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Biomedical subjects

J R Williams

Publications and source records attributed to J R Williams.

At least 145 records · Page 8Linked to original sources
PubMed1992

Influence of radiologist grade on fluoroscopic patient dose.

The effect of radiologist grade on patient dose during fluoroscopic barium studies was assessed over a one-year period in a large teaching hospital using area-kerma measurements made with a Diamentor M2 system. The number of studies investigated was 164 for barium swallows, 274 for barium meals and 1288 for barium enemas. The patient's AP thickness was assessed at the abdominal level from a formula combining the patient's estimated height and weight. For each study there was no significant change in AP thickness as a function of radiologist grade. For all barium studies there was a trend for both the screening time and the patient dose to fall to a minimum for the grades third-year registrar/first-year senior registrar. From this group to consultant level the dose and screening time rose.

Fluoroscopy↗
PubMed1991

A system for the quality audit of treatment dose delivery in radiotherapy.

Treatment planning is a process requiring the cooperation of a number of different staff groups. The possibility for error is well recognised and quality control procedures are necessary to ensure that the chances of errors in planning leading to incorrect treatments are as low as possible. An audit system is described which is based on the calculation of the dose delivered to the patient using the parameters set for treatment as input data. The calculated dose is compared with the prescribed dose and errors greater than a defined limit are flagged. During a period of 19 months during which this audit procedure has been operating a total of 14 errors in excess of 5% were discovered and corrected, this is approximately 0.5% of the total number of plans checked.

Humans↗
PubMed1991

A method for quantitative autoradiography over stained sections of tumors exposed in vivo to radiolabeled antibodies.

Quantitative autoradiography can be an important element in calculating dose patterns delivered to tumors and normal tissues of animals injected with radiolabeled antibodies. In this article we develop a computer algorithm that permits quantitative evaluation of grain density over large areas of stained tissue with minimal grain counting. This algorithm, using spectral classification of brightfield and darkfield images, image ratios, and manual counting of small sections of an autoradiograph, yields images defined in terms of grain density, independent of staining artifacts. These quantitative images give a precise indication of intratumor radioimmunoglobulin targeting, and can serve as source functions for dosimetric calculations.

Algorithms↗
PubMed1991

Do not catheterise your nephrectomies.

A retrospective study of 100 consecutive nephrectomy patients showed a 20% catheterisation rate. Of the 11 carried out post-operatively only 4 were for urinary retention. The post-operative catheterisation rate for males was 7.1% and for females 2%. The rate of post-operative retention was 4.4%, which is much lower than that reported from other units. This rate of post-operative catheterisation for retention is so low that in spite of the very mild increase in complications compared with intra-operative catheterisation, the practice of routine prophylactic catheterisation of nephrectomy patients is unnecessary and cannot be recommended.

Adolescent↗
PubMed1991

Changes in physicians' sources of pharmaceutical information: a review and analysis.

Since 1952, 20 datasets have been generated through 17 studies in an attempt to describe the sources and importance and/or use of information about pharmaceuticals by physicians. The authors review the findings of the studies and subject them to three sequentially relevant, but different, meta-analytic procedures. The results of these analyses indicate significant changes in the sources and importance of various commercial/noncommercial and personal/nonpersonal information as they relate to physicians' prescribing behavior. Those changes over time have specific implications for marketers of pharmaceuticals.

Advertising↗
PubMed1991

Employee experiences with early return to work programs.

Those who administer early return to work programs should be aware of the differing needs of workers who have suffered on the job injuries. Many employees are able to move through a program without problems; others are at risk for poor outcomes. Those workers most in need of assistance should an on the job injury occur are those who have relatively poor satisfaction in the job in which injury occurred, a longer period of disability due to injury, aggravation of injury while on the early return to work program, or perceptions of little support from within the company. Particular attention to certain aspects of programs (identification of workers at risk for poor outcome, design of modified jobs, and communication of concern for workers) may enhance favorable response to early return to work programs.

Accidents, Occupational↗
PubMed1990

Hypophysectomy and growth hormone replacement effects on multiple immune responses in rats.

Male Fischer 344 rats were hypophysectomized at 8 weeks of age. At 10 weeks of age, one group of these animals was treated with 40 micrograms of bovine somatotropin given daily sc for 13 days. A third group was sham-operated and injected daily with saline. All animals were sacrificed on Day 14 and multiple immune responses were assessed in each rat. Immune responses assayed included specific antibody production and delayed-type hypersensitivity (DTH) reactions to antigen, natural killer (NK) cell cytotoxicity, and production of interleukin 2 (IL2). Body and lymphoid organ weights, hematologic parameters, and spleen cell numbers were also recorded. Hypophysectomized (Hx) rats had reduced antibody synthesis, DTH reactions, NK cytotoxicity, IL2 (or IL4) production, body and organ weights, rbc counts, packed cell volumes, and hematocrits compared to sham-operated controls. White blood cell counts were elevated. Treatment of Hx animals with GH restored antibody and IL2 production and thymic weights and partially restored DTH reactions. These data indicate the pituitary is important in maintaining normal immune functions, and part of this effect may be via production of GH. It is postulated that GH may act through stimulation of IL2 (or IL4).

Animals↗
PubMed1990

The 4 mM blood lactate level as an index of exercise performance in 11-13 year old children.

The aim of this study was to assess the use of the 4 mM blood lactate level measured during incremental treadmill exercise as an indicator of exercise performance in 11-13 year old children. Fifty girls and 53 boys (means age 12.2 +/- 0.6 years) gave informed consent to participate in the study. The children completed a discontinuous, incremental running test on a motorized treadmill. A 1 min pause separated the 3 min exercise stages during which time duplicate capillary blood samples were taken for immediate assay of whole blood lactate concentration. Cardiorespiratory variables were measured continuously during exercise using a computerized on-line system. Mean values for peak oxygen uptake were 48 +/- 7 ml kg-1 min-1 and 42 +/- 7 ml kg-1 min-1 in boys and girls respectively. The exercise intensity corresponding to a blood lactate concentration of 4 mM was interpolated from plots of % peak oxygen uptake vs blood lactate and was reached at 91 +/- 7% peak oxygen uptake in both boys and girls. The results indicate that children can exercise at intensities close to their peak oxygen uptake without accumulating high levels of blood lactate and the use of the 4 mM blood lactate level to assess and monitor exercise performance in children of this age may therefore be inappropriate.

Adolescent↗
PubMed1990

Molecular analysis of in vivo hprt mutations in human T lymphocytes. V. Effects of total body irradiation secondary to radioimmunoglobulin therapy (RIT)

The hprt (hypoxanthine guanine phosphoribosyltransferase) T cell cloning assay was used to detect in vivo mutations in T lymphocytes of individuals receiving radioimmunoglobulin therapy (RIT). A total of 28 patients receiving 131I and/or 90Y-labeled antiferritin antibodies was studied. Mutant frequencies for patients were clearly much higher than for historic non-treated controls (median 68.0 X 10(-6) for patients versus a median of 6.8 X 10(-6) for 115 controls). There was a good correlation of mutant frequency with initial activity of RIT (rlinear = 0.68, rquadratic = 0.76; P less than 0.05) although the correlation of mutant frequency with total activity after several rounds of treatment was poor (R = 0.18). Molecular studies of the hprt mutants demonstrated that a much higher proportion of mutations occurring in RIT treated patients had gross structural alterations of the hprt gene (33%) than did mutations occurring in controls (15%). There was a good correlation (r = 0.72) of mutants with gross alterations and total RIT activity. T cell receptor gene studies demonstrated that most of the mutants (92%) represented independent in vivo mutations, which is similar to previous findings with background mutations in non-irradiated individuals. These studies demonstrate the usefulness of the hprt T cell cloning assay for studies of in vivo human somatic cell gene mutations resulting from ionizing radiation.

Adult↗