strontium-radioisotopes and Pneumonia

A nonparametric hazard-function (HP) method for generating monotonically increasing incidence vs dose curves after long-term exposure to a toxic agent (e.g. radiation or chemical carcinogens) is described in detail in this paper. Here, incidence refers to the response-probability estimate that is adjusted for competing risks. The maximum likelihood principle was used to arrive at an appropriate point estimate of the cumulative hazard function (i.e. the negative natural logarithm of the proportion of the nonresponders) and the response probability for an array of doses that depends on the data set to be analyzed. The resultant point estimates can be used to develop or select an appropriate model for risk vs dose assessment. As an example of the application of the HF method, data for liver neoplasms caused by long-term exposure of mice to 2-acetylaminofluorene and data for radiation pneumonitis and pulmonary fibrosis caused by long-term exposure of dogs to ionizing radiation are analyzed.

Topics: 2-Acetylaminofluorene; Animals; Dogs; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Female; Liver Neoplasms; Mice; Neoplasms, Experimental; Pneumonia; Pulmonary Fibrosis; Risk; Strontium Radioisotopes; Time Factors

Topics: Alpha Particles; Animals; Cell Survival; Cesium Radioisotopes; Dogs; Dose-Response Relationship, Radiation; Electrons; Gamma Rays; Models, Biological; Plutonium; Pneumonia; Pulmonary Fibrosis; Radiation Injuries, Experimental; Radiation, Ionizing; Relative Biological Effectiveness; Strontium Radioisotopes; Yttrium Radioisotopes

Acute lobar pneumonia and pulmonary embolism were induced in rabbits and the blood flow in the pulmonary artery and bronchial arteries was determined using isotopic microspheres. In acute pneumonia the pulmonary artery flow to the involved lung was reduced 8.5 times and the bronchial artery flow was reduced 5.0 times compared to flow in the normal lung. In acute pulmonary embolism, both the pulmonary artery flow (2.3 times) and the bronchial artery flow (2.5 times) were also reduced. For all animals, the reduction in pulmonary artery flow paralleled the reduction in bronchial artery flow (r=0.65).

Topics: Acute Disease; Animals; Blood Flow Velocity; Bronchial Arteries; Cesium Radioisotopes; Female; Microspheres; Pneumonia; Pulmonary Artery; Pulmonary Circulation; Pulmonary Embolism; Rabbits; Strontium Radioisotopes

Topics: Animals; Morbidity; Pneumonia; Radiation Effects; Rats; Strontium; Strontium Isotopes; Strontium Radioisotopes