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Results for “deconvolution”

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At least 577 records · Page 32Linked to original sources
PubMed1992

Use of high-performance liquid chromatographic peak deconvolution and peak labelling to identify antiparasitic components in plant extracts.

Artemisia absynthium L. is a commonly used medicinal plant for parasitic diseases all over the world. By means of high-performance liquid chromatography with diode-array detection and the PU6100 solvent optimization system, two sesquiterpene lactones, alpha-santonin and ketopelenolid-A, were tentatively identified in methanolic extracts of this plant. alpha-Santonin is a well known antiparasitic compound and could be one of the active principles of this plant species. Reconstructed spectra are potentially useful in scanning a complex chromatogram for pharmacologically active compounds.

Animals↗
PubMed1981

A simple method of realizing the deconvolution of ultrasonic images.

A readily implementable procedure for improving the lateral resolution of ultrasonic images is proposed. The starting point is the approximation of the sound-beam profile by model functions which arise from the convolution of rectangular functions of varying width. From these model functions it is possible to state analytically the Fourier transforms and their reciprocals. These reciprocals can be allocated to a chain circuit of recursive space frequency filters of the first degree, whereby a single basic element corresponds to the rectangular approximation and still produces a resolution improvement by a factor of 1.5. For noise suppression a low-pass limitation function is introduced whose inverse Fourier transform is mathematically similar to the sound-beam approximation; however, as compared with this, it is compressed by a specific factor and thus is optimally matched to the expected resolution improvement.

Computers↗
PubMed1995

Deconvolution of 29Si magic-angle spinning nuclear magnetic resonance spectra of silicate glasses revisited--some critical comments.

It is common practice to quantify 29Si magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra of silicate glasses by using lineshape fitting routines based on Gaussian distribution functions. This procedure depends on several -implicit -assumptions. In this contribution we have addressed and questioned these underlying assumptions. Also "goodness-of-fit" criteria and experimental considerations ("goodness-of-data") have been discussed. Some illustrative practical examples (silica glass, binary Na2O-SiO2 glasses with different Na:Si ratio) are given.

Algorithms↗
PubMedDate not supplied

EPR bone dosimetry: a new approach to spectral deconvolution problems.

EPR dosimetry was used to assess the dose to bone samples from radiation accident victims. Complications in the measurement process arose from overlapping resonances of multiple paramagnetic centers. A computer fitting routine was developed to enhance measurement of the EPR signal of interest, thereby improving the precision of the dose assessment.

Accidents, Occupational↗
PubMed2006

Imaging of multiple mRNA targets using quantum dot based in situ hybridization and spectral deconvolution in clinical biopsies.

Gene expression mapping using microarray analysis has identified useful gene signatures for predicting outcome. However, little of this has been translated into clinically effective diagnostic tools as microarrays require high quality fresh-frozen tissue samples. We describe a methodology of multiplexed in situ hybridization (ISH) using a novel combination of quantum dot (QD)-labeled oligonucleotide probes and spectral imaging analysis in routinely processed, formalin-fixed paraffin embedded human biopsies. The conditions for QD-ISH were optimized using a poly d(T) oligonucleotide in decalcified bone marrow samples. Single and multiplex QD-ISH was performed in samples with acute leukemia and follicular lymphoma using oligonucleotide probes for myeloperoxidase, bcl-2, survivin, and XIAP. Spectral imaging was used for post hybridization tissue analysis, enabling separation of spatially colocalized signals. The method allows quantitative characterization of multiple gene expression using non-bleaching fluorochromes. This is expected to facilitate multiplex in situ transcript detection in routinely processed human clinical tissue.

Biopsy↗
PubMed2004

Deconvoluting the functions of polypeptide N-alpha-acetylgalactosaminyltransferase family members by glycopeptide substrate profiling.

The polypeptide N-alpha-acetylgalactosaminyltransferases (ppGalNAcTs) play a key role in mucin-type O-linked glycan biosynthesis by installing the initial GalNAc residue on the protein scaffold. The preferred substrates and functions of the >20 isoforms in mammals are not well understood. However, current data suggest that glycosylated mucin domains are created by the successive, often hierarchical, action of several specific ppGalNAcTs. Herein we analyzed the glycopeptide substrate preferences of several ppGalNAcT family members using a library screening approach. A 56-member glycopeptide library designed to reflect a diversity of glycan clustering was assayed for substrate activity with ppGalNAcT isoforms using an azido-ELISA. The data suggest that the ppGalNAcTs can be classified into at least four types, which working together, are able to produce densely glycosylated mucin glycoproteins.

Amino Acid Sequence↗
PubMed2004

Resolution of overlapped non-absorbing and absorbing solutes using either an absorption null-balance detection window or multivariate deconvolution applied to capillary electrophoresis of anionic surfactants.

Non-absorbing alkyl ether sulfates (AES) can be separated using anthraquinone-2-carboxylic acid (AQCA) as a probe; however, absorbing alkyl benzene sulfonates (ABS), if present, interfere indirect detection of most AES oligomers. Overcoming of this interference, as well as the simultaneous characterisation and evaluation of AES, fatty acids and ABS, was accomplished by using a diode-array detector and the procedures here discussed. First, it was shown that ABS can be made undetectable by using a 9 nm wide and 227 nm centred charge-absorptivity null-balance detection window (NBDW), where its contribution to the absorbance cancels the dilution effects that its presence induces on the signal of the background chromophore (BGC). Two other procedures, not requiring any prior knowledge on the nature of the absorbing interference, were also addressed. In the first one, the NBDW procedure was emulated by software, by treating the time-wavelength data matrix stored during the experimental run, and in the second one, both the ABS and BGC spectra, and the concentration profiles of ABS and the non-absorbing solutes, were recovered by orthogonal projection approach (OPA) and alternating least squares (ALS). The OPA-ALS processing provided the deconvolved signals and the wavelengths required to implement the experimental and software-emulated NBDW procedures. A composite ABS spectrum and a mixed concentration profile of the non-absorbing solutes, that involves mutual ABS-BGC dilution effects are enclosed in the OPA-ALS straightforward solutions. The pure spectra and concentration profiles were finally retrieved by crossed orthogonalisation. For the NBDW procedures, the limits of detection (S/N = 3) for AES oligomers overlapped by 1500 microg ml(-1) ABS were of ca. 10 microM AES. Using decyl sulfate as internal standard, the relative standard deviation for AES in an ABS containing industrial sample was 4.5%. The procedures here described are useful to remove the interference produced by any absorbing solute when overlapped with indirectly detected solutes in both capillary electrophoresis (CE) and HPLC.

Anions↗
PubMed2005

Deconvolution of overlapped peaks based on the exponentially modified Gaussian model in comprehensive two-dimensional gas chromatography.

Comprehensive two-dimensional gas chromatography (GC x GC) has attracted much attention for the analysis of complex samples. Even with a large peak capacity in GC x GC, peak overlapping is often met. In this paper, a new method was developed to resolve overlapped peaks based on the mass conservation and the exponentially modified Gaussian (EMG) model. Linear relationships between the calculated sigma, tau of primary peaks with the corresponding retention time (tR) were obtained, and the correlation coefficients were over 0.99. Based on such relationships, the elution profile of each compound in overlapped peaks could be simulated, even for the peak never separated on the second-dimension. The proposed method has proven to offer more accurate peak area than the general data processing method.

Chromatography, Gas↗
PubMed2006

Deconvolution of fluorescence spectra: contribution to the structural analysis of complex molecules.

Fluorescence spectroscopy is a sensitive analytical tool in the studies of both simple and complex molecular structures. In complex molecules, however, determining the number and position of components may give a specific insight into the structure, complementary to the other analytical techniques. We applied log-normal model to analyze fluorescence of simple monofluorophore molecule. In order to analyze spectra where both fluorophores and Raman emission bands were present, we developed a method obtained by combination of the symmetric, Gaussian, for Raman and asymmetric, log-normal model, for fluorescence, applicable to the molecules of different complexity. Technically, for each sample we varied excitation wavelength with 5 nm step and recorded the corresponding emission spectra. They were subsequently used for component analysis. Position of each component was plotted against the excitation wavelength. Applying this approach we could identify minimal number of components having stable positions, while their approximate probability density (APD) in a spectral series was correlated with the probable number of fluorophores in the molecule. The method was tested on molecules containing different number of fluorophores: monomers involved in the synthesis of plant polymer lignin-coniferyl alcohol (one fluorophore), ferulic acid (two fluorophores) and on lignin model compound produced from these monomers (many fluorophores). All investigated species belong to benzene-substituted class of compounds, and it is reasonable to assume that they have similar fluorescence band contour. We also report the results of environmental scanning electron microscopy (ESEM) studies showing multilayered dehydrogenative polymer (DHP) structure, in order to show complexity of the polymer. Our results present complementarity of these two approaches in the structural studies of the lignin model compound.

Biopolymers↗
PubMed2006

A deconvolution method for the separation of specific versus nonspecific interactions in noncovalent protein-ligand complexes analyzed by ESI-FT-ICR mass spectrometry.

A method to separate specific and nonspecific noncovalent interactions observed in ESI mass spectra between a protein and its ligands is presented. Assuming noncooperative binding, the specific ligand binding is modeled as a statistical distribution on identical binding sites. For the nonspecific fraction we assume a statistical distribution on a large number of "nonspecific" interacting sites. The model was successfully applied to the noncovalent interaction between the protein creatine kinase (CK) and its ligands adenosine diphosphate (ADP) and adenosine triphosphate (ATP) that both exhibit nonspecific binding in the mass spectrum. The two sequential dissociation constants obtained by applying our method are K(1,diss) = 11.8 +/- 1.5 microM and K(2,diss) = 48 +/- 6 microM for ADP. For ATP, the constants are K(1,diss) = 27 +/- 7 microM and K(2,diss) = 114 +/- 27 microM. All constants are in good correlation with reported literature values. The model should be valuable for systems with a large dissociation constant that require high ligand concentrations and thus have increased potential of forming nonspecific adducts.

Adenosine Diphosphate↗