Comparison of administration of single- and triple-course steroid pulse therapy combined with tonsillectomy for immunoglobulin A nephropathy

Immunoglobulin A nephropathy (IgAN) is a form of chronic glomerulonephritis that can cause end-stage renal disease. Recently, tonsillectomy combined with corticosteroid pulse (TSP) has been shown to be effective for achieving clinical remission and favorable renal outcome in patients with IgAN. However, the standard regimen of corticosteroid use in TSP has not been established. Herein, we compared the effect of single- or triple-course steroid pulse therapy combined with tonsillectomy in patients with IgAN.This retrospective, observational cohort study included 122 patients with IgAN enrolled from January 2004 to December 2018 at 2 independent institutions. We divided the patients into 2 groups; single-course (TSP1: n = 70) and triple-course (TSP3: n = 52) of corticosteroid pulse therapy (1 course comprised 3 consecutive days' infusion of 0.5 g methylprednisolone) combined with tonsillectomy. The primary outcome for renal survival was defined as the first occurrence of ≧30% decrease in estimated glomerular filtration rate from baseline. Secondary outcomes included the incidence of clinical remission and recurrence of the disease.Regarding clinical parameters and findings at baseline, there were no significant differences between the 2 groups. The 8-years renal survival in the 2 groups was not significantly different according to Kaplan-Meier curves (TSP1; 82.5% vs TSP3; 69.2%, log-rank test P = .39). The cumulative incidence rates of remission of hematuria (94.4% vs 85.4%, P = .56) and clinical remission (85.0% vs 64.8%, P = .07) were comparable in both groups, while those of proteinuria showed higher rates in TSP1 than TSP3 (88.4% vs 65.4%, P = .02). The cumulative incidence of relapse of hematuria (5.6% vs 2.3%, P = .42) and proteinuria (7.1% vs 3.3%, P = .41) showed no significant differences in the 2 groups. Cox regression analyses showed that the number of courses of corticosteroid pulse therapy was not significantly associated with renal outcome (TSP1 vs TSP3; Hazard ratios 0.69, 95% confidence intervals 0.29-1.64, P = .39).The effect of single-course corticosteroid pulse therapy is not statistically, significantly different from triple-course in TSP protocol for improving renal outcome and preventing relapse in patients with IgAN. Single-course corticosteroid pulse therapy may become a treatment option for patients with IgAN.

Anti-allergic effect of the Src family kinase inhibitor saracatinib

The aim of this study was to evaluate the anti-anaphylactic and anti-allergic potentials of saracatinib, a Src family kinase inhibitor that was already shown to be safe in clinical trials when it was used as an anti-cancer drug. Using in vitro mast cell models, we found that saracatinib inhibited the degranulation response and cytokine production in RBL2H3 cells that were stimulated with IgE and antigen without affecting cell viability. Phosphorylation of Lyn, Akt, a PI3K substrate, and MAPKs including ERK, JNK, and p38, as well as the intracellular Ca²⁺ increase induced by this stimulation were also suppressed by saracatinib. This drug also inhibited symptoms in our established anaphylaxis mouse model, anaphylaxis-dependent spotted distribution of immune complex in skin (ASDIS). The intravenous injection of the mixture of IgE and antigen induced acute spotted distribution of immune complex in skin in hairless HR-1 mice, and its inhibition by intradermal injection of saracatinib was observed. Moreover, toluidine blue-stained skin sections indicated that the degranulation ratio of dermal mast cells was reduced in saracatinib-treated skin compared with vehicle-treated skin. Because only a few signaling inhibitors are used as anti-anaphylaxis and anti-allergic drugs, these results indicated the valuable suggestion that saracatinib and the Src family kinase inhibitors are good candidates for anti-anaphylaxis and anti-allergic drugs.

Direct observation of orientation distributions of actin filaments in a solution undergoing shear banding

Shear banding is frequently observed in complex fluids. However, the configuration of macromolecules in solutions undergoing shear banding has not yet been directly observed. In this study, by using the fact that F-actin solutions exhibit shear banding and actin filaments are visualized by fluorescent labels, we directly observed the intrinsic states of an actin solution undergoing shear banding. By combining the 3D imaging of labeled actin filaments and particle image velocimetry (PIV), we obtained orientation distributions of actin filaments in both high and low shear rate regions, whose quantitative differences are indicated. In addition, by using the orientation distributions and applying stress expression for rod-like polymers, we estimated stress tensors in both high and low shear rate regions. This evaluation indicates that different orientation distributions of filamentous macromolecules can exhibit a common shear stress.

Dispersion relation in oscillatory reaction-diffusion systems with self-consistent flow in true slime mold

In the large amoeboid organism Physarum, biochemical oscillators are spatially distributed throughout the organism and their collective motion exhibits phase waves, which carry physiological signals. The basic nature of this wave behaviour is not well-understood because, to date, an important effect has been neglected, namely, the shuttle streaming of protoplasm which accompanies the biochemical rhythms. Here we study the effects of self-consistent flow on the wave behaviour of oscillatory reaction-diffusion models proposed for the Physarum plasmodium, by means of numerical simulation for the dispersion relation and weakly nonlinear analysis for derivation of the phase equation. We conclude that the flow term is able to increase the speed of phase waves (similar to elongation of wave length). We compare the theoretical consequences with real waves observed in the organism and also point out the physiological roles of these effects on control mechanisms of intracellular communication.

A novel therapeutic approach combining human plasma-derived Factors VIIa and X for haemophiliacs with inhibitors: evidence of a higher thrombin generation rate in vitro and more sustained haemostatic activity in vivo than obtained with Factor VIIa alone

BACKGROUND AND OBJECTIVES

Therapy with recombinant Factor VIIa (rFVIIa) for haemophiliacs with inhibitors still has some unresolved problems, such as the requirement for frequent infusions of rFVIIa every 2-3 h to sustain haemostatic activity for an extended time-period and that the therapeutic dose of rFVIIa is not always predictable. In the present study, we searched for an effective combination of plasma-derived FVIIa with other blood coagulation factors, and demonstrated that a therapeutic approach combining plasma-derived FVIIa and Factor X (FX) was more useful for treating haemophiliacs with inhibitors than FVIIa alone.

MATERIALS AND METHODS

The haemostatic effects of FVIIa and FX were evaluated in vitro and in vivo. In in vitro experiments we assessed the following: the ability to enhance the thrombin generation rate in a reconstituted blood coagulation model without Factor VIII (FVIII) or Factor IX (FIX); the ability to correct the activated partial prothrombin time (APTT) of FVIII-depleted plasma or FIX-depleted plasma; and the ability to correct the clotting time of haemophilia-like whole blood using thromboelastography (TEG). In in vivo experiments, the haemostatic activity of the combination treatment of FVIIa and FX was determined by measuring the bleeding time and TEG using a monkey haemophilia B model produced by the injection of anti-human FIX polyclonal antibodies. The degree of thrombogenicity of the combination was evaluated using the rabbit stasis model.

RESULTS

The addition of FX to FVIIa dramatically enhanced the thrombin generation rate in the reconstituted blood coagulation model and corrected the prolonged APTTs of FVIII- and FIX-depleted plasmas to levels achieved by the replacement therapies. In contrast, the addition of prothrombin to FVIIa did not show such enhancing activity. Furthermore, FVIIa-induced whole blood clotting times in the FVIII- and FIX-inhibited states were also shortened by the addition of FX in a concentration-dependent manner. Finally, the co-administration of FVIIa (80 microg/kg) and FX (800 microg/kg) in a monkey haemophilia B model resulted in a more robust and persistent haemostatic effect on the secondary bleeding time and whole-blood clotting time of TEG than that of FVIIa alone. The results of rabbit stasis tests for evaluating the risk of thrombogenicity showed that the combination of FVIIa and FX was less thrombogenic than FEIBA.

CONCLUSIONS

The present study demonstrated that the combination of FVIIa and FX appeared to have a higher and more sustainable haemostatic potential than FVIIa alone, and less thrombogenicity than FEIBA. A therapeutic approach combining FVIIa and FX could be a promising and novel approach to compensate for the disadvantages of rFVIIa and FEIBA for haemophiliacs with inhibitors.

Large-scale production and properties of human plasma-derived activated Factor VII concentrate

BACKGROUND AND OBJECTIVES

An activated Factor VII (FVIIa) concentrate, prepared from human plasma on a large scale, has to date not been available for clinical use for haemophiliacs with antibodies against FVIII and FIX. In the present study, we attempted to establish a large-scale manufacturing process to obtain plasma-derived FVIIa concentrate with high recovery and safety, and to characterize its biochemical and biological properties.

MATERIALS AND METHODS

FVII was purified from human cryoprecipitate-poor plasma, by a combination of anion exchange and immunoaffinity chromatography, using Ca2+-dependent anti-FVII monoclonal antibody. To activate FVII, a FVII preparation that was nanofiltered using a Bemberg Microporous Membrane-15 nm was partially converted to FVIIa by autoactivation on an anion-exchange resin. The residual FVII in the FVII and FVIIa mixture was completely activated by further incubating the mixture in the presence of Ca2+ for 18 h at 10 degrees C, without any additional activators. For preparation of the FVIIa concentrate, after dialysis of FVIIa against 20 mm citrate, pH 6.9, containing 13 mm glycine and 240 mm NaCl, the FVIIa preparation was supplemented with 2.5% human albumin (which was first pasteurized at 60 degrees C for 10 h) and lyophilized in vials. To inactivate viruses contaminating the FVIIa concentrate, the lyophilized product was further heated at 65 degrees C for 96 h in a water bath.

RESULTS

Total recovery of FVII from 15 000 l of plasma was approximately 40%, and the FVII preparation was fully converted to FVIIa with trace amounts of degraded products (FVIIabeta and FVIIagamma). The specific activity of the FVIIa was approximately 40 U/ micro g. Furthermore, virus-spiking tests demonstrated that immunoaffinity chromatography, nanofiltration and dry-heating effectively removed and inactivated the spiked viruses in the FVIIa. These results indicated that the FVIIa concentrate had both high specific activity and safety.

CONCLUSIONS

We established a large-scale manufacturing process of human plasma-derived FVIIa concentrate with a high yield, making it possible to provide sufficient FVIIa concentrate for use in haemophiliacs with inhibitory antibodies.

Smart behavior of true slime mold in a labyrinth

Even for humans it is not easy to solve a maze. But the plasmodium of true slime mold, an amoeba-like unicellular organism, has shown an amazing ability to do so. This implies that an algorithm and a high computing capacity are included in the unicellular organism. In this report, we discuss information processing in the microorganism to focus on the issue as to whether the maze-solving behavior is akin to primitive intelligence.

A novel human metalloprotease synthesized in the liver and secreted into the blood: possibly, the von Willebrand factor-cleaving protease?

We identified a novel metalloprotease, which could be responsible for cleaving the Tyr842-Met843 peptide bond of von Willebrand factor (vWF). This metalloprotease was purified from Cohn Fraction-I precipitate of human pooled plasma by the combination of gel filtration, DEAE chromatography, and preparative polyacrylamide gel electrophoresis in the presence of SDS. The NH2-terminal amino acid sequence of the isolated protein was: AAGGILHLELLVAVGPDVFQAHQEDTRRY. Based on this sequence, we searched human genomic and EST databases, and identified compatible nucleotide sequences. These results suggested that this protein is a novel metalloprotease, a member of the family of a disintegrin and metalloprotease with thrombospondin type-1 motifs (ADAMTS), and its genomic DNA was mapped to human chromosome 9q34. Multiple human tissue northern blotting analysis indicated that the mRNA encoding this protease spanned approximately 5 kilobases and was uniquely expressed in the liver. Furthermore, we determined the cDNA sequence encoding this protease, and found that this protease was comprised of a signal peptide, a proregion followed by the putative furin cleavage site, a reprolysin-type zinc-metalloprotease domain, a disintegrin-like domain, a thrombospondin type-1 (TSP1) motif, a cysteine-rich region, a spacer domain, and COOH-terminal TSP1 motif repeats.

Path finding by tube morphogenesis in an amoeboid organism

We have studied how the plasmodium of Physarum polycephalum, a large amoeboid cell, is able to track the shortest path between two selected points in a labyrinth. When nutrients are supplied at these points to a sheet-like plasmodium extended fully in a maze, the organism forms a single tube which connects the two sites via the shortest route. During the path finding, plasmodial parts in dead ends of the maze shrink and finally the tube with the minimum-length is selected from the existing possibilities. A simple cellular mechanism based on interacting cellular rhythms may describe the experimental observations.

Spatiotemporal symmetry in rings of coupled biological oscillators of Physarum plasmodial slime mold

Spatiotemporal patterns in rings of coupled biological oscillators of the plasmodial slime mold, Physarum polycephalum, were investigated by comparing with results analyzed by the symmetric Hopf bifurcation theory based on group theory. In three-, four-, and five-oscillator systems, all types of oscillation modes predicted by the theory were observed including a novel oscillation mode, a half period oscillation, which has not been reported anywhere in practical systems. Our results support the effectiveness of the symmetric Hopf bifurcation theory in practical systems.

Induction of acquired factor IX inhibitors in cynomolgus monkey (Macaca fascicularis): a new primate model of hemophilia B

Inherited hemophilia dog and other transient hemophilic animal models have been used for evaluation of hemostatic agents for use in treatment of hemophilia. We established the first nonhuman primate hemophilic model by immunizing cynomolgus monkeys with human FIX (hFIX) in adjuvants. FIX activities of all three hFIX-immunized monkeys decreased transiently to less than 10% in accordance with prolongation of activated partial thromboplastin time (APTT). Forty micrograms of human factor VIIa (hFVIIa) per kilogram body weight (that was reported to be clinically effective) was administered to the monkey with the highest inhibitor titer to evaluate its usefulness as a hemophilia inhibitor model. Results of thromboelastography (TEG) after the injection demonstrated that the hemostatic effect of FVIIa in this model would be similar to that in hemophiliacs with inhibitors. The antibodies purified from the monkey's plasma by hFIX-immobilized gel were composed of two types: Ca(2+)-dependent and -independent antibodies, with features of IgG(1) and IgG(4). Both types of antibodies reacted to cynomolgus FIX, and only Ca(2+)-dependent antibodies also expressed inhibitory activity against cynomolgus FIX. Immunoblotting analyses of Ca(2+)-dependent antibodies using hFIX and its derivatives suggested that they recognized the Ca(2+)-dependent conformation related to the gamma-carboxyglutamic acid (Gla) domain. Comparison of FIX cDNA from human, cynomolgus monkey, and other species, and the results of immunization of various animals (goats, beagle dogs, rabbits, and rats) with hFIX in adjuvants strongly suggested that the development of acquired FIX inhibitors in the monkeys might be due to high cross-reactivity of the antibodies to molecular mimic antigens, hFIX, and cynomolgus FIX.

Factor VIIa modified in the 170 loop shows enhanced catalytic activity but does not change the zymogen-like property

Factor VIIa (VIIa) is an unusual trypsin-type serine proteinase that appears to exist in an equilibrium between minor active and dominant zymogen-like inactive conformational states. The binding of tissue factor to VIIa is assumed to shift the equilibrium into the active state. The proteinase domain of VIIa contains a unique structure: a loop formed by a disulfide bond between Cys310 and Cys329, which is five residues longer than those of other trypsin types. To examine the functional role of the loop region, we prepared two mutants of VIIa. One of the mutants, named VII-11, had five extra corresponding residues 316-320 of VII deleted. The other mutant, VII-31, had all of the residues in its loop replaced with those of trypsin. Functional analysis of the two mutants showed that VIIa-11 (Kd = 41 nm) and VIIa-31 (Kd = 160 nm) had lower affinities for soluble tissue factor as compared with the wild-type VIIa (Kd = 11 nm). The magnitude of tissue factor-mediated acceleration of amidolytic activities of VIIa-11 (7-fold) and that of VIIa-31 (2-fold) were also smaller than that of wild-type VIIa (30-fold). In the absence of tissue factor, VIIa-31 but not VIIa-11 showed enhanced activity; the catalytic efficiencies of VIIa-31 toward various chromogenic substrates were 2-18-fold greater than those of the wild-type VIIa. Susceptibility of the alpha-amino group of Ile-153 of VIIa-31 to carbamylation was almost the same as that of wild-type VIIa, suggesting that VIIa-31 as well as wild-type VIIa exist predominantly in the zymogen-like state. Therefore, the tested modifications in the loop region had adverse effects on affinity for tissue factor, disturbed the tissue factor-induced conformational transition, and changed the catalytic efficiency of VIIa, but they did not affect the equilibrium between active and zymogen-like conformational states.

Effect of activated human protein C on disseminated intravascular coagulation induced by lipopolysaccharide in rats

Protein C is the zymogen of an anticoagulant serine protease and is converted to its active form (activated protein C: APC) by thrombin in the presence of thrombomodulin. APC plays an important role in regulating coagulation and fibrinolysis by inactivating not only blood coagulation factors Va and VIIIa but also type-1 plasminogen activator inhibitor (PAI-1). The aim of the present study was to examine the effect of a human APC product (designated as CTC-111), compared with that of heparin, on the disseminated intravascular coagulation (DIC) induced by lipopolysaccharide (LPS) in rats. LPS (1 mg/kg/h) infusion was performed through a femoral vein for 4 h. One-fifth amount of the total dosage of CTC-111 or heparin was injected into the other femoral vein, followed by a 4-h infusion of the remainder. Both CTC-111 (10,000-100,000 U/kg) and heparin (400-800 IU/kg) inhibited the decrease in platelet count and fibrinogen level equally. The prolonged activated partial thromboplastin time and prothrombin time observed in DIC rats were further elongated in both CTC-111- and heparin-treated rats. But, this prolongation was less in CTC-111-treated rats than in the heparin-treated ones. Heparin inhibited the increase in fibrin and fibrinogen degradation products more prominently than CTC-111. On the other hand, CTC-111 strongly inhibited the increase in PAI-1 activity but heparin did not. These results suggest that CTC-111 may enhance fibrinolysis through its direct inhibitory effect on PAI-1. The parameters for liver or renal damage, i.e., plasma glutamic-oxaloacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT), creatinine (Cre) and blood urea nitrogen (BUN), were significantly increased by LPS infusion. Both CTC-111 (100,000 U/kg) and heparin (800 IU/kg) decreased the increase in GOT and GPT levels significantly, whereas neither affected the increase in Cre or BUN. From these results, the activation of the blood coagulation system might partially contribute to the progression of liver damage caused by LPS, and might be less involved in the progression of renal damage in this model. In conclusion, CTC-111 showed both anticoagulant and profibrinolytic activity in the LPS-induced DIC model without excessive prolongation of coagulation time. From these results, CTC-111 is expected to be a useful remedy for DIC without the risk of bleeding.

Interaction between cell shape and contraction pattern in the Physarum plasmodium

The relationship between cell shape and rhythmic contractile activity in the large amoeboid organism Physarum polycephalum was studied. The organism develops intricate networks of veins in which protoplasmic sol moved to and fro very regularly. When migrating on plain agar, the plasmodium extends like a sheet and develops dendritic veins toward the rear. After a particular stimulation, the vein organization changes into veinless or vein-network structures. In both structures, the mixing rate of the protoplasm, which is related to communication among contraction oscillators, decreased compared with that of the dendritic one. Accompanying these changes in vein structure, the spatio-temporal pattern of the rhythmic contraction changed into a small-structured pattern from a synchronized one. In the above process, cell shape affects the contraction pattern, but, conversely, the contraction pattern effects the cell shape. To demonstrate this, a phase difference in the rhythmic contraction was induced artificially by entraining the intrinsic rhythm to external temperature oscillations. New veins then formed along the direction parallel to the phase difference of the rhythm. Consequently, the vein organization of the cell interacts with the contractile activity to form a feedback loop in a mechanism of contraction pattern formation.

Modulation of cellular rhythm and photoavoidance by oscillatory irradiation in the Physarum plasmodium

We studied responses of cellular rhythm and light-induced movement to periodic irradiation in a unicellular amoeboid organism, the Physarum plasmodium. The intrinsic frequency of the contraction rhythm, which is based on biochemical oscillations, became synchronized with the frequency of periodic irradiation with light when both frequencies were close enough. In order to study the role of the synchronization in light-induced movement, periodic irradiation was applied to only part of the plasmodium. The rate of avoidance of light was modulated in the frequency band in which the synchronization occurred. The synchronization property of the contraction oscillation underlies the regulation of tactic movement in plasmodium.

Reaction-diffusion-advection model for pattern formation of rhythmic contraction in a giant amoeboid cell of the physarum plasmodium

The plasmodium of Physarum polycephalum is a large amoeboid organism showing rhythmic contraction everywhere within an organism, and moves by forming spatio-temporal patterns of the rhythmic contraction. We propose a reaction-diffusion-advection model for the pattern formation. This model is constructed under physiological suggestions that the chemical oscillator acts as a clock regulating the rhythmic contraction and interacts spatially not only by diffusion but also by advection of protoplasm. Behavior of the model is studied by numerical calculation, especially the effects of the advection term on a simple reaction-diffusion system. The advection effect reproduces experimentally observed phenomena of fluctuating propagation of the contraction wave. Concept of the reaction-diffusion-advection system is promising for modeling the mechanism of amoeboid behaviour in the Physarum plasmodium. Copyright 1999 Academic Press.

Large-scale preparation of human thrombin: polyethylene glycol potentiates the factor Xa-mediated activation of prothrombin

We investigated the ability of polyethylene glycol 4000 to accelerate thrombin generation in a mixture of prothrombin and factor X at concentrations of 1-30%. In the presence of 5 mM of CaCl2, polyethylene glycol 4000 promoted prothrombin activation at concentrations above 1%. The peak of activation was seen at levels of 14 and 20% of polyethylene glycol 4000. The effect of the polyethylene glycol was remarkably dependent on its molecular weight; molecular weights greater than 2000 were required for accelerating thrombin generation. Under optimal conditions, polyethylene glycol 4000, in the presence of CaCl2, promoted conversion of all of the prothrombin into thrombin and its derivatives. We conclude that polyethylene glycol 4000, at concentrations ranging from 14 to 20%, effectively accelerates thrombin generation in the presence of 5 mM of CaCl2. This new method for preparing thrombin is based on the use of polyethylene glycol 4000 and CaCl2 and is applicable to the manufacture of thrombin.

A kinetic analysis of the interaction of human recombinant tissue factor pathway inhibitor with factor Xa utilizing and immunoassay and the effect of antithrombin III/heparin on the complex formation

We have recently shown that a complex formation of tissue factor pathway inhibitor (TFPI) and factor Xa (Xa) promotes a clearance of proteoglycans-associated TFPI. In the current studies, the interaction between human recombinant TFPI (h-rTFPI) and Xa were kinetically analyzed by utilizing both a protease inhibitor, p-(amidophenyl) methanesulfonyl fluoride hydrochloride, and a specific enzyme-linked immunosorbent assay for the complex of h-rTFPI with Xa. We further investigated the effect of antithrombin III on the complex formation between h-rTFPI and Xa. We found that the h-rTFPI/Xa complex formed in a time-dependent manner: the second-order rate constant (K1) for the complex formation was calculated to be 0.86x10(6) M(-1)s(-1). The addition of antithrombin III to the h-rTFPI solution modestly reduced the rate of the complex formation between h-rTFPI and Xa. Heparin strikingly enhanced antithrombin III's inhibition of Xa and resulted in complete abrogation of the complex formation between h-rTFPI and Xa in the absence or presence of acidic phospholipids. Furthermore, antithrombin III induced dissociation of the preformed h-rTFPI/Xa complex in the presence of heparin. These results suggest that in the presence of heparin, antithrombin III interferes with the catabolism of TFPI mediated via Xa.

Activated protein C prevents LPS-induced pulmonary vascular injury by inhibiting cytokine production

We investigated the effect of activated protein C (APC) on pulmonary vascular injury and the increase in tumor necrosis factor (TNF) levels in lipopolysaccharide (LPS)-treated rats to determine whether APC reduces LPS-induced endothelial damage by inhibiting cytokine production. Intravenously administered LPS (5 mg/kg) induced pulmonary vascular injury, as indicated by an increase in the lung wet-to-dry weight ratio. LPS-induced pulmonary vascular injury was prevented by APC but not by active site-blocked factor Xa [dansyl glutamyl-glycyl-arginyl chloromethyl detone-treated activated factor X (DEGR-Xa)], a selective inhibitor of thrombin generation, or inactivated APC [diisopropyl fluorophosphate-treated APC (DIP-APC)]. APC, but not DEGR-Xa or DIP-APC, significantly inhibited the LPS-induced increase in the plasma level of TNF. APC significantly inhibited the production of TNF by LPS-stimulated monocytes in a dose-dependent fashion in vitro, but DIP-APC did not. APC did not inhibit the functions of activated neutrophils in vitro. These findings suggest that APC prevented LPS-induced pulmonary vascular injury by inhibiting TNF production by monocytes and not via its anticoagulant activity. The serine protease activity of APC appears to be essential for inhibition of TNF production.

Action spectrum for sporulation and photoavoidance in the plasmodium of Physarum polycephalum, as modified differentially by temperature and starvation

The plasmodium of the myxomycete Physarum polycephalum sporulates in bright natural environments, suggesting a relationship between photobehavior and sporulation. Thus, the action spectra for two light-dependent phenomena as well as the effects of other environmental conditions have been studied. Sporulation like photo-avoidance responded to UVC (near 270 nm) and near IR (near 750 nm) in addition to the well-documented UVA (near 350 nm) and blue (near 460 nm) regions. Sporulation and photoavoidance had similar sensitivities in the shorter wavelengths, while the former was about 100 times more sensitive in near IR. The plasmodium moved away from light in a wide spectral range. Starvation and high temperature at 31 degrees C (25 degrees C in standard conditions) reduced photoavoidance to UVA and to blue light, respectively. A high fluence rate of UVC suppressed the rhythmic contraction of the plasmodium, and the action spectrum peaked at 270 nm. These results indicate that the Physarum plasmodium may stay at brighter places not by positive phototaxis but by weakening the negative phototaxis to sunlight or by other possible taxes such as hydrotaxis. There may be at least four different photo-systems in the plasmodium.

Inhibitory potency of Erythrina variegata proteinase inhibitors toward serine proteinases in the blood coagulation and fibrinolytic systems

The Erythrina variegata Kunitz family trypsin inhibitors, ETIa and ETIb, prolonged the activated partial thromboplastin time (APTT) and also the prothrombin time (PT) of human plasma, but the Kunitz family chymotrypsin inhibitor, ECI, and Bowman-Birk family inhibitor, EBI, from E. variegata hardly prolonged these times. Trypsin inhibitors ETIa and ETIb inhibited the amidolytic activity of factor Xa, and ETIb but not ETIA inhibited plasma kallikrein. Neither ETIa nor ETIb exhibited any inhibitory activity toward beta-factor XIIa and thrombin. Furthermore, trypsin inhibitors ETIa and ETIb inhibited plasmin, a serine proteinase in the fibrinolytic system, whereas ECI and EBI did not. These results indicate that Erythrina Kunitz proteinase inhibitors possess different potency toward serine proteinases in the blood coagulation and fibrinolytic systems, in spite of their high similarity in amino acid sequence.

Species specificity of anticoagulant activity of activated human protein C: involvement of factor V as well as protein S

Activated protein C (APC) possesses species specificity in its anticoagulant activity. Human APC exerts only weak activity in rat plasma compared with that in human plasma. The present study was undertaken to estimate the difference in interaction of human and rat factors with human APC and to assess the cause of the species specificity. Human or rat protein S (PS), factor V, or factor VIII was used to supplement human plasma depleted of each respective factor, and the anticoagulant activity of human APC was measured in term of the elongation of activated partial thromboplastin time (APTT). The activity of human APC in rat PS- or factor V-supplemented plasma was weaker than that in the human PS- or factor V-supplemented plasma. Furthermore, using purified human and rat factor V, human APC showed weaker inactivation of rat factor V than human factor V. Equal anticoagulant activity was observed in human or rat factor VIII-supplemented plasma. And there was a little difference in the interaction of APC with its inhibitors in human or rat plasma during a few minutes of incubation as judged by measurement of residual activity by an enzyme capture assay. From these results factor V as well as PS seems to play a major role in the species specificity of APC.

Phase switching of oscillatory contraction in relation to the regulation of amoeboid behavior by the plasmodium of Physarum polycephalum

The plasmodium of the true slime mould Physarum polycephalum is a large aggregate of protoplasm and behaves like an amoeboid cell, exhibiting rhythmic contraction everywhere within the organism. Phase dynamics of these oscillations were studied in relation to the global organization of amoeboid behavior, by analysing the thickness oscillation, isotonic tension and the motive force of the streaming. Usually the plasmodium showed synchrony, the phase of the oscillation being the same everywhere excepting the peripheral part. We found several situations where this in-phase relationship switched to anti-phase. This occurred either at the early stages of the plasmodial coalescence, or when a single plasmodium was nearly separated by partition, or when the streaming of the protoplasm was hindered by applying the hydrostatic pressure. Furthermore, the motive force of the protoplasmic streaming increased once the anti-phase relationship was established. In this way, the weak interactions among plasmodial parts induce the switching of phase relationship from in-phase to anti-phase, and this transition in turn acts to increase the interaction by promoting a rapid mixing of the protoplasm. This global feedback mechanism by phase switching should help maintain a large single plasmodium without separating into parts. The possible mechanism of phase switching is discussed in terms of coupled nonlinear oscillators.

Activated protein C attenuates endotoxin-induced pulmonary vascular injury by inhibiting activated leukocytes in rats

We investigated the effect of activated protein C (APC) on lipopolysaccharide (LPS)-induced pulmonary vascular injury in rats to investigate the possible usefulness of APC as a treatment for adult respiratory distress syndrome. Intravenously administered LPS (5 mg/kg) significantly increased pulmonary vascular permeability. APC prevented the LPS-induced increase in pulmonary vascular permeability observed at 6 hours. Heparin plus antithrombin III (ATIII) and active site-blocked factor Xa (DEGR-Xa), a selective inhibitor of thrombin generation, inhibited LPS-induced coagulopathy but did not prevent LPS-induced pulmonary vascular injury. LPS-induced pulmonary vascular injury was significantly attenuated in rats with nitrogen mustard-induced leukocytopenia and in rats treated with ONO-5046, a potent granulocyte elastase inhibitor. Administration of LPS also increased pulmonary accumulation of leukocytes, as evaluated by measurement of myeloperoxidase activity in the lungs. APC significantly reduced LPS-induced increases in pulmonary accumulation of leukocytes at 1 hour. Neither ATIII plus heparin nor DEGR-Xa inhibited leukocyte accumulation. Active site-blocked APC (DIP-APC) prevented neither the LPS-induced pulmonary accumulation of leukocytes nor the LPS-induced increase in pulmonary vascular permeability. These results suggest that the mechanism of APC inhibition of LPS-induced pulmonary vascular injury was independent of its anticoagulant activity and was related to its ability to inhibit accumulation of leukocytes. In addition, these findings suggest that the serine protease activity of APC may be essential to its inhibitory effect on LPS-induced pulmonary accumulation of leukocytes and subsequent pulmonary vascular injury.

Characterization of the binding of factor Xa to fibrinogen/fibrin derivatives and localization of the factor Xa binding site on fibrinogen

The binding of human factor Xa to fibrinogen and its derivatives was characterized. Factor Xa bound to immobilized fibrin with a concentration at half-maximal binding (C50) of 100 nM. The 4-carboxyglutamic acid (Gla) domain of factor Xa is important in factor Xa binding to fibrin monomer, based on the following observations; the binding requires Ca2+; Gla-domain-lacking factor Xa could not bind to fibrin; factor Xa binding was significantly reduced by prior treatment of factor Xa with factor IX/factor-X-binding protein from the venom of Trimeresurus flavoviridis which specifically binds to the Gla domain of human factors IX and X. Factor Xa also bound to fibrinogen, fibrinogen degradation products (FDP)-D and FDP-E, with a similar affinity (C50 = 75-131 nM). In a solution-phase equilibrated binding assay, approximately 0.76 mol factor Xa bound to 1 mol fibrinogen with a dissociation constant of 180 nM. The binding of 125I-labeled factor Xa to the fibrin monomer was inhibited markedly by unlabeled factor Xa, but only slightly by thrombin, suggesting that the binding site of factor Xa on fibrin monomer differs from that of thrombin. We localized the binding site of factor Xa on fibrinogen: factor Xa bound strongly to the A alpha chain, but weakly to the B beta and gamma chains of fibrinogen. The A alpha chain was then digested with lysyl endopeptidase and separated by reverse-phase HPLC. Among resulting peptides, factor Xa bound specifically to a peptide corresponding to residues Asp82-Lys123 of the A alpha chain. This factor-Xa-binding site is located in the boundary between the central E domain and the terminal D domain of fibrinogen and is apparently distinct from the reported thrombin-binding site.

Alpha-2-macroglobulin as the major defence in acute pseudomonal septic shock in the guinea-pig model

An intravenous injection of 1.2 mg/kg of Pseudomonas aeruginosa elastase induces immediate lethal shock in guinea-pigs. In the present study, alpha-2-macroglobulin (alpha 2M) was shown to be the major factor in guinea-pig plasma that inhibits the enzymatic activity of elastase in vitro. Depletion of circulating alpha 2M by injecting anti-guinea-pig alpha 2M rabbit IgG F(ab')2 rendered the animals sensitive to a dose of elastase of 0.05 mg/kg. When the alpha 2M-depleted guinea-pigs were reconstituted with human alpha 2M, this sensitivity was reversed. Lethal shock did not occur in alpha 2M-depleted animals even at an elastase dose of 0.2 mg/kg when Hageman factor was simultaneously depleted, indicating that elastase induces shock through activation of the Hageman factor-dependent system. Similar results were obtained when the culture supernatants of an elastase-producing strain, IFO-3455, were used instead of the purified elastase, whereas no cardiovascular changes occurred, even in the alpha 2M-depleted guinea-pigs, when the culture supernatants were pretreated with an elastase specific inhibitor (zincov) or when the culture supernatants of an elastase non-producing strain, PA-103 were used.

The role of human factor X activation peptide in activation of factor X by factor IXa

We studied the interaction of factor X activation peptide (XAP) with factor IXa and factor Xa and the effect of XAP on factor IXa-catalyzed activation of factor X. XAP associated with factor Xa in the presence of 5 mM Ca2+ was dissociated from factor Xa by gel chromatography using Ultrogel AcA54 in 5 mM EDTA, or in 8 M urea-0.1% SDS. An exogenous isolated XAP inhibited the factor IXa-catalyzed factor X activation both in the presence and absence of factor VIIIa. 4-Amidinophenylmethylsulfonyl (aPMS)-factor Xa independent of XAP also inhibited the factor X activation more effectively than XAP alone in the presence of factor VIIIa. However, aPMS-factor Xa independent of XAP hardly inhibited the factor X activation in the absence of factor VIIIa. The binding of 125I-labeled factor X to the aPMS-factor IXa fixed to a microwell plate was inhibited by unlabeled factor X or XAP, but not by aPMS-factor Xa with or without XAP. Factor IXa directly bound to XAP and aPMS-factor Xa with XAP, but did not bind to aPMS-factor Xa without XAP. These findings suggest that the region of XAP in factor X directly interacts with factor IXa, and factor Xa region other than XAP interacts with factor VIIIa. Desialation or deletion of N-linked carbohydrates of XAP reduced the inhibitory activity of XAP for the factor X activation by factor IXa to approximately 50% of that of the intact XAP. This suggests that the sialic acids in the carbohydrate chains of the XAP region partly contribute to the interaction with factor IXa during its activation.

Non-specific activity of (+/-)-CP-96,345 in models of pain and inflammation

The non-peptide NK1 receptor antagonist, CP-96,345, and its 2R,3R enantiomer CP-96,344, which is not an NK1 receptor antagonist (IC50 > 10 microM), were evaluated for antinociceptive and anti-inflammatory activities in several classical models of pain and inflammation in the rat. Both CP-96,345 and CP-96,344 reduced carrageenin-induced paw oedema and hyperalgesia, and attenuated the second phase of formalin-induced paw licking with equal potency. These results indicate that NK1 antagonism is not responsible for the activity of (+/-)-CP-96,345 in the above animal models.

Tissue factor-dependent autoactivation of human blood coagulation factor VII

We recently showed that single-chain zymogen factor VII is converted to two-chain factor VIIa in an autocatalytic manner following complex formation with either cell-surface or solution-phase relipidated tissue factor apoprotein (Nakagaki, T., Foster, D. C., Berkner, K. L., and Kisiel, W. (1991) Biochemistry 30, 10819-10824). We have now performed a detailed kinetic analysis of the autoactivation of human plasma factor VII in the presence of relipidated recombinant tissue factor apoprotein and calcium. Incubation of factor VII with equimolar amounts of relipidated tissue factor apoprotein resulted in the formation of factor VIIa amidolytic activity coincident with the conversion of factor VII to factor VIIa. The time course for the generation of factor VIIa amidolytic activity in this system was sigmoidal, characterized by an initial lag phase followed by a rapid linear phase until activation was complete. The duration of the lag phase was decreased by the addition of exogenous recombinant factor VIIa. Relipidated tissue factor apoprotein was essential for factor VII autoactivation. No factor VII activation was observed following complex formation between factor VII and a recombinant soluble tissue factor apoprotein construct consisting of the aminoterminal extracellular domain in the presence or absence of phospholipids. Kinetic analyses revealed that factor VII activation in the presence of relipidated tissue factor apoprotein can be defined by a second-order reaction mechanism in which factor VII is activated by factor VIIa with an apparent second-order rate constant of 7.2 x 10(3) M-1 S-1. Benzamidine inhibited factor VII autoactivation with an apparent Ki of 1.8 mM, which is identical to the apparent Ki for the inhibition of factor VIIa amidolytic activity by this active site competitive inhibitor. Our data are consistent with a factor VII autoactivation mechanism in which trace amounts of factor VIIa rapidly activate tissue factor-bound factor VII by limited proteolysis.

The role of phospholipids and the factor VII Gla-domain in the interaction of factor VII with tissue factor

Whether or not the factor VII Gla-domain is involved in the high-affinity interaction of factor VII and tissue factor via calcium-dependent interactions with surrounding phospholipids is unknown. To investigate this, we have purified the factor VII Gla-peptide (FVII-GP) from digested recombinant human factor VIIa and assessed its effect on factor VII:tissue factor interactions. FVII-GP inhibited the activation of factor X by factor VIIa in the presence of either soluble or cell surface tissue factor half-maximally at 0.5 microM and 2.7 microM, respectively. However, FVII-GP failed to inhibit the specific binding of factor VIIa to cell-surface tissue factor, and did not inhibit the ability of tissue factor to stimulate the amidolytic activity of factor VIIa. Unrelipidated tissue factor apoprotein stimulated the amidolytic activity of factor VIIa to the same extent as relipidated tissue factor apoprotein. These findings suggest that the factor VII Gla-domain does not directly interact with tissue factor, but rather is important for calcium binding and concomitant expression of other factor VII epitopes necessary for tissue factor recognition and binding. To test this hypothesis, we have prepared a monoclonal antibody against a putative factor VII epitope that participates in the interaction of factor VII with cell-surface tissue factor (peptide 195-206) and assessed its ability to bind to factor VII in the presence and absence of calcium. Binding of this monoclonal antibody (PW-4) to intact factor VIIa was calcium-dependent and could be inhibited in a dose-dependent manner by peptide 195-206.(ABSTRACT TRUNCATED AT 250 WORDS)

Inactivation of factor Va by activated protein C on selected human tumor cell lines

Previous studies have demonstrated that platelets or aortic endothelial cells provide an appropriate surface that augments the proteolytic inactivation of factor Va by activated protein C (APC). We have examined the ability of three human tumor cell lines (HepG2, CAPAN-2 and J82) to support the inactivation of human factor Va by human APC in the presence and absence of human protein S. APC-mediated factor Va inactivation on these tumor cell lines was assessed by measuring the ability of residual cell-bound factor Va to augment the proteolytic activation of prothrombin by factor Xa. Each of the tumor cell lines studied supported factor Va inactivation by APC in the presence of calcium ions. HepG2 cell monolayers supported this reaction most effectively, with CAPAN-2 and J82 cell monolayers exhibiting moderate and weak effectiveness, respectively. Although not essential for this reaction, protein S moderately enhanced the rate of factor Va inactivation by APC on these tumor cell lines. In addition, pretreatment of each tumor cell line with rabbit antihuman protein S IgG had little, if any, effect on its ability to support factor Va inactivation by APC. Our data suggest that these, and perhaps other, tumor cells can provide an appropriate phospholipid surface for promoting factor Va binding and rapid inactivation by APC.