Aortic aneurysm in Marfan's syndrome: changes in the ultrastructure and composition of collagen.
AUTOR(ES)
Scheck, M
RESUMO
Aneurysmal aortic tissue and the mitral valve of a patient with Marfan's syndrome were examined. Biochemical analysis of the tissue showed a qualitative and quantitative defect in alpha 2 chain production of Type I collagen. On polyacrylamide gel electrophoresis of the aortic extract, two separate bands in the alpha 2 region and an increase of the alpha 1 to alpha 2 ratio were found. Examination by electron microscopy revealed elastic fibre degeneration, helical collagen fibres, and metabolically active modified smooth muscle cells. The formation of helical collagen fibres is attributed to a defect in the development of chains and cross-links of collagen precursors produced by the hypertrophic smooth muscle cells. Elastic fibre disintegration is believed to be due to a lack of support by Type I collagen fibres, which have decreased tensile strength. A scheme for the pathogenesis of aortic aneurysm and other connective tissue abnormalities in Marfan's syndrome is proposed as follows. Type I collagen fibres have decreased tensile strength because of a defect in the alpha 2 chain biosynthesis and decreased cross-linking. Over many years the wall of the ascending aorta is subjected to cyclic stresses and it dilates. Elastic fibres disintegrate. The attempt at repair by metabolically activated modified smooth muscle cells is abortive, and rupture is likely to occur.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1233030Documentos Relacionados
- Surgical Treatment of Mitral-Aortic Incompetence and Aneurysm of the Ascending Aorta in a Child with Marfan's Syndrome: Case Report
- Marfan syndrome: abnormal alpha 2 chain in type I collagen.
- Giant intracranial aneurysm associated with Marfan's syndrome: a case report.
- Surgical Treatment of Mitral Aortic Incompetence and Aneurysm of the Ascending Aorta in a Child with Marfan's Syndrome: A Case Report
- Aortic root complications in Marfan's syndrome: identification of a lower risk group.