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  • 1975-1979  (4)
  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Two membrane fractions were obtained from electric organ tissue of the electric eel by sucrose gradient centrifugation of tissue homogenates. Electron microscopic examination showed that both fractions contained mainly vesicular structures (microsacs). Both the light and heavy fractions had a-bungarotoxin-binding capacity and Na+-K+ ATPase activity, while only the light fraction had AChE activity. The polypeptide patterns of vesicles derived from both the light and heavy fractions were examined by SDS-polyacrylamide gel electrophoresis and found to be very similar. The ratio of protein to phospholipid in the light vesicles was much lower than in the heavy vesicles, but the relative amounts of individual phospholipids in the two fractions were similar.A marked difference in the permeability of the light and heavy vesicles was observed by measuring efflux of both [14C]sucrose and 22Na+, and also by monitoring volume changes induced by changing the osmotic strength of the medium. All three methods showed the heavy vesicles to be much more permeable than the light ones. Only the light vesicles displayed increased sodium efflux in the presence of carbamylcholine.The AChE in the light fraction does not appear to be membrane-bound, but is rather a soluble enzyme, detached from the membrane during homogenization, which migrates on the gradient similarly to that of the light vesicles. This is supported by the fact that the bulk of the AChE is readily removed by washing the vesicles. Moreover, under the conditions employed in our sucrose gradient separations,‘native’14 S + 18 S AChE exists in the form of aggregates which migrate very similarly to the major peak of AChE activity of tissue homogenates.Separated innervated and non-innervated surfaces of isolated electroplax were obtained by microdissection. α-Bungarotoxin-binding capacity was observed only in the innervated membrane. About 80% of the AChE was in the innervated membrane, and about 70% of the Na+-K+ ATPase in the non-innervated membrane.The data presented indicate that the light and heavy vesicle fractions separated by sucrose gradient centrifugation are not derived exclusively from the innervated and non-innervated membranes respectively, as previously suggested by others, but contain membrane fragments from both sides of the electroplax. The separation of two populations on sucrose gradients may be explained both by the differences in permeability and in protein to phospholipid ratios.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 218 (1978), S. 137-144 
    ISSN: 1432-1459
    Keywords: Diphenylhydantoin ; Primidone ; Phenobarbital ; Plasma level ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Plasmakonzentration von Phenytoin wurde bei 45 Epileptikern, die nur dieses Medikament erhielten, bestimmt. Bei 20 weiteren Patienten, die auch Phenobarbital erhielten, wurde im Serum Dekonzentration der beiden Antiepileptika, bei 18 Patienten, die außerdem auch Primidon einnahmen, Dekonzentration der drei Medikamente bestimmt. Es wurde die Plasmakonzentration von Phenytoin auf die eingenommene Medikamentendosis bezogen und der Einfluß der gleichzeitigen Einnahme von Phenobarbital bzw. sowohl von Phenobarbital wie auch von Primidon auf die Phenytoinkonzentration analysiert. Aufgrund der eigenen Untersuchungsergebnisse können folgende Schlußfolgerungen gezogen werden: 1. Die Epileptiker können mit Bezug auf die Phenytoinkonzentration im Serum in zwei Gruppen unterteilt werden. In einer ersten Gruppe wird ein Gleichgewicht bei einem relativ hohen Phenytoinspiegel im Serum, bezogen auf eine bestimmte Medikamentendosierung, erreicht, in einer zweiten Gruppe besteht die Tendenz zu einer deutlich niedrigeren Plasmakonzentration bei gleicher Dosis. Beide Gruppen entsprechen ihrem Verhalten mathematisch einer exponentiellen Kurve, die für jede Gruppe spezifisch ist. 2. Bei gleichzeitiger Einnahme mit Phenytoin senkt Phenobarbital tendenzmäßig den Phenytoin-Plasmaspiegel. Aufgrund der vorgelegten Kurvenbilder kann man den zu erwartenden Phenytoinspiegel bei gleichzeitiger Verwendung beider Medikamente errechnen. 3. Wenn zusätzlich zum Phenytoin sowohl Primidone als auch Phenobarbital gegeben werden, senkt dies den Phenytoinspiegel weit mehr, als aus der alleinigen Gabe von Phenobarbital zu erwarten wäre.
    Notes: Summary The phenytoin plasma levels were measured in 45 epileptic patients whose only treatment was phenytoin. The plasma of 20 other patients receiving both phenytoin and phenobarbital was also tested for the concentration of these two drugs and 18 patients treated with phenytoin, phenobarbital and primidone were investigated in the same way. The results were used to calculate the plasma levels of phenytoin in relation to dosage and to measure the effect of the simultaneous use of phenobarbital on the phenytoin plasma levels and of primidone together with phenobarbital on phenytoin concentration. The results led to the following conclusions: The population of epileptic patients can be divided into 2 groups. In the first group the patients reach equilibrium at the relatively high phenytoin plasma level for a given dose of phenytoin, and in the second group the phenytoin plasma level tends to be significantly lower for parallel dosages. Both groups, in their behavior, obey mathematically an exponential graph specific for each group. Phenobarbital tends to lower the plasma phenytoin level when the two drugs are used simultaneously. It is also possible, by the graphs produced, to calculate the expected phenytoin plasma levels when using the drugs together. Primidone and phenobarbital together decrease the phenytoin level much more than expected from the effect of phenobarbital alone.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 31 (1975), S. 1401-1403 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Following 1 h exposure, the level of phospholipase A2 penetration into the axoplasm of the squid giant axon was 107 to 350% of that in the external media; corresponding values for phospholipase C were 18 to 31%. Phospholipases can therefore be used to study phospholipid function in axons since they can penetrate through connective tissue and Schwann cell to reach the axolemma.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 218 (1978), S. 137-144 
    ISSN: 1432-1459
    Keywords: Diphenylhydantoin ; Primidone ; Phenobarbital ; Plasma level ; Epilepsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Die Plasmakonzentration von Phenytoin wurde bei 45 Epileptikern, die nur dieses Medikament erhielten, bestimmt. Bei 20 weiteren Patienten, die auch Phenobarbital erhielten, wurde im Serum Dekonzentration der beiden Antiepileptika, bei 18 Patienten, die außerdem auch Primidon einnahmen, Dekonzentration der drei Medikamente bestimmt. Es wurde die Plasmakonzentration von Phenytoin auf die eingenommene Medikamentendosis bezogen und der Einfluß der gleichzeitigen Einnahme von Phenobarbital bzw. sowohl von Phenobarbital wie auch von Primidon auf die Phenytoinkonzentration analysiert. Aufgrund der eigenen Untersuchungsergebnisse können folgende Schlußfolgerungen gezogen werden: 1. Die Epileptiker können mit Bezug auf die Phenytoinkonzentration im Serum in zwei Gruppen unterteilt werden. In einer ersten Gruppe wird ein Gleichgewicht bei einem relativ hohen Phenytoinspiegel im Serum, bezogen auf eine bestimmte Medikamentendosierung, erreicht, in einer zweiten Gruppe besteht die Tendenz zu einer deutlich niedrigeren Plasmakonzentration bei gleicher Dosis. Beide Gruppen entsprechen ihrem Verhalten mathematisch einer exponentiellen Kurve, die für jede Gruppe spezifisch ist. 2. Bei gleichzeitiger Einnahme mit Phenytoin senkt Phenobarbital tendenzmäßig den Phenytoin-Plasmaspiegel. Aufgrund der vorgelegten Kurvenbilder kann man den zu erwartenden Phenytoinspiegel bei gleichzeitiger Verwendung beider Medikamente errechnen. 3. Wenn zusätzlich zum Phenytoin sowohl Primidone als auch Phenobarbital gegeben werden, senkt dies den Phenytoinspiegel weit mehr, als aus der alleinigen Gabe von Phenobarbital zu erwarten wäre.
    Notes: Summary The phenytoin plasma levels were measured in 45 epileptic patients whose only treatment was phenytoin. The plasma of 20 other patients receiving both phenytoin and phenobarbital was also tested for the concentration of these two drugs and 18 patients treated with phenytoin, phenobarbital and primidone were investigated in the same way. The results were used to calculate the plasma levels of phenytoin in relation to dosage and to measure the effect of the simultaneous use of phenobarbital on the phenytoin plasma levels and of primidone together with phenobarbital on phenytoin concentration. The results led to the following conclusions: The population of epileptic patients can be divided into 2 groups. In the first group the patients reach equilibrium at the relatively high phenytoin plasma level for a given dose of phenytoin, and in the second group the phenytoin plasma level tends to be significantly lower for parallel dosages. Both groups, in their behavior, obey mathematically an exponential graph specific for each group. Phenobarbital tends to lower the plasma phenytoin level when the two drugs are used simultaneously. It is also possible, by the graphs produced, to calculate the expected phenytoin plasma levels when using the drugs together. Primidone and phenobarbital together decrease the phenytoin level much more than expected from the effect of phenobarbital alone.
    Type of Medium: Electronic Resource
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