ABSTRACT
We report a comparison of the results obtained at 500 MHz for heteronuclear shift correlation (HSQC) experiments with very small natural product samples using conventional and cryogenically cooled 3 mm NMR probes. The cryo probe affords a 12- to 16-fold reduction in data acquisition time for a comparable signal-to-noise ratio.
Subject(s)
Magnetic Resonance Spectroscopy/methods , Poisons/chemistry , Strychnine/chemistry , Cold Temperature , Magnetic Resonance Spectroscopy/instrumentationABSTRACT
Methyl iodide-131 (CH3I-131) is described as an agent for detection of acute experimentally produced pulmonary arterial occlusion in dogs. When gaseous CH3I-131 is inhaled, radioactivity passes instantaneously from the alveoli to the lung capillary bed. Where pulmonary blood flow exists, activity is washed out into the systemic circulation, but in areas of blood stasis, a transient pulmonary "hot spot" remains. CH3I-131 is easily produced and inexpensive, but administration is awkward and strict radiation safety precautions are mandatory.
Subject(s)
Arterial Occlusive Diseases/diagnostic imaging , Iodine Radioisotopes , Pulmonary Artery , Serum Albumin , Technetium , Animals , Dogs , Iodine Radioisotopes/administration & dosage , Pulmonary Circulation , Pulmonary Embolism/diagnostic imaging , Radionuclide Imaging , Technetium Tc 99m Aggregated AlbuminABSTRACT
The renal extraction efficiencies for various radioactive agents were measured in normal anesthetized dogs during 1 hr after a single intravenous injection. Radioassays were made on serial blood samples drawn simultaneously from the aorta upstream from the renal arteries and from one renal vein. As a reference substance [131I]o-iodohippurate was injected concurrently in all experiments. Blood clearances from serial venous samples and urinary excretion also were measured. Extraction efficiency from whole blood was calculated as (A-V) divided by A, where A = aortic concentration and V = renal venous concentration. This ratio for commercial [131I]o-iodohippurate fell steadily from 88% at 30 sec to 50% at 1 hr. For "purified" [131I]o-iodohippurate the fall was less marked, to 61% at 1 hr. The EE ratios for all other agents were stable after the first minute. The Tc-99m complexes of DTPA, glucoheptonate, and acetylcysteine had ratios averaging 27-29%. The ratios of Tc-99m DMS and Hg-197 chlormerodrin had much lower average values of 8 and 14%, respectively. None of the newer agents approached the extraction efficiency of [131I]o-iodohippurate.
Subject(s)
Iodohippuric Acid/metabolism , Kidney/diagnostic imaging , Technetium/metabolism , Animals , Aorta , Bone and Bones/diagnostic imaging , Bone and Bones/metabolism , Dogs , Iodohippuric Acid/blood , Iodohippuric Acid/urine , Kidney/blood supply , Kidney/metabolism , Radionuclide Imaging , Reference Values , Renal Artery , Renal Veins , Technology, Pharmaceutical , Time FactorsABSTRACT
We have occluded segmental and subsegmental pulmonary arteries in the dog with Swan-Ganz balloon catheters or i.v. injection of autologous clot, and have studied the chest with transmission computed tomography (TCT), Tc-99m-MAA gamma imaging, and plain radiographs. The arterial occlusions were between 1 and 5 hr old at the time of imaging. Radiographs revealed no lesions. Tc-99m MAA scanns revealed ten of 11 lesions. When a TCT image was made before i.v. injection of Renografin-60, two of 11 lesions were identified; after Renografin the score was four out of ten. The appearance of lesions on TCT was highly variable. Tc-99m-MAA gamma imaging, therefore, is far more accurate than TCT in the identification of small experimentally produced acute pulmonary arterial occlusions in the dog, and our study fails to suggest a secure place for TCT in the diagnosis of small, acute human pulmonary emboli. The commonly-held assumption that postembolic lung is oligemic is questioned.
