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H Fukao

Publications and source records attributed to H Fukao.

At least 37 records · Page 2Linked to original sources
PubMed1995

In vivo setting behaviour of fast-setting calcium phosphate cement.

The in vivo setting behaviour of fast-setting calcium phosphate cement (FSCPC) between femoral muscles of the rat was investigated to evaluate the possible value of FSCPC for medical and dental application. Conventional CPC (c-CPC) and FSCPC were implanted between femoral muscles, and various aspects of the setting behaviour such as setting time, mechanical strength and conversion ratio of cement into hydroxyapatite (HAP: Ca10(PO4)6(OH)2) were measured by the Vicat needle method, diametral tensile strength (DTS) measurement, and quantitative powder X-ray diffraction (XRD) analysis, respectively. The setting time of FSCPC in vivo was 5-7 min, in contrast to 48 min for c-CPC. As a result of its fast setting, set specimens of FSCPC showed higher mechanical strength from the initial stage than c-CPC. Higher DTS values were observed in FSCPC than c-CPC implanted after 24 h. Powder XRD analysis revealed faster conversion of FSCPC than c-CPC into HAP, which was responsible both for the faster setting and higher mechanical strength from the initial stage. We concluded, therefore, that FSCPC may be used for a wide range of clinical applications, i.e. fields where fast setting is required such as orthopaedic, plastic and reconstructive, and oral and maxillofacial surgery.

Animals↗
PubMed1995

Fibrinolytic activity in liver tissues of stroke-prone spontaneously hypertensive rats.

1. Plasminogen activator activity was detected in the extract solution of the liver tissues of both stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats by the synthetic substrate assay. 2. The total PA activity in the liver extract of WKY (26.8 +/- 8.3 i.u.) was about 1.5-fold higher than that of SHRSP (18.5 +/- 4.1 i.u., n = 8, P < 0.005). 3. The enzymography of the liver extract revealed three lytic bands with a molecular weight of 67 kDa, 44 kDa and 38 kDa. 4. The inhibitor activity of the liver extract was detected by the reverse fibrin autography method with one lytic resistance band at 70 kDa. 5. Thus, fibrinolytic components exist in the liver tissue of both strains of rats, but their contribution to the stroke requires further study.

Amino Acid Sequence↗
PubMed1995

Identification of urokinase-type plasminogen activator receptor in human endothelial cells and its modulation by phorbol myristate acetate.

Human endothelial cells express antithrombotic properties by producing prostacyclin, heparan sulfate and plasminogen activator (PA). Using an established cell line, TKM-33, from human umbilical vein endothelial cells, the pericellular urokinase-type PA (u-PA) activity and expression of u-PA receptor (u-PAR) were investigated. The endothelial cells produced and secreted large amounts of u-PA and low levels of tissue-type PA (t-PA) and of PA inhibitor-1 (PAI-1), which were identified by immunohistochemical study and electrophoretic enzymography. Diisopropylfluoro-phosphate-treated 125I-u-PA bound specifically to acid-treated monolayered endothelial cells with a Kd of 3.46 +/- 1.17 nM, and Bmax of (0.09 +/- 0.04) x 10(6) sites/cell. mRNA of u-PAR was detected by using Northern blot analysis. Thus, these endothelial cells express u-PAR which bounds u-PA specifically. Phorbol myristate acetate (PMA) stimulation to the endothelial cells altered the Kd value to 3.18 +/- 0.64 nM, and Bmax value to (0.19 +/- 0.10) x 10(6) sites/cell, respectively. PMA treatment of endothelial cells increased u-PAR mRNA. Similarly, H7-treated endothelial cells showed a dose-dependent increase of u-PAR mRNA. However, PMA and H7 did not stimulate the expression of u-PA and t-PA mRNAs significantly. The expression of PAI-1 mRNA was increased by both PMA and H7. These findings suggest that the established endothelial cell line, TKM-33, possesses the character of endothelial cells and expresses u-PAR on their cell surface which is occupied by intrinsic u-PA secreted from the cells. The pericellular u-PA activity and the expression of u-PAR were regulated by protein kinase pathway.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Kinetic analysis of plasminogen activation by staphylokinase/plasminogen complex in the presence of fibrin.

Staphylokinase (SAK) expresses plasminogen activator activity by forming a complex with plasminogen. In order to elucidate the mechanism for the expression of enzymatic activity of the complex, a cross-linked staphylokinase/plasminogen (SAK/plg) complex was produced with disuccinimidyl suberate, and its enzymatic characteristics were compared with those of a streptokinase/plasminogen (SK/plg) complex. SAK/plg complex and SK/plg complex showed a band with a molecular weight of 110 kDa and 140 kDa by SDS-PAGE under non-reduced condition, respectively. Both complexes exhibited plasminogen activator activity in a concentration-dependent manner on fibrin film and synthetic chromogenic substrate assay. The kinetic analysis of enzymatic activity of both complexes was performed. The plasminogen activator activity of SAK/plg complex was enhanced about 5-fold in the presence of FCB-2. However, SK/plg complex showed only 1.7-fold increase in the presence of FCB-2. These findings indicate that the SAK/plg complex reacts with fibrin, and efficient plasminogen activation is induced on fibrin surface.

Amino Acid Sequence↗
PubMed1994

Effects of alpha 2-plasmin inhibitor on plasminogen activation by staphylokinase/plasminogen complex.

Using a stable cross-linked SAK/plg complex, the effects of alpha 2-plasmin inhibitor on plasminogen activation by SAK were investigated. alpha 2-Plasmin inhibitor inhibited dose-dependently plasminogen activation by the SAK/plg complex. When FCB-2 or EACA was added to the reaction mixture of SAK/plg complex and alpha 2-plasmin inhibitor, the inhibitory activity of alpha 2-plasmin inhibitor was abolished and the enzymatic activity of the complexes was restored. alpha 2-Plasmin inhibitor inhibited the activity of the SK/plg complex, but neither FCB-2 nor EACA restored the plasminogen activator activity in the mixture of SK/plg complex and alpha 2-plasmin inhibitor. Using 125I-labeled SAK/plg complex or SK/plg complex, the reaction of the complex with alpha 2-plasmin inhibitor was analyzed. The SAK/plg complex produced a new complex with alpha 2-plasmin inhibitor. The formation of a new high molecular weight complex with alpha 2-plasmin inhibitor was abolished by both EACA or FCB-2. With regard to the SK/plg complex, neither EACA nor FCB-2 suppressed the complex formation with alpha 2-plasmin inhibitor. These findings indicate that the SAK/plg complex binds to fibrin, and that this complex expresses plasminogen activator activity without being affected by alpha 2-plasmin inhibitor.

Amino Acid Sequence↗
PubMed1994

Synthetic dipeptide, N-stearoyl-D-Ser-L-Pro-OEt, induces release of tissue-type plasminogen activator in cultured cells and in experimental animals.

The tissue-type plasminogen activator (t-PA)-releasing action of synthetic dipeptides containing Gly, Ser or Pro was investigated. Among 10 dipeptides, Boc-L-Ser-L-Pro-OH and H-L-Ser-L-Pro-OH induced t-PA release in vitro, but the others were inactive. Since Boc-L-Ser-L-Pro-OH was more effective than H-L-Ser-L-Pro-OH, 7 related dipeptides with N-acylation were synthesized. Five of them enhanced the release of t-PA; N-stearoyl-L-Ser-L-Pro-OH (FK-5) had the greatest effect. Four compounds were further examined for activity to enhance the release of t-PA in rats. FK-5 produced a two-fold increase in fibrinolytic activity, and N-palmitoyl-L-Ser-L-Pro-OH (FK-4) also markedly enhanced the release of t-PA. Since FK-5 caused severe hemolysis, 7 analogues of FK-5 were synthesized. All of them enhanced the release of t-PA from melanoma (Bowes) cells. In rats, FK-5, N-stearoyl-D-Ser-L-Pro-OH (FK-8) and N-stearoyl-D-Ser-L-Pro-OEt (FK-10) enhanced the fibrinolytic activity two-fold. FK-5 and FK-8 also exhibited strong hemolytic activity, but FK-10 did not induce hemolysis. Therefore, FK-10 was examined in rabbits. After the injection of this compound, the fibrinolytic activity in the euglobulin fraction was markedly enhanced without accompanying hemolysis. Thus, FK-10 potently enhances fibrinolytic activity both in vitro and in vivo.

Amino Acid Sequence↗
PubMed1994

Recombinant variants of tissue-type plasminogen activator containing amino acid substitutions in the fibronectin finger-like domain and the kringle 1 domain.

Tissue-type plasminogen activator (t-PA) is a fibrin-specific agent which is used to treat acute myocardial infarction. Pharmacokinetically, t-PA is characterized by a rapid clearance from the circulation. In a previous study, we constructed variant forms of t-PA with genetic modifications at the fibronectin finger-like domain (finger domain) or at the kringle 1 domain (K1 domain). The finger modified variant, t-PA N37S.S38V.G39V.R40E. A41F.Q42S had about a 6.0-fold higher plasma half-life in vivo than wild-type t-PA. Two variants with modifications in the K1 domain, t-PA G161R.K162R.S165W and t-PA N115P, showed an improved kinetic parameters and a 2.2-fold higher plasma half-life in vivo than wild-type t-PA, respectively. To create a recombinant variant of t-PA with a higher enzymatic activity and a further prolonged half-life in vivo, the genes containing each modifications were joined and expressed in animal cells. The two variants, t-PA N37S.S38V.G39V.R40E.A41F.Q42S.G16 1R.K162R.S165W and t-PA N37S.S38V.G39V.R40E.A41F.Q42S.N11 5P, were purified from conditioned media and their biochemical, pharmacokinetic and thrombolytic profiles were investigated. Although the variant t-PA N37S.S38V.G39V.R40E.A41F.Q42S.G16 1R.K162R.S165W demonstrated an impaired enzymatic activity compared to the wild-type t-PA, the half-life of the variant, t-PA N37S.S38V.G39V.R40E.A41F.Q42S. N115P, following intravenous bolus injection in rabbits was considerably longer than that of finger-domain modified variants.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Effect of bone resorbing factors on u-PA and its specific receptor in osteosarcoma cell line.

This study investigated the effect of bone resorbing factors on the pericellular fibrinolytic system of osteosarcoma NY cells. Parathyroid hormone (PTH), prostaglandin E2, (PGE2) or tumor necrosis factor alpha (TNF-alpha) enhanced the secretion of urokinase-type plasminogen activator (u-PA) antigen and suppressed the secretion of plasminogen activator inhibitor-1 (PAI-1) antigen to the conditioned medium. The former two factors also increased u-PA antigen in the cell surface. Transforming growth factor beta (TGF-beta) enhanced u-PA antigen, but its activity was suppressed due to the increased secretion of PAI-1. The binding assay of [125I]DFP-u-PA to NY cells revealed the presence of a single class of binding sites with a Kd of 5.51 nM and Bmax of 0.92 x 10(5) binding sites/cell. PTH or PGE2 increased Bmax 1.4-fold and enhanced the u-PA receptor (u-PAR) mRNA level 1.4-fold or 2.4-fold, respectively. However, TGF-beta did not alter either the Kd or u-PAR mRNA level. Thus, pericellular fibrinolytic activity by u-PA/u-PAR and PAI-1 is modulated by bone resorbing factors.

Bone Resorption↗
PubMed1993

Regulation of scu-PA secretion and u-PA receptor expression in osteoblast-like cells.

The production of proteolytic enzymes by osteoblasts is considered important for initiating osteoclastic bone resorption. Using the established cell line NY as an example of osteoblast-like cells, the effect of intracellular cyclic AMP (cAMP) and protein kinase C (PKC) on plasminogen activator secretion and its specific binding to the cells were investigated. HT-1080 cells were used as the control. NY cells predominantly secrete single-chain urokinase-type plasminogen activator (scu-PA) and some two-chain u-PA. Both scu-PA and u-PA were present in the cell surface and cell lysate of NY cells, and their distribution in HT-1080 cells was quite similar to that of NY cells. Exposing cells to phorbol myristate acetate (PMA) or dibutyryl cyclic AMP (db cAMP) enhanced the secretion of scu-PA and two-chain u-PA, whereas 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7) decreased scu-PA secretion, indicating that it is enhanced by protein kinase C (PKC) as well as by cAMP in NY cells. On the other hand, in HT-1080 cells, PMA decreased the level of two-chain u-PA secretion into the conditioned medium. The binding assay of 125I-DFP-u-PA to NY cells revealed the presence of a single class of binding sites with a Kd of 2.23 nM and Bmax of 0.82 x 10(6) binding sites/cell. PMA however, altered neither the Kd nor the Bmax. Dibutyryl cAMP increased the Bmax 1.9 fold. Thus, NY cells secrete u-PA and express specific binding sites on the cell surface, which are modulated by cAMP and PKC.(ABSTRACT TRUNCATED AT 250 WORDS)

Cyclic AMP↗
PubMed1993

[Molecular biology of tissue-type plasminogen activator (t-PA) and clinical application of recombinant t-PA].

Activation of blood fibrinolysis is initiated by the activation of plasminogen to plasmin by plasminogen activator (PA). The plasmin thus produced can degrade fibrin, the main component of thrombus. Tissue-type PA (t-PA) which is mainly secreted from vascular endothelial cells possesses a high affinity for fibrin in contrast to urokinase-type PA (u-PA). Enzymatic activity of t-PA is expressed in either single-chain form or two-chain form. Further, t-PA activity enhanced markedly in the presence of fibrin; 600-1,000-fold increase. Thus, the thrombolytic therapy is now being performed by using t-PA. The mechanism for thrombolysis by t-PA involves the activation of fibrinolytic system on the fibrin surface. The kringle 2 domain of t-PA molecule plays an important role on the binding to fibrin. But in single-chain t-PA, finger domain plays a role for its binding to fibrin. Recent studies have revealed that the t-PA specific receptor (t-PAR) is expressed on the endothelial cells which localizes t-PA activity by fixing t-PA around the cells.

Amino Acid Sequence↗
PubMed1992

Recombinant variants of tissue-type plasminogen activator containing amino acid substitutions in the finger domain.

Tissue-type plasminogen activator (t-PA) is a fibrin-specific agent which has been used to treat acute myocardial infarction. In an attempt to clarify the determinants for its rapid clearance in vivo and high affinity for fibrin clots, we produced five variants containing amino acid substitutions in the finger domain, at amino acid residues 7-9, 10-14, 15-19, 28-33, and 37-42. All the variants had a prolonged half-life and a decreased affinity for fibrin of various degrees. The 37-42 variant demonstrated about a 6-fold longer half-life with a lower affinity for fibrin. Human plasma clot lysis assay estimated the fibrinolytic activity of the 37-42 variant to be 1.4-fold less effective than that of the wild-type rt-PA. In a rabbit jugular vein clot lysis model, doses of 1.0 and 0.15 mg/kg were required for about 70% lysis in the wild-type and 37-42 variant, respectively. Fibrinogen was degraded only when the wild-type rt-PA was administered at a dose of 1.0 mg/kg. These findings suggest that the 37-42 variant can be employed at a lower dosage and that it is a more fibrin-specific thrombolytic agent than the wild-type rt-PA.

Amino Acids↗
PubMed1992

Tissue-type plasminogen activator, type 1 plasminogen activator inhibitor and their complex in plasma with disseminated intravascular coagulation.

The levels of tissue-type plasminogen activator (t-PA), type 1 plasminogen activator inhibitor (PAI-1), and t-PA/PAI-1 complex antigens were analyzed in the plasma of disseminated intravascular coagulation (DIC) patients and healthy controls. Other fibrinolytic parameters such as the levels of plasminogen, alpha 2-antiplasmin (alpha 2-AP), plasmin/alpha 2-AP (PAP), and D-dimer were also estimated to clarify the fibrinolytic states in these plasmas. The antigens of t-PA, PAI-1, and t-PA/PAI-1 complex were found to increase from 8.5 +/- 4.3, 54.4 +/- 21.2, and 8.6 +/- 3.5 ng/ml in normal plasma to 36.4 +/- 25.1, 106.8 +/- 54.7, and 46.6 +/- 34.5 ng/ml in DIC plasma, respectively. The molar ratio of total t-PA to total PAI-1 was 1:6 and 1:3 in normal plasma and DIC plasma, respectively, indicating an enhanced fibrinolytic state in the DIC plasma. The DIC plasma revealed a significant consumption of plasminogen (62.1 +/- 27.8%), and alpha 2-AP (63.7 +/- 25.3%) and an increase in PAP (2.6 +/- 2.7 micrograms/ml) and D-dimer (3.9 +/- 10.7 micrograms/ml). These results suggest that the production and secretion of t-PA and PAI-1 from endothelial cells were enhanced in DIC, resulting in an increased t-PA/PAI-1 complex with dominant fibrinolytic activity.

Disseminated Intravascular Coagulation↗
PubMed1992

Analysis of binding protein for tissue-type plasminogen activator in human endothelial cells.

The specific binding sites for tissue-type plasminogen activator (t-PA) were investigated in human umbilical vein endothelial cells. After adding 125I-t-PA (M.W. 70 kDa) to endothelial cells in suspension culture, the ligand was recovered from the cell extract after disuccinimidyl suberate treatment as a high molecular complex with M.W. of 90 kDa on SDS-PAGE. The complex reacted to only anti-t-PA IgG but not to anti-PAI-1 IgG immunoblot analysis, indicating a t-PA specific binding protein. 125I-t-PA ligand blotting of the cell extract revealed that the binding protein had M.W. 20 kDa. The binding of 125I-t-PA to endothelial cells was reduced in the presence of an excess amount of t-PA, plasminogen and 6-aminohexanoic acid, indicating that the binding sites were also recognized by plasminogen, and that t-PA and plasminogen were bound via lysine binding sites in the molecule. These findings suggest that human endothelial cells have specific t-PA binding molecules which may be expressed on the cell surface as t-PA receptors.

Aminocaproic Acid↗
PubMed1992

Cerebral plasminogen activator activity in spontaneously hypertensive stroke-prone rats.

BACKGROUND AND PURPOSE: In the spontaneously hypertensive stroke-prone rat, it is unclear whether plasminogen activator plays a role in the development of stroke. The present study was undertaken to investigate brain levels of plasminogen activator activity in spontaneously hypertensive stroke-prone rats and Wistar-Kyoto rats. METHODS: Plasminogen activator was purified from the brains of rats of both strains. The purification involved used ammonium sulfate precipitation, gel filtration, a zinc chelate-Sepharose column, and a concanavalin A-Sepharose column. Fraction I (0.15 M KCl-soluble fraction) and fraction II (2 M KCl plus 6 M urea-soluble fraction) were purified from both strains. RESULTS: Total plasminogen activator activity in the original homogenates for fractions I and II derived from spontaneously hypertensive stroke-prone rats was increased to twice the level found in Wistar-Kyoto rats. The final product purified from fractions I and II in both strains of rats revealed single bands of plasminogen activator activity on enzymatic analysis with a molecular weight of 72,000. The purified product had stronger S-2288 amidolytic activity than S-2444 amidolytic activity, and it also displayed fibrin-binding ability. CONCLUSIONS: The study demonstrated that there is an increased content of plasminogen activator in the brains of spontaneously hypertensive stroke-prone rats that might be related to the development of stroke.

Animals↗
PubMed1991

Comparative fibrinolytic properties of staphylokinase and streptokinase in animal models of venous thrombosis.

The thrombolytic and pharmacokinetic properties of staphylokinase were compared with those of streptokinase in hamsters with a pulmonary embolus produced from human plasma or from hamster plasma, and in rabbits with a jugular vein blood clot produced from rabbit blood. In both models, a continuous intravenous infusion of staphylokinase and streptokinase over 60 min in hamsters or over 4 h in rabbits, induced dose-dependent progressive clot lysis in the absence of significant systemic activation of the fibrinolytic system. The results of thrombolytic potency (clot lysis at 30 min after the end of the infusion, in percent, versus dose administered, in mg/kg) were fitted with an exponentially transformed sigmoidal function (formula: see text) and the maximal percent clot lysis (c), the maximal rate of lysis (z = 1/4 ac.eb) and the dose at which the maximal rate of lysis is achieved (b) were determined. In hamsters with a pulmonary embolus produced from human plasma, streptokinase had a somewhat higher thrombolytic potency than staphylokinase, as revealed by a higher z value (2,100 +/- 1,100% lysis per mg/kg streptokinase administered versus 1,100 +/- 330% lysis per mg/kg for staphylokinase). In hamsters with a pulmonary embolus produced from hamster plasma, staphylokinase had a somewhat higher thrombolytic potency than streptokinase (z = 1,600 +/- 440 versus 1,200 +/- 370% lysis per mg/kg). Staphylokinase had a higher thrombolytic potency than streptokinase in rabbits,as revealed by a higher z-value (950 +/- 350% lysis per mg/kg staphylokinase administered versus 330 +/- 39% lysis per mg/kg for streptokinase) and a lower b-value (0.035 +/- 0.010 mg/kg staphylokinase versus 0.091 +/- 0.008 mg/kg for streptokinase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Plasminogen activator inhibitor 1 in human carcinoma tissues.

The content of PAI-I was measured in carcinoma tissues from the stomach and colorectum divided macroscopically into 3 portions: the central part of the carcinoma, the marginal part of the carcinoma containing some normal mucosa, and the normal mucosa. Among these tissues, the highest levels of PAI-I antigen were found in the central part of the carcinoma. On the other hand, no PAI-I antigen or activity was observed in the normal mucosae. The PAI-I produced in the stomach and colorectal carcinoma tissues showed a non-lytic zone with a molecular weight of 54 kDa by reverse fibrin autography, and this 54-kDa band reacted with anti-PAI-I IgG on an immunoblotted nitrocellulose membrane by the avidin-biotin complex method. The contents of PAI-2 in the carcinoma tissues were not significantly different from those in the normal mucosa of the stomach and colorectum. In both the stomach and colorectal carcinomas, the highest value of u-PA/total PA (sum of u-PA and t-PA) was observed in the central part of the carcinoma, followed by the marginal part of the carcinoma, and was lowest in the normal mucosa. We conclude that increased levels of PAI-I in malignant tissue of the stomach and colorectal tract may serve to modulate extra-cellular proteolysis by u-PA.

Biomarkers, Tumor↗