Evaluation of sieving polymers for fast, reproducible electrophoretic analysis of short tandem repeats (STR) in capillaries

Efficient capillary electrophoretic STR analysis requires rapid, reproducible and robust separation of DNA fragments with reasonable capillary longevity--this is currently accomplished using proprietary commercial polymeric sieving matrices specifically developed for this separation. These matrices, while effective, are costly and do not provide adequate resolution of STR DNA fragments in capillaries with shorter effective separation lengths, increasing the time required to accomplish the separation and minimizing the potential extrapolation to other miniaturized platforms. As the forensic community looks toward next generation microchip technology as a means of processing casework more rapidly, new sieving polymers need to be evaluated for utilization in this platform. The research presented here describes the assessment of commercially-available polymeric sieving matrices for STR analysis, with consideration given to feasibility of incorporation into a microdevice. Polymer composition, molecular weight, and concentration were evaluated, along with an assessment of the effects of buffer composition, separation temperature, and capillary length. These variables were evaluated individually or collectively on the ability to resolve STR DNA fragments and the reproducibility of the separations and the results compared to a proprietary commercial product. A 600,000 Da MW poly(ethylene oxide) (PEO) solution at a 3% (w/v) concentration was determined to be the most suitable matrix for these separations. This polymer, in coated capillaries, provided highly robust and reproducible separations, with near baseline resolution of fragments having single base differences. Reductions in the temperature of the separation, from 60 degrees C to 40 degrees C, and the urea concentration of the buffer, from 7 M to 3.5 M, provided increased longevity of the PEO polymer for repeated separations. Comparison of this polymer with currently specified commercial products used for STR analysis showed that the optimized PEO matrix provided superior separations under all conditions tested. In addition, PEO could be utilized in shorter capillary systems, with a concurrent decrease in analysis time, highlighting its potential for use in shortened capillary or microdevice systems.     

The who, what, and why of risk adjustment: a technology on the cusp of adoption

Risk adjustment (RA) consists of a series of techniques that account for the health status of patients when predicting or explaining costs of health care for defined populations or for evaluating retrospectively the performance of providers who care for them. Although the federal government seems to have settled on an approach to RA for Medicare Advantage programs, adoption and implementation of RA techniques elsewhere have proceeded much more slowly than was anticipated. This article examines factors affecting the adoption and use of RA outside the Medicare program using case studies in six U.S. health care markets (Baltimore, Seattle, Denver, Cleveland, Phoenix, and Atlanta) as of 2001. We found that for purchasing decisions, RA was used exclusively by public agencies. In the private sector, use of risk adjustment was uncommon and scattered and assumed informal and unexpected forms. The most common private sector use of RA was by health plans, which occasionally employed RA in negotiations with purchasers or to allocate resources internally among providers. The article uses classic technology diffusion theory to explain the adoption and use of RA in these six markets and derives lessons for health policy generally and for the future of RA in particular. For health policy generally, the differing experiences of public and private actors with RA serve as markers of the divergent paths that public and private health care sectors are pursuing with respect to managed care and risk sharing. For the future of RA in particular, its history suggests the need for health service researchers to consider barriers to use adoption and new analytic technologies as they develop them.     

Obesity, courts, and the new politics of public health

Health care politics are changing. They increasingly focus not on avowedly public projects (such as building the health care infrastructure) but on regulating private behavior. Examples include tobacco, obesity, abortion, drug abuse, the right to die, and even a patient's relationship with his or her managed care organization. Regulating private behavior introduces a distinctive policy process; it alters the way we introduce (or frame) political issues and shifts many important decisions from the legislatures to the courts. In this article, we illustrate the politics of private regulation by following a dramatic case, obesity, through the political process. We describe how obesity evolved from a private matter to a political issue. We then assess how different political institutions have responded and conclude that courts will continue to take the leading role.     

PENDULUM--a guideline-based approach to the interpretation of STR mixtures

Several years ago, a theory to interpret mixed DNA profiles was proposed that included a consideration of peak area using the method of least squares. This method of mixture interpretation has not been widely adopted because of the complexity of the associated calculations. Most reporting officers (RO) employ an experience and judgement based approach to the interpretation of mixed DNA profiles. Here we present an approach that has formalised the thinking behind this experience and judgement. This has been written into a computer program package called PENDULUM. The program uses a least squares method to estimate the pre-amplification mixture proportion for two potential contributors. It then calculates the heterozygous balance for all of the potential sets of genotypes. A list of "possible" genotypes is generated using a set of heuristic rules. External to the programme the candidate genotypes may then be used to formulate likelihood ratios (LR) that are based on alternative casework propositions. The system does not represent a black box approach; rather it has been integrated into the method currently used by the reporting officers at the Forensic Science Service (FSS). The time saved in automating routine calculations associated with mixtures analysis is significant. In addition, the computer program assists in unifying reporting processes, thereby improving the consistency of reporting.