Universal dependence of hydrogen oxidation and evolution reaction activity of platinum-group metals on pH and hydrogen binding energy

Understanding how pH affects the activity of hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER) is key to developing active, stable, and affordable HOR/HER catalysts for hydroxide exchange membrane fuel cells and electrolyzers. A common linear correlation between hydrogen binding energy (HBE) and pH is observed for four supported platinum-group metal catalysts (Pt/C, Ir/C, Pd/C, and Rh/C) over a broad pH range (0 to 13), suggesting that the pH dependence of HBE is metal-independent. A universal correlation between exchange current density and HBE is also observed on the four metals, indicating that they may share the same elementary steps and rate-determining steps and that the HBE is the dominant descriptor for HOR/HER activities. The onset potential of CO stripping on the four metals decreases with pH, indicating a stronger OH adsorption, which provides evidence against the promoting effect of adsorbed OH on HOR/HER.

Hydrogen Evolution and Oxidation: Mechanistic Studies and Material Advances

Electrochemical energy storage and conversion through hydrogen is essential for a clean and sustainable energy system. Highly efficient hydrogen electrocatalysts play a key role in the electrochemical transformation reactions. A comprehensive understanding of the hydrogen reaction kinetics and mechanisms is critical for the catalyst design and development. Especially pH-dependent hydrogen evolution and oxidation reaction (HER/HOR) kinetics receives increasing interest, and understanding its origin adds new knowledge to fundamental hydrogen electrocatalysis. Here, a detailed description of kinetic analysis and reaction mechanisms for HER/HOR, and a brief summary about recent development of highly efficient and cost-effective hydrogen electrocatalysts are presented. Lastly, recent advances in the fundamental understanding of pH-dependent hydrogen electrocatalysis are discussed.

Robust expression of TNF-alpha, IL-1beta, RANTES, and IP-10 by human microglial cells during nonproductive infection with herpes simplex virus

Cytokine (TNF-alpha/beta, IL-1beta, IL-6, IL-18, IL-10, and IFN-alpha/beta/gamma) and chemokine (IL-8, IP-10, MCP-1, MIP-1alpha/beta, and RANTES) production during herpes simplex virus (HSV) 1 infection of human brain cells was examined. Primary astrocytes as well as neurons were found to support HSV replication, but neither of these fully permissive cell types produced cytokines or chemokines in response to HSV. In contrast, microglia did not support extensive viral replication; however, ICP4 was detected by immunochemical staining, demonstrating these cells were infected. Late viral protein (nucleocapsid antigen) was detected in <10% of infected microglial cells. Microglia responded to nonpermissive viral infection by producing considerable amounts of TNF-alpha, IL-1beta, IP-10, and RANTES, together with smaller amounts of IL-6, IL-8, and MIP-1alpha as detected by RPA and ELISA. Surprisingly, no interferons (alpha, beta, or gamma) were detected in response to viral infection. Pretreatment of fully permissive astrocytes with TNF-alpha prior to infection with HSV was found to dramatically inhibit replication, resulting in a 14-fold reduction of viral titer. In contrast, pretreatment of astrocytes with IL-1beta had little effect on viral replication. When added to neuronal cultures, exogenous TNF-alpha or IL-1beta did not suppress subsequent HSV replication. Exogenously added IP-10 inhibited HSV replication in neurons (with a 32-fold reduction in viral titer), however, similar IP-10 treatment did not affect viral replication in astrocytes. These results suggest that IP-10 possesses direct antiviral activity in neurons and support a role for microglia in both antiviral defense of the brain as well as amplification of immune responses during neuroinflammation.

Extracellular matrix protein 1 promotes cell metastasis and glucose metabolism by inducing integrin β4/FAK/SOX2/HIF-1α signaling pathway in gastric cancer

Extracellular matrix protein 1 (ECM1) is related to strong invasiveness and poor prognosis in major malignancies, but the underlying mechanism remains unknown. Here we aimed to elucidate the function of ECM1 on cell metastasis and glucose metabolism in gastric cancer (GC). The level of ECM1 in sera and tissues of patient with GC were positively correlated with tumor invasion and recurrence. Genetic manipulation of ECM1 expression affected cell metastasis and glucose metabolism in GC cell lines. Enhanced ECM1 expression facilitated gene expression levels associated with epithelial-mesenchymal transition (EMT) and glucose metabolism. Interestingly, our results indicated that ECM1 directly interacted with integrin β4 (ITGB4) and activated ITGB4/focal adhesion kinase (FAK)/glycogen synthase kinase 3β signaling pathway, which further induced the expression of transcription factor SOX2. Aberrant expression of SOX2 altered gene expression of EMT factors and glucose metabolism enzymes. Furthermore, SOX2 enhanced hypoxia-inducible factor α (HIF-1α) promoter activity to regulate glucose metabolism. The micro-positron emission tomography/computed tomography imaging of xenograft model showed that ECM1 substantially increased ¹⁸F-fluorodeoxyglucose uptake in xenograft tumors. Using in vivo mouse tail vein injection experiments, ECM1 was also found to increase in lung surface metastasis. These findings provide evidence that ECM1 regulates GC cell metastasis and glucose metabolism by inducing ITGB4/FAK/SOX2/HIF-1α signal pathway and have important implications for the development of therapeutic target to prevent tumor metastasis and recurrence.

Incidence and mortality of nasopharyngeal carcinoma: interim analysis of a cluster randomized controlled screening trial (PRO-NPC-001) in southern China

BACKGROUND

Previous mass screening studies have shown that IgA antibodies against Epstein-Barr Virus (EBV) can facilitate early detection of nasopharyngeal carcinoma (NPC), but the impact of EBV-antibody screening for NPC-specific mortality remains unknown.

PATIENTS AND METHODS

A prospective, cluster randomized, controlled trial for NPC screening (PRO-NPC-001) was conducted in 3 selected towns of Zhongshan City and 13 selected towns of Sihui City in southern China beginning in 2008. Serum samples of the screening group were tested for two previously selected anti-EBV antibodies. Subjects with serological medium risk were subsequently retested annually for 3 years, and those with serological high risk were referred to otorhinolaryngologists for diagnostic check-up. An interim analysis was carried out to evaluate the primary end points of the NPC-specific mortality and the early diagnostic rate, and the secondary end point of the NPC incidence, through linkage with the database of Zhongshan City.

RESULTS

Among 70 296 total subjects, 29 413 screened participants (41.8% of the total subjects) in the screening group and 50 636 in the control group, 153 (43.3 per 100 000 person-year), 62 (55.3 per 100 000 person-year) and 99 (33.1 per 100 000 person-year) NPC cases were identified. The early diagnostic rates of NPC were significantly higher in the participants (79.0%, P < 0.0001) and the screening group (45.9%, P < 0.0001) compared with the control group (20.6%). Although no differences were found between NPC-specific mortality of the screening group and the control group [relative risk (RR)= 0.82, 95% confidence interval (CI) 0.37-1.79], lower NPC-specific mortality was noticed among participants from the screening group versus the control group (RR = 0.22, 95% CI 0.09-0.49).

CONCLUSION

IgA antibodies against EBV can identify high-risk population and was effective in screening for early asymptomatic NPC. Although the mortality reduction was not significant in the primary end point, we noted encouraging evidence of a mortality reduction in screening participants in this interim analysis.

CLINICAL TRIAL NUMBER

NCT00941538.

Chemical constituents of Isatis indigotica

From the roots of Isatis indigotica, ten compounds (1-10) were isolated. Compound 1 is a new alkaloid whose structure was elucidated as (E)-3-(3',5'-dimethoxy-4'-hydroxy-benzylidene)-2-indolinone. Compounds 2-4 were discovered for the first time from a natural source and compounds 5-7 were originally isolated from this species. In a preliminary study, compounds 4-8 showed antiendotoxic activities in vitro.

Role of Aβ-receptor for advanced glycation endproducts interaction in oxidative stress and cytosolic phospholipase A₂ activation in astrocytes and cerebral endothelial cells

Blood-brain barrier (BBB) dysfunctions have been implicated in the progression of Alzheimer's disease. Cerebral endothelial cells (CECs) and astrocytes are the main cell components of the BBB. Although amyloid-β oligomers (Aβ₄₂) have been reported to mediate oxidative damage to the CECs and astrocytes and trigger the downstream mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, the cell surface binding site for Aβ₄₂ and exact sequence of these events have yet to be elucidated. In this study, the receptor for advanced glycation endproducts (RAGE) was postulated to function as a signal transducing cell surface receptor for Aβ₄₂ to induce reactive oxygen species (ROS) generation from NADPH oxidase and trigger downstream pathways for the phosphorylation of extracellular signal-regulated kinases (ERK1/2) and cytosolic phospholipase A₂ (cPLA₂). We found that Aβ₄₂ competed with the anti-RAGE antibody (Ab(RAGE)) to bind to RAGE on the surfaces of CECs and primary astrocytes. In addition, Ab(RAGE) abrogate Aβ₄₂-induced ROS production and the colocalization between the cytosolic (p47-phox) and membrane (gp91-phox) subunits of NADPH oxidase in both cell types. Ab(RAGE) as well as NADPH oxidase inhibitor and ROS scavenger suppressed Aβ₄₂-induced ERK1/2 and cPLA₂ phosphorylation in CECs. At the same time, only Ab(RAGE), but neither NADPH oxidase inhibitor nor ROS scavenger, inhibited the ERK1/2 pathway and cPLA₂ phosphorylation in primary astrocytes. Therefore, this study demonstrates that NADPH oxidase complex assembly and ROS production are not required for Aβ₄₂ binding to RAGE at astrocytic surface leading to sequential phosphorylation of ERK1/2 and cPLA₂, and suggests the presence of two different RAGE-dependent downstream pathways in the CECs and astrocytes.

In-situ encapsulation of quantum dots into polymer microspheres

We have incorporated fluorescent quantum dots (QDs) into polystyrene microspheres using functionalized oligomeric phosphine (OP) ligands. We find that a uniform distribution of quantum dots is loaded inside each polymer bead. Some local close-packing of quantum dots in the beads is attributed to the self-polymerization of the functionalized ligands. The presence of quantum dots disturbs the nucleation and growth processes during the formation of polymer microspheres and results in a wider size distribution of the quantum dot-embedded polystyrene beads than for the control without dots. The change in quantum efficiency of the quantum dots before (approximately 20%) and after (12%) loading into the beads substantiates the protection of oligomeric phosphine ligands yet indicates that the properties of these quantum dots are still affected during processing.

Expression of kappa opioid receptors in human and monkey lymphocytes

mRNA encoding the kappa opioid receptor gene sequence was identified and isolated from various human lymphocytic cells: CEM x174 (a hybrid of T and B origin) cells, Jurkat-T4 cells, human peripheral blood mononuclear cells (PBMC) and purified CD4+ cells. Analyzing the cDNA sequences of RNA transcripts spanning the putative second extracellular loop, which has reported dynorphin specificity, and the seventh transmembrane domain revealed a 100% and 95% homology in amino acid sequence to corresponding kappa opioid receptor sequences in human placenta and rat brain, respectively. Expression of a similar kappa opioid receptor sequence could be detected in normal monkey PBMC but not in monkey PBMC in which the CD4+/CD8+ cell ratio (or CD4+ cell number) was significantly reduced due to prolonged SIV infection. These findings suggest that human and monkey lymphocytes constitutively express kappa opioid receptor mRNA.

N-terminal domain of BARF1 gene encoded by Epstein-Barr virus is essential for malignant transformation of rodent fibroblasts and activation of BCL-2

The BARF1 gene encoded by the Epstein-Barr virus induces morphological changes, loss of contact inhibition and anchorage independence in established rodent Balb/c3T3 fibroblast. BARF1 gene was also capable of inducing malignant transformation in a human Louckes B cell line. Our recent study showed that BARF1 gene had an ability to immortalize primary epithelial cells. However we do not know which region(s) of BARF1 protein is(are) responsible for inducing malignant transformation in established rodent cells. Using the deletion mutants, we now localized a malignant transforming region in N-terminal of BARF1 protein. The mutants lacking this region were unable to transform the cells in malignant state. Furthermore, we demonstrated that only the mutants containing this region rendered the cells resistant to apoptosis induced by serum deprivation. Surprisingly, the BARF1 gene was capable of activating anti-apoptotic Bcl-2 expression and this activation was due to the N-terminal transforming region. These data suggest that the cooperation of BARF1 with Bcl-2 is essential for the induction of malignant transformation.

Oncological outcome of T1 rectal cancer undergoing standard resection and local excision

AIM

We studied the outcome and prognostic factors for T1 rectal cancer patients undergoing standard resection or transanal excision.

METHOD

One hundred and twenty-four patients with T1 rectal cancer were included in the study, of whom 66 (53.2%) underwent standard resection and 58 (46.8%) underwent transanal excision. Survival analysis was performed to compare the outcome.

RESULTS

The 5-year local recurrence rate was 11.0% in the transanal excision group versus 1.6% in the standard resection group (P = 0.031) but the 5-year disease-free survival and overall survival rates were not significantly different between the two groups. Multivariate analysis suggested that a high tumour grade and perineural or lymphovascular invasion were independent risk factors for local recurrence and recurrence-free survival. For high-risk patients (with at least one of the above risk factors), the 5-year local recurrence and 10-year recurrence-free survival rates were 21.2% and 74.5%, versus 1.2% and 92.0% in low-risk patients (P = 0.00003 and P = 0.003). In patients undergoing transanal excision, none in the low-risk group had local recurrence during follow up, while 40% (6 of 15) of patients in the high-risk group developed local recurrence within 5 years after surgery. The 5-year local recurrence rate was 45.0%.

CONCLUSION

Transanal excision in T1 rectal cancer may result in a high rate of local failure for patients with a high-grade tumour, or perineural or lymphovascular invasion. Local excision should be avoided as a curative treatment in high-risk patients.

COL1A1-PDGFB fusion transcripts in fibrosarcomatous areas of six dermatofibrosarcomas protuberans

The fibrosarcomatous transformation of dermatofibrosarcoma protuberans (DFSP) has been considered for some time to be associated with an adverse clinical outcome. However, the molecular and cellular mechanism underlying the tumor progression remains undetermined. As the chimeric gene, COL1A1-PDGFB, has been proposed to play an important role in the histogenesis of DFSP, we conducted a reverse transcription-polymerase chain reaction assay to ascertain whether the COL1A1-PDGFB fusion transcripts can be detected in both conventional DFSP and fibrosarcomatous components of DFSP with fibrosarcomatous areas (DFSP-FS), using a simple method of microdissection on sections of archival formalin-fixed, paraffin-embedded tumor specimens from six DFSP-FS cases. The COL1A1-PDGFB fusion transcripts could be detected in FS areas in five of the six cases, whereas conventional DFSP areas of all cases expressed the chimeric mRNA. A subsequent sequence analysis of the polymerase chain reaction products confirmed that the detected messages were derived from identical gene fusions in the two different components of each of the five cases. Our results verify that the COL1A1-PDGFB fusion transcripts are preserved in the FS areas of most DFSP-FSs. The expression of the fusion transcripts in both conventional DFSP and FS areas of DFSP-FS supports a common histogenesis of the two components.

Status of the Small-Angle Neutron Scattering Station at the Beijing Synchrotron Radiation Facility

Beamline 4B9A at the Beijing Synchrotron Radiation Facility provides focused monochromatic radiation in an energy range of 3–10 keV. The small-angle X-ray scattering (SAXS) station that is located at the end of the beamline is equipped with a SAXS camera, a position-sensitive detector, an on-line data-acquisition and control system and an alignment carriage. Studies in molecular biology and materials science have been performed at the station. Some results of SAXS studies of biomembranes are described. The experiments confirm that the angular resolution is better than 0.5 mrad with this setting.

Quantum transport in alkane molecular wires: effects of binding modes and anchoring groups

Effects of binding modes and anchoring groups on nonequilibrium electronic transport properties of alkane molecular wires are investigated from atomic first-principles based on density functional theory and nonequilibrium Green's function formalism. Four typical binding modes, top, bridge, hcp-hollow, and fcc-hollow, are considered at one of the two contacts. For wires with three different anchoring groups, dithiol, diamine, or dicarboxylic acid, the low bias conductances resulting from the four binding modes are all found to have either a high or a low value, well consistent with recent experimental observations. The trend can be rationalized by the behavior of electrode-induced gap states at small bias. When bias increases to higher values, states from the anchoring groups enter into the bias window and contribute significantly to the tunneling process so that transport properties become more complicated for the four binding modes. Other low bias behaviors including the values of the inverse length scale for tunneling characteristic, contact resistance, and the ratios of the high/low conductance values are also calculated and compared to experimental results. The conducting capabilities of the three anchoring groups are found to decrease from dithiol, diamine to dicarboxylic-acid, largely owing to a decrease in binding strength to the electrodes. Our results give a clear microscopic picture to the transport physics and provide reasonable qualitative explanations for the corresponding experimental data.