Viewing the Interaction Between Double Strand Deoxyribonucleic Acid and Graphene Oxide via Atomic Force Microscopy

The interaction between DNA and graphene-oxide (GO) is fundamental and of significance to a number of biomedical applications. It is fairly clear that π-π stacking effect accounts for the strong interaction between ssDNA and GO, while little is known on the mechanics of the relative weak interaction between dsDNA and GO. Here we employ AFM to investigate the coupling behavior of dsDNA-GO duplex and reveal preference adsorption of DNAon GO. The results show that dsDNA tends to aggregate on GO surface. Additionally, it is observed that GO also tend to stack into multi-layer structure in the presence of dsDNA, indicating dsDNA can simultaneously interact with two sides of the GO sheet. Such a structure is, however, unstable and can easily collapse by rinsing or heating.

Ultraviolet Electroluminescence from ZnS@ZnO Core-Shell Nanowires/p-GaN Introduced by Exciton Localization

We investigate the electroluminescence (EL) from light emitting diodes (LEDs) of ZnO nanowires/p-GaN structure and ZnS@ZnO core-shell nanowires/p-GaN structure. With the increase of forward bias, the emission peak of ZnO nanowires/p-GaN structure heterojunction shows a blue-shift, while the ZnS@ZnO core-shell nanowires/p-GaN structure demonstrates a changing EL emission; the ultraviolet (UV) emission at 378 nm can be observed. This discrepancy is related to the localized states introduced by ZnS particles, which results in a different carrier recombination process near the interfaces of the heterojunction. The localized states capture the carriers in ZnO nanowires and convert them to localized excitons under high forward bias. A strong UV emission due to localized excitons can be observed. Our results indicated that utilizing localized excitons should be a new route toward ZnO-based ultraviolet LEDs with high efficiency.

Core-resonant double photoemission from palladium films

We studied the core-resonant double photoemission process from palladium films with linearly polarized synchrotron radiation. We excited either the 3d or 4p core level and focused on the Auger transitions which leave two holes in the valence band. We find that the two-dimensional energy distributions are markedly different for the 3d and 4p decay. The 3d decay can be understood by a sequential emission of the two electrons while the 4p decay proceeds in a single step. Despite the large differences in the two-dimensional energy spectra we find the shape of the energy sum spectra rather similar. For the description of the 4p decay we propose a model which uses available single electron spectra, but suggest an alternative interpretation of these data. With this we are able to explain the range over which the available energy is shared. Key assumptions of the model are verified by our experiments on the 3d decay.

Artificial pneumothorax for pain relief during microwave ablation of subpleural lung tumors

BACKGROUND

When microwave ablation (MWA) is used for subpleural lesions, severe pain was the common side effect under the local anesthesia conditions during the procedure and postprocedure. To study the pain relief effect of artificial pneumothorax in the treatment of subpleural lung tumors with MWA.

MATERIALS AND METHODS

From February 2012 to October 2014, 37 patients with 40 subpleural lung tumors underwent MWA, including 17 patients of 19 sessions given artificial pneumothorax prior to MWA (group-I), and 20 patients of 21 sessions without artificial pneumothorax (group-II). Patient's pain assessment scores (10-point visual analog scale [VAS]) at during-procedure, 6, 12, 24, and 48 h after the MWA procedure and mean 24 h morphine dose were compared between the two groups. Complications of the artificial pneumothorax were also summarized.

RESULTS

Pain VAS were 0.53, 0.65, 1.00, 0.24, and 0.18 at during-procedure, 6, 12, 24, and 48 h for group-I and 5.53, 2.32, 2.82, 1.21, and 0.21 for group-II, respectively. Pain VAS in group I was significantly decreased at during-procedure, 6, 12, and 24 h after the MWA (P < 0.001). No statistical pain VAS difference was observed at 48 h after the MWA between the two groups (P > 0.05). The mean 24 h morphine dose was 5.00 mg in group-I and 12.63 mg in group-II (P = 0.000). "Artificial pneumothorax" related complications occurred in two patients from group-I, including one pleural effusion and one minor hemoptysis. No patient in group-I and group-II died during the procedure or in 30 days after MWA.

CONCLUSION

Artificial pneumothorax is a safe and effective method for pain relief during MWA of subpleural lung tumors.

Abstract AS31: MEK inhibition reverses antiestrogen resistance in ovarian cancer (OVCA) via alteration of cell cycle pathways and MAPK/estrogen regulated gene expression

BACKGROUND: It is estimated that 67% of epithelial OVCAs are estrogen receptor (ER) positive. However, the response to anti-estrogen therapy in OVCA remains marginal. The Ras/Raf/MEK/MAPK pathway is hyperactivated in 40% of OVCAs. We have previously shown that estrogens further activate kinases such as Src, ER and Src kinase binding in the cytoplasm suggesting a non-genomic role or ER in OVCA. We postulated that estrogens further activate MAPK signaling and combination ER blockade with MEK inhibition would block cross-talk and increase the efficacy of ER blockade.

METHODS: The effects of treatment with MEK inhibitor (AZD6244) and anti-estrogen (Fulvestrant), each alone or together, on cell cycle and cell survival were evaluated in ER+ OVCA lines in vitro. Drug effects on xenograft tumor growth were assayed in vivo in NOD/SCIDs. Reverse phase protein lysate array (RPPA) analysis and gene expression analysis (GEA) were performed to evaluate biomarkers of drug response. Finally, a previously reported MAPK gene signature identified in breast cancer was analyzed in the OVCA lines treated with AZD6244 and combination treatment. And using alteration of gene expression upon MEKi treatment as suggestive of MAPK regulation, we define a MAPK gene signature originating from ovarian cancer cells.

RESULTS: RPPA analysis of high grade serous tumors from the TCGA (n=408) demonstrates that over 70% of tumors have phosphorylated MEK and MAPK, and patients with ER+ cancers and high pMAPK or pMEK (top50%), have a worse overall survival than those with low pMAPK or pMEK. Estrogen (E2) increases phosphorylation of MEK in ER+ OVCA cells. Fulvestrant caused minimal growth arrest after treatment demonstrating intrinsic resistance. AZD6244 caused loss of pMAPK, partial G1 cell cycle arrest and a modest increase in p27 levels in a dose dependent manner after treatment. However, responsiveness of OVCA cells to fulvestrant increased by addition of AZD6244 in vitro, with synergistic cell cycle arrest mediated by p27 binding to Cyclin E/cdk2 and much greater inhibition of MAPK activity. Gene enrichment analysis showed an increase in the ERB4/MAPK gene set with Fulv alone and the addition of AZD6244 showed that the top 20 gene sets downregulated were all related to replication and cell cycle (ie FOXM1, CyclinE). RPPA confirmed that combination was more effective in decreasing cell cycle promoting proteins (ie FOXM1, Cyclin B1) and upregulating p27. AZD6244 treatment of OVCA lines resulted in differential expression of about ¼ of the breast cancer defined MAPK gene expression signature, and of these, fulvestrant addition to MEK inhibition (MEKi) differentially affected 19 genes, reflective of these being E2 regulated genes. Similarly, of the total MEKi affected genes, a subset were differentially regulated by the addition of fulvestrant indicating putative E2 regulation underlying these genes. Xenograft data showed the greatest decrease in tumor volume with the drug combination compared to either drug alone.

CONCLUSION: Given the majority of primary OVCAs express high MEK/MAPK activity may underlie failure of anti-estrogen therapy. MEK inhibition reverses anti-estrogen resistance in our OVCA models. These data support further pre-clinical and clinical evaluation of combined fulvestrant and MEK inhibition in OVCA.

Citation Format: K. Hew, P. Miller, J. Sun, Z. Wei, G. Zhang, Y. Lu, G. Mills, J. Slingerland, MD, PhD, D. El-Ashry, F. Simpkins. MEK inhibition reverses antiestrogen resistance in ovarian cancer (OVCA) via alteration of cell cycle pathways and MAPK/estrogen regulated gene expression [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS31.

Tracking a hospital outbreak of KPC-producing ST11 Klebsiella pneumoniae with whole genome sequencing

An outbreak of carbapenem-resistant Klebsiella pneumoniae strains emerged at a hospital, and was tracked in order to understand the spread of these infectious pathogens. A total of 66 K. pneumoniae strains were collected from sterile samples in 2012. The MICs of 20 antimicrobial agents were determined for all strains. Molecular typing was performed with pulsed-field gel electrophoresis (PFGE). Twelve blaKPC-producing K. pneumoniae strains isolated from ten patients were selected for whole genome sequencing. Phylogenetic reconstruction of these 12 strains was performed by the use of single-nucleotide polymorphism (SNP) row sequences of each draft genome sequence. Plasmids from the 12 strains were separated by S1 digestion and PFGE. The 12 K. pneumoniae strains isolated from the ten patients were deemed to be representative of the hospital outbreak, owing to their similar PFGE patterns. These 12 blaKPC-producing strains conferred multidrug resistance, which contrasted with the remaining 54, more susceptible, strains in the hospital. Differences in SNPs between each draft genome of the blaKPC-producing strains partitioned the 12 outbreak strains into three separate clades. The patients with each clade shared close hospital units. All 12 strains harboured at least one multidrug resistance plasmid. Strains showing high-level resistance may facilitate nosocomial dissemination and result in an infectious pathogen outbreak. Although the 12 blaKPC-producing K. pneumoniae strains possessed similar PFGE patterns, SNP variations throughout the genome allowed the strains to be divided into three clades. These results suggest that three independent transmission events led to hospital-wide dissemination of the outbreak strains.

Influence of Exciton Localization on the Emission and Ultraviolet Photoresponse of ZnO/ZnS Core-Shell Nanowires

The structural and optical properties of ZnO and ZnO/ZnS core-shell nanowires grown by a wet chemical method are investigated. The near-bandgap ultraviolet (UV) emission of the ZnO nanowires was enhanced by four times after coating with ZnS. The enhanced emission was attributed to surface passivation of the ZnO nanowires and localized states introduced during ZnS growth. The emission of the ZnO and ZnO/ZnS core-shell nanowires was attributed to neutral donor-bound excitons and localized excitons, respectively. Localized states prevented excitons from diffusing to nonradiative recombination centers, so therefore contributed to the enhanced emission. Emission from the localized exciton was not sensitive to temperature, so emission from the ZnO/ZnS core-shell nanowires was more stable at higher temperature. UV photodetectors based on the ZnO and ZnO/ZnS core-shell nanowires were fabricated. Under UV excitation, the device based on the ZnO/ZnS core-shell nanowires exhibited a photocurrent approximately 40 times higher than that of the device based on the ZnO nanowires. The differing photoresponse of the detectors was consistent with the existence of surface passivation and localized states. This study provides a means for modifying the optical properties of ZnO materials, and demonstrates the potential of ZnO/ZnS core-shell nanowires in UV excitonic emission and detection.

Elastocapillary coalescence of plates and pillars

When a fluid-immersed array of supported plates or pillars is dried, evaporation leads to the formation of menisci on the tips of the plates or pillars that bring them together to form complex patterns. Building on prior experimental observations, we use a combination of theory and computation to understand the nature of this instability and its evolution in both the two- and three-dimensional setting of the problem. For the case of plates, we explicitly derive the interaction torques based on the relevant physical parameters associated with pillar deformation, contact-line pinning/depinning and fluid volume changes. A Bloch-wave analysis for our periodic mechanical system captures the window of volumes where the two-plate eigenvalue characterizes the onset of the coalescence instability. We then study the evolution of these binary clusters and their eventual elastic arrest using numerical simulations that account for evaporative dynamics coupled to capillary coalescence. This explains both the formation of hierarchical clusters and the sensitive dependence of the final structures on initial perturbations, as seen in our experiments. We then generalize our analysis to treat the problem of pillar collapse in three dimensions, where the fluid domain is completely connected and the interface is a minimal surface with the uniform mean curvature. Our theory and simulations capture the salient features of experimental observations in a range of different situations and may thus be useful in controlling the ensuing patterns.

The LVV Auger line shape of sulfur on copper studied by Auger photoelectron coincidence spectroscopy

We have studied the line shapes of Cu(0 0 1)-p (2 × 2)S L2VV and L3VV Auger decay by means of Auger photoelectron coincidence spectroscopy. Measuring the LVV Auger spectrum in coincidence with S 2p1/2 and 2p3/2 photoelectrons respectively, we have been able to separate the two overlapping Auger spectra and determine their intrinsic line shapes. The two Auger transitions, though shifted in energy, display an identical line shape whose main features can be qualitatively understood considering a single particle approximation but are better described within a Cini-Sawatzky (CS) approach. Comparison between the experimental and the CS calculated spectra confirms that a substantial part of the Auger lines (∼20%) can be ascribed to decay events accompanied by the excitation of one additional electron-hole pair in the valence band. For the first time, the locality of the Auger process combined with the surface sensitivity of the APECS technique and its ability to separate overlapping structures are used to study Auger transitions taking place at the the surface states of a S/noble-metal interface.

Determination of trace labile copper in environmental waters by magnetic nanoparticle solid phase extraction and high-performance chelation ion chromatography

Cobalt magnetic nanoparticles surface functionalised with iminodiacetic acid were evaluated as a nano-particulate solid phase extraction absorbent for copper ions (Cu(2+)) from environmental water samples. Using an external magnetic field, the collector nanoparticles could be separated from the aqueous phase, and adsorbed ions simply decomplexed using dilute HNO3. Effects of pH, buffer concentration, sample and sorbent volume, extraction equilibrium time, and interfering ion concentration on extraction efficiency were investigated. Optimal conditions were then applied to the extraction of Cu(2+) ions from natural water samples, prior to their quantitation using high-performance chelation ion chromatography. The limits of detection (LOD) of the combined extraction and chromatographic method were ~0.1 ng ml(-1), based upon a 100-fold preconcentration factor (chromatographic performance; LOD=9.2 ng ml(-1) Cu(2+)), analytical linear range from 20 to 5000 ng mL(-1), and relative standard deviations=4.9% (c=1000 ng ml(-1), n=7). Accuracy and precision of the combined approach was verified using a certified reference standard estuarine water sample (SLEW-2) and comparison of sample determinations with sector field inductively coupled plasma mass spectrometry. Recoveries from the addition of Cu(2+) to impacted estuarine and rain water samples were 103.5% and 108.5%, respectively. Coastal seawater samples, both with and without prior UV irradiation and dissolved organic matter removal were also investigated using the new methodology. The effect of DOM concentration on copper availability was demonstrated.

Dynamic screening probed by core-resonant double photoemission from surfaces

The universal response of a sudden created core hole, predicted to occur on an attosecond (10(-18)  s) time scale, lacks an experimental demonstration. With a two-dimensional coincidence spectrometer, we demonstrate an extensive energy sharing between the Ag 4p photoelectron and the N2,3VV Auger electron exceeding 10 eV. This energy width provides access to the time scale of the emission process. This is the fingerprint of the dynamic fluctuation process 4p(-1)⇌4d(-2)4f. The shakeup induced interband transitions from the Ag(100) surface are also identified by comparing the coincidence spectrum with the M4,5VV Auger transitions.

Energy relations of positron-electron pairs emitted from surfaces

The impact of a primary positron onto a surface may lead to the emission of a correlated positron-electron pair. By means of a lab-based positron beam we studied this pair emission from various surfaces. We analyzed the energy spectra in a symmetric emission geometry. We found that the available energy is shared in an unequal manner among the partners. On average the positron carries a larger fraction of the available energy. The unequal energy sharing is a consequence of positron and electron being distinguishable particles. We provide a model which explains the experimental findings.

Role of cathepsin B in regulating migration and invasion of fibroblast-like synoviocytes into inflamed tissue from patients with rheumatoid arthritis

Cathepsin B (CB), an important proteinase that participates in joint destruction in rheumatoid arthritis (RA), exhibits higher expression in fibroblast-like synoviocyte (FLS) of abnormal proliferative synovial tissues. Whether and how it affects the biological behaviours of RA-FLS, such as migration and invasion, are poorly understood. In the present study, CB expression in synovial tissues of patients with RA and ostearthritis (OA) were measured by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC), respectively. Stable depletion of endogenous CB was achieved by small interfering RNA (siRNA) transfection, and decrease of CB activity was acquired by using its specific inhibitor (CA074Me). The effects of CA074Me and RNA interference (RNAi) treatments on proliferation, migration, invasion, matrix metalloproteinase (MMP)-2/-9 expression, focal adhesion kinase (FAK) activation, and mitogen-activated protein kinases (MAPKs) phosphorylation of FLS were analysed. In RA synovial tissues, CB was expressed at elevated levels compared with OA synovial tissues. CA074Me could inhibit invasion of FLS obtained from RA patients in an ex-vivo invasion model. CA074Me and siRNA treatments suppressed the migration and invasion of FLS, reduced the activity, expression and mRNA level of MMP-2, restrained the activation of FAK and reduced the expression of F-actin. Moreover, CA074Me decreased the phosphorylation of P38 MAPK and c-Jun N-terminal kinase (JNK) in FLS, while siCB treatment reduced the phosphorylation of P38 but not JNK. CB substantially contributes to the invasive phenotype of FLS that leads to joint destruction in RA. This proteinase may show promise as a therapeutic target in inflammatory arthritis.

Nuclear factor erythroid 2-related factor 2 rescues the oxidative stress induced by di-N-butylphthalate in testicular Leydig cells

Aim:

This study aimed to determine whether nuclear factor erythroid 2-related factor 2 antagonized the oxidative stress induced by di- N-butylphthalate (DBP) in testicular Leydig cells.

Methods:

Mouse TM3 testicular Leydig cells were treated with Nrf2 knockdown (KD) or overexpression in the presence and absence of DBP. Oxidative profiles were examined. Nrf2 target antioxidant genes were studied, and the effects of Nrf2 inducer sulphoraphane (SFN) were tested.

Results:

DBP induced intracellular oxidative stress to a similar extent with Nrf2 KD. Expression and protein levels of Nrf2 were increased together with its target genes, namely heme oxygenase 1, nicotinamide adenine dinucleotide phosphate quinone oxidoreductase 1 and peroxiredoxin 6, following DBP stimulation. Use of SFN not only restored the intracellular oxidative toxicity but also cell proliferation and testosterone secretion in response to DBP.

Conclusion:

Increased Nrf2 activity, for example, by SFN can effectively antagonize the oxidative stress in testicular Leydig cells caused by DBP.

Default network connectivity as a vulnerability marker for obsessive compulsive disorder

BACKGROUND

Aberrant functional connectivity within the default network is generally assumed to be involved in the pathophysiology of obsessive compulsive disorder (OCD); however, the genetic risk of default network connectivity in OCD remains largely unknown.

METHOD

Here, we systematically investigated default network connectivity in 15 OCD patients, 15 paired unaffected siblings and 28 healthy controls. We sought to examine the profiles of default network connectivity in OCD patients and their siblings, exploring the correlation between abnormal default network connectivity and genetic risk for this population.

RESULTS

Compared with healthy controls, OCD patients exhibited reduced strength of default network functional connectivity with the posterior cingulate cortex (PCC), and increased functional connectivity in the right inferior frontal lobe, insula, superior parietal cortex and superior temporal cortex, while their unaffected first-degree siblings only showed reduced local connectivity in the PCC.

CONCLUSIONS

These findings suggest that the disruptions of default network functional connectivity might be associated with family history of OCD. The decreased default network connectivity in both OCD patients and their unaffected siblings may serve as a potential marker of OCD.