A very low diffusion Fricke gel dosimeter with functionalised xylenol orange-PVA (XOPVA).

A gel dosimeter has been developed utilising a recently reported system for reducing Fe3+ diffusion in a Fricke gel dosimeter which chelates xylenol orange to the gelling agent poly(vinyl alcohol) (PVA). Formulations were investigated using both gelatin and PVA as the gelling agent, along with the inclusion of glyoxal. The resulting gel had an optical density dose response of 0.0031 Gy-1, an auto-oxidation rate of 0.000 23 h-1, and a diffusion rate of 0.132 mm2 h-1 which is a significant improvement over previously reported gelatin based Fricke gel dosimeters. The gel was also shown to be energy and dose-rate independent and could be reused after irradiation. Thus, this gel dosimeter has the potential to provide a safe and practical solution to three dimensional radiation dosimetry in the medical environment.

Impact of tissue preservation on collagen fiber architecture.

Microarchitectural features of collagen-rich extracellular matrices provide the mechanical foundation for tissue function and exhibit topographical cues that influence cellular behavior including proliferation, migration and protein expression. Preservation of tissue microarchitecture is required for accurate evaluation of tissue characteristics and pathology. It is unclear whether common tissue preservation methods possess equal ability to preserve microarchitecture. We investigated collagen microarchitecture in samples that had been flash frozen, fixed in formalin or preserved in RNAlater®, and which contained both collagen-rich and collagen-sparse regions. Fibrillar collagen organization was characterized using picrosirius red staining and second harmonic generation (SHG) microscopy. Maintenance of collagen fiber characteristics compared to the gold standard of flash freezing depended on both the method of preservation and the local collagen content of the tissue. Both formalin fixation and RNAlater® preserved collagen fiber characteristics similar to flash freezing in collagen-rich areas of the tissue, but not in collagen-sparse regions. Analysis using picrosirius red staining indicated preservation-dependent changes in overall tissue architecture and suprafibrillar organization. Together with considerations of cost, ease of use, storage conditions and ability to use the preserved tissue for RNA or protein analysis, our quantitative characterization of the effects of preservation method on collagen microarchitecture may help investigators select the most appropriate preservation approach for their needs.

Technical Note: Preliminary investigations into the use of a functionalised polymer to reduce diffusion in Fricke gel dosimeters.

PURPOSE: A modification of the existing PVA-FX hydrogel has been made to investigate the use of a functionalised polymer in a Fricke gel dosimetry system to decrease Fe(3+) diffusion. METHODS: The chelating agent, xylenol orange, was chemically bonded to the gelling agent, polyvinyl alcohol (PVA) to create xylenol orange functionalised PVA (XO-PVA). A gel was created from the XO-PVA (20% w/v) with ferrous sulfate (0.4 mM) and sulfuric acid (50 mM). RESULTS: This resulted in an optical density dose sensitivity of 0.014 Gy(-1), an auto-oxidation rate of 0.0005 h(-1), and a diffusion rate of 0.129 mm(2) h(-1); an 8% reduction compared to the original PVA-FX gel, which in practical terms adds approximately 1 h to the time span between irradiation and accurate read-out. CONCLUSIONS: Because this initial method of chemically bonding xylenol orange to polyvinyl alcohol has inherently low conversion, the improvement on existing gel systems is minimal when compared to the drawbacks. More efficient methods of functionalising polyvinyl alcohol with xylenol orange must be developed for this system to gain clinical relevance.

Outcomes of posterolateral lumbar fusion in Utah patients receiving workers' compensation: a retrospective cohort study.

STUDY DESIGN: A retrospective cohort study consisting of a medical record review and a follow-up telephone survey of patients with lumbar fusion, at least 2 years after their surgery, was performed. OBJECTIVE: To identify presurgical correlates and long-term outcomes from posterolateral lumbar fusion in Utah patients receiving workers' compensation. SUMMARY OF BACKGROUND DATA: Lumbar fusion has been criticized for its highly variable outcomes, and compensated workers are at particular risk for poor outcomes. Evidence suggests that presurgical psychosocial factors may be important modifiers of back pain reporting and back surgery outcomes. METHODS: The patients in this study were 185 compensated workers in Utah who underwent posterolateral lumbar fusion. Patient medical records were independently reviewed, and medical and sociodemographic variables were coded. A telephone outcome survey was completed with 130 patients (70%) an average of 4.6 years after their surgery. RESULTS: Reported solid fusion, reoperation, and disability rates for the follow-up sample were 74%, 24%, and 25%, respectively. As reported by the patients, 41% experienced no change or a worsened quality of life. Mean scores from the Roland and Morris Back Pain Disability Questionnaire, the Stauffer-Coventry-Index, and the Short-Form 20 Multidimensional Health Survey indicate that many patients experienced postsurgical dysfunction. Presurgical predictors of outcomes were number of prior low back operations, income at time of injury, age, litigation, and depression. CONCLUSIONS: Outcomes of posterolateral lumbar fusion among compensated workers in Utah are inconsistent. Outcomes can be predicted by presurgical sociodemographic variables. Screening for such presurgical risk factors may be important for prudent surgical decisions and rehabilitation planning.

Does pediatric orthopedic subspecialization affect hospital utilization and charges?

In the current climate of health care reform, there is a perception that overspecialization is responsible for increased medical costs. Few studies support the premise that high-quality surgical subspecialization improves the cost effectiveness of care. The purpose of this study was to compare hospital utilization and charges between a pediatric hospital staffed by pediatric orthopedic subspecialists and a community hospital system for the care of closed femur fractures and slipped capital femoral epiphysis (SCFE) in a pediatric population. We reviewed hospital charges and length-of-stay (LOS) data for all children treated for closed femoral shaft fractures and SCFE between 1992 and 1994 within the Intermountain Health Care System (IHC). Within the IHC, there are 23 community hospitals and one children's hospital (PCMC). Patients were matched for age and injury severity. Four of six orthopedic surgeons at PCMC are pediatric orthopedists, but none of the community orthopedists has subspecialty training in pediatric orthopedics. For closed femoral shaft fractures (n = 334), the average hospital charges were less (PCMC, $4,943/Other IHC, $9,031), and length of stay was shorter (PCMC, 2.81 days/Other IHC, 8.91 days) when the child was treated at the children's hospital by pediatric orthopedic subspecialists. For SCFE (n = 63), the average hospital charges were less (PCMC, $2,824/Other IHC, $3,544) and the length of stay was shorter (PCMC, 1.13 days/Other IHC, 1.64 days) at the children's hospital. These data suggest that hospital utilization and charges were significantly decreased if the care was provided by pediatric orthopedic subspecialists in a children's hospital.

A comparison of manual versus computer-assisted radiographic measurement. Intraobserver measurement variability for Cobb angles.

STUDY DESIGN: A comparison between computer-assisted measurement using digitized radiographs, which has the potential to reduce error, and manual measurement using standard radiographs. OBJECTIVE: To assess measurement variability for the Cobb method on digital radiographs and compare it with that of manual measurements on standard radiographs. BACKGROUND DATA: Studies of the Cobb method have demonstrated multiple sources of error leading to significant intraobserver measurement variability. Estimates for the 95% confidence interval for intraobserver variability range from 2.8 degrees to 10 degrees. METHODS: Twenty-four scoliosis radiographs were measured by six examiners. Two measurement sets were done manually ("manual set"), and two measurement sets were done on digitized images using a computer mouse ("computer set"). RESULTS: For the manual set, the 95% confidence interval for intraobserver variability was 3.3 degrees (range, 2.5-4.5 degrees). For the computer set, the value was 2.6 degrees (range, 2.3-3.3 degrees). This difference in 95% confidence intervals between the manual and computer sets was statistically significant (P < 0.001). CONCLUSIONS: The results of this study demonstrate that intraobserver variability for manual and computer Cobb angle measurements yield a 95% confidence interval of approximately 3 degrees, with the computer having a slightly lower variability. The computer technique removes sources of intrinsic error, e.g., the variability introduced by using different manual protractors, the inaccuracy of standard protractors, and the use of wide-diameter radiographic markers. Identical digital images can be shared electronically between centers, without having to duplicate and mail films. Multicenter studies in which different examiners will be measuring Cobb angles may consider using the computer as a measuring device to reduce intrinsic measurement errors.

The development of an instrument to measure motivation for marathon running: the Motivations of Marathoners Scales (MOMS).

This study reports the development of an instrument to assess the motives of marathon runners. The Motivations of Marathoners Scales (MOMS) contains 56 items distributed across nine scales. Content areas covered included health orientation, weight concern, self-esteem, life meaning, psychological coping, affiliation, recognition, competition, and personal goal achievement. Adequate internal consistency (Cronbach's alpha range .80 to .93), retest reliability (intraclass Rs range .71 to .90), and factorial validity of the scales were demonstrated. Assessment of the relationship between individual MOMS scales and other variables of conceptual relevance documents early evidence for the convergent and discriminant validity of the instrument. Future uses of the MOMS are discussed in light of theoretical, empirical, and practical considerations.

Hypnotic susceptibility, cognitive dissociation, and runner's high in a sample of marathon runners.

I studied the hypnotic ability of marathon runners as it relates to cognitive dissociation while running and to runner's high. Dissociating runners use a cognitive style in which they cut themselves off from the sensory feedback they would normally receive from their body. Marathon runners demonstrated high hypnotic susceptibility scores. Additionally, use of dissociation as a running strategy during the marathon was positively related to susceptibility, and runners who dissociated in training had higher susceptibility scores than did other runners. Runner's high was not related to hypnotic susceptibility; however, it was positively related to dissociation. The most common description of runner's high was general relaxation, whereas the least used description was total euphoria. Surprisingly some runners defined runner's high in ambivalent or negative terms. These results were related to the processes of self-hypnosis and to the positive mental health benefits of running.