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Biomedical subjects

D Thakkar

Publications and source records attributed to D Thakkar.

3 recordsLinked to original sources

DNA microarray technology for neonatal screening.

Modern molecular biology, owing much to the Human Genome Initiative, has elucidated many of the genetic mechanisms underlying heritable metabolic disease. While the use of molecular methods has flourished in research laboratories, complexity and cost have limited their utility in newborn screening. Newborn blood cards provide high quality DNA samples able to provide reliable support to highly multiplexed polymerase chain reactions (PCR). New manufacturing processes have reduced the cost of DNA microarray technology to the point where it is a practical tool for population screening. In a single assay, a DNA microarray facilitates the co-detection of amplification products diagnostic for several genetic diseases. High throughput is achieved with automation at every step, from DNA extraction to detection of hybrids. We suggest that it is both feasible and practical to develop a first-tier newborn screening protocol based upon multiplex PCR and analysis of amplification products using DNA microarrays. Initial data utilizing the model systems of sickle cell disease, alpha-1-antitrypsin deficiency and Factor V Leiden will be reported.

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Enhanced cellular uptake of oligonucleotides by EGF receptor-mediated endocytosis in A549 cells.

PURPOSE: The goal of this study was to investigate the feasibility of utilizing epidermal growth factor (EGF) receptor-mediated endocytosis to enhance cellular uptake and targeting of oligonucleotides in epithelial cancer cells. To overcome the problem of endosomal entrappment associated with receptor-mediated delivery, we also examined the effects of two fusogenic peptides, polymyxin B and influenza HA2 peptide, for their capability to promote cytoplasmic delivery of oligonucleotides. METHODS: A molecular conjugate consisting of EGF and poly-L-lysine (PL) was synthesized and complexed with 5' fluorescently-labeled oligonucleotide. Cellular uptake of the complex in presence or absence of the fusogenic peptides was monitored fluorometrically. Microscopic studies were performed to visualize the intracellular distribution of the oligonucleotide. RESULTS: Cells treated with the complex exhibited intracellular fluorescence intensity significantly enhanced over free oligonucleotide-treated controls. The uptake of the complex was shown to occur via the EGF receptor-mediated pathway. Fluorescence microscopic studies revealed cellular internalization of the complex, however, the complex appeared to be accumulated in endocytic vesicles. Exposure of the cells to complex in presence of HA2 peptide and polymyxin B resulted in a more diffused intracellular fluorescence pattern and a corresponding increase in fluorescence intensity. These results are consistent with the known fusion and destabilizing activities of the peptides. CONCLUSIONS: Since EGF receptors are overexpressed in many cancer cell types, the EGF-PL conjugate may potentially be used as an effective and selective delivery system to enhance uptake of oligonucleotides into cancer cells.

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