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Biomedical subjects

Y V Bobryshev

Publications and source records attributed to Y V Bobryshev.

At least 19 recordsLinked to original sources
PubMed2005

Cellular destruction following transmyocardial laser revascularization (TMR).

During transmyocardial revascularization, cellular destruction of cardiomyocytes occurs as a result of the high-energy laser. However, the features of myocardial cellular destruction are unclear. The present study was undertaken to examine the structural characteristics of cell death in the myocardium following transmyocardial revascularization. Myocardial specimens from 3 male patients who had died within 11 days following laser revascularization were collected within 1 h of death and were analyzed by immunohistochemistry and electron microscopy. For immunohistochemistry, antibodies to pro-apoptotic proteins CPP32 and BAX were used. Immunohistochemical examination demonstrated the presence of cells expressing both CPP32 and BAX along the laser channel. Electron microscopic analysis revealed that the lining surface of laser channels consisted of condensed acellular debris and dead cells. No endothelialization of channels was noted. The lumen of laser channels were surrounded by a rim of acellular debris with several outer concentric rims of cardiomyocytes showing features of cellular destruction. The present study identified features of both necrotic and apoptotic cellular death following laser revascularization.

Adult↗
PubMed2002

Hallmarks of atherosclerotic lesion development with special reference to immune inflammatory mechanisms.

Atherosclerosis is a complex disease that starts during childhood and becomes clinically evident later in life. Atherosclerosis results from an interaction between diverse factors including lipid metabolism, blood coagulation elements, cytokines and hemodynamic stress. Humoral and cellular immune reactions are key events in pathogenesis with the balance between pro-inflammatory and anti-inflammatory stimuli being crucial for the development of atherosclerotic lesions. Atherosclerotic lesions are characterised by the presence of immune competent cells including T-cells and dendritic cells. Dendritic cell interactions with T-cells might be responsible for T-cell activation in atherogenesis. Despite increasing acknowledgment that immune-inflammatory processes participate in atherogenesis, the immune mechanisms remain incompletely defined.

Arteriosclerosis↗
PubMed2002

Identification of dendritic cells in aortic atherosclerotic lesions in rats with diet-induced hypercholesterolaemia.

We have previously identified dendritic cells (DCs) in the intima of human large arteries. These vascular DCs are common in atherosclerotic lesions but their immature forms are also present in normal arterial intima. Pathophysiological studies on vascular DCs are limited because they have only been studied in human specimens obtained at operation or post-mortem. The aim of the current study was to determine whether DCs participate in the development of atherosclerotic lesions in hypercholesterolemic rats. Male Wistar rats were divided into a control (n=13) and experimental cohort (n=48). The experimental animals were fed an atherogenic diet and 1% saline, while the controls were fed standard rat cubes and water. The aortas were obtained from both groups at 10, 20, and 30 weeks following commencement of the diet. An en face immunohistochemical technique, routine section immunohistochemistry, and transmission electron microscopy were used to detect the presence of DCs in the aortas. Examination of the aortas showed that S100+ cells with dendritic cell morphology were present in the aortic intima of hypercholesterolemic rats. The S100+ DCs displayed immunopositivity for OX-62 and MHC Class II antibodies. Within various types of atherosclerotic lesions, these cells were clustered throughout the intima but were especially prominent around arterial branch-points where they co-localized with various cell types, including T-cells and macrophages. Ultrastructural analysis confirmed the presence of cells with characteristics typical of DCs. These features included the presence of a well-developed tubulovesicular system, dendritic processes, and a lack of secondary lysosomes and phagosomes. This study establishes the presence of DCs in the aortic intima of rats with diet-induced atherosclerosis. The presence of DCs in this model of experimental atherogenesis could provide a new approach to investigating the function of DCs and may help clarify the immune-inflammatory mechanisms underlying atherosclerosis.

Animals↗
PubMed2001

Induction of the transcriptional repressor Yin Yang-1 by vascular cell injury. Autocrine/paracrine role of endogenous fibroblast growth factor-2.

Yin Yang-1 (YY1) is a multifunctional transcription factor that can repress the expression of many growth factor, hormone, and cytokine genes implicated in atherogenesis. YY1 expression is activated in rat vascular smooth muscle cells shortly after injury. YY1 DNA binding activity paralleled elevated protein levels in the nucleus. Smooth muscle cell injury triggered the rapid extracellular release of immunoreactive fibroblast growth factor-2 (FGF-2). YY1 induction after injury was blocked by neutralizing antibodies directed against FGF-2. This growth factor increased YY1 mRNA and protein expression and stimulated YY1 binding and transcriptional activity. Overexpression of YY1 inhibited smooth muscle cell replication. Immunohistochemical analysis demonstrated YY1 staining in medial smooth muscle cells, coincident with FGF-2 expression. Proliferating cell nuclear antigen staining, in contrast, was confined mainly to the atherosclerotic intima. This is the first demonstration that YY1 is induced by either injury or FGF-2, is differentially expressed in normal and diseased human arteries, and that its overexpression inhibits vascular smooth muscle but not endothelial cell replication.

Animals↗
PubMed2001

Phenotype determination of anti-GM3 positive cells in atherosclerotic lesions of the human aorta. Hypothetical role of ganglioside GM3 in foam cell formation.

Earlier we reported that atherosclerotic plaques contain cells which were specifically and very intensively stained with anti-GM3 antibodies although no GM3 positive cells were detected in the normal non-diseased arterial intima. Because of their lipid inclusions, GM3 positive cells in atherosclerotic lesions seemed to be foam cells but their origin needed clarification. Using an immunohistochemical technique in the present work, we showed that some of these foam cells contained CD68 antigen. However, the most intense accumulation of GM3 occurred in the areas composed of foam cells which did not stain with any cell type-specific antibodies, including antibodies to macrophages (anti-CD68) and smooth muscle cells (anti-smooth muscle alpha-actin), perhaps, because the cell type-specific antigens were lost during the transformation of intimal cells into foam cells. Ultrastructural analysis of the areas where foam cells overexpressed GM3 demonstrated that some foam cells lacked both a basal membrane and myofilaments but contained a large number of secondary lysosomes and phagolysosomes, morphological features which might indicate their macrophage origin. Other foam cells contained a few myofilaments and fragments of basal membrane around their plasmalemmal membrane, suggesting a smooth muscle cell origin. These observations indicate that accumulation of excessive amounts of GM3 occurs in different cell types transforming into foam cells. We suggest that up-regulation of GM3 synthesis in intimal cells might be an essential event in foam cell formation. Shedding of a large number of membrane-bound microvesicles from the cell surface of foam cells was observed in areas of atherosclerotic lesions corresponding to extracellular GM3 accumulation. We speculate that extracellularly localised GM3 might affect the differentiation and modification of intimal cells in atherosclerotic lesions.

Adult↗
PubMed2001

Vascular-associated lymphoid tissue (VALT) involvement in aortic aneurysm.

Vascular-associated lymphoid tissue (VALT) consisting of accumulations of immunocompetent and antigen presenting cells has recently been recognised in the arterial wall. In this study, we investigated the involvement of VALT in immune responses in abdominal aortic aneurysms (AAAs). Tissue samples were collected during operations from 31 patients with atherosclerotic infrarenal abdominal aortic aneurysms ranging in diameters from 5 to 8 cm. The specimens were immediately frozen and examined using single and double immunohistochemical staining. T-cell subpopulations, B-cells, dendritic cells and macrophages were identified using cell type specific antibodies. Cell contacts were examined by electron microscopy. Most inflammatory infiltrates were found in the adventitia. T-cells were the predominant cell type in a majority of inflammatory infiltrates but in seventeen cases, typical lymphoid follicles with B-cells forming germinative centres were also observed. In eight cases, the lymphoid follicles aggregated in lymph node-like structures. Dendritic cells were present within all inflammatory infiltrates and contacted lymphocytes. The present observations show that in aortic aneurysm, VALT is involved in immune responses and its activation mostly occurs in the adventitia. The formation of lymphoid follicles and lymph node-like structures in the adventitia suggests that VALT might locally serve the entire complex of both cellular and humoral immune responses in the aneurysmal wall.

Aged↗
PubMed2001

Immunohistochemical and ultrastructural evidence that dendritic cells infiltrate stenotic aortocoronary saphenous vein bypass grafts.

We earlier speculated that antigen-presenting dendritic cells may be involved in the immune reactions leading to saphenous vein bypass graft failure. The purpose of this study was to confirm whether dendritic cells are present in stenotic human saphenous vein bypass grafts. Segments of stenotic saphenous vein grafts were explanted from 14 patients at re-do bypass operation and ten normal saphenous veins were harvested during femoro-popliteal grafting. Sections of specimens were analysed using cell type specific antibodies to identify dendritic cells (CD1a, S-100), T-lymphocytes (CD3), macrophages (CD68), smooth muscle cells (alpha-SMA) and endothelial cells (FVIII). Dual immunostaining, confocal immunofluorescent laser scanning microscopy and electron microscopy were used. Stenotic grafts showed structural alterations of intimal hyperplasia and varying degrees of atherosclerotic degeneration. No cells expressing CD1a and S-100 were observed in the intima and media of normal saphenous veins. Cells expressing these antigens were present around areas of medial neovascularization and within intimal atherosclerotic lesions in saphenous vein bypass grafts. Electron microscopy demonstrated the presence of cells containing a well-developed tubulovesicular system which is unique to cells from the dendritic cell family. Double immunohistochemistry and confocal immunofluorescent microscopy revealed the co-localization of T-lymphocytes with dendritic cells. Dendritic cells are present in stenotic saphenous vein bypass grafts. Dendritic cells may be responsible for antigen presentation and modulation of immune reactions in accelerated graft atherosclerosis through their interaction with T-lymphocytes.

Adult↗
PubMed2001

Colonisation of prosthetic grafts by immunocompetent cells in a sheep model.

The present study examined the distribution of immunocompetent cells in synthetic vascular grafts in an experimental sheep model. Sixty-two adult Merino sheep underwent synthetic patch closure of a longitudinal arteriotomy in the left common carotid artery. The synthetic patch materials used were gelatin sealed Dacron (n=10), fluoropassivated Dacron (n=10), Fluoropassiv (n=12), polyurethane (n=10), expanded polytetrafluoroethylene (n=10) and carbon-lined expanded polytetrafluoroethylene (n=10). The sheep were sacrificed after four weeks when the prosthetic patches were harvested and fixed in 10% neutral buffered formalin. Transverse sections were taken along the graft and paraffin embedded. Serial sections were stained with cell type specific antibodies to identify T-lymphocytes (CD3(+)), dendritic cells (S-100(+)), endothelial cells (von Willebrand factor(+)) and smooth muscle cells (smooth muscle alpha-actin(+)). All six graft types contained CD3(+) and S-100(+) cells in the neointima, within the synthetic matrix and in the perigraft layer. Three different tissue responses to synthetic materials were observed and the grafts were classified accordingly into three groups: (1) gelatin sealed Dacron, fluoropassivated Dacron and Fluoropassiv; (2) expanded polytetrafluoroethylene and carbon-lined expanded polytetrafluoroethylene; (3) polyurethane. The three synthetic materials in Group 1 showed almost identical reactions with least accumulation of immunocompetent cells within the synthetic material but greater accumulation of immuno-inflammatory infiltrates in the perigraft vascular tissue. In this group, new vessels penetrated into the synthetic material and there was prominent formation of foreign body (giant) cells. Group 2 showed greater accumulation of immunocompetent cells within the synthetic material itself but only sparse immuno-inflammatory infiltrates in the perigraft tissue. Group 3 showed a high degree of inflammatory response within both the synthetic material and the perigraft vascular tissue. These observations demonstrate that immunocompetent cells colonise the synthetic matrix of grafts and accumulate in the perigraft tissue, but inflammatory responses vary in different graft types.

Animals↗
PubMed2001

Expression of apoptosis-related proteins and structural features of cell death in explanted aortocoronary saphenous vein bypass grafts.

This study aimed to investigate the features of cell death occurring in aortocoronary saphenous vein bypass grafts. Human aortocoronary saphenous vein bypass grafts with angiographic luminal stenosis of > 75% were explanted from 14 patients at redo coronary artery bypass grafting. Proteins associated with apoptotic pathways were identified immunohistochemically using antibodies to Bcl-2, Fas, BAX, p53 and CPP32. Cells undergoing DNA fragmentation were identified by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). DNA synthesis was investigated using the antibody to proliferating cell nuclear antigen (PCNA). Ultrastructural features of cell death were examined by electron microscopy. Anti-apoptotic (Bcl-2) and pro-apoptotic (Bax, p53, CPP32 and Fas) proteins were expressed throughout the graft wall, but marked differences in the characteristics of cell death were noted between atherosclerotic and non-atherosclerotic areas of the intima. In atherosclerotic areas, pro-apoptotic proteins were widely expressed, but ultrastructural analysis failed to identify cells showing typical features of apoptosis. In these areas, necrotic cells were frequently observed, with negative correlation of Bcl-2 expression with TUNEL. Pro-apoptotic proteins showed no correlation with TUNEL. In contrast, in non-atherosclerotic areas of vein grafts, the expression of both anti-apoptotic (Bcl-2) and pro-apoptotic proteins (p53, Bax and CPP32) correlated with TUNEL. In atherosclerotic areas, non-atherosclerotic intimal areas, and in the underlying media, the numbers of TUNEL+ cells correlated with PCNA positivity. Ultrastructurally, apoptotic bodies and features of necrosis were observed in non-atherosclerotic areas of grafts. The present observations indicate that in atherosclerotic areas, cell death occurs mainly by necrosis, while in non-atherosclerotic areas, cell death occurs by both necrosis and apoptosis. An imbalance between DNA fragmentation and DNA synthesis may contribute to graft instability and failure.

Aged↗
PubMed2001

CD40 co-stimulatory molecule expression by dendritic cells in primary atherosclerotic lesions in carotid arteries and in stenotic saphenous vein coronary artery grafts.

We have previously identified dendritic cells in the intima of human large arteries and stenotic vein coronary bypass grafts. The mechanisms by which these dendritic cells might regulate immune responses in atherosclerotic lesions and stenotic vein grafts are unknown. The aim of the present study was to investigate whether dendritic cells in carotid plaques and in stenotic aortocoronary vein grafts express an immunoregulatory molecule CD40. Segments of wall from eight carotid arteries and three stenotic aortocoronary saphenous vein grafts were obtained at operation. CD40+ cells were detected in all specimens of both occluded and stenotic grafts and carotid plaques. Although CD40+ cells of various cell types were intermingled in most areas within the plaques and stenotic grafts, there were sites where CD40+ cells were located in small groups. Consecutive sections demonstrated that a small population of CD40+ cells stained positively for S100. These CD40+/S100+ cells were clustered within the intima but were also found in the media and adventitia. This suggests that dendritic cells, which accumulate within vessels affected by atherosclerosis and graft disease, express CD40 co-stimulatory molecule. The expression of CD40 molecule on the dendritic cells may be important in regulating T cell responses within atherosclerotic plaques and stenotic vein grafts.

CD40 Antigens↗
PubMed2001

Expression of vascular endothelial growth factor in aortocoronary saphenous vein bypass grafts.

Neovascularisation is a prominent feature of long-term aortocoronary saphenous vein bypass grafts but mechanisms involved in the formation of neovessels have not been previously studied. Vascular Endothelial Growth Factor (VEGF) is an important angiogenic factor that induces migration and proliferation of endothelial cells, enhances permeability and modulates thrombogenecity. This study investigated the expression of VEGF in aortocoronary saphenous vein bypass grafts. Aortocoronary saphenous vein bypass grafts with angiographic luminal stenosis of >75% were explanted from 14 patients at redo coronary artery bypass grafting. The grafts demonstrated two distinct forms of graft occlusion: four out of the 14 graft occlusions (29%) resulted from severe hyperplastic transformation of the intima complicated by thrombi attached to the degenerating liminal endothelium; the remaining graft occlusions (71%) were due to the development of atherosclerotic lesions associated with mural thrombosis. Hiperplastically altered intimal segments were practically free of neovascularisation while atherosclerotic-like lesions contained neovessels irregularly distributed throughout. Intimal neovessels were located exclusively in microzones enriched with VEGF-expressing cells and, furthermore, neovascular endothelial cells themselves also displayed VEGF immunopositivity. Double-immunostaining revealed that in areas of neovascularisation, the vast majority macrophages (CD68+) expressed VEGF. Some CD68+ foam cells that surrounded branches of neovascularisation were also VEGF-positive. These findings suggest that VEGF expressed by neovascular endothelial cells and by macrophages may act as a local regulator of endothelial cells functions and may induce intimal neovascularisation in aortocoronary saphenous vein bypass grafts affected by atherosclerosis.

Aged↗
PubMed2001

Evidence that dendritic cells infiltrate atherosclerotic lesions in apolipoprotein E-deficient mice.

Earlier we reported that atherosclerotic lesions of apoE-deficient mice contained cells which stained positively with anti-S-100 antibody and that cells exhibiting the ultrastructural features of dendritic cells were present in the aortic lesions. These observations suggested that dendritic cells might be involved in mouse atherosclerosis. By employing DEC-205 and MIDC-8 antibodies specific for dendritic cells, the present study has established that dendritic cells indeed accumulate in atherosclerotic lesions of apoE-deficient mice. Finding dendritic cells infiltrating atherosclerotic lesions in apoE-deficient mice offers the possibility of investigating the migratory routes of dendritic cells and their involvement in T-cell activation.

Animals↗
PubMed2000

Identification of dendritic cells in ePTFE grafts explanted from humans.

Following implantation different cell types interact with synthetic vascular prostheses resulting in a complex immuno-inflammatory response. Dendritic cells are responsible for activating the primary T-lymphocyte immune response in various pathological conditions by their role as antigen-presenters. This study aimed at examining whether dendritic cells accumulate within small diameter expanded polytetrafluoroethylene (ePTFE, Goretex(R)) grafts explanted from humans. Segments of expanded polytetrafluoroethylene were explanted from 11 patients (6 male, 5 female), aged between 60 and 83 years (mean 70.7 years) at secondary or revision bypass operation. The graft implant duration varied from 4 months to 12 years (mean 40.5 months). Dendritic cells were identified immunohistochemically using S-100 antibody, as well as by electron microscopy. Immunohistochemical examination showed that all 11 explanted synthetic grafts contained S-100(+) cells colonising both the synthetic matrix itself, and the adjacent perigraft tissue. Electron microscopic analysis confirmed the presence of cells with a characteristic dendritic cell morphology within the grafts. Dendritic cells which accumulated within synthetic grafts were found to co-localise with T-lymphocytes. Based on these observations, we speculate that dendritic cells may be involved in the immuno-inflammatory responses following the implantation of synthetic vascular prostheses through their interaction with T-lymphocytes.

Aged↗
PubMed2000

Immunophenotypic analysis of the aortic wall in Takayasu's arteritis: involvement of lymphocytes, dendritic cells and granulocytes in immuno-inflammatory reactions.

The present study was undertaken to examine the cellular composition of the aortic wall in Takayasu's arteritis and to investigate the association of different cell types in the immuno-inflammatory reactions of this disease. Specimens of aortic wall affected by Takayasu's arteritis were obtained from 10 patients (five male, five female), aged 32 to 68 years (mean 49.5 years) at elective operation. The mean duration of disease was 6.5 years (range 2 months to 13 years). Specimens were embedded in paraffin and the sections stained with antibodies to CD3 (to identify T cells), CD20 (B cells), S-100 (dendritic cells), CD15 (granulocytes), CD68 (macrophages), alpha-SMA (smooth muscle cells) and von Willebrand factor (endothelial cells). Immunohistochemical examination demonstrated that all specimens showed histological alteration with the replacement of the muscular and elastic layers of the media and adventitia by dense fibrous tissue, and were characterized by varying degrees of inflammatory cell infiltration. In five cases, inflammatory nodules consisting of numerous T cells and B cells were observed in the adventitia. Within the inflammatory nodules, as well as around areas of neovascularization in the deep portion of the intima, lymphocytes were co-localized with dendritic cells. In addition, in the adventitia, the accumulation of a large number of granulocytes was observed. The present study demonstrates that immune inflammation is a typical feature of Takayasu's disease, and that the interactions between dendritic cells and lymphocytes may be important in the control of the immune reactions in this vascular pathology.

Adult↗
PubMed2000

Dendritic cells in aortocoronary saphenous vein bypass grafts.

Dendritic cells are specialised leucocytes responsible for capturing and presenting antigens to T lymphocytes, which in turn mediate immune responses in various pathological conditions. The observations in this study demonstrate that dendritic cells are present in stenotic aortocoronary saphenous vein bypass grafts, which suggest that these cells may be involved in inflammatory actions which may subsequently contribute to graft failure.

Journal Article↗