Competitive, immunometric assay for fusion protein quantification: protein production prioritization.

Effective drug discovery demands the availability of microgram to gram quantities of high-quality protein encoded by novel transcripts. Protein expression vectors designed for large-scale protein production often include one or more specific tags to such transcripts, to simplify the purification of the targeted protein. Optimization of the complex expression and purification process requires the evaluation of multiple expression candidate clones to identify a production-suitable construct in terms of quality and final protein yield. Efficiency of the entire expression screening process is typically assessed by direct visualization of the banding patterns from whole-cell lysates on SDS-PAGE gels, by direct staining and/or immunoblotting, using antibodies against the tag or the protein of interest. These techniques, generally run under denaturing conditions, have proven to be only marginally predictive of the purification yield and authentic folding for native proteins. Small-scale, multiparallel affinity purification followed by SDS-PAGE analysis is more predictive for expression screening; however, this approach is labor intensive and time consuming. Here we describe the development of an alternative expression efficiency assessment technique, designed to evaluate the accessibility of affinity tags expressed with the desired fusion proteins, using acoustic membrane microparticle assay technology on the ViBE protein analysis workstation.

In-hospital mortality associated with the use of intra-aortic balloon counterpulsation.

We analyzed in-hospital mortality for patients treated with intra-aortic balloon counterpulsation from the Benchmark Counterpulsation Outcomes Registry (n = 25,136). In-hospital mortality was higher in patients who received only medical interventions (32.5%) than in those who underwent percutaneous (18.8%) and surgical (19.2%) interventions, and was greatest in the first days after hospital admission for all 3 intervention types. Therefore, diagnostic evaluation and treatment decisions should be made as early as possible, and physicians should be aware of associated risk factors in making choices for patients.

Intra-aortic balloon counterpulsation in US and non-US centres: results of the Benchmark Registry.

AIMS: To examine differences in patient characteristics and outcomes in 19636 patients enrolled in the USA and 3027 patients enrolled in other countries undergoing intra-aortic balloon pump (IABP) counterpulsation. METHODS AND RESULTS: Indications for IABP use; a larger percentage of US patients were identified as 'early support and stabilization for angiography or angioplasty' (21.1% US vs 11.8% non-US), and 'pre-operative support for high-risk CABG' (15.9% vs 6.6%). A smaller percentage of US patients vs non-US patients were identified as 'weaning from cardiopulmonary bypass' (14.3% vs 28.2%), and 'refractory ventricular failure' (6.2% vs 9.8%). One out of five patients in both groups was listed as 'cardiogenic shock' (18.9% US vs 20.2% non-US). All cause, risk-adjusted, in-hospital mortality (20.1% vs 28.7%; P<0.001), and mortality with IABP in place (10.8% vs 18.0%; P<0.001) were lower at US vs non-US sites. In both US and non-US institutions, IABP associated complication rates, such as IABP-related mortality (0.05% vs 0.07%), major limb ischaemia (0.9% vs 0.8%), and severe bleeding (0.9% vs 0.8%), were low. CONCLUSIONS: IABP counterpulsation is deployed at an earlier clinical stage in US patients. Mortality rates are higher for non-US patients, particularly for patients with non-surgery cardiac interventions, even after adjusting for risk factors. Complication rates were low. Physicians should therefore not be reluctant to use IABP in high-risk patients undergoing cardiac procedures.

Contemporary utilization and outcomes of intra-aortic balloon counterpulsation in acute myocardial infarction: the benchmark registry.

OBJECTIVES: We sought to examine contemporary utilization patterns and clinical outcomes in patients with acute myocardial infarction (AMI) requiring intra-aortic balloon pump (IABP) counterpulsation. BACKGROUND: Despite increasing experience with and broadened indications for intra-aortic counterpulsation, the current indications, associated complications, and clinical outcomes of IABP use in AMI are unknown. METHODS: Between June 1996 and August 2001, data were prospectively collected from 22,663 consecutive patients treated with aortic counterpulsation at 250 medical centers worldwide; 5,495 of these patients had AMI. RESULTS: Placement of an IABP in AMI patients was most frequently indicated for cardiogenic shock (27.3%), hemodynamic support during catheterization and/or angioplasty (27.2%) or prior to high-risk surgery (11.2%), mechanical complications of AMI (11.7%), and refractory post-myocardial infarction unstable angina (10.0%). Balloon insertions were successful in 97.7% of patients. Diagnostic catheterization was performed in 96% of patients, and 83% underwent coronary revascularization before hospital discharge. The in-hospital mortality rate was 20.0% (38.7% in patients with shock) and varied markedly by indication and use of revascularization procedures. Major IABP complications occurred in only 2.7% of patients, despite median use for three days, and early IABP discontinuation was required in only 2.1% of patients. CONCLUSIONS: With contemporary advances in device technology, insertion technique, and operator experience, IABP counterpulsation may be successfully employed for a wide variety of conditions in the AMI setting, providing significant hemodynamic support with rare major complications in a high-risk patient population.

Trends in intraaortic balloon counterpulsation complications and outcomes in cardiac surgery.

BACKGROUND: As the proportion of high-risk patients for cardiac surgery increases, use of intraaortic balloon counterpulsation (IABC) has increased, especially in preoperative therapy. Although the efficacy and cost-effectiveness of IABC have been demonstrated, historically higher complication rates have dissuaded some practitioners from using IABC. METHODS: This report describes IABC use in cardiac surgery, examines trends in complications over time, and compares outcomes in preoperative versus postoperative use in a single prospective worldwide registry over the past 3 years. RESULTS: The frequency of IABC use appears to be increasing with time as the complication rates have dramatically fallen. The overall IABC-related complication rate was 6.5% (460/7,101), and the rate of major complications (requiring surgery or transfusion) was 2.1% (148/7,101). Hospital mortality was significantly lower in patients treated preoperatively with IABC compared with patients treated postoperatively (8.8% vs 28.2%, p < 0.0001), although this may be due to a selection bias in the postoperative group. CONCLUSIONS: Preoperative IABC therapy leads to better patient outcomes in high-risk CABG patients. Improved IABC technology and better surveillance have led to increased use with lower complication rates. Although selection bias is inherent in retrospective studies, the Benchmark Counterpulsation Outcomes Registry outcomes are in close concordance to prospective randomized studies previously reported.

Comparison of outcomes after 8 vs. 9.5 French size intra-aortic balloon counterpulsation catheters based on 9,332 patients in the prospective Benchmark registry.

The Benchmark intra-aortic balloon counterpulsation (IABC) registry maintains prospectively gathered clinical information on a large cohort of IABC patients. The purpose of the present report is to compare in-hospital outcomes and complications in patients treated with the newer 8 vs. 9.5 Fr size catheters. Between January 1997 and August 2000, data on 7,078 9.5 Fr and 2,254 8 Fr IABC insertions were submitted to Benchmark. This was not a randomized comparison but rather a posthoc analysis of prospectively gathered data. There was less limb ischemia with the 8 Fr IABC size catheter. There were no significant differences in bleeding or mortality between the two groups. Smaller IABC catheter size is associated with significantly less limb ischemia, especially in higher-risk patients. The large, population-based, ongoing Benchmark registry provides a useful vehicle for outcomes research concerning the evolving practice of IABC.