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G Schumann

Publications and source records attributed to G Schumann.

At least 73 records · Page 4Linked to original sources
PubMed1992

Monoclonal fluorescence polarization immunoassay evaluated for monitoring cyclosporine in whole blood after kidney, heart, and liver transplantation.

In a prospective study we evaluated a novel fluorescence polarization immunoassay (FPIA) for determining cyclosporine (CsA) in whole blood. FPIA uses a monoclonal antibody and is performed on the TDx (Abbott). The within-series (CV less than 2%) and between-days (CV less than 3.3%) precision of the assay was excellent. The results obtained by the monoclonal FPIA in samples from transplant patients (n = 100) averaged 31.9% and 20.2% higher than those by HPLC and a specific radioimmunoassay (INCStar), respectively. Results by all three methods correlated well. Follow-up studies during the early course after liver transplantation, however, suggested that high metabolite concentrations affect FPIA results. This is explained by previously described cross-reactions of the monoclonal antibody with some CsA metabolites. The FPIA results in samples of such patients should be interpreted cautiously.

Chromatography, High Pressure Liquid↗
PubMed1991

Transfer RNA genes from Dictyostelium discoideum are frequently associated with repetitive elements and contain consensus boxes in their 5' and 3'-flanking regions.

A total of 68 different tRNA genes from the cellular slime mold Dictyostelium discoideum have been isolated and characterized. Although these tRNA genes show features common to typical nuclear tRNA genes from other organisms, several unique characteristics are apparent: (1) the 5'-proximal flanking region is very similar for most of the tRNA genes; (2) more than 80% of the tRNA genes contain an "ex-B motif" within their 3'-flanking region, which strongly resembles characteristics of the consensus sequence of a T-stem/T-loop region (B-box) of a tRNA gene; (3) probably more than 50% of the tRNA genes in certain D. discoideum strains are associated with a retrotransposon, termed DRE (Dictyostelium repetitive element), or with a transposon, termed Tdd-3 (Transposon Dictyostelium discoideum). DRE always occurs 50 (+/- 3) nucleotides upstream and Tdd-3 always occurs 100 (+/- 20) nucleotides downstream from the tRNA gene. D. discoideum tRNA genes are organized in multicopy gene families consisting of 5 to 20 individual genes. Members of a particular gene family are identical within the mature tRNA coding region while flanking sequences are idiosyncratic.

Animals↗
PubMed1991

[Biosynthesis of anthracycline: a new interpretation of the results for daunomycin biosynthesis].

On the basis of literature data and our own experiments the "late" biosynthetic pathway to daunomycin has been interpreted from a new point of view considering both the in vivo biosynthesis and formation of shunt products. In contrast to existing hypotheses proposed by other authors we discuss a modified sequence leading to C-11 oxidation and, as a consequence, understand epsilon-rhodomycinone as a shunt product instead of a biosynthetic intermediate. In addition, a new hypothesis about the "early" steps of the ring formation from polyketides by a sequence of enzyme reactions has been proposed.

Antibiotics, Antineoplastic↗
PubMed1990

Steroid-1-dehydrogenases in nocardioform bacteria studied by electrophoresis and immuno blotting techniques.

Fifteen noncardioform bacteria strains, capable of transforming steroid compounds were investigated with regard to their range of inducible steroid-1-dehydrogenase (St1DH)1 activities. The St1DHs of these bacteria were compared due to their immuno reactivity in Western blot experiments with a rabbit antiserum raised against the purified St1DH of Rhodococcus rhodochrous 7030. Four strains exhibited a strong immuno reactivity, irrespective of differences in the electrophoretic mobility of the enzymes. Five strains revealed significantly diminished reactivities, and in five strains with a very low St1DH content, no reactivity was found. One strain, designated as Nocardiaspec. 7151, exhibited a high, inducible St1DH activity, but no immunoreaction was found. The absence of immuno reactivity is discussed in connection with the considerably diminished electrophoretic mobility of this enzyme.

Blotting, Western↗
PubMed1990

Analyses with the KODAK-Ektachem. Accuracy control using reference method values and the influence of protein concentration. Part II. Substrates.

The reliability of the determination of the most common substrates with the Ektachem 700 was evaluated. Accuracy control was performed in various ways including the comparison of results with reference method values. The influence of protein concentration was investigated systematically using sera containing varying amounts of protein obtained by ultracentrifugation. Bilirubin. Deviation from the reference method values was within limits of the guidelines (Dt. Arztebl. 85 (1988) B517-B532). The influence of protein concentration was negligible. Cholesterol. The results agreed well with the reference method values. The method was not influenced by different protein concentrations. Creatinine. The results were in good agreement with reference method values, when the method was calibrated with the primary assigned values of the calibrators. At high protein concentrations, the results were higher than those of the comparative method. Glucose. The mean deviation from the reference method values was 1.0%. There was a clear positive bias at high protein concentrations. Protein. The results from the Ektachem deviated from the reference method values by -6.8%. Total glycerol (triacylglycerols). In the analysis of control sera, the Ektachem values differed greatly (+32.1%) from the reference method values. This difference was not found in a comparative study with native sera. At high protein concentrations the Ektachem results were higher than those of the comparative method. Urea. The results were lower than the method-dependent assigned values (-16.6%). This deviation was not observed in a comparative study with native sera. Interference by protein was not observed. Uric acid. In accuracy control with reference method values, a small bias was observed (+3.3%), which increased at high protein concentrations.

Bilirubin↗
PubMed1990

Determination of methotrexate in serum: the aca MTHO immunoassay and HPLC compared.

The determination of methotrexate on the aca clinical analyser (aca MTHO method) was evaluated and the method compared with a fluorescence polarisation immunoassay (FPIA) and a specific high-performance liquid chromatography (HPLC) procedure. The within series and the between days coefficients of variation of measurements in human pool serum spiked with methotrexate (0.07 mumol/l to 15 mumol/l) ranges from 11.7% to 2.5% and 14.0% to 5.8%, respectively. The calibration was found to be stable for 9 weeks. There was a good correlation between the results of the MTHO method when compared with FPIA and HPLC. At low methotrexate concentration, the results of HPLC were on average 11% and 14% lower than those obtained by the MTHO assay and FPIA respectively.

Chromatography, High Pressure Liquid↗
PubMed1990

[Studies for the assessment of the herbicide prometryne in the air].

An analytical method for the quantitative determination of the triazine herbicide prometryne in air is described. In the sample preparation procedure developed, the ambient air is drawn through the adsorber tube packed with the prepurified crosslinked polystyrene resin Wofatit EP 61 (0.2-0.5 mm) for collecting the pesticide with a high efficiency. A special modified cellulose filter is of use to sample particulate matter. The trapped vapours and aerosol are nearly quantitatively eluted from the sorbent by diethyl ether and then analyzed by gas chromatography. A greenhouse experiment yielded prometryne concentrations in air up to 146 ng.m-3 after spraying on soil. The described procedure permits the measurement of airborne prometryne at trace levels up to 1 ng.m-3.

Air Pollutants↗
PubMed1989

Three other types of duodenal polyps: mucosal cysts, focal foveolar hyperplasia, and hyperplastic polyp originating from islands of gastric mucosa.

Seven cases are reported that initially presented on endoscopic examination as duodenal polyps originating from islands of gastric mucosa within the duodenal bulb. Microscopic examination revealed mucosal cysts (MC), focal foveolar hyperplasia (FFH), and hyperplastic polyp (HPP). These lesions must be added to the list of neoplastic and tumorlike lesions of the duodenum that may endoscopically present as polyps.

Aged↗
PubMed1989

Effects of toxin isolated from the sea anemone Bolocera tuediae on electrical properties of isolated rat skeletal muscle and cultured myotubes.

Electrophysiological effects of a polypeptide toxin isolated from the sea anemone Bolocera tuediae (BTTX II) on isolated fast and slow rat skeletal muscle and on cultured rat myotubes are described in this paper. Nanomolar concentrations of BTTX II cause a concentration-dependent depolarization. This effect is prevented by the presence of tetrodotoxin. Action potential duration is prolonged in all preparations investigated, with the fast muscle being the least sensitive. The positive overshoot and the maximum rate of rise of the action potential is decreased by BTTX II. Cultured myotubes which are less susceptible to the sodium channel blocking activity of tetrodotoxin have the highest sensitivity to all actions of BTTX II. It is further shown that the proportion of spontaneously contracting myotubes is diminished and the frequency of contractions is increased by the toxin. The effects of Bolocera tuediae toxin II resemble those observed with Anemonia sulcata toxin II on mammalian skeletal muscle. From the results it is concluded, that BTTX II may interfere with both the activation and inactivation of sodium channels of the muscle membrane.

Action Potentials↗
PubMed1988

Biosynthesis of anthracyclinones: isolation of a new early cyclization product aklaviketone.

Five metabolites were isolated from fermentations of a mutant strain S 383 of Streptomyces galilaeus. Components S 383-O and S 383-A were identified as known derivatives of anthraquinone and naphthacenequinone, respectively, previously isolated from cultures of other blocked mutants of S. galilaeus strains. Component S 383-X was identical with 7-deoxyaklavinone. Compound S 383-Y (aklaviketone) was found to be a new metabolite. Its chemical structure has been determined by physico-chemical methods including mass spectrometry and NMR spectral studies. The compound (7-dehydro-7-deoxy-7-oxoaklavinone) is most likely the first cyclization product along the metabolic chain possessing the tetracyclic carbon skeleton of anthracyclinones. A proposed pathway is discussed.

Antibiotics, Antineoplastic↗
PubMed1988

MTP-PE: induction of tumoricidal leukocytes in the lungs of rats.

Buffer solubilized MTP-PE binds very quickly (within 10 min) to rat alveolar macrophages in vitro and activates them to the tumoricidal state. In vivo, the alveolar macrophages become tumoricidal after intratracheal instillation of MTP-PE. Intranasal application of a relatively large volume (300 microliter) gives the same result, because MTP-PE is then aspirated into the lungs. A wide dose range (1-10,000 micrograms/kg) is effective. Immediately after application of MTP-PE, activated macrophages can be washed out of the lungs. Between 8 and 48 hr after application many tumoricidal neutrophils are also found. Although the tumoricidal activity decreases with time, it can still be demonstrated 8 days after application. Intravenous injection is also effective, but only at 10(3)-fold higher doses. Inhalation of MTP-PE might be of therapeutical value in the treatment of cancer, particularly in the lungs.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Systemic activation of tumoricidal properties in mouse macrophages and inhibition of melanoma metastases by the oral administration of MTP-PE, a lipophilic muramyl dipeptide.

The purpose of these studies was to determine whether the oral administration of a lipophilic analog of muramyl dipeptide, MTP-PE, can produce in situ activation of tumoricidal properties in mouse macrophages. MTP-PE was dissolved in a phosphate-buffered saline to produce micelles. Single or multiple oral administrations of MTP-PE produced tumoricidal activation in both lung and peritoneal macrophages. This was in direct contrast to the i.v. or i.p. administrations of MTP-PE incorporated in liposomes, which produced activation in only lung or only peritoneal macrophages, respectively. The distribution and fate of [3H]-labeled MTP-PE subsequent to oral administration revealed that MTP-PE was found in various organs independent of reticuloendothelial activity. Finally, the repeated twice-weekly oral administrations of MTP-PE inhibited lung and lymph node metastasis in C57BL/6 mice by syngeneic B16 melanoma cells. The oral administration of MTP-PE, however, was not effective in eradicating well-established melanoma metastases. We conclude that the oral administration of a lipophilic muramyl dipeptide produces systemic activation of macrophages. The feasibility of enhancing host defense against infections and cancer by the oral administration of an immunomodulator has obvious clinical advantages.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

Aklanonic acid-producing mutants of Streptomyces galilaeus and Streptomyces peucetius var. caesius.

A number of blocked mutants was investigated which were obtained from taxonomically identified Streptomyces strains producing anthracyclines. Two of these mutants, NTG 061 derived from S. galilaeus F 198 and mutant 135 derived from S. peucetius var. caesius 601 F.I.1), accumulated an anthraquinone derivative which was identified as aklanonic acid. The results supplied further evidence that this compound was an intermediate of the biosynthetic pathway leading to different types of anthracyclines. It occurred before ring closure to the final tetracyclic anthracyclinone skeleton.

Anthraquinones↗
PubMed1987

Induction of tumouricidal macrophages by MTP-PE: its enhancement by a factor produced spontaneously by tumour cells.

Tumouricidal activity of rat alveolar macrophages is induced by MTP-PE in vitro. This tumouricidal activity is enhanced by a factor (tumour cell derived immunostimulating factor, TCIF) contained in tumour cell culture supernatants. TCIF is not species specific, since culture supernatants of rat MADB-200 as well as mouse B16 or Meth A tumour cells showed similar effects on rat alveolar macrophages. TCIF is not produced in cultures of normal cells, e.g. rat embryo cells. TCIF produced by MADB-200 tumour cells is relatively heat-stable and dialyzable. It is destroyed by treatment at pH 2 for 24 hrs. These results suggest that TCIF can participate in macrophage activation and could be of potential therapeutic value.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1987

[Results of stereotactic treatment of drug-resistant epilepsy].

After a brief review of results reported so far regarding the stereotactic treatment of seizures, the author describes the results achieved with eight patients on whom stereotactic coagulation was performed in the right or left amygdala-hippocampus complex between 1976 and 1983 on account of drug-resistant partial seizures. Except for one case, in which the indications were purely clinical and it proved impossible to influence the frequency of seizures, seizures either ceased or their frequency was reduced. With a mean duration of 15 years, the period of pharmacoresistance until surgery was indicated was far longer than reported in the literature.

Amygdala↗