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Biomedical subjects

S M Wright

Publications and source records attributed to S M Wright.

At least 55 records · Page 3Linked to original sources
PubMed1999

Production of endothelin by cultured human endothelial cells following exposure to nicotine or caffeine.

This study evaluated endothelin production by endothelial cells after exposure to nicotine or caffeine. Vasoconstrictive properties have been attributed to both nicotine and caffeine. The presence of endothelin, a potent vasoconstrictor itself, was determined using a radioimmunoassay. The optimal stimulatory doses for nicotine and caffeine were determined to be 1.0 micromol/L and 1.0 mmol/L, respectively. When endothelin production was evaluated over time after exposure to the optimal dose of each agent, it was determined that nicotine stimulated maximum endothelin production within 5 minutes. Caffeine failed to cause a distinct peak of endothelin production within 20 minutes. These results suggest that nicotine may have a possible acute and short-lived effect on the vasoconstrictive response associated with endothelin, while caffeine-induced endothelin release may require more long-term exposure.

Caffeine↗
PubMed1999

Increasing use of Medicare services by veterans with acute myocardial infarction.

OBJECTIVES: Some of the nation's 26 million veterans have two government-financed health care entitlements: Medicare and the Department of Veterans Affairs (VA). The aims of this investigation were to examine trends where Medicare-eligible VA users are initially hospitalized for acute myocardial infarction (AMI) and then to assess rates of cardiac procedure use and mortality for veterans initially admitted to each system of care. METHODS: We used VA and HCFA national databases to identify VA users (age range, > or = 65 years) who were initially admitted to a VAMC or Medicare financed hospital (Medicare hospital) with a primary diagnosis of AMI between January 1, 1992, and December 31, 1995, (n = 47,598). We examined the use of cardiac procedures (cardiac catheterization [CC], coronary artery bypass surgery [CABG], and coronary angioplasty [CA] and mortality (30-day and 1-year) by the type of initial admitting hospital within each system of care. RESULTS: Almost 70% of VA users hospitalized for AMI were initially admitted to Medicare hospitals versus VAMCs between 1992 (64%) and 1995 (72%). After adjusting for patient characteristics in logistic models, VA users initially hospitalized in Medicare hospitals were significantly more likely to undergo cardiac procedures than were VA users hospitalized in VAMCs. Differences in the odds of receiving a procedure were most significant when comparing Medicare hospitals with on-site cardiac technology to VA hospitals without on-site cardiac technology (CC: OR 4.34, 95% CI 3.98-4.73; CABG: OR 2.16, 95% CI 1.92-2.43; CA: OR 4.56, 95% CI 3.98-5.25). We found no significant differences in 30-day and 1-year adjusted mortality rates between VA users initially admitted to VAMCs or Medicare hospitals. CONCLUSIONS: Medicare-eligible VA users are increasingly hospitalized in Medicare hospitals for AMI. VA users cared for in Medicare hospitals receive more cardiac procedures but have the same survival as VA users cared for in VAMCs. These findings have policy implications for access, quality, and costs in both systems of care.

Aged↗
PubMed1999

Deficient hydrophilic lung surfactant proteins A and D with normal surfactant phospholipid molecular species in cystic fibrosis.

Chronic bacterial colonization of the lungs, with an excessive inflammatory response, is the major cause of morbidity and mortality in cystic fibrosis. Lung surfactant exhibits a spectrum of potential immunomodulatory properties: phospholipid components inhibit cellular inflammatory responses, whereas the hydrophilic surfactant proteins A (SP-A) and D (SP-D) are integral components of the innate host defense response of the lungs against bacterial infection. Consequently, alteration to the relative proportions of lung surfactant components may alter the susceptibility of the lungs to bacterial colonization. In this study, bronchoalveolar lavage (BAL) samples were collected at diagnostic fiberoptic bronchoscopy from 11 control children, 13 children with cystic fibrosis, and 11 children with acute lung infection. Electrospray ionization mass spectrometry analysis demonstrated negligible changes to the molecular species or total BAL concentrations of phosphatidylcholine, phosphatidylglycerol, or phosphatidylinositol among the three subject groups. In contrast, median SP-A concentration was decreased (P < 0.001) in the cystic fibrosis group (2.65 microg/ml) compared with control (12.35 microg/ml) and infection (9.76 microg/ml) groups. Median SP-D was also decreased (P < 0.05) in the infection (12.17 ng/ml) compared with the control group (641 ng/ml), and was below assay limits for the majority of cystic fibrosis children (P < 0. 001). This dramatic decrease of hydrophilic surfactant proteins in the presence of normal surfactant phospholipid may be one mechanism underlying the relative ineffectiveness of the cellular inflammatory response in killing invading bacteria in the lungs of patients with cystic fibrosis.

Bacterial Infections↗
PubMed1998

Attributes of excellent attending-physician role models.

BACKGROUND: Although effective role models are important in medical education, little is known about the characteristics of physicians who serve as excellent clinical role models. We therefore conducted a case-control study to identify attributes that distinguish such physicians from their colleagues. METHODS: We asked members of the internal-medicine house staff at four teaching hospitals to name physicians whom they considered to be excellent role models. A total of 165 physicians named by one or more house-staff members were classified as excellent role models (these served as the case physicians in our study). A questionnaire was sent to them as well as to 246 physicians who had residency-level teaching responsibilities but who were not named (controls). Of these 411 physicians, 341 (83 percent) completed questionnaires while unaware of their case-control status. RESULTS: Of the 341 attending physicians who responded, 144 (42 percent) had been identified as excellent role models. Having greater assigned teaching responsibilities was strongly associated with being identified as an excellent role model. In the multivariate analysis, five attributes were independently associated with being named as an excellent role model: spending more than 25 percent of one's time teaching (odds ratio, 5.12; 95 percent confidence interval, 1.81 to 14.47), spending 25 or more hours per week teaching and conducting rounds when serving as an attending physician (odds ratio, 2.48; 95 percent confidence interval, 1.15 to 5.37), stressing the importance of the doctor-patient relationship in one's teaching (odds ratio, 2.58; 95 percent confidence interval, 1.03 to 6.43), teaching the psychosocial aspects of medicine (odds ratio, 2.31; 95 percent confidence interval, 1.23 to 4.35), and having served as a chief resident (odds ratio, 2.07; 95 percent confidence interval, 1.07 to 3.98). CONCLUSIONS: These data suggest that many of the attributes associated with being an excellent role model are related to skills that can be acquired and to modifiable behavior.

Baltimore↗
PubMed1998

Development of an approach to estimating mid- to long-term critical loads for radiocaesium contamination of cow milk in western Europe.

This paper describes the application of the critical load methodology, developed to set emission targets for atmospheric pollutants, to radioecology. The critical load can be redefined within radioecology as the radionuclide deposition at which radionuclide activity concentrations in a specified food product will exceed the maximum permitted level. An empirically based approach is described which provides estimates of critical load values for cow milk in the mid- to long-term after an accident when soil-to-plant transfer of radiocaesium is largely responsible for plant radiocaesium contamination. The areas identified as being most potentially vulnerable to radiocaesium deposition using this approach are those with extensive areas of organic soils such as western Scotland, parts of Ireland, The Netherlands and Denmark. The classification of European soil types into soil groups with significantly different soil-to-plant transfer of radiocaesium, and the allocation of a transfer value to each soil group provide the greatest uncertainties within this approach. Potential problems and deficiencies affecting the estimation of parameter values are discussed.

Animals↗
PubMed1998

Use of a satellite-derived land cover map to estimate transport of radiocaesium to surface waters.

During the weeks to months after the deposition of radioactive fallout, the initial concentration of radioactivity in rivers and lakes declines as a result of flushing and removal to bottom sediments. In the long-term, however, radioactivity in the water body can remain at significant levels as a result of secondary contamination processes. In particular, it is known that soils contaminated by long-lived radionuclides such as 137Cs and 90Sr provide a significant source to surface waters over a period of years after fallout. Using The Land Cover Map of Great Britain, a satellite-derived land cover map as a surrogate indicator of soil type, we have related catchment land cover type to long-term 137Cs activity concentrations in 27 lakes in Cumbria, UK. The study has shown that satellite-derived maps could be used to indicate areas vulnerable to high long-term 137Cs transport to surface waters in the event of a nuclear accident. In these Cumbrian lakes, it appears that residual 137Cs levels are determined by transfers of 137Cs from contaminated catchments rather than within-lake processes. Only three of the cover types, open shrub moor, bog and dense shrub moor, as identified by the satellite, are needed to explain over 90% of the variation in long-term 137Cs activity concentrations in the lakes, and these have been shown to correlate spatially with occurrence of organic soils.

Cesium Radioisotopes↗
PubMed1998

A 16-element phased-array head coil.

Volume-array coils offer increased signal-to-noise ratio (SNR) over standard volume coils near the array elements while preserving the SNR at the center of the volume. As the number of array elements is increased, the SNR advantage as well as the complexity of actually constructing the array increases also. In this study, a 16-channel receive-only array for imaging of the brain is demonstrated and compared to a circularly polarized (CP) head coil of similar shape and diameter. The array was formed from a 2 x 8 grid of square elements placed on a cylindrical form. Mutual coupling was minimized by a combination of overlapping element placement and current-reducing matching networks. Simultaneous data acquisition from the 16 individual elements was performed using a four-channel receiver system with each channel time domain multiplexed by a factor of 4. Theoretical and experimental comparisons between the array and a standard CP head coil show that the array offers an increase in SNR of nearly a factor of 3 near its surface while maintaining a comparable SNR to that of the CP head coil in the center of the region of interest.

Brain↗
PubMed1998

Effects of soy protein on plasma cholesterol and bile acid excretion in hamsters.

The effect of dietary casein and soy protein on lipoprotein metabolism was compared in the Golden Syrian hamster (Mesocricetus auratus). Total plasma cholesterol was similar in animals fed either protein, but significant differences were seen in lipoprotein profile. In animals fed soy protein, cholesterol concentrations were lower in very-low-density lipoproteins (VLDL) but higher in low-density and high-density lipoproteins, compared with those fed casein. Significant differences were also seen depending on the nutritional state of the animals. In casein-fed hamsters, total plasma triacylglycerol and chylomicron + VLDL cholesterol and triacylglycerol were significantly higher when blood was collected during feeding, compared with animals that had been fasted overnight. By contrast, no significant change was seen in animals on the soy protein diet. This suggests that either intestinally derived lipoproteins are more rapidly cleared on the soy protein diet or that soy inhibits feeding-induced VLDL secretion. Fecal bile acid excretion was higher in the soy protein group, and there was a significant correlation between soy intake and bile acid excretion. Hepatic cholesterol decreased as the amount of soy protein consumed increased, suggesting that it is this pool of cholesterol that is used to replace the excreted bile acids. No significant difference was seen in plasma insulin or glucagon between hamsters fed the two proteins. Plasma triiodothyronine concentrations were, however, significantly higher and thyroxine concentrations lower in the soy protein-fed animals. This study shows specific effects of dietary proteins on plasma lipoprotein concentrations dependent on nutritional status of the animal.

Animals↗
PubMed1998

Availability of cardiac technology: trends in procedure use and outcomes for patients with acute myocardial infarction.

This study examines temporal trends in the use and outcomes of cardiac procedures for patients hospitalized with acute myocardial infarction in Department of Veterans Affairs (VA) hospitals with and without invasive cardiac services. Between 1988 and 1994, there was striking overall growth in the use of cardiac procedures in the VA. Over this time period, the authors found persistent variation in the use of cardiac procedures but diminished differences in patient survival among patients admitted to different types of hospitals. Growth of cardiac procedure use and improvements in patient survival were most significant in hospitals without on-site invasive cardiac services. We were unable to determine whether survival gains were associated with increased procedure use or unmeasured improvements in the process of care. These trends raise intriguing questions about access to and outcomes of cardiac procedures in health systems composed of hospitals with and without a full complement of on-site invasive cardiac services.

Acute Disease↗
PubMed1997

Denture treatment for the stroke patient.

This paper is based on a lecture to the joint meeting of the Gerodontic Society and the Community Dental Services Group of the BDA. The difficulties facing stroke patients who require denture treatment are described and recommendations are made to facilitate a successful result.

Aged↗
PubMed1997

Promotion criteria for clinician-educators in the United States and Canada. A survey of promotion committee chairpersons.

CONTEXT: Clinician-educators have concerns about their ability to be promoted and the criteria used by medical school promotion committees. OBJECTIVE: To discover the criteria and methods that medical school promotion committees use to make decisions about the promotion of clinician-educators. METHODS: In June 1996 we mailed a questionnaire to chairpersons of all medical school promotion committees in the United States and Canada. RESULTS: Of 142 schools surveyed, 115 (81%) responded; 45% of respondents had a clinician-educator promotion track. On a scale from 1 (minimally important) to 7 (extremely important), the mean importance ratings of aspects of clinician-educators' performance were the following: teaching skills (6.3), clinical skills (5.8), mentoring (5.7), academic administration (5.3), developing educational programs (5.3), nonresearch scholarship (5.1), clinical research (4.8), service coordination (4.7), and education research (4.5). Methods to evaluate each aspect of performance were rated by respondents for importance and frequency of use. The 4 most important methods for evaluating teaching were awards, peer evaluation, learner evaluation, and teaching portfolio; 70% or more of schools used these frequently or always. The 4 most important methods of evaluating clinical skills were peer evaluation, awards, trainee evaluation, and objective measures, which were used frequently or always by 78%, 65%, 58%, and 29% of schools, respectively. Clinician-educators were expected to have fewer peer-reviewed publications to be promoted than investigators (5.7 vs 10.6, P<.001). Schools with separate clinician-educator tracks differed little in survey responses from schools without such tracks. CONCLUSION: Most, but not all, promotion committees now assign high importance to the special contributions of clinician-educators and use a variety of methods to assess these, regardless of whether they have a separate clinician-educator promotion track.

Canada↗
PubMed1997

Spatial variation in the vulnerability of Norwegian Arctic counties to radiocaesium deposition.

Under the Arctic Monitoring and Assessment Programme (AMAP), studies have been undertaken to compare potential fluxes of radiocaesium via important food products. The results for three Norwegian Arctic counties are presented in this paper. The comparative importance of different foodstuffs in contributing to collective dose varies spatially due to differing rates of production and transfer. Although reindeer meat is an important contributor to the radiocaesium flux following a nuclear release, other food products such as cow milk and lamb have been identified as potentially important. Assuming an even deposition following a nuclear release the radiocaesium flux was estimated to be highest for reindeer meat in Finnmark and Troms, whereas cow milk gave the highest flux in Nordland. The total number, geographical distribution and diet composition of indigenous peoples within different Arctic regions is an important factor affecting individual and collective doses arising from a nuclear release. Finnmark has been shown to be the most vulnerable of the three counties because it has the highest flux of radiocaesium and the largest number of indigenous people. The potential contribution of foodstuffs which are known to readily accumulate radiocaesium needs further consideration, in particular, mushrooms, freshwater fish and berries.

Arctic Regions↗
PubMed1997

Theory and application of array coils in MR spectroscopy.

The theory and application of array coils are reviewed in the context of phased array spectroscopy. The optimization of the signal-to-noise ratio from an array of coils is developed by considering the efficiency of a phased array transmit coil. This approach avoids the need to consider noise correlation, and should be useful in future considerations of transmit phased array coils for MR spectroscopy. Methods to characterize array coil performance, including fields and coupling are briefly summarized, along with methods to minimize the effects of mutual inductance. The signal-to-noise advantages of array coils over single coils are examined for both planar and cylindrical arrays. Numerical simulations of planar arrays of 2 x 2, 4 x 4 and 8 x 8 elements and constant overall dimension are compared to a single coil of the same size. The results demonstrate a significant improvement in sensitivity near the array coil. Although the benefits of the array decrease as a function of distance from the array, the array sensitivity never drops below that of a single coil with the same overall dimensions, or that of a single element of the array. Similar results are obtained for a sixteen element cylindrical array, which is compared to a standard quadrature birdcage coil using both computational methods and phantom measurements. The phased array techniques reviewed are demonstrated with proton spectroscopic images of the brain.

Brain↗
PubMed1997

Oral awareness and ability to detect dental plaque.

Individuals exist who are unaware of the plaque on their teeth and unable to feel with their tongue any difference between tooth surfaces that are smooth and plaque free and those that are irregular or rougher because of a plaque coating. Oral form recognition (OFR), oral roughness discrimination (ORD) and plaque detection ability were examined in 46 undergraduate dental students. Forty-five of the students also completed Form C of Cattell's 16 PF Questionnaire. No relationship was found between the subjects' ability to detect dental plaque and their skills at either distinguishing between different surface roughnesses or recognizing forms orally. The association between personality and oral awareness was unclear.

Adult↗