Kinetic Aspects of the Interaction of Blood Clotting Enzymes

1965 ◽  
Vol 13 (01) ◽  
pp. 155-175 ◽  
Author(s):  
H. C Hemker ◽  
P.W Hemker ◽  
E. A Loeliger
Keyword(s):  
Kinetic Analysis ◽  
Enzyme Kinetics ◽  
Blood Clotting ◽  
Enzyme System ◽  
Enzyme Kinetic ◽  
Clotting Time ◽  
Standard Methods

SummaryApplication of the methods of enzyme-kinetic analysis to the results of clotting tests is feasible and can yield useful results. However, the standard methods of enzyme kinetics are not applicable without modifications imposed by the peculiarities of the blood-clotting enzyme system. The influence of the following complicating circumstances is calculated :1. Substrate is not present in excess.2. Only relative measures exist for concentrations of substrate or enzymes.3. Enzymes and substrates are often added together.4. Reagents are not pure.5. Clotting-time is our only measure for clotting-velocity.Formulas are deduced, which makes it possible to recognize the effect of these complications.

Kinetic Aspects of the Interaction of Blood Clotting Enzymes

1968 ◽  
Vol 19 (03/04) ◽  
pp. 364-367 ◽  
Author(s):  
H. C Hemker ◽  
P. W Hemker
Keyword(s):  
Enzyme Kinetics ◽  
Blood Clotting ◽  
Competitive Inhibition ◽  
Competitive Inhibitor ◽  
Kinetics Of

SummaryThe enzyme kinetics of competitive inhibition under conditions prevailing in clotting tests are developed and a method is given to measure relative amounts of a competitive inhibitor by means of the t — D plot.

The Blood-Clotting Time in Spent Silver Salmon, Oncorhynchus kisutch (Walbaum)

Copeia ◽  
1950 ◽  
Vol 1950 (2) ◽  
pp. 150 ◽  
Author(s):  
Max Katz ◽  
Morris Southward
Keyword(s):  
Blood Clotting ◽  
Oncorhynchus Kisutch ◽  
Clotting Time ◽  
Blood Clotting Time

Cellular Regulation of the Metabolism of Androgens in Rat Oral Mucosa. III. Activation of Δ4-3-ketosteroid-5α-A Ring Reductase Enzyme System by 5,5-Diphenylhydantoin

1979 ◽  
Vol 58 (2) ◽  
pp. 642-645 ◽  
Author(s):  
Jozef Vittek ◽  
Gary G. Gordon ◽  
Sydney C. Rappaport ◽  
A. Louis Southren
Keyword(s):  
Oral Mucosa ◽  
Enzyme System ◽  
Kinetic Studies ◽  
In Vitro Assay ◽  
Enzyme Kinetic ◽  
Cellular Regulation ◽  
Vitro Assay ◽  
Allosteric Mechanism

Systemic pretreatment of rats with diphenylhydantoin (DPH) or its addition into an in vitro assay increases 5α-reduction of testosterone by the oral mucosa. Enzyme kinetic studies showed that DPH binds to the enzyme and probably activates it by an allosteric mechanism.

DICOUMAROL STUDIES: I. ORAL ADMINISTRATION OF SYNTHETIC DICOUMAROL TO VARIOUS CLASSES OF SHEEP AND CATTLE

1963 ◽  
Vol 43 (2) ◽  
pp. 344-352 ◽  
Author(s):  
J. H. Linton ◽  
B. P. Goplen ◽  
J. M. Bell ◽  
L. B. Jaques
Keyword(s):  
Vitamin K ◽  
Blood Clotting ◽  
Post Partum ◽  
Late Pregnancy ◽  
Cumulative Effects ◽  
Factor Vii ◽  
Factor X ◽  
Clotting Time ◽  
Sodium Bisulphite ◽  
Bull Calves

In one experiment 3 steers, 4 bull calves and 4 wether lambs were orally administered 2 milligrams dicoumarol per kilogram body weight and blood-clotting time measurements were made over a 4-day period. All animals responded to the dicoumarol but differences were evident between sheep and cattle; sheep were apparently more tolerant of the drug.The ’one-stage prothrombin’ test was more reliable and sensitive than the clotting tests employed for factor VII, factor X and prothrombin concentration.In a second experiment, 16 ewes in late pregnancy were fed rations containing 0 to 30 p.p.m. of synthetic dicoumarol and vitamin K3 as a cross treatment. Evidence of abnormal clotting power of ewe blood was observed in ewes fed diets containing 10 p.p.m. of dicoumarol. There was some indication of cumulative effects at this level after 32 days on test. At intake levels of 20 and 30 p.p.m. clotting times were affected more markedly and some ewes exhibited extended bleeding times after 2 to 4 weeks on test. No unusual hemorrhaging occurred at parturition. In general, the lambs’ blood did not reflect the pre- or post-partum dicoumarol intake of their mothers but a few lambs, as in the case of the ewes, exhibited low tolerance for dicoumarol without showing much disturbance in terms of clotting time. A large single oral dose of menadione sodium bisulphite demonstrated the effectiveness of vitamin K3 as an antidote. However, vitamin K3 as a ration supplement at 12 milligrams per pound feed failed to protect ewes against the effects of dicoumarol.

Autoprothrombin II of human origin

1961 ◽  
Vol 201 (4) ◽  
pp. 660-662 ◽  
Author(s):  
Orhan N. Ulutin ◽  
J. Frederic Johnson ◽  
Walter H. Seegers
Keyword(s):  
Whole Blood ◽  
Blood Clotting ◽  
Human Origin ◽  
Clotting Time ◽  
Generation Test ◽  
Blood Clotting Time

Autoprothrombin II activity develops when prothrombin preparations of human origin are activated with purified thrombin at pH 8.2. Early during the activation an inhibitor seems to form. Concentrates of the autoprothrombin II can replace serum in the thromboplastin generation test provided platelets are used in the test, but not if a soy bean phosphatide is used. Dogs were given Coumadin in doses that lowered their own autoprothrombin concentration practically to zero. Then while continuing with use of the drug some purified autoprothrombin II was infused intravenously. This was tolerated very well. The autoprothrombin II concentration stayed at normal for 7 hr. In 24 hr none remained. The infusion was also followed by a shortening of the whole blood clotting time.

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