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Biomedical subjects

R A Wright

Publications and source records attributed to R A Wright.

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

Exercise-induced asthma. Is gastroesophageal reflux a factor?

An acid-induced cholinergic esophagobronchial reflex has been described whereby acid refluxing into the esophagus causes bronchospasm. Reports of exertional gastroesophageal acid reflux prompted us to study the possibility that exercise-induced asthma (EIA) could be related to gastroesophageal reflux (GER). Following an overnight fast, 10 athletes with a history of EIA (nine men, one woman; mean age 31) were studied. Continuous monitoring of intraesophageal pH and motility, ECG, and arterial oxygen saturation was done. After baseline monitoring at rest for 15 min, subjects underwent treadmill exercise for 10 min followed by continuous monitoring for 30 min after exercise. Spirometry was done at baseline prior to exercise, then repeated every 5 min after exercise for 30 min. Two subjects were retested at a later date following a standard test meal. All 10 subjects demonstrated a decrease in FEV1 in response to exercise, but only half met criteria for EIA. Although 60% (6/10) showed some evidence GER, only three subjects demonstrated a pathologic degree of GER. In the two subjects retested postprandially, change in FEV1 was no different in one and improved in the other despite worsening of GER in both. There was no significant correlations between GER and EIA (P = 0.2). EIA correlated inversely with amplitude of esophageal contractions (P = 0.029) and was directly related to the percentage of multipeaked contractions and the duration of peristaltic contractions (P = 0.08). EIA is not associated with exertional GER.

Adolescent↗
PubMed1996

Does fluoroscopic guidance for Maloney esophageal dilation impact on the clinical endpoint of therapy: relief of dysphagia and achievement of luminal patency.

BACKGROUND: Use of fluoroscopy for Maloney esophageal dilation is controversial. We designed this prospective, randomized, single-blinded study to determine whether fluoroscopic guidance has an impact on relief of dysphagia and achievement of luminal patency. METHODS: Patients with benign esophageal strictures were randomized to undergo Maloney dilation with or without fluoroscopic guidance. Strictures were dilated to size 48F. Dysphagia scores were obtained before and 1 week after dilation. RESULTS: Eighty-three patients underwent 100 dilation sessions with fluoroscopic guidance being used for 50 sessions (156 dilations) and blinded technique for 50 (161 dilations). A 12.5 mm barium pill passed after dilation following 62.0% of the fluoroscopic dilation sessions and 42.0% of the blinded dilations (p = 0.045). Dysphagia was improved in 93.0% of patients receiving fluoroscopic dilations and 69.0% of patients receiving blinded dilations (p = 0.006). The mean improvement in dysphagia score was -2.10 points for the fluoroscopic group versus -1.50 points for the blinded group (p = 0.057). Differences in these parameters between techniques were even greater in 12 patients re-randomized to both techniques at different sessions. CONCLUSIONS: The use of fluoroscopic guidance impacts favorably on the efficacy of Maloney dilation, resulting in greater relief of dysphagia and increased luminal patency compared to the blinded technique. Based on these results, use of fluoroscopy is recommended when Maloney esophageal dilation is performed.

Catheterization↗
PubMed1996

The novel metabotropic glutamate receptor agonist 2R,4R-APDC potentiates stimulation of phosphoinositide hydrolysis in the rat hippocampus by 3,5-dihydroxyphenylglycine: evidence for a synergistic interaction between group 1 and group 2 receptors.

The mGlu receptor subtypes and second messenger pathways that mediate 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD) responses in brain tissues are not fully understood. 1S,3R-ACPD differs from 3,5-dihydroxyphenylglycine (DHPG) or quisqualate in that 1S,3R-ACPD also activates group 2 mGlu receptors (mGlu2 and mGlu3) that are negatively linked to cAMP formation. To investigate the contribution of group 2 mGlu receptor activity of 1S,3R-ACPD to the phosphoinositide response in the rat hippocampus, we examined the effects of the novel group 2 mGlu receptor agonist 2R,4R-4-aminopyrrolidine-2,4-dicarboxylate (2R,4R-APDC). 2R,4R-APDC did not activate or inhibit group 1 mGlu receptors (human mGlu1 alpha and mGlu5a) or group 3 mGlu receptors (human mGlu4 and mGlu7), but potently decreased forskolin-stimulated cAMP formation in human mGlu2- and mGlu3-expressing cells. In slices of the adult rat hippocampus 2R,4R-APDC had no effect on basal phosphoinositide hydrolysis; however, it was found to greatly enhance phosphoinositide hydrolysis to DHPG or quisqualate. In the neonatal rat hippocampus, 2R,4R-APDC enhanced the potency of DHPG, while not affecting the maximal response to group 1 mGlu receptor agonists. Thus, the phosphoinositide response in the rat hippocampus to 1S,3R-ACPD is mediated by a synergistic interaction between group 1 and group 2 mGlu receptors.

Aging↗
PubMed1996

Regional variations of ultrasonic integrated backscatter in normal and myopathic left ventricles. A new multi-view approach.

The purpose of the present study was to determine whether the cyclic variation of integrated backscatter is measurable and quantifiable in all left ventricular walls and whether the information obtained using both parasternal and apical transducer positions can be used to identify changes in myocardial structure and contractility. The cyclic variation of integrated backscatter was measured from the parasternal long-axis, apical four-chamber and two-chamber views in 26 patients with idiopathic dilated cardiomyopathy (mean age 58 +/- 9 years; ejection fraction 29 +/- 10%) and compared with information obtained from 30 aged-matched healthy volunteers. For each subject, the cyclic variation of integrated backscatter was calculated from 16 predetermined regions-of-interest located within the myocardium of the basal and mid-segments of the left ventricle imaged from the long-axis view and also the basal mid and apical left ventricular segments imaged from the two apical views. The cyclic variation of integrated backscatter was found to be present in 100% of the analysed regions-of-interest in healthy volunteers and in 87.5% of the analysed regions-of-interest in patients with idiopathic dilated cardiomyopathy. The mean value of cyclic variation of integrated backscatter, averaged from all regions-of-interest in the idiopathic dilated cardiomyopathy group, was significantly reduced compared to that in the healthy volunteers group (3.2 +/- 2.5 dB [mean +/- SD] vs 4.8 +/- 2.9 dB, P < 0.0001). Additionally, the healthy volunteers group demonstrated marked regional variability in the magnitude of cyclic variation of integrated backscatter which closely followed the regional changes in the contractile function of the normal heart. These regional differences in the magnitude of the cyclic variation of integrated backscatter were only partially retained in the idiopathic dilated cardiomyopathy group, and suggest that a multi-view approach of the recording of cyclic variation of integrated backscatter can be of value to differentiate normal from myopathic myocardium and to quantify regional differences in myocardial contractile performance throughout the left ventricular walls.

Adult↗
PubMed1996

Medical education in the Russian Federation.

The process of becoming a medical doctor in the Russian Federation is detailed in this paper. There has been a decline in the number of students entering the medical profession, as well as a marked decrease in the faculty members at the medical institutes since perestroika. This is secondary to a marked decrease in financial support as well as falling morale.

Curriculum↗
PubMed1996

Finding the medically underserved: a need to revise the federal definition.

The relationship between the primary service area (PSA) of an urban community health center (CHC) program and a federally defined "medically underserved area" (MUA) was assessed. Federal guidelines that most reliably predicted medical underservice were identified. The service area was statistically defined by census tract penetration rates. The MUA was defined by an index of medical underservice (IMU) according to federal parameters of physician supply, poverty level, percentage elderly persons, and infant mortality. An index score was calculated for the country, service area, and each census tract. Analysis by tract determined the most significant discriminating parameters. By excluding two tracts concentrated with managed-care physicians, the service area qualified as an MUA. Tracts that fulfilled MUA and service area criteria were highly associated (p < 0.0001). Only poverty level and infant mortality were useful discriminating parameters. Federal indicators of demand (elderly population) and supply (physicians) did not adequately address issues to access for the medically underserved in urban neighborhoods. Other parameters that might serve as proxies of care access and underserved are discussed.

Aged↗
PubMed1996

Tracking community sentinel events: breast cancer mortality and neighborhood risk for advanced-stage tumors in Denver.

OBJECTIVES: The incidence of related sentinel events--breast cancer mortality and neighborhood-specific morbidity for advanced stage at diagnosis--were calculated for women likely to use a community health center in Denver, Colo. METHODS: For the center's service area, neighborhoods (n = 37) were defined by program use. Mortality rates and proportional hazards regression models were estimated for 4189 breast cancer cases recorded between 1979 and 1990. Neighborhood-specific standard morbidity ratios of advanced-stage tumors were based on age-specific rates applied to the entire community. RESULTS: Service area residents were more likely to present with advanced tumors (odds ratio [OR] = 1.4; 95% [CI] = 1.2, 1.5). After adjustment, advanced-stage disease and socioeconomic-demographic status, but not race-ethnicity, contributed significantly to survival. Two neighborhoods (6.5% of the population at risk) with standard morbidity ratios of 2.1 (95% CI = 1.3, 3.4) and 1.7 (95% CI = 1.2, 2.5) accounted for 42% of the excess cases of advanced-stage tumors between 1986 and 1990. CONCLUSIONS: Neighborhood variation in advanced-stage cancer can serve as the basis for efforts to improve access to breast cancer screening.

Adult↗
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

In vitro and in vivo antagonism of AMPA receptor activation by (3S, 4aR, 6R, 8aR)-6-[2-(1(2)H-tetrazole-5-yl) ethyl] decahydroisoquinoline-3-carboxylic acid.

The in vitro and in vivo pharmacology of a structurally novel competitive antagonist for the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) subtype of excitatory amino acid receptors is described. LY215490, (+/-)(6-(2-(1-H-tetrazol-5-yl)ethyl) decahydroisoquinoline-3-carboxylic acid), was shown to displace selectively 3H-AMPA and 3H-6-cyano-7-nitro- quinoxaline-2,3-dione (3H-CNQX) binding to rat brain membranes. LY215490 potently antagonized quisqualate-and AMPA-induced depolarizations of rat cortical slices in a competitive manner, while requiring higher concentrations to antagonize the effects of N-methyl-D-aspartate (NMDA) and kainate. In slices of rat hippocampus, LY215490 also selectively antagonized AMPA-evoked release of 3H-norepinephrine. These AMPA receptor activities were due to the (-) isomer of the compound. (3S,4aR,6R, 8aR)-6-[2-(1(2)H-tetrazole-5-yl)ethyl] decahydroisoquinoline-3-carboxylic acid (LY293558). LY215490 was centrally active following parenteral administration in mice as demonstrated by protection versus maximal electroshock seizures and decreases in spontaneous motor activity. LY215490 (its active isomer being LY293558) represents a novel pharmacological agent for in vitro and in vivo studies of AMPA receptor function in the CNS.

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↗