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PubMed2004

Assessment of the target-capture PCR hepatitis B virus (HBV) DNA quantitative assay and comparison with commercial HBV DNA quantitative assays.

Recent clinical studies suggest that hepatitis B virus (HBV) load and genotype may be independent predictors of responses to antiviral therapies. However, it is difficult for clinicians to accurately determine viral loads in patient samples because results--both the values and the units of measure--can vary greatly among different tests. Accordingly, the World Health Organization (WHO) has produced the first international standard for HBV DNA for nucleic acid amplification technology (NAT) assays. In the present study, we describe the performance of the target-capture PCR HBV DNA quantitative assay for the quantitation of HBV DNA in clinical samples and reference panels. The range of quantitation was between 50 and 10(10) IU/ml. The sensitivity and accuracy of the target-capture PCR assay were demonstrated by using the HBV panel from Quality Control for Medical Diagnostics (QCMD) and the WHO HBV DNA standard. The target-capture PCR assay quantitated the six genotype A members of the QCMD panel and dilutions of the WHO HBV DNA standard within an accuracy of 74 to 142%. Compared to current serological methods, the assay offers window period reductions of 19 days prior to HBV surface antigen and 26 days prior to HBV e antigen detection. The target-capture PCR assay was also compared with four commercially available NAT assays, and the various units of measure were standardized with respect to the international units of the WHO HBV DNA standard. The target-capture PCR assay is a sensitive, accurate, high-throughput, rapid, and reproducible assay for the determination of HBV loads.

DNA, Viral↗

PubMed2006

DC-SIGN and CLEC-2 mediate human immunodeficiency virus type 1 capture by platelets.

Platelets can engulf human immunodeficiency virus type 1 (HIV-1), and a significant amount of HIV-1 in the blood of infected individuals is associated with these cells. However, it is unclear how platelets capture HIV-1 and whether platelet-associated virus remains infectious. DC-SIGN and other lectins contribute to capture of HIV-1 by dendritic cells (DCs) and facilitate HIV-1 spread in DC/T-cell cocultures. Here, we show that platelets express both the C-type lectin-like receptor 2 (CLEC-2) and low levels of DC-SIGN. CLEC-2 bound to HIV-1, irrespective of the presence of the viral envelope protein, and facilitated HIV-1 capture by platelets. However, a substantial fraction of the HIV-1 binding activity of platelets was dependent on DC-SIGN. A combination of DC-SIGN and CLEC-2 inhibitors strongly reduced HIV-1 association with platelets, indicating that these lectins are required for efficient HIV-1 binding to platelets. Captured HIV-1 was maintained in an infectious state over several days, suggesting that HIV-1 can escape degradation by platelets and might use these cells to promote its spread. Our results identify CLEC-2 as a novel HIV-1 attachment factor and provide evidence that platelets capture and transfer infectious HIV-1 via DC-SIGN and CLEC-2, thereby possibly facilitating HIV-1 dissemination in infected patients.

Animals↗

PubMed1986

Pathogenesis of pupillary capture after posterior chamber intraocular lens implantation.

Pupillary capture is an unusual complication of posterior chamber intraocular lens implantation and may occur in the early or late postoperative period. We describe a series of patients with early or late onset pupillary capture and describe the pathogenesis. Early capture results from mechanical factors and is usually preventable. Late capture may be mechanical but is usually a sequel to the formation and subsequent contraction of iridocapsular synechiae. Synechiae result from lens epithelial or iris stromal hyperplasia and myofibroblastic metaplasia; they may be minimised by an atraumatic technique and adequate control of postoperative inflammation. The effect of pupillary capture is largely cosmetic, and we encountered no specific complications attributable to it.

Aged↗

PubMedDate not supplied

Capturing and using clinical outcome data: implications for information systems design.

There is an urgent need to capture and record data related to clinical outcomes, but there are many barriers. The range of problems includes lack of agreement on conceptualization of the term "outcome," inadequate measures of outcomes, and inadequate information systems to capture and manipulate data that would reflect outcomes. This article focuses on information system requirements to capture, store, and utilize clinical outcome data. For greatest accuracy, outcome data should be captured as close to the source as possible, including direct data capture from patients themselves and from their families. To make maximum use of outcome data, systems must be designed to 1) store data in multipurpose databases; 2) share data across different platforms; 3) link outcome data to other data that might influence or explain outcomes; 4) allow querying of the data by authorized personnel; and 5) protect patient confidentiality.

Decision Support Systems, Management↗

PubMed1995

Estimating completeness of cancer registration: an empirical evaluation of the two source capture-recapture approach in Germany.

STUDY OBJECTIVE: In recent years, capture-recapture methods have become increasingly popular in estimating completeness of disease registries. This study aimed to assess the performance of the two source capture-recapture method in estimating the completeness of cancer registration. DESIGN: The study was conducted in the population based cancer registry of Saarland, Germany, for which there are three main sources of notifications: reports by clinicians and pathologists, and death certificates. For groups of cases notified by one of the three sources, known completeness of registration by the other two sources was compared with the corresponding two source capture-recapture estimates. PATIENTS: A total of 16,020 patients notified to the cancer registry in 1970, 1975, 1980, and 1985 were included in the analysis. MAIN RESULTS: There was a tendency towards underestimation of completeness of notifications from pathologists and death certificates for patients notified by clinicians which was essentially confined to the older age groups. In contrast, capture-recapture methods tended to overestimate completeness of notifications from clinicians and death certificates for patients notified by pathologists. This overestimation was observed consistently in all age groups and for all of the most common cancer sites. Nevertheless, deviations of estimated completeness from known completeness were generally small or moderate. Agreement between estimated and known completeness was closest for patients notified by death certificates, although completeness was somewhat underestimated in patients above age 75. The observed patterns are in agreement with knowledge on clinical aspects and clinical management of cancer patients and with the circumstances of cancer registration in Saarland. CONCLUSIONS: Careful application of capture-recapture methods may provide an alternative to traditional approaches for estimating completeness of cancer registration.

Adolescent↗

PubMed2002

Estimation of the prevalence of diagnosed diabetes from primary care and secondary care source data: comparison of record linkage with capture-recapture analysis.

STUDY OBJECTIVE: To compare multiple source linkage and capture-recapture analysis in determining the current age and gender specific prevalence of type 1 and type 2 diabetes in a UK white population. To assess whole population trends in diabetes prevalence and treatment by comparison with previous studies. DESIGN: Data were obtained from hospital sources and all 74 general practices in the study population. Analyses were carried out both by record linkage and by use of a two source capture-recapture model to correct for incomplete ascertainment. SETTING: County of Clwyd, North Wales: total population 418,200. MAIN RESULTS: By record linkage the age adjusted prevalence of all diabetes was 2.04 (95% confidence intervals 2.00 to 2.09)%. Using the capture-recapture method it was 2.29 (2.24 to 2.33)%. From capture-recapture data the age adjusted prevalence of type 1 diabetes was 0.40 (0.37 to 0.43)% in men and 0.28 (0.25 to 0.30)% in women; the prevalence of type 2 was 2.03 (1.97 to 2.09)% in men and 1.67 (1.62 to 1.72)% in women. These figures represent an increase compared with previous surveys. The age specific prevalence of type 2 diabetes was greater in men in a ratio of approximately 1.5:1 and there were more patients treated by diet alone. CONCLUSIONS: Record linkage using multiple sources underestimates the prevalence of diabetes compared with capture-recapture estimates. The results suggest the prevalence of known diabetes in the UK has approximately doubled in less than 20 years. There is an increasing preponderance of male patients and of patients treated currently with diet alone.

Adolescent↗

PubMed2001

Application of laser capture microdissection and proteomics in colon cancer.

AIMS: Laser capture microdissection is a recent development that enables the isolation of specific cell types for subsequent molecular analysis. This study describes a method for obtaining proteome information from laser capture microdissected tissue using colon cancer as a model. METHODS: Laser capture microdissection was performed on toluidine blue stained frozen sections of colon cancer. Tumour cells were selectively microdissected. Conditions were established for solubilising proteins from laser microdissected samples and these proteins were separated by two dimensional gel electrophoresis. Individual protein spots were cut from the gel, characterised by mass spectrometry, and identified by database searching. These results were compared with protein expression patterns and mass spectroscopic data obtained from bulk tumour samples run in parallel. RESULTS: Proteins could be recovered from laser capture microdissected tissue in a form suitable for two dimensional gel electrophoresis. The solubilised proteins retained their expected electrophoretic mobility in two dimensional gels as compared with bulk samples, and mass spectrometric analysis was also unaffected. CONCLUSION: A method for performing two dimensional gel electrophoresis and mass spectrometry using laser capture microdissected tissue has been developed.

Colon↗

PubMed2002

Hydrodynamic contributions to multimodal guidance of prey capture behavior in fish.

Water movements, of both abiotic and biotic origin, provide a wealth of information of direct relevance to the guidance of prey capture behavior. To gather hydrodynamic information, fish have sensors of two basic types: those scattered over the surface of the body known as superficial neuromasts and similar sensors embedded in subdermal lateral line canals. Recently, the anatomical dichotomy between superficial and canal neuromasts has been matched by demonstrations of a corresponding functional dichotomy. Prey detection and localization are evidently mediated by canal neuromasts, whereas superficial neuromasts are more sensitive to water flows over the surface of the fish and participate in the orientation to water currents, a behavior known as rheotaxis. However, rheotaxis in combination with chemosensory inputs can also guide fish to their prey. Thus there is evidence that both lateral line sub-modalities either alone or in concert with other senses play a role in prey capture. Are there circumstances where prey capture requires integration of information from both lateral line sub- modalities? Recent evidence shows that fish are capable of tracking other fish on the basis of the hydrodynamic trails left behind by their swimming motion. Pharmacological and physical ablation of lateral line end organs shows that indeed integration of information from both sub-modalities is required for the complex hydrodynamic task of natural prey capture in the dark. Furthermore, these experiments provide an excellent demonstration of the integration of hydrodynamic, chemosensory, tactile and visual information for the multimodal guidance of prey capture behavior.

Animals↗

PubMed1993

Orthodromic capture of the atrial electrogram during transient entrainment of atrioventricular nodal reentrant tachycardia.

BACKGROUND: The reentry circuit of atrioventricular nodal reentrant tachycardia (AVNRT) has not been fully demonstrated. We hypothesized that if an upper common pathway was present, the atrial electrogram could not be captured orthodromically during transient entrainment of AVNRT by rapid atrial pacing. Based on this hypothesis, the presence of an upper common pathway was investigated. METHODS AND RESULTS: The atrial electrogram at the recording site of the His bundle potential was identified during induced AVNRT in 9 patients. To entrain AVNRT transiently, rapid pacing from the high right atrium and coronary sinus was applied at a cycle length 10 milliseconds shorter than that of AVNRT and repeated after a decrement of the paced cycle length in steps of 5 milliseconds until AVNRT was interrupted. In 5 of 7 patients, orthodromic capture of the atrial electrogram at the recording site of the His bundle potential was observed during transient entrainment of AVNRT by coronary sinus pacing, ie, the first postpacing interval of the atrial electrogram at the recording site of the His bundle potential was the same as the paced cycle length. In these 5 patients, the mean minimum paced cycle length capable of orthodromic atrial capture was 349 milliseconds, and the mean difference from the cycle length of AVNRT was only 16 milliseconds. During transient entrainment of AVNRT by high right atrial pacing, the atrial electrogram could not be captured orthodromically. CONCLUSIONS: Observation of orthodromic capture of the atrial electrogram at the recording site of the His bundle potential by coronary sinus pacing ruled out the presence of an upper common pathway in AVNRT, and the concept that perinodal atrial tissue is involved in the reentry circuit of AVNRT was supported.

Atrial Function↗

PubMed1997

Diagnosis of smear-negative pulmonary tuberculosis using sequence capture polymerase chain reaction.

Techniques based on the polymerase chain reaction (PCR) can be used to rapidly identify DNA from Mycobacterium tuberculosis in clinical samples from patients with tuberculosis, but prior studies evaluating this approach in the diagnosis of paucibacillary forms of pulmonary tuberculosis have reported poor sensitivity and/or specificity. We have developed a procedure in which mycobacterial DNA in crude samples is specifically captured prior to amplification, thereby concentrating the target sequences and removing irrelevant DNA and other inhibitors of the amplification reaction (sequence capture PCR). To evaluate the usefulness of this approach in the diagnosis of paucibacillary forms of pulmonary tuberculosis, sequence capture PCR was performed prospectively on samples of bronchoalveolar lavage fluid from consecutive patients suspected of having pulmonary tuberculosis but for whom three consecutive samples of respiratory secretions were smear negative. Of the 27 patients evaluated, active tuberculosis was diagnosed in nine; sequence capture PCR was positive for all of these patients, including the three for whom all specimens submitted for culture were negative. No positive results were obtained for lavage fluid from the 18 patients for whom the diagnosis of active tuberculosis was subsequently excluded or 25 additional patients undergoing bronchoalveolar lavage for evaluation of other pulmonary problems, even though many of these patients had a history of prior tuberculosis or radiographic evidence of prior tuberculous infection. Paucibacillary forms of pulmonary tuberculosis can be rapidly identified with high sensitivity and specificity using sequence capture PCR performed on samples obtained by bronchoalveolar lavage.

Adult↗

PubMed1992

Optimization and characterization of capture ELISA methodology for Lp(a) lipoprotein quantification.

In order to better characterize and optimize a typical capture ELISA system for Lp(a) lipoprotein, we have analysed kinetic details of the reaction. Plate coating with polyclonal antibody, recognition of captured analyte with monoclonal antibody, and detection of monoclonal antibody with alkaline phosphatase-labeled antiglobulin were essentially complete after one hour, probably being driven forward by a relative excess of reagent. However, complete capture of the Lp(a) analyte required about 6 h at low input concentrations. Shorter time periods for capture might therefore result in decreased sensitivity and reproducibility. Deviations from linearity in the assay dose response were associated with incomplete capture of Lp(a) and significant depletion of the monoclonal recognition antibody. With the final reaction conditions described, no significant differences in immunochemical reactivity between samples were found by analysis of dose response slopes. Finally, interferences from plasminogen, -20 degrees C storage, anticoagulants, LDL, haemolysis, and bilirubin were minimal.

Animals↗

PubMed2002

Marginal zone macrophages express a murine homologue of DC-SIGN that captures blood-borne antigens in vivo.

Antigen-presenting cells are localized in essentially every tissue, where they operate at the interface of innate and acquired immunity by capturing pathogens and presenting pathogen-derived peptides to T cells. C-type lectins are important pathogen recognition receptors and the C-type lectin, dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN), is unique in that, in addition to pathogen capture, it regulates adhesion processes such as DC trafficking and T-cell synapse formation. We have isolated a murine homologue of DC-SIGN that is identical to the previously reported murine homologue mSIGNR1. mSIGNR1 is more closely related to the human DC-SIGN homologue L-SIGN than to DC-SIGN itself because mSIGNR1 is specifically expressed by liver sinusoidal endothelial cells, similar to L-SIGN, and not by DCs. Moreover, mSIGNR1 is also expressed by medullary and subcapsular macrophages in lymph nodes and by marginal zone macrophages (MZMs) in the spleen. Strikingly, these MZMs are in direct contact with the bloodstream and efficiently capture specific polysaccharide antigens present on the surface of encapsulated bacteria. We have investigated the in vivo function of mSIGNR1 on MZMs in spleen. We demonstrate here that mSIGNR1 functions in vivo as a pathogen recognition receptor on MZMs that capture blood-borne antigens, which are rapidly internalized and targeted to lysosomes for processing. Moreover, the antigen capture is completely blocked in vivo by the blocking mSIGNR1-specific antibodies. Thus, mSIGNR1, a murine homologue of DC-SIGN, is important in the defense against pathogens and this study will facilitate further investigations into the in vivo function of DC-SIGN and its homologues.

Amino Acid Sequence↗

PubMed2003

Indirect capture augments leukocyte accumulation on P-selectin in flowing whole blood.

Leukocytes are captured directly by E- and P-selectin on activated endothelium and by indirect means, which includes attached leukocytes capturing free-flowing leukocytes. However, controversy exists as to whether the latter mechanism occurs in the presence of red blood cells. We analyzed leukocyte capture mechanisms on P-selectin under circulatory hydrodynamics using whole blood. The selective disruption of leukocyte-leukocyte interactions with an L-selectin monoclonal antibody reduced leukocyte accumulation by >50% under various stringencies (substrate concentrations and shear stresses). In addition, a direct analysis of leukocyte capture events revealed that 69% were indirect. Our data indicate that in the presence of red blood cells, P-selectin-attached leukocytes, individually and as a monolayer, augment leukocyte accumulation by indirect capture. This mechanism may contribute to increasing the density of leukocytes on discrete areas of activated endothelial cells at sites of inflammation. These findings are significant since L-selectin accounts for the majority of the leukocyte rolling flux in small venules at diverse inflammatory settings. Yet, the primary mechanism by which L-selectin mediates leukocyte accumulation remains unresolved.

Antibodies, Monoclonal↗

PubMed2005

Prey capture kinematics of ant-eating lizards.

While morphological and behavioral feeding specializations are obvious in many vertebrate groups, among lizards there appear to be few dietary specialists. By comparing the prey capture kinematics and overall feeding behavior in two highly specialized ant-eating lizards (Moloch horridus and Phrynosoma platyrhinos) with those of two closely related dietary generalists (Pogona vitticeps and Uma notata), we investigate whether dietary specialization has been accompanied by changes in the function and use of the feeding system. We quantified kinematic variables from high-speed video recordings (200-250 frames s(-1)) of each species feeding on ants. Prey capture was strikingly different in M. horridus to that of other species, being characterized by a suite of unusual behaviors including the lack of a body lunge, faster tongue protrusion, reduced prey processing and, most notably, the ability to modulate the slow open phase of the gape cycle. In concert, these traits make a single feeding event in M. horridus faster than that in any other iguanian lizard studied to date. Prey capture behavior in P. platyrhinos is kinematically more similar to U. notata and P. vitticeps than to M. horridus, but the ant specialists are similar in that both lack distinct prey processing behaviors, resulting in faster overall capture and feeding events. While ant feeding in P. vitticeps is faster than feeding on other prey, the duration of a single feeding event is still four times longer than in either ant specialist, because of extensive prey processing. Additionally, a phylogenetic comparison of ant specialist lizards with dietary generalists revealed that ant-eating lizards require significantly less time to capture and process prey. Thus there are not only significant behavioral modifications in these ant-eating lizards, but also multiple strategies among specialists, suggesting differing selective pressures or phylogenetic constraints in the evolution of ant eating in lizards.

Animals↗

PubMed1995

Kinematics of prey capture in a flatfish, Pleuronichthys verticalis

Hornyhead turbot, Pleuronichthys verticalis (Pleuronectiformes: Pleuronectidae), are morphologically asymmetrical teleosts with substantial bilateral asymmetry in the neurocranium, suspensorium and anterior jaws. In order to quantify the kinematics of prey capture and to test for functional bilateral asymmetries, four individuals of this species were video-taped feeding using a high-speed video system at 200 fields s-1. Frame-by-frame analysis revealed several features not commonly found in prey capture behavior of previously studied ray-finned fishes. These features include (1) extreme lateral compression of the suspensorium and opercular series prior to mouth opening, indicating the consistent presence of a preparatory phase during feeding, (2) apparent dissociation of hyoid retraction and lower jaw depression, (3) prolonged hyoid retraction throughout much of the feeding cycle, and (4) concomitant dorsal rotation of the neurocranium and closing of the jaws. P. verticalis also demonstrate a significant degree of functional bilateral asymmetry during prey capture. When approaching prey, fish flex their heads towards the ocular (anatomically the right) side of the body. During prey capture, their jaws bend out of the midline towards the blind (left) side. Comparisons of the displacement and timing for movements of homologous anatomical features on the ocular and blind sides of the head reveal that maximum gape is always larger on the blind side of the head than on the ocular side. In contrast, other kinematic variables measured are similar on both sides of the head. These results suggest that P. verticalis possess unique functional features of prey capture behavior and that morphological bilateral asymmetry of the head and jaws is associated with, and perhaps causally related to, the functional bilateral asymmetry present during feeding.

Journal Article↗

PubMed2005

The kinetics of analyte capture on nanoscale sensors.

This article presents a number of kinetic analyses related to binding processes relevant to capture of target analyte species in nanoscale cantilever-type devices designed to detect small concentrations of biomolecules. The overall analyte capture efficiency is a crucial measure of the ultimate sensitivity of such devices, and a detailed kinetic analysis tells us how rapidly such measurements may be made. We have analyzed the capture kinetics under a variety of conditions, including the possibility of so-called surface-enhanced ligand capture. One of the modalities studied requires ligand capture through a cross-linking mechanism, and it was found that this mode may provide a robust and sensitive approach to biomolecular detection. For the two modalities studied, we find that detection of specific biomolecules down to concentration levels of 1 nM or less appear to be quite feasible for the device configurations studied.

Biopolymers↗

PubMed2002

Factors affecting capture of Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) in traps placed in stored wheat.

Cryptolestes ferrugineus (Stephens), the rusty grain beetle, infests grain externally and is a common pest of stored wheat throughout the world. Detection and population estimation of this insect are important in avoiding discounts at the point of sale. Laboratory experiments compared number of insect captures in the WNB II probe and PC trap in stored grain with a known insect density. Capture rates were strongly related to insect densities in wheat. In a simultaneous test of insect density, ranging from one to three insects per kilogram, and temperatures between 20 and 40 degrees C, insect captures in WB II probe traps increased linearly with insect density in the grain but had a quadratic response to temperature. Hole density, ranging from 40 to 120 holes along a 15-cm stretch of the trap body, was unrelated to number of insect captures. Probe trap diameters ranging from 26 to 60 mm were also unrelated to insect captures. Finally, dead rusty grain beetles were recovered in probe traps. The recovery of dead insects increased with insect density when insects were found in an aggregated dispersal pattern, such as would be found following phosphine fumigation of grain. Experiments discussed here will help grain managers understand how probe traps may be used in C. ferrugineus population estimation.

Animals↗

PubMed2005

Spodoptera frugiperda pheromone lures to avoid nontarget captures of Leucania phragmatidicola.

We confirmed that commercial three- or four-component Spodoptera frugiperda (J.E. Smith) pheromone lures had a high nontarget capture rate for Leucania phragmatidicola Guenée, which compromised monitoring efforts in the northeastern United States. We compiled taxonomic features to distinguish L. phragmatidicola from S. frugiperda, and we compared five new lures. S. frugiperda catch specificity was improved by removing (Z)-11-hexadecen-1-ol acetate (Z11-16:Ac), which attracted L. phragmatidicola. Four lures tracked late-season S. frugiperda immigration, but two of these lures also tracked a bivoltine L. phragmatidicola flight with a second generation coincident with S. frugiperda immigration, and one lure attracted the first, but not the second, generation of L. phragmatidicola. In both low- and high-moth flight conditions, two-component lures had low L. phragmatidicola captures (0.5-1.4%), and although lures with more pheromonal components captured more S. frugiperda, they also had a high percentage of capture of L. phragmatidicola (38-48%). We conclude that although two-component lures captured fewer S. frugiperda, their similar temporal pattern, along with the lower level of L. phragmatidicola, makes them useful for development for monitoring programs in the northeastern United States.

Animals↗