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PubMed2003

Database deconvolution.

A new deconvolution technique is described. It regards the Rutland-Patlak plot as the integral of the retention function, and performs deconvolution by creating and then differentiating the Rutland-Patlak plot. The reasoning behind this approach is that in producing the Rutland-Patlak plot, both the content function and the integral of the input function are divided by the input function (i.e. the blood curve), and that this has the effect of producing data equivalent to that which would be produced if the input function did not vary (i.e. if there were a constant blood level of tracer). The concept was tested against data created by modelling techniques. It was able to reproduce retention functions with a variety of different shapes that were used to produce the artificial renogram data. The new deconvolution method is sufficiently simple to be used in either a database or a spreadsheet and does not require any special program units to be written. It does not appear to make any assumptions about the data nor the shape of the retention function, and does not appear to be vulnerable to the oscillating errors that sometimes occur in iterative deconvolution.

Algorithms↗
PubMed2003

Intrinsic fluorescence spectroscopy of glutamate dehydrogenase: Integrated behavior and deconvolution analysis.

In this paper, we present a deconvolution method aimed at spectrally resolving the broad fluorescence spectra of proteins, namely, of the enzyme bovine liver glutamate dehydrogenase (GDH). The analytical procedure is based on the deconvolution of the emission spectra into three distinct Gaussian fluorescing bands G(j). The relative changes of the G(j) parameters are directly related to the conformational changes of the enzyme, and provide interesting information about the fluorescence dynamics of the individual emitting contributions. Our deconvolution method results in an excellent fitting of all the spectra obtained with GDH in a number of experimental conditions (various conformational states of the protein) and describes very well the dynamics of a variety of phenomena, such as the dependence of hexamers association on protein concentration, the dynamics of thermal denaturation, and the interaction process between the enzyme and external quenchers. The investigation was carried out by means of different optical experiments, i.e., native enzyme fluorescence, thermal-induced unfolding, and fluorescence quenching studies, utilizing both the analysis of the "average" behavior of the enzyme and the proposed deconvolution approach.

Animals↗
PubMed2006

Blind deconvolution using a variational approach to parameter, image, and blur estimation.

Following the hierarchical Bayesian framework for blind deconvolution problems, in this paper, we propose the use of simultaneous autoregressions as prior distributions for both the image and blur, and gamma distributions for the unknown parameters (hyperparameters) of the priors and the image formation noise. We show how the gamma distributions on the unknown hyperparameters can be used to prevent the proposed blind deconvolution method from converging to undesirable image and blur estimates and also how these distributions can be inferred in realistic situations. We apply variational methods to approximate the posterior probability of the unknown image, blur, and hyperparameters and propose two different approximations of the posterior distribution. One of these approximations coincides with a classical blind deconvolution method. The proposed algorithms are tested experimentally and compared with existing blind deconvolution methods.

Algorithms↗
PubMed2003

Robust deconvolution of high-frequency ultrasound images using higher-order spectral analysis and wavelets.

Deconvolution of high-frequency (30-40 MHz) ultrasonic images of human skin was studied in vivo. Separate one-dimensional (1-D) functions for the axial and lateral profiles were first estimated using higher-order spectral methods. Subsequently, deconvolution was implemented us ing a regularized inverse Wiener filtering of the wavelet and scaling coefficients that were obtained after a wavelet decomposition of the RF signals. Deconvolution was first performed in the axial direction, then in the lateral direction. The methods were applied to data obtained from the skin of 16 volunteers using three different transducers. Significant improvements in both the axial and lateral resolutions were obtained in all the cases. Features such as hair follicles in the dermis and fingerprints on the surface of the finger were more clearly displayed in the processed images compared to the original images. The results indicate that the deconvolution method using higher-order spectral methods and wavelet analysis could significantly improve the quality of high-frequency ultrasonic skin images.

Adult↗
PubMed1992

Estimation of organ transport function: model-free deconvolution by recursive quadratic programming optimization.

A model-free deconvolution method is proposed for evaluating the frequency distribution function of organ transit times. The deconvolution is treated as a nonlinear constrained optimization problem and it is solved by using a modified constrained variable metric approach. The only constraint implemented in the solution is that all the discrete transport function values are not allowed to become negative. The method is tested on model mathematical systems of known analytical transport functions. The tests are performed on systems that included noise in both the input and output functions. The criteria of successful deconvolution are the reconvolution error and, most importantly, the deviation of the computed transport function from the known analytical one. The proposed method is then applied, as a pilot experiment, to biological data obtained from an isolated, perfused rabbit lung preparation contained within a plethysmograph. The results indicate that this type of deconvolution produces stable estimates which faithfully follow the analytical function while negating the need to assume either any functional form for the behavior of the transport function or any educated initial guess of its values.

Algorithms↗
PubMedDate not supplied

Improved quantification of radionuclide uptake using deconvolution and windowed subtraction techniques for scatter compensation in single photon emission computed tomography.

A comparison of two methods of scatter compensation in single photon emission computed tomography (SPECT) imaging is made on the basis of improvements in quantification. The methods, scatter-window subtraction and constrained deconvolution of an average point source response function (PSRF), are described; the theoretical basis of each method is also briefly assessed. Improvements in relative quantification offered by each method are measured by examining ratios of counts in hot cylinders to counts in a slightly radioactive background. The cylinder/background concentration ratio was varied by a factor of five; the sizes of the cylinders remained constant. Keeping the diameter of the cylinders constant allowed for an assessment of the effect of concentration differences, without the conflicting effect of variation in the size of the hot source. Results showed that while both scatter-window subtraction and constrained deconvolution offer quantification improvements in the final image, the method of prereconstruction deconvolution of a planar PSRF from each planar projection is substantially more successful than either scatter-window subtraction or other methods of implementing the deconvolution procedure.

Biophysical Phenomena↗
PubMed2006

Signal to noise ratio analysis of maximum length sequence deconvolution of overlapping evoked potentials.

In this study a general formula for the signal to noise ratio (SNR) of the maximum length sequence (MLS) deconvolution averaging is developed using the frequency domain framework of the generalized continuous loop averaging deconvolution procedure [Ozdamar and Bohórquez, J. Acoust. Soc. Am. 119, 429-438 (2006)]. This formulation takes advantage of the well known equivalency of energies in the time and frequency domains (Parseval's theorem) to show that in MLS deconvolution, SNR increases with the square root of half of the number of stimuli in the sweep. This increase is less than that of conventional averaging which is the square root of the number of sweeps averaged. Unlike arbitrary stimulus sequences that can attenuate or amplify phase unlocked noise depending on the frequency characteristics, the MLS deconvolution attenuates noise in all frequencies consistently. Furthermore, MLS and its zero-padded variations present optimal attenuation of noise at all frequencies yet they present a highly jittered stimulus sequence. In real recordings of evoked potentials, the time advantage gained by noise attenuation could be lost by the signal amplitude attenuation due to neural adaptation at high stimulus rates.

Adult↗
PubMed1991

The influence of noise on quantal EPSP size obtained by deconvolution in spinal motoneurons in the cat.

1. The amplitudes of quantal components that make up single-fiber excitatory postsynaptic potentials (EPSPS) were determined by a deconvolution technique and by simulation studies and were compared with the background noise. 2. A strong correlation was found between the sizes of EPSP quantal components and the standard deviation of the noise from which the data were extracted by deconvolution. A similar correlation was then shown in published data from several other laboratories. 3. EPSPS having amplitudes less than 100 microV were recorded that had little or no variance in their amplitudes. Most of these EPSPS showed a much smaller peak variance than would be expected if they fluctuated among amplitudes in steps of approximately 100 microV--the proposed mean value for the amplitude of the quantal EPSP. 4. Deconvolution of simulated data with the maximum likelihood algorithm resulted in the suppression of components less than 1.5 SD of the background noise. The remaining components were approximately equally spaced. No way was found to detect this error, and rejection of deconvolved data with components less than 1.5 noise SD did not eliminate it. The resulting erroneous data showed a strong correlation between the amplitudes of the components obtained and the noise standard deviation. 5. It is concluded that at least some EPSPS generated by single Ia-afferents on motoneurons are composed of quantal components significantly less than 100 microV and that deconvolution procedures are not capable of detecting such small components.

Action Potentials↗
PubMed1999

Deconvolution analysis for absorption and metabolism of aspirin in microcapsules.

We have previously proposed a novel deconvolution method, which can estimate first-pass metabolism of orally administered drugs. In the present study, we examined whether this deconvolution method is useful for evaluating oral dosage forms. The absorption and first-pass metabolism of orally administered aspirin formulated in several forms were analyzed. Two types of microcapsules consisting of Eudragit L100 alone and Eudragit L100/ethylcellulose (4:6) were prepared as sustained release formulations, for comparison with aspirin in powder form. The deconvolution analysis revealed that absorption of aspirin was sustained by encapsulating it in microcapsules. Interestingly, it also revealed that the percentage metabolized during absorption was different among the three types of formulations. Thus, the deconvolution method has enabled a comprehensive analysis of orally administered drugs. This method is believed to contribute to the evaluation of oral drug formulations.

Absorption↗
PubMed1992

A computer program (DCN) for numerical convolution and deconvolution of pharmacokinetic functions.

A program adapted for use on microcomputers (DCN) has been developed which permits one to perform operations of numerical convolution and deconvolution using polyexponential functions, that are often implemented in pharmacokinetic analysis. The program is written in Microsoft GWBASIC and can be used in personal computers with no modification. The user supplies information relating to the coefficients and exponentials defining the polyexponential equation of the response and weighting functions and the program performs the deconvolution operation by numerical integration using trapezoidal rule and provides numerical and graphic information concerning the input function. The program can be applied to the deconvolution of many linear pharmacokinetic systems and allows one to solve problems related to drug release, absorption, distribution, as well as others. Additionally, the program is able to perform the convolution operation if information about the input and weighting functions and is also able to simulate pharmacokinetic processes. The efficacy of the program was evaluated by comparison with several deconvolution algorithms, in particular that proposed by Veng-Pedersen and Iga.

Algorithms↗
PubMed2003

A method for local deconvolution.

A new method for deconvolution of one-dimensional and multidimensional data is suggested. The proposed algorithm is local in the sense that the deconvolved data at a given point depend only on the value of the experimental data and their derivatives at the same point. In a regularized version of the algorithm the deconvolution is constructed iteratively with the help of an approximate deconvolution operator that requires only the low-order derivatives of the data and low-order integral moments of the point-spread function. This algorithm is expected to be particularly useful in applications in which only partial knowledge of the point-spread function is available. We tested and compared the proposed method with some of the popular deconvolution algorithms using simulated data with various levels of noise.

Journal Article↗
PubMed2006

Deconvolution of axisymmetric flame properties using Tikhonov regularization.

We present a method based on Tikhonov regularization for solving one-dimensional inverse tomography problems that arise in combustion applications. In this technique, Tikhonov regularization transforms the ill-conditioned set of equations generated by onion-peeling deconvolution into a well-conditioned set that is less susceptible to measurement errors that arise in experimental settings. The performance of this method is compared to that of onion-peeling and Abel three-point deconvolution by solving for a known field variable distribution from projected data contaminated with an artificially generated error. The results show that Tikhonov deconvolution provides a more accurate field distribution than onion-peeling and Abel three-point deconvolution and is more stable than the other two methods as the distance between projected data points decreases.

Journal Article↗
PubMed1992

Pulsatile secretion of LH in the ram: a re-evaluation using a discrete deconvolution analysis.

The purpose of the present experiment was to characterize LH secretion pulsatility in rams by analysing the instantaneous secretion rate profile obtained by deconvoluting the plasma concentration profile. Plasma LH concentration profiles were obtained by collecting blood samples every 6 min for 24 h during two different sessions separated by an interval of 15 days. Individual kinetic parameters of ovine LH (oLH) were determined following i.v. injection of oLH. By deconvoluting the plasma concentration profile, it was shown that a pulse has an effective duration of only 20.41 +/- 7.69 (S.D.) min whereas the mean duration estimated from measurement of plasma concentrations was 61.00 +/- 15.16 min. The number of pulses was similar before and after deconvolution (7.80 +/- 1.99 vs 9.70 +/- 3.44 pulses/24 h respectively). Using deconvolution the calculated production rate was 2.26 +/- 0.94 micrograms/kg per 24 h, about 50% of this production being located in the pulses. Statistical analysis of pulsatility revealed that pulse occurrence was a nonperiodic event and that the amplitude of LH pulses and the associated amount of LH released were correlated with the duration of the preceding quiescence period, but had no statistically significant influence on the duration of the following quiescence period.

Animals↗
PubMed2004

[Evaluation of in vitro/in vivo correlation for three kinds of self-designed sustained-release nitrendipine formulations using deconvolution method].

AIM: To evaluate the in vitro/in vivo correlation for three kinds of self-designed sustained-release nitrendipine formulations using deconvolution method. METHODS: The characteristics of in vivo release were calculated by deconvolution method using the data of plasma concentration of three kinds of self-designed sustained-release nitrendipine formulations in healthy dogs, in which the in vivo results of nitrendipine solution after oral administrated to dogs were used as weight function. It was the compared with characteristics of in vitro release to assess the in vitro/in vivo correlations. RESULTS: The good correlations of in vitro/in vivo were shown in three kinds of self-designed sustained-release nitrendipine formulations using deconvolution method. CONCLUSION: The deconvolution method exhibited advantage in evaluation of in vitro/in vivo correlation for self-designed sustained-release nitrendipine formulations.

Administration, Oral↗
PubMed1983

Accuracy of deconvolution algorithms assessed by simulation studies: concise communication.

Deconvolution has been used to correct first-pass radionuclide angiocardiography for the time course of the delivery of radiopharmaceutical into the cardiopulmonary system. The extreme sensitivity of deconvolution to random errors in the data may account for some of the problems encountered in practice. We implemented several deconvolution algorithms that were suitable for use with the unimodal and multimodal superior vena caval and pulmonary curves found in left-to-right shunt quantification. The sensitivity of the algorithms to random errors was assessed using mathematical test problems degraded with pseudorandom noise. An algorithm that constrained the deconvolved pulmonary curve to be expressable as the non-negative sum of a set of lagged normal curves was found to have the smallest maximum error on the curves tested. Comparison with results from a previously published test problem indicated an error reduction of greater than 50% over previously used algorithms. Use of this algorithm may permit more accurate deconvolution of pulmonary time-activity curves and thereby improve shunt quantification.

Heart↗
PubMed1997

Use of the deconvolution principle in the estimation of absorption and pre-systemic intestinal elimination of drugs.

The deconvolution principle was used to evaluate the extent of absorption and first-pass elimination of selected drugs. In the first example, deconvolution of the portal blood profiles of etretinate (ET, a synthetic retinoid) indicated that there was significant gut-wall conversion of ET to acitretin (ETA, the primary metabolite of ET) during a 60-min intestinal perfusion of ET. In the second example, deconvolution was used to confirm that the extent of carbovir disappearing from the gastrointestinal lumen was matched by the extent of carbovir appearance in the portal blood. Thus, deconvolution has several important applications in the study of absorption and intestinal first-pass metabolism.

Animals↗
PubMed2025

OmicsTweezer: A distribution-independent cell deconvolution model for multi-omics Data.

Cell deconvolution estimates cell type proportions from bulk omics data, enabling insights into tissue microenvironments and disease. However, practical applications are often hindered by batch effects between bulk data and referenced single-cell data, a challenge that is frequently overlooked. To address this discrepancy, we developed OmicsTweezer, a distribution-independent cell deconvolution model. By integrating optimal transport with deep learning, OmicsTweezer aligns simulated and real data in a shared latent space, effectively mitigating data shifts and inter-omics distribution differences. OmicsTweezer is versatile, capable of deconvolving bulk RNA-seq, bulk proteomics, and spatial transcriptomics. Extensive evaluations on simulated and real-world datasets demonstrate its robustness and accuracy. Furthermore, applications in prostate and colon cancer showcase OmicsTweezer's ability to identify biologically meaningful cell types. As a unified deconvolution framework for multi-omics data, OmicsTweezer offers an efficient and powerful tool for studying disease microenvironments.

Humans↗
PubMed2000

Investigation of stretching vibrations of glycosidic linkages in disaccharides and polysaccharides with use of IR spectra deconvolution.

The results are presented for the deconvolution of IR spectra of disaccharides and polysaccharides with alpha and beta configurations of the 1 --> 4 glycosidic linkage (maltose, cellobiose, amylose, and cellulose), as well as of their corresponding monosaccharides (alpha- and beta-D-glucose) in the 1200-920 cm(-1) frequency range. It is established that a characteristic of di- and polysaccharides with 1 --> 4 glycosidic linkage is the appearance of new absorption bands in the 1175-1140 cm(-1) spectral range, as opposed to the IR spectra of monosaccharides. This can be a spectroscopic manifestation of the glycosidic linkage formation. In the 1000-970 cm(-1) frequency range, absorption bands, which are not observed in the monomer spectrum, are separated as a result of the deconvolution of the IR spectra of cellobiose and cellulose. The number of bands in this range remains unchanged for maltose and amylose, as compared to the monomer spectra. It is shown that the application of the method of deconvolution leads to a considerable enhancement in the resolution of the absorption bands in the IR spectra of mono-, di-, and polysaccharides.

Disaccharides↗