SEARCH · PubMed Health

Results for “trajectory analysis”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources

PubMed1998

Essential spaces defined by NMR structure ensembles and molecular dynamics simulation show significant overlap.

Large concerted motions of proteins which span its "essential space," are an important component of protein dynamics. We investigate to what extent structure ensembles generated with standard structure calculation techniques such as simulated annealing can capture these motions by comparing them to long-time molecular dynamics (MD) trajectories. The motions are analyzed by principal component analysis and compared using inner products of eigenvectors of the respective covariance matrices. Two very different systems are studied, the beta-spectrin PH domain and the single-stranded DNA binding protein (ssDBP) from the filamentous phage Pf3. A comparison of the ensembles from NMR and MD shows significant overlap of the essential spaces, which in the case of ssDBP is extraordinarily high. The influence of variations in the specifications of distance restraints is investigated. We also study the influence of the selection criterion for the final structure ensemble on the definition of mobility. The results suggest a modified criterion that improves conformational sampling in terms of amplitudes of correlated motion.

Computer Simulation↗

PubMed1994

Seminal fluid analysis and sperm function testing.

The diagnosis of male infertility is a rapidly developing field of investigation. The traditional descriptive approach to semen analysis is still at the heart of the diagnostic workup of male patients and important advances have been made in the standardization of the procedures used to construct the conventional semen profile, as embodied in the WHO handbook. Significant improvements have also been made in the techniques used to assess the quality of sperm motility. While this was once an entirely subjective exercise, the introduction of CASA systems to take objective measurements of the trajectories of human spermatozoa has revolutionized this form of analysis. The speed and accuracy of such systems has permitted detailed analyses of the relationships between sperm movement and sperm function, which has greatly enhanced the diagnostic power of this form of descriptive analysis. Notwithstanding the importance of the descriptive approach to semen analysis, it has also been recognized that to achieve an accurate diagnosis of male infertility such criteria should be supplemented with assays designed to reveal the functional competence of the spermatozoa. Bioassays have therefore been developed to measure such functions as the penetration of cervical mucus, sperm-zona interaction, the acrosome reaction, and sperm-oocyte fusion. All of these assays have been shown to generate information predictive of the fertilizing potential of human spermatozoa in vivo and in vitro. Despite their diagnostic value, the time, expense, and expertise required to run such functional assays has meant that they have not been widely used by infertility specialists. These functional assays are of value, however, in fundamental studies designed to elucidate the biochemical basis of defective sperm function. The first fruits of this research effort are now beginning to appear in the identification of a number of cytoplasmic markers for defective sperm function and the realization that lipid peroxidation plays a key role in the etiology of male infertility. In the wake of these fundamental studies will flow a new generation of biochemical tests for the diagnosis of defective sperm function and, it is hoped, the development of rational therapies with which to treat this condition.

Female↗

PubMed1985

Protein normal-mode dynamics: trypsin inhibitor, crambin, ribonuclease and lysozyme.

We have developed a new method for modelling protein dynamics using normal-mode analysis in internal co-ordinates. This method, normal-mode dynamics, is particularly well suited for modelling collective motion, makes possible direct visualization of biologically interesting modes, and is complementary to the more time-consuming simulation of molecular dynamics trajectories. The essential assumption and limitation of normal-mode analysis is that the molecular potential energy varies quadratically. Our study starts with energy minimization of the X-ray co-ordinates with respect to the single-bond torsion angles. The main technical task is the calculation of second derivative matrices of kinetic and potential energy with respect to the torsion angle co-ordinates. These enter into a generalized eigenvalue problem, and the final eigenvalues and eigenvectors provide a complete description of the motion in the basic 0.1 to 10 picosecond range. Thermodynamic averages of amplitudes, fluctuations and correlations can be calculated efficiently using analytical formulae. The general method presented here is applied to four proteins, trypsin inhibitor, crambin, ribonuclease and lysozyme. When the resulting atomic motion is visualized by computer graphics, it is clear that the motion of each protein is collective with all atoms participating in each mode. The slow modes, with frequencies of below 10 cm-1 (a period of 3 ps), are the most interesting in that the motion in these modes is segmental. The root-mean-square atomic fluctuations, which are dominated by a few slow modes, agree well with experimental temperature factors (B values). The normal-mode dynamics of these four proteins have many features in common, although in the larger molecules, lysozyme and ribonuclease, there is low frequency domain motion about the active site.

Aprotinin↗

PubMed2026

Proteomic analysis identifies pathways related to immune dysregulation in patients with hematologic malignancies after COVID-19 infection.

Patients with hematologic malignancies (HMs) are particularly vulnerable to coronavirus disease 2019 (COVID-19) because of underlying immune dysfunction and treatment-related immunosuppression. However, proteomic features associated with different clinical trajectories in this population remain insufficiently characterized. We performed serum proteomic analysis in 40 HM patients with COVID-19 and 15 healthy controls. Compared with controls, HM patients showed impaired immune-related responses during the acute phase of COVID-19. Acute-phase proteomic patterns differed across outcome groups; however, because outcome groups were closely intertwined with initial COVID-19 severity, ICU admission, and systemic illness, and because multivariable adjustment was not performed due to the limited sample size, these patterns should be interpreted as severity- and outcome-associated profiles rather than independent trajectory-specific markers. Fatal cases showed evidence of dysregulated immune activation, whereas patients later classified as having long COVID exhibited broader suppression of immune-related pathways. In addition to immune alterations, pathways related to platelet activation and cardiac-related dysfunction were associated with adverse clinical trajectories. Enzyme-linked immunosorbent assay validation supported the association of selected proteins with outcome groups during acute infection. These findings provide a proteomic overview of COVID-19 in HM patients and offer a basis for future mechanistic studies and larger external validation cohorts.IMPORTANCEPatients with hematologic malignancies are highly vulnerable to severe coronavirus disease 2019 (COVID-19), acute death, and long COVID due to preexisting immune dysfunction. However, the proteomic signatures linked to adverse clinical trajectories remain poorly understood. Our serum proteomic study identifies distinct acute-phase immune profiles associated with different outcomes: broad immune suppression characterizes long COVID, while dysregulated immune activation is associated with fatal cases. Platelet activation and cardiac-related pathways are also linked to poor outcomes. These findings provide key molecular insights for this high-risk population, supporting future biomarker development, risk stratification, and targeted clinical management.CLINICAL TRIALSThis study is registered with ClinicalTrials.gov as NCT05683353.

Humans↗

PubMed2026

Interventions to improve school attendance: a systematic review and meta-analysis of evidence from randomised controlled trials.

BACKGROUND: Poor school attendance adversely affects youth behaviour and health trajectories. We reviewed and synthesised the evidence from randomised controlled trials (RCTs) on interventions to improve school attendance. METHODS: This systematic review and meta-analysis updates the Education Endowment Foundation (EEF) 2022 review on attendance interventions. We synthesised RCT data to inform recommendations. We searched ERIC (via EBSCOhost), PsycINFO, Web of Science and Google Scholar for publications 1 January 2020-16 October 2024 to identify attendance interventions delivered to students, parents/guardians or school staff. We also extracted and analysed RCTs identified in the EEF review. Two reviewers independently extracted data from published articles and assessed risk of bias and certainty of evidence (Grading of Recommendations Assessment, Development and Evaluation, GRADE assessment). We synthesised and meta-analysed data per our protocol (PROSPERO: CRD42024610037). RESULTS: We screened 9366 titles and abstracts and included 61 articles (2000-2024): 43 articles published 2020-2024 plus 18 articles from the previous review (2000-2020), reporting 57 trials of 54 interventions. Pooled mean difference and 95% CIs for days of school attended was 0.63 (-0.34 to 1.61), I2=64.0%, low certainty, for mentoring interventions and 0.43 (0.10 to 0.76), I2=91.9%, moderate certainty, for parental engagement interventions. Other intervention areas including targeted approaches, behavioural programmes and social-emotional interventions had smaller, heterogeneous evidence bases. Risk of bias was moderate-to-low in most trials. CONCLUSION: A large range of interventions exist to address the diverse causes of school absence. Parental engagement demonstrated a small positive effect on attendance, particularly among younger age groups. Most trials were from the USA; implementation and evaluation in other countries will inform effectiveness.

CHILD↗

PubMed2014

Persistent inflammation, immunosuppression, and catabolism syndrome after severe blunt trauma.

BACKGROUND: We recently proffered that a new syndrome persistent inflammation, immunosuppression, and catabolism syndrome (PICS) has replaced late multiple-organ failure as a predominant phenotype of chronic critical illness. Our goal was to validate this by determining whether severely injured trauma patients with complicated outcomes have evidence of PICS at the genomic level. METHODS: We performed a secondary analysis of the Inflammation and Host Response to Injury database of adults with severe blunt trauma. Patients were classified into complicated, intermediate, and uncomplicated clinical trajectories. Existing genomic microarray data were compared between cohorts using Ingenuity Pathways Analysis. Epidemiologic data and outcomes were also analyzed between cohorts on admission, Day 7, and Day 14. RESULTS: Complicated patients were older, were sicker, and required increased ventilator days compared with the intermediate/uncomplicated patients. They also had persistent leukocytosis as well as low lymphocyte and albumin levels compared with uncomplicated patients. Total white blood cell leukocyte analysis in complicated patients showed that overall genome-wide expression patterns and those patterns on Days 7 and 14 were more aberrant from control subjects than were patterns from uncomplicated patients. Complicated patients also had significant down-regulation of adaptive immunity and up-regulation of inflammatory genes on Days 7 and 14 (vs. magnitude in fold change compared with control and in magnitude compared with uncomplicated patients). On Day 7, complicated patients had significant changes in functional pathways involved in the suppression of myeloid cell differentiation, increased inflammation, decreased chemotaxis, and defective innate immunity compared with uncomplicated patients and controls. Subset analysis of monocyte, neutrophil, and T-cells supported these findings. CONCLUSION: Genomic analysis of patients with complicated clinical outcomes exhibit persistent genomic expression changes consistent with defects in the adaptive immune response and increased inflammation. Clinical data showed persistent inflammation, immunosuppression, and protein depletion. Overall, the data support the hypothesis that patients with complicated clinical outcomes are exhibiting PICS. LEVEL OF EVIDENCE: Epidemiologic study, level III.

Adolescent↗

PubMed2000

Integrating person-centered and variable-centered analyses: growth mixture modeling with latent trajectory classes.

BACKGROUND: Many alcohol research questions require methods that take a person-centered approach because the interest is in finding heterogeneous groups of individuals, such as those who are susceptible to alcohol dependence and those who are not. A person-centered focus also is useful with longitudinal data to represent heterogeneity in developmental trajectories. In alcohol, drug, and mental health research the recognition of heterogeneity has led to theories of multiple developmental pathways. METHODS: This paper gives a brief overview of new methods that integrate variable- and person-centered analyses. Methods discussed include latent class analysis, latent transition analysis, latent class growth analysis, growth mixture modeling, and general growth mixture modeling. These methods are presented in a general latent variable modeling framework that expands traditional latent variable modeling by including not only continuous latent variables but also categorical latent variables. RESULTS: Four examples that use the National Longitudinal Survey of Youth (NLSY) data are presented to illustrate latent class analysis, latent class growth analysis, growth mixture modeling, and general growth mixture modeling. Latent class analysis of antisocial behavior found four classes. Four heavy drinking trajectory classes were found. The relationship between the latent classes and background variables and consequences was studied. CONCLUSIONS: Person-centered and variable-centered analyses typically have been seen as different activities that use different types of models and software. This paper gives a brief overview of new methods that integrate variable- and person-centered analyses. The general framework makes it possible to combine these models and to study new models serving as a stimulus for asking research questions that have both person- and variable-centered aspects.

Adolescent↗

PubMed2026

Dissecting fluctuating selection: A unified population and quantitative genetics framework.

One of the longstanding debates in evolutionary biology is the effect of fluctuating selection on genetic changes in populations. However, the extent to which these periodic forces influence organisms at both genomic and phenotypic levels remains unclear. Despite the compelling evidence of fluctuating selection from recent studies, there is a disconnect between empirical and theoretical findings concerning the underlying mechanisms due to the limited evidence regarding the scale and processes that generate genome-wide oscillations. This study aims to elucidate how both genetic factors (e.g. heritability, number of causative loci) and ecological factors (e.g. season length, the difference in the phenotypic optima between seasons, population size dynamics) drive fluctuating selection and to identify the parameters that produce consistent oscillatory patterns. We developed a modeling framework integrating quantitative and population genetics to simulate a population under various selection regimes. We applied spectral analysis to detect periodicity, indicating cyclical selective environments. Our simulations highlight the conditions sustaining oscillations in allele frequencies over time. Spectral analysis successfully identifies the periodic patterns from allele frequency trajectories, even under highly complex selection regimes. Not only does our study clarify the conditions that yield oscillatory behaviors, but these parameters can also potentially be estimated in natural populations, providing a possibility of empirically testing these models.

Fluctuating selection↗

PubMed2026

Dissecting fluctuating selection: A unified population and quantitative genetics framework.

Fluctuating selection↗

PubMed2005

[Particle trajectory model desulfurization spray tower used in numerical simulation of flue gas].

The commercial computational fluid dynamics (CFD) software FLUENT is used to predict the two-phase flow in a flue gas desulfurization (FGD) spray tower. The Euler-Lagrange method is used, in which the gas flow is described with standard k-epsilon turbulence model, and the motion of the liquid droplets is described with the particle trajectory model. The procedure of model definition, including force analysis of liquid particle, gas turbulent dispersion and the gas-liquid coupling method, is presented. The results show that the uniformity of axial gas velocity in the spray tower is satisfactory, and the hollow spray nozzle used in the tower can efficiently prevent short-circuiting of the flue gas. The concentration of liquid droplets in the central region is higher than near the wall, and this problem can be solved by optimizing the arrangement of the spray nozzles near the wall. Model predictions for particle trajectory are shown to be in good agreement with experimental results, and the particle trajectory model can predict the two-phase flow in the spray tower successfully.

Air Movements↗

PubMedDate not supplied

The potential shortcomings of measuring hyperactivated motility by computer-aided sperm analysis when sperm motion is multiphasic.

This paper was written from the standpoint that computer-aided sperm analysis (CASA) instruments, which capture a 'snapshot' of sperm trajectories in order to generate their data, may provide a poor measure of hyperactivated motility in a sperm population where hyperactivation is multiphasic in nature. To illustrate this point, a series of theoretical sperm populations were constructed which varied subtly but significantly in the nature of the hyperactivated behaviour expressed by spermatozoa. The parameters which were manipulated were: (i) the number of hyperactivated phases exhibited within a given period of time; (ii) the duration of these phases; and (iii) proportion of spermatozoa within the population which exhibited hyperactivated phases. These populations were then subject to an analysis in which snapshots of sperm motion were examined to determine the percentage of hyperactivated spermatozoa for that population. The results indicated that whilst this snapshot approach to quantifying hyperactivation could provide a figure for the percentage of hyperactivated spermatozoa within the sample window, this often inaccurately described the underlying behaviour of the population. Since there is very likely to be a significant amount of biological information contained within the nature of multiphasic behaviour, this paper has argued that this aspect of snapshot analysis is one which requires serious consideration by CASA manufacturers and medical researchers.

Diagnosis, Computer-Assisted↗

PubMed2004

Health care communication issues in multiple sclerosis: an interpretive description.

Communication between persons with chronic illness and their professional health care providers is a critical element of appropriate health care. As the field of health care communication evolves, it becomes apparent that aspects of the illness experience shared by those affected by specific diseases might be a source of particular insight into what constitutes effective or appropriate communications. This interpretive description of health care communication issues in multiple sclerosis was based on qualitative secondary analysis of a set of in-depth interviews and focus groups conducted with 12 persons with longstanding MS experience. Analysis of their accounts illustrates an intricate interplay between common features within the disease trajectory and the communications that are perceived as helpful or unhelpful to living well with this chronic illness. From the analysis of these findings, the authors draw interpretations regarding what might be considered communication competencies for those who care for patients with this disease.

Adult↗

PubMed2005

Ligand-free and -bound structures of the binding protein (LivJ) of the Escherichia coli ABC leucine/isoleucine/valine transport system: trajectory and dynamics of the interdomain rotation and ligand specificity.

The leucine/isoleucine/valine-binding protein (LIVBP or LivJ) serves as the primary high-affinity receptor of the Escherichia coli ABC-type transporter for the three aliphatic amino acids. The first structure of LIVBP determined previously without bound ligand showed a molecule comprised of two domains which are far apart and bisected by a wide open, solvent-accessible cleft. Here we report the crystal structures of another ligand-free state and three complexes with the aliphatic amino acids. In the present ligand-free structure, the two domains are farther apart. In the three very similar complex structures, the two domains are in close proximity, and each desolvated ligand is completely engulfed in the cleft and bound by both domains. The two different ligand-free structures, combined with those of the very similar ligand-bound structures, indicate the trajectory and backbone torsion angle changes of the hinges that accompany domain closure and play crucial functional roles. The amino acids are bound by polar and nonpolar interactions, occurring predominantly in one domain. Consistent with the protein specificity, the aliphatic side chains of the ligands lie in a hydrophobic pocket fully formed following domain or cleft closure. Comparison of the structures of LIVBP with several different binding proteins indicates no correlations between the magnitudes of the hinge-bending angles and the protein masses, the ligand sizes, or the number of segments connecting the two domains. Results of normal-mode analysis and molecular dynamics simulations are consistent with the trajectory and intrinsic flexibility of the interdomain hinges and the dominance of one domain in ligand binding in the open state.

ATP-Binding Cassette Transporters↗

PubMed1982

[The economic and social effects of rheumatoid pelvis-spondylitis].

The purpose of the research reported in this article was to reconstruct a typology of the various courses taken by rheumatoid pelvis-spondylitis based on medical evidence and then to assess the economic and social consequences of the illness generally and for each of the groups brought out by our research. The investigation dealt with 172 patients who had either been hospitalized or had consulted outside physicians or community clinics in the Nord-Pas-de-Calais Region or Paris. Between January 1978 and May 1979, these patients were asked to report to the places where they had had their consultations. Using the information in their medical records, the patients' statements and additional examinations, the case histories were pieced together, the patients' current condition was described and the typology of the disease was constructed. Then we collected the economic data and the disease's costs were reconstructed (medical costs, cost of losses in output, costs under the heading of either the individual or the community). Finally, data of a psychosocial nature made it possible to clarify the patients' understanding of the disease according to various criteria (particularly the different forms taken by the disease). The analysis of clinical, radiological, biological investigations makes it possible to bring out three trajectories of the disease. We have brought to light medical and economic costs of the disease clearly differentiated according to the trajectories of the illness. We have also underlined the role played by social factors in determining how the disease is perceived. Finally, the analysis of the effectiveness of known therapies shows that these therapies aim above all at easing the pain and limiting the stiffness and that a delay in applying these therapies does not seem decisive for the seriousness and the progression of the illness.

Adult↗

PubMed1999

Timing the Selection of Information During Rhythmic Catching.

Catching a ball requires that information be available close to the catch but early enough for prospective or corrective control. In the present experiment, 6 participants were asked to throw and catch a ball continuously for 1 min while wearing liquid-crystal goggles that restricted viewing to specific amounts of time at specific intervals. Participants were free to select the information by varying the frequency and phasing of throwing relative to the goggles. Video analysis revealed that they elected a frequency of throwing that matched the goggle frequency and chose to view the ball at or around its zenith. Earlier portions of the ball's trajectory were viewed as the goggle frequency increased. Despite variations in the viewing location, participants elected to view the ball on average 365 ms before the catch. Analysis of the hand's trajectory further revealed that the time interval (M = 82 ms) between the ball's zenith and the initiation of the final motion of the hand toward the catch did not vary as a function of the frequency of throwing. The authors conclude that the timing constraints imposed by the hand's movement are the basis for the selection of information for catching.

Journal Article↗

PubMed2000

Head-neck finite element model for motor vehicle inertial impact: material sensitivity analysis.

The aim of this study was to conduct a material sensitivity analysis using a head-neck finite element model (FEM). The model included the skull, C1-T1 vertebrae, intervertebral discs, facet joints, and biomechanically relevant ligaments. Poisson's ratio and elastic modulus of the head-neck components were varied. The loading condition included the impact load applied to the first thoracic vertebra. Commercially available software (LS-DYNA) was used for the analysis. Head angle versus time, head center of gravity trajectory, and head center of gravity angular acceleration responses were computed. In general, the variation of elastic modulus had a higher effect on the response compared to variation of Poisson's ratio. As the elastic modulus was increased, the head angle and angular acceleration increased. The present findings form a first step in the study of computational biomechanics of vehicular-related trauma.

Acceleration↗

PubMed1990

Juvenile delinquency and attention deficit disorder: boys' developmental trajectories from age 3 to age 15.

This article describes a longitudinal analysis of the behavior of a birth cohort of 435 boys. 4 groups were defined at age 13 on the basis of both self-reported delinquent behavior and professional diagnosis of Attention Deficit Disorder: ADD + delinquent, ADD only, delinquent only, and nondisordered. Biennial correlates of delinquency (antisocial behavior problems, verbal intelligence, reading difficulty, and family adversity) were traced across childhood. The ADD + delinquent boys consistently fared the worst on the assessments of family adversity, verbal intelligence, and reading. Their antisocial behavior began before school age, escalated at school entry, and persisted into adolescence. The ADD-only boys had normal family, intelligence, and reading scores, and showed only mild antisocial behavior in middle childhood. The delinquent-only boys showed no early risk from family, low intelligence, or reading deficit, and remained relatively free of conduct problems until they initiated delinquency at age 13. Persistence of criminal offending beyond adolescence is predicted for the ADD + delinquent boys.

Achievement↗

PubMed2004

Prediction of alcohol-related harm from controlled drinking strategies and alcohol consumption trajectories.

AIMS: To establish predictors of age 21 alcohol-related harm from prior drinking patterns, current levels of alcohol consumption and use of controlled drinking strategies. PARTICIPANTS: One thousand, five hundred and ninety-six students recruited from an initial sample of 3300 during their final year of high school in 1993. DESIGN: Longitudinal follow-up across five waves of data collection. SETTING: Post high school in Victoria, Australia. MEASUREMENTS: Self-administered surveys examining a range of health behaviours, including alcohol consumption patterns and related behaviour. FINDINGS: Drinking behaviours at age 21 were found to be strongly predicted by drinking trajectories established through the transition from high school. Multivariate regression analysis revealed that alcohol-related harms at age 21 were reduced where current levels of alcohol use fell within limits recommended in Australian national guidelines. After controlling for this effect it was found that the range of strategies employed by participants to control alcohol use maintained a small protective influence. Post-high-school drinking trajectories continued to demonstrate a significant effect after controlling for current behaviours. FINDINGS: revealed that over one quarter of males and females drank alcohol, but on a less-than-weekly basis. This pattern of alcohol use demonstrated considerable stability through the post-school transition and was associated with a low level of subsequent harm at age 21. CONCLUSIONS: Future research should investigate whether encouraging more Australian adolescents to drink alcohol on a less-than-weekly basis may be a practical intervention target for reducing alcohol-related harms.

Adolescent↗