David Whitcombe

Learn More
Molecular diagnostics is progressing from low-throughput, heterogeneous, mostly manual technologies to higher throughput, closed-tube, and automated methods. Fluorescence is the favored signaling technology for such assays, and a number of techniques rely on energy transfer between a fluorophore and a proximal quencher molecule. In these methods,(More)
We attempted to produce primer-dimers (PDs) from a variety of primers with differing types and extents of complementarity. Where PDs were produced they were cloned and sequenced. We were unable to produce detectable PDs either with individual primers alone or with similar sequence primers even if they had 3'complementarity. These observations led to the(More)
BACKGROUND Mutations in the PIK3CA gene (phosphoinositide-3-kinase, catalytic, alpha polypeptide) have recently been described in a number of cancers, and their detection is currently limited because of the low sensitivity of conventional sequencing techniques. METHODS We combined Amplification Refractory Mutation System (ARMS; AstraZeneca)(More)
We have developed a method whereby a single TaqMan probe can be used for many PCR reactions. We demonstrate its application as an integrated system for the direct measurement of allele-specific amplicon generation coupled to the suppression of primer-dimer accumulation in PCR. The system uses a 5'-exonuclease assay of amplicon annealed fluorogenic probes(More)
The most tangible advances in DNA diagnostics during the past year have been in enhancing existing techniques to simplify their use and improve throughput. This has led to simplified genotyping methods using homogeneous analysis coupled with spectral data output. Miniaturisation and increased throughput have also been achieved through improvements in DNA(More)
We combined the amplification refractory mutation system (ARMS) and fluorescence polarization (FP) to give a homogeneous genomic DNA genotype analysis method. Oligonucleotide probes labeled with the fluorescein dyes fluorescein isothiocyanate and 5-([4,6-dichlorotriazin-2-yl]amino)fluorescein and the rhodamine dye 6-carboxyrhodamine were included in(More)
The chemical mutagen ethylmethanesulphonate (EMS) has been used to generate mutants of Erwinia carotovora subspecies carotovora which are defective in the secretion of pectinases (Pel) and cellulases (Cel) but unaltered for protease (Prt) secretion. Such mutants, called Out-, still synthesize Pel and Cel but these enzymes accumulate within the periplasm.(More)
The accurate detection of DNA sequences is essential for a variety of post human genome projects including detection of specific gene variants for medical diagnostics and pharmacogenomics. A specific DNA sequence detection assay based on surface-enhanced resonance Raman scattering (SERRS) and an amplification refractory mutation system (ARMS) is reported.(More)
Scorpion probes, specific DNA probe sequences maintained in a hairpin-loop, can be modified to carry the components of an exciplex for use as a novel fluorescence-based method for specific detection of DNA. The exciplex partners (5'-pyrenyl and 3'-naphthalenyl) were attached to oligonucleotides via phosphoramidate links to terminal phosphate groups.(More)