Biomedical subjects
J L Harris
Publications and source records attributed to J L Harris.
Efforts to improve AME performance through CME and annual performance reports.
Continuing medical education (CME) serves to maintain or increase the knowledge, interpretive proficiencies, and technical skills that a physician uses in his/her practice of medicine. Resulting improvement is frequently difficult to measure, particularly in aerospace medicine, but CME is required for relicensure and/or for medical society membership in 70% of states. The Civil Aeromedical Institute first received American Medical Association approval for Category I CME credit for attendance at FAA seminars in January 1973. We began preparing annual performance reports for each aviation medical examiner (AME) in 1979 to attempt to isolate the causes of, and to reduce, computer rejection of about one-fourth of all medical certification input because of omissions or procedural errors. A special analysis of 1983 AME performance data found that errors were significantly reduced with recent and frequent seminar attendance, larger volume of exams, and pilot and military flight surgeon experience.
The problem of acute mesenteric arterial occlusion: report of a case.
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Situs inversus totalis with calculi in a left-sided gallbladder: report of a case.
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Carcinoma of the fallopian tube: a case report.
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Mechanisms of late decelerations of the fetal heart rate during hypoxia.
Transient maternal aortic occlusion decreases uterine blood flow and results in the delayed deceleration of the fetal heart rate. The response to this maneuver was examined in the hypoxic fetus. Pregnant ewes and their fetuses at 0.8 gestation were catheterized for chronic study. A blood flow transducer was placed around the common umbilical artery, and a Fogarty balloon-tipped catheter was placed in the maternal abdominal aorta distal to the renal arteries. The ewes were made hypoxic by breathing a hypoxic gas mixture through a mask placed over their faces. Transient maternal aortic occlusion resulted in a delayed and transient deceleration of the fetal heart rate in hypoxic fetuses, associated with a significant decrease in mean arterial pressure and umbilical blood flow. Infusion of atropine into the fetus before maternal aortic occlusion modified but did not abolish the fetal heart rate response. The deceleration was associated with the significant decrease in the "double-product" index of myocardial oxygen consumption. The conclusion is that late decelerations result from two mechanisms: chemoreceptor vagal reflex mechanisms and hypoxic myocardial depression.
Hemodynamic effects of alpha-adrenergic blockade during hypoxia in fetal sheep.
During hypoxemia there is a redistribution of cardiac output in the sheep fetus associated with increased vascular resistance in some fetal organs. The role of the alpha-adrenergic blocking drug to eight chronically instrumented hypoxemic sheep fetuses. We measured arterial blood pressure and heart rate, determined cardiac output and organ blood flows by means of radionuclide-labeled microspheres, and calculated vascular resistances in fetuses before and during hypoxia, and after injection of phenoxybenzamine 15 mg into the inferior vena cava of the hypoxemic fetus. Hypoxemia resulted in an increased vascular resistance in certain vascular beds. Alpha-adrenergic blockade during hypoxia abolished the increase in vascular resistance of the fetal body and caused an increase in the blood flow to some tissues which had a hypoxia-induced vasoconstriction. After alpha-adrenergic blockade during hypoxia, mean arterial blood pressure decreased from 48 +/- 6 to 42 +/- 6 mm Hg (p less than 0.05) and heart rate increased from 128 +/- 19 to 235 +/- 51 beats per minute (p less than 0.001). Cardiac output increased 23% and blood flow to the brain was maintained. We conclude that the alpha-adrenergic system is important in maintaining the redistribution of cardiac output that occurs in hypoxic fetal sheep.
Predicting seriousness of illness using external stress, imagery, and other cognitive mediating variables.
Measures of external life stress, trait anxiety, self-concept, subjective stress and three measures of imagery were taken on 188 college students and were used to predict seriousness of illness in an attempt (1) to determine if cognitive mediating variables could significantly add to external life stress in the prediction of seriousness of illness, and (2) to determine if imagery, alone or interacted with self-concept, could add to the prediction. Using multiple linear regression, trait anxiety, a subjective feeling of stress, self-concept, visual imagery, sex, and an interaction between self-concept and emotive imagery significantly increased the variance when added to external life stress in predicting seriousness of illness. Trait anxiety, when added to external life stress, increased the variance by an amount greater than life stress alone. This adds support to the concept that the interpretations of stress, the cognitive mediating variables, are certainly important and in fact may be more important than environmental factors alone in predicting seriousness of illness.
Fetal oxygen consumption and mechanisms of heart rate response during artificially produced late decelerations of fetal heart rate in sheep.
Delayed decelerations of fetal heart rate were produced by abruptly decreasing uterine blood flow to zero for 20 seconds in chronically instrumented, normoxic sheep. Fetal O2 consumption, O2 content, and O2 tension in umbilical blood decreased significantly before the decline in heart rate. Fetal arterial blood pressure did not change significantly. Complete vagal blockade abolished the late deceleration and uncovered a late acceleration, which in turn was eliminated by total beta-adrenergic blockade. We conclude that these late decelerations in normoxic sheep are vagally mediated and due to chemoreceptor rather than baroreceptor activity.
Increased fetal heart rate variability with acute hypoxia in chronically instrumented sheep.
Fetal heart rate (FHR) and oxygen consumption were determined in 45 studies in 20 chronically instrumented, normoxic sheep. FHR variability was measured by a template device to determine amplitude range, and oscillatory frequency was manually counted over 5-min periods. During 26 min of isocapnic hypoxia, fetal O2 consumption decreased 39% and FHR decreased 18%, and FHR variability increased, the changes being maintained over the treatment period. It is suggested that the maintenance of FHR variability during this profound hypoxia denotes adequate cardiorespiratory compensatory mechanisms during the short period; prolongation of the hypoxia would probably result in fetal cerebral or myocardial decompensation, and disappearance of FHR variability. The increased variability may be due to increased alpha-adrenergic activity.
Effect of parasympathetic and beta-adrenergic blockade on the umbilical circulation in the unanesthetized fetal sheep.
Parasympathetic and beta-adrenergic blocking agents were administered to near term chronically instrumented sheep. Parasympathetic blockade resulted in a significant increase in fetal heart rate and fetal arterial blood pressure, with a minimal nonsignificant increase in umbilical blood flow. beta-Adrenergic blockade resulted in a decrease in fetal heart rate and umbilical blood flow, though neither was statistically significant. There was no change in arterial blood pressure. The net result of parasympathetic and beta-adrenergic blockade on fetal heart rate suggests that the intrinsic rate is the same as when these influences are present.
Interdisciplinary health education: a case study of fact and fancy.
Meeting the health needs of patients and providing comphrehensive health care services require the integration and coordination of several professional health services. Traditional methods for training students in the health professions independently are being challenged by the need for future practitioners to understand and to utilize effectively the skills offered by the other disciplines. However, the movement of educational institutions toward interdisciplinary training programs entails the careful assessment of program design, content, and basic philosophy. Two and one-half years of experience with such a program at one academic health center are reviewed.
Computerization of a hospital clinical microbiology laboratory.
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A training program for interprofessional health care teams.
Interprofessional approaches to practice have gained increased popularity. This paper describes a course in team training for professionals in health care. It is an overview of the course's content with a discussion of the problems and issues that arose as the course was designed and implemented. It concludes with a discussion of the outcomes and evaluations of the students' and faculty's experience.
Characterization of multiple forms of brain tubulin subunits.
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AME seminar program in the United States: genesis, goals, and cost-benefit reflections.
The practicing physician's requirement for continuing postgraduate medical education is generally accepted and has generated a number of postgraduate education programs. In 1960, the FAA inaugurated a seminar program to serve the special educational needs of its approximately 7,500 designated Aviation Medical Examiners. These doctors, the majority of whom are civilian physicians representing almost every specialty, are charged with issuing or withholding the pilot's medical license to fly. Under the administration of coauthor Harris, the AME Seminar Program undergoes modification and change as improvements are suggested by accrued experience. Evaluation of data acquired from a variety of sources indicates that the AME does, in fact, need refresher training in civil aviation medicine. In helping fulfill that need, the AME Seminar Program is working effectively.
Capillary lengths and areas, and intercapillary distances in tissue near the human knee.
Quantiative stereological electron microscopy has been used to investigate the capillary lengths, surface areas and intercapillary distances in the tissues around the human knee, the synovial membrane, synovial capsule, fat and tendon. The vascularity of these regions was much less than in other areas of the body, especially muscle.
The quantitative morphology of skeletal muscle capillaries in relation to permeability.
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