Atrial septal perforation with Needle's Eye Snare during transvenous lead extraction.

Although the Needle's Eye Snare (Cook Medical) has been considered useful for lead extraction, serious complications can occur. We presented a case of atrial septal perforation associated with the Needle's Eye Snare. Our case highlights the importance of not persisting with the Needle's Eye Snare to prevent atrial damage.

Multilamellar and Multivesicular Outer Membrane Vesicles Produced by a Buttiauxella agrestis tolB Mutant.

Outer membrane vesicles (OMVs) are naturally released from Gram-negative bacteria and play important roles in various biological functions. Released vesicles are not uniform in shape, size, or characteristics, and little is known about this diversity of OMVs. Here, we show that deletion of tolB, which encodes a part of the Tol-Pal system, leads to the production of multiple types of vesicles and increases overall vesicle production in the high-vesicle-forming Buttiauxella agrestis type strain JCM 1090. The ΔtolB mutant produced small OMVs and multilamellar/multivesicular OMVs (M-OMVs) as well as vesicles with a striking similarity to the wild type. M-OMVs, previously undescribed, contained triple-lamellar membrane vesicles and multiple vesicle-incorporating vesicles. Ultracentrifugation enabled the separation and purification of each type of OMV released from the ΔtolB mutant, and visualization by quick-freeze deep-etch and replica electron microscopy indicated that M-OMVs are composed of several lamellar membranes. Visualization of intracellular compartments of ΔtolB mutant cells showed that vesicles were accumulated in the broad periplasm, which is probably due to the low linkage between the outer and inner membranes attributed to the Tol-Pal defect. The outer membrane was invaginating inward by wrapping a vesicle, and the precursor of M-OMVs existed in the cell. Thus, we demonstrated a novel type of bacterial OMV and showed that unconventional processes enable the B. agrestis ΔtolB mutant to form unique vesicles.IMPORTANCE Membrane vesicle (MV) formation has been recognized as a common mechanism in prokaryotes, and MVs play critical roles in intercellular interaction. However, a broad range of MV types and their multiple production processes make it difficult to gain a comprehensive understanding of MVs. In this work, using vesicle separation and electron microscopic analyses, we demonstrated that diverse types of outer membrane vesicles (OMVs) were released from an engineered strain, Buttiauxella agrestis JCM 1090T ΔtolB mutant. We also discovered a previously undiscovered type of vesicle, multilamellar/multivesicular outer membrane vesicles (M-OMVs), which were released by this mutant using unconventional processes. These findings have facilitated considerable progress in understanding MV diversity and expanding the utility of MVs in biotechnological applications.

Elementary processes of DNA surface hybridization resolved by single-molecule kinetics: implication for macroscopic device performance.

Direct monitoring of single-molecule reactions has recently become a promising means of mechanistic investigation. However, the resolution of reaction pathways from single-molecule experiments remains elusive, primarily because of interference from extraneous processes such as bulk diffusion. Herein, we report a single-molecule kinetic investigation of DNA hybridization on a metal surface, as an example of a bimolecular association reaction. The tip of the scanning tunneling microscope (STM) was functionalized with single-stranded DNA (ssDNA), and hybridization with its complementary strand on an Au(111) surface was detected by the increase in the electrical conductance associated with the electron transport through the resulting DNA duplex. Kinetic analyses of the conductance changes successfully resolved the elementary processes, which involve not only the ssDNA strands and their duplex but also partially hybridized intermediate strands, and we found an increase in the hybridization efficiency with increasing the concentration of DNA in contrast to the knowledge obtained previously by conventional ensemble measurements. The rate constants derived from our single-molecule studies provide a rational explanation of these findings, such as the suppression of DNA melting on surfaces with higher DNA coverage. The present methodology, which relies on intermolecular conductance measurements, can be extended to a range of single-molecule reactions and to the exploration of novel chemical syntheses.

Kinetic investigation of a chemical process in single-molecule junction.

Herein, we report on the kinetic investigation for the breakdown of single-molecule junctions. Current through the junctions was measured as a function of time to elucidate their lifetimes. The analysis of the lifetimes revealed that the breakdown reaction obeys first-order reaction kinetics, and the rate constants determined from the analysis were found to reflect the stability of the junctions.

Highly Reproducible Formation of a Polymer Single-Molecule Junction for a Well-Defined Current Signal.

Single-molecule devices attract much interest in the development of nanoscale electronics. Although a variety of functional single molecules for single-molecule electronics have been developed, there still remains the need to implement sophisticated functionalization toward practical applications. Given its superior functionality encountered in macroscopic materials, a polymer could be a useful building block in the single-molecule devices. Therefore, a molecular junction composed of polymer has now been created. Furthermore, an automated algorithm was developed to quantitatively analyze the tunneling current through the junction. Quantitative analysis revealed that the polymer junction exhibits a higher formation probability and longer lifetime than its monomer counterpart. These results suggest that the polymer provides a unique opportunity to design both stable and highly functional molecular devices for nanoelectronics.

Evidence for line width and carrier screening effects on excitonic valley relaxation in 2D semiconductors.

Monolayers of transition metal dichalcogenides (TMDC) have recently emerged as excellent platforms for exploiting new physics and applications relying on electronic valley degrees of freedom in two-dimensional (2D) systems. Here, we demonstrate that Coulomb screening by 2D carriers plays a critical role in excitonic valley pseudospin relaxation processes in naturally carrier-doped WSe2 monolayers (1L-WSe2). The exciton valley relaxation times were examined using polarization- and time-resolved photoluminescence spectroscopy at temperatures ranging from 10 to 160 K. We show that the temperature-dependent exciton valley relaxation times in 1L-WSe2 under various exciton and carrier densities can be understood using a unified framework of intervalley exciton scattering via momentum-dependent long-range electron-hole exchange interactions screened by 2D carriers that depend on the carrier density and the exciton linewidth. Moreover, the developed framework was successfully applied to engineer the valley polarization of excitons in 1L-WSe2. These findings may facilitate the development of TMDC-based opto-valleytronic devices.

Evaluation of the Kinetic Property of Single-Molecule Junctions by Tunneling Current Measurements.

We investigated the formation and breaking of single-molecule junctions of two kinds of dithiol molecules by time-resolved tunneling current measurements in a metal nanogap. The resulting current trajectory was statistically analyzed to determine the single-molecule conductance and, more importantly, to reveal the kinetic property of the single-molecular junction. These results suggested that combining a measurement of the single-molecule conductance and statistical analysis is a promising method to uncover the kinetic properties of the single-molecule junction.

Ferrocene conjugated oligonucleotide for electrochemical detection of DNA base mismatch.

We describe the synthesis, binding, and electrochemical properties of ferrocene-conjugated oligonucleotides (Fc-oligos). The key step for the preparation of Fc-oligos contains the coupling of vinylferrocene to 5-iododeoxyuridine via Heck reaction. The Fc-conjugated deoxyuridine phosphoramidite was used in the Fc-oligonucleotide synthesis. We show that thiol-modified Fc-oligos deposited onto gold electrodes possess potential ability in electrochemical detection of DNA base mismatch.

Interaction of Bacterial Membrane Vesicles with Specific Species and Their Potential for Delivery to Target Cells.

Membrane vesicles (MVs) are secreted from a wide range of microbial species and transfer their content to other cells. Although MVs play critical roles in bacterial communication, whether MVs selectively interact with bacterial cells in microbial communities is unclear. In this study, we investigated the specificity of the MV-cell interactions and evaluated the potential of MVs to target bacterial cells for delivery. MV association with bacterial cells was examined using a fluorescent membrane dye to label MVs. MVs derived from the enterobacterium Buttiauxella agrestis specifically interacted with cells of the parent strain but interacted less specifically with those of other genera tested in this study. Electron microscopic analyses showed that MVs were not only attached on B. agrestis cells but also fused to them. The interaction energy, which was characterized by hydrodynamic diameter and zeta potential based on the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, was significant low between MVs and cells in B. agrestis, compared to those between B. agrestis MVs and cells of other genera. Similar specific interaction was also occurred between B. agrestis MVs and cells of six other species belonging to Buttiauxella spp. B. agrestis harboring plasmid pBBR1MCS-1 secreted plasmid-containing MVs (p-MVs), and plasmid DNA in p-MVs was transferred to the same species. Moreover, antibiotic-associated MVs enabled effective killing of target species; the survival rate of B. agrestis was lower than those of Escherichia coli and Pseudomonas aeruginosa in the presence of gentamicin-associated MVs derived from B. agrestis. Altogether, we provide the evidence that MVs selectively interact with target bacterial cells and offer a new avenue for controlling specific bacterial species using bacterial MVs in microbial communities.

Bacterial membrane vesicles, an overlooked environmental colloid: Biology, environmental perspectives and applications.

Phospholipid vesicles play important roles in biological systems. Bacteria are one of the most abundant organisms on Earth, and bacterial membrane vesicles (MVs) were first observed 50 years ago. Many bacteria release MVs to the environment that mainly consist of the cell membrane and typically range from 20 to 400 nm in size. Bacterial MVs are involved in several biological functions, such as delivery of cargo, virulence and gene transfer. MVs can be isolated from laboratory culture and directly from the environment, indicating their high abundance in and impact on ecosystems. Many colloidal particles in the environment ranging in size from 1 nm to 1 µm have been reported but not characterized at the molecular level, and MVs remain to be explored. Hence, MVs can be considered terra incognita in environmental colloid research. Although MV biogenesis and biological roles are yet to be fully understood, the accumulation of knowledge has opened new avenues for their applications. Via genetic engineering, the MV yield can be greatly increased, and the components of MVs can be tailored. Recent studies have demonstrated that MVs have promising potential for applications such as drug delivery systems and nanobiocatalysts. For instance, MV vaccines have been extensively studied and have already been approved in Europe. Recent MV studies have evoked great interest in the fields of biology and biotechnology, but fundamental questions, such as their transport in the environment or physicochemical features of MVs, remain to be addressed. In this review, we present the current understanding of bacterial MVs and environmental perspectives and further introduce their applications.

Low-density microparticles with petaloid surface structure for pulmonary drug delivery.

The morphology of spray-dried particles composed of psicose and hydroxypropyl methylcellulose was modified by adding ammonium bicarbonate (ABC) to the solution. The surface structure of the particles was altered by immediate transformation of ABC to gaseous components during the spray drying. As a result, low-density microparticles with a petaloid surface structure, which was controllable by changing the evaporation rate of ABC, was obtained. This technique should be useful for modifying characteristics of solid particles for pulmonary drug delivery.

Sorption of Eu(III) on granite: EPMA, LA-ICP-MS, batch and modeling studies.

Eu(III) sorption on granite was assessed using combined microscopic and macroscopic approaches in neutral to acidic conditions where the mobility of Eu(III) is generally considered to be high. Polished thin sections of the granite were reacted with solutions containing 10 µM of Eu(III) and were analyzed using EPMA and LA-ICP-MS. On most of the biotite grains, Eu enrichment up to 6 wt % was observed. The Eu-enriched parts of biotite commonly lose K, which is the interlayer cation of biotite, indicating that the sorption mode of Eu(III) by the biotite is cation exchange in the interlayer. The distributions of Eu appeared along the original cracks of the biotite. Those occurrences indicate that the prior water-rock interaction along the cracks engendered modification of biotite to possess affinity to the Eu(III). Batch Eu(III) sorption experiments on granite and biotite powders were conducted as functions of pH, Eu(III) loading, and ionic strength. The macroscopic sorption behavior of biotite was consistent with that of granite. At pH > 4, there was little pH dependence but strong ionic strength dependence of Eu(III) sorption. At pH < 4, the sorption of Eu(III) abruptly decreased with decreased pH. The sorption behavior at pH > 4 was reproducible reasonably by the modeling considering single-site cation exchange reactions. The decrease of Eu(III) sorption at pH < 4 was explained by the occupation of exchangeable sites by dissolved cationic species such as Al and Fe from granite and biotite in low-pH conditions. Granites are complex mineral assemblages. However, the combined microscopic and macroscopic approaches revealed that elementary reactions by a single mineral phase can be representative of the bulk sorption reaction in complex mineral assemblages.

Competition of thermodynamic and dynamic factors during formation of multicomponent particles via spray drying.

As psicose cannot be spray dried because of its low glass transition temperature (T(g)), additives have been used to manufacture spray-dried particles. Its thermodynamic miscibility with each additive was evaluated by thermal analysis and C solid-state nuclear magnetic resonance. Aspartame was miscible with psicose at all ratios, and spray-dried particles were obtained when T(g) of the mixture was higher than the outlet temperature of the spray dryer, where 30 wt % of psicose was loaded. poly(vinylpyrrolidone) and cluster dextrin were partially miscible with psicose, with a maximum loading of 40 wt %. When polymeric excipients were used, their mixing behavior with psicose was affected by the dynamic factor during the spray drying, that is, enhanced phase separation due to the molecular-weight difference. The T(g) value of the polymer-rich phases, which were likely to form shell layers on the surfaces, played an important role in determining availability of the spray-dried particles. Hydroxypropyl methylcellulose (HPMC) offered a very effective loading capacity of 80 wt %, due to distinct phase separation to form shell phase with a very high T(g). Because molecular weight of HPMC was the smallest among the polymeric excipients, the thermodynamic miscibility seemed to affect the dynamic phase separation. These results provide useful information for preparing multicomponent spray-dried particles.

[Comparison of the Parker flex-tip tube with the standard tube for Airtraq intubation].

BACKGROUND: During tracheal intubation with the Airtraq laryngoscope (AL), the tracheal tube tip sometimes impinges on the glottis or other laryngeal structures. We tested a hypothesis that Parker flex-tip tube (PT) makes AL assisted tracheal intubation easier and faster than a conventional tube (Mallinckrod Hi-Lo tube : HT). METHODS: Study 1. Fifty patients were assigned to group PT (n = 25) or group HT (n = 25). After induction of general anesthesia, intubation was performed with AL. We recorded tube passage time, the number of tube impingements, circulatory changes and incidences of postoperative complications. Study 2. Twenty patients were divided into two groups and intubated either by HT or PT. We assessed the tip direction and contact points of each tube. RESULTS: Study 1. The use of PT significantly reduced the number of tube impingements compared to HT. Tube passage time in group PT was shorter than that in group HT, but the difference was not statistically significant. Study 2. The tube tip contact with the vocal cords was more frequent with HT. CONCLUSIONS: PT significantly reduced the number of impingements. The shape of tube tip and the smaller angle of PT when fitted in AL contributed to the relative ease of tube passage.

Synthesis and hybridization of oligonucleotides attached to a redox reporter via ethenyl linker at 5-position of pyrimidine base.

We describe a new ferrocene-based redox-reporter that electronically couples to the DNA Pi-electron system.

Improvement of occipital alpha activity by repetitive hyperbaric oxygen therapy in patients with carbon monoxide poisoning: a possible indicator for treatment efficacy.

OBJECTIVES: The main aim of this study was to evaluate the efficacy of repetitive hyperbaric oxygen (HBO) treatments with monitoring of quantitative electroencephalography (qEEG) for symptoms of acute carbon monoxide (CO) poisoning and prevention of delayed neuropsychiatric sequelae. METHODS: Eight patients with acute CO poisoning received repetitive HBO treatments five times a week and qEEG was recorded once a week. Peak alpha frequency, peak alpha power, and absolute and relative alpha power in the occipital region were evaluated. The repetitive HBO treatments were discontinued when the peak alpha frequency increased to and maintained a maximum in each patient. RESULTS: The mean number of HBO treatments was 20.3. The peak alpha frequency and the relative alpha power significantly increased after repetitive HBO treatments. The absolute alpha power and the peak alpha power insignificantly improved. Total numbers of HBO treatments were not correlated with age, duration of CO exposure, initial level of COHb, or interval to the first HBO treatment. After the completion of repetitive HBO treatments, no patient developed delayed neuropsychiatric sequelae. CONCLUSIONS: These results suggest that repetitive HBO treatments may prevent the delayed neuropsychiatric sequelae of CO poisoning when applied individually with monitoring of the peak alpha frequency as an indicator of efficacy.

Estimation of bone mineral density and architectural parameters of the distal radius in hemodialysis patients using peripheral quantitative computed tomography.

We analyzed bone changes in a series of hemodialysis patients followed up for a maximum of 299 months by assessing bone mineral density (BMD) and architectural parameters of the distal radius using peripheral quantitative computed tomography (pQCT), and determined the predictors of skeletal changes in these patients. No significant differences in trabecular BMD (BMD(T)) were found compared with BMD(T) of the normal control. In contrast, cortical BMD (BMD(C)) was significantly decreased compared with BMD(C) of the normal controls. Hemodialysis patients had significantly lower values for cortical bone area, cortical thickness, moment of inertia, and polar moment of inertia than the age-matched controls. From single and multiple regression analysis, the most significant predictor of metabolic bone disease in these cases was found to be duration of hemodialysis. In addition, increases in serum alkaline phosphatase and intact parathyroid hormone in secondary hyperparathyroidism were found to correlate with a decrease in pQCT values in cortical bone; as such, these increases were also found to be a predictive. The present study confirms that the reduction in both BMD(C) and architectural parameters in hemodialysis patients occurs partly because of prolonged hemodialysis and secondary hyperparathyroidism. In addition, immobilization, dietary factors, daily intake of calcium or vitamin D, and so on must be taken into account when clarifying the causes of skeletal complications resulting from hemodialysis.

A case of sleep choking syndrome improved by the Kampo extract of Hange-koboku-to.

A case of sleep choking syndrome with typical symptoms is presented. A 44-year-old Japanese male suffered from multiple episodes of choking, which suddenly appeared with fear of impending death about 30 min after falling asleep almost every night. Overnight polysomnography showed an apnea index of 0.92 events/h, an apnea-hypopnea index of 2.77 events/h, and normal respiration during sleep with the exception of the episodes of apnea and hypopnea. No choking episode occurred in the sleep laboratory. The administration of 500 mg of acetazolamide was ineffective, but the choking episode improved after the administration of Kampo extract of Hange-koboku-to (Ban-xia-hou-pu-tang). Hange-koboku-to may be effective in treating choking sensation during sleep as well as during wakefulness.