Purpose - to investigate the clinical and paraclinical features of the course of chronic gastroduodenitis (CGD) in children against the background of selenium deficiency. Materials and methods. Clinical and laboratory examination of 63 children (main group) aged from 7 to 18 years old, patients with CGD and 20 healthy children (comparison group) of the appropriate age was carried out. Quantitative determination of selenium in blood plasma was carried out using inductively coupled plasma mass spectrometry (ICP-MS) on an Optima 2000 DV spectrometer (Perkin Elmer, USA). Results. The average level of selenium in the blood plasma of children with inflammation of the gastric mucosa and duodenum was 73.45±4.21 μg/l, in children of the comparison group - 85.42±5.44 μg/l (p<0.05). 14 children had a selenium concentration within the normal range, and 49 patients had a significantly reduced selenium level (p<0.05), while 9 had the lowest level and was 57.2±3.5 ng/ml. Moderate erythema was recorded 3 times less often and a pronounced degree of erythema was recorded 4.6 times more often, in 4 people (8.1%) atrophy of the mucous membrane of the stomach and/or duodenum was detected, subatrophy was more often recorded (16.3%), 36.7% were diagnosed with the second degree of granularity. Was typicalhad nocturnal and «hungry» pain (22.4%). Conclusions. In the vast majority of children (77.7%), CGD occurs against the background of selenium deficiency in blood plasma. A direct correlation between the concentration of selenium in the blood plasma of sick children and the stage and activity of gastroduodenitis was established. The longer the course of the disease, the lower the levels of selenium in children's blood plasma. There is a pathomorphosis of CGD in children against the background of selenium deficiency: night and «hungry» pain, diffuse damage to the mucous membrane with erosions and subatrophy, a long course with high inflammatory activity are more common. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

Currently, the attention of many researchers is drawn to determine the features of the regeneration of the mucous membrane of the gastrointestinal tract in ulcers, as one of the most important protective factors in this pathology. Purpose - to investigate the indicators of endogenous polypeptides (epidermal growth factor - EGF and transforming growth factor α-TGF-α) in the serum of children with duodenal ulcers. Materials and methods. The study included 56 children aged 7-18 years (36 children with duodenal ulcer - the main group and 20 healthy children (comparison group). The content of endogenous polypeptides in serum was determined by enzyme-linked immunosorbent assay (ELISA) using the Human EGF ELISA Kit (Invitrogen, USA) for EGF and R&D system (USA) for TGF-α according to the manufacturer’s instructions. Statistical processing of the obtained results was carried out using parametric and non-parametric methods of evaluation of the obtained results. Results. Slightly higher levels of EGF and TGF-α were found in boys of both subgroups of the main group (EGF: 561.45 [391.81-699.34] pg/ml and 544.67 [411.23-569.77] pg/ml, p>0.05; TGF-α: 47.91 [21.41-29.69] and 42.56 [35.45-49.21] pg/ml, p>0.05). Concentrations of endogenous factors in exacerbation of ulcerative process are higher than in remission (p<0.001) and in remission does not reach that in healthy children, p<0.01). In patients with severe duodenal ulcers, EGF and TGF-α concentrations are higher (p<0.01), which may be due to the maximum degree of inflammatory-destructive process. Conclusions. The course of duodenal ulcer leads to disorders in the regulation of proliferative processes in the mucous membrane, which is manifested by increased levels of EGF and TGF-α in the serum of sick children, the more severe the course, the higher process. The research was carried out in accordance with the principles of the Helsinki declaration. The study protocol was approved by the Local ethics committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interest was declared by the authors. Key words: children, duodenal ulcer, epidermal growth factor (EGF), transforming growth factor α (TGF-α).

Despite the success of the treatment of infected individuals, Helicobacter pylori infection remains the most common human bacterial pathogen, infecting half of the world’s population. In a large part of people, H. pylori causes gastroduodenal diseases, in particular, chronic antral gastritis and ulcer disease. The possible role of selenium in the course of chronic inflammatory H. pylori-associated pathology of the upper gastrointestinal tract in children has not yet been fully investigated and understood. The aim is to determine selenium plasma levels in children with Helicobacter pylori-associated diseases of the upper gastrointestinal tract. Materials and methods. The study included 135 school-age children with Helicobacter pylori-associated diseases of the upper gastrointestinal tract, who made up the main study group (55 children with chronic gastritis (CG), 57 children with chronic gastroduodenitis (CGD), 23 children with duodenal ulcer (DU), and 20 practically healthy age-matched children were the comparison group. Quantitative measurements of plasma selenium were performed using inductively coupled plasma mass spectrometry (MS-ICP) on an Optima 2000 DV spectrometer (Perkin Elmer, USA). Results. The lowest level of plasma selenium was registered in children with H. pylori-negative DU (67.81 ± 2.67 μg/l), while in children with H. pylori-associated DU, its level was higher – 73.56 ± 2.34 μg/l (p < 0.05), however, it did not reach the level in children of the comparison group. A similar direction of changes in the selenium plasma concentration was observed in children with CGD: higher levels of selenium were detected in children with H. pylori-positive CGD compared to H. pylori-negative CGD (75.61 ± 2.48 μg/l and 70.99 ± 2.31 μg/l, respectively, p < 0.05). Conclusions. Significantly lower levels of plasma selenium in children with chronic destructive-inflammatory diseases of the upper gastrointestinal tract were found, which could be explained by the acute phase of inflammation in the mucous membrane of the stomach and duodenum resulting in a decrease in selenium absorption. In H. pylori-positive children, the level of selenium was significantly higher compared to H. pylori-negative children indicating a possible role of selenium in the pathogenesis and further progression of H. pylori-associated diseases.