Biomedical subjects

D Yourtee

Publications and source records attributed to D Yourtee.

4 recordsLinked to original sources

PubMed2001

Quantum mechanical quantitative structure activity relationships to avoid mutagenicity in dental monomers.

The objective of this study was to identify through quantum mechanical quantitative structure activity relationships (Q-QSARs) chemical structures in dental monomers that influence their mutagenicity. AMPAC, a semiempirical computer program that provides quantum mechanical information for chemical structures, was applied to three series of reference chemicals: a set of methacrylates, a set of aromatic and a set of aliphatic epoxy compounds. QSAR models were developed using this chemical information together with mutagenicity data (Salmonella TA 100, Ames Test). CODESSA, a QSAR program that calculates quantum chemical descriptors from information generated by AMPAC and statistically matches these descriptors with observed biological properties was used. QSARs were developed which had r2 values exceeding 0.90 for each study series. These QSARs were used to accurately predict the mutagenicity of BISGMA. a monomer commonly used in dentistry, and two epoxy monomers with developing use in dentistry, GY-281 and UVR-6105. The Q-QSAR quantum mechanical descriptors correctly predicted the level of mutagenicity for all three compounds. The descriptors in the correlation equation pointed to components of structure that may contribute to mutagenesis. The QSARs also provided 'dose windows' for testing mutagenicity, circumventing the need for extensive dose exploration in the laboratory. The Q-QSAR method promises an approach for biomaterials scientists to predict and avoid mutagenicity from the chemicals used in new biomaterial designs.

Dental Enamel↗

PubMed2000

Stereolithographic models of biopolymers.

Stereolithography (STL) has been used to make plastic models of the solvent accessible surfaces of biopolymers. Models have been made of proteins and proteins bound to DNA and RNA. The STL process uses a laser to photopolymerize a liquid resin. Using the ACES (accurate, clear, epoxy, solid) building technique, parts are made with minimum postcure shrinkage. Protein Data Bank files are converted to STL files that represent the surface topology of the biopolymer as a series of triangles and an index that describes their orientation. The models are useful in teaching biomolecular structure and the principle of docking. They are especially useful to the visually impaired.

Acetylcholinesterase↗

PubMed1993

Ion chromatography on a new moderate capacity anion exchange column.

The mechanisms of retention of anions on a new solvent-compatible, moderate capacity (170 microequivalent per column) anion-exchange column are described. Retention based on anion exchange is shown using both sodium hydroxide and 4-cyanophenolate eluants. Plots of the log k' vs. log C, (where k' is the capacity factor and C is the eluant concentration) are shown to be linear with slopes approximating the charge of the eluant as predicted by the standard anion-exchange equation. Sodium hydroxide is shown to be a relatively weak eluant, capable of separating monovalent anions that are difficult to separate on other columns. Sodium 4-cyanophenolate is shown to be a strong eluant, capable of eluting polyvalent anions. The retention of nonionic alkylphenones is also described. In plots of log k' vs. percentage acetonitrile in the eluant, these compounds were found not to follow the solvophobic mechanism typical of reverse-phase HPLC columns. Results are compared with other anion exchange columns. Applications include the determination of lysophosphatidyl inositol in brain microsomes and methacrylic acid in esterase-treated samples.

Animals↗

PubMed1988

Ion chromatographic determination of sugar phosphates in physiological samples.

Ion chromatography is shown to be capable of simultaneous determination of biologically important anions. Application of this technique is illustrated for the separation and quantification of the major anions present in rat brain and liver tissues. Sugar phosphates and carboxylic acids are separated on high-performance anion-exchange columns and are detected using chemically suppressed conductivity. Detection limits range from 20 to 100 pmol for the anions tested, including inositol phosphates, lactate, pyruvate, glucuronic acid-1-phosphate, fructose-6-phosphate and glucose-6-phosphate. The coefficient of variation for the determination of most anions was in the range 5-10%. Many of these anions are either difficult to separate with other methods, or require expensive radiochemical techniques for detection. This method should be applicable to other biological studies, from the flow of carbons in photosynthesis to the study of synaptic transmission.

Animals↗