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Featured researches published by Yasuo Ontachi.


Critical Care Medicine | 2001

An enhanced fibrinolysis prevents the development of multiple organ failure in disseminated intravascular coagulation in spite of much activation of blood coagulation

Hidesaku Asakura; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Masanori Saito; Ichiro Kumabashiri; Eriko Morishita; Masahide Yamazaki; Keiji Aoshima; Shinji Nakao

Objectives To investigate the relationship between fibrinolytic enhancement and the development of multiple organ failure (MOF) in disseminated intravascular coagulation (DIC). To detect the useful prognostic index for outcome in DIC. Design Case-control study. Setting A department of internal medicine in a university hospital, a clinical division for diagnosis and treatment, mainly of respiratory diseases, hematologic diseases, DIC, and other diseases requiring critical care medicine. Patients A total of 69 DIC patients, 31 with MOF. Interventions None. Measurement and Main Results The DIC patients with MOF had more elevated levels of tissue plasminogen activator antigen (t-PA) and plasminogen activator inhibitor antigen (PAI), and more depressed levels of plasmin-&agr;2 plasmin inhibitor complex (PIC) and fibrin/fibrinogen degradation products than those without MOF, although no significant difference in thrombin-antithrombin complex (TAT) levels was observed. A fibrinolytic enhancement (shown by PIC) was parallel to an activation of blood coagulation (shown by TAT) in DIC patients without MOF, although no such fibrinolytic enhancement was provoked even by much activation of blood coagulation in DIC patients with MOF. Whereas all the patients without MOF were restored from DIC, 14 of 31 patients with MOF were unable to be restored from DIC and died. A significant increase in plasma levels of t-PA and PAI under the condition of sustained hemostatic activation was observed in the patients who died. Conclusion Enhanced fibrinolysis was considered to be the important defense mechanism in preventing the development of MOF in DIC. The increases in plasma levels of t-PA and PAI were poor prognostic markers in DIC. Further careful study may be useful to clarify whether the fibrinolytic therapy is beneficial in clinical DIC patients with MOF.


European Journal of Haematology | 2001

Decreased plasma activity of antithrombin or protein C is not due to consumption coagulopathy in septic patients with disseminated intravascular coagulation

Hidesaku Asakura; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Takako Ito; Masanori Saito; Eriko Morishita; Masahide Yamazaki; Keiji Aoshima; Akiyoshi Takami; Tomotaka Yoshida; Yukio Suga; Ken-ichi Miyamoto; Shinji Nakao

Abstract: We investigated whether depressed plasma antithrombin and protein C activity, considered as a specific finding of disseminated intravascular coagulation (DIC), is due to consumption coagulopathy in septic patients with DIC. An analysis of hemostatic parameters was performed in 139 septic patients (68 with DIC and 71 without DIC). Plasma activity of antithrombin and protein C tended to be significantly decreased in septic patients with DIC but not in those without DIC (pu2003<u20030.001). However, when the septic patients were classified into three groups according to the albumin (or choline esterase) level, no significant differences in antithrombin activity or protein C activity were observed between the patients with and without DIC in any of the subgroups. Notably, neither the plasma activity of antithrombin nor protein C was decreased even in septic patients with DIC who had normal plasma levels of albumin (or choline esterase). No significant correlation was observed between plasma levels of thrombin–antithrombin complex (TAT) and antithrombin activity, or between plasma levels of TAT and protein C activity either in septic patients with DIC or without DIC. It is reasonable to conclude that the markedly reduced plasma activity of antithrombin and protein C is not due to consumption coagulopathy in septic patients with DIC.


Blood Coagulation & Fibrinolysis | 2003

Pathophysiology of disseminated intravascular coagulation (DIC) progresses at a different rate in tissue factor-induced and lipopolysaccharide-induced DIC models in rats

Hidesaku Asakura; Yukio Suga; Tomotaka Yoshida; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Takako Ito; Eriko Morishita; Masahide Yamazaki; Ken-ichi Miyamoto; Shinji Nakao

&NA; Tissue factor (TF) and lipopolysaccharide (LPS) are frequently used to induce disseminated intravascular coagulation (DIC) in experimental animal models. Although the pathophysiology of DIC may differ depending on which agent is used for induction, previous studies on models of DIC have not distinguished which DIC‐inducing agent was used. In the present paper, we evaluate the characteristics of TF‐induced and LPS‐induced DIC using two types of DIC models, with special reference to selected hemostatic parameters and pathological findings within the kidney. Male Wistar rats were administered TF (3.75 U/kg; sustained infusion for 4 h) or LPS (30 mg/kg; sustained infusion for 4 h) via the tail vein, and blood sampling was performed at 0, 1, 3, 4, 5, 7, 9, 11, and 28 h. Judging from changes in the levels of thrombin‐antithrombin complex, fibrinogen levels, and platelet counts, it is reasonable to conclude that the severity of both types of experimental DIC is similar with regard to hemostatic activation and consumption coagulopathy. A marked elevation in the level of D‐dimer was noted without any organ dysfunction or much fibrin deposition in the kidney upon administration of TF. However, a markedly prolonged period of elevation in plasminogen activator inibitor activity, a prolonged depression in antithrombin III activity, severe organ failure, and a markedly prolonged period of fibrin deposition in the kidney was observed following LPS administration. A modest number of the rats from the TF‐induced DIC model died during the experimental period, whereas a large number of rats died during LPS‐induced DIC, especially after 9 h. Since the time course of the pathophysiology differed remarkably among the TF‐induced and LPSinduced DIC models in rats, we recommend that TFinduced and LPS‐induced DIC be approached as distinct models in order to determine the implications of their experimental and clinical use. Blood Coagul Fibrinolysis 14:221‐228


Critical Care Medicine | 2002

Marked difference in pathophysiology between tissue factor- and lipopolysaccharide-induced disseminated intravascular coagulation models in rats

Hidesaku Asakura; Yukio Suga; Keiji Aoshima; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Masanori Saito; Eriko Morishita; Masahide Yamazaki; Akiyoshi Takami; Ken-ichi Miyamoto; Shinji Nakao

Objective Tissue factor and lipopolysaccharide frequently have been used to induce disseminated intravascular coagulation in experimental animal models. Although the pathophysiology of disseminated intravascular coagulation may differ according to the agents used to induce it, these previous models have not distinguished between the use of different disseminated intravascular coagulation-inducing agents. In this study, we attempted to evaluate the characteristic features of these agents in two types of disseminated intravascular coagulation models, with special reference to selected hemostatic parameters and pathologic findings in the kidney. Design Prospective, comparative, experimental study. Setting Laboratory at a university hospital. Subjects Twenty-seven male Wistar rats, age 6–7 wks, weighing 160–170 g. Interventions Three groups of animals were studied: a control group (n = 8) receiving physiologic saline, a tissue factor-treated group (n = 11) receiving tissue factor 3.75 units/kg, and a lipopolysaccharide-treated group (n = 8) receiving lipopolysaccharide 30 mg/kg; each group sustained infusion for 4 hrs via the tail vein. Measurements and Main Results The degree of hemostatic activation in both types of experimental disseminated intravascular coagulation was identical, based on the results of thrombin-antithrombin III complex levels. Markedly elevated D-dimer concentrations were observed without organ dysfunction or fibrin deposition in the kidney on administration of tissue factor, whereas markedly elevated plasminogen activator inhibitor activity, decreased antithrombin III activity, severe organ failure, and marked fibrin deposition in the kidney were observed for lipopolysaccharide administration. Conclusion Because pathophysiology differed remarkably between the tissue factor- and lipopolysaccharide-induced disseminated intravascular coagulation models in rats, we recommend that they be assessed carefully as distinct entities to determine implications of their experimental and clinical use.


Blood Coagulation & Fibrinolysis | 2001

Elevated levels of free tissue factor pathway inhibitor antigen in cases of disseminated intravascular coagulation caused by various underlying diseases.

Hidesaku Asakura; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Masanori Saito; Eriko Morishita; Masahide Yamazaki; Yukio Suga; Akiyoshi Takami; Ken-ichi Miyamoto; Shinji Nakao

Tissue factor pathway inhibitor (TFPI) is primarily synthesized by vascular endothelial cells and is foundin vivoin association with endothelial cells, lipoproteins, or in free form. Free TFPI is the most potent and important type, because it is released from endothelial cells following an injection of heparin, or as a result of pathological stimuli. In order to study the role of TFPI in disease, the concentration of free form TFPI was measured in the plasma of 114 patients suffering from disseminated intravascular coagulation (DIC), as the result of several underlying diseases. Plasma antigen levels of free TFPI were significantly higher even in those patients not exhibiting DIC than in normal healthy subjects. These levels were even higher among patients exhibiting DIC, especially those with acute promyelocytic leukemia or cancer, receiving continuous heparin drip infusions. A significant correlation was observed between the plasma antigen levels of free form TFPI and those of fibrin/fibrinogen degradation products, and free form TFPI and plasmin inhibitor complex (r= 0.428,P< 0.0001 andr= 0.329,P< 0.0001, respectively) among 114 DIC patients. There were no significant differences between the plasma levels of free TFPI in DIC patients with or without multiple organ failure. It has been suggested that the plasma levels of free TFPI are closely related to the levels of fibrinolysis occurring in DIC patients, although further study is required to clarify the degree to which TFPI is expressed by endothelial cells during DIC.


Atherosclerosis | 2001

Elevated plasma levels of free-form of TFPI antigen in hypercholesterolemic patients

Eriko Morishita; Hidesaku Asakura; Masanori Saito; Masahide Yamazaki; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Tamotsu Matsuda; Shinji Nakao

Several studies have previously reported high levels of total tissue factor pathway inhibitor (TFPI) antigen in patients with hypercholesterolemia. The relationship between serum lipid concentrations and total and free-form TFPI antigen in 32 patients with primary type II hypercholesterolemia and 38 age- and gender-matched normolipemic control subjects was studied (Study Group I). Plasma concentrations of total TFPI (tTFPI) antigen, free-form TFPI (fTFPI) antigen, tissue factor antigen, factor VII activity (FVIIc), and prothrombin fragment 1+2 (F1+2) were measured. The median levels of tTFPI, fTFPI, FVIIc, and F1+2 were higher in hyperlipidemic patients compared with those in healthy subjects. The effect of lowering total cholesterol on hypercoagulability in 25 patients with type II hyperlipoproteinemia (Study Group II) were also studied. The median levels of tTFPI, FVIIc, and F1+2 decreased significantly after 6 months of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor therapy in the hypercholesterolemic patients. On the other hand, fTFPI did not change after therapy. Plasma tTFPI was strongly correlated with total cholesterol and low density lipoprotein (LDL)-cholesterol in hyperlipidemic patients. In contrast to the strong correlation between tTFPI and total cholesterol, the correlation between plasma fTFPI and total cholesterol was relatively poor. These results suggest that the activation of the anticoagulant system as well as the activation of the coagulation system may occur in association with hypercholesterolemia. Furthermore, the results of this study may suggest that lowering of total cholesterol in hyperlipidemic patients reduces the thrombin generation in plasma and that down-regulation of LDL does not affect the anticoagulant potency of TFPI in plasma.


Journal of Thrombosis and Haemostasis | 2005

Selective inducible nitric oxide synthase inhibition attenuates organ dysfunction and elevated endothelin levels in LPS-induced DIC model rats

Hidesaku Asakura; Risa Asamura; Yasuo Ontachi; Tomoe Hayashi; Masahide Yamazaki; Eriko Morishita; Ken-ichi Miyamoto; Shinji Nakao

Summary.u2002 We examined the role of nitric oxide (NO) produced by an inducible isoform of NO synthase (iNOS) using N[6]‐(iminoethyl)‐lysine (L‐NIL), a selective iNOS inhibitor, in the rat model of lipopolysaccharide (LPS)‐induced disseminated intravascular coagulation (DIC) and investigated changes in organ function, plasma levels of NOX (metabolites of NO) and endothelin. We induced experimental DIC by the sustained infusion of 30u2003mgu2003kg−1 LPS for 4u2003h via the tail vein. We then investigated the effect of L‐NIL (6u2003mgu2003kg−1, from −u200a0.5 to 4u2003h) on LPS‐induced DIC. Blood was withdrawn at 4 and 8u2003h, and all four groups (LPS with or without L‐NIL at 4 and 8u2003h) consisted of eight rats. Three of the animals in the 8‐h LPS group died, and we examined blood samples from five rats in this group. None of the other rats died. The LPS‐induced elevation of creatinine, alanine aminotransferase, glomerular fibrin deposition and plasminogen activator inhibitor was significantly suppressed by L‐NIL coadministration, although L‐NIL did not affect the platelet count, fibrinogen concentration or the level of thrombin–antithrombin complex. Moreover, plasma levels of the D‐dimer that reflect the lysis of cross‐linked fibrin were significantly increased by L‐NIL coadministration in the LPS‐induced DIC model. Plasma levels of NOX and endothelin were obviously increased by LPS infusion. However, both levels were significantly suppressed in the LPSu2003+u2003L‐NIL group, when compared with the LPS group. Although mean arterial pressure (MAP) was significantly decreased between 2 and 8u2003h compared with the control in the LPS group, this depression was significantly attenuated in the LPSu2003+u2003L‐NIL group. Our results suggest that NO induced by iNOS contributes to hypotension (depressed MAP), the progression of hepatic and renal dysfunction, microthrombus deposition and elevated endothelin levels in the rat model of LPS‐induced DIC.


Blood Coagulation & Fibrinolysis | 1999

Prednisolone inhibits endotoxin-induced disseminated intravascular coagulation and improves mortality in rats : importance of inflammatory cytokine suppression

Masahide Yamazaki; Keiji Aoshima; Tomoe Mizutani; Yasuo Ontachi; Masanori Saito; Eriko Morishita; Hidesaku Asakura; Tamotsu Matsuda; Triplett Da

In order to determine whether prednisolone has a protective effect against the development of disseminated intravascular coagulation (DIC), we measured the effect of prednisolone on changes in hemostatic parameters and plasma levels of inflammatory cytokines in endotoxin-treated rats. Decreases in platelet count and fibrinogen levels, prolongation of prothrombin time, and increases in the plasma fibrin degradation products and levels of thrombin-antithrombin III (TAT) complex following the administration of endotoxin, all of which are associated with DIC, were significantly suppressed by the administration of prednisolone. Heparin administration significantly suppressed changes in all these parameters except for the decrease in platelet count. The combination of prednisolone and heparin was more effective than either treatment alone. In order to determine whether these effects of prednisolone are correlated with the suppression of inflammatory cytokine production, we examined the relationship between changes in plasma levels of cytokine, the hemostatic parameters listed above, and mortality using a number of intervention regimens designed to alter events of the experimentally induced DIC. Changes in hemostatic parameters associated with DIC following 30 mg/kg per 4 h of endotoxin infusion were significantly suppressed by treatment with 1 mg/kg prednisolone 30 min before beginning endotoxin infusion, followed by administration of 250 U/kg heparin 2 h after the start of endotoxin infusion (prednisolone-endotoxin-heparin regimen). The heparin and prednisolone were administrated subcutaneously. The administration of prednisolone and heparin in the reverse order (i.e. heparin first and prednisolone second: heparin-endotoxin-prednisolone regimen) also suppressed changes in hemostatic parameters, albeit to a smaller degree. Cytokine production was also significantly suppressed by the first treatment, but was not affected by the regimen in which heparin was administered first. Administration of prednisolone alone or heparin alone 30 min before endotoxin significantly reduced the number of renal glomeruli with fibrin thrombi. Plasma levels of creatinine and alanine transferase were reduced only by prednisolone. Increased plasma levels of interleukin-1beta, tissue necrosis factor-alpha and interleukin-6 were suppressed by prednisolone but not by heparin, and there were significant correlations between plasma levels of TAT and cytokines. Prednisolone was more effective than heparin in reducing mortality at 24 h after 100 mg/kg over 4 h of endotoxin infusion (four of 20 versus 15 of 20 deaths for prednisolone and heparin, respectively). These findings suggest that prednisolone inhibits the development of endotoxin-induced DIC and reduces mortality by a different mechanism than heparin, possibly through suppressing the production of inflammatory cytokines. Prednisolone may be efficacious in preventing DIC and multiple organ dysfunction caused by endotoxin.


International Journal of Hematology | 2007

Living-Donor Lobar Lung Transplantation for Broncho-Bronchiolitis Obliterans after Allogeneic Hematopoietic Stem Cell Transplantation: Does Bronchiolitis Obliterans Recur in Transplanted Lungs?

Hirokazu Okumura; Shigeki Ohtake; Yasuo Ontachi; Jun Ozaki; Shigeru Shimadoi; Yuko Waseda; Yukio Kondo; Hirohito Yamazaki; Akiyoshi Takami; Masahide Yasui; Hiroshi Date; Shinji Nakao

We report a successful case of living-donor lobar lung transplantation (LDLLT) for therapy-resistant broncho-bronchiolitis obliterans (BBO) after allogeneic hematopoietic stem cell transplantation (HSCT). Bronchiolitis obliterans (BO) is one of the late-onset noninfectious pulmonary complications that occur after allogeneic HSCT and is usually resistant to immunosup-pressive therapy. A 17-year-old girl with acute lymphoblastic leukemia (ALL) had undergone allogeneic bone marrow transplantation (BMT) from an HLA-matched sibling in 1997. Five years later, she relapsed with ALL and was treated with chemotherapy following stem cell rescue and donor lymphocyte infusion from the original BMT donor. Eight months later, BBO resistant to immunosuppressive therapies, including rituximab, developed in combination with chronic graft-versus-host disease (GVHD). In February 2004, the patient underwent LDLLT from 2 other family members who were mismatched at 3 HLA loci. The patient has been in good health for more than 30 months following LDLLT and shows no sign of BBO in the transplanted lungs, just as with other patients who have undergone lung transplantation for BO associated with chronic GVHD. LDLLT may therefore be considered a viable therapeutic option for the treatment of BO after allogeneic HSCT.


Osteoporosis International | 2001

Vitamin K Administration to Elderly Patients with Osteoporosis Induces No Hemostatic Activation, Even in Those with Suspected Vitamin K Deficiency

Hidesaku Asakura; S. Myou; Yasuo Ontachi; Tomoe Mizutani; Minori Kato; Masanori Saito; Eriko Morishita; Masahide Yamazaki; Shinji Nakao

Abstract: The administration of menaquinone-4 (MK-4), one of subclasses of vitamin K2, significantly reduces bone loss in postmenopausal osteoporotic women. However, concerns have been raised about whether vitamin K administration alters the hemostatic balance by inducing a thrombotic tendency. We investigated here whether the administration of vitamin K in the form of MK-4 induced a thrombotic tendency in 29 elderly patients with osteoporosis (5 men, 24 women; age range 78.7±5.1 years). Patients were administered 45 mg/day (three times a day, 30 min after each meal) of MK-4 for 12 weeks. Blood samples were obtained from the patients at 0, 4 and 12 weeks after the start of MK-4 administration. A number of hemostatic parameters remained stable under the markedly increased plasma levels of MK-4. However, in patients with suspected vitamin K deficiency, whose plasma levels of vitamin K or factor VII were low, vitamin-K-dependent clotting factors such as factor VII and prothrombin were gradually increased after administration of MK-4. No changes in the sensitive molecular markers such as TAT and F1+2, which reflect the amount of thrombin generated in the blood stream, were observed, even in those patients with suspected vitamin K deficiency. These results indicate that MK-4 can be administered safely, with regard to maintaining the hemostatic balance, to osteoporotic patients receiving no anticoagulant therapy.

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