Biomedical subjects

T I Ronkina

Publications and source records attributed to T I Ronkina.

At least 19 recordsLinked to original sources

PubMed1993

[The activation of the proliferation of human corneal endothelium in malignant tumors of various sites and diabetes mellitus].

The morphological investigation of corneal endothelium was carried out in 205 human eyes of patients with malignant tumors of different localization including the eye, and also with diabetes mellitus. The investigation was performed in flat specimens by electron microscopy. In all types of pathology mitotic figures were found in endothelial population, most frequently in cases of diabetes of moderate and severe degree. Simultaneously the endothelial cell density increased significantly comprising in case of choroidal melanoma 2416 cell/mm2, in cancer of different localization 2916 cell/mm2; in the control group in 40-60-year-old patients 2160 cell/mm2; in diabetes mellitus of moderate and severe degree 2770 cell/mm2, in the control group in 60-80-year-old patients 1975 cell/mm. Simultaneously the endothelial cell area decreased significantly, the number of small unchanged cells of mitosis product increased and that of large cells diminished. Therefore, it growth factors in the host are more active, mitotic division of corneal endothelial cells will become more active as well.

Adult↗

PubMed1993

[Activation of corneal endothelial proliferation in cancers of various sites].

90 corneas from patients, 40 to 80 years old, who had died from carcinoma of mammary gland, lungs and other organs, and 20 corneas from patients of the same age dying from cardiovascular diseases, were studied. The density of endothelial cells was significantly increased in carcinoma patients (for example, 2939 cells/mm2 versus 2160 in control at the age of 40-60 years) with a simultaneous decrease of the cell surface. There was an increase in the number of cells with a small surface and a decrease in the number of binuclear cells. Mitosis (mainly prophase and telophase) is found in the endothelial cells of cancer patients.

Adult↗

PubMed1990

[The reparative potentials of human corneal endothelium from the aspect of age].

Morphometric and cytospectrophotometric studies of the endothelium of human cornea in age aspect, from 20 to 80 years, has revealed the presence of nuclei with double content of DNA (4 c) irrespective of age, as well as binuclear cells. Their number increases with age. At the age of 20-40 years, 4 tetraploid nuclei and 3 binuclear cells were found, and after 80 years of age - 45 tetraploid nuclei and 11 binuclear cells per a cornea. This speaks about the ability of the endothelium cell of the human cornea to incomplete polyploidizing cellular mitosis-variant of a normal proliferation of the cells and is characteristic for long-living and slightly proliferating tissues. The increase of the number of polyploid cells in the corneal endothelium with age speaks about activation of adaptation mechanisms in the course of age involution.

Adult↗

PubMed1989

[The biomechanical properties of the crystalline lens capsule in emmetropia and myopia].

Morphometric and electronmicroscopic studies of the capsule of a clear lens depending on the degree of myopia and age as compared with the capsule of a clear lens in emmetropia and myopia have shown that with age the anterior capsule of a clear lens becomes thicker, while the posterior capsule becomes thinner and increases in length. This is connected with the weakening of accommodation in the presence of different curvature of the anterior and posterior surfaces of the lens on the background of the lowering of the metabolic level in elderly persons. In myopia, with the development of age changes the thickness of the lens capsule remains almost unchanged. The degree of myopia doesn't influence the thickness and the length of the anterior capsule of the lens, while with the rise of myopia the thickness of the posterior capsules increases. No dystrophic changes in the structure of such a capsule in high myopia were revealed. Hypertrophy of the posterior capsule speaks about the increase of its mechanic strength in a clear lens and is connected with the weakness of accommodation. Such a capsule can serve as a support for IOL implants in patients with myopic refraction.

Adult↗

PubMed1989

[The early diagnosis, evaluation of treatment results and modelling of certain aspects of the pathogenesis of retinal dystrophy].

The paper analyses results after a study of the functional state of pigmented epithelium and the retina in patients with a dry form of senile macular dystrophy as well as of experimental simulation of retinal dystrophy with the help of melatonin and its treatment by taurine. Melatonin in 10(-3) M concentration leads to development of dystrophic changes in pigmented epithelium and interacting with it structures, this being testified by remarkable lowering of EOG parameters and electron microscopic findings. Taurine in 10(-3) M concentration blocks the action of exogenic melatonin as well as has a pronounced positive action on metabolism of dystrophic changes in the pigmented epithelium and photoreceptors. Examination of patients with different stages of a dry form of senile macular dystrophy revealed statistically significant reduction of KA cEOG at the initial stage of the disease in the presence of normal ERG parameters. In 18% of patients, supernormal values of KA were recorded, that are likely to reflect the presence of "predystrophic hyperactivity" of the pigmented epithelium cells. In progression of the process, the further reduction of electrophysiologic values was recorded. The data obtained speaks about the important role of pigmented epithelium pathology in the pathogenesis of senile macular dystrophy and about high information value of the cEOG method for detection of early stages of the disease. It is believed that disturbances in melatonin metabolism can be one of causes leading to development of retinal dystrophy.

Adult↗

PubMed1988