In silico analysis shows that dynamic changes in curvature guide cell migration over long distances

In vitro experiments have shown that cell scale curvatures influence cell migration; cells avoid convex hills and settle in concave valleys. However, it is not known whether dynamic changes in curvature can guide cell migration. This study extends a previous in-silico model to explore the effects over time of changing the substrate curvature on cell migration guidance. By simulating a dynamic surface curvature using traveling wave patterns, we investigate the influence of wave height and speed, and find that long-distance cell migration guidance can be achieved on specific wave patterns. We propose a mechanistic explanation of what we call dynamic curvotaxis and highlight those cellular features that may be involved. Our results open a new area of study for understanding cell mobility in dynamic environments, from single-cell in vitro experiments to multi-cellular in vivo mechanisms.

Delayed Elimination of Fibrin from the Lungs in Rats Given α2-Antiplasmin

Injection of human α2–antiplasmin resulted in delayed elimination of fibrin from the lungs in rats with thrombin–induced intravascular coagulation. The amount of α2–antiplasmin injected was chosen so as to simulate the posttraumatic increase of this inhibitor in man. By injecting trace amounts only of radiolabelled α2–antiplasmin a specific uptake of this protein in the lungs was noted after the thrombin-induced coagulation. The results may indicate that the posttraumatic increase in α2–antiplasmin is of significance for the delayed elimination of fibrin seen in patients following trauma.

An approach to the in vitro evaluation of potential for cytochrome P450 enzyme inhibition from herbals and other natural remedies

Herbals and other natural remedies could affect the disposition of conventional pharmaceuticals through inhibition of human cytochrome P-450 (CYP) enzymes. We have developed an approach to the problem of determining a critical potential for CYP enzyme inhibition by commercial herbal remedies etcetera using standardised extraction procedures in combination with commercially available human CYP enzyme 3A4, 2D6 and 2C19 inhibition assays. We present a survey of commercially available natural remedies on the local market using this approach together with a discussion on how to decide when further in vivo interaction studies may be warranted. We confirmed earlier findings on Hypericum (St. John's wort) and Echinacea purpurea activities, and report that extracts of Valeriana as well as a fish oil preparation were potent inhibitors of all tested enzymes. As a first estimate to assess the relevance of in vitro findings, we have chosen to express the inhibitory potency as the volume that the extractable inhibitory activity for a recommended human dose could be diluted into to yield a half-maximal inhibition--litres per dose unit. We propose that preparations for which this measure approaches four litres/dose unit, i.e. corresponding to the human blood volume, should be investigated further for potential enzyme interaction with pharmaceuticals.

Cytokine-induced tendinitis: a preliminary study in rabbits

This study was designed to determine the effects of a single injection of a species-specific preparation of cytokines into rabbit patellar tendons and to compare the results with a known model of tendinitis, the collagenase-injection model. New Zealand White rabbits were divided into two groups and two time periods (4 and 16 weeks) and injected in the midsubstance of the right patellar tendon with either cytokines or collagenase under ultrasound guidance to confirm intratendinous needle placement. The left patellar tendon was injected with 0.025 ml of saline solution and served as a control. The rabbits were returned to cage activity after injection. At death, two rabbits in each group underwent histological analysis; the remaining eight animals in each time frame were evaluated biomechanically and then biochemically with use of the patella/whole patellar tendon/tibia complex. Histologic results at 4 weeks in the tendons injected with cytokines demonstrated increased cellularity, which was resolving by 16 weeks. The matrix appeared unchanged. The tendons injected with collagenase demonstrated increased angiogenesis of the matrix, hypercellularity, and fibrosis around the tendon at 4 weeks. At 16 weeks, myxoid changes, focal fibrosis, and collagen-bundle disarray with persistent increase in cellularity were noted. Biomechanically, a significant decrease in ultimate load at 16 weeks was seen in the tendons injected with cytokines but no change was seen in cross-sectional area. The tendons injected with collagenase demonstrated a significant increase in cross-sectional area at 4 and 16 weeks compared with those injected with cytokines. Biochemically, there was no significant difference in collagen content between the two groups at 4 or 16 weeks but the tendons injected with collagenase demonstrated a significant increase in crosslinking at 16 weeks. Our conclusion is that the tendons injected with the cytokine preparation represent a model of mild, seemingly reversible tendon injury. The cytokine preparation produces no matrix damage or evidence of collagen degradation and is species specific.

Methotrexate and sulfasalazine promote adenosine release by a mechanism that requires ecto-5'-nucleotidase-mediated conversion of adenine nucleotides

We and others have shown that an increased extracellular concentration of adenosine mediates the antiinflammatory effects of methotrexate and sulfasalazine both in vitro and in vivo, but the mechanism by which these drugs increase extracellular adenosine remains unclear. The results of the experiments reported here provide three distinct lines of evidence that adenosine results from the ecto-5'-nucleotidase- mediated conversion of adenine nucleotides to adenosine. First, pretreatment of a human microvascular endothelial cell line (HMEC-1) with methotrexate increases extracellular adenosine after exposure of the pretreated cells to activated neutrophils; the ecto-5'-nucleotidase inhibitor alpha, beta-methylene adenosine-5'-diphosphate (APCP) abrogates completely the increase in extracellular adenosine. Second, there is no methotrexate-mediated increase in extracellular adenosine concentration in the supernate of cells deficient in ecto-5'-nucleotidase, but there is a marked increase in extracellular adenosine concentration in the supernates of these cells after transfection and surface expression of the enzyme. Finally, as we have shown previously, adenosine mediates the antiinflammatory effects of methotrexate and sulfasalazine in the murine air pouch model of inflammation, and injection of APCP, the ecto-5'-nucleotidase inhibitor, abrogates completely the increase in adenosine and the decrement in inflammation in this in vivo model. These results not only show that ecto-5'-nucleotidase activity is a critical mediator of methotrexate- and sulfasalazine-induced antiinflammatory activity in vitro and in vivo but also indicate that adenine nucleotides, released from cells, are the source of extracellular adenosine.

The anti-inflammatory mechanism of sulfasalazine is related to adenosine release at inflamed sites

The anti-inflammatory mechanism of sulfasalazine is not well understood. It has recently been shown that sulfasalazine inhibits 5-aminoimidazole-4-carboxamidoribonucleotide (AICAR) transformylase, an enzyme involved in de novo purine biosynthesis. We recently demonstrated that methotrexate promotes intracellular AICAR accumulation, thereby increasing adenosine release and diminishing inflammation, so we tested the hypothesis that sulfasalazine similarly promotes intracellular AICAR accumulation. We studied adenosine release and the state of inflammation in in vitro and in vivo models of the inflammatory process. The adhesion of stimulated neutrophils (FMLP) to endothelial cells preincubated with sulfasalazine was inhibited in a dose-dependent manner. Elimination of extracellular adenosine by addition of adenosine deaminase or inhibition of adenosine by the adenosine A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX) completely reversed the anti-inflammatory effect of sulfasalazine (at concentrations <1 microM in this in vitro model. To determine whether this phenomenon was relevant to inhibition of inflammation in vivo, we studied the effect of sulfasalazine (100 mg/kg/day by gastric gavage for 3 days) on leukocyte accumulation in the murine air pouch model of inflammation. Treatment with sulfasalazine markedly decreased the number of leukocytes that accumulated in the inflamed (carrageenan, 2 mg/ml) air pouch. Injection of either adenosine deaminase or DMPX, but not the A1 receptor antagonist 8-cyclopentyl-dipropylxanthine, significantly reversed the anti-inflammatory effects of sulfasalazine treatment. Sulfasalazine increased the exudate adenosine concentration from 127 +/- 64 nM to 869 +/- 47 nM. Moreover, sulfasalazine treatment promoted a marked increase in splenocyte AICAR concentration from 35 +/- 6 to 96 +/- 3 pmols/10(6) splenocytes, which is consistent with the in vitro observation that sulfasalazine inhibits AICAR transformylase. These results indicate that sulfasalazine, like methotrexate, enhances adenosine release at an inflamed site and that adenosine diminishes inflammation via occupancy of A2 receptors on inflammatory cells. Our studies provide evidence that sulfasalazine and methotrexate may be described as a newly recognized family of anti-inflammatory agents that share the property of using adenosine as an antagonist of inflammation.

The anti-inflammatory mechanism of sulfasalazine is related to adenosine release at inflamed sites

The anti-inflammatory mechanism of sulfasalazine is not well understood. It has recently been shown that sulfasalazine inhibits 5-aminoimidazole-4-carboxamidoribonucleotide (AICAR) transformylase, an enzyme involved in de novo purine biosynthesis. We recently demonstrated that methotrexate promotes intracellular AICAR accumulation, thereby increasing adenosine release and diminishing inflammation, so we tested the hypothesis that sulfasalazine similarly promotes intracellular AICAR accumulation. We studied adenosine release and the state of inflammation in in vitro and in vivo models of the inflammatory process. The adhesion of stimulated neutrophils (FMLP) to endothelial cells preincubated with sulfasalazine was inhibited in a dose-dependent manner. Elimination of extracellular adenosine by addition of adenosine deaminase or inhibition of adenosine by the adenosine A2 receptor antagonist 3,7-dimethyl-1-propargylxanthine (DMPX) completely reversed the anti-inflammatory effect of sulfasalazine (at concentrations <1 microM in this in vitro model. To determine whether this phenomenon was relevant to inhibition of inflammation in vivo, we studied the effect of sulfasalazine (100 mg/kg/day by gastric gavage for 3 days) on leukocyte accumulation in the murine air pouch model of inflammation. Treatment with sulfasalazine markedly decreased the number of leukocytes that accumulated in the inflamed (carrageenan, 2 mg/ml) air pouch. Injection of either adenosine deaminase or DMPX, but not the A1 receptor antagonist 8-cyclopentyl-dipropylxanthine, significantly reversed the anti-inflammatory effects of sulfasalazine treatment. Sulfasalazine increased the exudate adenosine concentration from 127 +/- 64 nM to 869 +/- 47 nM. Moreover, sulfasalazine treatment promoted a marked increase in splenocyte AICAR concentration from 35 +/- 6 to 96 +/- 3 pmols/10(6) splenocytes, which is consistent with the in vitro observation that sulfasalazine inhibits AICAR transformylase. These results indicate that sulfasalazine, like methotrexate, enhances adenosine release at an inflamed site and that adenosine diminishes inflammation via occupancy of A2 receptors on inflammatory cells. Our studies provide evidence that sulfasalazine and methotrexate may be described as a newly recognized family of anti-inflammatory agents that share the property of using adenosine as an antagonist of inflammation.

Sulphasalazine inhibition of human granulocyte activation by inhibition of second messenger compounds

The effects of sulphasalazine on the production of second messenger compounds in human granulocytes have been characterised by various stimuli. The increases in cytosolic calcium, inositol trisphosphate, diacylglycerol, and phosphatidic acid (all important mediators of intracellular signal transduction) triggered by stimulation were inhibited by sulphasalazine. The metabolites 5-amino-salicylic acid and sulphapyridine were less potent inhibitors than the mother compound. It is concluded that sulphasalazine inhibits the synthesis of phosphoinositide derived second messenger compounds at the level of phospholipase C or its regulatory guanosine 5'-triphosphate (GTP) binding protein. Inhibition of phosphatidic acid synthesis was either due to the same mechanism, or to interaction with a phospholipase D regulating GTP binding protein.

Spermine: an anti-oxidant and anti-inflammatory agent

This work demonstrates that spermine is a natural antioxidant and anti-inflammatory agent. It is found that: (1) Spermine inhibits the cytochrome C reduction initiated by FMLP- or PMA-stimulated human granulocytes. (2) Spermine inhibits the Fe(III)/xanthine oxidase stimulated lipid peroxidation of brain phospholipid liposomes. The antioxidative effect disappears at high Fe(III) concentrations. (3) Spermine forms a complex with Fe(II). (4) Spermine inhibits the Fe(II)-induced depolymerization of hyaluronic acid, and EDTA abolishes this effect. (5) Spermine or spermine-Fe(II) has no superoxide mimetic effect. These findings suggest that spermine has at least two antioxidative mechanisms of action: (I) Spermine inhibits the generation of the transport of superoxide radicals from stimulated granulocytes, and (II) Spermine inhibits the Haber-Weiss reaction by forming an unreactive chelate with Fe. Spermine thus prevents generation of destructive hydroxyl radicals.

The hydroxylamine OXANOH and its reaction product, the nitroxide OXANO., act as complementary inhibitors of lipid peroxidation

The effects of the nitroxide 2-ethyl-2,5,5-trimethyl-3-oxazolidinoxyl (OXANO.) and the corresponding hydroxylamine 2-ethyl-1-hydroxy-2,5,5-trimethyl-3-oxazolidine (OXANOH) on in vitro lipid peroxidation in rat liver microsomes and reconstituted lipid vesicles were investigated, and compared with those of some commonly used spin trapping agents. OXANO. and OXANOH (10-100 microM) inhibited iron-dependent lipid peroxidation, as did the spin trapping agents (10-100 mM). OXANO. mainly inhibited the rate of peroxidation, but caused only a small delay in the time of onset. OXANOH exerted its effect by delaying the onset of peroxidation in an antioxidant fashion, and also by inhibiting the rate. Higher concentrations of both substances were required to inhibit t-butylhydroperoxide-dependent lipid peroxidation. OXANO. was found to oxidize the ferrous-ADP complex required for initiation of peroxidation, and this is probably the basis of the inhibitory effect of this compound. Since the reaction of OXANO. tends to produce OXANOH and vice versa, either one could inhibit all reactions of lipid peroxidation.

[Infections caused by central venous catheter used in surgery]

The central venous catheters, now usually adopted in surgical patients, present some potential septic risks, and the longer the catheter is in place, the more dangerous it is. The authors report their experience on 130 central venous catheters, out of which 96 were used for TPN administration and 34 for monitoring purposes. The catheters were introduced through subclavian, internal jugular or basilic veins, in accordance with a standardized technique. The observed infection percentage, caused by the catheters, was 7.7%; the infection was easily controlled by the catheter removal and a proper antibiotic therapy. The only death, surely due to sepsis, was caused by Candida fungus in an immunosuppressed female patient. Therefore the authors stress the importance to prevent septic complications in order to avoid fatal ones.

Inhibitory effects of sulfasalazine and related compounds on superoxide production by human polymorphonuclear leukocytes

The inhibitory effects of sulfasalazine, some sulfasalazine-related compounds and indomethacin on superoxide production by human polymorphonuclear (PMN) leukocytes were studied. The inhibition of the chemotactic peptide (FMLP)-induced superoxide production, which is membrane receptor-mediated, was strongly dependent on the concentration both of the secretory stimulus and of the test compounds, indicating an interaction between the receptor and the test compound. Furthermore, a positive correlation was found between the lipophilicity of the compound and the degree of inhibition. However, when the receptor was by-passed by direct activation of the receptor-linked G protein by the use of fluoride ions as secretory stimuli, the test compounds still inhibited superoxide production. On the other hand, superoxide production by cells stimulated with phorbol ester was not inhibited by the test compounds. Furthermore, the production of phosphatidic acid was decreased in the presence of sulfasalazine, indicating impaired phosphoinositide metabolism. The inhibition of this metabolism was not due to increased intracellular concentrations of cyclic AMP, although sulfasalazine did inhibit cyclic nucleotide phosphodiesterase. We conclude that sulfasalazine attenuates superoxide production by PMN leukocytes at a post-receptor site of action at a step before the activation of protein kinase C, possibly by interfering with the phosphoinositide metabolism but independent of cyclic AMP.

Inhibition of lipid peroxidation by spin labels. Relationships between structure and function

Inhibition of lipid peroxidation by nitroxide radicals and their corresponding hydroxylamines was investigated. The nitroxides were either oxazolidines or piperidines, differing in substitution of the backbone of the molecule (a five or six-membered ring structure, respectively). Concentration requirements for 50% inhibition of microsomal lipid peroxidation varied from 340 to 6 microM for the nitroxides, and from 120 to 3 microM for the hydroxylamines, correlating with lipophilicity and chemical structure. Intramembrane concentrations required for 50% inhibition was independent of lipophilicity when peroxidation was initiated with ADP-Fe2+ but increased with lipophilicity when peroxidation was initiated with t-butylhydroperoxide. During studies of the kinetics of the inhibition, two modes were seen: a delay or a decreased rate of the process. The former mode was seen with the more lipophilic inhibitors. The mechanism of inhibition was similar for all nitroxides and consisted of the following three major components: blocking of primary initiation, prevention of secondary (peroxide-dependent) initiation, and scavenging of various lipoid radicals in the membrane, the major mode of action of the hydroxylamines. Inhibitory efficiency was interpreted in terms of steric hindrance, diffusibility, regeneration of inhibitor, and ability to interact with hydrophilic sites in a hydrophobic environment.

Genetically engineered polymers of human CuZn superoxide dismutase. Biochemistry and serum half-lives

CuZn superoxide dismutase is a highly stable dimer of identical subunits with a combined molecular mass of 32,000 daltons. Two human superoxide dismutase genes have been joined in the same translational reading frame, using spacers of different lengths, to encode single chain proteins consisting of two identical human superoxide dismutase subunits. The first construct encodes two directly linked subunits; the terminal glutamine codon of the first gene was changed to a methionine codon and followed immediately by the second gene. The second construct encodes two subunits linked by a 19-amino-acid human immunoglobulin IgA1 hinge sequence. Both constructs produce high levels of catalytically active superoxide dismutase when expressed in Escherichia coli. The protein containing the IgA1 hinge sequence forms polymers up to 750,000 in molecular weight, which are linked together noncovalently by the hydrophobic bonding of the dimer interface. The polymers are soluble, thermostable, and of near normal specific activity. Site-directed in vitro mutagenesis was used to inactivate one of the two human superoxide dismutase subunits. The resulting human superoxide dismutase polymers have approximately 50% activity, thus confirming that the products of both genes are catalytically active. Large amounts of individual polymeric forms have been purified from recombinant yeast and tested for serum stability in rats. The serum half-life is approximately 7 min for both the two-chain wild type human superoxide dismutase dimer (Mr 32,000) and the single chain molecule consisting of a human superoxide dismutase dimer covalently linked by the immunoglobulin hinge region (Mr 34,000), whereas the higher molecular weight polymers (Mr greater than or equal to 68,000) all have half-lives of approximately 145 min.

Studies on biosynthesis of alpha 2-antiplasmin in rat liver cells

Biosynthesis, intracellular processing and secretion of alpha 2-antiplasmin (AP) were studied in primary cultures of rat hepatocytes by the pulse-chase technique. The experiments demonstrated that AP is present intracellularly as a 73 kD form and is secreted as a 79 kD form with affinity for human plasminogen kringles. Addition of human plasmin to the culture medium resulted in the formation of a 141 kD protein, probably a plasmin-AP complex, concomitantly with the disappearance of the 79 kD protein. The presence of tunicamycin, a blocker of N-linked glycosylation in the endoplasmic reticulum, during culture resulted in expression of a 63 kD form in medium and cell lysates. This latter form was unchanged after reduction and displayed affinity for human plasminogen kringles. The 79 kD form in the culture medium was resistant to treatment with endo-beta-N-acetylglucosaminidase-H while the intracellular 73 kD form was degraded to 63 kD, indicating glycosylation in the Golgi complex. It is concluded that rat AP is synthesized in a 63 kD form which is glycosylated in the endoplasmic reticulum to a 73 kD form; and that this in turn is trimmed and glycosylated further in the Golgi complex to the 79 kD form, which is secreted. The glycosylation is apparently not necessary for the secretion or for the affinity for human plasminogen kringles.

Peroxidation of phospholipids promoted by myeloperoxidase

Myeloperoxidase was found to promote peroxidation of phospholipids under acidic conditions in the presence of hydrogen peroxide and iodide ions. The peroxidation was markedly enhanced by pyrophosphate-chelated ferric iron and was inhibited by desferrioxamine and superoxide dismutase. This observation adds lipid peroxidation to the oxidative damage caused by myeloperoxidase, which is a phagocytic cell enzyme involved in phagocyte-mediated cell destruction.

Increased production of malondialdehyde in patients with HIV infection

The mean plasma content of malondialdehyde (MDA) in 30 patients in different stages of HIV infection was found to be about 30% higher than that in controls. The phenomenon was not correlated to the degree of immunodeficiency and was noted early in the course of the disease. This indicates a higher degree of basal lipid peroxidation, which might contribute to the tissue damage seen in these patients. A new reverse phase liquid chromatography method was used for quantitative measurements of MDA in plasma after reaction of this compound with thiobarbituric acid.

Inhibition of heme-promoted enzymatic lipid peroxidation by desferrioxamine and EDTA

Oxyhemoglobin, methemoglobin and hematin were found to catalyze xanthine-oxidase-induced peroxidation of phospholipid liposomes, while oxy- and metmyoglobin were inactive in this respect. The peroxidation was inhibited by desferrioxamine and by EDTA. Peroxidation catalyzed by 0.4 microM oxyhemoglobin was decreased by 50% by approximately 2 microM desferrioxamine or 20 microM EDTA and completely inhibited by 10 microM desferrioxamine or 100 microM EDTA. Inhibition of hemoglobin-catalyzed peroxidation was not accompanied by any changes in the absorbance spectra of hemoglobin, indicating that the heme iron was not withdrawn by the inhibitor. Inhibition of hematin-catalyzed peroxidation by desferrioxamine may have been due to iron chelation and removal, as judged from changes in absorbance spectra. The peroxidation was apparently not dependent on hydrogen peroxide since catalase did not inhibit peroxidation but on the contrary promoted it in some cases.

Two forms of alpha 2-antiplasmin: post-traumatic changes in the rat

The plasminogen-binding (PB-AP) and non-plasminogen-binding (NPB-AP) forms of alpha 2-antiplasmin (AP), were assayed in rat plasma by a modified rocket immunoelectrophoretic technique before and up to 48 h after turpentine-induced trauma, using an intermediary gel containing kringles 1-3 from plasminogen. The concentration of PB-AP was significantly elevated by 22% 24 h post-traumatically, while NPB-AP was decreased at that point in time, leaving the total AP level unchanged. Total AP increased by 57% during the period 24-48 h after trauma, mainly on account of increases in the NPB-AP form. It is concluded that the plasma level of AP can remain unchanged in spite of increased fibrinolysis inhibition, owing to a relative increase in the functionally more active PB-AP.

Effect of anti-inflammatory drugs on xanthine oxidase and xanthine oxidase induced depolymerization of hyaluronic acid

The inhibitory effect of various anti-inflammatory drugs on the xanthine oxidase derived depolymerization of hyaluronic acid was studied. The depolymerization was assayed by repeated viscosity measurements. By using a low xanthine oxidase activity, the decrease in viscosity with time followed first order reaction kinetics and was therefore suitable for kinetic analysis. The xanthine oxidase activity was monitored by assay of O2-consumption with a Clark-electrode and by assay of urate production. We present evidence that salicylic, acetylsalicylic, gentisic and azodisalicylic acid and sulfasalazine inhibit the production of oxygen-derived free radicals by xanthine oxidase. We found that sulfapyridine, 5-aminosalicylic acid, allopurinol, mannitol, glucuronic acid and N-acetylglucosamine in addition to the earlier studied drugs, paracetamol, ibuprofen, benoxaprofen and gentisic acid exert their effect via scavenging of free radicals. These drugs had very little effect on the enzyme activity.

Peroxidation of liposomes promoted by human polymorphonuclear leucocytes

Human polymorphonuclear leucocytes were found to promote peroxidation of phospholipid liposomes upon stimulation by phorbol myristate acetate. Peroxidation required the presence of either pyrophosphate-chelated or ADP-chelated iron, whereas iron chelated to EDTA or ATP had no effect. Peroxidation was also catalyzed by ferritin, but not by transferrin. Superoxide dismutase abolished the peroxidation, whereas catalase and apparently also the hydroxyl radical scavenger dimethyl sulphoxide were inactive, indicating that the peroxidation was mediated by superoxide radicals but not by hydrogen peroxide or hydroxyl radicals. Xanthine oxidase-promoted peroxidation was studied for comparison and showed similar characteristics except that transferrin catalyzed the peroxidation. Peroxidation of membrane lipids may be a mechanism whereby granulocytes cause tissue damage in inflammation. The drugs paracetamol, gentisic acid and 5-aminosalicylic acid inhibited lipid peroxidation, probably through their ability to react with the superoxide anion.

Peroxidation of linolenic acid promoted by human polymorphonuclear leucocytes

Human polymorphonuclear leucocytes were found to promote peroxidation linolenic acid micelles. The peroxidation was markedly enhanced by addition of ferric iron, either in the form of chloride, ADP-complex or EDTA to the phosphate-buffered reaction mixture. The leucocyte oxygen burst was induced by the addition of the lipid micelles, and no other stimulatory agent was therefore required. Pretreatment of the leucocytes with cytochalasin B did not inhibit t.e lipid peroxidation which indicates that phagocytosis was not part of the peroxidative mechanism. Lipid peroxidation was inhibited by alpha-tocopherol acetate, butylated hydroxytoluene, manganese ions and desferrioxamine but not by superoxide dismutase, catalase or the hydroxyl radical scavenger dimethylsulfoxide. Lipid peroxidation promoted by xanthine oxidase, was studied for comparison. This was inhibited by superoxide dismutase, indicating that xanthine oxidase, in contrast to leucocytes, promotes lipid peroxidation via a superoxide-dependent mechanism. Manganese ions and butylated hydroxytoluene, and to a lesser extent alpha-tocopherol, were also inhibitors. The leucocyte promoted lipid peroxidation is similar to the well-known peroxidation promoted by microsomal NADPH-cytochrome P450 reductase, which also is not induced by superoxide radicals. Peroxidation of lipids may be a mechanism whereby granulocytes express tissue damage in for example inflammation and ischaemia.

Xanthine oxidase induced depolymerization of hyaluronic acid in the presence of ferritin

Oxygen free radicals generated by xanthine oxidase are able to depolymerize hyaluronic acid in the presence of ferritin-bound iron. This suggests that ferritin can catalyse the Haber-Weiss reaction, leading to the formation of highly damaging hydroxyl radicals.

Fibrinolysis inhibition after a major standardized trauma

The present investigation on 20 patients after total hip replacement surgery has confirmed that the posttraumatic increase of the fibrinolysis inhibition activity (FIA) in serum and plasminogen-depleted serum is due to the primary fibrinolysis inhibitor (PFI, alpha 2-antiplasmin). This protein exists in at least two forms and it was indicated that PFI alpha with affinity to immobilized plasminogen, is mainly responsible for the posttraumatic variations of the FIA in plasminogen-depleted serum. PFI beta, the major part of the PFI-related antigen, which has none or low such affinity, displayed weak FIA and relatively small increase after the surgical trauma. It was established that the posttraumatic increase of the FIA was not derived from the low molecular weight fraction in serum of those patients.

Delayed elimination of fibrin from the lungs in rats given alpha 2-antiplasmin

Injection of human alpha 2-antiplasmin resulted in delayed elimination of fibrin from the lungs in rats with thrombin-induced intravascular coagulation. The amount of alpha 2-antiplasmin injected was chosen so as to simulate the posttraumatic increase of this inhibitor in man. By injecting trace amounts only of radiolabelled alpha 2- antiplasmin a specific uptake of this protein in the lungs was noted after the thrombin-induced coagulation. The results may indicate that the posttraumatic increase in alpha 2-antiplasmin is of significance for the delayed elimination of fibrin seen in patients following trauma.

Effect of dextran on fibrinolysis inhibition activity in the blood after major surgery

Patients undergoing total hip replacement surgery were given 500 ml of 6% dextran 70 or 5% albumin by intravenous infusion on the third postoperative day when the post-traumatic fibrinolysis inhibition has reached its maximum. The large increase in the fibrinolysis inhibition activity measured by a clot-lysis system was counteracted by the infusion of dextran, whereas the albumin infusion had no such effect. The plasma concentration of antiplasmin (chromogenic substrate assay) and the immunologically determined plasma levels of the primary fibrinolysis inhibitor (alpha2-antiplasmin), alpha2-macroglobulin, alpha2-antitrypsin and plasminogen were not changed after the infusion of dextran. It is hypothesized that dextran exerts its effects partly by interfering with the interaction between the primary fibrinolysis inhibitor, fibrin and plasmin(ogen) and by enhancing the activation rate of plasminogen. This observed effect of dextran may be of importance in the prevention of deep venous thrombosis and pulmonary embolic complications, as well as pulmonary microembolism.

Urokinase-induced fibrin clot lysis and its inhibition by plasma

The kinetics of the urokinase-induced plasmin digestion of fibrin clots has been studied. Some theoretical aspects on the kinetics of the underlying enzyme reactions are presented. It is shown that the clot-lysis time may be used to measure the relative amounts of fibrinolysis inhibitors in plasma.

Fibrinolysis Inhibition After a Standardized Trauma, Total Hip Replacement Surgery

Inhibition of the fibrinolytic system with delayed elimination of fibrin from the lungs after trauma is probably an important factor in the pathogenesis of the delayed microem-bolism syndrome. In the present investigation the posttraumatic inhibition of the fibrinolytic system was studied in 20 patients. Lowered levels of plasminogen and plasminogen activators in the blood as well as a decreased response to the venous occlusion test were found after trauma. The most impressive finding was a heavily increased fibrinolysis inhibition activity (FIA) measured by a clot lysis assay with a maximum 3 days after traum in plasminogen depleted serum. After gel filtration of these sera on Sephadex G-25 the protein-fractions showed a loss of FIA but the same posttraumatic increase as in whole serum. Antibodies against the primary fibrinolysis inhibitor (PFI) (“α2-antinlasmin”) strongly reduced the FIA in posttraumatic serum. A good correlation was seen between the increase of PFI with affinity to plasminogen (PFI:α) and FIA whereas PFI:β (with lower of no affinity to plasminogen) showed a weak correlation to the posttraumatic FIA increase. The strong FIA of the fraction adsorbed to the plasminogen was apparently due to PFI:α and not to α2-macroglobulin or α1-antitrypsin. This investigation showed that PFI:α seem to be of major importance for the posttraumatic increase in FIA.

Effect of Dextran on the Posttraumatic Fibrinolysis Inhibition

Increased fibrinolysis inhibition activity (PIA) in the blood is seen in patients with postoperative thromboembolic complications and has been suggested to be of importance in the pathogenesis of these conditions. Infusion of dextran (500 ml 6 %) to patients 3 days after total hip replacement surgery, when PIA was maximal, strongly decreased FIA of plasma measured by a clot lysis assay. Plasma antiplasmin (chromogenic substrate assay) and immunologically determined levels of the primary fibrinolysis inhibitor (PFI, α2-antiplasmin), α2-macroglobulin, α1-antitrypsin and plasminogen were not changed after the infusion of dextran. The effect of dextran on plasminogen activation by urokinase and fibrin degradation was studied in clotted plasma. The presence of dextran accelerated both the fibrinolysis and the uptake of labelled plasmin on fibrin. This effect of dextran was not seen in experiments where the clot was made of purified fibrinogen (containing plasminogen) instead of plasma. The FIA-decreasing effect of dextran is also dependent on the presence of physiological plasmin inhibitors and fibrin. The results indicate that the activation of plasminogen is enhanced by dextran provided that fibrin and inhibitors are present.

Severity and prognosis after early excisions from one to twenty percent of the body surface area

The authors review 101 small and medium early excisions with immediate grafting. They study several parameters concerning the severity of the burn, the time and the duration of the surgical procedure, the blood losses, the effect on the protidemia during the shock period, the duration of the hospital care, the septicemic risk, the mortality, and the functional and cosmetic results. They come to the conclusion that, under 15% of the body surface area, early excision can be done at one single operation with hardly any risk, and that it is better to perform it as soon as possible (before 12 hours if possible). With a good splinting and a daily rehabilitation, the cosmetic and functional results are very satisfactory.