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Biomedical subjects

J A Parker

Publications and source records attributed to J A Parker.

At least 19 recordsLinked to original sources
PubMed1992

Study of retinal dystrophy in RCS rats: a comparison of Mg-ATP dependent light scattering activity and ERG b-wave.

A comparative study using the techniques of ERG to measure the b-wave and light scattering relaxation spectrophotometry (LSRS) to determine the dynamic behavior Mg-ATP dependent processes in the rod photoreceptors of pigmented control and dystrophic RCS rats has been carried out. LSRS results, based exclusively on photoreceptor rod outer segment dynamics, suggest a progressive failure in the dark and light-induced Mg-ATP dependent processes as a function of age. The dark signal amplitude in the dystrophic rats decreases to about 50% of the control by 5 weeks post-natal; the light-induced signal has decreased by 30% in the same period. The ERG b-wave results indicate that the differences in the amplitude and the time required to attain the peak amplitude become increasingly pronounced between the control and dystrophic groups of rats again as a function of age. By 10 weeks of age, the intensity of light required to obtain a b-wave with a amplitude of 100 microM is 10(3) greater in the dystrophic RCS rats. Similarly, the time to achieve this peak increases in the dystrophs with age. These results indicate that the retinal dystrophy in the RCS rat affects the activity of the rod photoreceptor cells.

Adenosine Triphosphate↗
PubMed1992

Recombinant tissue-type plasminogen activator versus a novel dosing regimen of urokinase in acute pulmonary embolism: a randomized controlled multicenter trial.

Thrombolysis of acute pulmonary embolism can be accomplished more rapidly and safely with 100 mg of recombinant human tissue-type plasminogen activator (rt-PA) (Activase) than with a conventional dose of urokinase (Abbokinase) given as a 4,400-U/kg bolus dose, followed by 4,400 U/kg per h for 24 h. To determine the effects of a more concentrated urokinase dose administered over a shorter time course, this trial enrolled 90 patients with baseline perfusion lung scans and angiographically documented pulmonary embolism. They were randomized to receive either 100 mg/2 h of rt-PA or a novel dosing regimen of urokinase: 3 million U/2 h with the initial 1 million U given as a bolus injection over 10 min. Both drugs were delivered through a peripheral vein. To assess efficacy after initiation of therapy, repeat pulmonary angiograms at 2 h were performed in 87 patients and then graded in a blinded manner by a panel of six investigators. Of the 42 patients allocated to rt-PA therapy, 79% showed angiographic improvement at 2 h, compared with 67% of the 45 patients randomized to urokinase therapy (95% confidence interval for the difference in these proportions [rt-PA minus urokinase] is -6.6% to 30.4%; p = 0.11). The mean change in perfusion lung scans between baseline and 24 h was similar for both treatments. Three patients (two treated with rt-PA and one with urokinase) had an intracranial hemorrhage, which was fatal in one. The results indicate that a 2-h regimen of rt-PA and a new dosing regimen of urokinase exhibit similar efficacy and safety for treatment of acute pulmonary embolism.

Acute Disease↗
PubMed1992

Survey design and observations relating to cancer education funding. Cancer Education Survey II: cancer education in United States medical schools (conducted by The American Association for Cancer Education with the support of the American Cancer Society).

A survey has been conducted of cancer education programs for medical students in United States medical schools by the American Association for Cancer Education with grant support from the Department of Detection and Treatment of the American Cancer Society (formerly the Professional Education Department). Two questionnaires were used, an Educational Resources Questionnaire (ERQ), which 126 of the 128 medical schools completed and returned, and a Faculty and Curriculum Questionnaire (FCQ), which was completed and returned by 1,035 faculty members who had been named as active in undergraduate medical student cancer education by respondents in each school who had been designated by the Dean's Office to complete the ERQ. Overall conclusions included: (1) increased coordination of cancer education activities is a major need in many schools; (2) there is widespread interest in the further development of cancer education objectives; (3) development of a national cancer education curriculum is needed; (4) there is interest in the development of improved instructional materials and methods; (5) development of evaluation methods is needed for cancer education programs; and (6) an ongoing funding process is needed to provide support for interdepartmental coordination of cancer education activities. Cancer prevention and detection topics were ranked above cancer treatment in plans for future curriculum emphasis. More detailed conclusions and recommendations are provided in this publication and three subsequent articles in this issue of the Journal of Cancer Education.

American Cancer Society↗
PubMed1992

Instructional methods and the use of teaching resources in cancer education curricula. Cancer Education Survey II: cancer education in United States medical schools.

The findings on cancer teaching methodology presented in this abstract come from an American Association for Cancer Education (AACE)/American Cancer Society-sponsored survey of American allopathic medical schools in 1989 and 1990 to determine how and how well cancer is presented in the medical school curriculum. Responses were received from 126 institutional and approximately 1,000 faculty respondents. Approximately one-third (368) of faculty respondents indicated the use of specific learning objectives; utilization does vary across disciplines. The lecture remains the dominant form of instructional method. Computers were reported as an instructional modality by only 16% of the faculty respondents. Prepared audiovisual instructional materials appeared to be widely utilized. Use varied from 86% for 35mm slides to 11% for video discs. Faculty favored the development of new teaching materials for ten topic areas ranging from approximately 40% for early detection and prevention to a low of approximately 25% for rehabilitation and continuing care. The survey identified an underutilization of existing outpatient facilities and tumor registries for cancer teaching purposes. The findings give rise to questions concerning the appropriateness of the match between specific instructional goals and the teaching methods employed. Eight recommendations designed to strengthen cancer training are made.

Computer-Assisted Instruction↗
PubMed1992

Cancer prevention education in United States medical schools. Cancer Education Survey II: cancer education in United States medical schools.

The Cancer Education Survey collected data from 126 of 128 US Medical Schools on the current status of cancer-related educational activities for undergraduate medical students. The study was conducted by a Supervisory Committee of the American Association for Cancer Education, with funding from the American Cancer Society. The survey obtained data concerning institutional characteristics in support of undergraduate medical student cancer education, ie, administrative structures, current cancer-related curricula, sources of financial support, and anticipated changes in these characteristics. Institutions were also queried on specific topics of cancer prevention, detection, and diagnosis that might be taught as identifiable areas of instruction for medical students. Three-fourths of the institutions had a lecture on the principles of cancer screening, and, among those, nearly three-fourths classified it as a part of a required course or rotation. Detection of common cancers is taught in virtually all institutions. The least likely cancer prevention lecture topics are related to prevention and cessation of smoking, a well-verified cancer risk. Also, no consistent pattern emerges that might indicate that association with a cancer center imparts to a medical school a greater emphasis on delivery of cancer prevention topics.

American Cancer Society↗
PubMed1992

Changing the cancer curriculum: a curriculum committee's response to the results of the AACE Cancer Education Survey II. Cancer Education Survey II: cancer education in United States medical schools.

The AACE Cancer Education Survey-II offers an unusual opportunity based on data from 125 medical schools and 1,035 experienced cancer educators to effect constructive change with regard to cancer education. The changes suggested include more coordination; integration; and a shift of emphasis to include more on topics of prevention, early diagnosis, tumor biology, rehabilitation, palliative care, and psychosocial issues. Ample opportunities, especially in the ambulatory care arena, exist at most medical schools, and there is a great deal of interest in improving the situation. This article reviews the factors contributing to resistance to change, the data on adult learning, and the major movements and dilemmas facing medical education today. It also discusses some of the external forces like the Liaison Committee on Medical Education (LCME) and foundation support, which are being harnessed to effect change. Given these barriers, forces, and opportunities, the article ends with a possible action plan for an individual, an institution, and national bodies interested in cancer education. The knowledge, skills, values, and attitudes must be defined, taught effectively, and evaluated. It is an opportune time, armed with this useful data, to bring about change in how cancer subjects are taught. The ultimate goal is more knowledgeable and effective practitioners and scientists who can decrease the morbidity and mortality from cancer.

Curriculum↗
PubMed1992

Assessment of intracardiac shunts with gadolinium-enhanced ultrafast MR imaging.

Dye dilutional techniques are widely accepted for the assessment of intracardiac shunts, but current techniques require arterial access or radioisotope injection. Ultrafast (less than 500 msec) magnetic resonance (MR) imaging is ideally suited for the evaluation of an indicator during passage through the heart. Twenty patients were studied, including 13 with shunts. Four-chamber, T1-weighted images were obtained during bolus injection of gadopentetate dimeglumine. A single image was obtained in 420 msec, with repetitive images acquired after each QRS complex. After the contrast material was injected, there was pronounced signal intensity enhancement in the right atrium, followed by the right ventricular cavity, left atrium, left ventricular cavity, and descending aorta. Patients with substantial intracardiac shunts demonstrated early recirculation. First-pass contrast material-enhanced MR imaging is a promising new technique for the rapid assessment of intracardiac shunts. Combined with anatomic and functional MR imaging techniques, it can help provide a comprehensive noninvasive evaluation of suspected intracardiac shunts or provide follow-up in patients with known shunts.

Adult↗
PubMed1992

Stroke volume and cardiac output decrease at termination of obstructive apneas.

Patients with obstructive sleep apnea (OSA) experience repetitive nocturnal oscillations of systemic arterial pressure that occur in association with changes in respiration and changes in sleep state. To investigate cardiac function during the cycle of obstruction (apnea) and resumption of ventilation (recovery), we continuously measured left ventricular stroke volume (LVSV) and mean arterial blood pressure (MAP) during non-rapid-eye-movement sleep in six males with severe OSA (apnea/hypopnea index > or = 30 events/h associated with oxygen saturation < 82%). LVSV was assessed continuously using an ambulatory ventricular function monitor (VEST; Capintec). The apnea-recovery cycle was divided into three phases: 1) early apnea (EA), 2) late apnea (LA), and 3) recovery (Rec). In all subjects recovery was associated with an abrupt decrease in LVSV [54.0 +/- 14.5 (SD) ml] compared with either EA (91.4 +/- 14.7 ml; P < 0.001) or LA (77.1 +/- 15.2 ml; P < 0.005). Although heart rate increased with recovery, the increase was not sufficient to compensate for the decrease in LVSV so that cardiac output (CO) fell (EA: 6,247 +/- 739 ml/min; LA: 5,741 +/- 1,094 ml/min; Rec: 4,601 +/- 1,249 ml/min; EA vs. Rec, P < 0.01; LA vs. Rec, P < 0.025). Recovery was also associated with a significant increase in MAP. We speculate that such abrupt decreases in LVSV and CO at apnea termination, occurring coincident with the nadir of oxygen saturation, may further compromise tissue oxygen delivery.

Adult↗
PubMed1991

Relatively enhanced S cone function in the Goldmann-Favre syndrome.

Using electrophysiologic and psychophysical tests that measure rod, midspectral, and S (blue) cone function, we studied four patients with the Goldmann-Favre syndrome, an autosomal recessive vitreoretinal degeneration. With spectral electroretinography, the predominant signal was from the S cones. With dark-adapted perimetry, all patients had severely reduced rod sensitivities and subnormal midspectral cone sensitivities. With S cone perimetry, the patients had normal or subnormal S cone function. Sensitivity differences between S and midspectral cones were significantly different from normal; there was relatively higher sensitivity to S cones compared to midspectral cones throughout the visual field. This relationship of dysfunctional cone mechanisms in the Goldmann-Favre syndrome is similar to that in the enhanced S cone syndrome, a recently identified retinal degeneration with S cone hypersensitivity. The results suggest that the Goldmann-Favre and the enhanced S cone syndromes are linked by a common pattern of retinal dysfunction.

Adult↗
PubMed1991

Regional myocardial blood flow and left ventricular diastolic properties in pacing-induced ischemia.

The relation between left ventricular diastolic abnormalities and myocardial blood flow during ischemia was studied in eight open chest dogs with critical stenoses of the proximal left anterior descending and circumflex coronary arteries. The heart was paced at 1.7 times the heart rate at rest for 3 min. In dogs with coronary stenoses, left ventricular end-diastolic pressure increased from 8 +/- 1 to 14 +/- 2 mm Hg during pacing tachycardia (p less than 0.01) and 16 +/- 3 mm Hg (p less than 0.01) after pacing, with increased end-diastolic and end-systolic segment lengths in the ischemic regions. Left ventricular diastolic pressure-segment length relations for ischemic regions shifted upward during and after pacing tachycardia in dogs with coronary stenoses, indicating decreased regional diastolic distensibility. In dogs without coronary stenoses, the left ventricular diastolic pressure-segment length relation was unaltered. Pacing tachycardia without coronary stenoses induced an increase in anterograde coronary blood flow (assessed by flow meter) in both the left anterior descending and circumflex coronary arteries, and a decrease in regional vascular resistance. In dogs with coronary stenoses, regional vascular resistance before pacing was decreased by 18%; myocardial blood flow (assessed by microspheres) was unchanged in both the left anterior descending and circumflex coronary artery territories. During pacing tachycardia with coronary stenoses, regional coronary vascular resistance did not decrease further; subendocardial myocardial blood flow distal to the left anterior descending coronary artery stenosis decreased (from 1.03 +/- 0.07 to 0.67 +/- 0.12 ml/min per g, p less than 0.01), as did subendocardial to subepicardial blood flow ratio (from 1.04 +/- 0.09 to 0.42 +/- 0.08, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Impact of early post-exercise myocardial redistribution of TI-201 on SPECT imaging. Preliminary observations.

In a series of 62 male patients undergoing exercise TI-201 SPECT myocardial scintigraphy, planar 45 degrees LAO images were acquired before (2-5 minutes postinjection, P1) and after (35 minutes postinjection, P2) the initial SPECT study in order to identify those patients with redistribution during the first 30 minutes after exercise. Consensus interpretation by four readers identified early redistribution (between P1 and P2) in 11 patients (18%), rated major (change of greater than 1.5 scoring unit) in five and minor (change of 1-1.5 scoring unit) in six. Only one patient (2%) showed major early redistribution that could not be appreciated on corresponding SPECT images. In this preliminary investigation, early thallium redistribution sufficient to affect identification of significant exercise-induced ischemia on SPECT imaging was infrequent and of limited clinical importance.

Adult↗
PubMed1991

Success in basic combat training: the role of cigarette smoking.

We studied whether cigarette smoking affected a soldier's ability to complete basic combat training. Demographic and tobacco use information was collected from a cohort of soldiers before they began training. A list of all graduates was obtained and analyzed against the initial questionnaire data. In this prospective study, the smoking group comprised 339 soldiers and the nonsmoking group comprised 535 soldiers. We found that those soldiers who smoked one or more packs of cigarettes per day were at a greater risk for failing basic combat training (relative risk = 2.05, P = 0.092. There was no relationship observed between a soldier's education and his ability to complete basic combat training. Our data indicate that smoking one or more packs of cigarettes per day may adversely affect a soldier's ability to complete basic combat training.

Achievement↗
PubMed1990

Three years' experience with an all-digital nuclear medicine department.

We describe our all-digital, filmless, department of nuclear medicine, which has been fully operational for 3 years. The approach to the design and implementation of a nuclear medicine picture archiving and communication system (PACS) is discussed, as well as enhancements found to be necessary or desirable during our 3 years of experience using the system. Studies are initially viewed on remote monitors in the reading room, and transferred from multiple vendor's computers to the PACS by floppy disc network. Scans are analyzed on networked image workstations using a variety of software imaging tools. Reports are dictated into a digital voice storage system, allowing the referring physician immediate telephone access. The dictated report is typed into a computer, electronically edited, reviewed, billed, and printed for appropriate distribution on an integrated medical information system. The final report is stored on the PACS, along with the scan image and other patient information on 1-gigabyte removable optical discs. Two networked optical disc drives allow us to have approximately 3 years of our department's studies available instantly, allowing recall of previous studies for comparison with the current scan. Emergency night and weekend studies are sent via modern over normal phone lines to the on-call physician, who has a similar image workstation at home. Digital image storage allows for easy manipulation of the data, such as gray scale manipulation and cine (movie) display. Cost analysis shows significant savings compared with a film-based department. We conclude that an all-digital nuclear medicine department is practical, cost effective, and beneficial to both patients and staff.

Analog-Digital Conversion↗
PubMed1990

Reduced supine cardiac volumes and diastolic filling rates in elderly patients with chronic medical conditions. Implications for postural blood pressure homeostasis.

Very elderly individuals with multiple chronic illnesses are at high risk of orthostatic hypotension, falls, and associated morbidity and mortality. Alterations in cardiac volumes and filling characteristics may contribute in part to an increased prevalence of orthostatic hypotension and falls in these people. In this study cardiac function was evaluated with gated radionuclide ventriculography in eight healthy young subjects (19-38 years) and 25 elderly persons with stable chronic illnesses (73-96 years), 14 of whom had a history of recurrent falls. Blood pressure was measured supine during the radionuclide ventriculography, then after one minute of standing. Supine stroke volume index, end diastolic volume index, cardiac index, and peak filling rates were significantly lower in elderly subjects compared to young, and ejection fraction and end systolic volume index (measures of systolic function) were the same in young and old. Compared to the young, elderly subjects had a reduction in ventricular filling during the first third of diastole, but an augmentation in the last third, during atrial contraction. Within the group of elderly subjects, the directional change in systolic blood pressure during orthostasis was significantly correlated with basal supine systolic blood pressure (R = 0.81, P less than .0001) and supine cardiac index (R = 0.66, P = .002). Thus, very old people representative of those seen in clinical practice have reduced cardiac volumes and impaired early diastolic filling, a result possibly related to elevations in systolic blood pressure. These changes in cardiac structure and function may contribute, in part, to orthostatic hypotension in advanced age.

Accidental Falls↗
PubMed1990

Measurement of joint inflammation in rheumatoid arthritis with indium-111 chloride.

Studies in the collagen and rabbit models of arthritis have indicated that indium-111 chloride (111InCl3) scintigraphy objectively measures synovial inflammation. Indium-111 chloride scans, with imaging three days after 19 MBq intravenous injection, were performed on 21 patients with definite or classical rheumatoid arthritis (RA), all of whom were functional class II. Standard clinical indices of disease activity were recorded at the time of imaging by the same investigator, who was unaware of the results of joint scans. In addition, eight patients with severe osteoarthritis, four of whom were considered to need hip or knee joint replacement, were similarly scanned. In each patient 16 joints were graded as 0 to 5, based on increasing degrees of 111InCl3 uptake, by a single investigator blinded to the patient's diagnosis and clinical status. In the group with RA significant correlations were observed between individual joint uptake on scan and peripheral joints with swelling, joints reported to be painful, and joints with any abnormality on physical examination. In the group with osteoarthritis joints positive on scan correlated with the presence of pain. A total scan score (sum of individual joint scores) was calculated for each patient. In the patients with RA values ranged from 0 to 42 with a mean (SEM) of 20.7 (2.7) and correlated with the number of swollen joints and decreasing grip strength. In the group with osteoarthritis the mean total scan score (9.2 (1.5), range 3-14) was significantly lower than in the patients with RA. These data show that 111InCl3 scanning can measure joint involvement by RA.

Adult↗
PubMed1990

Pulmonary embolism: segmental appearance of perfusion lung scan defects correlates with successful response to thrombolytic therapy.

Lung scan data from a series of 45 patients receiving thrombolytic therapy were reviewed to determine if any pattern on the pretherapy perfusion lung scans could be identified that predicted response to therapy. A segmental appearance on the pretherapy scans (complete or nearly complete absence of perfusion in a whole segment or a very large subsegment) was correlated with the amount of improvement in perfusion on lung scans obtained 24 hours after the start of thrombolytic therapy. As a group, patients with a segmental appearance on the pretherapy lung scans had more improvement in the perfusion reduction score than patients with a nonsegmental appearance (P less than .005). However, the correlation between segmental appearance and a favorable response to thrombolytic therapy was not strong enough to allow use of this appearance in the selection of patients for therapy.

Female↗
PubMed1990

Histopathological features of congenital fundus lesions in familial adenomatous polyposis.

We report the light and electron microscopic findings for two lesions from two patients who died of complications of familial adenomatous polyposis. In the first case microscopy of a small (100 to 200 mu), uniformly dark lesion (the commonest type seen in this condition) showed enlarged retinal pigment epithelial cells with an increased number of pigment granules. This is consistent with the term "hypertrophy of the retinal pigment epithelium", currently used to describe these lesions. In the second case we sectioned a larger (1000 to 1500 mu), oval, grey lesion from the posterior pole. The pigment epithelium was normal, but between it and outer retina was an unusual choristoma consisting largely of myelinated axons and astrocytes.

Adenomatous Polyposis Coli↗