POS0446 Arp2/3 AS A Lasp1 INTERACTION PARTNER REGULATES CELL-TO-CELL CONTACT FORMATION OF FIBROBLAST-LIKE SYNOVIOCYTES IN RA

Background

In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) undergo a stable transformation resulting in an aggressive phenotype mediating cartilage damage by increased levels of adhesion molecules. In this context, Lasp1 and the Arp2/3 complex are of interest because they modulate actin organization and focal adhesion turnover.

Objectives

In this study, the effects of Arp2/3 on cadherin-11 mediated cell-to-cell contact formation have been investigated using the arthritic hTNFtg mouse model.

Methods

Expression levels of Lasp1 and Arp2/3 protein complex were investigated in synovial tissue of wild type (wt) and hTNFtg hind paws by immunohistochemistry. Primary FLS were analysed, respectively and co-immunoprecipitation experiments were performed. In addition, lasp1-/- mice were interbred with hTNFtg animals and offspring were evaluated for disease progression and joint destruction. To further study the role of Arp2/3 in the function of the cadherin-11 adhesion complex, the effects of an Arp2/3 inhibitor (CK666) on cell-to-cell contact formation in FLS derived from hTNFtg and lasp1-/-hTNFtg mice were investigated by stainings. To assess signaling pathway activation, cells were stimulated with the growth factor PDGF.

Results

Upregulated Lasp1 levels were found in synovial tissue and FLS of hTNFtg compared to wt mice. Assays showed that Arp2/3 is part of the adherens junction (AJ) machinery in FLS although Arp2/3 expression levels were not changed between the genotypes. In vivo evaluation of lasp1-/-hTNFtg mice revealed a milder arthritis score, less cartilage degradation and reduced FLS attachment to articular cartilage compared to hTNFtg mice. In vitro, the loss of Lasp1 led to clear alterations in AJ arrangement indicated by altered β-catenin pattern. As expected, β-catenin expression was mainly located at adhesion sites between adjacent cells. In hTNFtg FLS, these structures were characterized by a zipper-like pattern. In contrast, these structures were disrupted in lasp1-/-hTNFtg FLS. Interestingly, CK666 induced zipper-like structures in hTNFtg FLS comparable to the pattern found in lasp1-/-hTNFtg cells. Furthermore, lasp1-/-hTNFtg FLS showed decreased Src phosphorylation following PDGF stimulation in comparison to hTNFtg FLS.

Conclusion

Lasp1 represents an interesting target involved in RA-caused joint destruction, because its loss results in significantly reduced cartilage destruction and altered FLS contacts mediated by Arp2/3.

Disclosure of Interests

None declared.

AB0089 INTEGRIN α11β1 DEFICIENCY AFFECTS THE COURSE OF DISEASE IN THE ARTHRITIC hTNFtg MOUSE

Background

Rheumatoid arthritis (RA) is an autoimmune disorder conducted by fibroblast-like synoviocytes (FLS), which acquire a tumor-like phenotype causing irreversible cartilage and bone damage. FLS attache to the extracellular matrix (ECM) invading the joints, a process mediated by integrins. Integrins are transmembrane proteins regulating several cell functions like cell migration, cell proliferation, tissue invasion and cytokine expression – key mechanisms during the pathogenesis of RA. The collagen-binding Integrin α11β1 (α11) is expressed on FLS mediating their adhesion to the ECM and in this study, we analysed its implication in RA.

Objectives

We examined the pathogenesis of RA in a murine arthritis model (hTNFtg) lacking α11 to analyze its contribution to joint destructions and the disease course.

Methods

Expression levels of α11 were analysed by Western Blot and immunofluorescence staining using FLS and synovial tissue of patients with RA and hTNFtg mice in comparison to their respective controls. Crossbreeding hTNFtg with α11 deficient (itga11-/-) mice enabled us to evaluate arthritis progression using clinical parameters like paw swelling and grip strength. Inflammation area and cartilage damage were quantified by histomorphological techniques such as toluidine blue staining of in paraffin-embedded sections from hind paws. Bone erosion was visualized by µCT imaging and quantification of the bone volume in the tarsal bone area.

Results

High expression levels of α11 could be detected in hTNFtg and human RA samples in comparison to their controls. The progression of arthritis in itga11-/-hTNFtg was slower and less severe in comparison to hTNFtg mice, visible in a stronger grip strength and reduced paw swelling at the same timepoint. The histomorphology analysis confirmed these results showing higher cartilage area (3.21% vs 5.22%, p < 0.05), less cartilage destruction (51.73% vs 35.65%, p < 0.05) and reduced inflammation (28.28% vs 12.00%) in itga11-/-hTNFtg compared to the hTNFtg mice. Also, the quantification of the tarsal bone area revealed a higher bone volume (77.94% vs 84.92%, p < 0.01) in itga11-/-hTNFtg.

Conclusion

This study showed the important role of α11 in the progression of joint destruction as it is highly expressed in hTNFtg mice and in human synovial tissue of patients with RA. Its absence results in less severe arthritis progression and joint destruction, therefore a possible and interesting target for RA treatment.

Disclosure of Interests

None declared

Ballistic Graphene Cooper Pair Splitter

We report an experimental study of a Cooper pair splitter based on ballistic graphene multiterminal junctions. In a two transverse junction geometry, namely the superconductor-graphene-superconductor and the normal metal-graphene-normal metal, we observe clear signatures of Cooper pair splitting in the local as well as nonlocal electronic transport measurements. Our experimental data can be very well described by our beam splitter model. These results open up possibilities to design new entangled state detection experiments using ballistic Cooper pair splitters.

Creation of equal-spin triplet superconductivity at the Al/EuS interface

In conventional superconductors, electrons of opposite spins are bound into Cooper pairs. However, when the superconductor is in contact with a non-uniformly ordered ferromagnet, an exotic type of superconductivity can appear at the interface, with electrons bound into three possible spin-triplet states. Triplet pairs with equal spin play a vital role in low-dissipation spintronics. Despite the observation of supercurrents through ferromagnets, spectroscopic evidence for the existence of equal-spin triplet pairs is still missing. Here we show a theoretical model that reveals a characteristic gap structure in the quasiparticle density of states which provides a unique signature for the presence of equal-spin triplet pairs. By scanning tunnelling spectroscopy we measure the local density of states to reveal the spin configuration of triplet pairs. We demonstrate that the Al/EuS interface causes strong and tunable spin-mixing by virtue of its spin-dependent transmission.

Andreev bound states at spin-active interfaces

Andreev bound states are ubiquitous in superconducting hybrid structures. They are formed near impurities, in Josephson junctions, in vortex cores and at interfaces. At spin-active superconductor-ferromagnet interfaces, Andreev bound states are formed due to spin-dependent scattering phases. Spin-dependent phase shifts are an important ingredient for the generation of triplet Cooper pairs in superconductor-ferromagnet hybrid structures. Spectroscopy of Andreev bound states is a powerful probe of superconducting order parameter symmetry, as well as spin-dependent interface scattering and the triplet proximity effect.This article is part of the theme issue 'Andreev bound states'.

Spin manipulation in nanoscale superconductors

The interplay of superconductivity and magnetism in nanoscale structures has attracted considerable attention in recent years due to the exciting new physics created by the competition of these antagonistic ordering phenomena, and the prospect of exploiting this competition for superconducting spintronics devices. While much of the attention is focused on spin-polarized supercurrents created by the triplet proximity effect, the recent discovery of long range quasiparticle spin transport in high-field superconductors has rekindled interest in spin-dependent nonequilibrium properties of superconductors. In this review, the experimental situation on nonequilibrium spin injection into superconductors is discussed, and open questions and possible future directions of the field are outlined.

Observation of Thermoelectric Currents in High-Field Superconductor-Ferromagnet Tunnel Junctions

We report on the experimental observation of spin-dependent thermoelectric currents in superconductor-ferromagnet tunnel junctions in high magnetic fields. The thermoelectric signals are due to a spin-dependent lifting of the particle-hole symmetry, and are found to be in excellent agreement with recent theoretical predictions. The maximum Seebeck coefficient inferred from the data is about -100  μV/K, much larger than commonly found in metallic structures. Our results directly prove the coupling of spin and heat transport in high-field superconductors.

Charge and spin transport in mesoscopic superconductors

BACKGROUND

Non-equilibrium charge transport in superconductors has been investigated intensely in the 1970s and 1980s, mostly in the vicinity of the critical temperature. Much less attention has been paid to low temperatures and the role of the quasiparticle spin.

RESULTS

We report here on nonlocal transport in superconductor hybrid structures at very low temperatures. By comparing the nonlocal conductance obtained by using ferromagnetic and normal-metal detectors, we discriminate charge and spin degrees of freedom. We observe spin injection and long-range transport of pure, chargeless spin currents in the regime of large Zeeman splitting. We elucidate charge and spin transport by comparison to theoretical models.

CONCLUSION

The observed long-range chargeless spin transport opens a new path to manipulate and utilize the quasiparticle spin in superconductor nanostructures.

Long-range spin-polarized quasiparticle transport in mesoscopic Al superconductors with a Zeeman splitting

We report on nonlocal transport in multiterminal superconductor-ferromagnet structures, which were fabricated by means of e-beam lithography and shadow evaporation techniques. In the presence of a significant Zeeman splitting of the quasiparticle states, we find signatures of spin transport over distances of several μm, exceeding other length scales such as the coherence length, the normal-state spin-diffusion length, and the charge-imbalance length. The relaxation length of the spin signal shows a nearly linear increase with magnetic field, hinting at a freeze-out of relaxation by the Zeeman splitting. We propose that the relaxation length is given by the recombination length of the quasiparticles rather than a renormalized spin-diffusion length.

Observation of Andreev bound states at spin-active interfaces

We report on high-resolution differential conductance experiments on nanoscale superconductor-ferromagnet tunnel junctions with ultrathin oxide tunnel barriers. We observe subgap conductance features that are symmetric with respect to bias and shift according to the Zeeman energy with an applied magnetic field. These features can be explained by resonant transport via Andreev bound states induced by spin-active scattering at the interface. From the energy and Zeeman shift of the bound states, both the magnitude and sign of the spin-dependent interfacial phase shifts between spin-up and spin-down electrons can be determined. These results contribute to the microscopic insight into the triplet proximity effect at spin-active interfaces.

Surface stress-charge response of a (111)-textured gold electrode under conditions of weak ion adsorption

We report a cantilever bending investigation into the variation of surface stress, f, with surface charge density, q, for (111)-textured thin films of gold in aqueous NaF and HClO 4. The graphs of f(q) are highly linear, and the surface stress-charge coefficients, d f/d q, are -1.95 V for 7 mM NaF and -2.0 V for 10 mM HClO 4 near the potential of zero charge. These values exceed some previously published experimental data by a factor of 2, but they agree with recent ab initio calculations of the surface stress-charge response of gold in vacuum.

Evidence for crossed Andreev reflection in superconductor-ferromagnet hybrid structures

We have measured the nonlocal resistance of aluminum-iron spin-valve structures fabricated by e-beam lithography and shadow evaporation. The sample geometry consists of an aluminum bar with two or more ferromagnetic wires forming point contacts to the aluminum at varying distances from each other. In the normal state of aluminum, we observe a spin-valve signal which allows us to control the relative orientation of the magnetizations of the ferromagnetic contacts. In the superconducting state, at low temperatures and excitation voltages well below the gap, we observe a spin-dependent nonlocal resistance which decays on a smaller length scale than the normal-state spin-valve signal. The sign, magnitude, and decay length of this signal are consistent with predictions made for crossed Andreev reflection.

[A questionnaire for assessment of "temprament in early childhood" as judged by parents]

OBJECTIVES

This study assesses a German version of Rothbart's Infant Behavior Questionnaire for the internal consistency, inter-correlations and stability of the scales. Associations between the scales with maternal depression and anxiety are analyzed.

METHODS

Independent samples of infants aged 6 to 8 months and 10 to 12 months (n = 149, respectively n = 109) and their mothers were studied. A longitudinal study of a sample of 101 mother-infant pairs was carried out at the infant's age of 4, 8 and 12 months.

RESULTS

The internal consistency and independence of the five scales on the questionnaire are satisfactory. The stability coefficients correspond to a good degree to those of the American version of the IBQ scales.

CONCLUSIONS

Thus a German version is now available that can be used in research and practice to measure the features of early childhood temperament by parental report.

Driving current through single organic molecules

We investigate electronic transport through two types of conjugated molecules. Mechanically controlled break junctions are used to couple thiol end groups of single molecules to two gold electrodes. Current-voltage characteristics ( IVs) of the metal-molecule-metal system are observed. These IVs reproduce the spatial symmetry of the molecules with respect to the direction of current flow. We hereby unambiguously detect an intrinsic property of the molecule and are able to distinguish the influence of both the molecule and the contact to the metal electrodes on the transport properties of the compound system.

Infants with atopic dermatitis: maternal hopelessness, child-rearing attitudes and perceived infant temperament

BACKGROUND

Atopic dermatitis (AD) is a common disease of childhood. It frequently starts in the first year of life. There is agreement on the existence of psychological influences on this disease. Although some studies in this field examine aspects of the parent-child relationship, studies concerning early infancy are very rare. The present study was conducted in order to find out whether maternal characteristics relevant to the mother-infant relationship, i.e. depressiveness/hopelessness, child-rearing attitudes and perceived infant behaviour, associated with infant AD.

METHODS

Two cohorts (3- to 4-month- and 10- to 12-month-old infants), each with 20 infants suffering from AD, and 20 healthy infants were recruited. AD infants were further divided into subgroups according to the diagnostic criteria: atopic family history, itching and characteristic locations of eczema. After a paediatric examination of the infant, mothers completed standardized questionnaires concerning depressiveness/hopelessness, child-rearing attitudes and perception of infant behaviour.

RESULTS

Varying with different diagnostic features of the infants' AD, mothers of AD infants described themselves as more depressive/hopeless, as more anxious/overprotective and characterized their infant as less frequently positive and more frequently negative in its emotional behaviour compared to the control group.

CONCLUSION

The results underline the importance of psychological support for mothers of infants with AD.

[Effects of significantly increased perinatal risks on developmental status in adolescence]

In a 13-years-catamnesis a sample of 50 children with severe perinatal risks was assessed with regard to their physical, cognitive and behavioral development; selective drop-outs were analysed. In accordance with the results of other prospective studies there are deficits in visual-motor functioning, higher rates of somatic complaints, social withdrawal and attention deficits; a large number of these children attend special schools. The study presents predicative relations between risk factors of birth-time and the developmental status at youth. In comparison with typical single risks (e.g. gestational age or respiratory distress syndrome) a complex index for the perinatal risk, the so-called birth-optimality offers no substantial advantage. A significant influence of social factors is shown for school achievement. Children of fathers with higher educational level are attending schools of a higher grade. The combination of biological and social factors improves the reliability of developmental prognosis; the Mental Developmental Index of the Bayley Scales of Infant Development provides additional prognostic accuracy. For compensating developmental disadvantages especially parents with lower educational level should be informed about beneficial care. Even children of these families, who scored low in early cognitive assessments should receive early intervention or therapeutic support.

Infants with "Colic"-mothers' perspectives on the crying problem

OBJECTIVES

This study was designed to evaluate relationships between infant crying behavior and fussing behavior and the mother's causal attributions of the crying, her emotional responses to the crying, as well as her later perception of infant temperament.

METHODS

Twenty mothers who presented their 3-9-week-old infants in pediatric practices because of excessive crying ("colic complaint group") and 20 mothers who visited for public preventive screening ("control group") were compared. Mothers kept a "baby diary." A highly structured interview with the mothers was conducted. When the babies were 4 months old, mothers completed a temperament questionnaire. The colic complaint group was subdivided using the Wessel criteria.

RESULTS

Infants from the colic complaint group who did not meet these criteria did not differ from control subjects in any of the parameters derived from the diaries. However, the mothers of this group described significantly heightened negative affect and cognitions of being rejected in response to the crying. In contrast, mothers of infants who conformed to Wessel's definition, and thereby far exceeded the other subjects in crying duration, did not differ from control mothers in respect of the aforementioned feelings and cognitions. Mothers' "negative affect and feelings of being rejected" were associated with the perception of high negative emotionality 4 months later.

CONCLUSION

In regard to the colic problem, attention must be paid not only to the characteristics of the child, but also to aspects of maternal perception and processing of the crying problem.

[Covariation of parental judgments of child behavioral characteristics with a developmental scale and observation of behaviors]

The aim of the present study is the validation of a German questionnaire that was designed to assess "infant temperament" by parental judgement. The questionnaire represents an adaptation of Rothbart's "Infant Behavior Questionnaire" (IBQ). It was studied whether the parental judgements concerning positive emotionality, negative emotionality/irritability, motor activity and soothability of the infant are correlated to corresponding observed child behavior. Furthermore we tried to determine influences of parental characteristics on their judgements. 31 First-born healthy 4 months old infants were observed in their home environment as well as in the video laboratory of our institute. The Bayley Scales of Infant Development (Mental Scale) were applied. The mothers filled in the Temperament Questionnaire and scales to assess maternal depression and anxiety. We yielded the expected significant correlations for the scales measuring positive and negative emotionality, and motor activity with the observed behavioral characteristics of the infants. Independent of these results the mothers' judgements of their infant's positive and negative emotionality was associated with maternal depression. We can therefore conclude that the two scales contain subjective and objective elements that are independent of each other.

[Infantile colic as maternal reason of consulting a pediatrician: characteristics of mother and child]

About 10-20% of infants under four months of age suffer from infantile colic (IC), an excessive screaming behaviour caused by multiple factors. WESSELS et al. (1954) definition is that babies in usually good health and nutritional condition are screaming/whining more than three hours daily, more than three days weekly for no apparent reasons. The question is whether/in what way daily routines of infants concerned differ from normal infants. Mothers of colicky infants (n = 25) and mothers in a control group (n = 25) record characteristics of the mother/child relationship, their assumptions why the child is screaming, care and attention they provide and babies' reactions. For seven days the mothers kept a diary about the babies' behaviour and worked on questionnaires concerning social support received, depressant effects and exhaustion. Interviews about the extent of care provided as well as personal thoughts and emotions were conducted. The "colic group" formed two subgroups: one fulfilling Wessels criteria (Wessel-Koliker; WK), the other more conforming with the "control group" babies though mothers complained about screaming (Non-Wessel-Koliker; NWK). "Colic group"-babies received more attention and care (compared to the "control group" babies), attempts to calm them down frequently failed and mothers in this group reacted less promptly to their babies' screaming. "NWK-group"-mothers strongly tend to attribute the babies' screaming to "meteorism" or "discontent". No differences existed between groups concerning social support, depressant effects and exhaustion. There is a risk that the colic may negatively influence the mother/child interaction beyond three months.

[Neuromotor and cognitive development of high-risk newborn infants at 5 years of age]

A group of 5-year-old children bearing a perinatal neurological risk is divided into subgroups according to the specific courses of their neuromotoric development. Then comparison is made between two of the subgroups consisting of children with a favourable neuromotoric development at the age of 5 and a control-group of healthy born children with regard to the neuromotoric as well as the cognitive development. As a result the children of the two subgroups, whose neuromotoric development in the age of five was comparable to that of the control group, showed a significantly lower performance on a concentration test than those of the control group. Additionally there is also a deficiency within the scope of verbal competence, whereas the level of the performance IQ of the children with perinatal neurological risk is quite comparable with that of the children of the control group.

[The ideal image and sex role norms in the Giessen Test]

This study was intended to test the assumption whether the ideal-image measure within the Giessen-Test reflects the specific personality as hypothesized by psychoanalytic theory or a general norm-orientation. To test this assumptions the items of the Giessen-Test were transformed an submitted to random samples of in- and out-patients. The results clearly indicate that the ideal-image as measured by the Giessen-Test is a general norm-orientation and consists of the dimensions "social-acknowledgement" and "capability of binding". Within the second dimension there seems to be a gender difference. Additional analysis of variance and Cronbachs alpha indicate that differences between in- and out-patients are the result of a possible "curative effect".

[Ontogenesis of affect regulation]

The psychophysiological basis of biological rhythms in human adults and infants is discussed in the present paper. The significance of the influence of hormones on central nervous functions is demonstrated by neurophysiological and psychobiological evidence. Moreover, complex interactions among humoral, immune and central nervous systems referring to biological rhythms, are described.

[Ontogenesis of sleep-wakefulness regulation]

In addition to traditional opinions endogenous sleep factors play an important role in modern concepts concerning sleep-wake regulation. The recent development of neurochemical research including experiments with neuropeptides has modified the classical theories of sleeping and waking. Moreover, the influence of hormones as cortisol or prolactin on neurotransmitters involved in sleep-wake regulation, special problems of the endogenous sleep-rhythms, and the conditions of the ontogenetic development are discussed. In addition, a new concept, the so-called Stimulation theory is described.

[Power, status and valency in healthy and ill partners]

Using the degree of identification and projection (self concept/concept of self as perceived by others--Giessen-test) it was possible to develop a new approach to power, status and valency in couple relationships by means of deriving theoretical probabilities from those three core variables. The anticipated scores were validated using a number of reference scores of typical clinical samples and putting them in relationship to the standardized marital couples.

[A map of dyadic relations in the Giessen Test]

A series of random samples was carried out to validate a new model for diagnosing couple relationships using the Giessen test. The model delineates all theoretically possible types of couple relationships in the course of which individual scores can be compared simultaneously with standard scores. The interpretation is based on a two-dimensional diagram, which is to be understood as a reduction of a more complex structure.