Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “deconvolution”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,135 records · Page 63Linked to original sources
PubMed1988

Evaluation of valvular regurgitation by factor analysis of first-pass angiography.

We have evaluated left ventricular regurgitation by means of factor analysis of 99mTc first-pass radionuclide angiography (FPRNA) and time-activity curve deconvolution. The FPRNA regurgitant fraction (RF) was computed in 26 individuals: 13 patients (eight mitral, three aortic, and two mitral-aortic) and 13 controls. The reference method was contrast ventriculography (CV) performed within 1 hr after FPRNA. In 19 patients, CV was preceded by the determination of cardiac output, using indocyanine green dye (n = 16) or thermodilution technique (n = 3), to determine a catheterization regurgitant fraction (CATH-RF). Lung and left ventricular (LV) time-activity curves were gathered by factor analysis and the FPRNA regurgitant fraction assessed by a lagged normal deconvolution of these curves. In valvular regurgitation, the LV deconvolved curve demonstrates the appearance of a long transit time component that is amenable to quantification. The presence of regurgitation was determined by contrast ventriculography. With a 10% RF as an acceptable upper limit of normal for nonregurgitant patients, FPRNA yielded one false-negative and no false-positive studies (n = 26), while CATH-RF yielded two false-negative and four false-positive determinations (n = 19). The following are results of quantitative determination of RF (mean +/- s.d.): FPRNA 0.39 +/- 0.19 (n = 13 Valvular), 0.01 +/- 0.03 (n = 13 Controls); CATH 0.34 +/- 0.24 (n = 11 Valvular), 0.13 +/- 0.12 (n = eight controls). FPRNA was able to differentiate (p less than 0.001) between control patients (CV grading 0) and mild/moderate regurgitation (CV grading 1+ or 2+) and severe regurgitation (3+ or 4+) (p less than 0.025).

Adult↗
PubMed1989

Amplitude fluctuations in small EPSPs recorded from CA1 pyramidal cells in the guinea pig hippocampal slice.

EPSPs have been evoked in CA1 pyramidal cells by (1) activation of single CA3 neurons (unitary EPSPs), and (2) low-intensity stimuli to the CA1 stratum radiatum. Five unitary EPSPs were obtained; their mean peak amplitudes ranged from 85 to 275 microV and 3 of the 5 showed fluctuations in amplitude that were too great to be attributed to baseline noise. After subtraction of the variance due to the noise, these EPSPs had coefficients of variation much higher than those reported for variability in the quantal EPSP in other preparations. These results suggest that intermittent transmitter release is a major cause of EPSP amplitude fluctuation at this synapse. A noise deconvolution technique based on a nonrestrictive model of transmitter release was applied to the EPSPs obtained in this study. For 2 of the EPSPs evoked by stratum radiatum stimulation, the amplitudes fluctuated between discrete values that were sufficiently separated with respect to the noise to be resolved by the deconvolution procedure. Quantal increments of 224 and 193 microV were determined for the 2 EPSPs.

Animals↗
PubMed1985

Pharmacokinetics and bioavailability of suprofen injection solution after intravenous application versus capsules on six healthy male volunteers.

In a three-way cross-over study six healthy male volunteers received intravenously 50 mg and 100 mg suprofen as a bolus injection and orally 200 mg as one capsule. The plasma level curves could be fitted to a two-compartimental model by means of the computer program NONLIN. The pharmacokinetic parameter estimates did not show dose dependency. The absolute bioavailability of suprofen taken as one capsule was 92.2% based on AUC-values and did not indicate a first-pass effect. The plasma input curve was determined by point-area deconvolution. Assuming first order input a half-life of 23 min could be derived based on point-area deconvolution. Different dissolution models based on USP XX are discussed in relation to the kinetic data generated.

Adult↗
PubMed1985

Application of Chelex standard beads in integrated morphometrical and X-ray microanalysis.

Chelex ion exchange beads loaded with a known amount (18.3% weight percentage (w/w)) of platinum, have been co-embedded with a mouse peritoneal cell population. To establish the influence of the various deconvolution methods applied, upon the platinum concentration in cytoplasmic granules and erythrocytes these cross-sectioned beads are used as a standard. It is concluded that irrespective of the deconvolution method chosen 1) the Pt concentration inside the particles is identical when the particles and the co-embedded Chelex Pt standard, are analysed strictly under the same instrumental conditions 2) the Pt concentration outside the particle is zero, or virtually zero when that element is absent there (erythrocyte surrounded by Epon) 3) the Pt concentration outside the particle in the surrounding cytoplasm was identical (when the element Pt was present there). The information about the elemental concentration obtained by point analysis in the STEM-mode in homogeneous objects was compared with the mean value obtained by the reduced raster method. The ratio between these values were constant. As an example of a heteromorphic, heterogeneous cell organelle population, the application of the method of integrated morphometrical and chemical (X-ray) analysis is demonstrated on lysosomes within a single human liver parenchymal cell, containing iron and cerium. It was shown that the cerium concentration (from the cytochemical reaction to detect acid phosphatase activity in lysosomes) was rather homogeneously distributed over the small population and in the individual lysosomes. The iron distribution was very inhomogeneous, both in its distribution over the lysosomal area, and among the lysosomes in the population.

Animals↗
PubMed1985

Interrelations of radiocalcium absorption tests and their clinical relevance.

Intestinal absorption of radiocalcium from an oral test dose was measured in 84 patients with various disorders of bone and calcium metabolism. In each subject, five different methods were used to assess intestinal absorption and the estimates obtained were compared inter- and intra-individually. The whole-body counting technique was chosen as reference method and as a basis for comparison of the other four estimates. Plasma levels of radiocalcium after oral administration seem to provide a simple and rapid test which may serve its purpose in various clinical situations. Fractional intestinal calcium absorption can be assessed equally well by the whole-body counting technique, the double-isotope method or the double-isotope deconvolution technique, since these methods yield comparable results. The deconvolution technique additionally provides a quantitative description of the absorptive process of calcium with respect to time.

Adult↗
PubMed1979

[Evaluation of intestinal absorption of calcium by means of double-isotope methods and oral administration of the tracer].

The percent intestinal absorption of calcium was measured in normal volunteers and in patients with idiopathic hypercalciuria employing the deconvolution method, the ratio of the two administered isotopes at equilibrium and the percent of dose present in plasma 2 hr after oral administration of the tracer. Comparison of results obtained showed that the technique based on the ratio between the two radioisotopes overestimates intestinal absorption by about 9% with respect to values calculated with the deconvolution method, but gives results comparable to those determined by oral administration of the isotope. The percent dose of the tracer 2 h after i.v. administration is closely correlated with the size of the miscible calcium pool. A less significant correlation exists between the size of the pool and percent of the dose 2 h after oral administration.

Administration, Oral↗
PubMed1984

Diuresis renography and parenchymal transit times in the assessment of renal pelvic dilatation.

A comparison has been made between the results of diuresis renography and deconvolution analysis of the renogram in 36 patients (46 kidneys) with urographically demonstrated renal pelvic dilatation. The mean transit times obtained by deconvolution analysis of the parenchymal renograms of eight normal volunteers had a mean value of 2.8 + 0.6 (S.D.) min, and the upper limit of normal was thus established as 4 min. Twenty-two of 29 kidneys (76%) with nonobstructive diuresis renograms had parenchymal mean transit times of 4 min or below. Fourteen out of 17 kidneys (82%) with obstructive diuresis renograms had parenchymal mean transit times above 4 min. Both investigations may contribute to the noninvasive assessment of dilated renal pelves; the parenchymal retention function (quantified by mean transit time) assesses the effects of dilatation on tubular transit and renal function, whereas the diuresis renogram is a more specific test for evaluating impedance to flow.

Diuresis↗
PubMed1984

Rectal, oral and I.A. administration of etomidate to rats: significant avoidance of hepatic first-pass elimination following rectal administration.

The systemic availabilities of the hepatic high-clearance drug etomidate following oral and rectal administration to rats were determined. The mean curve following intra-arterial administration to another group of rats was taken as a reference. The results showed that the mean rectal systemic availabilities calculated according to the AUC method and the deconvolution method were considerably higher (70.1% and 67.6% respectively) as compared to the mean values following oral administration (4.5% and 9.2% respectively). The deconvolution method gave detailed information about the profiles of the rate and cumulative amount of drug absorbed versus time. It showed that the mean maximal rate of absorption was higher and the time at which this occurred was shorter after rectal (5343 micrograms/hr and 0.13 hr) than after oral (600 micrograms/hr and 0.23 hr) administration. Mean blood elimination half-lives following rectal administration (112.6 min) were longer than that after i.a. administration (61.7 min). The mean half-life of 22.8 min after oral administration should be considered as a distribution half-life. The mean clearance following i.a. administration was 35.2 ml/min (142.7 ml/min/kg), which is higher than hepatic bloodflow and indicates extra-hepatic metabolism. It is concluded that there is a substantial avoidance of hepatic first-pass elimination of etomidate following rectal administration to rats.

Administration, Oral↗
PubMed1983

Measurements of regional tissue and blood-pool radiotracer concentrations from serial tomographic images of the heart.

Quantification of myocardial tissue kinetics from serial tomographic images is limited because of bidirectional cross-contamination of recorded counts between myocardium and blood for metabolic tracers with relative slow blood clearance. We have developed and validated a new deconvolution technique that permits calculation of spillover fractions derived from geometric measurements of the imaged cross section (wall thickness, chamber diameter) and the intrinsic resolution of the tomograph. Serial gated positron-emission computerized imaging (PCT) and a-v blood sampling across the heart were performed in five dogs for 45 min after i.v. C-11 palmitate (CPA) and in five dogs for 3 hr after i.v. F-18 deoxyglucose (FDG). Tracer concentrations in myocardial tissue and arterial blood were also measured in vitro. Uncorrected PCT tissue and blood concentrations correlated poorly with in vitro measurements. After correction for count crossover, the correlation for FDG in tissue was r = 0.99, for FDG in blood r = 0.97, and for CPA in blood r = 0.99. Deconvolution techniques applied to serial PCT images provide accurate noninvasive measurement of myocardial tracer concentrations and direct determination of the arterial input function required for measurements of myocardial metabolism.

Animals↗
PubMed1997

Conformation and stability of streptokinases from nephritogenic and nonnephritogenic strains of streptococci.

Conformation and stability of three Sks from Streptococcus equisimilis strain H46A, Streptococcus pyogenes strain A374, and Streptococcus pyogenes strain AT27 were compared by limited proteolysis, CD, and fluorescence measurements and by DSC. The general similarity of the peptide CD spectra in the spectral region 185 to 260 nm indicates the same type of folding for the three proteins. Fluorescence and aromatic CD spectra are consistent with a predominant surface localization of the aromatic amino acids and a low rigidity of their surroundings. A major difference among the three Sks is shown by deconvolution of their excessive heat capacity functions. Deconvolution reveals two energetic folding units in Sk H46A but three energetic folding units in Sk A374 and Sk AT27. Digestion of the Sks with trypsin indicates a reduced sensitivity of the C-terminal region of Sk A374 and Sk AT27 in comparison to Sk H46A. This suggests that amino acids of the C-terminal region participate in the formation of the third folding unit of Sk A374 and Sk AT27.

Amino Acid Sequence↗
PubMed1997

Evaluation of renographic and metabolic parameters in human kidney transplantation.

BACKGROUND: The aim of this work is to demonstrate that the value of the mean transit time (MTT) obtained from the 99mTc-MAG3 renogram deconvolution is related to the levels of adenine nucleotides determined in cortical biopsies from transplanted kidneys. METHODS: The functional state was estimated by means of the MTT and the initial height (H0) of the renal retention function obtained from the 99mTc-MAG3 renogram deconvolution and by the measure of adenine nucleotides obtained from biopsies. We studied 30 kidney graft recipients, 25 normal functioning grafts (NFG) and 5 with acute tubular necrosis (ATN). RESULTS: The MTT is significantly longer for ATN (p < 0.001). The initial uptake values (H0) are significantly lower for ATN (p < 0.001). The sum of adenine nucleotides (SAN) is significantly greater for NFG than for ATN (p < 0.001). The values of the MTT seem to reflect the energy state of the cells in transplanted kidney. CONCLUSION: The analysis of MTT may be indicative of the functional metabolic recovery and thus it may be predictive of the renal graft function at least in the same extent than the biochemical analysis of a cortical renal biopsy immediately after blood reperfusion of the tissue.

Adenine Nucleotides↗
PubMed1997

Peptide and nonpeptide lead discovery using robotically synthesized soluble libraries.

The method of combinatorial synthesis of peptide and nonpeptide libraries on solid phase is analyzed and the automation of the mix and divide key step described. A set of amino acids leading to a high molecular diversity is proposed as well as a number of scaffolds for the preparation of variable polyamide libraries. Adequacy of the resin bead quantities to library size and to the ratio of the synthesized peptide types is discussed. Examples of the use of capillary electrophoresis and of spectroscopic methods (MS, MS/MS, and NMR) for the analysis of the library content are given. The iterative deconvolution SURF (synthetic unrandomization of randomized fragments) is compared with positional scanning and the success of coupling of mixtures evaluated. It is concluded that extension of the original mix and divide method and the SURF deconvolution (as proposed by Houghten et al. Nature (London), 354: 84-86 1991) to nonpeptide libraries affords new leads that can be optimized towards useful therapeutics.

Amino Acids↗
PubMed1997

Neural network-based PET image reconstruction.

In PET image analysis, conventional deconvolution alone will not give sufficient information for a precise study of a localized brain function. In the deconvolution process, which is a type of inverse problem, it is important to confine the solution space by incorporating a priori knowledge such as the tissue distribution given by MR images as well as smoothness in the blood flow distribution profile. An MR-embedded neural-network model is described to reduce the partial volume effect in the restoration of blood flow profiles from PET images.

Brain↗
PubMed2025

Immune Cell Type-Specific DNA Methylation Regions Associate With 24-Hour Blood Pressure Regulation in Black People.

BACKGROUND: DNA methylation and immune cells have been linked to blood pressure (BP) regulation and the development of hypertension. However, the immune cell profiles and the cell type-specific DNA methylation associated with BPs remain unclear. METHODS: This study evaluates the 19 cell type deconvolution algorithms using reduced representation bisulfite sequencing data, comparing them to in silico mixtures derived from whole-genome bisulfite sequencing. The top-performing algorithm, Epigenetic Dissection of Intra-Sample Heterogeneity (EpiDISH)-Robust Partial Correlations, was applied to 281 Black inpatients with 24-hour BP monitoring. The immune cell profiles and cell type-specific DNA methylation regions associated with these BP phenotypes were further investigated using regression analysis. RESULTS: In patients with hypertension, B-cell and CD4 effector memory T-cell abundances were significantly elevated. Monocyte and CD8 effector memory T-cell fractions positively correlated with nighttime BP, and CD3 T cells were inversely associated with office BP. These associations remained robust after covariate adjustments and were partially validated in the Medical Information Mart for Intensive Care-IV cohort. For the first time, we identified several cell type-specific DNA methylation regions as being associated with BP phenotypes and patterns across 13 immune cells, with approximately one third predominantly found in effector CD8 T cells. CONCLUSIONS: These findings provide novel insights into the epigenetically regulated immune mechanisms underlying BP regulation and identify potential targets for hypertension management.

Humans↗
PubMed1997

Growth and growth hormone secretion after treatment for childhood non-Hodgkin's lymphoma.

The aim of this study was to evaluate the growth and growth hormone (GH) secretion, as assessed by the rate and pattern of secretion, in patients in remission from non-Hodgkin's lymphoma (NHL) who had been treated with corticosteroids and intense chemotherapy. None of the patients had received cranial irradiation. Twelve children were investigated yearly by taking 24-hour GH profiles starting 1 year from the time of diagnosis. The mean age at onset of the disease was 7.5 years. Another 12 young adults were studied in a cross-sectional manner 4.1-21.3 years (mean, 9.0 years) after diagnosis of NHL. The mean age at onset of the disease was 10.7 years. The median height velocity was significantly decreased during the 1st year following diagnosis (standard deviation scores [SDS] -0.15, P < .001), especially during the first 3 months (SDS -0.75, P < .001) when the most intense treatment was given. During the 2nd year height velocity was still somewhat reduced (SDS -0.13, P < .001). However, there was no reduction in final attained height. Spontaneous GH secretion, in terms of both secretory rate and pulsatile pattern, was evaluated by measuring integrated GH concentrations in 20-minute blood samples collected over a 24-hour period. The plasma GH concentrations were transformed into GH secretion rates by means of a deconvolution technique. Fourier time series analysis was applied to determine possible disturbances of rhythmicity of the GH secretion. The GH secretion rate and the pulsatile pattern of secretion in the NHL patients were similar to those of the reference population of pubertal matched healthy controls. There was no influence of the age at diagnosis or of the time from diagnosis of NHL on the GH secretion rate. Growth impairment in children with a malignant disease treated only with steroids and chemotherapy is therefore probably not caused by disturbed GH secretion, but rather by direct interference with bone growth of the cytotoxic drugs used. There was no significant influence on weight gain during the treatment period so an indirect effect of chemotherapy on bone growth through interference with adequate nutrition seems unlikely. However, GH secretion was not evaluated during the period of growth retardation, and therefore a transient deficiency was not excluded.

Adolescent↗
PubMed1997

Characterization of oligonucleotide metabolism in vivo via liquid chromatography/electrospray tandem mass spectrometry with a quadrupole ion trap mass spectrometer.

The pattern of nuclease degradation observed for an antisense phosphorothioate oligonucleotide in pig kidney was determined using liquid chromatography/electrospray mass spectrometry (LC/ESI-MS) and LC/ESI-MS/MS with a quadrupole ion trap mass spectrometer. Metabolites were separated by length using reversed-phase high-performance liquid chromatography with aqueous hexafluoropropan-2-ol-triethylamine and a methanol gradient. The individual masses of metabolites in each LC peak were determined via deconvolution and converted into potential nucleotide compositions. The nucleotide composition was used to locate metabolites within the known oligomer sequence. The identity of metabolites was confirmed using on-line LC/MS/MS to generate fragment ions suitable for sequence verification. A limited number of shorter oligonucleotide fragments were observed, suggesting that metabolism in vivo may be sequence dependent.

Animals↗
PubMed1999

High-sensitivity analysis and sequencing of peptides and proteins by quadrupole ion trap mass spectrometry.

This paper describes experience with the commercially available LCQ quadrupole ion trap mass spectrometer applied to the off-line analysis of peptides and proteins. The standard front end of the electrospray probe was replaced with a micromanipulator which, with the aid of a magnifying device, allowed the use of a variety of miniaturized spraying interfaces. The low sample consumption and extended analysis times of these devices were ideally suitable to obtain improved results in terms of sensitivity and mass accuracy. This needed a careful optimization of the number of ions stored inside the trap (ion target parameter) and required spectrum averaging of many scans. A method is presented for the mathematical fitting of ZoomScan spectra to theoretical isotopic distributions, which allowed the mass determination of large peptides with more accuracy than that achieved by conventional deconvolution algorithms. A very simple on-line desalting configuration is also described which needed no external micro-high-performance liquid chromatographic pumps, and can be easily mounted using the built-in syringe delivery system of the LCQ. This set-up allowed extended analysis times of 'in-gel' protein digests in subpicomole amounts. Finally, the multiple fragmentation capabilities of the ion trap were found to be extremely useful for the analysis of peptide modifications such as phosphorylation and for sequencing individual peptides from highly complex MHC-bound peptide pools.

Animals↗
PubMed1998

Image processing based on the combination of high-resolution electron microscopy and electron diffraction.

A method of crystal structure determination by electron crystallographic image processing based on the combination of high-resolution electron microscopy (HREM) and electron diffraction is introduced. It consists of two stages: image deconvolution and resolution enhancement. In the first stage an image taken at an arbitrary defocus condition is transformed into the structure image with the resolution depending on the resolution of the electron microscope. In the second stage the image resolution is enhanced to the diffraction resolution limit by combining the electron diffraction data and using the phase extension technique so that in the final image most unoverlapped atoms can be resolved individually. The experimental diffraction intensities are corrected for approximating to square structure factors. The principle of the image processing and the procedure of diffraction intensity correction are briefly described and the results of applications are illustrated. Since the method is based on the weak phase object approximation (WPOA), the validity of WPOA is discussed by introducing an approximate image contrast theory named pseudo weak phase object approximation (PWPOA) to demonstrate the image contrast change with the crystal thickness for very thin crystals.

Copper↗