strontium-radioisotopes and Ischemia

Topics: Angina Pectoris; Animals; Arteriosclerosis; Blood Flow Velocity; Coronary Circulation; Coronary Disease; Diffusion; Dogs; Electrocardiography; Heart; Heart Ventricles; Humans; Ischemia; Male; Middle Aged; Myocardial Infarction; Oxygen; Strontium Radioisotopes

We examined the effect of rigid plate application on the radiostrontium clearance of the intact canine femur at 6 months. We examined each of the component surgical steps. We calculated the clearance both for the whole bone and for each of the five transverse sections of the whole bone. Screw application, but not drilling, increased the clearance in the segment about the screw holes. Plate application produced an increase in the segment beneath the plate as well as around the screws and in the whole bone. These changes are accomplished not only by an absolute increase in clearance to the middle three segments, but by a relative diminution in clearance by the most proximal and distal segments. The histomorphometric changes in long bones following rigid plating may be accompanied by regional increases in bone blood flow.

Topics: Animals; Bone and Bones; Bone Diseases, Metabolic; Bone Plates; Bone Screws; Dogs; Femur; Fracture Fixation, Internal; Ischemia; Postoperative Complications; Radionuclide Imaging; Regional Blood Flow; Strontium Radioisotopes

The effects of each of the surgical stages involved in compression plating on the development of cortical thinning and porosity were assessed in the intact midshaft, stress-shielded femoral segments of adult mongrel dogs 6 months postoperatively. The data were evaluated in terms of a postsurgical tetracycline-based measure of remodeling and terminal 85Sr clearance (SrC) values for the plated segments of bone. Drilling had no effect on any parameter. Screw application was associated with minimal cortical thinning (p less than 0.05), while plate fixation clearly promoted thinning (p less than 0.01) and porosity (p less than 0.05). The percentage of labeled osteons, a measure of remodeling activity, increased only after plate fixation (p less than 0.05), and the labeling patterns suggested that most osteons had formed during the first 4 postsurgical months. That none of these changes were correlated with the 6-month SrC values suggests that the development of plate-induced osteopenia involves disparate histomorphometric time constants, rather than lack of any association.

Topics: Animals; Bone and Bones; Bone Diseases, Metabolic; Bone Plates; Bone Screws; Dogs; Femur; Fracture Fixation, Internal; Ischemia; Postoperative Complications; Regional Blood Flow; Strontium Radioisotopes; Wound Healing

We evaluated the effect of scleral buckling procedures on uveal blood flow in rabbits by injection of microspheres labeled with strontium 85. Cerclage reduced both anterior and posterior uveal blood flow, and removing the cerclage returned the blood flow to normal. Sham cerclage and local scleral buckle did not decrease blood flow.

Topics: Animals; Ischemia; Microspheres; Rabbits; Regional Blood Flow; Scleral Buckling; Strontium Radioisotopes; Uvea

This study was designed to determine whether coronary vasodilation distal to a flow-limiting coronary artery stenosis could result in redistribution of myocardial blood flow to produce subendocardial underperfusion. Studies were performed in 10 awake dogs chronically prepared with electromagnetic flow-meters and hydraulic occluders on the left circumflex coronary artery. Regional myocardial blood flow was measured using radionuclide-labeled microspheres, 7-10 mum in diameter, injected into the left atrium. A 5(-s) coronary artery occlusion was followed by reactive hyperemia with excess inflow of arterial blood effecting 375+/-20% repayment of the blood flow debt incurred during occlusion. When, after a 5(-s) occlusion, the occluder was only partially released to hold arterial inflow to the preocclusion level for 20 s before complete release, the delayed reactive hyperemia was augmented (mean blood flow repayment = 610+/-45%, P < 0.01). This augmentation of the reactive hyperemia suggested that ischemia was continuing during the interval of coronary vasodilation when coronary inflow was at the preocclusion level. Measurements of regional myocardial blood flow demonstrated that endocardial flow slightly exceeded epicardial flow during control conditions. When arterial inflow was limited to the preocclusion rate during vasodilation after a 5(-s) total coronary artery occlusion, however, flow to the subepicardial myocardium was increased at the expense of underperfusion of the subendocardial myocardium. Thus, in the presence of a flow-limiting proximal coronary artery stenosis, ischemia-induced coronary vasodilation resulted in redistribution of myocardial blood flow with production of subendocardial ischemia in the presence of a net volume of arterial inflow which, if properly distributed, would have been adequate to prevent myocardial ischemia.

Topics: Animals; Cerium Isotopes; Computers; Coronary Circulation; Coronary Disease; Coronary Vessels; Dogs; Electromagnetic Phenomena; Endocardium; Heart Rate; Hemodynamics; Hyperemia; Ischemia; Radioisotopes; Rheology; Scandium; Spectrometry, Gamma; Strontium Radioisotopes

Topics: Animals; Body Weight; Diuresis; Glomerular Filtration Rate; Hematocrit; Hemodynamics; Ischemia; Kidney; Kidney Cortex; Male; Microspheres; Rats; Regional Blood Flow; Strontium Radioisotopes; Time Factors; Ureteral Obstruction; Urine

Topics: Adolescent; Adult; Chronic Disease; Diagnosis, Differential; Fascia; Fasciotomy; Female; Fractures, Bone; Humans; Ischemia; Leg; Leg Injuries; Male; Muscular Diseases; Necrosis; Pain; Physical Exertion; Sports Medicine; Strontium Radioisotopes

Topics: Animals; Aorta; Blood Pressure; Cerium Isotopes; Chromium Radioisotopes; Depression, Chemical; Female; Heart Ventricles; Iodine Radioisotopes; Ischemia; Kidney; Methods; Microspheres; Nobelium; Pentobarbital; Pregnancy; Pulmonary Circulation; Rabbits; Radioisotopes; Strontium Radioisotopes

Topics: Autoradiography; Femur Head; Femur Head Necrosis; Humans; Ischemia; Regional Blood Flow; Strontium Radioisotopes

Topics: Animals; Assisted Circulation; Cesium Isotopes; Chromium Radioisotopes; Coronary Circulation; Coronary Disease; Dogs; Female; Ischemia; Male; Methods; Microspheres; Radioisotopes; Strontium Radioisotopes; Time Factors

Topics: Animals; Blood Flow Velocity; Blood Pressure; Cardiac Output; Cesium Isotopes; Coronary Circulation; Coronary Disease; Coronary Vessels; Dogs; Electrocardiography; Heart Ventricles; Hemoglobins; Ischemia; Ligation; Microspheres; Oxygen; Oxygen Consumption; Radioisotopes; Strontium Radioisotopes

Topics: Aged; Antineoplastic Agents; Bone Diseases; Cortisone; Female; Hip Dislocation, Congenital; Humans; Ischemia; Knee; Leg Length Inequality; Male; Necrosis; Polyneuropathies; Radiography; Radionuclide Imaging; Strontium Radioisotopes