Biomedical subjects

A Birkhahn

Publications and source records attributed to A Birkhahn.

5 recordsLinked to original sources

PubMed1996

Do etomidate and propofol influence oxygen radical production of neutrophils?

The effects of etomidate in an alcoholic vehicle and in a lipid-emulsion as well as those of propofol on N-formyl-methionyl-leucyl-phenylalanine (FMLP-) and zymosan-induced oxygen radical production of neutrophils were examined and compared with the effects of their respective vehicles. Furthermore free-radical scavenging capacities of these medications were investigated. The dose-response effects of etomidate, propofol and their respective vehicles on neutrophil function were tested by FMLP- and zymosan-induced chemiluminescence of neutrophils and, in addition, in a cell-free chemiluminescence system. Effects of commercial preparations of etomidate were generally not drug-specific but due to the vehicles and/or to unphysiologic osmolality values. Propofol impaired chemiluminescence of neutrophils in a drug-specific manner, even in the therapeutic concentration range. Free-radical scavenging contributed to this depression of chemiluminescence of neutrophils by propofol. Different composition of the lipid-emulsions of etomidate and propofol resulted in either a stimulation or suppression of chemiluminescence of neutrophils. Propofol but not etomidate impairs chemiluminescence of neutrophils drug-specifically. Besides a potential interaction with the neutrophils, free-radical scavenging accounts for this suppression.

Etomidate↗

PubMed1995

Stereoselective suppression of neutrophil function by ketamine?

The effects of the commercially available ketamine preparation (Ketanest), the ketamine racemate and of the two enantiomers, the R(-)-racemate and the S(+)-racemate, as well as its drug-free solvent were examined by N-formyl-methionyl-leucyl-phenylalanine-(FMLP)- and zymosan-induced oxygen radical production of polymorphonuclear cells (PMN). The racemate and the two enantiomers of ketamine suppressed FMLP- and zymosan-induced chemiluminescence of PMN in a dose-dependent fashion to the same extent. Therefore suppression of chemiluminescence of PMN by ketamine does not result from a specific receptor interaction.

Cell-Free System↗

PubMed1994

Do barbiturates impair zymosan-induced granulocyte function?

PURPOSE: The dose-response relationship of commercially available preparations of methohexital, pentobarbital, phenobarbital, and thiopental and their respective drug-free solutions on granulocyte function was investigated to evaluate whether suppression of neutrophil chemiluminescence is mediated by the barbiturates themselves or by their drug-free solutions. Furthermore, it was assessed whether suppression of chemiluminescence is due to an interaction mainly with neutrophils or to free radical scavenging. METHODS: The dose-response effects of the four barbiturates on granulocyte function were tested by zymosan-induced neutrophil chemiluminescence and, in addition, in a cell-free chemiluminescence system. RESULTS: Methohexital and pentobarbital did not influence zymosan-induced neutrophil chemiluminescence, whereas phenobarbital and thiopental decreased neutrophil chemiluminescence in a dose-dependent fashion. Nonphysiological osmolality (531 mosmol/kg) caused this impaired neutrophil chemiluminescence at the greatest concentration of phenobarbital. Thiopental solely suppressed neutrophil chemiluminescence drug specifically. Because thiopental also reduced chemiluminescence generated in a cell-free system, free radical scavenging might contribute to the impaired neutrophil chemiluminescence observed with thiopental. CONCLUSIONS: With the exception of thiopental, barbiturates do not impair oxygen radical production during phagocytosis of neutrophils.

Cell-Free System↗

PubMed1994

Do barbiturates and their solutions suppress FMLP-induced neutrophil chemiluminescence?

The dose-response relationship of four commercially available barbiturates (methohexitone, pentobarbitone, phenobarbitone and thiopentone) and of their drug-free solutions on the production of oxygen radicals by neutrophils were tested by N-formylmethionyl-leucyl-phenylalanine (FMLP)-induced granulocyte chemiluminescence and in a cell-free chemiluminescence system. Methohexitone had no effect on neutrophil chemiluminescence. Pentobarbitone, phenobarbitone and thiopentone dose-dependently decreased FMLP-induced chemiluminescence and cell-free chemiluminescence. Suppression of neutrophil chemiluminescence by pentobarbitone and phenobarbitone was due to effects of the drug-free solutions and an osmolality greater than 360 mosmol kg-1. Only thiopentone suppressed granulocyte chemiluminescence drug-specifically. The physicochemical properties of commercially available barbiturate preparations and their solutions, as well as free radical scavenging capacity, have to be considered if these preparations are used to evaluate drug-specific effects on the production of oxygen radicals by neutrophils.

Barbiturates↗

PubMed1993

Benzodiazepines and their solvents influence neutrophil granulocyte function.

We have examined the effects of commercially available preparations and drug-free solvents of diazepam (Valium, Diazepam-Lipuro) and midazolam (Dormicum) by N-formylmethionyl-leucylphenylalanine (FMLP)- and zymosan-induced polymorphonuclear cell (PMN) chemiluminescence and in a cell-free chemiluminescence system. In the case of Valium, drug-free solvent and diazepam suppressed PMN chemiluminescence. With Diazepam-Lipuro, the solvent stimulated and diazepam inhibited PMN chemiluminescence. With midazolam (Dormicum), only the active drug depressed PMN chemiluminescence. FMLP-induced PMN chemiluminescence was depressed 10-100 fold more by diazepam and midazolam than zymosan-induced chemiluminescence.

Diazepam↗