Funahara Y

Intravenous injection of sonicated blood induces pulmonary microthromboembolism in rabbits with ligation of the splenic artery.

Pulmonary thromboembolism (PTE) is found in long hospitalized patients. Chronic PTE has been reported to play an important role in cardiac failure in thalassemic patients after splenectomy. However, the mechanism of PTE in these patients remains unclear. In this study, we attempted to establish an animal model of PTE. We divided New Zealand white rabbits into three groups: Group I was injected sonicated blood, II was injected non-sonicated blood after ligation of the splenic artery, and III was injected sonicated blood after ligation of the splenic artery. After injection of the sonicated blood, we examined the platelet counts every 10 minutes until 1 hour and the rabbits were sacrificed for histological examination. Platelets significantly decreased in number immediately after the injection of sonicated blood in Groups I and III. Many pulmonary thromboemboli composed mainly of platelets were found in Group III but not in other groups. These pathological changes seem to be partly similar to those of thalassemic patients after splenectomy. This animal model is thought to be useful to study the pathogenesis of pulmonary thromboembolism, especially in thalassemic patients after splenectomy.

Enhancement of collagen-induced aggregation of platelets in whole blood

In order to elucidate the features of platelet aggregation in whole blood, studies were carried out on human blood. The platelet aggregation reaction was monitored by counting the residual free platelet number with an electronic particle counter (Coulter). Platelets in citrated whole blood were aggregated by a very small amount of collagen which did not aggregate platelets in citrated plasma. Such enhancement was not observed if ADP or epinephrine was used. By addition of isolated erythrocytes to platelet rich plasma, enhancement of the platelet response to collagen was obtained. The erythrocyte membrane stabilizer, Dilazep, abolished the enhancement effect of erythrocytes. Those results indicated that erythrocytes enhanced the platelet response to collagen. Although participation of ADP from the erythrocytes in the enhancement was suggested, the results of ADP determinations on suspensions of erythrocytes indicated that other factors of the erythrocytes might be involved in the enhancement.

Detection of PF3 availability in whole blood from volunteers and beta-thalassemia/HbE patients: a promising method for prediction of thrombotic tendency.

The platelet factor 3 (PF 3) plays a very important role in activation of coagulation factors and is regarded to be available during activation of platelets. However, membrane fraction of erythrocytes is also shown to have PF 3-like activity, suggesting that the abnormal erythrocytes may accelerate the activation of platelet by forming thrombin on their abnormal membrane or by way of other factors of the abnormal erythrocytes, and may increase the availability of PF 3 in whole blood (WB). To examine this hypothesis, we developed a method for determination of PF 3 activity, because the method now available for the PF3 determination could not detect changes in PF 3 activity with time. The principles of our method were as follows: 1) The reaction system was adjusted so that the amount of thrombin generated in a fixed reaction time correlates with the amount of PF 3. 2) To avoid inhibition of thrombin activity by antithrombin III, a synthetic thrombin inhibitor, MD 805, was added to the system and the activity of thrombin generated was measured by synthetic thrombin substrate S-2238 using A405 as an indicator of the availability of PF3. The results obtained by the method were the following: WB taken from volunteers showed A405 of 0.12 +/- 0.02 at 30 minutes after blood collection and then the A405 increased to 0.27 +/- 0.03 at 90 minutes. However, one volunteer showed the value of 0.59 at 90 minutes, though the value at 30 minutes was 0.16. The platelet number in his WB did not change during the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostacyclin release from the coronary vascular wall by vasoactive substances.

Which vasoactive substances that are synthesized in vivo could induce the release of a sufficient amount of prostacyclin (PGI2) to inhibit platelet aggregation from the vascular wall was investigated in the isolated dog heart perfused by a modified method of Langendorff. Infusion of 5 microM bradykinin or 25 u/ml crude thrombin into the heart for 30 sec resulted in the transient appearance of inhibitory activity of platelet aggregation. The inhibitory activity was stable at alkaline pH but unstable at acidic pH and thermolabile. The appearance of the inhibitory activity was prevented by treatment of the coronary vessel with 30 microM indomethacin or 1 mM tranylcypromine. These results indicated that the inhibitory activity was caused by PGI2. When 25 microM acetylcholine, 25 microM noradrenaline, 25 microM isoproterenol, 10 microM adenosine triphosphate (ATP), 5 microM adenosine, 1 microM angiotensin II, 25 microM histamine or 1 microM serotonin was infused for 30 sec, no inhibitory activity of platelet aggregation was observed. Bradykinin (5 X 10(-9) approximately 5 X 10(-6) M) and purified thrombin (1 X 10(-9) approximately 1 X 10(-7) M) induced a dose-dependent release of PGI2 which was assayed using a radioimmunoassay for 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha).

EFFECT OF VASOACTIVE AGENTS ON FACTOR VIII RELEASE FROM PERFUSED ISOLATED DOG LEG

Abstract The present study was carried out to determine whether factor VIII with procoagulant activity was released by vasoactive agents from blood vessels of dog hind leg perfused with artificial physiological solution. F. VIII procoagulant activity was measured by the one-stage method using F. VIII deficient plasma. When bradykinin, acetylcholine, isoproterenol or salbutamol was administered via the perfused femoral artery, a transient but steep rise in F. VIII procoagulant activity was clearly observed in the venous perfusate. On the other hand, when adrenaline or noradrenaline was administered, a characteristic long-lasting release of F. VIII was observed. The effects of angiotensin II and vasopressin were found to be far weaker than those of the other vasoactive agents. The above results indicate that F. VIII with procoagulant activity may be released from the blood vessels by vasoactive agents. Furthermore, two different patterns of F. VIII release were demonstrated, viz. the transient release induced by bradykinin, acetylcholine, isoproterenol or salbutamol, and the long-lasting release induced by adrenaline or noradrenaline.

Plasminogen activator activity of cultured endothelial cells derived from canine coronary vessel and human umbilical artery and vein

The present study was undertaken to determine which cells participate in plasminogen activator (PA) release from the vascular wall. Canine coronary vessel was confirmed to release PA when various agents were administered in perfusion experiments. Endothelial cells from the coronary vessel were then isolated and cultured for 2 days. PA activity was observed in lysates of the cultured cells, and the medium used for the cultivation was found to contain little PA activity. This suggests that the endothelial cells participate in PA release from the vascular wall. In addition, the PA synthesis was also studied in cultured endothelial cells from human umbilical artery and vein. Both contained little PA activity, indicating that vascular endothelial cells may vary in PA synthesis and release according to the vessel.

Obesity among school children in a province of southern Thailand and its association with socioeconomic status

The association of nutrition status of children aged 7–12 years (n=663) with socioeconomic factors in a province of southern Thailand in 1995 was investigated. Three type of schools were surveyed: a school with a higher educational standard (elite school) in the municipality of the province, a school with many children from low-income families (low-income school) in the same municipality, and five ordinary schools in rural areas of the province (district schools). The proportions of obese children were 22.1%, 5.8% and 2.7%, respectively for the three type of schools, when obesity was defined as weight to height of over 120% of the median of children in Bangkok. The risk ratios and 95% confidence intervals for obesity in the elite and the low-income schools were 5.0 (3.5–7.2) and 1.9 (0.8–4.8), respectively, taking the district schools as a reference. Our research suggested that the high prevalence of obesity among elite-school children could be related to the comparatively high socioeconomic status of the children’s families. It also shows that the children in the province studied were as a whole considerably leaner than children in the big cities of Thailand. These results imply a need for appropriate interventions which cannot only prevent obesity, but also improve the malnutrition of school children in the rural provinces of southern Thailand.

An evaluation of prothrombin assay method using MD805 by means of warfarin-treated plasma

The prothrombin assay method using the synthetic thrombin-inhibitor MD805 was standardized by fixing the concentrations of MD805 and S-2238 through their extinction coefficients (epsilon 333 for MD805 and epsilon 316 for S-2238). The prothrombin assay was directly proportional to the concentration of plasma up to 200% of the normal level and was not significantly influenced by the variety of three kinds of commercially available tissue thromboplastin preparations. Using plasma from Warfarin-treated patients and healthy volunteers, the correlation was studied between the prothrombin assay and the conventional coagulation tests such as Prothrombin time (INR), Thrombotest and Hepaplastintest (Normotest), and the correlation coefficients of -0.85, 0.81 and 0.94 were obtained respectively. FUT-175 and MD805 in the test plasma hardly affected the prothrombin assay in the concentration ranges which affected remarkably the conventional coagulation tests. These results indicated that the prothrombin assay was useful for monitoring the hyper- or hypoprothrombin state even on anticoagulant therapy. Eighteen healthy volunteers at 18 to 20 years old showed the mean and standard deviation of 0.96 +/- 0.097.