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PubMed2004

Measles virus (MV) hemagglutinin: evidence that attachment sites for MV receptors SLAM and CD46 overlap on the globular head.

Measles virus hemagglutinin (MVH) residues potentially responsible for attachment to the wild-type (wt) MV receptor SLAM (CD150) have been identified and localized on the MVH globular head by reference to a revised hypothetical structural model for MVH (www.pepscan.nl/downloads/measlesH.pdb). We show that the mutation of five charged MVH residues which are conserved among morbillivirus H proteins has major effects on both SLAM downregulation and SLAM-dependent fusion. In the three-dimensional surface representation of the structural model, three of these residues (D505, D507, and R533) align the rim on one side of the cavity on the top surface of the MVH globular head and form the basis of a single continuous site that overlaps with the 546-548-549 CD46 binding site. We show that the overlapping sites fall within the footprint of an anti-MVH monoclonal antibody that neutralizes both wt and laboratory-vaccine MV strains and whose epitope contains R533. Our study does not exclude the possibility that Y481 binds CD46 directly but suggests that the N481Y mutation of wt MVH could influence, at a distance, the conformation of the overlapping sites so that affinity to CD46 increases. The relevance of these results to present concepts of MV receptor usage is discussed, and an explanation is proposed as to why morbillivirus attachment proteins are H, whereas those from the other paramyxoviruses are HN (hemagglutinin-neuraminidase).

Amino Acid Sequence↗
PubMed1999

Incorporating a statistically based shape model into a system for computer-assisted anterior cruciate ligament surgery.

This paper addresses the problem of extrapolating very sparse three-dimensional (3-D) data to obtain a complete surface representation. A new method that uses statistical shape models is proposed and its application to computer-assisted anterior cruciate ligament (ACL) reconstruction is detailed. The rupture of the ACL has become one of the most common knee injuries. One problem during reconstruction is to find the optimal attachment points for the graft. Therefore a system for computer-assisted reconstruction of the ACL has been proposed by TIMC laboratory. During surgery the surgeon collects several data points on the tibial and femoral joint surface with a 3-D localizer system. These 3-D data are used to find those attachment points resulting in a low anisometry of the graft, while preventing impingement between the graft and the femoral notch. As the collected data points only cover a small surface patch of the femur, it is desirable to extrapolate these data to also have a visualization in those areas where no data points are available. A sufficiently good approximation of the actual femur by the model would further allow us to better deal with the notch impingement problem of the graft. The chosen approach is to fit a deformable model to the data points, it can be subdivided into two steps, constructing the model and fitting this model to the data. To incorporate a priori knowledge into the model, the allowed deformations are determined by the statistics of the shape variation of a set of training objects. Matching the training objects together is obtained by elastic registration of surface points using octree splines. The fitting process of the sparse intra-operative data with the statistical model results in a non-linear multi-dimensional function minimization. A hybrid search strategy combining local and global methods is used to avoid local minima. First experimental results with a model generated from 10 femurs are presented, including fitting of the model with both simulated and real intra-operative data.

Anisotropy↗
PubMed1990

Object relations in borderline adolescents.

Although pathological object relations is a core aspect of borderline psychopathology, few studies have examined borderline object relations empirically, and none has focused on borderline adolescents. The present study examined four dimensions of object relations, as measured by the Thematic Apperception Test, in a sample of adolescent borderlines, psychiatric comparison subjects, and normals. These dimensions are complexity of object representations, affect-tone of relationship paradigms, capacity for emotional investment in relationships and moral standards, and understanding of social causality. Borderlines differed significantly from both comparison groups in several distinct ways, supporting some aspects of psychoanalytic theories of borderline object relations, while challenging others. Borderline adolescents have a malevolent object world, a relative incapacity to invest in others in a non-need-gratifying way, and a tendency to attribute motivation to others in simple, illogical, and idiosyncratic ways. Their object representations, however, can be quite complex, suggesting something other than a preoedipal arrest.

Adolescent↗
PubMed2003

Memories of mother, complementarity and shame: predicting response to subliminal stimulation with "Mommy and I are one".

A poorly understood finding with potentially wide-ranging implications is that subliminal stimulation with "Mommy and I are one" affects behavior. In this study (n= 62), "Mommy and I are one" lowered implicit mood (p= 0.0015) in comparison with a neutral stimulus ("People are walking"). The effect was most pronounced in shame-prone participants with less positive memories of their mother, and low self-mother complementarity (interaction p= 0.0044). Effects of a potentially shame-inducing stimulus ("I am completely isolated") were not significant (ps > 0.11). The results concerning less positive memories of mother replicate previous findings. We suggest that activation of unconscious associative networks explains the data. Though more research is needed, the cognitive content of these networks may involve representations of self-with-mother; for some, the affective content could involve shame.

Adult↗
PubMed1984

Multiple personality and borderline personality disorder.

The authors offer their theory that multiple personality represents a "special instance" of borderline personality disorder, that the introjects are composed of a representation of the self, a representation of the object, and an affective bond.

Adult↗
PubMed1980

A Theoretical and technical approach to narcissistic disturbance.

This paper makes a limited contribution to the theoretical problem of narcissism and offers a possibly useful technical approach. Terminology is clarified and two concepts are introduced: self-narcissism and object-narcissism. Detailed clinical material illustrates the presence of an unwished-for self-image acting as a resistance. Interpretation leading to integration of the self-image into the self-representation results in an increase in authenticity on which conventional interpretative activity depends. Objections and alternative views of the material are breifly discussed.

Adult↗
PubMed1991

Multiple representations contribute to body knowledge processing. Evidence from a case of autotopagnosia.

Body schema disturbances were studied in a 62-yr-old woman with Alzheimer's disease. She was severely impaired in verbal and nonverbal tasks requiring her to localize body parts (on her own body, the examiner's body or a doll's body) even though she correctly named the same parts when pointed at by the examiner. Pointing responses were misdirected mainly to parts contiguous with the target area and, to a lesser extent, to functionally equivalent body parts. We also found that the patient was able to define body part names functionally but not spatially. In another series of tasks, and in contrast to the above results, performances were normal when small objects, attached to the patient's body, served as pointing targets. Furthermore, on subsequent testing she pointed correctly at the remembered position of these objects. The fact that the same point in 'body space' is localized correctly when it corresponds to an external object and erroneously when it corresponds to a body part contradicts the idea of the body schema as a unitary function. Learning the position of objects on the body surface requires access to some form of body-reference system on which this information can be mapped. We argue that such a system can be available in autotopagnosia and is independent from the visuospatial representations of the body structure that are postulated to be damaged or inaccessible in this syndrome. An integrated account of the present results and of those reported by other authors suggests that multiple levels of representation (e.g., sensorimotor, visuospatial, semantic) are involved in the organization of body knowledge.

Agnosia↗
PubMed1998

Guidelines for analysis and redesign of dental implants.

This article describes the simulation of the mechanical behavior of two types of endosseous-threaded dental implants and the development of design guidelines for such implants. Two- and three-dimensional representations, static and dynamic cyclic loads, different material models, axial loads, and loads directed at the occlusal angle are all used. A novel model of trabecular bone is used to incorporate fatigue effects. Directional material behavior, progressive bone loss, and partial osseointegration are also modeled. Bone support using muscle attachment is modeled using spring constraints as opposed to fixed constraints used in previous studies. The tapered thread design from Brånemark Inc. exhibited higher stress levels in bone than those observed in the parallel profile thread from BUD Medical Devices, Inc. The BUD implant distributes stresses more evenly. Studies examining 25%, 75%, and 100% osseointegration showed cortical bone carried most of the load with resulting overload leading to crestal bone loss. Plots of stress showed that with increasing crestal bone loss, the majority of the load was transferred directly to the weaker trabecular bone tissue. Finally, it was shown that with proper implant redesign, loads can be transferred more evenly to the implant. This also improves fatigue life of the bone.

Alveolar Process↗
PubMed1995

Using maternal representational patterns to evaluate postpartum depression.

This paper has reviewed postpartum depression through the use of a case history. As exemplified by the case, a key factor contributing to the onset of postpartum depression appears to be the caregiver's representations of her own experience with caregivers. In general, mothers whose representations of their childhood experience are positive appear psychologically equipped to transfer these emotions to the infant and to assume caregiving tasks with enthusiasm. In contrast, mothers whose representations of their caregiving experience are negative are apathetic about engaging the infant in interaction and hesitant about accepting the maternal role. While several etiologic factors have been linked to postpartum depression, representational deficits may provide a more comprehensive explanation of the origins of the disorder because such deficits encompass not only the mother's capacities, but also influence the interactional patterns mother exhibits with the infant. The case history describes a mother who represented a conflicted relationship with her own caregiver. Initially, her representations of her own mother were vague and unclear. Through inquiry, however, she gained access to her own experience--or, at least, to her representation of it--and began to understand how her own memories had negatively affected her ability to interact adaptively with her infant son. Treatment focused on three areas: Overcoming the mother's depressed affect; providing behavioral support for the infant's developmental efforts; and, re-invigorating the dyadic relationship. To accomplish these goals, the mother was taught observation techniques and intuitive behaviors. These techniques enabled her to view the infant in an objective fashion, devoid of distorted representations from her own childhood that reflected her attitude toward her caregiver. Helping the mother attain this new perspective enabled her to generate more adaptive representations, to acknowledge infant development more positively, and to initiate an adaptive dyadic exchange.

Adult↗
PubMed2005

Playing dead: an unconscious fantasy, bodily focused defenses, and their roots in infancy.

A patient's unconscious fantasy of being her mother's dead baby emerged during the course of a long analysis, and was understood as her expression and explanation, constructed and elaborated throughout her development, of a fundamental and formative early infant state and experience. This patient's identification with a baby who had died before she was born was connected to her major complaint, a pervasive feeling that she could not act with intention, and to her obsessive ruminations, compulsive actions, and masochistic attacks on her body. The bodily based aspects and focus of these defenses were autistic-like, self-directed activities that can be understood as having their roots in what was experienced as catastrophic loss in the earliest weeks and months of life. Infant research, particularly on contingency detection, is especially useful in clarifying the ways in which these defenses may form, and in reconstructing and tracing the trajectories and intricate transformations of body ego, self- and other representations, and defenses from their earliest beginnings to their current manifestations in patients' fantasies and symptoms.

Adult↗
PubMed1982

[Development of a psychoanalytic memory theory].

A theory of memory for biographical material is proposed. This theory consists in the following central assumptions: a symbol formation process, which on the one hand maps affectively experienced object relations into inner propositions (representations) and on the other hand transforms representations into communicable symbols; repression which may affect representations and which thus establishes an unconsciousness which is rooted in object relations; defense mechanisms, which are part of the symbol formation process and which transform unconscious representations into conscious but distorted symbols. This theory is supposed to explain remembering, distorted remembering, and phenomena of compulsive repetition.

Affect↗
PubMed2006

Three-dimensional biofilm model with individual cells and continuum EPS matrix.

An innovative type of biofilm model is derived by combining an individual description of microbial particles with a continuum representation of the biofilm matrix. This hybrid model retains the advantages of each approach, while providing a more realistic description of the temporal development of biofilm structure in two or three spatial dimensions. The general model derivation takes into account any possible number of soluble components. These are substrates and metabolic products, which diffuse and react in the biofilm within individual microbial cells. The cells grow, divide, and produce extracellular polymeric substances (EPS) in a multispecies model setting. The EPS matrix is described by a continuum representation as incompressible viscous fluid, which can expand and retract due to generation and consumption processes. The cells move due to a pushing mechanism between cells in colonies and by an advective mechanism supported by the EPS dynamics. Detachment of both cells and EPS follows a continuum approach, whereas cells attach in discrete events. Two case studies are presented for model illustration. Biofilm consolidation is explained by shrinking due to EPS and cell degradation processes. This mechanism describes formation of a denser layer of cells in the biofilm depth and occurrence of an irregularly shaped biofilm surface under nutrient limiting conditions. Micro-colony formation is investigated by growth of autotrophic microbial colonies in an EPS matrix produced by heterotrophic cells. Size and shape of colonies of ammonia and nitrite-oxidizing bacteria (NOB) are comparatively studied in a standard biofilm and in biofilms aerated from a membrane side.

Biofilms↗
PubMed2002

Association between bone loss in periodontal disease and polymorphism of N-acetyltransferase (NAT2).

BACKGROUND: The individual susceptibility to periodontal disease is probably the result of an interaction of multiple genetic and environmental influences. Polymorphism of the N-acetyltransferase (NAT 2) modifies the individual susceptibility to toxicity from certain therapeutic drugs or heterocyclic amines including substances from cigarette smoke. Subjects are to be classified as 'slow' or 'rapid' acetylators according to how fast their bodies metabolise such xenobiotics. Differences in their ability to detoxify these substances may contribute to an increased risk for periodontitis in subjects exposed to cigarette smoke or other xenobiotics. OBJECTIVE: The purpose of this study was to assess whether the NAT2 genotype is a risk factor for periodontal disease in Caucasian patients suffering from adult periodontitis. MATERIAL AND METHODS: 154 Caucasian subjects were assigned to one of the 3 groups: no, moderate, and severe periodontal disease based on bone and attachment loss. In all subjects, genotyping for mutations on the N-acetyltransferase (NAT2) gene was performed by means of PCR and RFLP analysis. RESULTS: Comparison of frequency distribution of NAT2 acetylation types between the most diseased group and not or moderately affected subjects showed a tendency to over-representation of slow acetylators with severe disease. When using bone loss as measure of periodontitis, this over-representation shows a significant association with the disease (odds ratio=2.13, p=0.025). In the logistic regression analysis, adjusted for age and smoking, NAT2 slow phenotype was significantly associated with the severity of bone loss, the odds ratio being 2.09 (95% C.I. 1.02-4.26, p=0.043). In a case-control analysis (controlled for smoking, gender and age) mean bone loss showed a significant difference between the 2 NAT2-type groups (Mann-Whitney test p=0.041). CONCLUSION: The data suggest that the slow acetylator phenotype may be associated with a higher risk of periodontitis, especially in smokers. Possible explanations regarding the mechanism are discussed; however, such attempts are highly speculative at this time.

Adult↗
PubMed1983

Cognitive aspects of splitting and libidinal object constancy.

Features of normal cognitive development during the preoperational period have been described and interrelated with features of the rapprochement subphase of the separation-individuation process and with the beginning of libidinal object constancy. Specifically, aspects of preoperational thought have been shown to be consistent with and to complement the psychoanalytic developmental understanding of the child's renewed fear of object loss during rapprochement, of splitting, and of the "integration" of split object representations. The cognitive processes of centering and decentering have been shown to be central to the phenomena discussed.

Affect↗
PubMed2003

The influence of visual reference on stance and walking on a moving surface.

BACKGROUND: It is apparent that visual information is used in maintaining stable posture and ambulating throughout the stationary world. Considerable previous research has indicated that significant perturbations of posture can be induced with a shift in the entire visual scene. In motion environments, it is assumed that posture and ambulatory ability are controlled more by vestibulo-spinal reflexes, but the role of visual reference has not been extensively studied. METHOD: In the present study, the frequency of motion-induced interruptions (MIIs) under conditions which did and did not provide a stable visual reference were compared. Subjects were tested on a motion platform driven by a simulated ship-motion profile. Two independent observers recorded MIIs for standing and walking under two conditions. In one, the subjects were allowed to see the walls and ceiling of the stationary test cubicle that housed the motion platform. In the other, curtains attached to the motion platform prevented this view. Force plate recordings were also obtained during the standing tasks. RESULT: Observers reported significantly more MIIs, and force plate recordings indicated more postural instability under the condition involving curtains. CONCLUSIONS: These results suggest that manipulations, such as artificial horizons, that provide stable visual representations of the static environment within which the motion occurs may provide important health and safety measures for individuals working in modern vehicular conveyances.

Adaptation, Physiological↗
PubMed1981

The area of faith in Winnicott, Lacan and Bion.

The area of faith is distinguishable from operations which primarily emphasize ego mastery and introjection-internalization processes. Faith is implicit in Winnicott's transitional experiencing and carried forward in object usage. In Bion faith is linked with openness to O or the (unknowable) ultimate reality of a session and is the operative principle of the psychoanalytic attitude. This paper emphasizes the play of faith in Winnicott's object usage and Bion's O. A certain faith is also required to tolerate the movement of meaning in Lacan's Symbolic order. Faith as a fundamental dimension is in tension with the defensive use of mastery and introjective-projective representational networks. In its various forms this complex tension is part of the structure of human life and constitutes the arena in which faith may evolve.

Consciousness↗