New synthetic inhibitors of C1r, C1 esterase, thrombin, plasmin, kallikrein and trypsin

Therapeutic regimens in acute experimental hemorrhagic pancreatitis. Effects of hydration, oxygenation, peritoneal lavage, and a potent protease inhibitor

In this study we evaluated the effects of hydration, oxygenation, peritoneal lavage, and the protease inhibitor gabexate mesilate in acute hemorrhagic pancreatitis induced by feeding mice a choline-deficient, ethionine-supplemented diet. Different groups of mice were kept at various concentrations of O2 (21%, 35%, and 45% O2), or were treated by either s.c. injections or i.p. injections of electrolyte solution at various doses (0, 4, 6, or 8 ml/day). Further groups were treated either with i.p. lavage, lavage with 1.5 mg/ml of gabexate, or i.p. injections of 100 mg/kg of gabexate without lavage. The potential benefits of the various regimens were assessed by measuring survival, various biochemical and histologic features, and alterations in hematocrit, pH, and blood gases. Increasing O2 concentrations reversed hypoxemia and acidosis, but had no effect on biochemical or morphologic alterations and did not improve survival. However, hydration by s.c. fluid markedly improved survival and normalized the hematocrit without having major effects on biochemical or morphologic alterations. Intraperitoneal fluid did not improve survival. Gabexate injections without lavage had a slight effect on survival and serum amylase concentration and very little effect on histology. Lavage without gabexate had a greater effect on survival, serum amylase, and histology. Addition of gabexate to the lavage fluid increased the beneficial effect of lavage. Increases in amylase and activated trypsin in ascites were markedly reduced by lavage and even more so by lavage with addition of gabexate. We conclude that sufficient hydration appears to be an important factor in supportive care for severe acute pancreatitis, whereas oxygenation without sufficient hydration has no major benefit. Peritoneal lavage with gabexate showed the greatest benefit of the various regimens for acute severe pancreatitis and is worthy of clinical trials.

Inhibition of the accumulation of macrophages and the generation of macrophage chemotactic activity by dexamethasone in concanavalin A-induced peritonitis of mice

A delayed-type inflammatory response was evoked in mice using concanavalin A (Con A) as a stimulus, and the effect of various anti-inflammatory agents on the inflammation was examined. The intraperitoneal injection of Con A in the mouse resulted in the marked accumulation of leukocytes, especially macrophages, in the peritoneal cavity between 16 and 48 hr after the injection. Prior to the accumulation of macrophages, the chemotactic activity for macrophages appeared in the peritoneal fluid, and was associated with protein(s) in the molecular weight range from 10,000 to 100,000 daltons. When the effect of various agents on Con A-induced peritonitis was examined, neither anticomplementary agents (FUT-175 and K-76 COONa), bromophenacyl bromide, nordihydroguaiaretic acid nor indomethacin affected the generation of chemotactic activity and the accumulation of macrophages, suggesting that C5a, prostaglandins and leukotriene B4 are hardly involved in the Con A-induced macrophage accumulation. On the other hand, dexamethasone suppressed both the generation of chemotactic activity and the accumulation of macrophages. Taking into consideration the observation that the synthesis of macrophage chemotactic factors by mitogen-stimulated lymphocytes is inhibited by glucocorticoids, these results suggest that the macrophage chemotactic lymphokines might be involved in the accumulation of macrophages in Con A-induced peritonitis.

Adjustment of polyamine contents in Escherichia coli

Adjustment of polyamine contents in Escherichia coli was studied with strains of Escherichia coli producing normal (DR112) and excessive amounts of ornithine decarboxylase [DR112(pODC)] or S-adenosylmethionine decarboxylase [DR112(pSAMDC)]. Although DR112(pODC) produced approximately 70 times more ornithine decarboxylase than DR112 did, the amounts of polyamines in the cells of both strains did not change significantly. The amounts of polyamines in DR112(pODC) were adjusted by excretion of excessive amounts of putrescine to the medium. When ornithine was deficient in cells, polyamine contents in DR112(pODC) were much higher than those in DR112, although polyamine contents were low in both strains. This indicates that large amounts of ornithine decarboxylase increased the utilization of ornithine for putrescine synthesis. During ornithine deficiency, strain DR112 produced 3.4 times more ornithine decarboxylase. Strain DR112(pSAMDC) produced seven times more S-adenosylmethionine decarboxylase than DR112 did. In DR112(pSAMDC) an increase (40%) in spermidine content, a decrease (35%) in putrescine content, and no significant excretion of putrescine and spermidine were observed. The amount of ornithine decarboxylase in DR112(pSAMDC) was approximately 30% less than that in DR112. In addition, S-adenosylmethionine decarboxylase activity was strongly inhibited by spermidine. A possible regulatory mechanism to maintain polyamine contents in Escherichia coli is discussed based on the results.

Rosmarinic acid: a new inhibitor of complement C3-convertase with anti-inflammatory activity

Rosmarinic acid (RA) is a naturally occurring compound, isolated from Rosmarinus officinalis or Melissa officinalis which inhibits the in vitro immunohaemolysis of antibody-coated sheep erythrocytes by guinea pig serum. In further experiments this reduced immunohaemolysis was found to be due to inhibition of the C3-convertase of the classical complement pathway. The threshold concentration for inhibition of C3-convertase was 10(-6) mol/l. RA with an optimal inhibitory concentration between 5 and 10 mumol/l., resulting in about 70% inhibition of haemolysis. However, higher concentrations of RA were less effective at inhibiting C3-convertase. The inhibition may not be specific for C3-convertase, since another serine protease, elastase, was also weakly inhibited by RA in vitro. RA also exhibited inhibitory activity in three in vivo models in which complement activation plays a role. Thus, RA (0.316-3.16 mg/kg i.m.) reduced paw oedema induced by cobra venom factor (CVF) in the rat, and at 1-100 mg/kg p.o. inhibited passive cutaneous anaphylaxis in the rat. In addition, at 10 mg/kg i.m. RA impaired in vivo activation by heat-killed Corynebacterium parvum (i.p.) of mouse macrophages, as measured by the decreased capacity of the activated macrophages to undergo the oxidative burst. RA (0.1-10 mg/kg i.m.) did not inhibit t-butyl hydroperoxide-induced paw oedema in the rat, indicating selectivity for complement-dependent processes.

Nonspecific inhibition of Escherichia coli ornithine decarboxylase by various ribosomal proteins: detection of a new ribosomal protein possessing strong antizyme activity

Escherichia coli ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) was found to be inhibited by several basic proteins. When ribosomal proteins were tested, major ribosomal proteins, with the exceptions of S1, S5, S6, S8, S10, L3, L5, L6, L7/L12, L8, L9 and L10 proteins, showed antizyme activity in addition to the recognized antizymes (S20/L26 and L34 proteins). Furthermore, it was found that L20 protein and a new ribosomal protein, tentatively named X1 protein and bound to 50 S ribosomal subunits, showed stronger antizyme activity than S20/L26 and L34 proteins. The antizyme activity of S20/L26 and L34 proteins was at most 10% of the total antizyme activity of ribosomal proteins. Several basic polypeptides also showed antizyme activity in the order polyarginine greater than protamine greater than histone greater than polylysine. Ribosomal proteins and basic polypeptides inhibited ornithine decarboxylase activity competitively. Ribosome-bound antizymes were inactive as antizymes, and antizyme inhibition of ornithine decarboxylase was eliminated by ribosomes. When E. coli extracts were separated into ribosomes and 100,000 X g supernatant fraction, no significant antizyme activity was observed in the supernatant fraction. Results of these in vitro experiments infer that basic antizymes may not function as inhibitors of ornithine decarboxylase in vivo.

Inhibitory effects of FUT-175, a new synthetic protease inhibitor, on intravascular hemolysis by human serum in mice

Effects of FUT-175, a new protease inhibitor, on intravascular hemolysis of mouse erythrocytes caused by intravenous injection of human serum was studied in mice. In in vitro experiments, unsensitized erythrocytes obtained from various species of animals were lysed with sera in EGTA-GVB-Mg++. After heat inactivation of sera at 50 degrees C for 30 min, hemolysis in EGTA-GVB-Mg++ was abolished, indicating loss of activity of the alternative complement pathway. FUT-175 inhibited the alternative complement pathway-mediated hemolysis with IC50 values of 1.3 X 10(-7) to 4.0 X 10(-7) M. Intravenous injection of human serum caused intravascular hemolysis of mouse erythrocytes in mice. No remarkable change was observed in the mice that were injected with heat-inactivated (56 degrees C, 30 min) human serum. Intravenous administration of FUT-175 at a dose of 3 or 10 mg/kg inhibited intravascular hemolysis of mouse erythrocytes regardless of whether it was administered before or after injection of human serum. These results indicated that FUT-175 prevents intravascular hemolysis of mouse erythrocytes through the inhibitory effect of both alternative and classical complement pathway.

Pharmacological studies of FUT-175, nafamostat mesilate. V. Effects on the pancreatic enzymes and experimental acute pancreatitis in rats

Effects of FUT-175 on the pancreatic enzymes in vitro and in vivo in the enterokinase-induced experimental acute pancreatitis were investigated, and they were compared with those of gabexate and aprotinin. In in vitro experiments, FUT-175 inhibited the pancreatic protease activities 10 to 100 times more potently than gabexate. Furthermore, FUT-175 inhibited the enterokinase activity. Unlike aprotinin, FUT-175 inhibited alpha 2-macroglobulin bound trypsin activity as well as free trypsin. In in vivo experiments, at doses of 0.5-50 micrograms/kg/min, FUT-175 suppressed the elevated protease activities in the experimental acute pancreatitis more potently than gabexate. Differently from the action of aprotinin, FUT-175 suppressed trypsin activities both in the pancreas and in the plasma to the same extent. Furthermore, FUT-175 reduced the mortality of rats in the experimental acute pancreatitis in a dose-dependent manner. These data strongly support that FUT-175 is clinically useful in the therapy of acute pancreatitis.

Studies on the effects of primary therapy for DIC following circulatory arrest

Comparative studies in early treatment for DIC caused by circulatory arrest were carried out on three groups of dogs during 300 min from the recovery of circulatory arrest: a heparin group, a FOY (gabexate mesilate) group, and a FUT-175 (nafamostat mesilate) group. The parameters employed were platelet count, prothrombin time (PT), activated partial prothrombin time (APTT), fibrinogen, antithrombin-III (AT-III), and fibrin or fibrinogen degradation products (FDP). In the heparin group, there was less of a drop in the platelet count and the level of AT-III than in the control group, but the FDP levels were the same as in the control group. The PT and APTT remained within normal limits in the FOY group and no decrease was observed in either platelet count or AT-III levels. In addition, FDP levels were kept within normal limits. In the FUT-175 group, prolongation of APTT, no decline in the platelet count and AT-III levels, and normal levels of FDP were observed. The results of these experiments indicate the importance of early treatment for DIC. Judging from the parameters, better results were obtained in the FOY and FUT-175 group than in the heparin group.

Proteolytic response to nutritional step-down in Tetrahymena

The ciliate Tetrahymena thermophila is usually grown in a medium containing proteose peptone and yeast extract as organic nutrients. When the ciliate is transferred to step-down conditions, i.e., an inorganic medium, it is shown that the cells respond by rapidly and drastically increasing their rate of protein degradation. A method for measuring the response to step-down conditions is presented, and the response is characterized. The types of proteinases involved are indicated by the use of specific inhibitors. It is concluded that Tetrahymena reacts in much the same way as mammalian cells, and provides a suitable system for investigating the regulation of protein degradation.

Detection of intermediary Clr with complete active site, using a synthetic proteinase inhibitor

The synthetic proteinase inhibitor, FUT-175 (6-amidino-2-naphthyl-4-guanidinobenzoate), strongly suppressed activation of Clr at 37 degrees C, causing 50% inhibition at 0.03 mM. To clarify whether the inhibitor was incorporated into the active site of intermediary Clr formed during the incubation, determination of the active site was tried using this inhibitor. Consequently, release of amidinonaphthol equimolar with the amount of Clr used was observed in the early period of incubation, in which the activation to Clr- was about 5%. These results indicate that intermediary Clr already has a complete active site.

Pharmacological studies of FUT-175, nafamstat mesilate. I. Inhibition of protease activity in in vitro and in vivo experiments

FUT-175, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfonate (nafamstat mesilate), a novel synthetic protease-inhibiting agent, was studied to determine its in vitro effects against various proteases and other enzymes, as well as to determine its in vivo protease inhibitory effects. FUT-175 was found to inhibit, in an intense, specific and reversible way, the enzyme activities of trypsin, C1r, C1s, thrombin, kallikrein and plasmin with IC50 values of the order of 10(-6)-10(-8) M. FUT-175 also inhibited complement-mediated hemolysis, including both classical and alternative pathways, sites of inhibition being on C1r and C1s as evidenced by the intermediate-cell technique. In animal model reactions in which the complement system is known to be involved as pathogenetic factors, e.g., Forssman shock, Forssman cutaneous vasculitis, zymosan-induced paw edema, endotoxin shock and local Shwartzman reaction, FUT-175 was highly effective in that, for example, intravenous dosing at 3 mg/kg could completely protect guinea pigs from the lethal Forssman shock. FUT-175 was also found to be effective in trypsin-induced shock in mice, in lethality due to thrombin-thrombosis in mice and in kinin formation in the inflammatory process in rats.

The effect of 6-amidino-2-naphtyl-4-guanidinobenzoate dimethane sulfonate (FUT-175) on experimental glomerulonephritis in mice

Effect of 6-amidino-2-naphtyl-4-guanidinobenzoate dimethane sulfonate (FUT-175) on experimental glomerulonephritis in mice was studied. Employed models are nephrotoxic serum (NTS) nephritis in ddY or A/He mice, rabbit IgG (RGG) accelerated NTS nephritis in ddY mice and spontaneous nephritis in (NZB x NZW) F1 mice. The severity of nephritis was evaluated by measuring proteinuria and serological parameters and examining renal tissue by light microscopy. Therapy with FUT-175 clearly prevented the pathological changes of proteinuria and serological parameters in all four nephritis models. By contrast, treatment hardly affected histopathological changes of the kidney in any of the models. Cyclophosphamide used as a comparative drug showed more clearly remission of the onset and development of NTS nephritis and RGG accelerated NTS nephritis in ddY mice by means of the changes of urinary and selorogical parameters. These evidences suggest that FUT-175 shows beneficial effects on the nephritis in either normal or complement deficient mice.