Az érfal trombogenitása és annak szabályozása = Vessel wall thrombogenicity and its regulation

Fiziológiás hemosztázis ill. artériás trombózis keletkezésekor a trombociták a gyorsan áramló vérből von Willebrand faktoron keresztül tapadnak ki az érfalban lévő kollagénhez. Az érfal mátrix komponenseit vizsgálva megállapítottuk, hogy a media rétegből izolálható proteoglikánok, a perlecan és a biglycan/decorin gátolják a von Willebrand faktor kötődését a kollagénhez, és így a jelenlétükben in vitro kialakuló kollagén struktúra antitrombogén. Az adventitia proteoglikánok a kollagén trombogenitását nem befolyásolják. A media proteoglikánok antitrombotikus tulajdonsága perlecan esetében a fehérje komponenshez, míg biglycan, decorin esetében az adventitia rétegétől eltérő kondroitin szulfát/dermatán szulfát oldalláncokhoz köthető. Kimutattuk, hogy plazmin, trombin, és neutrofil granulocita metalloproteinázok fokozzák az érfal media rétegében lévő kollagén trombogenitását, ami gyulladásban ill. hemosztázisban fokozott trombózishajlamhoz vezethet. Az artériás trombusban a trombociták egymáshoz fibrinogénen, von Willebrand faktoron keresztül kapcsolódnak. Megállapítottuk, hogy fiziológiás koncentráció viszonyok esetén a von Willebrand faktor védi a fibrinogént a plazmin hasítása ellen, és bár ő is plazmin szubsztrát, a hatás nem a szubsztrátok kompetícióján alapul. Artériás trombusban a fibrinogén kb. 50 %-a fibrinné alakul, ennek degradációját a von Willebrand faktor nem befolyásolja. | In the course of hemostasis or arterial thrombosis platelets are captured from rapidly flowing blood by von Willebrand factor immobilized on vascular collagens. Collagen structures in the media layer of vessel wall, however, do not support platelet adhesion. We have found that perlecan and biglycan/decorin isolated from the media layer of the arterial wall, but none of the adventitia proteoglycans, inhibit von Willebrand factor binding to collagen and platelet adhesion to reconstituted collagen surfaces. The antithrombotic effect of perlecan is due to its core protein component, whereas the inhibitory effects of media biglycan and decorin are attributable to their chondroitin sulphate/dermatan sulphate chains, which are different from those in adventitia biglycan and decorin. We have shown that the antithrombotic properties of the media collagen structures, in situ, can be disrupted by plasmin, thrombin and matrix metalloproteases of neutrophil granulocytes, which suggests that vascular thrombogenicity may increase at sites of inflammation and when the hemostatic system is activated. In platelet-rich thrombi fibrinogen and von Willebrand factor serve as molecular bridges between platelets. Our data indicate that von Willebrand factor protects fibrinogen, but not fibrin from plasmin degradation. Although von Willebrand factor is also a substrate for plasmin, its protective effect is not due to substrate competition

Lytic and mechanical stability of clots composed of fibrin and blood vessel wall components.

Background Proteases expressed in atherosclerotic plaque lesions generate collagen fragments, release glycosaminoglycans (chondroitin sulfate [CS] and dermatan sulfate [DS]) and expose extracellular matrix (ECM) proteins (e.g. decorin) at sites of fibrin formation. Objective Here we address the effect of these vessel wall components on the lysis of fibrin by the tissue plasminogen activator (tPA)/plasminogen system and on the mechanical stability of clots. Methods and results MMP-8-digested collagen fragments, isolated CS, DS, glycosylated decorin and its core protein were used to prepare mixed matrices with fibrin (additives present at a 50-fold lower mass concentration than fibrinogen). Scanning electron microscopy (SEM) showed that the presence of ECM components resulted in a coarse fibrin structure, most pronounced for glycosylated decorin causing an increase in the median fiber diameter from 85 to 187 nm. Rheological measurements indicated that these structural alterations were coupled to decreased shear resistance (1.8-fold lower shear stress needed for gel/fluid transition of the clots containing glycosylated decorin) and rigidity (reduction of the storage modulus from 54.3 to 33.2 Pa). The lytic susceptibility of the modified fibrin structures was increased. The time to 50% lysis by plasmin was reduced approximately 2-fold for all investigated ECM components (apart from the core protein of decorin which produced a moderate reduction of the lysis time by 25%), whereas fibrin-dependent plasminogen activation by tPA was inhibited by up to 30%. Conclusion ECM components compromise the chemical and mechanical stability of fibrin as a result of changes in its ultrastructure

Coloring the Past: Neural Historical Buildings Reconstruction from Archival Photography

Historical buildings are a treasure and milestone of human cultural heritage. Reconstructing the 3D models of these building hold significant value. The rapid development of neural rendering methods makes it possible to recover the 3D shape only based on archival photographs. However, this task presents considerable challenges due to the limitations of such datasets. Historical photographs are often limited in number and the scenes in these photos might have altered over time. The radiometric quality of these images is also often sub-optimal. To address these challenges, we introduce an approach to reconstruct the geometry of historical buildings, employing volumetric rendering techniques. We leverage dense point clouds as a geometric prior and introduce a color appearance embedding loss to recover the color of the building given limited available color images. We aim for our work to spark increased interest and focus on preserving historical buildings. Thus, we also introduce a new historical dataset of the Hungarian National Theater, providing a new benchmark for the reconstruction method

Az érfal trombogenitása és hatása a trombolizisre = Thrombogenicity of the vascular wall and its impact on thrombolysis

A projekt keretében az érfal – vérsejt interakciók a trombus keletkezésében betöltött szerepét és az így alakuló véralvadék litikus érzékenységét vizsgáltuk. Fő megállapításaink: 1. Leukocita eredetű proteázok (elasztáz, matrix metalloproteáz 8 és 9) úgy módosítják az érfal szerkezetét, hogy a vérlemezkék von Willebrand faktor (VWF)-függő adhéziója fokozódik. 2. A VWF jelenléte kivédi a fibrinogén plazminnal történő proteolízisét, így hozzájárul a vérlemezkék közötti fibrinogén hidak fenntartásához. 3. Sebészileg eltávolított trombusok hisztológiai feldolgozása igazolja a leukociták in vivo szerepét a trombusok feloldásában valamint a sejt-eredetű foszfolipidek és szabad zsírsavak trombuson belüli jelenlétét. 4. A zsírsavak növelik a szöveti plazminogén aktivátor (tPA) fibrin-specificitását azáltal, hogy fokozzák a plazminogén aktivációt fibrin felszínen, de gátolják azt homogén oldatban. 5. A zsírsavak gátolják a keletkező plazmint is kevert-típusú inhibitorként, míg a fibrin részben kivédi ezt a gátlóhatást. 6. Vérplazma eredetű immunoglobulin G módosítja a lipidek fibrinolízisre gyakorolt hatásait, méghozzá eltérő módon egészségeseknél és egyes kóros állapotokban. 7. Modell rendszerben az intermolekuláris béta-lemezek fokozzák a tPA-függő plazminogén aktivációt és emellett ilyen szerkezetek átmeneti megjelenése kimutatható a fibrinháló oldása során. Eredményeink alapul szolgálhatnak a trombusszerkezethez igazított trombolitikus eszközök tervezéséhez és fejlesztéséhez. | The research targeted the role of the interactions of the blood vessel wall and blood cells in the formation of thrombi, as well as the lytic susceptibility of the formed thrombi. Major results: 1. Leukocyte-derived proteases modify the structure of the arterial wall, so that the von Willebrand factor (VWF) dependent adhesion of platelets increases. 2. The presence of VWF protects fibrinogen against digestion with plasmin and thus contributes to the stability of the fibrinogen as adhesive glue between platelets. 3. Histological evidence from thrombi removed with surgery supports the in vivo role of leukocytes in the dissolution of thrombi as well as the presence of phospholipids and free fatty acids (FFA) in thrombi. 4. FFA increase the fibrin specificity of tissue plasminogen activator (tPA) through stimulation of plasminogen activation on fibrin surface and inhibition of tPA in solution. 5. FFA inhibit the generated plasmin in a mixed-type inhibitor pattern and fibrin protects plasmin against this inhibition. 6. Blood-derived immunoglobulin G modifies the lipid effects on fibrinolysis in a manner, which differs in healthy subjects and antiphospholipid syndrome patients. 7. In a model system intermolecular beta-sheets stimulate the tPA-dependent plasminogen activation and the presence of such structures can be shown transiently in the course of fibrin dissolution. Our results can be implemented in the design of thrombolytic tools tailored to specific thrombus structures

THE APPLICATION OF NOVEL ORGANIC DEEMULSIFIERS FOR THE SEPARATION OF OIL-IN-WATER EMULSIONS

The paper summarizes the results of tests of separation of oil-in-water emulsions with the application of novel organic deemulsifiers. Fresh and used emulsions of different concentrations were tested. The manipulated variables were: the concentration of oil in the emulsion; the concentration and amount of deemulsifier solution; the temperature. The results of these tests are presented graphically

Trombolízis: a trombus celluláris és molekuláris komponenseinek hatása a fibrinolízisre = Thrombolysis: modulation of fibrinolysis by cellular and molecular components of thrombi

Megvizsgáltuk, hogy egy trombusban lévő komponensek hogyan befolyásolják a fibrin szerkezetét, annak feloldását illetve a fibrinolízis iniciálásában szerepet játszó enzimeket. A vörösvértestek különböző eloszlásban találhatók és litikus rezisztenciát okozhatnak. Módosíthatják a fibrin strukturát és gátolják a plazminogén aktivációt. A vörösvértestek különböző eloszlása magyarázhatja a betegek eltérő reakcióit a fibrinolítikus terápia során. Más kísérletek azt jelzik, hogy a fibrin feloldását hátráltathatja a mechanikai stress azáltal, hogy a fibrin feszülése gátlólak hat a plazminogén aktivációra. Ami a neutrofil granulocitákat illeti azt találtuk, hogy az arteriás human trombus feloldásában a leukocita elasztáz jelentős szerepet játszhat és az függ a vérlemezkétől is, mert azok hasonlóan a plazmin függő lízishez, stabilizálhatják a trombust a sejt-függő fibrinolízisben is. A vérlemezke adhéziója az érfal mediájához egy nagyságrenddel nagyobb lesz, ha az ér falát neutrofil elasztázzal vagy matrix metalloproteinázzal kezeljük. Az érfalban történő morfológiai változásokat atomerő mikroszkóppal és scanning elektron mikroszkóppal mutattuk ki. A vonWillebrand faktorral kimutattuk, hogy bár a plazminnak lehet gyenge szubsztrátja (a fibrinogénhez képest) mégis megvédi a fibrinogént a plazmin emésztésétől, a fibrinogén alvadóképes marad és adhezív képességét is megtartja a vérlemezke gazdag trombusban . | We examined components the present in a thrombus how influence the fibrinolysis? We found that red blood cells are distributed is different ways, in a thrombus and may cause lytic resistance. The various distribution of red blood cells may explain the different reactions of patients during fibrinolytic therapy. Other experiment indicate that the mechanical stress hinders fibrin dissolution because fibrin stretch inhibits plasminogen activation. For this publication already appeared commentary reference We further examined these possibilities. We found that in the solubilization of arterial human thrombus the leukocyte elastase may play a significant role and this depends on platelets too because they stabilize the thrombus . Adhesion of platelet to the media of vessel wall increases by an order of magnitude if the vessel wall is treated by neutrophyl elastase or matrix metalloproteinase. The morphological change in the vessel wall was followed by atomic force microscopy and scanning electron microscopy. We showed about von Willebrand factor, that it may be a week substrate of plasmin (compared with fibrinogen), nevertheless it protects fibrinogen from digestion by plasmin, the clotting and the adhesive capacity of fibrinogen remains in the platelet rich thrombus . We also studied that components released by proteases from arterial plaque how influence fibrinolysis.

A trombolízis endogén modulációja = Endogenous modulations of thrombolysis

Az eredmények két feltételezés köré csoportosulnak. Az egyik, hogy a fibrinolítikus reakciók kompartmentekben játszódnak le, szilárd és folyékony fázis határfelületén, ahol a reakciósebességek nagy mértékben megváltoznak. Ilyen kompartmentnek tekinthető maga a trombus is. A másik hipotézis, hogy egy trombusban a fibrinen és vérlemezkén kívül egyéb molekuláris és celluláris komponensek is találhatók, amelyek megváltoztathatják a fibrin szerkezetét és fibrinolítikus reakciók sebességét. Az eredményeink azt jelzik, hogy a miozinen kívül (amely vérlemezkéből származhat) a vérlemezke foszfolipidek és az ezekből felszabaduló zsírsavak is befolyásolhatják a fibrinolízist. A foszfolipidek általában gátolják a plazminogén aktivációját és a plazmin aktivitását. Ezen kívül a trombusban diffúziós barriert képeznek az aktivátorokkal szemben. A zsírsavak is hasonlóan viselkednek, kivéve azt, hogy fibrin felszínen a plazminogén aktivációját fokozzák (fibrin specifikus zsírsav hatás). A trombusban immunglobulinok (IgG) is találhatók, amelyek szintén gátolják a fibrinolízist. Ez a gátló hatás, antifoszfolipid szindrómás betegből izolált IgG jelenlétében sokkal kifejezettebb. Kimutattuk, hogy bizonyos denaturált fehérjék (hasonlóan a fibrinhez) tPA kofaktorként viselkednek, amiért az aggregátum mérete (10 nm rádiusz felettinek kell, hogy legyen) és a béte-redőzet mennyisége a felelős. | The results are assembled around two groups. One is that the fibrinolytic reactions occur in compartments, on the surface of solid and fluid phase, where the reaction rates are extremely changed. Such a compartment is a thrombus itself. The other hypothesis is that in a thrombus besides fibrin and platelet there are additional molecular and cellular components which may alter the structure of fibrin and the rate of fibrinolytic reactions. Our results indicate that besides myosin (originated from platelets), platelet phospholipids and fatty acids released from them may influence fibrinolysis. The phospholipids, usually inhibit the activation of plasminogen and the activity of plasmin. In addition, they form diffusion barrier against the plasminogen activators. Fatty acids act similarly, except that on the surface of fibrin they accelerate plasminogen activation. Immunoglobulins (IgG) also can be found in a thrombus and they inhibit fibrinolysis, this inhibition is more expressed when IgG is isolated from patients with antiphospholipid-syndrome. We proved that certain denatured proteins (similarly to fibrin) act as cofactor for tPA, and for this nature the size of aggregatum (>10nm) and the amount of beta-sheet are responsible

Neutralization of the anti-coagulant effects of heparin by histones in blood plasma and purified systems

SummaryNeutrophil extracellular traps (NETs) composed primarily of DNA and histones are a link between infection, inflammation and coagulation. NETs promote coagulation and approaches to destabilise NETs have been explored to reduce thrombosis and treat sepsis. Heparinoids bind histones and we report quantitative studies in plasma and purified systems to better understand physiological consequences. Unfractionated heparin (UFH) was investigated by activated partial thromboplastin time (APTT) and alongside low-molecular-weight heparins (LMWH) in purified systems with thrombin or factor Xa (FXa) and antithrombin (AT) to measure the sensitivity of UFH or LMWH to histones. A method was developed to assess the effectiveness of DNA and non-anticoagulant heparinoids as anti-histones. Histones effectively neutralised UFH, the IC50 value for neutralisation of 0.2 IU/ml UFH was 1.8 μg/ml histones in APTT and 4.6 μg/ml against 0.6 IU/ml UFH in a purified system. Histones also inhibited the activities of LMWHs with thrombin (IC50 6.1 and 11.0 μg/ml histones, for different LMWHs) or FXa (IC50 7.8 and 7.0 μg/ml histones). Direct interactions of UFH and LMWH with DNA and histones were explored by surface plasmon resonance, while rheology studies showed complex effects of histones, UFH and LMWH on clot resilience. A conclusion from these studies is that anticoagulation by UFH and LMWH will be compromised by high affinity binding to circulating histones even in the presence of DNA. A complete understanding of the effects of histones, DNA and heparins on the haemostatic system must include an appreciation of direct effects on fibrin and clot structure.</jats:p

Mechanical Stability and Fibrinolytic Resistance of Clots Containing Fibrin, DNA, and Histones

Neutrophil extracellular traps are networks of DNA and associated proteins produced by nucleosome release from activated neutrophils in response to infection stimuli and have recently been identified as key mediators between innate immunity, inflammation, and hemostasis. The interaction of DNA and histones with a number of hemostatic factors has been shown to promote clotting and is associated with increased thrombosis, but little is known about the effects of DNA and histones on the regulation of fibrin stability and fibrinolysis. Here we demonstrate that the addition of histone-DNA complexes to fibrin results in thicker fibers (increase in median diameter from 84 to 123 nm according to scanning electron microscopy data) accompanied by improved stability and rigidity (the critical shear stress causing loss of fibrin viscosity increases from 150 to 376 Pa whereas the storage modulus of the gel increases from 62 to 82 pascals according to oscillation rheometric data). The effects of DNA and histones alone are subtle and suggest that histones affect clot structure whereas DNA changes the way clots are lysed. The combination of histones + DNA significantly prolongs clot lysis. Isothermal titration and confocal microscopy studies suggest that histones and DNA bind large fibrin degradation products with 191 and 136 nm dissociation constants, respectively, interactions that inhibit clot lysis. Heparin, which is known to interfere with the formation of neutrophil extracellular traps, appears to prolong lysis time at a concentration favoring ternary histone-DNA-heparin complex formation, and DNase effectively promotes clot lysis in combination with tissue plasminogen activator