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Biomedical subjects

G Smith

Publications and source records attributed to G Smith.

At least 271 records · Page 15Linked to original sources
PubMed1998

"Semi-straight sort of sex": class and gay community attachment explored within a framework of older homosexually active men.

Gay Community Attachment has proved a significant predictor of successful behavior change among gay-identifying men in response to HIV/AIDS. Related work at Macquarie University, Sydney, Australia, indicated that attachment to gay community is not a simple issue; rather, complex issues of sexual identity formation, the constraints of social inequality and localized sexual cultures inhibit the process of attachment and, therefore, successful HIV prevention. This paper discusses some of the findings from close-focus (qualitative) research on older homosexually active men which explore in depth the dynamic whereby these men attached themselves to gay community in terms of an analysis of class, generation, and the interplay with self-construction and masculinity.

Adult↗
PubMed1998

Assessment of the accuracy of the crossed-cylinder aberroscope technique.

Simulations of the optics of the Howland crossed-cylinder aberroscope technique show that errors in alignment, data collection, and analysis can lead to unexpected asymmetries of the determined aberrations in a rotationally symmetric system. In particular, coma can be incorrectly indicated. The magnitude of the error in aberration measurement depends on the magnitude of the alignment, data collection, and alignment errors. These findings indicate that the tolerances for setting up the technique and data collection should be analyzed thoroughly before quantitative significance is given to the determined aberration coefficients.

Computer Simulation↗
PubMed1998

Influence of Stiles-Crawford effect apodization on spatial visual performance.

The Stiles-Crawford effect is often invoked by vision scientists when predictions of the effects of aberrations and defocus on spatial visual performance are not borne out experimentally. Modeling the Stiles-Crawford effect as an apodization, we investigated the expected influence that it would have on spatial visual performance in the presence of 1-diopter primary spherical aberration at the edge of a 6-mm-diameter centered pupil. The changes in refraction produced by a high Stiles-Crawford effect, according to various criteria, were small at approximately 0.10 diopter. The Stiles-Crawford effect has only a small capability to compensate for defocus and spherical aberration. These results indicate that the Stiles-Crawford effect has little influence on spatial visual performance in the case of centered pupils. We suggest that the faith that has often been placed in the Stiles-Crawford effect to account for discrepancies between experimental results and expected results is not justified, at least for well-centered pupils and Stiles-Crawford effects.

Light↗
PubMed1998

Attitude towards aggression and creative functioning in patients with breast cancer.

Three projective personality tests were used to assess attitude to aggression (The Identification Test), anxiety and defenses (The Meta-Contrast Technique) and creative functioning (The Creative Functioning Test) in 70 patients with breast cancer. Discriminant analyses were applied pro primo to characterize psychologically patients with a better prognosis and patients with a poorer prognosis. A second aim was to characterize psychologically older (postmenopausal) and younger (premenopausal) women. Generally, high scores on the Identification Test indicated maladaptive attitudes towards aggression among all the patients. Patients with a poorer prognosis showed responses that in healthy subjects indicate acknowledgement of aggressive impulses, perhaps suggesting lack of "defenses" against such impulses among those patients. Another way to describe it would be that patients with a better prognosis seem to have (normally nonadaptive) "defenses" against aggressive impulses while those with poorer prognosis have not. Surprisingly, the patients with a better prognosis (but not those with a poorer prognosis) gave responses classified as depression in the Meta-Contrast Technique. Typical of premenopausal patients were responses classified as anxiety as well as reaction formation on the Identification Test. Responses classified as adaptive defenses (isolation) were seen in the Meta-Contrast Technique. A surprising finding was that many of these patients were characterized by high scores on the creativity test. These original statistically significant findings of attitudes towards aggression and creative functioning in breast cancer patients are discussed in relation to the underlying nature of aggression and creativity.

Adult↗
PubMed1998

Errors in determining the direction of the visual axis in the presence of defocus.

The visual axis is the ray path from the fixation point to the fovea by way of the nodal points. Such a ray path does not exist in unaccommodated vision when the fixation point does not coincide with the far point of the eye because of induced or natural defocus. Nevertheless an approximation to the visual axis can be obtained by the position of a small pupil close to the cornea for which a bichromatic vernier target appears correctly aligned. When the visual axis is determined, an eye rotation from the visual fixation position must occur, which is reversed upon removing the small pupil. Upon engaging in any experiments for which the visual axis is then used as a reference, there is an error in this reference position. We develop simple paraxial equations to estimate this error. We show that these equations have good accuracy. The error associated with locating the visual axis at the cornea is 0.002 mm per dioptre of defocus, which is small enough to be ignored.

Convergence, Ocular↗
PubMed1998

Tools from the implementation workbench: a project manager's survival kit.

Change rarely comes easy. There are frequently obstacles of various shapes and sizes throughout the implementation process, and in order to ensure success a project manager must have the right tools and know how to use them. Just as craftspeople master the tools of their trade, so too must project managers--not only if they are to succeed but also if they are to survive. This article focuses on the "how to"--the skill set needed to be a successful project manager. It describes the project management process and reviews some basic but invaluable tools.

Humans↗
PubMed1998

Patterns and associates of hyperphagia in patients with dementia.

This study examined patterns and associates of excessive eating (hyperphagia) in a community-based registry of patients with dementia. From patients enrolled in the Mayo Clinic Alzheimer's Disease Patient Registry (n = 439), 39 were identified with excessive eating reported on the Behavior Symptom Checklist at some time during their illness. They were matched for age, gender, duration of disease, and Global Deterioration Scale (GDS) score to "normal eaters." Annualized weight change was determined based on weight from the 6 months before the evaluation to weight 6 months after the evaluation. Annualized weight change scores were not significantly different between excessive eaters and normal eaters nor between wanderers and nonwanderers. In cross-sectional analysis, univariate modeling suggested age at onset, GDS, and Mini-Mental State Examination score to be significant predictors of excessive eating. Using multivariate logistic model with backward elimination, only age of onset and GDS were retained as associates of excess eating. Rater type also emerged as a significant predictor for excessive eating with family raters reporting this behavior in 16% of patients compared to 5% for other raters. In chi-square analyses excessive eating was associated with greater frequency of wandering, unpredictable behavior, inappropriate dressing, inappropriate bodily concerns, and threatening self-harm. Associates of excess eating were subsequently examined separately in wandering and nonwandering excessive eaters. Logistic modeling suggested that among nonwanderers, patients who were younger but more severely demented were likely to have reported excessive eating. These results suggest hyperphagia to be present in approximately 10% of a community-based cohort of patients with dementia and associated with increasing functional decline. Excessive eating does not appear to arise from memory dysfunction, but for wanderers may result from needing increased caloric intake because of increased activity levels. Thus, for wandering excessive eaters, it may be appropriate to endure the eating to ensure appropriate caloric intake. Nonwandering excessive eaters were younger, had greater dementia severity, and had more unpredictable behavior. They may have dementia with prominent frontal lobe involvement and may respond to any food stimulus respective of hunger. Restricting food exposure may be an effective management intervention for them.

Aged↗
PubMed1998

Developmental switching in the parasitic nematode Strongyloides stercoralis is controlled by the ASF and ASI amphidial neurons.

Parasitic nematodes of the genus Strongyloides are remarkable for their ability to switch between alternative free-living developmental pathways in response to changing internal environmental conditions. After exiting the host, soil-dwelling larval stages may develop either to infectivity via 2 microbiverous stages (homogonic development) or to free-living adulthood via 4 microbiverous larval stages (heterogonic development). The progeny of these adults then give rise to the infective stage. In the latter case, free-living existence is extended in time and the number of infective larvae is greatly amplified. Anterior chemosensory neurons (amphidial neurons) are thought to respond to environmental cues and via signal transduction pathways control the direction of larval development. We now demonstrate by laser microbeam ablation that 2 classes of amphidial neurons (ASF and ASI), acting together, control the direction of free-living larval development. Larvae in which the neurons were killed developed to infectivity via the homogonic route rather than to adulthood via the otherwise predominant heterogonic route. These neurons are probable homologues of neurons ADF (=ASF) and ASI in Caenorhabditis elegans, suggesting the control of development at the cellular level is conserved among divergent taxa of nematodes. These observations also have important implications for the evolution of nematode parasitism and the design of new prophylactic measures against parasitic nematodes of medical and veterinary medical importance.

Animals↗
PubMed1998

Appendicectomy and ulcerative colitis.

The aetiology of ulcerative colitis (UC) is unknown. However, much interest has been devoted recently to the relationship between appendicectomy and ulcerative colitis. A case-control study was conducted, comparing appendicectomy rates between 110 patients with UC (group 1) and 136 patients attending an orthopaedic clinic free from UC (group 2). The appendicectomy rates were 0.9% (group 1) and 10.3% (group 2), respectively (P < 0.002). The present study shows that patients with ulcerative colitis had rarely undergone appendicectomy before the first manifestation of colitis. Further research on this relationship is called for.

Adolescent↗
PubMed1998

Anti-inflammatory effects of topically applied dimethyl sulfoxide gel on endotoxin-induced synovitis in horses.

OBJECTIVE: To evaluate the effect of topically applied dimethylsulfoxide (DMSO) on lipopolysaccharide (LPS)-induced synovitis in the mid-carpal joint. ANIMALS: 6 sound, healthy, adult horses (12 carpi). PROCEDURE: In a double-blinded, crossover, paired study with a 1-week washout period, mid-carpal joints were allocated to group 1 (DMSO, n = 6) or group 2 (control, n = 6). Each joint was injected with 1.3 ml (0.0125 ng/dl) of LPS to induce synovitis. For group-1 joints, DMSO gel (15 g; 90%) was applied after injection of LPS and at 12-hour intervals for 60 hours. Joints of group 2 received LPS, but not DMSO gel. All horses were evaluated by serial lameness examinations and synovial fluid analyses (total and differential WBC count and total protein concentration) at 12-hour intervals for 60 hours after LPS injection. Plasma and synovial fluid were obtained at baseline and 36 hours to document presence of DMSO. RESULTS: Mean WBC concentration was significantly (P < 0.05) lower in group-1, compared with group-2 joints, at 24 hours and had a trend to be lower at 36 hours. Mean total neutrophil count was significantly lower in group-1, compared with group-2 joints at 24 hours. In group-1 joints, DMSO was detected by use of gas chromatography in the synovial fluid of 5 of 6 joints and in plasma from 1 of 6 horses. CONCLUSION: Topically applied DMSO penetrated into synovial fluid in sufficient quantities to be detected and to decrease joint inflammation.

Administration, Topical↗
PubMed1998

Should we patch corneal abrasions? A meta-analysis.

BACKGROUND: Eye patching is commonly recommended for treating corneal abrasions. This advice seems based more on anecdotes or disease-oriented evidence theorizing that there is faster healing or less pain when the eye is patched. This meta-analysis was performed to determine if eye patching is a useful treatment for corneal abrasions. METHODS: We conducted a comprehensive search of both MEDLINE (1966 to 1997) and Science Citation Index to locate relevant articles. We reviewed the bibliographies of included studies, and ophthalmology and primary care texts. Local ophthalmologists and authors were contacted to identify any unpublished data. Controlled trials that evaluated eye patching compared with no patching in patients older than 6 years with uncomplicated corneal abrasions were considered. The outcomes of interest were healing rates and degree of pain. RESULTS: Seven trials were identified for inclusion, of which five could be statistically combined. Healing rates were similar in the two groups. The summary ratios (95% confidence interval) of healing rates in the patch group as compared with the no-patch group were 0.87 (0.68 to 1.13) and 0.90 (0.75 to 1.10) at days 1 and 2, respectively. Six studies evaluated pain: four found no difference and two favored not patching. No differences in complication rates were noted between the patched and nonpatched groups. CONCLUSIONS: Eye patching was not found to improve healing rates or reduce pain in patients with corneal abrasions. Given the theoretical harm of loss of binocular vision and possible increased pain, we recommend the route of harmless nonintervention in treating corneal abrasions.

Bandages↗
PubMed1997

Etomidate inhibits [3H]noradrenaline release from SH-SY5Y human neuroblastoma cells.

We have examined the effects of the intravenous anaesthetic induction agent etomidate on K+ and carbachol evoked [3H]noradrenaline ([3H]NA) release and the associated increase in [Ca2+]i in SH-SY5Y human neuroblastoma cells in a attempt to study potential anaesthetic target site(s). Preincubation with etomidate produced a dose-dependent inhibition of both K+ and carbachol evoked [3H]NA release with estimated IC50 values of 88 and 69 microM, respectively. Only K+ stimulated increase in [Ca2+]i was inhibited by etomidate preincubation with an IC50 of 146 microM. Acute addition of etomidate after K+ challenge also inhibited the increase in [Ca2+]i with an IC50 of 99 microM. In addition etomidate displaced the binding of [3H]PN200-110 to L-type voltage sensitive Ca2+ channels with a Ki of 48 microM. As K+ but not carbachol evoked [3H]NA release is extracellular Ca2+ dependent and was inhibited by etomidate these data coupled with the PN200-110 displacement studies suggest that etomidate may interact with L-type voltage sensitive Ca2+ channels. The inhibition of carbachol evoked release without affecting the associated increase in [Ca2+]i suggests that etomidate may exert additional effects at either the muscarinic receptor or the secretory machinery in these cells.

Calcium↗
PubMed1997

Natural scrapie and PrP genotype: case-control studies in British sheep.

Natural scrapie in sheep is associated with polymorphisms of the PrP gene, particularly at amino acid codons 136, 154 and 171. This paper reports the results of nine scrapie case-control studies in Bleu du Maine, Herdwick, Merino x Shetland, Poll Dorset, Scottish Halfbred, Shetland, Soay, Suffolk and Swaledale sheep from British flocks affected by scrapie. In some outbreaks, scrapie was found to occur only in animals with at least one PrP allele encoding valine at codon 136 (V136), usually a relatively rare allele in healthy controls. In other outbreaks, the V136, PrP allele was either not found or was not an absolute prerequisite for scrapie to develop. Although scrapie had a strong tendency to affect sheep with PrP genotypes homozygous for glutamine at codon 171 (QQ171), these genotypes (QQ171 but varying at other codon positions) were relatively common in healthy controls. The reliable prediction of scrapie susceptibility in previously uninvestigated sheep flocks will therefore require information at least about PrP genotypes at codons 136 and 171.

Animal Husbandry↗
PubMed1997

Management of school leavers given a diphtheria and tetanus vaccine intended for children instead of the intended low dose preparation.

In November 1995, 102 school leavers in two North Staffordshire schools were given high dose diphtheria and tetanus vaccine (intended for primary immunisation of children) rather than a preparation with a low dose of diphtheria vaccine intended for adults and adolescents. We describe the management of the incident and the action taken to minimise the risk of such an error being made again. Pupils who had received the high dose vaccine and a control group were surveyed with a self-administered questionnaire. Thirteen children out of 67 given the higher dose diphtheria vaccine consulted their general practitioner and the same number had time off school, compared with none of 25 from a control school. This excess morbidity was probably attributable to the higher dose of diphtheria vaccine.

Absenteeism↗