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Adenocarcinomas of the gastrointestinal tract (esophagus, stomach, and colon) represent a heterogeneous group of diseases with distinct etiology, clinical features, treatment approaches, and prognosis. Studies are ongoing to isolate molecular genetic subtypes, perform complete biological characterization of the tumor, determine prognostic groups, and find predictive markers to the effectiveness of therapy. Separate molecular genetic classifications were created for esophageal adenocarcinoma [The Cancer Genome Atlas (TCGA)], stomach cancer (TCGA, Asian Cancer Research Group), and colon cancer (Colorectal Cancer Subtyping Consortium). In 2018, isolation of TCGA molecular genetic subtypes for adenocarcinomas of the gastrointestinal tract (esophagus, stomach, and colon) highlighted the need for further studies and clinical validation of subtyping of gastrointestinal adenocarcinomas. However, this approach has limitations. The aim of our work was to critically analyze integration of molecular genetic subtyping of gastrointestinal adenocarcinomas in clinical practice.

Lipoic acid is an important participant of the process of biological oxidation in both lipid and carbohydrate metabolism, produces a lipotropic effect by reducing the blood cholesterol level, and exhibits a pronounced antidote action in cases of poisoning with mercury, arsenic, and cadmium. Lipoic acid is administered for the treatment of atherosclerosis, ischemic heart disease, liver disorders, and various intoxicated states. This compound enters both into monopreparations (tabletized or capsulated) and in complex mixtures with vitamins and trace elements (e.g., in complevit, tivit, and saltivit additives).Analysis of lipoic acid encounters certain difficulties because this compound is susceptible to various transformations, primarily via oxidation and polymerization. The use of conventional methods such as spectrophotometry or polarography for the determination of lipoic acid in medicinal preparations shows low precision because of low extinction (in spectrophotometry) and high sensitivity to impurities with close redox potentials (in polarography), these factors hindering the correct analysis.HPLC is widely used and proved to be a universal method for the determination of lipoic acid and vitamins (A, E, etc.) in multivitamin complexes, making possible simultaneous analysis for these components in the same sample. We have checked this possibility both on lipoic acid monopreparations (tablets) and on new multivitamin complexes (tivit, saltivit) containing water-and fat-soluble vitamins, lipoic and succinic acid, and trace elements.An important advantage of the proposed HPLC technique is the simple sample preparation procedure, which significantly reduces the total duration of analysis and ensures simultaneous determination of the content of lipoic acid and vitamins A and E in these drugs. EXPERIMENTAL PARTThe samples were prepared using methanol, acetonitrile, and isopropanol of chromatographic purity grade, rectified ethyl alcohol, trifluoroacetic acid (TFA), and doubly distilled water.Preparation of sample solutions. Multivitamin pills to be tested are assumed to contain 0.002 -0.030 g of lipoic acid, 800 -4300 IU of retinol acetate (vitamin A), and 0.005 -0.030 g of a-tocopherol acetate (vitamin E). To several (2 -5) tablets in a 50-ml flat-bottom flask was added 7.5 ml of 0.05 M aqueous HCl and the mixture was kept with continuous stirring on a water bath at 60 ± 5°C until complete disintegration of the sample preparation, after which the flask was cooled in a stream of cold water. To this mixture was added 5 ml of ethyl ether and the whole was stirred for 2 -3 min. Then, 10 -15 ml of 96% ethanol was added and the mixture was stirred and quantitatively transferred to a 50-ml measuring flask with a glass-ground stopper. The flask was filled with the same solvent to the mark, after which the contents was thoroughly stirred and treated in a centrifuge. Immediately prior to analysis, the solution was filtered through a Millipore filter with a pore size of 0.2 -0.4 mm.Reference retinol acetate solution. An exactl...

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Abstract— The UV spectra of solid amorphous films of all‐trans retinyl polyenes. i. e. retinyl acetate, retinyl palmitate, axerophtene and retinal, on supports are investigated. It is shown that in the absence of oxygen the spectra of the films do not change at room temperature; in the presence of O2 the fast oxidation of the polyenes occurs which in the case of retinol esters and axerophtene is accompanied by the shift of the absorption maxima to the shorter wavelengths. Consequently, the interpretation of blue shift of UV spectra of retinyl polyene films given by Hotchandani and Leblanc (1976) is incorrect. The formation of the only compound is shown to occur during the first stage of the oxidation of retinyl acetate and retinyl palmitate films. Proceeding from IR spectra of oxidized films the compound is assigned to the corresponding 11‐cis isomer.