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Biomedical subjects

I G Panova

Publications and source records attributed to I G Panova.

At least 19 recordsLinked to original sources
PubMed2005

In vivo and in vitro proliferative and differentiation activity of human embryonic retinal cells.

Differentiation of human embryonic retinal cells (20-22 weeks gestation) was studied using morphological, immunohistochemical, and biomolecular approaches. The retina included several regions differing by the degree of cell differentiation. Mitoses were rarely found in the marginal zone. This zone contained low differentiated cells. The central retinal area consisted of typical layers with differentiated cells. Culturing was accompanied by the formation of aggregates and neurospheres, where mitoses and progenitor or differentiated cells expressing markers of photoreceptors, neurons, and glia were found.

Cell Differentiation↗
PubMed1999

[Changes in the structural properties of the saliva with pH changes].

The pH and active concentration of sodium ions were measured by the potentiometric method and optic density and concentration of inorganic phosphorus by photoelectrocolorimetry in mixed salivary pools of 10 subjects aged 16-18 years. A cariogenic situation was simulated in these pools by slight acidification with hydrochloric acid solution, which led to structural changes. Oral fluid of subjects with negligible caries is more resistant to unfavorable effects than mixed saliva of subjects with a higher index of decayed/lost teeth. Experimental studies revealed that pH = 6.2 is the critical value of hydrogen index, at which structural properties of saliva are positively disturbed and its mineralizing potential decreases. The data contribute to elucidation of the molecular mechanisms of caries development.

Adolescent↗
PubMed1999

[The determination of the coagulation threshold of the electrolyte potassium chloride in human mixed saliva].

For quantitative assessment of the stability of dispersed phase corpuscles in the gingival fluid, coagulation threshold and coagulating effect of electrolyte KCl were studied in salivary pools of caries-resistant (CR) and caries-liable (CL) subjects by the optic method widely used for investigation of pure colloid systems. Test samples were prepared by mixing certain volumes of saliva, distilled water, and KCl. Light absorbance was measured by photoelectrocolorimetry on a MKMF-1 device and pH was measured by the potentiometric method using pH-121 device. Coagulation threshold and coagulating effect of the electrolyte were estimated using the graphic method. The saliva of both CR and CL subjects generally follows the regularities typical of pure colloid systems. KCl coagulation threshold of CR subjects' saliva is higher than of subjects with caries, while its coagulating effect is higher in the CL group. Dispersed phase corpuscles in the saliva of CR subjects are more stable than in subjects with caries. These results may be used in development of quantitative methods for assessing the stability of salivary dispersed phase corpuscles and salivary mineralizing capacity in subjects with different oral status.

Colloids↗
PubMed1996

[The structural properties of the saliva in the modelling of a cariogenic situation].

A cariogenic situation was modeled by soft acidification by hydrochloric acid in vitro in mixed salivary pool of 10 subjects aged 16-18, and the values of pH and active concentration of sodium ions, optic density, and concentration of inorganic phosphorus were studied. Soft acidification of human mixed saliva was found to result in its structural disorders. The saliva of subjects with negligible caries was more stable to unfavorable exposure than mixed saliva of subjects with a higher CFL index. Experiments showed that pH of 6.2 is the critical value causing evident destruction of the saliva and reducing its mineralizing potential. These data may be used in studies of the molecular mechanisms of caries development.

Adolescent↗
PubMed1990

[Electron microscopic and morphometric study of the effects of ENKAD preparation on photoreceptor cells of the retina in Campbell rats with hereditary retinal dystrophy].

The drug , a complex of ribonucleotides, which was found to improve the vision in some patients with retinitis pigmentosa, stimulates the morphogenesis of rod outer segments (ROS) in mutant Campbell rats with inherent retinal dystrophy. Four litters of neonatal rats, which being subdivided into groups, were injected subcutaneously with either 0.1 ml of 3.5% drug (experimental group) or 0.1 ml of 0.9% NaCl (control group) daily for 6-7 days. The results were checked in posterior area of the retina at Day 7 by the method of electron microscopy and morphometry. The drug treatment resulted in the 12-20 per cent increase of ROS disc number as compared with that in control group. Therefore, photoreceptors are the first retinal cells to be stimulated by the complex of ribonucleotides in rats.

Adjuvants, Immunologic↗
PubMed1983

Retinal pigment epithelium: pattern of proliferative activity and its regulation by intraocular pressure in postnatal rats.

The postnatal proliferative activity of retinal pigment epithelium (RPE) cells and its dependence on intraocular pressure were studied using [3H]thymidine and [14C]thymidine autoradiography in normal and experimentally induced microphthalmic pigmented rats. The regulation of RPE growth by intraocular pressure was shown to involve the control of the number of binucleated cells by means of stimulation of cell entry into the S phase of the cell cycle. Binucleated cells in the rat RPE are formed by acytokinetic mitoses between days 2 and 9. The significance of the postnatal proliferation and formation of binucleated cells in the RPE is discussed in terms of the specificity of the G2 phase for melanotropic hormone action on RPE differentiation.

Aging↗
PubMed1980

[Periodization of the postnatal proliferative activity in the rat retinal pigment epithelium detected by a method of experimental microphthalmia].

The dynamics of postnatal proliferative activity (PA) in the retinal pigment epithelium (RPE) and of its dependence on the general eye growth factor (intraocular pressure) was studied by means of 3H-thymidine autoradiography and experimental microphtalmia (lens removal from the eyes of the 1 and 4 days old rats). The regulation of RPE growth by the intraocular pressure was shown to be connected with the control of the number of cells by means of stimulation of their entry in S phase. The number of binucleated cells, formed as a result of acytokinetic mitosis, reflected the minimal number of cells proceeded through the reproduction cycle and was a weighted average, constant for each age and RPE zone. The first period of PA coincided with the most intensive growth of scleral part (2 to 5 days after birth) and was characterized by independence from the intraocular pressure and differences in PA intensity in different RPE zones (the highest in the central zone and dorsal and temporal regions of the equatorial zone). The second period (5 to 11 days) was dependent from the intraocular pressure and characterized by the levelling and decrease of PA in all RPE zones. The postnatal PA in RPE was characterized by a long G2 phase and a short G1 phase. The functional importance of PA and mass polyploidization of cells in RPE is discussed in the light of G2 phase specificity for the differentiating effect of melanotropic hormones on the pigment cells.

Animals↗
PubMed1978

[Effect of experimental arrest of eye growth on the proliferation and polyploidization of the retinal pigment epithelium in rats].

Following the lens removal from the left eye of the newborn rats, animals were obtained with one normal (control) and another microphtalmic eye. The animals were sacrificed on the 2nd, 3rd, 5th, 7th and 9th days of postnatal development after four injections of 3H-thymidine during 19 hrs. The number of labelled nuclei and mono- and binuclear cells in the central zone of the eye fundus was counted on the autographs. After the initial increase of the index of labelled nuclei in the operated eyes (on the 2nd, 3rd and 5th days) it fell below the control level (on the 7th and 9th days). The number of binuclear cells in the operated eyes, as well as in the control, attains on the 5th day 50% of the total number of cells and remains at this level up to the end of the experiment, whereas in the control eyes the number of binuclear cells increases up to 60% on the 7th and 80% on the 9th day. The results obtained have shown that in rats the factors of total eye growth participate in the control of proliferative activity and polyploidization of the pigment epithelium cells in the retina.

Age Factors↗