Richard I. Walker

Distribution and Clearance of Circulating Endotoxin.

To elucidate the mechanisms of endotoxin action the distribution and clearance of injected endotoxin were studied in New Zealand white rabbits; some animals were rendered tolerant through successive (5 days) doses of endotoxin (E. coli lipopolysaccharide) and the remainder were nontolerant. Blood and plasma clearance of small doses of chromium-labeled endotoxin was more rapid in tolerant than in nontolerant rabbits. In both groups clearance was nearly complete within 10 minutes after injection. Circulating endotoxin was distributed between plasma and platelets in both non- and tolerant animals. A minimal amount of endotoxin was found in leukocytes by this was believed the result of contaminating platelets.

The Procoagulant Activity of Granulocytes

Summary Rabbit granulocytes and human-blood leukocytes (mostly granulocytes) shortened the recalcification time of normal rabbit and human plasmas and human plasmas deficient in Factors VIII, IX, XI and XII but not those deficient in Factors VII and X. While these cells shortened the recalcification time of Factor V deficient plasma they failed to shorten the prothrombin time. Neither did granulocytes shorten the prothrombin time of plasmas deficient in Factors VII and X. Rabbit granulocyte lysosomes resembled the intact parent cells in their effect on normal and deficient plasmas. Rabbit lymphocytes had no detectable procoagulant activity. The minimal procoagulant activity observed with the human lymphocyte suspension may have resulted in part from contaminating granulocytes.

Effect of lysosomal cationic proteins from polymorphonuclear leukocytes upon the fibrinogen and fibrinolysis system

Heterogeneous lysosomal cationic proteins from PMN leukocytes contain substances exhibiting in vitro (1) Anticoagulant activity; (2) Fibrinogen precipitating activity; (3) Fibrin polymerizing-precipitating activity; (4) Plasminogen activator activity; and (5) Direct fibrinogenolytic and fibrinolytic activity. The anticoagulant activity is not blocked by serum or SBTI. The plasminogen activator, stable at acid pH, is blocked by EACA. An acid-labile direct fibrinogenolytic and fibrinolytic activity, stable at neutral pH, is incompletely blocked by the plasmin inhibitor, SBTI.

The study of granulocyte kinetics by mathematical analysis of DNA labelling

SummaryA commonly used experimental procedure for the study of granulocyte kinetics involves the labelling and subsequent tracing of granulocyte DNA. Following the introduction of a label into the system, observations are made periodically on the concentration of label in the DNA of granulocytes taken from the circulating blood. A mathematical model for the expected value of this concentration (expressed as a function of time following label introduction) has been derived, studied, and related to experimental observations from studies using P32 as a label. Insofar as the derivation of the model accurately incorporates the relevant aspects of granulocyte kinetics, the model will be useful in the interpretation of the experimental observations in terms of these kinetics.Among other things, study of the model indicates that the assumption of “flash” labelling made with respect to some labels is quite crucial and needs to be examined critically. It has also been necessary to make adjustments to allow for the observed emergence of labelled cells from the marrow soon after label introduction. In addition, despite a high degree of confounding of parameter effects it has been possible to suggest bounds on some of the parameters of the model for some species. The bounds will be refined as the model is improved and more data become available. Study and development of the model continues with particular interest in generalizations to include the diseased state chronic granulocytic leukemia.

A method for the study of the incorporation of inorganic radiophosphorus into leukocyte deoxyribonucleic acid

Abstract A modification of the Schmidt-Thannhauser procedure for isolating DNA coupled with a new method for DNA digestion and an adaptation of the Berenblum and Chain method for phosphorus determination have been shown to be suitable for use in studying the incorporation of inorganic P 32 into leukocyte DNA. With these techniques tracer doses as small as 2 μc/kg are permitted. Peak tagging of rabbit leukocytes was found to occur on the fourth day following injection. Disappearance of the label through the tenth day was virtually exponential.

Effect of Phosphate Loading on Leukocyte Labelling with Inorganic P32.

Summary The effect of an intravenous load of non-isotopic inorganic phosphate following P32 on plasma clearance and on leukocyte labelling has been studied. Such a load produces immediate dilution of plasma phosphate activity, decreases rate of clearance of plasma radioactivity during the period of loading, diminishes the level of labelling of circulating leukocyte acid soluble and DNA phosphorus, and prevents development of a peak in DNA-P specific activity. The findings suggest that marrow labelling during the first 2 hours after P32 injection is responsible for development of the peak in DNA-P specific activity found in peripheral blood leukocytes.