A Method to Correct for the Continuing Activation during the Second Stage in a Two-Stage Assay

1968 ◽  
Vol 19 (01/02) ◽  
pp. 161-168
Author(s):  
W Berg

SummaryIn coagulation and fibrinolysis, kinetic data are difficult to obtain with ordinary quantitative methods because no simple means are available to stop the reaction before the determination of the activity formed.This work describes how to calculate, from the data recorded, the amount of activity at the moment the determination is started.A formula is given for a zero, a first and a second-order reaction.The method is exemplified by urokinase activation of plasminogen into plasmin. The determination of the plasmin activity is done by means of the lysis time method.

1965 ◽  
Vol 14 (01/02) ◽  
pp. 127-144 ◽  
Author(s):  
W Berg ◽  
K Korsan-Bengtsen ◽  
J Ygge

SummaryThe lysis time method for the determination of plasminogen has been investigated using plasminogen-free thrombin and fibrinogen preparations.The experiments have shown that the lysis of a fibrin clot is the result of two consecutive reactions: the formation of fibrin which proceeds as a first order reaction and the degradation of fibrin which proceeds as a zero order reaction. Plasminogen is activated in a separate reaction. If the rate of the fibrin formation is much greater than the rate of degradation, the lysis of the fibrin clot is approximately of zero order in fibrin. The lysis time will then be inversely proportional to the plasmin concentration and proportional to the fibrinogen concentration. In a double logaritmic system the correlation between lysis time and plasmin activity is a straight line with a slope of 135°.Plasminogen is rapidly activated with streptokinase. Maximal activation is obtained only with a certain streptokinase concentration. Higher concentrations inactivate plasmin and with lower concentrations, the maximal activity is never reached. A spontaneous inactivation is seen after about 30 minutes. With urokinase, a higher maximal plasminogen activity is obtained than with streptokinase. Urokinase in higher concentrations does not inactivate plasmin.A standard assay for determination of plasminogen by the lysis time method has been worked out and is based on these results.


1966 ◽  
Vol 16 (01/02) ◽  
pp. 001-017 ◽  
Author(s):  
W Berg ◽  
K Korsan-Bengtsen ◽  
J Ygge

SummaryA one-stage lysis time system containing fibrinogen, streptokinase, thrombin, and a known, small amount of plasminogen was used to determine plasminogen in plasma.The known amount of plasminogen was added to the system in order to keep the lysis times relatively short when a highly diluted plasma was tested. High dilutions of plasma were used to reduce the influence of the plasma inhibitors.The calculation of the plasminogen concentration was made on the basis of the correlation: “plasminogen = fibrinogen/lysis time” which was valid in the system. The method allowed determination of plasminogen in plasma with varying fibrinogen concentrations, as the fibrinogen concentration in plasma was considered in the calculation.The presence of “spontaneous” plasmin activity in the plasma did not influence the plasminogen determination. Estimated by this method, the plasminogen content in plasma from 32 blood donors aged 25-45 years was 13.1 ±2.4 casein u/ml. The error of a single determination was 0.3 casein u/ml. The plasminogen content in plasma, determined with the present method, is about 3-4 times higher than the content found when a caseinolytic method is used.


2000 ◽  
Vol 65 (12) ◽  
pp. 857-866
Author(s):  
Mladjen Micevic ◽  
Slobodan Petrovic

The alcoholysis of 1,2,2-trimethylpropyl-methylfluorophosphonate (soman) was examined with a series of alkoxides and in corresponding alcohols: methanol, ethanol, 1-propanol, 2-propanol, 2-methoxyethanol and 2-ethoxyethanol. Soman reacts with the used alkoxides in a second order reaction, first order in each reactant. The kinetics of the reaction between 1,2,2-trimethylpropyl-methylfluorophosphonate and ethanol in the presence of diethylenetriamine was also examined. A third order reaction rate constant was calculated, first order in each reactant. The activation energy, frequency factor and activation entropy were determined on the basis of the kinetic data.


1930 ◽  
Vol 3 (4) ◽  
pp. 650-659
Author(s):  
John T. Blake

Abstract A procedure for the determination of combined selenium in rubber has been evolved. The rate of combination of selenium and rubber has been ascertained under certain conditions and shown to follow a first-order equation. A minimum value for the molecular weight of rubber has been estimated. The formation of hard rubber under chosen experimental conditions has been put on a mathematical basis and has been shown to follow a second-order reaction. The soft- and hard-rubber reactions have been shown qualitatively to be successive reactions and the function of accelerators has been discussed. The theory explains the anomalous results obtained by previous investigators.


2020 ◽  
Vol 30 (1) ◽  
pp. 27-33
Author(s):  
I. A. Burmaka ◽  
◽  
A.V. Yanchetskyy ◽  
◽  
◽  
...  

In the article is specified, that a decision-making process contains the following stages: control of environment, including relative position and parameters of relative motion, the exposure of situation of rapprochement of vessels, in the case of rapprochement of vessels it is necessary to produce estimation of degree of his danger, at dangerous rapprochement is needed to define the type of co-operation, depending on the degree of danger of situation of rapprochement the choice of strategy of divergence is produced. On the first stage of process of decision-making surrounding mobile objects come to light by ARPA or AIS, for which is measured parameters of motion and relative position. It is shown that on the second stage of process of decision-making, using the measured parameters, it is necessary to expect the value of speed of change of distance between vessels, taking into account that at its negative value ships are drawn together. On the third stage of process of decision-making at rapprochement of vessels estimation of degree of his danger is produced, what development of situation of rapprochement to the moment of time of their shortest rapprochement is forecast for. On the fourth stage of decision-making it is necessary to define the type of cooperation of the drawn together vessels, taking into account principle their process control of divergence. It is especially substantial for principle of locally-independent management by the process of divergence, when coordination of co-operation of vessels at dangerous rapprochement is needed. The fifth stage of decision-making is characterized by the choice of strategy of divergence, thus at the locally-independent process control of divergence the choice of strategy of divergence is produced depending on the degree of danger of situation of rapprochement, by the standard maneuver of divergence or for excessive rapprochement of vessels it is necessary to use the maneuver of urgent divergence. In work as the index of efficiency of the analytical collision avoidance systems vessels probability of safe completion of process of divergence, which is work of probabilities of successful end of stages of process of decision-making on the choice of strategy of divergence, is offered. It is shown that first three stages of decision-making on the choice of strategy of divergence are characterized by general probability of absence of danger of collision on condition that distance of the shortest rapprochement is equal to the set minimum-possible distance of rapprochement. For determination of the mentioned probability the error of distance of the shortest rapprochement is considered and expression is got for the closeness of its distributing. To that end collected dependence of error of distance of the shortest rapprochement from the errors of measuring of distance and bearing. By the got expression for the closeness of distributing of error of distance of the shortest rapprochement probability is certain of that at equality of distance of the shortest rapprochement with limit-possible distance of rapprochement there will not be the collision.


1997 ◽  
Vol 2 (3) ◽  
pp. 52-66 ◽  
Author(s):  
T. Scheff

In this article, I describe the morphological method as a new stage of inquiry, between the first stage, qualitative methods, and the third, quantitative methods. The proposed second stage involves microscopic examination of single instances, and, if more than one instance is available, comparisons with each other. This method is particularly useful for the objective determination of meaning, a crucial problem for the human sciences. Because the determination of meaning is complex, yet taken for granted, I describe its intricacy. The new method also can be used to generate micro-macro theories, perhaps the next stage in the development of the human sciences. To form a bridge between qualitative and quantitative methods, which are increasingly separated, part/whole morphology can lead to research which is valid, reliable, and cost-efficient. Qualitative methods involve exploration, the first step in inquiry. Quantitative methods involve verification, the last step. Although preliminary exploration is usually necessary and always helpful, exploration requires verification. The weakness of verification alone is that since experiments and other standardized formats (such as the scale and the standardized interview) are narrow and rigid, one needs to have considerable knowledge before an adequate testing procedure can be designed. Qualitative methods are like wide-angled lenses with little depth; quantitative methods are as narrow as using the wrong end of a telescope. Furthermore, since verification is costly and time-consuming, only hypotheses and theories should be tested which are not only plausible, but are likely to be general and important. The procedure outlined here is more labourious than most qualitative studies, but it is also more cost-efficient than those which automatically seek verification. The approach outlined here can be seen as the next step after what Giddens (1984) has called ‘instantiation’. He asked for actual instances of the behaviour described by any theory. His call, in turn, can be seen as a reiteration of Max Weber's (1947) insistence that the task of sociology is to reduce concepts about society to ‘understandable action, that is, without exception, to the actions of participating individuals (persons).


1974 ◽  
Vol 31 (03) ◽  
pp. 439-451
Author(s):  
Robert H. Yue ◽  
Toby Starr ◽  
Menard M. Gertler

SummaryA simple quantitative method for the determination of antithrombin III in plasma is described. It is based on the preferential precipitation of plasma antithrombin activities by a chemical compound 2,5-diamino-7-ethoxyacridin lactate (rivanol). When the incubation time of plasma with rivanol took place within 0.5 and 2 hours under specifically controlled experimental conditions, rivanol precipitated α2-macro-globulin selectively and quantitatively without any effect on antithrombin III. In the presence of rivanol, the inhibition of thrombin by plasma antithrombin III followed a second-order reaction with a rate constant of 80 1/M/sec. In this assay procedure, only the initial thrombin activity and the 30 minutes residual thrombin activity are required to evaluate the amount of antithrombin III present in the plasma quantitatively. “With proper routine laboratory care, this assay system was found to be accurate and reproducible.


1965 ◽  
Vol 14 (03/04) ◽  
pp. 508-518 ◽  
Author(s):  
G. G Neri Serneri ◽  
P. L Rossi Ferrini ◽  
P Paoletti ◽  
A Panti ◽  
G D’Ayala Valva

SummaryThe effects of bradykinin on coagulation and fibrinolysis have been studied both “in vitro” and “in vivo” in man. “In vitro” bradykinin employed at different concentrations does not affect the coagulation and fibrinolysis processes in any appreciable way. Bradykinin, intraarterially injected in man in the dose of 10 y, does not modify coagulation studied both with global investigations (thrombelastogram, recalcification time) and with analytical researches (Quick’s time, activation test of intrinsic thromboplastin, thrombin generation test and thromboplastin test, thrombin time, determination of antithrombin II and III). Bradykinin instead produces an activation of fibrinolysis both in the thrombelastographic investigation and in the lysis time of euglobulins. The decrease in the activity of the proactivator and of plasminogen supports our view that bradykinin produces an activation of the fibrinolytic system by liberating tissue kinases which act on the proactivator. The authors have discussed the physiological and physiopathological significance of the observed findings.


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