Synthesis and Metabolism of Nitric Oxide (NO) in Chicken Embryos and in the Blood of Adult Chicken.

In chicken embryos, nitric oxide (NO) is accumulated in the pool of NO donors: S-nitrosothiols, nitrosyl-iron complexes, high-molecular-weight nitro-compounds. Oxidation of NO to nitrate occurs with different intensity in the embryos of different chicken breeds. In some embryos, NO donors accumulate almost without oxidation. Stable concentration of NO donors and nitrate in the blood of adult chicken is a result of dynamic equilibrium between NO synthesis and elimination (oxidation, consumption by other tissues, and excretion). As NO oxidation occurs mainly not in the blood, but in other tissues, decomposition of NO donors and NO oxidation are determined the properties of these tissues, in particular, the presence of physiological targets of NO, rather than spontaneous processes. Hence, evaluation of the intensity of NO metabolism is important for prediction of the efficiency of preparations containing NO donors and stimulators of its synthesis.

Mechanisms of Specific Embryonic Effects of Nitrogen Oxide.

The study of NO metabolism in chicken embryos showed that the intensity of oxidation of both endogenous and exogenous for the embryo NO donors to nitrate is determined by the presence or state of NO targets, rather than donor concentration. The mechanism of this oxidation and its physiological role are discussed. It was also shown that oxidation product nitrate is actively eliminated from the amnionic sac.

[STRUCTURE OF PARAPATELLAR CARTILAGES IN CANIDS].

The aim of the study was to establish general patterns and morphological characteristics of the parapatellar structures of the knee joint in canids: dogs of factory breeding - Caucasian shepherd dog (n=15), Central Asian shepherd dog (n=14), poodle (n=9), the toy Terrier (n=13), Yorkshire Terrier (n=14) and Steppenwolf (n=17) and foxes (n=7) obtained from natural biocenoses. Subtle anatomical dissection was conducted and macroscopic evaluation of the structures was performed together with light microscopic analysis of serial histological sections stained with hematoxylin-eosin and picrofuchsin-fuchselin. Comparative analysis of the parapatellar cartilages allowed to establish both common regularities and breed-specific signs of their structure, that resulted from the impact of biomechanics of the locomotor behavior of the animals. In all the investigated canids parapatellar cartilages were formed by fibrous cartilaginous tissue with a predominance of fibrous structures over the cellular component and they could be divided into 3 zones - superficial, medial and deep. The peculiarities of the fibroarchitectonics of collagen bundles in each of them correspond to the nature of the pattern of biomechanical loads applied. Micromorphological studies performed show that parapatellar cartilages can act as compensatory devices, leveling functional overload of the quadriceps femoris in the extension phase of the knee joint.

Morpho-tribo-mechanical characteristics of the articular cartilage in animals under conditions of hypokinesis.

The influence of activity upon the structure and properties of articular cartilage has been examined in two populations of fur-bearing animals. Morphological changes in cartilage of the caged animals were noted. Friction was mentioned in a vibrotribometer and it was noted that the caged animals exhibited a lower friction coefficient than the free-moving animals. In both cases the friction initially increased with age, reaching a maximum after about three years. It is concluded that prolonged hypokinesis associated with a cage-breeding regime acts like a mechanical stress factor which stimulates the development of degenerative changes in cartilage.

[Structural adaptations of the articular cartilage in fur-bearing animals under conditions of mobility]. / Strukturnye adaptatsii sustavnogo khriashcha u pushnykh zverei v usloviiakh razlichnoi podvizhnosti.

Adaptive properties of the articular cartilage and plasticity of its structures under various conditions of static-dynamic loading on joints have been studied when the data obtained in sables and minks, living in natural biocenosis and in cages, are compared. By means of optic, raster electron microscopy and microroentgenological analysis, peculiarities of structural formation of the articular cartilage have been revealed in ontogenesis, as well as succession in formation of its zonal architectonics. Conditions of prolonged hypodynamia are manifected as a number of anomalies in distribution of the cartilagenous integument of the joints affecting cellular and tissue levels of adaptation.

[Changes in the femur of fur-bearing animals during hypodynamia]. / Izmeneniia bedrennoi kosti pushnykh zverei v usloviiakh gipodinamii.

Under conditions of hypodynamia the form and internal architectonics of the femoral bone undergo certain changes. In young animals these changes are of quantitative character without any signs of a manifested destruction. Later on, certain indications of focal resorption appear in the spongy substance, as does partial destruction of the beams. Gradually, definite signs of osteoporosis and osteosclerosis as a result of dystrophic alterations in the osseous tissue develop. These phenomena, though progress with age, nevertheless, develop against the background of noticeable compensatory shifts in the osseous structures: increment in the mass of some osseous beams, appearance of new strengthening osseous plates in the spongiosa. The symptom complex at adaptational rearrangement of the bone under hypodynamia should be taken into account at differential diagnosis of these conditions both in the clinic and at experimental modelling.