Gel electrofocusing (EF) on Sephadex G-75, which provides relatively non-restrictive pore sizes and relatively broad protein concentration distributions (which reduces concentration-dependent aggregation), was adapted for use in glass tubes. This allows for EF with meticulously controlled low temperatures in conjunction with large sample and gel volumes. Specifically, the technique was developed for EF of steroid receptors, which are highly sensitive to temperature (temperature transformed), and whose aggregation behavior excluded the use of polyacrylamide or agarose gels. The technique uses the temperature-controlled apparatus designed for quantitative polyacrylamide gel electrophoresis, with three additions. These are a) a 12-place evacuation device for forming simultaneously 12 cylindrical Sephadex gels (either 6 or 18 mm diameter), b) an electrode arrangement capable of maintaining the same regulated voltage across several gel tubes, and c) a jacket and lid of polyurethane foam to insulate the electrolyte chambers of the EF apparatus.
A new catheter of dual lumen construction, suitable for clinical use, is capable of navigating acute vessel branches by selective retrojet fluid thrusts issuing from cowlings built into its distal sidewalls. Conventional radiopaque liquids can be used both to drive the system and to fluoroscopically locate its position relative to the vascular network. In vitro studies have shown the catheter to traverse straight vessels and negotiate difficult lateral turns over short radii in the process of entering progressively smaller branches. In vivo studies have verified these capabilities and suggest a means for embolizing tumors and arteriovenous malformations located at otherwise inaccessible regions. For arterial infusion of drugs to treat tumors, the turbulent jet action is utilized to enhance mixing within the blood stream to overcome the streaming phenomenon common to other catheters. The result is better distribution of the agent and increased opportunity for the drug to reach more of the tumor. The catheter system is undergoing clinical trials.
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