Wafer-Scale Epitaxial Growth of an Atomically Thin Single-Crystal Insulator as a Substrate of Two-Dimensional Material Field-Effect Transistors.

As the electron mobility of two-dimensional (2D) materials is dependent on an insulating substrate, the nonuniform surface charge and morphology of silicon dioxide (SiO2) layers degrade the electron mobility of 2D materials. Here, we demonstrate that an atomically thin single-crystal insulating layer of silicon oxynitride (SiON) can be grown epitaxially on a SiC wafer at a wafer scale and find that the electron mobility of graphene field-effect transistors on the SiON layer is 1.5 times higher than that of graphene field-effect transistors on typical SiO2 films. Microscale and nanoscale void defects caused by heterostructure growth were eliminated for the wafer-scale growth of the single-crystal SiON layer. The single-crystal SiON layer can be grown on a SiC wafer with a single thermal process. This simple fabrication process, compatible with commercial semiconductor fabrication processes, makes the layer an excellent replacement for the SiO2/Si wafer.

Dual-specificity phosphatase 18 modulates the SUMOylation and aggregation of Ataxin-1.

We previously reported that SUMOylation promotes the aggregation of ataxin-1 and JNK is involved in the process. Here we show that dual-specificity phosphatase 18 (DUSP18), a member of protein tyrosine phosphatases, exerts the opposite effects on ataxin-1. DUSP18 associated with ataxin-1 and suppressed JNK activated by ataxin-1. Interestingly DUSP18, but not the other DUSPs interacting with ataxin-1, caused the mobility shift of ataxin-1. De-phosphorylation by DUSP18 was initially suspected as a cause for such an effect; however, the phosphorylation of ataxin-1 was unchanged. Instead DUSP18 inhibited SUMOylation and reduced ataxin-1 aggregation. The catalytic mutant of DUSP18 failed to reduce the SUMOylation and aggregation of ataxin-1 indicating that the phosphatase activity is indispensable for the effects. Moreover, DUSP18 disrupted the co-localization of ataxin-1 with the PML component Sp100. These results together implicate that JNK and DUSP18 reciprocally modulate the SUMOylation, which plays a regulatory role in the aggregation of ataxin-1.

Development of Nanofiber Reinforced Double Layered Cabin Air Filter Using Novel Upward Mass Production Electrospinning Set Up.

Recently, numerous researchers are interested in the development of new air filter because of air pollution caused by rapid industrialization and urbanization. The major concerns in developing air filters are: pressure drop and filtration efficiency which are considered significant. As the pressure drop increases, the energy consumption becomes high. In this study, we developed a novel air filter (polyurethane fiber mat) for nano size filtration using a mass production electrospinning, which is expected to enhance filtration efficiency and pressure drop effects. To determine the optimal electrospinning conditions for filter efficiency, various concentrations (8, 10, 12 wt/wt%) of thermoplastic polyurethane were prepared and employed. Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) were used for fiber characterization, and finally, efficiency test was conducted to evaluate the filter performance of developed nanofiber-based air filter. From this study, it could be concluded that optimization by adjusting the polymer concentration and electrospinning operating condition was the best efficient alternative method to fabricate nano-fibrous air filter system with improved filtration performance.

Gamma-knife subcaudate tractotomy for treatment-resistant depression and target characteristics: a case report and review.

Stereotactic subcaudate tractotomy has previously been suggested to be an effective treatment for depression. This is the first study to report the use of gamma-knife subcaudate tractotomy for treatment-resistant depression. A 49-year-old woman with major depressive disorder had been treated for 30 years, with nine suicide attempts during that time. The right and left target maximum diameter was 11 mm within 50 % isodose lines. The target was located more posteriorly and inferiorly than the subgenual cingulate target typically used for deep-brain stimulation. The maximum radiation dose was 130 Gy. During the 4 months after surgery, the patient improved gradually from 23 to 4 according to the Hamilton Rating Scale for Depression and antidepressant medication was discontinued. Target-sized focal lesions were identified and no edema was seen postoperatively. No aggravation or neurologic deficit occurred during the 2.5 years of follow-up. Gamma-knife subcaudate tractotomy for depression is a minimally invasive technique. Investigations of the effectiveness and safety profile in a larger group are warranted.

The requirements of yeast Hsp70 of SSA family for the ubiquitin-dependent degradation of short-lived and abnormal proteins.

Cytoplasmic Hsp70s of SSA family, especially Ssa1p, are involved in the degradation of a variety of misfolded proteins in yeast. However the importance of other Ssa proteins in this process is unclear. To clarify the role(s) of individual Ssa proteins in proteolysis, we measured the breakdown of various cell proteins in mutants lacking different Ssa proteins. In mutants lacking Ssa1p and Ssa2p, the proteasomal degradation of short-lived proteins was reduced, which was not restored fully by the over-expression of Ssa1p. By contrast, the degradation of stable cellular proteins did not require Ssa proteins. The degradation of the cytosolic model substrates (Ub-P-ß-gal and R-ß-gal) and their ubiquitylation were inhibited by the inactivation of Ssa proteins. In addition, Ssa1p and the co-chaperone Ydj1p are indispensable for the intracellular degradation of a mutant secretory protein, Siiyama variant of human antitrypsin. Our findings indicate that both Ssa1p and Ssa2p are essential for the ubiquitin-dependent degradation of short-lived proteins and the requirements of Ssa proteins and the co-chaperones widely vary depending on the conformations and folding status of the substrates.

cIAPs promote the proteasomal degradation of mutant SOD1 linked to familial amyotrophic lateral sclerosis.

Although the ubiquitin-proteasome system is believed to play an important role in the pathogenesis of familial amyotrophic lateral sclerosis (FALS), caused by mutations in Cu/Zn-superoxide dismutase 1 (SOD1), the mechanism of how mutant SOD1 protein is regulated in cells is still poorly understood. Here we have demonstrated that cellular inhibitor of apoptosis proteins (cIAPs) are specifically associated with FALS-linked mutant SOD1 (mSOD1) and that this interaction promotes the ubiquitin-dependent proteasomal degradation of mutant SOD1. By utilizing cumate inducible SOD1 cells, we also showed that knock-down or pharmacologic depletion of cIAPs leads to H2O2 induced cytotoxicity in mSOD1 expressing cells. Altogether, our results reveal a novel role of cIAPs in FALS-associated mutant SOD1 regulation.

Induction of rat liver tumor using the Sleeping Beauty transposon and electroporation.

The Sleeping Beauty (SB) transposon system has been receiving much attention as a gene transfer method of choice since it allows permanent gene expression after insertion into the host chromosome. However, low transposition frequency in higher eukaryotes limits its use in commonly-used mammalian species. Researchers have therefore attempted to modify gene delivery and expression to overcome this limitation. In mouse liver, tumor induction using SB introduced by the hydrodynamic method has been successfully accomplished. Liver tumor in rat models using SB could also be of great use; however, dose of DNA, injection volume, rate of injection and achieving back pressure limit the use of the hydrodynamics-based gene delivery. In the present study, we combined the electroporation, a relatively simple and easy gene delivery method, with the SB transposon system and as a result successfully induced tumor in rat liver by directly injecting the c-Myc, HRAS and shp53 genes. The tumor phenotype was determined as a sarcomatoid carcinoma. To our knowledge, this is the first demonstration of induction of tumor in the rat liver using the electroporation-enhanced SB transposon system.

Dimerization of pro-oncogenic protein Anterior Gradient 2 is required for the interaction with BiP/GRP78.

Anterior Gradient 2 (AGR2), an ER stress-inducible protein, has been reported to be localized in endoplasmic reticulum (ER) and its level is elevated in numerous metastatic cancers. Recently, it has been demonstrated that AGR2 is involved in the control of ER homeostasis. However, the molecular mechanism how AGR2 regulates ER stress response remains unclear. Herein we show that AGR2 homo-dimerizes through an intermolecular disulfide bond. Moreover, dimerization of AGR2 attenuates ER stress-induced cell death through the association with BiP/GRP78. Thus, these results suggest that dimerization of AGR2 is crucial in mediating the ER stress signaling pathway.

Comparison of the effects of sublethal concentrations of biofoulants, copper pyrithione and zinc pyrithione on a marine mysid - A multigenerational study.

To determine the effect of copper pyrithione (CuPT) and zinc pyrithione (ZnPT), a set of acute (96 h-LC50) and chronic endpoints was studied in the marine mysid, Neomysis awatschensis. Based on the 1/10 NOECs and NOEC values calculated from 96 h-toxicity test, survival and growth, intermolt duration, feeding, and the number of newborn juveniles were measured by evaluating enzymatic activity of detoxification parameter glutathione S-transferase (GST) and cholinergic biomarker acetylcholinesterase (AChE) in the marine mysid exposed to 96 h-NOECs of CuPT and ZnPT for four weeks across three generations. Dose-dependent decreases in survival rate monitored for four weeks were observed with age-specific sensitivity in response to the 96 h-NOECs of both antifoulants. Higher growth retardation was observed with an increase in intermolt duration and inhibition of the feeding rate in CuPT-exposed mysid compared to ZnPT-exposed mysid across generations. The numbers of newborn juveniles significantly decreased at the third generation by exposure to the 96 h-NOECs of both antifoulants. GST activity was significantly inhibited in response to 96 h-NOECs of both antifoulants, whereas AChE activity was only reduced by the 96 h-NOECs of CuPT at the third generation. These results indicate that CuPT has a higher toxicity than ZnPT and even sublethal levels of CuPT and ZnPT would have detrimental effects on the maintenance of the mysid population. Finally, consistent exposure to environmentally relevant concentrations of CuPT and ZnPT can induce intergenerational toxicity in mysid.

Confirmation of Frm2 as a novel nitroreductase in Saccharomyces cerevisiae.

Nitroreductases comprise a group of FMN- or FAD-dependent enzymes that reduce nitrosubstituted compounds by using NAD(P)H, and are found in bacterial species and yeast. Although there is little information on the biological functions of nitroreductases, some studies suggest their possible involvement in oxidative stress responses. In the yeast Saccharomyces cerevisiae, a putative nitroreductase protein, Frm2, has been identified based on its sequence similarity with known bacterial nitroreductases. Frm2 has been reported to function in the lipid signaling pathway. To study the functions of Frm2, we measured the nitroreductase activity of purified Frm2 on 4-nitroquinoline-N-oxide (4-NQO) using NADH. LC-MS analysis of the reaction products revealed that Frm2 reduced NQO into 4-aminoquinoline-N-oxide (4-AQO) via 4-hydroxyaminoquinoline (4-HAQO). An Frm2 deletion mutant exhibited growth inhibition in the presence of 4-NQO. Thus, in this study, we demonstrate a novel nitroreductase activity of Frm2 and its involvement in the oxidative stress defense system.

Change in Bone Mineral Density in Stroke Patients with Osteoporosis or Osteopenia.

We aimed to investigate the correlation between changes in bone mineral density (BMD) of the lumbar spine (LS) and femoral neck (FN) and osteoporosis-related factors in stroke patients with osteoporosis or osteopenia, and we suggest the need for active rehabilitation treatment. This study included 63 osteoporosis and 34 osteopenia patients who underwent a BMD test following primary stroke onset. The osteoporosis group was followed up with a BMD test after 12 months of bisphosphonate treatment, and the osteopenia group was followed up without medication. The correlation between BMD changes and functional factors was analyzed, biochemical markers were measured, and hematology tests were performed. In the osteoporosis group, a significant increase was observed in LS BMD (p < 0.05), and in the osteopenia group, there was a significant decrease in FN BMD (p < 0.05). The group with a functional ambulatory category of 1 or more showed a significant improvement in BMD (p < 0.05). Comparative analysis was performed on various indicators, but no significant correlation was found between any variable. In stroke patients with osteoporosis or osteopenia, early appropriate drug treatment is important to prevent bone loss and reduce the risk of fractures, and comprehensive rehabilitation treatment, such as appropriate education and training to prevent falls, is essential.

Exposure to Environmentally Relevant Concentrations of Polystyrene Microplastics Increases Hexavalent Chromium Toxicity in Aquatic Animals.

The prevalence of hexavalent chromium [Cr(VI)] and microplastics (MPs) is ubiquitous and is considered a threat to aquatic biota. MPs can act as a vector for waterborne metals; however, the combined effects of Cr(VI) and MPs on aquatic organisms are largely unknown. In this study, aquatic model animals, such as rotifers (Brachionus calyciflorus and B. plicatilis), water fleas (Daphnia magna), amphipods (Hyalella azteca), polychaetes (Perinereis aibuhitensis), and zebrafish (Danio rerio) were exposed to environmental concentrations (1, 10, and 100 particles L-1) of 1 µm polystyrene MPs alone, Cr(VI) alone, or Cr(VI) combined with MPs. Following exposure, the potential effects were measured by analyzing basic life endpoints (e.g., survival rate and growth). A significant response to MPs alone was not observed in all animals. However, MPs combined with Cr(VI) concentration-dependently increased Cr(VI) toxicity in two rotifer species. The survival rate of water fleas was significantly reduced upon exposure to Cr(VI) + MPs (100 particles L-1) compared with exposure to Cr(VI) alone, and significantly decreased the number of offspring. Although there was no significant effect on the body length of the amphipod, concentration-dependent decreases in their survival rates were observed. In contrast, no significant change was found in the survival rate of polychaetes; however, their burrowing ability was inhibited by Cr(VI) + MPs (100 particles L-1). Further, larval mortality was increased in response to Cr(VI) + MPs (100 particles L-1) in zebrafish. Taken together, the findings suggest that MPs can exacerbate Cr(VI) toxicity, even at environmental levels.

Crustacean cardioactive peptide in the Chagas' disease vector, Rhodnius prolixus: presence, distribution and physiological effects.

Crustacean cardioactive peptide (CCAP), a cyclic nonapeptide (PFCNAFTGCamide), has multifunctional roles in insects including stimulating visceral and cardiac muscle contraction, and regulating ecdysis. Previously, we have sequenced the cDNA for CCAP from Rhodnius prolixus central nervous system (CNS) and shown expression of the CCAP transcript in neurons of the CNS. In the present study, we have biochemically identified and sequenced CCAP from 5th instar R. prolixus CNS using matrix-assisted laser desorption ionization-time of flight-tandem mass spectrometry, and mapped CCAP-like immunoreactivity in the CNS and peripheral tissues of 5th instar R. prolixus. Physiologically, the hindgut of R. prolixus was found to be sensitive to CCAP, showing dose-dependent increases in contractions with threshold at 5 × 10(-9) M and maximum response at 10(-7) M CCAP. Also, CCAP was found to increase the frequency of the heartbeat in a reversible, dose-dependent manner, with threshold close to 10(-11) M and maximum response at 10(-10) M CCAP.

Positive regulation of apoptosis signal-regulating kinase 1 by dual-specificity phosphatase 13A.

Apoptosis signal-regulating kinase 1 (ASK1), a member of the MAP kinase kinase kinase, is activated by several death stimuli and is tightly regulated by several mechanisms such as interactions with regulatory proteins and post-translational modifications. Here, we report that dual-specificity phosphatase 13A (DUSP13A) functions as a novel regulator of ASK1. DUSP13A interacts with the N-terminal domain of ASK1 and induces ASK1-mediated apoptosis through the activation of caspase-3. DUSP13A enhances ASK1 kinase activity and thus its downstream factors. Small interfering RNA (siRNA) analyses show that knock-down of DUSP13A in human neuroblastoma SK-N-SH cells reduces ASK1 kinase activity. The phosphatase activity of DUSP13A is not required for the regulation of ASK1. This regulatory action of DSUP13 on ASK1 activity involves competition with Akt1, a negative regulator of ASK1, for binding to ASK1. Taken together, this study provides novel insights into the role of DUSP13A in the precise regulation of ASK1.

Anterior gradient 2 is involved in the post-transcriptional regulation of ß-dystroglycan.

Anterior gradient 2 (AGR2) is a protein disulfide isomerase over-expressed in numerous types of cancer. Although AGR2 plays a role in ER homeostasis, its function(s) in tumorigenesis is still elusive. Here we demonstrate that AGR2 is involved in the regulation of the ß-subunit of dystroglycan (ß-DG), a component of the multi-protein complex linking the extracellular matrix and cytoskeletal network. In breast cancer cells, AGR2 over-expression led to the up-regulation of ß-DG but not that of α-DG, while the transcript levels of these subunits were unchanged. Conversely, the reduced expression of AGR2 caused the down-regulation of ß-DG. Interestingly, induced expression of AGR2 increased the degree of co-localization of AGR2 and ß-DG in the cytoplasm suggesting that AGR2 facilitates the trafficking of ß-DG. In addition, AGR2 over-expression caused the re-arrangement of the actin cytoskeletal network. Presumably over-expressed AGR2 up-regulates ß-DG post-transcriptionally and facilitates its trafficking, which then causes re-arrangement of the cytoskeletal network, which plays a role in the adhesion and invasion of cancer cells.

Consistent exposure to microplastics induces age-specific physiological and biochemical changes in a marine mysid.

In this study, a marine mysid, Neomysis awatschensis, was exposed to 1 × 103-5 × 105 particles mL-1 of polystyrene microbeads (1 and 10 µm). Exposure to microplastics (MPs) resulted in ingestion and egestion in feces. MPs exposure during the early stage resulted in mortality and oxidative stress, while more mature stages were increasingly tolerant to MPs. Feeding rates were inhibited by MPs, and age-specific oxidative stress was observed. Growth parameters were significantly affected by MPs with lower 20-hydroxyecdysone (20E) concentrations and longer intermolt durations. The number of hatched juveniles from females that were exposed to MPs was significantly lower than the control treatment, but no significant differences were observed between survival rates of newly hatched juveniles in the different treatments. Our results suggest that the detrimental effects of prolonged exposure to MPs could be age- and size-specific and harmful for the maintenance of mysid populations.

A solvent-free headspace GC/MS method for sensitive screening of N-nitrosodimethylamine in drug products.

A solvent-free headspace gas chromatography-mass spectrometry (SF-HS-GC/MS) method was developed and validated for screening N-nitrosodimethylamine (NDMA) in various active pharmaceutical ingredients (APIs) and drug products. Experimental parameters such as incubation temperature, incubation time, and sample volume in solvent-free headspace conditions were optimized. The developed SF-HS-GC/MS method was validated in terms of linearity, limit of quantification (LOQ), precision, and accuracy. The results indicated excellent linearity from 5 to 500 ng g-1 with correlation coefficients higher than 0.9999. The LOQ of this method was 5 ng g-1 and matrix effects ranged from 0.97 to 1.11. The accuracy ranged from 92.77 to 106.54% and the precision RSDs were below 5.94%. No significant matrix effect was observed for any of the drug products. Also, artefactual NDMA formation in ranitidine, nizatidine, and metformin was investigated under HS conditions. Adjusted (mild) SF-HS conditions were suggested for precise quantification of NDMA in positive drug products by GC/MS. The present SF-HS-GC/MS method is a promising tool for the screening and determination of toxic NDMA in APIs and drug products.

Synthesis of high quality 2D carbide MXene flakes using a highly purified MAX precursor for ink applications.

The practical application of 2D MXenes in electronic and energy fields has been hindered by the severe variation in the quality of MXene products depending on the parent MAX phases, manufacturing techniques, and preparation parameters. In particular, their synthesis has been impeded by the lack of studies reporting the synthesis of high-quality parent MAX phases. In addition, controllable and uniform deposition of 2D MXenes on various large-scale substrates is urgently required to use them practically. Herein, a method of pelletizing raw materials could synthesize a stoichiometric Ti3AlC2 MAX phase with high yield and processability, and fewer impurities. The Ti3AlC2 could be exfoliated into 1-2-atom-thick 2D Ti3C2T x flakes, and their applicability was confirmed by the deposition and additional alignment of the 2D flakes with tunable thickness and electrical properties. Moreover, a practical MXene ink was fabricated with rheological characterization. MXene ink exhibited much better thickness uniformity while retaining excellent electrical performances (e.g., sheet resistance, electromagnetic interference shielding ability) as those of a film produced by vacuum filtration. The direct functional integration of MXenes on various substrates is expected to initiate new and unexpected MXene-based applications.

Hsp104 is essential for the selective degradation in yeast of polyglutamine expanded ataxin-1 but not most misfolded proteins generally.

Molecular chaperones of the Hsp70/40 family protect against the accumulation of mutated or misfolded proteins in part by facilitating their degradation. In the polyglutamine (polyQ) diseases, mutant proteins containing expanded polyQ repeats accumulate in intracellular inclusions and cause neurodegeneration. Although the ubiquitin-proteasome system and chaperones all help protect against accumulation of such toxic proteins, their precise roles are still unclear. Here we observed that the polyQ-expanded mutant ataxin-1 [82Q] was rapidly and selectively degraded in yeast while the wild-type protein [30Q] was stable. The selective degradation of the mutant ataxin-1 required proteasomes, but did not require Ydj1p, an Hsp40 homolog, which is involved in the disaggregation and/or breakdown of a number of misfolded proteins. However, another chaperone Hsp104 promoted degradation of mutant ataxin-1 without influencing the solubility or breakdown of short-lived cell proteins generally. Thus Hsp104-dependent degradation of mutant ataxin-1 may account for the ability of this chaperone to reduce toxicity caused by polyQ-repeat proteins.

Oxidative stress-enhanced SUMOylation and aggregation of ataxin-1: Implication of JNK pathway.

Although the polyglutamine protein ataxin-1 is modified by SUMO at multiple sites, the functions of such modification or how it is regulated are still unknown. Here we report that SUMO-1 or Ubc9 over-expression stimulated the aggregation of ataxin-1 and that oxidative stress, such as hydrogen peroxide treatment, further enhanced SUMO conjugation and aggregation of ataxin-1. Accordingly, co-treatment with antioxidant N-acetyl-cysteine attenuated the effect of oxidative stress. Ataxin-1, which can activate c-Jun N-terminal kinase (JNK) pathway by itself, strongly associated with apoptosis signal-regulating kinase 1 (ASK1) while not interacting with JNK. Finally, treatment of JNK-specific inhibitor caused a reduction in the oxidant-enhanced SUMOylation and aggregation of ataxin-1. Together these results indicate that SUMO modification of ataxin-1 promotes the aggregation of ataxin-1 and that oxidative stress and JNK pathway play roles in this process.