Sign-tunable anomalous Hall effect induced by two-dimensional symmetry-protected nodal structures in ferromagnetic perovskite oxide thin films

Magnetism and spin-orbit coupling (SOC) are two quintessential ingredients underlying novel topological transport phenomena in itinerant ferromagnets. When spin-polarized bands support nodal points/lines with band degeneracy that can be lifted by SOC, the nodal structures become a source of Berry curvature; this leads to a large anomalous Hall effect (AHE). Contrary to three-dimensional systems that naturally host nodal points/lines, two-dimensional (2D) systems can possess stable nodal structures only when proper crystalline symmetry exists. Here we show that 2D spin-polarized band structures of perovskite oxides generally support symmetry-protected nodal lines and points that govern both the sign and the magnitude of the AHE. To demonstrate this, we performed angle-resolved photoemission studies of ultrathin films of SrRuO$_3$, a representative metallic ferromagnet with SOC. We show that the sign-changing AHE upon variation in the film thickness, magnetization, and chemical potential can be well explained by theoretical models. Our study is the first to directly characterize the topological band structure of 2D spin-polarized bands and the corresponding AHE, which could facilitate new switchable devices based on ferromagnetic ultrathin films

Electronic band structure of (111) SrRuO3SrRuO_{3} thin film−-an angle-resolved photoemission spectroscopy study

We studied the electronic band structure of pulsed laser deposition (PLD) grown (111)-oriented SrRuO$_3$ (SRO) thin films using \textit{in situ} angle-resolved photoemission spectroscopy (ARPES) technique. We observed previously unreported, light bands with a renormalized quasiparticle effective mass of about 0.8$m_{e}$. The electron-phonon coupling underlying this mass renormalization yields a characteristic "kink" in the band dispersion. The self-energy analysis using the Einstein model suggests five optical phonon modes covering an energy range 44 to 90 meV contribute to the coupling. Besides, we show that the quasiparticle spectral intensity at the Fermi level is considerably suppressed, and two prominent peaks appear in the valance band spectrum at binding energies of 0.8 eV and 1.4 eV, respectively. We discuss the possible implications of these observations. Overall, our work demonstrates that high-quality thin films of oxides with large spin-orbit coupling can be grown along the polar (111) orientation by the PLD technique, enabling \textit{in situ} electronic band structure study. This could allow for characterizing the thickness-dependent evolution of band structure of (111) heterostructures$-$a prerequisite for exploring possible topological quantum states in the bilayer limit

CXCR6, a Newly Defined Biomarker of Tissue-Specific Stem Cell Asymmetric Self-Renewal, Identifies More Aggressive Human Melanoma Cancer Stem Cells

Background: A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells. Recent investigations of a variety of tumor types have shown that phenotypically identifiable and isolable subfractions of cells possess the tumor-forming ability. In the present paper, using two lineage-related human melanoma cell lines, primary melanoma line IGR39 and its metastatic derivative line IGR37, two main observations are reported. The first one is the first phenotypic evidence to support the origin of melanoma cancer stem cells (CSCs) from mutated tissue-specific stem cells; and the second one is the identification of a more aggressive subpopulation of CSCs in melanoma that are CXCR6+. Conclusions/Significance: The association of a more aggressive tumor phenotype with asymmetric self-renewal phenotype reveals a previously unrecognized aspect of tumor cell physiology. Namely, the retention of some tissue-specific stem cell attributes, like the ability to asymmetrically self-renew, impacts the natural history of human tumor development. Knowledge of this new aspect of tumor development and progression may provide new targets for cancer prevention and treatment

A Resource for Discovering Specific and Universal Biomarkers for Distributed Stem Cells

Specific and universal biomarkers for distributed stem cells (DSCs) have been elusive. A major barrier to discovery of such ideal DSC biomarkers is difficulty in obtaining DSCs in sufficient quantity and purity. To solve this problem, we used cell lines genetically engineered for conditional asymmetric self-renewal, the defining DSC property. In gene microarray analyses, we identified 85 genes whose expression is tightly asymmetric self-renewal associated (ASRA). The ASRA gene signature prescribed DSCs to undergo asymmetric self-renewal to a greater extent than committed progenitor cells, embryonic stem cells, or induced pluripotent stem cells. This delineation has several significant implications. These include: 1) providing experimental evidence that DSCs in vivo undergo asymmetric self-renewal as individual cells; 2) providing an explanation why earlier attempts to define a common gene expression signature for DSCs were unsuccessful; and 3) predicting that some ASRA proteins may be ideal biomarkers for DSCs. Indeed, two ASRA proteins, CXCR6 and BTG2, and two other related self-renewal pattern associated (SRPA) proteins identified in this gene resource, LGR5 and H2A.Z, display unique asymmetric patterns of expression that have a high potential for universal and specific DSC identification

SRPA genes and their role in ASC functions

Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2006."June 2006."Includes bibliographical references (leaves 175-187).Molecular markers for adult stem cells (ASCs) are highly demanded for research and clinical applications. The development of specific molecular markers for ASCs has been difficult mainly due to the technical barriers in the identification and isolation of rare ASCs. Previously, reported transcriptional profiling studies for defining molecular features of ASCs were compromised by the use of impure ASC preparations. Thesis for this research was that the study of asymmetric self-renewal, a defining property of ASCs, might provide key clues to understanding ASC function and lead to discovery of novel molecular markers for ASCs. Fifty two self-renewal pattern associated (SRPA) genes were identified by cDNA microarray analysis with cell culture models whose self-renewal pattern could be reversibly regulated, instead of using heterogeneous ASC-enriched populations. From evaluation of whole genome transcript levels to expand the SRPA gene pool, 543 SRPA genes were discovered. Both microarray studies showed that asymmetric self-renewal associated (ASRA) genes were highly represented in ASC-enriched populations but not in embryonic stem cells. The SRPA gene expression signature successfully distinguished isolated ASC-enriched populations from non-stem cell populations by principal component analysis (PCA).(cont.) The SRPA gene signature clustered and classified putative epidermal stem cell-enriched populations better than reported stemness gene signatures in PCA. Therefore, gene microarray analyses for studying self-renewal pattern per se confirmed for the first time that asymmetric self-renewal is an essential molecular feature of ASCs in vivo. Chromosome mapping of the SRPA genes identified two SRPA chromosome gene cluster regions. One chromosome cluster contained primarily ASRA genes, whereas the other contained primarily symmetric self-renewal associated (SSRA) genes. These two SRPA chromosome cluster regions are frequently rearranged or deleted in particular human cancers. Functional and expression analysis of several selected ASRA and SSRA gene-encoded proteins implicated them in control of asymmetric self-renewal and non-random chromosome co-segregation, respectively. Moreover, one plasma membrane bound ASRA protein, CXCR6, had properties of one of the most specific molecular markers for ASCs described to date. In conclusion, this research strongly supported the precept that asymmetric self-renewal is a unique molecular feature for understanding ASCs, their relation to cancer, their unique function, and for their eventual exclusive identification.by Minsoo Noh.Ph.D

Bavachin from Psoralea corylifolia Improves Insulin-Dependent Glucose Uptake through Insulin Signaling and AMPK Activation in 3T3-L1 Adipocytes

The fruit of Psoralea corylifolia L. (Fabaceae) (PC), known as “Bo-Gol-Zhee” in Korea has been used as traditional medicine. Ethanol and aqueous extracts of PC have an anti-hyperglycemic effect by increasing plasma insulin levels and decreasing blood glucose and total plasma cholesterol levels in type 2 diabetic rats. In this study, we purified six compounds from PC and investigated their anti-diabetic effect. Among the purified compounds, bavachin most potently accumulated lipids during adipocyte differentiation. Intracellular lipid accumulation was measured by Oil Red-O (ORO) cell staining to investigate the effect of compounds on adipogenesis. Consistently, bavachin activated gene expression of adipogenic transcriptional factors, proliferator-activated receptorγ (PPARγ) and CCAAT/enhancer binding protein-α (C/EBPα). Bavachin also increased adiponectin expression and secretion in adipocytes. Moreover, bavachin increased insulin-induced glucose uptake by differentiated adipocytes and myoblasts. In differentiated adipocytes, we found that bavachin enhanced glucose uptake via glucose transporter 4 (GLUT4) translocation by activating the Akt and 5′AMP-activated protein kinase (AMPK) pathway in the presence or absence of insulin. These results suggest that bavachin from Psoralea corylifolia might have therapeutic potential for type 2 diabetes by activating insulin signaling pathways

A customizable view for Web-based STEP data

A key to successful deployment of concurrent engineering is sharing of product data.We propose a new approach to sharing the product data on the Web.In a concurrent engineering environment, each participant who is as disparate as design, production, and purchase requires a different view depending on their roles and interests.Ther efore, it is very important to support the individuals data requirements. Our system supports views for custom-defined functionalities as well as predefined standardized views.The system allows individual users to design their own views.An important consideration is given to improve the system performance by maintaining indexes.This research was supported by Korea Science and Engineering Foundation (KOSEF), grant no.97-02-00-09-01-3, and carried out at the Research Institute of Engineering Science at Seoul National University

Serratus anterior plane block with ultrasound-guided hydrodissection for lateral thoracic pain caused by long thoracic nerve neuropathy – A case report -

Background Long thoracic nerve (LTN) neuropathy occasionally occurs in young people who engage in various sports. It may have a traumatic or non-traumatic etiology. The landmark manifestation of LTN neuropathy is scapular winging; however, it can also occur without scapular winging and specific magnetic resonance imaging findings. Case An 18-year-old male complained of right-sided lateral chest pain for 7 months. He was treated with medication, trigger point injection, and physical therapy but showed no improvement. Electromyelogram findings suggested LTN neuropathy in the right lateral chest. We performed a serratus anterior (SA) plane block with ultrasound (US)-guided hydrodissection and achieved pain relief. Conclusions We report the successful treatment of LTN neuropathy with an SA plane block and US-guided hydrodissection

Sparse feature selection identifies H2A.Z as a novel, pattern-specific biomarker for asymmetrically self-renewing distributed stem cells

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