Biomedical subjects
P Wilding
Publications and source records attributed to P Wilding.
Effect of glycation of low-density lipoprotein on the immunological determination of apolipoprotein B.
Non-enzymatic glycation of low-density lipoprotein (LDL) may contribute to the premature atherogenesis of patients with diabetes mellitus. To assess whether glycation of apolipoprotein B, the predominant protein of LDL, interferes with the ability to immunologically quantify this protein, we prepared and purified glycated LDL by incubating normal plasma samples with high concentrations of glucose. Although both the plasma and the LDL specimens incubated with glucose contained significantly more glycated protein than control specimens, the quantitative interaction of an apolipoprotein B-specific antibody with glycated vs nonglycated LDL was not significantly different. We conclude that apolipoprotein B can be accurately quantified immunologically despite the presence of clinically excessive degrees of LDL glycation.
Macroenzymes: biochemical characterization, clinical significance, and laboratory detection.
"Macroenzymes" are enzymes in serum that have formed high-molecular-mass complexes, either by self-polymerization or by association with other serum components. Many enzymes in serum that are measured in clinical chemistry laboratories can occur in a macroenzyme form. Macroenzymes are interesting clinically because of their association with several diseases, including autoimmune diseases and liver disease, and are being investigated as possible diagnostic markers. Most importantly, macroenzymes frequently interfere with the interpretation of serum enzyme results, and as a result can cause diagnostic and therapeutic errors. We review the biochemical characterization, clinical significance, and laboratory detection of macroenzymes.
Assessment of proton nuclear magnetic resonance spectroscopy for detection of malignancy.
Water-suppressed proton nuclear magnetic resonance spectra were generated (by using 360 and 500 MHz systems) from human plasma and serum samples taken from 35 apparently healthy individuals, 52 patients with overt malignancies, and 37 patients with hypertriglyceridemia (triglycerides greater than 200 mg/dL or 2.26 mmol/L). The line widths from the lipoprotein-lipid methylene and methyl resonances at approximately 1.3 and 0.9 ppm were averaged by the method of Fossel et al. (N Engl J Med 1986;315:1369-76), but, contrary to their findings, we were unable to distinguish normal individuals from those with malignant tumors (e.g., mean +/- SD line width at 360 MHz: normal group = 32.9 +/- 3.6 Hz, malignant group = 28.3 +/- 4.9 Hz). The average line-width measurements (y), however, varied with the triglyceride content (x, mg/dL) of the plasma or serum as follows (logarithmic transformation of the data determined at 360 MHz and regression analysis): y = 110 (x-0.27). Data from both nonmalignant and malignant specimens fit this equation, the coefficient of correlation being -0.91. These findings suggest that considerable caution should be used in interpreting water-suppressed proton NMR spectra for cancer detection.
The "intelligent workstation" for cell-surface phenotyping based on principles of pattern recognition and image analysis.
Technical advancements in computer hardware and the associated computerized architectures allow the design and fabrication of dedicated, modestly expensive computerized workstations to aid humans in complex decision-making tasks. We refer to these as "Intelligent Workstations" because they accommodate the hypothesis-driven reasoning ability of the user into the system. Concomitant with the rapid developments in computers, diagnostic and therapeutic technologies related to cell analysis have undergone growth. Combining these technologies requires careful formulation and analysis of the diagnostic model involving image cytometry. Here we present a model of the intelligent workstation for image cytometry and illustrate its advantages in cell-surface phenotyping. Combining cell morphology with cell-surface phenotyping has clear diagnostic utility that no other widely available methods can supply. Although the reported results are based on samples of peripheral blood, cell suspensions of disaggregated cells can also be analyzed.
Fc receptors for IgG on human neutrophils: analysis of structure and function by using monoclonal antibody probes.
Structural and functional characteristics of Fc receptors for IgG (Fc gamma) on human neutrophils were examined with two monoclonal antibody probes specific for the Fc gamma receptors, Leu 11b and 3G8. To determine the distribution, density, and membrane mobility of the Fc gamma receptor, we used immunogold staining techniques, flow cytometry analysis, and fluorescence microscopy. Both 3G8 and Leu 11b inhibited several cell functions, thereby depicting the regulatory role of the Fc gamma receptor in mediating neutrophil activities. Among the functions studied were release of lysosomal enzymes, release of superoxide anion (O2-), and Fc-dependent rosette formation and phagocytosis. The densities of Fc gamma determinants recognized by Leu 11b and 3G8 on cells from a patient with chronic myelogenous leukemia were less than the density of epitopes on neutrophils from a normal individual. Taken together, the detailed analysis of physical and functional aspects of the Fc gamma receptor on neutrophils described in this study serve as a model for further assessment of the use of Fc gamma phenotyping of cells as a diagnostic tool.
Use of pattern recognition technology for determination of the human differential leukocyte count.
The imprecision, inaccuracy, and clinical sensitivity of an automated differential counter based on pattern recognition technology (HEMATRAK model 590) were evaluated using the NCCLS standard H20-T. The data show that the instrument is capable of performing assays in a manner comparable with the reference method proposed by NCCLS. In addition, data are presented from a multicenter study involving 174 HEMATRAK instruments which showed that the automated systems produce results equivalent to manual procedures (based on approximately 350 individual assays).
Differential scanning calorimetric study of muscle and its proteins: myosin and its subfragments.
Explore the source record for details and available documents.
Immunogold staining: adaptation of a cell-labeling system for analysis of human leukocyte subsets.
We have assessed the Immunogold Cell-Labeling System (IGS) for potential use in the clinical laboratory. In this technique, cell suspensions incubated with monoclonal mouse antibodies are reacted with anti-mouse antibodies labeled with colloidal gold. Surface marker cells, bearing dark blue-black granules, are easily distinguished by light microscopy. The percentages of T cells, T cell subsets, B cells, monocytes, or granulocytes identified by IGS corresponds with numbers obtained by flow cytometry analysis or immunofluorescence studies. Results by IGS and flow cytometry were similar for samples from patients with aberrant lymphocyte populations (e.g., leukemias) or from transplant recipients. IGS may thus be a useful diagnostic technique for studying neoplasias or other immunologically mediated disorders. This technique can also be used to characterize the surface phenotype of leukemic cell lines. The sensitivity and accuracy of IGS can be evaluated by measurements of different cell lines mixed in predetermined ratios.
International Federation of Clinical Chemistry (IFCC). Scientific Committee, Analytical Section. IFCC/WHO principles and recommendations on evaluation of diagnostic reagent sets used in health laboratories with limited resources. Part 3. Selection and evaluation using reference materials. General considerations.
The purpose of this document is to provide general considerations for the selection and evaluation of clinical chemistry kits in laboratories with limited resources. Separate documents have been developed to provide guidance on experimental procedure, the statistical treatment and interpretation of the data and criteria for acceptable performance of diagnostic kits designed to measure specific analytes.
International Federation of Clinical Chemistry, Scientific Committee, Analytical Section: IFCC/WHO principles and recommendations on evaluation of diagnostic reagent sets used in health laboratories with limited resources. Part 4. Evaluation of performance using reference materials of analytes commonly determined in blood serum or plasma.
Explore the source record for details and available documents.
International Federation of Clinical Chemistry, Scientific Committee, Analytical Section: evaluation of performance of diagnostic reagent sets used in health laboratories with limited resources. Appendix A: Glucose.
Explore the source record for details and available documents.
International Federation of Clinical Chemistry (IFCC), Scientific Committee, Clinical Section. The theory of reference values. Part 2. Selection of individuals for the production of reference values.
Explore the source record for details and available documents.
Spectral analysis of urinary reactions: a preliminary study based on a novel concept.
The concept of spectral analysis of urinary reactions (a range of simple chemical tests combined with pattern analysis) is described. A preliminary study in which we used 10 nonspecific tested on untimed urine specimens from 20 controls and 20 diabetics, matched for age and sex, suggested that a combination of these tests could be used to separate diabetics from healthy subjects. This combination, however, did not prove satisfactory for a further group of 13 diabetics. Closer examination revealed that factors such as therapy and glycosuria affected the results of these tests. This approach, which should extend the usefulness of urinalysis, may prove viable when larger groups, and possibly a different set of tests, are used to establish a more robust combination of tests.
Provisional recommendation (1978) on evaluation of diagnostic kits. Part 1. Recommendation for specifications of labelling of clinical laboratory materials (Stage 2, Draft 1).
Explore the source record for details and available documents.
Provisional recommendation (1978) on evaluation of diagnostic kits. Part 2. Guidelines for the evaluation of clinical chemistry kits (Stage 2, Draft1).
Explore the source record for details and available documents.
Provisional recommendation on the theory of reference values (1978). Part 1. The concept of reference values.
Explore the source record for details and available documents.
Drug interference in clinical chemistry: studies on ascorbic acid.
The expert group "Drug Interference in Clinical Chemistry" of the Bureau of Reference, Directorate General for Research, Science and Education of the Commission of the European Communities, consisting of one participant of each member of the European Communities, presents this first report on the final results of its activities. Within the framework of a first stage basic program, the paper describes interferences of therapeutic and elevated doses of ascorbic acid on commonly used clinical chemical methods. This is the result of a bipartite study that was jointly planned, carried out and evaluated. Local and personal influences have been eliminated, as have variations due to methodology, measurement equipment and reagents, in order to be able to present distinct causal effects of ascorbic acid. No definite influence of ascorbic acid on analytical values for urea, cholesterol, calcium, protein, bilirubin, aspartate aminotransferase and alkaline phosphatase could be detected. At therapeutic concentrations, ascorbic acid distinctly interferes with the analysis of glucose, uric acid, creatinine and inorganic phosphate. The extent and direction of interferences vary, depending on the type of reaction, kit and apparatus. In some cases the influence of ascorbic acid results in severe disturbance of the analytical methods leading to useless values.