David J. Newman

Bio: David J. Newman is an academic researcher from St Helier Hospital. The author has contributed to research in topics: Renal function & Cystatin C. The author has an hindex of 23, co-authored 51 publications receiving 3418 citations.

Principles And Practice Of Immunoassay

Abstract: The antigen-antibody reaction production of polyclonal antibodies production of monoclonal antibodies modification of antibodies separation techniques for heterogeneous immunoassays properties of antibodies and general considerations on reagnet optimization radio-labelled immunoassay heterogeneous enzyme immunoassay including enzyme amplification homogeneous enzyme mediated immunoassays including enzyme, substrate, cofactor amd inhibitor labels fluoro-immunoassay including time resolved flourescence homogeneous fluoro-immunoassay including fluorescence polarization and fluorescence excitatin transfer phosporescence immunoassay luminescence immunoassays including enhanced systems electrometric immunoassays alternate optical immunoassays including evanescent wave - surface plasma resonance multilayer thin film carrier immunoassay systems dry reagent carrier immunoassay systems immunochromatographic immunoassays immunoconcentration immunoassay radial partition immunoassay data handling for immunoassay.

Initial evaluation of cystatin C measurement by particle-enhanced immunonephelometry on the Behring nephelometer systems (BNA, BN II)

Abstract: Serum cystatin C has been suggested as a new marker of glomerular filtration rate (GFR). We describe a fully automated and rapid particle-enhanced nephelometric immunoassay (PENIA) for measuring serum cystatin C on the Behring nephelometer systems (BNA, BN II). Each sample is analyzed in 6 min with as many as 75 samples per batch. The assay covers the range 0.23–7.25 mg/L, up to seven times the upper limit of normal. The intra- and interassay imprecision are <3.3% and <4.5%, respectively. There is absolute linearity across the assay range ( r 2 = 0.997), with analytical recovery by cystatin C addition between 95% and 109% (mean 102%). Hemoglobin (≤8.0 g/L), bilirubin (≤488 μL), triglycerides (≤23 mmol/L), rheumatoid factor (≤2000 kIU/L), and myeloma paraprotein (≤41 g/L) do not interfere with the assay. This assay agreed well with an in-house particle-enhanced turbidimetric immunoassay (PETIA) (mean difference = 1.73 ± 2.10) and a commercial PETIA (mean difference = 1.13 ± 0.86). This is a new assay by which cystatin C may be effectively used as a marker of GFR estimation.

Adult reference ranges for serum cystatin C, creatinine and predicted creatinine clearance

Abstract: Serum cystatin C measurement has been previously shown by ourselves and others to be a better indicator of changes in glomerular filtration rate (GFR) than serum creatinine. However, the available ...

Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate.

Abstract: Using standardized creatinine assays, the authors remeasured serum creatinine levels in 1628 patients whose glomerular filtration rate (GFR) had been measured by urinary clearance of 125I-isothalam...

Assessing Kidney Function — Measured and Estimated Glomerular Filtration Rate

Abstract: In the coming years, estimates of the glomerular filtration rate (GFR) may replace the measurement of serum creatinine as the primary tool for the assessment of kidney function. Indeed, many clinical laboratories already report estimated GFR values whenever serum creatinine is measured. This review considers current methods of measuring GFR and GFR-estimating equations and their strengths and weaknesses as applied to chronic kidney disease.

Aptamers: An Emerging Class of Molecules That Rival Antibodies in Diagnostics

Abstract: Antibodies, the most popular class of molecules providing molecular recognition needs for a wide range of applications, have been around for more than three decades. As a result, antibodies have made substantial contributions toward the advancement of diagnostic assays and have become indispensable in most diagnostic tests that are used routinely in clinics today. The development of the systematic evolution of ligands by exponential enrichment (SELEX) process, however, made possible the isolation of oligonucleotide sequences with the capacity to recognize virtually any class of target molecules with high affinity and specificity. These oligonucleotide sequences, referred to as "aptamers", are beginning to emerge as a class of molecules that rival antibodies in both therapeutic and diagnostic applications. Aptamers are different from antibodies, yet they mimic properties of antibodies in a variety of diagnostic formats. The demand for diagnostic assays to assist in the management of existing and emerging diseases is increasing, and aptamers could potentially fulfill molecular recognition needs in those assays. Compared with the bellwether antibody technology, aptamer research is still in its infancy, but it is progressing at a fast pace. The potential of aptamers may be realized in the near future in the form of aptamer-based diagnostic products in the market. In such products, aptamers may play a key role either in conjunction with, or in place of, antibodies. It is also likely that existing diagnostic formats may change according to the need to better harness the unique properties of aptamers.

Protein biomarker discovery and validation: the long and uncertain path to clinical utility.

Abstract: Better biomarkers are urgently needed to improve diagnosis, guide molecularly targeted therapy and monitor activity and therapeutic response across a wide spectrum of disease. Proteomics methods based on mass spectrometry hold special promise for the discovery of novel biomarkers that might form the foundation for new clinical blood tests, but to date their contribution to the diagnostic armamentarium has been disappointing. This is due in part to the lack of a coherent pipeline connecting marker discovery with well-established methods for validation. Advances in methods and technology now enable construction of a comprehensive biomarker pipeline from six essential process components: candidate discovery, qualification, verification, research assay optimization, biomarker validation and commercialization. Better understanding of the overall process of biomarker discovery and validation and of the challenges and strategies inherent in each phase should improve experimental study design, in turn increasing the efficiency of biomarker development and facilitating the delivery and deployment of novel clinical tests.

Expressing the Modification of Diet in Renal Disease Study equation for estimating glomerular filtration rate with standardized serum creatinine values.

Abstract: Purpose: We sought to reexpress the 4-variable Modification of Diet in Renal Disease (MDRD) Study equation for estimation of glomerular filtration rate (GFR) using serum creatinine (Scr) standardized to reference methods. Methods: Serum specimens included creatinine reference materials prepared by the College of American Pathologists (CAP), traceable to primary reference material at the NIST, with assigned values traceable to isotope dilution mass spectrometry (IDMS), a calibration panel prepared by the Cleveland Clinic Research Laboratory (CCRL), and frozen samples from the MDRD Study. Split specimens were measured at the CCRL using the Roche enzymatic and Beckman CX3 kinetic alkaline picrate assays. Results: Roche enzymatic assay results on CAP samples were comparable to IDMS-assigned values. Beckman CX3 assay results in 2004–2005 were significantly higher than but highly correlated with simultaneous Roche enzymatic assay results ( r 2 = 0.9994 on 40 CCRL samples) and showed minimal but significant upward drift from Beckman CX3 assay results during the MDRD Study in 1989–1991 ( r 2 = 0.9987 in 253 samples). Combining these factors, standardized Scr = 0.95 × original MDRD Study Scr. The reexpressed 4-variable MDRD Study equation for Scr (mg/dL) is GFR = 175 × standardized Scr−1.154 × age−0.203 × 1.212 (if black) × 0.742 (if female), and for Scr (μmol/L) is GFR = 30849× standardized Scr−1.154 × age−0.203 × 1.212 (if black) × 0.742 (if female) [GFR in mL · min−1 · (1.73 m2)−1]. Conclusion: When the calibration of Scr methods is traceable to the Scr reference system, GFR should be estimated using the MDRD Study equation that has been reexpressed for standardized Scr.