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Biomedical subjects

K Brune

Publications and source records attributed to K Brune.

At least 19 recordsLinked to original sources
PubMed1996

Stereospecific determination of tiaprofenic acid in plasma: problems with drug degradation.

A sensitive stereospecific high-performance liquid chromatographic assay for the quantification of tiaprofenic acid in human plasma was developed. The procedure involved extraction of tiaprofenic acid from acidified plasma into hexanediethyl ether (8:2, v/v). Stereospecific separation was achieved with a prepacked alpha1-acid glycoprotein column without derivatization. The mobile phase consisted of 2% 2-propanol in 0.01 M phosphate buffer, pH 6.5. Tiaprofenic acid was detected at 317 nm. The limit of quantification was found to be 25 ng/ml for each enantiomer using a 0.5 ml plasma sample. The assay was reproducible and accurate to be applied to the stereoselective pharmacokinetic analysis of tiaprofenic acid in plasma. Because of photoinstability of tiaprofenic acid plasma sampling and sample extraction should be performed under light protection.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1995

2-Arylpropionyl-CoA epimerase: partial peptide sequences and tissue localization.

The R-enantiomers of 2-arylpropionic acids (2-APAs) such as ibuprofen (IBU) exhibit the phenomenon of species- and substrate-dependent metabolic chiral inversion. Only R-enantiomers are activated to acyl-CoA-thioesters by an acyl-CoA-synthetase via an adenylate intermediate. The acyl-CoA-thioesters are substrates for an epimerase, which is responsible for chiral inversion. A 42 kDa epimerase from the cytosolic fraction of rat livers was isolated and purified to homogeneity. Polyclonal antibodies were raised against the epimerase in rabbits. The anti-epimerase antibodies were used for affinity column chromatography to separate homogeneous protein for amino acid sequence analysis. Sequence data analysis of 3 internal peptide sequences showed 50% and more homology with regions of enzymes involved in fatty acid metabolism. The polyclonal anti-epimerase antibodies were used to analyze the tissue distribution of the in guinea pigs and rats by Western blot analysis. Furthermore, the correlation of inversion enzyme activity in various tissues under comparable incubation conditions and cross-reactivity in Western blot analysis was investigated.

Amino Acid Sequence↗
PubMed1995

Cyclophilin-A is a zinc-dependent DNA binding protein in macrophages.

The association of cyclosporin A (CsA) immunosuppression with inhibition of transcription factor-dependent lymphokine gene activation formed the basis of our decision to investigate nuclear-associated Cyp isoforms. Immunofluorescence microscopy of mouse macrophages cell line with a monoclonal antibody mAb7F1 raised against CypA shows a co-localisation of CypA in the nucleus and in the cytosol. Nuclear CypA binds to DNA in a zinc ion-dependent manner, in contrast to recombinant CypB. Peptidyl-prolyl cisltrans isomerase (PPIase) activity of nuclear CypA is inhibited by zinc ions. The zinc inhibited CypA does not bind cyclosporin A (CsA). We suggest that nuclear Cyp in complex with zinc ions recognizes DNA sequences and is involved in transcription modulating processes.

Amino Acid Isomerases↗
PubMed1995

Activation of Ca2+ signaling in neutrophils by the mast cell-released immunophilin FKBP12.

The immunophilins of the FK506-binding protein (FKBP) family are intracellular proteins that bind the immunosuppresants FK506 and rapamycin. In this study we show that HMC-1 mast cells sensitized with IgE release FKBP12 upon stimulation with anti-IgE. The release is rapid and not affected by actinomycin D or cycloheximide, suggesting that it is due to exocytosis from a storage compartment. FKBP12 from HMC-1 mast cells exhibits biological activity. When applied extracellularly to human neutrophils, it induces transient changes in the intracellular Ca2+ concentration ([Ca2+]i) due to Ca2+ release from intracellular stores. Inhibition of [Ca2+]i changes by ruthenium red and ryanodine indicates that ryanodine receptor/Ca2+ release channels are involved in FKBP12-induced Ca2+ signaling. Neutrophil activation by mast cell-derived FKBP12 is prevented by complexing FKBP12 with FK506 or rapamycin. These results demonstrate that extracellular FKBP12 functions as a cytokine in cell-to-cell communication. They further suggest a pathophysiological role for FKBP12 as a mediator in immediate or type I hypersensitivity and may have implications for novel therapeutic strategies in the treatment of allergic disorders with FK506 and rapamycin.

Amino Acid Sequence↗
PubMed1995

Inflammatory models of cutaneous hyperalgesia are sensitive to effects of ibuprofen in man.

A new experimental procedure was developed to quantify the analgesic actions of non-steroidal anti-inflammatory drugs (NSAIDs) in healthy human subjects. In order to mimic the clinical situation, the drug was 'therapeutically' administered 1 day after induction of inflammation by freezing a small skin area. The procedure was easily tolerated and led to a marked hyperalgesia without ongoing pain which was tested using mechanical impact stimulation and magnitude estimation. For comparison, we used a previously established model of repeated noxious pinching of an interdigital skin web which induces a hyperalgesia to pressure (rated via visual analogue scale), and topical application of capsaicin which leads to quantifiable flare and allodynia responses. The effects of a cumulative drug regime of ibuprofen in 2 different doses (3 x 400 mg and 3 x 800 mg at 2-h intervals) were tested versus placebo using a double-blind cross-over design with 24 volunteers of either gender. Ibuprofen caused a significant suppression of the hyperalgesia to repeated pinching and of the hyperalgesia to impact stimulation following freeze trauma. In contrast, there was no effect on the areas of flare and allodynia induced by capsaicin application and on the impact evoked sensations from untreated skin. The two dosages of ibuprofen, however, appeared to be equally effective in a way that suggests a plateauing of the antihyperalgesic effect. The two models in which hyperalgesia is affected by ibuprofen, i.e., repeated pinching and impact stimulation after freeze trauma, seem to provide comparable sensitivity. The freeze model may in the future have the advantage to allow for a better temporal resolution of the drug's action profile.

Adult↗
PubMed1995

Pharmacokinetics of ketoprofen enantiomers after different doses of the racemate.

The pharmacokinetics of the enantiomers of ketoprofen after oral administration of 12.5 mg, 25 mg and 50 mg and i.v. administration of 50 mg racemic ketoprofen to 24 healthy subjects were investigated. The AUC values of R- (r2 = 0.929) and S-ketoprofen (r2 = 0.930) were proportional to dose. The absolute bioavailability of the 50 mg oral dose was 84.5 (s.d. 20.6) % and 81.4 (18.0) % for R-ketoprofen and S-ketoprofen, respectively. With the exception of AUC values no dose dependent differences in pharmacokinetic parameters were observed. However, the R-enantiomer had higher AUC, lower clearance data and higher Cmax values than the S-form after oral administration. The results suggest that stereochemical and pharmacokinetic considerations cannot explain the lack of dose response observed with ketoprofen doses below 50 mg.

Administration, Oral↗
PubMed1995

Effects of flurbiprofen enantiomers on pain-related chemo-somatosensory evoked potentials in human subjects.

1. The aim of the study was to investigate the analgesic effects of flurbiprofen enantiomers using an experimental pain model based on both chemo-somatosensory event-related potentials (CSSERP) and subjective pain ratings. 2. Healthy female volunteers (n = 16, age 23-36 years) participated in a placebo-controlled, randomised, double-blind, four-way crossover study. Single doses of (S)-flurbiprofen (50 mg), (R)-flurbiprofen (50 and 100 mg) and placebo were administered orally. Measurements were taken before and 2 h after administration of the medications. During each measurement, 32 painful stimuli of gaseous carbon dioxide (200 ms duration, interval approximately 30 s) of two concentrations (60 and 65% CO2 v/v) were applied to the right nostril. EEG was recorded from five positions and CSSERP were obtained in response to the painful CO2- stimuli. Additionally, subjects rated the perceived intensity of the painful stimuli by means of a visual analogue scale (VAS). 3. The CSSERP-amplitude P2, a measure of analgesic effect, decreased after administration of both (R)- and (S)-flurbiprofen, while it increased after placebo. This was statistically significant at recording positions C4 (P < 0.01) and Fz (P < 0.05). The analgesia-related decreases in evoked potential produced by (R)-flurbiprofen were dose-dependent. Comparing similar doses of (R)- and (S)-flurbiprofen, the decrease in CSSERP-amplitudes produced by the (S)-enantiomer was somewhat more pronounced, indicating a higher analgesic potency. 4. The present data indicate that both enantiomers of flurbiprofen produce analgesic effects. Since (R)-flurbiprofen caused only little toxicity in rats as compared with the (S)-enantiomer or the racemic compound, a reduction of the quantitatively most important side effects in the gastrointestinal tract might be achieved by employing (R)-flurbiprofen in pain therapy.

Adult↗
PubMed1995

Distribution of extracellular matrix proteins in indomethacin-induced lesions in the rat stomach.

INTRODUCTION: We investigated the distribution of extracellular matrix (ECM) proteins in indomethacin-induced lesions of the rat stomach. METHOD: Twenty rats received indomethacin orally at a dose of 8 mg/kg/body weight. The animals were killed at 3, 6, 12, 24, and 48 h after administration of the drug. The stomachs were removed and frozen in liquid nitrogen. Cryostat serial sections of the lesions were immunostained with antibodies to collagen III, IV, and VI, laminin, and fibronectin. RESULTS: Fibronectin was the dominant extracellular protein of the provisional ECM in deep gastric lesions and gastric ulcers. Collagen III was strongly positive in stromal cells under the necrotic material in gastric erosions. Basal membrane proteins (collagen IV and laminin) were found to originate from the muscularis mucosae at the ulcer edge. CONCLUSION: There is a typical distribution of ECM proteins in erosions and ulcers of the rat stomach. Fibronectin was most prominent in the provisional matrix of gastric erosions and ulcers.

Animals↗
PubMed1995

Antinociceptive effects of R(-)- and S(+)-flurbiprofen on rat spinal dorsal horn neurons rendered hyperexcitable by an acute knee joint inflammation.

The antinociceptive effects of the S(+)-enantiomer of flurbiprofen (potent inhibitor of cyclooxygenase) and the R(-)-enantiomer (500 times less potent) were investigated in the spinal cord of 20 anesthetized rats. In lumbar segments, 20 wide-dynamic-range dorsal horn neurons with knee joint input were recorded extracellularly. After induction of an acute inflammation in the knee joint by kaolin and carrageenan, the neurons developed hyperexcitability consisting of enhanced responses to stimuli applied to the inflamed knee and the noninflamed ankle and an expansion of receptive fields. Intravenous administration of R(-)-flurbiprofen (1-9 mg/kg) and S(+)-flurbiprofen (0.3-9 mg/kg) at 5.5 to 8.5 h after kaolin, dose dependently reduced the neurons' responses to pressure applied to the inflamed knee (18 of 18 neurons) and the noninflamed ankle (17 of 17 neurons) and paw (8 of 8 neurons). R(-)-flurbiprofen decreased the receptive field size in 8 of 16 neurons, S(+)-flurbiprofen in 10 of 16 neurons. The suppressive effects started 3 to 6 min and reached a maximum 9 to 15 min after i.v. administration. S(+)-flurbiprofen was more potent than the R(-)-enantiomer. When injected directly into the knee joint, S(+)-flurbiprofen (50 and 80 micrograms), but not the R(-)-enantiomer (100 and 180 micrograms) reduced the hyperexcitability in 12 of 12 neurons. These results suggest a central site of antinociceptive action for R(-)-flurbiprofen and S(+)-flurbiprofen and an additional peripheral site for S(+)-flurbiprofen. The doses used in these experiments did not produce any sedative effects in rats subjected to behavioral testing.

Analgesics↗
PubMed1995

EEG analysis and pharmacodynamic modelling after intravenous bolus injection of eltanolone (pregnanolone).

An intravenous bolus dose of 0.75 mg Kg-1 eltanolone emulsion was administered to 18 unpremedicated ASA I or II patients. In addition to clinical observation and haemodynamic monitoring, EEG power spectrum and median frequency were recorded. Venous blood was collected to establish a concentration-effect relation using the median frequency as a pharmacodynamic parameter for hypnotic effect, and with analysis of data with the sigmoidal Emax model. Emax was determined as the maximal decrease of the median frequency caused by the CNS depressant effect of eltanolone. The results of seven of 15 patients with complete serum and EEG analysis could be described by a sigmoidal curve. The calculated IC50, the serum concentration producing 50% inhibition of Emax, was 0.57 micrograms mL-1. Median frequency occasionally decreased independently of eltanolone serum concentration in seven patients because interference by natural sleep was not prevented before induction or during awakening by setting continuous stimulations. In relation to the peak serum concentration, the decrease in median frequency occurred late in one patient. Nevertheless, the present study provides a preliminary estimation of the IC50 of eltanolone. From the clinical point of view, eltanolone showed satisfactory induction characteristics which warrant further evaluation.

Adolescent↗
PubMed1994

Modulation of nitric oxide effects by flurbiprofen enantiomers and nefopam and its relation to antinociception.

We have examined the interactions of the analgesics, R- and S-flurbiprofen and nefopam, with nitric oxide (NO) in several experimental systems. Phenylephrine-precontracted rat aortic strips with intact endothelium were relaxed by R- and S-flurbiprofen and nefopam in a concentration-dependent manner. Removal of endothelium, inhibition of guanylate cyclase, inhibition of NO biosynthesis and inactivation of NO significantly reduced these relaxations. R- and S-flurbiprofen as well as nefopam enhanced the inhibition of platelet aggregation caused by rat peritoneal neutrophils or 3-morpholinosydnonimine. The antinociceptive effects of R- and S-flurbiprofen in the mouse writhing test as well as those of nefopam in the hot plate test were not significantly affected by administration of NO synthase inhibitors. We conclude that the increase in the biological activity of NO by R- and S-flurbiprofen and nefopam does not play a major role in the antinociceptive activity of the drugs, but might contribute to acute hypotension, a side-effect occasionally seen with flurbiprofen and nefopam.

Analgesics↗
PubMed1994

Is the formation of R-ibuprofenyl-adenylate the first stereoselective step of chiral inversion?

Coenzyme A thioester formation is reported to be the first step of chiral inversion of R-ibuprofen. In order to investigate the mechanism of this reaction adenylate derivatives of the ibuprofen enantiomers were synthesized chemically. R- and S-ibuprofenyl-adenylates as well as free acids were incubated with rat liver mitochondria in the presence of coenzyme A, MgCl2 with or without ATP. The optical antipodes formed by inversion and the coenzyme A thioester derivatives of both enantiomers were found after incubation of both R- or S-ibuprofenyl-adenylate and R-ibuprofen. By contrast, after incubation with S-ibuprofen neither R-enantiomer nor coenzyme A thioesters were detected. These experiments suggest that the formation of R-ibuprofenyl-adenylate may be the first stereoselective step of chiral inversion.

Animals↗
PubMed1994

Opioid receptor agonist potencies of morphine and morphine-6-glucuronide in the guinea-pig ileum.

It has been suggested that morphine-6-glucuronide, a major metabolite of the opioid analgesic morphine, is more potent as an analgesic than the parent drug. This finding appears not to be due to differences in affinity for opioid receptors. Therefore, in the present study the opioid receptor mediated effects of morphine and morphine-6-glucuronide were compared in vitro using electrically induced contractions of isolated guinea-pig ilea in the absence and presence of increasing concentrations of the selective opioid receptor antagonists CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2) (mu) and norbinaltorphimine (kappa). The results showed a similar efficacy and potency for morphine and morphine-6-glucuronide and indicated that both compounds act reversibly, mainly at mu-opioid receptors. It is concluded that morphine and its metabolite morphine-6-glucuronide are equipotent at mu-opioid receptors.

Amino Acid Sequence↗
PubMed1994

Is the inversion from R- to S-ketoprofen concentration dependent? Investigations in rats in vivo and in vitro.

The effects of dose on the pharmacokinetics of ketoprofen (KT) enantiomers were investigated in rats in vivo and in hepatoma cells in continuous culture in vitro following administration of the optically pure enantiomers and the racemate of KT. With the exception of AUC (area under the curve) no pharmacokinetic differences could be found following i.v. administration of various doses of KT enantiomers (2.5, 5 and 10 mg/kg) and of racemic KT (5, 10 and 20 mg/kg) and between single enantiomer and racemate administration in rats in vivo. Independent of the dose administered the fraction inverted was about 66%. In line with the findings in vivo good correlation between incubation concentration and AUC of R- and S-KT was found in the hepatoma cells in vitro. The ratios of AUC(S)/AUC(R) were not significantly affected by concentration after R-KT (2.5-20 micrograms/mL) and racemate incubation (5-40 micrograms/mL) in the concentration ranges investigated. However, unlike in rats in vivo enhanced inversion was observed following racemate as compared to single enantiomer incubation in vitro.

Animals↗
PubMed1994

Stereoselective pharmacokinetics of methadone in beagle dogs.

The pharmacokinetics of methadone were studied in beagle dogs (n = 4) following intravenous administration of the racemate (0.5 mg/kg) and of the individual (R)-(0.25 mg/kg) and (S)-enantiomers (0.25 mg/kg) using a stereospecific HPLC assay. There was no significant difference between the pharmacokinetic parameters of (R)-methadone and (S)-methadone following administration of the individual enantiomers. Stereoselective differences were evident following administration of the racemate (P values for differences in AUC and CL were 0.01 and 0.046, respectively) and the clearance of the (S)-enantiomer was increased when administered as part of the racemate (316 +/- 81 vs 487 +/- 128 ml/min, P = 0.04). The data suggest that stereoselective disposition including potential enantiomer-enantiomer interactions should be considered in pharmacokinetic-pharmacodynamic studies of (R,S)-methadone.

Animals↗
PubMed1994

Double-blind study with dipyrone versus tramadol and butylscopolamine in acute renal colic pain.

To investigate the combined analgesic and spasmolytic effect of dipyrone, 104 patients suffering from "severe" or "excruciating" colic pain due to a confirmed calculus in the upper urinary tract were randomized to receive i.v. either 2.5 g dipyrone (36 patients), 100 mg tramadol (35 patients), or 20 mg butylscopolamine (33 patients) in a multicentre, observer-blind, parallel-group study conducted in 8 German centres. The three treatment groups were homogeneous when analyzed by age, sex, height, and baseline pain intensity. Dipyrone was significantly more effective than tramadol in reducing pain for the primary endpoint, pain intensity differences (PID) at 20, 30, and 50 min after drug administration, and was significantly more effective than butylscopolamine at 30 and 50 min for the secondary efficacy endpoint, pain intensity differences on a categorical scale. Dipyrone had the highest SPID0-2 h of the three drugs (P < 0.05). Only 5 patients receiving dipyrone needed "rescue" medication as compared with 13 patients given tramadol and 11 patients receiving butylscopolamine. Adverse events were observed in 4 patients receiving butylscopolamine and in 1 patient each given dipyrone and tramadol. "Distinct" pain relief as assessed on a visual analogue scale (VAS) is a reliable method of determining the onset of analgesic action in the colic pain model.

Acute Disease↗