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Biomedical subjects

B R Binder

Publications and source records attributed to B R Binder.

At least 127 records · Page 7Linked to original sources
PubMed1992

Inhibition of tissue kallikrein by protein C inhibitor. Evidence for identity of protein C inhibitor with the kallikrein binding protein.

We studied the inhibition of tissue kallikrein by protein C inhibitor (PCI), a relatively unspecific heparin-dependent serine protease inhibitor present in plasma and urine. PCI inhibited the amidolytic activity (cleavage of H-D-valyl-L-leucyl-arginine-p-nitroaniline) of urinary kallikrein with an apparent second order rate constant of 2.3 x 10(4) M-1 s-1 and formed stable complexes (85 kDa) with urinary kallikrein as judged from silver-stained sodium dodecyl sulfate-polyacrylamide gels. Complex formation was time-dependent and was paralleled by a decrease in the intensity of the main PCI protein band (Mr = 57,000) and an increase in the intensity of the lower Mr (54,000) PCI form (cleaved inhibitor). Heparin interfered with the inhibition of tissue kallikrein by PCI and with the formation of tissue kallikrein-PCI complexes in a dose-dependent fashion and completely abolished PCI-tissue kallikrein interaction at 300 micrograms/ml. This is in contrast to findings on the interaction of PCI with all other target proteases studied so far (i.e. stimulation of inhibition by heparin) but is similar to the reaction pattern of 125I-labeled tissue kallikrein with so called kallikrein binding protein described in serum and other systems. To study a possible relationship between PCI and this kallikrein binding protein we incubated 125I-labeled urinary kallikrein in serum and in PCI-immunodepleted serum in the absence and presence of heparin and analyzed complex formation using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In normal serum, formed complexes co-migrated with complexes of purified PCI and 125I-kallikrein and were less intense in the presence of heparin. No complex formation at all was seen in PCI-depleted serum. Our data indicate that PCI may be a physiologically important endogenous inhibitor of tissue kallikrein and provide evidence that PCI may be identical to the previously described kallikrein binding protein.

Amides↗
PubMed1992

Determination of plasma urokinase-type plasminogen activator antigen in patients with primary liver cancer: characterization as tumor-associated antigen and comparison with alpha-fetoprotein.

We determined the plasma levels of urokinase-type plasminogen activator (u-PA) antigen and alpha-fetoprotein (AFP) in 44 patients with different stages of liver cirrhosis and in 29 patients with liver cirrhosis-based primary liver cancer at the time of first clinical detection of the malignant disease. Sensitivity values of u-PA and AFP in detecting primary liver cancer were 57 and 62%, respectively, and specificity values were 95 and 86%, respectively. A combination of both markers led to a significant increase of sensitivity to 89.7%. The specificity of the combination of both markers was 97.3%. In tumor patients with unilocular disease and tumor patients with multicentric disease and/or metastatic spread, similar sensitivity values could be obtained with both markers. Therefore, a combination of u-PA and AFP can increase the accuracy of detection of primary liver cancer, especially in chronic liver diseases known to be predisposing for primary liver cancer, e.g., liver cirrhosis of long duration.

Antigens, Neoplasm↗
PubMed1992

A decrease in plasminogen activator inhibitor-1 activity after successful percutaneous transluminal coronary angioplasty is associated with a significantly reduced risk for coronary restenosis.

To determine a possible relation of changes in plasma levels of plasminogen activator inhibitor 1 (PAI-1) and tissue plasminogen activator (t-PA) to the development of coronary restenosis after successful coronary angioplasty (PTCA), we followed 104 patients with a low grade residual stenosis after PTCA (less than 30%) for a period of 12 months. PAI-1 plasma levels (functional activity) and t-PA antigen were determined 1 day before PTCA and 3 days, 3 months and 6 months thereafter. Thirty-four patients (32.69%) developed angiographically proven coronary restenosis (group A) within a time range of 4-48 weeks (median 12.5 weeks) after PTCA while the remaining patients (group B) had neither clinical signs nor angiographic evidence of restenosis after 6 months. No significant differences could be demonstrated in t-PA antigen or PAI-1 activity (plasma levels between the two groups of patients the day before PTCA). During the whole observation period t-PA plasma levels were not significantly different between the two groups; however, PAI-1 plasma levels were significantly higher at 3 months and 6 months after PTCA in patients of group A (p less than 0.005). When the pattern of PAI-1 plasma levels over time (increase or decrease between two consecutive time points of blood collection) was used to discriminate between the two study groups only 3.5-18% of patients with a decrease in PAI-1 developed coronary restenosis within the following observation period in contrast to 25-58% of patients with an increase in PAI-1 plasma levels (p less than 0.05 to p less than 0.0005).

Aged↗
PubMed1992

Possible identity of kallikrein binding protein with protein C inhibitor.

Protein C inhibitor (PCI) inhibits tissue kallikrein by forming stable 1:1 complexes (k1 = 2.3 x 10(4)M-1s-1). Heparin inhibits the tissue kallikrein/PCI-interaction and complex formation of 125I-tissue kallikrein in serum. 125I-tissue kallikrein complexes formed in plasma can be immunoprecipitated with monoclonal anti-PCI IgG suggesting that PCI might be identical to the kallikrein binding protein described previously (J. Chao et al. 1986, Biochem. J. 239, 325-331).

Carrier Proteins↗
PubMed1992

Determination of human low molecular weight kininogen by immunoassay.

It was the aim of the present investigation to develop a convenient method for determination of human kininogens. Using mono- and polyclonal antibody preparations an ELISA-system for specific determination of LMWK could be developed. In addition, the specificity of the monoclonal antibody suggests that their epitope in HMWK and its heavy chain is different to that in LMWK.

Antibodies, Monoclonal↗
PubMed1992

Allosteric regulation of tPA-mediated plasminogen activation by a modifier mechanism: evidence for a binding site for plasminogen on the tPA A-chain.

We studied the mechanism responsible for nonlinear double reciprocal plots for tissue type plasminogen activator (tPA)-mediated plasminogen activation reported previously by several groups. We found nonlinear Eadie-Scatchard plots for Glu-plasminogen activation by recombinant single-chain tPA confirming a non-Michaelis-Menten behavior of tPA. In order to characterize this mechanism, enzyme kinetic studies with truncated substrates (Lys- and miniplasminogen) and modified or truncated enzymes (two-chain tPA and tPA B-chain) were performed. Thereby it could be excluded that product-mediated modifications of the enzyme or the substrate are responsible for the nonlinear plots. Linear plots, i.e., Michaelis-Menten kinetics, were only found when tPA B-chain was used as a plasminogen activator, indicating that the tPA A-chain should be responsible for the non-Michaelis-Menten behavior. Binding studies of plasminogen to immobilized tPA A-chain in fact demonstrated a saturable binding of Glu- and miniplasminogen to the A-chain of tPA with a KD approximately 0.1 microM and one binding site per molecule of tPA A-chain. These data suggested a modifier mechanism responsible for the nonlinear plots whereby the substrate plasminogen itself could function as a modifier. When such a mechanism was included into a model for tPA-mediated plasminogen activation, the experimentally obtained data could be fitted into such a model by nonlinear regression analysis with resulting p-values of less than 0.001.

Allosteric Regulation↗
PubMed1992

Endogenous fibrinolytic system in chronic large-vessel thromboembolic pulmonary hypertension.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) is a disorder characterized by pulmonary arterial hypertension as a consequence of organized thrombotic material in the central pulmonary arteries. Incomplete resolution of acute pulmonary emboli is believed to be pathogenically important; however, the mechanism for poor thrombus dissolution remains to be explained. We undertook this study to assess the major determinants of plasma fibrinolysis in patients with CTEPH (n = 32). METHODS AND RESULTS: Immunological and functional levels of tissue-type plasminogen activator (t-PA) and type 1 plasminogen activator inhibitor (PAI-1) were quantified in platelet-poor plasma (PPP) from patients with CTEPH as well as age-matched controls. Although basal PPP t-PA antigen levels (CTEPH mean, 29.5 ng/ml; control mean, 2.7 ng/ml) and PAI-1 antigen levels (CTEPH mean, 55.8 ng/ml; control mean, 21.0 ng/ml) were higher in the CTEPH group, no between-group differences were detected in the enzymatic activities of these two molecules. The CTEPH group demonstrated a greater rise in t-PA antigen (CTEPH mean rise, 53.0 ng/ml; control mean rise, 5.6 ng/ml) and PA activity (CTEPH mean rise, 10.5 IU/ml; control mean rise, 1.2 IU/ml) than controls in response to an experimentally induced venous occlusion. Immunoprecipitation and fibrin autography of PPP from two patients with markedly elevated basal t-PA antigen levels demonstrate that the t-PA antigen was present in PPP primarily in complex with PAI-1. CONCLUSIONS: Although abnormalities of the fibrinolytic system were detected, neither a high resting plasma PAI-1 activity nor a blunted response of t-PA to venous occlusion can be invoked as an etiology for CTEPH:

Adolescent↗
PubMed1991

Urinary protein C inhibitor. Glycosaminoclycans synthesized by the epithelial kidney cell line TCL-598 enhance its interaction with urokinase.

Protein C inhibitor (PCI), also known as plasminogen activator inhibitor 3, inhibits a variety of serine proteases by forming sodium dodecyl sulfate-stable 1:1 complexes. In purified systems PCI is only a weak inhibitor of urokinase. Nevertheless, complexes between PCI and urokinase are found in appreciable amounts in native human urine. Since PCI activity is stimulated by heparin and other glycosaminoglycans, we investigated the presence of stimulating glycosaminoglycans on cells lining the urinary tract. We chose the epithelial kidney tumor cell line TCL-598 as a model and isolated metabolically labeled glycosaminoglycans. TCL-598 incorporated [35S] sulfate into high Mr components (Mr greater than 200,000 and approximately 75,000) as judged from sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography of cell extracts; the Mr greater than 200,000 component bound specifically to PCI-Sepharose 4B and was eluted either with heparin (5 mg/ml) or with NaCl (2.0 M). Treatment of this PCI-binding material with chondroitinase ABC, but not with chondritinase AC or heparitinase, abolished binding to PCI-Sepharose, confirming the glycosaminoglycan nature of this material and suggesting the involvement of dermatan sulfate in binding. These glycosaminoglycans eluted from PCI-Sepharose stimulated urokinase inhibition by PCI in a dose-dependent way and enhanced complex formation of 125I-urokinase and PCI as did in control experiments dermatan sulfate from porcine skin and from bovine mucosa. Our results suggest that PCI activity might be regulated also in vivo by the presence or absence of stimulating glycosaminoglycans; dermatan sulfate-containing glycosaminoglycans associated with kidney cells might be responsible for stimulation of the urokinase inhibitory activity of PCI in the urinary tract; the type of glucosaminoclycans might furthermore regulate enzyme specificity of PCI.

Autoradiography↗
PubMed1991

Hepatic synthesis and clearance of components of the fibrinolytic system in healthy volunteers and in patients with different stages of liver cirrhosis.

We determined plasma levels of tissue-type plasminogen activator (t-PA) antigen, urokinase-type plasminogen activator (u-PA) antigen, and activity of the fast acting inhibitor of plasminogen activator (PAI-1) in patients with different stages of liver cirrhosis (Child A, B, and C) and in age and sex-matched healthy controls to investigate the contribution of the liver to the metabolism of these main components of the fibrinolytic system. For control purposes routine clotting parameters were also determined. In patients with the most severe form of liver cirrhosis (Child C) t-PA antigen levels were significantly elevated as compared to patients with Child A or Child B (p less than 0.05) or to controls (p less than 0.01). Furthermore, Child C patients exhibited significantly decreased PAI-1 plasma levels (p less than 0.05) as compared to controls. We were not able to demonstrate, however, any significant correlation between liver function and u-PA plasma levels. Furthermore, t-PA antigen and albumin plasma levels were negatively correlated (r = 0.48; p = 0.0015) and t-PA antigen and bilirubin were positively correlated (r = 0.46; p = 0.0022) thus indicating that the liver is mainly involved in the clearance of t-PA antigen. PAI-1 activity, however, seems to depend partially on synthesis by the liver as demonstrated by a positive correlation between PAI-1 and albumin (r = 0.33; p = 0.037). These physiologic liver functions are both progressively attenuated in severe liver damage and an increase of t-PA plasma levels and a decrease of PAI-1 might contribute to the higher fibrinolytic tendency observed in those patients.

Aged↗
PubMed1991

Fibronectin decreases the stimulatory effect of fibrin and fibrinogen fragment FCB-2 on plasmin formation by tissue plasminogen activator.

Fibronectin is a dimeric glycoprotein (Mr 440,000) involved in many adhesive processes. During blood coagulation it is bound and cross-linked to fibrin. Fibrin binding is achieved by structures (type I repeats) which are homologous to the "finger" domain of tissue plasminogen activator. Tissue plasminogen activator also binds to fibrin via the finger domain and additionally via the "kringle 2" domain. Fibrin binding of tissue plasminogen activator results in stimulation of its activity and plays a crucial role in fibrinolysis. Since fibronectin might interfere with this binding, we studied the effect of fibronectin on plasmin formation by tissue plasminogen activator. In the absence of fibrin, fibronectin had no effect on plasminogen activation. In the presence of stimulating fibrinogen fragment FCB-2, fibronectin increased the duration of the initial lag phase (= time period until maximally stimulated plasmin formation occurs) and decreased the rate of maximal plasmin formation which occurs after that lag phase mainly by increasing the Michaelis constant (Km). These effects of fibronectin were dose-dependent and were similar with single- and two-chain tissue plasminogen activator. They were also observed with plasmin-pretreated FCB-2. An apparent Ki of 43 micrograms/ml was calculated for the inhibitory effect of fibronectin when plasminogen activation by recombinant single-chain tissue plasminogen activator was studied in the presence of 91 micrograms/ml FCB-2. When a recombinant tissue plasminogen activator mutant lacking the finger domain was used in a system containing FCB-2, no effect of fibronectin was seen, indicating that the inhibitory effect of fibronectin might in fact be due to competition of fibronectin and tissue plasminogen activator for binding to fibrin(ogen) via the finger domain.

Fibrin↗
PubMed1991

Increased proteolytic activity on the surface of monocytes from patients with rheumatoid arthritis.

Studies on the expression and localization of the urokinase receptor on peripheral blood monocytes of patients with rheumatoid arthritis (RA), patients with osteoarthritis, and healthy volunteers showed a significant increase in the total number of urokinase receptors on monocytes of patients with RA, compared with osteoarthritis patients or with healthy subjects. The increase in the total number of urokinase receptors in RA was due to an elevation in the number of endogenously occupied urokinase receptors. These data provide evidence that increased proteolytic activity might contribute to the pronounced degradation of cartilage and connective tissue in patients with RA.

Adult↗
PubMed1991

Fibrinolytic parameters in spermatozoas and seminal plasma.

Urokinase-type (u-PA) and tissue-type plasminogen activator antigen (t-PA) as well as plasminogen activator-inhibitor activity were determined in seminal plasma and lysates of the respective spermatozoas in 67 ejaculate of males in infertile marriage without genito urinary pathology. U-PA was determined by a competition RIA, t-PA by an ELISA and PAI by a spectrophotometric assay. 15 patients showed normozoospermia, 11 azoospermia and 41 oligoasthenoteratozoospermia (OAT-syndrome). In lysates of spermatozoas, significantly higher levels of both plasminogenactivators and PAI were found in patients with OAT syndrome as compared to those exhibiting normozoospermia. Whereas PAI was absent in the seminal plasma of normozoospermic ejaculate, patients with azoospermia (180 +/- 13 mU/ml.) and OAT-syndrome (60 +/- 5 mU/ml.) showed high PAI levels. The similarly high values of t-PA (190.8-227.8 ng./ml.) and u-PA (19.4-32 ng./ml.) in the same compartment confirm their predominantly prostatic origin and seem to have no influence on the quality of the ejaculate.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

Plasminogen activation in diabetes mellitus: kinetics of plasmin formation with plasminogen and tissue plasminogen activator from diabetic donors.

Impaired function of the fibrinolytic system might be involved in the development of vascular disease and thromboembolic complications in diabetic patients. We studied kinetics of plasmin formation using t-PA and Pg purified from the plasma of three individual uncontrolled type I diabetic patients. Activation of diabetic Pg by normal t-PA in the presence of stimulating CNBr fragments of fibrinogen exhibited a prolonged lag phase (30 to 60 minutes) until maximally stimulated plasmin formation occurred (normal, 5 to 15 minutes) and substrate inhibition at Pg concentrations more than 10 to 30 nM. When normal Pg was activated by diabetic t-PA in the presence of CNBr-f, differentiation between lag phase and phase of maximal plasmin formation was not possible (activation time was 2 hours) and a high Km (7.5 microM) was calculated. After normalization of metabolic parameters in the patients studied, functional properties of t-PA and Pg improved. Km of diabetic t-PA returned to normal values (0.02 to 0.09 microM) and for diabetic Pg the prolonged lag phase was shortened, indicating that the functional abnormalities were reversible and possibly caused by metabolically induced changes (such as nonenzymatic glucosylation) in the t-PA or plasminogen molecule. We also studied the effect of in vitro glucosylation on functional properties of Pg. Similar, but less pronounced substrate inhibition as with diabetic Pg was observed when this glucosylated Pg was activated by t-PA in a system stimulated by CNBr fragments of fibrinogen. Therefore nonenzymatic glucosylation might explain, at least in part, functional abnormalities observed with Pg from diabetic patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1991

Hyperthermia stimulates plasminogen activator inhibitor type 1 expression in human umbilical vein endothelial cells in vitro.

The effect of exposure to hyperthermia on the fibrinolytic potential of human umbilical vein endothelial cells (HUVEC) in culture was studied. HUVEC responded to exposure to 42 degrees C with a time-dependent increase in plasminogen activator inhibitor type 1 (PAI-1) activity and antigen accompanied by a four- to fivefold increase in PAI-1 specific m-RNA and a decrease in tissue-type plasminogen activator (t-PA) antigen. The effect of 8 hours exposure to hyperthermia on PAI-1 activity and antigen could not be reversed by reexposure of the cells to 37 degrees C for 24 hours as evidenced by continuously increased amounts of PAI-1 released into the conditioned media. t-PA release, however, decreased during the 24-hour period at 37 degrees C after exposure to hyperthermia. No difference in PAI-1 antigen present in the extracellular matrix of heat treated HUVEC as compared to HUVEC kept at 37 degrees C could be found. Our data supports the idea that hyperthermia is one stress factor that influences the fibrinolytic potential of endothelial cells.

Blotting, Northern↗
PubMed1990

Matrix-bound plasminogen activator inhibitor type 1 inhibits the invasion of human monocytes into interstitial tissue.

Invasion of tissue by monocytes in the course of cellular immune reactions is a multistep process that is thought to be based on the action of urokinase type plasminogen activator (u-PA), an ubiquitous serine protease able to convert the zymogen plasminogen into the active protease plasmin. Expression and occupation of urokinase-type plasminogen activator receptors (u-PA-R) are known to be up-regulated by IFN-gamma and TNF-alpha, and endogenously occupied u-PA-R were found to be instrumental in monocyte invasiveness. We used the amnion invasion assay to investigate whether monocyte invasiveness is affected by matrix-bound plasminogen activator inhibitors (PAI) and by fluid phase u-PA. We show in this study that preincubation of amnion membranes with 1.5 U/cm2 PAI-1 decreases invasion of IFN-gamma activated monocytes by 70% compared with controls. Anti-vitronectin antibodies, which block PAI-1 binding to the matrix, abrogate the inhibitory effect of PAI-1 on monocyte invasiveness, indicating that active PAI-1 is bound via matrix-associated vitronectin. In contrast, preincubation of the amnion membrane with PAI-2 which does not bind to the extracellular matrix has no effect on monocyte invasiveness. Finally, the inhibitory action of matrix-bound PAI-1 can be abrogated by addition of 5 IU/ml u-PA to the monocytes in the invasion chamber. These findings indicate that monocyte invasiveness might be regulated not only by expression and occupation of u-PA-R but also by matrix-bound PAI-1.

Amnion↗
PubMed1990

Plasminogen activator inhibitor-1 levels in patients with chronic angina pectoris with or without angiographic evidence of coronary sclerosis.

Increased plasma levels of plasminogen activator inhibitor-1 (PAI-1) have been shown to exist in 40 to 60% of patients with stable coronary artery disease and have been suggested to be responsible for the development of coronary thrombotic complications. However, it is also discussed whether PAI-1 elevation might mainly be due to variables like increased age or to reactive mechanisms caused e.g. by the chest pain itself. To exclude age dependent or pain related influences, age-matched patients with stable angina pectoris (NHYA II) and angiographically proven coronary artery disease (CAD, n = 16) or without evidence for coronary sclerosis (variant angina, n = 10; angina-like syndrome with normal coronary angiogram, n = 5; non-CAD, n = 15) have been investigated for their plasma PAI-1 activity and t-PA antigen levels. The mean PAI activity in CAD patients (17.5 U/ml) was significantly higher than in non-CAD patients (9.6 U/ml) (p less than 0.0001). In the CAD patients no significant variation in plasma PAI-1 values could be demonstrated when related to the extent of the disease or to a history of previous myocardial infarction. t-PA antigen was also elevated in CAD patients as compared to the non-CAD group (p less than 0.02). The results suggest therefore a strong correlation between coronary artery disease itself and elevated levels of components of the plasma fibrinolytic system.

Angina Pectoris↗