Patricia E. Thorpe

Functional and morphological assessment of rat aorta stored in University of Wisconsin and Eurocollins solutions

University of Wisconsin (UW) and Eurocollins (EC) solutions are widely used for preservation of organs before transplantation. However, effect of storage solutions on vascular interface for transplant success is not known. In this study, we have used rat aorta as a model and assessed the effects of cold storage in UW and EC solutions on smooth muscle and endothelial function and the morphology. Smooth muscle and endothelial functions of the rat aorta were assessed using in vitro isometric tension measurement. Morphologic studies were done with scanning and transmission electron microscopy. No significant difference in contractile response to either norepinephrine (NE) or potassium chloride was observed between control aorta and aorta stored in UW solution for 1 hr or 24 hr. In contrast, sensitivity, but not the reactivity to NE and KCl, was increased in aorta stored in EC solution for 1 hr. If the tissues were stored in EC solution for 24 hr, both sensitivity and reactivity to NE and KCl were significantly reduced. Relaxatory response to acetylcholine, in endothelium-intact vessels were reduced in aortas stored in EC solution, but not in UW solution. The magnitude of relaxations observed in tissues stored in the EC solution for 24 hr was less than in tissues stored for 1 hr. Sodium nitroprusside elicited similar relaxatory response in en-dothelium-denuded control tissue and in tissues stored in UW and EC solution. Electron microscopy data revealed marked swelling of the cell, loss of mitochondria and other intracellular organelles, and striking calcium deposits after preservation of the vessels in EC for 1 or 24 hr. In aorta stored in UW solution for 24 hr, endothelial and smooth muscle cells were intact, with moderate-size vacuoles in the cytoplasm. These results suggest that the UW solution is more suitable than EC solution for short-term preoperative storage of blood vessels.

A noninjury, diet-induced swine model of atherosclerosis for cardiovascular-interventional research

To investigate whether atherosclerotic vascular disease in the microswine model can be induced by atherogenic diet alone and does not require balloon injury or endothelial denudation as widely stated in the literature, 28 female Yucatan microswine were fed a high-fat, high-cholesterol diet, including 2% sodium cholate, for an average of 310 ± 13 days. Four control swine were placed on a regular diet for an average of 287.2 ± 7.8 days. Selective coronary arteriography and morphologic and histologic studies were performed at the end of this period. Coronary arteries were fixed in vivo by pressure perfusion of formalin. Angiograms and sequential histologic sections were reviewed by a double-blind team. The angiography did not show apparent disease in all vessels but generally revealed mild irregularity. Quantitatively, there was a 30.5 ± 3.5% stenosis (mean ± standard error, P < 0.05 vs. control) in left anterior descending (LAD), 40.7 ± 4.5% of stenosis in right coronary artery (RCA) (P < 0.01 vs. control), and 24.8 ± 3.7% of stenosis in left circumflex artery (LCX). The lesions were eccentric in 95% of LCA, 95.8% of RCA, and 75% of LCX, and the remainder were concentric lesions. Typical lesions were characterized by significant intimal proliferation, cholesterol clefts, necrotic cores, heavy extracellular fat deposition, and calcification. Control animals had only occasional, minimal intimal lipid deposition in coronary arteries. These findings suggest that the Yucatan microswine is an ideal coronary atherosclerosis animal model for vascular research. Lesions can be induced by atherogenic diet alone. Cholesterol uptake is increased by adding sodium cholate to the feed. Moreover, balloon injury of the intima or media is not required to induce significant atherosclerotic lesions in coronary arteries.

Effect of Iodinated Contrast Media on Neutrophil Adhesion to Cultured Endothelial Cells

PURPOSE To investigate the influence of contrast media (CM) on endothelial cells (ECs) with respect to cytotoxicity and to neutrophil adhesion. MATERIALS AND METHODS Human umbilical vein ECs were incubated with chromium-51-labeled human neutrophils in the presence of CM (diatrizoate, ioxaglate, iopamidol, and iodixanol) in three concentrations: 2, 20, and 50 mg I/mL. CM was compared with glucose solutions prepared from plain, buffered glucose solutions, iso-osmolar to the corresponding CM solution. Neutrophil adhesion to the EC monolayer, EC morphology, and cytotoxicity were evaluated. RESULTS The effect of CM on neutrophil adhesion was dependent on dose, with increased adhesion at low CM concentrations (2 and 20 mg I/mL) and decreased adhesion at high CM concentration (50 mg I/mL). The response was observed only if ECs and neutrophils were exposed to CM simultaneously in a shared environment. Glucose solutions with the same osmolarity did not show similar effect. Both diatrizoate and ioxaglate had a greater cytotoxic effect on ECs and neutrophils than did iodixanol and iopamidol. CONCLUSION The altered neutrophil adhesion to ECs may be due to CM-induced cytotoxicity or CM-induced EC activation because the glucose solutions did not cause a similar change at equal osmolality. The lack of cell death, combined with altered neutrophil adhesion implies modulation of cell adhesion molecules by CM. The results could be pertinent to the pathogenesis of peripheral vascular lesions and the endothelial response in immunosuppressed or septic patients receiving CM during imaging studies.

Endothelin-1 levels in ischaemia, reperfusion, and haemorrhagic shock in the canine infrarenal aortic Revascularisation model

Endothelin-1 (ET-1) is a potent vasoconstrictive polypeptide produced from vascular endothelial cells. The effects of ischaemia, reperfusion, and exsanguination on plasma ET-1 levels were studied and compared in the mongrel dog after infrarenal aortic cross clamping. Ischaemia produced a trend toward increased ET-1 serum levels (p < 0.07 with Bonferroni correction) that did not reach significance. Plasma ET-1 levels were significantly increased during reperfusion and even further elevations were found following exsanguination. We found a 2-3 fold increase in ET-1 levels following reperfusion (Initial 3.19 +/- 0.27 pg/ml vs. Reperfusion maximum 6.32 +/- 0.72 pg/ml, Bonferroni p < 0.01). Haemorrhagic shock was associated with a 3-4 fold increase in ET-1 levels (Initial 3.19 +/- 0.27 pg/ml vs. Exsanguination maximum 8.37 +/- 0.97 pg/ml Bonferroni p < 0.001). These data reveal that ET-1 is released during reperfusion and exsanguination and may mediate remote vascular events associated with infrarenal aortic cross clamping and acute blood loss.

Posttraumatic innominate artery aneurysm with occlusion of the common carotid artery at its origin by an intimal flap

Blunt trauma involving the innominate and carotid arteries is a rare occurrence that can be lethal or have serious neurologic sequelae. To our knowledge this is the first reported case in the international literature describing the association of posttraumatic innominate, artery aneurysm with total occlusion and thrombosis of the common carotid artery at its origin by an intimal flap. The diagnostic problems created by this unusual injury are discussed. In this case the patency of the distal portion of the common and internal carotid arteries was demonstrated by magnetic resonance angiography (MRA), whereas color duplex and digital arteriographic studies were unsuccessful. This demonstration was crucial to patient management. Since no studies are available comparing color duplex imaging, conventional arteriography, and MRA in the evaluation of blunt carotid trauma, this case study is presented to demonstrate the utility of MRA in emergency situations. In addition, we analyze the possible pathogenesis and discuss the surgical treatment.

Dacron Graft Replacement with Bilateral Renal Vein Reimplantation for Inferior Vena Cava Leiomyosarcoma A Case Report

The surgical treatment of inferior vena cava (IVC) leiomyosarcomas is not well elucidated. The preferred procedures include either IVC wedge resection or ligation. The authors present a case in which Dacron graft replacement of the midportion of the IVC with bilateral renal vein implantation was performed for an IVC leiomyosarcoma. This is, to their knowledge, the first report in the literature describing a technically successful IVC Dacron graft replacement for a primary tumor. The report is presented to demonstrate the technical feasibility of this procedure and the good long-term graft patency rate. At present complete surgical excision of the tumor seems to offer the only chance for a long-term cure.

The role of thrombolytic therapy in pulmonary embolism

The presence of thrombus in the deep venous system is not normal. In some cases, it is well tolerated because it is not occlusive and because the body has an intrinsic ability to dissolve thrombus to an extent. Where a large amount of thrombus blocks a vessel, symptoms and signs of the abnormal condition can be immediate and alarming. Unfortunately, the process of thrombus accumulation in the deep veins is often silent and unexpected. More unfortunate is the fact that embolization of thrombus, from extremity veins to the pulmonary arteries, is unpredictable and seemingly random. It is known that anticoagulation tends to halt thrombus propagation. However, to most individuals, it seems intuitively better if thrombus is not present at all. When it is, early removal with thrombolytic agents, or thrombectomy devices might be an advantage if thrombus is not present, it cannot embolize, or damage valves. If the process required to remove the thrombus was inexpensive and risk-free, there would be little discussion or hesitation. However, the risk/benefit ratio of thrombus removal, whether in peripheral or central veins and arteries, is a subject of great debate. Careful studies and complete long-term follow-up data are necessary for the thrombolytic option to evolve, to develop safe and effective use of this powerful therapeutic tool.

Neuropeptide Y levels during ischemia and reperfusion in the canine infrarenal aortic revascularization model

Neuropeptide Y (NPY) is a potent vasoconstrictive polypeptide colocalized with norepinephrine in sympathetic neurons. The effects of ischemia and reperfusion on plasma NPY levels were studied and compared in the mongrel dog after infrarenal aortic cross-clamping. We found a two-to threefold increase in NPY levels during ischemia (initial 10.0 ± 1.8 pmol/L vs. maximum 24.7 ± 2.31 pmole/L,p< 0.001). The increase in NPY remained following reperfusion (initial 10.0 ± 0.8 pmole/L vs. maximum 23.9 ± 2.31 pmole/L,p< 0.001). These data reveal that NPY is released during ischemia and reperfusion and may be involved in mediating remote vascular events associated with infrarenal aortic cross-clamping.