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Abstract Background Control of intercellular penetration of microbial products is critical for the barrier function of oral epithelia. We demonstrated that CD24 is selectively and strongly expressed in the cells of the epithelial attachment to the tooth and the epithelial lining of the diseased periodontal pocket and studies in vitro showed that CD24 regulated expression of the epithelial intercellular adhesion protein E-cadherin. Results In the present study, the barrier function of oral epithelial cell monolayers to low molecular weight dextran was assayed as a model for the normal physiological function of the epithelial attachment to limit ingress of microbial products from oral microbial biofilms. Paracellular transfer of low molecular weight dextran across monolayers of oral epithelial cells was specifically decreased following incubation with anti-CD24 peptide antibody whereas passage of dextran across the monolayer was increased following silencing of mRNA for CD24. Changes in barrier function were related to the selective regulation of the genes encoding zonula occludens-1, zonula occludens-2 and occludin, proteins implicated in tight junctions. More particularly, enhanced barrier function was related to relocation of these proteins to the cell periphery, compatible with tight junctions. Conclusion CD24 has the constitutive function of maintaining expression of selected genes encoding tight junction components associated with a marginal barrier function of epithelial monolayers. Activation by binding of an external ligand to CD24 enhances this expression but is also effective in re-deployment of tight junction proteins that is aligned with enhanced intercellular barrier function. These results establish the potential of CD24 to act as a potent regulator of the intercellular barrier function of epithelia in response to local microbial ecology.

It is established that low-energy He-Ne laser without changes from the side of NADPH-dependent superoxide-producing activity of b558III cytochrome isolated from erythrocytic membranes (EM) promotes b558III activity decrease in EM. The level of metHb-restoring activity increases during irradiation by He-Ne laser. The form of optical spectrum of b558III cytochrome absorption in the visible spectrum area does not undergo essential changes after laser irradiation while optical spectral index (A412/A530) is reduced a little. It is supposed that in the basis of photochemical mechanisms of He-Ne laser protector action in oxidative stress lays its ability to increase EM stability due to a decrease of superoxide-producing and an increase of metHb-restoring activity of b558III cytochrome

Various stages of hypokinesia are marked by specific changes in the level and activity of endogenous metalloproteins with anti- (MAA) and prooxidant action (MPA). In particular, the level of MPA [cytochromes b5 and b558 (III + IV) and suprol] decreases in all stages (except for the level of cytochrome b5 exceeding that in the free control on the 15th and 30th day of hypokinesia). The superoxide production activity of suprol always exceeds that in the control, while the activity of cytochrome b558 (III) exceeds that in the control only on the 30th day of experiment. The level and activity of MAA [ceruloplasmin, transferrin (TF), superoxide dismutase (SOD), and catalase] decrease with the duration of hypokinesia (except for 15th day, when the level of TF and the activity of SOD exceed the values in the free control group). The administration of GABA and pyrrolidone decreases the extent of oxidative stress, which is manifested by leveling of the MAA and MPA content and activity.

Molecular mechanism of pathogenesis of psoriasis related with intensity of formation of oxygen active forms high concentration, depends on balance of pro-oxidant and antioxidant systems activity and leads to quantitative changes of toxic agents of peroxidation processes in blood. Observed results show disorders in Cu, Zn-superoxide dismutase activity and contents of ceruloplasmin, transferrin and new revealed pro-oxidant metalloproteins-cytochromes b558(III), b558(IV), b5, O2(-)-generating lipoprotein suprol and indicate of disturbances in intensity of lipid peroxidation processes. They are considered as obligatory but not specific link in molecular mechanisms of different etiology of oxidative stress formation being as important argument in pathogenesis of various diseases as well as psoriasis.

Unilateral ganglionsympathetectomy-removal of right upper cervical sympathetic ganglia and its combination with acute acoustic stress results in intensification of process of free radical oxidation of lipids and balance disturbance between components of antioxidative and pro-oxidative system of blood. Changes of composition and activity Cu, Zn-superoxide dismutase, catalase activity and contents of catalase, ceruloplasmin, transferrin and metalloproteins pro-oxidative action such as (cytochromes b558(I), b558(II), b558(III), b558(IV)) as well as O2-producing lipoprotein suprol and cytochromes b5 are evidence of compensating-adoptive function disturbances with according changes in blood, relatively to adaptive-trophic function of sympathetic system, its regulative role, in system of tissue metabolic conversion, which is directed, in particular, on compensation of anti-radical protection of cells.

Changes in the concentrations of antioxidant (Cu, Zn superoxide dismutase catalase, ceruloplasmin, and transferrin) and recently discovered pro-oxidant (cytochrome B-558 I-IV and suprol, a superoxide producing lipoprotein) metalloproteins and cytochrome B-5 were assessed in the blood of anesthesized and control rats. The concentrations of antioxidant and pro-oxidant metalloproteins varied. They were not changed during anesthesia, except suprol. As for the qualitative changes, phospholipid composition was altered, superoxide production decreased, and lipid peroxidation of suprol increased during anesthesia. The authors propose using antioxidant metalloproteins for decrease of the undesirable consequences of halothane anesthesia in experimental medicine.

Molecular mechanisms of the trauma stress of different origins in children to some extent is related to the quantitative changes of blood superoxide dismutase, catalase, ceruloplasmin, transferrin, cytochromes b5, b558III, b558IV and suprol. Non adequate changes of antioxidant (superoxide dismutase, catalase, ceruloplasmin, transferrin) and newly discovered prooxidant (cytochromes b5, b558III, b558IV, suprol) metalloproteins, as well as serum and erythrocyte cytochrome b5 depend on characteristic and duration of trauma stress caused by extremity fractures in children. This is due to the different mechanisms of adaptation to trauma stress.

Superoxide-generating lipoprotein was isolated and purified from human serum; four intraperitoneal injections of Fe(3+)-activated suprol (150 micrograms/ml) increased rat peripheral blood leukocytes only by 8-10% in 24 h. In 3 days after inoculation of animals with Pliss lymphosarcoma or M-1 sarcoma, similar injections of activated suprol increased leukocyte count up to the numbers in healthy animals. Growth of M-1 sarcoma and Pliss sarcoma was decreased by 31 +/- 4 and 52 +/- 2%, respectively. Activated suprol (15 micrograms/ml) stimulated growth of stationary chicken embryonic cell culture by 52.1%. Activated suprol at concentrations exceeding 50 micrograms/ml lysed all cells in the culture. Cu,Zn-superoxide dismutase suppressed suprol-stimulated proliferation of actively proliferating culture; not activated (native) suprol did not significantly increase leukocyte count, did not suppress tumor growth, and did not stimulate growth of cultured cells. The data suggest an important role of superoxide radicals in these processes. Inhibition of tumor growth by suprol may be associated with tumor DNA degradation by superoxide radicals (tumor DNA is more sensitive to O2- because superoxide dismutase activity is significantly lower in tumor cells versus normal tissues) and increased resistance of the organism due to stimulation of leukopoiesis.

A procedure for isolation and purification of the lipoprotein fraction from blood serum (human, rabbit, bovine, rat) has been developed which includes ion-exchange chromatography of the dialyzed serum on DEAE and CM cellulose and DEAE. Sephadex as well as gel filtration on Sephadex G-150 and biogel P-150. This fraction was purified until denaturation and loss of solubility. The optical purification index of this fraction (A280/A430) is 8.5. The fraction has an optical absorption spectrum with a maximum at 280 nm and a weakly expressed shoulder at 430 nm, its fluorescence spectrum has an excitation maximum at 370 nm and emission maximum at 430 nm characteristic of NADPH. The protein fraction presumably contains NADPH and about 50% of phospholipids. It is assumed that the mechanism of O2 production involves Fe3+ reduction to Fe2+ by NADPH and the electron transfer from Fe2+ to atmospheric oxygen. Suprol provides a simple and readily accessible source of superoxide radicals for the study of their effects on various biosystems.

Four types of water-soluble cytochromes b-558 (cyt. b-558) have been isolated and purified from blood serum (cyt. b-558 (I), cyt. b-558 (II)) and erythrocyte membranes (cyt. b-558 (III) and cyt. b-558 (IV)). The cytochromes differ in their acid-basic properties, molecular masses (110, 95, 125 and 80 kDa for cyt. b-558 (I), cyt. b-558 (II), b-558 (III) and cyt. b-558 (IV), respectively) as well as by the composition (cyt. b-558 (III) and cyt. b-558 (IV) are lipoproteins) and absorption maxima at the wavelengths of 340-360 nm. The cytochromes have similar absorption maxima at the wavelengths 600-400 nm (560, 530 and 412 nm in the oxidized state) and 558, 525 and 420 nm in the reduced state) which makes them identical to cytochromes b-558 obtained from blood constituents membranes.

The work deals with study of the possibility of increasing the efficacy of infusion therapy in massive blood loss by preliminary administration of superoxide dismutase (SOD). The data obtained bear evidence that in preliminary administration of SOD infusion of a blood substitute produces a more marked and stable improvement of central hemodynamics and microcirculation, oxygen regimen, and acid-base equilibrium in rats. A significant increase of the circulation volume and stroke volume of the heart following SOD injection may be linked with lesser intensity of lipid peroxidation in the cardiocyte membranes during reoxygenation.

Content and activity of endogenous superoxide dismutase (SOD) were decreased simultaneously with an increase in the rate of lipid peroxidation under conditions of burns trauma. At the same time, parameters of the EPR signal were unaltered. Administration of exogenous SOD normalized the patterns studied and increased distinctly the survival rate of rats.

The contents of Cu, Zn-superoxide dismutase and catalase isolated and purified from the rat liver at the terminal stages of alloxan diabetes were decreased by 40% and 15%, respectively, as compared to the control. It can be concluded that the decrease in superoxide dismutase and catalase activity in experimental alloxan diabetes is mainly connected with the decline in the content of these proteins at the terminal stages of the disease, this, probably, being the result of DNA degradation and RNA transport disturbances under the effect of oxygen active forms.

Patterns of ulcer-hemorrhagic impairments were distinctly decreased in gastric mucose of rats with emotional-painful stress after Cu, Zn-superoxide dismutase administration at a dose of 0.5 mg/kg every 30 min of the experiment. The protective effect of the enzyme was realized via regulation of free radical reactions as well as by means of maintaining of structure-functional activity of lipoprotein complexes in gastric mucose.

Optical and ESR spectra of erythrocyte superoxide dismutase denaturated with acid and alkali are described. Sharp changes in activity and spectra were found. "Residual" activity of alkaline denaturated protein was higher than of acidic denaturated sample. It is suggested that covalent bonding copper-nitrogen is essential for superoxide dismutase activity of the protein or synthetic copper complexes.

Cuprozinc superoxide dismutases were isolated from bovine liver, kidney and adrenal medulla. It was found that the enzyme from these sources exists in the form of three isoenzymes, the main izoenzyme being the most basic form. Physico-chemical properties of superoxide dismutases isolated from different tissues were found similar. Copper atoms in active sites of all superoxide dismutases investigated are bound with 4 nitrogen atoms.

The procedures for isolation and purification of Cu/Zn superoxide dismutase (SOD) from small amounts of rat liver at different stages of Pliss lymphosarcoma growth were developed. Two stages of tumour growth were distinguished. At the first stage (4-5th day after reinoculation) the intensity of optical (680 nm) and EPR spectra of SOD was decreased, on the average, to 30%, while at the second stage--by 40% at 680 nm and by 32%, at 260 nm. The intensity of the EPR spectra was also diminished by 40% as compared to the control. It was assumed that at initial stages of tumour growth the decrease of the SOD activity is mainly due to the reduction of enzyme Cu, while at the second stage--to the decrease of the protein content. In all probability, the observed changes are induced by the activation of lipid peroxidation involving active O2 species. The second stage is associated with the superoxide-induced impairment of the function of nucleic acids involved in protein biosynthesis.

The procedure for isolation of electrophoretically homogeneous preparation of erythrocuprein from 17 1 blood batch was described. The preparation had absorbtion value, A260/A680, of 25-26. The protein completely retains superoxide dismutase activity after treatment 7 min. at 75 degrees C. The heating of protein solution at 100 degrees C bring about autoreduction of protein copper as demonstrated by decreasing optical and EPR-spectral intensities. The reduced protein was oxidized in aerobic condition and oxidized preparation had optical and EPR-spectra differ from those of the native protein the activy being decreased.