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PubMed1995

Bilateral labyrinthectomy in the cat: effects on the postural response to translation.

1. This study examined the role of vestibular afferent information on the postural responses of four cats, evoked by movements of the support surface during stance. Animals were exposed to linear translations of the supporting surface in eight evenly spaced directions in the horizontal plane, before and after bilateral labyrinthectomy. Postural responses were quantified in terms of the ground reaction forces under each paw and the evoked activity in selected muscles. 2. The cats were able to stand on the platform within 1-3 days after labyrinthectomy and were able to maintain balance during all perturbations of stance, even when they stood in total darkness, completely deprived of visual information. After lesion, postural responses were characterized by normal latency and normal spatial and temporal patterning of electromyographic (EMG) response. The pattern of force response showed the force constraint strategy that characterizes postural responses in the intact animal. 3. The only deficit in the postural response after lesion was a hypermetria, or active over-response that caused the animals to overbalance somewhat but did not impair their ability to remain upright. Analysis of the trajectory of the animal's center of mass during the trials indicated that the hypermetria was due to an abnormally large, active response on the part of the animal and could not be attributed to changes in the passive stiffness of the musculoskeletal system. The hypermetria was transient, and response amplitude returned to control levels after the rapid compensation phase of 10-15 days. 4. It is concluded that vestibular information is not essential for triggering the rapid, automatic postural response to translations of the support surface, nor is it necessary for the selection or shaping of the evoked response. Instead, somatosensory information appears to predominate in these postural adjustments. However, vestibular afferent input does influence the scaling of the postural response.

Afferent Pathways↗

PubMed1983

Size and diet in the evolution of African ape craniodental form.

Interspecific differences in craniodental morphology among Pan paniscus, Pan troglodytes, and Gorilla gorilla are analyzed. These apes differ in both diet and body size, and thus present an excellent example in which to apply an allometric criterion of subtraction in order to determine morphological differences which might be related to divergent dietary specialization. The use of ontogenetic allometry in particular as a criterion of subtraction is discussed. Bivariate and multivariate results indicate that most of the variation in skull form among the species relates to the extension of a common growth trend to different sizes. Comparative analysis of growth trajectories reveals a number of differences, but none that appear to relate to a reorganization of skull proportions which might correspond to a dietary shift towards increased folivory. The dentition clearly exhibits non-allometric shape changes corresponding to the dietary differences, however. The meaning of these differences between cranial and dental patterns is discussed.

Africa↗

PubMed2007

Infant eye and head movements toward the side opposite the cue in the anti-saccade paradigm.

BACKGROUND: The anti-saccade task, when people must respond in the direction opposite to a visual stimulus, has been used as a marker of operation of the frontal cortical oculomotor area. However, early development of oculomotor control has been little studied with the infant anti-saccade paradigm, and a few studies did not recognize anti-saccades in infants in light of the results of adult anti-saccade. Since the characteristics of infant eye movements are little known, applying the criteria used in adult study is by no means the best way to study infant anti-saccade. As it is indicated that coordinated eye and head movements often enable infants to control the direction of their gaze, head movements should be examined as an infant orienting response. The aim of this study was to address how infants used eye and head movements during the anti-saccade paradigm. To distinguish infants' responses, we also investigated eye and head movements during a task for an inhibition of return. Inhibition of return, in which delayed responses occur in the direction to which attention had previously been oriented, has been thought to mark activity of the superior colliculus. Since the superior colliculus is thought to develop much earlier in life than the frontal lobes, we thought it useful to compare these task performances during infancy. METHODS: Infants were divided into three groups according to age. Anti-saccade and inhibition-of-return tasks were given. Their eye and head movements during tasks were independently recorded by the corneal reflection method in the head-free condition. RESULTS: Younger infants tended to initiate eye movement less than older ones in both tasks. In the anti-saccade task, responses opposite to the cue tended to show longer latency than responses to the cue. Infants made faster responses toward the side opposite the cue when it was to the right than when it was left of fixation. Regarding the comparison of responses toward the side opposite the cue between two tasks, the leftward eye movement was faster than the leftward head movements in the inhibition-of-return task, while no difference of latency was observed between eye and head movements in the anti-saccade task. A qualitative analysis of the trajectory of these responses revealed that head movement trajectories were steeper in the anti-saccade than in the inhibition-of-return task. CONCLUSION: Younger infants move head and eyes together, with head movements frequently starting first. On the other hand, both the leftward latency difference between eye and head and gentle trajectories of head in inhibition of return indicate that eye movements are more predominant over head movements in the inhibition-of-return task than in the anti-saccade task. This would suggest an earlier developing inhibition-of-return mechanism.

Journal Article↗

PubMed1999

Vimentin contributes to human mammary epithelial cell migration.

Vimentin expression in human mammary epithelial MCF10A cells was examined as a function of their migratory status using an in vitro wound-healing model. Analysis of the trajectories of the cells and their migratory speeds by time lapse-video microscopy revealed that vimentin mRNA and protein expression were exclusively induced in cells at the wound's edge which were actively migrating towards the center of the lesion. Actin labeling showed the reorganization of actin filaments in cells at the wound's edge which confirmed the migratory phenotype of this cell subpopulation. Moreover, the vimentin protein disappeared when the cells became stationary after wound closure. Using cells transfected with the vimentin promoter controlling the green fluorescent protein gene, we also demonstrated the specific activation of the vimentin promoter in the migratory cells at the wound's edge. Transfection of the antisense vimentin cDNA into MCF10A cells clearly reduced both their ability to express vimentin and their migratory speed. Taken together, these observations demonstrate that vimentin is transiently associated with, and could be functionally involved in, the migratory status of human epithelial cells.

Actins↗

PubMed2005

Molecular dynamics studies on free and bound targets of the bovine papillomavirus type I e2 protein: the protein binding effect on DNA and the recognition mechanism.

Molecular dynamics simulations of a total duration of 30 ns in explicit solvent were carried out on the BPV-1-E2 protein complexed to a high-affinity DNA target containing the two hydrogen-bonded ACCG.CGGT half-sites separated by the noncontacted ACGT sequence. The analysis of the trajectories focuses on the DNA structure and on the dynamics. The data are compared to those issued from recent simulations made on three free targets that recognize E2 with different affinities. E2 does not drastically perturb the mechanic properties of the free DNA: the structural relationships between the BI/BII backbone substates and some helical parameters are preserved in the complex despite a severe slowing down of the phosphate group motions. The structures of both free and bound half-sites are very close to each other although the conformational space explored by these regions is narrowed when they are contacted by the protein. The enhanced plasticity found in the best free target spacers, mainly manifested through the backbone motions, allows a clear overlap between several free and bound global DNA features such as the base displacement. Furthermore, this flexibility is preserved in the complex. Our results support the hypothesis that E2 takes advantage of free predistorted structures that may minimize the DNA deformation cost. In addition, we observe that E2 is far from totally stiffening the DNA, suggesting that the entropic penalty inherent in the complex formation could be limited.

Base Sequence↗

PubMed2000

Work-place homicide by bow and arrow.

Arrow wounds represent an unusual class of wounds rarely seen by most forensic pathologists. In this paper we present a case of homicide by bow and arrow and the characteristics of such injuries. The essential characteristics of the lesions obtained from conically-tapered field points and from hunting broadhead tips are described and discussed in relation to injuries caused by firearm bullets. In the present case, three arrows struck the victim, and the order in which the injuries were sustained are analyzed. We also discuss the possibilities of localizing the shooter relative to the victim by analysis of the trajectories.

Cause of Death↗

PubMed2001

African American women's experiences with the initial discovery, diagnosis, and treatment of breast cancer.

PURPOSE/OBJECTIVES: To describe the experiences of African American women living with breast cancer following the primary diagnosis and while undergoing initial treatment. DESIGN: Phenomenologic. SAMPLE/SETTING: 13 African American women (ages 30-66) purposefully selected from two oncology clinics in the mid-South. METHODS: Phenomenologic interviews (transcribed verbatim) and field notes were analyzed using Colaizzi's method of phenomenologic description and analysis. FINDINGS: Experience Trajectory, Femininity, and Spirituality were the three major themes. The Experience Trajectory subthemes were finding the lump, getting the diagnosis, undergoing surgery and adjuvant treatment. The Femininity subthemes were loss of all or part of the breast, loss of hair, and sexual attractiveness to a man. Spirituality was reflected as a reliance on God. CONCLUSIONS: Telling the story of their experience trajectory during their breast cancer experience is valuable in assessing African American women's feelings, emotions, and fears of body changes that occur during surgery and treatment. Their spirituality helps them through this experience. Research involving both African American women and their partners would provide greater insight into specific relationship patterns and communication related to sexuality during this experience. IMPLICATIONS FOR NURSING PRACTICE: Nurses need to listen to the stories of African American women about the initial experience of discovery, diagnosis, and treatment of breast cancer so they can be more informed advocates for these women. African American women need more information from healthcare providers regarding the whole experience trajectory.

Adaptation, Psychological↗

PubMed2004

Baltic sub-basin turnover times examined using the Rossby Centre Ocean model.

Not least when judging the possible effects of climate change it proves necessary to estimate the water-renewal rates of limited marine areas subject to pronounced external influences. In connection with the SWECLIM programme this has been undertaken for two ecologically sensitive sub-basins of the Baltic, viz. the Gulf of Riga and Gdansk Bay. For this purpose two methodologically different approaches have been employed, based on mass-balance budgets and analysis of Lagrangian trajectories, respectively. When compared to the results obtained using the Lagrangian technique, the box-model approach proved to be adequate for the Gulf of Riga representing a morphologically highly constrained basin, whereas it demonstrated certain shortcomings when applied to the more open topographic conditions characterizing Gdansk Bay.

Baltic States↗

PubMed2005

Dynamic and electrostatic effects in enzymatic processes. An analysis of the nucleophilic substitution reaction in haloalkane dehalogenase.

We present an analysis of rare event trajectories for the nucleophilic displacement of a chloride anion of 1,2-dichloroethane by a carboxylate group in haloalkane dehalogenase from Xanthobacterautotrophicus (DhlA) and in aqueous solution. Differences in the transmission coefficient are rationalized on the basis of the electrostatic coupling between the chemical system and the environment. Detailed analysis of the reactive trajectories reveals that the evolution of the hydrogen bond interactions established between the substrate and the environment present significant differences in aqueous solution and in the enzyme. The structure of the enzymatic active site provides a more adequate interaction pattern for the reaction progress.

Chlorides↗

PubMed2001

Enzyme specificity under dynamic control II: Principal component analysis of alpha-lytic protease using global and local solvent boundary conditions.

The contributions of conformational dynamics to substrate specificity have been examined by the application of principal component analysis to molecular dynamics trajectories of alpha-lytic protease. The wild-type alpha-lytic protease is highly specific for substrates with small hydrophobic side chains at the specificity pocket, while the Met190-->Ala binding pocket mutant has a much broader specificity, actively hydrolyzing substrates ranging from Ala to Phe. Based on a combination of multiconformation analysis of cryo-X-ray crystallographic data, solution nuclear magnetic resonance (NMR), and normal mode calculations, we had hypothesized that the large alteration in specificity of the mutant enzyme is mainly attributable to changes in the dynamic movement of the two walls of the specificity pocket. To test this hypothesis, we performed a principal component analysis using 1-nanosecond molecular dynamics simulations using either a global or local solvent boundary condition. The results of this analysis strongly support our hypothesis and verify the results previously obtained by in vacuo normal mode analysis. We found that the walls of the wild-type substrate binding pocket move in tandem with one another, causing the pocket size to remain fixed so that only small substrates are recognized. In contrast, the M190A mutant shows uncoupled movement of the binding pocket walls, allowing the pocket to sample both smaller and larger sizes, which appears to be the cause of the observed broad specificity. The results suggest that the protein dynamics of alpha-lytic protease may play a significant role in defining the patterns of substrate specificity. As shown here, concerted local movements within proteins can be efficiently analyzed through a combination of principal component analysis and molecular dynamics trajectories using a local solvent boundary condition to reduce computational time and matrix size.

Amino Acid Substitution↗

PubMed2006

Use of spinous processes to determine drill trajectory during placement of lateral mass screws: a cadaveric analysis.

OBJECTIVE: Prior cadaveric research showed that the lateral mass and facets are landmarks to determine the initial starting point for lateral mass screws and that the optimum screw trajectory was 30 degrees lateral and 15 degrees cephalad. The missing link was an intraoperative landmark to guide the trajectory for drilling according to these angles. The authors hypothesized that spinous processes can be used to guide the trajectory for lateral mass screw placement. METHODS: The authors analyzed 144 lateral masses of 72 cervical vertebrae in 18 cadavers (7 males and 11 females). The lateral and cephalocaudad angles were measured for each lateral mass from C3 to C6 while using the spinous processes of the adjacent three caudad vertebrae at each level to guide the starting trajectories for a total of 864 angles. The lateral and cephalad trajectory angles at each spinous process relative to the starting hole were compared with 30 degrees and 15 degrees . For each angle measured at a particular level, the same starting hole was used in the lateral mass, and the superolateral cortex of each spinous process was the most medial point. RESULTS: When drilling for the C3 and C4 lateral mass screws, the C4 and C5 spinous processes provided an accurate starting point, respectively, for the lateral angle but moderately overestimated the cephalocaudad angle. For C5 and C6 lateral mass screws, the C6 and C7 spinous processes provided an accurate starting point, respectively, for both the lateral and the cephalocaudad angles. CONCLUSION: The spinous processes can be an accurate local anatomic guide for lateral mass screw trajectory and will allow greater safety while drilling before performing laminectomies. These guides may change in patients with cervical spinal deformities.

Bone Screws↗

PubMed2001

Examining developmental trajectories in adolescent alcohol use using piecewise growth mixture modeling analysis.

OBJECTIVE: This study examined issues of heterogeneity in multiple stage development as it corresponds to qualitatively different developmental trajectories in alcohol use during adolescence. METHOD: Using a piecewise growth mixture modeling methodology, a two-piece growth model capturing growth trajectories in adolescent alcohol use from middle school (Grades 6 through 8) to high school (Grades 9 through 12) was examined (N = 179; 54% male). It was hypothesized that (1) two stages of alcohol use development with varying trajectories would exist in these data (the first corresponding to development during middle school, followed by a second stage of continuing growth during high school) and (2) there would be multiple growth trajectories (subgroups) of alcohol use in the stage-wise development, with varying effects in initial alcohol use and growth rates of alcohol use. RESULTS: Results indicated the tenability of the two-piece growth model of alcohol use with heterogeneity in the population comprising two distinct latent developmental trajectory classes. Class 1, with a high initial status of alcohol use at Grade 6, showed an upward increase in trajectory only during high school. Class 2, with a low initial status of alcohol use at Grade 6, showed a linear increase in middle school with a second growth spurt at high school entry and continuity in growth throughout the high school years. Analyses, incorporating time-invariate covariates, indicated varying influences of gender, early levels of deviant behavior, family structure (single vs two parent), peer encouragement and parent disapproval of alcohol use, and adolescent deviant behavior upon high school entry, on the two trajectory classes. Results also showed effects of the identified trajectories, with varying magnitudes, on later substance use in young adulthood, with Class 1 showing the strongest continuity in later substance use. CONCLUSIONS: Findings suggest heterogenous development of alcohol use in the adolescent population, associated with varying background and covariate influences. In addition, this heterogeneity is linked to alcohol and other substance use in young adulthood.

Adolescent↗

PubMed2000

Parents' perceptions of chronic illness trajectories.

The notion of a small, generic set of chronic illness trajectories that can be independent of specific medical diagnoses, though controversial, has some theoretical, clinical, and qualitative research support. The purpose of this study was to quantitatively describe trajectories among parents of children with a chronic condition. It was hypothesized that factor analysis would confirm 3 trajectories similar to those in the qualitative literature and that parents' perceptions of their child's trajectory would differ significantly from medically based perceptions. A total of 140 parents provided data on their perceptions of the past, present, and future course of the condition of their repeatedly hospitalized child. Fourteen time-related items from the Coping Health Inventory for Parents Questionnaire on Resources and Stress and the Parenting Stress Index were analyzed. Pre- and post-hospitalization factor analyses extracted the same 8 items to construct 3 trajectories: Life Threatening; Declining; and Stable, Optimistic. The views of approximately one third of the parents differed from medically based classifications. Type of nursing care had no bearing on the perceptions of the parents.

Adaptation, Psychological↗

PubMedDate not supplied

Recovery trajectory of unpartnered elders after myocardial infarction: an analysis of daily diaries.

The study reported here analyzed daily diary entries of unpartnered elders after myocardial infarction (MI) to gain perspective into their recovery. A total of 33 diaries were included as part of the qualitative analysis of the larger study referred to above. Diary content was evaluated through qualitative descriptive analysis. Six categories--activities of daily living, exercise practices, social support, symptom reporting, healthcare activities, and health-related expenses--were identified from the diaries. Results suggest that recovering, unpartnered MI elders have a need to return to a familiar lifestyle. Moreover, a few differences and similarities based on gender were found. In the rehabilitation setting, nurses should recognize the need for elders to return to normal activities, the importance of social support, the acknowledgement of gender differences, and the potential cost burden for these patients. Diaries were a valuable tool with which to uncover information about the recovery trajectory of unpartnered elders after MI.

Activities of Daily Living↗

PubMed1990

Analysis of the inheritance, selection and evolution of growth trajectories.

We present methods for estimating the parameters of inheritance and selection that appear in a quantitative genetic model for the evolution growth trajectories and other "infinite-dimensional" traits that we recently introduced. Two methods for estimating the additive genetic covariance function are developed, a "full" model that fully fits the data and a "reduced" model that generates a smoothed estimate consistent with the sampling errors in the data. By decomposing the covariance function into its eigenvalues and eigenfunctions, it is possible to identify potential evolutionary changes in the population's mean growth trajectory for which there is (and those for which there is not) genetic variation. Algorithms for estimating these quantities, their confidence intervals, and for testing hypotheses about them are developed. These techniques are illustrated by an analysis of early growth in mice. Compatible methods for estimating the selection gradient function acting on growth trajectories in natural or domesticated populations are presented. We show how the estimates for the additive genetic covariance function and the selection gradient function can be used to predict the evolutionary change in a population's mean growth trajectory.

Animals↗

PubMed2002

Ontogenetic study of the skull in modern humans and the common chimpanzees: neotenic hypothesis reconsidered with a tridimensional Procrustes analysis.

Heterochronic studies compare ontogenetic trajectories of an organ in different species: here, the skulls of common chimpanzees and modern humans. A growth trajectory requires three parameters: size, shape, and ontogenetic age. One of the great advantages of the Procrustes method is the precise definition of size and shape for whole organs such as the skull. The estimated ontogenetic age (dental stages) is added to the plot to give a graphical representation to compare growth trajectories. We used the skulls of 41 Homo sapiens and 50 Pan troglodytes at various stages of growth. The Procrustes superimposition of all specimens was completed by statistical procedures (principal component analysis, multivariate regression, and discriminant function) to calculate separately size-related shape changes (allometry common to chimpanzees and humans), and interspecific shape differences (discriminant function). The results confirm the neotenic theory of the human skull (sensu Gould [1977] Ontogeny and Phylogeny, Cambridge: Harvard University Press; Alberch et al. [1979] Paleobiology 5:296-317), but modify it slightly. Human growth is clearly retarded in terms of both the magnitude of changes (size-shape covariation) and shape alone (size-shape dissociation) with respect to the chimpanzees. At the end of growth, the adult skull in humans reaches an allometric shape (size-related shape) which is equivalent to that of juvenile chimpanzees with no permanent teeth, and a size which is equivalent to that of adult chimpanzees. Our results show that human neoteny involves not only shape retardation (paedomorphosis), but also changes in relative growth velocity. Before the eruption of the first molar, human growth is accelerated, and then strongly decelerated, relative to the growth of the chimpanzee as a reference. This entails a complex process, which explains why these species reach the same overall (i.e., brain + face) size in adult stage. The neotenic traits seem to concern primarily the function of encephalization, but less so other parts of the skull. Our results, based on the discriminant function, reveal that additional structural traits (corresponding to the nonallometric part of the shape which is specific to humans) are rather situated in the other part of the skull. They mainly concern the equilibrium of the head related to bipedalism, and the respiratory and masticatory functions. Thus, the reduced prognathism, the flexed cranial base (forward position of the foramen magnum which is brought closer to the palate), the reduced anterior portion of the face, the reduced glabella, and the prominent nose mainly correspond to functional innovations which have nothing to do with a neotenic process in human evolution. The statistical analysis used here gives us the possibility to point out that some traits, which have been classically described as paedomorphic because they superficially resemble juvenile traits, are in reality independent of growth.

Animals↗

PubMed1990

Conformational and helicoidal analysis of the molecular dynamics of proteins: "curves," dials and windows for a 50 psec dynamic trajectory of BPTI.

A new procedure for the graphic analysis of molecular dynamics (MD) simulations on proteins is introduced, in which comprehensive visualization of results and pattern recognition is greatly facilitated. The method involves determining the conformational and helicoidal parameters for each structure entering the analysis via the method "Curves," developed for proteins by Sklenar, Etchebest, and Lavery (Proteins: Structure, Function Genet. 6:46-60, 1989) followed by a novel computer graphic display of the results. The graphic display is organized systematically using conformation wheels ("dials") for each torsional parameter and "windows" on the range values assumed by the linear and angular helicoidal parameters, and is present in a form isomorphous with the primary structure per se. The complete time evolution of dynamic structure can then be depicted in a set of four composite figures. Dynamic aspects of secondary and tertiary structure are also provided. The procedure is illustrated with an analysis of a 50 psec in vacuo simulation on the 58 residue protein, bovine pancreatic trypsin inhibitor (BPTI), in the vicinity of the local minimum on the energy surface corresponding to a high resolution crystal structure. The time evolution of 272 conformational and 788 helicoidal parameters for BPTI is analyzed. A number of interesting features can be discerned in the analysis, including the dynamic range of conformational and helicoidal motions, the dynamic extent of 2 degrees structure motifs, and the calculated fluctuations in the helix axis. This approach is expected to be useful for a critical analysis of the effects of various assumptions about force field parameters, truncation of potentials, solvation, and electrostatic effects, and can thus contribute to the development of more reliable simulation protocols for proteins. Extensions of the analysis to present differential changes in conformational and helicoidal parameters is expected to be valuable in MD studies of protein complexes with substrates, inhibitors, and effectors and in determining the nature of structural changes in protein-protein interactions.

Biological Evolution↗

PubMed2000

How women receiving adjuvant chemotherapy for breast cancer cope with their treatment: a risk management perspective.

Retrospective interviews were undertaken with 12 women who had received an 18-week course of adjuvant chemotherapy for positive node breast cancer 1 year previously, and who had not experienced cancer recurrence. The nonstandardized interviews covered women's preconceptions about adjuvant chemotherapy, their information needs, and the impact of treatment. The qualitative data analysis drew upon the theoretical ideas of patient career, trajectory projection and qualitative risk analysis. Some women regarded adjuvant chemotherapy as no more than an 'insurance policy'. This perception may have arisen because doctors, attempting to minimize patient anxiety, did not discuss the high risk of disease recurrence which they faced. Other women equated adjuvant with curative chemotherapy, and anticipated hair loss or almost certain death. The women tried to cope with the physical and mental suffering associated with adjuvant chemotherapy through normalizing strategies, such as keeping a brave face, maintaining previous patterns of life, looking for humour and restructuring time. However, the rapid alterations in physical and mental state resulting from cycles of adjuvant chemotherapy resulted in a 'rollercoaster' experience for women which made normalization more difficult. Health professionals caring for women who must cope with uncertain future trajectories need to manage a risk communication dilemma. A strategy of fully informing women about the risks they face may cause anxiety or depression, and even impede recovery, given the evidence for psychological influences on health outcomes. But, if women do not understand the medical thinking on which their treatment is based, their misconceptions may be equally damaging.

Adaptation, Psychological↗