Biomedical subjects

M Ryska

Publications and source records attributed to M Ryska.

At least 37 records · Page 2Linked to original sources

PubMed1995

BF3-catalysed methanolysis combined with fast atom bombardment tandem mass spectrometry as a new tool for the preparation and analysis of linear secocyclosporins.

BF3-catalysed methanolysis is presented for cyclic peptide cleavage using cyclosporins as model compounds. The reaction conditions for BF3-catalysed methanolysis of cyclosporins were optimized to favour the formation of linear undecapeptides. The resulting secocyclosporins were analysed by fast atom bombardment tandem mass spectrometry. Only one dominant and two side mechanisms of the ring opening are operating so that the complete sequence determination of all prepared oligopeptides was achieved.

Amino Acid Sequence↗

PubMed1994

Fast atom bombardment mass spectrometry of elymoclavine glycosides.

A series of nine naturally occurring and/or semi-synthetic elymoclavine mono- and oligoglycosides containing various sugar units was investigated by fast atom bombardment, high-resolution measurements and linked scans. The fragmentations of the [M+H]+ and [M+Na]+ ions are described and their different contributions to the structure elucidation are discussed.

Carbohydrate Sequence↗

PubMed1991

Mass spectrometric structure determination of metabolites of 3-[2-(N,N-dimethylaminomethyl)phenylthio]phenol.

Metabolites of 3-[2-(N,N-dimethylaminoethyl)phenylthio]phenol (I) were isolated from the urine of rats, mice, rabbit and dog and from the faeces of rats by extraction and thin-layer chromatography. From the mass spectrum of I and using characteristics mass shifts in the spectra of metabolites, the structures of four metabolites were determined, whereas for two other isomeric metabolites the structures were resolved by means of IR spectra. Conclusions regarding the structures derived from the spectra were confirmed by comparing them with synthetic standards. Generally, metabolic changes of I can be characterized by demethylation, hydroxylation combined with methylation, S-oxidation and by a combination of these metabolic reactions.

Animals↗

PubMed1990

[Metabolites of substance VUFB 15468 in animals].

Metabolites of drug VUFB 15468 present in the urine of rats, mice and dogs and in rat faeces after peroral administration were determined qualitatively. The relative representation of the individual metabolites in the urine of rats and mice was determined radiometrically after p. o. administration of [3H]VUFB 15468. For qualitative demonstration the metabolites were extracted; they were detected, partially identified and purified by thin-layer chromatography and then analyzed by mass spectrometry and IR-spectrometry. Structures of 11 metabolites were completely or partially determined in rat urine. Five of them were also found in rat faeces, one in murine urine and five in canine urine. In all animal species also unchanged VUFB 15468 was found. For quantification of the individual metabolites and VUFB 15468, TLC-radiometry and liquid scintillation spectrometry were used in rats and mice. Of the relative representation of metabolites, about one third is unchanged VUFB 15468, the rest are metabolites. In mice, the proportion of unchanged VUFB 15468 is much higher, about two thirds.

Animals↗

PubMed1989

Cellular fatty acids and fatty aldehydes of Listeria and Erysipelothrix.

The cellular fatty acid composition determined by gas chromatography-mass spectrometry, was found not to differ among Listeria monocytogenes, L. innocua and L. ivanovii. Slight quantitative differences found in the fatty acid pattern of L. welshimeri were significantly pronounced in L. denitrificans. L. murrayi and L. grayi displayed characteristic closely related patterns. Considerable amounts of fatty aldehydes and their dimethyl acetals were observed in hydrolysates and methanolysates of L. seeligeri. The fatty acid composition of Erysipelothrix rhusiopathiae was found to strongly differ from that of Listeria.

Aldehydes↗

PubMed1989

[Spontaneous perforation of a pancreatic pseudocyst into the duodenum].

The authors describe a rare observation of a spontaneous perforation of a pseudocyst of the head of the pancreas into the duodenum with haemorrhage into the digestive tract. The case is documented by the clinical finding, computed tomography and endoscopic fistulography.

Adult↗

PubMed1988