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Results for “trajectory analysis”

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PubMed2002

Dual-wavelength fluorescent speckle microscopy reveals coupling of microtubule and actin movements in migrating cells.

Interactions between microtubules (MTs) and filamentous actin (f-actin) are involved in directed cell locomotion, but are poorly understood. To test the hypothesis that MTs and f-actin associate with one another and affect each other's organization and dynamics, we performed time-lapse dual-wavelength spinning-disk confocal fluorescent speckle microscopy (FSM) of MTs and f-actin in migrating newt lung epithelial cells. F-actin exhibited four zones of dynamic behavior: rapid retrograde flow in the lamellipodium, slow retrograde flow in the lamellum, anterograde flow in the cell body, and no movement in the convergence zone between the lamellum and cell body. Speckle analysis showed that MTs moved at the same trajectory and velocity as f-actin in the cell body and lamellum, but not in the lamellipodium or convergence zone. MTs grew along f-actin bundles, and quiescent MT ends moved in association with f-actin bundles. These results show that the movement and organization of f-actin has a profound effect on the dynamic organization of MTs in migrating cells, and suggest that MTs and f-actin bind to one another in vivo.

Actins↗

PubMed1996

Positive and negative symptoms: is their change related?

The objective of this study was to investigate the relationship between change in positive and negative symptoms over time during haloperidol treatment. Subjects were 178 acutely exacerbating chronic schizophrenia patients participating in a clinical trial of haloperidol. Positive and negative symptoms were measured by the positive and negative symptom clusters of the Brief Psychiatric Rating Scale and by the Scales for the Assessment of Positive and Negative Symptoms. Hierarchical linear model analysis was used to estimate symptom-change trajectories of positive and negative symptoms over time in individual patients and to investigate the inter-relationship between these trajectories. Results indicate that positive and negative symptom-change trajectories over time were closely associated. This result did not depend on extrapyramidal side effects, depression, or the baseline balance of positive and negative symptoms. Thus, our study suggests that in acutely exacerbating schizophrenia patients, changes of positive and negative symptoms over time are related during the initial phase of the pharmacological treatment. This relationship may not extend to other treatment paradigms or beyond the initial phase of the treatment.

Adult↗

PubMed1982

Differences in the movement of morphologically normal and abnormal human seminal spermatozoa.

Movement characteristics of human spermatozoa in fresh semen from 7 fertile men were studied using high-speed cinemicrography. Parameters that measured sperm swimming speed, flagellar beat frequency, flagellar beat shape, and the straightness of the swimming trajectory were obtained from frame-by-frame analysis of the cine films. In addition, each spermatozoon sampled for movement was also classified as being morphologically normal or abnormal, the latter being subdivided into the categories amorphous head, amorphous midpiece, elongated tapering head, piriform tapering head, megalocephalic and microcephalic. The morphological classification procedure involved direct reference of the sperm image on the screen of the cine film analysis console to metric morphological standards. Statistical analysis of the data investigated whether spermatozoa of different morphological types, as well as from different men, exhibited similar or dissimilar movement characteristics. It was found that morphologically normal spermatozoa swam faster and straighter, and exhibited higher beat frequencies than did morphologically abnormal sperm. These distinctions were most pronounced for spermatozoa with elongated or piriform tapering heads or amorphous midpieces.

Humans↗

PubMed2025

An intermediate activation state primes Langerhans cell migration from the epidermis.

Langerhans cells (LCs) are a specialized subset of dendritic cells in the epidermis, forming a dense network that acts as a frontline defense through immune surveillance. Upon antigen uptake, LCs become activated and orchestrate subsequent immune responses by migrating to lymphatics. However, how transcriptional programs are regulated during activation and how LCs behave in vivo during this transition remain poorly understood. Here, we combine single-cell transcriptomic analysis and intravital imaging to reconstruct the activation trajectory of epidermal LCs. We present a high-resolution single-cell transcriptomic dataset of over 22,000 high-quality epidermal LCs in both homeostatic and injured conditions. We define specific LC subpopulations representing sequential activation stages, characterized at the level of pathways and transcription factors. Notably, we identify a distinct intermediate state that precedes their migration. Integrating our data with an external dataset from homeostatic and injured skin reveals that wound-specific, WNT-modulated fibroblasts are the primary source of C3, the central component of the complement cascade. Intravital imaging of C3-deficient mice demonstrated that C3 is essential for effective recruitment of activated LCs to wound sites. Together, our findings uncover a novel population of activated epidermal LCs and highlight complement signaling as a critical mediator of LC recruitment during skin injury.

Activation↗

PubMed2000

Tunneling transverse to a magnetic field and its occurrence in correlated 2D electron systems.

We investigate tunneling decay in a magnetic field. Because of broken time-reversal symmetry, the standard WKB technique does not apply. The decay rate and the outcoming wave packet are found from the analysis of the set of the particle Hamiltonian trajectories and its singularities in complex space. The results are applied to tunneling from a strongly correlated 2D electron system in a magnetic field parallel to the layer. We show in a simple model that electron correlations strongly affect the tunneling rate.

Journal Article↗

PubMed2003

Complete identification of alkali sites in ion conducting lithium silicate glasses: a computer study of ion dynamics.

The available sites for ions in a typical disordered ionic conductor are determined. For this purpose we devised a straightforward algorithm which via cluster analysis identifies these sites from long time ionic trajectories below the glass transition. This is exemplified for a lithium silicate glass (Li2O)(x)(SiO2)((1-x)) for x=0.5 and x=0.1. We find for both concentrations that the number of sites is only slightly bigger than the number of ions. This result suggests a theoretical description of the dynamics in terms of mobile vacancies as most appropriate. Furthermore, identification of the ionic sites allows one to obtain detailed characteristics of the ionic motion, e.g., quantification of correlated forward-backward jumps.

Journal Article↗

PubMed2026

Divergent microbial preludes to necrotising enterocolitis defined by gut phages and bacterial resistomes.

BACKGROUND: Translating microbiome correlations into robust predictive features for complex gut disorders remains elusive, partly due to oversimplified models of pathogenesis and neglect of the virome, a key player in microbial ecosystems. Necrotising enterocolitis (NEC), a devastating disease of preterm infants with no reliable clinical predictors, exemplifies this challenge. OBJECTIVE: To determine the predictive potential of the gut prophageome and polymicrobial aetiologies for NEC. DESIGN: We applied integrated metagenomic and metatranscriptomic analyses and machine learning to 1825 longitudinal stool samples from 43 preterm infants who later developed NEC and 86 gestational age-matched and birthweight-matched controls across three US hospitals. We characterised gut prophageome acquisitions and their association with clinical exposures, including antibiotics, diet and pharmacotherapies. To predict NEC risk, we integrated pre-onset prophageome, antibacterial resistome and bacteriome profiles with neonatal pathology, stratifying the cohort by disease onset timing (early: ≤40 days; late: >40 days) for separate analysis. RESULTS: NEC cases exhibited distinct viral diversity trajectories before disease onset. Early-onset NEC was best predicted by phage-bacterial interaction signatures (75% accuracy, 81% sensitivity). Metatranscriptomics revealed increased phage DNA abundance with low gene expression, suggesting a lysogenic lifestyle that may stabilise pathobionts. These phages encode metabolic genes potentially enhancing pathobiont resilience. Late-onset NEC was best predicted by antibacterial resistome profiles (83% accuracy). CONCLUSION: The gut prophageome serves as both a source of pre-symptomatic predictive signals and an active modulator of NEC pathogenesis, with distinct microbial mechanisms driving early-onset and late-onset disease. These polymicrobial etiologies inform strategies for early detection, risk stratification and the development of microbiome-targeted preventive and therapeutic interventions.

BIOMARKERS↗

PubMed1997

Mechanisms by which cell geometry controls repetitive impulse firing in retinal ganglion cells.

Models for generating repetitive impulse activity were developed based on multicompartmental representations of ganglion cell morphology in the amphibian retina. Each model includes five nonlinear ion channels and one linear (leakage) channel. Compartmental distribution of ion channel type and density was designed to simulate whole cell recording experiments carried out in the intact retina-eyecup preparation. Correspondence between the model and physiology emphasized channel-specific details in the impulse waveform, based on phase plot analysis, frequency versus current (F/I) properties, and interspike trajectories for current injected into the soma, as well as the ability to conduct impulses in both orthodromic and antidromic directions. Two general types of model are developed, including equivalent cylinder representations and more realistic compartmentalizations of dendritic morphology. These multicompartmental models include representations for dendritic trees, soma, axon hillock, a thin axonal segment, and axon distal to thin segment. A large number of compartments (</=800) representing a single neuron were employed to ensure that maximum voltage differences between neighboring compartments during the steepest rates of change of membrane potential were acceptably small. Leakage conductance varied from 3 to 8 microS/cm2. The results establish that intercompartmental currents, due to inhomogeneous morphology, dominate membrane currents in the interspike intervals and thus play a major role in determining the impulse spacing and the information carried by impulse trains. Variations in input resistance are far less important than the degree to which ion channels are present in the dendritic compartments for the regulation of F/I properties. Cell geometry, including the thin axonal segment, places significant constraints on the location of ion channels required to support impulse initiation and propagation in both the ortho- and antidromic directions. The site of impulse initiation varies greatly and depends on the stimulus magnitude. Models that conform to physiological constraints also show irregular firing, particularly for near threshold stimulation of the soma, due to multiple sites of impulse initiation. Such behavior could represent an asset to the cells for conveying information under conditions of low contrast stimulation. Multiple spike initiation zones also can provide retinal ganglion cells with a variety of response characteristics, including spike doublets, depending on the level of cell activation. Increasing the diameter of the dendritic equivalent cylinder reduces the impulse frequency (F/I) response. Over a restricted range of ion channel densities in the dendritic tree, phase locking between dendritic membrane oscillations and somatic spiking can occur with dendritic stimulation, and mathematical chaos can be demonstrated when sufficiently thin dendritic processes are present. We conclude that cell morphology is the primary factor in determining firing patterns and the impulse frequency response of a given cell and that differences in channel density distribution across a population of cells plays, at most, a secondary role in this function. This conclusion applies to both synaptic activation and electrode stimulation of the soma.

Animals↗

PubMed2005

Reaching in children with and without developmental coordination disorder under normal and perturbed vision.

The aim of this study is to describe the reaching action of children with developmental coordination disorder (DCD) and to investigate whether their use of visual feedback during the time course of this action differs from that of normally developing children. Fifty-two children subdivided into 2 age bands (7-8 and 9-10 years) within 2 groups (with and without DCD) participated in this experiment. They were asked to reach for a target positioned either ipsilaterally or contralaterally to the reaching hand in 2 visual conditions: a condition where vision was unrestrained (normal vision) and a condition where they wore glasses with prismatic lenses (perturbed vision). An analysis of the experimental data indicates that the trajectories followed by the DCD group were longer and more curved than those of the control group. Further, the deceleration times were longer for the DCD group than for the normally developing children. The introduction of the prismatic lenses supports the idea that the use of visual feedback by children with DCD may be different from that in children without DCD.

Age Factors↗

PubMed1996

Zebrafish mutations affecting retinotectal axon pathfinding.

We have isolated mutants in the zebrafish Danio rerio that have defects in axonal connectivity between the retina and tectum. 5-day-old fish larvae were screened by labeling retinal ganglion cells with DiI and DiO and observing their axonal projections to and on the tectum. 82 mutations, representing 13 complementation groups and 6 single allele loci, were found that have defects in retinal ganglion cell axon pathfinding to the tectum. These pathfinding genes fall into five classes, based on the location of pathfinding errors between eye and tectum. In Class I mutant larvae (belladonna, detour, you-too, iguana, umleitung, blowout) axons grow directly to the ipsilateral tectal lobe after leaving the eye. Class II mutant larvae (chameleon, bashful) have ipsilaterally projecting axons and, in addition, pathfinding mistakes are seen within the eye. In Class III mutant larvae (esrom, tilsit, tofu) fewer axons than normal cross the midline, but some axons do reach the contralateral tectal lobe. Class IV mutant larvae (boxer, dackel, pinscher) have defects in axon sorting after the midline and retinal axons occasionally make further pathfinding errors upon reaching the contralateral tectal lobe. Finally, Class V mutant larvae (bashful, grumpy, sleepy, cyclops, astray) have anterior-posterior axon trajectory defects at or after the midline. The analysis of these mutants supports several conclusions about the mechanisms of retinal axon pathfinding from eye to tectum. A series of sequential cues seems to guide retinal axons to the contralateral tectal lobe. Pre-existing axon tracts seem not to be necessary to guide axons across the midline. The midline itself seems to play a central role in guiding retinal axons. Axons in nearby regions of the brain seem to use different cues to cross the ventral midline. Mutant effects are not all-or-none, as misrouted axons may reach their target, and if they do, they project normally on the tectum. The retinotectal pathfinding mutants reveal important choice points encountered by neuronal growth cones as they navigate between eye and tectum.

Animals↗

PubMed2006

Differential geometry of normalized Stokes vector trajectories in anisotropic media.

Trajectory of the normalized Stokes vector on the Poincaré sphere corresponding to light propagation in anisotropic tissues with birefringence and biattenuance is derived. Analytic expressions are determined from the Serret-Frenet formulas and derivatives of arc length for five quantities including the tangent, normal, and binormal vectors with curvature and torsion. Depth variation of curvature and torsion of normalized Stokes vector trajectories corresponding to light propagating in rodent tail tendon are given. Use of analytic expressions for depth variation of curvature and torsion of the normalized Stokes vector trajectories on the Poincaré sphere is discussed for analysis of polarization-sensitive optical coherence tomography data recorded from anisotropic biological tissues with birefringence and biattenuance.

Algorithms↗

PubMed2005

Three Prochlorococcus cyanophage genomes: signature features and ecological interpretations.

The oceanic cyanobacteria Prochlorococcus are globally important, ecologically diverse primary producers. It is thought that their viruses (phages) mediate population sizes and affect the evolutionary trajectories of their hosts. Here we present an analysis of genomes from three Prochlorococcus phages: a podovirus and two myoviruses. The morphology, overall genome features, and gene content of these phages suggest that they are quite similar to T7-like (P-SSP7) and T4-like (P-SSM2 and P-SSM4) phages. Using the existing phage taxonomic framework as a guideline, we examined genome sequences to establish "core" genes for each phage group. We found the podovirus contained 15 of 26 core T7-like genes and the two myoviruses contained 43 and 42 of 75 core T4-like genes. In addition to these core genes, each genome contains a significant number of "cyanobacterial" genes, i.e., genes with significant best BLAST hits to genes found in cyanobacteria. Some of these, we speculate, represent "signature" cyanophage genes. For example, all three phage genomes contain photosynthetic genes (psbA, hliP) that are thought to help maintain host photosynthetic activity during infection, as well as an aldolase family gene (talC) that could facilitate alternative routes of carbon metabolism during infection. The podovirus genome also contains an integrase gene (int) and other features that suggest it is capable of integrating into its host. If indeed it is, this would be unprecedented among cultured T7-like phages or marine cyanophages and would have significant evolutionary and ecological implications for phage and host. Further, both myoviruses contain phosphate-inducible genes (phoH and pstS) that are likely to be important for phage and host responses to phosphate stress, a commonly limiting nutrient in marine systems. Thus, these marine cyanophages appear to be variations of two well-known phages-T7 and T4-but contain genes that, if functional, reflect adaptations for infection of photosynthetic hosts in low-nutrient oceanic environments.

Bacteriophage T7↗

PubMed2005

Immunofluorescence detection of clustered gamma-H2AX foci induced by HZE-particle radiation.

We studied the spatial and temporal distributions of foci of the phosphorylated form of the histone protein H2AX (gamma-H2AX), which is known to be activated by double-strand breaks after irradiation of human fibroblast cells with high-energy silicon (54 keV/microm) and iron (176 keV/microm) ions. Here we present data obtained with the ion path parallel to a monolayer of human fibroblast cells that leads to gamma-H2AX aggregates in the shape of streaks stretching over several micrometers in an x/y plane, thus enabling the analysis of the fluorescence distributions along the ion trajectories. Qualitative analyses of these distributions provide insights into DNA damage processing kinetics for high charge and energy (HZE) ions, including evidence of increased clustering of DNA damage and slower processing with increasing LET.

Cells, Cultured↗

PubMed2026

Sex-Dependent Microbial and Host Profiles Following Fecal Microbiota and Bifidobacterium longum Treatment in Stress-Induced Gut Dysbiosis.

BACKGROUND/AIMS: Irritable bowel syndrome (IBS) is a chronic functional gastrointestinal disorder influenced by stress, microbial dysbiosis, and immune activation. Microbiota-directed therapies, including fecal microbiota transplantation and probiotics, show promise, but their sex-specific effects remain unclear. We compared the therapeutic effects of lyophilized fecal microbiota (LFM) with Bifidobacterium longum BBH016 in male and female Wistar rats subjected to repeated water avoidance stress. METHODS: Fecal pellet output (FPO), colonic mast cell infiltration, and fecal short-chain fatty acids were measured. Gut microbial composition and function were analyzed by 16S rRNA sequencing and Kyoto Encyclopedia of Genes and Genomes pathway prediction. RESULTS: Both interventions significantly reduced FPO and mast cell infiltration in males but had less pronounced effects in females. Microbiota analyses revealed sex-dependent responses, with distinct microbial trajectories in each treatment group. Using linear discriminant analysis effect size, we identified seven key taxa with treatment- or sex-specific enrichment. Alistipes onderdonkii and Bacteroides uniformis consistently increased in both LFM- and B. longum-treated groups, regardless of sex. Bacteroides finegoldii and Barnesiella intestinihominis were specifically enriched in the LFM group. In males, Blautia faecis and Fusicatenibacter saccharivorans were enriched following the interventions, whereas Parabacteroides goldsteinii appeared exclusively in stressed males. Functional predictions revealed the enrichment of estrogen signaling and bile acid pathways in males and the attenuation of proinflammatory pathways in females following LFM. Correlations between microbial taxa and host outcomes were predominantly observed in male rats. CONCLUSIONS: These findings highlight sex-specific microbial and host responses to microbiota-targeted therapies in a stress-induced IBS model, emphasizing sex as a biological variable in designing personalized microbiome-based treatments.

Animals↗

PubMedDate not supplied

[The grounded theory as a methodological alternative for nursing research].

This study presents a method of interpretative and systematic research with appliance to the development of studies in nursing called "the grounded theory", whose theoretical support is the symbolic interactionism. The purpose of the paper is to describe the grounded theory as an alternative methodology for the construction of knowledge in nursing. The study highlights four topics: the basic principle, the basic concepts, the trajectory of the method and the process of analysis of the data. We conclude that the systematization of data and its interpretation, based on social actors' experience, constitute strong subsidies to generate theories through this research tool.

Nursing Research↗

PubMed2003

The application of computer posturography in psychological diagnosis.

BACKGROUND: We analyzed assessment of equilibrium system efficiency versus organic test performance and dependence on functional aspect of cognitive and psychomotor functions. MATERIAL/METHODS: A population of 250 persons from 15 to 65 years of age was examined. Measurements of the sense of balance were carried out by means of computer posturograph. Three parameters describing the posturographic trajectory (its variability over time) were selected for analysis: the resultant sway coefficient, average, and maximum sway speeds. CNS function was assessed against the background of tests results from the psychoorganic triad. Cognitive and psychomotor functions were evaluated on the basis of the Raven test, Digital Symbol test, Poppelreuter test, Toulous - Pieron test, and the cross-type apparatus, as well as measurement of direct reaction to auditory and visual stimuli. RESULTS: The results showed decreased efficiency of the equilibrium system in persons with poorer performance on organic tests and a lower level of cognitive and psychomotor functions. The analyzed parameters of the equilibrium system demonstrated a higher degree of dependence on the degree of organic alteration than on the location of defects within the central nervous system. CONCLUSIONS: The resultant sway coefficient proved to be the most useful parameter of equilibrium for diagnostic purposes.

Adolescent↗

PubMedDate not supplied

[Motility of polymorphonuclear leukocytes in malnutrition].

Random polymorphonuclear granulocytes motility has been studied in malnourished children, aged between one month and one year. A technique, which allowed to observe trajectories of individual cells has been applied. An analysis included the measurements of cells centres position. Results have indicated, that the average cell velocity (one-minute translocation) does not differ in malnutrition from that seen during convalescence period. However, distribution of cell translocation values have been statistically significantly different.

Cell Movement↗

PubMed1981

Methods for comparing the mortality experience of heterogeneous populations.

Methods are presented which produce Maximum Likelihood Estimates (MLE) of the degree of heterogeneity in individual mortality risks under a variety of assumptions about the age trajectory of those mortality risks. With these estimates of the degree of population heterogeneity it is possible to adjust comparisons of mortality risks across populations for the effects of population heterogeneity, differential mortality selection, and different age trajectories of the force of mortality. These methods are demonstrated by applying a variety of standard assumptions about the age trajectory of the force of mortality to the analysis of a broad range of cohort mortality data for the U.S. and Swedish populations. The estimates of the degree of heterogeneity, produced under all of the selected force of mortality models, consistently indicated a considerable degree of heterogeneity in mortality risks.

Adult↗