Hisashi Mihara

Threshold phenomena in blood fibrinolysis

Abstract Measurements were made of the appearance time of fibrinolytic activity in plasma during urokinase (UK) infusion at various speeds to the rabbits. There was no observable fibrinolytic activity at a low infusion speed, but fibrinolytic activity did appear when the infusion speed was high. The results obtained indicated that threshold phenomena governed the appearance of fibrinolytic activity in the plasma, with a critical UK infusion speed of about 2,500 units/min. For infusions below this speed, even the administration of 300,000 units of UK failed to induce observable fibrinolytic activity in the plasma, reflecting the dynamic participation of the inhibition system of blood fibrinolysis under these conditions.

Arthus Tonsillitis in the Rabbit: Histological Findings and Fibrinolytic Activity in the Blood

Arthus-type hypersensitivity was induced experimentally in the tonsils of rabbits. Histopathological studies were performed on the Arthus tonsillitis so produced, and estimations of the plasma fibrinolytic activity were made on the blood of these rabbits. The findings obtained by macroscopic inspection of the tonsil revealed significant bleeding and swelling. Furthermore, the histopathological studies demonstrated bleed and infiltration of leukocytes into various parts of the parenchyma and connective tissue surrounding the tonsil during the early stages of tonsillitis. From the results concerning certain parameters of the fibrinolytic system in the blood, it was demonstrated that, during the early stage of tonsillitis, the fibrinolytic activity increased and whole plasmin was consumed. Based on the above findings, it seems that the change in fibrinolytic activity found in rabbits affected by Arthus tonsillitis closely resembles that in patients suffering from acute tonsillitis.

A protease-antiprotease system in antrochoanal polyp

SummaryTissue extract of antrochoanal polyps showed a faint lysis area on standard fibrin plates, but streptokinase (SK)-added tissue extract showed a large lysis area. No fibrinolytic activity was observed on plasminogen-free fibrin plates. It is concluded, therefore, that the fibrinolytic activity observed after SK addition is indicative of the existence of SK-responsive protein proactivator. The tissue extract did not contain plasminogen or antiprotease against trypsin or papain. It was stable at neutral pH at 37° C and stable at acid pH at 70° C. The role of proactivator is discussed in relation to the growth or enlargement of antrochoanal polyps.

Kinetic studies of urokinase metabolism

Abstract A two-compartment model is applied to the metabolism of urokinase (UK). In the first compartment, into which the administered UK flows, the inhibition system against fibrinolytic activity is dominant. If sufficient UK is administered, UK overflows into the second compartment, where it can show activity. The inactivation activity of UK in the first compartment (inactivation rate constant of UK activity, kel) calculated during UK infusion showed a high value before the appearance of fibrinolytic activity in the plasma, and a low value during the plateau stage. The inactivation rate constant of UK activity in the second compartment (ke2) was rather small. These changes in ke would lend support to a mode of UK administration that employs both one-shot and infusion administrations concomitantly.

Determination of α2-plasmin inhibitor in body fluids

Abstract A sensitive method was developed to determine α2PI at very low concentrations. The minimal measurable concentration of α2PI was 0.5 ng/assay tube. Using this method, the α2PI in plasma, urine, amniotic fluid and cerebrospinal fluid was estimated. The mean values and standard deviation for plasma were 5.63 + 1.34 mg/dl in 25 males, and 5.29 ± 1.62 mg/dl in 8 females; in the urine, 0.46 + 0.41 μg/dl in 82 male samples, and 0.69 ± 0.27 μg/dl in 8 female samples; in amniotic fluid, 4.13 ± 2.38 μg/dl in 16 samples; and in cerebrospinal fluid, 24.4 ± 6.6 μg/dl in 9 samples. The α2PI level in amniotic fluid was not correlated with the state of the pregnant mother, with that of the baby, or with the protein content or pH of the amniotic fluid.