Validation for quantification of immunoglobulins by Fourier transform infrared spectrometry.

BACKGROUND: The objective of this study was to develop a robust quantification method for simultaneously analyzing molecules in human plasma using the Fourier transform infrared (FT-IR) system with a partial least square (PLS) regression. METHODS: Plasma spectra were analyzed from 4000 to 500 cm(-1) (with 2.0 cm(-1) of resolution and 32 scans), and the molecule concentrations (IgA, IgG, IgM) were measured blindly by using a cross-validation model prepared by PLS analysis of data from 135 samples. RESULTS: There was a significant correlation between the FT-IR predicted concentration and the concentration obtained with the clinical reference method: R(2)=0.98 (IgA), R(2)=0.98 (IgG), and R(2)=0.97 (IgM). The root mean square error of prediction (RMSEP) was 0.05 g.L(-1) (IgA), 0.4 g.L(-1) (IgG), and 0.03 g.L(-1) (IgM). Variability of inter-experimenter reproducibility was less than 2%. The interchangeability of the two methods was studied by using the Bland-Altman method. CONCLUSIONS: Together with PLS analysis, FT-IR spectrometry appears to be an easy-to-use and accurate method to determine multianalyte concentrations in dried human plasma. It could be an alternative tool for rapidly quantifying many molecules after developing a specific predictive model.

Human plasma modifications induced by total joint replacement: analysis by Fourier transform infrared spectroscopy.

To better understand the events occurring after major surgery, we examined the plasma content of 40 patients undergoing elective total joint replacement. For this study, we used Fourier transform infrared (FT-IR) spectroscopy, a nondestructive and sensitive technique, to analyse changes in the vibrational spectra of plasma samples. Important metabolic changes were observed. Both lipid and protein levels were globally decreased one day after surgery as compared with preoperative levels. In contrast, triglyceride, glycerol, saccharide and amino acid contents were largely increased one day after surgery. Moreover, we detected a specific 1180-945 cm(-1) spectral window, which allows good separation of patient sera before surgery from patient sera one day after surgery. One week after surgery, the biochemical changes were not entirely reversed. Thus, FT-IR spectroscopy appears to be a rapid useful tool to investigate the metabolic alterations induced by surgery and the recovery period, and to correlate them with biochemical and physiological data.

Postoperative plasma metabolic consequences of an osseous substitute implantation: analysis by fourier transform infrared spectroscopy.

In this study, we have investigated the postoperative plasma consequences of coral implantation into femoral condyle of rabbits. Analyses were performed using Fourier transform infrared (FT-IR) spectroscopy, a sensitive and nondestructive method, to evaluate plasma modifications one day, one week, one month, and three months after surgery. This technique showed that both surgery and implantation induced important changes of lipidic compounds one day after surgery, with a body lipolysis. Major modifications appeared one week after surgery, with a decrease of protein and saccharide contents, and an increase of amino acids accompanied by a noticeable inflammatory process. These last changes were revealed by a hierarchical classification in the 1430-1295 and 1137-1092 cm(-1) spectral regions, leading to two well-separated groups, before and one week after surgery. After a delayed time of three months and despite a substantial recovery for biomolecules such as proteins and fatty acids, some alterations are always observed, such as for amino acids, triglycerides, and glycerol. Moreover, molecules implicated in the inflammatory process had not reached their initial level.

Fourier transform infrared spectroscopy as a new tool for characterization of mollicutes.

Fourier transform infrared (FT-IR) spectroscopy is a convenient physico-chemical technique to investigate various cell materials. Bacteria of class Mollicutes, identified by conventional methods, as Mycoplasma, Acholeplasma and Ureaplasma genera were characterized using this method. A data set of 74 independent experiments corresponding to fourteen reference strains of Mollicutes was examined by FT-IR spectroscopy to attempt a spectral characterization based on the biomolecular structures. In addition to the separation of Mollicutes within the lipidic region into five main clusters corresponding to the three phylogenetic groups tested, FT-IR spectroscopy allowed a fine discrimination between strains belonging to the same species by using selective spectral windows, particularly in the 1200-900 cm(-1) saccharide range. The results obtained by FT-IR were in good agreement with both taxonomic and phylogenetic classifications of tested strains. Thus, this technique appears to be a useful tool and an accurate mean for a rapid characterization of Mollicutes observed in humans.

Fourier transform IR spectroscopic appraisal of radiation damage in Micrococcus luteus.

Fourier transform IR spectroscopy (FTIR) is used to analyze cells of Micrococcus luteus, the type species of the highly heterogeneous genus Micrococcus that belongs to the Micrococcaceae family. The cells of M. luteus, which is a Gram-positive and yellow-pigmented bacterium, are submitted to increasing doses of gamma radiation. Irradiation leads to the generation of reactive oxygen species that induce biochemical changes as shown in spectral profiles. Beyond a dose of 0.70 kGy, significant differences between samples are observed, particularly in the 1485-900 cm(-1) region, which contains information about membrane lipids, cell wall polysaccharides, and nucleic acids. After a dose of 16.50 kGy, M. luteus is reincubated for times ranging from 1 to 24 h. Postirradiation reincubated bacteria are found far from the control and irradiated cells (mainly in the 985-900 cm(-1) range), suggesting that a biomolecular rearrangement occurs as soon as reincubation begins in the growth medium. Thus, FTIR spectroscopy appears to be a very useful technique for the rapid visualization of the alterations induced by both the radiation and mutagenic response during reincubation. The use of mathematical methods gives good insight into the biomolecular compounds involved in these two mechanisms. In view of these preliminary results, we hypothesize that it can be successfully applied to any type of tissue and that it may be a future interesting tool for evaluating the effects of radiation in humans.

Gamma irradiation and cellular damage in Kocuria rosea: investigation by one- and two-dimensional infrared spectroscopy.

Fourier transform infrared (FT-IR) spectroscopy was used to investigate the radiation-induced effects on Kocuria rosea. Bacterial suspensions at the stationary phase were exposed to increasing doses of gamma radiation. In the region 1350-840cm(-1), assigned to phosphodiester backbone, nucleic acids, and sugar rings, the radical damaging effects were dose-dependent, with the first threshold at 2.75kGy and the second at 13.75kGy inducing more striking spectral variations. Postirradiation reincubation did not significantly affect the biomolecular response, except in the spectral range 1100-1000cm(-1). These observations suggest the occurrence of new phylogenetic characteristics for K. rosea following irradiation. Moreover, two-dimensional analysis was used to highlight correlated evolutions of molecular species as radical aggression increased. The results point to an evolutionary scheme during the time course of irradiation. Thus, one- and two-dimensional IR analyses are convenient means of investigating the metabolic events following oxidative stress generated by either chemical or physical agents.