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R J Bacon

Publications and source records attributed to R J Bacon.

4 recordsLinked to original sources
PubMed1991

Factors related to medical school application and acceptance in minority summer enrichment program students.

Baylor College of Medicine has conducted a summer enrichment program for minority/disadvantaged premedical students since 1969. Follow-up data on medical school application and acceptance for participants from 1980 through 1984 were analyzed in relation to selected preprogram variables--cumulative college grade point average, total Scholastic Aptitude Test score, competitiveness of undergraduate college, sex, and ethnicity. Results of univariate and multivariate analyses indicated that: 1) females were significantly less likely to apply to medical school than males, 2) females had significantly lower mean MCAT scores (5.9 vs 7.2) even though their preprogram academic performance was comparable to that of the males, and 3) after controlling for MCAT scores, none of the preprogram variables were significant in predicting medical school acceptance. These findings suggest the need for research to explain the discrepancy between male and female MCAT performance and frequency of medical school application in summer program participants. The findings also have implications for the type of counseling provided to female participants in summer enrichment programs.

College Admission Test↗
PubMed1990

Estimation of aortic and pulmonary blood flow in a paediatric population using Doppler ultrasound: an in-vitro study.

The noninvasive measurement of blood flow using ultrasound has been attempted by numerous workers. In order to evaluate the technique of duplex scanning applied to the problem of noninvasive assessment of aortic and pulmonary blood flow in a paediatric population with ventricular septal defect, we attempted an in-vitro simulation of these flow conditions. The factors which have been considered in the design of the apparatus include the availability of a range of tube diameters, an aortic-"like" waveform, laminar flow, variable downstream peripheral resistance, a compliance factor and viscosity of the flow medium. The ultrasound probe beam characteristics, sample volume size and shape were also determined. From the results of the beam plots it was apparent that the region of sensitivity of the CW Doppler probes were inappropriate for the measurement of blood flow in neonates. In order to simulate physiological parameters in a paediatric population as closely as possible, five tubes of diameters ranging from 9-18 mm were used, in each tube a range of flow values from 0.8 L min-1 to 5 L min-1 were measured. The flow values were measured by both "bucket and stopwatch" and duplex scanner for both steady and pulsatile flow conditions. The results are presented as correlations between the direct and noninvasive pulsed Doppler assessment of flow measurement and are in the range 0.92-0.99 significant at p less than .001. A discussion of the reliability of flow measurements made using a conventional duplex scanner is given.

Aorta↗
PubMed1984

Assessment of beta-adrenoceptor selectivity of a new beta-adrenoceptor antagonist, bisoprolol, in man.

Bisoprolol is a new beta-adrenoceptor antagonist which has shown beta-adrenoceptor selectivity in studies in isolated tissues. Bronchial and cardiac beta-adrenoceptor blockade were assessed in eight normal subjects before and after oral ingestion of placebo, bisoprolol 20 and 40 mg, metoprolol 200 mg and propranolol 80 mg in random order. Bronchial beta-adrenoceptor blockade was assessed as the displacement of the bronchodilator dose-response curve to inhaled isoprenaline after each beta-adrenoceptor blocking drug compared to placebo and expressed as the dose ratio. Bronchodilatation was measured as change in specific airway conductance (sGaw) in the body plethysmograph. Cardiac beta-adrenoceptor blockade was assessed as the percentage reduction in exercise heart rate during the fifth minute of exercise at 70% of the subject's maximum work rate. Bisoprolol 20 and 40 mg caused a 24 and 25% reduction in exercise heart rate respectively, compared to 26% with metoprolol 200 mg and 20% with propranolol 80 mg. The dose ratios for the airway dose-response curves for the four beta-adrenoceptor blocking drugs were 1.04 and 3.4 for bisoprolol 20 and 40 mg, 1.4 for metoprolol 200 mg and 30 for propranolol 80 mg. Both doses of bisoprolol produced considerably less bronchial beta-adrenoceptor blockade than propranolol 80 mg despite causing a greater reduction in exercise heart rate. Bisoprolol 20 mg caused a similar amount of bronchial beta-adrenoceptor blockade and a similar reduction in exercise heart rate as metoprolol 200 mg, confirming that it is cardio-selective in man.

Adrenergic beta-Antagonists↗