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Biomedical subjects

R A Neill

Publications and source records attributed to R A Neill.

At least 19 recordsLinked to original sources
PubMed2001

Journal article content as a predictor of commitment to change among continuing medical education respondents.

BACKGROUND: Journal reading is a time-tested means of continuing medical education (CME) among physicians. Asking physicians to make a written statement of commitment to change has been shown to increase the likelihood of eventual change in practice behavior when used in conjunction with CME lectures. We describe the type and medical content of articles responsible for commitment to change comments among readers of a large circulation primary care journal. METHODS: Response to the question "what change(s) do you plan to make in your practice as a result of reading the articles in this issue?" were analyzed from CME response cards associated with six issues (1 year's publication) of the Archives of Family Medicine. Responses indicating a commitment to change were analyzed to characterize the type and content of articles responsible for their generation. RESULTS: During the 1-year study period, original contributions (reports of research trials) dealing with medicine and preventive medicine content accounted for the greatest number of comments. After adjusting for the frequency of article type and content, special articles and those dealing with complementary medicine accounted for the highest number of comments on a per-article basis. FINDINGS: Family physicians make commitment to change statements on the basis of a broad range of journal articles. Certain articles are more likely to generate statements of commitment to planned changes in practice.

Education, Medical, Continuing↗
PubMed2001

Effects of antecedent prolonged exercise on subsequent counterregulatory responses to hypoglycemia.

In the present study the hypothesis tested was that prior exercise may blunt counterregulatory responses to subsequent hypoglycemia. Healthy subjects [15 females (f)/15 males (m), age 27 +/- 1 yr, body mass index 22 +/- 1 kg/m(2), hemoglobin A(Ic) 5.6 +/- 0.5%] were studied during 2-day experiments. Day 1 involved either 90-min morning and afternoon cycle exercise at 50% maximal O2 uptake (VO2(max)) (priorEXE, n = 16, 8 m/8 f) or equivalent rest periods (priorREST, n = 14, 7 m/7 f). Day 2 consisted of a 2-h hypoglycemic clamp in all subjects. Endogenous glucose production (EGP) was measured using [3-3H]glucose. Muscle sympathetic nerve activity (MSNA) was measured using microneurography. Day 2 insulin (87 +/- 6 microU/ml) and plasma glucose levels (54 +/- 2 mg/dl) were equivalent after priorEXE and priorREST. Significant blunting (P < 0.01) of day 2 norepinephrine (-30 +/- 4%), epinephrine (-37 +/- 6%), glucagon (-60 +/- 4%), growth hormone (-61 +/- 5%), pancreatic polypeptide (-47 +/- 4%), and MSNA (-90 +/- 8%) responses to hypoglycemia occurred after priorEXE vs. priorREST. EGP during day 2 hypoglycemia was also suppressed significantly (P < 0.01) after priorEXE compared with priorREST. In summary, two bouts of exercise (90 min at 50% VO2(max)) significantly reduced glucagon, catecholamines, growth hormone, pancreatic polypeptide, and EGP responses to subsequent hypoglycemia. We conclude that, in normal humans, antecedent prolonged moderate exercise blunts neuroendocrine and metabolic counterregulatory responses to subsequent hypoglycemia.

3-Hydroxybutyric Acid↗
PubMed2001

Effect of morning exercise on counterregulatory responses to subsequent, afternoon exercise.

The aim of this study was to determine whether a bout of morning exercise (EXE(1)) can alter neuroendocrine and metabolic responses to subsequent afternoon exercise (EXE(2)) and whether these changes follow a gender-specific pattern. Sixteen healthy volunteers (8 men and 8 women, age 27 +/- 1 yr, body mass index 23 +/- 1 kg/m(2), maximal O(2) uptake 31 +/- 2 ml x kg(-1) x min(-1)) were studied after an overnight fast. EXE(1) and EXE(2) each consisted of 90 min of cycling on a stationary bike at 48 +/- 2% of maximal O(2) uptake separated by 3 h. To avoid the confounding effects of hypoglycemia and glycogen depletion, carbohydrate (1.5 g/kg body wt po) was given after EXE(1), and plasma glucose was maintained at euglycemia during both episodes of exercise by a modification of the glucose-clamp technique. Basal insulin levels (7 +/- 1 microU/ml) and exercise-induced insulin decreases (-3 microU/ml) were similar during EXE(1) and EXE(2). Plasma glucose was 5.2 +/- 0.1 and 5.2 +/- 0.1 mmol/l during EXE(1) and EXE(2), respectively. The glucose infusion rate needed to maintain euglycemia during the last 30 min of exercise was increased during EXE(2) compared with EXE(1) (32 +/- 4 vs. 7 +/- 2 micromol x kg(-1) x min(-1)). Although this increased need for exogenous glucose was similar in men and women, gender differences in counterregulatory responses were significant. Compared with EXE(1), epinephrine, norepinephrine, growth hormone, pancreatic polypeptide, and cortisol responses were blunted during EXE(2) in men, but neuroendocrine responses were preserved or increased in women. In summary, morning exercise significantly impaired the body's ability to maintain euglycemia during later exercise of similar intensity and duration. We conclude that antecedent exercise can significantly modify, in a gender-specific fashion, metabolic and neuroendocrine responses to subsequent exercise.

Adult↗
PubMed2000

Effects of differing durations of antecedent hypoglycemia on counterregulatory responses to subsequent hypoglycemia in normal humans.

The aim of this study was to determine whether the duration of antecedent hypoglycemia regulates the magnitude of subsequent counterregulatory failure. A total of 31 lean healthy overnight-fasted individuals (16 men/15 women) were studied. There were 15 subjects (8 men/7 women) who underwent two separate 2-day randomized experiments separated by at least 2 months. On day 1, 2-h hyperinsulinemic (9 pmol x kg(-1) x min(-1)) euglycemic (5.2 +/- 0.1 mmol/l) or hypoglycemic (2.9 +/- 0.1 mmol/l) glucose clamps (prolonged hypoglycemia) were carried out in the morning and afternoon. Of the other subjects, 16 participated in a 2-day study in which day 1 consisted of morning and afternoon short-duration hypoglycemia experiments (hypoglycemic nadir of 2.9 +/- 0.1 mmol for 5 min), and 10 of these individuals underwent an additional 2-day study in which day 1 consisted of morning and afternoon intermediate-duration hypoglycemia (hypoglycemic nadir of 2.9 +/- 0.1 mmol for 30 min). The next morning (day 2) all subjects underwent an additional 2-h hyperinsulinemic-hypoglycemic clamp (2.9 +/- 0.1 mmol/l). The rate of fall of glucose (0.07 mmol/min) was carefully controlled during all hypoglycemic studies so that the glucose nadir was reached at 30 min. Despite equivalent day 2 plasma glucose and insulin levels, there were significant differences in counterregulatory physiological responses. Steady-state epinephrine, glucagon, growth hormone, cortisol, and pancreatic polypeptide levels were similarly significantly blunted (P < 0.01) by the differing duration day 1 hypoglycemia compared with day 1 euglycemia. Muscle sympathetic nerve activity and endogenous glucose production were also similarly blunted (P < 0.01) by day 1 hypoglycemia (relative to day 1 euglycemia). Day 2 hypoglycemic symptoms were significantly reduced (P < 0.01) after day 1 prolonged intermediate- but not short-duration hypoglycemia. In summary, two episodes of short-duration moderate hypoglycemia can produce significant blunting of key neuroendocrine and metabolic counterregulatory responses. Hypoglycemic symptom scores are reduced by prolonged but not short-duration prior hypoglycemia. We conclude that in healthy overnight fasted humans, 1) neuroendocrine, autonomic nervous system, and metabolic counterregulatory responses are sensitive to the blunting effects of even short-duration prior hypoglycemia, and 2) the duration of antecedent hypoglycemia results in a hierarchy of blunted physiological responses with hypoglycemic symptom awareness less vulnerable than neuroendocrine responses.

Adult↗
PubMed1997

Illustrations and implications of current models of HIV health service provision in rural areas.

Despite recent evidence of faster than average increases in HIV/AIDS cases in rural areas across the U.S., there is still a generally poor understanding of successful models of rural HIV/AIDS health-care delivery. Past research in rural Kentucky suggested several barriers to care resulting in most rural HIV-positive patients traveling from rural to urban areas for care. Patients sought urban areas for care for reasons including patient confidentiality, a perceived lack of expertise on the part of rural physicians in caring for HIV-positive patients, and outright referral from rural to urban areas. Case histories are used to illustrate a variety of models of care used by rural HIV-positive patients. These include splitting and sharing care between rural primary care physicians and urban medical specialists, as well as patients receiving all their care in urban areas. Implications of these models for quality of care are discussed.

Adult↗
PubMed1995

Frequency of human immunodeficiency virus testing among rural US residents and why it is done.

OBJECTIVE: To examine the frequency with which rural residents' undergo human immunodeficiency virus (HIV) antibody testing and the reasons why. DESIGN: Data are from the 1991 National Health Interview Survey's supplemental questions on knowledge and attitudes about acquired immunodeficiency syndrome. SUBJECTS: The respondents were 42,725 adults (aged > or = 18 years), representing a nationwide sample of the civilian, noninstitutionalized population of the United States. Rural (n = 9903) and urban (n = 32,822) respondents were compared. RESULTS: Although 7.1% of rural and 7.9% of urban respondents are at high risk for contracting HIV (P = .06), 25.2% of rural and 33.0% of urban respondents had been tested for HIV (P = .001). Excluding blood donations, 10.7% of rural and 17.2% of urban respondents had been tested for HIV (P = .001). The primary reason between the two groups for not getting tested was a belief of being at low risk for contracting HIV. Rural respondents were less likely than urban respondents (6.6% vs 10.4%) (P = .001) to be tested for HIV in the next 12 months. Rural respondents were less informed about HIV risks than were urban respondents. Urban residence is a significant predictor of having had an HIV test even after controlling for actual risk status, perceived risk status, age, education, income, sex, perceived health status, and a scale of knowledge of acquired immunodeficiency syndrome risk factors (odds ratio, 1.54; 95% confidence interval, 1.37 to 1.73). CONCLUSIONS: Rural residents are less knowledgeable about HIV risk factors and are less likely to have been tested for HIV. With the increasing rates of infection in rural areas, specific and focused efforts for counseling and testing for HIV antibodies in rural areas might prevent and control HIV infection and acquired immunodeficiency syndrome.

Adult↗
PubMed1994

The utility of electronic mail as a medium for patient-physician communication.

OBJECTIVE: To examine patients' knowledge, use, and attitudes regarding electronic mail communication with their family physicians. DESIGN: Mail survey. SETTING: A university-based family practice center. PARTICIPANTS: Adult patients (18 years and older) of full-time faculty physicians at a university-based family practice center who had seen their physicians at lease once in the 10-month period between July 1, 1992, and April 30, 1993 (N = 4094). Subjects were eligible for participation if both they and their physicians had an electronic mail address at the University of Kentucky, Lexington (n = 117). INTERVENTION: None. MAIN OUTCOME MEASURES: Patient-reported knowledge, use, and attitudes regarding the utility of electronic mail as a means of patient-physician communication. RESULTS: The response rate to the survey was 74% (n = 87). Patient-physician communication via electronic mail was positively perceived by patients for whom electronic mail was accessible Patient-physician communication via electronic mail was perceived to increase speed, convenience, and access to medical care. Electronic mail communication was perceived to be good for simple and nonurgent problems, such as refilling prescriptions, communicating laboratory results, and making appointments. Ninety percent of the patients who had corresponded with their physicians via electronic mail used the medium to discuss a medical problem. CONCLUSIONS: Although electronic mail is not presently in wide use for patient-physician communication, there is great potential for its widespread acceptance.

Attitude↗
PubMed1992

Effects of flicker modulation depth on the detection of changes in target location.

Response times to a change in location of a small, low contrast target in a uniform flickering field were investigated under a range of flicker modulation depths. Increasing depth of modulation gave an increased response time for modulation depths from 0% (no flicker, to approx. 35%. Further increases in modulation depth had only a marginal effect on response time. It is shown that this effect is not due to flicker adaptation. The functional form of the modulation dependence is qualitatively similar to that reported by Badcock and Smith (1989, Vision Research, 29, 803-808), but shows a large difference in the modulation at which a levelling of performance occurred. It is shown that this difference is consistent with the presence of a third temporal filter, as proposed by Mandler and Makous (1984, Vision Research, 24, 1881-1887).

Adult↗
PubMed1992

Temporal relationships between induced changes in c-myc mRNA abundance, proliferation, and differentiation in HL60 cells.

Changes in the relative abundances of c-myc mRNA have been related to changes in other parameters of differentiation (histochemical, clonogenic) during the course of the differentiation of HL60 cells to monocytes/macrophages or to granulocytes. Induction of differentiation to monocytes/macrophages was marked by a rapid rate of appearance of committed cells (80 to 90% in 24 hours) and a concomitant rapid loss of c-myc mRNA. Induction of granulocytic differentiation resulted in a much slower rate of appearance of committed cells (50% in 48 hours), and a much faster rate of loss of c-myc mRNA (tenfold in 1 hour). These data are consistent with there being a direct link between down-regulation of the expression of c-myc and the onset of proliferation arrest and monocytic differentiation, but show there is no such association of c-myc mRNA abundance and proliferation or differentiation during the maturation of HL60 granulocytes.

Cell Differentiation↗
PubMed1991

Discrimination of motion in depth trajectory following acute alcohol ingestion.

Evoked potentials were recorded at four scalp sites O1, O2, T5, T6; before and after the consumption of one of two alcohol dose levels, to the occurrence of disparate stimuli in dynamic random dot stereograms. Twenty young adult subjects, all of whom had vision which was normal or corrected to normal, were randomly assigned to the two dosage groups. Subjects viewed stimuli which embodied crossed disparity and followed one of three trajectories in depth. The task was to distinguish between and identify, by specific button presses, these trajectories. One half of the stimuli were presented with monocular cues to motion in depth (dark condition); in the remainder only stereoscopic depth information was available (uniform condition). Responses to both conditions showed alcohol-related reduction of evoked responses across all sites. It was concluded that the visual systems associated with the processing of motion in depth were susceptible to alcohol effects, as revealed by reductions in the amplitude of evoked responses.

Adult↗
PubMed1990

Detecting target shifts under uniform field flicker.

An experiment was performed in which a small target, viewed foveally, underwent 1 degree lateral shifts at quasi-random intervals. Subjects' response latency to the shift was investigated under various square-wave flicker conditions and compared to non-flickering conditions. Flicker was found to raise latencies, the effect peaking between 8 and 14 Hz. Under constant luminance difference between target and background the high target contrast phase was found to dominate the response cueing. The results are discussed in terms of a simple model of cumulative signal strength and adaptation processes.

Adult↗
PubMed1988

Scalp response topography to dynamic random dot stereograms.

Responses were recorded to dynamic random dot stereograms from 32 sites (acquired in separate 8-channel montages). The disparate stimulus comprised a central, 3 degrees square of 30 arc min crossed disparity, superimposed on a 10.7 degrees square background field. Stimulus onset occurred 100 msec into a 500 msec recording epoch, with a 100 msec stimulus duration. Wave forms for 8 subjects were normalised across the 100 msec pre-stimulus period. Average amplitudes were calculated for the post-onset intervals: 120-140, 140-180, 180-220, 220-260 and 260-300 msec. Contour lines of evoked response amplitude were plotted from these data. These plots are compared with theoretical plots generated from a '3 concentric sphere' model of the head. The results lend support to the proposal that preliminary stereoscopic processing takes place in the primary visual cortex, followed by secondary processing in more anterior cortical regions.

Adult↗
PubMed1988

Component enhancement through temporal compression and expansion of event-related potentials.

A technique is described in which wave forms are temporally compressed or expanded to provide optimal correlation with a superaveraged template. In certain instances, this filter can be applied more appropriately than other filters which shift or rotate wave forms. A 2-part experiment was carried out in which the efficacy of the filter was evaluated for responses of (a) moderate size and consistent latency, and (b) small amplitude and variable latency. The filter was effective in enhancing data for the small, variable responses while it had no significant effect on more consistent data. Possible functional interpretations of latency adjustment techniques are presented.

Adult↗
PubMed1988

The determinants of the non-motoric CNV in a complex, variable foreperiod, information processing paradigm.

The aim of the present study was to examine the determinants of the non-motoric CNV or E-wave elicited in a complex, variable foreperiod information processing task. Subjects were required to determine whether two sets of tones, one set presented back-to-back (S1/S2), the other separated by a variable foreperiod (S3/S4), were either matching or mismatching. Data were collected over two recording sessions; a baseline and an experimental run. The experimental session comprised three conditions; a match, a mismatch and no-response conditions. Mean amplitude and factor score comparisons showed the parietally-dominant E-wave to be dependent on the task relevance of the stimulus which it precedes. Differing midline distributions for the negative afterwave and the E-wave with increased processing requirements was taken to suggest that the two responses reflect functionally distinct phenomena.

Adult↗
PubMed1988

Stereoscopic evoked responses to crossed and uncrossed disparity accompanying simulated refractive error.

Evoked potentials were recorded to the occurrence of a disparate stimulus in dynamic random dot stereograms. Seven adult males, all of whom had vision which was normal or corrected to normal, participated in the experiment. Subjects viewed 100 ms duration stimuli which embodied 30 arc min of either crossed or uncrossed disparity under four conditions of spherical overcorrection: -0.25, +1.0, +2.0, +3.0 dioptres. The first condition, essentially normal refraction, yielded reliable behavioural reports of the stimulus and clear evoked potentials to both crossed and uncrossed disparity. With increasing overcorrection the behavioural reports became less reliable, and the evoked potentials were degraded for both conditions of disparity. The responses to the crossed disparity condition, however, showed significantly less degradation in both behavioural and electrophysiological measures. The implications of this finding may be that there are separate cortical subsystems for the processing of crossed and uncrossed disparity and that the former is more robust under non-ideal viewing conditions.

Adult↗
PubMed1987

Effects of movement in the background field on long-range apparent motion.

Two experiments are reported using time-till-breakdown as a measure of apparent motion (AM) in untrained subjects. In Experiment 1 centrally viewed dynamic random dot stereograms and non-disparate stimuli in dynamic random dot fields yielded higher optimal frequencies than did a standard binocular condition. In Experiment 2 a higher optimal frequency was observed for disparate dynamic random dot stimuli compared with both standard binocular and non disparate stimuli presented on a static random dot field. Interaction between short- and long-range AM processes is considered in the interpretation of the findings.

Depth Perception↗
PubMed1987

Detection threshold differences to crossed and uncrossed disparities.

Using a sample of 85 subjects measurements were made of minimum stimulus durations necessary for detection of crossed and uncrossed disparity stimuli which were presented in five positions in the visual field: centre, lower, upper, right, and left field. The results indicated large detection duration differences between the two disparity conditions, with a marked superiority for crossed disparity detection at all positions. A left-right visual field anisotropy was demonstrated for crossed disparity stimuli.

Depth Perception↗