Browsing by Author "Čolić, Miodrag (20933591700)"

Background/Aim. The deposition of hydroxyapatite (HAP) on the surface of titanium (Ti) alloys enhances bioactivity and osseointegration of the alloys which are widely used as implant materials in dentistry and orthopaedic surgery. However, the stability of HAP and subsequent biocompatibility of such alloys depends on the coating technique. The aim of this work was to test the cytotoxicity of a Ti alloy (Ti6Al4V), coated with HAP by a new plasma deposition method. Methods. The Ti6Al4V samples prepared as discs, 10 mm in diameter and 2 mm in thickness, were coated with HAP (one or both sides of the alloy) by an innovative atmospheric plasma jet method. The cytotoxicity of uncoated and HAP coated Ti6Al4V samples was evaluated by examining the morphological changes and viability of L929 fibroblasts in direct contact with the test materials. Adequate negative (polystyrene) and positive (nickel) control discs of the same size were used. The indirect cytotoxicity was determined by cultivating L929 cells with conditioning medium (CM), prepared as extract of the test samples incubated in the complete Roswell Park Memorial Institute (RPMI) 1640 medium for cell cultures. The cytotoxic effect was evaluated based on the degree of metabolic activity, necrosis, apoptosis and proliferation of L929 cells, using the appropriate assays. Results. Uncoated and one side HAP coated Ti6Al4V alloys were classified as non-cytotoxic according to the current ISO 10993-5 criteria, whereas two sides HAP coated Ti6Al4V alloy samples were slightlymoderate cytotoxic. The cytotoxicity manifested as the inhibition of metabolic activity and proliferation of L929 cells as well as the induction of their apoptosis and necrosis was significantly reduced by conditioning of HAP/Ti6Al4V alloys for 24 hours. The cytotoxic effect of HAP/Ti6Al4V CM only partly decreased in the presence of nifelate, a calcium (Ca) channel blocker, suggesting that Ca ions were not the only responsible cytotoxic agent. Conclusion. The original HAP coating procedure by atmospheric plasma spraying with high energy input enables the production of the stable adhesive coatings on Ti6Al4V alloys. Their cytotoxicity, which depends on the quantity of HAP coating layer, could be significantly reduced up to the non-cytotoxic level by prior conditioning of the alloys in culture medium. Such a procedure, which removes leachable toxic components, could be useful before implantation of HAP coated alloys in vivo. © 2019, Inst. Sci. inf., Univ. Defence in Belgrade. All rights reserved.

As revealed with ED1 and ED2 monoclonal antibodies, macrophages are scattered throughout the thymic tissue. However, in contrast to the cortex and medulla, in the cortico-medullary zone macrophages are large and show strong reactivity with rabbit polyclonal antisera to cyclooxygenase. Only few smaller cortical macrophages also show weaker presence of prostaglandin synthase. After cyclosporin treatment cortical macrophages become strikingly similar to the macrophages of the cortico-medullary zone of the normal thymus. Cortical macrophages become enlarged and develop the strong expression of prostaglandin synthase. Our results show that a specific type of macrophages (with distinct histochemical characteristics, enzyme profile and ultrastructural organization, which is strategically positioned within the thymic tissue - as we demonstrated earlier) possesses the enzyme capacity required for prostaglandin synthesis. After cyclosporin treatment, which interferes with the maturation of thymocytes, cortical macrophages thoroughly change and develop the strong prostaglandin synthase expression, similar to that of normal cortico-medullary zone macrophages. © 1994, Gustav Fischer Verlag · Stuttgart · Jena · New York. All rights reserved.

As revealed with ED1 and ED2 monoclonal antibodies, macrophages are scattered throughout the thymic tissue. However, in contrast to the cortex and medulla, in the cortico-medullary zone macrophages are large and show strong reactivity with rabbit polyclonal antisera to cyclooxygenase. Only few smaller cortical macrophages also show weaker presence of prostaglandin synthase. After cyclosporin treatment cortical macrophages become strikingly similar to the macrophages of the cortico-medullary zone of the normal thymus. Cortical macrophages become enlarged and develop the strong expression of prostaglandin synthase. Our results show that a specific type of macrophages (with distinct histochemical characteristics, enzyme profile and ultrastructural organization, which is strategically positioned within the thymic tissue - as we demonstrated earlier) possesses the enzyme capacity required for prostaglandin synthesis. After cyclosporin treatment, which interferes with the maturation of thymocytes, cortical macrophages thoroughly change and develop the strong prostaglandin synthase expression, similar to that of normal cortico-medullary zone macrophages. © 1994, Gustav Fischer Verlag · Stuttgart · Jena · New York. All rights reserved.

Objectives: The aims of this study were to evaluate the morphometric and structural characteristics of abdominal aortic aneurysms (AAA), and to form a morphometric model of the AAA that could be applicable in the development of mathematical and computation models for rupture risk assessment. Material and Methods: The following morphometric parameters significant for biomechanical stability and compliance of the aortic wall were analyzed: the thickness of the wall, the thickness of the media and the thickness of the adventitia. Morphometry was performed with the Olympus BX 41 microscope and the Olympus C - 5060 wide zoom digital camera with an application of the Olympus DP-soft Image Analyzer program. The media-to-wall and adventitia-to-wall ratios were calculated. Parameters were correlated with the diameters of the aneurysms (established by MSCT angiography), the patients' age and gender, the presence of a thrombus and the grade of inflammation. Results and Discussion: Our results showed that an increase in the AAA diameter affected the structure of the aortic wall in the following ways: 1. the thickness of the aortic wall significantly increased, with the greatest increase for aneurysms with diameters between 41 and 60 mm (ANOVA F=268.561; p<0.001); 2. the thickness of the adventitia and its proportion in the wall thickness significantly increased, in the same group (ANOVA F=376.727, p<0.001); 3. the thickness of the media and its proportion in the wall thickness significantly decreased, with the greatest increase for aneurysms with diameters >60mm (ANOVA F=265.865; p<0,001). The supposed influence of the latter two factors reduced the adaptability of the vascular wall and augmented the rupture risk since the aortic wall media is responsible for the elastic properties of the blood vessels, while increased and fibrotic adventitia did not provide sufficient compliance. We confirmed, by means of the Univariate Analysis of Variance, that the increase of the adventitia and destruction of the media were even greater in aneurysms with inflammation and in patients over 65 years old. Female patients with small aneurysms (d<40mm) are at a special rupture risk. They have a significantly thinner wall (F=35.164; p<0.001), with a significantly thinner media (F=35.473; p<0.001) and a significantly thicker adventitia (F=21.146; p<0.001) than male patients. Small-diameter aneurysms with a thrombus are also under special rupture risk. Destruction of the media was advanced in this group, with an exceptionally small medial thickness compared to larger aneurysms with a thrombus (F=237.770; p<0.001). Conclusions and Clinical Relevance: A correction of AAA computation models with histomorphometric data is necessary for an accurate prediction of rupture risk. Parameters used in computation models are based on CT scans, but not all parameters are easily assessed with a CT scan (i.e., the wall thickness). Most of the computation models operate under the assumption that aneurysms are homogenous structures, which is not the case. On the contrary, aneurysms are heterogeneous, with extreme variations of structure among patients and in different parts of the same aneurysm. Some data are not uniquely defined and recognized, (i.e., the influence of a thrombus on the wall structure). Hence, the goal of morphometric models is to provide sufficient data for the construction of an improved and adjustable model for rupture risk prediction that will combine many different factors and enable a tailored decision making process for each patient. © 2009 Nova Science Publishers, Inc.

Background & objectives: Aluminum (Al) toxicity is closely linked to the pathogenesis of Alzheimer's disease (AD). This experimental study was aimed to investigate the active avoidance behaviour of rats after intrahippocampal injection of Al, and biochemical and immunohistochemical changes in three bilateral brain structures namely, forebrain cortex (FBCx), hippocampus and basal forebrain (BF). Methods: Seven days after intra-hippocampal (CA1 sector) injection of AlCl3 into adult male Wistar rats they were subjected to two-way active avoidance (AA) tests over five consecutive days. Control rats were treated with 0.9% w/v saline. The animals were decapitated on the day 12 post-injection. The activities of acetylcholinesterase (AChE) and glucose-6-phosphate dehydrogenase (G6PDH) were measured in the FBCx, hippocampus and BF. Immunohistochemical staining was performed for transferrin receptors, amyloid β and tau protein. Results: The activities of both AChE and G6PDH were found to be decreased bilaterally in the FBCx, hippocampus and basal forebrain compared to those of control rats. The number of correct AA responses was reduced by AlCl3 treatment. G6PDH administered prior to AlCl3 resulted in a reversal of the effects of AlCl3 on both biochemical and behavioural parameters. Strong immunohistochemical staining of transferrin receptors was found bilaterally in the FBCx and the hippocampus in all three study groups. In addition, very strong amyloid β staining was detected bilaterally in all structures in AlCl3-treated rats but was moderate in G6PDH/AlCl3-treated rats. Strong tau staining was noted bilaterally in AlCl3-treated rats. In contrast, tau staining was only moderate in G6PDH/AlCl3-treated rats. Interpretation & conclusions: Our findings indicated that the G6PDH alleviated the signs of behavioural and biochemical effects of AlCl3-treatment suggesting its involvement in the pathogenesis of Al neurotoxicity and its potential therapeutic benefit. The present model could serve as a useful tool in AD investigations.

Widespread coronavirus disease (COVID)-19 is causing pneumonia, respiratory and multiorgan failure in susceptible individuals. Dysregulated immune response marks severe COVID-19, but the immunological mechanisms driving COVID-19 pathogenesis are still largely unknown, which is hampering the development of efficient treatments. Here we analyzed ~140 parameters of cellular and humoral immune response in peripheral blood of 41 COVID-19 patients and 16 age/gender-matched healthy donors by flow-cytometry, quantitative PCR, western blot and ELISA, followed by integrated correlation analyses with ~30 common clinical and laboratory parameters. We found that lymphocytopenia in severe COVID-19 patients (n=20) strongly affects T, NK and NKT cells, but not B cells and antibody production. Unlike increased activation of ICOS-1+ CD4+ T cells in mild COVID-19 patients (n=21), T cells in severe patients showed impaired activation, low IFN-γ production and high functional exhaustion, which correlated with significantly down-regulated HLA-DR expression in monocytes, dendritic cells and B cells. The latter phenomenon was followed by lower interferon responsive factor (IRF)-8 and autophagy-related genes expressions, and the expansion of myeloid derived suppressor cells (MDSC). Intriguingly, PD-L1-, ILT-3-, and IDO-1-expressing monocytic MDSC were the dominant producers of IL-6 and IL-10, which correlated with the increased inflammation and accumulation of regulatory B and T cell subsets in severe COVID-19 patients. Overall, down-regulated IRF-8 and autophagy-related genes expression, and the expansion of MDSC subsets could play critical roles in dysregulating T cell response in COVID-19, which could have large implications in diagnostics and design of novel therapeutics for this disease. © Copyright © 2021 Tomić, Đokić, Stevanović, Ilić, Gruden-Movsesijan, Dinić, Radojević, Bekić, Mitrović, Tomašević, Mikić, Stojanović and Čolić.

Widespread coronavirus disease (COVID)-19 is causing pneumonia, respiratory and multiorgan failure in susceptible individuals. Dysregulated immune response marks severe COVID-19, but the immunological mechanisms driving COVID-19 pathogenesis are still largely unknown, which is hampering the development of efficient treatments. Here we analyzed ~140 parameters of cellular and humoral immune response in peripheral blood of 41 COVID-19 patients and 16 age/gender-matched healthy donors by flow-cytometry, quantitative PCR, western blot and ELISA, followed by integrated correlation analyses with ~30 common clinical and laboratory parameters. We found that lymphocytopenia in severe COVID-19 patients (n=20) strongly affects T, NK and NKT cells, but not B cells and antibody production. Unlike increased activation of ICOS-1+ CD4+ T cells in mild COVID-19 patients (n=21), T cells in severe patients showed impaired activation, low IFN-γ production and high functional exhaustion, which correlated with significantly down-regulated HLA-DR expression in monocytes, dendritic cells and B cells. The latter phenomenon was followed by lower interferon responsive factor (IRF)-8 and autophagy-related genes expressions, and the expansion of myeloid derived suppressor cells (MDSC). Intriguingly, PD-L1-, ILT-3-, and IDO-1-expressing monocytic MDSC were the dominant producers of IL-6 and IL-10, which correlated with the increased inflammation and accumulation of regulatory B and T cell subsets in severe COVID-19 patients. Overall, down-regulated IRF-8 and autophagy-related genes expression, and the expansion of MDSC subsets could play critical roles in dysregulating T cell response in COVID-19, which could have large implications in diagnostics and design of novel therapeutics for this disease. © Copyright © 2021 Tomić, Đokić, Stevanović, Ilić, Gruden-Movsesijan, Dinić, Radojević, Bekić, Mitrović, Tomašević, Mikić, Stojanović and Čolić.

In our previous experiments, we demonstrated that xylazine, an α 2 -adrenergic agonist, stimulated proliferation of thymocytes triggered by concanavalin A. In contrast, higher concentrations of xylazine were inhibitory. In this work, we studied the mechanisms involved in immunosuppression of xylazine and found that the compound at concentrations between 100 μM and 500 μM induced apoptosis of rat thymocytes in vitro. In addition, xylazine at concentrations higher than 50 μM also induced apoptosis of a thymocyte hybridoma (BWRT8) and increased apoptosis of the line triggered by T cell receptor (TCR) cross-linking. Apoptosis was confirmed by morphological analysis staining with merocyanine 540 and propidium iodide and in cases of BWRT8 by fragmentation of DNA. The mechanisms of xylazine-induced apoptosis of the BWRT8 hybridoma were further examined. We demonstrated that the process in both nonactivated and activated (TCR cross-linking) BWRT8 cells was not prevented by yohimbine (a selective α-adrenergic antagonist) and by antibodies to Fas and Fas-L. In contrast, cell death was completely blocked by a caspase inhibitor, z-Val-Ala-Asp (OMe)-CH2F. Cyclosporine, a calcineurin blocker, partly inhibited the xylazine-induced apoptosis of activated BWRT8 cells. © 2003 Prous Science. All rights reserved.

In our previous experiments, we demonstrated that xylazine, an α 2 -adrenergic agonist, stimulated proliferation of thymocytes triggered by concanavalin A. In contrast, higher concentrations of xylazine were inhibitory. In this work, we studied the mechanisms involved in immunosuppression of xylazine and found that the compound at concentrations between 100 μM and 500 μM induced apoptosis of rat thymocytes in vitro. In addition, xylazine at concentrations higher than 50 μM also induced apoptosis of a thymocyte hybridoma (BWRT8) and increased apoptosis of the line triggered by T cell receptor (TCR) cross-linking. Apoptosis was confirmed by morphological analysis staining with merocyanine 540 and propidium iodide and in cases of BWRT8 by fragmentation of DNA. The mechanisms of xylazine-induced apoptosis of the BWRT8 hybridoma were further examined. We demonstrated that the process in both nonactivated and activated (TCR cross-linking) BWRT8 cells was not prevented by yohimbine (a selective α-adrenergic antagonist) and by antibodies to Fas and Fas-L. In contrast, cell death was completely blocked by a caspase inhibitor, z-Val-Ala-Asp (OMe)-CH2F. Cyclosporine, a calcineurin blocker, partly inhibited the xylazine-induced apoptosis of activated BWRT8 cells. © 2003 Prous Science. All rights reserved.