Biomedical subjects

Robin Miller

Publications and source records attributed to Robin Miller.

4 recordsLinked to original sources

PubMed2006

Mantle fields in the era of dynamic multileaf collimation: field shaping and electronic tissue compensation.

Mantle field radiotherapy for Hodgkin's disease is complicated by significant dose gradient (up to 10-20%) across the large fields required. Many different strategies of tissue compensation have been investigated, including custom physical compensators to provide better dose distributions. We present a method using dynamic multileaf collimator (dMLC) fluence modulation to simultaneously shape the treatment field and give homogeneous dose at depth throughout the classic mantle field. Five patients were treated for early-stage Hodgkin's disease with a conventional anterior-posterior-posterior-anterior (AP-PA) mantle field. The patients were planned using the Varian Eclipse treatment planning system, version 6.1.3, and treated on a Varian 2300CD. An AP-PA dynamic MLC beam-shaped and dose-compensated plan was created for each, and compared with the conventional blocked plan. Nine dose points were calculated at midplane in each plan. Chamber measurements were taken to confirm accurate dMLC delivery of the planned doses. The mean dose per fraction, relative to a central axis dose of 1.8 Gy, was increased in the conventional plans compared with the dMLC plans in the right (R) neck, left (L) neck, R supraclavicular, L supraclavicular, and L axillary points. The mediastinum tended to be underdosed relative to central axis, with the mid-mediastinal and lower mediastinal points showing improved coverage with the dMLC plans. Measurements showed excellent agreement between planned doses and delivered doses, with less than 2% in-field variation. Dynamic MLC fluence modulation was used to effectively deliver a mantle field that is both shape- and electronically-dose-compensated with sliding window MLC. Homogeneity was significantly improved throughout the treatment field, and measurements confirmed accurate dose delivery using this technique.

Dose-Response Relationship, Radiation↗

PubMed2003

Negative regulation of T cell activation by placental protein 14 is mediated by the tyrosine phosphatase receptor CD45.

CD45 is the major protein tyrosine phosphatase receptor on T cell surfaces that functions as both a positive and a negative regulator of T cell receptor (TCR) signaling. Although CD45 is required for the activation of TCR-associated Src family kinases, it also dephosphorylates phosphoproteins involved in the TCR-signaling cascade. This study links CD45 to the inhibitory activity of placental protein 14 (PP14), a major soluble protein of pregnancy that is now known to be a direct modulator of T cells and to function by desensitizing TCR signaling. PP14 and CD45 co-capped with each other, pointing to a physical linkage between the two. Interestingly, however, the binding of PP14 to T cell surfaces was not restricted to CD45 alone, with evidence showing that PP14 binds to other surface molecules in a carbohydrate-dependent fashion. Notwithstanding the broader molecular binding potential of PP14, its interaction with CD45 appeared to have special functional significance. Using transfected derivatives of the HPB. ALL mutant T cell line that differ in CD45 expression, we established that the inhibitory effects of PP14 are dependent upon the expression of intact CD45 on T cell surfaces. Based upon these findings, we propose a new immunoregulatory model for PP14, wherein one of its surface molecular targets, CD45, mediates its T cell inhibitory activity, accounting for the intriguing capacity of PP14 to elevate TCR activation thresholds and thereby down-regulate T cell activation.

Calcium↗

PubMed2003

Early implementation of Proposition 36: criminal justice and treatment system issues in eight counties.

This article examines key differences emerging in implementation of California's Proposition 36 voter initiative across eight diverse large, medium, and small counties. The data were collected in 2001 in a key informant survey of county policymakers. Unlike most major California criminal justice initiatives of recent years, Proposition 36 represents a potential lessening of adjudicatory and penal controls rather than an increase in their severity, in this case in response to charges of drug use, possession, or transportation. Furthermore, Proposition 36 was written broadly enough to allow considerable discretion in implementation across the counties, including the specification of funding to support mandated provisions of the Act and division of oversight responsibilities among criminal justice and treatment stakeholders. Hence actual content and scope of criminal justice system procedural changes, and impact of the proposition on criminal justice and treatment systems and on arrestees, are likely to vary by county. The article identifies key approaches and decisions made in the sampled counties that are predicted to affect the proposition's impact in the areas of treatment versus criminal justice resources, prosecutorial implementation, defendant and defense responses, assessing criminal histories and treatment needs, treatment versus criminal justice supervisory responsibility, and procedural variations and client behavior.

California↗

PubMed2002

Professional's Information Link (PiL): a web-based asynchronous consultation service.

Despite the massive growth of on-line information resources, many clinicians still prefer to obtain information from other clinicians, particularly those to whom they refer patients. Based on this notion and an information needs assessment, we developed the Professional's Information Link (PiL), a Web-based asynchronous consultation service to facilitate question answering between rural clinicians and an academic medical center. The system aims to provide answers to questions within two working days. It also includes patient handouts and continuing medical education resources. Our preliminary evaluation demonstrates modest but enthusiastic use of the system.

Academic Medical Centers↗