Search

Objectives. We sought to assess the angiographic outcome, complication rates and clinical features of percutaneous transluminal coronary angioplasty (PTCA) after failed thrombolysis for acute myocardial infarction. Background. “Rescue angioplasty” refers to mechanical reopening of an occluded infarct-related artery (IRA) after failed intravenous thrombolysis. Although the procedure is commonly performed, data describing its technical and clinical outcome are sparse. Early reports suggested that rescue PTCA is less often successful and produces more complications than primary PTCA. Other reports have described beneficial effects of successful rescue PTCA but adverse outcomes when PTCA is unsuccessful. Methods. Using data from the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-1) angiographic substudy, we compared clinical and angiographic outcomes of 198 patients selected for a rescue PTCA attempt with those of 266 patients with failed thrombolysis but managed conservatively and, for reference, with those of 1,058 patients with successful thrombolysis. Results. Patients offered rescue PTCA had more impaired left ventricular function than those in whom closed vessels were managed conservatively. Rescue successfully opened 88.4% of closed arteries, with 68% attaining Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow. The interventions did not increase catheterization laboratory or postprocedural complication rates. Multivariate analysis identified severe heart failure to be a determinant of a failed rescue attempt. Successful rescue PTCA resulted in superior left ventricular function and 30-day mortality outcomes, comparable to outcomes in patients with closed IRAs managed conservatively, but less favorable than in patients in whom thrombolytic therapy was initially successful. The mortality rate after a failed rescue attempt was 30.4%; however, five of the seven patients who died after failed rescue PTCA were in cardiogenic shock before the procedure. Conclusions. Rescue PTCA tends to be selected for patients with clinical predictors of a poor outcome. It is effective in restoring patency. Patients who die after a failed rescue attempt are often already in extremis before the angioplasty attempt.

Cell fusion is a characteristic cytopathic effect induced by the human immunodeficiency virus (HIV) that leads to the formation of syncytia between infected lymphocytes. Although this process has been shown to occur following the specific binding of the 110-120 kD externalized envelope molecule of the virus with the CD4 glycoprotein, the region of the HIV envelope that directly mediates cell fusion is unknown. In an attempt to identify this fusion domain, we compared the amino acid sequences from the envelope molecules of several HIV isolates to the fusion proteins of paramyxoviruses. We found that the amino terminal region of the HIV transmembrane protein gp41 had a striking degree of similarity with the fusion domain of the respiratory syncytial virus. Moreover, similar sequences were noted in the fusion proteins of other paramyxoviruses and the transmembrane envelope proteins of a variety of lentiviruses suggesting that a functional relationship exists between these glycoproteins. This finding indicates that the amino terminal region of the HIV gp41 molecule may mediate cell fusion for this virus, and could be an important target in the design of immunologic strategies for the prevention of HIV infection in vivo.

The concept of operations is often assumed when assessing different design variables in a tradespace study for a particular system architecture, The way a system operates, however, has a large effect on its performance, and can often be the only variable through which stakeholders can influence a system after the system is implemented. The concept of pliable system architectures is introduced so that operational variables can be explicitly considered and incorporated into tradespace studies. System transitions can be predicted by pliability, and these transitions can provide insight into other system “ilities” such as changeability, adaptability, flexibility and survivability. Two techniques are introduced in order to demonstrate the usefulness of the pliability concept; (1) a step-by-step process by which operational variables can be identified within a system architecture, and (2) a process by which very large tradespaces can be sampled into a manageable set of system instances that provide maximum insight for the level of effort to model them. As these new concepts and methodologies are new and part of ongoing research, they will need to be tested and validated in future work. Refereed/Peer-reviewed

Previous research has identified design principles that enable survivability for systems, but it is unclear if these principles are appropriate and sufficient for systems of systems as well. This paper presents a preliminary examination of how some of the characteristic properties of systems of systems may enable or hinder survivability, based on existing design principles and a newly proposed taxonomy of disturbances. Two new design principles, defensive posture and adaptation, are introduced. The next phase of research will be to conduct empirical studies to validate the design principles against some of the characteristic properties of systems of systems, and test hypotheses about how survivability will be affected. Refereed/Peer-reviewed