Ernest L. Dobson

The Measurement of Liver Circulation by Means of the Colloid Disappearance Rate: I. Liver Blood Flow in Normal Young Men

A method for calculating the liver blood flow by means of the rate of disappearance of colloidal chromic phosphate from the blood has been reviewed. This method has been applied to the study of liver circulation in a group of 29 fasting normal men. The significance of the colloid disappearance rate constant as a physiologic expression of the liver blood flow has been discussed and the average value obtained for this constant in normal young men was 0.287 ± 0.007 min.−1 Extra hepatic colloid localization, hepatic efficiency for colloid removal, speed of mixing, and type and time of sampling have been discussed.

Cell division and phagocytic activity in liver reticulo-endothelial cells.

Summary Radioautographs of liver sections from mice given tritiated thymidine were used to identify the cells which were preparing for division and colloidal saccharated iron oxide was used to identify the active phagocytic cells. In livers of mice whose reticulo-endothelial system was stimulated by estradiol, it was established that the cells preparing for division and those which had recently divided were actively phagocytic. In livers of mice whose reticulo-endothelial system had been “blockaded” with saccharated iron oxide, it was established that the cells which had phagocytized colloid were able to divide in the process of recovery from “blockade.” No evidence was found for a stem cell which proliferates and differentiates to provide the active phagocytic population.

Studies of Human Peripheral Blood Flow: The Effect of Injection Volume on the Intramuscular Radiosodium Clearance Rate

The effects of changes in injection volume on the intramuscular radiosodium clearance rate was investigated in six normal young men. The clearance rate was found to be quite sensitive to the volume of solution injected, and an increase in the rate of clearance corresponding to a decrease in volume was uniformly noted. Rigid control of the injection volume is necessary when this method is used for regional blood flow measurements.

Factors Concerned in the Early Stages of Thermal Shock

The present study is concerned with the early stages of burn injury and demonstrates that the factor of plasma volume reduction does not adequately account for the prompt, precipitous fall in cardiac output.

The Measurement of Total "Sodium Space" and Total Body Sodium in Normal Individuals and in Patients with Cardiac Edema

Total sodium space and total body sodium contents were determined in four groups of individuals with the aid of radiosodium24. There appears to be an increase in these values with age, but the presence of well compensated cardiovascular disease in the older age group does not significantly alter the magnitude of these measurements. When congestive failure with edema occurs, there is a marked increase in total sodium space and total body sodium. The increase in total sodium space shows a good correlation with the clinical degree of edema.

Sodium Space and Body Sodium Content, Exchangeable with Sodium21, in Normal Individuals and Patients with Ascites

Tlie sodium space and body sodium content, exchangeable with sodium24, were determined in 20 patients with ascites resulting from hepatic cirrhosis. Values were markedly increased over normal and roughly proportional to the degree of ascites estimated clinically. It appears that the expansion of the sodium space in cirrhosis with ascites represents the actual increase of body fluid due to the ascitic volume. No relationship was found between the serum sodium concentration and body sodium content. In the presence of ascites and/or edema, a deficiency of body sodium content cannot be inferred from a lowered sodium concentration in the serum.

Mathematical models for exchange of substances in regional vascular beds— Measurement of the rates within vivo counters

Sangren and Sheppard developed a mathematical model for first-order processes taking place in the regional circulation, applicable—for example—to tracer studies of potassium transport. It permits calculation of specific activity at any point along a “tube of flow” or in the cuff of tissue surrounding it as a function of time following a spike injection of tracer. In efforts to relate to the exchange a rate curves obtained within vivo counters pointed at the region of interest, we developed a compartment-system model of the process. In investigating the properties of the Sangren and Sheppard model integrated over an entire circulatory bed, as thein vivo counter would see it, we found that when the distribution of transit times of the “tubes of flow” can be approximated by an exponential sum, the solution reduces to that of the compartment system model. This results in an important simplification in the calculation, and insight into the assumptions underlying the two different models. A curve-fitting computer program for the compartment model has been written and applied to double-isotope studies of potassium transport in the hind leg of the dog.