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Biomedical subjects

G Spiteller

Publications and source records attributed to G Spiteller.

At least 55 records · Page 3Linked to original sources
PubMed1994

alpha-Hydroxyaldehydes, products of lipid peroxidation.

Besides the well known products of lipid peroxidation, 4-hydroxy-2-nonenal, saturated and unsaturated aldehydes, 2-hydroxy-heptanal was found to be a major aldehydic product of lipid peroxidation (LPO) of n-6 fatty acids (linoleic acid 18:2, arachidonic acid 20:4). 2-Hydroxyhexanal is produced also, but only in much lower yield. 2-Hydroxyalkanales with 8,9,10 and 11 C-atoms are derived from hydroperoxides of oleic acid. An oxidation product of all unsaturated fatty acids is glyoxal. Analyses were performed after aldehyde specific derivatization reactions by GC-MS.

Aldehydes↗
PubMed1994

Effects of soybean lipoxygenase-1 on phosphatidylcholines containing furan fatty acids.

Naturally occurring tetraalkylsubstituted furan fatty acids (F-acids) were tested as potential substrates for soybean lipoxygenase-1. For this purpose, F-acid methyl ester and phosphatidylcholines containing F-acids at the sn-2 position of the glycerol residue were incubated with the enzyme. Oxidation of F-acids only occurs in the presence of linoleic acid as co-substrate. Linoleic acid is converted by lipoxygenase to the corresponding hydroperoxide that oxidizes the F-acid, probably in a radical reaction, to form an unstable dioxoene compound. This intermediate then forms, dependent on pH, unsaturated furanoid acids or isomers with cyclopentenolone structure that can be detected by gas chromatography/mass spectrometry (GC/MS). F-acids located at the sn-2 position of a synthetic phosphatidylcholine (PC), containing linoleic acid in the sn-1 position, are co-oxidized to a greater extent by incubation with soybean lipoxygenase-1 than are F-acids bound to PC with myristic acid in the sn-1 position when subjected to the enzyme in the presence of a great excess of linoleic acid. The results suggest that F-acids may play a strategic role in antioxidative processes in plant cells.

Fatty Acids↗
PubMed1993

The occurrence of furan fatty acids in Isochrysis sp. and Phaeodactylum tricornutum.

Two algae species with a fundamentally different fatty acid composition were investigated for their furan fatty acid (F-acid) content. Isochrysis sp. contains different F-acids with a pentyl side chain in alpha'-position of the furan ring. In consideration of its fatty acid composition which is predominated by compounds with a C-18 chain, this result supports the assumption that pentyl-F-acids derive from linoleic acid. In contrast, only F-acids with propyl side chain were found in Phaeodactylum tricornutum. The low content of C-18 fatty acids in this diatomae contradicts the previous hypothesis that linolenic acid is the precursor of propyl-F-acids. But the presence of (n - 4) unsaturated fatty acids with 16 carbon atoms in Phaeodactylum tricornutum suggests that propyl-F-acids are synthesized from 9,12-hexadecadienoic acid in a very similar biogenetic pathway than pentyl-F-acids.

Eukaryota↗
PubMed1993

Review: on the chemistry of oxidative stress.

Injury of plant cells as well as mammalian cells is connected with the activation of 'dormant' lipoxygenases. In the presence of oxygen, these enzymes are activated and enabled to catalyze the formation of hydroperoxides of linoleic and other polyunsaturated fatty acids. Reactivity of dormant lipoxygenases seems to be dependent on the carbon number between the alkyl end and the double bond situated next to this end in an unsaturated acid. In contrast to these dormant lipoxygenases there exists a second group of lipoxygenases, which are active in plant cells all the time, independent of an injury. They react mainly with acids possessing two homoconjugated double bonds within a distance of seven CH2 groups from the carboxylic end. Thus, they 'count' from the reverse end of the molecule. These lipoxygenases produce F-acids. They are converted, when plant cells are injured by hydroperoxides produced from unsaturated acids, into dioxoenoic acid intermediates which probably are used for defense. In mammalian tissues, lipoxygenases produce in the case of cell injury plasmalogen epoxides. These are analogous to dioxoenoic acids' highly reactive intermediates (in a chemical sense) which react immediately with nucleophiles. Such transformation of plasmalogens may be responsible for the development of chronic diseases, e.g., atherosclerosis, Alzheimer's disease and also for aging.

Animals↗
PubMed1992

Analysis of peptides of human seminal plasma by mass spectrometry.

A procedure is described to isolate peptides from complex biological fluids (e.g. seminal plasma) in pure form within a short time. The sequence of the isolated peptides was determined by liquid secondary ion mass spectrometry in combination with enzymatic cleavage reactions. The method was used for the structure elucidation of a peptide of molecular weight 2766 u with an N-terminal pyroglutamine residue.

Amino Acid Sequence↗
PubMed1992

A new carbamazepine metabolite in uraemic filtrate.

1. After administration of carbamazepine (Tegretal) to an epileptic patient suffering also from uraemia, a previously unknown metabolite was detected in the haemofiltrate. It was identified as the 10,11-dihydro-10-hydroxy-carbamazepine-O-beta-glucuronide. 2. Its identification was accomplished mainly by electron impact (EI), liquid secondary ion (LSI) mass spectrometry and n.m.r. spectroscopy.

Carbamazepine↗
PubMed1991

[Fragments from albumin and beta 2-microglobulin--constituents of the middle molecule fraction in hemofiltration].

Peptides were isolated from the middle molecule fraction of hemofiltrate obtained from uremic patients by adsorption of the organic compounds on RP 18. By stepwise elution an enriched peptide fraction was obtained. This procedure was followed by a combination of ion-exchange-chromatography, gel-chromatography and HPLC. The pure peptides obtained in this way were investigated by liquid secondary ion mass spectrometry (LSIMS)-if necessary after enzymatic digestion. The identified peptides turned out to be fragments of the human serum albumin and beta 2-microglobulin.

Adult↗
PubMed1990

Simple method for the analysis of glycerol enol ethers derived from plasmalogens in complex lipid mixtures and subsequent determination of the aldehydic components by gas chromatography-mass spectrometry.

Glycerol enol ethers, obtained by the reduction of plasmalogens with lithium aluminum hydride, can be converted into glycerol alk-(1)-enyl ether bismethyl ethers with diazomethane in the presence of silica gel. Their mass spectra allow the position of the enol ether group in glycerol unit to be deduced. Branches in the aldehydic components of the glycerol alk-(1)-enyl ether bismethyl ethers can be identified unequivocally by preparation of the 2-alkyl-1,3-dithiolanes, desulphurization with Raney nickel and deuterium to hydrocarbons and subsequent analysis by gas chromatography-mass spectrometry.

Aldehydes↗
PubMed1989

The common occurrence of furan fatty acids in plants.

The observation that F-acids (1) occur in rat chow initiated a search for F-acids in human diet. We observed that the amount of F-acids with a pentyl side chain in alpha-position taken up with a one-day diet correlates well with the amount of excreted degradation products, the pentyl urofuran acids (2), (3) and (4). Therefore it can be concluded that F-acids with a pentyl side chain are not produced in the human body but are introduced through the diet. The origin of F-acids carrying an alpha-propyl side chain is less clear. The amount of propyl-urofuran acids (2) and (3) excreted in urine was found in one case out of three to be five times higher than the amount of F-acids carrying a propyl group in alpha-position taken up by the diet. Therefore, it can presently not be excluded that a portion of the propyl F-acids is produced by the body. F-acids found in human food are mainly introduced into the body by vegetables and fruits. F-acids were found also in birch leaves in considerable amounts, as well as in grasses, dandelion and clover leaves. Thus, we can conclude that F-acids are common constituents of plants.

Chromatography, Gas↗
PubMed1988

Practical hints for peptide sequencing by soft ionization methods.

Practical hints are summarized for the investigation of peptides by soft ionization methods based on liquid secondary ion mass spectrometry. The method aims: to purify the sample; to force a peptide to the surface by ion pair formation; to recover the sample used for mass spectral analysis; to distinguish between Lys and Gln by derivatization; to spot amino acids in the low mass region; and to improve sequence information by use of peptide fragments, not described previously.

Amino Acids↗
PubMed1988

Investigations of the origin of the furan fatty acids (F-acids).

The possible role of linoleic acid as a biogenetic precursor of the furan fatty acids (F-acids) was investigated in in vivo experiments in the rat, using a C19 analogue of linoleic acid and gas chromatography-mass spectrometry. No evidence of incorporation of this compound into the F-acids was found. Using an improved analysis procedure by converting F-acids into their tetrahydrofuran derivatives (enabling a separation from the large amounts of normal fatty acids), F-acids (F3, F4 and F6) were detected in rat food, correcting earlier results. Quantification of F-acid intake with food and excretion of furandicarboxylic acids in the urine, suggested the possibility that the F-acids are not produced de novo in the rat, but instead accumulate in tissue after nutritional intake.

Animals↗
PubMed1987

Excretion of urinary acids during inverted sleep-waking rhythm.

Some organic acids that occur in human urine are excreted in very different amounts during the day and the night. The day-night rhythm in the excretion rate of citric acid and propylurofuran acid changes only gradually if the normal rhythm of life is inverted, e.g., if a person sleeps during the day and works at night (shift of 12 h), paralleling the gradual adjustment of steroid metabolism under the same conditions. In contrast, the typical rhythm in the excretion rate of tetrahydrofuran acids and tartaric acid inverts immediately if the sleep-waking rhythm of a person is inverted. In contrast to propylurofuran acid, pentylurofuran acid is excreted unrhythmically. No change in the excretion rate of amino acids was observed if the daily rhythm was inverted. Quantifications were achieved by liquid-liquid extraction, derivatization and gas chromatography computerized peak area integration.

Acids↗
PubMed1987

Unusual conjugates in biological profiles originating from consumption of onions and garlic.

After consumption of onions or garlic, biological profiles of human urine samples show, in the methylated conjugate fraction, peaks corresponding to the methylates of N-acetyl-S-(2-carboxypropyl) cysteine (1), N-acetyl-S-allylcysteine (2) and hexahydrohippuric acid (3). The compounds 1 and 2 are metabolites of peptides introduced with onions or garlic into the body.

Acetylcysteine↗
PubMed1987

[Disorders of steroid metabolism in inflammatory skin diseases].

The corticosteroid and androgen metabolites in the urine of 37 test subjects (11 healthy volunteers, 16 patients with eczema, and 10 patients with psoriasis) were investigated by means of gas chromatography and mass spectrometry. In addition, we studied the cortisol and testosterone levels in the plasma by radioimmunoassay. Those patients who had been treated with corticosteroids during the last two weeks were excluded. Our findings revealed that the excretion rate of steroid metabolites was significantly reduced in dermatological patients. The excretion rate of corticosteroids in urine was decreased an average of 25% (eczema) and 29% (psoriasis). The reduction of the androgen metabolites amounted to 26% and 31%. Cortisol and testosterone levels in the plasma were normal in all the cases.

Adrenal Cortex Hormones↗