RESUMO
Alginate is a natural polymer widely applied in materials science, medicine, and biotechnology. Its ability to bind metal ions in order to form insoluble gels has been comprehensively used to create capsules for cell technology, drug delivery, biomedical materials, etc. To modify and predict the properties of cross-linked alginate, knowledge about the mechanism of alginate binding with metal ions and the properties of its gels is necessary. This article presents the results obtained by proton Nuclear Magnetic Resonance Spectroscopy for alginate containing calcium and strontium (alkaline earth metal diamagnetic) ions and by Electron Paramagnetic Resonance Spectroscopy for alginate with copper (Cu) and manganese (Mn) (transition metal paramagnetic) ions. It was found that in the case of calcium (Ca) and Mn ions, their concentration does not affect their distribution in the alginate structure and the cross-linking density. In the case of strontium (Sr) and Cu ions, their number affects the number of binding sites and, accordingly, the cross-linking density. Thus, the cross-linking of alginate depends mainly on the characteristics of specific cations, while the nature of the bond (ionic or coordination type) is less important.
RESUMO
There is a generally recognized need for a morphological assessment of the individual risk of developing gastric cancer in a patient with chronic gastritis, according to the OLGA system (Operative Link for Gastritis Assessment). At the same time, the role of assessing the biopsy from the incisura angularis remains controversial. The aim of our study was to assess the value of incisura angularis biopsy in staging gastritis according to the OLGA system by examining the atrophic and inflammatory changes in the antrum, incisura angularis, and body. MATERIALS AND METHODS: A total of 718 patients (576 women and 142 men) aged 20 to 84 years were examined. Most of the patients were in the age group of 50 to 70 years (54.6%). Depending on the detection of H. pylori and autoimmune gastritis markers, all patients were divided into three groups. The first group included 380 patients with H. pylori gastritis without signs of autoimmune gastritis. The second group consisted of 209 patients with autoimmune gastritis, in whom no infection was detected during the examination, and there were no indications of H. pylori eradication. The third group consisted of 129 patients with chronic gastritis of combined etiology (autoimmune and H. pylori). Endoscopy biopsies were taken according to the updated Sydney System. Histological assessments of the grade and the stage of gastritis were carried out according to the standard OLGA-based protocol. Then, the same assessments were evaluated without taking into account histological changes in the incisura angularis. RESULTS: When assessing the severity of inflammatory changes in the gastric mucosa according to the OLGA system, grade II (72.3%) was most often detected in all groups of patients. A severe degree of activity of chronic gastritis was most often observed in the group of patients with H. pylori gastritis (6.1%). These indicators practically did not change if the assessment did not take the angulus biopsy into account. When assessing the severity of atrophy of the glands in the gastric mucosa in patients of the first group, mild stages of atrophy prevailed. Without taking into account the angulus biopsy, a decrease in the stage of atrophy was observed in 27 cases (7.11%), and in only 4 cases did stage IV change to stage III, while in 23 cases, discrepancies were noted only within groups with a mild stage of atrophy. There were no transitions from stage III to stage II. In the group of patients with autoimmune gastritis, pronounced stages of atrophy prevailed-in more than 77%. Without taking into account the angulus biopsy, a decrease in the stage of atrophy was observed in eight cases (3.83%), and in three (1.4%) patients, stage III was changed to stage II. In the group of patients with combined etiology (autoimmune + H. pylori), severe stages of atrophy also prevailed (70.5%). A decrease in the stage of atrophy without taking into account the angulus biopsy was only observed in three patients (2.32%), of which two cases concerned patients with mild stages of atrophy. Thus, in general, severe stages of atrophy of the gastric mucosa (stages III and IV according to the OLGA staging system) were detected in 313 patients (43.59%). If the assessment of the atrophy stage did not take into account changes in the angulus biopsy, then severe stages of atrophy (III and IV according to OLGA) were detected in 310 patients (43.17%). In total, changes in the assessment of the atrophy stage occurred in 38 patients (5.29%), and this was more often observed in patients with stages I and II of atrophy. CONCLUSIONS: Accounting for histological changes in the incisura angularis does not significantly affect the assessment of the grade and stage of chronic gastritis according to the OLGA system, regardless of the etiology of atrophic gastritis.