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Biomedical subjects

P A Graham

Publications and source records attributed to P A Graham.

At least 19 recordsLinked to original sources
PubMed2002

Influence of a high fibre diet on glycaemic control and quality of life in dogs with diabetes mellitus.

A study was undertaken to evaluate a high fibre diet used in the management of 10 dogs with naturally occurring insulin-dependent diabetes mellitus. Following baseline measurements of health and glycaemic control, the dogs were fed a canned diet containing a blend of insoluble and soluble dietary fibres and were monitored during the ensuing four months. Switching to the high fibre diet was associated with significantly lower mean 24-hour and postprandial plasma glucose concentrations, which were maintained over the study period. The high fibre diet was also associated with significant reductions in plasma concentrations of fructosamine, glycated haemoglobin, free glycerol and cholesterol, and there were significant improvements in dog activity and demeanour. Bodyweight declined during the fourth month of feeding the diet, which is likely to have resulted from underfeeding relative to increased activity. The results indicate that a high fibre diet can significantly improve glycaemic control and quality of life in dogs with diabetes mellitus.

Animals↗
PubMed2001

Patient positioning using detailed three-dimensional surface data for patients undergoing conformal radiation therapy for carcinoma of the prostate: a feasibility study.

PURPOSE: The increasing complexity of radiotherapy highlights the need for accurate setup. This paper assesses the potential of position corrections, derived from the three-dimensional (3D) surface of the patient, in reducing positioning errors in patients undergoing conformal radiation therapy of the prostate. METHODS AND MATERIALS: Twenty patients undergoing conformal radiation therapy for prostate cancer had planning computed tomography (CT) scans and then weekly treatment CT scans over the course of their treatment. Patients were positioned on the CT table using three coplanar tattoo marks used for patient setup on the accelerator. Surfaces were computed from the planning CT (planning surface), and the treatment CT (treatment surfaces). Using a surface matching utility, the planning and treatment 3D surfaces were compared. The prostate was implicitly localized based on surface matching of the external contour and by matching the bony anatomy. The resultant prostate displacement after correction was assessed for the two localization methods. RESULTS: Correcting patient position via the surface comparisons reduced the standard deviation of prostate displacement with respect to the patient isocenter in the lateral and anterior/posterior directions. In the lateral direction, prostate and surface motion was highly correlated (r = 0.96). In the anterior/posterior direction the corrections from the surface data were as effective as those derived from the bony anatomy. CONCLUSION: Detailed surface data can aid the positioning of patients receiving conformal radiation therapy to the prostate by reducing the displacement of the target from the intended treatment position. This study shows that surface corrections can be as effective as those derived from bony anatomy, and may be exploited where definition of bony anatomy is difficult.

Feasibility Studies↗
PubMed2001

Lymphocytic thyroiditis.

Lymphocytic thyroiditis is a common canine condition that can lead to functional hypothyroidism. It is associated with more than 50% of cases of canine hypothyroidism. Evidence in human beings and experimental situations suggests that it is a disease of defective immunoregulation, but specific investigation of the molecular pathogenesis of the naturally occurring disease in dogs has not yet been carried out. The condition is heritable in those breeds that have been studied, and progression to hypothyroidism, if it occurs, can be slow. Factors that influence the progression from subclinical thyroiditis to hypothyroidism in dogs are still to be identified, but excessive iodine intake is an important factor in other species.

Animals↗
PubMed2001

Update on the diagnosis and treatment of disorders of calcium regulation.

The availability of PTH, iCa, PTHrP, and 25OHD assays for evaluation of calcium abnormalities in companion animals has been well received [table: see text] by clinicians and diagnosticians. Use of these assays has heightened awareness that some of these disorders are more common than originally thought. Also, there is added insight of alterations of calcium homeostasis as a consequence of other illness or environmental factors such as diet. Animal counterparts of other disorders of calcium metabolism in people are likely to be identified, and use of these assays should play a significant role. As already emphasized, the foundation of using [table: see text] these assays is first assessing whether the calcium abnormality is of a parathyroid-dependent or parathyroid-independent classification.

Animals↗
PubMed2001

Fructosamine concentration and resistance to natural, predominantly Teladorsagia circumcincta infection.

Fructosamine concentrations reflect protein status and because infection with Teladorsagia circumcincta can induce a relative protein deficiency, we examined the usefulness of fructosamine concentrations as markers of the intensity of infection in naturally infected lambs. Fructosamine concentration was a heritable trait and variation in fructosamine concerntrations was associated with differences in body weight, and a variety of parasitological variables; animals with increased fructosamine concentrations grew more quickly, had increased faecal egg counts in one of the three study years, had decreased pepsinogen concentrations and decreased IgA activity against 4th-stage larvae of T. circumcincta. Fructosamine concentrations were also associated with variation in the subsequent acquisition of nematodes and in the length of adult female T. circumcincta; lambs with increased fructosamine concentrations had fewer nematodes but the mean length of adult female T. circumcincta was longer. Therefore fructosamine concentrations are potentially useful indicators of the severity of nematode infection and may predict magnitude of subsequent infection.

Abomasum↗
PubMed2000

The influence of relative resistance and urea-supplementation on deliberate infection with Teladorsagia circumcincta during winter.

The consequences for lambs of infection over the winter with Teladorsagia circumcincta were quantified by deliberate, trickle infection of selected animals at 7 months of age. Infected and control uninfected animals were each allocated into four groups, relatively resistant animals on a normal diet, relatively resistant animals on an isocaloric diet supplemented with urea, and relatively susceptible animals on the same two diets. Resistance and susceptibility was assessed by faecal egg counts following natural infection during the summer preceding the deliberate infection. During the deliberate infection egg counts remained low and most parasites recovered at necropsy were inhibited larvae. Nonetheless, infection reduced weight gain, decreased albumin and fructosamine concentrations and provoked a noticeable pepsinogen and eosinophil response. As most larvae were inhibited these responses may have been largely a consequence of immuno-inflammatory responses in the host rather than the direct action of parasites themselves. Relatively resistant animals on the supplemented diet allowed fewer larvae to establish and had higher fructosamine concentrations, higher albumin concentrations and decreased pepsinogen responses. Therefore, a combination of relatively resistant sheep and nutritional supplementation appears most efficient at controlling infection.

3-Hydroxybutyric Acid↗
PubMed2000

3D dynamic body surface sensing and CT-body matching: a tool for patient set-up and monitoring in radiotherapy.

Recent advances in radical broad-beam conformal radiotherapy for disease at non-rigid sites suggest that the treatment room set-up of patients should be performed using the CT-plan digital body surface as a reference standard. In effect, the CT-plan surface is a "virtual shell" and should be used as such. To do this requires 3D body surface information to be captured live in the treatment room and then manipulated for comparison with the CT virtual shell. To address this situation, a near real-time prototype opto-electronic dynamic 3D surface sensor has been developed and equipped with a novel software utility for visualizing and matching the disparate surfaces arising from planning and treatment environments. Using the CT virtual shell and height-maps produced by the sensor, a two-phase 3D positioning strategy for patient set-up and monitoring is described. Phase one is an image-guided manual "approach". Phase two is automated "docking" using simulated annealing to determine optimum set-up corrections. The concepts and implementation are illustrated using archival patient data and an anthropomorphic phantom "patient" in a treatment room environment.

Humans↗
PubMed1999

Animation and radiobiological analysis of 3D motion in conformal radiotherapy.

PURPOSE: To allow treatment plans to be evaluated against the range of expected organ motion and set up error anticipated during treatment. METHODS: Planning tools have been developed to allow concurrent animation and radiobiological analysis of three dimensional (3D) target and organ motion in conformal radiotherapy. Surfaces fitted to structures outlined on CT studies are projected onto pre-treatment images or onto megavoltage images collected during the patient treatment. Visual simulation of tumour and normal tissue movement is then performed by the application of three dimensional affine transformations, to the selected surface. Concurrent registration of the surface motion with the 3D dose distribution allows calculation of the change in dose to the volume. Realistic patterns of motion can be applied to the structure to simulate inter-fraction motion and set-up error. The biologically effective dose for the structure is calculated for each fraction as the surface moves over the course of the treatment and is used to calculate the normal tissue complication probability (NTCP) or tumour control probability (TCP) for the moving structure. The tool has been used to evaluate conformal therapy plans against set up measurements recorded during patient treatments. NTCP and TCP were calculated for a patient whose set up had been corrected after systematic deviations from plan geometry were measured during treatment, the effect of not making the correction were also assessed. RESULTS: TCP for the moving tumour was reduced if inadequate margins were set for the treatment. Modelling suggests that smaller margins could have been set for the set up corrected during the course of the treatment. The NTCP for the rectum was also higher for the uncorrected set up due to a more rectal tissue falling in the high dose region. CONCLUSION: This approach provides a simple way for clinical users to utilise information incrementally collected throughout the whole of a patient's treatment. In particular it is possible to test the robustness of a patient plan against a range of possible motion patterns. The methods described represent a move from the inspection of static pre-treatment plans to a review of the dynamic treatment.

Computer Graphics↗
PubMed1999

Serum fructosamine concentrations in hyperthyroid cats.

Serum fructosamine concentrations were measured in 35 healthy cats and in 30 hyperthyroid cats before and 30 days after curative radioiodine ((131)I) treatment. Hyperthyroid cats were divided into those with 30 day post-treatment total thyroxine (T4) concentrations within (EuT4) or below (HypoT4) the reference range. The median (semi-interquartile range, SIR) fructosamine concentration was significantly lower in hyperthyroid compared with healthy cats (295. 0 (18.5) micromol l(-1)) both before (254.0 (27.6) micromol l(-1)) and after (268.5 (28.0) micromol l(-1)) treatment (P < 0.001 in each case). (131)I therapy was associated with increases in serum fructosamine (mean increase 20.4 micromol l(-1), P = 0.039) and total protein (6.3 g l(-1), P < 0.002) in the HypoT4 group and in globulin concentration in both EuT4 (5.9 g l(-), P < 0.002) and HypoT4 (5.2 g l(-1), P = 0.023) groups. There were no direct relationships between the observed elevations in fructosamine concentration and those in total protein or globulin concentrations suggesting that the effect may be due to reduced rates of protein turnover. Reduced values may need to be considered when interpreting serum fructosamine concentrations for monitoring the degree of glycaemic control in diabetic cats with concurrent hyperthyroidism.

Animals↗
PubMed1998

Prevalence of autoantibodies to thyroglobulin in dogs with nonthyroidal illness.

OBJECTIVE: To evaluate a thyroglobulin autoantibody (TgAA) assay and determine a diagnostic threshold. SAMPLE POPULATION: Serum samples from dogs with various endocrine abnormalities and from 30 obese adult female Beagles. PROCEDURE: TgAA were determined by use of the ELISA. Six experiments were done: 1, definition of positive results for TgAA using samples from normal and T3 autoantibody (T3AA) positive dogs; 2, establishment of prevalence of positive results in 91 clinically normal dogs; 3, evaluation of positive results for sera from dogs with nonthyroidal illnesses; 4, testing of samples from dogs with primary hypothyroidism but absence of T4AA or T3AA, or both; 5, determination of prevalence of false-negative results in dogs that are T4AA and/or T3AA positive, which were (18 dogs) or were not (22 dogs) receiving L-thyroxine replacement therapy; and 6, examination of thyroid biopsy specimens from 18 dogs (8 TgAA positive and 10 TgAA negative). RESULTS: Positive results were defined as at least twice (200%) the optical density of the negative-control sample. False-positive results were obtained for only 3.4% of 146 dogs with nonthyroidal illness. Thirty-seven percent of dogs with primary hypothyroidism, but no evidence of T4AA or T3AA, or both, were TgAA positive. False-negative results were found in 1 of 22 and 2 of 18 T3AA-positive dogs with and without thyroid replacement therapy, respectively. Thyroid biopsy specimens from 8 TgAA-positive dogs had evidence of lymphocytic thyroiditis, whereas those from 10 TgAA-negative dogs did not. CONCLUSION AND CLINICAL RELEVANCE: The assay is sensitive and specific for identification of lymphocytic autoimmune thyroiditis in dogs, and has potential for aiding early diagnosis of thyroiditis in dogs and identifying dogs likely to perpetuate hypothyroidism in breeding programs.

Animals↗
PubMed1997

Pharmacokinetics of a porcine insulin zinc suspension in diabetic dogs.

Ten dogs with naturally occurring diabetes mellitus were injected with a highly purified porcine insulin zinc suspension at a dose according to their expected requirement. Plasma insulin and glucose concentrations were measured at two-hourly intervals over 24 hours following injection. There were either one or two peaks in plasma insulin concentration: one at about four hours (mean 4.3 +/- 1.3 [SD]) and another at about 11 hours (mean 11 +/- 1.85) after the injection. The second insulin peak was seen in only eight dogs. Persistence of elevated plasma insulin concentrations ranged from 14 to 24 hours (mean 17.4 +/- 3.65). These results compare favourably with those published for other intermediate-acting insulin preparations used to treat canine diabetes mellitus and suggest that this preparation has useful properties for the successful management of many canine diabetics.

Animals↗
PubMed1988

A double-crossover trial comparing the effects of topical carteolol and placebo on intraocular pressure.

The effect of topical carteolol 2% on the intraocular pressures of 12 patients suspected of having glaucoma was measured in a double-crossover trial of six weeks' duration. Carteolol produced a significant reduction in intraocular pressure (p less than or equal to 0.001), when compared with placebo. This represented reductions of 11% and 14%, after one and two weeks of treatment.

Administration, Topical↗
PubMed1987

A comparison of the effects of oral nadolol and topical timolol on intraocular pressure, blood pressure, and heart rate.

We compared the effects of oral nadolol 20 mg once daily and topical timolol 0.25% twice daily on the intraocular pressures of 22 glaucoma suspects, in a 12 week double-masked crossover study. Both nadolol and timolol reduced intraocular pressure (p less than 0.001). The reductions in intraocular pressure did not differ significantly after two weeks and four weeks of treatment. Nine of these subjects underwent treadmill exercise tests in order to compare the effects of nadolol and timolol on the cardiovascular system. The effects of the two treatments on blood pressure were comparable, but nadolol caused a significantly greater reduction in heart rate than timolol at rest (p less than 0.05). Nadolol reduces intraocular pressure effectively and may prove a useful alternative treatment for chronic simple glaucoma.

Administration, Oral↗