In @entity1614 , mutations of the fibrillin gene ( @entity16865 ) lead to @entity439 of the thoracic aorta, making the aortic wall more susceptible to dissection, but the precise sequence of events underlying @entity439 formation is unknown. We used a rodent model of @entity1614 , the mgR/mgR @entity19 (with mgR: hypomorphic @entity16865 mutation), which underexpresses @entity16865 , to distinguish between a defect in the early formation of elastic fibers and the later disruption of elastic fibers. The content of @entity13403 plus @entity27378 was used as an index of early elastogenesis; disruption of elastic fibers was analyzed by histomorphometry. Because disruption of the medial elastic fibers may produce aortic stiffening, so amplifying the aneurysmal process, we measured thoracoabdominal pulse wave velocity as an indicator of aortic wall stiffness. Both mgR/mgR and wild-type (C57BL/6J-129SV) strains were normotensive, and wall stress was not significantly modified because the increase in internal diameter (0.80+/-0.06 vs 0.63+/-0.03 mm in wild type, P<0.05) was accompanied by increased medial cross-sectional area. The aortic wall stiffened (4-fold increase in the elastic modulus-to-wall stress ratio). @entity13403 content was not modified (mgR/mgR 432+/-31 vs wild type 492+/-42 microg/mg wet weight, P>0.05). Elastic fibers showed severe @entity1949 : the percentage of the media occupied by elastic fibers was 18+/-3% in mgR/mgR @entity19 vs 30+/-1% in wild-type @entity19 , with the number of elastic segments being 1.9+/-0.2 vs 1.4+/-0.1x10(-6)/mm(2) in the wild type (both P<0.05). In conclusion, underexpression of @entity16865 in @entity19 leads to severe @entity1949 but no change in cross-linking, together with @entity384 . This result suggests that @entity1949 of the medial elastic network and not a defect in early elastogenesis is 1 of the determinants of @entity384 in @entity1614 .

Aortic wall mechanics and composition in a transgenic @entity19 model of XXXX .

@entity1949 :: ('MESH:D012892', 'Disease') :: ['fragmentation', 'elastic network fragmentation'] @entity19 :: ('10090', 'Species') :: ['mice', 'mouse'] @entity13403 :: ('MESH:D003895', 'Chemical') :: ['Desmosine', 'desmosine'] @entity1614 :: ('MESH:D008382', 'Disease') :: ['Marfan syndrome'] @entity27378 :: ('MESH:D007524', 'Chemical') :: ['isodesmosine'] @entity384 :: ('MESH:D002311', 'Disease') :: ['aortic dilatation'] @entity439 :: ('MESH:D000783', 'Disease') :: ['aneurysm'] @entity16865 :: ('14118(Tax:10090)', 'Gene') :: ['FBN1']
@entity1614 :: (MESH:D008382,Disease) :: ['Marfan syndrome']
