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J Bedford

Publications and source records attributed to J Bedford.

At least 19 recordsLinked to original sources
PubMed2004

The use of gel dosimetry for verification of electron and photon treatment plans in carcinoma of the scalp.

In recent years there has been a large amount of research into the potential use of radiation sensitive gels for three-dimensional verification of clinical radiotherapy doses. In this paper we report the use of a MAGIC gel dosimeter (Fong et al 2001 Phys. Med. Biol. 46 3105) for the verification of a specific patient's radiation therapy dose distribution. A 69-year-old male patient presented with a squamous cell carcinoma extending approximately 180 degrees across the top of the scalp (anterior to posterior) and from just over midline to 90 degrees left of the skull. The patient's treatment was commenced using two electron fields. For gel dosimetry, phantoms were produced in which the outer surface spatially corresponded to the outer contours of the patient's anatomy in the region of irradiation. The phantoms were treated with either electrons or intensity modulated radiation therapy (IMRT) with photons. The results identified a hot spot between the matched electron fields and confirmed the more homogeneous dose distribution produced by the IMRT planning system. The IMRT plan was then clinically implemented. The application of a clinical dose to a phantom shaped to a specific patient as well as the ability to select a slice at will during phantom imaging means that gel dosimetry can no longer be considered to simply have potential alone, but is now in fact a useful dosimetric tool.

Aged↗
PubMed2004

Eating attitudes across age and gender groups: a Canadian study.

OBJECTIVE: The purpose was to examine the eating attitudes across gender and age groups. METHOD: The study included 343 individuals over 18 years of age (range: 18 to 94 years; mean 48 +/- 22), who were divided into 3 age categories: 18 to 34 years, 35 to 64 years and 65 years and above with a distribution of 35% (119), 37% (128) and 28% (97) respectively. The participants completed a background questionnaire and the Eating Attitudes Test (EAT-26). RESULTS: A total of 30 participants (8.7%) scored above the cut-off point on the EAT-26 which is indicative of potential eating disturbances. Only statistically significant gender differences were observed in the total EAT-26 scores. Factor analysis revealed three subscales of EAT-26, food preoccupation, image preoccupation, and external focus or social pressure, with acceptable level of reliability and these were used for age and gender comparison. Age and gender differences were observed in the food and image preoccupation subscales only. DISCUSSION: Although EAT-26 is widely used in clinical and non-clinical population, age and gender comparisons have not been made in a population-based sample. Use of the subscales of eating attitudes should help health professionals better identify those at risk for eating disturbances and provide the opportunity for intervention.

Adolescent↗
PubMed2000

Influenza vaccination in asthma: a primary care experience.

BACKGROUND: Despite the recommendation of the Department of Health that patients with asthma receive annual vaccination against influenza, uptake remains unsatisfactory with many patients suspicious that vaccination is harmful. AIM: To examine the effect of influenza vaccination on asthmatic patients typical of a general practice setting. METHOD: A multicentre study with 56 patients participating from 14 practices in England and Scotland. Patients completed peak expiratory flow rate (PEFR) and symptom diaries for two weeks before and two weeks after influenza vaccination. RESULTS: A non-significant fall in baseline PEFR of 10.5 l/min, from an average of 431.5 l/min, was observed after influenza vaccination, representing a 2% change from baseline. A significant increase in night time reliever use of 0.17 puffs per night (P < 0.01) was found. Non-significant increases in number of nights per week with sleep disturbed due to asthma, severity of night-time and day-time symptoms, and day-time reliever use were also noted. CONCLUSION: Influenza is an important cause of morbidity and mortality in asthmatics. This study confirms the safety of influenza vaccination in patients with asthma typical of those seen in primary care. General practitioners need not hesitate in recommending this valuable intervention to their asthmatic patients and should consider ways in which uptake can be improved.

Adolescent↗
PubMed1998

A versatile image analysis approach for simultaneous chromosome identification and localization of FISH probes.

Modern cytogenetic techniques, such as comparative genomic hybridization (CGH) and the multi-color fluorescence in situ hybridization (FISH) techniques of multiplex fluorescence in situ hybridization (M-FISH) and spectral karyotyping (SKY), require a coordinated banding analysis to maximize their usefulness. All of the methods currently used, including Giemsa (G-) banding, Alu banding, and 4',6-diamidino-2-phenyl-indole (DAPI) banding, have serious drawbacks. A simple and effective method to band chromosomes concurrently with FISH is needed. To address this problem, we stained chromosomes with DAPI and chromomycin A3, and then used an image analysis program to generate banding by dividing the image taken with a DAPI excitation filter by the image taken with a chromomycin A3 excitation filter. The result was a metaphase spread in which the chromosomes possessed a banding pattern characteristic of R-banding. The image analysis program was then used to generate linescans of pixel intensity versus relative position along the length of chromosomes that were banded using this technique, which we have called D/C R-banding. Each chromosome in a genome was represented by a characteristic scan profile, which was unaffected by FISH signals. Reference linescans were prepared by karyotyping D/C R-banded chromosomes for a given species, and then drawing lines along the length of the known chromosomes. The linescans were combined into a spreadsheet database, which was linked by dynamic data exchange to the image analysis program and normalized for length and intensity. The linescan of an unknown chromosome was then transferred to the spreadsheet, where it was normalized for length and intensity and overlaid on the linescans of each chromosome in the genome. Unknown chromosomes were identified by comparison of their graphs with graphs in the standardized reference genome. We have used this approach to create reference linescan karyotypes of several species, and to identify chromosomes on which FISH was performed.

Animals↗
PubMed1994

Topographic mapping of the pattern onset evoked magnetic response to stimulation of different portions of the visual field.

Visual evoked magnetic responses to pattern onset/offset stimuli were recorded in 5 normal subjects. The outgoing and ingoing magnetic currents were seen maximally over the contralateral visual cortex to the half field stimulated in the majority of subjects. The distribution of magnetic currents with half field stimulation would be consistent with a dipole on the midline with the positive end pointing laterally. Quadrantic stimuli produced dipoles which would be consistent with a vector sum of dipoles situated, in the case of upper quarter field stimulation, in the lingual gyri on the floor of the calcarine fissure. Lower quadrantic stimulation produced a vector consistent with dipoles on the cuneal gyrus and on the ceiling of the calcarine fissure producing a resultant vector. The use of paired octant stimuli to improve localisation was demonstrated on both right left and upper and lower half fields.

Adult↗
PubMed1993

Putative determinants of the cellular response to hyperthermia.

Recently, it has been demonstrated that two different thermal resistant states found in Chinese hamster cells, one transient, associated with thermotolerance, and the other permanent, associated with the increased expression of the cognate member of the hsp 70 family, are characterized by faster recovery from heat-induced perturbations in several cellular processes (Laszlo 1992b). These processes include total cellular protein and RNA synthesis, the localization of hsp70, the organization of vimentin, and the protein composition of the nucleus. In the present study, the recovery from heat-induced perturbations in cellular physiology was extended further to two more types of Chinese hamster cells: permanently heat resistant cells in which thermoresistance is associated with the overexpression of hsp27 and heat-sensitive cell lines. When the heat-resistant hsp27 transfected cell lines were compared with the control wild-type cell line, the recovery of protein synthesis from heat-induced inhibition was similar in the normal and hsp27 transfected cells, while the recovery from heat-induced inhibition of total RNA synthesis and the recovery from heat-induced increased association of hsp70 with nuclei were both more rapid in the hsp27 transfected cell lines. In the permanently heat-sensitive cell lines, the kinetics of recovery from heat-induced inhibition of protein synthesis did not correlate with the heat sensitive state. However, delays in the recovery from heat-induced alterations in total cellular RNA synthesis and from heat-induced excess nuclear association of hsp70 were associated with the heat-sensitive state. Overall, these results suggest that the kinetics of recovery from heat-induced alterations in total cellular RNA synthesis and the localization of hsp 70 are putative candidates for being determinants of the cellular response to hyperthermia, and thus have the potential to form the basis of predictive assays for use in conjunction with clinical hyperthermia.

Adaptation, Physiological↗
PubMed1990

A sensitive radioimmunoassay measuring endothelin-like immunoreactivity in human plasma: comparison of levels in patients with essential hypertension and normotensive control subjects.

1. A radioimmunoassay has been developed for measuring endothelin-like immunoreactivity in human plasma using an antibody raised against endothelin-1 which also cross-reacts with big endothelin-1 and endothelin-2 but not endothelin-3. 2. The sensitivity of the assay was 1 fmol/tube with inter- and intra-assay coefficients of variation of 13% and 9%, respectively. Cross-reactivity with endothelin-3 and non-endothelin peptides was less than 1%. 3. Endothelin-like immunoreactivity was present in the plasma of hypertensive patients (n = 25) at a concentration of 5.7 +/- 0.5 pmol/l (mean +/- SEM), which was not significantly different from that of age-matched control subjects (5.1 +/- 0.5 pmol/l). At these levels, endothelin-1 is unlikely to function as a circulating hormone. 4. Within the normotensive group, the concentration of endothelin-like immunoreactivity in plasma was positively correlated with mean arterial blood pressure, but in hypertensive patients it showed a significant negative correlation.

Adult↗
PubMed1988

Basic radiobiology.

Experimental studies of the biological effects of radiation were started soon after the discoveries of x-rays in 1895, but there is still much that is not known. This article includes some research objectives that are essentially pragmatic in nature, intended to support and improve the current practice of radiotherapy, but the central thrust is the understanding of the mechanisms involved in the biological effects of radiation at the cellular and molecular levels. The article was written by a consortium of scientists and suffers inevitably from the drawback that writing styles are inconsistent, and coverage is not uniform. However, it benefits from the enormous advantage that it reflects the accumulated wisdom and judgment of more than a dozen scientists who, in their own areas of expertise, are recognized as being at the cutting edge of radiation research. The niceties of style and syntax are sacrificed in favor of the quality of the science and the maturity of judgment. The study of DNA damage as a mechanism for cell injury in early- and late-responding tissues, as well as a comparison of DNA damage that leads to lethality, as opposed to transformation and mutagenesis, are key items. The study of cell lethality with cells in culture led to the identification of repair, both sublethal and potentially lethal, as well as the dose-rate effect, and has had a considerable impact on radiotherapy. Future studies should focus on understanding the factors that determine radiosensitivity/radioresistance. A variety of approaches are available, including the study of genetically deficient cell lines from cancer-prone individuals. A parallel approach is the application of the techniques of molecular biology to clone the repair genes in mammalian cells, and to understand genetic defects that alter gene regulation, or to regulate biochemical factors in the cell. Substantial progress has been made in developing in vitro assays for mutagenesis, particularly using hybrids of rodent and human cells. Better methods are needed to study the effects of mutation on gene expression, and sensitive systems are needed that can detect low doses of radiation. Assays of oncogenic transformation, the in vitro counterpart of carcinogenesis, have been used to investigate the oncogenic potential of various types of radiation and chemotherapy agents. Key topics in future will include the investigation of supra-additivity between different agents, the identification and characterization of oncogenes that may be activated by radiation, the development of quantitative assays based on human cells, and further studies involving cell-to-cell communication.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Duplication of part of the long arm of chromosome 1 in marrow cells of a treated case of myelomatosis.

In a case of classical myelomatosis treated with melphalan, a clone of cells with a chromosomal abnormality was found in the bone marrow during remission. There was good reason to think that the hemopoietic cells, rather than plasmacytoma cells, were implicated. Although the clone persisted, no evidence of leukemia developed over a period of observation of 2 yr. The anomaly was interpreted as a duplication of part of the long arm of chromosome 1, which appeared to involve the segment q21 to q31.

Aged↗