The design, fabrication, and operation of a radial capillary array electrophoresis microplate and scanner for high-throughput DNA analysis is presented. The microplate consists of a central common anode reservoir coupled to 96 separate microfabricated separation channels connected to sample injectors on the perimeter of the 10-cm-diameter wafer. Detection is accomplished by a laser-excited rotary confocal scanner with four color detection channels. Loading of 96 samples in parallel is achieved using a pressurized capillary array system. High-quality separations of 96 pBR322 restriction digest samples are achieved in < 120 s with the microplate system. The practical utility and multicolor detection capability is demonstrated by analyzing 96 methylenetetrahydrofolate reductase (MTHFR) alleles in parallel using a noncovalent 2-color staining method. This work establishes the feasibility of performing high-throughput genotyping separations with capillary array electrophoresis microplates.

Protein disulfide isomerase (PDI) plays a key role in protein folding by catalyzing rearrangements of disulfide bonds in substrate proteins following their synthesis in eukaryotic cells. Besides its major role in the processing and maturation of secretory proteins in the endoplasmic reticulum, this enzyme and its homologs have been implicated in multiple important cellular processes; however, they have not served as targets for the development of therapeutic agents. The authors developed a high-throughput screening assay for PDI and its homologous enzymes in 384-well microplates. The method is based on the enzyme-catalyzed reduction of insulin in the presence of dithiothreitol and measures the aggregation of reduced insulin chains at 650 nm. This kinetic assay was converted to an end-point assay by using hydrogen peroxide as a stop reagent. The feasibility of this high-throughput assay for screening chemical libraries was demonstrated in a pilot screen. The authors show that this homogenous turbidometric assay is robust and cost-effective and can be applied to identify PDI inhibitors from chemical libraries, opening this class of enzymes for therapeutic exploration.

Spectroscopic effects of spin-orbit coupling of excited-state potential surfaces are calculated by using the numerical integration of the time-dependent Schrodinger equation and the time-dependent theory of electronic spectroscopy. Intensity borrowing by a spin-forbidden transition from a nearby spin-allowed transition is calculated in terms of amplitude transfer of the wave packet between states. The main emphasis of the calculations is to analyze the vibronic structure in emission and absorption spectra arising from coupled surfaces. The coupling causes dramatic changes in both the relative intensities of the vibronic bands and the spacings between members of a progression. These changes are quantitatively calculated, and the theory is applied to the spectra of transition-metal complexes. The intensity and spacing between vibronic peaks in the absorption spectrum of K2Ni02 are calculated and analyzed. A striking example of relative intensities in vibronic peaks induced by spin-orbit coupling is found in the emission spectra of d2 and d3 metal ions in octahedral environments where the lowest energy spin-forbidden transitions arise from a change in the spin state with no change in the orbital component. Short progressions in totally symmetric modes are frequently observed even though no changes in the orbital populations, bond properties, or force constants are expected. The vibronic structure in spectra of Ti2+, V3+, Cr3+, and Mn4+ ions in octahedral halide lattices is analyzed.

Pure gold films are deposited on germanium, silicon, silicon dioxide, and quartz by photolyzing (CH3)zAu-(hexafluoroacetylacetonate) in the gas phase. Shiny gold films are deposited at low incident fluences (<5 mJ/cm2), whereas higher fluences yield dull brown deposits. The effects of the fluence and the repetition rate of the pulsed laser on the morphology of the deposited film are studied by using SEM. The film quality is analyzed by using XPS and Auger spectroscopic methods. No detectable carbon is found in either the gold or brown films, indicating that both are pure gold with different surface morphologies. Luminescence in the gas phase is observed under the conditions used for the photodeposition. The emission spectrum, containing two bands having well-resolved vibronic fine structure, originates from dimeric gold, Au2. The spectroscopic identification of ligand-free gold indicates that there is a gas-phase photochemical component in the deposition process. Deposition mechanisms, including both a surface component and a gas-phase component, are discussed.

Solubility and permeability are intimately linked in drug absorption processes. They have, however, been traditionally assayed separately. To support this linkage, a combined solubility/permeability assay was developed for determining absorption properties of chemical entities. First, solubility is determined at 4 pH values by comparing the concentration of a saturated compound solution to its dilute, known concentration. The filtered, saturated solution from the solubility assay is then used as input material for the membrane permeability determination. The permeability assay is a parallel artificial membrane technique whereby a membrane is created on a solid support parallel artificial membrane permeation assay (PAMPA). The 2 artificial membranes presented here model the gastrointestinal tract and the blood-brain barrier (BBB). Data are presented for control compounds, which are well documented in the literature and exemplify a range of solubility and membrane permeability. The advantages of the combination method are 1) reduction of sample usage and preparation time, 2) elimination of interference from compound precipitation in membrane permeability determination, 3) maximization of input concentration to permeability assay for improved reproducibility, and 4) optimization of sample tracking by streamlining data entry and calculations. BBB permeability ranking of compounds correlates well with literature CNS activity. Key words: PAMPA, ADME-Tox, blood-brain-barrier, high throughput W ITH AN EVER INCREASING PRESSURE to push compounds through the drug discovery pipeline, there is a steady demand for reliable, high-throughput assay technologies in bottleneck areas. One bottleneck area that has received significant attention lately is ADME-Tox (Absorption, Distribution, Metabolism, Excretion, and Toxicology). The pressure is then compounded by the fact that 40% of late-stage failures are associated with poor pharmacokinetic properties, 1 such as low oral absorption. In the present article, we focus on the 2 major factors of absorption: solubility and membrane permeability.2-6 The focus of this report is to develop a high-throughput process that will integrate both solubility and permeability assays to increase throughput and decrease cost.Several different techniques are available for determining aqueous solubility.7-12 After reviewing the available technologies for solubility testing, the direct ultraviolet (UV) method 13 was chosen based on its adaptability into a high-throughput format, low cost, and reliability. One potential problem for the direct UV method is compounds with weak UV absorption; however, these compounds are in the minority. If required, other detection methods such as high-performance liquid chromatography or liquid chromatography/mass spectrometry can be implemented. The direct UV method requires a small amount (~0.25 mg) of compound and can be conducted over a wide range of pH values in the presence of many different excipients including DMSO. Importantly, the resulting filtrate from this t...