ABSTRACT: The Microbial Detection Array Combined with Random Phi29-Amplification used as a Diagnostic Tool for Unbiased Virus Detection in Clinical Samples
Project description:A common technique used for sensitive and specific diagnostic virus detection in clinical samples is PCR. However, an unbiased diagnostic microarray containing probes for all human pathogens could replace hundreds of individual PCR-reactions and remove the need for a clear clinical hypothesis regarding a suspected pathogen. We have established such a diagnostic platform for unbiased random amplification and subsequent microarray identification of viral pathogens in clinical samples. We show that Phi29 polymerase-amplification of a diverse set of clinical samples generates enough viral material for successful identification by the Microbial Detection Array developed at the Lawrence Livermore National Laboratory, California, USA, demonstrating the potential of the microarray technique for broad-spectrum pathogen detection. We conclude that this method detects both DNA and RNA virus, present in the same sample, as well as differentiates between different virus subtypes. We propose this assay for unbiased diagnostic analysis of all viruses in clinical samples.
Project description:A common technique used for sensitive and specific diagnostic virus detection in clinical samples is PCR. However, an unbiased diagnostic microarray containing probes for all human pathogens could replace hundreds of individual PCR-reactions and remove the need for a clear clinical hypothesis regarding a suspected pathogen. We have established such a diagnostic platform for unbiased random amplification and subsequent microarray identification of viral pathogens in clinical samples. We show that Phi29 polymerase-amplification of a diverse set of clinical samples generates enough viral material for successful identification by the Microbial Detection Array developed at the Lawrence Livermore National Laboratory, California, USA, demonstrating the potential of the microarray technique for broad-spectrum pathogen detection. We conclude that this method detects both DNA and RNA virus, present in the same sample, as well as differentiates between different virus subtypes. We propose this assay for unbiased diagnostic analysis of all viruses in clinical samples. 19 clinical samples were analyzed for presence of virus using the MDA microarray. One of the samples is a negative control (water). One HCV-positive serum sample is included twice (HCV+1 and HCV+2).
Project description:In this study, we extend array CGH technology by making the accurate detection of segmental aneusomies possible from a single lymphoblast and fibroblast following Phi29 DNA polymerase amplification Keywords: array CGH, aCGH
Project description:In this study, we extend array CGH technology by making the accurate detection of chromosomal imbalances possible from a single fibroblast and blastomere following Phi29 DNA polymerase amplification. Keywords: CGH
Project description:This SuperSeries is composed of the following subset Series: GSE4078: Phi29-based amplification of fresh-frozen and FFPE tumor DNA GSE4079: Genome-Wide Gene Dosage Representation in Phi29-Amplified DNA Abstract: Sufficient quantity of genomic DNA can be a bottleneck in genome-wide analysis of clinical tissue samples. DNA polymerase Phi29 can be used for the random-primed amplification of whole genomes, although the amplification may introduce bias in gene dosage. We have performed a detailed investigation of this technique in archival fresh-frozen and formalin-fixed/paraffin-embedded tumor DNA by using cDNA microarray-based comparative genomic hybridization. Phi29 amplified DNA from matched pairs of fresh-frozen and formalin-fixed/paraffin-embedded tumor samples with similar efficiency. The distortion in gene dosage representation in the amplified DNA was nonrandom and reproducibly involved distinct genomic loci. Regional amplification efficiency was significantly linked to regional GC content of the template genome. The biased gene representation in amplified tumor DNA could be effectively normalized by using amplified reference DNA. Our data suggest that genome-wide gene dosage alterations in clinical tumor samples can be reliably assessed from a few hundred tumor cells. Therefore, this amplification method should lend itself to high-throughput genetic analyses of limited sources of tumor, such as fine-needle biopsies, laser-microdissected tissue, and small paraffin-embedded specimens. Refer to individual Series
Project description:Abstract: Sufficient quantity of genomic DNA can be a bottleneck in genome-wide analysis of clinical tissue samples. DNA polymerase Phi29 can be used for the random-primed amplification of whole genomes, although the amplification may introduce bias in gene dosage. We have performed a detailed investigation of this technique in archival fresh-frozen and formalin-fixed/paraffin-embedded tumor DNA by using cDNA microarray-based comparative genomic hybridization. Phi29 amplified DNA from matched pairs of fresh-frozen and formalin-fixed/paraffin-embedded tumor samples with similar efficiency. The distortion in gene dosage representation in the amplified DNA was nonrandom and reproducibly involved distinct genomic loci. Regional amplification efficiency was significantly linked to regional GC content of the template genome. The biased gene representation in amplified tumor DNA could be effectively normalized by using amplified reference DNA. Our data suggest that genome-wide gene dosage alterations in clinical tumor samples can be reliably assessed from a few hundred tumor cells. Therefore, this amplification method should lend itself to high-throughput genetic analyses of limited sources of tumor, such as fine-needle biopsies, laser-microdissected tissue, and small paraffin-embedded specimens. This SuperSeries is composed of the SubSeries listed below.
Project description:In this study, we extend array CGH technology by making the accurate detection of chromosomal imbalances possible from a single fibroblast and blastomere following Phi29 DNA polymerase amplification. Firstly, array CGH experiments were performed on four different fibroblast cell lines, derived from patients affected by, respectively, trisomy 13, 18, 21, and monosomy X. For each cell line, three single cells were amplified. Following DNA amplification, all cells showed the expected DNA yields (n=12; 1.87 µg plus:minus 0.39). Sex-mismatch array CGH experiments were conducted on amplified DNA samples obtained from each cell. Sex chromosome ploidy levels, as well as all expected autosomal abnormalities were clearly identified. Secondly, we applied single-cell aneuploidy screening for the detection of chromosomal imbalances in preimplantation embryos. DNA from blastomeres from three 7-8 cell-stage embryos was amplified by ï¦29 DNA polymerase. Following DNA amplification, all cells yielded the expected amount of DNA (n=16; 2.45 µg plus:minus 0.41). Chromosomal aneuploidies were accurately detected using a simple and rapid array CGH protocol.
Project description:The Microbial Detection Array for Detection of Emerging Viruses in Clinical Samples - A Useful Panmicrobial Diagnostic Tool--Array Version 2f
Project description:Changes in alternative splicing are associated with several pathological conditions, including cancer. Microarrays strategies, which allow for the characterization of thousands of alternative splice forms in a single test, can be applied to identify differential alternative splicing events. In this study, a novel splice array platform was developed, including the design of a high-density oligonucleotide array, a labeling procedure, and an algorithm to identify splice events. The array consists of exon probes and thermodynamically balanced junction probes. Suboptimal probes are tagged and considered in the final analysis. An unbiased labeling protocol was developed using random primers. The algorithm used to distinguish changes in expression from changes in splicing was calibrated using internal non-spliced control sequences. The performance of this splice array was first validated with artificial constructs for CDC6, VEGF, and PCBP4 isoforms. The platform was then applied to the analysis of differential splice forms for 8000 genes in lung cancer samples compared to matched normal lung tissue. The expression of lung cancer-associated splice isoforms was validated by RT-PCR. Overexpression of splice isoforms was identified for genes encoding CEACAM1, FHL-1, MLPH, and SUSD2. None of these splicing isoforms had been previously associated with lung cancer. In conclusion, this highly accurate methodology enables the detection of alternative splicing events in complex biological samples, providing a powerful tool to identify novel diagnostic and prognostic biomarkers for cancer and other pathologies.