Simultaneous Mapping of Electrocatalytic Activity and Selectivity via Hybrid Scanning Electrochemical Probe Microscopy.

Nanoscale scanning electrochemical probe microscopy started to elucidate the heterogeneity of electrocatalytic activity at electrode surfaces. However, understanding the heterogeneity in product selectivity, another crucial aspect of interfacial reactivity, remains challenging. Herein, we introduce a method combining scanning electrochemical microscopy (SECM) and scanning electrochemical cell microscopy (SECCM) to enable the spatially resolved mapping of both activity and selectivity in electrocatalysis. A dual-channel nanopipette probe was developed: one channel for activity mapping and the other for product detection with a high collection efficiency (>95%) and sensitivity. Simultaneous mapping of activity and selectivity in the oxygen reduction reaction (ORR) is demonstrated. Combined with colocalized crystal orientation mapping, we uncover the local electrocatalytic performance of ORR at different facets on polycrystalline Pt and Au. The high-resolution selectivity mapping enabled by our method with colocalized structural characterization can provide structure-activity-selectivity relationships that are often unavailable in ensemble measurement, holding promise for understanding key structural motifs controlling interfacial reactivity.

Resistive pulse analysis of chiral amino acids utilizing metal-amino acid crystallization differences.

Here, we report a proof-of-concept resistive pulse method for analyzing chiral amino acids utilizing metal-amino acid crystallization differences. This method involves introducing an amino acid sample solution into a micropipette through a pressure-driven flow. The sample then mixes with a metal ion solution inside the pipette, forming metal-amino acid crystals. The crystal size depends on the enantiomeric excess (x) of chiral amino acid samples. Large x values lead to large crystals. The crystal size difference is then reflected in the resistive pulse size as they block the ionic transport in a micropipette to different extents. We used Cd-cystine crystallization as a model system and found approximately five times the mean current pulse size difference for racemic (x = 0) and L-only (x = +1) cystine samples. A similar result was observed for aspartate. Our discovery opens up new opportunities for micro/nanoscopic chiral amino acid analysis, which can potentially be used in single-cell analysis.

Characterization and complete genome sequence analysis of two Myoviral bacteriophages infecting clinical carbapenem-resistant Acinetobacter baumannii isolates.

AIMS: The aim of this study was to characterize phenotypical properties, to analyse whole genomes of novel Acinetobacter baumannii phages infecting carbapenem-resistant Ac. baumannii (CRAB) and to evaluate their potential as antimicrobial alternatives to control Ac. baumannii in clinical settings. METHODS AND RESULTS: The Ac. baumannii phages, Βϕ-R1215 and Βϕ-R2315, were isolated from sewage samples. These phages were characterized by transmission electron microscopy, host spectrum, the thermal/pH stability test, the bacterial lysis assay and the whole genome analysis. Both phages lysed 21 of 45 CRAB hosts, and showed high stability at various pH (pH 4-10) and temperature (25-60°C), and were strongly active against host bacteria in vitro. The genomes of Βϕ-R1215 and Βϕ-R2315 are linear double-strands of DNA with 44·866 and 44·846 bp respectively. These two genomes revealed high similarity at the DNA level, but the organization and direction of open reading frames were different. CONCLUSIONS: The Ac. baumannii phages, Βϕ-R1215 and Βϕ-R2315, are novel lytic phages lysing CRAB strains which were isolated from respiratory samples of patients. SIGNIFICANCE AND IMPACT OF THE STUDY: In vitro and in silico data showed that these novel Ac. baumannii phages, Βϕ-R1215 and Βϕ-R2315, have potential as antimicrobial alternatives to control CRAB in healthcare settings.

Risk factors for non-cancer health events in patients with head and neck squamous cell carcinoma.

BACKGROUND: Cancer progression and non-cancer-related morbidities can affect the quality of life and survival of patients with head and neck squamous cell carcinomas (HNSCC). The aim of this study was to investigate the risk factors for the development of non-cancer health events (NCHEs) in HNSCC. PATIENTS AND METHODS: The study involved 465 previously-untreated patients with HNSCC diagnosed between 2005 and 2009 at the Asan Medical Center. Non-cancer-associated morbidity was defined as readmission after treatment of HNSCC due to non-cancer-related causes. NCHEs were defined as the occurrence of non-cancer-associated morbidity or mortality. The incidence and risk factors for NCHEs were analyzed. RESULTS: During the median follow-up of 47.6 months, non-cancer morbidity and mortality occurred in 83 (17.8%) and 25 patients (5.4%), respectively. Thirteen patients (52%) died from non-cancer-related causes with no previous admission for non-cancer causes. Multivariate analysis showed that the incidence of NCHEs was significantly associated with a Charlson comorbidity index ≥1 and stage III/IV disease (P < 0.001). CONCLUSIONS: Patients with comorbidities and advanced diseases may be at higher risk of NCHEs. Because NCHEs are sometimes life-threatening, every effort should be made to avoid unexpected non-cancer-associated mortality in the HNSCC patients.

Experimental realization of Josephson junctions for an atom SQUID.

We report the creation of a pair of Josephson junctions on a toroidal dilute gas Bose-Einstein condensate (BEC), a configuration that is the cold atom analog of the well-known dc superconducting quantum interference device (SQUID). We observe Josephson effects, measure the critical current of the junctions, and find dynamic behavior that is in good agreement with the simple Josephson equations for a tunnel junction with the ideal sinusoidal current-phase relation expected for the parameters of the experiment. The junctions and toroidal trap are created with the painted potential, a time-averaged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single atom-SQUID case reported here. Since rotation plays the same role in the atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor.

Learning from the Heterogeneity at Electrochemical Interfaces.

Understanding the structure-activity relationship at electrochemical interfaces is crucial in improving the performance of practical electrochemical devices, ranging from fuel cells, electrolyzers, and batteries to electrochemical sensors. However, functional electrochemical interfaces are often complex and contain various surface structures, creating heterogeneity in electrochemical activity. In this Perspective, we highlight the role of heterogeneity in electrochemistry, especially in the context of electrocatalysis. Current methods for revealing the heterogeneity at electrochemical interfaces, including nanoelectrochemistry tools and single-entity approaches, are discussed. Lastly, we provide perspectives on what one can learn by studying heterogeneity and how one can use heterogeneity to design more efficient electrochemical devices.

Effect of remifentanil on arterial oxygenation during one-lung ventilation.

This study was designed to assess the dose-related effects of remifentanil on arterial oxygenation during one-lung ventilation (OLV) under total intravenous anaesthesia with propofol. A total of 104 patients scheduled for elective lung resection surgery requiring OLV were randomly assigned to one of four groups with a target effect-site concentration (Ce) of remifentanil of 0.5, 1, 2 or 4 ng/ml. Patients were anaesthetized with propofol and remifentanil in 100% oxygen. Arterial blood gas analysis was performed after 15 min of two-lung ventilation (TLV15, baseline) and after 15 and 30 min of OLV (OLV15 and OLV30). Mean arterial oxygen tension (PaO2) decreased significantly at OLV15 and OLV30 compared with baseline in all groups, but was comparable in the four groups at each time point, suggesting that remifentanil infusion with a Ce < or =4 ng/ml can be successfully used for anaesthesia with propofol during OLV in lung surgery without any significant changes in PaO2.

Quantum interference of currents in an atomtronic SQUID.

Quantum interference of currents is the most important and well known quantum phenomenon in a conventional superconducting quantum interference device (SQUID). Here, we report the observation of quantum interference of currents in an atomtronic SQUID. Analogous to a conventional SQUID, currents flowing through two junctions in an atomtronic SQUID interfere due to the phase difference from rotation. This interference results in modulation of critical currents. This modulation was observed for three different radii with clear modulation periods which were measured to be consistent with fundamental rotation rates. This observation shows the possibility of studying various interesting SQUID physics with an atomtronic SQUID and especially, macroscopic quantum phenomena with currents may be realized with an atomtronic SQUID toward the goal of quantum metrology of rotation sensing.

Effect of drug-eluting metal stents in benign esophageal stricture: an in vivo animal study.

BACKGROUND AND STUDY AIMS: The aim of this study in canines was to investigate the effectiveness and safety of self-expandable metal stents, which were coated with paclitaxel to minimize the tissue response. MATERIALS AND METHODS: 14 dogs (5-10 kg) were randomly allocated to two groups. Drug-eluting stents (DES, n = 7) or nondrug-eluting stents (non-DES, n = 7) were endoscopically inserted and fixed in the esophagus of healthy dogs. Every 2 weeks, for a maximum period of 8 weeks, an endoscopic examination was performed to evaluate the status of stent insertion, the grade of tissue hyperplasia, and mucosal change at both ends of the stent. RESULTS: One case of stent migration was observed after 4 weeks in the non-DES group. In this group, tissue reaction and hyperplasia remained for more than 4 weeks after stent insertion. By contrast, an endoscopic examination of the surrounding esophageal mucosa in the DES group showed very little tissue reaction, and the stent was easily separated from the esophageal tissue. CONCLUSION: Although further studies are required to confirm our results, we suggest that these newly designed DES may provide an alternative tool to manage refractory benign esophageal stricture.

Allopurinol-induced aplastic anemia in a patient with chronic kidney disease.

Aplastic anemia is a rare complication of allopurinol use. We report an unusual case of aplastic anemia associated with allopurinol therapy for hyperuricemia in a patient with chronic kidney disease. A 37-year-old female patient diagnosed with Stage III chronic kidney disease was admitted with pancytopenia. She had a history of taking allopurinol for 5 months. Her bone marrow showed extremely decreased cellularity (< 20%) and there was no malignant cell infiltration. She was free of infections, including parvovirus B19, cytomegalovirus and Epstein-Barr virus. These results suggested a diagnosis of aplastic anemia. Allopurinol was discontinued immediately and treatment with blood transfusions and prednisolone was begun. After 6 months, the bone marrow cellularity improved to approximately 70%. Recently, it was suggested that decreased activity of multidrug resistance P-glycoprotein may play a role in acquired aplastic anemia. So we measured the inhibitory effect of allopurinol and oxypurinol on P-glycoprotein activity. But neither allopurinol nor oxypurinol inhibited P-glycoprotein activity.

Curie-Weiss behavior of liquid structure and ideal glass state.

We present the results of a structural study of metallic alloy liquids from high temperature through the glass transition. We use high energy X-ray scattering and electro-static levitation in combination with molecular dynamics simulation and show that the height of the first peak of the structure function, S(Q) - 1, follows the Curie-Weiss law. The structural coherence length is proportional to the height of the first peak, and we suggest that its increase with cooling may be related to the rapid increase in viscosity. The Curie temperature is negative, implying an analogy with spin-glass. The Curie-Weiss behavior provides a pathway to an ideal glass state, a state with long-range correlation without lattice periodicity, which is characterized by highly diverse local structures, reminiscent of spin-glass.

Protective effect of antioxidant supplementation in sperm-preparation medium against oxidative stress in human spermatozoa.

BACKGROUND: Oxidative stress induced by reactive oxygen species (ROS) is associated with an impaired fertilization ability of spermatozoa. We investigated the effects of adding antioxidants to a sperm preparation medium on the functional parameters of the spermatozoa. METHODS: Spermatozoa were washed with Ham's F-10 media containing the antioxidants, ethylenediaminetetraacetic acid (EDTA) and catalase, at various concentrations, and then the ROS levels in sperm suspensions, and the forward motility, acrosome reaction, DNA integrity and lipid peroxidation of the spermatozoa were assessed. RESULTS: The ROS levels were significantly lower in sperm suspensions washed with the antioxidants (196 approximately 312 rlu; relative light units) than in control sperm (604 rlu, P < 0.05). The addition of 10 microM EDTA to the sperm preparation medium significantly improved the motility of the spermatozoa compared with the control group, the groups containing EDTA at other concentrations and the groups containing catalase. Catalase significantly increased the acrosome reaction rate of the spermatozoa. Both EDTA and catalase significantly decreased the DNA fragmentation rate of the spermatozoa. However, the antioxidants did not reduce lipid peroxidation. CONCLUSIONS: Supplementing sperm preparation medium with EDTA or catalase significantly improved the overall functional parameters of the spermatozoa by reducing the ROS levels.

Removal of a metallic foreign body embedded in the external nose via open rhinoplasty approach.

Most metallic foreign bodies are inert, but they can cause chronic inflammatory reactions and be a source of infection. Identification and removal of foreign bodies from wounds is often necessary. The present report describes two cases of a foreign body embedded in the external nose. Each case was successfully treated by an open rhinoplasty approach. This approach is an effective and safe method for removal of foreign bodies in the external nose. It provides a good surgical field and a better cosmetic outcome than a conventional incision.

Percutaneous direct puncture glue embolization of high-flow craniofacial arteriovenous lesions: a new circular ring compression device with a beveled edge.

SUMMARY: The purpose of this study was to evaluate the efficacy of a newly designed circular ring compression device that allows safe and effective glue injection during preoperative embolization of high-flow superficial craniofacial arteriovenous malformations (AVMs). The device was used in 4 cases of craniofacial AVM with multiple feeding arteries and draining veins. It provided a safe glue injection route as well as effective compression of radiating multiple venous drainage routes.

Cloning and sequence analysis of cDNAs encoding the heavy and light chain variable regions of a human monoclonal antibody with specificity for hepatitis B surface antigen.

We cloned and analyzed the cDNA sequences encoding the variable regions of a human monoclonal antibody (23HN) (gamma1, kappa) that binds to the common a antigenic determinant on hepatitis B surface antigen and its fine epitope is different from those of previously known mAbs with the same specificity. The heavy and light chain variable regions are the members of human heavy chain subgroup III and kappa light chain subgroup III, respectively, and are most homologous to human germline VH segment DP-50 and Vkappa segment DPK-22, respectively.

Angiopoietin-1 inhibits irradiation- and mannitol-induced apoptosis in endothelial cells.

BACKGROUND AND PURPOSE: Angiopoietin-1 (Ang1) is a vasculogenic factor that signals through the endothelial cell-specific Tie2 receptor tyrosine kinase. We recently reported that Ang1 prevented apoptosis induced by serum deprivation in endothelial cells. In this study, we examined whether Ang1 prevents apoptosis in endothelial cells treated with irradiation or clinical concentrations of mannitol. METHODS AND RESULTS: ++Ang1 prevented irradiation- and mannitol-induced apoptosis in human umbilical vein endothelial cells in a dose-dependent manner. Pretreatment with soluble Tie2 receptor, but not Tie1 receptor, blocked the antiapoptotic effect of Ang1. Two phosphatidylinositol 3'-kinase (PI3-kinase)-specific inhibitors, wortmannin and LY294002, blocked the Ang1-induced antiapoptotic effect. The antiapoptotic potency of Ang1 was similar to or greater than that of vascular endothelial growth factor, basic fibroblast growth factor, and endothelin-1. Ang1 also prevented apoptosis in cultured endothelial cells from porcine pulmonary and coronary arteries and in endothelial cells of explanted rat aorta. CONCLUSIONS: Ang1 promotes the survival of endothelial cells in irradiation- and mannitol-induced apoptosis through Tie2 receptor binding and PI3-kinase activation. Pretreatment with Ang1 could be beneficial in maintaining normal endothelial cell integrity during intracoronary irradiation or systemic mannitol therapy.

Normal TCRbeta transcription and recombination in the absence of the Jbeta2-Cbeta2 intronic cis element.

The developmental regulation of antigen receptor gene transcription and recombination are mediated by cis regulatory elements. At the T cell receptor beta chain locus (TCRbeta), two DNase I hypersensitive sites within the Jbeta2-Cbeta2 intron contained binding sites for NF-kappaB and additional nuclear factors and were postulated to be involved in controlling TCRbeta transcription and V(D)J recombination. To test this possibility, we deleted these elements from the mouse genome by homologous recombination and assayed the effect on transcription of both the germline and rearranged TCRbeta locus, and on TCRbeta rearrangement in T and B lymphocytes. We found that TCRbeta transcription and V(D)J recombination and T cell development were normal in these mutant mice. Therefore, the Jbeta2-Cbeta2 intronic elements are dispensable for TCRbeta assembly and function.

Generation and characterization of a novel tetravalent bispecific antibody that binds to hepatitis B virus surface antigens.

Hepatitis B virus (HBV) infection is a worldwide public health problem affecting about 350 million people. HBV envelope contains three surface antigens, called pre-S1, pre-S2 and S. For the prophylaxis of HBV infection, only an anti-S monoclonal antibody was tested for the protective efficacy against HBV infection, but it was shown to be incomplete. In addition, some immune escape mutants carrying mutations on the S antigen were reported. Therefore, a multivalent bispecific antibody rather than a single monoclonal antibody would be more beneficial for the prophylaxis of HBV infection. We have generated a novel tetravalent bispecific antibody with two binding sites for each of the S and pre-S2 antigens. Each of the antigen-binding sites was composed of a single-chain Fv (ScFv). The tetravalent antibody was generated by constructing a single gene encoding a single-chain protein. This protein consisted of an anti-S ScFv whose carboxyl end was tethered, through a 45 amino acid linker, to the amino terminus of anti-preS2 ScFv that in turn was joined to the hinge region of human gamma1 constant region. The single-chain protein was expressed in Chinese hamster ovary cells and secreted in culture supernatant as a homodimeric molecule. The tetravalent bispecific antibody showed both anti-S and anti-pre-S2 binding activities. In addition, the binding affinity of the bispecific antiboy for HBV particles was greater than that of either parental antibody. The tetravalent bispecific antibody is a potentially useful reagent for the prevention and treatment of HBV infection.

Cloning, expression and characterization of a murine-human chimeric antibody with specificity for pre-S2 surface antigen of hepatitis B virus.

The cloning, expression and characterization of a murine-human chimeric antibody with specificity for the pre-S2 surface antigen (Ag) of hepatitis B virus (HBV) is described. The heavy and light chain variable region (VH and VL) genes encoding the murine monoclonal antibody (mAb) were isolated and combined with human gamma 1 and kappa constant region genes, respectively. The expression vectors containing the chimeric heavy and light chain genes were sequentially electroporated into murine Sp2/0 hybridoma cells and transfectomas secreting chimeric antibody were isolated. The chimeric antibody was purified and characterized by ELISA, Western analysis and competition immunoassay, demonstrating that the transfectoma functionally express and secrete murine-human chimeric antibody which retained the specificity and affinity of the parental murine mAb.

Complications in Stent-Assisted Endovascular Therapy of Ruptured Intracranial Aneurysms and Relevance to Antiplatelet Administration: A Systematic Review.

BACKGROUND AND PURPOSE: Despite the increasing use of stent-assisted coiling for ruptured intracranial aneurysms, there is little consensus regarding the appropriate antiplatelet administration for this. The objectives of this systematic review were to provide an overview of complications and their association with the method of antiplatelet administration in stent-assisted coiling for ruptured intracranial aneurysms. MATERIALS AND METHODS: A comprehensive search of the literature in the data bases was conducted to identify studies reporting complications of stent-assisted coiling for ruptured intracranial aneurysms. The pooled event rate of preprocedural thromboembolisms, hemorrhages, and mortality was estimated from the selected studies. Subgroup analyses were performed by the method of antiplatelet administration (pre-, postprocedural, and modified). Meta-analysis was conducted to compare periprocedural complications and mortality between ruptured intracranial aneurysms and unruptured intracranial aneurysms. RESULTS: Of the 8476 studies identified, 33 with 1090 patients were included. The event rates of thromboembolism and intra- and postprocedural hemorrhage were 11.2% (95% CI, 9.2%-13.6%), 5.4% (95% CI, 4.1%-7.2%), and 3.6% (95% CI, 2.6%-5.1%), respectively. Subgroup analyses of thromboembolism showed a statistically significant difference between groups (P < .05). In the preprocedural and modified antiplatelet groups, the risk for thromboembolism in stent-assisted coiling for ruptured intracranial aneurysm was not significantly different from that for unruptured intracranial aneurysm, though this risk of the postprocedural antiplatelet group was significantly higher in ruptured intracranial aneurysms than in unruptured intracranial aneurysms. CONCLUSIONS: On the basis of current evidence, complications of stent-assisted coiling for ruptured intracranial aneurysm may be affected by the method of antiplatelet administration.