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Biomedical subjects

G Lercker

Publications and source records attributed to G Lercker.

6 recordsLinked to original sources
PubMed1992

Improvement of extraction procedure for biogenic amines in foods and their high-performance liquid chromatographic determination.

A high-performance liquid chromatography method is described for the simultaneous determination of the biogenic amines tryptamine, 2-phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine in cheese. The optimization of the procedure for the extraction of amines from the matrix is described. The separation of dansyl derivatives of the amines was achieved by reversed-phase liquid chromatography with gradient elution, followed by UV detection at 254 nm. The mobile phase was acetonitrile-0.01 M phosphate buffer (pH 7)-water. Under these conditions, rapid elution of the amines in less than 13 min was obtained. Validation of the method included calibration experiments, addition of standard amines for the determination of amine recoveries and repeatability tests.

Biogenic Amines↗
PubMed1992

Cannabinoid acids analysis.

The cannabinoid pattern of vegetable preparations from Cannabis sativa (hashish, marijuana) allows to recognize the phenotype of the plants, to be used as drug or for fiber. Cannabinoid determination by analytical point of view has represented some problems caused by the complex composition of the hexane extract. Capillary gas chromatography of the hexane extracts of vegetable samples, shows the presence of rather polar constituents that eluted, with noticeable interactions, only on polar phase. The compounds can be methylated by diazomethane and silanized (TMS) by silylating reagents. The methyl and methyl-TMS derivatives are analyzed by high resolution gas chromatography (HRGC) and by gas chromatography-mass spectrometry (GC-MS). The identification of the compounds shows their nature of cannabinoid acids, which the main by quantitative point of view results the cannabidiolic acid (CBDA). It is known that the cannabinoid acids are thermally unstable and are transformed in the corresponding cannabinoids by decarboxilation. This is of interest in forensic analysis with the aim to establish the total amount of THC in the Cannabis preparations, as the active component.

Cannabinoids↗
PubMed1989

Effect of a hyperlipidic diet on lipid composition, fluidity, and (Na+-K+)ATPase activity of rat erythrocyte membranes.

Feeding rats a hyperlipidic diet in which animals were offered daily a variety of high-energy food resulted in a significant increase of serum free fatty acids and a decrease of phospholipids with respect to controls. On the contrary, there were no significant differences in erythrocyte membrane total lipid composition between the two groups. Erythrocyte membranes showed a significant decrease in saturated fatty acid content and a significant increase in (n-6) polyunsaturated fatty acid content; (n-3) polyunsaturated fatty acids significantly decreased. Membrane fluidity, investigated by fluorescence polarization of diphenylhexatriene, significantly increased in the erythrocyte membranes of the experimental group. These results seem compatible with the decreased saturated/unsaturated fatty acid ratio. A significant decrease of (Na+-K+)ATPase activity occurred in erythrocyte membranes of the experimental group rats with respect to the controls.

Animals↗
PubMed1989

Lipid composition, fluidity and enzymatic activities of rat liver plasma and mitochondrial membranes in dietary obese rats.

Total lipids and fatty acid composition were determined in liver plasma and mitochondrial membranes from control and dietary obese rats after 4 weeks of the experimental period. The lipid composition of liver plasma and mitochondrial membranes showed an increase of triacylglycerols in obese rats. The liver plasma membranes showed a decrease of saturated/unsaturated fatty acid ratio and an increase of (n-6) polyunsaturated fatty acids, whereas the (n-3) polyunsaturated acids were decreased. Contrary to what occurs with plasma membranes, few modifications were observed in mitochondrial membranes. Changes of the fatty acid composition of the phospholipid bilayer are of potentially great importance in structural and functional parameters of membrane. Fluidity of liver plasma membranes of dietary obese rats was highly increased, while the mitochondrial ones remained unchanged. These results can be well explained by the decreased saturated/unsaturated fatty acid ratio. A significant decrease of (Na+-K+) ATPase activity (a membrane bound enzyme) was found in plasma membranes of dietary obese rats. Mitochondrial enzymatic activities and oxidative phosphorylation showed few changes except a small, but significant decrease of state 3 respiratory rate. In this study we also determined the fatty acid composition of all the foods offered to animals and their daily intakes in order to discuss their possible influence on changes in structural and functional membrane parameters.

Animals↗
PubMedDate not supplied

[Saturated fatty acids determination by GLC after TLC separation (author's transl)].

The determination of fatty acid composition of oils and fats by conventional GLC on polar columns gives satisfactory results for most of the applications. Higher precision is, however, desirable when the content of minor components is of interest. A typical example is the quantitative determination of the percentage of peanut oil in a seed oil mixture, on the basis of the content of lignoceric acid (n-C21). Lignoceric acid, wich is containen in peanut oil in the amount of 1-2%, shows, on polar columns, a very long retention time and, owing to its low percentage, flat and non well measurable peaks. A method was therefore developed which allows an accurate determination of all saturated fatty acids, particulary of those with high molecular weight. The method is based on the separation of satured fatty acids by argentation TLC followed by GLC determination on non polar columns.

Arachis↗