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  • 1
    ISSN: 1432-1912
    Keywords: Key words Gangliosides ; Retina ; Spreading depression ; Calcium homeostasis ; Migraine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gangliosides are amphiphilic, sialic acid-containing glycosphingolipids which are found preferentially in complex composition in the cellular membranes of the nervous system of vertebrates, including the vertebrate retina as well as in other membranes. They are always exposed to the extracellular side of the membranes. By virtue of the negative charges they carry at their headgroup, they contribute to the surface charge of the membrane and may affect ion distribution, mainly that of protons and calcium ions, at the outer side of the membranes. Using retinal spreading depression (RSD) as a tool, we show in this study that the addition of exogenous gangliosides to the extracellular space can change the state of excitability of the retinal tissue. In RSD experiments it reduces the propagation velocity as well as the intrinsic optical signal of RSD waves. These effects are concentration dependent (IC50 about 20 μM) and increase with the increasing negative charge of the ganglioside headgroup. As a possible mechanistic basis of the changes found, the change of the calcium homeostasis of the extracellular space by the exogenously added gangliosides is discussed. Gangliosides have been reported to be useful in the treatment of some neuropathological syndromes, including migraine, although experimental verification has not been possible up to now. Taking into account that the retina is a true part of the CNS, our data may be interpreted as the requested verification.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Herzschrittmachertherapie & Elektrophysiologie 11 (2000), S. II35 
    ISSN: 1435-1544
    Keywords: Key words Syncope – loop recorder – arrhythmias ; Schlüsselwörter Synkope – Looprekorder – Arrhythmien
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung: Bis zu 30% aller Menschen erleiden im Laufe ihres Lebens eine Synkope. Während die Prognose bei Patienten ohne strukturelle Herzerkrankung meist als gut beurteilt wird, zeigen zahlreiche Untersuchungen eine erhöhte Mortalität z. B. bei Patienten mit kardialen Synkopen und eingeschränkter Ventrikelfunktion. Die aus diesem Grunde erforderliche Diagnostik ist aufwendig und mit erheblichen Kosten verbunden. Sie führt jedoch meist nicht zur definitiven Klärung der Synkopenursache, da die Erhebung pathologischer Untersuchungsbefunde zeitgleich mit dem Auftreten der klinischen Symptome nur selten gelingt. Der Arzt ist daher bei der Interpretation der Befunde auf Analogschlüsse angewiesen. Auch nach umfassender Diagnostik mit nichtinvasiven und invasiven Methoden liegt der Anteil ungeklärter Synkopen heutzutage bei etwa 20%. In diesen Fällen soll mit dem implantierbaren Looprekorder eine Symptom-Rhythmus-Korrelation erzielt werden. Nach den ersten vorliegenden Daten bei Patienten mit rezidivierenden Präsynkopen und Synkopen, deren Ursache mittels konventioneller Diagnostik nicht geklärt werden konnte, ist der Nachweis oder Ausschluss einer rhythmogenen Synkope mit dem implantierbaren Looprekorder bei etwa 60% der Patienten möglich. Trotz der einfachen und wenig traumatischen Implantationsprozedur sollte jedoch das Auftreten lokaler Komplikationen nicht unterschätzt werden. Modellrechnungen zur Kosteneffektivität legen nahe, dass durch gezieltere Diagnostik unter Vermeidung wenig effektiver Tests und durch Steigerung des diagnostischen Nutzens die zusätzlichen Kosten für solche Systeme zumindest teilweise kompensiert werden können. Ein Looprekorder sollte daher bei Verdacht auf rezidivierende kardiale Synkopen möglichst frühzeitig eingesetzt werden. Die Entscheidung zwischen externem und implantierbarem Looprekorder ist abhängig von der Episodenhäufigkeit.
    Notes: Summary Up to 30% of the western population experience at least one syncope during their lifetime. The prognosis is considered to be good in patients without structural heart disease. However, for patients with cardiac syncope and impaired left ventricular function, incrased mortality rates were shown in several studies. Diagnostic procedures to clarify the underlying mechanism of syncope are both time and moneyconsuming. In addition, they do not always lead to a conclusive diagnosis because pathologic test results can rarely be documented parallel to the typical clinical symptoms. Therefore, physicians usually depend on assumptions to make a decision. Even today, after thorough invasive and noninvasive tests, 20% of patients with syncope remain undiagnosed. Insertable loop recorders were expected to obtain a close correlation between symptoms and arrhythmias particularly in these patients. First results with insertable loop recorders in patients with recurrent syncope or presyncope of unknown origin after conventional diagnostic procedures show an additional diagnostic yield of nearby 60% (proof or exclusion of arrhythmogenic syncope). Although the implantation procedure appears to be minimally traumatic, the rate of local complications should not be underestimated. Calculations of cost-effectiveness suggest that an increase in diagnostic yield and avoidance of less effective tests may at least partly compensate additional costs of the system. Loop recorders therefore should be taken into consideration early, when cardiac syncope is suspected. The decision between external and insertable devices only depends on episode frequency.
    Type of Medium: Electronic Resource
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