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Biomedical subjects

N Walker

Publications and source records attributed to N Walker.

At least 73 records · Page 4Linked to original sources
PubMed1996

The nuclear channel system in endometrial adenocarcinoma exposed to medroxyprogesterone acetate.

The nuclear channel system (NCS), giant mitochondria and subnuclear glycogen form a triad of ultrastructural features observed in normal human endometrial epithelium in response to progestational steroids. Both the giant mitochondria and subnuclear glycogen have been described in endometrial adenocarcinoma, but the NCS has not. This article reports the development of the NCS in adenocarcinoma treated with medroxyprogesterone acetate. Previous studies suggest that the NCS in normal tissue is a response to the acyl group in the 17-beta position of the D-ring of some progestational steroids, such as medroxyprogesterone acetate. Medroxyprogesterone acetate was administered to 12 postmenopausal women with endometrial adenocarcinoma. Hysterectomies were performed 8 to 20 days after treatment. Pretreatment specimens were also obtained on 8 of the 12 patients. Using standard electron microscopy procedures, light microscopy on plastic semithin sections was first used to confirm the presence of tumor. Thin sections of malignant endometrium were prepared and evaluated ultrastructurally for progestational alterations. Abnormal giant mitochondria and subnuclear glycogen were found both before and after treatment. The third element of the triad, the NCS, was not observed in any of the available pretreatment biopsies, but was seen in three of the treated specimens. Thus it appears that the NCS is a response to the given progesterone therapy.

Adenocarcinoma↗
PubMed1996

Age-adjusted recurrence risks for relatives of patients with multiple sclerosis.

Familial aggregation is a cardinal epidemiological feature of multiple sclerosis, but few investigators have systematically examined recurrence risks for relatives of affected individuals in the United Kingdom. As part of a cross-sectional study of multiple sclerosis in Cambridgeshire, pedigree details were taken on 674 probands. Sex-specific, crude and age-adjusted recurrence risks were assessed amongst relatives of probands, applying a statistical model based on the observed age at onset of affected individuals and providing risks for clinical counselling. Details on year of birth, present age or age at death, and disease status were available on 11 391 relatives of successive probands. Nineteen percent of patients reported an additionally affected relative; 128 non-proband affected relatives were identified and the highest risk was observed for sisters. There was a systematic reduction in relative risk with genetic distance from the proband and no preferential recurrence for maternal or paternal relatives.

Adult↗
PubMed1996

Caudate nucleus area in drug-induced parkinsonism.

This study examined caudate nuclei areas in 10 schizophrenic subjects with and 25 schizophrenic subjects without parkinsonian symptoms. The subjects with parkinsonian symptoms were found to have statistically significantly smaller right caudate nuclei and a trend towards smaller left caudates. Cortical measurements did not differ between the groups. These results are consistent with the suggestion that antipsychotic drugs exert some neurotoxic effects, but should be viewed as preliminary and require replication.

Aged↗
PubMed1996

Supporting perception in the service of dynamic decision making.

Skilled performers in complex environments rely heavily on heuristic strategies to cope with the time pressure and complexity of dynamic tasks. We suggest that the use of task simplification strategies based largely on perception and pattern recognition is fundamental to the novice-expert shift in dynamic decision making. We therefore suggest that interface training interventions should support the development of highly effective and robust heuristic strategies, rather than the development of more abstract, cognitively intensive strategies. A pair of empirical studies are presented that investigated the benefits of training interventions aimed at supporting perceptual and pattern-recognitional activities in dynamic environments. Results suggest that the acquisition of skilled performance in dynamic environments can be accelerated by supporting perceptual activities in the service of dynamic decision making. Implications of these results for training, aiding, and interface design are discussed.

Adult↗
PubMed1996

Caudate nucleus morphology in tardive dyskinesia.

OBJECTIVE: The objective of this project was to test whether there are differences in the size of the caudate nucleus in schizophrenic in-patients with and without tardive dyskinesia. METHOD: The study was cross-sectional in design, examining group differences between institutionalised schizophrenic patients with and without tardive dyskinesia, using non-enhanced computerised tomography scans of the brain. The group comprised 15 schizophrenic patients with persistent tardive dyskinesia and 21 in-patient schizophrenic controls who were group-matched for demographic variables. RESULTS: The dyskinetic subjects had a significantly larger left caudate nucleus and tended to have a larger right caudate nucleus than the controls. There were no differences between the groups on any of the measures of cerebral atrophy. CONCLUSIONS: The findings can be understood within the context of models of neostriatal function. It is possible that a larger caudate nucleus could be used to identify patients at risk of developing tardive dyskinesia.

Adult↗
PubMed1996

Training older adults to use automatic teller machines.

The present study assessed the success of several instructional programs in teaching the use of automatic teller machines (ATMs). Fifty-six older adults (aged 61 to 81) participated in the study, randomly assigned to each of four, 14-member groups. The description group received only a general overview of an ATM; the text guide group received written instructions for performing various transactions on an ATM; the pictorial guide group received written instructions accompanied by pictures of corresponding ATM screens; and the online tutorial group completed a step-by-step tutorial on a simulated ATM. Participants practiced on an ATM simulator. They were tested after a 24-h interval on their ability to perform familiar transactions on an unfamiliar ATM simulator and to perform completely novel transactions. Accuracy was best for the online tutorial group, intermediate for the text and pictorial guide groups, and worst for the description group. These data demonstrate both the importance of providing older adults with ATM training and the fact that the type of training influences the level of performance. The online tutorial, which provided specific practice on the task components, best facilitated acquisition and transfer performance.

Age Factors↗
PubMed1996

A survey of automatic teller machine usage across the adult life span.

The purpose of this study was to analyze automatic teller machine (ATM) usage across the adult life span. We conducted an extensive survey of 9000 people in the Memphis and Atlanta metropolitan areas. Approximately 17% of those people responded. The survey assessed detailed demographic information, experience with technology in general, experience specifically related to ATMs, problems and dislikes with ATMs, and reasons that people do not use ATMs. The survey provided a valuable set of data. First, we have detailed information about the demographics and individual characteristics of ATM users and nonusers; importantly, these data are stratified across the adult life span. In addition, we know the likes and dislikes of ATM users and the types of problems they typically have using ATMs. Moreover, we have detailed analysis of why adults of all ages may choose not to use ATMs. Training and design implications of these data are discussed.

Adult↗
PubMed1996

Document classification and searching--a neural network approach.

This article introduces the basic concepts of Artificial Neural Networks and the related work that is currently being carried out at ESRIN in the field of document classification and searching. Some of the authors' ideas on the future directions that these techniques might take are also presented.

Algorithms↗
PubMed1995

Oncocytic metaplasia of bile duct epithelium in hepatic GVHD.

A 15-year-old female underwent matched unrelated BMT for chemotherapy resistant ALL. She died 3 months later from septicaemia complicating grade IV GVHD. Light and electron microscopic examination of the post-mortem liver confirmed GVHD and showed oncocytic metaplasia of interlobular bile duct epithelium. We report that oncocytic metaplasia of bile duct epithelium is part of the pathological spectrum of hepatic GVHD.

Adolescent↗
PubMed1995

Synthesis, structure and antitumor activity of new benz[d,e]isoquinoline-1,3-diones.

New benz[d,e]isoquinoline-1,3-diones related to mitonafide (CAS 54824-17-8) and amonafide (CAS 69408-81-7) with double substitution on the chromophore and branched side chains have been synthesized and their biological activity determined. Molecular modeling studies of 3a based on X-ray crystallographic data of mitonafide have shown that the aromatic system intercalates between GC steps of DNA. The in vitro cytotoxic test data using CX-1 and LX-1 cells showed higher cytotoxic activities in disubstituted derivatives compared to both lead compounds. Some of the compounds have been selected for in vivo test using L1210 tumor cells and CX-1 cells. Two of them (3b and 3j) have shown promising activity as good candidates for clinical development.

Adenine↗
PubMed1994

Progress on smoking control in Western Australia.

In 1990, 20 years of campaigning by the Western Australian branch of the Australian Council on Smoking and Health succeeded in getting tobacco advertising banned in Western Australia and a fund set up to replace the sponsorship of sport by tobacco companies. The council coordinated the activities of the mainly professional medical organisations that formed its members, ensuring that messages about the dangers of tobacco were consistently presented from different angles. The campaigners also ensured that medical data were reworked for presentation to decision makers and public, invaded the corporate world, and minimised opposition by enlisting the support of sportspeople opposed to tobacco sponsorship. The council hopes now that elimination of advertising will reduce the prevalence of smoking.

Advertising↗
PubMed1994

Statistical analysis of data from the Third International IALSC Workshop on Lung Tumor and Differentiation Antigens.

The main aim of the statistical analysis of data collected in the Third International IALSC Workshop on Lung Tumor and Differentiation Antigens, was to identify groups of monoclonal antibodies (MAbs) having similar profiles of reactivity against a variety of cell types in flow cytometry, histology, immunofluorescence and immunocytochemistry experiments. This was achieved through cluster analysis. We describe the methods used in the cluster analysis, and in the data processing leading to it.

Antibodies, Monoclonal↗
PubMed1994

Small bowel transplantation for pediatric short bowel syndrome: evaluation of the graft length required for development and the immunologic aspects relating to graft length.

Small bowel transplantation (SBT) is thought to be the only radical treatment for short bowel syndrome in childhood. It is very important that the length of the graft and the type of intestine be chosen carefully because this will determine the outcome of transplantation. This model of short bowel syndrome in the rat confirms that total intestinal resection results in malnutrition and failure to gain weight. After 10 cm of ileum was transplanted orthotopically in a syngeneic combination in rats with total intestinal resection, the animals gained weight. The authors determined that 10 cm of terminal ileum is the minimum length required for survival. Second, the immunologic basis of lethal graft-versus-host reaction (GVHR) as it relates to the intestinal graft length was also evaluated. Ileal grafts of 10 cm from LEW (RT1l) rats were implanted heterotopically into (LEW x BN)F1 rats. Ileal grafts of 10 or 40 cm were implanted from BN(RT1n) rats into (LEW x BN)F1 animals. A lethal GVHR always occurred after grafting a 10 cm ileum in the LEW/F1 combination, whereas only 17% of the BN/F1 recipients died of typical GVHR. However, in the latter combination, 67% lethal GVHR was induced when 40 cm of the intestinal graft was implanted. These results indicate that mesenteric lymph nodes are a major source of lethal GVHR, but gut-associated lymphoid tissue can also induce this.

Animals↗
PubMed1994

Olfactory receptor gene cluster on human chromosome 17: possible duplication of an ancestral receptor repertoire.

A gene superfamily of olfactory receptors (ORs) has recently been identified in a number of species. These receptors share a seven transmembrane domain structure with many neurotransmitter and hormone receptors, and are likely to underlie the recognition and G-protein-mediated transduction of odorant signals. Previously, OR genes cloned in different species were from random locations in the respective genomes. We report here the cloning of 16 human OR genes, all from chromosome 17 (17p13.3). The intronless coding regions are physically mapped (on 35 cosmids) in one 0.35Mb long contiguous cluster, with an average intergenic separation of 15kb. The human OR genes in the cluster belong to four different gene subfamilies, displaying as much sequence variability as any randomly selected group of ORs. This suggests that the cluster identified may be one of several copies of an ancestral OR gene repertoire whose existence may predate the divergence of mammals. The latter may have duplicated in some species to form the present mammalian OR gene repertoire, with several hundred genes. The human chromosome 17 OR gene cluster may thus be a good model for understanding human olfaction, as well as the ontogeny and phylogeny of the OR gene superfamily.

Amino Acid Sequence↗