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  • General Chemistry  (4)
  • Mice, Inbred C57BL  (2)
  • Rats, Sprague-Dawley  (2)
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  • 1
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    American Association for the Advancement of Science (AAAS)
    Publikationsdatum: 2002-02-09
    Beschreibung: Light synchronizes mammalian circadian rhythms with environmental time by modulating retinal input to the circadian pacemaker-the suprachiasmatic nucleus (SCN) of the hypothalamus. Such photic entrainment requires neither rods nor cones, the only known retinal photoreceptors. Here, we show that retinal ganglion cells innervating the SCN are intrinsically photosensitive. Unlike other ganglion cells, they depolarized in response to light even when all synaptic input from rods and cones was blocked. The sensitivity, spectral tuning, and slow kinetics of this light response matched those of the photic entrainment mechanism, suggesting that these ganglion cells may be the primary photoreceptors for this system.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Berson, David M -- Dunn, Felice A -- Takao, Motoharu -- EY12793/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 2002 Feb 8;295(5557):1070-3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neuroscience, Brown University, Providence, RI, 02912 USA. David_Berson@brown.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11834835" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Axons/ultrastructure ; *Biological Clocks ; *Circadian Rhythm ; Dendrites/ultrastructure ; Isoquinolines ; Kinetics ; Light ; *Light Signal Transduction ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley ; Retinal Ganglion Cells/chemistry/cytology/*physiology ; Rod Opsins/analysis/physiology ; Suprachiasmatic Nucleus/cytology/*physiology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2008-04-25
    Beschreibung: Rod and cone photoreceptors detect light and relay this information through a multisynaptic pathway to the brain by means of retinal ganglion cells (RGCs). These retinal outputs support not only pattern vision but also non-image-forming (NIF) functions, which include circadian photoentrainment and pupillary light reflex (PLR). In mammals, NIF functions are mediated by rods, cones and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Rod-cone photoreceptors and ipRGCs are complementary in signalling light intensity for NIF functions. The ipRGCs, in addition to being directly photosensitive, also receive synaptic input from rod-cone networks. To determine how the ipRGCs relay rod-cone light information for both image-forming and non-image-forming functions, we genetically ablated ipRGCs in mice. Here we show that animals lacking ipRGCs retain pattern vision but have deficits in both PLR and circadian photoentrainment that are more extensive than those observed in melanopsin knockouts. The defects in PLR and photoentrainment resemble those observed in animals that lack phototransduction in all three photoreceptor classes. These results indicate that light signals for irradiance detection are dissociated from pattern vision at the retinal ganglion cell level, and animals that cannot detect light for NIF functions are still capable of image formation.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871301/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871301/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guler, Ali D -- Ecker, Jennifer L -- Lall, Gurprit S -- Haq, Shafiqul -- Altimus, Cara M -- Liao, Hsi-Wen -- Barnard, Alun R -- Cahill, Hugh -- Badea, Tudor C -- Zhao, Haiqing -- Hankins, Mark W -- Berson, David M -- Lucas, Robert J -- Yau, King-Wai -- Hattar, Samer -- R01 DC006904/DC/NIDCD NIH HHS/ -- R01 DC006904-01/DC/NIDCD NIH HHS/ -- R01 DC006904-02/DC/NIDCD NIH HHS/ -- R01 DC006904-03/DC/NIDCD NIH HHS/ -- R01 DC006904-04/DC/NIDCD NIH HHS/ -- R01 EY006837/EY/NEI NIH HHS/ -- R01 EY006837-16A1/EY/NEI NIH HHS/ -- R01 EY006837-18/EY/NEI NIH HHS/ -- R01 EY006837-20A1/EY/NEI NIH HHS/ -- R01 EY006837-21/EY/NEI NIH HHS/ -- R01 EY014596/EY/NEI NIH HHS/ -- R01 EY014596-01/EY/NEI NIH HHS/ -- R01 EY014596-02/EY/NEI NIH HHS/ -- R01 EY014596-03/EY/NEI NIH HHS/ -- R01 EY014596-04/EY/NEI NIH HHS/ -- R01 EY014596-05/EY/NEI NIH HHS/ -- R01 EY014596-06/EY/NEI NIH HHS/ -- R01 EY017137/EY/NEI NIH HHS/ -- R01 GM076430/GM/NIGMS NIH HHS/ -- R01 GM076430-01/GM/NIGMS NIH HHS/ -- R01 GM076430-02/GM/NIGMS NIH HHS/ -- R01 GM076430-03/GM/NIGMS NIH HHS/ -- R01 GM076430-04/GM/NIGMS NIH HHS/ -- R01 GM076430-05/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 May 1;453(7191):102-5. doi: 10.1038/nature06829. Epub 2008 Apr 23.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18432195" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; Brain/cytology/metabolism ; Circadian Rhythm/physiology/radiation effects ; Cues ; Electroretinography ; Light ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Motor Activity/physiology ; Pupil/physiology/radiation effects ; Reflex/physiology/radiation effects ; Retinal Cone Photoreceptor Cells/*metabolism ; Retinal Ganglion Cells/*cytology/*metabolism ; Retinal Rod Photoreceptor Cells/*metabolism ; Rod Opsins/deficiency/genetics/*metabolism ; Vision, Ocular/*physiology/radiation effects ; Visual Acuity/physiology
    Print ISSN: 0028-0836
    Digitale ISSN: 1476-4687
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2010-06-26
    Beschreibung: Chronic exposure to drugs of abuse induces countless modifications in brain physiology. However, the neurobiological adaptations specifically associated with the transition to addiction are unknown. Cocaine self-administration rapidly suppresses long-term depression (LTD), an important form of synaptic plasticity in the nucleus accumbens. Using a rat model of addiction, we found that animals that progressively develop the behavioral hallmarks of addiction have permanently impaired LTD, whereas LTD is progressively recovered in nonaddicted rats maintaining a controlled drug intake. By making drug seeking consistently resistant to modulation by environmental contingencies and consequently more and more inflexible, a persistently impaired LTD could mediate the transition to addiction.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kasanetz, Fernando -- Deroche-Gamonet, Veronique -- Berson, Nadege -- Balado, Eric -- Lafourcade, Mathieu -- Manzoni, Olivier -- Piazza, Pier Vincenzo -- New York, N.Y. -- Science. 2010 Jun 25;328(5986):1709-12. doi: 10.1126/science.1187801.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉INSERM U862, NeuroCentre Magendie, 147 Rue Leo Saignat, 33077, Bordeaux Cedex, France.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20576893" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Animals ; *Behavior, Addictive ; Cocaine/administration & dosage ; Cocaine-Related Disorders/*physiopathology ; Disease Models, Animal ; Glutamic Acid/metabolism ; *Long-Term Synaptic Depression ; Nucleus Accumbens/*physiopathology ; Rats ; Rats, Sprague-Dawley ; Receptors, Metabotropic Glutamate/metabolism ; Receptors, N-Methyl-D-Aspartate/metabolism ; Self Administration ; Synaptic Transmission
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2003-01-11
    Beschreibung: In the mammalian retina, a small subset of retinal ganglion cells (RGCs) are intrinsically photosensitive, express the opsin-like protein melanopsin, and project to brain nuclei involved in non-image-forming visual functions such as pupillary light reflex and circadian photoentrainment. We report that in mice with the melanopsin gene ablated, RGCs retrograde-labeled from the suprachiasmatic nuclei were no longer intrinsically photosensitive, although their number, morphology, and projections were unchanged. These animals showed a pupillary light reflex indistinguishable from that of the wild type at low irradiances, but at high irradiances the reflex was incomplete, a pattern that suggests that the melanopsin-associated system and the classical rod/cone system are complementary in function.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lucas, R J -- Hattar, S -- Takao, M -- Berson, D M -- Foster, R G -- Yau, K-W -- R01 EY006837/EY/NEI NIH HHS/ -- R01 EY006837-16A1/EY/NEI NIH HHS/ -- R01 EY014596/EY/NEI NIH HHS/ -- R01 EY014596-01/EY/NEI NIH HHS/ -- R37 EY006837/EY/NEI NIH HHS/ -- R37 EY006837-13/EY/NEI NIH HHS/ -- R37 EY006837-14/EY/NEI NIH HHS/ -- R37 EY006837-15/EY/NEI NIH HHS/ -- R37 EY006837-15S1/EY/NEI NIH HHS/ -- New York, N.Y. -- Science. 2003 Jan 10;299(5604):245-7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Integrative and Molecular Neuroscience, Division of Neuroscience and Psychological Medicine, Faculty of Medicine, Imperial College London, Charing Cross Campus, St. Dunstans Road, London W6 8RF, UK. r.j.lucas@ic.ac.uk〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12522249" target="_blank"〉PubMed〈/a〉
    Schlagwort(e): Adaptation, Ocular ; Animals ; Carbachol/pharmacology ; Circadian Rhythm ; Darkness ; *Light ; Light Signal Transduction ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Olivary Nucleus/cytology/physiology ; Phenotype ; Photoreceptor Cells, Vertebrate/physiology ; Pupil/drug effects/*physiology ; *Reflex, Pupillary ; Retinal Degeneration/genetics/physiopathology ; Retinal Ganglion Cells/*physiology ; Rod Opsins/*genetics/*physiology ; Suprachiasmatic Nucleus/physiology
    Print ISSN: 0036-8075
    Digitale ISSN: 1095-9203
    Thema: Biologie , Chemie und Pharmazie , Informatik , Medizin , Allgemeine Naturwissenschaft , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 108 (1996), S. 2922-2937 
    ISSN: 0044-8249
    Schlagwort(e): Aromatizität ; Chemiegeschichte ; Hückel ; Erich ; Pericyclische Reaktionen ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Zwischen 1930 und 1937 kamen von Erich Hückel, einem theoretisch arbeitenden Physiker, mit den quantenmechanischen Beschreibungen ungesättigter und konjugierter Moleküle wesentliche Beiträge zur Organischen Chemie. Hier folgt einem kurzen Überblick über seine wissenschaftliche Laufbahn aus der Sicht eines Organikers eine vereinfachte Darstellung der stark approximativen theoretischen Methoden, die er verwendete. Für cyclische Moleküle der Klasse CnHn ist die Aussage, daß im Fall von (4N + 2) π-Elektronen (N = 0,1,2,…) abgeschlossene Schalen vorliegen, von besonderer Bedeutung. Die Analyse von Schlüsselanwendungen der Ideen Hückels zeigt, wie sie schließlich die Erforschung neuer Gebiete in der organischen Synthese und bei organischen Reaktionsmechanismen anregten. Ein weiterer bedeutsamer (aber bis vor kurzem kaum beachteter) Beitrag von Hückel war die Erkenntnis, daß die Konnektivität der Atome ein entscheidender Faktor für die Spinmultiplizität in Nicht-Kekulé-Molekülen ist. Sie liefert, wie jüngere theoretische und experimentelle Befunde bestätigen, im Prinzip eine Basis für die Voraussage von Verstößen gegen die Hundsche Regel. Darüber hinaus werden die Wechselwirkung von Experimenten mit den unterschiedlichen Ausprägungen der Quantentheorie und die Auswirkung dieser Wechselwirkung auf die Entwicklung der Chemie kurz betrachtet. Schließlich werden Mutmaßungen angestellt, warum das Werk Hückels jahrzehntelang einen so geringen Einfluß auf die Organische Chemie ausübte, bis man endlich anfing, seine Bedeutung zu erkennen.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 80 (1968), S. 765-777 
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Bei vielen Carboniumionen-Umlagerungen, die in Lösung über mehrere aufeinander-folgende Zwischenstufen verlaufen, bestimmt die stereochemische Konfiguration am Ausgangspunkt der Heterolyse zwei Reaktionsschritte später die Spezifität der Wanderung. Diese Erinnerungseffekte (memory effects) können kleinen, bislang unbeobachtbaren Minima in der Energieoberfläche zugeschrieben werden. Durch Markierungsmethoden aller Art wird gezeigt, daß Erinnerungseffekte allgemein bei der Bildung bicyclischer Carboniumionen durch Ringerweiterung auftreten. Die Zwischenstufen bei diesen Reaktionen verhalten sich unsymmetrisch, obwohl sie im Gleichgewichtszustand notwendigerweise symmetrisch oder quasi-symmetrisch sind. Der Erinnerungseffekt benutzt die Geschwindigkeit einer intramolekularen Carboniumionen-Umlagerung als Bezugsgröße, mit der die Geschwindigkeit der Symmetrieeinstellung verglichen wird. Auf diese Weise dient das System zum Nachweis von Subspezies.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 35 (1996), S. 2750-2764 
    ISSN: 0570-0833
    Schlagwort(e): aromaticity ; history of chemistry ; Hückel ; Erich ; pericyclic reactions ; Aromaticity ; History of chemistry ; Hückel, Erich ; Pericyclic reactions ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the period between 1930 and 1937, Erich Hückel, a theoretical physicist, made profound contributions to organic chemistry in his quantum mechanical descriptions of unsaturated and conjugated compounds. A brief account of his academic career is followed by simplified expositions, from the point of view of an organic chemist, of the highly approximate theoretical methods he used. Of special significance in the case of cyclic molecules of the class CnHn is the concept of filled shells when the number of π electrons is (4 N + 2) (N = 0,1,2,…). Examinations of key applications of Hückel's ideas reveal how they eventually motivated the exploration of new fields in organic synthesis and organic reaction mechanism. Another significant (but until recently, virtually ignored) contribution by Hückel was the recognition that atomic connectivity is a strong determinant of spin multiplicity in non-Kekulé molecules. This idea provides, in principle, a basis for predicting violations of Hund's rule, as recent computational and experimental developments confirm. The interaction of experiment with different styles of quantum theory, and the impact of this relationship on the development of chemistry, are briefly considered. Speculations are given on why Hückel's work exerted so little influence on organic chemistry for decades before its importance finally began to be recognized.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 7 (1968), S. 779-791 
    ISSN: 0570-0833
    Schlagwort(e): Memory effects ; Stereochemistry ; Rearrangement ; Carbocations ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The stereochemical configuration at the initial site of heterolysis in a carbonium ion process in solution controls the specificity of migration two steps later in many sequential multiple rearrangements. These “memory effects” are attributable to the presence on the potential energy surface of small, hitherto undetectable minima. A variety of structural, stereochemical, and isotopic marking techniques are used to demonstrate that memory effects are a general feature of the ring-expansion route to bicyclic carbonium ions. The intermediates formed in these reactions, although necessarily symmetrical or quasi-symmetrical at equilibrium, act unsymmetrically. The memory effect uses the rate of an intramolecular carbonium ion rearrangement as a calibration with which to compare the rate of symmetrization. In this way, the system functions as a sensor of sub-species.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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