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At least 19 recordsLinked to original sources
PubMed1992

Estimating population size for capture-recapture data when capture probabilities vary by time and individual animal.

There have been no estimators of population size associated with the capture-recapture model when the capture probabilities vary by time and individual animal. This work proposes a nonparametric estimation technique that is appropriate for such a model using the idea of sample coverage, which is defined as the proportion of the total individual capture probabilities of the captured animals. A simulation study was carried out to show the performance of the proposed estimation procedure. Numerical results indicate that it generally works satisfactorily when the coefficient of variation of the individual capture probabilities is relatively large. An example is also given for illustration.

Animals↗
PubMed1992

Light microscopical demonstration of non-specific alkaline phosphatase activity with an incubation medium containing cerium and two calcium as the capturing agents. The cerium/calcium-hydrogen peroxide-P-phenylenediamine/pyrocatechol (Ce/Ca-H2O2-PPD/PC) double capture technique.

A new method for the light microscopical demonstration of alPase activity in cryotome sections by using simultaneously cerium and calcium as capturing agents (double capture technique) is described. This method has an increased sensitivity compared with the single cerium-based and the Gomori based-cerium (single calcium and cerium converted) with techniques described previously. Presuming that the enzymatic activity during incubation of sections in the presence of a defined capturing agent is constant, the increased sensitivity after employment of the double capture method could be attributed to a decrease of enzyme inhibition by cerium through the presence of calcium. Based on model experiments it is assumed that calcium phosphate and cerium phosphate are the primary reaction products, the former converting into cerium phosphate already during incubation. The remaining calcium phosphate is converted completely by treatment with cerium citrate solution (conversion reaction). After oxidation with H2O2 the cerium perhydroxyphosphate was visualized in a paraphenylenediamine/pyrocatechol (Hanker-Yates reagent) solution without H2O2 to give a black reaction product. This visualization procedure is superior to the DAB or DAB-Ni mode as published earlier. Some results concerning the mode of inhibition of the pseudoperoxidase activity of the hemoglobin are presented.

Alkaline Phosphatase↗
PubMed1991

Residues of pentachlorophenol and other chlorinated contaminants in human tissues: analysis by electron capture gas chromatography and electron capture negative ion mass spectrometry.

Samples of human tissues including testes, kidneys, prostate glands, livers, and adipose tissues removed at autopsy were analyzed for pentachlorophenol (PCP) and nonachloro-2-phenoxyphenol (NCPP); the fat samples were also analyzed for other chlorinated contaminants. Electron capture gas chromatography was used to quantitate the residues after isolation and cleanup. Identity of the residues was confirmed by electron capture negative ion mass spectrometry. All tissues analyzed for PCP tested positive with a range from 0.007 ppm (microgram/g) in subcutaneous fat to 4.14 ppm in testis. Residues of NCPP were much lower, ranging from levels below the detection limit to 0.59 ppm in testis. The highest average residues, based on the lipid content of the tissue, of PCP (1.09 ppm) and of NCPP (0.19 ppm) were found in testis followed by kidney (0.95 ppm PCP), prostate (0.84 ppm PCP), and liver (0.59 ppm PCP). Residues of these chemicals in the adipose tissues were on the average about 40 times lower than the residues in the non-fatty tissues. Other chlorinated contaminants found in the subcutaneous fat included hexa-, hepta-, and octa-chlorodibenzo-p-dioxins at sub-ppb levels and DDE averaging 2.47 ppm.

Adipose Tissue↗
PubMed1978

A new dynamic model system for the study of capture reactions for diffusable compounds in cytochemistry. I. Description of the model with special attention to phosphate capture in acid phosphatase cytochemistry.

A model system is described for the investigation of the dynamics of precipitation processes in a matrix. In this system a solution containing the molecular species to be precipitated and the precipitating medium are pumped along opposite sides of a polyacrylamide film. The solutions flowing continuously along the film, interact and can form a precipitate inside the film. The applicability of the model was tested on the capture reaction for phosphate ions by the Gomori type medium for acid phosphatase. Precipitation of lead phosphate in the film occurred only at a phosphate concentration above a certain value. The dependence of this minimal phosphate concentration on various parameters was studied and the results were compared with values found in earlier model studies and calculations concerning phosphate concentrations that can be built up in lysosomes during the Gomori reaction. The system seems promising for obtaining fundamental data about other cytochemical enzyme trapping reactions as well as for the matrix facotrs involved in bone calcification and shell formation.

Acid Phosphatase↗
PubMed1990

Alternate methods for the determination of atrial capture threshold utilizing the telemetered intracardiac electrogram.

Periodic determination of pacemaker capture threshold is important to ensure appropriate pacemaker function. During dual chamber pacing, it is sometimes difficult to identify evidence of atrial depolarization on surface electrocardiography (ECG), and this can interfere with the ability to ascertain atrial capture. We describe new methods for determining atrial capture threshold using a standard telemetered endocardial atrial electrogram (AEGM). For the first method, the atrial output is decremented until loss of atrial capture is demonstrated by the appearance of native P wave activity on the AEGM. The atrial capture threshold can then be accurately determined as the point at which a stepwise increase in atrial output results in extinction of the native P wave activity. The second method uses the direct visualization of the AEGM recorded between the ring electrode and pacemaker generator during unipolar (lead tip electrode) pacing. This requires the presence of a bipolar lead. Using this method of recording, it is possible to identify a signal after the atrial stimulus artifact during atrial capture, which disappears with loss of capture. This signal is consistent with a paced "evoked atrial potential" and allows verification of atrial capture. After validating the methods in two sets of test patients with clearly identifiable atrial depolarization on surface ECG, one method was successfully applied to a patient in whom atrial depolarization could not be reliably ascertained on surface ECG. These methods promise to be useful in selected patients in whom confirmation of atrial capture would otherwise be difficult.

Animals↗
PubMed1992

A new pacemaker algorithm for continuous capture verification and automatic threshold determination: elimination of pacemaker afterpotential utilizing a triphasic charge balancing system.

A new pacemaker algorithm designed to automatically verify pacemaker capture and determine pacing threshold by detection of a stimulus evoked potential was studied in 20 patients undergoing permanent pacemaker implantation. To eliminate pacing stimulus afterpotential and detect an evoked response, a hardware feedback circuit and a software template matching algorithm were used to produce a triphasic charge-balanced pacing pulse. After charge balancing the pacing lead, a residual artifact is measured. A capture window is defined as the area integral of the first 24 msec of the evoked depolarization, and a capture threshold as one third the amplitude of the capture window. The maximum allowable residual artifact is one eighth the amplitude of the capture window. Once the stimulus afterpotential is eliminated and the evoked response detected, capture threshold is automatically and continuously determined and the algorithm adds a 0.8-V safety margin to the pacemaker output. This algorithm was run automatically and after simulated loss of capture, produced by manually decreasing pacer output below threshold, in the bipolar (13 patients) and unipolar (20 patients) pacing modes. In each patient loss of capture was immediately detected. The data were consistent (P = NS) between algorithm runs. During unipolar pacing the area integral of the first 24 msec of the evoked response was 412 +/- 137 versus 413 +/- 144 and the residual artifact 5.8 +/- 4.8 versus 8.1 +/- 7.5. The resulting ratio (signal/noise) of the two parameters was 150 +/- 141 versus 145 +/- 181. Automatically determined threshold was 0.69 +/- 0.43 V versus 0.69 +/- 0.42.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1978

The influence of atrial systole on ventricular capture by failing artificial pacemakers. II. Experimental observations.

The mechanism by which atrial systeole influences the efficacy of ventricular capture by a failing pacemaker was investigated in 12 dogs with atrioventricular heart block. Atrial systole caused facilitation of ventricular capture in eight dogs, and inhibition of capture in 10 dogs. Interpolating atrial extrasystoles caused an enhancement or depression of the hemodynamic performance of the atrial systole that affected the efficacy of the pacemaker stimulus. These interpolation experiments showed that atrial systole influenced the efficacy of capture by a mechanical mechanism and not by an electrotonic mechanism. Atrial systole probably caused motion of the endocardial pacing catheter and/or ventricular myocardium. This motion increased or decreased the contact between the pacing electrode and the endocardium with subsequent changes in the efficacy of capture. In three dogs with pacing through epicardial electrodes, atrial systole had no effect on the efficacy of capture.

Animals↗
PubMedDate not supplied

Performance characteristics of a commercial antibody-capture enzyme immunoassay for detection of Toxoplasma-specific IgM antibodies.

Antibody-capture enzyme immunoassay (EIA) for the detection of Toxoplasma-specific IgM has been shown to provide significantly higher specificity than the indirect IgM EIA. A new commercially available antibody-capture EIA (PLATELIA Toxo IgM EIA) converted 99 out of 100 false-positive Toxo-plasma IgM determinations to true negative. Experiments using Toxoplasma IgM calibrators demonstrated the antibody-capture EIA is approximately eightfold more sensitive than a new automated microparticle EIA for Toxoplasma IgM antibodies (IMX Toxo IgM EIA), and approximately equal in sensitivity to the indirect immunofluorescence assay. Precision studies of the antibody capture EIA using low, medium, and high calibrators gave coefficients of variation ranging from 3.0%-4.5% for within-run and 5.2%-11.4% for run-to-run variation experiments. Interference from high levels of bilirubin, albumin, hemoglobin, and lipid was not detected. Sera from patients with inflammatory or infectious disorders were tested for interference in the antibody-capture EIA. False-positive Toxoplasma IgM results were not observed, but low-level negative interference was detectable when patient sera was mixed with Toxoplasma-positive sera. Preparations of purified human IgM also produced negative interference in the antibody-capture EIA for Toxoplasma IgM.

Animals↗
PubMed1992

Present status of boron neutron capture therapy.

The neutron capture reaction 10B(1n,4He)7Li produces two energetic particles, 4He2+ and 7Li3+ that are strongly cell toxic. Due to the short range of these nuclear fragments (5-9 microns) mainly those cells that have bound or internalized a 10B-containing substance are growth-inactivated. The most critical and difficult step in an efficient boron neutron capture therapy (BNCT) is the tumour targeting. It is today possible to synthesize a large number of boron compounds and conjugate them to tumour-seeking macromolecules, such as monoclonal antibodies or different polypeptides. The boron-containing substances presently considered for therapy are sulfhydryl boron hydride (BSH) and boron-phenylalanine, (BPA) for the treatment of gliomas and malignant melanomas respectively. Other boronated compounds considered are ligands for receptor-amplified tumour cells, antibodies for tumour cells with specific antigens and thioureas for treatment of melanotic melanomas. The required boron concentration is given by the relative dose due to neutron capture in 10B and that of the competing capture reactions in nitrogen and hydrogen. Capture in nitrogen produces protons with a range of about 10-11 microns and this gives a radiation dose to all cells in the neutron activated area. Calculations show that the local concentration of 10B near the critical radiation target, DNA, must be higher than 10 ppm (10 micrograms/g). Increased emphasis will be put on the development of combinations of treatments that fulfil the requirements for attacking the microscopic spread of the tumour.

Boron↗
PubMedDate not supplied

The immunochemistry of sandwich ELISAs--V. The capture antibody performance of polyclonal antibody-enriched fractions prepared by various methods.

Studies compare the performance of antibody-enriched serum fractions prepared by various methods, when adsorbed on polystyrene microtiter wells as capture antibodies (CAbs) and tested against multivalent antigens. The criteria of performance in the RIA used included antigen capture capacity (AgCC) and the nmol of functional capture sites per microtiter well (CAbt). Affinity purified polyclonal (pAb) and monoclonal antibodies (mAb) were employed as reference CAbs. AgCC was highest for enriched fractions prepared using caprylic acid and a high-pressure SpG affinity column. The performance of capture antibodies is expressed by an equation which was empirically derived and experimentally tested; CAbt x AgCC/ng adsorbed IgG. In terms of this parameter, CAb-enriched fractions prepared with caprylic acid performed best. The data reported also provide insight into solid-phase ligand immunochemistry. Adsorbed polyclonal CAb performed with remarkable homogeneity in percent bound and in Scatchard plots. Values obtained for CAbt from Steward-Petty plots were directly correlated with the length of the LBR of log-log percent bound plots but indicated that less than 10% of the potential capture sites of polyclonal CAbs remained functional after adsorption; mAb showed a more serious loss of activity. The loss of CAbt was a general phenomenon for all preparations tested although relative to their antibody content, certain antibody-enriched fractions retained a higher proportion of CAbt than their affinity-purified counterparts. Comparative studies in which the activity of adsorbed mAb and pAb was compared to the same antibodies immobilized by a non-adsorptive procedure, indicated that adsorbed CAbs also express lower affinity. The studies we report offer a single parameter criterium for comparatively evaluating CAb performance while simultaneously revealing the need to develop immobilization procedures that can preserve CAbt and antibody affinity so that immunoassays with wide dynamic ranges and high AgCC can be developed without waste of antibody.

Adsorption↗
PubMed1992

Transport calculations of depth-dose distributions for gadolinium neutron capture therapy.

Depth-dose distributions were calculated for thermal and epithermal neutron fluence and capture gamma ray dose rates using a two-dimensional neutron-coupled gamma-ray transport code (DOT 3.5) for gadolinium neutron capture therapy. The results show that (i) a capture gamma-ray dose rate of 10 Gy h-1 was obtained with a thermal neutron fluence rate of 1.5 x 10(9) cm-2 s-1 in a simulated tumour containing 5000 PPM gadolinium placed near the surface of a water phantom, (ii) deep-seated tumours may be treated with epithermal neutrons, and (iii) gadolinium neutron capture therapy appears to achieve comparable dose distributions to those of boron neutron capture therapy.

Gadolinium↗
PubMed2026

RAmpSim: a thermodynamic simulator for hybridization capture in metagenomic sequencing.

MOTIVATION: Simulators that generate synthetic datasets help address the lack of ground truth for developing and benchmarking computational tools. Many read simulators assume uniform sampling across reference genomes; however, for newer capture-based sequencing technologies (e.g. TELSeq), this assumption is intentionally broken to oversample regions of interest. Along with systematic biases arising from probe multiplicity, sequence composition, and species abundances inherent to capture-based sequencing, this mismatch between modeling assumptions and the characteristics of real data necessitates the design of a new capture-based sequencing-specific simulator. RESULTS: We present RAmpSim, a fast simulator that models bait-target hybridization and fragment capture using a thermodynamic nearest-neighbor energy model and Boltzmann-weighted sampling of binding sites. Fragments are generated through multinomial sampling parameterized by bait concentration, binding energy, and genomic abundance before being passed to existing models of platform-specific errors. Implemented in Rust, RAmpSim reproduces empirical within-genome coverage and cross-species enrichment patterns observed in capture-based metagenomic datasets. RAmpSim generally outperforms a uniform baseline with respect to position-based earth mover's distance when compared against the empirical coverage distribution. Classification analysis also shows high recall in recovering empirical high-coverage regions while outperforming a uniform baseline. AVAILABILITY: Code, example scripts, and data sources are available at https://github.com/az002/RAmpSim.git.

Metagenomics↗
PubMed2026

Target Capture of Ancient Shell DNA Enables Phylogenetic Reconstruction of Deep-Sea Molluscs.

Target capture is widely used to enrich endogenous DNA from calcium phosphate skeletal material in vertebrates, but its performance on calcium carbonate hard parts widely produced by invertebrates remains poorly understood. Here, we compared DNA recovery from four fresh and 12 ancient (eight radiocarbon-dated to 1671-1135&#x2009;years old before present) deep-sea vesicomyid clam shells, including species Archivesica marissinica, A. nanshaensis and A. okutanii, using whole-genome sequencing (WGS) or target capture of ultraconserved elements (UCEs). WGS achieved 16.65% on-target read recovery of UCEs from fresh soft tissue, but <&#x2009;1% from shell specimens. By contrast, UCE capture in the same specimen increased on-target reads by up to 155-fold, reaching 29.84% in fresh shells and up to 72-fold, reaching 19.89% in ancient shells. Target capture of UCEs recovered 142-1001 loci per sample compared to 0-230 with WGS alone. Ancient shells of A. marissinica and A. okutanii, based on reads mapped with bwa-mem2 and bbmap, exhibited characteristic post-mortem DNA damage signals, with average 5'-end C-to-T misincorporation rates of 3.46% and 15.97%, respectively, exceeding the levels observed in fresh A. marissinica shells (maximum 1.24%). UCE-based phylogenetic reconstructions incorporating shell ancient DNA recovered two major clades within Pliocardiinae, consistent with published phylogenomic trees. Together, these findings demonstrate that target-capture enrichment enables effective recovery of highly degraded DNA from ancient mollusc shells and supports robust phylogenetic inference at the intrageneric scale, expanding the utility of shells-one of the most abundant invertebrate remains-for evolutionary, biogeographic and conservation studies.

Animals↗
PubMed1991

Ventricular pacing threshold and time to capture postdefibrillation in patients undergoing implantable cardioverter-defibrillator implantation.

To assess the effect of defibrillation and amiodarone on ventricular pacing threshold and time to capture in patients undergoing automatic implantable cardioverter-defibrillator (AICD) implantation, 28 patients were prospectively evaluated. The patients were entered into one of two protocols: Ia--epicardial ventricular pacing threshold measured at baseline (preventricular fibrillation induction) and 10 and 60 seconds postdefibrillation with 20 J, or Ib--two fibrillation-defibrillation sequences were performed 3 minutes apart and ventricular pacing thresholds were measured for each sequence at baseline and at 10 and 60 seconds postdefibrillation with 20 J. Ten patients also underwent asynchronous pacing at 1.1 times baseline threshold during ventricular fibrillation with measurement of time to capture postdefibrillation. All patients were randomly assigned to receive either amiodarone or no antiarrhythmic drug therapy. Ventricular fibrillation was induced with AC (applied for 1-2 seconds), and standard epicardial bipolar and epicardial patch electrodes of the AICD were used for pacing and defibrillation, respectively. Ventricular pacing threshold at baseline, 10 seconds, 60 seconds, and 3 minutes postdefibrillation did not differ significantly. There were no significant differences in patients with or without amiodarone therapy. Furthermore, there was no transient loss of ventricular capture postdefibrillation or significant difference in time to capture with amiodarone (less than or equal to 2 seconds). We conclude that following internal defibrillation with 20 J: (1) ventricular pacing threshold at 10 seconds, 60 seconds, and 3 minutes were not significantly different from baseline with one or two fibrillation-defibrillation sequences, (2) time to capture was short, and (3) there was no significant difference in no drug versus amiodarone. These findings have direct clinical importance in considering device therapy with both pacing and defibrillating capabilities.

Amiodarone↗
PubMed1992

Feasibility of using intracardiac impedance measurements for capture detection.

Energy consumption and longevity of modern pacemakers are determined by the controlling electronic circuitry and by the stimulation energy. While with technological progress the electronics' energy consumption has been reduced significantly, clinical practice shows that many cardiac pacemakers are programmed to suboptimal settings with regard to minimization of pacing energy consumption. Several methods for optimizing pacemaker output settings have been proposed in the past. The most promising concept is an output parameter optimizing pacemaker with automatic capture detection. We examined whether it is possible to distinguish between effective and ineffective pacemaker stimulus capture by analyzing high pass filtered intracardiac impedance signals that are derived from standard bipolar pacing leads. In one series of 11 patients undergoing replacement or implantation of chronic bipolar pacemakers, four patients during electrophysiology studies, and eight volunteers undergoing invasive electrophysiology trials, we examined intracardiac impedance signals obtained with various stimulation rates and output parameter settings. Additionally we analyzed a series of five patients with implanted pacemakers that can measure and telemeter intracardiac impedance signals. Several evaluation concepts have been analyzed regarding their ability to discriminate between effective and ineffective stimuli. We developed an adequate algorithm that detects capture or loss of capture at different output parameter settings based on intracardiac impedance analysis. The sensitivity is 98.5% and specificity is 91% to loss of capture for the currently investigated algorithm and this can be used to determine the optimal setting of pulse width and amplitude with regard to energy consumption. This concept is currently under realization in the external programmer and in the future an implementation of these algorithms within the pacemaker itself is intended.

Algorithms↗