542 research outputs found

    Gate-tunable band structure of the LaAlO3_3-SrTiO3_3 interface

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    The 2-dimensional electron system at the interface between LaAlO3_{3} and SrTiO3_{3} has several unique properties that can be tuned by an externally applied gate voltage. In this work, we show that this gate-tunability extends to the effective band structure of the system. We combine a magnetotransport study on top-gated Hall bars with self-consistent Schr\"odinger-Poisson calculations and observe a Lifshitz transition at a density of 2.9×10132.9\times10^{13} cm−2^{-2}. Above the transition, the carrier density of one of the conducting bands decreases with increasing gate voltage. This surprising decrease is accurately reproduced in the calculations if electronic correlations are included. These results provide a clear, intuitive picture of the physics governing the electronic structure at complex oxide interfaces.Comment: 14 pages, 4 figure

    Stability of stationary velocity profiles in fiber spinning

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    Quality assessment of surgical disc samples discriminates human annulus fibrosus and nucleus pulposus on tissue and molecular level

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    A discrimination of the highly specialised annulus fibrosus (AF) and nucleus pulposus (NP) cells in the mature human intervertebral disc (IVD) is thus far still not possible in a reliable way. The aim of this study was to identify molecular markers that distinguish AF and NP cells in human disc tissue using microarray analysis as a screening tool. AF and NP samples were obtained from 28 cervical discs. First, all samples underwent quality sorting using two novel scoring systems for small-sized disc tissue samples including macroscopic, haptic and histological evaluation. Subsequently, samples with clear disc characteristics of either AF or NP that were free from impurities of foreign tissue (IVD score) and with low signs of disc degeneration on cellular level (DD score) were selected for GeneChip analysis (HGU1332P). The 11 AF and 9 NP samples showed distinctly different genome-wide transcriptomes. The majority of differentially expressed genes (DEGs) could be specifically assigned to the AF, whereas no DEG was exclusively expressed in the NP. Nevertheless, we identified 11 novel marker genes that clearly distinguished AF and NP, as confirmed by quantitative gene expression analysis. The novel established scoring systems and molecular markers showed the identity of AF and NP in disc starting material and are thus of great importance in the quality assurance of cell-based therapeutics in regenerative treatment of disc degeneration

    Acetate and Butyrate Improve β-cell Metabolism and Mitochondrial Respiration under Oxidative Stress

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    Islet dysfunction mediated by oxidative and mitochondrial stress contributes to the development of type 1 and 2 diabetes. Acetate and butyrate, produced by gut microbiota via fermentation, have been shown to protect against oxidative and mitochondrial stress in many cell types, but their effect on pancreatic β-cell metabolism has not been studied. Here, human islets and the mouse insulinoma cell line MIN6 were pre-incubated with 1, 2, and 4 mM of acetate or butyrate with and without exposure to the apoptosis inducer and metabolic stressor streptozotocin (STZ). Both short-chain fatty acids (SCFAs) enhanced the viability of islets and β-cells, but the beneficial effects were more pronounced in the presence of STZ. Both SCFAs prevented STZ-induced cell apoptosis, viability reduction, mitochondrial dysfunction, and the overproduction of reactive oxygen species (ROS) and nitric oxide (NO) at a concentration of 1 mM but not at higher concentrations. These rescue effects of SCFAs were accompanied by preventing reduction of the mitochondrial fusion genes MFN, MFN2, and OPA1. In addition, elevation of the fission genes DRP1 and FIS1 during STZ exposure was prevented. Acetate showed more efficiency in enhancing metabolism and inhibiting ROS, while butyrate had less effect but was stronger in inhibiting the SCFA receptor GPR41 and NO generation. Our data suggest that SCFAs play an essential role in supporting β-cell metabolism and promoting survival under stressful conditions. It therewith provides a novel mechanism by which enhanced dietary fiber intake contributes to the reduction of Western diseases such as diabetes

    A Reconsideration of the Self-Compassion Scale's Total Score:Self-Compassion versus Self-Criticism

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    The Self-Compassion Scale (SCS) is currently the only self-report instrument to measure self-compassion. The SCS is widely used despite the limited evidence for the scale's psychometric properties, with validation studies commonly performed in college students. The current study examined the factor structure, reliability, and construct validity of the SCS in a large representative sample from the community. The study was conducted in 1,736 persons, of whom 1,643 were included in the analyses. Besides the SCS, data was collected on positive and negative indicators of psychological functioning, as well as on rumination and neuroticism. Analyses included confirmatory factor analyses (CFA), exploratory factor analyses (EFA), and correlations. CFA showed that the SCS's proposed six-factor structure could not be replicated. EFA suggested a two-factor solution, formed by the positively and negatively formulated items respectively. Internal consistency was good for the two identified factors. The negative factor (i.e., sum score of the negatively formulated items) correlated moderately to strongly to negative affect, depressive symptoms, perceived stress, as well as to rumination and neuroticism. Compared to this negative factor, the positive factor (i.e., sum score of the positively formulated items) correlated weaker to these indicators, and relatively more strongly to positive affect. Results from this study do not justify the common use of the SCS total score as an overall indicator of self-compassion, and provide support for the idea, as also assumed by others, that it is important to make a distinction between self-compassion and self-criticism.</p

    The role of mindfulness and self-compassion in depressive symptoms and affect:A Comparison between Cancer Patients and Healthy Controls

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    Objectives: Mindfulness and self-compassion are related to psychological well-being and can be regarded as personal resources. It is, however, unclear whether these resources are always beneficial (direct effect) or only in stressful circumstances (buffer effect). We therefore examined whether mindfulness and self-compassion are equally or more strongly related to depressive symptoms and affect in cancer patients, compared to healthy controls. Methods: Using a case-control design, 245 cancer patients were matched to 245 healthy controls (without chronic somatic comorbidities). Both groups filled out questionnaires concerning mindfulness (Five Facet Mindfulness Questionnaire), self-compassion (Self-Compassion Scale), depressive symptoms (Center for Epidemiologic Studies Depression Scale), and affect (Positive and Negative Affect Scale). Using correlation and regression analyses, we examined within both groups the associations for mindfulness (i.e., total score and five facets) and self-compassion (i.e., total score, two factors and six facets) with depressive symptoms and affect. Results: Mindfulness and self-compassion were equally strongly related to depressive symptoms and affect in cancer patients versus healthy controls. Mindfulness facets Act with awareness and Non-judgment were strongly related to depressive symptoms, negative affect, and the negative self-compassion factor. In contrast, mindfulness facets Describe and Observe were strongly related to positive affect and the positive self-compassion factor. When distinguishing the six self-compassion facets, Isolation and Mindfulness were strongly related to depressive symptoms, Over-identification to negative affect, and Mindfulness to positive affect. Conclusions: Results suggest that mindfulness and self-compassion are basic human personal resources associated with psychological functioning, regardless of the presence or absence of stressful life experiences

    Inclusion of extracellular matrix molecules and necrostatin-1 in the intracapsular environment of alginate-based microcapsules synergistically protects pancreatic β cells against cytokine-induced inflammatory stress

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    Immunoisolation of pancreatic islets in alginate-based microcapsules is a promising approach for grafting of islets in absence of immunosuppression. However, loss and damage to the extracellular matrix (ECM) during islet isolation enhance susceptibility of islets for inflammatory stress. In this study, a combined strategy was applied to reduce this stress by incorporating ECM components (collagen type IV/RGD) and necroptosis inhibitor, necrostatin-1 (Nec-1) in alginate-based microcapsules in vitro. To demonstrate efficacy, viability and function of MIN6 β-cells and human islets in capsules with collagen type IV/RGD and/or Nec-1 was investigated in presence and absence of IL-1β, IFN-γ and TNF-α. The combination of collagen type IV/RGD and Nec-1 had higher protective effects than the molecules alone. Presence of collagen type IV/RGD and Nec-1 in the intracapsular environment reduced cytokine-induced overproduction of free radical species and unfavorable shifts in mitochondrial dynamics. In addition, the ECM components collagen type IV/RGD prevented a cytokine induced suppression of the FAK/Akt pathway. Our data indicate that the inclusion of collagen type IV/RGD and Nec-1 in the intracapsular environment prevents islet-cell loss when exposed to inflammatory stress, which might contribute to higher survival of β-cells in the immediate period after transplantation. This approach of inclusion of stress reducing agents in the intracapsular environment of immunoisolating devices may be an effective way to enhance the longevity of encapsulated islet grafts. Statement of significance: Islet-cells in immunoisolated alginate-based microcapsules are very susceptible to inflammatory stress which impacts long-term survival of islet grafts. Here we show that incorporation of ECM components (collagen type IV/RGD) and necrostatin-1 (Nec-1) in the intracapsular environment of alginate-based capsules attenuates this susceptibility and promotes islet-cell survival. This effect induced by collagen type IV/RGD and Nec-1 was probably due to lowering free radical production, preventing mitochondrial dysfunction and by maintaining ECM/integrin/FAK/Akt signaling and Nec-1/RIP1/RIP3 signaling. Our study provides an effective strategy to extend longevity of islet grafts which might be of great potential for future clinical application of immunoisolated cells
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