was expressed in 96% of OCUH-16 cells in cytoplasm, 24% of PLC/PRF/5 cells, 20% of Huh-6 cells, and no Huh-7 cells. Bcl-2 protein was expressed in 43%–72% of cells in cytoplasm and nuclei of the four lines examined. Administration of anti-Fas induced apoptosis in about 40% of OCUH-16 cells, but did not induce apoptosis in the other three cell lines. In conclusion, an original cell line, OCUH-16 cells, expressed Fas and Bcl-2 proteins and underwent apoptosis following treatment with anti-Fas, but the other three cell lines examined did not undergo apoptosis. OCUH-16 cells are thus very useful for the study of apoptosis and molecules related to apoptosis at the levels of cell-surface receptors and intracytoplasmic regulation of apoptosis.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s007950050002

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98

Digitale Medien

Effects of interleukin-6 (IL-6) on chemotherapy-induced apoptosis in human ovarian cancer cell lines (1999)

Ishioka, S. ; van Haaften-Day, Caroline ; Sagae, Satoru ; [weitere]

Springer

International journal of clinical oncology 4 (1999), S. 84-89

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ISSN: 1437-7772

Schlagwort(e): Key words Ovarian cancer ; Apoptosis ; IL-6 ; CDDP ; Taxol

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Abstract Background. Apoptosis is a cascade of events that is regulated by many factors. We studied the effects of interleukin-6 (IL-6) on chemotherapy-induced apoptosis in three human ovarian cancer cell lines (JV, GG, and NF). Methods. Cells were treated with the anticancer drugs cis-diamminedichloroplatinum (II) (CDDP) and paclitaxel (Taxol; Bristol-Myers Squibb Pharmacessticals, Noble Park, Australia) over a period of 72 h. The treatments were repeated in combination with human recombinant IL-6 or anti-IL-6 monoclonal antibody (anti-IL-6 mAb). The induction of cell death was examined by morphology and by internucleosomal DNA fragmentation. Results. Reduced cytotoxicity and fewer apoptotic cells were observed after treatment with CDDP or Taxol combined with IL-6 compared with treatment with CDDP or Taxol alone. However, treatment with CDDP or Taxol combined with anti-IL-6 mAb enhanced the cytotoxic effects of the drugs and increased the number of apoptotic cells. These findings indicated that apoptosis caused by CDDP or Taxol was influenced negatively by high doses of IL-6. Conclusion. The use of CDDP or Taxol combined with anti-IL-6 mAb may have therapeutic value for patients with ovarian cancer.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s101470050032

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99

Digitale Medien

Preoperative imaging of a choledochal cyst in children: non-breath-holding magnetic resonance cholangiopancreatography (1999)

van Heurn-Nijsten, E. W. A. ; Snoep, G. ; Kootstra, G. ; [weitere]

Springer

Pediatric surgery international 15 (1999), S. 546-548

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ISSN: 1437-9813

Schlagwort(e): Key words Cholangiography ; Choledochal cyst ; Cholestasis ; Magnetic resonance imaging

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s003830050667

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100

Digitale Medien

Posteromedial corner of the knee: MR imaging with gross anatomic correlation (1999)

Loredo, R. ; Hodler, Juerg ; Pedowitz, Robert ; [weitere]

Springer

Skeletal radiology 28 (1999), S. 305-311

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ISSN: 1432-2161

Schlagwort(e): Key words Joint ; Knee ; Anatomy ; Magnetic resonance imaging ; Posteromedial corner ; Intra-articular contrast

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: 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.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s002560050522

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