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Biomedical subjects

J Palmer

Publications and source records attributed to J Palmer.

At least 145 records · Page 8Linked to original sources
PubMed1994

Set-size effects in visual search: the effect of attention is independent of the stimulus for simple tasks.

In visual search, both attentional and non-attentional sensory processes contribute to set-size effects. Here, non-attentional sensory effects were controlled and the remaining effects matched closely the purely attentional effects measured by a cueing paradigm. Using these controls, set-size effects were measured for five simple and two more complex tasks. The set-size effects were of similar magnitude for all of the simple tasks and larger for the complex tasks. For stimuli in the simple tasks, the results were consistent with the existence of a purely attentional effect on decision processing that is independent of the particular stimulus.

Adult↗
PubMed1994

Quantitative evaluation of aerosol deposition pattern in the lung in patients with chronic bronchitis.

A number of numeric measurements have been suggested to describe the pattern of deposition of inhaled aerosols, but there is little information about the relationship between the different measurements. We compared four different methods for analysis of aerosol deposition pattern with respect to their ability to separate patients with chronic bronchitis (CB) from healthy subjects, and with respect to their relationship to a simple index of airflow obstruction. Twelve healthy subjects and 22 patients with CB were studied. All the subjects inhaled a radiolabelled aerosol produced with an air-jet nebulizer. The aerosol contained albumin millimicrospheres labelled with 99Tcm. The ratio of peripheral to central deposition--the penetration index, the coefficient of variation, the coefficient of skewness and the quotient between maximum and mean value deposition were calculated using a gamma camera. The differences between the patients and the healthy subjects were statistically significant for all variables (p < 0.001). The sensitivity of measurements of aerosol deposition for detection of CB was similar to that of forced expiratory volume in one second (FEV1). We found strong correlations between the indices of aerosol deposition and FEV1 between all indices. In clinical routine practice, studies of aerosol deposition offer little advantage in the evaluation of patients with CB. Any of the indices may be suitable for evaluation of aerosol deposition in e.g. studies of inhaled pharmaceuticals.

Administration, Inhalation↗
PubMed1994

Proficiency testing in parasitology. An educational tool to improve laboratory performance.

In 1977, the Laboratory Proficiency Testing Program began testing laboratories that examine samples for gastrointestinal parasites and operated with little change in the subsequent 17 years. Four surveys, each containing four samples, are distributed each year to every currently licensed medical laboratory in Ontario. Participation is mandatory. Survey results indicate a remarkable improvement in laboratory performance during this period. Improvement is believed to result from a combination of the voluntary withdrawal from testing by laboratories with poor performance and the improved performance of the others. The extensive educational services devised and carried out by the Parasitology Committee is believed to have been a significant factor leading to this improvement.

Data Collection↗
PubMed1994

Further leaks.

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Equipment Failure↗
PubMed1994

Distribution and dosimetry of 111In DTPA-D-Phe-octreotide in man assessed by whole body scintigraphy.

The distribution and dosimetry of the somatostatin analog 111In-DTPA-octreotide was evaluated in 6 patients. Whole body scintigraphy in anterior and posterior projections was performed 0.5, 5, 24 and 48 hours after injection. Region-of-interest analysis for different organs and the whole body was used to determine 111In octreotide half-life-corrected uptake in absolute and relative terms. A rapid initial uptake was seen in the kidneys (2-7%), the spleen (2-6%) and in the liver (4-8%). A lower uptake was seen in the pituitary gland (maximum 0.3%), the thyroid (maximum 0.07%), in the female breast (maximum 1.2%), in the urinary bladder and in the intestinal tract. The elimination pattern varied between different organs. The effective dose equivalent was evaluated to be in the range 0.08 to 0.13 mSv/MBq (average 0.10 mSv/MBq). The behavior of 111In-DTPA-octreotide suggests follow-up scintigraphy in a period extending up to at least 24 hours after injection.

Absorption↗
PubMed1993

Serevent nationwide surveillance study: comparison of salmeterol with salbutamol in asthmatic patients who require regular bronchodilator treatment.

OBJECTIVE: To compare safety of salmeterol and salbutamol in treating asthma. DESIGN: Double blind, randomised clinical trial in parallel groups over 16 weeks. SETTING: General practices throughout the United Kingdom. SUBJECTS: 25,180 patients with asthma considered to require regular treatment with bronchodilators who were recruited by their general practitioner (n = 3516). INTERVENTIONS: Salmeterol (Serevent) (50 micrograms twice daily) or salbutamol (200 micrograms four times a day) randomised in the ratio of two patients taking salmeterol to one taking salbutamol. All other drugs including prophylaxis against asthma were continued throughout the study. MAIN OUTCOME MEASURES: All serious events and reasons for withdrawals (medical and non-medical) whether or not they were considered to be related to the drugs. RESULTS: Fewer medical withdrawals due to asthma occurred in patients taking salmeterol than in those taking salbutamol (2.91% v 3.79%; chi 2 = 13.6, p = 0.0002). Mortality and admissions to hospital were as expected. There was a small but non-significant excess mortality in the group taking salmeterol and a significant excess of asthma events including deaths in patients with severe asthma on entry. Use of more than two canisters of bronchodilator a month was particularly associated with the occurrence of an adverse asthma event. CONCLUSIONS: Treatment over 16 weeks with either salmeterol or salbutamol was not associated with an incidence of deaths related to asthma in excess of that predicted. Overall control of asthma was better in patients allocated to salmeterol. Serious adverse events occurred in patients most at risk on entry and were probably due to the disease rather than treatment.

Administration, Inhalation↗
PubMed1993

The influence of dietary carbohydrate on performance of supramaximal intermittent exercise.

The present investigation examined the influence of dietary carbohydrate (CHO) on the performance of supramaximal intermittent exercise. A group of 14 moderately trained male students [mean age 21.0 (SD 1.6) years] completed a maximal oxygen consumption test and two identical 'maximal interval tests' (MIT1 and MIT2) over a 10-day experimental period. Each MIT involved five 60-s all-out periods of cycling (against 0.736 N.kg-1 body mass), with each period separated by 5 min of passive recovery. All subjects consumed a moderate CHO diet for 3 days preceding MIT1 (55.3% of energy intake as CHO) and were then randomly assigned to either a high CHO (83%), moderate CHO (58%) or low CHO (12%) diet for the 3 days separating MIT1 and MIT2. All food and drink consumed during the experimental period was weighed and recorded for later dietary analysis. Measurements of work done, exercise oxygen consumption (VO2), venous blood pH, plasma lactate and plasma glucose concentrations were compared between interval tests. Independent Student's t-tests revealed that the 5.6% increase in total work done recorded by the high CHO group and the 2.3% increase by the moderate CHO group between MIT1 and MIT2, were significantly different to the 5.4% decrease in performance recorded for the low CHO group (P < 0.001 and P < 0.01, respectively). No significant differences in performance changes was found between the high and moderate CHO groups; 10 subjects in each of these groups would have been necessary to attain significance at the 0.05 level using the same procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Measuring the effect of attention on simple visual search.

Set-size in visual search may be due to 1 or more of 3 factors: sensory processes such as lateral masking between stimuli, attentional processes limiting the perception of individual stimuli, or attentional processes affecting the decision rules for combining information from multiple stimuli. These possibilities were evaluated in tasks such as searching for a longer line among shorter lines. To evaluate sensory contributions, display set-size effects were compared with cuing conditions that held sensory phenomena constant. Similar effects for the display and cue manipulations suggested that sensory processes contributed little under the conditions of this experiment. To evaluate the contribution of decision processes, the set-size effects were modeled with signal detection theory. In these models, a decision effect alone was sufficient to predict the set-size effects without any attentional limitation due to perception.

Adult↗
PubMed1993

Effects of axial dynamization on bone healing.

The effects of early dynamization (physiologic axial compression) on canine fracture healing at six weeks were studied. Bilateral transverse mid-tibial osteotomies were created and initially stabilized with a 2-mm gap using relatively rigid external fixators. Seven days after osteotomy, the telescoping mechanism of one of the fixators on each dog was released (dynamized), resulting in physiologic loading of the osteotomy, while the contralateral fixator remained locked as a rigid control. The dynamized osteotomy closed, and increased functional weight bearing resulted from 3 weeks on. Radiographically the amount of periosteal callus increased over time, but no difference in callus size was seen between the dynamized fractures and the controls. Torsional mechanical testing found the dynamized osteotomies to be significantly stiffer, and they tended to tolerate more maximum torque than the controls. Microscopic evaluation found no difference in the volume of the periosteal and endosteal calluses or in the tissues constituting them. However, a significantly greater proportion of the dynamized osteotomy gap was filled with new bone. These results suggest that dynamization in this delayed union model improved fracture healing by reducing fracture gap size and increasing weight bearing, not by altering the pathway of fracture healing.

Animals↗
PubMed1993

Nonvolumetric stereotaxy-assisted craniotomy. Results in 50 consecutive cases.

Craniotomy using stereotactic techniques has the potential to improve the extent of tumor resection and to reduce wound and neurologic morbidity. Most reports of stereotaxy-assisted craniotomy (SC) for tumor resection have focused on techniques using sophisticated computer hardware and volumetric software. Results of nonvolumetric SC in 50 consecutive cases for tumor using the Brown-Roberts-Wells or Cosman-Roberts-Wells stereotactic systems are presented. Tumor type included malignant glial neoplasms (20 cases), metastases (19), benign glial tumors (5), meningiomas (4), and radiation necrosis (1). Results in the SC group were compared to a concurrent series of 50 conventional craniotomies (CC) for brain tumor by other surgeons. Sustained neurologic deficits were 4% in the SC group while 10% for CC. Wound complications were 4 and 8%, respectively. Median hospital stay was 5 days (mean 5.9, range 2-20) for SC and 7 days (mean 10.4, range 3-75) for CC. Low morbidity resections of many brain lesions can be performed using conventional stereotactic systems, the operating microscope and standard CT software.

Adult↗
PubMed1993

Motion at isoluminance: discrimination/detection ratios and the summation of luminance and chromatic signals.

Under some conditions, direction-of-motion thresholds are elevated with respect to detection thresholds for isoluminant chromatic stimuli. In the present study we investigated the effect of small luminance mismatches on ratios of direction-of-motion thresholds to detection thresholds (M/D ratios). The stimuli were 2 deg x 2 deg patches of a moving 1-cycle/deg, 2.75-deg/s sinusoidal grating, modulated spatially in luminance, chromaticity, or both. M/D ratios were close to 1 except when luminance modulation was < 1%, defined with respect to the individual subject's isoluminance point; in this range M/D ratios varied from 1.5 to 4.4. Sets of thresholds for both detection and motion tasks conformed approximately to ellipses. Thus, although motion processing shows a differential loss of sensitivity at isoluminance, similar summation rules appear to apply to the combination of luminance and chromatic signals for both tasks.

Color Perception↗
PubMed1993

Increased density of the azygos lobe on frontal chest radiographs simulating disease: CT findings in seven patients.

OBJECTIVE: Our objectives were to show that an opaque azygos lobe on the anteroposterior chest radiograph can be a normal finding and to investigate the causes of the increased density. MATERIALS AND METHODS: We prospectively examined 53 patients seen during a 3-year period in whom an azygos lobe was detected on chest radiographs. The size of the lobe was determined by the location of the trigone on chest radiographs. The trigone is the triangular area that marks the upper portion of the azygos fissure. If the trigone was located on the lateral aspect of the pulmonary apex, the azygos lobe was classified as type A (nine patients); if the trigone was situated at the midpoint of the cupula of the apex, the lobe was considered type B (20 patients); if the trigone was located on the medial face of the apex, the lobe was considered type C (24 patients). An opaque azygos lobe was defined as an increase of density suggestive of a pulmonary or mediastinal process. The findings on chest radiographs were compared with those on CT scans, which were obtained in all patients. RESULTS: Radiographs showed abnormally opaque azygos lobes in seven patients. Three cases were type B and the opaque lobe had a triangular aspect, suggesting pulmonary disease. Four cases were type C and the opacity had a convex aspect, suggesting a mediastinal mass. In all cases, CT scans showed a shallow azygos lobe and increased depth of the soft tissues of the mediastinum in front of the azygos lobe. This appearance was caused by tortuosity of the supraortic vessels in six cases and by a shadow from a normal thymus in one case. No pathologic process was discovered in any of the patients. CONCLUSION: We believe an opaque azygos lobe can be a normal finding, usually resulting from overlapping tortuous supraortic vessels.

Adolescent↗
PubMed1993

Expression of epidermal growth factor receptor in human glioblastoma multiforme.

The expression of epidermal growth factor receptor was determined in a series of 88 patients with glioblastoma multiforme using a monoclonal antibody to the receptor. Positive staining was seen in 17 patients but this did not have prognostic significance when compared with known clinical prognostic factors using a computer model. The significance of receptor expression in these tumours is discussed.

Brain↗