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Biomedical subjects

K Furuhashi

Publications and source records attributed to K Furuhashi.

At least 19 recordsLinked to original sources
PubMed1996

[The effect of prostaglandin E1 on body temperature, catecholamines and stress hormones during prolonged surgery].

The effects of prostaglandin E1 (PGE1) on body temperature, catecholamines and stress hormones were evaluated in 10 patients undergoing elective prolonged surgery over 12 hours. PGE1 (0.03 microgram.kg-1.min-1) was administered in 5 patients and was not administered in 5 patients. Deep skin-surface temperature gradients were 5.1 +/- 2.3 degrees C in PGE1 non-administered group and 0.8 +/- 0.9 degree C in PGE1 administered group (P < 0.05). Pharyngeal-skin surface temperature gradients were 8.8 +/- 2.1 degrees C in PGE1 non-administered group and 1.5 +/- 1.5 degrees C in PGE1 administered group (P < 0.05). There were no significant differences between the two groups in respects to catecholamines, stress hormones, lactate level and blood sugar. PGE1 0.03 microgram.kg-1.min-1 is effective in maintaining peripheral circulation without causing body temperature changes during prolonged surgery.

Adrenocorticotropic Hormone↗
PubMed1995

Ouabain enhances nitric oxide synthesis in rat vascular smooth muscle cells induced by interleukin-1 beta.

Incubation of cultured rat vascular smooth muscle cells with interleukin-1 beta caused a significant increase in the production of nitrite, a stable metabolite of nitric oxide (NO), in time- and dose-dependent manners. Addition of ouabain to the culture further enhanced interleukin-1 beta-induced nitrite production. Similarly, interleukin-1 beta produced a significant increase in the cellular level of guanosine 3',5'-cyclic monophosphate, and the increase was significantly enhanced by coincubation with ouabain. The calcium ionophore ionomycin also significantly enhanced interleukin-1 beta-induced nitrite generation. These findings indicate that ouabain enhances NO synthesis in vascular smooth muscle cells induced by interleukin-1 beta, presumably through an increase in intracellular calcium ion concentrations.

Animals↗
PubMed1995

The coagulation system is activated in idiopathic cardiomyopathy.

OBJECTIVES: We investigated the plasma levels of molecular markers for platelet activity and the thrombotic and fibrinolytic status in patients with hypertrophic cardiomyopathy and dilated cardiomyopathy to determine the activating site of coagulation in these disorders. BACKGROUND: A thromboembolic event is a serious complication in patients with idiopathic cardiomyopathy. However, the activating site of the coagulation system in idiopathic cardiomyopathy has not been fully investigated. METHODS: We determined the plasma levels of molecular markers for platelet activity (platelet factor 4 and beta-thromboglobulin), thrombotic status (fibrinopeptide A and thrombin-antithrombin III complex) and fibrinolytic status (D-dimer and plasmin-alpha 2-plasmin inhibitor complex) in 13 patients with hypertrophic cardiomyopathy, 17 patients with dilated cardiomyopathy and 20 normal subjects. RESULTS: Plasma levels of platelet factor 4, beta-thromboglobulin and plasmin-alpha 2-plasmin inhibitor complex did not differ significantly among the three groups, whereas plasma levels of fibrinopeptide A and thrombin-antithrombin III complex in both patient groups were significantly higher than those in normal subjects. Plasma levels of D-dimer in patients with dilated cardiomyopathy were significantly higher than those in patients with hypertrophic cardiomyopathy and normal groups. In patients with hypertrophic cardiomyopathy, both fibrinopeptide A and thrombin-antithrombin III complex levels were significantly correlated with left atrial diameter. In patients with dilated cardiomyopathy, fibrinopeptide A and thrombin-antithrombin III complex levels showed a positive correlation with left ventricular end-diastolic volume and a negative correlation with fractional shortening of the left ventricle. CONCLUSIONS: The activated coagulation system in patients with hypertrophic and dilated cardiomyopathy may be triggered by left atrial dilation in hypertrophic cardiomyopathy and left ventricular enlargement and dysfunction in dilated cardiomyopathy.

Antifibrinolytic Agents↗
PubMed1995

[Clinical evaluation of prophylactic nitroglycerin infusion during coronary artery bypass grafting].

We evaluated retrospectively the benefit of prophylactic nitroglycerin (TNG) infusions during elective coronary artery bypass grafting (CABG) in 73 patients. In all patients anesthesia was maintained with high dose fentanyl. Thirty-seven patients were infused TNG 0.3 microgram.kg-1.min-1 during surgery and 36 patients were not. The TNG-infused patients demonstrated lower perfusion pressure during cardiopulmonary bypass (CPB) and higher incidence of inotropic administrations than the uninfused patients. Serum myocardial creatine phosphokinase (CPK-MB) levels of TNG-infused patients were higher than those of TNG-uninfused patients on the first postoperative day. We speculate that inotropic administrations under low myocardial perfusion pressure at the time of weaning from CPB induces myocardial ischemia which in turn causes an increase in serum CPK-MB level. We conclude that prophylactic administration of TNG does not prevent perioperative ischemia during CABG.

Anesthesia, General↗
PubMed1993

Decrease of ischaemia-reperfusion related lung oedema by continuous ventilation and allopurinol in rat perfusion lung model.

Using isolated perfusion rat lung model, we studied the effect of continuous ventilation without perfusion and allopurinol on the development of ischaemia-reperfusion lung injury. Ischaemia was induced by stopping the perfusion. Normothermic ischaemia for 90 min without ventilation caused significant lung oedema. Continuous ventilation during ischaemia with 21% O2 decreased lung oedema significantly after 60 min of reperfusion. The same protection could be achieved by 100% N2 ventilation during 90 min of ischaemia, suggesting that xanthine oxidase (XO) is unlikely to cause the ischaemia-reperfusion lung injury. On the other hand allopurinol, XO inhibitor, equally inhibited lung oedema after 90 min of ischaemia and 60 min of reperfusion. These results indicate that mechanical movement of alveoli provides successful preservation of ischaemic lung, and allopurinol has some protective effect other than XO inhibition.

Allopurinol↗
PubMed1992

Identification of actin kinase activity in purified fragmin-actin complex.

Actin kinase phosphorylates actin of fragmin-actin complex, resulting in the inactivation of the nucleation and capping activities of the complex. Fragmin-actin complex was prepared by a new purification procedure. Incubation with ATP caused inactivation of the purified complex and phosphorylation of actin of fragmin-actin complex. The detailed analysis of the complex by SDS-gel electrophoresis showed that actin kinase was co-purified with the fragmin-actin complex. Formation of such an association between actin kinase and substrate suggests that the kinase is localized on the fragmin-actin complex to efficiently regulate actin cytoskeletons.

Actins↗
PubMed1992

Requirement of phosphatidylinositol 4,5-bisphosphate for alpha-actinin function.

Inositol phospholipid turnover is enhanced during mitogenic stimulation of cells by growth factors and the breakdown of phosphatidylinositol 4,5-bisphosphate (PtdInsP2) may be important in triggering cell proliferation. PtdInsP2 also binds actin-binding proteins to regulate their activity, but it is not yet understood how this control is achieved. The protein alpha-actinin from striated muscle contains large amounts of endogenous PtdInsP2, whereas that from smooth muscle has only a little but will bind exogenously added PtdInsP2. In vitro alpha-actinin binds to F-actin and will crosslink actin filaments, increasing the viscosity of F-actin solutions. We report here that alpha-actinin from striated muscle is an endogenous PtdInsP2-bound protein and that the specific interaction between alpha-actinin and PtdInsP2 regulates the F-actin-gelating activity of alpha-actinin. Although the F-actin-gelating activity of alpha-actinin from smooth muscle is much reduced compared with that from striated muscle, exogenous PtdInsP2 can enhance the activity of smooth muscle alpha-actinin to the level seen in striated muscles. These results show that PtdInsP2 is present in striated muscle alpha-actinin and that it is necessary for alpha-actinin to realize its maximum gelating activity.

Actinin↗
PubMed1992

Inositol phospholipid-induced suppression of F-actin-gelating activity of smooth muscle filamin.

Filamin, a high molecular weight actin-binding protein, cross-links actin filaments and produces a gel composed of F-actin. The effects of polyphosphoinositides on the gelating activity of smooth muscle filamin were examined by measuring the low shear viscosity of the F-actin solutions containing filamin incubated with phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP), or phosphatidylinositol 4,5-bisphosphate (PIP2). Micelles of these inositol phospholipids bound to filamin inhibited the ability to form a gel of F-actin. The inhibiting activity of each phospholipid was in the following order, PIP2 greater than PIP greater than PI. The F-actin binding assay of filamin revealed that the inhibition of F-actin-gelation resulted in the loss of the F-actin-binding activity of filamin. Thus, polyphosphoinositides may play important roles in regulating the gelating activity of filamin.

Actins↗
PubMed1992

Phosphorylation by actin kinase of the pointed end domain on the actin molecule.

Fragmin from plasmodium of Physarum polycephalum binds G-actin and severs F-actin in the presence of Ca2+ over 10(-6) M. The fragmin-actin complex consisting of fragmin and G-actin nucleates actin polymerization and caps the barbed (fast growing) end of F-actin, regardless of the concentrations of Ca2+, and the actin filaments are shortened. Actin kinase purified from plasmodium abolishes the nucleation and capping activities of the complex by phosphorylating actin of the fragmin-actin complex (Furuhashi, K., and Hatano, S. (1990) J. Cell. Biol. 111, 1081-1087). This inactivation of the complex leads to production of long actin filaments. We obtained evidence that Physarum actin is phosphorylated by actin kinase at Thr-201, and probably at Thr-202 and/or Thr-203, with 1 mol of phosphate distributed among them. This finding raises the possibility that the site of phosphorylation, Thr-201 to Thr-203, is positioned on the pointed (slow growing) end domain of the actin molecule, because growth of actin filaments from the fragmin-actin complex occurs only from the pointed end. These observations are consistent with a model of the three-dimensional structure of G-actin. Inactivation of the fragmen-actin complex may follow phosphorylation of the pointed end domain of actin.

Actins↗
PubMed1992

Actin kinase: a protein kinase that phosphorylates actin of fragmin-actin complex.

Actin of fragmin-actin complex is phosphorylated by an endogenous kinase from plasmodium of Physarum polycephalum. The phosphorylation abolishes the nucleation and capping activities of fragmin-actin complex. The kinase has been purified and termed actin kinase [Furuhashi, K. & Hatano, S. (1990) J. Cell Biol. 111, 1081-1087]. Enzymatic properties of the purified actin kinase were studied in detail. Actin kinase exhibited the highest activity under conditions physiological for the plasmodium (30 mM KCl, 6 mM MgCl2, pH 7.0). The Vmax and the Km of the enzyme for ATP were about 83 mumol/min/mg and 25 microM, respectively. The Km for fragmin-actin complex was 190 nM. The purified actin kinase phosphorylated actin of fragmin-actin complex at a constant rate regardless of Ca2+ concentration. Similarly, 2 microM cAMP, 2 microM cGMP, 2 micrograms/ml calmodulin in the presence of Ca2+ or 1 mM GTP showed no effect on the activity of the purified enzyme. Actin kinase did not phosphorylate histone H1, H2B, alpha-casein, or beta-casein, suggesting that actin kinase is a new kind of protein kinase which specifically phosphorylates actin of the fragmin-actin complex.

Actins↗
PubMed1990

Primary structure of profilins from two species of Echinoidea and Physarum polycephalum.

Profilin is a small G-actin-binding protein, the amino acid sequence of which was previously reported for calf, human, Acanthamoeba and yeast. Here the amino acid sequences of three profilins obtained from eggs of two species of Echinoidea, Clypeaster japonicus (order, Clypeasteroida) and Anthocidaris crassispina (order, Echinoida), and plasmodium of Physarum polycephalum were determined. Two echinoid profilins were composed of 139 amino acid residues, N-termini were acylated and the molecular mass was calculated to be 14.6 kDa, slightly larger than that of 13 kDa estimated by SDS/PAGE [Mabuchi, I. & Hosoya, H. (1982) Biomed. Res. 3, 465-476]. On the other hand, Physarum profilin was composed of 124 amino acid residues, the N-terminus was acylated, and the calculated molecular mass was 13132 Da. The sequences of C. japonicus and A. crassispina profilins were homologous (84% identical). However, the similarity of these profilins with those form other organisms was low. The sequence of Physarum profilin was homologous with Acanthamoeba profilin isoforms (51% identical) and with yeast profilin (42% identical), but not with other profilins. The relatively conservative sequence of profilins from yeast, Physarum, Acanthamoeba, echinoid eggs and mammalian cells was found in the N-terminal region, which was suggested to be a common actin-binding region. The C-terminal region was also conserved, although to a lesser extent than the N-terminal region.

Amino Acid Sequence↗
PubMed1990

Control of actin filament length by phosphorylation of fragmin-actin complex.

Fragmin is a Ca2(+)-sensitive F-actin-severing protein purified from a slime mold, Physarum polycephalum (Hasegawa, T., S. Takahashi, H. Hayashi, and S. Hatano. 1980. Biochemistry. 19:2677-2683). It binds to G-actin to form a 1:1 fragmin/actin complex in the presence of micromolar free Ca2+. The complex nucleates actin polymerization and caps the barbed end of the short F-actin (Sugino, H., and S. Hatano. 1982. Cell Motil. 2:457-470). Subsequent removal of Ca2+, however, hardly dissociates the complex. This complex nucleates actin polymerization and caps the F-actin regardless of Ca2+ concentration. Here we report that this activity of fragmin-actin complex can be abolished by phosphorylation of actin of the complex. When crude extract from Physarum plasmodium was incubated with 5 mM ATP and 1 mM EGTA, the activities of the complex decreased to a great extent. The inactivation of the complex in the crude extract was not observed in the presence of Ca2+. In addition, the activities of the complex inactivated in the crude extract were restored under conditions suitable for phosphatase reactions. We purified factors that inactivated fragmin-actin complex from the crude extract. These factors phosphorylated actin of the complex, and the activities of the complex decreased with an increased level of phosphorylation of the complex. These factors, termed actin kinase, also inactivated the complex that capped the barbed end of short F-actin, leading to elongation of the short F-actin to long F-actin. Thus the length of F-actin can be controlled by phosphorylation of fragmin-actin complex by actin kinase.

Actin Cytoskeleton↗
PubMed1989

A fragmin-like protein from plasmodium of Physarum polycephalum that severs F-actin and caps the barbed end of F-actin in a Ca2+-sensitive way.

Many protein factors regulating actin polymerization can be extracted from plasmodia of Physarum polycephalum in the presence of a high EGTA concentration (30 mM). A protein factor with the molecular weight of 60,000 (60 kDa protein) was especially interesting because of its fragmin-like properties. We purified and characterized this 60 kDa protein in the present study. The purified 60 kDa protein enhanced the initial rate of G-actin polymerization, severed F-actin, and capped the barbed end of F-actin in a Ca2+-dependent way. The threshold concentration for Ca2+ was around 10(-6) M. The flow birefringence measurement showed that the length of F-actin decreased from 2.8 to 1.0 microns depending on the concentration of 60 kDa protein added to F-actin. These properties were identical to those of fragmin (Mr 42,000) isolated from plasmodia (Hasegawa et al. (1980) Biochemistry 19, 2677-2683). However, the molecular weight, the tryptic peptide map, and the cross-reactivities with polyclonal anti-fragmin antibodies were different from those of fragmin. We concluded from these results that 60 kDa protein is a new Ca2+-sensitive F-actin-severing protein. Considering its similarity to fragmin, we termed the 60 kDa protein fragmin 60.

Actins↗