scholarly journals Contribution of the intra- and intermolecular routes in autocatalytic zymogen activation: application to pepsinogen activation.

2006 ◽  
Vol 53 (2) ◽  
pp. 407-420 ◽  
Author(s):  
Ramón Varón ◽  
Matilde E Fuentes ◽  
Manuela García-Moreno ◽  
Francisco Garcìa-Sevilla ◽  
Enrique Arias ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Rate Constants ◽  
Time Course ◽  
Initial Conditions ◽  
Reaction Scheme ◽  
Complete Analysis ◽  
Zymogen Activation ◽  
Relative Contribution ◽  
Starting Point ◽  
Definition Of

Taking as the starting point a recently suggested reaction scheme for zymogen activation involving intra- and intermolecular routes and the enzyme-zymogen complex, we carry out a complete analysis of the relative contribution of both routes in the process. This analysis suggests the definition of new dimensionless parameters allowing the elaboration, from the values of the rate constants and initial conditions, of the time course of the contribution of the two routes. The procedure mentioned above related to a concrete reaction scheme is extrapolated to any other model of autocatalytic zymogen activation involving intra- and intermolecular routes. Finally, we discuss the contribution of both of the activating routes in pepsinogen activation into pepsin using the values of the kinetic parameters given in the literature.

scholarly journals Music Against the Challenges of Digital Society

2021 ◽  
pp. 810-821
Author(s):  
Boris V. Markov ◽  
Dmitriy A. Yarochkin
Keyword(s):  
Modern Society ◽  
Theoretical Explanation ◽  
Complete Analysis ◽  
Starting Point ◽  
Definition Of ◽  
Political Technology ◽  
The Relationship ◽  
Networked Society ◽  
Anthropology Of Music

The aim of the article is to separate the concepts of musicology, music anthropology, music, and instrumentalism. This very division and reflection of the interrelations of concepts provide a starting point for a detailed study of the problems of musical instrumentalism. The article is methodological in nature. It contains a number of important settings that are necessary for the anthropological analysis of music. The Central theoretical explanation of the article is the separation of musical anthropology and the anthropology of music. For this purpose, a number of tasks, namely, the definition of the theoretical fields of musical anthropology and the anthropology of music, and the disclosure of the role of music in traditional and modern society are proposed. The concept of musical action is introduced. Solving these problems allows to give a more complete analysis of the relationship between a person and music. It is this problem that becomes the main problem in the music media mainstream, where popular music is used as a way of producing moods and experiences. Music becomes a particularly valuable commodity in a networked society, which is made not so much for the purpose of incorporating into the values of high culture but to control the behavior of people in the music market. In addition to commercialization, music is becoming an effective political technology that provides consensus among voters. In this regard, there is a cultural problem, how high art in general and music, in particular, can preserve its traditional purpose – to promote humanization

ON STABILITY OF COMMENSURATE FRACTIONAL ORDER SYSTEMS

2012 ◽  
Vol 22 (04) ◽  
pp. 1250084 ◽  
Author(s):  
JOCELYN SABATIER ◽  
CHRISTOPHE FARGES
Keyword(s):  
Fractional Order ◽  
Original Work ◽  
Closed Loop ◽  
Initial Conditions ◽  
Stability Theorem ◽  
Fractional Order Systems ◽  
Fractional Differentiation ◽  
Starting Point ◽  
Definition Of

This paper proposes a new proof of the Matignon's stability theorem. This theorem is the starting point of numerous results in the field of fractional order systems. However, in the original work, its proof is limited to a fractional order ν such that 0 < ν < 1. Moreover, it relies on Caputo's definition for fractional differentiation and the study of system trajectories for non-null initial conditions which is now questionable in regard of recent works. The new proof proposed here is based on a closed loop realization and the application of the Nyquist theorem. It does not rely on a peculiar definition of fractional differentiation and is valid for orders ν such that 1 < ν < 2.

Effect of Calcium ion on the interaction between Thrombin and Heparin. Thermal Denaturation

1977 ◽  
Vol 38 (03) ◽  
pp. 0677-0684 ◽  
Author(s):  
Raymund Machovich ◽  
Péter Arányi
Keyword(s):  
Calcium Ions ◽  
Rate Constants ◽  
Thermal Denaturation ◽  
Time Course ◽  
Complex Analysis ◽  
Heat Inactivation ◽  
Second Phase ◽  
Denaturation Kinetics ◽  
Enzyme Protection ◽  
Enzyme Denaturation

SummaryHeat inactivation of thrombin at 54° C followed first order kinetics with a rate constant of 1.0 min−1 approximately. Addition of heparin resulted in protection against thermal denaturation and, at the same time, rendered denaturation kinetics more complex. Analysis of the biphasic curve of heat inactivation in the presence of heparin revealed that the rate constants of the second phase changed systematically with heparin concentrations. Namely, at 4.5 × 10−6M, 9 × 10−6M, 1.8 × 10−5M and 3.6 × 10−5M heparin concentrations, the rate constants were 0.27 min−1, 0.17 min−1, 0.11 min−1 and 0.06 min−1, respectively.Sulfate as well as phosphate ions displayed also enzyme protection against heat inactivation, however, the same effect was obtained already at a heparin concentration, lower by three orders of magnitude.The kinetics of enzyme denaturation was not affected by calcium ions, whereas in the presence of heparin the inactivation rate of thrombin changed, i. e. calcium ions abolished the biphasic character of time course of thermal denaturation.Thus, the data suggest that calcium ions contribute to the effect of heparin on thrombin.

Holism, Chinese Medicine and Systems Ideologies: Rewriting the Past to Imagine the Future

2018 ◽  
Author(s):  
Volker Scheid
Keyword(s):  
Eighteenth Century ◽  
Chinese Medicine ◽  
Medical Humanities ◽  
Science And Technology Studies ◽  
Human Beings ◽  
The Past ◽  
Starting Point ◽  
The Us ◽  
Shared Objective ◽  
Definition Of

This chapter explores the articulations that have emerged over the last half century between various types of holism, Chinese medicine and systems biology. Given the discipline’s historical attachments to a definition of ‘medicine’ that rather narrowly refers to biomedicine as developed in Europe and the US from the eighteenth century onwards, the medical humanities are not the most obvious starting point for such an inquiry. At the same time, they do offer one advantage over neighbouring disciplines like medical history, anthropology or science and technology studies for someone like myself, a clinician as well as a historian and anthropologist: their strong commitment to the objective of facilitating better medical practice. This promise furthermore links to the wider project of critique, which, in Max Horkheimer’s definition of the term, aims at change and emancipation in order ‘to liberate human beings from the circumstances that enslave them’. If we take the critical medical humanities as explicitly affirming this shared objective and responsibility, extending the discipline’s traditional gaze is not a burden but becomes, in fact, an obligation.

Dosimetry and optimization in digital radiography based on the contrast-detail resolution

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
Wilson Otto Gomes Batista ◽  
Alexandre Gomes De Carvalho
Keyword(s):  
Image Quality ◽  
Inverse Image ◽  
Point Of View ◽  
Complete Analysis ◽  
Portable Devices ◽  
Evaluation Tool ◽  
Air Kerma ◽  
Direct Radiography ◽  
Definition Of ◽  
Entrance Surface Air Kerma

Contrast-detail (C-D) curves are useful in evaluating the radiographic image quality in a global way. The objective of the present study was to obtain the C-D curves and the inverse image quality figure. Both of these parameters were used as an evaluation tool for abdominal and chest imaging protocols. The C-D curves were obtained with the phantom CDRAD 2.0 in computerized radiography and the direct radiography systems (including portable devices). The protocols were 90 and 102 kV in the range of 2 to 20 mAs for the chest and 80 kV in the range of 10 to 80 mAs for the abdomen. The incident air kerma values were evaluated with a solid state sensor. The analysis of these C-D curves help to identify which technique would allow a lower value of the entrance surface air kerma, Ke, while maintaining the image quality from the point of view of C-D detectability. The results showed that the inverse image quality figure, IQFinv, varied little throughout the range of mAs, while the value of Ke varied linearly directly with the mAs values. Also, the complete analysis of the curves indicated that there was an increase in the definition of the details with increasing mAs. It can be concluded that, in the transition phase for the use of the new receptors, it is necessary to evaluate and adjust the practised protocols to ensure, at a minimum, the same levels of the image quality, taking into account the aspects of the radiation protection of the patient.

Oxidation scheme of symmetrically disulphonated naphthidines with cerium(IV) sulphate

1981 ◽  
Vol 46 (3) ◽  
pp. 561-572 ◽  
Author(s):  
Karel Komers
Keyword(s):  
Sulphuric Acid ◽  
Rate Constants ◽  
Oxidation Product ◽  
Side Reaction ◽  
Reaction Scheme ◽  
Second Order ◽  
Intermediate Products ◽  
Stable Intermediate ◽  
Starting Compound ◽  
Oxidation Agent

The author derived theoretical dependences of preasymptotic slopes of the currentless E-t curves (potential of an indicator redox electrode against time) on the number of equivalents, n, of added oxidation agent, assuming a reaction scheme of two consecutive concurrent second-order reactions involving the formation of intermediate products ( a side reaction of the starting compound with the final oxidation product leading to an adduct, which undergoes consecutive bimolecular oxidations leading again to the final product). The dependences enable to determine the type of the relatively stable intermediate products and the ratios of the rate constants. The theory was applied to the oxidation of four symmetrically disulphonated naphthidines with cerium(IV) sulphate in aqueous sulphuric acid and the results were substantiated spectrophotometrically

scholarly journals Conceptual and Practical Issues in the Pharmacological Treatment of Brain Injury

1993 ◽  
Vol 4 (3) ◽  
pp. 227-237 ◽  
Author(s):  
Donald G. Stein ◽  
Marylou M. Glasier ◽  
Stuart W. Hoffman
Keyword(s):  
Central Nervous System ◽  
Brain Injury ◽  
Time Course ◽  
Chemical Activity ◽  
Behavioral Testing ◽  
Naturally Occurring ◽  
New Information ◽  
Definition Of ◽  
Injury And Repair ◽  
The Brain

It is only within the last ten years that research on treatment for central nervous system (CNS) recovery after injury has become more focused on the complexities involved in promoting recovery from brain injury when the CNS is viewed as an integrated and dynamic system. There have been major advances in research in recovery over the last decade, including new information on the mechanics and genetics of metabolism and chemical activity, the definition of excitotoxic effects and the discovery that the brain itself secretes complex proteins, peptides and hormones which are capable of directly stimulating the repair of damaged neurons or blocking some of the degenerative processes caused by the injury cascade. Many of these agents, plus other nontoxic naturally occurring substances, are being tested as treatment for brain injury. Further work is needed to determine appropriate combinations of treatments and optimum times of administration with respect to the time course of the CNS disorder. In order to understand the mechanisms that mediate traumatic brain injury and repair, there must be a merging of findings from neurochemical studies with data from intensive behavioral testing.

Chemilumineszenz der SO2-Oxidation / Chemiluminescence of SO2-Oxidation

1978 ◽  
Vol 33 (3) ◽  
pp. 293-299 ◽  
Author(s):  
Joachim Stauff ◽  
Wolfgang Jaeschke
Keyword(s):  
Aqueous Solutions ◽  
Spectral Region ◽  
Time Course ◽  
Light Emission ◽  
Analog Computer ◽  
Reaction Scheme ◽  
So2 Oxidation ◽  
Recombination Product ◽  
Electronically Excited ◽  
Ph Range

Abstract The reactions of diluted aqueous solutions of SO2 resp. HSO3-ions with MnO4-or Ce4+ ions in the pH range 1-4 produce chemiluminescence in the spectral region of 450-600 nm. Measurements of the time course of the light emission and their simulation on an analog computer led to a reaction scheme in which a recombination product of primarily formed HSO3 radicals -of a lifetime of about 1 second -appears as precursor of electronically excited SO2 molecules. The participation of singlet oxygen can be excluded because at least the reaction with Ce4+ ions proceeds also in the absence of oxygen.

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