[APUD- and RAA- regulatory systems in acute radiation injury]. / APUD- i RAA-sistemy reguliatsii pri ostrom radiatsionnom porazhenii.

An experimental morpho-functional assessment of rat APUD and RAA systems status in acute radiation injury (cerebral form) was performed. The named regulatory systems were found to display an actual momentary post-exposure reaction, followed by subsequent functional changes of a distinct phase character. The latter were shown to determine in many respects the clinical picture and in some cases the outcome of the disease.

Ultrastructure of the rat duodenal endocrine cells after prolonged irradiation.

We propose classification of duodenal endocrine cells of intact rats based on ultrastructural signs of secretory granules and subdivided these cells into 10 basic types. The effect of long-term irradiation in a total dose of 2.5 Gy on ultrastructural organization of duodenal apudocytes was studied. Irradiation induced nonspecific changes of cell organelles in apudocytes. Differences in the ultrastructural disorganization were detected between different types of apudocyte populations and between different types of endocrine cells. Under conditions of adaptation to radiation apudocytes released the secretory product not only through molecular extrusion and exocytosis, but also via degranulation.

[Current methods for studying the functional morphology of apud cells]. / Sovremennye metody izucheniia funktsional'noi morfologii éndokrinnykh kletok.

The paper reviews methods for studying functional morphology of endocrine cells histochemistry and immunohistochemistry, radioautography and methods of ultrastructural verification of secretory granules. Methodological approach is illustrated by the authors' results on the influence of ionizing radiation and tumor growth on the cells of the diffuse endocrine system.

Diffuse neuroendocrine system: structural and functional effects of radiation injury to amine precursor uptake and decarboxylation (APUD) cells.

The paper presents a review of the results obtained by the authors on the study of external (gamma) and internal (I-131) radiation effects on the functional morphology and linkage of the diffuse neuroendocrine system (DNES) and amine precursor uptake and decarboxylation (APUD) cells of the stomach and duodenum. The investigations performed enabled us to determine that the morphological changes noted in APUD cells had a dose and time dependency. The present study supports the point of view that the radiation initiates serotonin release from APUD cells, which appears to initiate the mechanism of early postirradiation dysfunctions of the gastrointestinal tract and the subsequent adaptive response of DNES. Analysis of our results, together with a review of the literature, indicates that APUD cells actively participate both in pathogenesis of radiation injury and development of organ and tissue radiosensitivity.

Intestinal endocrine cells in radiation enteritis.

In this study, the intestinal endocrine cells were investigated in 13 surgical specimens affected by radiation enteritis. Endocrine cells were studied by means of Grimelius' silver staining and immunostaining for chromogranin, a general marker of endocrine cells. Positively stained cells were quantified by counting their number per unit length of muscularis mucosa. Results in radiation enteritis were compared with matched control specimens by using Student's t test. Chromogranin immunostaining showed a statistically significant increase of endocrine cells in radiation enteritis specimens compared with controls both in small and large intestine (ileum, 67.5 +/- 23.5 cells per unit length of muscularis mucosa in radiation enteritis versus 17.0 +/- 6.1 in controls; colon, 40.9 +/- 13.7 cells per unit length of muscularis mucosa in radiation enteritis versus 9.5 +/- 4.1 in controls--p less than 0.005 in both instances). Increase of endocrine cells was demonstrated also by Grimelius' staining; however, without reaching statistical significance. It is not clear whether or not the increase of endocrine cells in radiation enteritis reported in this study is caused by a hyperplastic response or by a sparing phenomenon. We should consider that increased endocrine cells, when abnormally secreting their products, may be involved in some of the clinical features of radiation enteropathy. In addition, as intestinal endocrine cells produce trophic substances to the intestine, their increase could be responsible for the raised risk of developing carcinoma of the intestine in long standing radiation enteritis.

[Postradiation death and recovery of duodenal APUD cells in rats]. / Postradiatsionnaia gibel' i vosstanovlenie APUD-kletok dvenadtsatiperstnoi kishki krys.

Electron microscopy has revealed death of some of the apudocytes and recovery of the other ones in small intestine of rats after single total body irradiation in sublethal dose (5 Gy) and local fractionated irradiation (35 Gy, 7 Gy X 5) of the abdomen. The ability of EC-cells to form the autophagosomes was found. An absence of uniform reaction of different types of apudocytes to radiation is discussed.

[Radiation pathomorphology of the APUD system]. / Radiatsionnaia patomorfologiia APUD-sistemy.

Complex histological, histochemical, immunological and electron-microscopic studies made it possible to receive new data on functional morphology of the endocrine cells of the APUD system in norm, radiation exposure and tumor growth. The data obtained are being discussed and analysed and optimal methods of optimization of radiation and chemotherapy of malignant tumors are being developed.