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Biomedical subjects

G M Segall

Publications and source records attributed to G M Segall.

18 recordsLinked to original sources
PubMed1992

Effects of anger on left ventricular ejection fraction in coronary artery disease.

This study examined the comparative potency of several psychological stressors and exercise in eliciting myocardial ischemia as measured by left ventricular (LV) ejection fraction (EF) changes using radionuclide ventriculography. Twenty-seven subjects underwent both exercise (bicycle) and psychological stressors (mental arithmetic, recall of an incident that elicited anger, giving a short speech defending oneself against a charge of shoplifting) during which EF, blood pressure, heart rate and ST segment were measured. Eighteen subjects had 1-vessel coronary artery disease (CAD), defined by greater than 50% diameter stenosis in 1 artery as assessed by arteriography. Nine subjects served as healthy control subjects. Anger recall reduced EF more than exercise and the other psychological stressors (overall F [3.51] = 2.87, p = .05). Respective changes in EF for the CAD patients were -5% during anger recall, +2% during exercise, 0% during mental arithmetic and 0% during the speech stressor. More patients with CAD had significant reduction in EF (greater than or equal to 7%) during anger (7 of 18) than during exercise (4 of 18). The difference in EF change between patients with CAD and healthy control subjects was significant for both anger (t25 = 2.23, p = 0.04) and exercise (t25 = 2.63, p = 0.01) stressors. In this group of patients with CAD, anger appeared to be a particularly potent psychological stressor.

Anger↗
PubMed1992

Effect of flow rate on adherence of unlabeled and indium-111 oxine-labeled leukocytes.

Uptake of radioactively labeled leukocytes has been observed in ischemic noninfected regions. Since this may be a flow-related phenomenon, the authors investigated the effect of flow rate on adherence of indium-111 oxine-labeled leukocytes with a model based on the elution patterns of radioactivity and granulocytes from nylon fiber columns. Relative radioactivity adherence (%RA) and relative granulocyte adherence (%GA) agreed closely, indicating that radioactivity retained by the columns is predominantly in the form of viable labeled granulocytes, and that labeled and unlabeled granulocytes have the same adherence characteristics. When other conditions were held constant, but passage speed was varied, %GA and %RA were related to the flow rate in an inverse linear fashion. Decrease in flow rate can lead to increased accumulation of leukocytes.

Cell Adhesion↗
PubMed1992

Functional imaging of peripheral vascular disease: a comparison between exercise whole-body thallium perfusion imaging and contrast arteriography.

Whole-body thallium scintigraphy was used to study leg muscle perfusion in 12 healthy individuals and 31 patients with peripheral vascular disease. Subjects were scanned immediately after exercise and 4 hr later. Buttock, thigh and calf perfusion were measured in terms of fractional uptake relative to whole-body activity, percent change in fractional uptake over 4 hr and interextremity symmetry ratios. The results were compared to contrast arteriography on a region by region basis. The overall sensitivity and specificity of thallium scintigraphy were 80% and 73%, respectively. The results suggest that thallium scintigraphy may provide useful information about the hemodynamic significance of noncritical anatomic lesions.

Angiography↗
PubMed1991

Safety of dipyridamole-thallium imaging in high risk patients with known or suspected coronary artery disease.

The effects of an oral dipyridamole suspension were studied in 400 consecutive patients to determine if certain subsets of patients were at greater risk of suffering major complications. Most patients (69%) experienced at least one side effect. Severe chest pain, severe hypotension, and severe dyspnea occurred in 9%, 2.5%, and 0.3% of patients respectively. Two patients were hospitalized for persistent chest pain but none suffered a myocardial infarction, malignant ventricular arrhythmia, or death. The test was found to be safe for patients over 70 yr old. Severe dyspnea was rare even among patients with lung disease who were withdrawn from theophylline prior to testing. Patients with three-vessel coronary artery disease were more likely to experience severe chest pain and those with significant left ventricular dysfunction were more likely to develop severe hypotension. In 99.5% of patients, side effects were promptly reversed by aminophylline. Dipyridamole-thallium imaging has an acceptable safety profile for a wide variety of patients, including those with severe coronary disease and/or left ventricular dysfunction.

Age Factors↗
PubMed1990

Kinetics of leukocyte sequestration in the lungs of acutely septic primates: a study using 111In-labeled autologous leukocytes.

To further clarify the role of leukocytes in the pathogenesis of ARDS, we studied the localization and kinetics of leukocyte migration using 111In-labeled autologous white cell scans (111In wbc scans) in four primates made acutely septic with infusions of Escherichia coli. Whole body images were obtained with a gamma camera and were acquired on computer every 15 min beginning immediately after the E. coli infusion. Simultaneous measurements of C5a and peripheral blood leukocyte count were also obtained. Within 5 min of initiating sepsis, three major events occurred: complement activation as measured by the production of C5a, a profound fall in peripheral leukocyte count, and a significant increase in the sequestration of leukocytes in the lungs. The pulmonary sequestration reached a peak at 15 min with a mean of 152% of baseline activity. This sequestration consisted of a population that was predominantly neutrophils. Damage to the pulmonary capillary endothelium was demonstrated by an increase in extravascular lung water. The results support a role for neutrophils and complement as mediators in the pathogenesis of ARDS.

Acute Disease↗
PubMed1990

Sequential assessment of pulmonary epithelial diethylene triamine penta-acetate clearance and intrapulmonary transferrin accumulation during Escherichia coli peritonitis.

The individual roles of pulmonary capillary endothelial and alveolar epithelial permeability in the pathogenesis of the adult respiratory distress syndrome (ARDS) are unclear. We developed a method for the sequential assessment of pulmonary macromolecule accumulation and small solute clearance in vivo using a gamma camera. We measured the exponential clearance coefficient of 111In-labeled diethylene triamine penta-acetate (111In-DTPA) to assess airway clearance of small solutes. We also calculated the exponential equilibration coefficient of 111In-labeled transferrin (111In-TF) to assess intrapulmonary accumulation of transferrin. We determined these parameters in guinea pigs with Escherichia coli peritonitis and compared them with a saline-treated control group, oleic-acid-treated groups, and a group treated with low molecular weight dextran Ringer solution. The pulmonary DTPA clearance and the intrapulmonary transferrin accumulation were significantly increased in the peritonitis group (29.4 +/- 8.2 x 10(-3) min-1, p less than 0.02, and 15.1 +/- 3.1 x 10(-3) min-1, p less than 0.02) when compared with the control group (3.1 +/- 0.8 x 10(-3) min-1 and 4.5 +/- 0.5 x 10(-3) min-1). These changes developed within 5.5 h of the initial insult. Neither increased extravascular lung water nor elevated pulmonary artery and left atrial pressures were detected in the peritonitis group. The low molecular weight dextran Ringer group did not show a significant increase in the pulmonary DTPA clearance and the intrapulmonary transferrin accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Exercise whole-body thallium scintigraphy in the diagnosis and evaluation of occlusive arterial disease in the legs.

Whole-body thallium scintigraphy can be used to diagnose and evaluate occlusive arterial disease in patients with leg claudication. We performed exercise and redistribution scans in 36 healthy individuals and 17 patients with claudication. Regions of interest were drawn around the whole body, as well as each buttock, thigh, and calf. Counts in each region were expressed as a percentage of whole-body activity, as well as an interextremity activity ratio for each level. Significant differences due to gender and age were found. The sensitivity and specificity of the test in men was 94% and 71%, respectively, using the criterion of percentage regional uptake and 81% and 90%, respectively, using interextremity comparison. We conclude that exercise whole-body thallium imaging is a simple and accurate test for the evaluation of suspected occlusive arterial disease in the legs.

Adult↗
PubMed1989

The role of bone scan and radiography in the diagnostic evaluation of suspected pedal osteomyelitis.

The authors reviewed the three-phase bone scans and radiographs of 24 patients with suspected pedal osteomyelitis who also had histologic confirmation of the diagnosis. Twenty patients had a pedal ulcer, cellulitis, or necrosis. Sensitivity and specificity of bone scanning were 70% and 43% respectively. Sensitivity and specificity of radiography were 70% and 50% respectively. The non-invasive diagnosis of pedal osteomyelitis remains problematic due to the poor specificity of bone scans and radiographs.

Adult↗
PubMed1989

Prone versus supine thallium myocardial SPECT: a method to decrease artifactual inferior wall defects.

Artifactual inferior wall defects as a result of diaphragmatic attenuation of activity are a frequent source of error in thallium myocardial single photon emission computed tomography (SPECT) studies. Thirty-four patients and 11 clinically normal volunteers were studied prospectively to see if specificity of inferior wall defects for right coronary artery disease could be improved by scanning patients prone versus supine. All individuals were scanned both prone and supine, in random order, following symptom limited treadmill exercise. Images were acquired at 3 degrees steps, 25 sec per frame, in a 180 degrees elliptical orbit always beginning in the 45 degrees right anterior oblique position relative to the patient. Polar maps generated from the short axis slices were used to calculate the average regional activity. The prone studies showed consistently higher inferior wall activity compared to the supine studies on both the exercise (182 +/- 22 vs. 160 +/- 23, p less than or equal to 0.001) and 4-hr delay studies (183 +/- 20 vs. 175 +/- 21, p less than or equal to 0.001). Prone imaging resulted in a significantly higher specificity for RCA disease compared to supine imaging (90% vs. 66%, p less than 0.05) with an improvement in accuracy from 71% to 82%. Sensitivity, specificity, and accuracy for left anterior descending and left circumflex artery disease were not significantly affected by patient position during imaging. All patients having SPECT thallium myocardial perfusion studies should be imaged prone to minimize artifactual inferior wall defects and improve accuracy.

Adult↗
PubMed1988

Variability of serum drug level following a single oral dose of dipyridamole.

Serum dipyridamole levels were measured in 27 patients undergoing planar thallium-201 myocardial perfusion scintigraphy after receiving a 300 mg oral dose. Mean serum dipyridamole level was 2.9 +/- 1.6 mcg/ml (range 0.2-5.7). No correlation was found between serum level and symptoms, heart rate or blood pressure response, peak heart to lung thallium activity ratio, peak heart to liver thallium activity ratio, or peak myocardial thallium washout. Serum level following a single oral dose of dipyridamole is unpredictable and patients with low drug levels cannot be easily identified at the time of study.

Administration, Oral↗
PubMed1986

Adherence of radiopharmaceuticals and labeled cells to intravenous tubing.

A survey of 67 nuclear medicine departments revealed no agreement on which radiolabeled agents could be injected through intravenous lines (IVs) and which required direct venipuncture. Labeled cells and several common radiopharmaceuticals were tested for adherence to intravenous tubing. Residual activity remaining in the tubing after an adequate flush was less than 1% of the injected dose in each case. Administration of radiolabeled agents through existing IVs is an acceptable alternative to direct venipuncture in many cases.

Catheters, Indwelling↗
PubMed1986

Diagnostic value of lung uptake of indium-111 oxine-labeled white blood cells.

One hundred sixty-two white-blood-cell scans were retrospectively reviewed to determine the sensitivity and specificity of the test for pulmonary and pleural infection. All scans were performed 18-24 hr after injection of indium-111 oxine-labeled autologous or donor cells. Pulmonary activity was graded on a scale of 0-4: 0 = equal to soft tissue; 1 = greater than soft tissue but less than rib; 2 = equal or greater than rib but less than liver; 3 = equal or greater than liver but less than spleen; 4 = equal to spleen. Activity was also characterized as being focal or diffuse. The white-blood-cell scan findings were correlated with the clinical diagnosis on the basis of physical examination, laboratory results, chest radiographs, clinical course, and pathologic studies when available. As pulmonary activity increased from grade 1 to 4, sensitivity declined from 93% to 14% and specificity increased from 64% to 100%. The sensitivity and specificity of focal uptake were 31% and 89% vs 62% and 74% for diffuse pulmonary activity. Making a distinction between focal and diffuse activity did not improve the specificity of low grades of pulmonary activity. The white-blood-cell scan can be very sensitive or very specific for pulmonary or pleural infection, depending on the criteria selected for a positive scan.

Adolescent↗