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Biomedical subjects

R A Wright

Publications and source records attributed to R A Wright.

At least 19 recordsLinked to original sources
PubMed1995

Reversible and irreversible neuronal injury induced by intrahippocampal infusion of the mGluR agonist 1S,3R-ACPD in the rat.

Metabotropic glutamate receptor (mGluR)-induced neuronal injury in the brain was further investigated in the rat. The highly selective mGluR agonist 1S,3R-1-aminocyclopentane-1, 3-dicarboxylic acid (1S,3R-ACPD) was infused stereotaxically into the left dorsal hippocampus of adult rats. Control (2 microliters saline injected) rats had minimal tissue injury that was confined to the area around the injection site. In contrast, a dose of 250 nmol/2 microliters 1S,3R-ACPD produced a moderate number of swollen and injured cells in polymorphic, pyramidal and molecular layers of the injected hippocampus which was observed at 4 and 8 h post-injection. However, at 24 h few injured or necrotic cells were found. A dose of 1000 nmol/2 microliters 1S,3R-ACPD produced severe cellular injury in polymorphic, pyramidal and molecular layers of the hippocampus at 4, 8, or 24 h. At 24 h after this higher dose of 1S,3R-ACPD, a number of necrotic cells (i.e. pyramidal neurons of area CA1) were found. Both doses of 1S,3R-ACPD produced seizures in animals that were characterized by multiple episodes of wet dog shakes, staring, immobility, facial automatisms, rearing, bilateral forelimb clonus, and loss of postural control. These data support a possible role for excessive mGluR activation in pathological states of convulsions and neurodegeneration.

Animals↗
PubMed1995

Second-messenger responses in brain slices to elucidate novel glutamate receptors.

G-Protein-coupled or 'metabotropic' glutamate receptors (mGluRs) are a novel heterogenous family of excitatory amino acid receptors. Activation of mGluRs in the rat hippocampus by the mGluR-selective agonist 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) leads to multiple changes in second-messenger formation. These include increases in basal phosphoinositide hydrolysis, decreases in forskolin-stimulated cAMP formation, and enhancement of cAMP formation via a potentiation of the effects of endogenous adenosine. These changes in mGluR coupling to phosphoinositide hydrolysis and the formation of cAMP likely reflect the in situ expression of heterogenous populations of mGluRs. A number of electrophysiological studies on the functions of mGluRs in hippocampal circuitry, ontogeny, and cellular functions have also been described. Any or all of these mGluR-mediated changes in second messengers may underlie the reported cellular effects associated with the mGluR activation by 1S,3R-ACPD. However, mGluR agonists that have selectivity for different mGluR second-messenger pathways are needed to sort out the cellular consequences of activating in situ expressed mGluR subtypes linked to specific second-messenger pathways.

Animals↗
PubMed1995

Social evaluation and cardiovascular response: an active coping approach.

Cardiovascular effects of social evaluation were examined under different task conditions. In Experiment 1, systolic responses in women were greater under public than private conditions when a fixed behavioral challenge was difficult, but not when the challenge was easy. In Experiment 2, social evaluation potentiated systolic responsivity in men and women when a behavioral challenge was unfixed, but not when a behavioral challenge was fixed and easy to meet. Results are discussed in terms of a recent integrative analysis of effort and cardiovascular response as well as alternative conceptions that posit, or might be taken to imply, an association between publicity and physiologic activation.

Adaptation, Psychological↗
PubMed1995

Cardiovascular effects of experimentally induced efficacy (ability) appraisals at low and high levels of avoidant task demand.

Subjects were led to believe they had low or high ability with respect to a scanning task and then given the chance to avoid a noise by attaining a low (easy) or high (difficult) standard on a version of the task. Performance period measurements indicated that heart rate reactivity was greater in the difficult than easy condition for high-ability subjects but greater in the easy than difficult condition for low-ability subjects. Furthermore, whereas heart rate responses tended to be greater for low- than for high-ability subjects when the standard was low, they were greater for high- than for low-ability subjects when the standard was high. Results for blood pressure reactivity were comparable, although pairwise comparisons were not as consistently reliable. The main findings conceptually replicate and extend effects from previous studies; they also call further into question conventional conceptions that intimate an inverse relation between perceived self-efficacy and physiologic responsivity in the face of threat.

Adaptation, Psychological↗
PubMed1995

A nurse's diary.

Explore the source record for details and available documents.

Community Health Nursing↗
PubMed1992

Interactive effects of difficulty and instrumentality of avoidant behavior on cardiovascular reactivity.

College-aged subjects performed 35 trials of an easy or difficult digit-recognition task. Half were told that a good performance would ensure a high chance of avoiding a blast of noise, and half were told that a good performance would ensure a low chance of avoiding the noise. Results indicated that heart rate and systolic blood pressure reactivity were higher in the difficult condition than in the easy condition only when the probability of avoiding the noise (given success) was high. When the probability of avoiding the noise (given success) was low, heart rate and systolic responsivity were low regardless of task difficulty. It also was found that (1) performance quality was poorer overall among difficult subjects than among easy subjects, and (2) that the difference in performance quality between the easy and difficult groups was somewhat (not significantly) greater in the low-probability conditions than in the high-probability conditions. Major findings are considered in terms of Obrist's reasoning regarding the psychophysiological consequences of active coping and a motivational model by Brehm, which specifies conditions under which individuals will be more and less task engaged.

Adaptation, Psychological↗
PubMed1992

Obstructive jaundice secondary to primary biliary involvement with Hodgkin's disease.

A 41-yr-old man presented with jaundice, night sweats, and weight loss. The patient had been on phenytoin for seizure disorder. The drug was discontinued, and a diminution of bilirubin and transaminases occurred over several weeks. Percutaneous liver biopsy revaled cholestasis at the time of maximal hyperbilirubinemia. Recurrent jaundice ensued several weeks later, and an ERCP revealed a common bile duct lesion. Laparotomy revealed Hodgkin's disease involving the common bile duct and periportal node. This cause represents the first report of extrahepatic biliary obstruction from Hodgkin's disease.

Adult↗
PubMed1992

Cryptococcal olecranon bursitis in cirrhosis.

A 47-year-old man with cirrhosis developed a case of previously unreported olecranon bursitis due to Cryptococcus neoformans. Most patients with disseminated cryptococcosis have deficiencies in cell mediated immunity. Cirrhosis may be an independent risk factor because of impaired chemotaxis and phagocytosis.

Amphotericin B↗
PubMed1992

The evaluation and treatment of men with asymptomatic prostate nodules in primary care: a decision analysis.

BACKGROUND: Whether to perform periodic rectal examinations in asymptomatic men as a screening test for prostatic cancer remains controversial. A randomized clinical trial that tests the efficacy of further evaluation and treatment of men who have been found to have asymptomatic prostate nodules may never be carried out. Decision analysis was therefore used to further investigate this clinical issue. METHODS: A decision tree was developed to model the decision of whether to biopsy an asymptomatic prostate nodule found by digital rectal examination in a 65-year-old man by his primary care physician. Test operating characteristics, probabilities of disease at different stages, probabilities of side effects from various treatments, and average life expectancies were obtained from the medical literature. Utilities for the various possible health outcome states were obtained from ratings by two experienced primary care physicians using the Kaplan-Anderson Quality of Well-Being Scale. These were used to adjust the quality-of-life expectancies for each outcome state. Multiple sensitivity analyses were performed to assess the robustness of the conclusions. RESULTS: Disregarding patient utilities, the average survival benefit of evaluation and treatment is 1.1 months. When quality-of-life adjustments are included in the analysis, evaluation and treatment results in an average loss of 3.5 quality-adjusted months of life. Factors that shift the decision toward evaluation and treatment include a positive predictive value of a prostate nodule for cancer of 49% or greater, specificity of prostate biopsy of 98.3% or greater, and the availability of much more effective treatment for stage D cancers. Factors that do not substantially affect the decision are cancer-free life expectancy, the percentage of cancers that are stage B at time of discovery, the sensitivity of prostate biopsy, and more effective treatment for stage C cancer, assuming the same rate of adverse consequences from treatment. CONCLUSIONS: The evaluation and treatment of prostatic nodules found by digital rectal examination in asymptomatic men in the primary care setting does not lead to significant improvement in life expectancy and adversely affects quality of life. Digital rectal examination should not be performed by primary care physicians as a screening test for prostate cancer.

Aged↗
PubMed1991

Clinical judgment and bioethics: the decision making link.

The literature on bioethics is diverse and confusing in its treatment of appropriate components for decision making. As a result, the literature on teaching bioethics is also confusing, even contradictory, in presenting an 'appropriate' framework within which learners may come to understand the nature and process of bioethics. The article sets out five decision components which are seen as common to all decision making. These components are then shown to have a significant influence both on bioethics decision making and on bioethics teaching. They are also shown to play a role in breaking down the separatism evidenced in contemporary bioethics literature aimed at individual professions.

Beneficence↗
PubMed1991

Outpatient liver biopsy: one man's experience.

As an academically based gastroenterologist, I performed 94 outpatient liver biopsies over a 42-month period, using the standard suction technique. Differential blood count and vital signs were monitored, with no statistically significant postbiopsy changes noted in the group at large. One patient required admission to the hospital for bleeding, and six patients required intramuscular analgesics for pain at the biopsy site. Four patients had bradycardia, and one of them required atropine for bradycardia and hypotension. Outpatient liver biopsy is a safe procedure with low morbidity and complication rate. It would appear that prolonged monitoring is not necessary.

Ambulatory Care↗
PubMed1991

Gastric emptying in achalasia.

Some investigators have postulated that patients with primary achalasia have a generalized upper gastrointestinal motility disorder. To evaluate gastric emptying in patients with primary achalasia, four patients were studied prospectively after successful brusque dilation. Gastric emptying of liquids and solids was normal in all patients. There is no defect in gastric emptying in patients with primary achalasia.

Deglutition Disorders↗
PubMed1990

Acid-induced esophagobronchial-cardiac reflexes in humans.

Esophagobronchial reflexes have been demonstrated in both the cat and dog models. In order to determine if these reflexes are present in humans and if they are vagally mediated, a prospective sequential study was initiated. One hundred thirty-six individuals referred for esophageal manometric measurements were studied. Measurements of airway flow, arterial oxygen saturation, and pulse rate were performed before and after intraesophageal infusion of sterile water, normal saline solution, and 0.1 N hydrochloric acid. Highly significant reductions in heart rate, airway flow, and arterial oxygen saturation were noted after infusion of normal saline and 0.1 N hydrochloric acid compared with baseline water infusion (P less than 0.001). Graded responses were noted with heart rate: the more acidic the solution infused, the larger the decrement of heart rate. Atropine abolished postsaline/acid decrements of airway flow, arterial oxygen saturation, and heart rate. It is concluded that acid-induced, vagally mediated esophagobronchial reflexes are present in humans.

Atropine↗
PubMed1990

Task demand and cardiovascular response magnitude: further evidence of the mediating role of success importance.

The interactive effects of success importance and task demand upon cardiovascular reactivity were investigated in 2 experiments. In Experiment 1, Ss learned that success on an easy or difficult memory task would allow them to avoid a mild or severe noise. As expected, pretask and task elevations in heart rate and systolic blood pressure increased with difficulty only when the noise was to be severe. In Experiment 2, Ss listened to a victim, attending either to how she must feel or to technical features of the presentation. Then they were given the chance to earn a donation by succeeding on an easy or difficult memory task. Pretask cardiovascular data accorded with predictions predicated on the assumption that the need to help would be greater among victim perspective Ss. For them, systolic elevations increased with difficulty, whereas for technical perspective Ss systolic elevations were low regardless of task demand.

Achievement↗
PubMed1990

Peripheral parenteral nutrition is no better than enteral nutrition in acute exacerbation of Crohn's disease: a prospective trial.

The use of parenteral nutrition in patients with exacerbation of regional enteritis is controversial, the clinical dictum being bowel rest and nutritional repletion. In order to address this issue, on the short-term at least, a prospective randomized trial compared peripheral parenteral alimentation and elemental feedings for 2 weeks in patients hospitalized with regional enterities. Both groups had significant objective clinical improvement on their respective nutritional supplementation regimens pre- versus posttherapy as assessed by the Crohn's Disease Activity Index (CDAI) (p less than 0.05). However, there was no significant difference in improvement between parenteral versus enteral groups as assessed by the CDAI. Changes in nutritional assessment parameters, including retinol binding protein, nitrogen balance, total lymphocyte count, and transferrin, were related to the quantity of calories consumed rather than the mode of delivery. A positive nitrogen balance was obtained in all patients despite weight loss in the majority. The route of nutrient delivery in acute exacerbation of regional enteritis does not appear to have an impact on the short-term outcome.

Adult↗