1. Although ventilation in normal human lungs has been shown to decrease from apex to base, comparable observations are lacking in regard to particle deposition. 2. We compared regional ventilation and particle deposition in normal subjects by using radioactive xenon and a radioactive aerosol while sitting, lying, and while breathing at an increased rate. Both smokers and non-smokers were studied. 3. Particle deposition and ventilation were closely related, and the greater the ventilation the greater the deposition of particles, a situation which prevailed irrespective of position and breathing rate. While supine, the apex to base gradient for both ventilation and particle deposition decreased but did not entirely disappear. At higher respiratory rates, central deposition of particles, especially in smokers, increased. 4. We concluded that there are regional differences in the deposition of particles and that such differences are closely related to regional ventilation.
1. The change in total body calcium content after surgery for primary hyperparathyroidism was studied in seven patients by whole body neutron activation analysis. Three patients who remained in the uncontrolled state for up to 12 months were also studied by this technique. 2. The technique and its reproducibility are described. Changes in total body calcium greater than ±4% should be detectable using this method. 3. The change in total body calcium after surgery was variable. Total body calcium content decreased in three cases after apparently successful parathyroidectomy. Not all the cases experiencing an increase in body calcium content had radiological evidence of bone disease. 4. The role of relative hypoparathyroidism due to suppression of normal parathyroid tissue by a functioning adenoma is discussed.
1. The distribution of intravenously administered 18 F was investigated in thirty-one normal human volunteers, seven patients with acute or chronic renal failure and two patients with malignant disease. The object was to define some features of the bodily distribution and handling of 18 F in the hope that this will shed some light on fluoride physiology in health and disease. 2. Plasma radioactivity at any given time depends on the degree of diffusion of 18 F through the extracellular fluid as well as on the competing effects of renal excretion and tissue uptake. The factors governing these last two functions are discussed. 3. At 1 h after injection 40% of the administered dose of 18 F is contained in the extracellular fluid, 20% has been excreted and 40% taken up by the tissues, including 2·5% into erythrocytes.