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Biomedical subjects

D A Bradley

Publications and source records attributed to D A Bradley.

At least 19 recordsLinked to original sources
PubMed2005

Infliximab in chronic ocular inflammation.

OBJECTIVE: Infliximab is a chimeric antibody which binds tumor necrosis factor (TNF). It is effective in several chronic inflammatory conditions, including sarcoidosis. METHODS: We report our experience with infliximab in chronic ocular inflammation as part of a retrospective review of all patients treated for chronic inflammatory ocular conditions seen over a 2-year period at our institution. RESULTS: 14 patients with various underlying ocular conditions were treated during the previous two years including patients with sarcoidosis (7), Crohn's disease (2), birdshot choroiditis (2), idiopathic disease (2), Volt-Koyanagi-Harada (1) and Behçet's disease (1). All patients had persistent inflammation despite systemic immunosuppressive agents and all but one patient experienced marked improvement in ocular inflammation with infliximab. One patient was non-compliant and non-evaluable; four patients, who had previously received etanercept with either no response (3 patients) or subsequent relapse (1 patient), responded to infliximab. CONCLUSION: Infliximab is an effective therapy in chronic inflammatory eye disease, especially when related to sarcoidosis.

Adult↗
PubMed2004

X-ray fluorescence and energy dispersive x-ray diffraction for the quantification of elemental concentrations in breast tissue.

This paper presents improvements on a previously reported method for the measurement of elements in breast tissue specimens (Geraki et al 2002 Phys. Med. Biol. 47 2327-39). A synchrotron-based system was used for the detection of the x-ray fluorescence (XRF) emitted from iron, copper, zinc and potassium in breast tissue specimens, healthy and cancerous. Calibration models resulting from the irradiation of standard aqueous solutions were used for the quantification of the elements. The present developments concentrate on increasing the convergence between the tissue samples and the calibration models, therefore improving accuracy. For this purpose the composition of the samples in terms of adipose and fibrous tissue was evaluated, using an energy dispersive x-ray diffraction (EDXRD) system. The relationships between the attenuation and scatter properties of the two tissue components and water were determined through Monte Carlo simulations. The results from the simulations and the EDXRD measurements allowed the XRF data from each specimen to be corrected according to its composition. The statistical analysis of the elemental concentrations of the different groups of specimens reveals that all four elements are found in elevated levels in the tumour specimens. The increase is less pronounced for iron and copper and most for potassium and zinc. Other observed features include the substantial degree of inhomogeneity of elemental distributions within the volume of the specimens, varying between 4% and 36% of the mean, depending on the element and the type of the sample. The accuracy of the technique, based on the measurement of a standard reference material, proved to be between 3% and 22% depending on the element, which presents only a marginal improvement (1%-3%) compared to the accuracy of the previously reported results. The measurement precision was between 1% and 9% while the calculated uncertainties on the final elemental concentrations ranged between 10% and 16%.

Adipose Tissue↗
PubMed2002

Concentrations of Fe, Cu and Zn in breast tissue: a synchrotron XRF study.

An x-ray fluorescence system with a synchrotron radiation source was used to quantify the levels of iron, copper and zinc in breast tissue specimens. Healthy tissue and breast carcinomas were investigated as an aid to understanding the mechanisms of breast cancer and as a possible complementary diagnostic tool. Eighty samples were measured in total. Twenty samples were matched pairs, i.e. 20 tumour samples with 20 corresponding healthy tissue specimens taken at a distance from the tumour. The remaining 40 samples consisted of 20 excised tumours and 20 healthy specimens from breast reduction surgeries. The levels of the elements of interest were quantified via calibration models constructed using the XRF response from standard solutions. The statistical analysis of the results indicates elevation of the levels of all three trace elements in the tumours. The effect is more prominent for copper and zinc while the contrast between healthy and diseased tissue is enhanced when comparing the independent specimens rather than the paired samples. Specifically, the ratio of mean tumour to mean healthy concentration for iron was 1.6 for the paired samples and 2.7 for the non-paired samples. The ratios describing copper content were 3.1 for paired and 3.6 for non-paired samples while for zinc they were 2.4 and 4.4 respectively.

Breast↗
PubMed2001

An attributable cost model for a telecare system using advanced community alarms.

We have developed an attributable cost model for a city-based telecare scheme involving 11,618 community alarm users. The equipment was assumed to cost 500 Pounds-1000 Pounds per installation, compared with 175 Pounds for the current system. Because of the significant additional capital cost of the proposed system, it would be necessary to borrow to finance it. For example, if the home equipment cost 500 Pounds per unit, an additional 2.2 million Pounds would be required. Nonetheless, it would be possible to achieve a return on the investment after 10 years. The principal savings would arise from reduced hospital bed costs and reduced residential care. The model suggests that the financial benefits of the proposed system would occur in the ratio of 4% to the local authority housing department, 43% to the National Health Service and 53% to the residential care provider.

Aged↗
PubMed2000

Oim mice exhibit altered femur and incisor mineral composition and decreased bone mineral density.

To investigate the role of the pro alpha 2(I) collagen chains of type I collagen in mineralization we used the oim (osteogenesis imperfecta model) mouse as our model system. The oim/oim mouse (homozygous for a null mutation in its COL1A2 gene of type I collagen) fails to synthesize functional pro alpha 2(I) collagen chains, synthesizing only homotrimers of pro alpha 1(I) collagen chains. To evaluate the role of pro alpha 2(I) collagen in type I collagen structure/function in mineralized tissues, we examined age-matched oim/oim, heterozygous (oim/+), and wild-type (+/+) mouse femurs and incisors for mineral composition (calcium, phosphorus, magnesium, fluoride, sodium, potassium, and chloride) by neutron activation analyses (NAA), and bone mineral content (BMC) and bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) in a longitudinal study (7 weeks to 16 months of age). NAA demonstrated that oim/oim femurs had significant differences in magnesium, fluoride, and sodium content as compared with +/+ mouse femurs, and oim/oim teeth had significant differences in magnesium content as compared to +/+ teeth. The ratio of calcium to phosphate was also significantly reduced in the oim/oim mouse femurs (1.58 +/- 0.01) compared with +/+ femurs (1.63 +/- 0.01). DEXA demonstrated that oim/oim mice had significantly reduced BMC and BMD as compared to oim/+ and +/+ mice. Serum and urine calcium, magnesium, and phosphorus levels, and Ca(47) absorption across the gut were equivalent in oim/oim and +/+ mice, with no evidence of hypercalciuria. These studies suggest that the known decreased biomechanical properties of oim/oim bone reflect both altered mineral composition as well as the decreased BMD, which further suggests that the presence of alpha2(I) chains plays an important role in mineralization.

Absorptiometry, Photon↗
PubMed2000

Do community alarm users want telecare?

Previous surveys have suggested that community alarm users are in general satisfied with the service provided. However, there is also evidence that users would like additional options that could be provided by a telecare system. Inner-city users of community alarms were consulted about their current systems and the extension of these to incorporate telecare options. The users lived in 160 homes in three multistorey apartment blocks. The average age of the 176 users surveyed was 76 years. Seventy-seven per cent of users were interested in automatic fall detection, 68% in lifestyle monitoring, 57% in telemedicine and 46% in videoconferencing. Nineteen of those interviewed (11%) did not want any of the suggested enhancements. The survey showed that elderly people are not technophobes, since 58% possessed either a microwave oven or a video-recorder, and also showed that the majority were prepared to accept new technologies that would support their independence.

Aged↗
PubMed2000

Safety and risk issues in using telecare.

The increasing adoption of technology to support independent living at home through the extended use of community alarms and, ultimately, second-generation telecare systems poses some safety problems. The implications of any failure of the technology must be addressed in order to provide a safe and reliable care service. The risks of using home-based technology can be assessed by standard techniques under three categories: environmental factors; human factors; and technological factors. A safety classification system for telecare devices is proposed leading to a range of design guidelines which represent good practice. An example of the use of these design principles is a prototype second-generation telecare system, MIDAS, which is currently undergoing trials. In order to reduce the risks associated with device failure, the system incorporates distributed intelligence, built-in self-testing and redundancy. Potentially hazardous situations can therefore be controlled.

Accidental Falls↗
PubMed1999

Performance assessment of patient dosimetry services and X-ray quality assurance instruments used in diagnostic radiology.

Experiences of the Regional Radiation Physics and Protection Service (RRPPS) in performance assessment of diagnostic X-ray QA instrumentation and on-patient dosemeters are recounted. Issues relating to the provision of realistic and reproducible reference conditions for calibrated X-irradiations are considered and summary statistics from test measurements of dose and kVp meters are provided. For both dose and kVp meters it is indicated that as many as 25% of instruments used in routine use in the U.K. may require some adjustment before they can truly be said to be performing as the manufacturer intended. Results from intercomparison exercises for patient dosimetry services are also discussed. It is apparent that, for those centres participating in the exercise, dose assessments are generally being obtained to within a bias and a relative standard deviation of less then 10%.

Female↗
PubMed1999

The feasibility of a sensitive low-dose method for the in vivo evaluation of Fe in skin using K-shell x-ray fluorescence (XRF).

An x-ray fluorescence (XRF) system designed for monitoring of skin Fe concentrations has been performance tested for use on patients treated for beta-thalassaemia. The essentials of the system are: a collimated x-ray tube operated at 20 kV and 20 mA; energy selection of the x-ray beam by means of a Cu K-edge filter; use of skin phantoms containing concentrations of Fe in the range 10 to 100 parts per million (ppm); and a high-purity germanium detector placed at 90 degrees to the incident beam. For a Cu K-edge filter of 0.15 mm thickness a quasi-monoenergetic beam of approximately 8.4 keV is obtained which is close to the absorption edge of Fe (7.11 keV). For a real-time counting period of 400s the systemis capable of detecting Fe concentrations of 15+/-2 ppm at a skin dose of the order of 5 mSv. This level of Fe is at the higher end of the normal range found in the skin. In using the same system and operating parameters, measurements on a sample of ferritin obtained from a rat's liver yield an Fe concentration of 36+/-3 ppm for a measurement time of 500 s; this can be compared with suppliers' data indicating an Fe level of 36 ppm.

Animals↗
PubMed1999

The monitoring of contaminated impervious planar surfaces.

The responses of several types of surface contamination monitor have been investigated for three typical working surfaces contaminated by three radionuclides commonly used in diagnostic or analytical biomedical applications. Of the three radionuclides, 99mTc is an intermediate-energy gamma emitter, 125I decays by electron capture, emitting low-energy x-rays, and 32P is a moderate-energy beta emitter. For each radionuclide monitored values have generally been found to be within 30% of projected response, this being based on calibrations which make use of standard radionuclide sources and conditions. The several types of contaminated non-absorbent surface that have been investigated produce monitored values which for a given type of monitor and radionuclide cannot be differentiated from each other.

Equipment Contamination↗
PubMed1999

Future systems for remote health care.

As the number of elderly people in society increases, the use of technology to support the care system is being examined. However, there is no agreed model of a technology-based health-care system that fully integrates the technical and social aspects to meet the needs of both clients and care providers. This paper examines a possible model from the perspective of both the client and the service provider, and estimates the costs, and hence the potential savings, associated with the introduction of a health-care system based on this model. Cost data are presented in the context of an installation as might be anticipated within a city such as Birmingham, UK. Installation costs of an advanced telecare system would be higher than the set-up costs of conventional systems. Expected savings in control centre costs and emergency services costs would be small. However, a reduction in the average annual length of hospital stay by one day and a reduction in the proportion of elderly people being treated in hospital from 32.4% to 32.0%, directly as a result of the use of advanced telecare, would produce significant savings. A financing scheme with a 5-year or 10-year repayment period would then be financially viable for a 10,000-home advanced telecare system.

Delivery of Health Care↗
PubMed1998

A systems approach to achieving CarerNet--an integrated and intelligent telecare system.

The system requirements for an integrated telecare system are presented by using a modification of the CORE methodology. The resulting system model uses viewpoint analysis to establish the needs and requirements of both the client and the care providers within a system context and discusses the implications for a user-centered, technology-based solution referred to as "CarerNet." The implementation of CarerNet is considered in terms of the enabling technologies required within the local environment of the client and identifies the monitoring, networking requirements, and system intelligence necessary to the provision of a comprehensive telecare service. A hypothetical case study based on patient aftercare following discharge from the hospital is presented to illustrate the points discussed.

Monitoring, Physiologic↗
PubMed1997

Discriminant analysis of normal and malignant breast tissue based upon INAA investigation of elemental concentration.

Discriminant analysis of six trace element concentrations measured by instrumental neutron activation analysis (INAA) in 26 paired-samples of malignant and histologically normal human breast tissues shows the technique to be a potentially valuable clinical tool for making malignant-normal classification. Nonparametric discriminant analysis is performed for the data obtained. Linear and quadratic discriminant analyses are also carried out for comparison. For this data set a formal analysis shows that the elements which may be useful in distinguishing between malignant and normal tissues are Ca, Rb and Br, providing correct classification for 24 out of 26 normal samples and 22 out of 26 malignant samples.

Breast↗
PubMed1997

Elevated trace element concentrations in malignant breast tissues.

In vitro neutron activation analysis (NAA) was performed on malignant and adjacent normal tissue from 46 human female breast tumours. The objective was to investigate the chemical environment of the tissues within which microcalcifications develop and to develop a method for discrimination between malignant and normal breast tissue. The elements Al, Br, Ca, Cl, Co, Cs, Fe, K, Mn, Na, Rb and Zn were significantly higher in the cancer tissues (all p < 0.001; except for Co, p < 0.003, Wilcoxon signed-ranks test). In addition, a significant correlation (0.80, Spearman rank correlation) was found for Rb and Zn in tumour tissues. Present results are supported by the findings of others. The relevance of elevated concentrations of these elements in cancer breast tissue remains a matter of conjecture. Evidence suggests that there is a connection both with increased cellular activity and blood supply and the formation of microcalcifications in malignant breast tissues. This study suggests an association between the elemental composition of breast tissues and the formation of breast particles. That is, elevations of elemental concentration and clustered calcifications in breast are possibly related.

Adult↗
PubMed1996

Hepatic spiral CT in children: scan delay time-enhancement analysis.

PURPOSE: To compare the effect of different time delays between contrast administration and the start of spiral CT scanning on hepatic enhancement in children. MATERIALS AND METHODS: Forty-five children (2-9 years old, mean 6 years) with no evidence of hepatic disease were examined with spiral CT. Sequential spiral scans through the entire liver were performed following a uniphasic injection of nonionic contrast medium. In group 1 scanning started at 80 % of the contrast injection time, in group 2 scanning started at 100 % of injection time, and in group 3 scanning started at 150 % of injection time. Mean hepatic, aortic, and inferior vena caval enhancement were determined using regions-of-interest measurements. RESULTS: Mean hepatic enhancement was 41.4, 47.0, and 40.6 HU for the 80 %, 100 %, and 150 % injection times, respectively. Enhancement was significantly greater in the 100 % injection time group (p < 0.05). A mean aortocaval difference of greater than 10 HU was present in all examinations. CONCLUSION: Our results suggest that delaying the initiation of spiral CT scanning until the completion of the contrast injection increases hepatic enhancement in children. These data should help to improve the quality of hepatic spiral CT in pediatric patients.

Child↗
PubMed1996

Microcalcification clustering parameters in breast disease: a morphometric analysis of radiographs of excision specimens.

X-ray microradiography of surgically excised breast specimens offers the possibility of morphological characterization of calcifications. When combined with digital imaging techniques there exists added potential for obtaining valuable basic quantitative morphometric information regarding differences between microcalcifications in tissues exhibiting evidence of fibrocystic change, benign and malignant tumours. A total of 157 excised breast specimens from 84 patients were microradiographed using a Softex Super Soft X-ray unit and Kodak AA high resolution industrial film. A Quantimet 570C image analysis system was used to digitize and analyse the microradiographs. Of the 157 microradiographs, 51 (from 30 patients) revealed microcalcification clusters. The existence of significant differences between the three identified categories of tissue were indicated by clustering parameters. These included the number of particles per cluster, area of clusters, maximum distance to nearest neighbour, and geometric mean distance to nearest neighbour. The distribution pattern index (DPI), another of the clustering parameters used in this study, has been observed to be a particularly powerful discriminator. The value for fibrocystic change was found to be significantly smaller (0.514) than that for benign tumour (0.796) whilst that for benign tumour was observed to be significantly larger than that for malignant tumour (0.604) at a p-value of less than 0.05 (Kruskal-Wallis one-way analysis of variance).

Adolescent↗
PubMed1994

Tibial lead determination by 99Tcm radiopharmaceutical x-ray fluorescence.

The feasibility of measuring tibial lead concentration by x-ray fluorescence with an internal 99Tcm labelled bone-seeking radiopharmaceutical was investigated using phantoms containing known values of lead concentration and 99Tcm activity. The minimum detectable concentration (MDC) at two standard deviations based on the counts in the Kalpha1 peak of 10.9 microg Pb ml(-1) was estimated to correspond to an MDC for an individual within a range of approximately 8-15 microg Pb (g bone mineral)(-1) if the counts from all four K x-ray peaks were included. Due to its much greater dose compared to an external source, the MDC of this internal source technique would have to be reduced before it could be used for measurements of occupationally or environmentally exposed individuals other than as an adjunct for a patient undergoing a bone scan. Methods of achieving such a reduction include increasing the acquisition time and the number of HPGE detectors, and optimizing the design of their collimators.

Adult↗