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Biomedical subjects

M Dahms

Publications and source records attributed to M Dahms.

7 recordsLinked to original sources
PubMed1998

[Interviewer effects in assessing subjective quality of life and satisfaction with care in sheltered housing].

The impact of interviewer-effects on subjective evaluative criteria was examined in a randomized control group design (n = 26 x 2) of clients of sheltered living in Berlin-Spandau. The assessment of care and subjective quality of life showed that clients were more satisfied if they had been interviewed by their responsible caregivers compared to interviewers from other providers of the same region--unknown to the clients. Conductibility of interviews was independent of interview conditions. A systematic overestimation of satisfaction should be taken into account if responsible caregivers interview their own clients. Such data should not be used comparing different settings.

Adult↗
PubMed1997

Elucidation of phase I and phase II metabolic pathways of rhein: species differences and their potential relevance.

Because of previously observed species differences in rhein tolerability, with rabbits being very susceptible to kidney disturbances, in vivo and in vitro biotransformation studies were performed to find out whether the differences in the undesired effects of rhein are associated with qualitative, species-dependent differences in its metabolism. First hints on species-dependent biotransformation profiles were obtained from in vivo experiments with 14C-labeled rhein in rat, rabbit, dog, and man. TLC-analysis of urine samples obtained after oral administration of 14C-rhein to rabbits revealed an additional, hydrophilic metabolite fraction in rabbit urine as compared with dog and human urine, all of which contain phenolic monoglucuronide and monosulfate as major metabolites. An investigation of urine samples (obtained from dogs, rabbits, rats, and human volunteers after oral application of unlabeled rhein) was conducted by means of mass spectrometric tandem techniques including on-line HPLC-MS/MS. In vitro experiments with subcellular liver fractions of rats and rabbits revealed the presence of three monohydroxylated metabolites of rhein, their quinoid oxidation products, and a bishydroxylated derivative of rhein. The hydroxylated phase I metabolites were detected as glucuronides in urine samples of all investigated species, whereas the quinoid product was present only in rabbit urine. Moreover, two regioisomeric phenolic glucuronides and sulfates or glucosides of rhein were found as major phase II metabolites in urine of all species. Furthermore, acyl glucuronides of rhein and monohydroxylated rhein and their respective isomeric acyl migration products were identified in human urine. In rabbit urine we discovered different bisglucuronides (bisphenolic glucuronide, mixed ether/ ester glucuronides), whereas in rats only the bisether/ether glucuronide was present. In addition, the investigations of dog and human urine showed the formation of two regioisomeric phenolic glucosides. With respect to a potential reactivity with endogenous macromolecules the quinoid metabolites as well as the bisester/ether glucuronides appear most relevant.

Animals↗
PubMed1996

Covalent binding of acidic drugs via reactive intermediates: detection of benoxaprofen and flunoxaprofen protein adducts in biological material.

The purpose of the study was the direct detection of intact protein adducts-resulting from in-vitro incubations of flunoxaprofen- and benoxaprofen glucuronides in biological materials or originating from in vivo studies-by polyacrylamide gel electrophoresis (SDS-PAGE) followed by blotting and fluorescent scan, presumably yielding better specificity for the macromolecular binding partner and avoiding alkaline cleavage to release the aglycone. Glucuronides were isolated from urine samples or generated by incubation of aglycone with cofactors and rat liver microsomes. Following dialysis against BSA solution, SDS-PAGE and subsequent electrotransblotting were performed. Apparently, albumin represents the major binding protein for the covalent binding of these acyl glucuronides in plasma following incubation with blank plasma. In microsomal proteins two fluorescent peaks (appr. 39 and 62 KD) were identified for flunoxaprofen and benoxaprofen incubations. In vivo covalent binding was detected for both flunoxaprofen and benoxaprofen in plasma samples. For the racemically administered benoxaprofen a slight preponderance in adduct concentrations was found for the S-enantiomer. The pharmacokinetic analysis of in vivo data obtained for R/S-benoxaprofen (dose: 600 mg racemate) and S-flunoxaprofen (dose: 100 mg racemate), both of which have been withdrawn from the market, (employing a stereospecific HPLC method when analyzing volunteers' and patients' samples collected in the last 14 years, yet not stored longer than 3-4 years) demonstrated that significant amounts of glucuronides occur for both drugs (n = 2 for each compound; average Cmax values of the glucuronides: S-flunoxaprofen: 395 ng/ml; S-benoxaprofen: 775 ng/ml; R-benoxaprofen: 563 ng/ml). Presumably because of stereoinversion in humans, aglycone and glucuronide concentrations were higher for S- than for R-benoxaprofen. In vivo aglycone/glucuronide ratios were smaller for S- than for R-benoxaprofen, although in vitro incubation with human liver microsomes resulted in preferential glucuronidation of the R-enantiomer of benoxaprofen. Plasma concentration-time curves of the glucuronides paralleled those of the respective aglycones in their terminal phase. S-Benoxaprofen adduct concentrations were higher than R-benoxaprofen adduct concentrations (S: 28 ng/ml; R: 18 ng/ml covalently bound) and S-flunoxaprofen adduct concentrations with 29 ng/ml in the same range as S-beoxaprofen adducts, although for the latter the dose range as well as the respective glucuronide concentrations were higher. This indicates a higher reactivity of S-flunoxaprofen as opposed to S-benoxaprofen glucuronides.

Animals↗
PubMed1990

[Enzymatic protein hydrolysate as the N-source for cell culture].

Supplement T, a preparation for cell culture growth, is just as effective as commercially available tryptose. It has met high demands throughout its application over six years under conditions of large-scale production of permanent cell lines. Supplement B has been used with good success in commercial production for breeding of FMD virus in BHC cells of IBR/IPN and PI-3 viruses in calf kidney cells cultures and of embryonic duck fibroblast cell cultures for production of vaccines against Marek's disease.

Animals↗