von Tanja Martens-Mantai
Statistik und Sichtungsnachweis dieser Seite findet sich am Artikelende
| [1.] Tmm/Fragment 011 01 - Diskussion Zuletzt bearbeitet: 2014-04-27 01:38:59 Hindemith | Fragment, Gesichtet, Granz 2009, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Tmm |
|
|
|
| Untersuchte Arbeit: Seite: 11, Zeilen: 1-3 |
Quelle: Granz 2009 Seite(n): 8, Zeilen: 7-9 |
|---|---|
| Given the widespread potential signalling capacities of Ca2+ waves, observations of the interactions between astrocytes and neurons in cell culture have suggested that Ca2+ waves play a role in SD initiation and propagation. | Given the widespread potential signaling [sic] capacities of Ca2+ waves, observations of the interactions between astrocytes and neurons in cell culture have suggested that Ca2+ waves play a role in SD initiation and propagation. |
The source is not mentioned. Here ends a longer passage of copied text, see previous page: Tmm/Fragment_010_01. |
|
| [2.] Tmm/Fragment 011 04 - Diskussion Zuletzt bearbeitet: 2014-04-25 09:18:07 Singulus | El Harrak 2009, Fragment, Gesichtet, KomplettPlagiat, SMWFragment, Schutzlevel sysop, Tmm |
|
|
|
| Untersuchte Arbeit: Seite: 11, Zeilen: 4-29 |
Quelle: El Harrak 2009 Seite(n): 9, 10, Zeilen: 9: 14ff; 10: 1ff |
|---|---|
| Widely accepted hypotheses hold that the primary event responsible for both the initiation and the propagation of SD is the release of some substance from neuronal elements to the extracellular compartment, which initially excites and then depresses adjacent neurons. The slowness of diffusion of the mediator would account for the low velocity of SD propagation. Among the substances proposed to mediate SD propagation are potassium (Grafstein, 1963; Bures et al., 1974) and excitatory amino acids (Fabricius et al., 1993). There are, however, observations that are difficult to reconcile with either of these two propositions.
SD had been interpreted as a composite process or a sequence of several linked events. To solve its genesis, a most important question concerns identification of the very first step in the chain reaction. In the extant literature, however, generally more attention has been given to the major depolarization and the attending extracellular potential shift than to the antecedent events. Among antecedents heralding the onset of SD that have been reported, are a slight increase of extracellular potassium, a small positive shift preceding the fast negative shift of the extracellular potential and several types of fast field activity including a short burst of action potentials or intense synaptic noise (Leao, 1944; Higashida et al., 1974). Even a silence of spontaneous or evoked activity has occasionally been described prior to other signs (Higashida et al., 1974). Not all of these early signs are obligatory prodromals of the large, accelerating, regenerative depolarization that is typical of the process. Even though the discharge of impulses is not required for the initiation or the propagation of SD, the impulse shower does regularly appear at its beginning. The mechanism that gives rise to the impulse discharge may well have a key role in the evolution of SD. The widely spread synchronization seems best explained by electrical continuity that could be provided by gap junctions. Effective communication by way of quasi-syncytial nets has been demonstrated in other systems, for example in the spread [of so-called calcium waves in cell cultures (Cornell- Bell et al., 1990).] |
Widely accepted hypotheses hold that the primary event responsible for both the initiation and the propagation of SD is the release of some substance from neuronal elements to the extracellular compartment, which initially excites and then depresses adjacent neurons. The slowness of diffusion of the mediator would account for the low velocity of SD propagation. Among the substances proposed to mediate SD propagation are potassium (Grafstein, 1963; Bures et al., 1974) and excitatory amino acids (Fabricius et al., 1993). There are, however, observations that are difficult to reconcile with either of these two propositions.
SD had been interpreted as a composite process or a sequence of several linked events. To solve its genesis, a most important question concerns identification of the very first step in the chain reaction. In the extant literature, however, generally more attention has been given to the major depolarization and the attending extracellular potential shift (AI’,)[sic] than to the antecedent events. Among antecedents heralding the onset of SD that have been reported, are [page 10] a slight increase of extracellular potassium, a small positive shift preceding the fast negative shift of the extracellular potential and several types of fast field activity including a short burst of action potentials or intense synaptic noise (Leao, 1944; Higashida et al., 1974). Even a silence of spontaneous or evoked activity has occasionally been described prior to other signs (Higashida et al., 1974). Not all of these early signs are obligatory prodromals of the large, accelerating, regenerative depolarization that is typical of the process. Even though the discharge of impulses is not required for the initiation or the propagation of SD, the impulse shower does regularly appear at its beginning. The mechanism that gives rise to the impulse discharge may well have a key role in the evolution of SD. The widely spread synchronization seems best explained by electrical continuity that could be provided by gap junctions. Effective communication by way of quasi-syncytial nets has been demonstrated in other systems, for example in the spread of so-called calcium waves in cell cultures (Cornell-Bell et al., 1990). |
The source is not mentioned. For an explanation why the given references are to fairly old literature, refer to Tmm/Dublette/Fragment 011 04. There one can also see, what "AI’," actually is supposed to stand for. |
|
Letzte Bearbeitung dieser Seite: durch Benutzer:Singulus, Zeitstempel: 20140425091848