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Biomedical subjects

D Elliott

Publications and source records attributed to D Elliott.

At least 37 records · Page 2Linked to original sources
PubMed1999

Ocular perturbations and retinal/extraretinal information: the coordination of saccadic and manual movements.

Two experiments were conducted to examine the interactions between the ocular and manual systems during rapid goal-directed movements. A point-light array was used to generate Müller-Lyer configuration target endpoints (in-Müller, out-Müller, 'X') for 30 cm aiming movements. Vision (of the limb and target), eye position, and the concurrence of eye movement were varied to manipulate the availability of retinal and extraretinal information. In addition, the Müller-Lyer endpoints were used to generate predictable biases in accuracy of these information channels. Although saccadic amplitude was consistently biased, manual bias in response to illusory targets only occurred in trials with concurrent eye movement and elimination of retinal target information on limb movement initiation; covariation of eye and hand displacement was also most prevalent in these trials. Contrary to previous findings, there was no temporal relation between eye and hand movements. In addition to any role in coordinated eye-hand action, the availability of vision of both the limb and target again had strong performance benefits for rapid manual aiming.

Adult↗
PubMed1999

Hand deviations toward distractors. Evidence for response competition.

It has been suggested that, when movements are planned within cluttered environments, competing responses programmed to distracting stimuli are inhibited based on their relation to the action being performed. Further, as a result of this inhibition, the path of the movement made to the target object deviates away from the distractor. In contrast to the object avoidance hypothesis, the results of the present study show that, for aiming movements made in environments in which distractors are present, the path of the movement veers toward the distractor. Moreover, the effects of the distractors on the movement trajectory were independent of the direction of limb movement. These findings suggest that, when a distractor is not a potential physical barrier, a response to the distractor may be activated along with the target response and, owing to temporal advantages, cause a deviation of the movement trajectory toward the distractor.

Adult↗
PubMed1999

The utilization of visual information in the control of rapid sequential aiming movements.

Two experiments were conducted to examine the role of vision in the execution of a movement sequence. Experiment 1 investigated whether individual components of a sequential movement are controlled together or separately. Participants executed a rapid aiming movement to two targets in sequence. A full vision condition was compared to a condition in which vision was eliminated while in contact with the first target. The size of the first target was constant, while the second target size was varied. Target size had an influence on movement time and peak velocity to the first target. Vision condition and target size did not affect the time spent on the first target. These results suggest that preparation of the second movement is completed before the first movement is terminated. Experiment 2 examined when this preparation occurred. A full vision condition was compared to a condition in which vision was occluded during the flight phase of the first movement. Movement initiation times were shorter when vision was continually available. Total movement time was reduced with vision in two-target condition, but not in a control one-target condition. The time spent on the first target was greater when vision was not available during the first movement component. The results indicate that vision prior to movement onset can be used to formulate a movement plan to both targets in the sequence [Fischman & Reeve (1992).

Adolescent↗
PubMed1999

Measuring the health outcomes of general ICU patients: a systematic review of methods and findings.

Studies that have measured patient outcomes following a critical illness and admission to a general intensive care unit (ICU) have used a variety of methods and variables. Traditionally, the measures have been mortality and morbidity, but they now also include assessment of indices such as functional status, health status, quality of life and patient satisfaction. This review paper examines 31 previously published primary studies that measured patient outcomes from adult general ICUs. Inclusion criteria for the review process included papers with explicit measurement of patient outcomes beyond mortality rates: functional status, health status and quality of life. The paper includes summative descriptions of the reviewed papers, discussion of the various methods, results and limitations, and some synthesis of the pooled findings. The review indicated that the health status and activities of the majority of survivors who responded to the follow-up measures were similar to what they were before their critical illness. However, whether these subjects are representative of ICU survivors in general is not conclusive, as lack of methodological control over exclusions and losses to follow-up were evident. In addition, the heterogeneity of the ICU population in terms of age, acuity and diagnoses complicates any potential comparisons. There is an opportunity for further studies in this area by nurse researchers, in either intra- or multidisciplinary teams. Future studies should incorporate rigorous methodologies and a triangulated approach, in order to adequately examine patient outcomes following a critical illness and admission to a general ICU.

APACHE↗
PubMed1999

TRFK-5 reverses established airway eosinophilia but not established hyperresponsiveness in a murine model of chronic asthma.

We studied the effects of an anti-interleukin (IL)-5 monoclonal antibody (TRFK-5) or dexamethasone (DEX) to reverse already established airway hyperresponsiveness (AHR) and tissue eosinophilia in a Schistosoma mansoni antigen-sensitized and airway-challenged mouse model of chronic asthma. In this model at 4 d after antigen challenge there is dramatic bronchoalveolar lavage fluid (BAL) eosinophilia, AHR to intravenous methacholine (MCh), and histologic evidence of peribronchial eosinophilic infiltration and mucoid cell hyperplasia. These changes persist for up to 2 wk after antigen challenge. Treatment with DEX from Days 4 through 10 significantly reduced established airway eosinophilia compared with animals sham-treated with saline from Days 4 -10 (120 +/- 29 eosinophils/microl BAL for DEX-treated mice versus 382 +/- 60 eosinophils/microl BAL for sham-treated animals, p < 0.01). DEX-treated mice also had dramatically reduced mucoid cell hyperplasia, and airway responsiveness returned to normal. In contrast, TRFK-5 given during the same time period reduced airway eosinophilia (86 +/- 32 eosinophils/microl BAL versus 382 +/- 60 eosinophils/microl BAL, p < 0.01) but did not reduce goblet cell hyperplasia or reverse already established AHR. Treatment with DEX but not TRFK-5 also inhibited interferon gamma (IFN-gamma) content of BAL fluid (0.49 +/- 0.09 ng/ml BAL fluid for DEX versus 1.50 +/- 0.24 ng/ml BAL fluid and 1.36 +/- 0.13 ng/ml BAL fluid for TRFK-5 and sham-treated mice, respectively, both p < 0.001 versus DEX). Thus, treatment with DEX reduces established eosinophilic airway inflammation and AHR in S. mansoni-sensitized and airway-challenged mice but treatment with TRFK-5 reversed established eosinophilia without ameliorating established AHR. Together, these data suggest that once airway inflammation develops, neutralizing the effects of IL-5 or reducing eosinophilia alone may not result in inhibiting established AHR in atopic asthma.

Allergens↗
PubMed1999

CD28 interactions with either CD80 or CD86 are sufficient to induce allergic airway inflammation in mice.

Previous studies have shown that the pan CD28/cytotoxic T lymphocyte antigen (CTL)A-4 antagonist CTLA4 immunoglobulin (Ig) inhibits eosinophilic airway inflammation in Schistosoma mansoni-sensitized and airway-challenged mice. In the present study, the importance of CD28 as well as the individual roles of CD80 and CD86 were examined in this system using wild-type and CD28 knockout (KO) mice. Unlike wild-type controls, CD28KO mice did not produce systemic IgE or eosinophilic airway inflammation after antigen challenge. However, a lymphocytic infiltrate and continued production of interferon-gamma was observed in these animals. Thus, CD28 is not essential for the initial recruitment of lymphocytes into antigen-challenged airways but critically regulates the allergic T-helper 2 phenotype. We next determined by polymerase chain reaction and flow cytometry that CD80 and CD86 molecules are constitutively expressed in the naive murine lung and on eosinophils in the allergic lung, suggesting a potential important role for both ligands in the development of asthma. Combined anti-CD80/anti-CD86 treatment throughout the antigen challenge period fully blocked the development of allergic airways, whereas a partial reduction was observed in mice treated with either anti-CD80 or anti-CD86 antibody alone. However, only anti-CD86 blocked systemic IgE production. Therefore, signaling through either CD80 or CD86 is sufficient to generate a partial local allergic response, whereas CD86 costimulation is essential to induce systemic allergic (IgE) reactions. Finally, combined anti-B7 monoclonal antibody treatment after sensitization reduced airway eosinophilia and interleukin (IL)-4/IL-5 cytokine secretion consistent with an ongoing role for CD28/B7 interactions in the effector phase of the disease. These results emphasize the importance of differential B7 expression on different cells and in different organs on subsequent CD28/B7-mediated immune events, including the potential for CD28/B7 blockade in the treatment of atopic airway disease in people.

Animals↗
PubMed1998

IL-6-deficient mice form granulomas in murine schistosomiasis that exhibit an altered B cell response.

IL-6 can play an important role in various biological activities. Using IL-6-deficient, 129 x C57BL/6 mice and normal littermate controls, we studied the role of IL-6 in granulomas of mice infected with schistosomiasis mansoni. Granulomas from IL-6(+/+) mice produced large quantities of IL-6, derived from T, B, and myeloid cells. Yet, IL-6 mutant mice generated normal-appearing granulomas of appropriate size. Multiple-parameter flow cytometric analysis of dispersed granuloma cells revealed no substantial differences. Granuloma cells and splenocytes were cultured in vitro to measure cytokine and immunoglobulin production. Compared to control cells, IL-6(-/-) granuloma cells secreted more IL-4, IL-5, and IL-10. However, splenocytes secreted cytokines comparably. In the IL-6(-/-) state, the granuloma cells released less IgE and substantially more IgM, although IgG1, IgG2a, and IgA secretion remained normal. ELISPOT assay showed that dispersed granuloma cells from IL-6-deficient animals had substantially more IgM-secreting B cells. Thus, schistosome granulomas make IL-6 that is not essential for most aspects of granuloma development. However, IL-6 deficiency results in some disturbance of granuloma cytokine and immunoglobulin expression.

Animals↗
PubMed1998

The substance P and somatostatin interferon-gamma immunoregulatory circuit.

Murine schistosomiasis mansoni is a parasitic disease in which flukes living in the portal vein of the host produce ova that deposit in the liver and intestines. In these organs, ova release antigens that induce chronic, focal granulomatous inflammation. IFN-gamma is an inflammatory cytokine important in macrophage activation and B-cell differentiation. A substance P (SP)/somatostatin (SOM) neurokine immunoregulatory circuit controls IFN-gamma production in schistosome granulomas. SP stimulates, while SOM inhibits IFN-gamma release, modulating IFN-gamma-dependent circuitry. SP and SOM function through interaction with authentic SP and SOM receptors located on granuloma T cells. Also, the granulomas produce authentic SP and SOM14, as evidenced by the presence of mRNA and product. The granulomas have no nerves. This, and other data suggest that the inflammatory cells make these neurokines. Granuloma macrophages produce SOM. Macrophages from various sources express SOM mRNA in response to LPS, IFN-gamma, IL-10 or several other inflammatory mediators. Thus, the inflammation of murine schistosomiasis has a complete SP/SOM immunoregulatory circuit, which in turn is subject to immunoregulation.

Animals↗
PubMed1998

Manual asymmetries in goal-directed movement: examination of the motor output hypothesis.

Two experiments are reported which examined the viability of motor output hypothesis as an explanation for manual asymmetries in goal-directed movement. Experiment 1 isolated the variability due to force generation by directly assessing precision of force production during an isometric wrist flexion task. Experiment 2 examined the additional role of externally based and internally created timing patterns on the performance of a repetitive force production task. Virtually no effects involving hand were apparent in either experiment. These findings provide no support for a hypothesis based solely on motor output to adequately account for hand differences in the performance of rapid, goal-directed movement.

Adult↗
PubMed1998

Manual asymmetries and saccadic eye movements in right-handers during single and reciprocal aiming movements.

Two experiments examined the coordination of eye and hand movements in right-handed subjects who completed single (Experiment 1) and reciprocal (Experiment 2) aiming movements with each hand. In both experiments eye movements preceded hand movement, and arrived well in advance of the hand to allow pickup of visual information about relative position of the hand and target to correct te ongoing movement. With reciprocal aiming differences emerged between the hands. A right hand advantage was found for movement execution, and a left hand advantage for movement initiation. Manual asymmetries were not due to practice differences between hands. Subjects made larger initial saccades and more corrective saccades when aiming with the left hand. The pattern of eye-hand coordination was consistent with Woodworth's (1899) two component model of limb control, and at odds with models of limb control which suggest that online visual pickup is of minor importance.

Adult↗
PubMed1998

The effect of nonregulatory stimuli on the triple jump approach run.

The purpose of this experiment was to examine the approach run of the triple jump. Specifically, we examined the effect of nonregulatory stimuli (Gentile, 1972) on two different ability levels in performing the triple jump approach run. These nonregulatory constraints (situational factors such as those seen in actual competition) were employed in three jumping conditions: Control (to obtain baseline performance measures), Distance (where participants attempted to obtain as great a jump as possible), and Accuracy (participants attempted to be as accurate as possible on takeoff without sacrificing distance). The results showed that the footfall position variability for all conditions was similar to those previously reported for the long jump approach run. However, in compliance with the nonregulatory constraints, participants altered other performance parameters in executing the approach run. The situational factors created changes that revealed themselves in foot placement on the takeoff board at the end of the approach run (foot position constant error and number of fouls increased for the Distance condition) and decreased horizontal velocity at takeoff in the Accuracy condition. Changes in performance parameters were related to the context in which the skill was performed and may further reflect changes made by jumpers in the course, such as a visual-motor task in competition. We suggest that the characteristics of the approach run may not be fully revealed by the pattern of footfall variability only, as has been suggested in previous work (e.g., Lee, Lishman, & Thomson, 1982), but that the situation under which the jump is performed may have a significant effect on the performance parameters that emerge in executing this type of motor skill.

Adult↗
PubMed1998

Principles of clinical medicine: Oregon Health Sciences University School of Medicine.

In 1992, the School of Medicine at Oregon Health Sciences University inaugurated a Principles of Clinical Medicine (PCM) course as part of an overall curricular revision. The PCM course, which covers the first and second years of medical school, integrates material from ten separate courses in the previous curriculum. Students learn longitudinally over the two years, rather than "cramming" discrete areas of knowledge and then moving on. Course sessions are related to concurrently taken basic science classes. Meeting two afternoons per week, the PCM course offers preceptorships, health care issues sessions, and patient examination sessions. The PCM course aims to encompass the body of knowledge, skills, and attitudes necessary to become a competent physician. First- and second-year students have more opportunities than previously to interact with patients and practicing physicians in the community. Competition between learning areas, student perceptions of "soft" and "hard" courses, teacher recruitment, and administrative burnout are ongoing difficulties, while faculty recognition and development, administrative commitment and flexibility, and student and faculty feedback all contribute to the success of the course. The PCM course is now the backbone of the first two years of medical school and creates a solid foundation for the third and fourth years.

Attitude of Health Personnel↗
PubMed1998

The control of sequential goal-directed movement: learning to use feedback or central planning?

Fifteen participants practiced a two-target sequential aiming movement with either full vision of the movement environment, vision during flight, or vision while in contact with the first target. After 100 acquisition trials, participants performed a retention test in their own condition and then were transferred to each of the other two vision conditions. Both performance and kinematic data indicated that rather than becoming less dependent on visual information with practice, subjects learned to adjust their movement trajectories to use the visual information available in their particular vision condition. Although transfer to a degraded vision condition disrupted performance, when vision was augmented participants quickly adjusted their aiming trajectories to use the added information. The findings suggest that at least part of learning involves the development of rapid and efficient procedures for processing afferent information, including visual response-produced feedback.

Adolescent↗
PubMed1998

CTLA4Ig inhibits airway eosinophilia and hyperresponsiveness by regulating the development of Th1/Th2 subsets in a murine model of asthma.

Complete T-cell activation requires two distinct signals, one delivered via the T-cell receptor, and the second "co-stimulatory" signal through CD28/B7 ligation. Previous studies showed that the blockade of CD28/B7 ligation alters differentiation of Th1/Th2 lymphocyte subsets in vitro and in vivo. The present study was designed to determine the effect of a CD28/B7 antagonist (CTLA4Ig) on Th1/Th2 development in Schistosoma mansoni-sensitized and airway-challenged mice. Treatment of mice with CTLA4Ig beginning 1 wk after sensitization abolished airway responsiveness to intravenous methacholine determined 96 h following antigen challenge. We also found a significant reduction in bronchoalveolar lavage (BAL) eosinophilia, and reduced peribronchial eosinophilic infiltration and mucoid-cell hyperplasia. Furthermore, CTLA4Ig treatment significantly decreased interleukin (IL)-4 and IL-5 content in BAL fluid in vivo, and the production of IL-5 by lung lymphocytes stimulated with soluble egg antigen (SEA) in vitro. In contrast, the content of interferon-gamma in BAL fluid and supernatant from SEA-stimulated lung lymphocytes from CTLA4Ig-treated mice was increased significantly compared with untreated animals. Thus, CTLA4Ig inhibits eosinophilic airway inflammation and airway hyperresponsiveness in S. mansoni-sensitized and airway-challenged mice, most likely due to attenuated secretion of Th2-type cytokines and increased secretion of Th1-type cytokines.

Abatacept↗
PubMed1998

Influence of spatial mapping on manual aiming asymmetries.

Two experiments were conducted to examine manual asymmetries in a one-dimensional aiming task. In Exp. 1, 10 right-handed adults slid a computer mouse 13 cm on a graphics tablet with both the right and left hands to targets of 3 different diameters. Under these conditions, the movement time for the right hand was significantly faster as expected. In Exp. 2, subjects performed similar movements to move a cursor 13 cm on a computer monitor. Thus the study was identical except the stimulus-response mapping was indirect. In this situation, there were no significant difference for either movement time or movement error between hands despite these performance measures indicating the target aiming was more difficult in Exp. 2. Because increases in task difficulty generally result in a greater advantage for the right hand, as indicated by Todor & Smiley, 1985, the present studies suggest that superiority of the right hand in aiming tasks may be diminished when spatial translation is required. Perhaps the spatial translation requires greater involvement of the right hemisphere, a process associated with manual advantage for the left hand, previously suggested by Roy and MacKenzie.

Adult↗