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  • Positron emission tomography  (2)
  • (2,5,8-trioxanonane-O2,O5)lithium methylphosphanide  (1)
  • Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium disilylphosphanide  (1)
  • 1
    ISSN: 1619-7089
    Keywords: Key words: Liver cell hypoxia ; Nitroimidazole imaging ; Fluorine-18 fluoromisonidazole ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Fluorine-18 labelled fluoromisonidazole ([18F]FMISO) has been shown to accumulate in hypoxic tissue in inverse proportion to tissue oxygenation. In order to evaluate the potential of [18F]FMISO as a possible positron emission tomography (PET) tracer for imaging of liver tissue hypoxia, we measured the [18F]FMISO uptake in 13 domestic pigs using dynamic PET scanning. Hypoxia was induced by segmental arterial hepatic occlusion. During the experimental procedure the fractional concentration of inspired oxygen (FiO2) was set to 0.67 in group A (n=6) and to 0.21 in group B (n=7) animals. Before and after arterial occlusion, the partial pressure of O2 in tissue (TPO2) and the arterial blood flow were determined in normal flow and flow-impaired liver segments. Standardised uptake values [SUV=kBq tissue (in g) / body weight (in kg) × injected dose (in kBq)] for [18F]FMISO were calculated from PET images obtained 3 hours after injection of about 10 MBq/kg body weight [18F]FMISO. Immediately before PET scanning, the mean arterial blood flow was significantly decreased in arterially occluded segments [group A: 0.41 (0.32–0.52); group B: 0.24 (0.16–0.33) ml min–1 g–1] compared with normal flow segments [group A: 1.05 (0.76–1.46); group B: 1.14 (0.83–1.57) ml min–1 g–1; geometric mean (95% confidence limits); P〈0.001 for both groups]. After PET scanning, the TPO2 of occluded segments (group A: 5.1 (4.1–6.4); group B: 3.5 (2.6–4.9) mmHg] was significantly decreased compared with normal flow segments [group A: 26.4 (21.2–33.0); group B: 18.2 (13.3–25.1) mmHg; P〈0.001 for both groups]. During the 3-h PET scan, the mean [18F]FMISO SUV determined in occluded segments increased significantly to 3.84 (3.12–4.72) in group A and 5.7 (4.71–6.9) in group B, while the SUV remained unchanged in corresponding normal liver tissue [group A: 1.4 (1.14–1.71); group B: 1.31 (1.09–1.57); P〈0.001 for both groups]. Regardless of ventilation conditions, a significant inverse exponential relationship was found between the TPO2 and the [18F]FMISO SUV (r 2=0.88, P〈0.001). Our results suggest that because tracer delivery to hypoxic tissues was maintained by the portal circulation, the [18F]FMISO accumulation in the liver was found to be directly related to the severity of tissue hypoxia. Thus, [18F]FMISO PET allows in vivo quantification of pig liver hypoxia using simple SUV analysis as long as tracer delivery is not critically reduced.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1619-7089
    Keywords: Key words: Fluorine-18 ; Bone graft viability ; Hip revision arthroplasty ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The biological fate of allogenic bone grafts in the acetabular cavity and their metabolic activity after acetabular augmentation is uncertain but is most important for the stability of hip implants after hip revision arthroplasty. The aim of this study was to quantify regional bone metabolism after hip replacement operations. Dynamic [18F]fluoride ion positron emission tomography (PET) was used to investigate the metabolic activity of acetabular allogenic bone grafts and genuine bone, either 3–6 weeks (short-term group, n = 9) or 5 months to 9 years (long-term group, n = 10) after hip revision arthroplasty. Applying a three-compartment model, the fluoride influx constant was calculated from individually fitted rate constants (K nlf) and by Patlak graphical analysis (K pat). The results were compared with genuine cancellous and cortical acetabular bone of contralateral hips without surgical trauma (n = 7). In genuine cortical bone, K nlf was significantly increased in short- (+140.9%) and long-term (+100.0%) groups compared with contralateral hips. Allogenic bone grafts were characterised by a significantly increased K nlf in the short-term group (+190.9%) compared with contralateral hips, but decreased almost to the baseline levels of contralateral hips (+45.5%) in the long-term. Values of K nlf cor-related with the rate constant K 1 in genuine (r = 0.89, P〈0.001) and allogenic bone regions (r = 0.79, P〈0.001), indicating a coupling between bone blood flow and bone metabolism in genuine bone as well as allogenic bone grafts. K pat values were highly correlated with K nlf measurements in all regions. In conclusion, [18F]fluoride ion PET revealed the presence of an increased host bone formation in allogenic bone grafts early after hip revision arthroplasty. In contrast to genuine cortical bone, allogenic bone graft metabolism decreased over time, possibly due to a reduced ability to respond to the same extent as genuine bone to elevated metabolic demands after surgery.
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  • 3
    ISSN: 0044-2313
    Keywords: (1,2-dimethoxyethane-O,O′)lithium methylphosphanide ; (2,5,8-trioxanonane-O2,O5)lithium methylphosphanide ; catena-poly(lithium-organylphosphanide) ; X-ray structure determination ; meso-helix ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Derivatives of Molecular Compounds. VIII. catena-Poly[(2,5,8-trioxanonane-O2,O5) lithium-methylphosphanide]  -  a Compound with a meso-Helix StructureStudies of Fritz et al. [10] showed methylphosphane to be lithiated at -60°C in 1,2-dimethoxyethane or bis(2-methoxyethyl) ether solution by stoichiometric amounts of lithium n-butanide in n-hexane. After removing the hydrocarbons almost completely by distillation and cooling the solutions to -60°C again, colourless square crystals of (1,2-dimethoxyethane-O,O′)lithium (1) and (2,5,8-trioxanonane-O2,O5)lithium methylphosphanide (2) precipitate. As shown by an X-ray structure determination (monoclinic, P21/n; a = 805.5(1); b = 1820.6(2); c = 851.5(1) pm; β = 116.76(1)° at -100 ± 3°C; Z = 4 formula units; R = 0.034) complex 2 forms a polymer which has the shape of an up to now scarcely noted meso-helix. Four-coordinated lithium is bound to two phosphorus (P—Li 252.9 and 253.2 pm; P—Li—P 131.8°; Li—P—Li 132.1°) and to two oxygen atoms (Li—O 203.9 and 206.8; O … O 270.7 pm; O—Li—O 82.5°) of the inherently tridentate 2,5,8-trioxanonane ligand. As compared to the standard value (185 pm) the P—C distance (187.4 pm) is slightly lengthened. Structure determinations of (2,5,8-trioxanonane-O2,O5,O8) lithium 1-(phenylsulfonyl)alkyl compounds published some years ago [26, 27], allow a comparison of molecular parameters characteristic for the twofold or threefold coordinating chelate ligand.
    Notes: Nach Untersuchungen von Fritz u. a. [10] wird in 1,2-Dimethoxyethan oder Bis(2-methoxyethyl)ether Zur einfacheren Beschreibung der Koordination am Lithium wählen wir beim Bis(2-methoxyethyl)ether (diglyme) das Synonym 2,5,8-Trioxanonan. 1,2-Bis(dimethylamino)ethan (tmeda), Tetrahydrofuran (thf), 1,2-Dimethoxyethan (dme), Diethylether (OEt2) gelöstes Methylphosphan bei -60°C durch Lithium-n-butanid in n-Hexan metalliert. Beim Abkühlen der von Kohlenwasserstoffen weitgehend befreiten Ansätze auf wiederum -60°C kristallisiert (1,2-Dimethoxyethan-O,O′)lithium- (1) bzw. (2,5,8-Trioxanonan-O2,O5) lithium-methylphosphanid (2) in farblosen Quadern aus. Nach einer Röntgenstrukturanalyse (monoklin, P21/n; a = 805,5(1); b = 1 820,6(2); c = 851,5(1)pm; β = 116,76(1)° bei -100 ± 3°C; Z = 4 Formeleinheiten; R = 0,034) liegt Komplex 2 als Polymer in der bislang wenig beachteten achiralen Abfolge einer „meso-Helix“ vor. Lithium weist mit Bindungen zu zwei Phosphor- (P—Li 252,9 und 253,2 pm; P—Li—P 131,8°; Li—P—Li 132,1°) und zu nur zwei Sauerstoffatomen (Li—O 203,9 und 206,8; O … O 270,7 pm; O—Li—O 82,5°) des a priori dreizähnigen 2,5,8-Trioxanonan-Liganden ebenso wie Phosphor die Koordinationszahl 4 auf. Der P—C-Abstand ist mit 187,4 pm gegenüber dem Standard (185 pm) geringfügig verlängert. Vor einigen Jahren veröffentlichte Strukturen [26, 27] von (2,5,8-Trioxanonan-O2,O5,O8)- lithium-1-(phenylsulfonyl)alkyl-Verbindungen ermöglichen einen Vergleich charakteristischer Molekülparameter im zwei-oder dreifach koordinierenden Chelatliganden.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0044-2313
    Keywords: Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium disilylphosphanide ; [Li(tmeda)2]+ cation(1) ; [(H3Si)2P]- anion ; X-ray structure determination ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Metal Derivatives of Molecular Compounds. VII. Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium Disilylphosphanide  -  Synthesis and StructureCrystalline lithium phosphanides studied so far show a remarkably high diversity of structure types dependent on the ligands at lithium and the substituents at phosphorus. Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium disilylphosphanide (1) discussed here, belongs to the up to now small group of compounds which are ionic in the solid state. It is best prepared from silylphosphane by twofold lithiation with lithium dimethylphosphanide first and subsequent monosilylation with silyl trifluoromethanesulfonate, followed by complexation. As found by X-ray structure determination (wR = 0.038) on crystals obtained from diethyl ether {monoclinic; space group P21/c; a = 897.8(1); b = 1 673.6(2); c = 1 466.8(1) pm; β = 90.73(1)° at -100 ± 3°C; Z = 4 formula units}, the lithium cation is tetrahedrally coordinated by four nitrogen atoms of two 1,2-bis(dimethylamino)ethane molecules. Characteristic parameters of the disilylphosphanide anion are a shortened average P—Si bond length of 217 pm (standard value 225 pm) and a Si—P—Si angle of 92.3°.
    Notes: Untersuchungen an kristallinen Lithiumphosphaniden ergeben in Abhängigkeit von den Liganden am Lithium- und den Substituenten am Phosphoratom eine überraschend große Strukturviefalt. Das aus Silylphosphan durch zweifache Lithinierung mit Lithium-dimethylphosphanid, nachfolgende einfache Silylierung mit Silyl-trifluormethansulfonat und anschließende Komplexierung gut zugängliche Bis[1,2-bis(dimethylamino)ethan-N,N′]lithium-disilylphosphanid (1) gehört zur bislang kleinen Gruppe der im Festkörper ionisch vorliegenden Verbindungen. Nach einer Röntgenstruktur-analyse (wR = 0,038) an den aus Diethylether isolierten Kristallen {monoklin; Raumgruppe P21/c; a = 897,8(1); b = 1 673,6(2); c = 1 466,8(1) pm; β = 90,73(1)° bei -100 ± 3°C; Z = 4 Formeleinheiten} ist Lithium verzerrt tetraedrisch von vier Stickstoffatomen aus zwei 1,2-Bis(dimethyl-amino)ethan-Molekülen umgeben. Das Disilylphosphanid-Anion weist einen gegenüber dem Standard von 225 auf 217 pm verkürzten mittleren P—Si-Abstand und einen Si—P—Si-Winkel von 92,3° auf.
    Additional Material: 3 Ill.
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