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Biomedical subjects

I M Warner

Publications and source records attributed to I M Warner.

52 records · Page 3Linked to original sources
PubMed1995

Combined polymerized chiral micelle and gamma-cyclodextrin for chiral separation in capillary electrophoresis.

A combination of a polymerized chiral micelle, poly(sodium N-undecylenyl-D-valinate) [poly(D-SUV)] and gamma-cyclodextrin (gamma-CD) is used for the first time for chiral separation in capillary electrophoresis. A simple theory is presented to rationalize the synergistic effect of the enantioselectivity obtained by use of poly(D-SUV) and gamma-CD in combination. A mixture of four enantiomeric pairs is successfully resolved by use of this combination. The resolutions of the enantiomers using this approach are far superior to those obtained by use of either poly(D-SUV) or gamma-CD alone. In addition, the effects of the antipode (L-SUV), gamma-CD concentration, buffer concentration, organic solvents, and urea concentration on the resolution are also examined.

Buffers↗
PubMed1991

Sensitized room-temperature luminescence in reverse micelles using lanthanide counterions as acceptors.

The analytical usefulness of sensitized room-temperature luminescence in reverse micelles using lanthanide counterions is examined. The technique is based on the unique luminescent properties of tripositive lanthanide metal ions as counterions for the surfactant and the molecular organization produced by reverse micelles. After excitation, the analyte molecule transfers its triplet-state energy to an acceptor molecule (lanthanide), which subsequently emits luminescence. Two surfactants with different lanthanide counterions have been synthesized and characterized by spectroscopic and mass spectrometric techniques. When compared to the lanthanide salt, the sensitized luminescence of the lanthanide surfactant is substantially enhanced. The exact locations of the analyte and the counterion in the micellar system are discussed. The efficiencies of energy transfer for the two surfactants are compared.

Chemistry Techniques, Analytical↗
PubMed1990

Determination of platinum in blood by adsorptive voltammetry.

This work describes a sensitive method for the determination of platinum in blood, which can be used for determining the natural levels of platinum in human blood, for monitoring patients treated with platinum cytotoxic drugs, and for monitoring occupational exposure to these drugs and other platinum compounds. The method involves dry ashing of blood samples in a muffle furnace and determination of platinum by adsorptive voltammetric (AV) measurement of the catalytic reduction of protons by the platinum-formazone complex. The detection limit for a 100-microL sample of blood is 0.017 micrograms/L, with a recovery of 94% and a relative standard deviation of 7% at a platinum level of 1 microgram/L. By using this method, the natural levels of platinum in human blood were found to be in the range 0.1-2.8 micrograms/L (median = 0.6 micrograms/L). These results were verified by inductively coupled plasma mass spectrometry (ICP-MS) with blood prepared by wet ashing and using gold as an internal standard.

Electrochemistry↗
PubMed1988

Purification, partial characterization, and seroreactivity of a genuswide 60-kilodalton Legionella protein antigen.

A genuswide protein antigen extracted from Legionella pneumophila serogroup 1 (strain Philadelphia 1) cells was enriched by differential pelleting and ammonium sulfate precipitation and subsequently purified with a combination of high-performance size-exclusion and ion-exchange chromatography. The protein has an apparent molecular weight of 650,000 before and 63,000 after urea (5 M) treatment, as determined by size-exclusion chromatography. These proteins resolved to a single band of 60,000 after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The urea-treated protein had an isoelectric point of 5.8. This purified 60-kilodalton protein reacted with a convalescent-phase serum sample from a patient with legionellosis and rabbit immune sera prepared against each of 23 Legionella species. The 60-kilodalton protein may be useful in developing diagnostic tests for legionellosis.

Animals↗
PubMed1987

Fluorescence-detected circular dichroism studies of serum albumins.

Multidimensional fluorescence-detected circular dichroism (FDCD) is used to investigate the binding of bilirubin to four mammalian serum albumins. It is shown that the complexes formed with the albumins have distinctly different FDCD spectra. The effect of the pH-dependent transition from basic to acidic conditions on the complexes is examined. The binding of warfarin to albumin is also presented to demonstrate the general analytical utility of the multidimensional FDCD measurement for biochemical analysis.

Animals↗
PubMed1987

Survey of polynuclear aromatic compounds in oil refining areas.

Air samples in and around refinery areas were collected over a 3-year period. The results of the analysis for polynuclear aromatic compounds listed as priority pollutants by the United States Environmental Protection Agency are presented. The particulate matters in the air were collected on glass fiber filters using high volume samplers. These samples were later Soxhlet extracted with cyclohexane, and then extracted with DMSO/pentane for isolation of the polynuclear aromatic compounds. These extracts were then analyzed using gas chromatography-mass spectrometry for specified polynuclear aromatic compounds. It was found that much higher concentrations of these aromatic compounds were found in one refinery compared to another one. In general, the number of these priority pollutants detected and their concentrations were higher in sites inside the refineries relative to a site outside the refineries.

Journal Article↗
PubMed1987

Comparison of Flavobacterium and Sphingobacterium species by enzyme profiles, with use of pattern recognition of two-dimensional fluorescence data.

Enzyme profiles of eight Flavobacterium species and one Sphingobacterium species were compared after using a two-dimensional fluorescence technique. Enzyme contents and corresponding activities were rapidly determined for whole-cell preparations after incubation with a mixture of preselected fluorogenic substrates. A two-dimensional fluorescence spectrum of the resulting product mixture, measured with a video fluorometer, provided a characteristic "fingerprint" for each organism. Comparison of fluorescent spectra was facilitated by a Fourier-transform-based pattern-recognition algorithm and by a clustering technique involving the Pearson product-moment correlation coefficient. F. multivorum, F. thalpophilum, and S. mizutae formed one cluster; F. indologenes, F. spiritivorum, F. odoratum, and F. balustinum formed a second. F. meningosepticum was intermediate between the first and second cluster, whereas F. breve was different from all other strains examined, based on their spectral dissimilarity indices and correlation coefficients.

Flavobacterium↗
PubMed1986

A rapid enzymatic procedure for "fingerprinting" bacteria by using pattern recognition of two-dimensional fluorescence data.

We describe a rapid fluorescence technique for bacterial "fingerprinting," based on the differences in enzyme content and activity of various bacteria. Bacterial cells are incubated with a mixture of carefully chosen fluorogenic enzyme substrates to produce fluorophores with unique emission and excitation properties. The resulting two-dimensional fluorescence spectrum of the product mixture produces a pattern characteristic of the bacterium. A Fourier-transform-based pattern recognition algorithm is used for spectral matching and for differentiating visually similar spectra. This sensitive technique is potentially applicable to differentiation and identification of bacteria in clinical laboratories.

Bacteria↗
PubMed1983

Characterization of bacteria by mixed-dye fluorometry.

We describe an indirect detection method for bacterial identification and differentiation, based on selective adsorption of several fluorescent dyes. The lipid, protein, and nucleic acid components of fixed whole cells are stained with two mixtures, each containing two fluorochromes. The unadsorbed dyes were measured simultaneously with a video fluorometer [Clin Chem 22: 1483, 1976]. A dye-absorption matrix of the response can be generated, and we did so for each of nine bacteria. These responses were compared to a control or "complete" response matrix, and the response ratios of each bacterial species for each of the four dyes were calculated and plotted to obtain a characteristic pattern. From the response-ratio plots, plus simple pattern-recognition techniques, we could differentiate among all the bacteria. This rapid, sensitive technique is potentially applicable to a wide variety of bacteria.

Acridine Orange↗
PubMed1980

Identification of fluorescent Pseudomonas species.

Fluorescent pseudomonads may be identified through examination of the fluorescence "profiles" of diffusible pigments released into the growth medium. The profiles are obtained in the form of an emission-excitation matrix, the elements of which correspond to fluorescence intensity as a function of multiple exciting and emitting wavelengths. Use of a rapid scanning fluorometer to acquire these data provides a relatively fast method for identification of the microorganisms after incubation. This procedure can potentially be expanded for the identification of other microorganisms.

Pigments, Biological↗
PubMed1980

Multiparameter appraoch to the "fingerprinting" of fluorescent Pseudomonads.

A recent study has shown that an emission-excitation matrix could be used to provide a unique fingerprint for the selective identification and characterization of certain species of Pseudomonas. This paper describes the results of a systematic study of the variables that contribute to the uniqueness of the fingerprint. Additional insight concerning the nature of the fluorescent pigments of these species is gained by analysis with a high-performance liquid chromatograph/video fluorometer combination. While providing information about the analytical variables contributing to the analysis, this combination also added the variable of chromatographic retention time for unambiguous fingerprinting.

Autoanalysis↗
PubMed1976

Multicomponent analysis in clinical chemistry by use of rapid scanning fluorescence spectroscopy.

To be useful in the clinical laboratory, multicomponent fluorescence analysis requires both the rapid measurement of the fluorescence intensity at a variety of excitation and emission wavelengths and the unambiguous reduction of the data by efficient algorithms. The Video Fluorometer, which exploits the multi-channel capability of a low-light-level television sensor to simultaneously acquire excitation and emission spectra, can meet the first requirement. For example, a complete set of emission and excitation spectra for perylene can be obtained in less than 2 s at concentrations of 10(-10) mol/liter. To meet the second need, we present two types of data-reduction strategies: (a)a least-squares fit to the data, with use of the spectra of previously determined compounds likely to be present; and (b)a determination of the eigenvalues and eigenvectors fo the fluorescence matrix, from which the number of components and the possible spectra of each can be estimated. Computer simulations of the least-squares fitting algorithms show that five strongly overlapping components can be determined in the presence of noise with an accuracy of better than 5%. Also, a fluorescent sample containing two species with very similar but unknown spectral properties can be resolved to obtain the spectrum of each.

Anthracenes↗