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Biomedical subjects

J Palmer

Publications and source records attributed to J Palmer.

At least 109 records · Page 6Linked to original sources
PubMed1997

Analysis of p53 gene deletions in patients with non-Hodgkin's lymphoma by dual-colour fluorescence in-situ hybridization.

The most common tumour suppressor gene altered in human cancers is p53, which is located on the short arm of chromosome 17. Structural abnormalities of the short arm and loss of chromosome 17 have been reported to confer resistance to chemotherapy in patients with non-Hodgkin's lymphoma (NHL). Therefore we studied the incidence and prognostic value of p53 deletions in patients with NHL by fluorescence in-situ hybridization using a 40 kb cosmid probe. Specimens obtained from 79 patients with NHL were studied. 46 patients were untreated, and 33 were previously treated. 40 tumours had indolent and 39 had aggressive histologies. p53 deletions were observed in 14 specimens (18%) in 32-90% of the cells. No statistically significant difference in the incidence of p53 deletion was observed between indolent and aggressive NHLs or between untreated and previously treated patients. However, p53 deletions were observed in three of four patients with transformed lymphoma. In the untreated patients, p53 deletion had no effect on response to therapy, time to treatment failure, or survival. We conclude that p53 deletions are uncommon in NHL, and may be frequent in patients with transformed lymphoma. In this study, p53 deletions did not influence treatment outcome or prognosis of NHL. Because monosomy 17 and 17p abnormalities have been reported to confer poor prognosis in NHL, other tumour suppressor genes on 17p should therefore be studied.

Aneuploidy↗
PubMed1997

Kidney size estimation in piglets using dimercaptosuccinic acid (DMSA) scintigraphy.

The objective of this study was to validate kidney size measurements obtained by DMSA scintigraphy in kidneys of sizes relevant in paediatric practice. Kidney length, width and volume were measured by DMSA scintigraphy in 10 piglets in vivo and compared with measurements on excised kidneys using callipers, planar scintigraphy and submersion in water. In addition, a kidney phantom was constructed and placed in a torso phantom. The length, width and volume of the kidney phantom were compared with planar and tomographic scintigraphic measurements. The mean overestimation of kidney length by scintigraphy was 1.7% (+/- 1.2%) on excised kidneys and 3.9% (+/- 2.4%) in vivo. The corresponding figures for width measurements were 7.0% (+/- 3.9%) and 7.8% (+/- 4.4%). Tomography volume estimation overestimated the submersion volume by 23% (+/- 12%). Scintigraphic measurements on the phantom over-estimated length by 5%, width by 8% and volume by 11%. Scintigraphic renal length measurements are reliable and differ from the anatomical length by < 4% compared with excised kidneys and < 8% in vivo. Scintigraphic width measurements and volume estimations, especially on small kidneys, are less reliable.

Animals↗
PubMed1997

Pulmonary perfusion and density gradients in healthy volunteers.

UNLABELLED: The goal of this study was to measure regional pulmonary perfusion using SPECT and transmission tomography for attenuation correction and density measurements. METHODS: Regional pulmonary perfusion was studied after intravenous injection of radiolabeled particles in 10 supine healthy volunteers using SPECT. Transmission tomography was used to correct for attenuation, measure lung density and delineate the lungs. The effects of attenuation correction on pulmonary perfusion gradients were investigated. RESULTS: In perfusion measurements not corrected for attenuation, we found significant perfusion gradients in the direction of gravity but also significant gradients at isogravitational level. After correction for attenuation, the gravitational gradient was significantly greater than before correction, and gradients at isogravitational level were no longer observed. Perfusion in the ventral lung zone was half of that in the dorsal lung zone. Mean lung density was 0.28 +/- 0.03 g/ml, and density showed a significant increase in the direction of gravity and at isogravitational level. CONCLUSION: We found that SPECT perfusion studies of the lung not corrected for attenuation gave a false impression of nongravitational gradients and underestimate the gradient that is gravity-dependent. Transmission tomography, used for attenuation correction, also quantifies lung density and shows gravity dependent and nondependent density gradients.

Female↗
PubMed1997

Automated interpretation of myocardial SPECT perfusion images using artificial neural networks.

UNLABELLED: The purpose of this study was to develop a computer-based method for automatic detection and localization of coronary artery disease (CAD) in myocardial bull's-eye scintigrams. METHODS: A population of 135 patients who had undergone both myocardial 99mTc-sestamibi rest-stress scintigraphy and coronary angiography within 3 mo was studied. Different image data reduction methods, including pixel averaging and two-dimensional Fourier transform, were applied to the bull's-eye scintigrams. After a quantitative and qualitative evaluation of these methods, 30 Fourier components were chosen as inputs to multilayer perceptron artificial neural networks. The networks were trained to detect CAD in two vascular territories, using coronary angiography as gold standard. A "leave one out" procedure was used for training and evaluation. The performance of the networks was compared to those of two human experts. RESULTS: One of the human experts detected CAD in one of two vascular territories, with a sensitivity of 54.4% at a specificity of 70.5%. The sensitivity of the networks was significantly higher at that level of specificity (77.2%, p = 0.0022). The other expert had a sensitivity of 63.2% at a specificity of 61.5%. The networks had a sensitivity of 77.2% (p = 0.038) at this specificity level as well. The differences in sensitivity between human experts and networks for the other vascular territory were all less than 6% and were not statistically significant. CONCLUSION: Artificial neural networks can detect CAD in myocardial bull's-eye scintigrams with such a high accuracy that the application of neural networks as clinical decision support tools appears to have significant potential.

Coronary Angiography↗
PubMed1996

Cyclosporiasis: a new cause of diarrhea.

Cyclospora cayetanensis, a coccidian parasite, is a new cause of prolonged diarrhea. It has been most recently associated with ingestion of contaminated fruit. Although infection with C. cayetanensis is considered rare, the exact prevalence in Canada is unknown. Transmission is thought to occur through contaminated food and water. The incubation period varies from days to weeks. Patients present with nausea, vomiting, anorexia, bloating, abdominal cramping, increased gas and watery diarrhea. The illness may last up to 6 weeks and may respond to treatment with trimethoprim-sulfamethoxazole. C. cayetanensis is differentiated from other coccidians by its sporulation characteristics and its autofluorescence. To obtain a positive result of a laboratory test for the organism, a modified Ziehl-Neelsen acid-fast stain is recommended. Proper laboratory handling of specimens is facilitated by inclusion of clinical information on requisition forms.

Animals↗
PubMed1996

Infant color vision: motion nulls for red/green vs luminance-modulated stimuli in infants and adults.

Four-week-olds, 9-week-olds, and adult subjects were tested with low spatial frequency sinusoidal gratings moving at a speed of 25 deg/sec. Luminance-modulated and red/green gratings were presented either separately, or superimposed and moving in opposite directions in a chromatic motion nulling paradigm. An adult observer judged the direction of the slow phase of the subject's eye movements. Luminance-modulated gratings elicited directionally appropriate eye movements in all three age groups, with contrast thresholds decreasing markedly with age. For red/green gratings alone, 4-week-olds responded only marginally, but 9-week-olds and adults produced consistent directionally appropriate eye movements. In the motion nulling condition, 15% contrast luminance-modulated gratings were about equally effective in nulling the motion of the red/green gratings in all three age groups. A formal model of the motion nulling paradigm, separating threshold and equivalent luminance contrast parameters, was developed and applied to the data. Model fits showed that equivalent luminance contrast was constant or nearly constant across age groups. This outcome is consistent with the hypothesis that, with respect to adults, infants show a uniform rather than a differential loss of sensitivity to moving red/green vs luminance-modulated stimuli.

Adult↗
PubMed1996

Physiological pushing in the second stage of labour: the future for midwifery care.

Current literature indicates that, during the second stage of labour, directed, sustained pushing is the predominant management. Research demonstrates this management has adverse effects upon the mother and baby. The view that the second stage of labour is of high risk, and needs to be hastened, remains unsupported. It is this view that perpetuates the use of directed, sustained pushing. This article demonstrates that physiological pushing during second stage of labour is the way of the future. When midwives work with normal physiology, they work with, not against the woman during the second stage of labour. Midwives must empower women to trust their own instincts.

Delivery, Obstetric↗
PubMed1996

Dynamic indium-111-pentetreotide scintigraphy in breast cancer.

UNLABELLED: The efficacy of imaging breast cancer with 111In-pentetreotide (somatostatin receptor scintigraphy) was evaluate before surgery. METHODS: Seventy-one whole-body scintigrams in 24 patients with known breast cancer and 24 whole-body scintigrams in 8 controls were obtained at 0.5, 5 and 24 hr after intravenous injection of 110 MBq 111In-pentetreotide. Anterior and posterior projection images were acquired simultaneously. SPECT of the thorax was performed at 5 or 24 hr after injection in all breast cancer patients. The specimens were imaged immediately after surgery and the distribution of pentetreotide was assessed qualitatively and quantitatively. RESULTS: Somatostatin receptor-positive tumors were found in 18/24 patients with breast cancer. Pentetreotide uptake was significantly greater in breast cancer patients compared to control patients. In all patients with positive images, the early scintigram (0.5 hr) showed abnormal uptake. It was possible to delineate three different dynamic patterns. Increased uptake was visually most distinct at each time (9 patients). Moreover, bilaterally increased pentetreotide uptake was observed in 10/18 true-positive patients (in 8 at each time and in 2 patients only at 5 hr), but only one patient had a known bilateral tumor. CONCLUSION: We found higher incidence of somatostatin receptors in patients with breast cancer than in the control group. Moreover, bilaterally increased pentetreotide uptake in clinically unilateral disease was an unexpected finding.

Breast Neoplasms↗
PubMed1996

Effective immunization against influenza in pediatric renal transplant recipients.

Viral infections such as influenza are an important cause of morbidity following organ transplantation. We evaluated the immunogenicity of a commercially available influenza vaccine in pediatric renal transplant recipients in a two-phase, prospective study. In phase one, 47 transplant patients and seven control subjects with bronchopulmonary dysplasia received influenza vaccine. Sera were collected at the time of vaccination and 6 wk later. In phase two, sera from 18 transplant recipients and 47 healthy adults who had received the same vaccine were collected 6-12 months after vaccination. Antibody titers to the A/Taiwan/1/86 antigen were measured with hemagglutination inhibition assay in both phases of the study. Vaccine was well tolerated in all subjects. No vaccinated patient required hospitalization for complications of influenza infection. Vaccination did not increase the frequency of acute allograft rejection. In phase one, 43 patients (91%) and 5 controls (71%) either seroconverted (developed a fourfold or greater rise in titer), or developed post-vaccination titers > or = 1:160 (p = NS). Among the transplant recipients, non-seroconverters had a higher pre-vaccination geometric mean antibody titer (GMT) than those who seroconverted. Seroconversion developed independently of whether patients received double or triple immunosuppression. In phase two, post-vaccination GMT were similar for patients and control subjects at 11.5 and 8 months post-vaccination, respectively. In our study, influenza vaccination produced equivalent humoral immunity in transplant recipients and normal subjects. Routine influenza vaccination should be performed annually in this high-risk population.

Adjuvants, Immunologic↗