Tadahiro Sano

Hyperaggregability of platelets in thromboembolic disorders

Platelet aggregability was measured using platelet rich plasma (PRP) collected from 197 clinical cases including 52 healthy volunteers. In 31 patients of acute stage of thrombosis (within 2 weeks from the onset), a significant enhancement of platelet aggregation measured 5 min after an addition of 3 and 10 muM ADP or 0.1 and 1 mug/ml of adrenaline to PRP (p less than 0.05, compared to the healthy group). Also a significant enhancement of secondary aggregation induced by adrenaline was observed (p less than 0.05). The enhancement was especially marked in the response induced by adrenaline. Such an enhancement was not observed in patients in the recovery stage of thrombosis, hypertension, angina pectoris and other miscellaneous diseases. There was no difference in the parameters related to the velocity of aggregation or intensity of primary aggregation between the diseased and the healthy group. In response induced by collagen (bovine achilles tendon, 0.3 and 1 mg/ml) any difference in the aggregation curve was not observed between the diseased and the healthy group. Such findings suggest a presence of an enhancement of ADP-release mechanism of platelets in acute thrombosis. Aslo a significance of adrenaline-induced platelet aggregation was proposed to detect platelet functions for analysis of mechanism of thromboembolic disorders.

Electrocardiographic and hematological changes by exercise test in coronary patients and pyridinolcarbamate pretreatment. A double-blind crossover trial.

Abstract Forty hospitalized patients with angina pectoris, 25 men and 15 women, 37 to 75 years of age, were subjected to Masters two-step test. Three hours before the test, 1.0 Gm. of pyridinolcarbamate or placebo was given orally using a double-blind technique. Before, immediately after, and 3, 5, 7, 10, and 30 minutes after exercise, electrocardiographic changes and clinical symptoms were observed. In 20 of the above subjects prothrombin activity, calcium clotting time, and the platelet and adhesive platelet count was measured. Thirty-three of the 40 patients pretreated with placebo developed ischemic ECG findings immediately to 10 minutes after the exercise test. Seventeen of the same 40 subjects pretreated with pyridinolcarbamate developed ischemic ECG findings. The difference between placebo and pyridinolcarbamate was statistically significant at p For the second exercise test the 17 patients who had received pyridinolcarbamate for the first test were pretreated with placebo, and 13 showed positive ischemic ECG changes. The 23 patients who had received placebo for the first exercise test were pretreated for the second test with pyridinolcarbamate, and 10 developed positive ECG changes. There was no significant difference noted between the two exercise tests in regard to the appearance of ischemic ECG changes. The appearance of anginal pain after exercise was prevented by pretreatment with pyridinolcarbamate (p In comparison to other 39 healthy volunteers, the patients with angina pectoris showed enhanced blood coagulability and lower platelet count. In healthy persons, enhanced blood coagulability was observed one minute after the exercise test (p p

Influence of lipids metabolism on platelet activation in vivo

Platelet aggregability and plasma factor VIII-related antigen (F. VIIIR:AG) level in 16 ischemic heart disease (IHD) patients were increased by isometric exercise and these changes were prevented by administration of a lipid lowering agent, simfibrate, a derivative of clofibrate. Serum total cholesterol (TC) level decreased and the high density lipoprotein-cholesterol (HDL-C)/TC ratio increased with the treatment. Another 7 hyperlipidemics were administered with simfibrate. Platelet malondialdehyde (MDA) production decreased with improvement in lipid profile. In an in vitro study, platelet aggregability and the plasma level of von Willebrand factor (vWF) and F.VIIIR:AG of normal citrated blood were increased by passing it through a glass bead column. Combining above results of the three separate studies, it would be suggested that hyperlipidemia might enhance platelet activation in vivo, which occurred through contact of platelets to atherosclerotic rough vessel surface. The anti-platelet effect of simfibrate might be mediated through its effect on arachidonic pathway in platelets.

Isolation and chemical analyses of platelet-clumping substance in blood

Abstract A platelet-clumping substance was separated from 3,000 ml of rabbit acidified plasma using DEAE-Sephadex column chromatography. Active fraction was eluted accompanying each peak of protein and uronic acid respectively. After rechromatography, white water-soluble powder was obtained. Its yield was 231 mg, thus 77 μ of the clumping substance was obtained from one ml of plasma. It showed the clumping activity against washed or unwashed platelets equally, even in a concentration of 20 μg/ml without calcium ions. The chemical analysis showed 94.5 % protein, 0.6 % uronic acid, 2.4 % hexose and 2.5 % hexosamine. The substance showed metachromatic staining with toluidine blue. The clumping activity was lost after incubation with trypsin and pronase. Saccharose density gradient ultracentrifugation analysis showed that its molecular weight was between 13,000 to 68,000. Using immuno-electrophoresis, a characteristic precipitation line against prealbumin fraction was shown.

Effect of isometric handgrip on systolic time intervals in patients with ischemic heart disease and cyclic amp phosphodiesterase inhibitor pretreatment.

The effect of cAMP phosphodiesterase inhibitor EG626 on the left ventricular function was studied in 23 patients with ischemic heart disease at rest and during the IHG test. Administration of a single dose of the substance produced changes in STIs indicating an increase in cardiac output and a possible enhancement of myocardial contractility during the IHG test. EG626 may have a beneficial effect on impaired left ventricular function in patients with ischemic heart disease.

Platelet aggregation by platelet-clumping substance

Abstract The platelet-clumping substance isolated from rabbit plasma by the authors aggregated washed rabbit platelets, while ADP did not. The presence of AMP or adenosine did not inhibit the appearance of platelet aggregation induced by the clumping substance. Pretreatment of phosphoenol-pyruvate and pyruvate kinase on unwashed platelets did not affect the platelet aggregation by the clumping substance. It clumped human platelets and also shrimp thrombocytes. Electron microscopic findings showed that platelets to which the clumping substance was added aggregated in their original form as falt disc shapes with few pseudopods. While fusion of membrane was present, microtubules were observed in its regular form. These results showed the existence of a platelet-clumping substance in blood that is different from ADP, collagen, thrombin, adrenaline etc. and may play an important role in hemostasis and thrombogenesis.

A New Antiatherosclerotic Agent, EG467. Preliminary Report on its Experimental and Clinical Trial

EG467 is a nontoxic compound synthesized by the author with the cooperation of Prof. Ishikawa and his collaborators. The LD50 in rats and rabbits is over 5,000 mg/kg by oral administration and it is 3,500 mg/kg and over 2,500 mg/kg respectively by intraperitoneal administration. Long-term treatment of dogs and rats with 40 mg/kg and 200 mg/kg of EG467 for 10 months showed no recognizable toxicity, and the histological and electron microscopic analysis of all organs of these animals showed almost no change. No teratogenic nor carcinogenic effects have been observed during long-term treatment of rabbits with this compound. The solubility of this compound is relatively poor, but it is well absorbed by oral administration and an effect was easily obtained by oral administration.