Browsing by Author "Aptula, A. O."

Showing items 1-12 of 12

Aptula, A.O.; Jeliazkova, N.G.; Schultz, T.W.; Cronin, M.T.D. The Better Predictive Model: High q2 for the Training Set or Low Root Mean Square Error of Prediction for the Test Set?. QSAR Comb. Sci. 2005, 24, 3, 385–396.

Published: Villu Ruusmann (2012-05-23)

Abstract: The process of validation of computational models (e.g., QSARs) may become the most important step in their development. Different requirements for the reliability and predictability of QSAR models have been described in the literature. Despite these formal recommendations there are few practical rules as to when to cease adding variables to a QSAR (i.e., what ...

Dataset
Aptula, A.O.; Netzeva, T.I.; Valkova, I.V.; Cronin, M.T.D.; Schultz, T.W.; Kühne, R.; Schüürmann, G. Multivariate Discrimination between Modes of Toxic Action of Phenols. Quant. Struct.-Act. Relat. 2002, 21, 1, 12–22.

Published: Villu Ruusmann (2012-05-23)

Abstract: A set of 221 phenols, for which toxicity data to the ciliate Tetrahymena pyriformis were available, was subjected to stepwise linear discriminant analysis (LDA) in order to classify their toxic mechanisms of action. The compounds were a priori grouped into the following four mechanisms according to structural rules: polar narcotics, weak acid respiratory ...

Dataset
Aptula, A.O.; Roberts, D.W.; Cronin, M.T.D.; Schultz, T.W. Chemistry-Toxicity Relationships for the Effects of Di- and Trihydroxybenzenes to Tetrahymena pyriformis. Chem. Res. Toxicol. 2005, 18, 5, 844–854.

Published: Villu Ruusmann (2012-05-23)

Abstract: This paper presents a mechanistic analysis of aquatic toxicity data, quantified as pIGC(50) assessed in the 40 h Tetrahymena pyriformis population growth impairment assay, for 40 polyhydroxybenzene derivatives. The toxicity trends of these phenolic compounds have been shown to be consistent with mechanistic organic chemistry principles. Thus, it is shown that ...

Regression
Cronin, M.T.D.; Aptula, A.O.; Duffy, J.C.; Netzeva, T.I.; Rowe, P.H.; Valkova, I.V.; Schultz, T.W. Comparative assessment of methods to develop QSARs for the prediction of the toxicity of phenols to Tetrahymena pyriformis. Chemosphere 2002, 49, 10, 1201–1221.

Published: Villu Ruusmann (2012-05-23)

Abstract: Quantitative structure-activity relationships (QSARs) for the toxicity of 200 phenols to the ciliated protozoan Tetrahymena pyriformis, and the validation of the QSARs using a test set of a further 50 compounds, are reported. The phenols are structurally heterogeneous and represent a variety of mechanisms of toxic action including polar narcosis, weak acid ...

Regression
Netzeva, T.I.; Aptula, A.O.; Chaudary, S.H.; Duffy, J.C.; Schultz, T.W.; Schüürmann, G.; Cronin, M.T.D. Structure-Activity Relationships for the Toxicity of Substituted Poly-hydroxylated Benzenes to Tetrahymena pyriformis: Influence of Free Radical Formation. QSAR Comb. Sci. 2003, 22, 6, 575–582.

Published: Villu Ruusmann (2012-05-23)

Abstract: The aim of this study was to develop quantitative structure-activity relationships for the toxicity to Tetrahymena pyriformis of 30 substituted poly-hydroxylated benzenes. Physico-chemical descriptors for the expression of free radical formation, associated with the OH moiety on the aromatic ring, were calculated. These included one-electron equilibrium constants ...

Regression
Netzeva, T.I.; Schultz, T.W.; Aptula, A.O.; Cronin, M.T.D. Partial Least Squares Modelling of the Acute Toxicity of Aliphatic Compounds to Tetrahymena pyriformis. SAR QSAR Environ. Res. 2003, 14, 4, 265–283.

Published: Villu Ruusmann (2012-05-23)

Abstract: The aim of this study was to evaluate a multivariate statistical model, utilising Partial Least Squares (PLS) analysis, for the prediction of the acute toxicity of aliphatic chemicals to the ciliate Tetrahymena pyriformis. A model was developed that was capable of making a prediction regardless the mechanism of toxic action. The toxicity of 476 compounds, ...

Dataset
Roberts, D. W.; Aptula, A. O.; Patlewicz, G. Mechanistic Applicability Domains for Non-Animal Based Prediction of Toxicological Endpoints. QSAR Analysis of the Schiff Base Applicability Domain for Skin Sensitization. Chem. Res. Toxicol. 2006, 19, 9, 1228–1233.

Published: Iiris Kahn (2014-11-10)

Abstract: Several recent (1999 onward) publications on skin sensitization to aldehydes and ketones, which can sensitize by covalent binding to skin protein via Schiff base formation, present QSARs based on the Taft sigma* parameter to model reactivity and log P to model hydrophobicity. Here, all of the data are reanalyzed together in a stepwise self-consistent way using ...

HumanHealth Regression QMRF
Roberts, D.W.; Schultz, T.W.; Wolf, E.M.; Aptula, A.O. Experimental Reactivity Parameters for Toxicity Modeling: Application to the Acute Aquatic Toxicity of SN2 Electrophiles to Tetrahymena pyriformis. Chem. Res. Toxicol. 2010, 23, 1, 228–234.

Published: Villu Ruusmann (2012-05-23)

Abstract: A diverse set of 60 haloaliphatic compounds were evaluated for reactivity with cysteine thiol groups in the previously described RC(50) assay using glutathione (GSH) as a model nucleophile. Reactivity was quantified by the RC(50) value, the concentration of test compound that produced 50% reaction of the GSH thiol groups in 120 min. Under standard conditions, ...

Dataset
Schultz, T.W.; Cronin, M.T.D.; Netzeva, T.I.; Aptula, A.O. Structure-Toxicity Relationships for Aliphatic Chemicals Evaluated with Tetrahymena pyriformis. Chem. Res. Toxicol. 2002, 15, 12, 1602–1609.

Published: Villu Ruusmann (2012-05-23)

Abstract: Quantitative structure-activity relationships were developed for the toxicity data of 500 aliphatic chemicals tested in the two-day Tetrahymena pyriformis population growth impairment assay. These chemicals represented a number of structural classes spanning a variety of mechanisms of toxic action including narcoses and electrophilic mechanisms. A series of ...

Regression
Schultz, T.W.; Ralston, K.E.; Roberts, D.W.; Veith, G.D.; Aptula, A.O. Structure-activity relationships for abiotic thiol reactivity and aquatic toxicity of halo-substituted carbonyl compounds. SAR QSAR Environ. Res. 2007, 18, 1-2, 21–29.

Published: Villu Ruusmann (2012-05-23)

Abstract: Using abiotic thiol reactivity (EC50) and Tetrahymena pyriformis toxicity (IGC50) data for a group of halo-substituted ketones, esters and amides (i.e. SN2 electrophiles) and related compounds a series of structure-activity relationships are illustrated. Only the alpha-halo-carbonyl-containing compounds are observed to be thiol reactive with the order I > Br ...

Dataset
Schultz, T.W.; Sparfkin, C.L.; Aptula, A.O. Reactivity-based toxicity modelling of five-membered heterocyclic compounds: Application to Tetrahymena pyriformis. SAR QSAR Environ. Res. 2010, 7, 8, 681–691.

Published: Villu Ruusmann (2012-05-23)

Abstract: A diverse set of 57 heterocyclic organic chemicals, consisting of a five-membered unsaturated ring of four carbon atoms and one oxygen (furans), or sulfur (thiophenes), or nitrogen (pyrroles) were evaluated for reactivity with thiol and acute aquatic toxicity assays using glutathione (GSH) as a model nucleophile and the ciliate Tetrahymena pyriformis, respectively. ...

Regression
Schüürmann, G.; Aptula, A.O.; Kühne, R.; Ebert, R.U. Stepwise Discrimination between Four Modes of Toxic Action of Phenols in the Tetrahymena pyriformis Assay. Chem. Res. Toxicol. 2003, 16, 8, 974–987.

Published: Villu Ruusmann (2012-05-23)

Abstract: For a set of 220 phenols with literature data on their toxicity and associated mode of action (MOA) toward the ciliate Tetrahymena pyriformis, a stepwise classification scheme was developed that allows the identification of four MOAs from molecular hydrophobicity and AM1-based quantum chemical descriptors, employing linear discriminant analysis or binary ...

Regression

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