The Statistical Theory of the Elasticity of Rubber

1939 ◽  
Vol 12 (1) ◽  
pp. 56-63
Author(s):  
H. Dostal
Keyword(s):  
Finite Size ◽  
Point Of View ◽  
Chain Molecule ◽  
Tension Zone ◽  
Single Chain ◽  
Chain Molecules ◽  
Theoretical Investigations ◽  
Statistical Behavior ◽  
Coefficient Of Elasticity ◽  
Insight Into

Abstract The theoretical investigations of various authors, with the aid of which the physical properties of rubber-like substances have become understood on a basis of intermolecular statistics, have not, at least from a quantitative point of view, kept pace with investigations relating to kinetic theories of gases. However, only the facts of rubber elasticity have become understood, and to point out one case, the coefficient of elasticity cannot be derived, and much less the tension zone, beyond proportionality. The reason for this is that, although statistics of a single chain molecule of finite size can be compiled, the bond of the chain molecule and, as a further instance, the behavior of a molecule of infinite size formed by interlacing have not been clearly understood up to the present time. Consequently, it has been possible to gain an insight into the statistical behavior of individual chain molecules much more easily than into that of a piece of rubber, and therefore to deduce with less difficulty theories of the viscosity of high molecular solutions and similar systems. In the case of rubber, progress has been more difficult in explaining the effects which take place.

Regulation of the single-chain urokinase–urokinase receptor complex activity by plasminogen and fibrin: novel mechanism of fibrin specificity

Blood ◽  
2005 ◽  
Vol 105 (3) ◽  
pp. 1021-1028 ◽  
Author(s):  
Abd Al-Roof Higazi ◽  
Feras Ajawi ◽  
Sa'ed Akkawi ◽  
Edna Hess ◽  
Alice Kuo ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Plasminogen Activator ◽  
Plasma Concentrations ◽  
Chain Molecule ◽  
Plasminogen Activation ◽  
Single Chain ◽  
Michaelis Constant ◽  
Complex Activity ◽  
Catalytic Constant ◽  
Insight Into

AbstractActivation of plasminogen by urokinase plasminogen activator (uPA) plays important roles in several physiologic and pathologic conditions. Cells secrete uPA as a single-chain molecule (scuPA). scuPA can be activated by proteolytic cleavage to a 2-chain enzyme (tcuPA). scuPA is also activated when it binds to its receptor (uPAR). The mechanism by which the enzymatic activity of the scuPA/suPAR complex is regulated is only partially understood. We now report that the plasminogen activator activity of the scuPA/suPAR complex is inhibited by Glu- and Lys-plasminogen, but not by mini-plasminogen. In contrast, neither Glunor Lys-plasminogen inhibits the activation of plasminogen by 2-chain uPA. Inhibition of scuPA/suPAR activity was evident at a Glu-plasminogen concentration of approximately 100 nM, and at physiologic plasma concentrations inhibition was nearly complete. A plasminogen fragment containing kringles 1-3 inhibited the enzymatic activity of scuPA/suPAR with an inhibition constant (Ki) equal to 1.9 μM, increased the Michaelis constant (Km) of scuPA/suPAR from 18 nM to 49 nM, and decreased the catalytic constant (Kcat) approximately 3-fold from 0.035 sec—1 to 0.011 sec—1. Inhibition of scuPA/suPAR by plasminogen was completely abolished in the presence of fibrin clots. These studies provide insight into the regulation of uPA-mediated plasminogen activation and identify a novel mechanism for its fibrin specificity.

Thermoelastic Properties of Rubberlike Networks and Their Thermodynamic and Molecular Interpretation

1973 ◽  
Vol 46 (3) ◽  
pp. 593-618 ◽  
Author(s):  
J. E. Mark
Keyword(s):  
Isomeric State ◽  
State Theory ◽  
Thermoelastic Properties ◽  
Chain Molecules ◽  
Rotational Isomeric State ◽  
Theoretical Investigations ◽  
Molecular Interpretation ◽  
Molecular Aspects ◽  
Insight Into ◽  
Conformational Energies

Abstract Thermoelastic measurements and their interpretation by means of rotational isomeric state theory provide a great deal of insight into both thermodynamic and molecular aspects of rubberlike elasticity. Furthermore, conformational energies obtained in part from thermoelastic studies can in turn be used in the interpretation and even prediction of a variety of configurationally dependent properties of chain molecules, as is shown in many of the theoretical investigations cited in Sections IV and VII of this review.

Inhibition in Purified Systems and in Human Plasma of Chimaeric Plasminogen Activators Consisting of the NH2-Terminal Region of Tissue-Type Plasminogen Activator and the COOH-Terminal Region of UrokinaseType Plasminogen Activator

1988 ◽  
Vol 60 (02) ◽  
pp. 247-250 ◽  
Author(s):  
H R Lijnen ◽  
L Nelles ◽  
B Van Hoef ◽  
F De Cock ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Rate Constants ◽  
Plasminogen Activators ◽  
Second Order ◽  
Tissue Type ◽  
Single Chain ◽  
Chain Molecules ◽  
Order Rate ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator

SummaryRecombinant chimaeric molecules between tissue-type plasminogen activator (t-PA) and single chain urokinase-type plasminogen activator (scu-PA) or two chain urokinase-type plasminogen activator (tcu-PA) have intact enzymatic properties of scu-PA or tcu-PA towards natural and synthetic substrates (Nelles et al., J Biol Chem 1987; 262: 10855-10862). In the present study, we have compared the reactivity with inhibitors of both the single chain and two chain variants of recombinant u-PA and two recombinant chimaeric molecules between t-PA and scu-PA (t-PA/u-PA-s: amino acids 1-263 of t-PA and 144-411 of u-PA; t-PA/u-PA-e: amino acids 1-274 of t-PA and 138-411 of u-PA). Incubation with human plasma in the absence of a fibrin clot for 3 h at 37° C at equipotent concentrations (50% clot lysis in 2 h), resulted in significant fibrinogen breakdown (to about 40% of the normal value) for all two chain molecules, but not for their single chain counterparts. Preincubation of the plasminogen activators with plasma for 3 h at 37° C, resulted in complete inhibition of the fibrinolytic potency of the two chain molecules but did not alter the potency of the single chain molecules. Inhibition of the two chain molecules occurred with a t½ of approximately 45 min. The two chain variants were inhibited by the synthetic urokinase inhibitor Glu-Gly-Arg-CH2CCl with apparent second-order rate constants of 8,000-10,000 M−1s−1, by purified α2-antiplasmin with second-order rate constants of about 300 M−1s−1, and by plasminogen activator inhibitor-1 (PAI-1) with second-order rate constants of approximately 2 × 107 M−1s−1.It is concluded that the reactivity of single chain and two chain forms of t-PA/u-PA chimaers with inhibitors is very similar to that of the single and two chain forms of intact u-PA.

Functional Characterization of a Variant Factor XII (F XII Locarno) in a Cross Reacting Material Positive F XII Deficient Plasma

1992 ◽  
Vol 67 (02) ◽  
pp. 219-225 ◽  
Author(s):  
Walter A Wuillemin ◽  
Miha Furlan ◽  
Hans Stricker ◽  
Bernhard Lämmle
Keyword(s):  
Dextran Sulfate ◽  
Functional Characterization ◽  
Healthy Woman ◽  
Chain Molecule ◽  
Plasma Kallikrein ◽  
Factor Xii ◽  
Single Chain ◽  
Sulfate Adsorption ◽  
Prolonged Incubation ◽  
Functional Studies

SummaryThe plasma of a healthy woman was found to contain half normal factor XII (FXII) antigen level (0.46 U/ml) without any FXII clotting activity (<0.01 U/ml). The variant FXII in this plasma, denoted as FXII Locarno, was partially characterized by immunological and functional studies on the proposita’s plasma. FXII Locarno is a single chain molecule with the same size (M r = 80 kDa) as normal FXII. Isoelectric focusing suggested an excess of negative charge in the variant FXII as compared to normal FXII. In contrast to FXII in normal plasma, FXII Locarno was not proteolytically cleaved upon prolonged incubation of proposita’s plasma with dextran sulfate. Adsorption to kaolin was similar for both, abnormal and normal FXII. Incubation of the proposita’s plasma with dextran sulfate and exogenous plasma kallikrein showed normal cleavage of FXII Locarno outside of the tentative disulfide loop Cys340-Cys467, but only partial cleavage within this disulfide loop. Furthermore, plasma kallikrein-cleaved abnormal FXII showed neither amidolytic activity nor proteolytic activity against factor XI and plasma prekallikrein.These results suggest a structural alteration of FXII Locarno, affecting the plasma kallikrein cleavage site Arg353-Val354 and thus formation of activated FXII (a-FXIIa).

scholarly journals Systemic Lupus Erythematosus before and after COVID-19 Lockdown: How the Perception of Disease Changes through the Lenses of Narrative Medicine

Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 726
Author(s):  
Fulvia Ceccarelli ◽  
Venusia Covelli ◽  
Giulio Olivieri ◽  
Francesco Natalucci ◽  
Fabrizio Conti
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Lupus Erythematosus ◽  
Narrative Medicine ◽  
Good Control ◽  
Final Analysis ◽  
Point Of View ◽  
Systemic Lupus ◽  
Before And After ◽  
Text Content ◽  
Insight Into

Background: The COVID-19 pandemic contributes to the burden of living with different diseases, including Systemic Lupus Erythematosus (SLE). We described, from a narrative point of view, the experiences and perspectives of Italian SLE adults during the COVID-19 emergency, by distinguishing the illness experience before and after the lockdown. Methods: Fifteen patients were invited to participate. Illness narratives were collected between 22 and 29 March 2020 using a written modality to capture patients’ perspectives before and after the COVID-19 lockdown. We performed a two-fold analysis of collected data by distinguishing three narrative types and a qualitative analysis of content to identify the relevant themes and sub-themes reported. Results: Eight narratives included in the final analysis (mean length 436.9 words) have been written by eight females (mean age 43.3 ± 9.9 years, mean disease duration 13.1 ± 7.4 years). Six patients provided a quest narrative, one a chaos and the remaining one a restitution narrative. By text content analysis, we identified specific themes, temporally distinct before and after the lockdown. Before COVID-19, all the patients referred to a good control of disease, however the unexpected arrival of the COVID-19 emergency broke a balance, and patients perceived the loss of health status control, with anxiety and stress. Conclusions: We provided unique insight into the experiences of people with SLE at the time of COVID-19, underlining the perspective of patients in relation to the pandemic.

scholarly journals A proteoglycan form of heparin and its degradation to single-chain molecules.

1978 ◽  
Vol 253 (19) ◽  
pp. 6687-6693 ◽  
Author(s):  
H.C. Robinson ◽  
A.A. Horner ◽  
M. Höök ◽  
S. Ogren ◽  
U. Lindahl
Keyword(s):  
Single Chain ◽  
Chain Molecules

scholarly journals Sex Work in Slovenia: Assessing the Needs of Sex Workers

2021 ◽  
pp. 136078042110184
Author(s):  
Leja Markelj ◽  
Alisa Selan ◽  
Tjaša Dolinar ◽  
Matej Sande
Keyword(s):  
Needs Assessment ◽  
Sex Work ◽  
Sex Workers ◽  
Point Of View ◽  
Social Distress ◽  
Legal Advice ◽  
The Law ◽  
Client Relations ◽  
Insight Into

The research comprehensively identifies the needs and problems of sex workers in Slovenia from the point of view of three groups of actors in a decriminalized setting. The objective of the rapid needs assessment was to identify the needs of sex workers as perceived by themselves. In order to gain a deeper insight into this topic, we analyzed the functioning of the organizations working with the population, and examined the perspective of the clients. The results of the study show that no aid programmes have been developed for sex workers, even though organizations from various fields often come in contact with this population. Sex workers express the need to be informed about various topics (health, the law, legal advice) and emphasize client relations as the primary issue. The findings indicate the need for the development of a specialized aid programmes to address the fields of advocacy, reducing social distress and providing psychosocial assistance.

scholarly journals Translational Fusion of Two β-Subunits of Human Chorionic Gonadotropin Results in Production of a Novel Antagonist of the Hormone

Endocrinology ◽  
2007 ◽  
Vol 148 (8) ◽  
pp. 3977-3986 ◽  
Author(s):  
Satarupa Roy ◽  
Sunita Setlur ◽  
Rupali A. Gadkari ◽  
H. N. Krishnamurthy ◽  
Rajan R. Dighe
Keyword(s):  
Chorionic Gonadotropin ◽  
Human Chorionic Gonadotropin ◽  
Expression System ◽  
Biologically Active ◽  
Chain Molecule ◽  
Dependent Manner ◽  
Β Subunit ◽  
Single Chain ◽  
Α Subunit ◽  
Lh Receptor

The strategy of translationally fusing the α- and β-subunits of human chorionic gonadotropin (hCG) into a single-chain molecule has been used to produce novel analogs of hCG. Previously we reported expression of a biologically active single-chain analog hCGαβ expressed using Pichia expression system. Using the same expression system, another analog, in which the α-subunit was replaced with the second β-subunit, was expressed (hCGββ) and purified. hCGββ could bind to LH receptor with an affinity three times lower than that of hCG but failed to elicit any response. However, it could inhibit response to the hormone in vitro in a dose-dependent manner. Furthermore, it inhibited response to hCG in vivo indicating the antagonistic nature of the analog. However, it was unable to inhibit human FSH binding or response to human FSH, indicating the specificity of the effect. Characterization of hCGαβ and hCGββ using immunological tools showed alterations in the conformation of some of the epitopes, whereas others were unaltered. Unlike hCG, hCGββ interacts with two LH receptor molecules. These studies demonstrate that the presence of the second β-subunit in the single-chain molecule generated a structure that can be recognized by the receptor. However, due to the absence of α-subunit, the molecule is unable to elicit response. The strategy of fusing two β-subunits of glycoprotein hormones can be used to produce antagonists of these hormones.

scholarly journals The wave pattern of a doublet in a stream

1928 ◽  
Vol 121 (788) ◽  
pp. 515-523 ◽  
Keyword(s):  
Surface Effect ◽  
Ideal Point ◽  
Finite Size ◽  
Wave Pattern ◽  
Wave Resistance ◽  
Point Of View ◽  
The Body ◽  
Surface Elevation ◽  
More Care ◽  
Forced Waves

The following paper is a study of the surface waves caused by a doublet in a uniform stream, and in particular the variation in the pattern with the velocity of the stream or the depth of the doublet. In most recent work on this subject attention has been directed more to the wave resistance, which can be evaluated with less difficulty than is involved in a detailed study of the waves; in fact, it would seem that it is not necessary for that purpose to know the surface elevation completely, but only certain significant terms at large distances from the disturbance. Recent experimental work has shown con­siderable agreement between theoretical expressions for wave resistance and results for ship models of simple form, and attempts have been made at a similar comparison for the surface elevation in the neighbourhood of the ship. In the latter respect it may be necessary to examine expressions for the surface elevation with more care, as they are not quite determinate; any suitable free disturbance may be superposed upon the forced waves. For instance, it is well known that in a frictionless liquid a possible solution is one which gives waves in advance as well as in the rear of the ship, and the practical solution is obtained by superposing free waves which annul those in advance, or by some equivalent artifice. This process is simple and definite for an ideal point disturbance, but for a body of finite size or a distributed disturbance the complete surface elevation in the neighbourhood of the body requires more careful specification as regards the local part due to each element. It had been intended to consider some expressions specially from this point of view, but as the matter stands at present it would entail a very great amount of numerical calculation, and the present paper is limited to a much simpler problem although also involving considerable computation. A horizontal doublet of given moment is at a depth f below the surface of a stream of velocity c ; the surface effect may be described as a local disturbance symmetrical fore and aft of the doublet together with waves to the rear. Two points are made in the following work.

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