The circulatory half-lives of α -profibrin and α-fibrin monomer, and comparisons with other fibrin(ogen) derivatives

2003 ◽  
Vol 89 (01) ◽  
pp. 48-52 ◽  
Author(s):  
Patricia DiBello ◽  
John Shainoff
Keyword(s):  
Vascular Disease ◽  
Exponential Decay ◽  
Half Life ◽  
Decay Curve ◽  
Human Fibrinogen ◽  
Extravascular Space ◽  
Plasma Decay ◽  
Exponential Decay Curve ◽  
Fibrin Monomer ◽  
Double Exponential

SummaryPrevious studies showed that α-fibrin monomer (lacking both A-fibrinopeptides, FPA) is normally cleared from the circulation before it assembles into a clot. Recent studies indicate that substantial quantities of an intermediate, α-profibrin lacking only one of the two FPA are produced in the course of conversion of human fibrinogen to fibrin. Since clearance of the α-fibrin monomer is saturable and receptor mediated, the extent to which α-profibrin or other fibrin(ogen) derivatives might compete for monomer uptake was deemed important. We compared plasma decay of injected human α-fibrin, fibrinogen, and α-profibrin in rabbits using rabbit anti-human fibrinogen for assays. The circulatory half-life of human α-fibrin monomer was short (t1/2 = 2.3 h) and followed a simple exponential decay curve, as anticipated from clearance of rabbit α-fibrin. It was absorbed as fast as it permeated the extravascular space with no redistribution. Human fibrinogen had a long half-life (t1/2 = 39.5 h), calculated from the double exponential plasma decay curves (redistribution + catabolism) observed over 28 h. The α-profibrin had an intermediary half-life (t1/2 = 11 h) determined from double exponential decay curves. Since redistribution accompanied the slow clearance of α-profibrin, its binding by the fibrin receptor(s) must be weak, probably too weak to compete with the clearance of α-fibrin monomer. The initial production of α-fibrin monomer is only partially dependent on prior formation of α-profibrin, as recently shown. Thus, it is the slow clearance and the weak competition from α-profibrin that underlie the occurrence of substantial levels of α-profibrin unaccompanied by detectable levels of α-fibrin monomer in many subjects with vascular disease.

Turnover and Distribution of 131Iodine-Labelled Human Fibrinogen

1964 ◽  
Vol 11 (02) ◽  
pp. 404-422 ◽  
Author(s):  
Annemarie Amris ◽  
C. J Amris
Keyword(s):  
Body Weight ◽  
Cancer Patient ◽  
Distribution Ratio ◽  
Half Life ◽  
Fibrinolytic Activity ◽  
The Other ◽  
Turnover Rates ◽  
Human Fibrinogen ◽  
Coagulation Defects ◽  
Fractional Turnover

Summary14 patients (5 diabetics with arteriosclerotic complications, 4 patients with thrombo-embolic disease, 4 with cirrhosis, coagulation defects and increased fibrinolytic activity, and 1 cancer patient) and 3 control patients were subjected to turnover studies with 13iodine labelled human fibrinogen.Half-life times in the control patients were found to be 4 days, the fractional turnover rates 19–23 per cent, of intravascular fibrinogen per day, and the absolute turnover 0.02 to 0.06 gm per day per kg. body weight. The other patient’s half-life times and turnover rates varied considerably from 0.9–5.5 days, 13–160 per cent, per day of intravascular fibrinogen and 0.02–0.4 gm per day per kg. body weight respectively.As fibrinogen unlike other proteins subjected to turnover studies, is converted to fibrin, it is not possible to measure the true intra-extravascular distribution ratio of fibrinogen. But intravascular fibrinogen could be approximated to constitute 68–99 per cent, of the total fibrinogen. There is justification in believing that fibrinogen is degradated through a continuous coagulation in equilibrium with fibrinolysis, and that the organism contains a greater mass of fibrin, the “fibrin pool”. Considerations of the turnover mechanism can however only be hypothetical.

Tree windthrow and forest soil turnover

1989 ◽  
Vol 19 (3) ◽  
pp. 386-389 ◽  
Author(s):  
D. A. Norton
Keyword(s):  
Forest Soil ◽  
Exponential Decay ◽  
Half Life ◽  
Soil Development ◽  
Turnover Time ◽  
Important Influence ◽  
Plant Distribution ◽  
Canopy Trees ◽  
Decay Model ◽  
Exponential Decay Model

Soil turnover as a result of tree windthrow has an important influence on soil development and plant distribution in forests. Estimates of the time needed for soil turnover in a given area are often made, but unless these take into account the potential for reestablishment of canopy trees onto sites previously affected by windthrow, they are likely to substantially underestimate turnover time. Soil turnover is not a regular, uniform process, but rather results in a mosaic of soils with different turnover histories. Because soil turnover follows an exponential decay model, some area of soil will never be turned over. As it is therefore not possible to define the time when all the soil in an area has been turned over, it is proposed that soil turnover half-life (the time at which half the soil has been turned over) be used as a measure of soil turnover.

Influence of the Carbohydrate Moiety in the Dysfibrinogenemia of Liver Disease

1979 ◽  
Author(s):  
J. Martinez ◽  
J.E. Palascak
Keyword(s):  
Liver Disease ◽  
Sialic Acid ◽  
Acid Content ◽  
Similar Distribution ◽  
Thrombin Time ◽  
Sialic Acid Content ◽  
Human Fibrinogen ◽  
Fibrin Monomer ◽  
Sds Page ◽  
Functional Defect

Human fibrinogen is a glycoprotein which contains 6 sialic acid residues per molecule. Enzymatic removal of sialic acid modifies its functional properties as indicated by shortening of the thrombin time due to enhanced asialofibrin monomer polymerization. The abnormal fibrinogen of liver disease contains an Increased amount of sialic acid and is functionally characterized by impaired fibrin monomer polymerization. The prolongation of its thrombin time correlates with its increased sialic acid content. Enzymatic cleavage of the excess sialic acid results in normalization of the thrombin time and the fibrin monomer polymerization. Quantitative labelling of sialic acid with (3H) demonstrates increased labelling of the abnormal fibrinogen compared to normal fibrinogen reflecting the sialic acid content of the abnormal molecule. The radioactivity of the labelled normal and abnormal fibrinogens after reduction and SDS-PAGE was limited to the Bβ and γ chains with 60% of the radioactivity in the Bβ chain and 40% in the γ chain. A similar distribution of radioactivity was found after removal of the excess sialic acid from the respective chains. β-galactose was also increased in the abnormal fibrinogen and paralleled the increase in sialic acid. These studies indicate that sialic acid is distributed normally on the chains of the abnormal fibrinogen of liver disease, but its increased content is responsible for the functional defect of the protein.

scholarly journals A gamma Gly-268 to Glu substitution is responsible for impaired fibrin assembly in a homozygous dysfibrinogen Kurashiki I

Blood ◽  
1996 ◽  
Vol 87 (11) ◽  
pp. 4686-4694 ◽  
Author(s):  
K Niwa ◽  
M Takebe ◽  
T Sugo ◽  
Y Kawata ◽  
J Mimuro ◽  
...  
Keyword(s):  
Tissue Type ◽  
Factor Xiiia ◽  
Cross Linking ◽  
Fibrin Gel ◽  
Functional Abnormality ◽  
Human Fibrinogen ◽  
Fibrin Monomer ◽  
Longitudinal Association ◽  
Self Association ◽  
A Site

A new type of gamma Gly-268 (GGA) to Glu (GAA) substitution has been identified in a homozygous dysfibrinogen by analyses of the affected polypeptide and its encoding gene derived from a 58 year-old man manifesting no major bleeding or thrombosis. The functional abnormality was characterized by impaired fibrin assembly most likely due to failure to construct properly aligned double-stranded fibrin protofibrils. This presumption was deduced from the following findings: (1) Factor XIIIa-catalyzed cross-linking of the fibrin gamma-chains progressed in a normal fashion, indicating that the contact between the central E domain of one fibrin monomer and the D domain of another took place normally; (2) Nevertheless, factor XIIIa-catalyzed cross-linking of the fibrinogen gamma-chains was obviously delayed, suggesting that longitudinal association of D domains of different fibrin monomers, ie, D:D association was perturbed; (3) Plasminogen activation catalyzed by tissue-type plasminogen activator was not as efficiently facilitated by polymerizing fibrin monomer derived from the patient as by the normal counterpart. Therefore, gamma Gly-268 would not be involved in the 'a' site residing in the D domain, which functions as a complementary binding site with the thrombin-activated 'A' site in the central E domain, but would be rather involved in the D:D self association sites recently proposed for human fibrinogen. Thus, the gamma Glu-268 substitution newly identified in this homozygous dysfibrinogen seems to impair proper alignment of adjacent D domains of neighboring fibrin molecules in the double-stranded fibrin protofibril, resulting in delayed fibrin gel formation.

scholarly journals δ-Aminolaevulinate dehydratase, the regulatory enzyme of the haem-biosynthetic pathway in Neurospora crassa

1972 ◽  
Vol 129 (1) ◽  
pp. 31-37 ◽  
Author(s):  
S. Muthukrishnan ◽  
K. Malathi ◽  
G. Padmanaban
Keyword(s):  
Neurospora Crassa ◽  
Half Life ◽  
Biosynthetic Pathway ◽  
Decay Curve ◽  
Feedback Inhibition ◽  
Regulatory Function ◽  
Protein Inhibitor ◽  
Biphasic Pattern ◽  
Iron Deficient

The activity of δ-aminolaevulinate dehydratase is very low in the mould Neurospora crassa compared with the activities detected in bacterial and animal systems. The enzyme is inducible in iron-deficient cultures by addition of iron and is repressed by protoporphyrin. The properties of the purified enzyme indicate its allosteric nature and susceptibility to feedback inhibition by coproporphyrinogen III. Neurospora extracts also contain a protein inhibitor of the enzyme and a small-molecule activator, which appears to be associated with the enzyme. The regulatory function of this enzyme in vivo is correlated with the accumulation of δ-aminolaevulinic acid in normal cultures of N. crassa. The decay curve of the iron-induced enzyme in vivo shows a biphasic pattern, with one of the components showing a half-life of 4–5 min.

Double Exponential Decay of Imprisoned Resonance Radiation

1971 ◽  
Vol 49 (1) ◽  
pp. 90-101 ◽  
Author(s):  
J. S. Deech ◽  
W. E. Baylis
Keyword(s):  
Exponential Decay ◽  
Linear Polarization ◽  
Incident Radiation ◽  
Average Degree ◽  
Resonance Radiation ◽  
Quantum Mechanical ◽  
Scattering Process ◽  
Double Exponential ◽  
Degree Of Coherence ◽  
Experimental Values

The decay of imprisoned resonance radiation in mercury has been studied using delayed-coincidence techniques. It is characterized by two exponentially decaying components, whose relative amplitudes depend on the direction of linear polarization of the incident radiation. When this direction makes an angle of 54.7° to the direction of observation, only one component is observed. Classical and quantum-mechanical theories are presented which show that the geometry of the scattering cell plays an important role at low atomic densities. Experimental values are presented for the average degree of coherence transferred in the scattering process and for the natural lifetime of the 63P1 state of mercury.

Activities: An Interest in Radioactivity

1996 ◽  
Vol 89 (3) ◽  
pp. 209-230
Author(s):  
Jane B. Kennedy
Keyword(s):  
Exponential Decay ◽  
Exponential Growth ◽  
Half Life ◽  
Core Curriculum ◽  
Equal Access ◽  
Compound Interest

Introduction: This activity explores exponential growth and decay, emphasizing the paired concepts of doubling and half-life. Exponential growth is derived from actual computations to obtain compound interest, whereas exponential decay is modeled by the use of “radioactive” dice. The activity is based on the concept of the differentiated core curriculum, which asserts that all students should be guaranteed equal access to the same curricular topics but recognizes that all students may not explore the content to the same depth or at the same level of formalism.

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