Assessing the (a)symmetry of concentration-effect curves

Giraldo, Jesús; Vivas, Nuria M.; Vila, Elisabet; Badı́a, Albert

doi:10.1016/s0163-7258(02)00223-1

Cited by 126 publications

(110 citation statements)

References 42 publications

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“…which is adopted here as a low-dimensional fitting model, often termed a concentration-effect curve in pharmacological applications [26]. Here t is the time with the gelation half…”

Section: Resultsmentioning

confidence: 99%

Universal aspects of hydrogel gelation kinetics, percolation and viscoelasticity from PA-hydrogel rheology

Adibnia

Hill

2016

Journal of Rheology

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Polyacrylamide (PA) hydrogels have been studied extensively, but fundamental aspects of their gelation kinetics, percolation dynamics, and viscoelasticity are still not well understood. This paper focuses on the rheology of PA hydrogels having unusually low monomer concentrations. These furnish loss tangents that span four orders of magnitude when varying the crosslinker concentration [...] Close correspondence of the exponents with those of Adam et al. for the radical copolymerization of a di↵erent material supports the long-standing hypothesis that dynamics at the gel point are universal for a prescribed gelation mechanism

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“…which is adopted here as a low-dimensional fitting model, often termed a concentration-effect curve in pharmacological applications [26]. Here t is the time with the gelation half…”

Section: Resultsmentioning

confidence: 99%

Universal aspects of hydrogel gelation kinetics, percolation and viscoelasticity from PA-hydrogel rheology

Adibnia

Hill

2016

Journal of Rheology

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“…Quantitative curve shape analysis is necessary for accurate comparisons between concentration-signal curves. The following pharmacologic descriptors can be used for the shape analysis of f(x) curves, where f stands for the signal and x ϭ log[A], being [A] ligand concentration (Giraldo et al, 2002;Giraldo, 2003): 3. The location of the curve or midpoint (x 50 ): x for f ϭ Left ϩ 1/2 (Right Ϫ Left).…”

Section: Methodsmentioning

confidence: 99%

Modeling the Binding and Function of Metabotropic Glutamate Receptors

Rovira¹,

Roche²,

Serra³

et al. 2008

J Pharmacol Exp Ther

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706 -713, 2004). The former study allowed us to explain the mechanistic features associated with VFT recognition by agonists and antagonists integrating a negative allosteric interaction for agonist binding. The second study helped us to quantitatively describe the functional dynamics of transduction of the VFT occupation into functional response, confirming a putative positive cooperativity at the level of receptor coupling efficacy. This model will help both to better understand the functioning of these receptors and to characterize the mechanism of action of various types of allosteric modulators. Moreover, this model may be of general utility for oligomeric systems in which the ligand binding and effector domains correspond to distinct structural domains.The two main neurotransmitters, glutamate and GABA, activate not only ionotropic receptors but also G-proteincoupled receptors (GPCRs), called the metabotropic glutamate (mGlu) and GABA B receptors, respectively. These receptors belong to the class C of the large GPCR family (Pin et al., 2003) and play essential roles in the central nervous system by regulating fast excitatory and inhibitory transmission. As such, these receptors are the subject of intense research for the development of new drugs targeting the central nervous system.In addition to their sequence divergence with the other GPCRs, mGlu and GABA B receptors have peculiar structural characteristics. These receptors form constitutive dimers that are stabilized by a disulfide bridge in the case of mGlu receptors. Moreover, each protomer of a mGlu dimer is composed of three main structural domains: an extracellular Venus flytrap (VFT) domain where agonists bind, a transmembrane heptahelical domain (HD) responsible for G-protein activation, and a cysteine-rich domain (CRD) that interconnects the VFT and the HD both structurally and functionally (Rondard et al., 2006). These structural features make these receptors complex proteins and raise several issues regarding how agonist binding in the VFT leads to G-protein activation by the HD.Important information on the functioning of these proteins has been obtained from mutagenesis and structural studies

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“…E parameter allows the Hill model to reproduce the asymmetry in the observed data (Gottschalk and Dunn 2005;Giraldo et al 2002). Figure 3a (pCO 2 = 30 %, calcite fraction \150 lm) provides an interesting comparison of the models as this system shows significant asymmetry in the observed sorption curve.…”

Section: The Hill Equation As a Mechanistic Modelmentioning

confidence: 98%

Kinetic model selection and the Hill model in geochemistry

Turner

Henley

Sleap

et al. 2014

Int. J. Environ. Sci. Technol.

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This study introduces the Hill model for modelling sorption kinetics and illustrates its efficacy using formal model selection procedures. Although the coefficient of determination (R 2 ) value can be used to ensure goodness-of-fit of a particular model to a set of data, a measure that incorporates the number of model parameters, such as the Bayesian information criterion, law of iterated logarithm criterion, Akaike information criterion, and the extra sum-of-squares F-test is necessary to undertake reliable model selection. This study undertook a formal model selection procedure based on these criteria, in combination with the coefficient of determination, for a range of candidate kinetics sorption models [the pseudo-second order (PSO), the intra-particle diffusion (IPD), Power, Elovich, and the four and five parameter Hill models]. It was found that the model order that statistically best described the data was Hill 5 [ Hill 4 [ pseudo-second order [ Elovich [ Power [ IPD as given by the evidence ratios, information criterion weights and Bayes factors. The extra sum-of-squares F-test, only applicable to nested models, confirms the best fit order as Hill 5 [ Hill 4 [ PSO models. Two new parameters (T and k Hill ) have also been defined that give the Hill models a mechanistic meaning directly comparable to the well-defined parameters of the pseudo-second-order model, namely, the pseudo-secondorder rate constant k pso and the instantaneous sorption coefficient h pso . In the field of geochemistry the use of the four and five parameter Hill models for describing sorption kinetics has been overlooked with many studies favouring the PSO model. It is strongly recommended that the Hill model be considered more widely as a general predictive tool in geochemistry.

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Assessing the (a)symmetry of concentration-effect curves

Cited by 126 publications

References 42 publications

Universal aspects of hydrogel gelation kinetics, percolation and viscoelasticity from PA-hydrogel rheology

Universal aspects of hydrogel gelation kinetics, percolation and viscoelasticity from PA-hydrogel rheology

Modeling the Binding and Function of Metabotropic Glutamate Receptors

Kinetic model selection and the Hill model in geochemistry

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