Brian R. Moyer

Biodistribution and autoradiographic localization of I-125--labeled synthetic Peptide in aortic atherosclerosis in cholesterol-fed rabbits.

I-125-labeled SP4 is a synthetic oligopeptide derived from apolipoprotein B of low-density lipoprotein that has been shown to localize in atherosclerotic plaques in experimental animals. However, its biodistribution and mechanism of localization need to be further elucidated. Twenty-four cholesterol-fed (CF) and 20 normal (NL) New Zealand White rabbits were injected with I-125-SP4 and killed 15 to 30 min (6 NL; 6 CF) or 2 h (14 NL; 18 CF) later. We obtained aortic autoradiograms and activity concentrations (% injected dose/gin) in aortic segments and other tissues. The uptake of I-125-SP4 was higher in CF than in NL rabbits in all aortic segments (p < 0.05). I-125-SP4 was cleared rapidly in both CF and NL rabbits with 60 to 70% of the injected dose cleared from the blood by 1 h. No statistically significant differences in radiotracer biodistribution were observed between NL and CF rabbits although activity tended to be higher in the liver, gallbladder, and intestine in NL rabbits and in the kidney and spleen in CF rabbits. Silver grains were distributed mainly on foam cells of the fatty streaks in aortic microautoradiograms from two additional rabbits that had been injected with I-125-SP4. There were 23,518 ± 15,878 (SD) grains/mm2 in fatty plaques but only 14,669 ± 11,035 grains/mm2 in media muscle (p< 0.0001 [9 sections, 17 areas evaluated] in an atherosclerotic animal) in injected animals and 13,439 ± 5,565 grains/mm2 in media muscle (two sections, four areas) in the normal control animals (NS versus media of atherosclerotic animal). I-125-SP4 specifically localizes in aortic atherosclerotic plaques in CF rabbits. There is no significant difference in tissue distribution between normal and CF rabbits except in the aorta. Preliminarily, it appears that the site of tracer uptake is on foam cells and this suggests the possibility of relative specificity for fatty plaque.

Radionuclide and Nuclear Magnetic Resonance Methods of Evaluating Atherosclerosis

Radionuclide techniques devoted to the evaluation of the atherosclerotic process have focused on measurements of function and metabolism of the heart and brain that might be affected by atherosclerosis, as well as on detection of thrombus formation in major arteries within and leading to these organs. This approach has more recently been joined by efforts to study the biochemical behavior of the arterial wall itself as well as the interaction of blood constituents with the components of the arteries. There is now sufficient basis to predict that we will be able to study facets of the atherosclerotic process in man using not only labeled platelets, labeled fibrin, and labeled lipoproteins, but labeled monoclonal antibodies to arterial wall constituents, fibrin, and lipoprotein receptor sites.

Effect of temperature on the latent track fading rate of AgC1 (cadmium doped) crystal detectors

Author(s): McGinnis, John; Cassou, Ronald; Benton, Eugene V.; Budinger, Thomas; Moyer, Brian.