Rhona M. Jack

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BACKGROUND Paraoxonase (PON1), a HDL-associated enzyme, protects against toxicity from specific organophosphorus compounds and oxidized lipids. Common polymorphisms in the PON1 gene have been identified and characterized in the coding region, 5' regulatory region and 3' UTR. The Q192R coding region polymorphism determines substrate-dependent differences in(More)
The developed algorithm reported herein, referred to as "DotMap," addresses the need to rapidly identify analyte peak locations in gas chromatography x gas chromatography-time of flight mass spectrometry (GC x GC-TOF-MS) data. The third-order structure of GC x GC-TOF-MS data is such that at each point in the GC x GC chromatogram, a complete mass spectrum is(More)
BACKGROUND The implementation of mass spectrometry to measure serum 25-hydroxyvitamin D [25(OH)D] concentrations has led to concerns regarding the measurement and reporting of the C3-epimer of 25-hydroxyvitamin D(3) [3-epi-25(OH)D(3)], for which there is a near-total lack of data regarding its clinical significance. METHODS We developed a chromatographic(More)
CONTEXT Tests that are performed outside of the ordering institution, send-out tests, represent an area of risk to patients because of complexity associated with sending tests out. Risks related to send-out tests include increased number of handoffs, ordering the wrong or unnecessary test, specimen delays, data entry errors, preventable delays in reporting(More)
The clinical phenotype of Sanfilippo Syndrome is caused by one of four enzyme deficiencies that are associated with a defect in mucopolysaccharide metabolism. The four subtypes (A, B, C, and D) are each caused by an enzyme deficiency involved in the degradation of heparan sulfate. We have developed a highly efficient synthesis of the substrates and internal(More)
Purpose: Acid alpha-glucosidase is present in various tissues, including blood cells. Historically, enzyme measurement in cultured fibroblasts, or muscle, has been the gold standard to confirm a diagnosis of Pompe disease, due to the possibility of alternate isoenzyme activity masking disease in white cell assays. Enzyme measurement in an isolated(More)
This report is about applying a Fisher ratio method to entire four dimensional (4D) data sets from third-order instrumentation data. The Fisher ratio method uses a novel indexing scheme to discover the unknown chemical differences among known classes of complex samples. This is the first report of a Fisher ratio analysis procedure applied to entire 4D data(More)
BACKGROUND Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are typically measured in urine for the diagnosis and monitoring of neuroblastoma, a tumor in children <5 y. A protocol for evaluation of serum VMA and HVA has been utilized at our institution for approximately 25 y, originally validated using high performance liquid chromatography (HPLC)(More)