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Biomedical subjects

D E Tow

Publications and source records attributed to D E Tow.

At least 19 recordsLinked to original sources
PubMed1997

Radiolabelling leukocytes with 99Tcm-stannous chloride colloid for the detection of inflammatory lesions.

Freshly prepared 99Tcm-stannous chloride colloid (99Tcm-SCC) was used to label human leukocytes. The radiolabelled leukocytes were then injected intravenously into rats bearing carrageenan-induced inflammation in their hindlimbs. Scintigraphic imaging (n = 3) and biodistribution studies (n = 4) 4 h post-injection were performed. The ratio of radioactivity (cpm/pixel) accumulated in the inflammation site to that in the corresponding area of the contralateral limb was 2.9 +/- 0.8, as calculated by region-of-interest analyses of the planar images. The distribution of radioactivity in the dissected tissue showed that the ratio of radioactivity (cpm/g) of infected tissue to that of a normal sample obtained from the contralateral limb was 2.6 +/- 0.5. The biodistribution study of dissected organs showed high uptake in liver (58.9 +/- 8.2%), spleen (4.3 +/- 1.8%) and lungs (6.3 +/- 2.4%). The results of this preliminary study indicate that 99Tcm-SCC can be used as an alternative agent for radiolabelling leukocytes for the detection of inflammatory lesions.

Animals↗
PubMed1994

Effect of metabolic alterations on the accumulation of technetium-99m-labeled d,l-HMPAO in slices of rat cerebral cortex.

It is widely recognized that the distribution of technetium-99m-labeled d,l-hexamethylpropylene amine oxime (99mTc-HMPAO) in the brain is determined by the regional blood flow. However, other factors may affect this process including the metabolism of the brain tissue. To examine this possibility we studied the effects of metabolic alterations on 99mTc-HMPAO uptake in rat brain cortex slices, with concurrent measurement of oxygen consumption (QO2). 99mTc-HMPAO uptake was determined by incubating slices of rat cerebral cortex at 37 degrees C in Krebs-Ringer phosphate glucose medium containing 99mTc-HMPAO with and without test substances. Differential gradients for 99mTc activity between the tissue and the suspending medium (T/M ratio) were derived from the equation T/M[99mTc] = counts per gram of tissue/counts per milliliter of medium. The QO2 of the brain slices was measured using a biological oxygen monitor equipped with a polarographic oxygen probe. Inhibitors affecting oxidative phosphorylation caused parallel suppression of the T/M ratio and QO2. Agents that uncouple oxidation from phosphorylation increased the QO2 and decreased the T/M ratio. Incubation of slices at 22 degrees C depressed the T/M ratio and QO2. The presence of inhibitors of oxidative phosphorylation in the incubation medium increased the release of 99mTc activity from slices that had been prelabeled with 99mTc-HMPAO. These findings suggest that the altered metabolic status of the brain tissue modulates the kinetics and net accumulation of 99mTc-HMPAO at the cellular level by either depressing uptake, increasing back-diffusion, or both.

2,4-Dinitrophenol↗
PubMed1994

Intrathoracic splenosis mimicking metastatic lung cancer.

A case of posttraumatic intrathoracic splenosis mimicking lung cancer is presented. The diagnosis was made by a radiocolloid liver-spleen study followed by a heat-damaged Tc-99m labeled red cell scan. A favorable change in the staging of the patient's real contralateral lung cancer resulted.

Aged↗
PubMed1994

Gallium-67 scintigraphy as an aid in the detection of spinal epidural abscess.

Gadolinium-enhanced MRI is considered the study of choice for diagnosing spinal epidural abscess (SEA). Most of such cases, however, are not suspected initially, and thus do not benefit from the procedure. A case of SEA is described in which positive Ga-67 scintigraphy shortly before onset of lower extremity dysfunction was instrumental in obtaining an emergency gadolinium-enhanced MRI and establishing the diagnosis.

Abscess↗
PubMed1994

Demonstration of viable, stunned myocardium with technetium-99m-sestamibi.

Delayed improvement of left ventricular contractile function in the setting of acute ischemia followed by reperfusion ("stunned myocardium") has been observed in a number of clinical scenarios, and may have important clinical implications. At present, there are no widely accepted techniques available to demonstrate its presence. We report a case in which a rest 99mTc-sestamibi scan performed 12 hr after thrombolytic therapy in the setting of acute myocardial infarction demonstrated viable myocardium in a region that was akinetic by contrast ventriculography. After surgical revascularization, follow-up 99mTc-sestamibi images showed normal perfusion and radionuclide ventriculography demonstrated normal left ventricular function. Demonstration of preserved 99mTc-sestamibi myocardial uptake in the infarct zone despite an extensive region of akinesis by contrast ventriculography predicted the recovery of left ventricular function after revascularization in this case. This suggests that perfusion imaging with 99mTc-sestamibi early after myocardial reperfusion can detect stunned myocardium and thus facilitate the decision-making process regarding management of such patients.

Coronary Artery Bypass↗
PubMed1992

Changes in septal regional ejection fraction early and late following coronary artery bypass grafting in patients without postoperative myocardial infarction.

Changes in regional ejection fraction (rEF) of the interventricular septum following coronary artery bypass graft (CABG) surgery were examined using first-pass radionuclide ventriculography (RNVG) in patients without objective evidence of postoperative myocardial infarction (MI). One hundred and one patients had pre- (mean 6.3 days) and early postoperative (mean 8.7 days) RNVGs, and 60 of these patients had follow-up studies at 14-39 months (mean 27 months) postsurgery. Early post-CABG, mean rEF in the proximal septum was unchanged from the preoperative value (35.3%), with almost equal numbers of patients showing increased (n = 36), unchanged (n = 33) or decreased (n = 32) rEFs. In the distal septum, mean rEF increased from 47.1 to 50.7%, with more than twice as many patients having increased (n = 44) as decreased (n = 20) rEF. At late follow-up, proximal septum rEF in individual patients tended to revert to the presurgery baseline, with 72% (13/18) of regions with early decrease improved and 61% (14/23) of those with early improvement decreased. In the distal septum, rEF was less than early post-CABG in 76% (19/25) of patients with early improvement, while being improved in 27% (3/11) of those with early decrease in rEF. In the absence of MI, changes in rEF in the proximal septum early post-CABG tend to resolve over time. While global changes in cardiac systolic motion are the probable cause of many new post-CABG septal abnormalities, persistent septal dysfunction probably reflects effects of permanent damage as a result of the operative procedure.

Adult↗
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

Significance of changes in resting left ventricular ejection fraction after coronary artery bypass grafting.

The prognostic significance of changes in resting left ventricular ejection fraction was examined in 102 patients who underwent successful coronary artery bypass grafting. Between preoperative and early postoperative radionuclide ventriculography, mean resting left ventricular ejection fraction improved from 47.2% to 53.9% (p less than 0.01). Left ventricular ejection fraction increased by 5% or greater in 64 patients (63%), remained unchanged (within 4%) in 31 (30%), and decreased by at least 5% in 7 (7%). During 14 to 39 months (mean 27 months) of clinical follow-up, patients with normal preoperative left ventricular ejection fraction had a lower prevalence of recurrent angina, congestive heart failure, and mortality resulting from cardiovascular disease. Cardiovascular morbidity and mortality occurred with equal frequency for patients who did and did not show early postoperative improvement in left ventricular ejection fraction (36% versus 39%). Among 69 patients who had a third radionuclide ventriculography at late follow-up, left ventricular ejection fraction was less than the early postoperative value in 69% and less than the preoperative result in 36%. Patients with early postoperative improvement in left ventricular ejection fraction were more likely to retain resting left ventricular contractile function, at least at the preoperative level (71% versus 46%).

Adult↗
PubMed1990

Persistent chest pain following oral dipyridamole for thallium 201 myocardial imaging.

A patient was admitted to the hospital with acute chest pain. After acute myocardial infarction was ruled out, he underwent a stress thallium 201 scintigraphy using oral dipyridamole and developed persistent angina with ST-segment elevation. This complication has not been reported previously. It is recommended that appropriate intervention be available if severe ischemia develops following administration of dipyridamole for diagnostic imaging.

Angina Pectoris↗
PubMed1990

Intrahepatic cholestasis due to hypersensitivity reaction to procainamide.

Hypersensitivity reactions to procainamide involving liver dysfunction are rare. We describe a patient who developed liver dysfunction after procainamide administration, manifested by fever, jaundice, elevated bilirubin concentration, and alkaline phosphatase concentration. Hepatobiliary scintigraphy demonstrated good hepatic uptake of the radionuclide without movement from hepatic parenchyma. To our knowledge, this is the first reported case of procainamide-induced intrahepatic cholestasis as demonstrated by radionuclide hepatobiliary scintigraphy.

Aged↗
PubMed1987

Effects of the Mueller maneuver on global and regional left ventricular function in angina pectoris with or without previous myocardial infarction.

In patients with coronary artery disease, left ventricular (LV) regional wall akinesia can develop during the Mueller maneuver. The present study determines if the presence of myocardial ischemic disease with no infarction is a sufficient condition for this to occur, or if the presence of prior acute myocardial infarction (MI) is necessary. In men, first-pass radionuclide ventriculography was performed in the 30 degree left anterior oblique supine position to measure LV ejection fraction, end-diastolic and end-systolic volumes and heart rate, and to obtain an image of the LV cavitary perimeter. This procedure was performed in 4 subject groups: 13 normal volunteers, 25 patients with coronary artery disease but no prior MI, 13 patients with coronary artery disease and prior nontransmural MI, and 36 patients with coronary artery disease and prior transmural MI. All patients had angina and underwent routine contrast coronary angiography; 60 also underwent contrast coronary angiography; 60 also underwent contrast LV angiography. Ejection fraction decreased during the Mueller maneuver in each of all the coronary artery disease groups (p less than 0.01), but not in the normal subjects. Heart rate increased in groups 1, 2 and 4 (p less than 0.01), and end-diastolic volume decreased in all 4 groups (p less than 0.01), whereas end-systolic volume did not change. Only in group 4 did regional wall akinesia develop (17 patients) during the Mueller maneuver. Among patients who had akinesia during the Mueller maneuver and also underwent routine contrast ventriculography, half of the akinetic segments were not seen on routine contrast study, but were seen only on radionuclide ventriculography during the Mueller maneuver.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1987

Mueller maneuver and LV function in coronary artery disease.

Decreasing pleural pressure impedes the ejection of blood from the left ventricle (LV), may lead to decreased LV compliance because of interdependence effects and leads to increased transmural LV systolic and diastolic pressure. Previous work from this laboratory has shown that patients with coronary artery disease (CAD) often develop akinetic segments of the LV wall during the Mueller maneuver. In the presence of increased LV transmural pressure regional akinesis could be caused either by the development of regional ischemia or by mechanical inhibition of motion of an area of nonfunctional myocardium as would be caused by previous myocardial infarction (MI). The present study was designed to distinguish between these two mechanisms by determining if the presence of CAD alone is sufficient to lead to regional akinesis or if prior MI is necessary. We used first pass radionuclide ventriculography (RVG) in the 30 degrees LAD supine position to measure LV ejection fraction (EF), end-diastolic (EDV) and end-systolic (ESV) volumes, heart rate and to assess regional wall motion during the Mueller maneuver. This was done in four groups of subjects: 13 normal subjects, 25 patients with CAD but no prior MI, 13 patients with prior nontransmural MI and 36 patients with prior transmural MI. All subjects had angina pectoris and underwent contrast coronary arteriography. Most also underwent routine contrast left ventriculography as well. There were no significant differences among the three patient groups as regards medications, extent and severity of CAD, and response to routine exercise tolerance testing. EF decreased significantly in the three patient groups (4%-9%, p less than 0.01) but not in the normals during the Mueller maneuver. Heart rate increased (5-10 bpm, p less than 0.05) in the normals and in patient groups 2 and 4. EDV decrease in all four subject groups (8%-10%, p less than 0.01), while ESV remained unchanged. Akinesis of the LV wall developed during the Mueller maneuver only in one group-2 patient, but did so in 17/36 patients with prior transmural MI (group 4, p less than 0.001). One-half of the akinetic LV wall segments seen during the Mueller maneuver on RVG were not seen on routine contrast ventriculography. We tested the effects of posture (supine versus upright) on the response to the Mueller maneuver in six normal subjects and found no changes in the response of EDV and ESV to the Mueller maneuver.(ABSTRACT TRUNCATED AT 400 WORDS)

Coronary Disease↗