MODERATION OF QUANTITATIVE CHANGES OF REGENERATING ERYTHROPOIETIC CELLS BY EXTRACELLULAR UBIQUITIN.

Hematological disorders caused by radiation remain the most challenging problem of the last decades. Environmental radiation, as well as medical application of radiation causes serious problems especially from the point of view of blood formation and passage of blood functional cells. Bone marrow emptying followed by the rise of immature cells in the bloodstream is the main pathology that must be eliminated. The importance of the issue is well recognized by all investigators. Opening of agents for regulation of spontaneous regeneration of hematopoietic cell lines is of prime importance in cancer treatment. Ubiquitin is a globular protein of eukaryotic cells. It is involved in regulation of cell cycle. Recently we studied the influence of extracellular ubiquitin on regeneration of leukopoiesis. Interestingly what is its effect on erythropoietic cell lines? Erythrocytes are more resistant to irradiation, than nucleic cells. Their depletion-elevation picks during blood regeneration clearly reveal low sharpness. Nevertheless, depletion of erythropoietic cells if not treated, may cause short- and long-term side effects. We studied the influence of intraperitoneally injected ubiquitin on the process of spontaneous regeneration of erythropoietic cell lines of bone marrow (BM) and peripheral blood (PB) after irradiation in mice. The source of radiation was 137Cs with dose rate 1Gy/min., the duration of exposure 3 min and 5 min. Nonlinear white mice of 22±2 gr. were used for experiment. Animals were divided into five groups (6 animals in each group): the first control group of intact mice; the second test group of mice irradiated by the sublethal dose of 3Gy; the third test group of mice irradiated by 3Gy intraperitoneally injected by ubiquitin by the dose of 100µg/ml at the 72 hour point after irradiation; the fourth test group of mice irradiated by the dose of LD50 5Gy; the fifth test group of mice irradiated by 5Gy intraperitoneally injected by ubiquitin at the 72 hour point after irradiation. PB and BM samples from the control group and the test groups of mice have been taken every 24 hours after irradiation during 7 days. Microscopy and statistical methods have been implicated for calculation of cell count of PB and BM. Analyzing the results we concluded that Ubiquitin prevents depletion-elevation picks of erythrocytes and erythroblasts regardless of the severity of damage caused by different doses of radiation indicating normalization of the regeneration process after irradiation. The study is important for opening new therapeutic agents for normalization of regeneration hematopoiesis after irradiation.

ALTERED MICROCIRCULATION IN SEPTIC SHOCK.

Retrospective data analysis of microcirculation in septic shock was conducted. Sepsis is characterized by a severe microvascular dysfunction that persists despite fluid resuscitation and leads to multi-organ failure even after normalization of hemodynamics in response to fluid resuscitation, vasopressors and the treatment of infection. Several clinical studies suggest that microcirculatory alterations in severe sepsis are stronger predictors of outcome than global hemodynamic variables. Microvascular dysfunction under septic shock is related to: increased capillary permeability that manifests as a breakdown of the microvascular endothelial barrier (factors which may contribute to capillary leak syndrome include endogenous proinflammatory cytokines, angiopoietin 2, vascular endothelial growth factor); arteriolar hyporesponsiveness to vasoconstrictors and vasodilators, the loss of adrenergic sensitivity and tone of smooth muscle cells lining the arterioles; loss of the anti-adhesive function of endothelial surfaces; decreased density of perfused capillaries (due to several contributing factors: decreased deformability of erythrocytes and neutrophils; activation of the clotting cascade with fibrin deposition and the formation of microthrombi; dysfunction of vascular autoregulatory mechanisms by nitric oxide; enhanced functional arteriovenous shunting of the microcirculation).

Myocardial dysfunction during septic shock (review).

Patients with septic shock frequently develop myocardial dysfunction evidenced by severely depressed ejection fraction with ventricular dilatation, as measured by an increase in mean systolic and end diastolic ventricular volumes. The pathophysiology of myocardial dysfunction is complex and involves a multitude of factors. The current review describes individual contributing factors and mechanisms such as upregulation of proinflammatory cytokines (IL-1, TNFα, IL-2, IL-6, IFN-γ), reduced myocardial responsiveness to ß-adrenergic stimulation, elevated circulating endothelin levels, Impaired calcium uptake and release from calcium sarcoplasmic reticulum storage, and decreased calcium channel sensitivity, overexpression of inducible NOS and increased production of Nitric oxide. We also discuss possible reasons for apparently detrimental effect of NO inhibition on cardiovascular function in large clinical trials with sepsis patients.

Role of oxidative stress in pathogenesis of atherosclerosis.

Atherosclerotic disease remains a major cause of death. Documented cases of atherosclerosis in Georgia (Caucasus) have increased by up to 40% and, moreover, the disease is occurring with increased frequency and greater severity in younger adults. Prevention of atherosclerosis as well as detection at early stages of the disease is reviewed. The authors argue that known indicators (serum cholesterol and triglycerides, blood pressure, life style factors) show up too late in the disease when damage is already extensive, still controllable to some extent, but irreversible. Imbalances in the redox status in which excess oxidation occurs or reducing power cannot be maintained (e.g. in inflammation, age, smoking, high lipid content and oxidation) creates a state in which molecular and tissue modifications progress rapidly, leading to development of lesions and full-blown atherogenesis. Oxidative stress do not replace the recognized role of lipids and cholesterol in atherosclerosis, but rather underline that role. Indeed, quantifying redox processes may well elucidate some molecular mechanisms by which lipids mediate atherogenesis.

[Mechanisms of gamma-inducible death of Jurkat cells line].

Mechanisms of radio-inducible death of Jurkat cells were investigated. Human lymphoblastoid T-cell line Jurkat is widely established model for studying apoptosis mechanisms. The cell was radiated by "Teragam" (Czech Republic) by dose 2 g during 1 minute. After radiation cells were incubated at standard conditions during 24 hours. After gamma radiation in cell population amount of cells in gaplois (apoptotic G 0) stage was increased 8,2 folds, in diplois (G 0/G1) stage - by 17%, in synthetic (S) stage decreased by 35% and tetraploid (G2/M) stage by 73% in comparison to control group. It was revealed intensive production of free radicals of oxygen and nitric oxide and decreasing activity of antioxidant enzymes (superoxidismutasa, catalasa and glutathione peroxidase). Revealed dependence between intensification of apoptosis and radiation-induced arrest of cell cycle G2/M phase may be determined by excess amount of free oxygen and nitrogen radicals generated in Jurkat cells as a result of nondirect effects of low doses of gamma radiation.