Dose-response modeling
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Inhibition of acethylcholinesterase (AChE) as a key molecular event induced by organophosphate (OP) pesticides and nerve agents presents a human health concern. In efficacy testing of experimental oximes, potential antidotes in OP poisoning, reactivation of OP-inhibited AChE is used as specific endpoint. However, according to our best knowledge, so far oximes have not been quantitatively evaluated by comprehensive benchmark dose (BMD) approach, that would improve both identification and quantification of the effect and allow more rigorous comparison of efficacies. Thus, we have examined in vivo dose-response relationship for two promising experimental oximes, K203 and K027, concerning reactivation of erythrocyte AChE inhibited by dichlorvos (DDVP). Groups of Wistar rats were treated with six different doses of oximes (i.m) immediately after DDVP challenge (s.c) and AChE was measured 60 min later. Dose-response modeling was done by PROAST software 65.5 (RIVM, The Nederlands). BMD-covariate method resulted in four-parameter model from both exponential and Hill model families as the best estimate of relationship between AChE activity and oxime dose, with potency parameter being oxime-dependent. Oxime K027 was shown to be 1.929-fold more potent considering that 58% increase in AChE activity was achived with the dose BMD58-K027 = 52 μmol/kg in contrast to BMD58-K203 = 100 μmol/kg.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory metabolismus MeSH
- dichlorvos chemie farmakologie MeSH
- erytrocyty enzymologie MeSH
- krysa rodu rattus MeSH
- molekulární struktura MeSH
- oximy chemie farmakologie MeSH
- potkani Wistar MeSH
- pyridinové sloučeniny chemie farmakologie MeSH
- reaktivátory cholinesterasy farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
... DOSE-RESPONSE MODELLING: BASIC CONCEPTS 22 -- 4.1 Introduction 22 -- 4.2 What is dose? ... ... 23 -- 4.3 What is response? 24 -- 4.4 What is a model? 25 -- 4.5 What is dose-response modelling? ... ... 27 -- 4.6 Risk versus safety in dose-response modelling 31 -- 4.7 Summary 33 -- 5. ... ... 49 -- 6.2 Models and distributions 51 -- 6.2.1 Dose-response models 51 -- 6.2.1.1 Continuous dose-response ... ... models 51 -- 6.2.1.2 Quantal dose-response models 53 -- 6.2.1.3 Thresholds 53 -- 6.2.1.4 Severity (degree ...
Environmental health criteria, ISSN 0250-863X 239
xx, 137 s. : il., tab. ; 21 cm
A novel series of 7-methoxytacrine (7-MEOTA)-donepezil like compounds was synthesized and tested for their ability to inhibit electric eel acetylcholinesterase (EeAChE), human recombinant AChE (hAChE), equine serum butyrylcholinesterase (eqBChE) and human plasmatic BChE (hBChE). New hybrids consist of a 7-MEOTA unit, representing less toxic tacrine (THA) derivative, connected with analogues of N-benzylpiperazine moieties mimicking N-benzylpiperidine fragment from donepezil. 7-MEOTA-donepezil like compounds exerted mostly non-selective profile in inhibiting cholinesterases of different origin with IC50 ranging from micromolar to sub-micromolar concentration scale. Kinetic analysis confirmed mixed-type inhibition presuming that these inhibitors are capable to simultaneously bind peripheral anionic site (PAS) as well as catalytic anionic site (CAS) of AChE. Molecular modeling studies and QSAR studies were performed to rationalize studies from in vitro. Overall, 7-MEOTA-donepezil like derivatives can be considered as interesting candidates for Alzheimer's disease treatment.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- butyrylcholinesterasa krev metabolismus MeSH
- cholinesterasové inhibitory chemická syntéza chemie farmakologie MeSH
- Electrophorus MeSH
- indany chemie farmakologie MeSH
- koně MeSH
- kvantitativní vztahy mezi strukturou a aktivitou * MeSH
- lidé MeSH
- molekulární modely MeSH
- molekulární struktura MeSH
- piperidiny chemie farmakologie MeSH
- rekombinantní proteiny metabolismus MeSH
- takrin analogy a deriváty chemie farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- absorpce MeSH
- amoxicilin MeSH
- biologické modely MeSH
- lidé MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
Living organisms interact with various chemical compounds via receptors, which is described by the receptor theory. The affinity of the biologically active compounds toward receptors and their ability to trigger a biological or toxic signal vary substantially. In this work, we describe a new insight into understanding of the mode of action of receptor partial agonists and the receptor theory using a Full Logistic Model (FLM) of mixture toxicology. We describe the hypothesis that the effect of a partial agonist can be mathematically described via separation of agonistic and antagonistic behavior of the partial agonist where the antagonistic effect is described as an action of the compound producing zero effect. In this way, a competitive antagonist can be considered as an agonist with zero effect. This idea is also placed into a context with classical concepts, e.g., Gaddum's equation. Using the assumption that competitive antagonists are agonists with no effect, equations describing the microscopic and macroscopic equilibrium constants have been derived. Accordingly, we show that the constants could be calculated from the measured partial agonistic dose-response curve. As a consequence, we provide a simple mathematical tool for comparison of dose-response curves of drugs according to their affinities and efficacies.
From four molecules, inspired by the structural features of fascaplysin, with an interesting potential to inhibit cyclin-dependent kinases (CDKs), we designed a new series of tri-heterocyclic derivatives based on 1H-pyrrolo[2,3-b]pyridine (7-azaindole) and triazole heterocycles. Using a Huisgen type [3 + 2] cycloaddition as the convergent key step, 24 derivatives were synthesized and their biological activities were evaluated. Comparative molecular field analysis (CoMFA), based on three-dimensional quantitative structure-activity relationship (3D-QSAR) studies, was conducted on a series of 30 compounds from the literature with high to low known inhibitory activity towards CDK2/cyclin E and was validated by a test set of 5 compounds giving satisfactory predictive r(2) value of 0.92. Remarkably, it also gave a good prediction of pIC50 for our tri-heterocyclic series which reinforce the validation of this model for the pIC50 prediction of external set compounds. The most promising compound, 43, showed a micro-molar range inhibitory activity against CDK2/cyclin E and also an antiproliferative and proapoptotic activity against a panel of cancer cell lines.
- MeSH
- cyklin E antagonisté a inhibitory metabolismus MeSH
- cyklin-dependentní kinasa 2 antagonisté a inhibitory metabolismus MeSH
- heterocyklické sloučeniny chemická syntéza chemie farmakologie MeSH
- indoly chemická syntéza chemie farmakologie MeSH
- inhibitory enzymů chemická syntéza chemie farmakologie MeSH
- kvantitativní vztahy mezi strukturou a aktivitou MeSH
- lidé MeSH
- molekulární modely * MeSH
- molekulární struktura MeSH
- nádorové buněčné linie MeSH
- proliferace buněk účinky léků MeSH
- protinádorové látky chemická syntéza chemie farmakologie MeSH
- screeningové testy protinádorových léčiv MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
7-methoxytacrine-4-pyridinealdoxime (7-MEOTA-4-PA, named hybrid 5C) is a compound formerly synthesized and evaluated in vitro, together with 4-pyridine aldoxime (4-PA) and commercial reactivators of acetylcholinesterase (AChE). This compound was designed with the purpose of being a prophylactic reactivator, capable of interacting with different subdomains of the active site of AChE. To investigate these interactions, theoretical results from docking were first compared with experimental data of hybrid 5C, 4-PA, and two commercial oximes, on the reactivation of human AChE (HssAChE) inhibited by VX. Then, further docking studies, molecular dynamics simulations, and molecular mechanics Poisson-Boltzmann surface area calculations, were carried out to investigate reactivation performances, considering the near attack conformation (NAC) approach, prior to the nucleophilic substitution mechanism. Our results helped to elucidate the interactions of such molecules with the different subdomains of the active site of HssAChE. Additionally, NAC poses of each oxime were suggested for further theoretical studies on the reactivation reaction.
- MeSH
- acetylcholinesterasa metabolismus MeSH
- cholinesterasové inhibitory chemická syntéza chemie farmakologie MeSH
- lidé MeSH
- molekulární modely MeSH
- molekulární struktura MeSH
- obidoxim chlorid chemie farmakologie MeSH
- organothiofosforové sloučeniny chemie farmakologie MeSH
- oximy chemie farmakologie MeSH
- pralidoximové sloučeniny chemie farmakologie MeSH
- pyridiny chemie farmakologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Receptor ligands in mixtures may produce effects that are greater than the effect predicted from their individual dose-response curves. The historical basis for predicting the mixture effect is based on Loewe's concept and its mathematical formulation. This concept considers compounds with constant relative potencies (parallel dose-response curves) and leads to linear additive isoboles. These lines serve as references for distinguishing additive from nonadditive interactions according to the positions of the experimental data on or outside of the lines. In this paper, we applied a highly relevant two-state model for a description of the receptor-ligand interaction in the construction of the isobologram. In our model we consider partial agonists that have dose-response curve slopes differing from one. With this theoretical basis, we demonstrated that a combination of compounds with different efficacies leads to curved isoboles. This model should overwrite Tallarida's flawed assumption about isobolographic analysis of partial agonists and enhance our understanding of how the partial agonists contribute to the overall mixture effect.
