"Freeing" Graphene from Its Substrate: Observing Intrinsic Velocity Saturation with Rapid Electrical Pulsing

Rapid (nanosecond-scale) electrical pulsing is used to study drift-velocity saturation in graphene field-effect devices. In these experiments, high-field pulses are utilized to drive graphene's carriers on time scales much faster than that on which energy loss to the underlying substrate can occur, thereby allowing the observation of the highest saturation velocities reported to date. In a dramatic departure from the behavior exhibited by conventional metals and semiconductors, as the electron or hole density is reduced toward the charge-neutrality point, the drift velocity is found to reach values comparable to the Fermi velocity itself. Corresponding current densities are as large as 10(9) A/cm(2), similar to the values reported for carbon nanotubes and for graphene-on-diamond transistors. In essence, our approach of rapid pulsing allows us to "free" graphene from the deleterious influence of its substrate, revealing a pathway to achieve the superior electrical performance promised by this material. The usefulness of this approach is not merely limited to graphene but should extend also to a broad variety of two-dimensional semiconductors.

Block copolymer synthesis by controlled/living radical polymerisation in heterogeneous systems

We review the range of CLRP-controlled syntheses of block copolymer particles in dispersed systems, which are being exploited to create new opportunities for the design of nanostructured soft materials.

Palladium-catalyzed arylation of β-methylene C(sp3)–H bonds at room temperature: desymmetrization of simple cycloalkyl carboxylic acids

A new protocol for Pd-catalyzed β methylene C–H arylation of N-quinolyl cycloalkylcarboxamides with aryl iodides at room temperature is reported.

Hippocampal neurogenesis in the APP/PS1/nestin-GFP triple transgenic mouse model of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common causes of dementia. Although the exact mechanisms of AD are not entirely clear, the impairment in adult hippocampal neurogenesis has been reported to play a role in AD. To assess the relationship between AD and neurogenesis, we studied APP/PS1/nestin-green fluorescent protein (GFP) triple transgenic mice, a well-characterized mouse model of AD, which express GFP under the control of the nestin promoter. Different ages of AD mice and their wild-type littermates (WT) were used in our study. Immunofluorescent staining showed that neurogenesis occurred mainly in the subgranular zone (SGZ) of the dentate gyrus (DG) and subventricular zone (SVZ) of the lateral ventricles (LVs). The expression of neural stem cells (NSCs) (nestin) and neural precursors such as doublecortin (DCX) and GFAP in AD mice were decreased with age, as well as there being a reduction in 5-bromo-2-deoxyuridine (BrdU)-positive cells, when compared to WT. However, the number of maturate neurons (NeuN) was not significantly different between AD mice and wild-type controls, and NeuN changed only slightly with age. By Golgi-Cox staining, the morphologies of dendrites were observed, and significant differences existed between AD mice and wild-type controls. These results suggest that AD has a far-reaching influence on the regulation of adult hippocampal neurogenesis, leading to a gradual decrease in the generation of neural progenitors (NPCs), and inhibition of the differentiation and maturation of neurons.

Conduction Mechanisms in CVD-Grown Monolayer MoS2 Transistors: From Variable-Range Hopping to Velocity Saturation

We fabricate transistors from chemical vapor deposition-grown monolayer MoS2 crystals and demonstrate excellent current saturation at large drain voltages (Vd). The low-field characteristics of these devices indicate that the electron mobility is likely limited by scattering from charged impurities. The current-voltage characteristics exhibit variable range hopping at low Vd and evidence of velocity saturation at higher Vd. This work confirms the excellent potential of MoS2 as a possible channel-replacement material and highlights the role of multiple transport phenomena in governing its transistor action.

Abstract 751: In vitro activity of dianhydrogalactitol alone or with platinum drugs in the treatment of non-small cell lung cancer

The median overall survival time for patients with stage IV non-small cell lung cancer (NSCLC) is 4 months, and 1- and 5-year survival is less than 16% and 2%, respectively. NSCLC is usually treated with surgery followed by treatment with either Tyrosine Kinase Inhibitors (TKIs) or platinum-based regimens. Unfortunately, TKI resistance has emerged as a significant unmet medical need, and long-term prognosis with platinum-based therapies is poor. Dianhydrogalactitol (VAL-083) is a structurally unique bi-functional alkylating agent mediating interstrand DNA crosslinks at N7 of guanine. It has previously demonstrated activity against NSCLC in preclinical and clinical trials, and is approved for treatment of lung cancer in China, suggesting that it may be a therapeutic option for drug-resistant NSCLC. However, the underlying basis for its activity remains unclear. We thus aimed to investigate in vitro i) the role of p53 status in the activity of VAL-083, ii) VAL-083 activity in comparison to cisplatin and oxaliplatin, and iii) the combination of VAL-083 with cisplatin or oxaliplatin.

The dependence on p53 status was investigated in isogenic models with (HCT-116p53-/-) or without (HCT-116p53+/+) p53 knockout. The cytotoxic activity of VAL-083 was tested in a panel of 9 human NSCLC cell lines, of which 4 were wild-type (wt) p53, 4 were mutant p53 and 1 was null for p53. The potential for combination was investigated by determining superadditivity and assessing synergy using the criteria of combination index (CI) of <1, obtained by following the Compusyn constant-dose ratio protocol. Cytotoxicty in all cases was monitored on day 5 with the MTT assay.

Studies in HCT-116 models demonstrated that loss of p53 increased resistance to cisplatin and oxaliplatin by 3- and 6-fold, respectively, whereas resistance to VAL-083 was <2-fold. As single agents, VAL-083, cisplatin and oxaliplatin displayed cytotoxic activity in all 9 NSCLC cell lines to varying degrees, with H460 being the most sensitive to the three agents (IC50 < 0.5 uM). The IC50 in the other cell lines ranged from 0.9 to 6.1 μM, 0.5 to 2.2 μM and 0.6 to 2.6 μM for VAL-083, cisplatin and oxaliplatin, respectively, and there was no overt difference in drug sensitivity between the wt and mutant/null p53 group. This suggests that either wt p53 is not activated and/or other genetic alterations attenuate cytotoxic activities. If the agents have similar mode of action, then combinations may only demonstrate cytotoxic additivity. However, the combination of VAL-083 with cisplatin or oxaliplatin in the A549 NSCLC model, demonstrated significant superadditivity (p<0.05) and synergism (CI < 1) for both combinations. This strongly favors non-overlapping mechanism of action between the platinum drugs and VAL-083. In conclusion, VAL-083 is less dependent on p53 for its activity, and demonstrates superadditivity/synergy against NSCLC cells when combined with either cisplatin or oxaliplatin.

Citation Format: Anne Steino, Guangan He, Jeffrey A. Bacha, Sarath Kanekal, Dennis M. Brown, Zahid H. Siddik. In vitro activity of dianhydrogalactitol alone or with platinum drugs in the treatment of non-small cell lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 751. doi:10.1158/1538-7445.AM2015-751

Phase I study of azacitidine and oxaliplatin in patients with advanced cancers that have relapsed or are refractory to any platinum therapy

Background

Demethylation process is necessary for the expression of various factors involved in chemotherapy cytotoxicity or resistance. Platinum-resistant cells may have reduced expression of the copper/platinum transporter CTR1. We hypothesized that azacitidine and oxaliplatin combination therapy may restore platinum sensitivity. We treated patients with cancer relapsed/refractory to any platinum compounds (3 + 3 study design) with azacitidine (20 to 50 mg/m²/day intravenously (IV) over 15 to 30 min, D1 to 5) and oxaliplatin (15 to 30 mg/m²/day, IV over 2 h, D2 to 5) (maximum, six cycles). Platinum content, LINE1 methylation (surrogate of global DNA methylation), and CTR1 expression changes (pre- vs. post-treatment) were assessed. Drug pharmacokinetics were analyzed.

Results

Thirty-seven patients were treated. No dose-limiting toxicity (DLT) was noted at the maximum dose. The most common adverse events were anemia and fatigue. Two (5.4%) patients had stable disease and completed six cycles of therapy. Oxaliplatin (D2) and azacitidine (D1 and 5) mean systemic exposure based on plasma AUC_all showed dose-dependent interaction whereby increasing the dose of oxaliplatin reduced the mean azacitidine exposure and vice versa; however, no significant differences in other non-compartmental modeled parameters were observed. Blood samples showed universal reduction in global DNA methylation. In tumor samples, hypomethylation was only observed in four out of seven patients. No correlation between blood and tumor demethylation was seen. The mean cytoplasmic CTR1 score decreased. The pre-dose tumor oxaliplatin levels ranged from <0.25 to 5.8 μg/g tumor. The platinum concentration increased 3- to 18-fold. No correlation was found between CTR1 score and oxaliplatin level, which was found to have a trend toward correlation with progression-free survival.

Conclusions

Oxaliplatin and azacitidine combination therapy was safe. CTR1 expression was not correlated with methylation status or tissue platinum concentration.

Electronic supplementary material

The online version of this article (doi:10.1186/s13148-015-0065-5) contains supplementary material, which is available to authorized users.

ENaC mediates human extravillous trophblast cell line (HTR8/SVneo) invasion by regulating levels of matrix metalloproteinase 2 (MMP2)

INTRODUCTION

Placenta dysfunction is thought to be the major etiological factor related to preeclampsia. The epithelial sodium channel (ENaC) has been localized in the apical plasma membrane of epithelia, mediating the active reabsorption of sodium in kidney, and be involved in the regulation of blood pressure. In previous studies, we found that the reduced expression of ENaC on placenta in preeclampsia patients. The aim of this study was to determine the role of MMP2 in the ENaC-induced trophoblast cell invasion ability, which is closely related to the occurrence of preeclampsia.

METHODS

Here we checked whether pregnancy related hormones human chorionic gonadotropin (HCG), prolactin and aldosterone could affect ENaC expression in the first trimester extravillous trophoblast cell line (HTR8/SVneo) by RT-PCR and Western blot. Cell invasion was studied by matrigel invasion assay. Tube formation assay was used to investigate the interaction between trophoblast cells and endothelial cells. The effects of ENaC on MMP2 were further determined by RT-PCR, western blot and gelatin zymography.

RESULTS

We demonstrated that HCG, prolactin and aldosterone could up-regulate the expression of αENaC in protein levels. Trophoblast cell invasion ability is stimulated when αENaC was up-regulated by aldosterone, and inhibited when ENaC was down-regulated by amiloride and αENaC specific RNAi (SiENA/ENaC). The interaction between HTR8/SVneo cells and HUVEC cells was enhanced when treated with aldosterone and weakened when treated with amiloride and SiRNA/ENaC. Amiloride and SiRNA/ENaC could inhibit MMP2 expression and activity.

DISSCUTION

Aldosterone induced ENaC activity is important for trophoblast cells invasion. The results also indicate that ENaC could mediate trophoblast cells invasion ability through regulating expression and activity of matrix metalloproteinase-2 (MMP2).

Palladium-catalyzed alkylation of unactivated C(sp3)–H bonds with primary alkyl iodides at room temperature: facile synthesis of β-alkyl α-amino acids

Practical synthesis of β-alkyl α-amino acidsviaC(sp³)–H alkylation at room temperature.

Abstract CT201: Phase I study of 5-azacytidine and oxaliplatin in patients with advanced cancers relapsed or refractory to platinum compounds

Purpose: To explore whether the hypomethylating agent 5-azacytidine (5-aza) restores platinum sensitivity.

Experimental Design: Patients with advanced cancer relapsed/refractory to platinum compounds were treated with 5-aza 20-50 mg/m2/d IV (D 1-5) and oxaliplatin 15-30 mg/m2/d IV (D 2-5) (“3+3” design escalation phase followed by expansion phase; NCT01039155). PK studies were performed. Global DNA and gene-specific methylation changes (baseline to D12) in blood and tissue, tissue platinum level, and CTR1 (copper transporter involved in platinum uptake) expression were assessed (expansion phase).

Results: Overall, 37 patients were treated (median age, 59 yrs; men, 49%; prior: oxaliplatin, 68%; carboplatin, 30%; cisplatin, 16%) (escalation, n=21; expansion, n=16). No DLT was noted at the maximum dose level tested (5-aza, 50 mg/m2/d; oxaliplatin 30 mg/m2/d; used in expansion phase). The most common adverse events were anemia (49% of pts.) and fatigue (32%). LINE-1 was measured (surrogate for global DNA methylation) in pre- and post-treatment blood samples (9 patients) and in tumor samples (7 patients). All blood samples showed reduction in global DNA methylation (baseline to D12) (median, -22%; range, [-32%, -12%], p&lt;.0001). Paired tumor and blood pre- and post-treatment samples were available in 2 patients. In paired comparison, 1 patient had reduction in global methylation both in tumor and blood (-34% and -32%, respectively); and 1 patient had increased methylation in tumor (+52%) and decreased in blood (-22%).

The mean cytoplasmic CTR1 score was 217.5 and 177.5 on D1 and D12, respectively (mean difference, -40; 95% CI: -69.1,-10.9; p=.02). The respective mean nuclear CTR1 score was 67.5 and 42.5 (mean difference, -25; 95% CI: -55.5,+5.5; p=.08). Oxaliplatin (D2) and 5-aza (D1 and 5) mean systemic exposure based on plasma AUCall resulted in a dose-dependent trend (oxaliplatin 15 to 30 mg/m2, 704.3 to 1149.0 hr·ng/mL; 5-aza 20 to 50 mg/m2, 112.5 to 404.5 [D1] and 143.7 to 426.5 hr·ng/mL [D5]). When the same dose of oxaliplatin was used with increasing doses of 5-aza from 25-50 mg/m2, a reduction in mean oxaliplatin exposure was noted (AUCinf: 1919.4 to 1455.9 hr·ng/mL). No significant differences in other non-compartmental modeled parameters estimated were observed. The total tumor oxaliplatin level was measured in 7 patients. The pre-dose levels ranged from &lt;.25 to 5.8 µg/g tumor (median, .59). The post-dose levels increased 3- to 18-fold (median, 3.8) in 5 post-dose samples (mean difference, 1.48 µg/g; 95% CI: .01,2.95; p=.049). Two patients, having the highest pre-dose level, had unchanged levels. Two (5.4%) patients (colon, n=1; prostate, n=1) had stable disease and received 6 cycles of therapy.

Conclusion: 5-aza combined with oxaliplatin was safe. Hypomethylation was inconsistent in tumor tissue, the CTR1 score decreased and the tumor oxaliplatin level increased.

Citation Format: Apostolia M. Tsimberidou, Kirk Culotta, Ignacio Wistuba, Siqing Fu, Aung Naing, Gerald Falchook, Sarina Piha-Paul, Ralph Zinner, Jaime Rodriguez-Canales, Guangan He, Zahid H. Siddik, Jaroslav Jelinek, Woonbok Chung, Yang Ye, Rabih Said, Kenneth Hess, David J. Stewart, Razelle Kurzrock, Jean-Pierre Issa. Phase I study of 5-azacytidine and oxaliplatin in patients with advanced cancers relapsed or refractory to platinum compounds. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr CT201. doi:10.1158/1538-7445.AM2014-CT201

Matrine-induced apoptosis of human nasopharyngeal carcinoma cells via in vitro vascular endothelial growth factor-A/extracellular signal-regulated kinase1/2 pathway inactivation

Matrine, a main active extract from Sophora flavescens Ait, has been demonstrated to exert anticancer effects on various cancer cell lines, such as malignant melanoma, breast cancer, and lung cancer. However, it is currently unclear whether matrine could also elicit an inhibitory effect on growth of nasopharyngeal carcinoma (NPC), let alone the possible molecular mechanisms. Therefore, in a previous study, we investigated matrine-induced proliferation inhibition and apoptosis in NPC cells. It was shown that proliferation of human NPC cells (CNE1 and CNE2) was significantly diminished by matrine in a dose- and time-dependent manner, and apoptosis was induced in both 2 NPC cells, particularly in CNE2 cells. Moreover, the increased apoptosis rate in matrine-treated CNE2 cells confirmed the proapoptotic activity of matrine. We further found that matrine treatment dose- and time-dependently reduced the levels of vascular endothelial growth factor-A (VEGF-A), and inactivated extracellular signal-regulated kinase1/2 (ERK1/2), followed by increased expression of downstream target caspase-3. Overall, we conclude that matrine could induce apoptosis of human NPC cells via VEGF-A/ERK1/2 pathway, which supports the potential use of matrine in clinically treating NPC.

Surface characterization and osteoblast response to a functionally graded hydroxyapatite/fluoro-hydroxyapatite/titanium oxide coating on titanium surface by sol-gel method

OBJECTIVES

To improve efficacy of current titanium and its alloys, in bioactivity and speed of osseointegration, of orthopaedic implants.

MATERIALS AND METHODS

A novel triple-layered functional graded coating, consisting of a porous hydroxyapatite (HA) outermost layer, fluoro-HA (FHA) intermediate layer and titanium oxide (TiO2 ) innermost layer, was created on a titanium substrate by a multistep sol-gel method. X-ray diffraction analysis showed TiO2 anatase and apatite crystallization in the coating.

RESULTS

Morphological analysis performed by scanning electron microscopy showed excellent bonding between coating and substrate, with a thickness of ~2 μm. Scratch testing found favourable adhesion strength of the composite coating. In addition, optical microscope images suggested good biocompatibility. Considering thet in vitro cell response, osteoblasts on the coating exhibited higher cell proliferation and ALP activity compared to pure titanium and HA coating, and demonstrated excellent coating bioactivity.

CONCLUSIONS

Current results indicated that the novel TiO2 /FHA/HA coating has promising clinical applications in orthopaedic and dental implantation.

Neither cytochrome P450 family genes nor neuroendocrine factors could independently predict the SSRIs treatment in the Chinese Han population

OBJECTIVE

This study was intended to explore the relationship between the genetic polymorphisms of the 8 single nucleotide polymorphisms (SNPs) at CYP genes, neuroendocrine factors and the response to selective serotonin reuptake inhibitors (SSRIs) in Chinese Han depressive patients.

METHOD

This was a 6-week randomized controlled trial consisting of 290 Chinese Han depressive patients treated with SSRIs. 8 SNPs of CYP450 genes and 7 neuroendocrine factors were detected. Allele and genotype frequencies were compared between responders and non-responders. The relationships between neuroendocrine factors and treatment response were also analyzed.

RESULTS

No significant differences were found in clinical features between 2 groups at the baseline. No statistical correlation was found between either the genotype or allele frequencies of SNPs in CYP1A2, CYP2C19, or CYP2D6 gene and the -efficacy of SSRIs. There were strong linkage disequilibria between rs4986894, rs1853205, and rs12767583 of CYP2C19 genes, and rs2472299, rs2472300 of CYP1A2 genes. No associations were found between the above haplotypes and the antidepressant response. No neuroendocrine factor was a significant predictor for a response to SSRI antidepressants independently. The combination of neuroendocrine factors, however, predicted the response by 76.1%.

CONCLUSION

There were no significant associations between the 6 SNPs of CYP gene polymorphisms and SSRI response. Neither cytochrome P450 family genes nor neuroendocrine factors independently predict the patients' response to the antidepressants separately. A combination of neuroendocrine factors, however, does have the potential to predict the response.

Selective neuronal differentiation of neural stem cells induced by nanosecond microplasma agitation

An essential step for therapeutic and research applications of stem cells is their ability to differentiate into specific cell types. Neuronal cells are of great interest for medical treatment of neurodegenerative diseases and traumatic injuries of central nervous system (CNS), but efforts to produce these cells have been met with only modest success. In an attempt of finding new approaches, atmospheric-pressure room-temperature microplasma jets (MPJs) are shown to effectively direct in vitro differentiation of neural stem cells (NSCs) predominantly into neuronal lineage. Murine neural stem cells (C17.2-NSCs) treated with MPJs exhibit rapid proliferation and differentiation with longer neurites and cell bodies eventually forming neuronal networks. MPJs regulate ~75% of NSCs to differentiate into neurons, which is a higher efficiency compared to common protein- and growth factors-based differentiation. NSCs exposure to quantized and transient (~150 ns) micro-plasma bullets up-regulates expression of different cell lineage markers as β-Tubulin III (for neurons) and O4 (for oligodendrocytes), while the expression of GFAP (for astrocytes) remains unchanged, as evidenced by quantitative PCR, immunofluorescence microscopy and Western Blot assay. It is shown that the plasma-increased nitric oxide (NO) production is a factor in the fate choice and differentiation of NSCs followed by axonal growth. The differentiated NSC cells matured and produced mostly cholinergic and motor neuronal progeny. It is also demonstrated that exposure of primary rat NSCs to the microplasma leads to quite similar differentiation effects. This suggests that the observed effect may potentially be generic and applicable to other types of neural progenitor cells. The application of this new in vitro strategy to selectively differentiate NSCs into neurons represents a step towards reproducible and efficient production of the desired NSC derivatives.

Recruitment of trimeric proliferating cell nuclear antigen by G1-phase cyclin-dependent kinases following DNA damage with platinum-based antitumour agents

BACKGROUND

In cycling tumour cells, the binary cyclin-dependent kinase Cdk4/cyclin D or Cdk2/cyclin E complex is inhibited by p21 following DNA damage to induce G1 cell-cycle arrest. However, it is not known whether other proteins are also recruited within Cdk complexes, or their role, and this was investigated.

METHODS

Ovarian A2780 tumour cells were exposed to the platinum-based antitumour agent 1R,2R-diaminocyclohexane(trans-diacetato)(dichloro)platinum(IV) (DAP), which preferentially induces G1 arrest in a p21-dependent manner. The Cdk complexes were analysed by gel filtration chromatography, immunoblot and mass spectrometry.

RESULTS

The active forms of Cdk4 and Cdk2 complexes in control tumour cells have a molecular size of ~140 kDa, which increased to ~290 kDa when inhibited following G1 checkpoint activation by DAP. Proteomic analysis identified Cdk, cyclin, p21 and proliferating cell nuclear antigen (PCNA) in the inhibited complex, and biochemical studies provided unequivocal evidence that the increase in ~150 kDa of the inhibited complex is consistent with p21-dependent recruitment of PCNA as a trimer, likely bound to three molecules of p21. Although p21 alone was sufficient to inhibit the Cdk complex, PCNA was critical for stabilising p21.

CONCLUSION

G1 Cdk complexes inhibited by p21 also recruit PCNA, which inhibits degradation and, thereby, prolongs activity of p21 within the complex.

Fast energy relaxation of hot carriers near the Dirac point of graphene

We investigate energy relaxation of hot carriers in monolayer and bilayer graphene devices, demonstrating that the relaxation rate increases significantly as the Dirac point is approached from either the conduction or valence band. This counterintuitive behavior appears consistent with ideas of charge puddling under disorder, suggesting that it becomes very difficult to excite carriers out of these localized regions. These results therefore demonstrate how the peculiar properties of graphene extend also to the behavior of its nonequilibrium carriers.

Topographical distribution pattern of cervical intraepithelial neoplasia across the cervix

OBJECTIVE

The distribution of cervical intraepithelial neoplasia (CIN) lesions across the cervix was determined.

METHODS

A total of 575 women whose pathological diagnosis after cervical conization was confirmed as CIN were studied; 146 had low-grade CIN and 429 had high-grade CIN. CIN lesion location on the cervix was recorded using 12-h clock face notation.

RESULTS

In both groups, 12 o'clock was the most common and 2 o'clock the least common lesion location. The most severe lesions were most often located at 8 o'clock and 7 o'clock, in the low- and high-grade groups, respectively. The 2 o'clock site was the least frequent site for the most severe lesion in both groups. Lesions were found more frequently on the posterior lip of the cervix than on the anterior lip, and on the right side of the cervix than on the left side, in both groups.

CONCLUSIONS

The distribution of CIN lesions is not randomly distributed across the cervix. The 12, 8 and 7 o'clock sites, and the posterior lip and right side of the cervix, should be targeted during colposcopy-directed biopsy of patients with CIN lesions as this may improve diagnostic accuracy.