Biomedical subjects

L H Hall

Publications and source records attributed to L H Hall.

40 records · Page 3Linked to original sources

PubMedDate not supplied

E-state modeling of corticosteroids binding affinity validation of model for small data set.

Data for 31 steroids binding to the corticosteroid binding globulin (CBG) were modeled using E-state molecular structure descriptors and a kappa shape index. Both E-state and hydrogen E-state descriptors appear in the model in atom-level and atom-type descriptors. A four-variable model is obtained that is statistically satisfactory: r (2) = 0.81, s = 0.51; r (2)(press) = 0.72; s(press) = 0.62. Structure interpretation is given for each variable in the model. A leave-group-out (LGO) approach to model-validation is presented in which each observation is removed from the data set three times in random groups of 20% of the whole data set. The average of the resulting predicted values constitutes consensus predictions for these data for which r (2)(LOO) = 0.70. These collective results support the claim that the E-state model may be useful for prediction of pK binding values for new compounds.

Adrenal Cortex Hormones↗

PubMedDate not supplied

Modeling antileukemic activity of carboquinones with electrotopological state and chi indices.

The antileukemic activity (medium effective dose, MED) of a set of 37 carboquinones was modeled using a combination of the electrotopological state (E-state) and molecular connectivity indices with multiple linear regression. A four-variable model gave good statistics: r2 = 0.90, s = 0.21. Using the leave-one-out method, the cross-validation statistics indicate a model useful for prediction: r2press = 0.85, spress = 0.26. The same variables were used to model the optimum effective dose (OD): r2 = 0.88, s = 0.19. The cross-validation statistics indicate a model useful for prediction: r2press = 0.83, spress = 0.23. The descriptor variables are interpreted in terms of the molecular structure.

Animals↗

PubMedDate not supplied

QSAR modeling based on structure-information for properties of interest in human health.

The development of QSAR models based on topological structure description is presented for problems in human health. These models are based on the structure-information approach to quantitative biological modeling and prediction, in contrast to the mechanism-based approach. The structure-information approach is outlined, starting with basic structure information developed from the chemical graph (connection table). Information explicit in the connection table (element identity and skeletal connections) leads to significant (implicit) structure information that is useful for establishing sound models of a wide range of properties of interest in drug design. Valence state definition leads to relationships for valence state electronegativity and atom/group molar volume. Based on these important aspects of molecules, together with skeletal branching patterns, both the electrotopological state (E-state) and molecular connectivity (chi indices) structure descriptors are developed and described. A summary of four QSAR models indicates the wide range of applicability of these structure descriptors and the predictive quality of QSAR models based on them: aqueous solubility (5535 chemically diverse compounds, 938 in external validation), percent oral absorption (%OA, 417 therapeutic drugs, 195 drugs in external validation testing), AMES mutagenicity (2963 compounds including 290 therapeutic drugs, 400 in external validation), fish toxicity (92 substituted phenols, anilines and substituted aromatics). These models are established independent of explicit three-dimensional (3-D) structure information and are directly interpretable in terms of the implicit structure information useful to the drug design process.

Animals↗

PubMedDate not supplied

Class 5 composite resin restorations: margin configurations and the distance from the CEJ.

An in vitro study of 60 teeth examined the cervical microleakage of class 5 composite resin restorations in regard to preparation design and location from the cementoenamel junction (CEJ). Four groups of 15 teeth each were prepared for a class 5 composite resin restoration with the cervical margins finished as follows: a butt joint margin placed less than 1 mm from the CEJ, a beveled margin placed less than 1 mm from the CEJ, a butt joint placed greater than 1.5 mm from the CEJ, and a beveled margin placed greater than 1.5 mm from the CEJ. The teeth were acid etched, treated with an enamel bonding agent, and restored with a microfilled composite resin, and then sectioned for further analysis. The sectioned specimens were evaluated for cervical microleakage by Ca45 autoradiography. The butt joint margins placed less than 1 mm from the CEJ had significantly more microleakage than the other groups, indicating that all enamel margins of a class 5 composite resin restoration should be beveled to decrease microleakage regardless of their location relative to the cementoenamel junction.

Composite Resins↗