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Biomedical subjects

M D Ezekowitz

Publications and source records attributed to M D Ezekowitz.

At least 73 records · Page 4Linked to original sources
PubMed1984

Double-blind, placebo-controlled trial of propranolol given once, twice and four times daily in stable angina pectoris: a multicenter study using serial exercise testing.

To determine if propranolol given twice daily (b.i.d.) or once daily (q.d.) was as effective as 4 times daily (q.i.d.) for treatment of stable angina pectoris, 78 patients with exercise-induced ST depression of 1.5 mm were randomized to q.i.d., b.i.d., q.d. and placebo groups. All patients received 5 tablets per day, and propranolol groups received 80, 160 and 320 mg/day on successive weeks. At weekly visits, patients underwent treadmill exercise testing before the 8:00 AM dose and at 2 and 9 hours afterward. Exercise duration (seconds) was significantly improved at the final visit compared with baseline by b.i.d. (120 +/- 36 [mean +/-] standard error of the mean p less than 0.001 n = 18) and q.i.d. (100 +/- 37, p less than 0.01; n = 17) regimens, but not by the q.d. (30 +/- 33; n = 18) and placebo regimens (27 +/- 37; n = 17). There was a significant decrease from baseline in the magnitude of ST depression at the final visit, measured at maximal common exercise duration in b.i.d. (-0.96 +/- 0.20 mm, p less than 0.001), q.i.d. (-0.84 +/- 0.20 mm, p less than 0.01) and q.d. (-0.58 +/- 0.18 mm, p less than 0.05) groups, but not in the placebo group (0.03 +/- 0.2 mm). Hourly heart rate by Holter was reduced in all 3 propranolol groups; however, the mean serum propranolol level was significantly lower just before the first dose with q.d. group (56 +/- 20 ng/ml) compared with b.i.d. and q.i.d. groups (146 +/- 22 and 119 +/- 28 ng/ml) with 320 mg/day (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Detection of active left ventricular thrombosis during acute myocardial infarction using indium-111 platelet scintigraphy.

Platelet scintigraphy with radioactive indium-111 may be used both to identify and to reflect the activity of thrombin in vivo in man. Forty-one patients with acute myocardial infarction were studied for active left ventricular thrombosis by platelet scintigraphy and followed until in-hospital death, discharge, or same-admission cardiac surgery for evidence of systemic embolization. A total of 4.7 +/- 2.4 X 10(9) platelets (mean +/- 1 SD) labelled with 381 mu Ci +/- 51 mu Ci of indium-111 was injected intravenously at 91 +/- 88 hours following the onset of chest pain. Patients were imaged in multiple views on the day of and three to four days after injection of the platelet suspension. Group 1 (n = 29) had transmural myocardial infarctions, of which 21 were anterior (peak total level of creatine phosphokinase [CPK], 2,272 +/- 2,026 IU; mean +/- 1 SD) and eight were inferior (CPK level, 1,673 +/- 589 IU). Group 2 (n = 12) had subendocardial myocardial infarctions (CPK level 799 +/- 751 IU). Those with subendocardial and transmural inferior myocardial infarctions had neither left ventricular thrombosis nor emboli. Ten (48 percent) of 21 with anterior transmural myocardial infarctions had left ventricular thrombosis by platelet scintigraphy. Three with and one without such thrombosis by scintigraphy had acute neurologic episodes. In the group with anterior myocardial infarctions, seven of ten patients with and four of 11 without left ventricular thrombosis received heparin subcutaneously (chi 2 = 1.22 [Yates correction]; p greater than 0.30). We conclude that platelet scintigraphy may be used to monitor antiplatelet and anticoagulant therapy in patients with anterior transmural myocardial infarctions who are at risk for left ventricular thrombosis and systemic embolization.

Aged↗
PubMed1983

Diagnostic accuracy of indium-111 platelet scintigraphy in identifying left ventricular thrombi.

This study defines the optimum imaging time window after injection of labeled platelet suspension for detection on left ventricular (LV) thrombi, identifies the most useful imaging views, and determines the reproducibility of this technique. A total of 662 images obtained from 64 patients were analyzed retrospectively on 2 separate occasions by 3 observers blinded as to patient identity, view (right anterior oblique, anterior, left anterior oblique, and left lateral), and time after injection of the platelet suspension that the images were obtained (0 to 2, 3 to 4, and 5 to 6 days). Images were categorized as either positive or negative. In every case surgical or autopsy verification of the presence or absence of LV thrombus was possible. The best combination of sensitivity, specificity, and diagnostic accuracy was found in the 3- to 4-day period in the left anterior oblique view and was 54 +/- 5% (mean +/- standard deviation), 98 +/- 1%, and 85 +/- 2%, respectively. Sensitivity, specificity, and diagnostic accuracy were not enhanced by adding additional views (right anterior oblique, left lateral, and anterior) to the left anterior oblique view in the 3- to 4-day time period. However, using multiple views, localization of thrombi to the left ventricle was facilitated. In a second retrospective analysis, a comparison of day 0 with day 3 to 4 images enhanced sensitivity and accuracy to 65 (p less than 0.001) and 90% (not significant), respectively. Specificity was unchanged at 99%. Mean intra- and interobserver agreement was 91 and 88%, respectively. Thus, (1) indium-111 platelet scintigraphy is a reproducible and specific technique for identifying LV thrombus, and (2) we advise imaging on day 0 and again 3 to 4 days after injection of the platelet suspension in right anterior oblique, left anterior oblique, left lateral, and anterior views to maximize accuracy and to facilitate localization of LV thrombus.

Blood Platelets↗
PubMed1982

Comparison of Indium-111 platelet scintigraphy and two-dimensional echocardiography in the diagnosis of left ventricular thrombi.

In a study comparing indium-111 platelet scintigraphy and two-dimensional echocardiography as methods of identifying left ventricular thrombi, the results obtained with both techniques were verified at surgery or autopsy in 53 patients--34 with left ventricular aneurysms, and 19 with mitral-valve disease. Left ventricular thrombi were found at surgery or autopsy in 14 of the patients with aneurysms and in none of those with mitral-valve disease. Thirteen of 53 echocardiograms (25 per cent) were technically inadequate and excluded from the analysis. In the group with aneurysms, the sensitivity of scintigraphy in detecting thrombi was 71 per cent, and that of echocardiography was 77 per cent. The specificity of scintigraphy was 100 per cent, and that of echocardiography was 93 per cent. We conclude that indium-111 platelet scintigraphy and two-dimensional echocardiography have useful and complementary roles in the detection of left ventricular thrombi. Both these noninvasive techniques can be used to monitor therapy.

Adult↗
PubMed1982

Human platelets labeled with In-111 8-hydroxyquinoline: kinetics, distribution, and estimates of radiation dose.

Platelets from nine normal male subjects were labeled with In-111 8-hydroxyquinoline (In-111 oxine) in the presence of plasma in either "closed" blood transfer packs or in "open" test tubes. The mean labeling efficiencies in these two systems were 27 and 53%, respectively. Mean survival time of In-111-labeled autologous platelets was 8.76 days, with a standard deviation of 1.05 according to the maximum-likelihood estimate of the gamma-function model. The initial recovery of In-111 platelets in the circulation was 57% with a standard deviation of 11%. The distribution of In-111 platelets in liver and spleen was quantitated by anterior, posterior, and transmission gamma-camera imaging. During the first 30 min, 38% of the injected dose accumulated in the spleen, 13% in the liver. No significant increase in In-111 radioactivity was observed in either of the two organs over a 3-9-day period. The bone marrow was an additional site of In-111 accumulation. The spleen was the critical organ with respect to radiation dose. The splenic dose was estimated to be 34 rad/mCi In-111 platelets, that of the liver 2.1 rad/mCi. With the injection of 100-150 microCi of In-111-labeled platelets in normal subjects, giving a splenic radiation of 5 rad, a complete 10-day survival study can be performed and uptake of In-111 in different organs can be measured quantitatively for at least 3-4 days.

Adult↗
PubMed1981

Failure of aspirin to prevent incorporation of indium-111 labelled platelets into cardiac thrombi in man.

The in vitro and in vivo behaviour of platelets was studied in eleven patients with left ventricular aneurysms and mural thrombi. Five patients were on aspirin 300-2400 mg/day; the remaining six patients were controls. In vitro function was tested by the aggregation response of platelets to adenosine diphosphate (ADP) and collagen. In vivo function was assessed by the incorporation of indium-111-labelled platelets into cardiac thrombi as measured by scintigraphy. Platelets from patients on aspirin, whether tested before or after labelling, aggregated less with collagen than did those of controls (18 vs 52%; p less than 0.01 before labelling, 13 vs 49%; p less than 0.02 after labelling). Second wave aggregation, induced by ADP, was impaired in patients on aspirin. In all patients scintigraphy showed that the autologous labelled platelets were incorporated into ventricular thrombi. Thus, although in vitro the platelets from patients on aspirin aggregated subnormally, in vivo they took part in thrombosis.

Aspirin↗
PubMed1980

Effect of aging on permeability of cockerel aorta to 125I-albumin.

The in vivo uptake of 125I-albumin (A), containing < 1% free iodide, by the cockerel aorta 10-243 min after intravenous injection was quantitatively studied in 22 normotensive normolipemic anesthetized cockerels, Uptake initially was rapid and linear with time (T) (10-37 min), thereafter slowing and approaching an equilibrium with the blood. The permeability of the wall (Pm) to A was defined as accumulated wall activity/mean blood activity X endothelium surface area X T from intravenous injection to death of animal for T in the range 10-37 min. Pm was determined in the young group, age 197 +/- 51 days (means +/- SD; n = 6), which represented cockerels close to puberty, and compared to a middle-aged group, age 591 +/- 15 days (n = 5). Pm in the older group, 1.5 X 10(-6) +/- 0.218 ml . cm-2 . s-1 (means +/- 1 SE) was twofold greater than the younger group, 0.813 X 10(-6) +/- 0.046 (P < 0.0001). Total cholesterol content, within the wall in 12 different animals, was unchanged over the period 130-320 days. It is concluded that Pm to A increases with age as part of a physiological process. This finding should be considered in any model of atherosclerosis.

Aging↗
PubMed1978

Isolated drainage of the superior vena cava into the left atrium in a 52-year-old man: a rare congenital malformation in the adult presenting with cyanosis, polycythemia, and an unsuccessful lung scan.

This report describes a 52-year-old black male with the isolated finding of an anomalous superior vena cava draining into the left atrium. The patient presented with dizziness, mild cyanosis, polycythemia and normal cardiac and pulmonary findings. The first major diagnostic clue in this confusing clinical presentation was an unsuccessful lung perfusion scan in which intravenous tracer consistently bypassed the lungs. This appears to be the first adult presenting with this rare anomaly. This condition should be suspected if cyanosis, clubbing, and a "normal" cardiac examination coexist and if the more common pulmonary and hematological causes of this triad have been excluded.

Cyanosis↗
PubMedDate not supplied

Use of an electromechanical infusion pump for transfusion of platelet concentrates.

To determine whether platelet concentrates can be administered safely through electromechanical infusion devices, we studied stored platelet concentrates passed through one pump system (Abbott). We measured in vitro changes in platelet count and lactic dehydrogenase (LDH) and beta-thromboglobulin (beta-TG) release which occurred after passing the concentrates through the pump system. To compare in vivo survival, five normal volunteers were given an injection of autologous Indium-111-labeled platelet concentrates at two different times, once using platelets which had been passed through the pump system (test group) and once using platelet concentrates which had not (control group). In vitro studies showed no significant changes (p greater than 0.05) in platelet count, or in LDH or beta-TG release after passage through the pump system. In vivo platelet recovery at 2 hours was 39.8 +/- 4.7 percent (mean +/- 1 SD) for the control platelets and 40.7 +/- 9.3 percent for the platelets passed through the pump system (p greater than 0.05; n = 5). There was no significant difference in platelet survival measured in days between the control group and the test group using a linear (8.0 +/- 0.9 vs. 7.2 +/- 0.3), exponential (3.7 +/- 0.7 vs. 3.1 +/- 0.5), or multiple hit (5.4 +/- 2.3 vs. 4.8 +/- 1.0) (p greater than 0.05; n = 5) model. We conclude that this pump system is acceptable for use in clinical practice when control over volume and rate of platelet transfusion is important.

Blood Transfusion↗
PubMedDate not supplied

The effect of mode of agitation and type of plastic bag on storage characteristics and in vivo kinetics of platelet concentrates.

We studied the characteristics of platelet concentrates stored for 5 days at 22 degrees C. Platelets were prepared in three plastic bags (PL 732, PL 1240, and CLX) and stored on one of four platelet agitators, 1- or 6-rpm elliptical and 2- or 6-rpm circular rotators. A total of 76 studies were divided among 12 groups, each group being composed of a different storage bag-rotator combination. In vivo recovery and survival were calculated using Indium-111 oxine-labeled platelets injected into autologous volunteers. Platelet recovery was assessed at 2 hours postinjection or as the y-intercept of the multiple-hit model survival curve. Survival was calculated using linear, exponential, and multiple-hit computer models. Linear T 1/2 also was calculated as an index of platelet survival. At 5 days, the pH of all concentrates was above pH 7.0 and platelet counts were above 5.5 X 10(10) per bag except for the PL 732 with the 6-rpm elliptical rotator, which was 4.6 X 10(10) per bag. This combination also showed a significantly higher poststorage lactic dehydrogenase (LDH) discharge compared to the mean of the other 11 groups (23.6 +/- 5.4% vs. 10.4 +/- 3.0%, p less than 0.05); however, the beta-thromboglobulin (beta-TG) release was not statistically different.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Donors↗