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At least 667 records · Page 37Linked to original sources
PubMed2005

The course of depressive symptoms in men from early adolescence to young adulthood: identifying latent trajectories and early predictors.

Heterogeneity in the longitudinal course of depressive symptoms was studied through the use of general growth mixture modeling for young men in the Oregon Youth Study (N=206), who ranged in age from 15 to 24 years. Four trajectory classes were identified: the very-low, the moderate-decreasing, the high-decreasing, and the high-persistent classes. The 3 lowest classes differed primarily quantitatively with the initial level or mean level across time being the major determinant of class differences, whereas the high-persistent class appeared qualitatively different in terms of long-term developmental trends and variation. Findings from univariate and multivariate analyses revealed specific effects of childhood, parental, contextual, and individual risk factors on the class membership as well as on the growth within each trajectory class.

Adolescent↗
PubMed2004

Developmental trajectories of cigarette smoking and their correlates from early adolescence to young adulthood.

Smoking initiation typically occurs in adolescence and increases over time into emerging adulthood. Thus adolescence and emerging adulthood compose a critical time period for prevention and intervention efforts. To inform these efforts, this study used latent growth mixture modeling to identify 6 smoking trajectories from ages 13 to 23 among 5,914 individuals: nonsmokers (28%), stable highs (6%), early increasers (10%), late increasers (10%), decreasers (6%), and triers (40%). By age 23, the trajectories merged into 2 distinct groups of low- and high-frequency and their standing on age 23 outcomes reflected this grouping. Consideration of these results can help researchers identify at-risk individuals before their smoking becomes too problematic, providing an opportunity for intervention and possible prevention of nicotine dependence.

Adolescent↗
PubMed2003

Marital status and quality in middle-aged women: Associations with levels and trajectories of cardiovascular risk factors.

The current study compared cardiovascular risk profiles and trajectories (i.e., within-person changes) of women who were married or cohabitating and who had high relationship satisfaction with those of women with moderate or low satisfaction and with those of women who were single, divorced, and widowed. Participants were 493 women from the Healthy Women Study, a prospective investigation of health during and after the menopausal transition. Risk factors were measured across more than 5 occasions and 13 years, on average. Data were analyzed using a multilevel modeling technique. Overall, women in relationships with high satisfaction had lower levels of biological, lifestyle, and psychosocial risk factors when compared with the other groups. In some cases, women in satisfying marriages also showed a lower risk trajectory on risk factors relative to other women. Hence, marriage appears to confer health benefits for women, but only when marital satisfaction is high.

Cardiovascular Diseases↗
PubMed2004

Marijuana use from adolescence to young adulthood: multiple developmental trajectories and their associated outcomes.

This study used latent growth mixture modeling to identify discrete developmental patterns of marijuana use from early adolescence (age 13) to young adulthood (age 23) among a sample of 5,833 individuals. After the a priori removal of abstainers, 4 trajectory groups were identified: early high users, who decreased from a relatively high level of use at age 13 to a more moderate level: stable light users, who maintained a low level of use: steady increasers, who consistently increased use; and occasional light users, who began use at age 14 and used at low levels thereafter. Analyses of covariance comparing the trajectory groups on behavioral, socioeconomic, and health outcomes at age 29 revealed that abstainers consistently had the most favorable outcomes, whereas early high users consistently had the least favorable outcomes.

Adolescent↗
PubMed2004

Family-focused preventive interventions: evaluating parental risk moderation of substance use trajectories.

Four years of longitudinal data from 373 families participating in a randomized intervention-control clinical trial were used to examine whether intervention effects on adolescent alcohol and tobacco use trajectories were moderated by family risk, as defined by parental social emotional maladjustment. Consistent with earlier outcome evaluations based on analyses of covariance, analyses confirmed that both the Preparing for the Drug Free Years program and the Iowa Strengthening Families Program favorably influenced alcohol use index trajectories across the time frame of the study; only the latter program, however, evidenced positive effects on a tobacco use index. Concerning the primary research question, analyses provided no support for family risk moderation of any intervention effect. Findings indicate the feasibility of developing universal preventive interventions that offer comparable benefits to all families.

Adolescent↗
PubMed2004

Comparing the developmental trajectories of marijuana use of African American and Caucasian adolescents: patterns, antecedents, and consequences.

Adolescent marijuana use has tripled recently, and the once-noted race gap between African American and Caucasian adolescents in marijuana use appears to have disappeared. Yet, relatively little research has examined marijuana use among African American adolescents. In this study, we examined developmental trajectories of marijuana use among Caucasian and African American adolescents to identify whether and when differences in marijuana use appear and whether the precursors and outcomes associated with these developmental trajectories differ by race. Findings indicate that both the developmental patterns and outcomes associated with marijuana use are different for African American and Caucasian adolescents. Early-onset Caucasian and mid-onset African American adolescents experienced the greatest number of negative outcomes later in life associated with their marijuana use, suggesting that groups to target for intervention may vary by race.

Adolescent↗
PubMed2006

The thrifty 'catch-up fat' phenotype: its impact on insulin sensitivity during growth trajectories to obesity and metabolic syndrome.

The analyses of large epidemiological databases have suggested that infants and children who show catch-up growth, or adiposity rebound at a younger age, are predisposed to the development of obesity, type 2 diabetes and cardiovascular diseases later in life. The pathophysiological mechanisms by which these growth trajectories confer increased risks for these diseases are obscure, but there is compelling evidence that the dynamic process of catch-up growth per se, which often overlaps with adiposity rebound at a younger age, is characterized by hyperinsulinemia and by a disproportionately higher rate in the recovery of body fat than lean tissue (i.e. preferential 'catch-up fat'). This paper first focuses upon the almost ubiquitous nature of this preferential 'catch-up fat' phenotype across the life cycle as a risk factor for obesity and insulin-related complications - not only in infants and children who experienced catch-up growth after earlier fetal or neonatal growth retardation, or after preterm birth, but also in adults who show weight recovery after substantial weight loss owing to famine, disease-cachexia or periodic dieting. It subsequently reviews the evidence indicating that such preferential catch-up fat is primarily driven by energy conservation (thrifty) mechanisms operating via suppressed thermogenesis, with glucose thus spared from oxidation in skeletal muscle being directed towards de novo lipogenesis and storage in white adipose tissue. A molecular-physiological framework is presented which integrates emerging insights into the mechanisms by which this thrifty 'catch-up fat' phenotype crosslinks with early development of insulin and leptin resistance. In the complex interactions between genetic constitution of the individual, programming earlier in life, and a subsequent lifestyle of energy dense foods and low physical activity, this thrifty 'catch-up fat' phenotype--which probably evolved to increase survival capacity in a hunter-gatherer lifestyle of periodic food shortages--is a central event in growth trajectories to obesity and to diseases that cluster into the insulin resistance (metabolic) syndrome.

Adiposity↗
PubMed2006

Neuregulin 1 (8p12) and childhood-onset schizophrenia: susceptibility haplotypes for diagnosis and brain developmental trajectories.

Childhood-onset schizophrenia (COS), defined as onset of psychosis by the age of 12, is a rare and malignant form of the illness, which may have more salient genetic influence. Since the initial report of association between neuregulin 1 (NRG1) and schizophrenia in 2002, numerous independent replications have been reported. In the current study, we genotyped 56 markers (54 single-nucleotide polymorphisms (SNPs) and two microsatellites) spanning the NRG1 locus on 78 COS patients and their parents. We used family-based association analysis for both diagnostic (extended transmission disequilibrium test) and quantitative phenotypes (quantitative transmission disequilibrium test) and mixed-model regression. Most subjects had prospective anatomic brain magnetic resonance imaging (MRI) scans at 2-year intervals. Further, we genotyped a sample of 165 healthy controls in the MRI study to examine genetic risk effects on normal brain development. Individual markers showed overtransmission of alleles to affecteds (P=0.009-0.05). Further, several novel four-marker haplotypes demonstrated significant transmission distortion. There was no evidence of epistasis with SNPs in erbB4. The risk allele (0) at 420M9-1395 was associated with poorer premorbid social functioning. Further, possession of the risk allele was associated with different trajectories of change in lobar volumes. In the COS group, risk allele carriers had greater total gray and white matter volume in childhood and a steeper rate of subsequent decline in volume into adolescence. By contrast, in healthy children, possession of the risk allele was associated with different trajectories in gray matter only and was confined to frontotemporal regions, reflecting epistatic or other illness-specific effects mediating NRG1 influence on brain development in COS. This replication further documents the role of NRG1 in the abnormal brain development in schizophrenia. This is the first demonstration of a disease-specific pattern of gene action in schizophrenia.

Adolescent↗
PubMed2002

Trajectories of target reaching arm movements in individuals with spinal cord injury: effect of external trunk support.

DESIGN: Deficits in trunk control due to spinal cord injury (SCI) lead to slower target-reaching movements of the hand. We investigated whether the movement path is also affected, and whether providing external support for the trunk can abolish the kinematic differences. OBJECTIVE: To compare movement trajectories between individuals with SCI and neurologically normal individuals, with and without external trunk support. SETTING: Neural Control/Biomechanics Laboratory, University of Illinois, Chicago, USA. METHODS: Five subjects with levels of injury between C7 and T4 were tested 3-8 years post-injury, and compared with five control subjects. Two targets were employed. Trajectories were recorded by a motion-capture system using infrared emitting markers. Peak speed and path curvature were calculated for the fingertip and for the acromion. RESULTS: Compared with control subjects, the subjects with SCI exhibited lower peak speed of the fingertip but not of the acromion, and less straight paths for both. When the trunk was supported externally, the difference in fingertip speed persisted. The support abolished the difference in path curvature for the fingertip but accentuated that for the acromion. CONCLUSION: The slower hand movements of individuals with SCI are not simply time-scaled versions of those of normal subjects, and the provision of trunk support does not erase the kinematic differences between the reaching movements of the two groups.

Acromion↗
PubMed2005

Comparison of measures of variability of speech movement trajectories using synthetic records.

In speech research, it is often desirable to assess quantitatively the variability of a set of speech movement trajectories. This problem is studied here using synthetic trajectories, which consist of a common pattern and terms representing amplitude and phase variability. The results show that a technique for temporal alignment of the records based on functional data analysis allows us to extract the pattern and variability terms as separate functions, with good approximation. Indices of amplitude and phase variability are defined, which provide a more accurate assessment of variability than previous approaches.

Algorithms↗
PubMed2003

An ecological approach to understanding youth smoking trajectories: problems and prospects.

Non-random patterns of aggregate youth smoking rates and trajectories across communities suggest that individual-level characteristics cannot account fully for the behavior in question. Instead, at least part of the explanation must lie somewhere within the community context. Such community-level contextual effects can impact directly both group and individual-level behavior (e.g. main effects), and they can also condition the effects of individual-level factors on individual behaviors (e.g. moderating effects). This paper reviews previous research examining community-level contextual effects regarding smoking and substance use more generally and identifies important limitations of this extant work, thus defining an agenda for future empirical studies. Next, the (in)compatibility of previous empirical findings with current theoretical models is discussed. In offering an alternative to these existing models, the paper concludes with presentation and discussion of a multi-level, integrated model of adolescent smoking trajectories. In this model, community/institutional forces are presumed to impact smoking above and beyond individual-level main effects. These posited community-level forces are broad and varied, representing school characteristics, neighborhood demographic characteristics, religious culture, media influence, economic context, health services and so on. In addition to exhibiting contextual main effects, the effects of community in the proposed multilevel model can be mediated by community-level processes, including the processes of control and socialization discussed herein. Also, community-level characteristics may interact in producing certain tobacco-use outcomes and, perhaps most importantly, they may moderate or condition the effects of interindividual differences on smoking.

Adolescent↗
PubMed2000

Aberrant trajectory of entorhino-dentate axons in the mutant Shaking Rat Kawasaki: a Dil-labelling study.

The Shaking Rat Kawasaki (SRK) is a neurological mutant that exhibits abnormalities of cell migration and lamination, with many similarities to the mouse reeler mutant. We recently used lamina-specific antibody staining to show that despite severe aberrations in the laminar organization of the SRK dentate gyrus, the entorhinal terminal field in the outer dentate molecular layer appeared relatively normal (Woodhams & Terashima, 1999, J. Comp. Neurol. 409 p57). However, neurofilament immunostaining suggested that entorhino-dentate afferents take an abnormal trajectory in reaching their appropriate targets, the granule cells dendrites. In the present study, anterograde tracing with the carbocyanine dye 1, 1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) has been used to delineate directly the path that entorhinal axons take to the dentate gyrus, confirming that in SRK entorhinal axons do indeed reach their appropriate terminal fields in the molecular layer, with laminar segregation between projections from the lateral and medial entorhinal cortices. However, these fibres fail to cross the hippocampal fissure between the subiculum and the dentate gyrus, coursing instead parallel to it until they curve round the deepest point of the fissure in field CA3. Similar findings were seen in the murine reeler mutant. Insertion of DiI crystals into the entorhinal cortex of neonatal rats also retrogradely labelled the developmentally transient Cajal-Retzius cells at the hippocampal fissure; these survive for longer in SRK than in normal littermates. The presence of a marked astrogliosis at the SRK hippocampal fissure may play a part in determining the abnormal trajectory taken by entorhino-dentate afferents in this mutant.

Animals↗
PubMed2003

Human walking along a curved path. I. Body trajectory, segment orientation and the effect of vision.

Task-related characteristics of gait and segment orientation during natural locomotion along a curved path have been described in order to gain insight into the neural organization of walking. The locomotor task implied continuous deviation from straight-ahead, thereby requiring continuous adjustment of body movement to produce and assist turn-related torques. Performance was compared to straight-ahead locomotion. Subjects easily reproduced both trajectories with eyes open (EO). The actual-to-required trajectory difference increased blindfolded (BF), more so during turning. Stride length was unchanged for the outer but decreased for the inner leg. The feet anticipated subsequent body rotation by pivoting toward the inner side of the curve at heel strike. A shift of body centre of mass and trunk roll toward the inner side accompanied turning. The head turned more than dictated by the heading change, and the absolute range of yaw oscillation increased. Head yaw anticipated body yaw by approximately 200 ms. Despite the minor effect of vision on the behaviour of all other segments, a difference in head pitch occurred between EO and BF; with EO, the head was flexed (P < 0.01), as to look at the path, while pitch was negligible with BF. In general, the changes in the amplitude of head, trunk and feet movements proved to be well related to the kinematics of the steering body, and constituted a sort of basic library of motor synergies.

Adult↗
PubMedDate not supplied

Use of the wound healing trajectory as an outcome determinant for acute wound healing.

Accurate and clinically practical methods for measuring the progress of acute wound healing is necessary before interventions designed to optimize and even accelerate acute wound healing can be applied. Complete wound closure rates and operative wound closure severity are irrelevant to most acute wounds since most are closed at the time of primary tissue repair and remain closed throughout healing. Analogous to chronic wound closure, the rate of increase of incision tensile strength progressively decreases as time passes and 100% unwounded tissue strength is never achieved making the endpoint definition of "healed" vague. Conceptualizing acute wound healing in terms of its design elements with reintegration into a final outcome lends itself to the description of acute wound healing as a mathematical trajectory. Frequently such an equation is a rate expressing the change in an acute healing parameter, most often tensile strength, over time. Such an approach also normalizes misinterpretations in analysis or errors in theory developed by measuring healing parameters at fixed points in time. Distributions of fractional strength gain times (e.g., 85% normal strength) can be determined using statistical methodology similar that used for failure time of survival analysis. Preclinical studies show that acute wound healing trajectories can be shifted to the left from a "normal" or "impaired" curve to an accelerated or more "ideal" curve. A useful method for measuring acute wound healing outcomes is therefore required before the basic science of acute wound healing is inevitably applied to the problem of acute surgical wounds.

Acute Disease↗
PubMed2004

Fluoroscopic frameless computer-assisted navigation for transsphenoidal surgery: a clinical assessment of accuracy in spatial position and trajectory.

OBJECTIVE: Fluoroscopic navigation technique in transsphenoidal surgery on the one hand provides multi-planar (antero-posterior and lateral views) navigation while on the other hand it does not need any preoperative preparation. To assess the clinical accuracy of the above technique in the transsphenoidal surgery, we performed this study. METHODS: 5 patients undergoing transsphenoidal surgery were assessed. Fluoroscopic images were compared with C-arm X-ray images for difference in spatial position and trajectory. RESULTS: 26 sets of data were collected for analysis. Mean pointer tip difference was 0.6 mm. The 95 % confidence interval was 1.3 mm. Mean trajectory difference was 1.2 degree. The 95 % confidence interval was 2.7 degree. CONCLUSION: With a good clinical accuracy, fluoroscopic navigation offers a distinct advantage to replace the traditional fluoroscopic approach for transsphenoidal surgery for its low X-ray exposure and multi-planar (antero-posterior and lateral views) navigation.

Adenoma↗
PubMed1993

Development of muscle power in preterm infants: individual trajectories after term age.

In a longitudinal study individual trajectories were traced for the developing relationship between active and passive muscle power in preterm (n = 37) and fullterm (n = 20) infants from term to 24 weeks (corrected) age. Such trajectories should enable the identification of those infants at highest risk for later neurological dysfunctions. This contention is supported by the findings of this study: those preterm infants who showed marked discrepancies between the two sorts of muscle power or rigidity in both beyond 12 weeks corrected age were most likely to manifest neurological problems at 52 weeks of age.

Female↗
PubMed2003

On the constructive role of noise in stabilizing itinerant trajectories in chaotic dynamical systems.

This work aims at studying dynamical models of neural networks, which exhibit phase transitions between states of various complexities. We use the biologically motivated KIII model, which has demonstrated excellent performance as a robust dynamical memory device. KIII is a high-dimensional dynamical system with extremely fragmented boundaries between limit cycles, tori, fixed points, and chaotic attractors. We study the role of additive noise in the development of itinerant trajectories. Noise not only stabilizes aperiodic trajectories, but there is an optimum noise level with highly itinerant behavior. We speculate that the previously found optimum classification performance of KIII as a function of the noise level, also identified as chaotic resonance, is related to chaotic itinerant oscillations among various ordered states.

Animals↗