MOLECULAR PATHOLOGY OF CEREBROVASCULAR ATHEROSCLEROSIS

Cerebrovascular disease are the third most common cause of death in Western countries. The most frequent manifestation of disease is a sudden episode of neurological deficit termed stroke which is the result of cerebral haemorrhage or cerebral infaction in the mayority of cases. Stroke secondary to atherosclerosis is most common in people over 50 years old.The incidence of stroke rises dramatically with ages, with the risk doubling with each decade after 35 years old. About 5 % of people over 65 years old have at least one stroke. Atherosclerosis is condition where fatty acid deposits occur in the inner lining of arteries and the forming of atherosclerotic plaque,a mass consisting of fatty deposit, and blood platelets.The plaque may obstruct or my trigger clot,a trombus,at that location causing cerebral trombosis.It is called ischemmic stroke. The basis of the response to injury hypothesis introduced by Russel Ross is that the earliest cellular events that occur during atherosclerosis is a specialized type of chronic inflammatory response to cell injury. What may begin as a protective inflammatory reponse can become excessive and deleterious to the cell of the artery wall. The adhesion of leucocytes on endothelial cells and their trans –endothelial migration into intima are mediated by adhesion molecules on the endothelial cell membrane that mainly belong to two protein families:the selectin and the addhesion molecules.

Testing of Photocatalytic Activity of Self-Cleaning Surfaces

Due to relatively successful application of TiO2 photocatalysis in the field of self-cleaning surfaces, a reliable and appropriate quantitative method for determining the self-cleaning efficiency of the products (photocatalyst films on different supports) should be widely recognized and established. Currently, the two standard methods are based on photobleaching of methylene blue aqueous solution in contact with thin solid catalyst layer, and on photodegradation of a solid fatty deposit (e.g. stearic acid) over catalyst layer followed indirectly by water contact angle (CA) measurements. Another method proposed recently is based on the entrapment of an organic dye in a solid polymer matrix deposited over the photocatalyst layer. Upon illumination, the dye (e.g. resazurin) is reduced by the photogenerated electrons to the form of a different colour or to the bleached form. Recently, a new method for determination of self-cleaning activity of photocatalytic surfaces was developed in our laboratory. It is based on the deposition of a transparent solid layer comprising terephthalic acid over the photocatalytic surface. When such a system is irradiated, among the other degradation products also a hydroxyterephthalic acid is formed due to a reaction between photoexcited TiO2 and terephthalic acid. Hydroxyterephthalic acid is a highly fluorescent molecule and can be easily detected by HPLC-FLD or spectrofluorimeter. Many different samples were tested using this method and using the standard method based on photodegradation of a solid fatty deposit over the catalyst layer. Regarding the sample (substrate) type, the focus was given to the self-cleaning ceramic tiles coated with TiO2-SiO2 thin films that were produced in cooperation with the major manufacturer of floor ceramic tiles in Slovenia, Martex d.o.o.. In case of self-cleaning ceramics and some other sample types, the advantages of the new method over standard methods were highlighted and critically evaluated.