Biomedical subjects

Adrian P Goodey

Publications and source records attributed to Adrian P Goodey.

3 recordsLinked to original sources

PubMed2005

A microchip CD4 counting method for HIV monitoring in resource-poor settings.

BACKGROUND: More than 35 million people in developing countries are living with HIV infection. An enormous global effort is now underway to bring antiretroviral treatment to at least 3 million of those infected. While drug prices have dropped considerably, the cost and technical complexity of laboratory tests essential for the management of HIV disease, such as CD4 cell counts, remain prohibitive. New, simple, and affordable methods for measuring CD4 cells that can be implemented in resource-scarce settings are urgently needed. METHODS AND FINDINGS: Here we describe the development of a prototype for a simple, rapid, and affordable method for counting CD4 lymphocytes. Microliter volumes of blood without further sample preparation are stained with fluorescent antibodies, captured on a membrane within a miniaturized flow cell and imaged through microscope optics with the type of charge-coupled device developed for digital camera technology. An associated computer algorithm converts the raw digital image into absolute CD4 counts and CD4 percentages in real time. The accuracy of this prototype system was validated through testing in the United States and Botswana, and showed close agreement with standard flow cytometry (r = 0.95) over a range of absolute CD4 counts, and the ability to discriminate clinically relevant CD4 count thresholds with high sensitivity and specificity. CONCLUSION: Advances in the adaptation of new technologies to biomedical detection systems, such as the one described here, promise to make complex diagnostics for HIV and other infectious diseases a practical global reality.

Algorithms↗

PubMed2003

DNA hybridization and discrimination of single-nucleotide mismatches using chip-based microbead arrays.

The development of a chip-based sensor array composed of individually addressable agarose microbeads has been demonstrated for the rapid detection of DNA oligonucleotides. Here, a "plug and play" approach allows for the simple incorporation of various biotinylated DNA capture probes into the bead-microreactors, which are derivatized in each case with avidin docking sites. The DNA capture probe containing microbeads are selectively arranged in micromachined cavities localized on silicon wafers. The microcavities possess trans-wafer openings, which allow for both fluid flow through the microreactors/analysis chambers and optical access to the chemically sensitive microbeads. Collectively, these features allow the identification and quantitation of target DNA analytes to occur in near real time using fluorescence changes that accompany binding of the target sample. The unique three-dimensional microenvironment within the agarose bead and the microfluidics capabilities of the chip structure afford a fully integrated package that fosters rapid analyses of solutions containing complex mixtures of DNA oligomers. These analyses can be completed at room temperature through the use of appropriate hybridization buffers. For applications requiring analysis of < or = 10(2) different DNA sequences, the hybridization times and point mutation selectivity factors exhibited by this bead array method exceed in many respects the operational characteristics of the commonly utilized planar DNA chip technologies. The power and utility of this microbead array DNA detection methodology is demonstrated here for the analysis of fluids containing a variety of similar 18-base oligonucleotides. Hybridization times on the order of minutes with point mutation selectivity factors greater than 10000 and limit of detection values of approximately 10(-13) M are obtained readily with this microbead array system.

Base Pair Mismatch↗

PubMed2003

Multishell microspheres with integrated chromatographic and detection layers for use in array sensors.

The development of miniaturized chromatographic systems localized within individual polymer microspheres and their incorporation into a bead-based cross-reactive sensor array platform is reported. The integrated chromatographic and detection concept is based on the creation of distinct functional layers within the microspheres. In this first example of the new methodology, complexing ligands have been selectively immobilized to create "separation" layers harboring an affinity for various metal cations. Additionally, a broadly responsive compleximetric dye is used to yield the "detection" layers that exhibit optical responses in the presence of a wide range of metal cations. Information concerning the identities and concentrations of solution-dissolved metal cations can be drawn from the temporal properties of the beads' optical responses. Varying the nature of the ligand in the separation shell yields a collection of cross-reactive sensing elements well-suited for use in array-based micrototal analysis systems. Accordingly, such beads have been incorporated into the "Electronic Taste Chip" platform and used for discriminating among aqueous metal cation solutions.

Anthraquinones↗