The measurement of collagen in angioplasty samples

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University of New Brunswick
Angioplasty is a method that is used to remove blockages in arteries. It is performed by inserting a balloon to the location of the plaque and inflating it at a high pressure. There are two reactions which have been observed; one where the edges of the plaque lift off the artery wall and the other where the plaque is compressed (Kleiman et al., 1990; Marsico et al., 1995; Hjemdahl-Monsen et al, 1990). This is thought to be because of the concentration of collagen, a protein with a high tensile strength, in the plaque (Roach, personal communication). It has been observed that there is a greater reduction in stenosis or blockage and so an increase in blood flow in arteries where the edges of the plaque are torn away post-angioplasty (Block et al., 1981). In order to determine the conditions under which either reaction will occur, a method was developed which allows for the concentration and distribution of collagen to be measured in formaldehyde fixed tissue. The absorbance of the tissue was found to relate to percent collagen through: %Coll= 70.9Abs - 5.7. The concentration and distribution of collagen in formaldehyde fixed tissue can now be measured down to the pixel level. This allowed for the concentration of collagen to be measured at various locations in the arteries that had undergone angioplasty and measure the change in collagen through the atherosclerotic lesions.