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  • 1
    ISSN: 1432-1041
    Keywords: Multidrug resistance ; verapamil enantiomers ; T-cell lymphoma ; norverapamil ; vincristine ; daunomycin ; cytotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Verapamil, a calcium channel blocker, is used as the racemate. Recently, racemic verapamil has been shown to increase the cytotoxicity of vinca alkaloid and anthracycline derivatives in several resistant tumour cell lines. With respect to its cardiovascular activity S-verapamil is an order of magnitude more potent than R-verapamil. Since it was not known whether the effect on multidrug resistance was also enantioselective a comparison has been made of the potency of the R and S enantiomers and racemic verapamil in their ability to increase the cytotoxicity of vincristine and daunomycin in sensitive (MOLT 4B) and drug resistant human T-lymphoma cell lines (MOLT/VCR-5×9, MOLT/DAU-8 and VCR 1000, a highly resistant subline of CCRF-CEM). Two major metabolites, norverapamil and D617 were tested in the same system. (+)-R, (−)-S-, racemic verapamil, norverapamil and D617 alone had no effect on cell growth in sensitive or resistant cell lines in concentrations up to 20 μM. In combination with vincristine, verapamil and norverapamil but not D617 produced a concentration dependent increase in the sensitivity of the resistant lines. Racemic verapamil, its individual enantiomers and norverapamil were equipotent. The concentration of the modifiers required to elicit 50% of the maximum effect (EC50) was of the order of 0.5 μM. No significant difference in the slopes of the concentration-effect curves were observed. The effect of verapamil and norverapamil was additive. In the sensitive MOLT 4B cell line both enantiomers and norverapamil increased sensitivity towards vincristine. However, the EC50 values were at least an order of magnitude higher (2.5–8 μM) than in the resistant cell lines. In contrast to the vincristine resistant cell lines, no effect on the potentiation of daunomycin cytotoxicity was observed in sensitive and daunomycin-resistant cells in the presence of a modifier. Since the activity of verapamil as a modifier of drug resistance is not enantioselective, the weaker calcium antagonist R-enantiomer appears to be better suited for clinical trials. Because of its lesser cardiovascular activity much higher doses could be given, and a higher plasma concentration would be achieved. As norverapamil, the major plasma metabolite formed during first pass elimination, is as potent as the parent drug as a modifier of drug resistance, the oral route of administration is preferable to i. v. administration in clinical trials employing R-verapamil as a modifier.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1463
    Keywords: Keywords: Salsolinol ; Parkinson's disease ; N-methylation.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary. An augmented synthesis of tetrahydroisoquinolines, such as salsolinol (SAL) or an increased N-methylation of these compounds has been addressed by various investigators as putative pathophysiologic mechanisms in Parkinson's disease (PD). Aim of this study was (1) to investigate putative relations between plasma levels of dopamine and R- and S-enantiomers of SAL and (2) whether these metabolic precursors of the neurotoxic N-methylated-SAL (NMSAL) are elevated in untreated "de-novo" Parkinsonian patients compared to age- and sex-matched healthy controls. Plasma levels of R- and S-SAL and dopamine did not significantly (R-SAL: p = 0.61, S-SAL: p = 0.51, dopamine: p = 0.84) differ in both groups. Parkinsonian patients' R-SAL plasma levels were inversely related to intensity (p = 0.03, r = −0.42) and duration of PD (p = 0.03, r = −0.43) in contrast to S-SAL and dopamine. Dopamine levels were not associated to R-SAL (p = 0.88, r2 = 0.0008) and S-SAL (p = 0.088, r2 = 0.12) neither in Parkinsonian patients nor in controls. We conclude, that an upregulation of N-methylation of tetrahydroisoquinolines takes place in PD by enzymes such as neutral N-methyltransferase specific for R-SAL. The activity of this enzyme has been found elevated in parkinsonian lymphocytes. This increased N-methylation by the N-methyltransferase specific for R-SAL leads to the known augmented levels of neurotoxic R-NMSAL in Parkinsonian patients compared to controls in the cenral nervous system especially in the beginning of PD.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Cysticercus racemosus ; Scolex ; Praziquantel ; Albendazol ; Dreidimensionale transkraniale Duplexsonographie ; Key words Cysticercus racemosus ; Scolex ; Praziquantel ; Albendazol ; Three-dimensional (3D) ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Neurocysticercosis, caused by Taenia solium larvae (cysticerci), is the most common parasitic infection of the human CNS Worldwide. In Germany its appearance is rare. Here we report two cases of neurocysticercosis which we followed over a period of 4–6 years. The first patient acquired neurocysticercosis in Germany. On admission he suffered from papilledema, partial seizures and a mild psychotic disorder. MR-tomography showed an internal hydrocephalus and multiple contrast enhancing parenchymal cysts. In the course of the disease a giant cyst within the left temporal pole developed and was exstirpated neurosurgically. The persistent internal hydrocephalus required ventriculoperitoneal shunting. Therapy with Praziquantel led to a clinical improvement, however, repeated analysis of the cerebrospinal fluid documented peristent inflammation. With the aid of a contrast enhanced three-dimensional (3D) ultrasound imaging technique we demonstrated increased cerebral perfusion surrounding one cyst. This may be interpreted as evidence for persistent disease activity. The second patient presented with repeated episodes of cysticercotic encephalitis, which is rarely described in the literature (incidence 1%). Clinical features, laboratory findings, diagnosis, and therapy of neurocysticercosis will be presented together with the pitfalls of the two described cases. Our cases will be compared to previous reports on clinical findings in neurocysticercosis.
    Notes: Zusammenfassung Die Neurozystizerkose, hervorgerufen durch eine Infektion mit larvenhaltigen Eiern (Onkosphären) des Schweinebandwurms (Taenia solium), ist die häufigste Parasitose des ZNS. In Deutschland ist ihr Auftreten eine Rarität. Zwei Kasuistiken deutscher Erkrankungsfälle und deren über einen Zeitraum von 4–6 Jahren dokumentierer Erkrankungsverlauf werden vorgestellt. Der erste Patient akquirierte eine parenchymatös verlaufende Neurozystizerkose in Deutschland, präsentierte sich mit einer Stauungspapille, zerebralen Anfällen sowie einem Psychosyndrom. MR-tomographisch zeigten sich multiple, Scolex-haltige, periventrikulär lokalisierte, Kontrastmittel-aufnehmende Zysten sowie ein Hydrozephalus internus. Therapeutisch waren neben einer Shuntanlage und der Teilexstirpation einer zerebralen Megazyste auch mehrere Anthelminthika-Therapien nötig, um einen Rückgang der Zystengröße zu bewirken. Kontinuierliche Liquoruntersuchungen dokumentieren diesen protrahierten Erkrankungsverlauf. Mit Hilfe der transkraniellen, kontrastverstärkten, dreidimensionalen Duplexsonographie konnte eine gesteigerte Perfusion im Randbereich der Zysten als Hinweis auf einen chronisch aktiven Krankheitsprozeß nachgewiesen werden. Bei dem zweiten Fall handelt es sich um eine seltene (Häufigkeit ca. 1%) meningoenzephalitische Verlaufsform der Neurozystizerkose. Die Verläufe sowie das Erkrankungsbild werden anhand eines aktuellen Literaturüberblicks diskutiert.
    Type of Medium: Electronic Resource
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  • 4
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    Unknown
    Provincetown, Mass., etc. : Periodicals Archive Online (PAO)
    The Journal of Genetic Psychology. 80 (1952) 3 
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 9 (1981), S. 187-191 
    ISSN: 1434-0879
    Keywords: Cystometry ; Long-term monitoring ; Bed-wetting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A system was developed and built for recording and processing urodynamic measurements during a 24 h period. The essential requirement was to obtain these signals without psychological stress. The system was small enough to allow the patient to move freely. Semiconductor pressure transducers were employed for measuring total bladder and rectal pressures and detrusor pŕessure was obtained by subtraction. Results gained with this method revealed some differences to those obtained with conventional methods.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical chemistry accounts 77 (1990), S. 123-141 
    ISSN: 1432-2234
    Keywords: Pseudopotentials ; Spin-orbit operator ; Transition metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Nonrelativistic and quasirelativisticab initio pseudopotentials substituting the M(Z−28)+-core orbitals of the second row transition elements and the M(Z−60)+-core orbitals of the third row transition elements, respectively, and optimized (8s7p6d)/[6s5p3d]-GTO valence basis sets for use in molecular calculations have been generated. Additionally, corresponding spin-orbit operators have also been derived. Atomic excitation and ionization energies from numerical HF as well as from SCF pseudopotential calculations using the derived basis sets differ in most cases by less than 0.1 eV from corresponding numerical all-electron results. Spin-orbit splittings for lowlying states are in reasonable agreement with corresponding all-electron Dirac-Fock (DF) results.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2234
    Keywords: Pseudopotentials ; Transition metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Recently published nonrelativistic and quasirelativistic energy-adjustedab initio pseudopotentials representing the M(Z−28)+ cores of the second row transition metal atoms and the M(Z−60)+ cores of the third row transition metal atoms have been tested in SCF, CI(SD) and CEPA1 calculations of the spectroscopic constants (R e ,D e , and ω e ) of the ground states of the neutral and singly charged silver and gold dimers, and in state averaged CASSCF and multi-reference CI(SD) calculations of the spectroscopic constants (R e ,D e , ω e , μ e , ∂μ/∂R). Comparison is made with experimental and reliable theoretical data where available; in the case of the hydrides, additional calculations with pseudopotentials published by other groups have been made for comparison.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0947-6539
    Keywords: chemical bonding ; electron localization ; scanning tunnelling microscopy ; surface structures ; tight-binding calculations ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The advantage of computer graphics in the visualization of tight-binding calculations is highlighted in a model study of the reconstruction of the Si(100) surface. Three different surface models - the unreconstructed surface Si(100)-(1 × 1), and symmetric and asymmetric pairing of surface atoms Si(100)-(2 × 1) - are investigated on the basis of density of states (DOS), local (projected) density of states (LDOS) and crystal orbital-overlap population (COOP) analysis. For the visualization of the real-space properties of tight-binding calculations, two- and three-dimensional images of the total (TED) and partial electron densities (PED) are shown. The PED calculated near the Fermi level are compared to densities of HOMOs and LUMOs in molecular systems and used to analyse constant current mode STM images, obtained by applying bias voltages of different sign. They show excellent agreement with STM experiments. The electron-localization function (ELF) has been shown to describe chemical bonds in molecules and solids surprisingly well. Here, the ELF is calculated for surfaces. In order to visualize the shape of the “dangling” surface bonds and bonds connecting surface atoms, two- and three-dimensional representations of the ELF are discussed. Using the reconstruction of the Si(100) surface as an example, we show that combining methods for extracting information from quantum mechanical calculations, such as PED, TED and ELF, leads to a more comprehensive description of the electronic surface structure. With the help of computer graphics, chemical concepts routinely used for describing local properties of molecules can be transferred very effectively to extended systems.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pest science 48 (1975), S. 107-109 
    ISSN: 1612-4766
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Construction of an electronical scab warning apparatus The control of the apple-scab in Germany needs an average of 10–15 treatments a year. In order to minimize the pollution of the natural environment and to determine the optimal time of infection an electronical scab warning apparatus has been developed. The system consists of a console, housing the electronic and data display components, and a sensing unit. The sensing unit, placed in the orchard, monitors duration of foliage moisture, temperature, and humidity. These data are processed and stored electronically in the console. The influence of humidity during periods when the foliage is dry, which determines how long the dormant fungus remains viable, is also taken into account. The console can provide an accurate read-out of fungus growth at an stage, and indicates the exact moment for most effective spraying. The basis of this construction is an elarged Mills-table, which enables to determine the infection time according to temperature and moisture on the leaves.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 26 (1887), S. 750-751 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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