Search PubMed⌕ Search

Biomedical subjects

R A Davidson

Publications and source records attributed to R A Davidson.

At least 19 recordsLinked to original sources
PubMed1992

Newer tests for the diagnosis of renovascular disease.

OBJECTIVE: To evaluate published reports of diagnostic methods for renovascular hypertension, including Doppler ultrasonography, magnetic resonance imaging, the captopril test, and captopril scanning. DATA SOURCES: MEDLINE and selected references from appropriate published articles. STUDY SELECTION: Studies included those that calculated sensitivities and specificities; studies that derived diagnostic criteria without application to another population of patients were excluded. Consensus of both authors was necessary for inclusion. DATA EXTRACTION: Articles were critically assessed independently by the authors and a consensus critique was developed. DATA SYNTHESIS: Major sources of variability exist in the investigations of recently developed tests for renovascular hypertension. These include variability in patient populations, performance of tests, and determination of outcome measures. CONCLUSIONS: Among the newer diagnostic tests, both magnetic resonance imaging and Doppler ultrasonography hold promise for the anatomic detection of renal artery stenosis, but clear diagnostic criteria have not been universally accepted. There is more information concerning the captopril test, which has a sufficiently high sensitivity to be useful in the screening of high-risk patients for renovascular hypertension. Scans after captopril administration, which appear to be more specific, may enable the prediction of a blood pressure response to angioplasty or surgery.

Captopril↗
PubMed1992

Lateralized mediation of arousal and habituation: differential bilateral electrodermal activity in unilateral temporal lobectomy patients.

The purpose of the present study was to increase our understanding of the differential hemispheric processing of arousal and habituation. Subjects were unilateral temporal lobectomy patients and controls. Each was exposed to an arousal/habituation task consisting of a series of tones and an auditory discrimination paradigm. Electrodermal activity was recorded from the left and right hands throughout. Results provide evidence for a state of hypoarousal in right temporal patients and some support for hyperarousability in lefts. This is consistent with data showing that right hemisphere damage is associated with inattention and denial and left hemisphere damage with hypervigilance and anxiety. The concept of laterally differentiated mediation of arousal and habituation was supported.

Adult↗
PubMed1992

Reduction of caregiver stress by respite care: a pilot study.

The purpose of this study was to determine whether providing respite care to persons with Alzheimer's disease and other dementias decreased stress and mood disturbances in caregivers. Caregivers of persons receiving respite care (n = 7), and not receiving respite care (n = 8) were tested at entry into the study and at 5 weeks and 10 weeks, using the Profile of Mood States and the Relative's Stress Scale. Using repeated measures analysis of variance, a downward trend for study subjects and an upward trend for controls was found for Relative's Stress Scores. Similar trends were found on the Personal Distress Subscale of the Relative's Stress Scale. No difference occurred in rates of institutionalization between those receiving and not receiving day care. Our study suggests that respite care for demented persons living at home significantly reduces the stress among caregivers.

Affect↗
PubMed1991

Caffeine and novelty: effects on electrodermal activity and performance.

Caffeine has been shown to affect both physiological functioning and certain aspects of performance. These effects are typically attributed to a simple increase in general arousal. The present study was based on the theory that the effects of caffeine are actually multidimensional. Specifically, we hypothesized that the drug raises arousal, acts to maintain elevated arousal under conditions otherwise conductive to habituation, and enhances the impact of situational and psychological sources of arousal. Subjects were given caffeine (300 mg) or placebo and white noise or no noise and exposed to a series of pure tones and two Backwards Recall Tasks, one novel, the other repetitive. Electrodermal activity (EDA) and task performance were recorded. Caffeine increased arousal as measured by EDA. It also acted to slow habituation during repetitive stimulation, thus maintaining heightened arousal. Finally, it enhanced the effects of novel stimulation, which also independently raised arousal. These results support a multidimensional theory of caffeine effects and provide some understanding of the popularity of caffeine as a psychotropic agent.

Acoustic Stimulation↗
PubMed1991

Magnetic resonance imaging in the evaluation of knee injuries.

To better define the role of magnetic resonance imaging (MRI) in the evaluation of knee injuries, we analyzed 10 recently published articles comparing MRI and arthroscopy in the detection of meniscal and anterior cruciate ligament tears. Sensitivity (SN), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) for medial meniscus (MM) tears, lateral meniscus (LM) tears, and anterior cruciate ligament (ACL) tears were either obtained or calculated from data contained in each article. The medians of measurements for MM tears were 97% SN, 89% SP, 88% PPV, and 96% NPV. Measurement medians for LM tears were 85% SN, 94% SP, 86% PPV, and 95% NPV. ACL tear measurement medians were 100% SN, 96% SP, 80% PPV, and 98% NPV. High NPVs were found in several studies, many of which were 100%. The high NPV of MR imaging suggests that diagnostic arthroscopic surgery is not necessary in the evaluation of patients with negative MRI studies. The superior sensitivity of MRI in detecting frank posterior horn tears, intrasubstance meniscal tears, and significant incidental findings also suggests that screening MRI scans can facilitate preoperative planning.

Arthroscopy↗
PubMed1990

Sensation-seeking: electrodermal and behavioral effects of stimulus content and intensity.

Although a number of studies support an arousal theory interpretation of differential sensation-seeking behavior, the conditions under which arousal correlates of this personality dimension are manifest is as yet unclear. Both theory and research suggest that among the external factors affecting the differential arousal response are stimulus relevance and stimulus intensity. The present study assessed the impact of these factors on both psychophysiological and behavioral responses. Subjects were preselected to represent the extremes of the sensation-seeking dimension, then exposed to auditory and visual presentations of a series of sexual and aggressive stimuli of systematically varied intensity. High sensation seekers gave larger amplitude SCRs to violent stimuli and larger initial responses to sexual stimuli presented visually, while verbal response intensities showed an opposite pattern. Overall, results provided support for an arousal theory interpretation of sensation-seeking, but suggested that the probability and magnitude of group differences is a somewhat complex function of stimulus intensity, stimulus modality, and perhaps other factors not yet assessed.

Adult↗
PubMed1989

Hypertension in the elderly.

Based on the best evidence we have currently, treating the elderly patient with diastolic hypertension will significantly decrease the risk of stroke. While the evidence for decreasing the risks of coronary disease, congestive heart failure, renal insufficiency, or total mortality is not present, such evidence does exist in younger patients with more severe hypertension. Thus, it is of benefit to reduce the blood pressure in hypertensive older patients. There is some evidence that the elderly may not be more susceptible to side effects of antihypertensive medications than younger populations. However, it is certainly reasonable to attempt blood pressure control by nonpharmacologic means prior to drug treatment. Demographic considerations may affect the choice of medication; in general the stepped-care approach will provide effective management of elevated blood pressure in this population.

Aged↗
PubMed1989

Changes in the educational value of inpatients at a major teaching hospital: implications for medical education.

Authors of recent studies have expressed concern about the adequacy of training for internal medicine housestaff, because a number of economic factors may be affecting the case mix on inpatient services. Major alterations in training programs have been recommended, including more training in ambulatory settings and minimizing house staff responsibility for procedure-oriented admissions. Almost no data have been collected regarding actual case-mix changes. In 1987, the author asked the faculty members of the Department of Medicine at the University of Florida College of Medicine to assess the educational value of two groups of patients admitted to the same hospital 15 years apart, one group in 1971 and the other in 1986; the faculty members were not told the difference in dates or the study hypothesis. They found the group of patients from 1971 to have significantly greater educational value than the group from 1986. There were no differences in the estimations of "sickness" of the two groups of patients. These findings support the hypothesis that changes in patient populations resulting from recent economic changes may have diminished the educational value of medical inpatients in academic settings.

Adult↗
PubMed1989

Incidence of hypertension in an ambulatory elderly population.

Investigations of the natural history of blood pressure have generally evaluated mean systolic and diastolic pressure changes. While information, this information is not directly applicable to clinical practice settings, in which patients are usually classified as normotensive or hypertensive. We measured the actual incidence of hypertension, using two different definitions, in an ambulatory elderly population of 2,584 individuals over an 8-year period. Using the less stringent blood pressure definition (systolic blood pressure greater than 140 mmHg and diastolic blood pressure greater than or equal to 90 mmHg), 884 (34.2%) participants were normotensive and 1,700 (65.8%) were hypertensive at an initial screening. The average annual incidence of hypertension over the subsequent eight years was 13.2%, and life tables demonstrated a gradual risk of developing hypertension. The development of hypertension was not associated with gender or age; while older age groups had a greater chance of developing hypertension than younger, the difference did not reach statistical significance.

Age Factors↗
PubMed1988

Strongyloides stercoralis infection in the ferret.

The ferret (Mustela putorius furo) was evaluated as an animal model for infection with human strains of Strongyloides stercoralis. Results indicate that such infections can be easily and reproducibly accomplished.

Animals↗
PubMed1987

Should the elderly hypertensive be treated? Evidence from clinical trials.

Clinical trials for over 15 years have addressed the therapeutic utility of treating elderly hypertensives. Many early trials showed no treatment effects. Because of the recent publication of new information, a review of available evidence concerning this issue was undertaken. Eight randomized clinical trials were assessed regarding trial design. The studies varied according to generalizability, diagnostic criteria, choice of therapy, outcome measures assessed, evaluation of compliance, methods of analysis, duration of follow-up, determination of side effects, and ability to exclude a type 2 error. While many of the earlier studies found no treatment effects, they lacked methodologic rigor; more recent studies demonstrated positive treatment effects. Pooling of results from similar trials supports a notable treatment effect in the prevention of stroke. There is also evidence that the elderly are not more susceptible to side effects of antihypertensive drugs, as is generally believed. The best evidence suggests the hypertensive elderly should be treated.

Aged↗
PubMed1986

Initial treatment of hypertension: a questionnaire survey.

The "stepped care" (SC) approach to the management of hypertension has been the standard of care for many years. Recently, concerns about safety of diuretics, coupled with the development of a variety of new antihypertensive agents, have led to questions about the continued use of SC. It is unclear what effect this continuing debate has had on the initial selection of drugs to treat mild to moderate hypertension. We developed four vignettes intended to represent typical patients with mild to moderate hypertension and asked three groups of physicians (house staff, faculty physicians, and private practitioners) how they would initially treat the patients represented by the vignettes. Ninety-five physicians responded. Among the physicians who chose a drug therapy for a vignette (85.9% of total responses), 81.2% selected either a diuretic or a beta-blocking agent, the standard SC regimen. Differences among the groups of physicians dealt with decisions to treat rather than choice of drugs, although house officers tended to use slightly more beta blockers and non-SC drugs. In spite of recent criticism of the SC approach, many physicians are comfortable with the use of diuretics or beta-blocking agents as the initial treatment of mild to moderate hypertension.

Antihypertensive Agents↗
PubMed1985

Immunology of parasitic infections.

Most parasites, by the nature of their continuous contact with the immune system, generate a prolific immune response. Unfortunately, much of this response is not protective, and some is harmful. Protective immunity in some infections is due to a combination of humoral and cellular immunity; in this circumstance parasites are coated with antibody which makes them susceptible to direct cytotoxicity by macrophages, eosinophils, and neutrophils. Antibody alone is protective against some other infections. Nonspecific and genetic factors are clearly important but are still undefined participants in the host response. The immune response may be pathogenic by inducing hypersensitivity, immunologically mediated fibrosis, or circulating immune complexes. Additionally, parasites have evolved unique ways of protecting themselves from the immune system, including altering their antigenic coat and inducing immunosuppression. Attempts to isolate "host-protective" antigens in parasitic infections may lead to effective vaccine development.

Animals↗
PubMed1984

Risk factors for strongyloidiasis. A case-control study.

Although infection with Strongyloides stercoralis is usually only mildly symptomatic, it can persist for many years and occasionally progress to the hyperinfection syndrome, with a resultant high mortality rate. We studied factors associated with S stercoralis infection by comparing 28 domestic cases of S stercoralis infection with 76 controls with negative stool samples for ova and parasites. The relative risk (RR) of S stercoralis infection was increased for white patients (RR = 5.6), men (RR = 3.9), and patients who had recently used corticosteroids (RR = 3.3), had a hematologic malignancy (RR = 5.28) or had prior gastric surgery (RR = 11.5). These risk factors might be for initial infection, persistence of infection, or both. Although they are not necessarily causal, knowledge of them may lead to earlier recognition of this dangerous and treatable disease.

Adrenal Cortex Hormones↗