Role of the kallikrein-kinin system in human pancreatitis

Various factors in the kallikrein-kinin system were evaluated in acute and chronic pancreatitis. It was noted in particular that plasma trypsin and glandular kallikrein increased markedly in acute phase of pancreatitis and its correlation with amylase was observed. Plasma prekallikrein (PPK) decreased in acute pancreatitis, but increased in chronic pancreatitis. A negative correlation was noted between PPK and kallikrein like activity. Both HMW and LMW kininogen decreased in acute pancreatitis. It was presumed from these findings that the increase in kinin and its activation at the acute phase of pancreatitis might be due to kallikrein or trypsin originating from the pancreas.

Influence of CAPD and residual diuresis on the serum levels of alpha-1-microglobulin in end-stage renal disease

The chronic retention of proteins of low molecular weight (LMWP) seems to be connected with some unsolved problems of end-stage renal disease (e.g. reduced immune function, AB amyloidosis, hormonal imbalances), irrespective of the type of renal replacement therapy. Therefore, several recently discovered LMWPs such as alpha 1-microglobulin have to be evaluated concerning their contribution to the uremic syndrome. Although we observed a considerable daily loss of total protein into the CAPD dialysate, no differences were found in the removal of small proteins (MW less than 68 kilodaltons) when compared to conventional hemodialysis. Maintenance of renal function (residual diuresis greater than 100 ml/day) seems to be more potent keeping the serum concentrations of LMWP low than CAPD or hemodialysis.

Interactions in vitro and in vivo between anionic and cationic porcine trypsin and porcine plasma proteinase inhibitors

A method for purifying porcine anionic and cationic trypsin is presented. Reaction mixtures with increasing amounts of the two porcine trypsins and porcine serum were studied in vitro to evaluate the relative importance of alpha 1-macroglobulin and alpha 2-macroglobulin as well as alpha 1-proteinase inhibitor in the rapid binding of porcine anionic and cationic trypsin. Porcine cationic trypsin was preferentially bound to alpha 1-macroglobulin, while anionic trypsin exhibited equal binding to both alpha-macroglobulins. Both trypsins were also bound by the alpha 1-proteinase inhibitor but not until alpha 1-macroglobulin approached saturation. Trypsin-alpha-macroglobulin complexes were cleared from plasma with a half-life of 6 min. For trypsin-alpha 1-proteinase inhibitor-complexes the half-life was 120 min. These findings are in accordance with results for other mammalian species, including man.

Acute phase response of plasma proteins in analbuminemic rats

In healthy Nagase analbuminemic rats (NAR), the highest degree of relative increase in serum protein concentration was found for alpha-2-macroglobulin, the most prominent acute phase protein in rats. Its levels were about 30- and 60-fold higher in males and females, respectively, than those in the control Sprague-Dawley (SD) rats. In terms of absolute concentration, however, alpha-1-inhibitor 3 (also called alpha-X-protein or murinoglobulin) showed the most conspicuous change, its levels being higher by about 7 mg/ml than those in SD. When the acute phase reaction was induced by subcutaneous injection of turpentine, the levels of alpha-1- and alpha-2-macroglobulins, alpha-1-cysteine proteinase inhibitor, alpha-1-antiproteinase, and alpha-1-inhibitor 3 in NAR changed in essentially the same way as in SD: alpha-1-inhibitor 3 decreased markedly while the rest increased further. These results suggest that mechanisms responsible for the elevation of serum globulins in healthy NAR are not directly related to those involved in the acute phase response. On the other hand, the antithrombin III levels in healthy NAR were about twice the control values and changed little during the inflammation. In contrast, this protein in SD doubled during the acute phase, its maximal levels being close to those in healthy or inflamed NAR. This suggests that the antithrombin III level in healthy NAR is regulated by a mechanism similar to that in SD maximally reacting to the acute phase stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Inactivation of serine proteinase inhibitors (serpins) in human plasma by reactive oxidants

Activated polymorphonuclear neutrophils (PMN) and macrophages generate oxidizing agents similar to or identical with N-chloroamines. Mimicking this oxidation in normal human plasma by usage of chloramine T (CT), we observed an oxidant concentration-dependent inactivating effect on plasma alpha 2-plasmin inhibitor (alpha 2-PI), antithrombin III (AT III), and alpha 1-proteinase inhibitor (alpha 1-PI). 20-50 mumol CT/ml plasma are necessary for almost complete inactivation of alpha 2-PI and AT III-activity, i.e. about 2-5 times the dose necessary for inactivation of alpha 1-PI which has already been classified as "oxidant sensitive". The inactivation of alpha 1-PI, alpha 2-PI and AT III in plasma by oxidants is the result of a specific oxidative damage since C1-inhibitor, serine proteinases and complexes of plasmin and alpha 2-PI were chloramine resistant under the conditions used. According to our results, the amount of chloramines released by 1 x 10(6) activated PMN, namely ca. 10 nmol (see Weiss et al. Science 222 625-628, 1983) would be sufficient to destroy alpha 1-PI and alpha 2-PI activity of 1.5 and 0.4 microliter of human plasma, respectively. Consequently, activated leukocytes may be able to create a microenvironment in which elastase as well as plasmin and thrombin can display their proteolytic activity unchecked by their regulator proteins. Oxidation may provide a general basis for altering enzyme/inhibitor balances.

Relationship between ex vivo anti-proteinase (factor Xa and thrombin) assays and in vivo anticoagulant effect of very low molecular weight heparin, CY222

There is uncertainty as to which activities of unfractionated heparin (UFH) and low MW heparin are responsible for their anticoagulant and antithrombotic properties. We have sought to answer this question by examining plasma samples taken during a recently conducted dose-finding study of the low MW heparin, CY222, in haemodialysis for chronic renal failure. In this study, in vivo anticoagulant effect was assessed by measurement of plasma FPA levels. UFH was administered as a dose of 5000 iu bolus + 1,500 iu/h maintenance infusion, while the effects of three doses of CY222 were studied (10,000, 15,000 and 20,000 Institute Choay anti-factor Xa u bolus, all with 1,500 Institute Choay anti-factor Xa u/h maintenance infusion). Anti-factor Xa levels were determined by chromogenic substrate assay. Anti-thrombin levels were determined by chromogenic substrate assay and by quantitation of catalysed thrombin-inhibitor complexes (using autoradiography). Analysis of the results indicate that plasma fibrinopeptide A (FPA) levels correlate with anti-factor Xa (r = -0.45) and anti-thrombin (substrate) (r = -0.63) levels of UFH, but only with the anti-factor Xa levels (r = -0.41) of CY222. These results suggest that the anti-factor Xa assay is currently the most suitable assay for monitoring low MW heparins such as CY222 in humans.

[Human leukocyte elastase]

This article reviews some properties of human leucocyte elastase. This 30 kDa glycoprotein formed of 218 amino acid residues, is a serine proteinase which cleaves proteins at Val-X, Ala-X, Leu-X or Met-X bonds. Leucocyte elastase solubilizes fibrous elastin and also degrades other extracellular matrix proteins. It hydrolyses and inactivates a number of plasma proteins. Synthetic substrates are more convenient than elastin to measure elastase activity. A large number of natural and synthetic inhibitors of leucocyte elastase have been described. The former include alpha 1-proteinase inhibitor or alpha 1-antitrypsin, inter-alpha-inhibitor, alpha 2-macroglobulin, bronchial and cervical mucous inhibitor and a number of animal and plant proteins. Numerous synthetic inhibitors with therapeutic potentials have been designed. The efficiency of an inhibitor depends, among others, upon its rate of association with the enzyme and upon the stability of the enzyme-inhibitor complex. Elastase probably plays a physiological function in neutrophil migration, phagocytosis and tissue remodeling. It apparently plays a pathological role in pulmonary emphysema, rheumatoid arthritis, infections and inflammation. The pathogenic role of leucocyte elastase is best understood in emphysema.

[The state of the protease-inhibitor system in the bronchoalveolar lavage of patients with diffuse lung diseases]

Proteolytic and antiproteolytic activities were studied in bronchoalveolar lavages of 102 patients with sarcoidosis of respiratory tissues, exogenous allergic and idiopathic fibrotic alveolitis. Deficiency of the antiproteolytic activity was observed in all the impairments studied, whereas elastase-like and fibrinolytic activities were distinctly increased in sarcoidosis and exogenous allergic alveolitis. Impairments of bronchial mucose, pathogenic microflora, increase in content of neutrophils in respiratory tract as well as potential deficiency of the body inhibitory system were responsible for disbalance in the system proteinases-inhibitors of bronchoalveolar lavage. Biochemical examination of bronchoalveolar lavages enabled to find that clinico-roentgenological dynamics of these diseases correlated with the level of proteolytic activity.

Serum alpha 1-protease inhibitor in diabetes mellitus: reduced concentration and impaired activity

We investigated possible alterations in serum alpha 1-protease inhibitor (alpha 1-PI) concentration and activity from insulin-dependent diabetic subjects (IDDs) and in vitro in serum samples containing high glucose concentrations. The in vivo measurements were compared to others taken from normal reference subjects and the in vitro measurements were performed in serum samples containing 0, 10, 20, and 40 mmol/l of glucose. The diabetics had a significantly lower mean alpha 1-PI concentration in their serum than did the reference subjects (1.74 +/- 0.1 g/l vs. 2.1 +/- 0.1 g/l, P less than 0.05), as well as a lower total alpha 1-PI inhibitory activity (201 +/- 0.7 vs. 246.9 +/- 13.5 U/l, P less than 0.02). Addition of glucose to the serum samples in the in vitro study significantly reduced the mean alpha 1-PI concentrations (P less than 0.01 in the case of 10 mmol/l glucose, and P less than 0.001 in the cases of 20 and 40 mmol/l). Added glucose also significantly reduced the mean serum alpha 1-PI activity as determined by the percentage of elastase inhibition in 1, 2, and 3 microliters of reference serum (P less than 0.02 in the case of 10 mmol/l glucose, P less than 0.01 in 20 mmol/l, and P less than 0.001 in 40 mmol/l). Hyperglycaemia thus impaired serum alpha 1-PI concentration and activity both in vivo and in vitro. While the underlying mechanisms and clinical implications of these observations are unknown, the abnormally low alpha 1-PI activity in diabetics may worsen the severity and contribute to the chronicity of their infections.

Determination of leukocyte elastase-inhibitor complexes and leukocyte neutral proteinase inhibitor by enzyme immunoassays. Leukocyte elastase-inhibitor complexes in porcine blood, III

Sensitive enzyme immunoassays for the determination of total leukocyte neutral proteinase inhibitor and polymorphonuclear elastase-leukocyte neutral proteinase inhibitor complexes are described. The usable ranges of the standard curves were from 80 ng/l to 10 micrograms/l. The relative intra-assay coefficients of variation of the tests were between 2 and 4%, and the inter-assay coefficients of variation between 4 and 10%. In vitro and in vivo studies were performed with septic pigs and isolated leukocytes. The results show that leukocyte neutral proteinase inhibitor can be used in pigs as a parameter for the development of a septicaemia.

Immobilized pH gradients in ultrathin-layer (100 micron) gels: avoiding capillarity by a 'squeezing-sealing mold' technique

Several procedures for casting 100 microns ultrathin immobilized pH gradients are described. When acrylate/glass molding cassettes (Pascali et al., Electrophoresis 1987, 8, 371-373) are used two main problems are encountered: (i) a tendency of polymerization solutions, at the beginning of delivery, to spread across the glass surfaces with troublesome effects on the gradient stratification, and (ii) the raising of steep menisci at both extremities of the pH intervals, originating from capillarity phenomena and resulting in nonuniform gradients with bowed electrophoretic patterns. The first shortcoming was acceptably solved by increasing the density of sucrose gradients, and pouring them into prewarmed molding cassettes. The detrimental effect of menisci could be overcome by using a 'squeezing-sealing mold' technique. A molding cassette was endowed with a continuous, squared spacer frame, the upper side being open by inserting a wedged clip. A slight excess of polymerization solution was first dispensed into the cassette and squeezed away on removal of the clip. By completely excluding air from the molding cassette, uniform and well reproducible ultrathin gels could be cast. A major advantage of ultrathin immobilized pH gradient gels is the drastically shorter focusing time.

[Interaction of plasminogen activator of urokinase type with human serum]

Effects of blood serum on u-PA (EC 3.4.21.31) fibrinolytic activity were studied. After incubation for one hour at 37 degrees of the enzyme with human blood serum (55-145 IU/ml of blood serum) the enzymatic activity was completely inhibited. At the same time, amido-lytic activity of u-PA, estimated with low molecular substance S2444 as a substrate, was maintained in presence of blood serum. Blood serum inhibitors did not exhibit the specific affinity to u-PA. Serine proteases (trypsin, chymotrypsin and plasmin) competed with u-PA at equimolar concentrations. These inhibitors were inactivated after blood serum preincubation with primary amines methylamine, ethylamine, putrescine, spermidine and spermine (0.1-10 mM). The u-PA-inhibitor complexes were not dissociated in presence of 2.5 mM sodium dodecylsulfate. Trypsin-albumin copolymer bound specifically the blood serum u-PA inhibitors and the fraction adsorbed was electrophoretically characterized as a protein with molecular mass of 185 kDa.

Cystatin C: a new marker of biocompatibility or a good marker for the redistribution of LMW proteins during hemodialysis?

The mechanism(s) behind the larger relative increase of Plasma beta 2 microglobulin (P-beta 2m) than that of Plasma albumin (P-alb) during Cuprophan hemodialysis is disputed. To elucidate this phenomenon P-alb, P-beta 2m (MW 11,800) and Plasma cystatin (P-cC; MW 13,000) an inhibitor of cystein proteinases, were determined before and after a Cuprophan or polysulphone hemodialysis (4-7 hr, QB 200 ml/min) in 30 stable regular dialysis treatment (RDT) patients. Body weight (BW) decreased by 2.5 +/- 1.4% (mean +/- SD). P-alb, P-beta 2m and P-cC increased by 11.4 +/- 14.8%, 15.4 +/- 11.5%, and 22.1 +/- 14.3%, respectively, during Cuprophan dialysis. The relative increase of P-cC was larger than that of P-beta 2m (P less than 0.05) and that of P-alb (P less than 0.02). During polysulphone dialysis BW decreased by 4.1 +/- 1.8%. P-alb, P-beta 2m, and P-cC increased almost equally by 28.1 +/- 18, 26.5 +/- 19.2, and 26.8 +/- 14.4%, respectively. These results are hard to interpret. Is the increase in P-cC a new marker of biocompatibility or does it reflect the true shift of low molecular weight (LMW) proteins between the interstitial and the plasma volume during hemodialysis better than P-beta 2m? In vitro studies indicate that small amounts of both Serum beta 2m (S-beta 2m) and Serum cystatin C (S-cC) are adsorbed to or sieved through the Cuprophan membrane, findings which render the kinetics of LMW proteins during hemodialysis still more complex.

Protease inhibitors in liver disease

Measurements of the principal protease inhibitors were carried out in patients with two types of chronic liver disease: alcoholic cirrhosis and primary biliary cirrhosis. Measurement of the two major protease inhibitors operative in the haemostatic mechanism--that is, antithrombin III and alpha 2-antiplasmin--showed significantly reduced levels in the alcoholic cirrhosis group, who satisfied clinical and biochemical criteria of impaired hepatocellular function, but not in the primary biliary cirrhosis group, who had relatively good preservation of hepatocellular function. Significant correlation of levels of both these major protease inhibitors with the serum albumin concentration was also found. No evidence of disseminated intravascular coagulation was detected, and therefore failure of synthesis by the liver is the likely explanation of the low levels noted.

Proteases and antiproteases related to the coagulation system in plasma and ascites. Prediction of coagulation disorder in ascites retransfusion

To improve the ability to predict the occurrence of coagulation disorders in ascites retransfusion and, in addition, to better define the nature of the coagulation disorder, several proteases and antiproteases were analyzed in ascites and plasma before ascites retransfusion in 17 patients. Plasminogen, alpha 2-antiplasmin, antithrombin III, and fibrin(ogen) degradation products in ascites were significantly altered in patients who later developed abnormal coagulation as compared to those who did not. Only plasminogen and alpha 2-antiplasmin in ascites achieved a sufficient predictive value for the occurrence of coagulation abnormalities. The pattern of the coagulation abnormalities observed strongly suggests fibrinolysis induced by the infusion of plasminogen activators as the cause of the coagulation disorder in ascites retransfusion procedures.

Protection against cancer through nutritionally-induced increase of endogenous proteinase inhibitors--a hypothesis

Population groups with a diet low in calories, fat and animal protein, but high in vegetables and fibre, have a low incidence of cancer of the colon, rectum, breast and prostate. It is proposed that such a diet protects against cancer by stimulating an increase of endogenous proteinase inhibitors (PI), in particular, alpha 2-macroglobulin (AM), above those of individuals on a diet rich in calories, fat and animal protein. Evidence in support of this hypothesis is discussed. In various models, PI has been shown to be anticarcinogenistic. Preschool and school children who although on a diet apparently below the requirements for protein and calories were still considered healthy, have been found to have increased AM levels. Raised PI levels have also been observed in rats low on protein and energy and restriction of food intake in an inbred colony of rats reduced the incidence of radiation-induced tumours.

Serum protease inhibitors in opisthorchiasis, hepatoma, cholangiocarcinoma, and other liver diseases

Serum alpha 1-antitrypsin, alpha 1-antichymotrypsin and alpha 2-macroglobulin increased significantly in patients suffering from liver diseases: hepatoma, amoebic liver abscess, hepatitis, hepatic cirrhosis, cholangiocarcinoma, carcinoma of the head of pancreas including liver fluke infection (opisthorchiasis). Marked increase of alpha 1-antitrypsin and alpha 1-antichymotrypsin were found in cholangiocarcinoma, carcinoma of the head of pancreas, amoebic liver abscess, hepatic cirrhosis and hepatoma. alpha 2-macroglobulin increased markedly in hepatic cirrhosis. The concentrations of protease inhibitors found in opisthorchiasis were only moderately elevated.

The role of endothelium in factor Xa regulation: the effect of plasma proteinase inhibitors and hirudin

The role of endothelium in the inhibition of human factor Xa was studied in a plasma environment. Human factor Xa can bind to and function on bovine aortic endothelium in a manner similar to that of bovine factor Xa. Approximately 70% of the bound factor Xa is subject to inhibition by plasma proteinase inhibitors, and the remaining 30% is irreversibly bound as part of a 125 Kd membrane-associated complex not subject to proteolytic degradation. The proportion reversibly bound and its rate of release do not alter with changes in calcium, citrate, heparin, or active proteinase inhibitor concentrations. The principal plasma proteinase inhibitor of human factor Xa was antithrombin III, which accounted for 60% to 65% of factor Xa released from endothelium, with alpha 1-proteinase inhibitor inactivating 20% to 25% and alpha 2-macroglobulin approximately 15%. All of the reversibly bound factor Xa was identified in complex with one of these three proteinase inhibitors. The thrombin active-site inhibitor hirudin was found to markedly accelerate the displacement of reversibly bound factor Xa from the endothelium and to associate specifically with factor Xa without a loss of activity toward chromogenic substrates, perhaps accounting for a novel mechanism of anticoagulation.

Aspects of biocompatibility of two different dialysis membranes: cuprophane and polysulfone

Intradialytic hypoxemia, leukopenia and coagulation system activation were monitored in 9 uremic patients during hemodialysis with cuprophane (Cu) and polysulfone (Psf) membranes, using the following parameters: polymorphonuclear count (PMN), elastase alpha-1 proteinase inhibitor (EI-alpha 1PI) complex, platelet count, beta-thromboglobulin (BTG), fibronectin (FN) and arterial oxygen tension (PaO2). Our results indicate that 1) intradialytic hypoxemia observed with both membranes does not seem to be exclusively related to the well-known membrane-dependent leukopenia; 2) platelet activation, as demonstrated by the plasma BTG increase, appears to be an exclusive cellulosic membrane-related phenomenon; 3) at the same time platelet activation seems to be the major factor responsible for high FN levels, the highest FN levels occurring concurrently with the lowest platelet count.