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PubMed1974

An electron-capture gas-liquid-chromatographic method for the determination of prostaglandin F2alpha in biological fluids.

A sensitive electron-capture gas-liquid-chromatographic method for the determination of sub-nanogram quantities of prostaglandin F(2alpha) was developed. The method is based on the sub-microgram scale conversion of the prostaglandin into the electron-capturing pentafluorobenzyl ester, and analysis of the latter as the tris-trimethylsilyl ether. The lower limit of detection was 12.5pg of the ester injected ;on-column' as the silylated product. The method was successfully applied to the determination of prostaglandin F(2alpha) in monkey plasma. The specificity of the analytical procedure was increased by incorporating a thin-layer chromatographic fractionation before gas-liquid chromatography. The utility of the analytical methodology developed was demonstrated by its application to the determination of plasma concentrations of intact prostaglandin F(2alpha) in a Rhesus monkey, after subcutaneous administration of a single dose of prostaglandin F(2alpha). The electron-capture gas-liquid-chromatographic assay is compared with the radioimmunoassay and the gas-liquid-chromatographic-mass-spectrometry assay for the determination of prostaglandin F(2alpha).

Animals↗

PubMed2000

Capture-recapture estimates of drug misuse in urban and non-urban settings in the north east of Scotland.

AIMS: To estimate the prevalence of opiate or benzodiazepine misuse in the Grampian Health Board area, Scotland and illustrate the use of the capture-recapture method in both rural and urban settings. DESIGN: Capture-recapture analyses on six distinct sources of data with unequal coverage of the geographical area. SETTING: Grampian Health Board area, including the City of Aberdeen. PARTICIPANTS: Data were collated from the Police, Social Work Departments, GPs contributing to the Scottish Drug Misuse Database, statutory drug agencies, a voluntary sector drug agency and a needle/syringe exchange. MEASUREMENTS: In total 1770 individuals were identified as misusing opiates or benzodiazepines and residing in the Grampian Health Board area; 1129 individuals were resident in the City of Aberdeen. FINDINGS: The total number of opiate or benzodiazepine misusers in the City of Aberdeen was estimated to be 2519 (95% CI 2048-3200). This figure corresponds to 2.0% (1.6-2.5%) of the population aged 15-54 years. In a town to the north of Aberdeenshire where high levels of heroin use had previously been reported in the media, 2.5% of the population aged 15-54 (1.8-3.8%) were estimated to be misusing opiates or benzodiazepines. CONCLUSIONS: Although there may be difficulties in applying capture-recapture methods in all settings, the methodology can give valuable information on the extent of drug misuse in both urban and non-urban areas. This information is particularly important to assess the spread of drug misuse from cities to rural areas.

Adolescent↗

PubMed2000

Across the Southern Alps by river capture? Freshwater fish phylogeography in South Island, New Zealand.

We used DNA analysis of galaxiid fish to test a hypothesis of localized headwater capture in South Island, New Zealand. The restricted western, but widespread eastern, distributions of three nonmigratory freshwater fish species suggest that part of the east-flowing Waiau River has been captured by the west-flowing Buller River. However, mitochondrial control region (Kimura 2-parameter distance = 4.1-5.4%) and microsatellite flanking sequences do not support a relationship between Waiau (N = 4 fish sequences) and western populations (N = 8) of Galaxias vulgaris. Instead, the point of capture is probably to the north-east, perhaps the Nelson lakes region. Phylogenetic analysis indicates that western populations, along with populations in the north-east (N = 18), represent a previously unidentified monophyletic Evolutionarily Significant Unit, possibly a cryptic species. We suggest a general caveat for zoogeographic conclusions based on distributional data alone.

Animals↗

PubMed2002

The P1 plasmid is segregated to daughter cells by a 'capture and ejection' mechanism coordinated with Escherichia coli cell division.

The fate of the P1 plasmid of Escherichia coli was followed by time-lapse photomicroscopy. A GFP-ParB fusion marked the plasmid during partition (segregation) to daughter cells at slow growth rate. The process differs from that previously inferred from statistical analysis of fixed cells. A focus of plasmid copies is captured at the cell centre. Immediately before cell division, the copies eject bidirectionally along the long axis of the cell. Cell division traps one or more plasmid copies in each daughter. They are not directed to a prescribed position but are free to move, associate and disassociate. Later, they are captured to the new cell centre to restart the cycle. A null P1 par mutant associates to form a focus, but it is neither captured nor ejected. A dominant negative ParB protein forms a plasmid focus that attaches to the cell centre but never ejects. It remains captive at the centre and blocks host cell division. The cells elongate. Eventually the intact focus is pushed to one side and the cells divide simultaneously in several places at the same time. This suggests that the wild-type plasmid imposes a regulatory node on the host cell cycle, preventing cell division until its own segregation is completed.

Bacterial Proteins↗

PubMed2003

Is there an optimal root architecture for nitrate capture in leaching environments?

Little is known about root architectural attributes that aid the capture of nitrate from coarse-textured soil profiles of high leaching potential. In this study, a range of root architectures from the herringbone to the dichotomous structure were simulated, and their capacity to take up nitrate leaching through a sandy profile was recorded. All root systems had equal total volume at each point in time, and so were considered cost equivalent. These simulations showed that the root architecture likely to maximize nitrate capture from sandy soils (under the Mediterranean rainfall pattern experienced in Western Australia) is one that quickly produces a high density of roots in the top-soil early in the season, thereby reducing total nitrate leached with opening season rains, but also has vigorous taproot growth, enabling access to deep-stored water and leached nitrate later in the season. This is the first published, spatially explicit attempt to assess the ability of different root architectures equivalent in cost, to capture nitrate from a spatially and temporally heterogeneous soil environment.

Journal Article↗

PubMed1997

[Evaluation of the completeness of the epidemiological surveillance systems for malaria by the Capture-recapture system in the French armies in l994].

The Capture-recapture method has been utilized to evaluate the annual incidence of malaria in the French armies in 1994 on the basis of the incidence derived from two regulatory systems, passive and exhaustive, of epidemiological surveillance: the Recueil et l'Exploitation des Données Epidémiologiques des Armées (REDEA) and the Surveillance Epidémiologique du Paladisme (SESP) system. Cases of malaria found by REDEA and SESP in 1994 rose to 480 and 424 respectively. Two hundred and thirty-eight cases were found by both systems. After validating the conditions for the application of the Capture-recapture method (in particular, having verified that the results from REDEA and SESP were probably independent), its utilization allowed us to evaluate the incidence of malaria in the French army in 1994 at 854 cases. The calculated exhaustivity values for REDEA and SESP were 56.2 and 49.6% respectively; 22% of cases were missed by both systems. The exhaustivity values of SESP and REDEA estimated in our study were comparable to those obtained by the Capture-recapture method applied in another legal inquiry into the passive and exhaustive epidemiological surveillance of meningitis and meningococcosis in France in 1989 and 1990. These results show that it is difficult to evaluate the epidemiological importance of a sickness on the results of passive and exhaustive surveillance alone. In 1995, a new system of surveillance was established in the army: a better conducted and more motivated retro-informative system, linked to a better education of medical officers in epidemiological surveillance permitted an improvement in the completeness of the results in the armies.

France↗

PubMed2000

Primary posterior capsulorhexis with optic capture and intracameral heparin in paediatric cataract surgery.

PURPOSE: To study the efficacy of using a primary posterior capsulorhexis with optic capture and intracameral heparin in preventing secondary posterior capsule opacification, in paediatric cataract surgery. METHODS: Primary posterior capsulorhexis and optic capture with a heparin-coated intraocular lens (IOL) was performed after lens aspiration in 14 cataractous eyes of 13 children (group I). Ten international units of heparin were added in the irrigating solution. The results were compared with 14 eyes of 11 children who underwent a similar surgical procedure but without a posterior capsulorhexis (group 2). RESULTS: The mean age of the patients in group I was 4.2+/-1.5 years (mean +/- SD) and in group 2 was 4.5+/-1.8 years (range 3-6 years in both the groups). The mean duration of follow up was 36+/-6.4 months in group I and 38+/-8.1 months in group 2. A best corrected visual acuity of 6/24 or better was achieved in 12 eyes in group I and II eyes in group 2. The visual axis remained clear in all the eyes in group I, while 8 eyes (57.14%) in group 2 developed posterior capsule opacification (P = 0.0034) which required a neodymium:yttrium-aluminum-garnet laser capsulotomy. CONCLUSIONS: Lens aspiration using intracameral heparin, combined with primary posterior capsulorhexis and optic capture of a heparin-coated IOL, is a useful technique to prevent secondary visual axis opacification in paediatric cataracts.

Anterior Chamber↗

PubMed1998

Nucleation and capture of large cell surface-associated microtubule arrays that are not located near centrosomes in certain cochlear epithelial cells.

This report deals with the as yet undetermined issue of whether cell-surface associated microtubules in certain cochlear epithelial cells are centrosomally nucleated and subsequently migrate to microtubule-capturing sites located at the surface regions in question. Alternatively, the cells may possess additional nucleating sites which are noncentrosomal and surface-associated. These alternative possibilities have been investigated for highly polarised epithelial cells called supporting cells in the mouse and guinea pig organ of Corti using antibodies to pericentrin and gamma-tubulin. There is substantial evidence that both proteins are essential components of microtubule-nucleating sites in cells generally. Each mature supporting cell possesses a large microtubule array that is remotely located with respect to its centrosome (more than 10 microns away). The antibodies bind to a cell's centrosome. No binding has been detected at 2 other microtubule-organising centres that are associated with the ends of the centrosomally-remote microtubule array while it is being constructed. Such arrays include thousands of microtubules in some of the cell types that have been examined. If all a cell's microtubules are nucleated by its centrosome then the findings reported above imply that microtubules escape from the centrosomal nucleating site and migrate to a new location. Furthermore capture of the plus and minus ends of the errant microtubules is taking place because both ends of a centrosomally-remote microtubule array are attached to sites that are precisely positioned at certain cell surface locations. Minus ends are locating targets with an exactitude comparable to that which has been demonstrated for plus ends in certain cell types. These cells apparently operate a single control centre strategy for microtubule nucleation that is complemented by precise positioning of plus and minus end-capturing sites at the cell surface.

Animals↗

PubMed2003

PCR-based detection of white spot syndrome virus in cultured and captured crustaceans in India.

AIMS: The occurrence and distribution of white spot syndrome virus (WSSV) among cultured and captured penaeid shrimps and crustaceans in the east coast of India was determined from November 1999 to April 2002 using PCR as a diagnostic tool. METHODS AND RESULTS: A total of 630 cultured samples consisting of 280 postlarvae collected from nine different hatcheries and 350 juvenile shrimps (40-60-day-old) collected from 18 different culture ponds were screened for WSSV. Of these cultured samples tested 53% were found to be single-step PCR positive. A total of 419 samples of captured crustaceans viz., Penaeus monodon brooders, P. indicus juveniles, Metapenaeus spp., crab Scylla serrata and Squilla mantis were also screened for WSSV by PCR, 23% of them were infected with WSSV. CONCLUSIONS: This study concluded that WSSV could be widespread in cultured and captured shrimps and other crustaceans in India. SIGNIFICANCE AND IMPACT OF THE STUDY: The results indicate that PCR screening of WSSV infection and rejection of infected stocks greatly assists shrimp aquaculture farmers for successful production and harvest.

Animals↗

PubMed1993

Chaotic capture of vortices by a moving body. I. The single point vortex case.

The study of the dynamical properties of vortex systems is an important and topical research area, and is becoming of ever increasing usefulness to a variety of physical applications. In this paper, we present a study of a model of a rotational singularity which obeys a logarithmic potential interacting with a bluff body in a uniform inviscid laminar flow, e.g., a line vortex interacting with a cylinder in three dimensions or a point vortex with a circular boundary in two dimensions. We show that this system is Hamiltonian and simple enough to be solved analytically for the stagnation points and separatrices of the flow, and a bifurcation diagram for the relevant parameters and classification of the various types of motion is given. We also show that, by introducing a periodic perturbation to the body, chaotic motion of the vortex can be readily generated, and we present analytic criteria for the generation of chaos using the Poincare-Melnikov-Arnold method. This leads to an important dynamical effect for the model, i.e., that the possibility exists for the vortex to be chaotically captured around the body for periods of time which are extremely sensitive to initial conditions. The basic mechanism for this capture is due to the chaotic dynamics and is similar to that of other chaotic scattering phenomena. We show numerically that cases exist where the vortex can be captured around an elliptic point external to (and possibly far from) the body, and the existence of other very complicated motions are also demonstrated. Finally, generalizations of the problem of the vortex-body interaction are indicated, and some possible applications are postulated such as the interaction of line vortices with aircraft wings.

Journal Article↗

PubMed2004

Quantum scattering and adiabatic channel treatment of the low-energy and low-temperature capture of a rotating quadrupolar molecule by an ion.

The capture rate coefficients of homonuclear diatomic molecules (H(2) and N(2)) in the rotational state j=1 interacting with ions (Ar+ and He+) are calculated for low collision energies assuming a long-range anisotropic ion-induced dipole and ion-quadrupole interaction. A comparison of accurate quantum rates with quantum and state-specific classical adiabatic channel approximations shows that the former becomes inappropriate in the case when the cross section is dominated by few partial contributions, while the latter performs better. This unexpected result is related to the fact that the classical adiabatic channel approximation artificially simulates the quantum effects of tunneling and overbarrier reflection as well as the Coriolis coupling and it suppresses too high values of the centrifugal barriers predicted by a quantum adiabatic channel approach. For H2(j=1)+Ar+ and N(2)(j=1)+He+ capture, the rate constants at T-->0 K are about 3 and 6 times higher than the corresponding values for H2(j=0)+Ar+ and N(2)(j=0)+He+ capture.

Journal Article↗

PubMed2004

Insect aquaplaning: Nepenthes pitcher plants capture prey with the peristome, a fully wettable water-lubricated anisotropic surface.

Pitcher plants of the genus Nepenthes have highly specialized leaves adapted to attract, capture, retain, and digest arthropod prey. Several mechanisms have been proposed for the capture of insects, ranging from slippery epicuticular wax crystals to downward-pointing lunate cells and alkaloid secretions that anesthetize insects. Here we report that perhaps the most important capture mechanism has thus far remained overlooked. It is based on special surface properties of the pitcher rim (peristome) and insect "aquaplaning." The peristome is characterized by a regular microstructure with radial ridges of smooth overlapping epidermal cells, which form a series of steps toward the pitcher inside. This surface is completely wettable by nectar secreted at the inner margin of the peristome and by rain water, so that homogenous liquid films cover the surface under humid weather conditions. Only when wet, the peristome surface is slippery for insects, so that most ant visitors become trapped. By measuring friction forces of weaver ants (Oecophylla smaragdina) on the peristome surface of Nepenthes bicalcarata, we demonstrate that the two factors preventing insect attachment to the peristome, i.e., water lubrication and anisotropic surface topography, are effective against different attachment structures of the insect tarsus. Peristome water films disrupt attachment only for the soft adhesive pads but not for the claws, whereas surface topography leads to anisotropic friction only for the claws but not for the adhesive pads. Experiments on Nepenthes alata show that the trapping mechanism of the peristome is also essential in Nepenthes species with waxy inner pitcher walls.

Animals↗

PubMed2004

Nonergodic and conformational control of the electron capture dissociation of protein cations.

Electron capture dissociation (ECD) MS is proving to be unusually valuable for "top down" protein sequencing and identification/localization of posttranslational modifications, because the ECD product ions can represent cleavages between most of a protein's amino acids. As proposed, this unusual reactivity results from immediate local utilization, before randomization, of much of the relatively large ( approximately 6 eV) energy from the electron reaction with the multiply charged protein ion, minimizing the effect of differences in the backbone bond dissociation energies. However, others conclude that e(-) capture produces a labile free radical species for which backbone cleavage is the lowest energy reaction. Supporting the nonergodic mechanism, ECD of ubiquitin (M + 12H)(12+) ions also yields thermalized radical (M + 12H)(11+.) ions that instead lose H. when activated. Also, the ECD spectrum of ubiquitin (M + 13H)(13+) ions is nearly unchanged by heating from 25 degrees C to 125 degrees C, demonstrating that this increase in thermal energy is small compared to the energy driving the reaction. These results support initial capture of the electron in a long-lived high-n Rydberg state, followed by internal conversion to the product valence state at an energy well above the dissociation barriers. The instantaneous conformation of the valence state is critical, with the observed products supporting an alpha-helical structure in which the protonated side chain of each basic residue is intercalated to hydrogen-bond to as many as three amide carbonyls. Activation (e.g., heat, collisions, lowered charge) can disrupt this conformation to allow additional H(+)-side-chain interactions and provide more complete sequence coverage.

Amino Acid Sequence↗

PubMed2002

Laser capture microdissection analysis of gene expression in macrophages from atherosclerotic lesions of apolipoprotein E-deficient mice.

Macrophage foam cells are integral in the development of atherosclerotic lesions. Gene expression analysis of lesional macrophage foam cells is complicated by the cellular heterogeneity of atherosclerotic plaque and the presence of lesions of various degrees of severity. To overcome these limitations, we tested the ability of laser capture microdissection (LCM) and real-time quantitative reverse transcription PCR to selectively analyze RNA from lesional macrophages of apolipoprotein E (apoE)-deficient mice. Proximal aortic tissue sections were immunostained for macrophagespecific CD68/macrosialin by a rapid (approximately 15-min) protocol. Alternating sections from each animal were used to isolate RNA either from entire sections (analogous to isolation from whole tissue) or by LCM selection of CD68-positive cells. We measured the mRNA levels of CD68, a macrophage-specific marker, alpha-actin, a smooth muscle cell marker, and cyclophilin A, a control gene. Compared with whole sections, CD68 mRNA levels were greatly enriched (33.6-fold) in the laser-captured lesional macrophages. In contrast to whole sections, LCM-derived RNA had undetectable levels of alpha-actin. To illustrate the ability of this method to measure changes in lesional macrophage gene expression, we injected 100 microg of lipopolysaccharide i.p. into apoE-deficient mice and detected in laser-captured lesional macrophages increased mRNA expression for vascular cell adhesion molecule-1, intercellular cell adhesion molecule-1, and monocyte chemoattractant protein-1 (11.9-, 32.5-, and 31.0-fold, respectively). By selectively enriching foam cell RNA, LCM provides a powerful approach to study the in situ expression and regulation of atherosclerosis-related genes. This approach will allow the study of macrophage gene expression under various conditions of plaque formation, regression, and response to genetic and environmental perturbations.

Actins↗

PubMed2006

The dominant role of CD8+ dendritic cells in cross-presentation is not dictated by antigen capture.

Mouse spleens contain three populations of conventional (CD11c(high)) dendritic cells (DCs) that play distinct functions. The CD8(+) DC are unique in that they can present exogenous antigens on their MHC class I molecules, a process known as cross-presentation. It is unclear whether this special ability is because only the CD8(+) DC can capture the antigens used in cross-presentation assays, or because this is the only DC population that possesses specialized machinery for cross-presentation. To solve this important question we examined the splenic DC subsets for their ability to both present via MHC class II molecules and cross-present via MHC class I using four different forms of the model antigen ovalbumin (OVA). These forms include a cell-associated form, a soluble form, OVA expressed in bacteria, or OVA bound to latex beads. With the exception of bacterial antigen, which was poorly cross-presented by all DC, all antigenic forms were cross-presented much more efficiently by the CD8(+) DC. This pattern could not be attributed simply to a difference in antigen capture because all DC subsets presented the antigen via MHC class II. Indeed, direct assessments of endocytosis showed that CD8(+) and CD8(-) DC captured comparable amounts of soluble and bead-associated antigen, yet only the CD8(+) DC cross-presented these antigenic forms. Our results indicate that cross-presentation requires specialized machinery that is expressed by CD8(+) DC but largely absent from CD8(-) DC. This conclusion has important implications for the design of vaccination strategies based on antigen targeting to DC.

Animals↗

PubMed2000

Unique role of the chemokine domain of fractalkine in cell capture. Kinetics of receptor dissociation correlate with cell adhesion.

The chemokine fractalkine (FK) has two structural features that make it unique in the chemokine family: a CX(3)C motif and an extended carboxyl terminus that anchors it to the cell surface. This mucin-like stalk or an equivalent spacer is required for FK to mediate the adhesion of cells expressing its receptor, CX(3)CR1. To determine whether the ability of FK to act as a cell adhesion molecule is due to the unique presentation of a chemokine domain on a stalk or to properties of the chemokine domain itself, we created a series of chimeras in which other soluble chemokines (RANTES (regulated on activation normal T cell expressed), monocyte chemoattractant protein 1, macrophage inflammatory protein 1 beta, secondary lymphoid tissue chemokine, and interleukin 8) were fused to the mucin stalk. When tested in a static-cell adhesion assay, many of these chemokine chimeras demonstrated activity equivalent to that of FK. In flow assays, however, none of the chimeras captured cells as efficiently as FK. Interestingly, FK captured cells expressing either CX(3)CR1 or the viral receptor US28. Cells bound to FK without rolling or detaching, whereas the interleukin 8 and monocyte chemoattractant protein 1 chimeras induced primarily cell rolling and detaching, respectively. In binding studies, FK has a significantly slower off-rate from its receptors than any of the other chemokine chimeras had for their cognate receptors. We conclude that presentation of a chemokine atop a mucin-like stalk is not, in and of itself, sufficient to capture cells. The unique ability of FK to mediate adhesion under flow may be a function of its slow receptor off-rate.

Animals↗

PubMed2003

Effects of the trematode Microphallus turgidus on locomotion and prey capture in the grass shrimp Palaemonetes pugio.

The grass shrimp, Palaemonetes pugio, is common in estuaries and marshes along the east coast of the USA and is frequently infected with metacercariae of the trematode, Microphallus turgidus. To test whether or not M. turgidus has an effect on intermediate host behaviour, the length of time spent swimming and walking over 1 min and 3 min intervals and prey (Artemia) capture rates of uninfected grass shrimp and those infected with 1-10, 11-20 or 21-30 metacercarial cysts were compared. Uninfected shrimps spent significantly more time swimming than infected shrimps during the first minute of observation. There were no differences between the control and infected groups in terms of swimming at 3 min, walking at 1 and 3 min, or in numbers of prey captured. These results indicate that M. turgidus may induce little or no change in grass shrimp locomotion nor in prey capture behaviour. This is in contrast to other parasites that modify intermediate host behaviour to enhance their transmission to definitive hosts. Furthermore, these data support earlier studies indicating that M. turgidus does not affect the growth and survival of P. pugio.

Animals↗

PubMed1986

Capture and detection of carcinoembryonic antigen on antibody coated beads used in enzyme immunoassay.

We have evaluated antibody coated beads for capture and detection of carcinoembryonic antigen (CEA). Assay parameters of time, temperature, buffer molarity, specificity of antibody on the bead and reagent addition sequence have been studied. Optimal assay kinetics occurred at a temperature of 45 degrees C and a buffer molarity of 0.1M or above. The type and quantity of antibody on the bead surface were also critical to optimal CEA detection. Beads coated with baboon or goat anti-CEA antibody were able to capture a higher percentage of CEA than monoclonal mouse anti-CEA antibody or guinea pig anti-CEA antibody. The sequence of addition of CEA, anti-CEA antibody coated bead, and anti-CEA-horse radish peroxidase conjugate was important for optimal CEA detection. Formation of an immune complex of CEA with the anti-CEA horse radish peroxidase conjugate prior to capture of the CEA on an antibody bead resulted in the optimal detection of CEA.

Animals↗