A Rabbit Model of Thrombosis on Atherosclerotic Lesions

Thrombus formation on a disrupted atherosclerotic plaque is a key event that leads to atherothrombosis. Because thrombus is induced by chemical or physical injury of normal arteries in most animal models of thrombosis, the mechanisms of thrombogenesis and thrombus growth in atherosclerotic vessels should be investigated in diseased arteries of appropriate models. Pathological findings of human atherothrombosis suggest that tissue factor, an initiator of the coagulation cascade, significantly affects enhanced platelet aggregation and fibrin formation after plaque disruption. We established a rabbit model of atherothrombosis based on human pathology in which differences in thrombus formation between normal and atherosclerotic arteries, factors contributing to thrombus growth, and mechanisms of plaque erosion can be investigated. Emerging transgenic and stem cell technologies should also provide an invaluable rabbit experimental model in the near future

Pathophysiology of Atherothrombosis — Thrombus Growth, Vascular Thrombogenicity, and Plaque Metabolism

Atherosclerotic plaque disruption does not always result in acute symptomatic events. Therefore, the formation of a large thrombus is a critical step in the development of atherothrombosis. However, little is known about the mechanisms involved in thrombus growth processes after plaque disruption. Studies in vivo have demonstrated that the tissue factor (TF) derived from the vascular wall contributes to the formation of thrombin-dependent platelet–fibrin thrombus on atherosclerotic arteries but not on normal arteries, and that altered blood flow in disrupted atherosclerotic arteries promotes platelet recruitment mediated by von Willebrand factor (VWF) on the thrombus surface and augmented blood coagulation resulting in thrombus growth. The thrombogenic potential of plaques is a fundamental factor in atherothrombosis. We recently found that the arterial glucose uptake reflects vascular thrombogenicity, which might be partly explained by metabolic adaptation and enhanced procoagulant activity in a hypoxic microenvironment. Hypoxic responses might link atherometabolism to vascular thrombogenicity

Do Uric Acid Deposits in Zooxanthellae Function as Eye-Spots?

The symbiosis between zooxanthellae (dinoflagellate genus Symbiodinium) and corals is a fundamental basis of tropical marine ecosystems. However the physiological interactions of the hosts and symbionts are poorly understood. Recently, intracellular crystalline deposits in Symbiodinium were revealed to be uric acid functioning for nutrient storage. This is the first exploration of these enigmatic crystalline materials that had previously been misidentified as oxalic acid, providing new insights into the nutritional strategies of Symbiodinium in oligotrophic tropical waters. However, we believe these deposits also function as eye-spots on the basis of light and electron microscopic observations of motile cells of cultured Symbiodinium. The cells possessed crystalline deposit clusters in rows with each row 100–150 nm thick corresponding to 1/4 the wavelength of light and making them suitable for maximum wave interference and reflection of light. Crystalline clusters in cells observed with a light microscope strongly refracted and polarized light, and reflected or absorbed short wavelength light. The facts that purines, including uric acid, have been identified as the main constituents of light reflectors in many organisms, and that the photoreceptor protein, opsin, was detected in our Symbiodinium strain, support the idea that uric acid deposits in Symbiodinium motile cells may function as a component of an eye-spot

Every Color Chromakey

In this paper, we propose a region extraction method using chromakey with a two-tone checker pattern background. The proposed method solves the problem in conventional chromakey techniques that foreground objects become transparent if they have the same color with the background. The adjacency condition between two-tone regions of the background and the geometrical information of the background grid lines are utilized for extracting foreground objects. Experimental results show the effectiveness of the proposed method. Same color (a) Conventional chromakey. Same color as C 1 or C