Featuring three papers this month, from Washington Univ (St Louis),
the Scripps Clinic and Research Foundation (La Jolla), and the Univ
of Nebraska (Omaha).  Abstracts are abstracted from the authors...

1. Abnormal expression of plasminogen activators in aortic
aneurysmal and occlusive disease.  Reilly JM, Sicard GA, Lucore CL. 
J Vasc Surg 1994; 19: 865-72.

Purpose:  Aortic aneurysms are characterized by destruction of ECM
of the media, whereas occlusive disease involves excess matrix
accumulation within the subendothelium.  Plasmin degrades ECM
directly and indirectly...  Several methods were used to determine
expression of tPA and uPA in AAA (#=12), AOD (#=8) and normal (#=6)
aortas.

Results (in brief):  tPA was increased more than three-fold in AAA
vs AOD aortic tissue.  

Comment (by mdt):  This work makes an interesting fit with results
reported from our laboratory this year (Jean-Claude J, et al,
Surgery 1994; 116:472-8), where we reported that Western blots for
plasmin revealed an approximately 7-fold increase in AAA versus 
controls.  


2.  Computed tomography scanning findings associated with rapid
expansion of abdominal aortic aneurysms.  Wolf YG, Thomas WS,
Brennan FJ, Goff WG, Sise MJ, Bernstein EF.  J Vasc Surg 1994; 20:
529-38.

Purpose:  To define features on CT scanning highly predictive of
subsequent rapid aneurysm expansion.

Methods: Review of CT scans of 80 patients who underwent serial
examinations.

Results: The CT scanning variables that correlated most
significantly with rate of expansion were the volume of the
aneurysm occupied by thrombus and the arc of the aneurysm wall
covered by thrombus.

Comment (by mdt):  Another interesting finding in connection with
the papers by Reilly and Jean-Claude mentioned above.  The
immunohistochemistry of the Jean-Claude paper was consistent with
the hypothesis that some of the plasmin (which is an MMP activator)
was leaching into the AAA wall from the clot.  If this turns out to
be consistent in the long term, there will be a molecular
explanation for the clinical findings reported by Wolf et al.


3. Abdominal aortic aneurysms are associated with altered matrix
proteins of the nonaneurysmal aortic segments.  Baxter BT, Davis
VA, Minion DJ, Want YP, Lynch TG, McManus BM.  J Vasc Surg 1994;
19: 797-803.


Purpose:  AAA's are associated with diffuse arteriomegaly and
peripheral aneurysms, suggesting a generalized process.  The
question is whether biochemical abnormalities occur in the aorta
remote from the actual site of the aneurysm.

Findings:  An increase in collagen and a putative dilutional
decrease in elastin were found in thoracic, supraceliac, and
suprarenal aorta remote from the AAA in 8 patients versus 9 AOD 
controls and 9 normal aortas. 

Comment (by mdt):  Baxter and his colleagues continue with their
interesting work.  My laboratory (Gandhi RH et al, Surgery 1994;
115: 617-20) has confirmed their previously reported findings
related to cross-link content as a ratio to valine in purified
elastin.  Clinical evidence for generalized arteriomegaly in AAA
patients (going back to Tilson & Dang, Arch Surg 1981; 116:1031-2,
if not before) strongly suggests that there must be a systemic
process affecting arteries in patients with AAA.  When this
systemic process is eventually uncovered by continuing
investigation, we will be much closer to an understanding of the
basic genetic susceptibility for AAA disease.