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Biomedical subjects

W Biederbick

Publications and source records attributed to W Biederbick.

10 recordsLinked to original sources
PubMed2005

[Management of bioterroristic attacks with dangerous infectious agents].

The ongoing discussion on threats by terrorist attacks leads to a realignment of tasks and responsibilities within the health care system. Especially the public health services are developing from exercising mainly an advisory function to becoming an integral part in disaster response to devastating biological scenarios. Recent risk assessment recommends authoritative integration of public health officials into disaster response planning and to define their role inside the command and control structures of disaster management. Interdisciplinary networks of public health services, medical treatment centres, emergency medical services, reference laboratories and hospital hygiene services have appeared to be successful in the management of life-threatening, contagious diseases and unexpected bioterrorist incidents as well. In March 2003 the "StAKoB" was established as a permanent working group of the centres for prepared ness and treatment. Major objectives of the working group are ex change of information, mutual support in cases of emergency and standardisation in staff training.

Biological Warfare↗
PubMed2001

Studies of the toxic effects of norepinephrine on isolated cardiomyocytes of guinea-pigs.

Catecholamines have been demonstrated to possess direct cardiotoxic effects mediated by oxygen free radicals in isolated organ preparations. In order to assess direct cytotoxic properties, the influence of exogenous noradrenaline (norepinephrine, CAS 51-41-2) (10(-6) mol/l) on isolated guinea-pigs cardiomyocytes was examined, in the presence of propranolol (10(-6) mol/l) and phentolamine (10(-6) mol/l) to inhibit adrenoceptor-mediated effects. Cell viability was assessed by morphologic examination (% of striated, rod-shaped cells), before and after a treatment period of 15 and 60 min by the measurement of intracellular enzyme activities in the supernatant of the suspension (lactate dehydrogenase, creatine kinase, aspartate aminotransferase, alanine aminotransferase, glutamate dehydrogenase). The proportion of viable, rod-shaped cardiomyocytes (21.6% +/- 7.6% after preparation, before starting the treatments) significantly decreased over the experimental time (p < 0.05) and, concomitantly, the activity of intracellular enzymes in the supernatant increased. There was no difference between controls and treated suspensions. Thus, there is no evidence for direct toxic effects of norepinephrine in micromolar concentration on isolated cardiomyocytes of guinea-pigs. However, cytoprotective effects by propranolol and/or phentolamine cannot be excluded in this model.

Adrenergic alpha-Antagonists↗
PubMed1999

Pseudocholinesterase-activity reduction during cardiopulmonary bypass: the role of dilutional processes and pharmacological agents.

UNLABELLED: 1. Pseudocholinesterase (ChE) activity is a determinant of the elimination kinetics of several drugs used in anesthesia. The time course of ChE activity was investigated in 16 patients undergoing cardiosurgery for a cardiopulmonary bypass (CPB) in normothermia or hypothermia. 2. The onset of the CPB was accompanied by a decrease in ChE activity (-37%) (P<0.05) and protein concentration (-24%) (P<0.05). The quotient ChE activity/protein concentration was numerically reduced to a smaller extent (-15%) (P>0.05). After the CPB was finished, ChE activity and the protein concentration remained low for the remaining operation time. 3. There was no difference in ChE activity, measured in vitro at 37 degrees C, between the normothermic and hypothermic group (P>0.05). 4. There was no correlation between heparin concentration in serum and reduction of ChE activity in vitro (P>0.05). In vitro, the ChE activity was not affected by either heparin in doses as high as 10,000 U/ml or aprotinin in doses as high as 10,000 U/ml (P>0.05). 5. CONCLUSIONS: (1) ChE activity is reduced by CPB mainly by hemodilution and (2) the pharmacological agents used in the present anesthetic technique (heparin, aprotinin, midazolam, fentanyl, propofol and mivacurium) do not inhibit ChE activity at therapeutic serum concentrations.

Aged↗
PubMed1997

Sensitive and convenient high-performance liquid chromatographic method for the determination of mitomycin C in human plasma.

An improved high-performance liquid chromatographic assay for the cytostatic drug mitomycin C in plasma is presented. The principal steps are precipitation of plasma proteins with acetonitrile, lyophilization of the supernatant and reversed-phase chromatography on a Hypersil ODS 5 microm column with 0.01 M NaH2PO4 buffer (pH 6.5)-methanol (70:30, v/v) in isocratic mode. At a flow-rate of 1.3 ml/min a column pressure of 180-220 bar resulted. Porfiromycin served as internal standard. UV detection was performed at 365 nm. Quantitation limit based on a coefficient of variation <10% in intra- and inter-day assay was 5 microg/l mitomycin C, detection limit based on a signal-to-noise ratio of 3 was 1 microg/l. Recovery was 100% and linearity was shown for the whole range of concentration (1-500 microg/l). None of the five drugs used during chemoembolisation interfered with the assay in vitro. The assay meets the requirements for pharmacokinetic studies of mitomycin C in patients as regards sensitivity and ease of use.

Antineoplastic Agents, Alkylating↗
PubMed1997

Caffeine in saliva after peroral intake: early sample collection as a possible source of error.

The influence of collection time on the correlation of caffeine concentrations in saliva and serum was examined in six healthy adults after peroral administration of 5 mg/kg caffeine citrate. Saliva was obtained from three different salivary glands (sublingual, right parotid, and left parotid) and evaluated separately. Caffeine concentrations in saliva and serum samples were determined by high-performance liquid chromatography. There were no differences in the caffeine concentrations in saliva from the three investigated glands (alpha = 0.05). Saliva samples collected earlier than 2 hours after caffeine intake showed higher caffeine concentrations than could be expected from the corresponding serum samples. Gingiva contamination was shown to be responsible for the higher caffeine concentrations in saliva, and it was concluded that saliva is a feasible matrix for therapeutic drug monitoring of caffeine. If caffeine is administered orally, saliva samples should be taken at least 2 hours after caffeine intake. If caffeine-containing beverages are used as the source of caffeine or if subjects do not cooperate by rinsing the mouth of caffeine contamination, an additional 60 minutes should be added before saliva sampling.

Administration, Oral↗
PubMed1996

Stereoselective high-performance liquid chromatographic assay with fluorometric detection of the three isomers of mivacurium and their cis- and trans-alcohol and ester metabolites in human plasma.

An improved high-performance liquid chromatography assay for the three stereoisomers of the muscle relaxant mivacurium and its metabolites in plasma is presented. The principal steps in the assay are precipitation of plasma proteins by acetonitrile, lyophilization of the supernatant and ion-exchange chromatography on Spherisorb 5-SCX column, with gradient elution (acetonitrile from 32 to 68% v/v and ionic gradient from 7 to 56 nmol l-1 Na2SO4), a flow-rate of 2.0 ml min-1, D-tubocurarine as internal standard and fluorometric detection (excitation wavelength = 280 nm, emission wavelength = 320 nm). Quantitation limit of cis-cis, cis-trans, trans-trans isomers were 0.003, 0.002 and 0.005 mumol l-1, respectively. Quantitation limits for the monoestercis metabolite were 0.011 mumol l-1, for the monoestertrans metabolite 0.017 mumol l-1, for the amino-alcoholtrans 0.020 mumol l-1 and for the amino-alcoholcis 0.021 mumol l-1. None of eight drugs used during anaesthesia interfered with the assay in vitro. Satisfactory performance was demonstrated by the measurement of the isomers and their metabolites in plasma of two patients over a 6-h period after repeated injections of mivacurium.

Alcohols↗
PubMed1996

Pharmacokinetics of intraarterial mitomycin C in the chemoembolisation treatment of liver metastases.

1. The pharmacokinetics of mitomycin C (MMC) were investigated in 12 colorectal cancer patients with liver metastases undergoing chemoembolisation. Hepatic artery branches were embolized using polyvinylalcohol microspheres (150-250 microns) before applying 20 mg MMC in 4-8 min. 2. Serum MMC concentrations were determined from peripheral venous blood samples by reverse-phase HPLC using ultraviolet detection. Pharmacokinetic parameters were computed assuming an open two-compartment model. 3. Pharmacokinetic parameters were similar to values given in the literature for intravenous (IV) or intraarterial (IA) bolus MMC injections (Tmax = 7.0 min following the beginning of MMC infusion, Vss = 0.57 1/kg, C1 = 8.9 ml/min.kg, T1/2 alpha = 8.3 min, T1/2 beta = 58.6 min). 4. The area under the serum concentration-time-curve (AUC), standardized by the MMC amount injected, was similar to values reported in the literature for IV or IA bolus injections. There is no evidence for reduced systemic MMC exposure following the embolization procedure used.

Antibiotics, Antineoplastic↗
PubMed1995

Mitomycin-C concentration in human ocular aqueous humor after topical administration during trabeculectomy.

UNLABELLED: The concentration of the antitumor antibiotic mitomycin (CAS 50-07-7, mitomycin C, MMC), used in ophthalmic surgery for its antiproliferative effects, was measured in the aqueous humor of 7 glaucoma patients undergoing trabeculectomy. Sponges soaked with MMC-solution (100 microliters of MMC-solution 0.2 mg/ml: 20 micrograms) were applied intraoperatively on the scleral flap for 5 min. 100 to 200 microliters of aqueous humor were drawn with a needle 10 min following the end of topical MMC-treatment. Samples were assayed for MMC using a reverse-phase HPLC-system with ultraviolet detection (C18-column, elution: phosphate buffer (0.01 mol/l, pH: 6.5): methanol, v:v = 70:30, 365 nm). Swabs were extracted in phosphate-buffer (0.1 mol/l, pH: 7.0) before HPLC-analysis. External calibration was used for MMC quantitation. Quantitation limit was 10 ng/ml. In all aqueous humor samples MMC-concentration was below 10 ng/ml. MMC in the swabs amounted to 37% of the MMC amount applied. CONCLUSION: After intraoperative topical application, the MMC concentration in the aqueous humor of patients is very low. The substantial loss of MMC from the swabs used for the topical MMC-treatment suggests 1. rapid systemic absorption of MMC and/or 2. a loss through irrigation of the operative field following topical MMC-application.

Administration, Topical↗