NEW APPROACHES TO THE TREATMENT OF PERIIMPLANTITIS (REVIEW).

Implant therapy, a modern treatment option for completely and partially edentulous patients. However, numerous clinical studies indicate a sufficiently large number (9-20%) of the failure rate of implants. The achievement of osseointegration depends on many factors, such as a suitable host, alteration in bone metabolism, hormone balance, smoking habits, and local conditions (quantity and quality of bone, biocompatible materials, traumatic surgical technique, occlusal conditions, quality of dental implants, and corrosion of the metal of implants, thoroughness of surgery and healing time). As can be seen from the review data, achievements in the field of dental implantation are based on a deep understanding of the fundamental cellular processes of regeneration and restoration of periodontal tissues, maintaining optimal local conditions that contribute to accelerating the regeneration process. A thorough knowledge of the cellular mechanisms of wound healing and the clinical consequences of modern periodontal treatments should provide further improvement or the development of new treatment strategies for the restoration and regeneration of soft tissues and dental implants. Various immuno-inflammatory mediators and bone-related molecules can be considered potential biomarkers that will be used for monitoring peri-implant health and disease. Their timely detection and systematic maintenance therapy may have a crucial impact on decreasing the occurrence of peri-implant lesions. Importantly, individual genetic data might contribute to therapeutic planning and prognosis, make its coordination depending on observed genotype. Supplementary evidence concerning the molecular pathophysiology of peri-implantitis may, in the future, benefit the treatment of dental implants, development of preventive approaches to avoid peri-implant tissue breakdown.

[The variants of changes in pro- and antioxidative processes in viral hepatitis and the necessity of differential approach in their antioxidative therapy].

There was investigated the changes in pro- and antioxidative processes in viral hepatitis of different etiology. It was revealed that the mechanisms mentioned above essentially differ from each other and for their treatment, accordingly, different groups of antioxidative drugs should be used. The data obtained indicates the impossibility of "universal" antioxidative therapy. The role of oxidative stress in the mechanisms of different types of hepatitis and unforeseen negative effect of antioxidative therapy requires special caution and attention in selection of mitochondrial respiratory chain stabilizing antioxidants. In hepatitis A, which is characterized by relatively less intensity of peroxidation natural antiradical remedies should be used (e.g. tocopherol). In viral hepatitis B and especially in hepatitis C, it is desirable to use the selenium-containing antioxidants. In hepatitis B, which is characterized by relatively less content of nitric oxide, it is recommended to use the stimulants of NO synthesis.

[The role of apoptosis in the development of virus hepatitis].

In present review hepatocyte apoptosis is presented as universal defensive reaction of liver, to the damages. Hepatocyte apoptosis may be caused by hepatotropic virus's direct affection, or by the immune reactions initiated by viruses. Apoptosis development caused by virus direct affection varies and contains at lest two mechanisms: production of specific proteins: B virus - X protein and C virus - core-protein; expression of the receptors leading the induction of this process on the hepatocyte membrane, for example, increasing of Fas-receptor and cell sensation to apoptosis stimulus. In apoptosis induced by immune reaction T-lymphocytes could trigger off apoptosis in two principal ways: by releasing perporines that produce holes through hepatocyte membrane and according to this process granzyms are permetted inside the cells. By destroying of caspases by proteases that initiate apoptosis cascade. In this article molecular mechanisms of the processes mentioned above are also discussed.

[The impact of ecopathologic factors on the development of dental diseases].

Environment pollution is listed as the most significant problem of the 21st century. In cities throughout the world, long periods of heavy air pollution have caused increase of illness rates. Effect of air pollution on the dental status of children in Tbilisi, Georgia (Caucasus) was studied. The research was conducted on 311 children aged 3-4 according to the standard method of WHO (caries spread, intense cavities and non cavitated teeth decay). A high rate of dental cavities (approx 98, 9%) and 8 individual cases of non-cavitated pathology of hard tissue of teeth was encountered in Tbilisi. It was found that tooth decay does not depend on the quotient of air pollution; at the same time, ecological index considerably affects the data of intense dental caries: it is higher in those parts of the city, where the pollution of the environment is high (6,0% and 3,9% accordingly). The research shows that the increase of ecotoxins in the atmosphere can affect not only the organs and system of the human organism, but also appears to be a risk factor for future dental pathology.

[Application of Populus Nigra preparations at experimental parodontitis].

Severe oxidative stress, developed under experimental periodontitis is accompanied by disturbances in mitochondrial respiration in tissue cells of gingiva, membrane damage and release of Fe(2+) and Mn(2+), leading to the worsening of inflammation process and gingival tissue necrosis. Reduction of free nitric oxide in gingival tissue appeared to be characteristic for experimental parodontitis: decreases local immunity, antimicrobial resistance, and tissue regeneration, disturbs blood supply and tissue trophism, which forwards important role in deepening of inflammation process and wasting of gingival tissue. Application of preparations derived from black poplar (Populus Nigra) gemma standardizes mitochondrial respiration, reduces presentation of inflammation, and considerably improves EPR-spectrum of gingival tissue. Though the complete normalization is not achieved--hazard of peroxidation still remains, the applied preparations, due to their strong anti- oxidative and anti-inflammatory activities is as an effective and rehabilitative means to tackle gingivitis and peiodontitis.

[Molecular mechanisms of apoptosis].

Apoptosis is the vital issue of Biology and Medicine. Recent concept of molecular and cellular mechanisms of apoptosis--a well-controlled form of cell death was reviewed. The aim of a review was to broaden knowledge of apoptosis mechanism and to reveal molecular targets for the modulation of these processes. The data on the apoptosis was analyzed. The biological role of physiological cell death in normal state and in different human pathologies is described. The literature data showed that many molecular mechanisms of apoptosis are still unknown. Three mechanisms are actually known to be involved in the apoptotic process: a receptor-ligand mediated mechanism, a mitochondrial pathway and a mechanism in which the endoplasmic reticulum plays a central role. Morphological and biochemical definitions of poptosis are presented. An original scheme of apoptosis mechanisms is constructed. The term "mediators of poptosis" is introduced. Extra cellular and intracellular mechanisms of apoptosis are examined. The special attention is paid to mitochondrial factors of apoptosis, Ca(2+)-ions, and proteins (Bcl-2, Bax, p-53).

[The role of changes in tissue redox-status in mechanism of paraneoplasia].

To specify mechanisms of paraneoplastic alterations of redox-status of tissues in experimental malignant tumor growth, we investigated electronic paramagnetic centers of blood, skeletal muscle and liver with electronic paramagnetic resonance (EPR) method. We also studied the concentration and activity of antioxidant enzymes. Our experiments on adult white male rats of mixed population with sarcoma C-45 and mice with Ehrlich carcinoma have shown that malignant tumor growth leads to enhanced lipid peroxidation (LPO): production of potent LPO promoters - Fe2+, Mn+2+, NO, ubiquinone; depression of antioxidant defence - reduced production of total ceruloplasmin, elevated blood levels of oxidized ceruloplasmin and enhanced catalase activity. It is suggested that malignant tumor growth is associated with marked paraneoplastic shifts in tissue redox-potential. These alterations are involved in mechanisms of paraneoplastic changes of red cells, microhemocirculation and circulation intensity. All these interrelated processes result in generalized paraneoplastic hypoxia of the organs and tissues. Basing on our and literature data, we propose an original scheme of the mechanisms of paraneoplastic disorders of tissue redox-status, microcirculation and erythrocytes.

Changes in the prooxidant and antioxidant status of tissues during paraneoplastic processes.

Electron paramagnetic resonance was used to identify paramagnetic centers in the blood and liver of laboratory rats with S-45 sarcoma and mice with Ehrlich carcinoma. Paraneoplastic changes in prooxidant and antioxidant activity of the blood and liver tissue, mitochondrial respiration, and NO metabolism and inhibition of antioxidant processes contribute to impairment of cell membrane structures, erythrocyte hemolysis, and hypoxia. An important role of these processes in the pathogenesis of paraneoplastic anemia is confirmed by the positive effect of antioxidant and membrane-stabilizing therapy.

[Relationship between lipid peroxidation processes, blood vessel wall changes and properties of erythrocytes in pathogenesis of microhemocirculation disorders during experimental diabetes mellitus].

The microhemocirculation play the main role in the development of the micro-and macroangiopathy during Diabetes Mellitus. The aim of our work was to study changes of free-radicals and deformability of erythrocytes using the filtration-photometric and electronic-paramagnetic methods in white rats during Alloxan Diabetes at different stages. Erythrocytes deformability was estimated by the time needed for erythrocytes passage through the filter and state of blood and blood vessels walls were studied by the EPR method. It had been detected that erythrocytes deformability sharply reduced and blood vessels wall was damaged by activation of lipid peroxidation and inhibition of antioxidant system, which may lead to disorders of microhemocirculation.

[Oxidative stress as common pathological phenomenon and possibilities of its correction].

It was shown that disorders of oxidative metabolism play an important role in the pathological processes which develops at subcellular level -- disorder of electron transport at ubichinon-oxidoreductase locus of respiratory chain in mitochondria. The latter could be discussed as common pathological phenomenon determining oxidative stress. It is found that altered synthesis and metabolism of nitric oxide plays an important role in the pathogenesis of oxidative stress. It has been detected the ways and mechanisms of disorders of NO synthesis and conversion. The negative role of widespread and irrational use of antioxidant therapy and "universal" antioxidant treatment was characterized.