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1.
Br J Cancer ; 2024 Jun 04.
Article in English | MEDLINE | ID: mdl-38834745

ABSTRACT

BACKGROUND: Diffuse invasion remains a primary cause of treatment failure in pediatric high-grade glioma (pHGG). Identifying cellular driver(s) of pHGG invasion is needed for anti-invasion therapies. METHODS: Ten highly invasive patient-derived orthotopic xenograft (PDOX) models of pHGG were subjected to isolation of matching pairs of invasive (HGGINV) and tumor core (HGGTC) cells. RESULTS: pHGGINV cells were intrinsically more invasive than their matching pHGGTC cells. CSC profiling revealed co-positivity of CD133 and CD57 and identified CD57+CD133- cells as the most abundant CSCs in the invasive front. In addition to discovering a new order of self-renewal capacities, i.e., CD57+CD133- > CD57+CD133+ > CD57-CD133+ > CD57-CD133- cells, we showed that CSC hierarchy was impacted by their spatial locations, and the highest self-renewal capacities were found in CD57+CD133- cells in the HGGINV front (HGGINV/CD57+CD133- cells) mediated by NANOG and SHH over-expression. Direct implantation of CD57+ (CD57+/CD133- and CD57+/CD133+) cells into mouse brains reconstituted diffusely invasion, while depleting CD57+ cells (i.e., CD57-CD133+) abrogated pHGG invasion. CONCLUSION: We revealed significantly increased invasive capacities in HGGINV cells, confirmed CD57 as a novel glioma stem cell marker, identified CD57+CD133- and CD57+CD133+ cells as a new cellular driver of pHGG invasion and suggested a new dual-mode hierarchy of HGG stem cells.

2.
J Transl Med ; 21(1): 444, 2023 07 06.
Article in English | MEDLINE | ID: mdl-37415222

ABSTRACT

BACKGROUND: Animal models representing different molecular subtypes of glioblastoma multiforme (GBM) is desired for developing new therapies. SVV-001 is an oncolytic virus selectively targeting cancer cells. It's capacity of passing through the blood brain barrier makes is an attractive novel approach for GBM. MATERIALS AND METHODS: 23 patient tumor samples were implanted into the brains of NOD/SCID mice (1 × 105 cells/mouse). Tumor histology, gene expression (RNAseq), and growth rate of the developed patient-derived orthotopic xenograft (PDOX) models were compared with the originating patient tumors during serial subtransplantations. Anti-tumor activities of SVV-001 were examined in vivo; and therapeutic efficacy validated in vivo via single i.v. injection (1 × 1011 viral particle) with or without fractionated (2 Gy/day x 5 days) radiation followed by analysis of animal survival times, viral infection, and DNA damage. RESULTS: PDOX formation was confirmed in 17/23 (73.9%) GBMs while maintaining key histopathological features and diffuse invasion of the patient tumors. Using differentially expressed genes, we subclassified PDOX models into proneural, classic and mesenchymal groups. Animal survival times were inversely correlated with the implanted tumor cells. SVV-001 was active in vitro by killing primary monolayer culture (4/13 models), 3D neurospheres (7/13 models) and glioma stem cells. In 2/2 models, SVV-001 infected PDOX cells in vivo without harming normal brain cells and significantly prolonged survival times in 2/2 models. When combined with radiation, SVV-001 enhanced DNA damages and further prolonged animal survival times. CONCLUSION: A panel of 17 clinically relevant and molecularly annotated PDOX modes of GBM is developed, and SVV-001 exhibited strong anti-tumor activities in vitro and in vivo.


Subject(s)
Brain Neoplasms , Glioblastoma , Oncolytic Virotherapy , Oncolytic Viruses , Humans , Animals , Mice , Glioblastoma/radiotherapy , Glioblastoma/metabolism , Brain Neoplasms/radiotherapy , Brain Neoplasms/metabolism , Xenograft Model Antitumor Assays , Mice, Inbred NOD , Mice, SCID , Disease Models, Animal , Cell Line, Tumor
3.
Phys Chem Chem Phys ; 25(19): 13359-13375, 2023 May 17.
Article in English | MEDLINE | ID: mdl-37145056

ABSTRACT

Decaphenylbiphenyl (1) and 2,2',4,4',6,6'-hexaphenylbiphenyl (2) are bulky molecules expected to be greatly destabilized by steric crowding. Herein, through a combined experimental and computational approach, we evaluate the molecular energetics of crowded biphenyls. This is complemented by the study of phase equilibria for 1 and 2. Compound 1 shows a rich phase behavior, displaying an unusual interconversion between two polymorphs. Surprisingly, the polymorph with distorted molecules of C1 symmetry is found to have the highest melting point and to be the one that is preferentially formed. The thermodynamic results also indicate that the polymorph displaying the more regular D2 molecular geometry has larger heat capacity and is probably the more stable at lower temperatures. The melting and sublimation data clearly reveal the weakening of cohesive forces in crowded biphenyls due to the lower molecular surface area. The experimental quantification of the intramolecular interactions in 1 and 2 indicated, using homodesmotic reactions, a molecular stabilization of about 30 kJ mol-1. We attribute the origin of this stabilization in both compounds to the existence of two parallel-displaced π⋯π interactions between the ortho-phenyl substituents on each side of the central biphenyl. Computational calculations with dispersion-corrected DFT methods underestimate the stabilization in 1, unless the steric crowding is well balanced in a homodesmotic scheme. This work demonstrates that London dispersion forces are important in crowded aromatic systems, making these molecules considerably more stable than previously thought.

4.
Environ Res ; 231(Pt 3): 116265, 2023 08 15.
Article in English | MEDLINE | ID: mdl-37263466

ABSTRACT

Modelling the removal of monovalent and divalent ions from seawater via nanofiltration is crucial for pre-treatment in seawater reverse osmosis systems. Effective separation of divalent ions through nanofiltration and allowing the permeate containing only monovalent ions to pass through the reverse osmosis system produces pure NaCl salt from the concentrate. However, the Donnan steric pore model and dielectric exclusion assume a uniformly distributed cylinder pore morphology, which is not representative of the actual membrane structure. This study analyzed the impact of membrane thickness on neutral solute removal and investigated the effect of two different methods for calculating the Peclet number on rejection rates of monovalent and divalent salts. Results show that membrane thickness has a significant effect on rejection rates, particularly for uncharged solutes in the range of 0.5-0.7 solute radius to membrane pore size ratio. Operating pressures above 10 bar favour the use of effective active layer thickness over the membrane pore size to calculate the Peclet number. At low pressures, using the effective active layer can lead to overestimation of monovalent salt rejection and underestimation of divalent salt rejection. This study highlights the importance of appropriate Peclet number calculation methods based on applied pressure when modelling membrane separation performance.


Subject(s)
Filtration , Membranes, Artificial , Osmosis , Filtration/methods , Ions , Seawater , Solutions
5.
J Digit Imaging ; 36(3): 1148-1157, 2023 06.
Article in English | MEDLINE | ID: mdl-36749455

ABSTRACT

Hyperreflective foci (HF) reflects inflammatory responses for fundus diseases such as diabetic macular edema (DME), retina vein occlusion (RVO), and central serous chorioretinopathy (CSC). Shown as high contrast and reflectivity in optical coherence tomography (OCT) images, automatic segmentation of HF in OCT images is helpful for the prognosis of fundus diseases. Previous traditional methods were time-consuming and required high computing power. Hence, we proposed a lightweight network to segment HF (with a speed of 57 ms per OCT image, at least 150 ms faster than other methods). Our framework consists of two stages: an NLM filter and patch-based split to preprocess images and a lightweight DBR neural network to segment HF automatically. Experimental results from 3000 OCT images of 300 patients (100 DME,100 RVO, and 100 CSC) revealed that our method achieved HF segmentation successfully. The DBR network had the area under curves dice similarity coefficient (DSC) of 83.65%, 76.43%, and 82.20% in segmenting HF in DME, RVO, and CSC on the test cohort respectively. Our DBR network achieves at least 5% higher DSC than previous methods. HF in DME was more easily segmented compared with the other two types. In addition, our DBR network is universally applicable to clinical practice with the ability to segment HF in a wide range of fundus diseases.


Subject(s)
Diabetic Retinopathy , Macular Edema , Humans , Diabetic Retinopathy/diagnostic imaging , Tomography, Optical Coherence/methods , Macular Edema/diagnostic imaging , Fundus Oculi , Neural Networks, Computer
6.
Lab Invest ; 102(2): 185-193, 2022 02.
Article in English | MEDLINE | ID: mdl-34802040

ABSTRACT

Brain tumors are the leading cause of cancer-related death in children. Tazemetostat is an FDA-approved enhancer of zeste homolog (EZH2) inhibitor. To determine its role in difficult-to-treat pediatric brain tumors, we examined EZH2 levels in a panel of 22 PDOX models and confirmed EZH2 mRNA over-expression in 9 GBM (34.6 ± 12.7-fold) and 11 medulloblastoma models (6.2 ± 1.7 in group 3, 6.0 ± 2.4 in group 4) accompanied by elevated H3K27me3 expression. Therapeutic efficacy was evaluated in 4 models (1 GBM, 2 medulloblastomas and 1 ATRT) via systematically administered tazemetostat (250 and 400 mg/kg, gavaged, twice daily) alone and in combination with cisplatin (5 mg/kg, i.p., twice) and/or radiation (2 Gy/day × 5 days). Compared with the untreated controls, tazemetostat significantly (Pcorrected < 0.05) prolonged survival times in IC-L1115ATRT (101% at 400 mg/kg) and IC-2305GBM (32% at 250 mg/kg, 45% at 400 mg/kg) in a dose-dependent manner. The addition of tazemetostat with radiation was evaluated in 3 models, with only one [IC-1078MB (group 4)] showing a substantial, though not statistically significant, prolongation in survival compared to radiation treatment alone. Combining tazemetostat (250 mg/kg) with cisplatin was not superior to cisplatin alone in any model. Analysis of in vivo drug resistance detected predominance of EZH2-negative cells in the remnant PDOX tumors accompanied by decreased H3K27me2 and H3K27me3 expressions. These data supported the use of tazemetostat in a subset of pediatric brain tumors and suggests that EZH2-negative tumor cells may have caused therapy resistance and should be prioritized for the search of new therapeutic targets.


Subject(s)
Brain Neoplasms/therapy , Enhancer of Zeste Homolog 2 Protein/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Xenograft Model Antitumor Assays/methods , Adolescent , Animals , Antineoplastic Combined Chemotherapy Protocols/pharmacology , Benzamides/administration & dosage , Benzamides/pharmacology , Biphenyl Compounds/administration & dosage , Biphenyl Compounds/pharmacology , Brain Neoplasms/genetics , Brain Neoplasms/metabolism , Chemoradiotherapy , Child , Cisplatin/administration & dosage , Combined Modality Therapy/methods , Drug Evaluation, Preclinical , Enhancer of Zeste Homolog 2 Protein/genetics , Enhancer of Zeste Homolog 2 Protein/metabolism , Enzyme Inhibitors/administration & dosage , Female , Gene Expression Profiling/methods , Humans , Infant , Male , Mice, Inbred NOD , Mice, SCID , Morpholines/administration & dosage , Morpholines/pharmacology , Pyridones/administration & dosage , Pyridones/pharmacology , Radiotherapy Dosage
7.
Chemistry ; 28(41): e202200931, 2022 Jul 20.
Article in English | MEDLINE | ID: mdl-35522216

ABSTRACT

Tetradecaphenyl-p-terphenyl (2) was synthesized from 2,3,5,6-tetraphenyl-1,4-diiodobenzene (11) by two methods. Ullmann coupling of 11 with pentaphenyliodobenzene (9) gave compound 2 in 1.7 % yield, and Sonogashira coupling of 11 with phenylacetylene, followed by a double Diels-Alder reaction of the product diyne 12 with tetracyclone (6), gave 2 in 1.5 % overall yield. The latter reaction also gave the monoaddition product 4-(phenylethynyl)-2,2',3,3',4',5,5',6,6'-nonaphenylbiphenyl (13) in 4 % overall yield. The X-ray structures of compounds 2 and 13 show them to possess core aromatic rings distorted into shallow boat conformations. Density functional calculations indicate that these unusual structures are not the lowest energy conformations in the gas phase and may be the result of packing forces in the crystal. In addition, while uncorrected DFT calculations indicate that the strain energy in compound 2 is approximately 50 kcal/mol, dispersion-corrected DFT calculations suggest that it is essentially unstrained, due to compensating, favorable, intramolecular interactions of its many phenyl rings. An attempted synthesis of tetradecaphenyl-o-terphenyl (4) by reaction of diphenylhexatriyne (14) with three equivalents of tetracyclone at 350 °C gave only the diadduct 2-(phenylethynyl)-2',3,3',4,4',5,5',6,6'-nonaphenylbiphenyl (15) in 17 % yield. Even higher temperatures failed to produce 4 and lowered the yield of 15, perhaps due to rapid decomposition of the starting materials. Ullmann coupling of 3,4,5,6-tetraphenyl-1,2-diiodobenzene (16) and compound 9 also failed to give compound 4.

8.
Gastroenterology ; 158(4): 971-984.e10, 2020 03.
Article in English | MEDLINE | ID: mdl-31734182

ABSTRACT

BACKGROUND & AIMS: Prostaglandin E2 (PGE2) promotes colorectal tumor formation and progression by unknown mechanisms. We sought to identify microRNAs (miRNAs) that might mediate the effects of PGE2 on colorectal cancer (CRC) development. METHODS: We incubated LS174T colorectal cancer cells with PGE2 or without (control) and used miRNA-sequencing technology to compare expression patterns of miRNAs. We knocked down levels of specific miRNAs or proteins in cells using small interfering RNAs or genome editing. Cells were analyzed by immunoblot, quantitative polymerase chain reaction, chromosome immunoprecipitation, cell invasion, and luciferase reporter assays; we measured gene expression, binding activity, cell migration and invasion, and transcriptional activity of transcription factors. NOD-scidIL-2Rg-/- mice were given injections of LS174T cells, and growth of primary tumors and numbers of liver and lung metastases were quantified and analyzed by histology. We used public databases to identify correlations in gene expression pattern with patient outcomes. RESULTS: We identified miRNA 675-5p (miR675-5p) as the miRNA most highly up-regulated by incubation of colorectal cancer cells with PGE2. PGE2 increased expression of miR675-5p by activating expression of Myc, via activation of protein kinase B, also known as (AKT), nuclear factor κB, and ß-catenin. PGE2 increased the invasive activities of cultured CRC cells. LS174T cells incubated with PGE2 formed more liver and lung metastases in mice than control LS174T cells. We identified a 3' untranslated region in the TP53 messenger RNA that bound miR675-5p; binding resulted in loss of the p53 protein. Expression of miR675-5p or its precursor RNA, H19, correlated with expression of cyclooxygenase-1 and cyclooxygenase-2 and shorter survival times of patients with CRC. CONCLUSIONS: We found that treatment of mice with PGE2 increased CRC cells invasive activity and ability to form liver and lung metastases. PGE2 down-regulates expression of p53 by increasing expression of miR675-5p, which binds to and prevents translation of TP53 messenger RNA. These findings provide insight into the mechanisms by which PGE2 promotes tumor development and progression. Strategies to target PGE2 might be developed for treatment of CRC.


Subject(s)
Colorectal Neoplasms/metabolism , Dinoprostone/genetics , MicroRNAs/metabolism , Neoplasm Metastasis/genetics , Tumor Suppressor Protein p53/metabolism , Cyclooxygenase 1/metabolism , Cyclooxygenase 2/metabolism , Humans , RNA, Long Noncoding/metabolism , Tumor Cells, Cultured , Up-Regulation/genetics
9.
J Transl Med ; 19(1): 167, 2021 04 26.
Article in English | MEDLINE | ID: mdl-33902640

ABSTRACT

BACKGROUND: Myopic maculopathy (MM) is the most serious and irreversible complication of pathologic myopia, which is a major cause of visual impairment and blindness. Clinic proposed limited number of factors related to MM. To explore additional features strongly related with MM from optic disc region, we employ a machine learning based radiomics analysis method, which could explore and quantify more hidden or imperceptible MM-related features to the naked eyes and contribute to a more comprehensive understanding of MM and therefore may assist to distinguish the high-risk population in an early stage. METHODS: A total of 457 eyes (313 patients) were enrolled and were divided into severe MM group and without severe MM group. Radiomics analysis was applied to depict features significantly correlated with severe MM from optic disc region. Receiver Operating Characteristic were used to evaluate these features' performance of classifying severe MM. RESULTS: Eight new MM-related image features were discovered from the optic disc region, which described the shapes, textural patterns and intensity distributions of optic disc region. Compared with clinically reported MM-related features, these newly discovered features exhibited better abilities on severe MM classification. And the mean values of most features were markedly changed between patients with peripapillary diffuse chorioretinal atrophy (PDCA) and macular diffuse chorioretinal atrophy (MDCA). CONCLUSIONS: Machine learning and radiomics method are useful tools for mining more MM-related features from the optic disc region, by which complex or even hidden MM-related features can be discovered and decoded. In this paper, eight new MM-related image features were found, which would be useful for further quantitative study of MM-progression. As a nontrivial byproduct, marked changes between PDCA and MDCA was discovered by both new image features and clinic features.


Subject(s)
Macular Degeneration , Myopia, Degenerative , Optic Disk , Retinal Diseases , Humans , Machine Learning , Optic Disk/diagnostic imaging
10.
J Chem Phys ; 154(13): 134304, 2021 Apr 07.
Article in English | MEDLINE | ID: mdl-33832250

ABSTRACT

We discovered a way to funnel high-frequency vibrational quanta rapidly and unidirectionally over large distances using oligo(p-phenylene) chains. After mid-IR photon photoexcitation of a -COOH end group, the excess energy is injected efficiently into the chain, forming vibrational wavepackets that propagate freely along the chain. The transport delivers high-energy vibrational quanta with a range of transport speeds reaching 8.6 km/s, which exceeds the speed of sound in common metals (∼5 km/s) and polymers (∼2 km/s). Efficiencies of energy injection into the chain and transport along the chain are found to be very high and dependent on the extent of conjugation across the structure. By tuning the degree of conjugation via electronic doping of the chain, the transport speed and efficiency can be controlled. The study opens avenues for developing materials with controllable energy transport properties for heat management, schemes with efficient energy delivery to hard-to-reach regions, including transport against thermal gradients, and ways for initiating chemical reactions remotely.

11.
Neural Plast ; 2020: 8891458, 2020.
Article in English | MEDLINE | ID: mdl-33101404

ABSTRACT

Background: Freezing of gait (FOG) is a disabling gait disorder influencing patients with Parkinson's disease (PD). Accumulating evidence suggests that FOG is related to the functional alterations within brain networks. We investigated the changes in brain resting-state functional connectivity (FC) in patients with PD with FOG (FOG+) and without FOG (FOG-). Methods: Resting-state functional magnetic resonance imaging (RS-fMRI) data were collected from 55 PD patients (25 FOG+ and 30 FOG-) and 26 matched healthy controls (HC). Differences in intranetwork connectivity between FOG+, FOG-, and HC individuals were explored using independent component analysis (ICA). Results: Seven resting-state networks (RSNs) with abnormalities, including motor, executive, and cognitive-related networks, were found in PD patients compared to HC. Compared to FOG- patients, FOG+ patients had increased FC in advanced cognitive and attention-related networks. In addition, the FC values of the auditory network and default mode network were positively correlated with the Gait and Falls Questionnaire (GFQ) and Freezing of Gait Questionnaire (FOGQ) scores in FOG+ patients. Conclusions: Our findings suggest that the neural basis of PD is associated with impairments of multiple functional networks. Notably, alterations of advanced cognitive and attention-related networks rather than motor networks may be related to the mechanism of FOG.


Subject(s)
Attention/physiology , Brain/physiopathology , Cognition/physiology , Gait Disorders, Neurologic/physiopathology , Parkinson Disease/physiopathology , Aged , Brain Mapping , Female , Gait Disorders, Neurologic/complications , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Neural Pathways/physiopathology , Parkinson Disease/complications
12.
Nano Lett ; 18(6): 3682-3687, 2018 06 13.
Article in English | MEDLINE | ID: mdl-29733598

ABSTRACT

P-type two-dimensional steep-slope negative capacitance field-effect transistors are demonstrated for the first time with WSe2 as channel material and ferroelectric hafnium zirconium oxide in gate dielectric stack. F4-TCNQ is used as p-type dopant to suppress electron leakage current and to reduce Schottky barrier width for holes. WSe2 negative capacitance field-effect transistors with and without internal metal gate structures and the internal field-effect transistors are compared and studied. Significant SS reduction is observed in WSe2 negative capacitance field-effect transistors by inserting the ferroelectric hafnium zirconium oxide layer, suggesting the existence of internal amplification (∼10) due to the negative capacitance effect. Subthreshold slope less than 60 mV/dec (as low as 14.4 mV/dec) at room temperature is obtained for both forward and reverse gate voltage sweeps. Negative differential resistance is observed at room temperature on WSe2 negative capacitance field-effect-transistors as the result of negative capacitance induced negative drain-induced-barrier-lowering effect.

13.
Nano Lett ; 17(6): 3965-3973, 2017 06 14.
Article in English | MEDLINE | ID: mdl-28562056

ABSTRACT

Experimental demonstrations of one-dimensional (1D) van der Waals material tellurium (Te) have been presented by Raman spectroscopy under strain and magneto-transport. Raman spectroscopy measurements have been performed under strains along different principle axes. Pronounced strain response along the c-axis is observed due to the strong intrachain covalent bonds, while no strain response is obtained along the a-axis due to the weak interchain van der Waals interaction. Magneto-transport results further verify its anisotropic property, which results in dramatically distinct magneto-resistance behaviors in terms of three different magnetic field directions. Specifically, phase coherence length extracted from weak antilocalization effect, Lϕ ≈ T-0.5, claims its two-dimensional (2D) transport characteristics when an applied magnetic field is perpendicular to the thin film. In contrast, Lϕ ≈ T-0.33 is obtained from universal conductance fluctuations once the magnetic field is along the c-axis of Te, which indicates its nature of 1D transport along the helical atomic chains. Our studies, which are obtained on high quality single crystal Te thin film, appear to serve as strong evidence of its 1D van der Waals structure from experimental perspectives. It is the aim of this paper to address this special concept that differs from the previous well-studied 1D nanowires or 2D van der Waals materials.

14.
Nano Lett ; 16(10): 6701-6708, 2016 10 12.
Article in English | MEDLINE | ID: mdl-27649304

ABSTRACT

The Poisson's ratio of a material characterizes its response to uniaxial strain. Materials normally possess a positive Poisson's ratio - they contract laterally when stretched, and expand laterally when compressed. A negative Poisson's ratio is theoretically permissible but has not, with few exceptions of man-made bulk structures, been experimentally observed in any natural materials. Here, we show that the negative Poisson's ratio exists in the low-dimensional natural material black phosphorus and that our experimental observations are consistent with first-principles simulations. Through applying uniaxial strain along armchair direction, we have succeeded in demonstrating a cross-plane interlayer negative Poisson's ratio on black phosphorus for the first time. Meanwhile, our results support the existence of a cross-plane intralayer negative Poisson's ratio in the constituent phosphorene layers under uniaxial deformation along the zigzag axis, which is in line with a previous theoretical prediction. The phenomenon originates from the puckered structure of its in-plane lattice, together with coupled hinge-like bonding configurations.

15.
Nano Lett ; 16(12): 7364-7369, 2016 12 14.
Article in English | MEDLINE | ID: mdl-27960486

ABSTRACT

Transition metal pentatelluride ZrTe5 is a versatile material in condensed-matter physics and has been intensively studied since the 1980s. The most fascinating feature of ZrTe5 is that it is a 3D Dirac semimetal which has linear energy dispersion in all three dimensions in momentum space. Structure-wise, ZrTe5 is a layered material held together by weak interlayer van der Waals force. The combination of its unique band structure and 2D atomic structure provides a fertile ground for more potential exotic physical phenomena in ZrTe5 related to 3D Dirac semimentals. However, the physical properties of its few-layer form have yet to be thoroughly explored. Here we report strong optical and electrical in-plane anisotropy of mechanically exfoliated few-layer ZrTe5. Raman spectroscopy shows a significant intensity change with sample orientations, and the behavior of angle-resolved phonon modes at the Γ point is explained by theoretical calculations. DC conductance measurement indicates a 50% of difference along different in-plane directions. The diminishing of resistivity anomaly in few-layer samples indicates the evolution of band structure with a reduced thickness. A low-temperature Hall experiment sheds light on more intrinsic anisotropic electrical transport, with a hole mobility of 3000 and 1500 cm2/V·s along the a-axis and c-axis, respectively. Pronounced quantum oscillations in magnetoresistance are observed at low temperatures with the highest electron mobility up to 44 000 cm2/V·s.

17.
J Neurooncol ; 128(1): 47-56, 2016 05.
Article in English | MEDLINE | ID: mdl-26956263

ABSTRACT

Metastatic intracranial germinoma is difficult to treat. Although the proto-oncogene KIT is recognized as one of the most frequent genetic abnormalities in CNS germinoma, the development of new target therapeutic agents for CNS germinoma is hampered by the lack of clinically-relevant animal models that replicate the mutated or over-expressed KIT. CNS germinoma tumor cells from five pediatric patients were directly implanted into the brains of Rag2/severe combined immune deficiency mice. Once established, the xenograft tumors were sub-transplanted in vivo in mouse brains. Characterization of xenograft tumors were performed through histologic and immunohistochemical staining, and KIT mutation analysed with quantitative pyro-sequencing. Expression of putative cancer stem cell markers (CD133, CD15, CD24, CD44, CD49f) was analyzed through flow cytometry. Two patient-derived orthotopic xenograft (PDOX) models (IC-6999GCT and IC-9302GCT) were established from metastatic germinoma and serially sub-transplanted five times in mouse brains. Similar to the original patient tumors, they both exhibited faint expression (+) of PLAP, no expression (-) of ß-HCG and strong (+++) expression of KIT. KIT mutation (D816H), however, was only found in IC-9320GCT. This mutation was maintained during the five in vivo tumor passages with an increased mutant allele frequency compared to the patient tumor. Expression of putative cancer stem cell markers CD49f and CD15 was also detected in a small population of tumor cells in both models. This new pair of PDOX models replicated the key biological features of pediatric intracranial germinoma and should facilitate the biological and pre-clinical studies for metastatic intracranial germinomas.


Subject(s)
Brain Neoplasms/genetics , Germinoma/genetics , Neoplasm Transplantation , Proto-Oncogene Proteins c-kit/genetics , Adolescent , Animals , Biomarkers, Tumor/metabolism , Brain/metabolism , Brain/pathology , Brain Neoplasms/pathology , Child , Female , Germinoma/metabolism , Germinoma/pathology , Heterografts , Humans , Immunohistochemistry , Infant , Male , Mice, SCID , Neoplasm Metastasis , Neoplastic Stem Cells , Proto-Oncogene Mas , Sequence Analysis, DNA , Survival Analysis
18.
Nanotechnology ; 27(43): 434002, 2016 10 28.
Article in English | MEDLINE | ID: mdl-27658938

ABSTRACT

Black phosphorus (BP), the bulk counterpart of monolayer phosphorene, is a relatively stable phosphorus allotrope at room temperature. However, monolayer phosphorene and ultra-thin BP layers degrade in ambient atmosphere. In this paper, we report the investigation of BP oxidation and discuss the reaction mechanism based on the x-ray photoelectron spectroscopy (XPS) data. The kinetics of BP oxidation was examined under various well-controlled conditions, namely in 5% O2/Ar, 2.3% H2O/Ar, and 5% O2 and 2.3% H2O/Ar. At room temperature, the BP surface is demonstrated not to be oxidized at a high oxidation rate in 5% O2/Ar nor in 2.3% H2O/Ar, according to XPS, with the thickness of the oxidized phosphorus layer <5 Å for 5 h. On the other hand, in the O2/H2O mixture, a 30 Å thickness oxide layer was detected already after 2 h of the treatment. This result points to a synergetic effect of water and oxygen in the BP oxidation. The oxidation effect was also studied in applications to the electrical measurements of BP field-effect transistors (FETs) with or without passivation. The electrical performance of BP FETs with atomic layer deposition (ALD) dielectric passivation or h-BN passivation formed in a glove-box environment are also presented.

19.
Chem Soc Rev ; 44(9): 2732-43, 2015 May 07.
Article in English | MEDLINE | ID: mdl-25307017

ABSTRACT

Phosphorus is one of the most abundant elements preserved in earth, and it comprises a fraction of ∼0.1% of the earth crust. In general, phosphorus has several allotropes, and the two most commonly seen allotropes, i.e. white and red phosphorus, are widely used in explosives and safety matches. In addition, black phosphorus, though rarely mentioned, is a layered semiconductor and has great potential in optical and electronic applications. Remarkably, this layered material can be reduced to one single atomic layer in the vertical direction owing to the van der Waals structure, and is known as phosphorene, in which the physical properties can be tremendously different from its bulk counterpart. In this review article, we trace back to the research history on black phosphorus of over 100 years from the synthesis to material properties, and extend the topic from black phosphorus to phosphorene. The physical and transport properties are highlighted for further applications in electronic and optoelectronics devices.

20.
Cancer Metastasis Rev ; 33(1): 173-81, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24346160

ABSTRACT

The major functions of Hippo (Hpo) signaling pathway are to control cell growth, proliferation, and apoptosis. As its important downstream player, yes-associated protein (YAP)-1 was originally found to promote cell proliferation and transformation. Overexpression of YAP-1 has been linked to tumor progression and worse survival in certain malignancies. However, it has been recently recognized as a tumor suppressor gene as well since it also induces apoptosis. Decreased or absent expression of YAP-1 is highly correlated with tumor progression and worse survival in other tumors such as breast cancer. It is clear that YAP-1 plays a dual role as oncogene and tumor suppressor gene in human oncogenesis, depending on the specific tissue type involved. Here, we reviewed the recent research on both the oncogenic and tumor suppressor function of YAP-1 and its significance in human malignancy. The clinical implication of YAP-1 expression in cancer prognosis and the development of targeted therapy will also be discussed.


Subject(s)
Adaptor Proteins, Signal Transducing/genetics , Cell Proliferation/genetics , Neoplasms/genetics , Phosphoproteins/genetics , Adaptor Proteins, Signal Transducing/metabolism , Apoptosis/genetics , Gene Expression Regulation, Neoplastic , Humans , Models, Genetic , Neoplasm Metastasis , Neoplasms/metabolism , Neoplasms/pathology , Oncogene Proteins/genetics , Oncogene Proteins/metabolism , Phosphoproteins/metabolism , Transcription Factors , Tumor Suppressor Proteins/genetics , Tumor Suppressor Proteins/metabolism , YAP-Signaling Proteins
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