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Biomedical subjects

A Appleby

Publications and source records attributed to A Appleby.

At least 19 recordsLinked to original sources
PubMed2001

From blacklist to beacon, a case study in reducing dermatology out-patient waiting times.

At its worst our dermatology department had a waiting list for routine appointments of 57 weeks. As a result we started to lose contract income and consequently were unable to replace a retiring consultant. The service faced fragmentation and loss of the inpatient ward. Using a series of internally planned and driven initiatives it was possible to retrieve the situation. Our efforts were recognized by a national waiting list Beacon award in 1999. This study describes the methods used to increase new patient throughput, reduce demand and hence reduce waiting time for new patient appointments. Change was achieved only when medical, nursing staff, general practitioners, managers and health authorities were involved in the process. The changes needed to be led by a consultant enthusiast and managed effectively. There remains a constantly increasing demand for the service and reducing the waiting list simply invites a further increase in referral. In a resource-limited health care system the provider must be able to limit demand by using agreed referral exclusion criteria in order to balance supply and demand.

Ambulatory Surgical Procedures↗
PubMed2000

High blood cortisol levels and low cortisol receptor affinity: is the chub, Leuciscus cephalus, a cortisol-resistant teleost?

In contrast to the relatively minor intra- and interspecies differences in blood cortisol levels reported for salmonid species, there is a more pronounced distinction between cortisol levels among the Salmonidae and the Cyprinidae, with both basal and stress-induced cortisol levels markedly higher in the latter. This study shows that in the chub, Leuciscus cephalus, a widely distributed European cyprinid, mean blood cortisol levels during stress (1500 ng mL(-1)) exceeded those reported for most other species of fish and, even in unstressed chub, cortisol levels (50-100 ng mL(-1)) were within the range known to cause immunosuppression, growth retardation, and reproductive dysfunction in salmonid fish. The chub appears to be atypical only with respect to plasma cortisol levels; the levels of plasma glucose and plasma lactate in unstressed and stressed chub are similar to those reported for other species. Plasma levels of 11-ketotestosterone in males and 17beta-estradiol in females are lower than those reported for salmonids but similar to those reported for other cyprinid species and display clear stress-induced reduction. Comparative analysis of the binding characteristics of the trout and chub gill cortisol receptor revealed that the total number of binding sites in gill tissue for each species was similar (B(max); approximately 50-100 fmol mg(-1) protein). However, the affinity of the binding site for cortisol displayed an eightfold difference between the species (rainbow trout: K(d) approximately 6 nM; chub: K(d) approximately 50 nM). Therefore, the potentially adverse effects of high circulating levels of cortisol found both at rest and under conditions of stress in chub may be offset by the lower affinity of the cortisol receptor, rather than the abundance of target-tissue receptor sites. This strategy is similar to that reported for some glucocorticoid-resistant rodents and New World primates.

Animals↗
PubMed1999

CCD imaging for optical tomography of gel radiation dosimeters.

Several investigations have been carried out by a number of researchers over the past few years to evaluate the utility of imaging gel dosimeters for the three-dimensional measurement of radiation fields. These have been proposed to be of particular value in mapping radiation dose distributions associated with emerging and complex approaches to cancer treatment such as conformal (CRT), intensity modulated (IMRT), "gamma knife," and pencil beam radiotherapies. Imaging of the gels has been successfully accomplished with clinical MRI units and via laser-based optical scanning. However, neither of these methods is generally accessible to all potential users, limiting the broader study and implementation of this valuable tool. We report here the design, methodology, and results of a preliminary study carried out to evaluate the utility of a new, inexpensive, and simplified approach to tomographic imaging of gel radiation dosimeters. For the purpose of this initial investigation, an array of liquid scintillation vials was prepared, containing a ferrous sulphate xylenol orange (FSX) gelatin formulation. The FSX formulation undergoes a change in optical absorption characteristics following irradiation, and the resulting color change can be observed visually. The vials were irradiated individually to different doses. Three-dimensional imaging was accomplished by tomographic reconstruction from two-dimensional optical images acquired using a diffuse, fluorescent light source, a digital charge-coupled device camera, single-photon-emission-computed tomography software, and other simple components designed by the authors. The resulting transverse images were evaluated through a region-of-interest (ROI) analysis to obtain the average change in image density in each vial as a function of radiation dose. These measured ROI values were subjected to a linear regression analysis to fit them to a straight line, and to determine the goodness of fit. Results from multiple imaging trials are compared. The correlation coefficients obtained are typically on the order of 0.98, and the p value from analysis of variance is approximately 0.05, indicating a linear and reproducible response for the dosimeter formulation and imaging system.

Dose-Response Relationship, Radiation↗
PubMed1996

X-ray beam energy, scatter, and radiation risk in chest radiography.

Effective doses for patients undergoing chest radiography were computed utilizing updated weighting factors, published organ doses and measured entrance doses. The effective dose decreases with beam energy (kVp) and reaches a minimum value after 100 kVp, with values when a grid is used (6.90 microSv) being 145% higher at this energy than when no grid is used (2.82 microSv). The uncertainties associated with derivation of the tissue weighting factors are shown not to affect the point at which risk is minimized. Use of the effective dose as the measure of risk does not require special treatment of the remainder tissue as with use of effective dose equivalent. The effective dose required for radiographs of constant optical density was examined to incorporate the behavior of the detector's response to energy and compare results to previous work where exit dose was held constant. The effective dose at 120 kVp with a grid (6.84 microSv) is compared to an estimate of that associated with the current kVp distribution (14.55 microSv). Since image quality is enhanced by the grid, its use in conjunction with a beam energy of 120 kVp could maximize the benefit/risk ratio in chest radiography and should be considered for universal implementation. Such adoption could reduce the population risk compared to current practice.

Humans↗
PubMed1989

Radiation chemistry of high-energy carbon, neon, and argon ions: molecular hydrogen yields.

Molecular hydrogen yields are reported for cupric sulfate solutions irradiated with high-energy heavy ions. The data are sparse but appear to be consistent with expectations from current theoretical models of the track structure of these ions. By considering these data in conjunction with previously published yields from other systems, estimates of the total water decomposition yields, G'-H2O, have been made.

Argon↗
PubMed1986

Radiation chemistry of high-energy carbon, neon, and argon ions: hydrated electron yields.

Neutral aqueous solutions of sodium nitrate/ethanol have been irradiated with high-energy heavy ions from the Berkeley Bevalac. Yields of nitrite have been used to estimate G values for the hydrated electron as a function of the residual range of these ions. Values of G(e-aq) have been estimated as a function of ion energy by adjusting the measured values for the effects of heavy ion fragmentation.

Argon↗
PubMed1985

Radiation chemistry of high-energy carbon, neon, and argon ions: hydroxyl radical yields.

Chemical yields of H2O2 have been measured from aerated aqueous solutions of bromide and of formate irradiated at various pHs and solute concentrations with high-energy ions from the Berkeley Bevalac. Hydroxyl radical yields have been deduced from these data as a function of beam penetration into the solutions. By taking fragmentation of the primary ions into account, estimates of the instantaneous Gi OH values for the primary beams as a function of their energy have been made.

Argon↗
PubMed1983

Familial intracranial aneurysm and infundibular widening.

We present details of a family who show a high incidence of both intracranial saccular aneurysm and infundibular widening. Familial aneurysms are compared with aneurysms occurring in the general populations with regard both to site distribution and age of onset of symptoms. The possibility of infundibular widening being preaneurysmal is further discussed. It is highly likely that the mode of inheritance in familial cases is one of dominance.

Adolescent↗
PubMed1976

The empty sella syndrome.

The empty sella syndrome (ESS) presents a varied clinical and radiographic picture. It may remain asymptomatic or may stimulate an intrasellar growth thereby causing diagnostic and therapeutic problems. An air encephalogram (AEG) is required for diagnosis. The purpose of this paper is to review the clinical and radiological features of the ESS and to discuss the pathogenetic mechanisms involved.

Humans↗