[CHARACTERISTICS OF OSTEOCYTE CELL LINES FROM BONES FORMED AS A RESULT OF MEMBRANOUS (SKULL BONES) AND CHONDRAL (LONG BONES) OSSIFICATION].

The aim of this work was to analyze the literature data and the results of authors' own research, to answer the question--if the osteocytes of bone tissues resulting from membranous and chondral ossification, belong to one or to different cell lines. The differences between the cells of osteocyte lines derived from bones resulting from membranous and chondral ossification were established in: 1) the magnitude of the mechanical signal, initiating the development of the process of mechanotransduction; 2) the nature of the relationship between the magnitude of the mechanical signal that initiates the reorganization of the architecture of bone structures and the resource of their strength; in membranous bones significantly lower mechanical signal caused a substantially greater increment of bone strength resource; 3) the biological activity of bone structures, bone fragments formed from membranous tissue were more optimal for transplantation; 4) the characteristics of expression of functional markers of bone cells at different stages of their differentiation; 5) the nature of the reaction of bone cells to mechanical stress; 6) the sensitivity of bone cells to one of the factors controlling the process of mechanotransduction (PGI2); 7) the functioning of osteocytes during lactation. These differences reflect the functional requirements to the bones of the skeleton--the supporting function in the bones of the limbs and the shaping and protection in the bones of the cranial vault. These data suggest that the results of research conducted on the bones of the skull, should not be transferred to the entire skeleton as a whole.

[Noncollagen bone proteins use in the composition of osteoplactic material Gapkol modified by vacuum].

In rat experiments the ability of noncollagen bone proteins (NCBP) in the composition of osteoplactic modified material Gapkol (not tanned in formalin and subjected to vacuum extraction) to increase bone reparation in comparison with traditional Gapkol was studied. Quantitative evaluation was performed on rat parietal bone and qualitative evaluation was performed on rat mandible. It was shown that Gapkol with NCBP (not tanned in formalin and subjected to vacuum extraction) increased reparative osteogenesis.

[Enforcing osseointegration of dental implantates spray-coated by bioceramics with the help of hyaluronic acid and hydroxyapatite gel in experimental conditions].

Influence of HAP-gel (2 g of 2% solution of hyaluronic acid mixed with 0,5 g of hydroxyapatite and 0,1 ml of colloidal silver) upon osseointegration in case of delayed introduction of titanium implantates in dog jaw. By scanning electron microscopy it was shown that solely use either of HAP-gel or of ceramic spraying increased direct contact area between bone and implantates in the 6 and 9 months time period. Combination of spray-coated ceramic with HAP-gel was effective in 3 months after implantation, when solely the HAP-gel or the ceramic spraying were little effective. In the following terms of experiment (6 and 9 months) significant differences between groups 3 and 4 (implantate with ceramic spraying but without HAP-gel in the alveolus and implantate with ceramic spraying and with HAP-gel in the alveolus) were not found. The area of implantate integration with jaw bone (cortical part of it was excluded) was equal to 80% and was maximal for the given conditions of the experiment.

[Experimental study of osseointegration of zirconium and titanium dental implants].

In an experiment performed on pigs, methods of light and scanning electron microscopy were used to study the interaction of zirconium and titanium dental implants with bone 6 months following their insertion. Distinct features of integration of both implant types with bone structures were detected. Sites of direct contact of bone structures with metal were found to undergo constant remodeling according to biochemical and metabolic conditions in each zone of an implant surface. Statistically the degree of interactive properties of zirconium implants significantly exceeded similar parameter for titanium screws. Along the perimeter of the zones of bone contact with zirconium implants greater numbers of forming and formed bone areas were revealed as compared to the zones of bone contact with titanium implants, where erosion lacunae were more numerous. The complex of research methods used in this study have not revealed distinct changes in the structure of osteocytes, located in immediate proximity to the metal surface in comparison with more distant sites in the bone.

Biocompatibility of Laser-deposited Hydroxyapatite Coatings on Titanium and Polymer Implant Materials.

We have investigated the biocompatibility of calcium phosphate coatings deposited by pulsed laser ablation from hydroxyapatite (HA) targets onto polyethylene and Teflon substrates. It was found that the cell density, attachment, and morphology of primary rat calvaria osteoblasts were influenced by both the original polymer and by the nature of the apatite coatings. HA coatings on Teflon were found to have higher biocompatibility in terms of cell adhesion and spreading. In vivo studies of bone response to coatings deposited by KrF excimer and CO2 lasers on commercial Ti6A14V alloy implants show that both deposition techniques suppress fibrous tissue formation and promote osteogenesis. © 1998 Society of Photo-Optical Instrumentation Engineers.

[Interrelation of matrix vesicles with spatial distribution of mineral component in fibrous and hyaline cartilages]. / Vzaimosviaz' puzyr'kov matriksa s prostranstvennym raspredeleniem mineral'nogo komponeneta voloknistogo i gialinovogo khriashchei.

Mineral components of the human fibrous and hyaline cartilages were studied by the methods of light, scanning, transmission electron microscopy and cryofractography. The interterritorial matrix of the fibrous cartilage was found to contain not only the local deposits of mineral in matrix vesicles, but also the calcified collagen fibrils and interfibrillar spaces forming the collagen fibers and occupying its major part. In the hyaline cartilage and in the territorial matrix of fibrous cartilage, mineral deposits were located in mineralized conglomerates, the basis of which was formed by matrix vesicles, surrounded by collagen fibrils and interfibrillar space substance. Such conglomerates participate in the formation of calcospherites.

[Structural organization of compact and cancellous tissue of human rib in aging]. / Strukturnaia organizatsiia kompaktnogo i gubchatogo veshchestva rebra cheloveka pri starenii.

Using the scanning electron microscopy the thickness of external and internal layers of compact bone of the rib as well as the structure of its cancellous bone was investigated in humans aged from 19 to 89 years. The differences of bone remodeling mechanism were found in men and women of the older age groups. In men, the gradual attenuation of osseous structures was taking place. In women, bone loss was found to be rapidly progressing due to the elimination of its structural elements (transformation of compact layer into cancellous bone and disappearance of some part of trabeculae from the latter).

[The bone regeneration process under chymotrypsin exposure (an experimental study)]. / Protsess regeneratsii kosti pod vozdeistviem khimotripsina (éksperimental'noe issledovanie).

Disturbance of femur diaphysis compact substance was induced experimentally in rabbits. In the course of the operation single administration of crystalline chimotripsin into the wound was performed and its influence on bony structures regeneration was studied. Methods of light and scanning electron microscopy revealed that reparative processes started earlier and were more active than that in control. This promotes regenerate formation and complete healing of bone defect. Intramuscular administration of proteolytic enzyme does not exert essential influence on bone regeneration.

[Ultrastructural organization of the human lamellar bone tissue mineral component in aged and elderly]. / Ul'trastrukturnaia organizatsiia mineral'nogo komponenta plastinchatoi kostnoi tkani u liudei zrelogo i starcheskogo vozrasta.

The lamellar bone mineral component in mature and senile age was studied using the methods of transmission electron microscopy and cryofractography. This component was shown to be formed by crystals (13-4 x 7-8 x 3-4 nm) of the prismatic shape that formed coplanar units (29-3 x 18-21 x 3-4 nm). The peculiarities of mineral particle distribution inside and between the collagen fibrils, as well as on the completely formed areas of bone surface, were detected. It was established that the length and the width of coplanar crystal aggregates was significantly higher in senile age as compared to similar linear parameters defined in persons of mature age (by 17-20 and 5-9%, respectively).

[Involvement of the anterior longitudinal ligament of the spine in the morphogenesis of osteophytes in spondylosis deformans]. / Ob uchastii perednei prodol'noi sviazki pozvonochnika v morfogeneze osteofitov pri deformiruiushchem spondileze.

Morphology and relief of the mineralizing front of osteophytes associated with lumbar spondylosis have been studied by means of scanning electron microscopy. During osteophyte formation deep-laid fibers of anterior longitudinal ligament of the spine undergo mineralization followed by their resorption and subsequent replacement by bone structures. Osteophyte surface at its apex consists of mineralized fibers of longitudinal ligament of the spine, formed by mineralized cartilage structures in the area adjacent to the intervertebral disk and by resting bone surface with zone of bone formation and resorption in the area adjacent to longitudinal ligament of the spine.

[Morphofunctional characteristics of the endosteum in connection with bone remodeling]. / Morfofunktsional'naia kharakteristika éndosta v sviazi s problemoi remodelirovaniia kosti.

Current information on the endost structure at different stages of bone remodelling is given on the basis of the original data and literature. Possible causes and character of the bone cells activity changes during the cycle of remodelling at the decreased functional stimulation on the bone structures and under pathological conditions are discussed.

[Morphological characteristics of aneurysmal bone cysts in children]. / Morfologicheskie osobennosti anevrizmal'nykh kostnykh kist u detei.

The morphology of aneurysmal bone cysts (ABC) in 10 children was studied by light and scanning electron microscopy. Angiodysplasia signs and disorder of bone remodeling occur in ABC areas leading to secondary hemodynamic disorders and abnormal bone remodeling with predominance of resorption in dynamics of remodeling.

[Study of a series of enzyme systems and ultrastructure of rat liver in iron-manganese poisoning]. / Izuchenie riada fermentnykh sistem i ul'trastruktury pecheni krys pri zhelezo-margantsevoi intoksikatsii.

During consumption of drinking water containing manganese or combination of iron and manganese several biochemical patterns were altered in animal blood and liver tissue: content of SH-groups, total lipids, activity of alkaline phosphatase, content of cytochromes b5 and P-450 in liver microsomal fractions. Light and electron microscopy showed that local unspecific alterations of hepatocytes structure occurred in liver tissue. Activation of cytochromes in response to administration of the metals appears to involve alterations in phospholipid composition of endoplasmic reticulum.

[The experimental validation of the potential use of hydroxyapatite-containing preparations for the obturation of the dentin tubules in prepared teeth]. / Eksperimental'noe obosnovanie vozmozhnosti ispol'zovaniia gidroksiapatitsoderzhashchikh preparatov dlia obturatsii dentinnykh trubochek preparirovannykh zubov.

Ultramicroscopic hydroxyapatite (UMHA) was used for obturation of dentine tubules of prepared teeth in dog experiments. Scanning electron microscopy showed that amorphous layer on the tooth surface prevents the penetration of UMHA in the tubules. This layer is not removed by the traditional treatment with alcohol and ether. Exposure of dentin to primer sintac altered the amorphous layer, but did not completely remove it. Solutions consisting of 10% citric acid and 3% iron chloride or 10% EDTA completely removed the amorphous layer in 1 min and permitted hydroxyapatite penetrate in the dentin canaliculi and obturate them. The agent more effectively penetrates in the dentin tubules of vital teeth than of pulp-free ones.

[Biocompatible coatings for metallic implants obtained by laser spraying]. / Biosovmestimye pokrytiia dlia metallicheskikh implantov, poluchennye lazernym napyleniem.

Use of various lasers and regimens for spraying the coatings and for additional thermal processing makes it possible to purposefully alter the morphology, composition, and crystallinity of the coatings, and hence, the optimal coatings, as regards their biological activity, may be created. Replacement of eximer lasers with CO2 lasers makes the spraying process cheaper and comparable in efficacy with the plasma process, with the quality of coatings and reproducibility of their parameters appreciably improved. Experiments with coatings of three types, sprayed by CO2 lasers, demonstrated that they met the mechanical and physico-chemical requirements of biocompatibility.

[The structural characteristics of the bony tissue at the surface of an implant with hydroxyapatite spray-coated with excimer and CO2 lasers]. / Osobennosti postroeniia kostnoi tkani u poverkhnosti implanta s pokrytiiami iz gidroksiapatita, napylennymi éksimernym i CO2-lazerami.

Rat experiments were performed to study osteogenesis and osseointegration in implanting fragments of dental titanic implants into the spongy bone. The implant spray-coating with hydroxyapatite produced by excimer and CO2 lasers stimulates osteogenesis. Bone tissue integration with implant proceeds more actively in response to CO2 laser radiation. The weakest integration was registered between the metal and bone tissues.

Effect of hydroxyapatite as a component of biostable composites on population and proliferation of mesenchymal stem cells.

Three groups of biostable composite materials were studied. The initial binder polymers (polymethylmethacrylate, polyamide-12, superhigh-molecular-weight polyethylene) and hydroxyapatite-containing composites on the basis of these polymers were tested. Biostable polymers, including those containing hydroxyapatite, were nontoxic for fibroblasts and mesenchymal stem cells: the adhesion parameters for these cells were maximum for polyamide-12 and superhigh-molecular-weight polyethylene and did not depend on the presence of hydroxyapatite. Cell adhesion to "pure" polymethylmethacrylate was significantly lower than to other composites, but increased after integration of hydroxyapatite. The efficiency of proliferation of fibroblast and mesenchymal stem cell on the surface of polyamide-12 and superhigh-molecular-weight polyethylene was maximum and did not depend on the presence of hydroxyapatite. The efficiency of cell proliferation on the surface of "pure" polymethylmethacrylate was low, but increased significantly if it was combined with hydroxyapatite, particularly in areas of mineral particles accumulation. It seems that the presence of high amounts of hydroxyapatite in polymethylmethacrylate samples promotes cell adhesion and proliferation.

[Morpho-functional correlations of the structure of bone cells and adjoining bone matrix in the developing bone]. / Morfofunktsional'nye korreliatsii struktury kostnykh kletok i podlezhashchego matriksa v razvivaiushcheisia kosti.

By means of scanning and transmissive electron microscopy methods structure of the developing bone has been studied. Interconnection of the cell structure and spatial organization of the adjoining matrix has been demonstrated. On the surface of the growing bone not only forming areas have been revealed, where under osteoblasts at various functional states, osteoid layer is determined, but also areas of resorption and completed osteogenesis. This demonstrates an interrupted character of osteogenesis at modelling. At the same time for the remodelling process presence of erosive lacunae is specific; they are filled with a newly deposited collagenous matrix. Therefore, it is possible to suppose that formation of the bone as an organ during the postnatal development includes in itself both mechanisms supporting its form at outgrowth of the osseous matrix volume (modeling) and its continuous rearrangement and adaptation to real conditions of functioning (remodelling).

[Structure of the spongy substance of the human vertebra in the elderly]. / Osobennosti struktury gubchatogo veshchestva pozvonkov cheloveka v pozhilom vozraste.

Structural peculiarities of the spongy substance samples from the lumbar vertebrae of elderly persons have been studied basing on qualitative and quantitative analysis of the raster-electronmicroscopic microphotos. The structural peculiarities and space organization of the spongy substance of the vertebral body have been studied in six topographically different zones. Mean thickness of the trabeculae and average width of the medullary spaces, as well as a relative volume of the osseous substance per volume unit of the spongy substance have been defined. Definite signs of the developing osteoporosis have been revealed in all the zones studied; the signs are mostly expressed in the central and superior zones of the vertebral body. Morphological signs of the age reorganization of the trabecular architectonics display in fenestration of the lamellar structures, up to their complete disappearance. Simultaneously, trabecules having cylindric form decrease in their thickness, and mean width of the medullary space increases.

[Topography of the mineralization front on different surfaces of the body of a vertebra]. / Rel'ef fronta mineralizatsii na razlichnykh poverkhnostiakh tela pozvonka.

Peculiarities of the relief of the mineralization front have been investigated on the periostal surface of the human vertebral body in several zones. The material has been obtained from male persons at the age of 20-84 years and studied by means of the light and scanning electron microscopy. The size of lateral surfaces of the vertebral body does not differ essentially from the relief of the periostal surfaces of other bones. In people of middle age certain changes in structure of the mineralized cartilage plate in the area adjoining the nucleus pulposus and the fibrous ring of the intervertebral disc are demonstrated. In persons of elderly and old age a definite decrease in thickness of the cortical layer of the vertebra is noted. At the same time, the plate of the mineralized cartilage adjoining the cortical layer grows thicker and collagene fibers in the spinal column ligaments undergo mineralization. Sometimes, microfractures of the cortical plate of the vertebral body and Schmorl noduli are revealed.