Acquired Carotid-Jugular Fistula Secondary to a Pseudoaneurysm Following Carotid Endarterectomy.

Acquired arteriovenous fistulas involving the carotid artery are most frequently the result of trauma and iatrogenic causes such as central venous catheterisation. Occasionally, they may develop spontaneously due to erosion of an aneurysm into an adjacent vein. We report a rare case of an acquired carotid-jugular fistula secondary to a pseudoaneurysm that occurred four months following carotid endarterectomy.

Alternative access - Iliac artery angioplasty performed via left arm brachiocephalic fistula.

The majority of peripheral endovascular interventions are performed with access through the groin, followed by brachial and radial artery approaches. We describe a unique case of successful iliac artery endovascular intervention, performed via a left upper limb brachiocephalic fistula access site.

Proteomics of ischemia and reperfusion injuries in rabbit myocardium with and without intervention by an oxygen-free radical scavenger.

A brief period of ischemia followed by timely reperfusion may lead to prolonged, yet reversible, contractile dysfunction (myocardial stunning). Damage to the myocardium occurs not only during ischemia, but also during reperfusion, where a massive release of oxygen-free radicals (OFR) occurs. We have previously utilized 2-DE and MS to define 57 protein spot changes during brief ischemia/reperfusion (15 min ischemia, 60 min reperfusion; 15I/60R) injury in a rabbit model (White, M. Y., Cordwell, S. J., McCarron, H. C. K., Prasan, A. M. et al., Proteomics 2005, 5, 1395-1410) and shown that the majority of these occur because of physical and/or chemical PTMs. In this study, we subjected rabbit myocardium to 15I/60R in the presence of the OFR scavenger N-(2-mercaptopropionyl) glycine (MPG). Thirty-seven of 57 protein spots altered during 15I/60R remained at control levels in the presence of MPG (15I/60R + MPG). Changes to contractile proteins, including myosin light chain 2 (MLC-2) and troponin C (TnC), were prevented by the addition of MPG. To further investigate the individual effects of ischemia and reperfusion, we generated 2-DE gels from rabbit myocardium subjected to brief ischemia alone (15I/0R), and observed alterations of 33 protein spots, including 18/20 seen in both 15I/60R-treated and 15I/60R + MPG-treated tissue. The tissue was also subjected to ischemia in the presence of MPG (15I/0R + MPG), and 21 spot changes, representing 14 protein variants, remained altered despite the presence of the OFR scavenger. These ischemia-specific proteins comprised those involved in energy metabolism (lactate dehydrogenase and ATP synthase alpha), redox regulation (NADH ubiquinone oxidoreductase 51 kDa and GST Mu), and stress response (Hsp27 and 70, and deamidated alpha B-crystallin). We conclude that contractile dysfunction associated with myocardial stunning is predominantly caused by OFR damage at the onset of reperfusion, but that OFR-independent damage also occurs during ischemia. These ischemia-specific protein modifications may be indicative of early myocardial injury.

Modifications of myosin-regulatory light chain correlate with function of stunned myocardium.

The precise molecular basis for myocardial stunning remains unresolved, but protein damage within the myofibril is a likely mechanism. We used two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) to identify protein modifications in stunned myocardium. In isolated, perfused rabbit hearts, low-flow ischemia (1 ml/min) and reperfusion resulted in impaired left-ventricular function (rate-pressure product (RPP) after 15-min ischemia: 65 +/- 5% pre-ischemia). We have characterised the sequence of ventricular myosin-regulatory light chain (MLC-2, 18 kDa) in rabbit myocardium and identified two non-phosphorylated (P(1) and P(2)) and two phosphorylated (P(3) and P(4) at Ser-14) isoelectric point variants. MS revealed that the acidic isoelectric point post-translational modification of P(1) and P(3), resulting in P(2) and P(4) respectively, was due to deamidation of asparagine to aspartate at residue 13, adjacent to Ser-14 phosphorylation site. After 15-min ischemia and reperfusion, a 15-kDa MLC-2 fragment was detected (MLC-2(14-165)), resulting from N-terminal cleavage between Asn/Asp-13 and Ser-14 of non-phosphorylated MLC-2, which accounted for 9.8% of visible non-phosphorylated MLC-2. Subsequent 2-DE of subcellular fractions showed that the fragment was lost from the myofilament. Treatment with an OH radical scavenger, N-(2-mercaptopropionyl) glycine (MPG, 3 mmol/l), preserved contractile function (RPP: 106 +/- 9% pre-ischemia) and prevented cleavage of MLC-2. Proteolytic damage to MLC-2, related to presence of OH radicals during reperfusion, correlates with myocardial stunning and may contribute to impaired contractility.

Duration of ischaemia determines matrix metalloproteinase-2 activation in the reperfused rabbit heart.

It has been hypothesised that activation of matrix metalloproteinase-2 (MMP-2) contributes to reversible myocardial dysfunction (stunning) following short-term ischaemia and reperfusion. Gelatin zymography was used to measure release of both pro-MMP-2 (72 kDa) and MMP-2 (62 kDa), into the coronary effluent from isolated, perfused rabbit hearts during 90 min aerobic perfusion (control), or low-flow ischaemia (15 or 60 min at 1 mL/min), followed by 60 min reperfusion. In controls, pro-MMP-2 was detected in the coronary effluent throughout the first 30 min of aerobic perfusion, but MMP-2 was not detected. In contrast, MMP-2 was detected in the coronary effluent during reperfusion after both 15 and 60 min ischaemia. However, while left ventricular systolic function was impaired after both 15 min and 60 min ischaemia, a significant increase in the release of MMP-2 was only detected in hearts following 60 min ischaemia. The dissociation between mechanical function and MMP-2 levels suggest that MMP-2 does not contribute to myocardial stunning in this model, but may contribute to myocardial dysfunction following prolonged ischaemia.