Unidirectional Real-Time Photoswitching of Diarylethene Molecular Monolayer Junctions with Multilayer Graphene Electrodes.

We fabricate and characterize vertical molecular junctions consisting of self-assembled monolayers of diarylethene (DAE) contacted by a multilayer graphene (MLG) electrode on the top and gold on the bottom. The DAE molecular junctions show two stable electrical states, a closed state (high conductance) or an open state (low conductance), which are created upon illumination with UV or visible light, respectively. For the Au-DAE-MLG junction structure, we observe that the current levels between the two conductance states are separated by 2 orders of magnitude. However, in a real-time measurement, we observe only unidirectional switching behavior from the open to the closed state.

High-Yield Functional Molecular Electronic Devices.

An ultimate goal of molecular electronics, which seeks to incorporate molecular components into electronic circuit units, is to generate functional molecular electronic devices using individual or ensemble molecules to fulfill the increasing technical demands of the miniaturization of traditional silicon-based electronics. This review article presents a summary of recent efforts to pursue this ultimate aim, covering the development of reliable device platforms for high-yield ensemble molecular junctions and their utilization in functional molecular electronic devices, in which distinctive electronic functionalities are observed due to the functional molecules. In addition, other aspects pertaining to the practical application of molecular devices such as manufacturing compatibility with existing complementary metal-oxide-semiconductor technology, their integration, and flexible device applications are also discussed. These advances may contribute to a deeper understanding of charge transport characteristics through functional molecular junctions and provide a desirable roadmap for future practical molecular electronics applications.

Gate-dependent asymmetric transport characteristics in pentacene barristors with graphene electrodes.

We investigated the electrical characteristics and the charge transport mechanism of pentacene vertical hetero-structures with graphene electrodes. The devices are composed of vertical stacks of silicon, silicon dioxide, graphene, pentacene, and gold. These vertical heterojunctions exhibited distinct transport characteristics depending on the applied bias direction, which originates from different electrode contacts (graphene and gold contacts) to the pentacene layer. These asymmetric contacts cause a current rectification and current modulation induced by the gate field-dependent bias direction. We observed a change in the charge injection barrier during variable-temperature current-voltage characterization, and we also observed that two distinct charge transport channels (thermionic emission and Poole-Frenkel effect) worked in the junctions, which was dependent on the bias magnitude.

Electrical characterization of benzenedithiolate molecular electronic devices with graphene electrodes on rigid and flexible substrates.

We investigated the electrical characteristics of molecular electronic devices consisting of benzenedithiolate self-assembled monolayers and a graphene electrode. We used the multilayer graphene electrode as a protective interlayer to prevent filamentary path formation during the evaporation of the top electrode in the vertical metal-molecule-metal junction structure. The devices were fabricated both on a rigid SiO2/Si substrate and on a flexible poly(ethylene terephthalate) substrate. Using these devices, we investigated the basic charge transport characteristics of benzenedithiolate molecular junctions in length- and temperature-dependent analyses. Additionally, the reliability of the electrical characteristics of the flexible benzenedithiolate molecular devices was investigated under various mechanical bending conditions, such as different bending radii, repeated bending cycles, and a retention test under bending. We also observed the inelastic electron tunneling spectra of our fabricated graphene-electrode molecular devices. Based on the results, we verified that benzenedithiolate molecules participate in charge transport, serving as an active tunneling barrier in solid-state graphene-electrode molecular junctions.

Statistical investigation of the length-dependent deviations in the electrical characteristics of molecular electronic junctions fabricated using the direct metal transfer method.

We fabricated and analyzed the electrical transport characteristics of vertical type alkanethiolate molecular junctions using the high-yield fabrication method that we previously reported. The electrical characteristics of the molecular electronic junctions were statistically collected and investigated in terms of current density and transport parameters based on the Simmons tunneling model, and we determined representative current-voltage characteristics of the molecular junctions. In particular, we examined the statistical variations in the length-dependent electrical characteristics, especially the Gaussian standard deviation σ of the current density histogram. From the results, we found that the magnitude of the σ value can be dependent on the individual molecular length due to specific microscopic structures in the molecular junctions. The probable origin of the molecular length-dependent deviation of the electrical characteristics is discussed.

A New Triggering Receptor Expressed on Myeloid Cells (TREM) Family Member, TLT-6, is Involved in Activation and Proliferation of Macrophages.

The triggering receptor expressed on myeloid cells (TREM) family, which is abundantly expressed in myeloid lineage cells, plays a pivotal role in innate and adaptive immune response. In this study, we aimed to identify a novel receptor expressed on hematopoietic stem cells (HSCs) by using in silico bioinformatics and to characterize the identified receptor. We thus found the TREM-like transcript (TLT)-6, a new member of TREM family. TLT-6 has a single immunoglobulin domain in the extracellular region and a long cytoplasmic region containing 2 immunoreceptor tyrosine-based inhibitory motif-like domains. TLT-6 transcript was expressed in HSCs, monocytes and macrophages. TLT-6 protein was up-regulated on the surface of bone marrow-derived and peritoneal macrophages by lipopolysaccharide stimulation. TLT-6 exerted anti-proliferative effects in macrophages. Our results demonstrate that TLT-6 may regulate the activation and proliferation of macrophages.

Effect of feeding fermented rice punch on oestrous induction in anoestrous bitches.

INTRODUCTION: As a consequence of poor productivity caused by a long anoestrous period, considerable research effort has been given to oestrus induction in dogs to enhance the productivity of young dogs and to preserve breeds. MATERIALS AND METHODS: Oestrus was induced in 30 anoestrous bitches more than three months after the last oestrus. Bitches orally received fermented rice punch with or without bromocriptine once daily for 21 consecutive days. The bitches were divided into two groups (n=10 per group): Group (1) fed fermented rice punch and Group (2) administered bromocriptine (100 µg/kg/day) and fed fermented rice punch. RESULTS: The concentration of dopamine in fermented rice punch was 47.2 mg/kg (parts per million). Six of 10 (60.0 per cent) and seven of 10 (70.0 per cent) bitches showed pro-oestrual bleeding in Groups 1 and 2, respectively. The mean and median values (min-max) to oestrus induction was not significantly different between Groups 1 and 2 (9.7±7.3, 6.5 (3-22) and 11.3±6.6, 7.9 (5-21) days) after treatment commencement (P>0.05). The pregnancy rate was very similar between Groups 1, 2 (66.0%) and control (66.0, 57.0 and 50.0 per cent). The mean and median values (min-max) of pups per bitch are also not significantly different between Groups 1, 2 and control (7.0±1.8, 7.0 (5-9) and 7.5±2.1, 7.5 (5-10) and 7.0±0, 7.0 (7-7)). CONCLUSION: We suggest that rice punch effectively induces oestrus in bitches.

A new approach for high-yield metal-molecule-metal junctions by direct metal transfer method.

The realization of high-yield, stable molecular junctions has been a long-standing challenge in the field of molecular electronics research, and it is an essential prerequisite for characterizing and understanding the charge transport properties of molecular junctions prior to their device applications. Here, we introduce a new approach for obtaining high-yield, vertically structured metal-molecule-metal junctions in which the top metal electrodes are formed on alkanethiolate self-assembled monolayers by a direct metal transfer method without the use of any additional protecting interlayers in the junctions. The fabricated alkanethiolate molecular devices exhibited considerably improved device yields (∼70%) in comparison to the typical low device yields (less than a few %) of molecular junctions in which the top metal electrodes are fabricated using the conventional evaporation method. We compared our method with other molecular device fabrication methods in terms of charge transport parameters. This study suggests a potential new device platform for realizing robust, high-yield molecular junctions and investigating the electronic properties of devices.

Gate-bias stress-dependent photoconductive characteristics of multi-layer MoS2 field-effect transistors.

We investigated the photoconductive characteristics of molybdenum disulfide (MoS2) field-effect transistors (FETs) that were fabricated with mechanically exfoliated multi-layer MoS2 flakes. Upon exposure to UV light, we observed an increase in the MoS2 FET current because of electron-hole pair generation. The MoS2 FET current decayed after the UV light was turned off. The current decay processes were fitted using exponential functions with different decay characteristics. Specifically, a fast decay was used at the early stages immediately after turning off the light to account for the exciton relaxation, and a slow decay was used at later stages long after turning off the light due to charge trapping at the oxygen-related defect sites on the MoS2 surface. This photocurrent decay phenomenon of the MoS2 FET was influenced by the measurement environment (i.e., vacuum or oxygen environment) and the electrical gate-bias stress conditions (positive or negative gate biases). The results of this study will enhance the understanding of the influence of environmental and measurement conditions on the optical and electrical properties of MoS2 FETs.

Three-terminal single-molecule junctions formed by mechanically controllable break junctions with side gating.

Molecules are promising candidates for electronic device components because of their small size, chemical tunability, and ability to self-assemble. A major challenge when building molecule-based electronic devices is forming reliable molecular junctions and controlling the electrical current through the junctions. Here, we report a three-terminal junction that combines both the ability to form a stable single-molecule junction via the mechanically controllable break junction (MCBJ) technique and the ability to shift the energy levels of the molecule by gating. Using a noncontact side-gate electrode located a few nanometers away from the molecular junction, the conductance of the molecule could be dramatically modulated because the electrical field applied to the molecular junction from the side gate changed the molecular electronic structure, as confirmed by the ab initio calculations. Our study will provide a new design for mechanically stable single-molecule transistor junctions fabricated by the MCBJ method.

Monoclonal antibody against α-actinin 4 from human umbilical vein endothelial cells inhibits endothelium-dependent vasorelaxation.

BACKGROUND: This study was attempted to identify new molecules expressed on the plasma membrane of human umbilical vein endothelial cells (HUVECs) using monoclonal antibody-based proteomics technology and to determine the effect of the identified antibody on vascular reactivity. METHODS: Twenty-two antibodies were developed from rats inoculated with HUVECs, and their effects were determined by observing vascular reactivity. RESULTS: Among the 22 antibodies, the C-7 antibody significantly inhibited endothelium-dependent vasorelaxation in response to acetylcholine (ACh) but not to histamine. Moreover, the C-7 antibody did not affect norepinephrine-induced contraction in either the endothelium-intact or -denuded aorta. A proteomics study involving immunoprecipitation of the C-7 antibody with biotinylated HUVECs showed that this antibody binds to plasma membrane proteins corresponding to immunoglobulin heavy chain (VHDJ region), chaperonin-containing T-complex polypeptide 1 and α-actinin 4. The muscarinic M3 ACh receptor and α-actinin 4 were colocalized on the plasma membrane of HUVECs, and the colocalization was found to increase in response to ACh and was inhibited by pretreatment with the C-7 antibody. CONCLUSIONS: These results demonstrate that monoclonal C-7 antibody exerts an inhibitory effect on endothelium-dependent vasorelaxation induced by ACh and that this response may at least partially result from the inhibition of α-actinin 4.

Mesenchymal stem cells regulate the proliferation of T cells via the growth-related oncogene/CXC chemokine receptor, CXCR2.

Mesenchymal stem cells (MSCs) have known to induce immunosuppressive properties by preventing T cell proliferation. However, it is remains unclear how MSCs inhibit T cell proliferation. To identify the factor that inhibits T cell proliferation, we conducted a cytokine array analysis of culture medium from a co-culture of MSCs and T cells and found that the chemokines, CXCL1, 2 and 3, were induced in T cells. MSCs also induced the expression of the CXCR2 receptor on T cell surface. Particularly, CXCL3 inhibited proliferation and increased apoptosis in T cells, which were reversed by CXCR2 inhibitor treatment. Moreover, CXCL3 decreased JAK2, STAT3, and AKT phosphorylation and these responses were also abolished by CXCR2 inhibitor treatment. MSCs suppressed the proliferation of T cells into tumor tissue. Collectively, these data demonstrate that MSCs directly regulate T cell proliferation by induction of CXCL3 chemokine and its receptor, CXCR2 on the surface in T cells.

Increased HoxB4 Inhibits Apoptotic Cell Death in Pro-B Cells.

HoxB4, a homeodomain-containing transcription factor, is involved in the expansion of hematopoietic stem cells and progenitor cells in vivo and in vitro, and plays a key role in regulating the balance between hematopoietic stem cell renewal and cell differentiation. However, the biological activity of HoxB4 in other cells has not been reported. In this study, we investigated the effect of overexpressed HoxB4 on cell survival under various conditions that induce death, using the Ba/F3 cell line. Analysis of phenotypical characteristics showed that HoxB4 overexpression in Ba/F3 cells reduced cell size, death, and proliferation rate. Moreover, the progression from early to late apoptotic stages was inhibited in Ba/F3 cells subjected to HoxB4 overexpression under removal of interleukin-3-mediated signal, leading to the induction of cell cycle arrest at the G2/M phase and attenuated cell death by Fas protein stimulation in vitro. Furthermore, apoptotic cell death induced by doxorubicin-treated G2/M phase cell-cycle arrest also decreased with HoxB4 overexpression in Ba/F3 cells. From these data, we suggest that HoxB4 may play an important role in the regulation of pro-B cell survival under various apoptotic death environments.

Alpha 1,3-galactosyltransferase deficiency in pigs increases sialyltransferase activities that potentially raise non-gal xenoantigenicity.

We examined whether deficiency of the GGTA1 gene in pigs altered the expression of several glycosyltransferase genes. Real-time RT-PCR and glycosyltransferase activity showed that 2 sialyltransferases [α2,3-sialyltransferase (α2,3ST) and α2,6-sialyltransferase (α2,6ST)] in the heterozygote GalT KO liver have higher expression levels and activities compared to controls. Enzyme-linked lectin assays indicated that there were also more sialic acid-containing glycoconjugate epitopes in GalT KO livers than in controls. The elevated level of sialic-acid-containing glycoconjugate epitopes was due to the low level of α-Gal in heterozygote GalT KO livers. Furthermore, proteomics analysis showed that heterozygote GalT KO pigs had a higher expression of NAD+-isocitrate dehydrogenase (IDH), which is related to the CMP-N-acetylneuraminic acid hydroxylase (CMAH) enzyme reaction. These findings suggest the deficiency of GGTA1 gene in pigs results in increased production of N-glycolylneuraminic acid (Neu5Gc) due to an increase of α2,6-sialyltransferase and a CMAH cofactor, NAD+-IDH. This indicates that Neu5Gc may be a critical xenoantigen. The deletion of the CMAH gene in the GalT KO background is expected to further prolong xenograft survival.

T lymphocytes derived from human cord blood provide effective antitumor immunotherapy against a human tumor.

BACKGROUND: Although the graft-versus-tumor (GVT) effect of donor-derived T cells after allogeneic hematopoietic stem cell transplantation has been used as an effective adoptive immunotherapy, the antitumor effects of cord blood (CB) transplantation have not been well studied. METHODS: We established the animal model by transplantation of CB mononuclear cells and/or tumor cells into NOD/SCID mice. The presence of CB derived T cells in NOD/SCID mice or tumor tissues were determined by flow cytometric and immunohistochemical analysis. The anti-tumor effects of CB derived T cells against tumor was determined by tumor size and weight, and by the cytotoxicity assay and ELISPOT assay of T cells. RESULTS: We found dramatic tumor remission following transfer of CB mononuclear cells into NOD/SCID mice with human cervical tumors with a high infiltration of CD3+ T cells in tumors. NOD/SCID mice that receive neonatal CB transplants have reconstituted T cells with significant antitumor effects against human cervical and lung tumors, with a high infiltration of CD3+ T cells showing dramatic induction of apoptotic cell death. We also confirmed that T cells showed tumor specific antigen cytotoxicity in vitro. In adoptive transfer of CD3+ T cells into mice with pre-established tumors, we observed much higher antitumor effects of HPV-specific T cells by ELISPOT assays. CONCLUSIONS: Our results show that CB derived T lymphocytes will be useful for novel immunotherapeutic candidate cells for therapy of several tumors in clinic.

Doxorubicin exerts cytotoxic effects through cell cycle arrest and Fas-mediated cell death.

Doxorubicin (DOX) is involved in the induction of DNA damage, inhibition of cell proliferation, impairment of mitochondria, and cell death. To determine the biological effects of DOX in murine lymphocytes, we analyzed cell proliferation, cell cycle status, and apoptosis in Ba/F3 and EL4 lymphoid cells. DOX treatment resulted in significant cellular morphological alteration with increased intracellular granularity and cell size. DOX inhibited cell proliferation through cell cycle arrest at the G(2)/M phase as well as by cell death. In addition, DOX treatment dramatically upregulated Fas expression and enhanced caspase activation to promote intracellular apoptotic signaling for cell death. Treatment with an agonistic antibody stimulated Fas and accelerated the cell death effects. In conclusion, we demonstrate that DOX induces cell cycle arrest and apoptosis by increased Fas expression and ultimately results in enhanced cell death.

CD137 ligand-mediated reverse signals increase cell viability and cytokine expression in murine myeloid cells: involvement of mTOR/p70S6 kinase and Akt.

Cross-linking of CD137 ligand (CD137L), a member of the TNF family, with recombinant CD137-Fc (rCD137-Fc) protein enhanced adherence of bone marrow-derived macrophages, and increased the expression of ICAM-1, IL-1beta, IL-6, M-CSF and phosphotyrosine proteins. In RAW264.7 cells, a murine myeloid cell line, rCD137-Fc not only increased adherence but also cell multiplication, in a manner comparable to LPS or M-CSF. In addition, it up-regulated expression of IL-1beta, IL-1 receptor antagonist, IL-6, COX2, tenascin C, neuropeptide Y and M-CSF mRNA. Neutralization of M-CSF by incubating the RAW264.7 cells with anti-M-CSF mAb did not prevent the CD137L signal-induced viability. Viability was blocked by PP2, an Src tyrosine kinase inhibitor, rapamycin, an mTOR inhibitor and LY294002, a PI3K inhibitor, but not by Wortmannin, another PI3K inhibitor. Cross-linking of CD137L increased phosphorylation of Akt and p70S6 kinase. The latter was blocked by PP2, rapamycin or LY294002, but not by Wortmannin, whereas phosphorylation of Akt was blocked by LY294002 or Wortmannin. These findings demonstrate that reverse signals evoked by CD137L regulate immune functions in macrophages.

Implication of human OCT4 transactivation domains for self-regulatory transcription.

OCT4 plays a crucial role in pluripotency and self-renewal of embryonic stem cells. OCT4 is also expressed in testicular germ cell tumors (GCTs), suggesting the important function of OCT4 as an oncogenic factor in GCTs. To understand the molecular mechanism of human OCT4 (hOCT4) in tumorigenesis as well as stemness, we identified hOCT4 transactivation domains in human embryonic carcinoma cells. Context analyses of heterologous GAL4 and natural hOCT4 revealed that each N-terminal domain or C-terminal domain independently stimulated transcriptional activity, and that both domains are required for synergistic transactivation by deletion mapping analysis. Dose-dependent overexpression of exogenous hOCT4 significantly decreased the transcriptional activity of the hOCT4 promoter. This inhibition was reversed by the removal of one or both domains. These results suggest that the inhibitory effect of hOCT4 is mediated by transactivation domains, and that the self-regulation of hOCT4 may be mediated via a negative feedback loop in pluripotent cells.