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1.
Nano Lett ; 22(3): 935-941, 2022 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-35089714

RESUMO

Spintronics involves the development of low-dimensional electronic systems with potential use in quantum-based computation. In graphene, there has been significant progress in improving spin transport characteristics by encapsulation and reducing impurities, but the influence of standard two-dimensional (2D) tunnel contacts, via pinholes and doping of the graphene channel, remains difficult to eliminate. Here, we report the observation of spin injection and tunable spin signal in fully encapsulated graphene, enabled by van der Waals heterostructures with one-dimensional (1D) contacts. This architecture prevents significant doping from the contacts, enabling high-quality graphene channels, currently with mobilities up to 130 000 cm2 V-1 s-1 and spin diffusion lengths approaching 20 µm. The nanoscale-wide 1D contacts allow spin injection both at room and at low temperature, with the latter exhibiting efficiency comparable with 2D tunnel contacts. At low temperature, the spin signals can be enhanced by as much as an order of magnitude by electrostatic gating, adding new functionality.

2.
J Biol Chem ; 297(3): 100987, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34364871

RESUMO

Progressive fibrosis leads to loss of organ function and affects many organs as a result of excessive extracellular matrix production. The ubiquitous matrix polysaccharide hyaluronan (HA) is central to this through association with its primary receptor, CD44, which exists as standard CD44 (CD44s) or multiple splice variants. Mediators such as profibrotic transforming growth factor (TGF)-ß1 and proinflammatory interleukin (IL)-1ß are widely associated with fibrotic progression. TGF-ß1 induces myofibroblast differentiation, while IL-1ß induces a proinflammatory fibroblast phenotype that promotes fibroblast binding to monocyte/macrophages. CD44 expression is essential for both responses. Potential CD44 splice variants involved, however, are unidentified. The TGF-ß1-activated CD44/epidermal growth factor receptor complex induces differentiation of metastatic cells through interactions with the matrix metalloproteinase inducer, CD147. This study aimed to determine the CD44 variants involved in TGF-ß1- and IL-1ß-mediated responses and to investigate the potential profibrotic role of CD147. Using immunocytochemistry and quantitative PCR, standard CD44s were shown to be essential for both TGF-ß1-induced fibroblast/myofibroblast differentiation and IL-1ß-induced monocyte binding. Co-immunoprecipitation identified that CD147 associated with CD44s. Using CD147-siRNA and confocal microscopy, we also determined that incorporation of the myofibroblast marker, αSMA, into F-actin stress fibers was prevented in the absence of CD147 and myofibroblast-dependent collagen gel contraction was inhibited. CD147 did not associate with HA, but removal of HA prevented the association of CD44s with CD147 at points of cell-cell contact. Taken together, our data suggest that CD44s/CD147 colocalization is essential in regulating the mechanical tension required for the αSMA incorporation into F-actin stress fibers that regulates myofibroblast phenotype.


Assuntos
Basigina/fisiologia , Diferenciação Celular/fisiologia , Receptores de Hialuronatos/fisiologia , Miofibroblastos/citologia , Fator de Crescimento Transformador beta1/fisiologia , Basigina/metabolismo , Humanos , Receptores de Hialuronatos/metabolismo , Ácido Hialurônico/metabolismo , Interleucina-1beta/fisiologia , Miofibroblastos/metabolismo
3.
J Am Soc Nephrol ; 32(10): 2501-2516, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34155061

RESUMO

BACKGROUND: Proximal tubular cells (PTCs) are the most abundant cell type in the kidney. PTCs are central to normal kidney function and to regeneration versus organ fibrosis following injury. This study used single-nucleus RNA sequencing (snRNAseq) to describe the phenotype of PTCs in renal fibrosis. METHODS: Kidneys were harvested from naïve mice and from mice with renal fibrosis induced by chronic aristolochic acid administration. Nuclei were isolated using Nuclei EZ Lysis buffer. Libraries were prepared on the 10× platform, and snRNAseq was completed using the Illumina NextSeq 550 System. Genome mapping was carried out with high-performance computing. RESULTS: A total of 23,885 nuclei were analyzed. PTCs were found in five abundant clusters, mapping to S1, S1-S2, S2, S2-cortical S3, and medullary S3 segments. Additional cell clusters ("new PTC clusters") were at low abundance in normal kidney and in increased number in kidneys undergoing regeneration/fibrosis following injury. These clusters exhibited clear molecular phenotypes, permitting labeling as proliferating, New-PT1, New-PT2, and (present only following injury) New-PT3. Each cluster exhibited a unique gene expression signature, including multiple genes previously associated with renal injury response and fibrosis progression. Comprehensive pathway analyses revealed metabolic reprogramming, enrichment of cellular communication and cell motility, and various immune activations in new PTC clusters. In ligand-receptor analysis, new PTC clusters promoted fibrotic signaling to fibroblasts and inflammatory activation to macrophages. CONCLUSIONS: These data identify unrecognized PTC phenotype heterogeneity and reveal novel PTCs associated with kidney fibrosis.


Assuntos
Células Epiteliais/metabolismo , Células Epiteliais/patologia , Túbulos Renais Proximais/patologia , Fenótipo , RNA/metabolismo , Transcriptoma , Animais , Ácidos Aristolóquicos , Comunicação Celular , Movimento Celular , Núcleo Celular , Mapeamento Cromossômico , Células Epiteliais/fisiologia , Fibroblastos/metabolismo , Fibrose , Macrófagos/metabolismo , Masculino , Camundongos , RNA/genética , Regeneração , Análise de Sequência de RNA
4.
Nano Lett ; 20(5): 3808-3818, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32310666

RESUMO

When approaching the atomically thin limit, defects and disorder play an increasingly important role in the properties of two-dimensional (2D) materials. While defects are generally thought to negatively affect superconductivity in 2D materials, here we demonstrate the contrary in the case of oxygenation of ultrathin tantalum disulfide (TaS2). Our first-principles calculations show that incorporation of oxygen into the TaS2 crystal lattice is energetically favorable and effectively heals sulfur vacancies typically present in these crystals, thus restoring the electronic band structure and the carrier density to the intrinsic characteristics of TaS2. Strikingly, this leads to a strong enhancement of the electron-phonon coupling, by up to 80% in the highly oxygenated limit. Using transport measurements on fresh and aged (oxygenated) few-layer TaS2, we found a marked increase of the superconducting critical temperature (Tc) upon aging, in agreement with our theory, while concurrent electron microscopy and electron-energy loss spectroscopy confirmed the presence of sulfur vacancies in freshly prepared TaS2 and incorporation of oxygen into the crystal lattice with time. Our work thus reveals the mechanism by which certain atomic-scale defects can be beneficial to superconductivity and opens a new route to engineer Tc in ultrathin materials.

5.
J Am Soc Nephrol ; 30(9): 1641-1658, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31405951

RESUMO

BACKGROUND: GATA3 is a dual-zinc finger transcription factor that regulates gene expression in many developing tissues. In the kidney, GATA3 is essential for ureteric bud branching, and mice without it fail to develop kidneys. In humans, autosomal dominant GATA3 mutations can cause renal aplasia as part of the hypoparathyroidism, renal dysplasia, deafness (HDR) syndrome that includes mesangioproliferative GN. This suggests that GATA3 may have a previously unrecognized role in glomerular development or injury. METHODS: To determine GATA3's role in glomerular development or injury, we assessed GATA3 expression in developing and mature kidneys from Gata3 heterozygous (+/-) knockout mice, as well as injured human and rodent kidneys. RESULTS: We show that GATA3 is expressed by FOXD1 lineage stromal progenitor cells, and a subset of these cells mature into mesangial cells (MCs) that continue to express GATA3 in adult kidneys. In mice, we uncover that GATA3 is essential for normal glomerular development, and mice with haploinsufficiency of Gata3 have too few MC precursors and glomerular abnormalities. Expression of GATA3 is maintained in MCs of adult kidneys and is markedly increased in rodent models of mesangioproliferative GN and in IgA nephropathy, suggesting that GATA3 plays a critical role in the maintenance of glomerular homeostasis. CONCLUSIONS: These results provide new insights on the role GATA3 plays in MC development and response to injury. It also shows that GATA3 may be a novel and robust nuclear marker for identifying MCs in tissue sections.


Assuntos
Fator de Transcrição GATA3/metabolismo , Glomerulonefrite/metabolismo , Glomérulos Renais/metabolismo , Animais , Movimento Celular , Proliferação de Células , Modelos Animais de Doenças , Feminino , Fatores de Transcrição Forkhead/metabolismo , Fator de Transcrição GATA3/genética , Haploinsuficiência , Humanos , Glomérulos Renais/anormalidades , Glomérulos Renais/embriologia , Glomérulos Renais/patologia , Masculino , Células Mesangiais/metabolismo , Células-Tronco Mesenquimais/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Cultura Primária de Células , Ratos , Ratos Wistar
6.
Nano Lett ; 18(11): 6954-6960, 2018 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-30372086

RESUMO

Hexagonal boron nitride (hBN) is a prototypical high-quality two-dimensional insulator and an ideal material to study tunneling phenomena, as it can be easily integrated in vertical van der Waals devices. For spintronic devices, its potential has been demonstrated both for efficient spin injection in lateral spin valves and as a barrier in magnetic tunnel junctions (MTJs). Here we reveal the effect of point defects inevitably present in mechanically exfoliated hBN on the tunnel magnetoresistance of Co-hBN-NiFe MTJs. We observe a clear enhancement of both the conductance and magnetoresistance of the junction at well-defined bias voltages, indicating resonant tunneling through magnetic (spin-polarized) defect states. The spin polarization of the defect states is attributed to exchange coupling of a paramagnetic impurity in the few-atomic-layer thick hBN to the ferromagnetic electrodes. This is confirmed by excellent agreement with theoretical modeling. Our findings should be taken into account in analyzing tunneling processes in hBN-based magnetic devices. More generally, our study shows the potential of using atomically thin hBN barriers with defects to engineer the magnetoresistance of MTJs and to achieve spin filtering, opening the door toward exploiting the spin degree of freedom in current studies of point defects as quantum emitters.

7.
Nano Lett ; 16(1): 629-36, 2016 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-26612060

RESUMO

Superconducting layered transition metal dichalcogenides (TMDs) stand out among other superconductors due to the tunable nature of the superconducting transition, coexistence with other collective electronic excitations (charge density waves), and strong intrinsic spin-orbit coupling. Molybdenum disulfide (MoS2) is the most studied representative of this family of materials, especially since the recent demonstration of the possibility to tune its critical temperature, Tc, by electric-field doping. However, just one of its polymorphs, band-insulator 2H-MoS2, has so far been explored for its potential to host superconductivity. We have investigated the possibility to induce superconductivity in metallic polytypes, 1T- and 1T'-MoS2, by potassium (K) intercalation. We demonstrate that at doping levels significantly higher than that required to induce superconductivity in 2H-MoS2, both 1T and 1T' phases become superconducting with Tc = 2.8 and 4.6 K, respectively. Unusually, K intercalation in this case is responsible both for the structural and superconducting phase transitions. By adding new members to the family of superconducting TMDs, our findings open the way to further manipulate and enhance the electronic properties of these technologically important materials.


Assuntos
Dissulfetos/química , Molibdênio/química , Nanoestruturas/química , Potássio/química , Catálise , Calcogênios/química , Condutividade Elétrica , Temperatura
8.
Int J Clin Exp Pathol ; 17(4): 151-164, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38716349

RESUMO

OBJECTIVES: Acute Kidney Injury (AKI) and Chronic Kidney Disease (CKD) are increasingly recognised as one disease continuum, rather than distinct entities, and are associated with a huge burden to healthcare services. The leading cause of AKI worldwide is Ischaemia Reperfusion Injury (IRI), most commonly seen in clinical settings of sepsis-driven hypotension. Ischaemic Preconditioning (IPC) is a strategy aimed at reducing the deleterious effects of IRI. The objectives of this study were to demonstrate an efficacious in vivo model of Kidney IRI, and the protective influence of IPC in attenuating AKI and development of renal fibrosis. METHODS: A rat model of bilateral kidney IRI was used: Male Lewis rats (n=84) were assigned to IRI, sham or IPC. In IRI, renal pedicles were clamped for 45 minutes. IPC groups underwent pulsatile IPC prior to IRI. Kidneys were retrieved at 24 hours, 48 hours, 7 days, 14 days and 28 days, and assessed histologically. RESULTS: IRI led to marked AKI (24-48 h) and renal fibrosis development by 28 days. IPC attenuated this damage, with 66% less fibrosis. Interestingly, at 14-days, the histological appearance of both IRI and IPC kidneys was rather similar, potentially representing an important transitional point at which kidneys commit to either fibrosis or recovery. This may provide a suitable inflexion point for introduction of novel anti-fibrotic therapies. CONCLUSIONS: In conclusion, we have characterised a model of kidney injury from acute to chronic phases, allowing detailed mechanistic understanding and which can be manipulated by effective treatment strategies such as IPC.

9.
Nat Commun ; 15(1): 6933, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-39138190

RESUMO

The ongoing efforts to optimize rechargeable Li-ion batteries led to the interest in intercalation of nanoscale layered compounds, including bilayer graphene. Its lithium intercalation has been demonstrated recently but the mechanisms underpinning the storage capacity remain poorly understood. Here, using magnetotransport measurements, we report in-operando intercalation dynamics of bilayer graphene. Unexpectedly, we find four distinct intercalation stages that correspond to well-defined Li-ion densities. Transitions between the stages occur rapidly (within 1 sec) over the entire device area. We refer to these stages as 'in-plane', with no in-plane analogues in bulk graphite. The fully intercalated bilayers represent a stoichiometric compound C14LiC14 with a Li density of ∼2.7·1014 cm-2, notably lower than fully intercalated graphite. Combining the experimental findings and DFT calculations, we show that the critical step in bilayer intercalation is a transition from AB to AA stacking which occurs at a density of ∼0.9·1014 cm-2. Our findings reveal the mechanism and limits for electrochemical intercalation of bilayer graphene and suggest possible avenues for increasing the Li storage capacity.

10.
Sci Rep ; 13(1): 10343, 2023 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-37365221

RESUMO

We study the room-temperature electrical control of charge and spin transport in high-quality bilayer graphene, fully encapsulated with hBN and contacted via 1D spin injectors. We show that spin transport in this device architecture is measurable at room temperature and its spin transport parameters can be modulated by opening of a band gap via a perpendicular displacement field. The modulation of the spin current is dominated by the control of the spin relaxation time with displacement field, demonstrating the basic operation of a spin-based field-effect transistor.

11.
Hum Mol Genet ; 19(10): 2028-38, 2010 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-20190276

RESUMO

GCMB is a member of the small transcription factor family GCM (glial cells missing), which are important regulators of development, present in vertebrates and some invertebrates. In man, GCMB encodes a 506 amino acid parathyroid gland-specific protein, mutations of which have been reported to cause both autosomal dominant and autosomal recessive hypoparathyroidism. We ascertained 18 affected individuals from 12 families with autosomal recessive hypoparathyroidism and have investigated them for GCMB abnormalities. Four different homozygous germline mutations were identified in eight families that originate from the Indian Subcontinent. These consisted of a novel nonsense mutation R39X; a missense mutation, R47L in two families; a novel missense mutation, R110W; and a novel frameshifting deletion, I298fsX307 in four families. Haplotype analysis, using polymorphic microsatellites from chromosome 6p23-24, revealed that R47L and I298fsX307 mutations arose either as ancient founders, or recurrent de novo mutations. Functional studies including: subcellular localization studies, EMSAs and luciferase-reporter assays, were undertaken and these demonstrated that: the R39X mutant failed to localize to the nucleus; the R47L and R110W mutants both lost DNA-binding ability; and the I298fsX307 mutant had reduced transactivational ability. In order to gain further insights, we undertook 3D-modeling of the GCMB DNA-binding domain, which revealed that the R110 residue is likely important for the structural integrity of helix 2, which forms part of the GCMB/DNA binding interface. Thus, our results, which expand the spectrum of hypoparathyroidism-associated GCMB mutations, help elucidate the molecular mechanisms underlying DNA-binding and transactivation that are required for this parathyroid-specific transcription factor.


Assuntos
Genes Recessivos/genética , Hipoparatireoidismo/genética , Mutação/genética , Proteínas Nucleares/genética , Glândulas Paratireoides/patologia , Fatores de Transcrição/genética , Sequência de Aminoácidos , Sequência de Bases , Núcleo Celular/metabolismo , DNA/metabolismo , Ensaios Enzimáticos , Família , Feminino , Genes Reporter , Humanos , Luciferases/metabolismo , Masculino , Modelos Moleculares , Dados de Sequência Molecular , Proteínas Mutantes/química , Proteínas Nucleares/química , Especificidade de Órgãos/genética , Glândulas Paratireoides/metabolismo , Linhagem , Ligação Proteica , Transporte Proteico , Fatores de Transcrição/química
12.
Microcirculation ; 18(5): 390-9, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21438962

RESUMO

OBJECTIVE: We recently demonstrated that the formation of CLSs in vitro, which are thought to be a reconstitution of VM, is controlled by VEGFA. CLS formation also requires the extracellular matrix signals, presumably transduced by integrins. Both pathways are affected by Ca(2+). Therefore, we directly tested the roles of Ca(2+) and integrin in melanoma VM. METHODS: The investigation was performed by immunocytochemical, histochemical, and 3D co-culture assays. We have also used an in vivo animal model. RESULTS: The extracellular and intracellular Ca(2+) chelators, EGTA and BAPTA-AM, prevented CLS formation on Matrigel, caused actin rearrangement, and completely destroyed the preformed CLS. Addition of colcemid or cytochalasin D prevented the CLS formation and destroyed the preformed CLS network. Herein, we also show that blocking antibodies to ανß3 and ανß5 integrins disrupted the CLS network. Control blocking antibody to ß1 integrin had no effect. In vivo experiments indicated that Ca(2+) chelation dramatically reduced the signs of VM in melanoma tumors grafted in mice. CONCLUSIONS: Our results indicate that the formation of CLS is tightly regulated by extracellular and intracellular Ca(2+) levels; ανß3 and ανß5 integrins are primarily responsible for CLS formation, whereas ß1 integrin does not participate in CLS formation.


Assuntos
Sinalização do Cálcio , Capilares/metabolismo , Integrinas/metabolismo , Melanoma/irrigação sanguínea , Melanoma/metabolismo , Neovascularização Patológica/metabolismo , Animais , Anticorpos Neutralizantes/farmacologia , Capilares/patologia , Linhagem Celular Tumoral , Quelantes/farmacologia , Humanos , Integrinas/antagonistas & inibidores , Melanoma/patologia , Camundongos , Transplante de Neoplasias , Neovascularização Patológica/patologia , Transplante Heterólogo
13.
Adv Mater ; 33(39): e2103257, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34365697

RESUMO

Superconductors with nontrivial band structure topology represent a class of materials with unconventional and potentially useful properties. Recent years have seen much success in creating artificial hybrid structures exhibiting the main characteristics of 2D topological superconductors. Yet, bulk materials known to combine inherent superconductivity with nontrivial topology remain scarce, largely because distinguishing their central characteristic-the topological surface states-has proved challenging due to a dominant contribution from the superconducting bulk. In this work, a highly anomalous behavior of surface superconductivity in topologically nontrivial 3D superconductor In2 Bi, where the surface states result from its nontrivial band structure, itself a consequence of the non-symmorphic crystal symmetry and strong spin-orbit coupling, is reported. In contrast to smoothly decreasing diamagnetic susceptibility above the bulk critical field, Hc2 , as seen in conventional superconductors, a near-perfect, Meissner-like screening of low-frequency magnetic fields well above Hc2 is observed. The enhanced diamagnetism disappears at a new phase transition close to the critical field of surface superconductivity, Hc3 . Using theoretical modeling, the anomalous screening is shown to be consistent with modification of surface superconductivity by the topological surface states. The possibility of detecting signatures of the surface states using macroscopic magnetization provides a new tool for the discovery and identification of topological superconductors.

14.
Adv Mater ; 33(5): e2004138, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33346397

RESUMO

Higher-order exchange interactions and quantum effects are widely known to play an important role in describing the properties of low-dimensional magnetic compounds. Here, the recently discovered 2D van der Waals (vdW) CrI3 is identified as a quantum non-Heisenberg material with properties far beyond an Ising magnet as initially assumed. It is found that biquadratic exchange interactions are essential to quantitatively describe the magnetism of CrI3 but quantum rescaling corrections are required to reproduce its thermal properties. The quantum nature of the heat bath represented by discrete electron-spin and phonon-spin scattering processes induces the formation of spin fluctuations in the low-temperature regime. These fluctuations induce the formation of metastable magnetic domains evolving into a single macroscopic magnetization or even a monodomain over surface areas of a few micrometers. Such domains display hybrid characteristics of Néel and Bloch types with a narrow domain wall width in the range of 3-5 nm. Similar behavior is expected for the majority of 2D vdW magnets where higher-order exchange interactions are appreciable.

15.
Small ; 6(24): 2877-84, 2010 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-21053339

RESUMO

A stoichiometric derivative of graphene with a fluorine atom attached to each carbon is reported. Raman, optical, structural, micromechanical, and transport studies show that the material is qualitatively different from the known graphene-based nonstoichiometric derivatives. Fluorographene is a high-quality insulator (resistivity >10(12) Ω) with an optical gap of 3 eV. It inherits the mechanical strength of graphene, exhibiting a Young's modulus of 100 N m(-1) and sustaining strains of 15%. Fluorographene is inert and stable up to 400 °C even in air, similar to Teflon.


Assuntos
Grafite/química , Politetrafluoretileno/química , Halogenação , Microscopia Eletrônica de Transmissão , Análise Espectral Raman
16.
ACS Appl Mater Interfaces ; 12(51): 57638-57648, 2020 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-33314909

RESUMO

Graphene has great potential for use in infrared (IR) nanodevices. At these length scales, nanoscale features, and their interaction with light, can be expected to play a significant role in device performance. Bubbles in van der Waals heterostructures are one such feature, which have recently attracted considerable attention, thanks to their ability to modify the optoelectronic properties of two-dimensional (2D) materials through strain. Here, we use scattering-type scanning near-field optical microscopy (sSNOM) to measure the nanoscale IR response from a network of variously shaped bubbles in hexagonal boron nitride (hBN)-encapsulated graphene. We show that within individual bubbles there are distinct domains with strongly enhanced IR absorption. The IR domain boundaries coincide with ridges in the bubbles, which leads us to attribute them to nanoscale strain domains. We further validate the strain distribution in the graphene by means of confocal Raman microscopy and vector decomposition analysis. This shows intricate and varied strain configurations, in which bubbles of different shape induce more bi- or uniaxial strain configurations. This reveals pathways toward future strain-based graphene IR devices.

17.
Phys Rev E ; 102(4-1): 042119, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33212580

RESUMO

Using a computer simulation, we have studied the random sequential adsorption of stiff linear k-mers onto a square lattice. Each such particle occupies k adjacent lattice sites. During deposition, the two mutually perpendicular orientations of the particles are equiprobable, hence, a macroscopically isotropic monolayer is formed. However, this monolayer is locally anisotropic, since the deposited particles tend to form domains of particles with the same orientation. Using the "excluded area" concept, we have classified lattice sites into several types and examined how the fraction of each type of lattice site varies as the number of deposited particles increases. The behaviors of these quantities have allowed us to identify the following stages of domain formation: (i) the emergence of domain seeds, (ii) the filling of domains, and (iii) densification of the domains.

18.
Endocr Connect ; 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31961795

RESUMO

Hypoparathyroidism is genetically heterogeneous and characterized by low plasma calcium and parathyroid hormone (PTH) concentrations. X-linked hypoparathyroidism (XLHPT) in two American families, is associated with interstitial deletion-insertions involving deletions of chromosome Xq27.1 downstream of SOX3 and insertions of predominantly non-coding DNA from chromosome 2p25.3. These could result in loss, gain, or movement of regulatory elements, which include ultraconserved element uc482, that could alter SOX3 expression,. To investigate this, we analysed SOX3 expression in EBV-transformed lymphoblastoid cells from 3 affected males, 3 unaffected males, and 4 carrier females from one XLHPT family. SOX3 expression was similar in all individuals, indicating that the spatiotemporal effect of the interstitial deletion-insertion on SOX3 expression postulated to occur in developing parathyroids did not manifest in lymphoblastoids. Expression of SNTG2, which is duplicated and inserted into the X chromosome, and ATP11C, which is moved telomerically, were also similarly expressed in all individuals. Investigation of male hemizygous (Sox3-/Y and uc482-/Y) and female heterozygous (Sox3+/- and uc482+/-) knock-out mice, together with wild-type littermates (male Sox3+/Y and uc482+/Y, and female Sox3+/+ and uc482+/+), revealed Sox3-/Y, Sox3+/-, uc482-/Y, and uc482+/- mice to have normal plasma biochemistry, compared to their respective wild-type littermates. When challenged with a low calcium diet, all mice had hypocalcaemia, and elevated plasma PTH concentrations and alkaline phosphatase activities, and Sox3-/Y, Sox3+/-, uc482-/Y, and uc482+/- mice had similar plasma biochemistry, compared to wild-type littermates. Thus, these results indicate that absence of Sox3 or uc482 does not cause hypoparathyroidism, and that XLHPT likely reflects a more complex mechanism.

19.
ACS Nano ; 14(6): 7280-7286, 2020 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-32427466

RESUMO

Defect-free graphene is impermeable to gases and liquids but highly permeable to thermal protons. Atomic-scale defects such as vacancies, grain boundaries, and Stone-Wales defects are predicted to enhance graphene's proton permeability and may even allow small ions through, whereas larger species such as gas molecules should remain blocked. These expectations have so far remained untested in experiment. Here, we show that atomically thin carbon films with a high density of atomic-scale defects continue blocking all molecular transport, but their proton permeability becomes ∼1000 times higher than that of defect-free graphene. Lithium ions can also permeate through such disordered graphene. The enhanced proton and ion permeability is attributed to a high density of eight-carbon-atom rings. The latter pose approximately twice lower energy barriers for incoming protons compared to that of the six-atom rings of graphene and a relatively low barrier of ∼0.6 eV for Li ions. Our findings suggest that disordered graphene could be of interest as membranes and protective barriers in various Li-ion and hydrogen technologies.

20.
Can J Urol ; 16(4): 4726-32, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19671223

RESUMO

BACKGROUND: The ability of aggressive tumors to form nonendothelial tumor cell-lined microvascular channels is known as "vasculogenic mimicry" (VM). VM channels are revealed as periodic acid-Schiff (PAS)-positive patterns, and in some tumors their presence predicts clinical outcomes. OBJECTIVE: We aimed to study VM channels in clear cell renal cell carcinoma (cRCC) tumors and explore their prognostic significance and relationship to other suggested prognostic factors such as thymidine phosphorylase (TP) and vascular endothelial growth factor (VEGF) expression. METHODS: We retrospectively studied 45 patients who had undergone radical nephrectomy for clinically confined cRCC (stage T2-T3NOMO) at the Russian Cancer Research Center. The tumor sections were reviewed for disease stage, nuclear grade, perirenal fat invasion, and lymph node involvement, and we performed immunohistochemical staining for VEGF and TP expression, and PAS staining. Disease-free survival probabilities were determined by Kaplan-Meier estimates and prognostic factors were evaluated by univariate analysis. RESULTS: PAS-positive patterns observed in the cRCC tumor included back-to-back closed loops, networks, arcs, and parallel patterns. There was a significant decrease in disease-free survival among patients with PAS-positive networks (p = 0.005), but not among patients with other PAS-positive patterns. TP expression was also a significant predictor of disease-free survival (p = 0.035), but this factor did not correlate with the presence of PAS-positive networks. Notably, in our small sample, the six patients whose tumors were positive for both factors had the highest risk of cancer recurrence. CONCLUSIONS: The presence of PAS-positive networks is an independent and relevant prognostic parameter for disease-free survival in patients with cRCC. Our data suggest that the combination of PAS-positive networks and TP expression may identify patients with the highest risk of cancer recurrence.


Assuntos
Carcinoma de Células Renais/metabolismo , Neoplasias Renais/metabolismo , Adulto , Idoso , Carcinoma de Células Renais/química , Intervalo Livre de Doença , Feminino , Humanos , Neoplasias Renais/química , Masculino , Pessoa de Meia-Idade , Reação do Ácido Periódico de Schiff , Prognóstico , Estudos Retrospectivos , Timidina Fosforilase/análise , Fator A de Crescimento do Endotélio Vascular/análise
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