Biomedical subjects

Raymond Snyder

Publications and source records attributed to Raymond Snyder.

4 recordsLinked to original sources

PubMed2005

Arsenic transport and transformation associated with MSMA application on a golf course green.

The impact of extensively used arsenic-containing herbicides on groundwater beneath golf courses has become a topic of interest. Although currently used organoarsenicals are less toxic, their application into the environment may produce the more toxic inorganic arsenicals. The objective of this work was to understand the behavior of arsenic species in percolate water from monosodium methanearsonate (MSMA) applied golf course greens, as well as to determine the influences of root-zone media for United State Golf Association (USGA) putting green construction on arsenic retention and species conversion. The field test was established at the Fort Lauderdale Research and Education Center (FLREC), University of Florida. Percolate water was collected after MSMA application for speciation and total arsenic analyses. The results showed that the substrate composition significantly influenced arsenic mobility and arsenic species transformation in the percolate water. In comparison to uncoated sands (S) and uncoated sands and peat (S + P), naturally coated sands and peat (NS + P) showed a higher capacity of preventing arsenic from leaching into percolate water, implying that the coatings of sands with clay reduce arsenic leaching. Arsenic species transformation occurred in soil, resulting in co-occurrence of four arsenic species, arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in percolate water. The results indicated that substrate composition can significantly affect both arsenic retention in soil and arsenic speciation in percolate water. The clay coatings on the soil particles and the addition of peat in the soil changed the arsenic bioavailability, which in turn controlled the microorganism-mediated arsenic transformation. To better explain and understand arsenic transformation and transport after applying MSMA in golf green, a conceptual model was proposed.

Arsenic↗

PubMed2005

Site of primary tumor has a prognostic role in operable breast cancer: the international breast cancer study group experience.

PURPOSE: Cancer presenting at the medial site of the breast may have a worse prognosis compared with tumors located in external quadrants. For medial tumors, axillary lymph node staging may not accurately reflect the metastatic potential of the disease. PATIENTS AND METHODS: Eight-thousand four-hundred twenty-two patients randomly assigned to International Breast Cancer Study Group clinical trials between 1978 and 1999 were classified as medial site (1,622; 19%) or lateral, central, and other sites (6,800; 81%). Median follow-up was 11 years. RESULTS: A statistically significant difference was observed for patients with medial tumors versus those with nonmedial tumors in disease-free survival (DFS; 10-year DFS, 46% v 48%; HR, 1.10; 95% CI, 1.02 to 1.18; P = .01) and overall survival (10-year OS 59% v 61%; HR, 1.09; 1.01 to 1.19; P = .04). This difference increased after adjustment for other prognostic factors (HR, 1.22; 95% CI, 1.13 to 1.32 for DFS; and HR, 1.24; 95% CI, 1.14 to 1.35 for OS; both P = .0001). The risk of relapse for patients with medial presentation was largest for the node-negative cohort and for patients with tumors larger than 2 cm. In the subgroup of 2,931 patients with negative axillary lymph nodes, 10-year DFS was 61% v 67%, and OS was 73% v 80% for medial versus nonmedial sites, respectively (HR 1.33; 95% CI, 1.15 to 1.54; P = .0001 for DFS; and HR 1.40; 95% CI, 1.17 to 1.67; P = .0003 for OS). CONCLUSION: Tumor site has a significant prognostic utility, especially for axillary lymph node-negative disease, that should be considered in therapeutic algorithms. New staging procedures such as biopsy of the sentinel internal mammary nodes or novel imaging methods should be further studied in patients with medial tumors.

Adult↗

PubMed2005

Reducing the global breast cancer burden: the importance of patterns of care research.

Breast cancer treatment guidelines are not uniformly followed in clinical practice, with evidence for substantial variations in treatment patterns, quality of care, and patient outcomes among and within countries. The factors that drive treatment decisions are unclear. Furthermore, the impact of different treatment strategies on survival is poorly understood outside the clinical trial setting. Sources of patterns of care information often have limitations in completeness, quality, timeliness of reporting, and relevance to the larger population. Patterns of care studies frequently lack details on cancer stage at diagnosis, tumor biology, and treatment received. It is difficult to compare data between studies and/or track changes over time because of variations in data sources and collection techniques. Thus, the design and implementation of a global registry is sorely needed in order to prospectively evaluate worldwide patterns of care and outcomes in patients with breast cancer. Components of this registry should include random selection of centers of variable practice settings in multiple countries and accurate and rapid data reporting at prestudy and follow-up timepoints. Data collected would include tumor and demographic factors, staging information, treatment rendered, and survival. Variables that influenced the treatment selected would be assessed. This unique international effort would allow the development of strategies to improve diagnostic and treatment-related standards of care and survival outcomes, thus reducing the breast cancer burden worldwide.

Breast Neoplasms↗

PubMed2004

High-transfer-rate high-capacity holographic disk data-storage system.

We describe the design and implementation of a high-data-rate high-capacity digital holographic storage disk system. Various system design trade-offs that affect density and data-rate performance are described and analyzed. In the demonstration system that we describe, high-density holographic recording is achieved by use of high-resolution short-focal-length optics and correlation shift multiplexing in photopolymer disk media. Holographic channel decoding at a 1-Gbit/s data rate is performed by custom-built electronic hardware. A benchmark sustained optical data-transfer rate of 10 Gbits/s has been successfully demonstrated.

Journal Article↗