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Biomedical subjects

W Hooper

Publications and source records attributed to W Hooper.

15 recordsLinked to original sources
PubMed2000

The effect of body size on the metabolic clearance of carbamazepine.

OBJECTIVES: To examine the profile of the known pathways of carbamazepine (CBZ) metabolism in a group of children and adolescents, and to test for associations with physical measurements, age and plasma hormonal levels. STUDY DESIGN: Cross-sectional study of children and adolescents attending a neurological outpatients department who were medicated with CBZ. Partial clearances of CBZ to CBZ-epoxide (CBZ-ep), CBZ-10,11-trans-diol (CBZ-diol), 2-hydroxy-CBZ (CBZ-2-OH), 3-hydroxy-CBZ (CBZ-3-OH), CBZ-acridan (CBZ-acr) and their respective glucuronides were calculated by relating 24-h recovery of these metabolites from urine to trough steady-state serum CBZ levels. CBZ and its metabolites were measured by a gradient high performance liquid chromatography (HPLC) method. Serum CBZ-ep, LH, FSH, prolactin, IGF-I, and testosterone or oestradiol and progesterone were also measured. Surface area (SA) and liver volume (LV) were calculated from height and weight. RESULTS: Twelve males and nine females with an age range of 6-17 years participated in the study. Partial clearance to each of the metabolites was most strongly correlated with the calculated size of the liver relative to body weight. These associations persisted when corrected for potential confounders using multiple regression analysis. CONCLUSION: In the age group studied, urinary clearance of CBZ to its known metabolites is proportional to the size of the liver relative to body weight.

Adolescent↗
PubMed1999

Incorporating ethics in priority setting: a case study of a regional health board in Canada.

The authors were involved in developing an ethical framework to assist the Queens Region Board (Prince Edward Island, Canada) set priorities in health and health care. Two and one half years after the adoption of this framework, the authors undertook an evaluation of the framework. This paper will discuss: (a) the historical background of regionalization in Canada, and in particular the circumstances leading up to the institution of regional boards in Prince Edward Island; (b) the sorts of ethical issues facing the Queens Regional Board; (c) issues arising in connection with the use and development of ethics frameworks for managing ethical issues in priority setting; (d) the framework adopted by the Queens Board and the process that led to its development; (e) issues arising as concerns implementation of the framework; (f) questions and issues pertinent to other boards and bodies considering similar initiatives.

Canada↗
PubMed1995

Waterborne cryptosporidiosis associated with a borehole supply.

From 1 April to 31 May 1993, 64 cases of cryptosporidiosis were diagnosed within one district health authority. Forty were classified as primary cases, 35 of whom were clustered in an area supplied by a discrete public water supply that supplied the majority of homes in a large town. Most of the water in this supply is abstracted from boreholes and some is filtered before distribution. Households that received mains water from this supply were 15 times more likely to be affected than households nearby that received water from other sources. A case control study demonstrated a dose response relationship between consumption of water obtained from the town supply and risk of illness. Very low concentrations of cryptosporidial oocysts were detected in the water supply on four occasions several weeks after the outbreak. Environmental investigation failed to reveal a likely mechanism for contamination of the water supply.

Adolescent↗
PubMed1983

Mechanism of increase in left ventricular end-diastolic pressure after contrast ventriculography in patients with coronary artery disease.

Elevation in left ventricular (LV) end-diastolic pressure (EDP) after contrast ventriculography (CV) has been proposed as a form of stress intervention in patients with coronary artery disease (CAD). The mechanism of this change has not been delineated. Accordingly, we performed two studies in CAD patients. In study 1 (n = 10), CV was repeated 3 minutes after an initial study. LVEDP rose from 14.9 +/- 6.6 mm Hg prior to the first ventriculogram to 26.9 +/- 10.8 mm Hg 3 minutes after the first ventriculogram (p less than 0.05) and immediately prior to the repeat CV (performed to evaluate the changes in volume produced by the first ventriculogram). In four patients with LV micromanometer pressures, the entire diastolic pressure-volume relation was shifted upward. LV ejection fraction (EF) and end-diastolic volume (EDV), peak LV pressure, and peripheral vascular resistance were unchanged at the time of repeat CV, and there was no correlation between the change in EDP and any of these variables. In study 2 (n = 6), gated radionuclide angiography was performed prior to and at minutes 2 to 7 after CV as were measurements of LV and right ventricular (RV) pressures. While both LV and RV EDP rose following contrast ventriculography, LV and RV EDV and EF were unchanged. We conclude that alterations in LVEDP after CV are unrelated to changes in LV or RV EDV and are most likely mediated by a decrease in myocardial compliance.

Adult↗
PubMed1983

Radionuclide analysis of pulmonary blood volume: the response to spontaneous angina pectoris and sublingual nitroglycerin in patients with coronary artery disease.

By manually assigning pulmonary regions of interest and deriving pulmonary time-activity (volume) curves, we were able to make count estimates of pulmonary blood volume (PBV) from gated cardiac blood pool scans. Five patients with coronary heart disease developed angina spontaneously while under a gamma camera. This produced an increase in cardiac volumes (p less than 0.05), a reduction in left ventricular ejection fraction (p less than 0.01), along with a marked increase in PBV (0.010 +/- 0.003 to 0.015 +/- 0.002 units, p less than 0.05). Nitroglycerin was then administered and reduced PBV in association with a return to normal in cardiac systolic function and size. In patients with stable chronic ischemic heart disease, sublingual nitroglycerin also reduced PBV (p less than 0.05), although not as much as when administered during an anginal episode. We conclude that gated imaging of the chest can be utilized to follow changes in PBV serially. These changes can be utilized to evaluate clinically important changes in hemodynamic status and the response to pharmacologic interventions.

Adult↗
PubMed1982

Postural changes in pulmonary blood flow in pulmonary hypertension: a noninvasive technique using ventilation-perfusion scans.

To determine whether postural changes in ratio of upper to lower (U:L) zone pulmonary blood flow reflect pulmonary arterial pressures, we used pulmonary perfusion photoscintigraphy to study 12 normal subjects and 10 patients with precapillary pulmonary hypertension (eight classified as "primary" and two as thromboembolic). All patients underwent right-heart catheterization and measurement of pulmonary arterial systolic, diastolic, mean and capillary (wedge) pressures. The distribution of perfusion was then assessed in the supine and erect positions after i.v. injection of technetium-99m-labeled, macroaggregated albumin. Perfusion distribution was corrected for lung volume by xenon-133 equilibrium ventilation scans. In normal subjects, the U:L lung zone perfusion ratio decreased by 70.7 +/- 12.2% with the change in position. The patient group differed (p less than 0.0001) from normal subjects in that there was only a 19 +/- 17.4% shift of U:L ratio with the postural change. The mean pulmonary arterial pressure in the patient groups was 50 +/- 24.2 mm Hg. The postural change in U:L zone ratio correlated significantly with the mean pulmonary arterial pressure (r = -0.84, p less than 0.01) pulmonary arterial systolic (r = -0.83, p less than 0.01) and diastolic pressures (r = -0.72, p less than 0.05) and with the pulmonary vascular resistance (r = -0.74, p less than 0.02). No correlation was found with other hemodynamic, spirometric or blood gas data. We conclude that the postural shift in U:L ratio warrants further exploration as a noninvasive approach for detecting and quantifying pulmonary hypertension.

Adult↗
PubMed1981

Evaluation of left ventricular function in chronic pulmonary disease by exercise gated equilibrium radionuclide angiography.

To assess left ventricular (LV) response to supine bicycle exercise, we studied 10 normal (group 1). 10 patients with coronary artery disease (CAD) (group 2), 12 patients with severe obstructive lung disease (COPD) (group 3), and eight patients with both CAD and COPD (group 4) by gated equilibrium radionuclide angiography. Most individuals in all groups also had pulmonary catheter-obtained measurements of LV filling pressures during exercise. Normal individuals increased their ejection fraction (EF) during exercise by increasing stroke volume (SV) and reducing end-systolic volume (ESV) without changing end-diastolic volume (EDV); pulmonary artery (PAP) and wedge (PAW) pressures were unaltered. CAD patients (group 2) showed no change in EF with increased EDV, ESV, SV, and PAW. COPD patients (group 3) exhibited decreases in EDV, ESV, and SV, accounting for abnormal EF responses in 6 of 12; PAW was unchanged and the marked elevation of PAP correlated with reduced EDV. Group 4 patients (CAD plus COPD) had abnormal EF responses with increased EDV and ESV without change in SV. Thus an abnormal LV function response to exercise in COPD patients may be multifactorial, thereby indicating the possible need for therapeutic modalities in addition to those employed in alleviating pulmonary parenchymal disease.

Adult↗
PubMed1981

Left ventricular size and function after subcutaneous administration of terbutaline.

To assess the response of the left ventricle to subcutaneously administered terbutaline sulfate, a proposed beta-2 selective agonist, we evaluated 12 patients who had suffered previous myocardial infarctions using equilibrium radionuclide angiography. Six patients (group 1) had normal global left ventricular ejection fraction at rest less than 0.49). All patients had a marked decline in end-diastolic volume and end-systolic volume with a significant (P less than 0.01) increase in ejection fraction after terbutaline injection. Cardiac output increased 30 percent in group 2 patients because of an increase in stroke volume, with little change in heart rate (plus or minus 3.1 beats per minute, P equals NS). Cardiac output increased 7 percent in the patients in groups 1, due primarily to an increase in heart rate in 7 beats per minute (+9 percent) with little change in stoke volume. Systemic vascular resistance decreased significantly more in the patients with compensated heart failure than the subjects in group 1 (342 plus or minus 84 vs 90 plus or minus 35 dynes-sec cm(-5), P less than 0.05). We conclude that terbutaline exerts its most beneficial effect on the left ventricle in patients with depressed resting global function, and may prove to be a useful agent in the treatment of congestive heart failure.

Aged↗
PubMedDate not supplied

Ethics for regional boards.

When regional health boards choose how to allocate limited resources on the public's behalf, they are exercising ethical judgment. When board members are familiar with the study of ethics and the tools it has produced, they are able to make informed and consistent ethical choices. One board in P.E.I. drew upon ethical principles to first codify its core values, and then develop a process for making decisions which conformed to those values. As boards across Canada assume greater authority and responsibility for public health, a clear understanding of ethical principles can guide their difficult choices.

Decision Making, Organizational↗