Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

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Characteristics of Factor VIII Related Protein in Different Types of von Willebrand’s Disease

10.1055/s-0039-1680547 ◽

1977 ◽

Author(s):

A. L. Bloom ◽

I. R. Peake

Keyword(s):

Factor Viii ◽

Dose Response ◽

Related Protein ◽

Con A ◽

Response Curves ◽

Von Willebrand's Disease ◽

Normal Plasma ◽

Different Types ◽

Dose Response Curves ◽

Antigenic Reactivity

The antigenic, biochemical and biological reactions of factor VIII related protein were studied in normal plasma and in the plasma of patients with different types of von Willebrand’s disease (vWd). Antigenic reactivity was compared using the Laurell electroimmunoassay (LA) and an immunoradiometric assay (IRMA). Biochemical characteristics of factor VIII related antigen (FVIIIRAG) were compared by examining its electrophoretic mobility (EM) on two dimensional crossed Immunoelectrophoresis (2DCIE) and by determining its precipitation properties with the glycoprotein precipitant concanavalin A (Con A),Biological reactions were compared using the ristocetin cofactor (RiCoF) assay on fixed platelets and by determining procoagulant factor VIII (FVIIIC). In normal plasma the levels of FVIIIRAG measured by LA correlated with the IRMA and dose response curves were parallel. At a concentration of lmg/ml Con A completely precipitated FVIIIRAG. The biological activities, RiCoF anú FVIIIC, were normal and correlated with those of FVIIIRAG. In patients with vWd in whom levels of FVIIIRAG by LA were normal the EM by 2DCIE was increased. In these patients the dose-response curves of the IRMA were not parallel to normal, FVIIIRAG was not precipitated normally by Con A and the RiCoF activity was reduced. Similar findings were observed in some patients with “typical” intermediate vWd in whom the plasma levels of FVIIIRAG were too low to determine EM, In other patients with vWd the dose response curves of the IRMA were parallel. The results suggest that the non-parallel dose response curves of the IRMA were due to the presence of abnormal FVIIIRAG and were consistent with variations of antigenic reactivity or binding sites in these patients.

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Steady-state enzyme kinetics with high-affinity substrates or inhibitors. A statistical treatment of dose–response curves

Biochemical Journal ◽

10.1042/bj1350101 ◽

1973 ◽

Vol 135 (1) ◽

pp. 101-107 ◽

Cited By ~ 52

Author(s):

Peter J. F. Henderson

Keyword(s):

Steady State ◽

Dose Response ◽

Statistical Treatment ◽

Enzyme Concentration ◽

Bacterial Respiration ◽

Maximal Effect ◽

Response Curves ◽

Kinetic Measurements ◽

Lending Library ◽

Dose Response Curves

A statistical treatment of steady-state enzyme kinetic measurements is described that allows for depletion of free substrate or free inhibitor concentrations owing to significant binding to the enzyme. Vmax., Km or Ki, enzyme concentration, the concentration of substrate or inhibitor required for a half-maximal effect and standard errors of these parameters can be calculated from dose–response measurements; the concentration of each component of the system may be estimated also. The statistically best values of the parameters are used to convert dose–response curves into convenient linear forms. The method is applied to dose–response measurements of hydroxyquinoline N-oxide inhibition of bacterial respiration and aminopterin inhibition of dihydrofolate reductase. Two FORTRAN programs for this method have been deposited as Supplementary Publication no. SUP 50019 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies may be obtained on the terms indicated in Biochem. J. (1973) 131, 5.

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Computer modelling of estrogenic transcriptional activation can account for different types of dose-response curves of estrogens

The Journal of Steroid Biochemistry and Molecular Biology ◽

10.1016/0960-0760(93)90291-4 ◽

1993 ◽

Vol 46 (2) ◽

pp. 163-176 ◽

Cited By ~ 7

Author(s):

S. Dove ◽

H. Schönenberger

Keyword(s):

Dose Response ◽

Transcriptional Activation ◽

Computer Modelling ◽

Response Curves ◽

Different Types ◽

Dose Response Curves

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Fibrinolysis in Normal Subjects - Comparison Between Plasminogen Activator Inhibitor and Other Components of the Fibrinolytic System

Thrombosis and Haemostasis ◽

10.1055/s-0038-1642775 ◽

1988 ◽

Vol 59 (02) ◽

pp. 299-303 ◽

Cited By ~ 40

Author(s):

Grazia Nicoloso ◽

Jacques Hauert ◽

Egbert K O Kruithof ◽

Guy Van Melle ◽

Fedor Bachmann

Keyword(s):

Plasminogen Activator ◽

Fibrinolytic Activity ◽

Plasminogen Activator Inhibitor ◽

Venous Occlusion ◽

Venous Stasis ◽

Plasminogen Activator Inhibitor 1 ◽

Plate Assay ◽

Fibrin Plate ◽

Activator Inhibitor ◽

Pai 1

SummaryWe analyzed fibrinolytic parameters in 20 healthy men and 20 healthy women, aged from 25 to 59, before and after 10 and 20 min venous occlusion. The 10 min post-occlusion fibrinolytic activity measured directly in diluted unfractionated plasma by a highly sensitive 125I-fibrin plate assay correlated well with the activity of euglobulins determined by the classical fibrin plate assay (r = 0.729), but pre-stasis activities determined with these two methods did not correlate (r = 0.084). The enhancement of fibrinolytic activity after venous occlusion was mainly due to an increase of t-PA in the occluded vessels (4-fold increase t-PA antigen after 10 min and 8-fold after 20 min venous occlusion). Plasminogen activator inhibitor (PAI) activity and plasminogen activator inhibitor 1 (PAI-1)1 antigen levels at rest showed considerable dispersion ranging from 1.9 to 12.4 U/ml, respectively 6.9 to 77 ng/ml. A significant increase of PAI-1 antigen levels was observed after 10 and 20 min venous occlusion. At rest no correlation was found between PAI activity or PAI-1 antigen levels and the fibrinolytic activity measured by 125I-FPA. However, a high level of PAI-1 at rest was associated with a high prestasis antigen level of t-PA and a low fibrinolytic response after 10 min of venous stasis. Since the fibrinolytic response inversely correlated with PAI activity at rest, we conclude that its degree depends mainly on the presence of free PAI.

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BIOASSAY OF THYROID HORMONE USING HYPOTHYROID TADPOLES

Acta Endocrinologica ◽

10.1530/acta.0.0410143 ◽

1962 ◽

Vol 41 (1) ◽

pp. 143-153 ◽

Cited By ~ 2

Author(s):

U. Henriques

Keyword(s):

Thyroid Hormone ◽

Dose Response ◽

Developmental Rate ◽

Response Curves ◽

Sodium Salts ◽

Dose Response Curves

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.

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Dose Response Curves for Microwave Ablation in the Cardioplegia-Arrested Porcine Heart

The Heart Surgery Forum ◽

10.1532/hsf98.20051011 ◽

2005 ◽

Vol 8 (4) ◽

pp. E269-E274 ◽

Cited By ~ 1

Author(s):

Sydney L. Gaynor ◽

Gregory D. Byrd ◽

Michael D. Diodato ◽

Yosuke Ishii ◽

Anson M. Lee ◽

...

Keyword(s):

Dose Response ◽

Microwave Ablation ◽

Response Curves ◽

Porcine Heart ◽

Dose Response Curves

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Modeling Nonmonotonic Dose-Response Curves

10.21236/ada391664 ◽

2001 ◽

Author(s):

Quinton J. Nottingham ◽

Jeffrey B. Birch ◽

Barry A. Bodt

Keyword(s):

Dose Response ◽

Response Curves ◽

Dose Response Curves

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Comment Concerning the Effects of Light Intensity on Melatonin Suppression in the Review “Light Modulation of Human Clocks, Wake, and Sleep” by A. Prayag et al.

Clocks & Sleep ◽

10.3390/clockssleep3010011 ◽

2021 ◽

Vol 3 (1) ◽

pp. 181-188

Author(s):

Peter Bracke ◽

Eowyn Van de Putte ◽

Wouter R. Ryckaert

Keyword(s):

Phase Shift ◽

Light Intensity ◽

Dose Response ◽

Light Modulation ◽

Response Curves ◽

Practical Applications ◽

Circadian Phase ◽

Melatonin Suppression ◽

Dose Response Curves ◽

Circadian Phase Shift

Dose-response curves for circadian phase shift and melatonin suppression in relation to white or monochromatic nighttime illumination can be scaled to melanopic weighed illumination for normally constricted pupils, which makes them easier to interpret and compare. This is helpful for a practical applications.

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