Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002736 (amyotrophic lateral sclerosis)
 19,048 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present work two second-order calibration methods, generalized rank annihilation method (GRAM) and multivariate curve resolution-alternating least square (MCR-ALS) have been applied on standard addition data matrices obtained by gas chromatography-mass spectrometry (GC-MS) to characterize and quantify four unsaturated fatty acids cis-9-hexadecenoic acid (C16:1omega7c), cis-9-octadecenoic acid (C18:1omega9c), cis-11-eicosenoic acid (C20:1omega9) and cis-13-docosenoic acid (C22:1omega9) in fish oil considering matrix interferences. With these methods, the area does not need to be directly measured and predictions are more accurate. Because of non-trilinear conditions of GC-MS data matrices, at first MCR-ALS and GRAM have been used on uncorrected data matrices. In comparison to MCR-ALS, biased and imprecise concentrations (%R.S.D.=27.3) were obtained using GRAM without correcting the retention time-shift. As trilinearity is the essential requirement for implementing GRAM, the data need to be corrected. Multivariate rank alignment objectively corrects the run-to-run retention time variations between sample GC-MS data matrix and a standard addition GC-MS data matrix. Then, two second-order algorithms have been compared with each other. The above algorithms provided similar mean predictions, pure concentrations and spectral profiles. The results validated using standard mass spectra of target compounds. In addition, some of the quantification results were compared with the concentration values obtained using the selected mass chromatograms. As in the case of strong peak-overlap and the matrix effect, the classical univariate method of determination of the area of the peaks of the analytes will fail, the "second-order advantage" has solved this problem successfully.
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PMID:Second-order standard addition for deconvolution and quantification of fatty acids of fish oil using GC-MS. 1907 46

Protein folding is a complex process that can take place through different pathways depending on the inducing agent and on the monitored time scale. This diversity of possibilities requires a good design of experiments and powerful data analysis tools that allow operating with multitechnique measurements and/or with diverse experiments related to different aspects of the process of interest. Multivariate curve resolution-alternating least squares (MCR-ALS) has been the core methodology used to perform multitechnique and/or multiexperiment data analysis. This algorithm allows for obtaining the process concentration profiles and pure spectra of all species involved in the protein folding from the sole raw spectroscopic measurements obtained during the experimental monitoring. The process profiles provide insight on the mechanism of the process studied whereas the shapes of the recovered pure spectra help in the characterization of the protein conformations involved. Relevant features of the MCR-ALS algorithm are the possibility to handle fused data, i.e., series of experiments monitored with different techniques and/or performed under different experimental conditions, and the flexibility to include a priori information linked to general properties of concentration profiles and spectra and to the kinetic model governing the folding process. All these characteristics help to obtain a comprehensive description of the protein folding mechanism. To our knowledge, this work includes for the first time the simultaneous analysis of steady-state and short-time scale kinetic experiments linked to a protein folding process. The potential of this methodology is shown taking myoglobin as a model system for protein folding or, in general, for the study of any complex biological process that needs multitechnique and multiexperiment monitoring and analysis. Transformations in myoglobin due to changes in pH have been monitored by ultraviolet/visible (UV-vis) absorption and circular dichroism (CD) spectroscopy. Steady-state and stopped-flow experiments were carried out to account for the evolution of the process at different time scales. In this example, the multiexperiment analysis has allowed for the reliable detection and modeling of a kinetic transient species in the myoglobin folding process, absent in the steady-state working conditions.
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PMID:Experimental monitoring and data analysis tools for protein folding: study of steady-state evolution and modeling of kinetic transients by multitechnique and multiexperiment data fusion. 1910 Aug 82

The physicochemical characterization of the peptide sequence E1(145-162) corresponding to the structural protein E1 of the hepatitis G virus was done by studying its interaction with model membranes. Small unilamellar vesicles (SUVs) of dimyristoylphosphatidylglycerol or dimyristoylphosphatidylcholine were chosen as mimetic membranes. Peptide incorporation and location in the phospholipid bilayer was investigated by fluorescence anisotropy with SUVs labeled with diphenylhexatriene (DPH) or trimethylammonium-DPH. The addition of the peptide E1(145-162) showed significant changes in the anisotropy values of the probe located at the air/water interface. These results indicate that the peptide E1(145-162) preferably interacts with the lipid surface without penetrating inside the bilayer. A series of fluorescence experiments based on tryptophan peptide fluorescence were modeled by means of multivariate curve resolution-alternating least squares (MCR-ALS) algorithm to further study the peptide interaction with bilayers at different temperatures. The preliminary results obtained with MCR-ALS showed how the peptide concentration decay is directly linked to the appearance of a new specie, which corresponds to the lipid-peptide binding. These results provide useful information for the design of synthetic immunopeptides that can be incorporated into a liposomal system with potential to promote a direct delivery of the membrane-incorporated immunogen to the immunocompetent cells, thus increasing the immuno response from the host.
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PMID:Fluorescence study of the dynamic interaction between E1(145-162) sequence of hepatitis GB virus C and liposomes. 1915 20

One of the most suitable analytical techniques used for edible oil quality control is Fourier transform mid infrared spectroscopy (FT-MIR). FT-MIR spectroscopy was used to continuously characterize the aging of various edible oils thanks to a specific aging cell. There were differences in the spectra of fresh and aged oils from different vegetable sources, which provide the basis of a method to classify them according to the oxidative spectroscopic index value. The use of chemometric treatment such as multivariate curve resolution-alternative least square (MCR-ALS) made it possible to extract the spectra of main formed and degraded species. The concentration profiles gave interesting information about the ability of the various oils to support the oxidative treatment and showed that all oils present the same aging process. Both methods led to concordant results in terms of induction times determined by the oxidative spectroscopic index and the appearance of oxidation products revealed by MCR-ALS.
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PMID:Infrared study of aging of edible oils by oxidative spectroscopic index and MCR-ALS chemometric method. 1915 93

The equilibria of a new Schiff base derived from 3,6-bis((aminoethyl)thio)pyridazine were studied spectrophotometrically with the aid of factor-analytical methods. Hard modeling program was used for determination of the acidity constants of the Schiff base in dimethylformamide (DMF)/water mixture (30:70 v/v). In this method acidity constant equations act as hard models and the score vectors obtained by decomposing of absorbance data matrix will be linear combinations of equilibrium concentrations of species that exist in the absorption matrix. Two rank annihilation factor analysis (TRAFA) was used as a standard method to investigate the accuracy of the method. The tautomerization constant, K(t), of the Schiff base solution in various DMF/water mixtures has also been determined using spectral variations of the Schiff base solutions in various volume ratios of water with the aid of evolving factor analysis (EFA) and multivariate curve resolution alternative least squares (MCR-ALS) methods. In addition the intramolecular hydrogen bonding strength and its related thermodynamic parameters have been determined using MCR-ALS and spectral variation of the Schiff base solutions in different temperatures.
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PMID:Spectrophotometric determination of acidity and tautomeric constants and hydrogen bonding strength for a new Schiff base using hard modeling and multivariate curve resolution alternative least squares methods. 1918 17

The determination of the three-dimensional structure of a weak protein-protein complex in solution using small-angle X-ray scattering requires the deconvolution of its contribution from those of other components coexisting in equilibrium. Using the oligomerization equilibrium of low molecular weight phosphatase (lmwPTP) as a model system, we show computationally and experimentally that the individual low-resolution structures of monomeric and dimeric lmwPTP can be determined from a small number of SAXS curves using the multivariate curve resolution with alternating least squares (MCR-ALS) algorithm. The dimeric complex represents no more than 15% of the macromolecules in the most concentrated sample. The derived structures are in good agreement with the crystallographic ones and the dissociation constant matches the one measured by NMR. These results demonstrate the power of SAXS, in combination with MCR-ALS, to study transient biomolecular complexes. The limits of the method were explored using a three-species model that describes the oligomerization of lmwPTP at higher concentrations.
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PMID:Low-resolution structures of transient protein-protein complexes using small-angle X-ray scattering. 1927 29

Fourier transform infrared (FTIR) spectroscopy is the most common spectroscopic technique used for study of protein structure. Initially, band deconvolution techniques were applied to determine the secondary structure of proteins. Recently, several multivariate regression methods have been used to predict the secondary structure of proteins as an alternative to the previous methods. Multivariate curve resolution-alternating least squares (MCR-ALS) was applied on the FTIR spectra of proteins to resolve the fraction and spectral profiles of different structural motifs. Initial estimates of spectral profiles of different protein motifs were built using orthogonal projection approach (OPA). Predicted fractions of alpha-helix and beta-sheet obtained by MCR-ALS technique were compared with those from partial least squares (PLS) modeling which revealed superiority of the former. If we consider the possibility of pure spectra prediction in addition to the prediction of secondary structure from the data set, MCR-ALS can be proposed as a very valuable alternative for qualitative and quantitative study of protein structures.
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PMID:Application of multivariate curve resolution-alternating least squares (MCR-ALS) for secondary structure resolving of proteins. 1937 89

Multivariate curve resolution with alternating least squares (MCR-ALS) has been applied to voltammetric data obtained from analysis of the competitive binding of cysteine (Cys) and cysteine-glycine (Cys-Gly) by Cd(II) as a first approach towards mixtures of phytochelatins and related compounds in natural media. From different starting points, the possibilities of formation of mixed complexes and/or displacements between ligands are investigated. Analysis of the resulting unitary voltammograms and concentration profiles of the resolved components by MCR-ALS suggests that the strongest ligand (Cys-Gly) is able to displace the weakest (Cys) from its metal complexes, whereas this does not happen in the opposite direction. On the other hand, no evidence of Cd mixed-ligand complexes was found.
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PMID:Competitive binding of cadmium by plant thiols: an electrochemical study assisted by multivariate curve resolution. 1938 18

Multivariate data analysis methods are applied to study of the geographical and temporal distribution of nitric oxide (NO) in Catalonia (North-East Spain), measured during the period 2001-2006 in 50 sampling stations. Principal component analysis (PCA) and Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) were applied for that purpose. The simultaneous analysis of NO data from sampling stations showed that its geographical distribution was rather uniform during the period considered. When three individual sampling stations were considered (two urban sites and one rural location), three different temporal patterns were resolved, with marked daily-night changes mainly attributed to traffic and also, important winter-summer seasonal variations. A decreasing trend in the levels of NO has been also observed in recent years. Comparison with nitrogen dioxide (NO(2)) profiles shows that the daily variation is quite similar to the NO variation, however NO(2) displays very little oscillations along the seasons and no reduction of its concentration was observed in the last years, contrasting with NO tendencies. The use of MCR-ALS is confirmed to be a useful method to improve interpretability in atmospheric contamination studies. The use of non-negativity and trilinearity constraints is shown to provide improved interpretations of the different contamination patterns in environmental terms.
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PMID:Variation patterns of nitric oxide in Catalonia during the period from 2001 to 2006 using multivariate data analysis methods. 1942 61

Curing reactions include side and consecutive reactions while the polymer is growing. In this paper, we used multivariate curve resolution-alternating least squares (MCR-ALS) to obtain quantitative information about the concentration of the chemical species involved in these reactions. The cationic curing reaction between diglycidyl ether of bisphenol A (DGEBA) and gamma-valerolactone (gamma-VL) was monitored by infrared spectroscopy (FTIR-ATR). If the MCR-ALS method is to be used with recorded spectral data, the rank deficiency usually present in the data matrix needs to be overcome and the goodness of the results depends on the initial estimates of the chemical species involved in the reaction. Our strategy was to sequentially apply MCR-ALS in the time intervals where there is selectivity for some reactions and to use the error criterion based on the global phase angle to identify the optimal number of iterations in ALS. The estimated spectra were sequentially incorporated into the data matrix to overcome the rank deficiency. The MCR-ALS results are evaluated by the residuals and parameters such as lack of fit, the percentage of explained variance and the coefficient of dissimilarity between the recovered spectra and the spectra of the pure species, when it is possible. For intermediate species, the correspondence between the ALS spectra solution and the chemical knowledge of this species was also qualitatively evaluated. The goodness of the estimated concentration profile of the two reagents gamma-VL and DGEBA, was evaluated by the correlation coefficient value between the estimated profile and the profile obtained when the specific absorption bands were monitored at 1776 and 910 cm(-1), respectively for each reagent. The correlation coefficient values were 0.9954 and 0.9885, respectively.
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PMID:MCR-ALS for sequential estimation of FTIR-ATR spectra to resolve a curing process using global phase angle convergence criterion. 1942 71


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