Gingival crevicular fluid tissue/blood vessel-type plasminogen activator and plasminogen activator inhibitor-2 levels in patients with rheumatoid arthritis: effects of nonsurgical periodontal therapy.

BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate the effect of nonsurgical periodontal therapy on clinical parameters and gingival crevicular fluid levels of tissue/blood vessel-type plasminogen activator (t-PA) and plasminogen activator inhibitor-2 (PAI-2) in patients with periodontitis, with or without rheumatoid arthritis (RA). MATERIAL AND METHODS: Fifteen patients with RA and chronic periodontitis (RA-P), 15 systemically healthy patients with chronic periodontitis (H-P) and 15 periodontally and systemically healthy volunteers (C) were included in the study. Plaque index, gingival index, probing pocket depth, clinical attachment level, bleeding on probing, gingival crevicular fluid t-PA and PAI-2 levels, erythrocyte sedimentation rate, serum C-reactive protein and disease activity score were evaluated at baseline and 3 mo after mechanical nonsurgical periodontal therapy. RESULTS: All periodontal clinical parameters were significantly higher in the RA-P and H-P groups compared with the C group (p < 0.001) and decreased significantly after treatment (p < 0.001). Pretreatment t-PA levels were highest in the RA-P group and significantly decreased post-treatment (p = 0.047). Pre- and post-treatment PAI-2 levels were significantly lower in controls compared with both periodontitis groups (p < 0.05). Gingival crevicular fluid volume and the levels of t-PA and PAI-2 were significantly correlated. CONCLUSION: In patients with periodontitis and RA, nonsurgical periodontal therapy reduced the pretreatment gingival crevicular fluid t-PA levels, which were significantly correlated with gingival crevicular fluid PAI-2 levels. The significantly higher t-PA and PAI-2 gingival crevicular fluid levels in periodontal patients, regardless of systemic status, suggest that the plasminogen activating system plays a role in the disease process of periodontitis.

Urokinase and its receptor in follicular and inflammatory cysts of the jaws.

OBJECTIVE: Proteases are considered critical in peri-cystic tissue degradation required in jaw cyst expansion. We studied the expression of the plasminogen activation system (plasminogen activators; their inhibitor type-1, PAI-1; the receptor for the urokinase-type plasminogen activator, uPAR) in follicular and inflammatory cysts of the jaw, to identify a possible role of this system in jaw cyst enlargement. MATERIALS AND METHODS: Jaw cysts were collected by therapeutic enucleation. ELISA and casein zymography were used to measure and characterize plasminogen activators in cyst fluid. By immunohistochemistry we examined the presence of uPAR in cyst walls and inflammatory cells, and by Western blotting the molecular forms of uPAR within the cyst fluid. RESULTS: Inflammatory cysts fluid contained higher amounts of plasminogen activators of the urinary-type (uPA), and lower amounts of PAI-1, when compared to follicular cysts fluid. Epithelial layers of both types of cysts and inflammatory cells expressed uPAR. Native 3-domain uPAR was scarcely detectable within cysts, where its cleavage was accounted for by uPA. CONCLUSION: These data suggest a plasminogen activation-dependent mechanism of cyst enlargement, where only the outward uPAR expressed on epithelial cells and on inflammatory cells direct the peri-cystic protease cascade, in a way similar to tumor enlargement within tissues.

Human dental pulp stromal cell conditioned medium alters endothelial cell behavior.

BACKGROUND: Angiogenesis is of utmost importance for tissue regeneration and repair. Human dental pulp stromal cells (hDPSCs) possess angiogenic potential, as they secrete paracrine factors that may alter the host microenvironment. However, more insight into how hDPSCs guide endothelial cells (ECs) in a paracrine fashion is yet to be obtained. Therefore, the current study aimed to investigate the effect(s) of conditioned medium derived from hDPSCs (hDPSC-CM) on EC behavior in vitro. METHODS: hDPSCs were harvested from third molars scheduled for surgical removal under informed consent. The angiogenic profile of hDPSC-CM was identified using human angiogenesis antibody array and enzyme-linked immunosorbent assay (ELISA). Using real-time reverse transcription-polymerase chain reaction (RT-PCR) and ELISA, the mRNA and protein expression level of specific angiogenic biomarkers was determined in human umbilical vein endothelial cells (HUVECs) exposed to hDPSC-CM. The effect of hDPSC-CM on HUVEC attachment, proliferation and migration was evaluated by crystal violet staining, MTT, transwell migration along with real-time cell monitoring assays (xCELLigence; ACEA Biosciences, Inc.). A Matrigel assay was included to examine the influence of hDPSC-CM on HUVEC network formation. Endothelial growth medium (EGM-2) and EGM-2 supplemented with hDPSC-CM served as experimental groups, whereas endothelial basal medium (EBM-2) was set as negative control. RESULTS: A wide range of proangiogenic and antiangiogenic factors, including vascular endothelial growth factor, tissue inhibitor of metalloproteinase protein 1, plasminogen activator inhibitor (serpin E1), urokinase plasminogen activator and stromal cell-derived factor 1, was abundantly detected in hDPSC-CM by protein profiling array and ELISA. hDPSC-CM significantly accelerated the adhesion phases, from sedimentation to attachment and spreading, the proliferation rate and migration of HUVECs as shown in both endpoint assays and real-time cell analysis recordings. Furthermore, Matrigel assay demonstrated that hDPSC-CM stimulated tubulogenesis, affecting angiogenic parameters such as the number of nodes, meshes and total tube length. CONCLUSIONS: The sustained proangiogenic and promaturation effects of hDPSC-CM shown in this in vitro study strongly suggest that the trophic factors released by hDPSCs are able to trigger pronounced angiogenic responses, even beyond EGM-2 considered as an optimal culture condition for ECs.

Plasminogen activation by fibroblasts from periodontal ligament and gingiva is not directly affected by chemokines in vitro.

OBJECTIVE: Chronic inflammation in periodontal disease is associated with increased plasminogen activation and elevated levels of chemokines. It is unknown whether chemokines can regulate the activation of plasminogen via modulation of plasminogen activators (PA) and the corresponding plasminogen activator inhibitors (PAI) in periodontal tissue. DESIGN: To establish a link between chemokines and activation of plasminogen, human periodontal ligament fibroblasts (PDL) and gingival fibroblasts (GF) were incubated with IL-8, monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, and platelet factor-4, either alone or in the presence of the inflammatory mediators TGF-beta and IL-1. The potential of the cell lysates to activate plasminogen was based on kinetic studies with the substrate casein. Casein zymography was performed to determine the molecular sizes of the PA. Total PAI-1 in the cell-conditioned medium was quantified by immunoassay. RESULTS: We report that the chemokines did not affect activation of plasminogen by PDL and GF. Even in the presence of TGF-beta which suppressed, and IL-1 which stimulated plasminogen activation, the chemokines had no direct effect. Inhibition of PA and plasmin, but not of matrix metalloproteinases and cysteine proteinases prevented caseinolysis. The plasminogen activation capacity of the cell lysates was represented by a single band with features of uPA. The immunoassay showed that the release of PAI-1 in PDL and GF remained unaffected by the chemokines, also when stimulated with TGF-beta. CONCLUSIONS: These results suggest that plasminogen activation by PDL and GF is not directly affected by the chemokines even in the presence of the inflammatory mediators TGF-beta and IL-1.

Inherited fibrinolytic disorder due to an enhanced plasminogen activator level.

A family with "in vitro" increased red-cell fall out from the blood clot was studied. One member of the family (JVM) had a clinical history of hemorrhages after minor trauma or dental extractions. Routine coagulation and platelet function were normal except for the fibrinogen level which was slightly low in several members. The antigenic as well as functional evaluation of factor XIII was within normal limits. No factor XIII inhibitors were present. An increase in the clot permeability index was observed in most family members. The study of the fibrinolytic system showed an enhanced lysis of euglobulins, a normal plasminogen value, normal level of fibrin/ogen degradation products, normal fibrinolytic inhibitors, and an increase in the activity of the plasminogen activator. The activity of this activator was inhibited by an antiserum against tissue-type plasminogen activator. The t-pA inhibitor was in the normal range. It is concluded that the family studied in this paper shows familial alteration in the fibrinolytic system due to an excess of plasminogen activator immunologically related to that in human tissue.

A rapid and highly sensitive solid-phase radioassay for plasminogen activators.

A rapid and highly sensitive solid-phase radioassay for the measurement of plasminogen activators is presented. The method employs a convenient and stable 125I-fibrinogen-latex bead product and can reproducibly detect 0.25 milli Ploug units/ml of urokinase. This represents a 100-fold increase in sensitivity over previously published radioisotopic solid-phase technique and a 120-fold increase over the sensitivity of the fibrin plate method. Since the assay can readily detect plasminogen activator levels in euglobulin solutions prepared from pre- and post-venous occlusion plasma, it may be useful for rapidly detecting and monitoring the fibrinolytic potential of patients predisposed to thromboembolic disease.

Detection of plasminogen activators in oral cancer by laser capture microdissection combined with zymography.

Plasminogen activation is believed to be critical to the progression of oral squamous cell carcinoma by facilitating matrix degradation during invasion and metastasis, and high levels of urokinase plasminogen activator (uPA) and plasminogen activator (PA) inhibitor-1 (PAI-1) in tumors predict poor disease outcome. We describe the development of a novel method for studying PA in oral cancer that combines the sensitivity and specificity of zymography with the spatial resolution of immunohistochemistry. Laser capture microdissection (LCM) was combined with plasminogen-casein zymography to analyze uPA, tissue PA (tPA), uPA-PAI-1 complexes, and tPA-PAI-1 complexes in 11 tumors and adjacent non-malignant epithelium from squamous cell carcinomas of the tongue, floor of mouth, larynx, and vocal cord. uPA was detectable in all tumor samples analyzed, uPA-PAI-1 complexes in three samples, and tPA in nine. PA was detectable in as little as 0.5 microg protein lysate from microdissected tumors. In all specimens, uPA expression was highly increased in tumor tissue compared to adjacent non-malignant tissue. In conclusion, LCM combined with zymography may be excellently suited for analyzing the prognostic significance and causal involvement of the plasminogen activation system in oral cancer.

An orthotopic floor-of-mouth cancer model allows quantification of tumor invasion.

OBJECTIVES: To establish an orthotopic murine floor-of-mouth cancer model for the analysis of the role of proteases such as urokinase-type plasminogen activator (u-PA) and the matrix metalloprotease MMP-9 (MMP-9) in in vivo invasion. STUDY DESIGN: Randomized, prospective animal study. METHODS: Two human squamous cell carcinoma cell lines, UM-SCC-1 and 022, were assayed via zymography for their in vitro secretion levels of u-PA and MMP-9. Both cell lines (5 x 10(6) cells) were injected into the cervical subcutaneous tissues of female athymic nude (nu/nu) mice superficial to the mylohyoid muscle. Mice were sacrificed after 30 days, and tumor invasion characteristics were histologically compared. Additional mice were then inoculated with invasive UM-SCC-1 cells and sacrificed 10, 30, and 40 days after inoculation to identify distinct stages of invasion. RESULTS: In vitro secretion levels of MMP-9 and activity of u-PA were higher in UM-SCC-1 cells than in 022 cells. In the in vivo studies, tumors formed from 022 cells were found to be noninvasive, whereas tumors derived from UM-SCC-1 cells progressed through distinct and readily identifiable histologic stages of invasion. These stages included invasion of adjacent muscle layers (mylohyoid, geniohyoid, and genioglossus muscles) and of associated structures (blood vessels, bone, nerve, and regional lymph nodes). A staging system was devised accordingly. CONCLUSION: We developed an in vivo quantitative cancer invasion model that allows determination of the effect of the expression and activity levels of the proteases MMP-9 and u-PA. Tumor invasion occurred in an orderly and stepwise fashion involving muscles and related vascular, nervous, and bony structures of the floor of the mouth and tongue. This orderly invasion allowed the development of a staging system. We anticipate that this model will have wide applicability in the study of in vivo tumor response to a variety of novel therapeutic approaches.

Plasminogen activator activity is decreased in rat gingiva during diabetes.

Diabetes produces extensive alterations of collagen metabolism including enhanced gingival collagenase activity. However, the mechanism for this enhanced enzyme activity is unclear. Collagenase is secreted from cells in a latent form and plasmin has been proposed as an important in vivo activator of procollagenase. Plasmin is converted from its precursor, plasminogen, by the proteolytic action of a serine proteinase, plasminogen activator (PA). The current study was therefore undertaken to determine the effect of diabetes on gingival PA activity in the rat. Since doxycycline is a potent collagenase inhibitor, the effect of doxycycline on gingival PA activity was also investigated. Eighteen male, Sprague-Dawley rats were made diabetic by streptozotocin injection (7 mg/100 g). Control rats (N = 8) were sham-treated. Doxycycline (5 mg/day/rat) was administered to 9 of the 18 diabetic rats by gavage on a daily basis. The other 9 diabetic rats were administered with saline. After 3 weeks, blood and gingival tissue were collected from each rat for the determination of glucose level and gingival PA activity. The tissues were then minced and extracted with 5 mM sodium phosphate containing 1% Triton X-100. PA assay was performed using chromatogenic substrate to determine PA activity in the extracts. Gingival PA activity in the diabetic rats was significantly reduced compared to the control (13.5 +/- 1.6 vs. 36.0 +/- 3.3 microunits/100 micrograms protein, P < 0.01). Doxycycline administration to diabetic rats had no effect on the already reduced gingival PA activity (10.4 +/- 3.5 in doxycycline-treated rats vs. 13.5 +/- 1.6 mu units/100 micrograms protein in untreated diabetic rats). PA activities in gingival tissues from the diabetic, nondiabetic control and doxycycline-treated diabetic groups were also demonstrated on zymographs as lytic bands. Regarding the well-known fact that gingival collagenase activity is enhanced during diabetes, our results did not support the notion that this biochemical alteration is attributed to increased activation of procollagenase by PA.

The expression of plasminogen activator system in a rat model of periodontal wound healing.

BACKGROUND: The plasminogen activator system has been proposed to play a role in proteolytic degradation of extracellular matrices in tissue remodeling, including wound healing. The aim of this study was to elucidate the presence of components of the plasminogen activator system during different stages of periodontal wound healing. METHODS: Periodontal wounds were created around the molars of adult rats and healing was followed for 28 days. Immunohistochemical analyses of the healing tissues and an analysis of the periodontal wound healing fluid by ELISA were carried out for the detection of tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA), and 2 plasminogen activator inhibitors (PAI-1 and PAI-2). RESULTS: During the early stages (days 1 to 3) of periodontal wound healing, PAI-1 and PAI-2 were found to be closely associated with the deposition of a fibrin clot in the gingival sulcus. These components were strongly associated with the infiltrating inflammatory cells around the fibrin clot. During days 3 to 7, u-PA, PAI-1, and PAI-2 were associated with cells (particularly monocytes/macrophages, fibroblasts, and endothelial cells) in the newly formed granulation tissue. During days 7 to 14, a new attachment apparatus was formed during which PAI-1, PAI-2, and u-PA were localized in both periodontal ligament fibroblasts (PDL) and epithelial cells at sites where these cells were attaching to the root surface. In the periodontal wound healing fluid, the concentration for t-PA increased and peaked during the first week. PAI-2 had a similar expression to t-PA, but at a lower level over the entire wound-healing period. CONCLUSIONS: These findings indicate that the plasminogen activator system is involved in the entire process of periodontal wound healing, in particular with the formation of fibrin matrix on the root surface and its replacement by granulation tissue, as well as the subsequent formation of the attachment of soft tissue to the root surface during the later stages of wound repair.

Proteolytic activity of rabbit incisor dentine.

The presence of proteolytic activity and plasminogen activator was demonstrated in extracts of the dentine from serial sections from all regions of the incisor. Maximal activity was at neutral pH, although some was also present at acidic pH. Preparations of dentine non-collagenous matrix (NCM) proteins were sensitive to the proteolytic activity; NCM prepared by EDTA extraction contained such activity.

Immunological characterization of plasminogen activators in human parotid saliva.

These were characterized in stimulated saliva from 21 healthy volunteers using antibodies specific for human tissue-type plasminogen activator (t-PA) or urokinase. After pre-incubation with immunoglobulins, with and without specific antibodies, the fibrinolytic activity was assayed on fibrin plates containing plasminogen. Fibrinolytic activity was demonstrated in all salivas but one; it was completely quenched by antibodies against t-PA, but antibodies against urokinase-like plasminogen activator had no effect. The fibrinolytic activity was expressed in international units (IU) using a standard curve obtained by serial dilution of the international tissue-plasminogen standard. The normal range was 0.05-0.35 IU/ml, and the maximal value 2 IU/ml. There is thus considerable individual variation in fibrinolytic activity in parotid saliva, where it is regulated by t-PA under physiological conditions.

Localization of plasminogen activators and plasminogen-activator inhibitors in human gingival tissues demonstrated by immunohistochemistry and in situ hybridization.

The plasminogen-activating system plays an important part in tissue proteolysis in physiological as well as pathological processes. Plasminogen activators u-PA (urokinase) and t-PA (tissue) as well as the inhibitors PAI-1 and PAI-2 are present in gingival crevicular fluid in concentrations significantly greater than in plasma. This fact, and the finding that the concentrations of t-PA and PAI-2 are higher in areas with gingival inflammation, indicate local production of these components. The present study describes, by means of in situ hybridization and immunohistochemistry, the localization of the plasminogen activators and their inhibitors in gingival tissues from patients undergoing periodontal surgery. t-PA mRNA and t-PA antigen were primarily found in the epithelial tissues, predominantly in the sulcular and junctional regions, although occasionally in the oral epithelium and in blood vessels of the connective tissue. u-PA and u-PA-receptor signals were seen in single cells within the junctional and sulcular epithelia and adjacent to blood vessels close to the junctional epithelium, but rarely in the oral epithelium. Similar to t-PA, the predominant location of PAI-2 mRNA was the gingival epithelia. In the junctional and sulcular epithelia, PAI-2 mRNA was seen throughout the thickness, while in the oral epithelium the strongest signals were seen in stratum granulosum and stratum spinosum. PAI-1 mRNA was invariably found in the connective tissue associated with blood vessels. The present study confirms earlier indications of local production of plasminogen activators and their inhibitors in gingival tissues. In addition, the results demonstrate that t-PA and PAI-2 in these patients are produced predominantly in the epithelial tissues. Furthermore, the presence of t-PA and PAI-2 seems to be most pronounced in the areas likely to be subjected to bacterial assault.

Molecular characterization of plasminogen activators in human gingival crevicular fluid.

Plasminogen activators (PAs), a family of serine proteases, and their inhibitors (PAIs) are important in fibrinolysis, wound healing and tissue remodelling. Previous studies revealed differences in the localization of PA activity between healthy and diseased gingival tissues, suggesting that PAs and PAIs could play a part in periodontal homeostasis and disease. PAs and PAIs are synthesized by most of the cells types making up the periodontium and can be identified in gingival crevicular fluid (GCF). These studies sought to characterize the molecular species of PAs and their inhibitors in GCF collected from clinically healthy sites. PA enzymatic activity in GCF samples demonstrated by fibrin zymography revealed the presence of only tissue-type PA (tPA) activity. No urokinase-type PA (uPA) enzymatic activity was detected. tPA enzymatic activity appeared predominantly as an uncomplexed 70-kDa species, although some samples contained enzyme-inhibitor complexes. Quantitation of total tPA by enzyme immunoassay showed a mean concentration of 1.6 ng/microl. Analysis of GCF samples for uPA by immunoblotting and enzyme immunoassay disclosed the presence of small amounts of uPA (0.2 ng/microl), which were present predominantly in activator-inhibitor complexes. Immunoblotting showed specific PAI-2 immunoreactivity bands in high molecular-weight complexes and low molecular-weight degradation products, but less than nanogram amounts of free PAI-2 molecules. Enzyme immunoassay revealed that PAI-2 was present in an at least a seven times greater amount than PAI-1. These observations support the hypothesis that PA-generated proteolysis and its regulation by endogenous inhibitors has a role in the diverse biochemical mechanisms underlying periodontal physiology and pathology including host-microbial interaction, polymorphonuclear leucocyte infiltration, turnover and migration of epithelial cells, connective tissue degradation and remodelling, fibrinolysis and wound healing.

An enzyme-linked immunosorbent assay for host cell protein contaminants in recombinant PEGylated staphylokinase mutant SY161.

Staphylokinase, a bacterially-derived protein which functions as a plasminogen activator, has potential utility as a human therapeutic for thrombotic disorders. A recombinant version of this protein, SY161, contains 13 amino acid substitutions designed to decrease immunogenicity, and has been covalently modified by crosslinking a 5 kDa polyethyleneglycol (PEG) group to the N-terminal region to prolong the drug circulating half-life. The recombinant PEG-modified SY161 staphylokinase is currently in phase II clinical trials as a treatment for acute myocardial infarction. We have developed a sensitive product specific host cell protein (HCP) assay in the ELISA format to monitor in process host-derived contaminant clearance and final drug product purity. The assay is based upon use of goat polyclonal antibodies raised against E. coli host strain cell proteins from a null cell line, extracted by the same manufacturing process used to produce SY161. The identification and clearance of HCP contaminants was confirmed during drug product production using SDS-PAGE and Western blotting utilizing the same polyclonal HCP antibodies. The assay is specific for E. coli host cell strain proteins with a useful detection range from 1 to 100 ng/ml, and is not affected by product level. The level of residual HCPs in the clinical product produced by our manufacturing process was determined to be less than 1 ng/ml at a product concentration of 1 mg/ml.

Effect of black-pigmented bacteria on the plasminogen-plasmin system in human pulp and osteoblastic cells.

OBJECTIVE: To date, there have been relatively few studies addressing the presence and expression of the plasminogen-plasmin system at the site of bacterial infection. The aim of the present study was to investigate the effect of black-pigmented bacteria on the expression of the plasminogen-plasmin system in human pulp and osteoblastic cells. STUDY DESIGN: The supernatants of Porphyromonas endodontalis, Porphyromonas gingivalis, and Prevotella intermedia were used to evaluate tissue-type plasminogen activator (t-PA) and type 1 plasminogen activator inhibitor (PAI-1) gene expression in human pulp and osteoblastic cells. The levels of mRNA were quantitatively measured by using reverse transcription-polymerase chain reaction. RESULTS: In this study, black-pigmented bacteria induced not only t-PA but also PAI-1 gene expression in human pulp and osteoblastic cells. In addition, the ratio of t-PA to PAI-1 was higher in human pulp and osteoblastic cells stimulated by black-pigmented bacteria than in untreated cell cultures (P <.05). CONCLUSIONS: A fine balance exists in the expression of components of the plasminogen-plasmin system, whereby tissue homeostasis is maintained. Black-pigmented bacteria activate the activator-inhibitor system in human pulp and osteoblastic cells through unbalance regulation of t-PA and PAI-1, which might result in an uncontrolled degradation of pulpal and periapical tissues.

[Streptokinase immobilization in insoluble carriers, and properties of the immobilized protein]. / Immobilizatsiia streptokinazy na nerastvorimykh nositeliakh i svoistva immobilizirovannogo belka.

Immobilization of streptokinase was performed by bromine cyan-activated cellulose and by aminoethyl cellulose using glutaric aldehyde and N-cyclohexyl-N'-[2-(4-morpholinyl)-ethyl-carbodiimide. The specific activator activity of the immobilized streptokinase is 70-100% of that of free streptokinase. In multiple application of the immobilized protein preparations streptokinase obtained by bromine cyan-activated cellulose is the most stable: it retains more than 40% of initial activity after 10 repeated applications. The immobilized streptokinase is shown to be more thermostable as compared to the soluble one.

[The normal fibrinolytic activity of the oral mucosa and saliva and in pathology]. / Fibrinoliticheskaia aktivnost' slizistoi obolochki polosti rta i sliuny v norme i pri patologii.

Local fibrinolysis was studied of oral cavity in healthy individuals (n = 20) and in patients suffering from inflammatory changes in the mucous membrane of the oral cavity (n = 23). Comparison of the results was done with reference to the indicators of the systemic fibrinolysis activity in the same persons. There has been revealed a definite fibrinolytic activity of saliva, particularly its mucinous component. In healthy subjects it is significantly higher as compared to the patients. The local fibrinolysis is provided by the activator of plasminogen rather than the enzyme plasmin. The mucous membrane of the oral cavity does not possess physiologically significant activity since the tissue activator of plasminogen it contains is extracted with 2M solution of potassium thiocyanate only. No shifts of systemic fibrinolytic potential have been revealed in inflammatory changes of the mucous membrane.

[Identification of plasminogen activators in the saliva of Rhapactor biparticeps (Reduviidae)]. / Identification d'activateurs du plasminogène dans la salive de Rhapactor biparticeps (Reduviidae).

Plasminogen activators are identified in the saliva of Rhapactor biparticeps using a particular technique which includes human fibrin in polyacrylamide gel. This technique is described and results are discussed according to classical methods used for fibrinolysis studies.

[Demonstration of plasminogen activators in the saliva of a predatory insect of the family of Reduviidae (Heteroptera)]. / Mise en évidence d'activateurs du plasminogène dans la salive d'un insecte prédateur de la famille des Reduviidae (Heteroptera).

The study of digestive and salivary proteases of Rhapactor biparticeps, has shown that the salivary glands of this insect are rich in proteolytic enzymes, however, the gut has none. The characterisation of these enzymes on different substrates showed that they are only active on fibrinogen and plasmatic proteins which are involved in the coagulation system. Among these fibrinolytic enzymes that has been identified and characterized, are the plasminogen activators. Their unexpected presence in the entomophagic insect is discussed.