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  • Articles: DFG German National Licenses  (4)
  • 1990-1994  (4)
  • microwaves  (2)
  • Copper-62  (1)
  • Molecular shape  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Comparison of potential energy maps and molecular shape invariance maps for two-dimensional conformational problems (1990)
    Springer
    Theoretical chemistry accounts 76 (1990), S. 377-390 
    Details
    ISSN: 1432-2234
    Keywords: Molecular shape ; Conformational energy maps ; Shape invariance maps ; van der Waals surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is well known that many molecular properties are strongly dependent on internal nuclear arrangements. Two possible, independent approaches can be followed while studying changes in molecular characteristics as functions of the nuclear geometry. These are the analysis of potential energy surfaces and the analysis of molecular shape. In this work, we seek to establish relationships between potential energy maps and shape invariance region maps, where each point of these maps represents a nuclear configuration. The study is performed by analyzing the occurrence and lack of certain symmetries in both types of maps. As illustrative examples, we consider the three structural isomers of the dihydroxybenzene molecule. Potential energy is computed at the STO-3G ab initio level, while the shape is described by the shape group method as applied to fused-sphere van der Waals surfaces. It is shown that the symmetry of the shape invariance maps follows closely, but not exactly, the symmetry of potential energy surfaces. The molecular surface is thus “blind” to some small changes of the potential (a feature to be expected to hold also for molecular surfaces defined in terms of electronic charge density). Our findings suggest that a crude fused-sphere model may suffice to describe some of the structural changes in molecular surfaces, as well as their relationships to the electronic energy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00528878
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Development of a high performance zinc-62/copper-62 radionuclide generator for positron emission tomography (1992)
    Springer
    European journal of nuclear medicine 19 (1992), S. 418-425 
    Details
    ISSN: 1619-7089
    Keywords: Radionuclide generator ; Zinc-62 ; Copper-62 ; Pyruvaldehyde-bis(N4-methylthiosemicarbazone) ; PTSM ; Positron emission tomography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Clinical utilisation of positron emission tomography could be enhanced by the availability of shortlived radionuclides derived from generator systems. The zinc-62/copper-62 combination is one such system which could be used as a source for a number of copper-62 radiopharmaceuticals. We have developed and optimised a high activity (5.6 GBq, 150 mCi) zinc-62/copper-62 generator to provide 62CU in a form that is suitable for direct labelling of pyruvaldehyde-bis-(N 4-methylthiosemicarbazone)-copper(II), Cu(PTSM). The distribution coefficients of Zn(II) and Cu(II) between anion-exchange resin and various hydrochloric acid/organic solvent mixtures were measured. Based on these measurements a generator eluent of 0.3 M HCl/40% ethanol provided 62CU in 〉90% yield in a 3-ml volume. A very low 62Zn breakthrough of less than 3×10−7% was achieved. Copper-PTSM was successfully labelled with the no-carrier-added 62Cu eluent directly from the generator with 94% radiochemical yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00177368
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Modification of membrane fluidity in melanin-containing cells by low-level microwave radiation (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 131-146 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; cell membrane ; order ; melanin ; oxygen radicals ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The treatment of a B16 melanoma cell line with 2.45-GHz pulsed microwaves (10 mW/cm2, 10-μs pulses at 100 pps, 1-h exposure; SAR, 0.2 W/kg) resulted in changes of membrane ordering as measured by EPR (electron paramagnetic resonance) reporter techniques. The changes reflected a shift from a more fluid-like phase to a more solid (ordered) state of the cell membrane. Exposure of artificially prepared liposomes that were reconstituted with melanin produced similar results. In contrast, neither B16 melanoma cells treated with 5-Bromo-2-Deoxyuridine (3 μg/day × 7 days) to render them amelanotic, nor liposomes prepared without melanin, exhibited the microwave-facilitated increase of ordering. Inhibition of the ordering was achieved by the use of superoxide dismutase (SOD), which strongly implicates oxygen radicals as a cause of the membrane changes. The data indicate that a significant, specific alteration of cell-membrane ordering followed microwave exposure. This alteration was unique to melanotic membranes and was due, at least in part, to the generation of oxygen radicals. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130207
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Increased sensitivity of the non-human primate eye to microwave radiation following ophthalmic drug pretreatment (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 379-393 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; glaucoma drugs ; primates ; corneal endothelium ; iris ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Previous studies in our laboratory have established that pulsed microwaves at 2.45 GHz and 10 mW/cm2 are associated with production of corneal endothelial lesions and with disruption of the blood-aqueous barrier in the non-human primate eye. In the study reported here we examined ocular damage in monkeys (M. mulatta and M. fascicularis) following topical treatment with one of two ophthalmic drugs (timolol maleate and pilocarpine) that preceded exposure to pulsed microwaves. Anesthetized monkeys were sham exposed or exposed to pulsed, 2.45 GHz microwaves (10 μs, 100 pps) at average power densities of 0.2, 1, 5, 10, or 15 mW/cm2 4 h a day for 3 consecutive days (respective SARs were 0.052, 0.26, 1.3, 2.6, and 3.9 W/kg). Immediately before microwave exposure, one or both eyes were treated topically with one drop of 0.5% timolol maleate or of 2% pilocarpine. Following administration of a drug, we observed a significant reduction in the power-density threshold (from 10 to 1 mW/cm2) for induction of corneal endothelial lesions and for increased vascular permeability of the iris. Diagnostic procedures (in vivo specular microscopy and fluorescein iris angiography) were performed following each exposure protocol. In addition, increased vascular permeability was confirmed with horseradish peroxidase tracer techniques. Although we did not measure intraocular temperatures in experimental animals, the results suggest that a mechanism other than significant heating of the eye is involved. Our data indicate that pulsed microwaves at an average SAR of 0.26 W/kg, if administered after pretreatment with ophthalmic drugs, can produce significant ocular effects in the anesthetized primate. 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130505
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    Paper (German National Licenses)
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