Parabiotic demonstration of a substance released from burned tissue affecting marrow megakaryocyte diameter and number in mice.

Four groups of C3H mice were studied to determine effects of substances released into blood from burned tissue on platelet counts and megakaryocyte numbers and sizes. Burns were full thickness scald injuries over 20% of body. Groups were: 1) Single, non-burned (controls); 2) Single, burned; 3) Parabiosed non-burned; 4) Parabiosed, one burned in each pair. Platelet counts and megakaryocyte counts and sizing were done at sacrifice. On 2nd postburn day platelet counts of group 4 were significantly lower (P less than 0.0005) than in group 1, but higher than in group 2. On day 5 platelet counts of group 4, returned to normal, then rose above normal. Two to five days postburn, megakaryocyte diameters were significantly larger in groups 2 and 4. Fifty megakaryocytes from each mouse of treatment groups were measured. A blood-borne substance(s) derived from burned tissue appears responsible for waning and waxing of megakaryocyte activity.

Direct effects of endotoxin on the microcirculation.

Endotoxin (E Coli, Difco), 0.5 mg in 10 ml saline, or whole blood, was infused over a ten-minute period in the retrograde direction into a branch of a mesenteric artery in anesthetized dogs; control infusions were physiologic saline or whole blood without endotoxin. After infusion, the animal's blood was allowed to circulate through the microcirculatory field. Changes in the microcirculation were recorded by cine and still photography. After infusion of endotoxin there was coincident margination of leukocytes and thickening of endothelial cells, then formation of fibrin thrombi in small veins, followed by lyses of the thrombi and extravasation of erythrocytes. Systemic blood pressure did not fall until after endothelial cell thickening and leukocyte margination (five to 25 minutes after infusion). The mean pressure fell to between 30 and 50 mm Hg, even though the dose of endotoxin was less than 1/100 of that required to cause this blood pressure fall when given IV. It is hypothesized that intracellular hydration of endothelial cells causes increased leakage of fluids and extravasation of erythrocytes following endotoxin. If the internal volumes of hexahedron-shaped cells increase without an increase in their surface areas they must assume a more spherical shape, thereby permitting gaps to develop between adjacent cells.

Purification and properties of an antiactivator fraction from bovine serum.

A method is described for the purification of antiactivator from bovine euglobulin-free serum by means of gelfiltration and ion exchange chromatography. The purified antiactivator has no antifibrinolytic activity. It has a molecular weight of about 115,000 and it appears to be a gamma globulin. The dissociation constant of its complex with urokinase is 1.6 x 10(-9) M and the maximum urokinase binding is close to 2000 CTA units per mg. Its concentration in bovine serum is 0.37%. Flufenamate displaces urokinase from the antiactivator at very low concentrations, about 10(-4) M. Cysteine restores its activity if lost by standing. Also an antifibrinolysin fraction is obtained free of antiactivator activity.

Tissue gas and blood analyses of human subjects breathing 80% argon and 20% oxygen.

Eight human volunteers, individually studied in a hyperbaric chamber, breathed: 1) air at 1 ATA; 2) 80% argon and 20% oxygen and 1 ATA for 30 min; 3) air at 1 ATA for 30 min; 4) 100% 02 at 1 ATA for 30 min; 5) air at 1 ATA for 30 min; 6) 100% O2 at 2 ATA for 60 min; and 7) 80% argon and 20% oxygen at 1 ATA for 30 min. Oxygen, carbon dioxide, nitrogen, and argon tensions were measured in muscle and subcutaneous tissue by mass spectroscopic analyses. Venous blood obtained at regular intervals was analyzed for coagulation and fibrinolytic factors. Inert gas narcosis was not observed. After breathing argon for 30 min, muscle argon tensions were almost three times subcutaneous tensions. Argon wash-in mirrored nitrogen wash-out. Argon wash-in and wash-out had no effect on tissue Po2 or Pco2. Coagulation and fibrinolytic changes usually associated with vascular bubbles were absent.

Characterization of the terminal degradation products of canine fibrinogen by plasmin.

Fibrinogen, isolated from canine plasma by the successive procedures of (1) freezing and thawing, (2) fractional precipitation with 25% saturated (HN4)2SO4 and (3) Sepharose 6B gel-filtration, had a molecular weight of 282 000 by the rapid sedimentation equilibrium method. However, a molecular weight for canine fibrinogen of 332 000, which is closer to that reported for human and bovine fibrinogens (340 000 plus or minus 20 000), was obtained from the sum of the molecular weights of the Aalpha, Bbeta and gamma chains, determined from dodecylsulfate gel electrophoretic patterns of reduced fibrinogen. Canine fibrinogen, subjected to proteolysis by urokinase-activated plasminogen for 24 h, contained degradation fragments D and E which were isolated by starch block electrophoresis and Sephadex G-200 gel-filtration. The purified D and E fragments with sedimentation coefficients of 5.0 S and 2.5 S had weight average molecular weights of 89 000 and 42 000, respectively by the rapid sedimentation equilibrium method. The ratio of D to E was 2:1 per parent fibrinogen molecule. Antigenic analysis according to anti-fibrinogen antiserum showed that both D and E fragments were antigenically deficient to native fibrinogen and revealed a reaction of non-identity with each other. Upon immunoelectrophoresis at pH 8.2, D and E had different electrophoretic mobilities. Preliminary studies indicate that based on thrombin time alone, D has anticoagulant activity while E appears to be a coagulation potentiator. Canine fibrinogen apparently consist of two core fragments with dissimilar chemical characteristics in common with the fundamental structures of human and bovine fibrinogens.