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PubMed2002

Stage-specific expression of genes associated with rat spermatogenesis: characterization by laser-capture microdissection and real-time polymerase chain reaction.

Spermatogenesis in the rat consists of 14 unique morphologic cellular associations between Sertoli cells and developing germ cells within the seminiferous epithelium. The complexity of the cellular associations leads to difficulty in the isolation of individual cells at a defined stage of development for the study of their unique patterns of gene or protein expression. Thus, laser-capture microdissection is an ideal technique to permit such analysis. This study used laser-capture microdissection and real-time reverse transcription-polymerase chain reaction (RT-PCR) to quantitate the stage-specific expression of a series of genes of functional significance in hormonal regulation and cell-cell interactions in spermatogenesis, including cathepsin-L, CREM-tau, transition protein-1, androgen receptor, beta1-integrin, N-cadherin, and hypoxanthine phosphoribosyltransferase (HPRT). Frozen sections (10 micro m) were obtained from normal adult rat testes. Laser-capture microdissection (LCM) was used to capture all cells in cross-sections of seminiferous tubules that were grouped into stages I-V, VII-VIII, and IX-XIII. Transition protein-1 expression was lowest during stages I-V and increased 5.9-fold during stages VII-VIII and IX-XIII (P < 0.01). Cathepsin-L expression was highest during stages I-V and VII-VIII, falling 4.9-fold during stages IX-XIII (P < 0.05). Similarly, CREM-tau expression was highest during stages I-V and VII-VIII, falling 1.6-fold during stages IX-XIII (P < 0.05). A novel CREM-tau isoform lacking the phosphorylation domain was also characterized but was not stage-specific. beta1-Integrin, N-cadherin, and androgen receptor expression did not change between the spermatogenic stages examined. HPRT housekeeper expression was lowest during stages I-V but increased 1.5-fold during stages VII-VIII and IX-XIII (P < 0.05). This study is the first to apply LCM and real-time RT-PCR analysis to quantitate stage-specific changes in the expression of multiple genes in the seminiferous epithelium.

Animals↗

PubMed1998

Spinal cord injury incidence in Mississippi: a capture-recapture approach.

BACKGROUND: Many studies have investigated spinal cord injury incidence rates. Few, however, have adjusted for the underascertainment. The current study used the capture-recapture method to estimate the ascertainment-corrected spinal cord injury incidence rate in Mississippi. METHODS: Two sources were used for case ascertainment: Mississippi's spinal cord injury registry and hospital reports. The two-sample capture-recapture method was used to adjust for undercount. RESULTS: Two hundred one spinal cord injuries were reported to or found by the Mississippi State Department of Health in 1993, with a crude incidence rate of 7.8 per 100,000 population per year among hospital admissions and prehospital fatalities. Using the two-sample capture-recapture method, it is estimated that the incidence rate would be 9.3 per 100,000 population per year. CONCLUSION: Capture-recapture estimates suggest that Mississippi's spinal cord injury incidence rate is more than twice the national average.

Epidemiologic Methods↗

PubMed2006

Analysis of simulated angiographic procedures: part 1--capture and presentation of audio and video recordings.

PURPOSE: To assess different methods of recording angiographic simulations and to determine how such recordings might be used for training and research. MATERIALS AND METHODS: Two commercially available high-fidelity angiography simulations, the Mentice Vascular Interventional Simulation Trainer and the Simbionix AngioMentor, were used for data collection. Video and audio records of simulated procedures were created by different methods, including software-based screen capture, video splitters and converters, and external cameras. Recording parameters were varied, and the recordings were transferred to computer workstations for postprocessing and presentation. RESULTS: The information displayed on the simulators' computer screens could be captured by each method. Although screen-capture software provided the highest resolution, workflow considerations favored a hardware-based solution that duplicated the video signal and recorded the data stream(s) at lower resolutions. Additional video and audio recording devices were used to monitor the angiographer's actions during the simulated procedures. The multiple audio and video files were synchronized and composited with personal computers equipped with commercially available video editing software. Depending on the needs of the intended audience, the resulting files could be distributed and displayed at full or reduced resolutions. CONCLUSIONS: The capture, editing, presentation, and distribution of synchronized multichannel audio and video recordings holds great promise for angiography training and simulation research. To achieve this potential, technical challenges will need to be met, and content will need to be tailored to suit the needs of trainees and researchers.

Angiography↗

PubMed2002

Coevolving avian eye size and brain size in relation to prey capture and nocturnality.

Behavioural adaptation to ecological conditions can lead to brain size evolution. Structures involved in behavioural visual information processing are expected to coevolve with enlargement of the brain. Because birds are mainly vision-oriented animals, we tested the predictions that adaptation to different foraging constraints can result in eye size evolution, and that species with large eyes have evolved large brains to cope with the increased amount of visual input. Using a comparative approach, we investigated the relationship between eye size and brain size, and the effect of prey capture technique and nocturnality on these traits. After controlling for allometric effects, there was a significant, positive correlation between relative brain size and relative eye size. Variation in relative eye and brain size were significantly and positively related to prey capture technique and nocturnality when a potentially confounding variable, aquatic feeding, was controlled statistically in multiple regression of independent linear contrasts. Applying a less robust, brunching approach, these patterns also emerged, with the exception that relative brain size did not vary with prey capture technique. Our findings suggest that relative eye size and brain size have coevolved in birds in response to nocturnal activity and, at least partly, to capture of mobile prey.

Animals↗

PubMed2006

Diffusive capture process on complex networks.

We study the dynamical properties of a diffusing lamb captured by a diffusing lion on the complex networks with various sizes of N. We find that the lifetime {T} of a lamb scales as {T} approximately N and the survival probability S(N-->infinity, t) becomes finite on scale-free networks with degree exponent gamma > 3. However, S(N, t) for gamma < 3 has a long-living tail on tree-structured scale-free networks and decays exponentially on looped scale-free networks. This suggests that the second moment of degree distribution {k2} is the relevant factor for the dynamical properties in the diffusive capture process. We numerically find that the normalized number of capture events at a node with degree k, n(k), decreases as n(k) approximately k(-sigma). When gamma < 3, n(k) still increases anomalously for k approximately kmax, where kmax is the maximum value of k of given networks with size N. We analytically show that n(k) satisfies the relation n(k) approximately {k2}P(k) for any degree distribution P(k) and the total number of capture events Ntot is proportional to {k2}, which causes the gamma -dependent behavior of S(N, t) and {T}.

Journal Article↗

PubMed2001

Radiative proton capture on (6)He.

Radiative capture of protons is investigated as a probe of clustering in nuclei far from stability. The first such measurement on a halo nucleus is reported here for the reaction 6He(p,gamma) at 40 MeV. Capture into 7Li is observed as the strongest channel. In addition, events have been recorded that may be described by quasifree capture on a halo neutron, the alpha core, and 5He. The possibility of describing such events by capture into the continuum of 7Li is also discussed.

Journal Article↗

PubMed2005

Hierarchical chain model of spider capture silk elasticity.

Spider capture silk is a biomaterial with both high strength and high elasticity, but the structural design principle underlying these remarkable properties is still unknown. It was revealed recently by atomic force microscopy that an exponential force-extension relationship holds both for capture silk mesostructures and for intact capture silk fibers [N. Becker et al., Nat. Mater. 2, 278 (2003)]]. In this Letter a simple hierarchical chain model was proposed to understand and reproduce this striking observation. In the hierarchical chain model, a polymer is composed of many structural motifs which organize into structural modules and supramodules in a hierarchical manner. Each module in this hierarchy has its own characteristic force. The repetitive patterns in the amino-acid sequence of the major flagelliform protein of spider capture silk is in support of this model.

Animals↗

PubMed1999

A goodness-of-fit test for capture-recapture model Mt under closure.

A new, fully efficient goodness-of-fit test for the time-specific closed-population capture-recapture model Mt is presented. This test is based on the residual distribution of the capture history data given the maximum likelihood parameter estimates under model Mt, is partitioned into informative components, and is based on chi-square statistics. Comparison of this test with Leslie's test (Leslie, 1958, Journal of Animal Ecology 27, 84-86) for model Mt, using Monte Carlo simulations, shows the new test generally outperforms Leslie's test. The new test is frequently computable when Leslie's test is not, has Type I error rates that are closer to nominal error rates than Leslie's test, and is sensitive to behavioral variation and heterogeneity in capture probabilities. Leslie's test is not sensitive to behavioral variation in capture probabilities but, when computable, has greater power to detect heterogeneity than the new test.

Animals↗

PubMed2002

Determination of the unknown age at first capture of western rock lobsters (Panulirus cygnus) by random effects model.

We propose a method for fitting growth curves to multiple recapture data of lobsters when the age at first capture is unknown. The von Bertalanffy growth curve is used to model the growth. To account for individual variability, the unknown age in logarithmic scale of a lobster at first capture, the individual asymptotic size, and the individual growth coefficient of its carapace length are modeled as random effects with a trivariate normal distribution. Unlike previously suggested models, the present model permits correlation between the growth coefficient and the age at first capture and can be fitted readily using existing software. The error structures between consecutive recaptures of a lobster are assumed to be a first-order autoregressive process with unequally spaced time points. A comparison between this model and the Fabens growth equation is given. The proposed method is a flexible method and can be applied to fit different growth equations when the age at first capture is unknown.

Age Factors↗

PubMed2003

A model for chloroplast capture.

Chloroplast capture, the introgression of a chloroplast from one species into another, has been frequently suggested as the explanation for inconsistencies between gene trees based on nuclear and cytoplasmic markers in plants. We use a genetic model to determine the conditions for capture to occur, and we find that they are somewhat more general than those given in earlier verbal arguments. Chloroplast capture can occur if cytoplasm substitution provides an advantage in seed production. This can happen through reallocation to the female function when cytonuclear incompatibilities cause partial male sterility, but also under more general conditions. Capture is promoted by nuclear incompatibilities between the two genomes (or a low heterosis in F1 hybrids) and by partial selfing when hybridization causes a decrease in the selfing rate and inbreeding depression is strong. We discuss empirical predictions that can be used to test this mechanism.

Biological Evolution↗

PubMed2005

Do new objects capture attention?

The visual system relies on several heuristics to direct attention to important locations and objects. One of these mechanisms directs attention to sudden changes in the environment. Although a substantial body of research suggests that this capture of attention occurs only for the abrupt appearance of a new perceptual object, more recent evidence shows that some luminance-based transients (e.g., motion and looming) and some types of brightness change also capture attention. These findings show that new objects are not necessary for attention capture. The present study tested whether they are even sufficient. That is, does a new object attract attention because the visual system is sensitive to new objects or because it is sensitive to the transients that new objects create? In two experiments using a visual search task, new objects did not capture attention unless they created a strong local luminance transient.

Attention↗

PubMed1988

Factors influencing silhouette trap captures of the blackfly Austrosimulium bancrofti in Queensland, Australia.

Three silhouette traps of novel design were used to investigate the trap finding ability of female Austrosimulium bancrofti (Taylor) (Diptera: Simuliidae) in southeast Queensland. The traps were 'upright', 'elongate' or 'square' in shape. Five highly significant factors: hour after sunrise, temperature, relative humidity, trap shape and distance between traps, were included in a model which generated fitted estimates of flies captured under defined conditions. The rate of increase and the level of maximum capture rate indicated that the elongate trap captured the highest numbers of blackflies. An interaction between hour after sunrise and temperature suggests a strong endogenous modification of trap finding activity. Numbers captured increased with increasing distance between traps and decreasing relative humidity. The importance of these results in understanding behaviour of A. bancrofti is discussed.

Animals↗

PubMed2002

Does capture-recapture analysis provide more reliable estimates of the incidence and prevalence of leg ulcers in the community?

OBJECTIVE: To determine whether capture-recapture analysis provides more reliable estimates of the cumulative incidence and prevalence of leg ulcers in Auckland, New Zealand. METHODS: A population-based, cross-sectional study was conducted in the Central and North Auckland health districts of New Zealand in 1998. Cases were identified through health professional referral and by self-notification. All ages and ulcer types were investigated. Both traditional and capture-recapture methods of analysis were used to estimate the cumulative incidence and prevalence of leg ulcers in the study population. RESULTS: Four hundred and twenty-six people with current leg ulcers were identified during the 12-month study period. Using traditional methods of analysis, the annual cumulative incidence rate of leg ulcers in Auckland was 32 per 100,000, with a point prevalence of 39 per 100,000 and a period prevalence of 79 per 100,000 per year. Results from capture-recapture analysis, however, suggest an annual cumulative incidence rate of 252 per 100,000, with a point prevalence of 248 per 100,000 and a period prevalence of 530 per 100,000 per year. CONCLUSIONS: The traditional method of calculating cumulative incidence and prevalence clearly under-estimates the frequency of leg ulcers in the Auckland region. Capture-recapture analysis provides a more reliable estimate of disease frequency, since cases that remain unidentified in the population are considered.

Adolescent↗

PubMed2005

Unique temporal change is the key to attentional capture.

Attentional capture refers to the observation that some events break through and attract one's attention even when one is engaged in a task for which these events are irrelevant. Previous research, focusing primarily on spatial factors, has shown that a new object is more salient in this regard than an abrupt change in an object's features. Here we show that feature changes can be as effective as new objects in capturing attention, provided that they occur during a period of temporal calm. Conversely, both feature changes and new objects are far less effective in capturing attention when they occur simultaneously with other display changes, such as coincident with the initial onset of the display or with small visual transients that occur during a display transition. These results highlight the importance of considering both space and time in studies of attentional capture; the most effective stimulus is unique in both dimensions.

Adolescent↗

PubMed1997

Dual chamber pacing in hypertrophic obstructive cardiomyopathy: beneficial effect of atrioventricular junction ablation for optimal left ventricular capture and filling.

Clinical improvement with dual chamber pacing has largely been reported in patients suffering from hypertrophic obstructive cardiomyopathy and mainly attributed to the reduction of the subaortic pressure gradient. To be effective, pacing must induce a permanent and complete capture of the LV. In two patients of our collective, symptoms (angina and dyspnea NYHA Class III and/or syncopes) persisted or relapsed despite pacing. This was related to the inability to obtain full LV capture due to a too-short native PR interval. RF ablation of the AV junction was therefore performed in both patients, resulting in permanent AV block in one and prolonged PR interval up 310 ms in the second. Pacing was thereafter associated with an immediate and significant clinical improvement related to permanent LV capture, whatever the patient's activity. After RF ablation, the AV delay was set up to induce the best LV filling, as assessed by Doppler analysis of mitral flow. Our observations suggest that RF ablation or modification of the AV junction can be a successful procedure in some patients with residual or recurrent symptoms, when the latter result from a loss of capture or from the inability to program an AV delay that does not compromise the active component to LV filling. Doppler echocardiography is a simple and effective mean to assess the hemodynamic effect of AV interval modulation in this setting.

Angina Pectoris↗

PubMed2006

Preservation of ventricular capture by anodal stimulation after dislodgment of an epicardial electrode.

A 58-year-old man had a bipolar epicardial left ventricular (LV) implanted for cardiac resynchronization therapy after a failed transvenous approach. The system was programmed in an LV tip-right ventricular coil configuration, but during follow-up loss of LV capture with recurrence of symptoms occurred. Changing to an LV tip-LV ring configuration restored LV pacing through anodal capture. Loss of cathodal capture was caused by dislodgment of the cathodal electrode due to a broken fixation suture. Anodal capture was used to reinstall resynchronization therapy, which resulted in clinical improvement. There were no adverse effects from anodal stimulation in a follow-up period of 6 months.

Bundle-Branch Block↗

PubMed2005

A semiparametric method for estimating population size for capture-recapture experiments with random covariates in continuous time.

A semiparametric estimation procedure is proposed to model capture-recapture data with the aim of estimating the population size for a closed population. Individuals' covariates are possibly time dependent and missing at noncaptured times and may be measured with error. A set of estimating equations (EEs) based on covariate process and capture-recapture data is constructed to estimate the relevant parameters and the population size. These EEs can be solved by an algorithm similar to an EM algorithm. Simulation results show that the proposed procedures work better than the naive estimate. In some cases they are even better than "ideal" estimates, for which the true values of covariates are available for all captured subjects over the entire experimental period. We apply the method to a capture-recapture experiment on the bird species Prinia flaviventris in Hong Kong.

Algorithms↗

PubMed1991

A new capture test using conjugated peptides for the detection of HIV antibodies.

A new capture test utilizing conjugated peptides has been developed for the detection of antibodies elicited against HIV-1. Human sera diluted 1:1000 were incubated in ELISA plates precoated with protein G. The captured IgG were allowed to react with three synthetic peptides corresponding to the gp41 sequence (591-611) YLKDQQLLGIWGCSGKLICTT, the gp120 sequence (314-329) IRIQRGPGRAFVTIGK and the p27 sequence (182-198) EWRFDSRLAFHHVAREL. The peptides were used in the form of N-hydroxysuccinimido-biotin ovalbumin conjugates. Peroxidase-labelled streptavidin was used to detect antigen-antibody complexes. The sensitivity and specificity of detection of antibodies were analyzed with 40 HIV positive sera, 10 seroconverting sera and 21 normal human sera (NHS). The results were compared with a commercial indirect ELISA in which a single conjugated gp41 peptide was used as antigenic probe. This indirect ELISA recognized 100% of the HIV positive and the seroconverting sera. The new capture test using the gp41 conjugated peptide also recognized 100% of the HIV positive sera but was more specific since it gave no false positive results whereas the indirect test did. The gp120 and p27 conjugated peptides detected 35/40 (87.5%) and 31/40 (77.5%) of HIV positive sera respectively and also detected 9/10 (90%) and 10/10 (100%) of the seroconverting sera respectively, without any false positive results (0/21). The proposed new capture test is a very sensitive and specific assay for detecting HIV antibodies.

Amino Acid Sequence↗