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  • 1
    Electronic Resource
    Electronic Resource
    Exploring the Conformational Behavior of Rigid Porphyrin-Quinone Systems by High-Temperature MD Simulations and Temperature-Dependent 1H-NMR Experiments (1996)
    Springer
    Journal of molecular modeling 2 (1996), S. 383-385 
    Details
    ISSN: 0948-5023
    Keywords: High-Temperature MD Simulations ; Confor-mational Analysis ; Porphyrin-Quinone Systems ; Photosynthesis Models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Photoinduced electron transfer reactions play an important role in the primary step of the biological photosynthesis process. In an attempt to understand better the mechanism of the charge separation organic donor-acceptor molecules containing porphyrins and quinones were designed as photosynthesis models. In order to study the structure dependence of the photoinduced electron transfer twofold and fourfold bridged porphyrin-quinone systems with increasing donor-acceptor distance were synthesized (Figure 1) [1, 2, 3]. It was assumed that in these molecules the porphyrin and quinone should be linked in a rigid and well-defined orientation. To verify this assumption the conformational behavior of these systems was studied by high-temperature MD simulations in combination with conformational analysis of selected minimized structures [4, 5].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s0089460020383
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  • 2
    Electronic Resource
    Electronic Resource
    Evidence for prolonged recovery of dopaminergic transmission after detoxification in alcoholics with poor treatment outcome (1995)
    Springer
    Journal of neural transmission 102 (1995), S. 149-157 
    Details
    ISSN: 1435-1463
    Keywords: Dopamine receptors ; Growth Hormone ; alcoholism ; dopamine ; relapse ; neuroadaption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary It has been hypothesized that dysfunction of dopaminergic neurotransmission is involved in the pathogenesis of alcohol addiction. Therefore, peripheral dopamine levels, sensitivity of central dopamine receptors (apomorphine-induced Growth Hormone (GH) secretion), and the inhibitory efficacy of G-proteins on adenylyl cyclase activity (as an indicator for dopamine D2-receptor coupled second messenger mechanisms) were measured in 45 alcohol-dependent patients before and after detoxification and in 10 healthy controls. The time needed to adjust to abstinence conditions differed between patients with good and poor treatment outcome. In subsequent abstainers, effects of alcohol withdrawal were already found during the first 24 hours of abstinence (normalisation of GH response, increases in dopamine levels and the inhibitory efficacy of G-proteins). During the next 7 days of abstinence, no more significant changes were observed in the assessed variables. In subsequent relapsers, no significant effect of acute ethanol withdrawal on the same measures was found. However, at day 8 of abstinence, increases in apomorphine-induced GH secretion (towards normalisation), in dopamine plasma levels, and in the inhibitory efficacy of G-proteins (towards above-normal levels) were observed. This retarded adjustment of dopaminergic signal transduction seems to reflect the relapse risk of treatment non-responders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276510
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  • 3
    Electronic Resource
    Electronic Resource
    Psychopathologische Korrelate dopaminerger Dysfunktion bei alkoholabhängigen und schizophrenen Patienten (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 399-407 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Dopaminerges Verstärkungssystem ; Anhedonie ; Alkoholabhängigkeit ; Dopaminhypothese der Schizophrenien ; Phasische versus tonische Dopaminfreisetzung ; Key words Dopaminergic reward system ; Anhedonia ; Alcohol dependence ; Dopamine hypothesis of schizophrenia ; Phasic versus tonic dopamine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary It has been suggested that anhedonia, the loss of pleasure, is associated with a dysfunction of the dopaminergic reward system in schizophrenic and alcohol-dependent patients. In a series of neuroendocrinological and brain imaging studies, we examined pre- and postsynaptic mechanisms of dopaminergic neurotransmission in non-human primates and in schizophrenic and alcohol-dependent patients. Among alcoholics, we found indicators of a sensitization of dopaminergic neurotransmission, which was associated with the relapse risk, but not with anhedonia or depression. Schizophrenics with neuroleptic blockade of striatal dopamine D2 receptors displayed psychomotor slowing and reduced motivation, but not anhedonia. Primate studies pointed to the importance of a temporo-cortical dysfunction in the pathogenesis of phasic dopaminergic dysregulation in the striatum. These observations indicate that a dysfunction of stimulus-dependent dopamine release may be associated with motivational deficits caused by a reduction in incentive salience, but not with anhedonia.
    Notes: Zusammenfassung Aufgrund von Tierversuchen war postuliert worden, daß Anhedonie das gemeinsame psychopathologische Korrelat einer Störung des dopaminergen Verstärkungssystems darstellt. In einer Serie neuroendokrinologischer und bildgebender Studien untersuchten wir prä- und postsynaptische Mechanismen der dopaminergen Neurotransmission bei Primaten sowie bei schizophrenen und alkoholabhängigen Patienten. Bei abstinenten alkoholabhängigen Patienten fanden sich Hinweise auf eine Sensitivierung der dopaminergen Neurotransmission, die mit dem Rückfallrisiko, nicht jedoch mit Anhedonie oder Depressivität assoziiert war. Schizophrene Patienten mit neuroleptikainduzierter Blockade der striären Dopamin-D2-Rezeptoren zeigten eine Motivationsstörung und psychomotorische Verlangsamung gegenüber medikationsfreien Patienten, aber keine Assoziation der Rezeptorblockade mit Anhedonie. Primatenstudien verwiesen auf die Rolle der temporofrontalen Kortices bei der Regulation der phasischen subkortikalen Dopaminfreisetzung. Unsere Befunde sprechen für die Annahme, daß eine Dysfunktion der stimulusabhängigen, striären Dopaminfreisetzung mit Motivationsstörungen, nicht jedoch mit Anhedonie, assoziiert ist.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050455
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  • 4
    Electronic Resource
    Electronic Resource
    Serotonerge Dysfunktion als Folge sozialer Isolation Bedeutung für die Entstehung von Aggression und Alkoholabhängigkeit (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 780-789 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Serotonin ; Verhaltensinhibierendes System ; Impulsivität ; Aggression ; Depression ; Key words Serotonin ; Behavior inhibition system ; impulsivity ; Aggression ; Depression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Dysfunction of serotonergic neurotransmission has been associated with two different psychopathological syndromes – impulsive aggressivity resulting form a lack of stimulation of the “behavior inhibition system” on the one hand and the manifestation of clinical depression and compulsive syndromes on the other. The examination of primate behavior provides a model which may reconciliate these seemingly contradictory hypotheses. According to primate experiments, monoaminergic depletion results in anxious and desperate behavior only if the individual has previously been exposed to social isolation stress, which in turn induces a decrease in the central serotonin turnover rate. Young non-human primates who experience early social separation stress are anxious and fearful, while as adults they tend to be aggressive, consume excessive amounts of alcohol and are less intoxicated by alcohol intake. These observation indicate the importance of social separation stress in the pathogenesis of alcoholism and antisocial behavior and may point to prophylactic and pharmacological treatment strategies.
    Notes: Zusammenfassung Eine Dysfunktion serotonerger Transmission wurde mit zwei verschiedenen psychopathologischen Syndromen in Verbindung gebracht. Einerseits wurde der serotonergen Neurotransmission eine wesentliche Rolle in der Stimulation des “verhaltensinhibierenden Systems” zuerkannt und postuliert, daß ein verminderter Serotoninumsatz zur Enthemmung impulsiver und aggressiver Verhaltensweisen führt. Andererseits gibt es Hinweise auf die Bedeutung einer verminderten serotonergen Transmission in der Pathogenese der Depression und der Angsterkrankungen. Eine mögliche Deutung der vordergründig widersprüchlichen Befunde ergibt sich aus der Untersuchung serotonerger Transmission bei Primaten. Eine pharmakogen induzierte Verarmung an monoaminergen Neurotransmittern führt demnach nur dann zu depressionsanalogen Verhaltensweisen, wenn in der individuellen Entwicklung mehrfach Phasen sozialer Isolation durchlebt wurden. Umgekehrt ist soziale Isolation bei jungen Primaten mit einem verminderten Serotoninumsatz, verstärkter Ängstlichkeit und sozialer Inkompetenz assoziiert, während sich bei diesen Primaten im Erwachsenenalter eine erhöhte Aggressivität und Alkoholtoleranz und ein erhöhter freiwilliger Alkoholkonsum nachweisen lassen. Diese Befunde unterstreichen die Bedeutung von Streß- und Lernfaktoren in der Ausgestaltung der psychopathologischen Korrelate einer serotonergen Dysfunktion und verweisen auf mögliche prophylaktische und pharmakologische Behandlungsoptionen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050512
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  • 5
    Electronic Resource
    Electronic Resource
    Production of medium-weight isotopes by fragmentation in 750 A MeV 238U on 208Pb collisions (1998)
    Springer
    The European physical journal 2 (1998), S. 193-198 
    Details
    ISSN: 1434-601X
    Keywords: PACS:25.75.-q – 25.70.Mn – 21.10.Ft – 21.10.Gv – 27.50.+e – 27.50.+j – 24.10.Pa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Projectile fragmentation of 238U in a lead target was investigated at a bombarding energy of 750 A MeV. Isotopic production cross sections of about 250 different projectile fragments in the element range Z= 30–53 were measured with the FRagment Separator (FRS). The magnetic selection and the kinematical analysis of the measured isotopes allowed to disentangle fission and fragmentation residues. The mass loss of these residues indicates a violent collision where a large amount of energy is dissipated. The position of the fragmentation corridor defined by the measured residues was used to determine an effective proton-evaporation barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050108
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  • 6
    Electronic Resource
    Electronic Resource
    Fission of highly excited fragments from collisions of 750 A.MeV 238U-ions on 208Pb (1998)
    Springer
    The European physical journal 2 (1998), S. 179-191 
    Details
    ISSN: 1434-601X
    Keywords: PACS:25.85.-w Fission reactions – 25.75.-q Relativistic heavy-ion collosions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: Fragments of relativistic 750 A.MeV U-projectiles were investigated by using the fragment separator FRS for magnetic selection of reaction products including ray-tracing and ΔE-ToF techniques. For elements between Ge and Sb, measurements of isotopic yield distributions and velocities revealed three processes: fragmentation, low-energy fission, and high-energy fission. The last of these regimes is presently reported. First and second moments of distributions of mass numbers, atomic numbers and velocities of the corresponding fragments allowed us to identify 101 43Tc56 as the most probable fragment of a high energy symmetric fission reaction. Moreover, we could deduce a hypothetical mean fissioning fragmentation product 208Rn and its highly excited pre-fragmentation parent 227Ra produced in a primary abrasion reaction at an excitation energy of about 290 MeV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100500050107
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  • 7
    Electronic Resource
    Electronic Resource
    Complications of extracorporeal shock wave lithotripsy using portable equipment: a multicenter study (1997)
    Springer
    Der Urologe 36 (1997), S. 217-221 
    Details
    ISSN: 1433-0563
    Keywords: Key words Extracorporeal shock wave lithotripsy • Complications • Mobile unit lithotripsy ; Schlüsselwörter Extrakorporale Stoßwellenlithotripsie • Komplikationen • Transportable ESWL
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Transportable Lithotripsiegeräte werden in zunehmendem Maße in urologischen Kliniken zur Harnsteinbehandlung eingesetzt, wenn kein festinstallierter Lithotriptor vorhanden ist bzw. eine solche Anschaffung als unrentabel angesehen wird. In der vorliegenden Studie wird überprüft, inwieweit die Komplikationsrate bei diskontinuierlicher Anwendung der ESWL mit transportablen Lithotripsiesystemen von den bekannten Komplikationsdichten aus etablierten Zentren verschieden ist. An bis zu 54 Kliniken wurde die Komplikationsrate bei diskontinuierlicher Anwendung transportabler Lithotripsiesysteme von 1993–1995 bei insgesamt 12 901 Therapien erfaßt. Schwerwiegende Komplikationen ergaben sich in insgesamt 85 Fällen (0,66 %). Die Mehrzahl davon (n = 64) waren intra- oder perirenale Hämatome; 3mal mußte nephrektomiert werden. Die Mortalität lag bei 0 %. Für die einzelnen Komplikationen lassen sich aus diesen Fallzahlen Wahrscheinlichkeiten ihres Auftretens berechnen. Insgesamt zeigt die Untersuchung, daß die ESWL mit mobilen Systemen mit der gleichen geringen Komplikationsrate angewendet werden kann, wie sie von etablierten Steinzentren bekannt ist.
    Notes: Summary An increasing number of urological departments are taking advantage of portable lithotripsy units if a system is not available in their clinic or purchase does not seem feasible; however, infrequent application of ESWL in such a setting should not increase the rate of complications. From 1993 to 1995, up to 54 urological departments using mobile lithotripsy units collected data concerning all major complications. A total of 12 901 treatments were performed which led to 85 major complications (0.66 %). Of them 64 were intrarenal or perirenal hematomas. There was no fatal complication. In three patients nephrectomy had to be performed subsequently. The probability of complications can be calculated according to these data. Overall, less frequent application of ESWL does not yield higher complication rates than those at ESWL centers where larger numbers of treatments are performed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001200050092
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  • 8
    Electronic Resource
    Electronic Resource
    Anhedonie – nosologieübergreifendes Korrelat einer Dysfunktion des dopaminergen Verstärkungssystems? (1999)
    Springer
    Der Nervenarzt 70 (1999), S. 391-398 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Anhedonie ; Dopaminerges Verstärkungssystem ; Negativsymptomatik ; „Incentive salience” ; Stimulus-induzierte Dopaminfreisetzung ; Key words Anhedonia ; Dopaminergic reward system ; Negative symptoms ; Incentive salience ; Stimulus-induced dopamine release
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The dopaminergic reward system is activated by primary rewarding factors such as food, sexual activity and parental care. Its activation enhences the occurency of behaviors which induced the stimulation of dopaminergic neurotransmission. Indications of a dysfunction of the dopaminergic reward system are found in major depression, schizophrenia, and addictive disorders. It has been hypothesized that dysfunction of the dopaminergic reward system is associated with anhedonia, the inability to experience pleasure. However, animal studies indicate that a reduction of central dopaminergic neurotransission is associated with a de- crease in incentive salience of reward-indi-cating stimuli and not with anhedonia per se. Sensitization of dopaminergic neurotransmission, on the other hand, seems to induce cue-dependent craving in addicted patients. In schizophrenia, phasic, stimulus-dependent dopamine release in the striatum may play a role in the abnormal attribution of salience to previously neutral stimuli.
    Notes: Zusammenfassung Das dopaminerge Verstärkungssystem wird durch sog. primäre Verstärker wie Essen, sexuelle Aktivität und elterliches Fürsorgeverhalten angesprochen. Seine Aktivierung führt zum gehäuften Auftreten all jener Verhaltensweisen, die zu seiner Stimulation beigetragen haben. Hinweise auf Störungen zentraler dopaminerger Transmission finden sich bei so unterschiedlichen Krankheitsbildern wie der majoren Depression, der Schizophrenie und bei Abhängigkeitserkrankungen. Damit stellt sich die Frage, ob Anhedonie, der „Verlust der Lebensfreude”, als nosologieübergreifendes Korrelat einer Dysfunktion des dopaminergen Verstärkungssystems auftritt. In Tierversuchen ergaben sich Hinweise darauf, daß eine verminderte dopaminerge Neurotransmission mit einer reduzierten Aufmerksamkeitszuwendung gegenüber belohnungsanzeigenden Stimuli und nicht mit Anhedonie per se assoziiert ist. Demgegenüber induziert eine Sensitivierung des dopaminergen Systems bei Abhängigkeitserkrankungen möglicherweise das stimulus-abhängige Verlangen nach der Suchtsubstanz. Eine Enthemmung der phasischen, stimulus-induzierten Dopaminfreisetzung im Striatum könnte auch in der Pathogenese der Schizophrenie von Bedeutung sein und dazu führen, daß bislang neutralen Stimuli eine besondere Bedeutung zugeschrieben wird.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050454
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  • 9
    Electronic Resource
    Electronic Resource
    Medikamentenindizierter Kopfschmerz (1999)
    Springer
    Der Schmerz 13 (1999), S. 304-314 
    Details
    ISSN: 1432-2129
    Keywords: Schlüsselwörter Medikamenteninduzierter Kopfschmerz ; Serotonin ; Migräne ; Depression ; Angsterkrankungen ; Key words Drug-induced headache ; Serotonin ; Migraine ; Depression ; Anxiety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The pathogenesis of drug abuse in patients suffering from drug-induced headache is not known in detail. It is unclear whether drug abuse in chronic daily headache should be classified as a form of drug dependence. Current findings concerning the neurobiological correlates of addictive behavior and affective disorders point to the importance of monoaminergic dysregulation, especially a dysfunction of central serotonergic neurotransmission. We reviewed the literature on drug-induced headache and examined hypothetical pathomechanisms of addiction. Drugs causing drug-induced headache such as paracetamol, coffein and ergotamine interfere with behavior patterns or neurotransmitter systems that are also affected by drugs of abuse. Several drugs that ameliorate acute headache interact with central serotonergic neurotransmission and may affect anxiety and depression in patients with chronic daily headache. Non human primate and human studies revealed mechanisms of serotonergic dysfunction in drug dependence, which may also be relevant for drug-abuse in medication-induced headache. Medication-induced dysfunction of monoaminergic, especially serotonergic neurotransmission, may affect drug dependence by exacerbating mood disorders. Further studies are necessary to assess serotonergic neurotransmission in patients with drug-induced headache and abuse of medication.
    Notes: Zusammenfassung Die Pathogenese des Medikamentenmißbrauchs bei chronischen Kopfschmerzen ist weitgehend unbekannt. Es ist unklar, ob es sich um eine typische Abhängigkeitserkrankung handelt und ob sich monoaminerge neurobiologische Störungen nachweisen lassen, die in vergleichbarer Form auch bei anderen Abhängigkeitssyndromen auftreten. Wir analysierten die vorliegende Literatur zu medikamenteninduzierten Kopfschmerzen im Hinblick auf Befunde zu möglichen neurobiologischen Mechanismen der Abhängigkeitsentwicklung. Schmerzmittel, Koffein und Ergotamine verursachen ähnliche Verhaltensauffälligkeiten oder wirken in vergleichbarer Weise auf monoaminerge Neurotransmittersysteme ein wie Suchtsubstanzen. Eigene bildgebende Untersuchungen zeigten eine Assoziation zwischen einer serotonergen Dysfunktion, affektiven Störungen und der Entwicklung abhängigen Verhaltens, die auch für die Entstehung der medikamenteninduzierten Kopfschmerzen relevant sein könnte. Medikamentös induzierte Störungen der monoaminergen, insbesondere der serotonergen Neurotransmission führen möglicherweise deshalb zur Abhängigkeitsentwicklung, weil sie affektive Störungen verstärken. Weitere Studien sind notwendig, um serotonerge Mechanismen der Entstehung und Aufrechterhaltung des Medikamentenmißbrauchs bei medikamenteninduzierten Kopfschmerzen zu überprüfen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004820050237
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  • 10
    Electronic Resource
    Electronic Resource
    Partial charge-changing cross sections for neutron-deficient isotopes from58Ni fragmentation (1995)
    Springer
    The European physical journal 352 (1995), S. 77-83 
    Details
    ISSN: 1434-601X
    Keywords: 21.10.Ft ; 25.70.Np ; 27.40.+z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract At the projectile-fragment separator FRS of GSI, relativistic secondary beams of about 520 MeV/nucleon were produced by fragmentation of a primary beam of58Ni at 650 MeV/nucleon in a beryllium target. By means of aΔE—Bρ—TOF measurement, the fragments were identified and their charge-changing probabilities in targets of (CH2) n , C, Al, and Pb placed at the exit of the FRS were determined. Whereas a first article dealt with the total charge-changing cross sections, we describe in this second article the element distributions of these secondary fragments, which are found to depend strongly on the isospin of the secondary projectile as well as on the target material. In the case of the lead target, the influence of the electromagnetic dissociation is clearly visible in the one-proton and two-proton removal channels. The preference for the formation of even-Z fragments is much more pronounced for exotic secondary projectiles than for projectiles close to stability. Calculations with a geometrical abrasion-ablation model allow to understand the global features of the experimental data. However, far from stability, the discrepancies between calculations and experimental data increase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01292762
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