[The influence of hyperoxic gas mixture on the respiratory part of the lungs in rats].

The respiratory part of the lungs was investigated in rats of 3 and 12 months of age before and after the influence of normobaric hyperoxic gas mixture (40 % and 90 % oxygen). We found the reduction in middle diameter, depth, cross-sectional area, width of the entrance to alveolus and the total width of respiratory bronchioles, alveolar ducts and sacs after 28 daily hyperoxic sessions (60 mines each). We detected increasing the amount of collagen fibers, the alveolar wall thickness and oxyproline concentration in a lung after breathing the hyperoxic gas mixture. These findings could indicate the connecting tissue growth in the respiratory part of the lungs and worsening of oxygen diffusion through the blood-air barrier. The investigated indexes changed to a greater degree in rats of 3 month of age.

[The effect of altered oxygen partial pressure on the resisitance to hypoxia and expression of oxygen-sensitive genes in Drosophila melanogaster].

As a result of resistance test to hypoxia of Drosophilas melanogaster of Oregon strain, we identified a high resistance (Group II) and low resistance (Group III) subpopulations of flies. Flies from groups II and III were incubated in a constant normobaric hypoxia (Po2=62-64 mm Hg) for 10 generations. A highly resistant group (Group IV) were exposed to a shortterm anoxia (Po,=1,5 mm Hg, 5 min) every generation. Larvae from Groups II, III, and IV demonstrated significantly elevated levels of Sir and CG 14740 expression. Larvae from Group II had a significantly higher expression of CG 14740 compared to group III. The restitution time after exposure to anoxia was significantly reduced in Group II (on 31% of the control values) Our results suggest that long-term adaptation to low oxygen partial pressure of highly resistant Drosophila significantly reduces the time of restitution and increases the expression of Sir2 and CG14740 genes.

[Effect of dosed diet restriction on physiological remodeling and bioelectric properties of bone].

The effect of dosed diet restriction on the physiological remodeling and bioelectric properties of bone tissue was studied in 48 male Wistar rats 3- and 18-months of age. The rate of bone tissue apposition was studied by the dynamic histomorphometry method (intravital tetracycline labeling). Electric potentials on the periosteal surface of the freshly isolated femurs were recorded. The magnitude of dielectric loss factor was determined to assess the quality of bone tissue. The control rats received a standard diet. The experimental rats received a limited diet (60 % of the standard mass) for 28 days. The magnitude and rate of the bone tissue apposition on the endosteal and periosteal surface of the tibia were less by 38.4% and 122.7% respectively in experimental rats after dosed diet restriction. Electric potential in the metaphyseal-epiphyseal growth zones of the femur was 29.7% lower, and the dielectric loss factor increased by 15.8%. The bone tissue apposition rate and the electric potential magnitude were increased 10 days after completion of the dosed diet restriction. The magnitude of the dielectric loss factor decreased after returning to the standard diet. Key words: dosed diet restriction, bone, remodelling, bioelectric properties.

[The influence of normobaric hypoxia on the morphofunctional changes of thyroid gland in young rats].

We investigated the influence of hypoxic gas mixture (the different modes) on the morphometric indexes of thyroid gland functional activity in 3-mounth rats. It was shown a decrease in the size of follicles of middle area and the colloid and an increase in the amount of thyrocytes in a follicle, resorption vacuoles and interfollicular epithelium after exposure to hypoxic gas mixture (10% oxygen). We also detected an increase in a follicle-colloid index and a decrease in the colloid accumulation index. Thus, a dosed normobaric hypoxia intensifies the functional activity and physiological regeneration processes of thyroid gland in the young animals.

[Determination of age-related liver stiffness changes in rats according to the ultrasonic shear wave elastography].

We examined by ultrasound shear wave elastography (SWE) changes of liver stiffness (LS) in three groups rats of different ages. LS measurement by SWE was performed on "Ultima PA" equipment ("Radmir", Kharkov, Ukraine) with a 10-5 MHz linear transducer. To assess the functional state of the liver at the same time we studied age-related biochemical and morphological differences in the liver. A valid LS determination (success rate of at least 60%) was observed in 96.6% animals of different age groups. We observed statistically significant increasing of LS between 3-month and 20-month rats (p = 0.010), but its value in each group do not exceed normal or reference range. In article discussed possible connection between age-related changes of LS and state of connective tissue elements, functional activity, hydration, etc. It is concluded that shear wave elastography may be a new objective biophysical method for obtaining information about the state of the liver stiffness of the liver tissue.

[The effects of oxygen partial pressure changes on the osteometric markers of the bone tissue in rats].

Our purpose was to investigate the oxygen partial pressure changes on the osteometric and biochemical markers of bone tissue in rats. It was shown that breathing of altered gas mixture did not change the mass, general length, sagittal diameter and density thigh-bones in 12-month Wistar male-rats. The dosed normobaric hypoxia increased the activity of alkaline phosphatase and decreased the activity of tartrate-resistant acid phosphatase. At the same time normobaric hyperoxia with 40 and 90% oxygen conversely decreased the activity of alkaline phosphatase and increased the activity of tartrate-resistant acid phosphatase.

[Dosed normobaric hypoxia as a non-medication approach of stimulation of physiological regeneration of liver parenchyma].

The investigation was devoted to studying the effects of different modes of dosed normobaric hypoxia on the changes in morphometric indexes of functional activity and physiological regeneration of liver parenchyma in young rats. It was shown, that in rats exposed to hypoxic gas mixture (10% O2), the amount of karyonucleus and binuclear hepatocytes, nucleocytoplasmic and nucleolar-nuclear correlation increased. The changes in these indexes appeared to be more intensive when dosed normobaric intermittent hypoxia was administered with alternation of deoxygenation and reoxygenation periods. We believe that dosed normobaric hypoxia increases the functional activity and physiological regeneration of liver parenchyma.

[Effect of normobaric hyperoxia on the markers of bone tissue metabolism].

We studied the influencing of normobaric hyperoxia one hour daily during 14 and 28 days on the bone metabolism for 3- and 12-monthly Wistar male-rats (n =80). It was shown, that breathed normobaric gas mixture with 90% O2 during 14 days significant reducing of C-terminal propeptides of type I collagen levels for 36%, an increasing piridinolin levels for 37% and concentration of C-terminal telopeptides of type I collagen for 8% in the blood serum. We found reliable decreasing the concentration ofpiridinolin levels for 27% in adult rats in the same conditions. The C-terminal propeptides of type I collagen levels did not change in any of the groups' research. We believe that 14 days normobaric hyperoxia (90%) in young animals accompanied by violation of collagen synthesis. The adult rats were more stable and had no changes after influence the two hyperoxia levels.

[Physiologic regeneration and functional activity of hepatocytes in normobaric hypoxia].

It was studied the effects of dosed normobaric hypoxia during 14 and 28 days on physiological regeneration and functional activity liver of parenhima fenomenas of adult rats. It was shown that after completion of experiment at rats increase sizes nucleus, the area of cytoplasm decrease, and also is increase the hepatocytes amount on tissue area unit. Concentration albumin increased after 14 days ofnormobaric hypoxia. Activity alanine aminotranferease increased and aspartate aminotransferase activity decreased after 28 days of dosed normobaric hypoxia. Thus our study suggested that normobaric hypoxia stimulante morphological marcers functional action and regenerator liver ability.

[The effect of dosed normobaric hypoxia on physiologic regeneration of the liver parenchima in young and old rats].

We studied the effect of dosed normobaric hypoxia during 28 days on functional state and physiological regeneration of liver parenchyma. After completion of experiments in 3 and 9-month old rats we observed an increase in the amount of hepatocytes per unit of tissue area, with hypertrophied nucleus and decreased cytoplasmic area. IGF-I gene expression in 9-month old animals was increased. Thus, our study suggests that normobaric hypoxia stimulates physiological regeneration of liver parenchyma in young and adult rats.

[Effect of alimentary deprivation on physiological regeneration of the liver parenchyma in young and mature rats].

It was studied the effects of alimentary deprivation during 28 days on functional state and physiological regeneration of liver. In 3 and 9-month rats it was shown an increase in the amount of hepatocytes per unit of area of tissue, their nucleis were hypertrophied, the area of cytoplasm was decreased, the number of binucleitic hepatocytes in 9-month animals was increased. Thus, our study suggests that a short-term 40% food limitation stimulates physiological regeneration of liver parenchyma.