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High-throughput polymerase chain reaction chemiluminescent enzyme immunoassay for typing and quantifying human papillomavirus DNAs.

A miniaturized polymerase chain reaction (PCR) chemiluminescent enzyme immunoassay (CLEIA) based on a 384-well microtiter plate for detection and typing of oncogenic high- and low-risk human papillomavirus (HPV) in genital lesions is described. The assay relies on PCR consensus amplification, hybridization of the digoxigenin-labeled product by means of type-specific biotin-labeled oligoprobes immobilized on the streptavidin-coated wells of a 384-well microtiter plate, and quantification by means of a horseradish peroxidase-labeled antidigoxigenin antibody and chemiluminescence detection. The method provides semiquantitative information on the viral load, with a limit of detection of 10-50 DNA copies for HPV 6, 11, 16, 18, 31, 33, 35, 39, 45, 51, 52, 53, 54, 58, and 59 and high reproducibility (intraassay CV 7.5%, interassay CV 9.5%). Results obtained on 60 clinical samples were concordant with those obtained with a conventional PCR-enzyme-linked immunosorbent assay colorimetric assay. The 384 PCR-CLEIA method, which is amenable to automation, represents a fast and high-throughput method for detecting and typing HPV DNAs in screening programs and evaluating the viral load.

Calibration↗

A high-throughput screen for single gene activities: isolation of apoptosis inducers.

We describe a novel genetic screen that is performed by transfecting every individual clone of an expression library into a separate population of cells in a high-throughput mode. The screen allows one to achieve a hitherto unattained sensitivity in expression cloning which was exploited in a first read-out to clone apoptosis-inducing genes. This led to the isolation of several genes whose proteins induce distinct phenotypes of apoptosis in 293T cells. One of the isolated genes is the tumor suppressor cytochrome b(L) (cybL), a component of the respiratory chain complex II, that diminishes the activity of this complex for apoptosis induction. This gene is more efficient and specific for causing cell death than a drug with the same activity. These results suggest further applications, both of the isolated genes and the screen.

Animals↗

Gene expression systems in the development of high-throughput screens.

Recent advances in the development of combinatorial automated chemical synthesis, robotic sample handling, and data collection and analysis have significantly increased the number of compounds available for screening against potential therapeutic targets. The implementation of highly sensitive in vitro biochemical and cell-based high-throughput screening assays is essential to facilitate the rapid identification of selective and potent lead molecules from compound libraries. The ability to easily produce functional proteins in sufficient quantities for in vitro biochemical assays and to devise useful cell-based systems is dependent on the successful application of a variety of gene expression systems.

Animals↗

A pilot study of high-throughput, sequence-based mutational profiling of primary human acute myeloid leukemia cell genomes.

In this pilot study, we used primary human acute myeloid leukemia (AML) cell genomes as templates for exonic PCR amplification, followed by high-throughput resequencing, analyzing approximately 7 million base pairs of DNA from 140 AML samples and 48 controls. We identified six previously described, and seven previously undescribed sequence changes that may be relevant for AML pathogenesis. Because the sequencing templates were generated from primary AML cells, the technique favors the detection of mutations from the most dominant clones within the tumor cell mixture. This strategy represents a viable approach for the detection of potentially relevant, nonrandom mutations in primary human cancer cell genomes.

Case-Control Studies↗

Phage display of functional human TNF-alpha converting enzyme catalytic domain: a rapid method for the production of stabilized proteolytic proteins for assay development and high-throughput screening.

The catalytic domain of human tumor necrosis factor-alpha (TNF-alpha) converting enzyme (TACE) was expressed in a phage display system to determine whether stable and active enzyme could be made for high-throughput screening (HTS). This would address many issues around screening of proteases in this class. The phage-displayed TACE catalytic domain (PDT) properly cleaved the fusion protein of glutathione S-transferase (GST)-pro-TNF-alpha to generate the mature TNF-alpha in vitro. To determine the utility of the PDT in HTS, the authors further demonstrated that PDT was able to generate a strong reproducible fluorescence signal by cleaving a fluorogenic TNF-alpha-specific peptide in vitro. More important, the catalytic activity of the PDT was inhibited by a broad-spectrum matrix metalloprotease (MMP) inhibitor but not by an MMP-I specific inhibitor, illustrating the potential utility of PDT for HTS. The PDT was also compared with baculovirus-expressed TACE (BET) in these assays to establish the relative efficacy of PDT. Both PDT and BET showed a similar specific cleavage profile against the defined substrates. Activity of the BET, however, was stable at 4 degrees C for less than 24 h. In contrast, the PDT exhibited remarkable stability, losing very little activity even after 2 years at 4 degrees C. On the basis of these results, the authors concluded that the phage display system might be a useful tool for expressing proteins that have stability issues related to auto-proteolytic activity. Furthermore, the ease and low cost of large-scale production of phage should make it suitable for assay development and HTS.

ADAM Proteins↗

High throughput screening in agrochemical research.

The demand for new herbicides, insecticides and fungicides led to a steady increase in the number of compounds being tested to find novel market products. To keep pace with the rising workload, high throughput screening (HTS) technologies have been introduced. In agrochemical research miniaturised in vivo tests on whole real target organisms are now possible and are an integral part of the screening cascade. A complementary target based in vitro HTS has also been established in agrochemical research. Target based HTS allows a directed approach towards untouched market shares by novel modes of action. Selection of the best suited targets is the most crucial issue in this approach. Genomic methods thereby deliver many essential genes as candidate targets. Consideration of further criteria such as druggability notably narrows down the number of promising targets. Though target to hit to lead progression still is as in pharmaceutical research a complex and therefore risky process, the implementation of novel bioscience technologies has entailed the transition to an integrated innovative agrochemical research perspective.

Agrochemicals↗

[High-throughput screening assay for groups of effective components extracted from Xiaoxuming Recipe].

OBJECTIVE: To present a new approach for the research of effective components extracted from compounds of traditional Chinese medicine and their action mechanisms by high-throughput screening assay. METHODS: We observed the anti-oxidation activities of 240 sequential components (L1-L120 and A1-A120) extracted from Xiaoxuming Recipe, the effects of these components on SH-SY5Y cells with H(2)O(2)-induced and L-glutamic acid-induced damages and the levels of resting calcium ion in neurocytes of rats. RESULTS: Some components (L1-L40, A100-A120) extracted from Xiaoxuming Recipe had the corresponding effects listed above. The combination of these components was regarded as the groups of effective components of Xiaoxuming Recipe in treating sequelae resulting from brain ischemia. CONCLUSION: Xiaoxuming Recipe has protective effect on brain-ischemia-induced damages through the actions of multiple components with multiple targets.

Animals↗

High-throughput screening using genome-wide siRNA libraries.

Small-interfering RNA (siRNA) technology is a new approach for blocking the production of a protein by specific degradation of the messenger RNA that encodes the protein. The high potency of siRNA and the relative ease of application have led to broad implementation of the method in many aspects of the life science research. The combination of the developments in its application and in siRNA libraries to cover whole genomes has further enabled genome-wide high-throughput functional screening.

Combinatorial Chemistry Techniques↗

High throughput analysis of differential gene expression.

Elucidation of the changes in gene expression associated with biological processes is a central problem in biology. Advances in molecular and computational biology have led to the development of powerful, high-throughput methods for the analysis of differential gene expression. These tools have opened up new opportunities in disciplines ranging from cell and developmental biology to drug development and pharmacogenomics. In this review, the attributes of five commonly used differential gene expression methods are discussed: expressed sequence tag (EST) sequencing, cDNA microarray hybridization, subtractive cloning, differential display, and serial analysis of gene expression (SAGE). The application of EST sequencing and microarray hybridization is illustrated by the discovery of novel genes associated with osteoblast differentiation. The application of subtractive cloning is presented as a tool to identify genes regulated in vivo by the transcription factor pax-6. These and other examples illustrate the power of genomics for discovering novel genes that are important in biology and which also represent new targets for drug development. The central theme of the review is that each of the approaches to identifying differentially expressed genes is useful, and that the experimental context and subsequent evaluation of differentially expressed genes are the critical features that determine success.

Animals↗

High-throughput determination of free D-aspartic acid in mammals by enzyme immunoassay using specific monoclonal antibody.

A method for rapid determination of free D-aspartic acid (D-Asp) in mammals has been established using a highly specific mouse monoclonal antibody against D-Asp for the first time. An anti-D-Asp monoclonal antibody was obtained by the immunization of bovine-serum-albumin-conjugated D-Asp to BALB/c mice. The obtained antibody has a high specificity toward D-Asp but shows a slight cross-reactivity to all other D- and L- amino acids including L-Asp. The calibration range of the competitive enzyme linked immunosorbent assay (ELISA) is 0.016-16 micromol/mL D-Asp in rat serum samples. The precisions of this method were evaluated by inter-plate and intraplate assays, and the relative standard deviation values were 4.8% and 4.5%, respectively. The values of D-Asp determined by the present ELISA have a good correlation to those determined by high-performance liquid chromatography with the correlation coefficient of 0.963. Using this ELISA, the time course of D-Asp in the rat serum after intravenous administration was successfully demonstrated. The present method provides a simple and high-throughput determination of D-Asp in mammals, and is a useful tool for clarifying the physiological roles and diagnostic values of this D-amino acid.

Amino Acid Sequence↗

Increasing specificity in high-throughput yeast two-hybrid experiments.

Since its inception, the yeast two-hybrid (Y2H) system has proven to be an efficient system to identify novel protein-protein interactions. However, Y2H screens are sometimes criticized for generating high rates of false-positives. Minimizing false-positive interactions is especially important in proteome wide high-throughput (HT) Y2H. Here, we summarize various approaches that reduce false-positives in HT-Y2H projects. We evaluated the potential of examining putative positives after removing the prey encoding plasmid by negative selection. We found that this method reliably identifies false-positives caused by spontaneous conversion of baits into auto-activators and provides significant time-savings in HT screens. In addition, we present a method to eliminate an important source of false-positives: contaminating prey plasmids. Y2H interactors can be wrongly identified due to the presence of two or more different plasmids in the cells of a single yeast colony. Of these independent plasmids, only one encodes a genuine interactor. Contaminating plasmids are eliminated by extended culture of yeast cells under positive selection for the interaction, allowing the identification of the true interaction partner.

Animals↗

High-throughput protein crystallography and drug discovery.

Single crystal X-ray diffraction is the technique of choice for studying the interactions of small organic molecules with proteins by determining their three-dimensional structures; however the requirement for highly purified protein and lack of process automation have traditionally limited its use in this field. Despite these shortcomings, the use of crystal structures of therapeutically relevant drug targets in pharmaceutical research has increased significantly over the last decade. The application of structure-based drug design has resulted in several marketed drugs and is now an established discipline in most pharmaceutical companies. Furthermore, the recently published full genome sequences of Homo sapiens and a number of micro-organisms have provided a plethora of new potential drug targets that could be utilised in structure-based drug design programs. In order to take maximum advantage of this explosion of information, techniques have been developed to automate and speed up the various procedures required to obtain protein crystals of suitable quality, to collect and process the raw X-ray diffraction data into usable structural information, and to use three-dimensional protein structure as a basis for drug discovery and lead optimisation. This tutorial review covers the various technologies involved in the process pipeline for high-throughput protein crystallography as it is currently being applied to drug discovery. It is aimed at synthetic and computational chemists, as well as structural biologists, in both academia and industry, who are interested in structure-based drug design.

Crystallography, X-Ray↗

High-throughput assays using a luciferase-expressing replicon, virus-like particles, and full-length virus for West Nile virus drug discovery.

Many flaviviruses cause significant human disease worldwide. The development of flavivirus chemotherapy requires reliable high-throughput screening (HTS) assays. Although genetic systems have been developed for many flaviviruses, their usage in antiviral HTS assays has not been well explored. Here we compare three cell-based HTS assays for West Nile virus (WNV) drug discovery: (i) an assay that uses a cell line harboring a persistently replicating subgenomic replicon (containing a deletion of viral structural genes), (ii) an assay that uses packaged virus-like particles containing replicon RNA, and (iii) an assay that uses a full-length reporting virus. A Renilla luciferase gene was engineered into the replicon or into the full-length viral genome to monitor viral replication. Potential inhibitors could be identified through suppression of luciferase signals upon compound incubation. The antiviral assays were optimized in a 96-well format, validated with known WNV inhibitors, and proved useful in identifying a new inhibitor(s) through HTS of a compound library. In addition, because each assay encompasses multiple but discrete steps of the viral life cycle, the three systems could potentially be used to discriminate the mode of action of any inhibitor among viral entry (detected by assays ii and iii but not by assay i), replication (including viral translation and RNA synthesis; detected by assays i to iii), and virion assembly (detected by assay iii but not by assays i and ii). The approaches described in this study should be applicable to the development of cell-based assays for other flaviviruses.

Antiviral Agents↗

Ultra-high-throughput microarray generation and liquid dispensing using multiple disposable piezoelectric ejectors.

The authors have constructed an array of 12 piezoelectric ejectors for printing biological materials. A single-ejector footprint is 8 mm in diameter, standing 4 mm high with 2 reservoirs totaling 76 micro L. These ejectors have been tested by dispensing various fluids in several environmental conditions. Reliable drop ejection can be expected in both humidity-controlled and ambient environments over extended periods of time and in hot and cold room temperatures. In a prototype system, 12 ejectors are arranged in a rack, together with an X - Y stage, to allow printing any pattern desired. Printed arrays of features are created with a biological solution containing bovine serum albumin conjugated oligonucleotides, dye, and salty buffer. This ejector system is designed for the ultra-high-throughput generation of arrays on a variety of surfaces. These single or racked ejectors could be used as long-term storage vessels for materials such as small molecules, nucleic acids, proteins, or cell libraries, which would allow for efficient preprogrammed selection of individual clones and greatly reduce the chance of cross-contamination and loss due to transfer. A new generation of design ideas includes plastic injection molded ejectors that are inexpensive and disposable and handheld personal pipettes for liquid transfer in the nanoliter regime.

Cell Line↗

Using extended-connectivity fingerprints with Laplacian-modified Bayesian analysis in high-throughput screening follow-up.

This article describes the use of a combination of extended-connectivity fingerprints (ECFPs) and Laplacian-modified Bayesian analysis in a study of the inhibition of Escherichia coli dihydrofolate reductase. The McMaster High-Throughput Screening Lab at McMaster University proposed a competition to predict the hits in a separate test set of 50,000 compounds. Although the problem seemed best approached with 3D methods, the authors show that 2D methods offer surprisingly competitive results with a low computational cost.

Algorithms↗

Aptamers as reagents for high-throughput screening.

The identification of new drug candidates from chemical libraries is a major component of discovery research in many pharmaceutical companies. Given the large size of many conventional and combinatorial libraries and the rapid increase in the number of possible therapeutic targets, the speed with which efficient high-throughput screening (HTS) assays can be developed can be a rate-limiting step in the discovery process. We show here that aptamers, nucleic acids that bind other molecules with high affinity, can be used as versatile reagents in competition binding HTS assays to identify and optimize small-molecule ligands to protein targets. To illustrate this application, we have used labeled aptamers to platelet-derived growth factor B-chain and wheat germ agglutinin to screen two sets of potential small-molecule ligands. In both cases, binding affinities of all ligands tested (small molecules and aptamers) were strongly correlated with their inhibitory potencies in functional assays. The major advantages of using aptamers in HTS assays are speed of aptamer identification, high affinity of aptamers for protein targets, relatively large aptamer-protein interaction surfaces, and compatibility with various labeling/detection strategies. Aptamers may be particularly useful in HTS assays with protein targets that have no known binding partners such as orphan receptors. Since aptamers that bind to proteins are often specific and potent antagonists of protein function, the use of aptamers for target validation can be coupled with their subsequent use in HTS.

Animals↗

High throughput sequencing and comparative genomics of foot-and-mouth disease virus.

Despite a basic understanding of many aspects of FMD biology, much information regarding FMDV virulence, host range, and virus transmission remains poorly understood. Here we present how the use of high throughput sequencing for complete genome sequences of foot-and mouth disease virus (FMDV) led to a series of new insights into viral genome sequence conservation and variability, genetic diversity in nature and phylogenetic classification of isolates, including the first complete sequences of the South African Territories type 1 and 3 (SAT1 and SAT3) genomes. Comparative genomic analysis of full-length sequences of FMDV isolates did allow: (i) the identification of highly conserved regulatory or coding regions which are critical for aspects of virus biology as well as novel viral genomic motifs with likely biological relevance; (ii) characterization of the first complete sequences of the SAT1 and SAT3 genomes; (iii) identification of a novel SAT virus lineage genetically distinct from other SAT and Euro-Asiatic lineages; (iv) precise identification of strains circulating around the world for epidemiological and forensic attribution; (v) assessment of mutation and recombination processes as mechanisms equally involved in evolution; (vi) mutation rates, tolerance and constraints of genes and proteins during evolution of FMD viruses during in vivo replication and (vi) support for the hypothesis of a new evolutionary model.

Animals↗

An efficient strategy for high-throughput expression screening of recombinant integral membrane proteins.

The recombinant expression of integral membrane proteins is considered a major challenge, and together with the crystallization step, the major hurdle toward routine structure determination of membrane proteins. Basic methodologies for high-throughput (HTP) expression optimization of soluble proteins have recently emerged, providing statistically significant success rates for producing such proteins. Experimental procedures for handling integral membrane proteins are generally more challenging, and there have been no previous comprehensive reports of HTP technology for membrane protein production. Here, we present a generic and integrated parallel HTP strategy for cloning and expression screening of membrane proteins in their detergent solubilized form. Based on this strategy, we provide overall success rates for membrane protein production in Escherichia coli, as well as initial benchmarking statistics of parameters such as expression vectors, strains, and solubilizing detergents. The technologies were applied to 49 E. coli integral membrane proteins with human homologs and revealed that 71% of these proteins could be produced at sufficient levels to allow milligram amounts of protein to be relatively easily purified, which is a significantly higher success rate than anticipated. We attribute the high success rate to the quality and robustness of the methodology used, and to introducing multiple parameters such as different vectors, strains, and detergents. The presented strategy demonstrates the usefulness of HTP technologies for membrane protein production, and the feasibility of large-scale programs for elucidation of structure and function of bacterial integral membrane proteins.

Chromatography, Gel↗