Inteins and affinity resin substitutes for protein purification and scale up

The development of self-cleaving fusion-tag technology has greatly simplified the purification of recombinant proteins at laboratory scale. The self-cleaving capability of these tags has recently been combined with additional purification tags to generate novel and convenient protein purification methods at a variety of scales. In this review, we describe some of these methods, and provide a rudimentary economic analysis of hypothetical large-scale applications. This work is expected to provide a rough outline for the evaluation of these methods for large-scale bioprocessing of a variety of products

Minimally invasive surgery and cancer: controversies part 1

Perhaps there is no more important issue in the care of surgical patients than the appropriate use of minimally invasive surgery (MIS) for patients with cancer. Important advances in surgical technique have an impact on early perioperative morbidity, length of hospital stay, pain management, and quality of life issues, as clearly proved with MIS. However, for oncology patients, historically, the most important clinical questions have been answered in the context of prospective randomized trials. Important considerations for MIS and cancer have been addressed, such as what are the important immunologic consequences of MIS versus open surgery and what is the role of laparoscopy in the staging of gastrointestinal cancers? This review article discusses many of the key controversies in the minimally invasive treatment of cancer using the pro–con debate format

Measurement of thermal conductivity of permanent mold ceramic coatings

The permanent mold process is one of the major casting processes, using metal molds to give high strength castings due to rapid solidification. Ceramic coatings on the mold surfaces are used to achieve the desired solidification rate of the casting, to minimize thermal shock and failure of the mold, and to facilitate release of the casting from the mold. Because the ceramic coatings have an important effect on the thermal behavior and thermal fatigue resistance of the permanent molds, knowledge of the thermal conductivity of the coating is essential for any modeling of the system. In this research, a survey of experimental methods for measuring thermal conductivity was conducted and the longitudinal transient method was selected as the best choice for simulating actual conditions in a permanent mold casting process. A steel bar is coated with the ceramic and dipped into molten aluminum at 700C; the temperature gradients are measured using a data acquisition system connected to a computer. From the acquired data, the thermal conductivity of the steel/coating system, the steel, and the coating can be determined. The thermal conductivity of an insulating-type mold coating was determined to test this technique. The thermal conductivity measurements from uncoated steel samples were very close to those reported in the literature for the steel. The thermal conductivity of the mold coating -- 0.027 W/cm C -- was close to that calculated based on the properties of the constituents in the coating. The influence of the coating on insulation characteristics was also measured from the tests --Abstract, pages iii-iv

Novel and economical purification of recombinant proteins: Intein-mediated protein purification using in vivo polyhydroxybutyrate (PHB) matrix association

This work combines two well-established technologies to generate a breakthrough in protein production and purification. The first is the production of polyhydroxybutyrate (PHB) granules in engineered strains of Escherichia coli. The second is a recently developed group of self-cleaving affinity tags based on protein splicing elements known as inteins. By combining these technologies with a PHB-specific binding protein, a self-contained protein expression and purification system has been developed. In this system, the PHB-binding protein effectively acts as an affinity tag for desired product proteins. The tagged product proteins are expressed in E. coli strains that also produce intracellular PHB granules, where they bind to the granules via the PHB-binding tag. The granules and attached proteins can then be easily recovered following cell lysis by simple mechanical means. Once purified, the product protein is self-cleaved from the granules and released into solution in a substantially purified form. This system has been successfully used at laboratory scale to purify several active test proteins at reasonable yield. By allowing the bacterial cells to effectively produce both the affinity resin and tagged target protein, the cost associated with the purification of recombinant proteins could be greatly reduced. It is expected that this combination of improved economics and simplicity will constitute a significant breakthrough in both large-scale production of purified proteins and enzymes and high-throughput proteomics studies of peptide libraries