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J.G. Hollyfield, K.G. Shadrach, K. West, J. Sun, K. Nakata, J.W. Crabb; Comparison Of Bruch’s Membrane/choroid Complex During Aging In Caucasian And African American Eyes: Identification Of Differences That May Underlie The Susceptibility To AMD. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2289.
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Purpose:Age–related macular degeneration (AMD) occurs more frequently in Caucasians than in African Americans. Previous studies indicate that cross–linked, high molecular weight protein complexes accumulate in drusen and Bruch’s membrane of AMD donor tissues. Here, we establish the presence and composition of these protein complexes in non–AMD tissues from these two ethnic groups in relationship to age Methods:10mm of Bruch’s membrane/choroid complex was isolated from macular and periphery locations in donor eyes (7 from Caucasians, ages 46, 51, 66, 71, 76, 80, and 82 years; and 6 from African Americans, ages 59, 66, 71, 78, 83 and 84 years). Tissues were processed for SDS–PAGE, Western blotting and proteomic analyses. Adjacent tissue samples were prepared for immunohistochemisty. Differences in TIMP–3 immunoreactivity were quantitated. Proteins were identified in extracted gel bands by LC MS/MS. Results:TIMP–3 immunoreactivity was greater in Caucasian samples in both tissue sections and in Western blots from all age groups. High molecular weight complexes containing TIMP–3 were present in all Caucasian samples. TIMP–3 in African American tissues did not appear in high mass complexes until the 8th decade. In contrast, complement factors (C3 and usually C9) were present in these tissues in both groups at all ages studied Conclusions:Cross–linked proteins accumulate in Bruch’s membrane/choroid with age and are more pronounced in Caucasian than in African American tissues. The accumulation of this material may in part be responsible for the previously described reduction in hydrolic conductivity of Bruch’s membrane with age. In African American tissues, these accumulations occur later in life than in Caucasians and therefore may be causally related to the reduced frequency of AMD in African Americans.
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