Efficient recombination of Lym-1 scFv gene using multiple doubly-restricted DNA fragments

In order to improve radioimmunotherapy of lymphoma, a Lym-1 single-chain antigen-binding (scFv) protein molecule was produced. Because the commonly used polymerase chain reaction (PCR) method frequently causes unexpected mutations, we developed a non-PCR method for scFv gene assembly. The method involved a stepwise linkage of doubly-restricted DNA fragments and re-digestion of the resultant concatamers. Using this strategy, the Lym-1 scFv expression gene was readily constructed without mutations. The recombinant gene was cloned into an expression vector and scFv protein was expressed. The method can be used for other genes or DNA recombination.

FDA use of international standards in the premarket review process

"This is an exciting time," says Eric Rechen, policy analyst in the U.S. Food and Drug Administration's (FDA) Office of Device Evaluation (ODE). "We're entering an era in which standards will have a more prominent role in the review of medical devices than ever before." During the past 10 years, there has been significant growth in the importance of standards in regulatory processes, as Donald J. Barth, regulatory staff manager for the Medical Products Group at Hewlett Packard Company, notes in setting the stage for discussion of the latest developments. Donald Marlowe, director of the FDA's Office of Science and Technology, and Rechen explain the use of standards in the regulatory review process as part of FDA efforts to ensure public safety in a time of shrinking agency resources. Marlowe discusses provisions of the FDA Modernization Act of 1997 that allow manufacturers to submit a declaration of conformity to a standard to satisfy premarket review requirements. A guidance on the recognition and use of consensus standards, a list of recognized standards, and a list of frequently asked questions are available at the Web site of the Center for Devices and Radiological Health (CDRH) at www.fda.gov/cdrh and via the AAMI Web site at www.aami.org. The information is also available by telephone via CDRH Facts on Demand at 800-899-0381. Rechen provides details about the two new approaches for premarket notifications available under the new 510(k) paradigm. Manufacturers may demonstrate substantial equivalence through special and abbreviated 510(k)s in addition to traditional 510(k)s. A copy of the new 510(k) paradigm is available at the AAMI and CDRH Web sites and through Facts on Demand. As the FDA and many manufacturers enter the new world of abbreviated and special 510(k)s, Larry Kroger, GE Medical Systems, provides his comments based on the 4 years of experience manufacturers of diagnostic x-ray products have had with simplified 510(k)s. A comparison of the European conformity assessment procedures with the new 510(k) paradigm will appear in an upcoming issue of BI&T.