Coexistence of Magnetic Order and Two-dimensional Superconductivity at LaAlO3_3/SrTiO3_3 Interfaces

A two dimensional electronic system with novel electronic properties forms at the interface between the insulators LaAlO$_3$ and SrTiO$_3$. Samples fabricated until now have been found to be either magnetic or superconducting, depending on growth conditions. We combine transport measurements with high-resolution magnetic torque magnetometry and report here evidence of magnetic ordering of the two-dimensional electron liquid at the interface. The magnetic ordering exists from well below the superconducting transition to up to 200 K, and is characterized by an in-plane magnetic moment. Our results suggest that there is either phase separation or coexistence between magnetic and superconducting states. The coexistence scenario would point to an unconventional superconducting phase in the ground state.Comment: 10 pages, 4 figure

Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface

LaAlO3 and SrTiO3 are insulating, nonmagnetic oxides, yet the interface between them exhibits a two-dimensional electron system with high electron mobility,1 superconductivity at low temperatures,2-6 and electric-field-tuned metal-insulator and superconductorinsulator phase transitions.3,6-8 Bulk magnetization and magnetoresistance measurements also suggest some form of magnetism depending on preparation conditions5,9-11 and suggest a tendency towards nanoscale electronic phase separation.10 Here we use local imaging of the magnetization and magnetic susceptibility to directly observe a landscape of ferromagnetism, paramagnetism, and superconductivity. We find submicron patches of ferromagnetism in a uniform background of paramagnetism, with a nonuniform, weak diamagnetic superconducting susceptibility at low temperature. These results demonstrate the existence of nanoscale phase separation as suggested by theoretical predictions based on nearly degenerate interface sub-bands associated with the Ti orbitals.12,13 The magnitude and temperature dependence of the paramagnetic response suggests that the vast majority of the electrons at the interface are localized, and do not contribute to transport measurements.3,6,7 In addition to the implications for magnetism, the existence of a 2D superconductor at an interface with highly broken inversion symmetry and a ferromagnetic landscape in the background suggests the potential for exotic superconducting phenomena.Comment: Edited version to appear in Nature Physic

Exposure to N-Ethyl-N-Nitrosourea in Adult Mice Alters Structural and Functional Integrity of Neurogenic Sites

BACKGROUND: Previous studies have shown that prenatal exposure to the mutagen N-ethyl-N-nitrosourea (ENU), a N-nitroso compound (NOC) found in the environment, disrupts developmental neurogenesis and alters memory formation. Previously, we showed that postnatal ENU treatment induced lasting deficits in proliferation of neural progenitors in the subventricular zone (SVZ), the main neurogenic region in the adult mouse brain. The present study is aimed to examine, in mice exposed to ENU, both the structural features of adult neurogenic sites, incorporating the dentate gyrus (DG), and the behavioral performance in tasks sensitive to manipulations of adult neurogenesis. METHODOLOGY/PRINCIPAL FINDINGS: 2-month old mice received 5 doses of ENU and were sacrificed 45 days after treatment. Then, an ultrastructural analysis of the SVZ and DG was performed to determine cellular composition in these regions, confirming a significant alteration. After bromodeoxyuridine injections, an S-phase exogenous marker, the immunohistochemical analysis revealed a deficit in proliferation and a decreased recruitment of newly generated cells in neurogenic areas of ENU-treated animals. Behavioral effects were also detected after ENU-exposure, observing impairment in odor discrimination task (habituation-dishabituation test) and a deficit in spatial memory (Barnes maze performance), two functions primarily related to the SVZ and the DG regions, respectively. CONCLUSIONS/SIGNIFICANCE: The results demonstrate that postnatal exposure to ENU produces severe disruption of adult neurogenesis in the SVZ and DG, as well as strong behavioral impairments. These findings highlight the potential risk of environmental NOC-exposure for the development of neural and behavioral deficits

MicroRNA Let-7f Inhibits Tumor Invasion and Metastasis by Targeting MYH9 in Human Gastric Cancer

BACKGROUND: MicroRNAs (miRNAs) are important regulators that play key roles in tumorigenesis and tumor progression. A previous report has shown that let-7 family members can act as tumor suppressors in many cancers. Through miRNA array, we found that let-7f was downregulated in the highly metastatic potential gastric cancer cell lines GC9811-P and SGC7901-M, when compared with their parental cell lines, GC9811 and SGC7901-NM; however, the mechanism was not clear. In this study, we investigate whether let-7f acts as a tumor suppressor to inhibit invasion and metastasis in gastric cancers. METHODOLOGY/PRINCIPAL: Real-time PCR showed decreased levels of let-7f expression in metastatic gastric cancer tissues and cell lines that are potentially highly metastatic. Cell invasion and migration were significantly impaired in GC9811-P and SGC7901-M cell lines after transfection with let-7f-mimics. Nude mice with xenograft models of gastric cancer confirmed that let-7f could inhibit gastric cancer metastasis in vivo after transfection by the lentivirus pGCsil-GFP- let-7f. Luciferase reporter assays demonstrated that let-7f directly binds to the 3'UTR of MYH9, which codes for myosin IIA, and real-time PCR and Western blotting further indicated that let-7f downregulated the expression of myosin IIA at the mRNA and protein levels. CONCLUSIONS/SIGNIFICANCE: Our study demonstrated that overexpression of let-7f in gastric cancer could inhibit invasion and migration of gastric cancer cells through directly targeting the tumor metastasis-associated gene MYH9. These data suggest that let-7f may be a novel therapeutic candidate for gastric cancer, given its ability to reduce cell invasion and metastasis

The neurogenic potential of astrocytes is regulated by inflammatory signals

Although the adult brain contains neural stem cells (NSCs) that generate new neurons throughout life, these astrocyte-like populations are restricted to two discrete niches. Despite their terminally differentiated phenotype, adult parenchymal astrocytes can re-acquire NSC-like characteristics following injury, and as such, these 'reactive' astrocytes offer an alternative source of cells for central nervous system (CNS) repair following injury or disease. At present, the mechanisms that regulate the potential of different types of astrocytes are poorly understood. We used in vitro and ex vivo astrocytes to identify candidate pathways important for regulation of astrocyte potential. Using in vitro neural progenitor cell (NPC)-derived astrocytes, we found that exposure of more lineage-restricted astrocytes to either tumor necrosis factor alpha (TNF-α) (via nuclear factor-κB (NFκB)) or the bone morphogenetic protein (BMP) inhibitor, noggin, led to re-acquisition of NPC properties accompanied by transcriptomic and epigenetic changes consistent with a more neurogenic, NPC-like state. Comparative analyses of microarray data from in vitro-derived and ex vivo postnatal parenchymal astrocytes identified several common pathways and upstream regulators associated with inflammation (including transforming growth factor (TGF)-β1 and peroxisome proliferator-activated receptor gamma (PPARγ)) and cell cycle control (including TP53) as candidate regulators of astrocyte phenotype and potential. We propose that inflammatory signalling may control the normal, progressive restriction in potential of differentiating astrocytes as well as under reactive conditions and represent future targets for therapies to harness the latent neurogenic capacity of parenchymal astrocytes

Normograms of ovarian volume, Uterine size and endometrial thickness in urban midlife Malaysia women

Cancers of the ovary and corpus uteri afflict 5% and 3.6% Malaysian women respectively. Ovarian cancer (OC) remained the deadliest gynaecological malignancy in perimenopausal women mainly due to the lack of symptoms until the disease had spread. Ultrasonography could provide a preliminary screening allowing the clinician to tailor subsequent management and counselling for these women. To support the basis for selective screening, a study on 517 urban disease free women aged 45 years and above, uterus-intact, non-users of HRT was undertaken. This study presented normograms of ovary, uterus and endometrium derived from entry ultrasound assessment. The sample comprised of 58.0% premenopaused and 42.0% postmenopaused women with an average age of 51.27±5.35 years old. Over two thirds were Chinese followed by Malays and Indians. The findings indicated that the average uterine size and endometrial thickness (ET) was 7.21±1.67x4.36±1.30cm and 6.36±3.73mm respectively. Premenopausal women had larger uterus compared to those postmenopaused (p70 years old. From these findings, a cut-off of <5.0mm was considered clinically acceptable in normal postmenopaused regardless of ethnicity. Nearly one fifth (18.9%) had uterine fibroids, a quarter (25%) in premenopausal women as compared to 10% postmenopaused (p<0.0005). The mean right and left ovarian volume (OV) was 5.48±7.85cm3 and 5.80±16.78cm3 respectively. There was a gradual decline in OV with age and menopause from about 7cm3 at age 45-49 years to less than 1.5cm3 at 70 years giving a clinical norm OV of <7.5cm3 and <3.5cm3 respectively in pre and postmenopausal Malaysian women. Benign ovarian cysts seen in 2.9% had a mean size of 65.14±88.22cm3. In conclusion, ET and OV normograms should be made available for the Malaysian population to facilitate screening for gynaecological malignancie

Utility of pap smears and mammograms in midlife urban Malaysian women

Cancers of the breast and cervix made up 30.4% and 12% of all cancer cases in Malaysia. Thus screening for reproductive organ cancers as women approached menopause becomes exceedingly important. The study reports the baseline assessment tests of 495 disease free urban Malaysian women aged 45 years and above who volunteered in a healthy lifestyle intervention study. The sample comprised of 58.0% premenopaused and 42.0% postmenopaused women with an average age of 51.27±5.35 years old. Over two thirds were Chinese followed by Malays and Indians. Overall, abnormal Pap smears were seen in 7.6% comprising of 1.3% cervical intraepithelial neoplasia (CIN), 6.1% human papilloma virus (HPV) infection and 0.2% atypical squmous cells of undetermined significances (ASCUS). Yeast and other infections were found in 6.9% and 1.9% respectively. Comparatively, postmenopausal women had a 2.8 fold higher cancerous changes whereas premenopausal women had a higher infection rate, 11.8% vs. 4.7% respectively (p=0.024) with comparable HPV infection rates in both. This study found 1.3% had breast cancer (BC) with 3.6% requiring a biopsy while 3.4% needed regular follow up. Postmenopaused women had more abnormal mammograms (p<0.0005) of a graver nature, requiring monitoring although the rate of BC was lower than the premenopaused, 0.010 versus 0.015. The findings identified better vigorous screening for malignant carcinoma of the cervix in postmenopausal women as the incidence was higher. As for breast abnormalities, screening should begin at an earlier age, amongst pre- and postmenopausal women from 45 years old and abov

Radial glia in the proliferative ventricular zone of the embryonic and adult turtle, Trachemys scripta elegans

To better understand the role of radial glial (RG) cells in the evolution of the mammalian cerebral cortex, we investigated the role of RG cells in the dorsal cortex and dorsal ventricular ridge of the turtle, Trachemys scripta elegans. Unlike mammals, the glial architecture of adult reptile consists mainly of ependymoradial glia, which share features with mammalian RG cells, and which may contribute to neurogenesis that continues throughout the lifespan of the turtle. To evaluate the morphology and proliferative capacity of ependymoradial glia (here referred to as RG cells) in the dorsal cortex of embryonic and adult turtle, we adapted the cortical electroporation technique, commonly used in rodents, to the turtle telencephalon. Here, we demonstrate the morphological and functional characteristics of RG cells in the developing turtle dorsal cortex. We show that cell division occurs both at the ventricle and away from the ventricle, that RG cells undergo division at the ventricle during neurogenic stages of development, and that mitotic Tbr2+ precursor cells, a hallmark of the mammalian SVZ, are present in the turtle cortex. In the adult turtle, we show that RG cells encompass a morphologically heterogeneous population, particularly in the subpallium where proliferation is most prevalent. One RG subtype is similar to RG cells in the developing mammalian cortex, while 2 other RG subtypes appear to be distinct from those seen in mammal. We propose that the different subtypes of RG cells in the adult turtle perform distinct functions