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Biomedical subjects

W E Wilkinson

Publications and source records attributed to W E Wilkinson.

At least 19 recordsLinked to original sources
PubMed1992

Bidisomide (SC-40230), a new antiarrhythmic agent: initial study of tolerability and pharmacokinetics.

Forty-nine healthy male volunteers received the test article for bidisomide (SC-40230) in a double-blind, placebo-controlled, dose-ranging study. Intravenous doses ranged from 0.03 to 2.5 mg/kg. There was a close relationship between the dose and the peak plasma concentration. The PR, QRS, QT, RR, and QTc intervals each demonstrated a statistically significant response to the dose administered. The PR and QRS intervals lengthened and the other intervals shortened (although to a lesser degree). The compound was well tolerated, with mild symptoms only at higher doses. Bioavailability was studied in 12 male volunteers, with each receiving 2.0 mg/kg of bidisomide, both orally and intravenously, in an open-label crossover trial. After a 10-minute zero-order intravenous infusion, bidisomide plasma levels could best be described in terms of a three-compartment pharmacokinetic model with the mean half-life values of alpha, beta, and gamma phases of 0.12, 1.77, and 12.3 hours, respectively. The mean absolute oral bioavailability was 43%.

Administration, Oral↗
PubMed1992

Treatment of paroxysmal supraventricular tachycardia with oral diltiazem.

Symptomatic paroxysmal supraventricular tachycardia is a troubling arrhythmia for many patients. To test the efficacy of oral diltiazem to reduce symptomatic recurrences of paroxysmal supraventricular tachycardia, we enrolled 17 patients in a double-blind, placebo-controlled crossover study. Sixteen of 17 patients completed a dose-ranging phase and were entered into the randomized phase. Although the time to first recurrence of tachycardia was slightly longer when patients took diltiazem, the difference was not significant (p = 0.15). The hazard ratio of the time to first recurrence on placebo compared with oral diltiazem was 2.7 (95% confidence interval, 0.8 to 9.1). Of the patients who had a recurrence of tachycardia in both treatment periods, the median reduction in heart rate in patients receiving diltiazem was 20 beats/min. (p less than 0.01; 95% confidence interval, 6 to 42).

Administration, Oral↗
PubMed1992

Quantitative cerebral anatomy of the aging human brain: a cross-sectional study using magnetic resonance imaging.

Seventy-six healthy adults underwent magnetic resonance imaging (1.5 T) to investigate the effects of age on regional cerebral volumes and on the frequency and severity of cortical atrophy, lateral ventricular enlargement, and subcortical hyperintensity. Increasing age was associated with (1) decreasing volumes of the cerebral hemispheres (0.23% per year), the frontal lobes (0.55% per year), the temporal lobes (0.28% per year), and the amygdala-hippocampal complex (0.30% per year); (2) increasing volumes of the third ventricle (2.8% per year) and the lateral ventricles (3.2% per year); and (3) increasing odds of cortical atrophy (8.9% per year), lateral ventricular enlargement (7.7% per year), and subcortical hyperintensity in the deep white matter (6.3% per year) and the pons (8.1% per year). Many elderly subjects did not exhibit cortical atrophy or lateral ventricular enlargement, however, indicating that such changes are not inevitable consequences of advancing age. These data should provide a useful clinical context within which to interpret changes in regional brain size associated with "abnormal" aging.

Adult↗
PubMed1992

Occupational injuries: a study of health care workers at a northwestern health science center and teaching hospital.

1. This retrospective study examined the magnitude of the problem of work related health hazards affecting professional and non-professional employees of a state university health science center and hospital. 2. From the 1,513 injury episodes that occurred among the 9,668 employees during the 32 month study period, it was determined that the highest risk categories for both department and job were nursing, housekeeping, food service, and laboratory technicians. 3. Injury rate for females (11.2 per 100 person years) was more than twice that of males (5.1). Injury rates declined from 11.6 per 100 person years at ages 25 to 39 to 3.8 at ages over 60. Puncture wounds (32.7%), mostly by needlesticks, were the most frequently reported injury type, followed by strains and sprains (17.2%), lacerations (12.5%), and contusions (12.1%).

Academic Medical Centers↗
PubMed1991

Mortality in patients treated with flecainide and encainide for supraventricular arrhythmias.

In a recent clinical trial, the class Ic antiarrhythmic drugs encainide and flecainide were found to be associated with an increased mortality risk in patients with new myocardial infarction and ventricular arrhythmias. The purpose of this study was to assess whether an increased mortality risk also accompanied the use of these drugs to treat patients with supraventricular arrhythmias. Data were obtained from the respective pharmaceutical sponsors on the mortality observed with each drug in United States and foreign protocols enrolling patients with supraventricular arrhythmias. Mortality in the encainide population (343 patients) and the flecainide population (236 patients) was compared with that in a research arrhythmia clinic, the Duke population (154 patients). Nine deaths occurred in the combined encainide-flecainide population and 10 deaths occurred in the Duke population; the follow-up periods averaged 488 days and 1,285 days, respectively. The 6-year survival functions of these 2 populations, estimated by the Kaplan-Meier technique, did not differ significantly (p = 0.62). The hazard ratio for the combined encainide-flecainide population relative to the Duke population was estimated to be 0.6 with a 95% confidence interval of 0.2, 1.7. These descriptive comparisons did not demonstrate any excess mortality when flecainide and encainide were used in patients with supraventricular arrhythmias.

Adult↗
PubMed1991

Propafenone treatment of symptomatic paroxysmal supraventricular arrhythmias. A randomized, placebo-controlled, crossover trial in patients tolerating oral therapy.

OBJECTIVE: To test the hypothesis that propafenone, administered orally, prevents symptomatic paroxysmal supraventricular arrhythmias. DESIGN: a 6-month, open-label, dose-finding phase followed by a randomized, double-blind, placebo-controlled, crossover phase, with each treatment period lasting up to 60 days. SETTING: An outpatient clinic. PATIENTS: Thirty-three patients with either paroxysmal supraventricular tachycardia (n = 16) or paroxysmal atrial fibrillation (n = 17) were enrolled. Their arrhythmias were documented by electrocardiogram before enrollment. Twenty-three patients (14 with paroxysmal supraventricular tachycardia and 9 with paroxysmal atrial fibrillation) were randomized and the data obtained from these patients were used in the efficacy analysis. INTERVENTION: Propafenone (300 mg three times daily in 19 patients, 300 mg twice daily in 3 patients, and 150 mg twice daily in 1 patient) and matching placebo tablets were administered in a randomized sequence. MEASUREMENTS: Symptomatic arrhythmia was documented by telephone transmission of the electrocardiogram. MAIN RESULTS: The time to first recurrence was prolonged for the overall group of 23 patients while they received propafenone (P = 0.004). The recurrence rate of arrhythmia during treatment with propafenone was estimated to be approximately one fifth of the recurrence rate during treatment with placebo. CONCLUSIONS: Propafenone is effective in reducing symptomatic paroxysmal supraventricular arrhythmias.

Adult↗
PubMed1991

Brain anatomic effects of electroconvulsive therapy. A prospective magnetic resonance imaging study.

To determine prospectively whether electroconvulsive therapy (ECT) produces structural brain changes, 35 inpatients with depression underwent magnetic resonance imaging before and twice after (at 2 to 3 days and at 6 months) completion of a course of brief-pulse, bilateral ECT. The magnetic resonance images were analyzed blindly for evidence of changes in brain structure using two approaches: measurement of regional brain volumes and a pairwise global comparison. Structural brain abnormalities were present in many patients before ECT. The course of ECT produced no acute or delayed (6-month) change in brain structure as measured by alterations of the total volumes of the lateral ventricles, the third ventricle, the frontal lobes, the temporal lobes, or the amygdala-hippocampal complex. In five subjects, the pairwise global comparisons revealed an apparent increase in subcortical hyperintensity, most likely secondary to progression of ongoing cerebrovascular disease during follow-up. Our results confirm and extend previous imaging studies that also found no relationship between ECT and brain damage.

Amygdala↗
PubMed1990

Occurrence of atrial fibrillation in patients with paroxysmal supraventricular tachycardia due to atrioventricular nodal reentry.

The occurrence of atrial fibrillation in patients with paroxysmal supraventricular tachycardia (PSVT) has been well documented when PSVT is secondary to atrioventricular reentry, but not when PSVT is secondary to atrioventricular nodal reentry (AVNRT). Seventeen patients with AVNRT were followed using transtelephonic electrocardiogram monitoring to document symptomatic tachycardias. The median length of telephone monitor surveillance was 357 days. Fifteen of 17 patients transmitted electrocardiograms that showed PSVT. Three of 17 patients (18%) transmitted electrocardiograms that showed atrial fibrillation. A transition from PSVT into atrial fibrillation was not recorded, but all three did have PSVT recorded on other days of follow-up. We report the occurrence of atrial fibrillation in patients with AVNRT and that its incidence is higher than expected for the general population.

Atrial Fibrillation↗
PubMed1990

MR imaging in patients with temporal lobe seizures: correlation of results with pathologic findings.

Thirty-nine consecutive patients with medically intractable complex partial seizures were studied with electroencephalography and MR imaging to localize an epileptogenic focus for temporal lobectomy. The patients were divided into three groups on the basis of pathologic findings after lobectomy: Group 1 comprised 13 patients with neoplasms, hamartomas, or cysts; group 2 comprised 13 patients with moderate and severe mesial temporal sclerosis (one patient was included in both groups 1 and 2); and group 3 comprised 14 patients who underwent aspiration lobectomy, which yielded limited tissue for pathologic study so no pathologic diagnosis was made. The majority of the patients in group 3 were assumed to have mesial temporal sclerosis. Abnormal MR signal in the temporal lobe on T2-weighted images was graded as minimal increase (1+), intermediate or moderate increase (2+), and very significant increase (3+). An abnormal signal was demonstrated in 26 (67%) of the 39 patients. In group 1, the tumor/cyst subgroup, an abnormal signal was seen in all 13 patients. Most had 3+ signal. There was increased signal in eight (62%) of 13 patients in group 2 and in six (43%) of 14 patients in group 3. This study suggests that MR can detect almost all tumors and a significant number of mesial temporal sclerosis lesions in individuals with complex partial seizures. On the basis of this small series, individuals who exhibit significant signal (3+) can be expected to have neoplasms, hamartomas, or cysts, and patients who exhibit minimal signal (1+) will usually have mesial temporal sclerosis.

Adult↗
PubMed1990

Regional cerebral blood flow measurement in humans by xenon-133 clearance.

Almost 30 years have passed since the first measurement of regional cerebral blood flow in humans by 133Xe clearance. A review of the methodology is presented for the two-dimensional intracarotid method and the related inhalation and IV injection techniques. Emphasis is placed on the mathematical models employed and the blood flow indices derived from them. Similarities and differences between methods are described, and the contribution of each to clinical research is summarized.

Brain↗
PubMed1990

A conceptual model of occupational health nursing.

Occupational health nurses can practice and research in their profession better if they approach occupational health nursing with a well developed conceptual model. The Wilkinson Windmill Model is one conceptualization of occupational health nursing an occupational health nurse may use for guidance in practice, research, and education. The model consists of five primary components. This conceptual model may be a useful framework for understanding the role of the occupational health nurse in many different environments and may prove valuable as a tool for conducting research.

Humans↗
PubMed1990

Oral contraceptives and breast cancer: a case-control study with hospital and community controls.

Several recent reports have noted an increase risk of breast cancer associated with the use of oral contraceptives (OCs) among various subgroups of young women. These reports spurred us to analyze data from a case-control study in North Carolina of 158 breast cancer patients, 326 hospital controls, and 1140 community controls less than 60 years of age. A logistic regression model was used to calculate odds ratios and 95% confidence intervals and to control for potential confounders. No association between ever-use of OCs and the risk of breast cancer was found for cases compared with either control group. No increased risk was observed for OC use before age 25 or before first full-term pregnancy, or in relation to duration of use, recency of use, or time since first use. Analysis of the subgroup of women less than 45 years of age also showed no relationship between OC use and breast cancer risk. However, an elevated risk of breast cancer was observed among nulliparous women with 5 or more years of OC use in comparisons with hospital controls (odds ratio 7.8) and community controls (odds ratio 2.3). This analysis was based on small numbers of subjects and the 95% confidence intervals touched or overlapped with 1. An unexpected association between duration of OC use and breast cancer risk was found among older premenopausal women in comparisons of cases with both control groups. For these women, a trend was evident in the odds ratio by duration of OC use, and the comparison between cases and community controls was statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Random and nonrandom behavior of symptomatic paroxysmal atrial fibrillation.

Little is known about the behavior of symptomatic paroxysmal atrial fibrillation (AF). The nature of the process formed by the successive occurrences of this arrhythmia was studied in 8 patients with a history of symptomatic paroxysmal AF. Trans-telephonic monitoring of the electrocardiogram was used to document the cardiac rhythm during symptoms. Patients were followed while successive attacks of paroxysmal AF were documented. A minimum of 12 and a maximum of 26 consecutive episodes of symptomatic paroxysmal AF were recorded from the 8 patients during 66 to 332 days. Methods developed in industrial reliability theory were used to show that, for the overall group of 8 patients, the interevent times between successive occurrences of symptomatic AF were not independent. However, for a subgroup including 6 of the patients, the interevent times were independent and governed by an exponential probability distribution. Differences in observed behavior of symptomatic AF may relate to differences in underlying mechanism within patients.

Adult↗
PubMed1988

Changes in serum lipids in patients with condylomata acuminata treated with interferon alfa-n1 (Wellferon).

Nine men with refractory condylomata acuminata were treated with intramuscular interferon alfa-n1 and the effect on their serum lipid levels was noted. Comparison of lipid panels before and after interferon revealed that all nine patients had an increase (median 62 mg/dl, p = 0.004) in their triglyceride level and a decrease (median 21 mg/dl, p = 0.004) in high-density lipoprotein cholesterol levels. Total cholesterol levels tended to decrease but the change was not statistically significant. This effect on serum lipids should be considered when interferon alfa-n1 is used in the treatment of genital warts.

Cholesterol↗
PubMed1988

Effects of image processing on nodule detection rates in digitized chest radiographs: ROC study of observer performance.

To evaluate the effects of image processing in digitized chest radiographs when high-resolution images are used, an examination was done in which the detection of pulmonary nodules in unprocessed digitized chest radiographs was compared with that in images that had undergone processing with two methods, adaptive filtration and histogram equalization. The processing techniques have been optimized in previous work to selectively enhance the retrocardiac and subdiaphragmatic areas without significant alteration of detail in the lung. Eight observers were shown 150 test radiographs (50 unprocessed, 50 processed with adaptive filtration, 50 processed with histogram equalization) containing 150 nodules. The results indicate a statistically significant (P less than .03) difference, with highest observer performance in the chest radiographs processed with adaptive filtration (median area under ROC curve = 0.78), compared with unprocessed images (median = 0.68) and chest radiographs processed with histogram equalization (median = 0.62). Performance in the lung was not significantly different. Adaptive filtration applied to selectively enhance underexposed areas of film images may improve nodule detection. Histogram equalization provided no improvement in performance.

Filtration↗