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Biomedical subjects

R Gray

Publications and source records attributed to R Gray.

At least 163 records · Page 9Linked to original sources
PubMed1997

Partnerships between self-help networks and health care facilities: the case of the Bayview Support Network.

This article discusses the role of patients and their families as peer support providers to other patients, and as decision makers within organizations. We use as a model the Bayview Support Network, a self-help network at the Toronto-Sunnybrook Regional Cancer Centre. We review the benefits of partnership, costs, limitations and risks. A list of features that contribute to effective partnership is also provided.

Cancer Care Facilities↗
PubMed1997

Differences in detrusor contractile function in women with neuropathic and idiopathic detrusor instability.

OBJECTIVE: To compare urodynamic indices of isometric and isotonic detrusor contractile function between patients with idiopathic detrusor instability and patients with multiple sclerosis (MS) and detrusor hyper-reflexia and thus determine whether the different types of detrusor instability share a common pathophysiological pathway. PATIENTS AND METHODS: Two groups of women were studied; 1139 neurologically normal patients with detrusor instability (mean age 55 years, SD 17) and 141 with multiple sclerosis (MS) and detrusor hyper-reflexia (mean age 45 years, SD 11). Patients were assessed using static water cystometry, examining storage function, isometric and isotonic detrusor contractile function and voiding outflow function. RESULTS: Bladder capacities were lower in the MS group, with a median of 357 mL, 95% confidence interval (CI) 305-400 mL, compared with the neurologically normal patients (median 450 mL, 95% CI 425-450, P < 0.001, Mann-Whitney U-test). Voiding was incomplete in the MS group, with a median (95% CI) residual volume of 100 (100-125) mL, but complete in the normal group, at 10 (10-10) mL. Higher median (95% CI) detrusor pressures at urethral opening (P(det open)) and closing (P(det close)) were recorded in the MS group than in the neurologically normal group, at 35.5 (33.2-46.6) cmH2O and 30 (27.6-31.6) cmH2O for P(det open), respectively (P = 0.003), and 25.3 (20.9-31.6)cmH2O and 16.6 (15.0-18.1) for P(det close), respectively, (P = 0.001). In the MS group, the median (95% CI) isometric unstable contractions were less well maintained, but were more powerful, at 17.6 (15.6-18.9) N, compared to the neurologically intact group at 14.4 (14.0-14.9) N (P = 0.002). In the MS group, contractions frequently did not relax back to baseline, whereas in the group with detrusor instability, full relaxation after contraction was more usual. There was no significant difference in the maximum speed of detrusor shortening (isotonic activity), measured by the velocity constant Q*, between the groups (median for both groups 20 mL/s, 95% CI 17-23). CONCLUSION: These results show differences in storage function, isometric detrusor contractile function and voiding outflow function between detrusor instability and detrusor hyper-reflexia, indicating that the two conditions may not share a common pathophysiological pathway.

Adult↗
PubMed1997

The administration of PRN medication by mental health nurses.

The use of PRN or 'as required' medication by mental health nurses is an important, yet little explored aspect of psychiatric inpatient care. In a survey of 100 inpatients in Canada (Craven et al. 1987), it was reported that 88% had been prescribed PRN medication. The most frequently administered drugs were antipsychotics, anticholinergics, and benzodiazepines. Similar results were found in a study by Walker (1991). Craven et al. (1987) also highlight that people over the age of 50 are more likely to be given PRN medication, and suggest that gender and legal status do not influence administration. Vitello et al. (1991), in a study of factors affecting the administration of PRN medication on a children's psychiatric unit, demonstrated that 91% of administrations were given orally (compared to 9% via intramuscular injection); however it is unclear if this finding can be generalized to an adult psychiatric setting. Mental health nurses' reasons for administering PRN medication have not been examined.

Adult↗
PubMed1997

Randomised trials of STD treatment for HIV prevention: report of an international workshop. HIV/STD Trials Workshop Group.

Three community trials of the impact of STD treatment interventions on HIV incidence in rural populations have been completed or are in progress in Uganda and Tanzania. Investigators from these trials met for a joint technical workshop in Baltimore in May 1996. This report summarises the consensus of the workshop, with the aim of providing useful input to research on HIV intervention strategies. Issues discussed include: (i) the role of community randomised trials; (ii) strategies for STD management; (iii) epidemiological and statistical issues in the design and analysis of community randomised trials; (iv) diagnostic methods for STDs in population surveys; (v) treatment regimens for STDs in rural Africa; and (vi) ethical issues in community trials.

Community Health Services↗
PubMed1997

Modal profiles for the Halstead-Reitan Neuropsychological Battery for Children.

Modal Profile Analysis was used to cluster students (aged 9 to 14 years) on 16 subtest scores from the Halstead-Reitan Neuropsychological Battery for Children (HRNB-C). This analysis produced eight modal profile types, all of which were replicated in multiple samples. An initial attempt to establish external validity indicated that the modal groups display dissimilar patterns of performance on independent variables. The present typology is compared to similar typologies developed with adult neuropsychological data. In sum, the current classification system provided less coverage than the adult typologies, but produced more unique or homogeneous modal groups. Discussion focuses on potential clinical and research uses of the modal HRNB-C profiles.

Journal Article↗
PubMed1996

Postchemotherapy adjuvant tamoxifen therapy beyond five years in patients with lymph node-positive breast cancer. Eastern Cooperative Oncology Group.

BACKGROUND: Data from a pilot study published in 1984 suggested that tamoxifen administration (as adjuvant hormonal therapy) for more than 5 years after initial breast cancer surgery might have therapeutic benefit. PURPOSE: A randomized trial was performed to assess the efficacy of maintaining tamoxifen therapy beyond 5 years in women with axillary lymph node-positive breast cancer who had been treated with surgery followed by 1 year of chemotherapy and 5 years of tamoxifen. METHODS: One hundred ninety-four women (87 postmenopausal and 107 premenopasual) enrolled in two concurrent Eastern Cooperative Oncology Group adjuvant trials (E4181 for postmenopausal patients and E5181 for premenopausal patients) were randomly assigned to continued tamoxifen therapy or observation. Data for 193 women (87 postmenopausal and 106 premenopausal) were available for analysis. Median follow-up is 5.6 years since the randomization at 5 years, with the longest follow-up being 8.0 years. The major analyses measured events from the time of randomization until relapse or death; these included time-to-relapse analyses, with new opposite-breast cancers counted as treatment failures, and survival analyses. Time-to-relapse comparisons and survival comparisons for women in the two treatment groups were made by use of the Kaplan-Meier method and the logrank test. Reported P values are two-sided. RESULTS: Five years after the randomization, no statistically significant differences were noted in either time to relapse or survival between women continuing to receive tamoxifen and those on observation. Eight-five percent of the women receiving tamoxifen were disease free at this time compared with 73% of those on observation (P = .10); survival was 86% for those continuing to receive tamoxifen and 89% for those on observation (P = .52). Differences in the time to relapse and survival between premenopausal and postmenopausal women assigned to the two treatment groups were also not statistically significant (time to relapse: P = .38 and P = .16 for premenopausal and postmenopausal patients, respectively; survival; P = .18 and P = .72 for premenopausal and postmenopausal patients, respectively). There was an indication that women with estrogen receptor-positive tumors may experience a longer time to relapse with continued tamoxifen therapy (P = .014); however, the survival difference for this subgroup was not statistically significant (P = .81). The toxicity patterns in the two treatment groups were similar. CONCLUSIONS AND IMPLICATIONS: Our results suggest that further evaluation of adjuvant tamoxifen therapy beyond 5 years in women with axillary lymph node-positive, estrogen receptor-positive breast cancer who have also been treated with adjuvant chemotherapy would be appropriate.

Adult↗
PubMed1996

Hippocampal synaptic transmission enhanced by low concentrations of nicotine.

Nicotine obtained from tobacco can improve learning and memory on various tasks and has been linked to arousal, attention, rapid information processing, working memory, and long-term memories that can cause craving years after someone has stopped smoking. One likely target for these effects is the hippocampus, a centre for learning and memory that has rich cholinergic innervation and dense nicotinic acetylcholine receptor (nAChR) expression. During Alzheimer's dementia there are fewer nAChRs and the cholinergic inputs to the hippocampus degenerate. However, there is no evidence for fast synaptic transmission mediated by nAChRs in the hippocampus, and their role is not understood. Nicotine is known to act on presynaptic nAChRs within the habenula of chick to enhance glutamatergic transmission; here we report that a similar mechanism operates in the hippocampus. Measurements of intracellular Ca2+ in single mossy-fibre presynaptic terminals indicate that nAChRs containing the alpha7 subunit can mediate a Ca2+ influx that is sufficient to induce vesicular neurotransmitter release. We propose that nicotine from tobacco influences cognition by enhancing synaptic transmission. Conversely, a decreased efficacy of transmission may account for the deficits associated with the loss of cholinergic innervation during Alzheimer's disease.

Action Potentials↗
PubMed1996

Percutaneous transpedicular biopsy of vertebral body lesions.

STUDY DESIGN: This prospective study evaluates the use of transpedicular biopsy in obtaining diagnostic tissue from vertebral body lesions. OBJECTIVE: To report the authors' experience of all (N = 32) percutaneous transpedicular biopsies performed between 1990-1994. SUMMARY OF BACKGROUND DATA: Previous articles have discussed the value of open biopsy of the vertebral body using a Craig needle. A large series of closed percutaneous transpedicular biopsies have not been reported. METHODS: The authors evaluated 32 patients (26 outpatients, six inpatients) who underwent transpedicular biopsy for T1-L4 lesions of the vertebral bodies. None of the tumors had an extraosseous component. Biopsy specimens were obtained from 25 lesions using C-arm fluoroscopy; seven were guided by computed tomography. All biopsies were performed with a 14- to 17-gauge bone biopsy needle. RESULTS: The needle passed through the pedicle into the site of disease in all patients, as confirmed by C-arm fluoroscopy or computed tomography. There were 22 malignancies; four isolated compression fractures, two at T6, one at T7, one at T8; four cases of infection or inflammation; and one case each of Paget's disease and myelofibrosis. Two patients required a second biopsy because the tissue sample was suspicious for lymphoma but not diagnostic. All 26 outpatients were discharged after a 2-hour observation period. There were no complications. CONCLUSION: Transpedicular biopsy of deep vertebral body lesions using a bone biopsy needle under computed tomography or fluoroscopy guidance can be performed safely and efficaciously as an outpatient procedure.

Adult↗
PubMed1996

Adjuvant chemotherapy plus tamoxifen compared with tamoxifen alone for postmenopausal breast cancer: meta-analysis of quality-adjusted survival.

BACKGROUND: Adjuvant tamoxifen for early breast cancer provides an improvement in relapse-free (RFS) and overall survival (OS), especially for older women. We carried out a meta-analysis to find out whether the benefit of adding chemotherapy to tamoxifen outweighs its costs in terms of toxic effects for postmenopausal patients. METHODS: The meta-analysis of quality-adjusted survival was based on data from 3920 patients aged 50 years or older with node-positive breast cancer randomly assigned in nine trials that compared combination chemotherapy plus tamoxifen with tamoxifen alone. The nine trials were included in the worldwide overview conducted by the early breast cancer trialists' collaborative group (EBCTCG). The quality-adjusted time without symptoms or toxicity (Q-TWiST) method was used to provide treatment comparisons incorporating differences in quality of life associated with subjective toxic effects of treatment and symptoms of disease relapse. FINDINGS: Within 7 years of follow-up the modest benefit of increased RFS and OS for patients who received chemotherapy just balanced the costs in terms of acute toxic side-effects. Chemotherapy-treated patients gained an average of 5.4 months of RFS and 2 months of OS (neither statistically significant), but had to receive cytotoxic treatment for between 2 and 24 months to achieve these gains. No values of preference weights for time spent undergoing chemotherapy and time after relapse gave significantly more Q-TWiST with chemotherapy plus tamoxifen than with tamoxifen alone. INTERPRETATION: Within 7 years of follow-up, adjuvant chemoendocrine therapy did not provide more quality-adjusted survival time than tamoxifen alone for women aged 50 years or older with node-positive breast cancer. Better selection and administration of chemotherapy regimen, different scheduling of chemotherapy and tamoxifen, and appropriate use of patient and tumour characteristics may increase the therapeutic advantage of the combination.

Antineoplastic Agents, Hormonal↗
PubMed1996

Evidence for a neural mechanism that encodes angles.

We measured the discrimination threshold (delta theta)Th for angle theta, where theta was either the angle of a Vee composed of two straight lines contained within the frontoparallel or the angle intersection of two straight lines contained within the frontoparallel plane. The two-line pattern was rotated bodily through a random angle between trials with the aim of eliminating the absolute orientation of one or the other line as a reliable cue to the task. We report evidence that this aim was achieved. Our main conclusion is that the ability to discriminate a change in angle theta cannot entirely be explained in terms of the ability to discriminate changes in the orientations of the individual lines that comprise the Vee. We propose that the human visual pathway contains a neural mechanism that encodes the difference in the orientations of two simultaneously-presented straight lines. Discrimination threshold for angle (delta theta)Th is roughly twice orientation discrimination threshold for an isolated line. When subjects cannot use the orientation of one or another line as a cue to the task, the plot of (delta theta)Th vs theta is approximately flat between the delta = 20 and 160 deg.

Cues↗
PubMed1996

Cyclopean motion perception produced by oscillations of size, disparity and location.

UNLABELLED: For cyclopean and monocularly-visible targets we measured psychophysical thresholds for perceptions produced by the following three stimuli: oscillations of disparity (DO), oscillations of size (SO) and oscillatory motion within the frontoparallel plane (FPO). RESULTS: thresholds for motion in depth perception produced by DO were similar for cyclopean and non-cyclopean targets over the entire 0.25-8 Hz frequency range investigated. Thresholds for perceiving motion in depth produced by SO were considerably (up to 2.5 times) higher for cyclopean targets than for monocularly-visible targets, as were thresholds for perceiving size oscillations. For both cyclopean and monocularly-visible target the perception of motion in depth could be canceled by pitting DO vs SO. Thresholds for perceiving FPO were similar to DO thresholds for the monocularly-visible target, but for the cyclopean targets FPO thresholds rose more steeply than DO thresholds for oscillation frequencies above 1 Hz. CONCLUSIONS: (1) for our subjects, the effective binocular stimulus for motion in depth perception is a rate of change of disparity; an interocular velocity difference is significant only to the extent that it produces a rate of change of disparity. (2) The sensations of motion in depth produced by DO and SO are qualitatively identical. (3) Neural signals produced by DO and SO converge onto a single neural mechanism that signals motion in depth.

Adaptation, Ocular↗