This case study of the public policy implications of introducing a new technology in radiology, namely, low-osmolar contrast media (LOCM), raises the issues of whether and how to place appropriate limits on new technologies. Although these contrast media represent small episodic costs, they may add up to an aggregate expenditure of nearly $1 billion per year if used for all contrast injections. As a result, this technology raises a number of important medical, economic, legal, and public policy questions. Our cost-effectiveness analysis and an analysis of the medical evidence suggest that LOCM should be limited to high-risk patients. We discuss in this article how the legal system might respond to such limitations, and we consider various public policy options for adopting restrictions on use. We conclude that the medical profession should take the lead in developing protocols for appropriate assessment, reimbursement, and use of LOCM. 相似文献
After intravenous injection of 1010 plaque forming particles of ØX174 bacteriophage into White Rock fowls, immune elimination began at 30 hours and viable phage was cleared from the circulation by 50–52 hours, the approximate time at which detectable antibody appeared. Little change was noted in the serum neutralizing activity in the interval from 44 to 217 days after injection, at which time the birds were reinjected with ØX174.
Sephadex Peak I (19S globulin) accounted for most of the early activity of the primary response. By Day 9 most of the activity had shifted to Peak II (7S globulin). In the secondary response, the shift had occurred by Day 4. Both 19S and 7S globulin fractions showed an increase in activity when compared to the same days of the primary response, but the 7S increase was proportionately greater.
All sera and serum fractions (whether 19S or 7S) were sensitive to reduction with 2-mercaptoethanol, but became, less sensitive during the course of immunization.
With regard to the production of 19S antibody, White Rock fowls showed a different response to the particulate antigen ØX174 compared with the response to injection of the soluble antigen, bovine serum albumin. There is evidence of immunological memory in the 19S response to ØX174.
It is reported that some types of insects have a remarkable ability to detect the direction of an incident sound even though its acoustic sensory organs are in very close proximity each other. Maybe the ears are jointed by a cuticular structure with which the separated motions can be coupled mechanically and thus be magnified. In this paper, a detailed model is setup to describe the principle of this type of localization using a mechanical coupled structure. The transfer functions and the responses of the model in terms of time and frequency are analyzed to describe the mechanism of its ability of directional hearing. This analytical model provides a method to design the experimental model for the predetermined incident sound pressure, and the analysis of this model shows that this structure have the ability to determine the direction of the incident stimulus. 相似文献
Composite lymphomas are rare combinations of Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma in the same patient, where clonal relatedness has been observed in most of the few cases analyzed. Here, we report a composite classical HL and diffuse large B-cell lymphoma (DLBCL) with interesting molecular features. Micromanipulation of single cells and analysis of V gene rearrangements revealed clonal relatedness with shared and distinct mutations, indicative of derivation from a common germinal center (GC) B-cell precursor and also of further development of both lymphomas in a GC. In the DLBCL, a very high mutation load, including inactivating mutations, and two copies of the same clonal rearrangement with different mutations in single cells were observed. Intriguingly, in the DLBCL precursor somatic hypermutation activity continued after acquisition of destructive V gene mutations, a feature previously found only in Epstein-Barr virus (EBV) infected B-cell expansions. Furthermore, we found evidence of light-chain receptor revision in the lymphoma precursor during a GC reaction. Re-expression of the V(D)J recombination machinery may enhance genomic instability in GC B cells and contribute to lymphomagenesis. 相似文献