bluuebunny/crossref_metadata_2025 huggingface dataset:
Proton Transport in Mesoporous Silica SBA-16 Thin Films With Three-Dimensional Cubic Structures
Authors: Hwang Junho , Daiguji Hirofumi
Published: December 2013

Mesoporous silica SBA-16 thin films with highly ordered 3D cubic structures were synthesized by evaporation-induced self-assembly method, using an F127 triblock copolymer as the structure-directing agent via dip coating, to investigate proton transport of aqueous solutions confined in mesopores. Using electrochemical measurements of ionic current under DC electric fields, we elucidated proton transport phenomena through mesopores of SBA-16 thin films. At low concentrations, ranging from 10−7 to 10−5 M, the I–V curves of KCl and HCl aqueous solutions were nonlinear. However, at 10−4 and 10−3 M, while I–V curves of KCl aqueous solutions displayed nonlinear behavior, those of HCl aqueous solutions were almost linear. The linear behavior can be attributed to a decrease in the electric potential barrier owing to a reduction in the surface charge density, which is caused by the protonation of silanol groups on the inner surface of mesopores. At high concentrations, ranging from 10−2 to 1 M, the I–V curves of KCl and HCl aqueous solutions were almost linear because the effect of surface charge of mesopores on ion transport was marginal.
Scaling-Up Microchannel Emulsification Foreseeing Novel Bioactives Delivery Systems
Authors: Neves Marcos A. , Kobayashi Isao , Nakajima Mitsutoshi
Published: December 2013

In the recent years, emulsification technologies that generate droplets individually have attracted a great deal attention in various fields, e.g., for chemicals, cosmetics, foods, and pharmaceuticals. Such drop-by-drop emulsification technologies include membrane emulsification using microporous membranes and microchannel (MC) emulsification, among others. The authors developed MC emulsification chips, consisting of parallel microgrooves or compactly arranged straight through-holes. Using this MC emulsification technique, the authors have evaluated the formulation a two-phase system consisting of size-controlled O/W emulsions loaded with bioactive molecules, such as β-carotene or γ-oryzanol, PUFAs or polyphenols. The MC emulsification process enabled the production of β-carotene-loaded O/W emulsions with average droplet size (dav) of 27.6 μm and coefficient of variation (CV) of 2.3% and γ-oryzanol-loaded droplets with dav of 28.8 μm and CV of 3.8%. The highly monodisperse O/W emulsions were physically stable during up 4 months storage in darkness at 5 °C. In addition, we investigated the formation characteristics of O/W emulsion droplets in the presence of electrolyte by MC emulsification using differently charged surfactants. Droplet formation was conducted by pressurizing a dispersed phase (refined soybean oil) through the MC silicon chip into a continuous phase containing 1.0 wt% of sodium dodecyl sulfate (SDS) or polyoxyethylene (20) sorbitan monolaurate (Tween 20), and an electrolyte (NaCl) (0–1.0 mol/L). Monodisperse O/W emulsions with an dav of 26 μm and a CV below 5% were produced when the NaCl concentration was lower than a threshold level that is 0.3 mol/L for SDS and 0.5 mol/L for Tween 20. The authors also developed a large MC emulsification device including a newly designed asymmetric MC array chip to realize the mass production of uniformly sized droplets on a liter per hour scale, so that satisfying the minimum droplet productivity needed for industrial-scale production. The large MC emulsification device has a potential droplet productivity exceeding several tons per year, which could satisfy a minimum industrial-scale production of monodisperse microdispersions containing emulsion droplets, microparticles, and microcapsules loaded with bioactive compounds. Such systems have as continuously increasing potential application in the formulation of functional foods, providing a good opportunity to improve the solubility of bioactive compounds, so that increasing their bioavailability.
Lateral Migration of Large and Small Droplets Suspended in Channel Flow
Authors: Makino Masato , Sugihara-Seki Masako
Published: December 2013

In order to investigate the effect of the size differences between suspended particles on the segregation behavior in channel flow of multicomponent suspensions, we conduct a two-dimensional numerical simulation for suspensions of fluid droplets of two different sizes subjected to a plane Poiseuille flow. The large and small droplets are assumed to have equal surface tensions and equal internal viscosities. The temporal evolutions of the lateral positions of the large and small droplets relative to the channel centerline are computed for various size ratios and area ratios of the large and small droplets. It is found that the small droplets tend to migrate toward the channel walls with increasing fraction of the large droplets and that the mean lateral positions of the large droplets are always closer to the channel centerline compared to the mean lateral positions of the small droplets, which represent the margination of the small droplets and the segregation of the droplets caused by the size difference. These trends are enhanced as the size ratio of large and small droplets is increased.
Pump Head Improvement of Diffuser/Nozzle Valve-Less Micropump
Authors: Tanaka Seiichi , Miyazaki Koji , Fujiwara Seiji
Published: December 2013

Micro-pumps are very important for advanced micro fluidic systems such as Lab-on-a-Chips and micro cooling systems, which have been well investigated during the last decades. We developed a valve-less micro-pump with one diffuser/nozzle shaped channel and a variable volume chamber which produces an oscillating flow. One-way flow of the micro-pump was realized in an asymmetric channel by an oscillating flow. Micro-pumps require at least total pump head of 40 kPa to apply micro fluidic devices. In order to achieve above pump head, improvement of original pump is required. In this study, the effect of channel geometry on the pump head of a valve-less micro-pump with a diffuser/nozzle shaped channel was investigated. The micro-pump channels of various angles of 30, 60, 90 degrees between main channel and connecting channel to the chamber with actuator were prepared. The cross section dimensions of the micro-pump channel were 500 microns × 500 microns. The spread angle of the diffuser shape was 50 degrees. The measured pump heads were rearranged using dimensionless numbers as head coefficient to compare for various pump channels. As a result, larger head coefficient was obtained at the angle of 30 degrees which had higher junction loss from the chamber to the inlet channel. The maximum pump head 10.2 kPa was obtained by improved micro-pump, and the value was 1.5 times higher than original pump. The pump head for various drive conditions and channels were estimated using simplified analysis for unsteady operation of the pump based on Bernoulli’s theorem. The calculated pump characteristics agreed with the measured ones.
Molecular Simulation of Adsorbed Water on Mesoporous Silica Thin Films
Authors: Yamashita Kyohei , Daiguji Hirofumi
Published: December 2013

Grand canonical Monte Carlo (GCMC) and canonical ensemble molecular dynamics (NVT-MD) simulations were performed to investigate water adsorption properties in mesoporous silica thin films. The effect of pore radius on the adsorption properties was assessed using two models of mesoporous silica thin films having different pore radius and film thickness (1.38 and 5.66 nm in Model 1, respectively, and 1.81 and 7.30 nm in Model 2, respectively). In the simulations, a water adsorption layer or water menisci were formed in a mesopore accompanying the growth or shrinkage of stable adsorption layers on the upper and lower surfaces. The stable two water adsorption layers were formed on the pore surface in both models. The curvature radius of a water meniscus decreased monotonically and approached a constant value. In addition, NVT-MD simulations were performed to investigate the kinetics of water uptake into a model of mesoporous silica thin film having a radius and thickness of 1.38 and 7.93 nm (Model 3). The calculation results showed that the kinetics of water uptake depended on the number of water molecules and there were two different transport mechanisms in the pore. One was diffusion of water along the pore surface, and the other was capillary rise of liquid water.
A Hybrid Fokker-Planck-DSMC Solution Algorithm for the Whole Range of Knudsen Numbers
Authors: Gorji M. Hossein , Küchlin Stephan , Jenny Patrick
Published: December 2013

In this work, we present a hybrid algorithm based on the Fokker-Planck (FP) kinetic model and direct simulation Monte Carlo (DSMC) for studies of rarefied gas flows. A particle based FP solution algorithm for rarefied gas flow simulations has recently been devised by the authors. The motivation behind the FP approximation is purely computational, i.e. due to the fact that the resulting random processes are continuous in time the computational cost of the corresponding time integration becomes independent of the Knudsen number. However, the method faces limitations for flows with very high Knudsen numbers (larger than approximately 5). In the method presented here, the FP approach is coupled with DSMC in order to gain from the efficiency of the FP model and from the accuracy of DSMC at small and large cell based Knudsen numbers, respectively.
Motion of Passive Particles Carried by Viscoelastic Fluid Flow in the Curvilinear Microchannel
Authors: Li Xiao-Bin , Li Dong-Yang , Zhang Hong-Na , Li Feng-Chen
Published: December 2013

Chaotic flow can be obtained in the viscoelastic fluid flow in the curved microchannel at very low Reynolds number. Influenced by the microstructures of viscoelastic fluid, the passive particles (scalar) transportation carried by the flow will be greatly enhanced. This paper presents a direct numerical simulation (DNS) for the chaotic viscoelastic flow and passive mixing in the curvilinear microchannel. The flow structures, mixing effect, passive scalar evolution with time are discussed. The simulations are conducted for a large range of viscoelasticity, which is parameterized by Weissenberg number (Wi). As Wi grows, the flow tends to a chaotic state, while the evolution of scalar gets strong and fast, showing excellent agreement with experiments. For the structures of scalar gradients in the flow field, they varies quickly in the form of isosurfaces with time, with “rolls” in the bulk changing into “threads” near the wall. That indicates the flow fields should be related to the micro deformation of viscoelastic molecules. The probability distribution function (pdf) analysis between micro-molecular deformation and flow field deformation shows that the main direction of molecular stretching is perpendicular to the main direction of flow field deformation. It implies they are weakly correlated, due to the confinement of channel wall.
Empirical Verification of Theoretical Models on Performance Characteristics of Micro-Pillar Wick Structures
Authors: Horner David , Tej Sai , Moghaddam Saeed
Published: December 2013

Two-phase passive heat carriers/spreaders are effective thermal management tools. However, their thermal performance is limited due to the transport characteristics of their wick structure. To enhance the performance of passive heat spreaders and expand their use to applications with high heat loads and severe operating environments, better wick structures are being developed. Advancements in the design of these structures have been hampered by a lack of models that can predict fluid flow rate in wicks over a wide range of geometrical parameters. The focus of this study is to find such a model for micro-pillar arrays. The model is intended for use in optimizing an array to achieve maximum liquid permeability at a given hydrostatic pressure. Two wicking devices with different pillar spacings were fabricated. The maximum heat transfer capacities of the devices at various wicking lengths were compared with predictions of selected correlations. A model by Byon et al. [1] predicted the experimental results with reasonable accuracy.
Studies on Micropump/Minipump Using Rotational Motion of Magnetic Material Balls
Authors: Kumamaru Hiroshige , Sakata Fuma , Ohue Akira , Itoh Kazuhiro , Shimogonya Yuji
Published: December 2013

Experiments and numerical analyses have been performed on micropumps/minipumps using rotational motion of magnetic material balls. In the pumps, magnetic material balls and nonmagnetic materials balls rotate in a closed channel loop, and a part of the balls acts as a piston and the remaining part of the balls serves as a valve. Experiments have been carried out on two pumps, i.e. a smaller pump and a larger pump with channel cross-sections of ∼1 mm and ∼2 mm inner diameter, respectively. The maximum flow rate achieved and the maximum pump head obtained are ∼500 μl/min and ∼70 Pa, respectively, for the smaller pump, and ∼2000 μl/min and ∼150 Pa, respectively, for the larger pump. Numerical analyses have been performed by dividing the pumping loop into a piston channel and a valve channel. The numerical analyses overestimate the flow rate obtained in the experiments, except for the region of larger pump heads in the larger pump.
Experimental Investigation of Enhanced Absorption of Carbon Dioxide in Diethanolamine in a Microreactor
Authors: Ganapathy Harish , Shooshtari Amir , Dessiatoun Serguei , Alshehhi Mohamed , Ohadi Michael M.
Published: December 2013

Natural gas in its originally extracted form comprises carbon dioxide and hydrogen sulfide as small, but non-negligible fractions of its dominant component, methane. Natural gas in the above form is typically subjected to a sweetening process that removes these acid gases. Microscale technologies have the potential to substantially enhance mass transport phenomena on account of their inherently high surface area to volume ratio. The present work reports the mass transfer characteristics during gas-liquid absorption in a microreactor. The absorption of CO2 mixed with N2 into aqueous diethanolamine was investigated in a single straight channel having a hydraulic diameter of 762 micrometer and circular cross-sectional geometry. The performance of the reactor was characterized with respect to the absorption efficiency and mass transfer coefficient. Close to 100% absorption efficiency was obtained under optimum operating conditions. Shorter channel lengths were observed to yield enhanced values of mass transfer coefficient on account of the improved utilization of the liquid reactants’ absorption capacity for a given reactor volume. In comparison to the 0.5 m long channel, the mass transfer coefficients with the 0.3 m and 0.1 m channels were higher on an average by 35.2% and 210%, respectively. Parametric studies investigating the effects of phase superficial velocity, liquid and gas phase concentration were performed. The mass transfer coefficients achieved using the present minichannel reactor were 1–3 orders of magnitude higher than that reported using conventional gas-liquid absorption systems.
Contribution of Microlayer Evaporation to Bubble Growth in Pool Saturated Boiling of Water
Authors: Yabuki Tomohide , Saitoh Takuya , Nakabeppu Osamu
Published: December 2013

Heat transfer and formation characteristics of the microlayer are investigated by the surface temperature measurement with a MEMS thermal sensor and the wall heat transfer evaluation using an experimental data. The temperature data clearly indicated transition of heat transfer phenomenon on the heated surface from microlayer formation via dry-out of the microlayer to rewetting of the dry-out region. Microlayer evaporation transferred extremely high heat flux over 1 MW/m2 and was found to be the dominant heat transfer mechanism in the wall heat transfer during isolated bubble boiling of water. The contribution of microlayer evaporation to bubble growth was found to be 50% and not vary with wall superheat. Finally the spatial distribution of initial thickness of microlayer was calculated from the wall heat transfer.
PLC-γ and PI3K Link Cytokines to ERK Activation in Hematopoietic Cells with Normal and Oncogenic
Kras
Authors: Diaz-Flores Ernesto , Goldschmidt Hana , Depeille Philippe , Ng Victor , Akutagawa Jon , Krisman Kimberly , Crone Michael , Burgess Michael R. , Williams Olusegun , Houseman Benjamin , Shokat Kevan , Sampath Deepak , Bollag Gideon , Roose Jeroen P. , Braun Benjamin S. , Shannon Kevin
Published: December 2013

Targeting signaling pathways upstream of oncogenic Ras may have therapeutic benefit in the treatment of leukemia.
Hormones in Repair and Resistance
Authors: Ferrarelli Leslie K.
Published: December 2013

Radiotherapy resistance in prostate cancer is promoted by androgen receptor-stimulated transcription of DNA repair genes.
Nucleotide Sequence Analysis of Integrative Conjugative Element Tn
5253
of Streptococcus pneumoniae
Authors: Iannelli Francesco , Santoro Francesco , Oggioni Marco R. , Pozzi Gianni
Published: December 2013

Conjugative transposon Tn
5253
, an integrative conjugative element (ICE) of
Streptococcus pneumoniae
carrying the
cat
and
tet
(M) genes, was shown to be 64,528 bp in size and to contain 79 open reading frames, of which only 38 could be annotated. Two distinct genetic elements were found integrated into Tn
5253
: Tn
5251
(18,033 bp), of the Tn
916
-Tn
1545
family of ICEs, and Ω
cat
(pC194) (7,627 bp), which could not conjugate but was capable of intracellular mobility by excision, circularization, and integration by homologous recombination. The highest conjugation frequency of Tn
5253
was observed when
Streptococcus pyogenes
was the donor (6.7 × 10
−3
transconjugants/donor).
Extended-Spectrum-β-Lactamase-Producing Escherichia coli as Intestinal Colonizers in the German Community
Authors: Valenza Giuseppe , Nickel Silke , Pfeifer Yvonne , Eller Christoph , Krupa Elzbieta , Lehner-Reindl Verena , Höller Christiane
Published: December 2013

We determined the presence of extended-spectrum-β-lactamase (ESBL)-producing
Escherichia coli
among 3,344 study participants from the German community. Intestinal colonization was detected in 211 persons (6.3%), without significant differences among the different age groups. The majority (95.2%) of isolates harbored CTX-M-type ESBL, with CTX-M-15 (46%) and CTX-M-1 (24.2%) as the most common types. The finding of ESBL producers and one isolate additionally producing carbapenemase OXA-244 indicates a risk of dissemination of resistant bacteria outside the hospitals.
An NF-κB-Based High-Throughput Screen Identifies Piericidins as Inhibitors of the Yersinia pseudotuberculosis Type III Secretion System
Authors: Duncan Miles C. , Wong Weng Ruh , Dupzyk Allison J. , Bray Walter M. , Linington Roger G. , Auerbuch Victoria
Published: December 2013

The type III secretion system (T3SS) is a bacterial appendage used by dozens of Gram-negative pathogens to subvert host defenses and cause disease, making it an ideal target for pathogen-specific antimicrobials. Here, we report the discovery and initial characterization of two related natural products with T3SS-inhibitory activity that were derived from a marine actinobacterium. Bacterial extracts containing piericidin A1 and the piericidin derivative Mer-A 2026B inhibited
Yersinia pseudotuberculosis
from triggering T3SS-dependent activation of the host transcription factor NF-κB in HEK293T cells but were not toxic to mammalian cells. As the
Yersinia
T3SS must be functional in order to trigger NF-κB activation, these data indicate that piericidin A1 and Mer-A 2026B block T3SS function. Consistent with this, purified piericidin A1 and Mer-A 2026B dose-dependently inhibited translocation of the
Y. pseudotuberculosis
T3SS effector protein YopM inside CHO cells. In contrast, neither compound perturbed bacterial growth
in vitro
, indicating that piericidin A1 and Mer-A 2026B do not function as general antibiotics in
Yersinia
. In addition, when
Yersinia
was incubated under T3SS-inducing culture conditions in the absence of host cells, Mer-A 2026B and piericidin A1 inhibited secretion of T3SS cargo as effectively as or better than several previously described T3SS inhibitors, such as MBX-1641 and aurodox. This suggests that Mer-A 2026B and piericidin A1 do not block type III secretion by blocking the bacterium-host cell interaction, but rather inhibit an earlier stage, such as T3SS needle assembly. In summary, the marine-derived natural products Mer-A 2026B and piericidin A1 possess previously uncharacterized activity against the bacterial T3SS.
Development and Bias Assessment of a Method for Targeted Metagenomic Sequencing of Marine Cyanobacteria
Authors: Batmalle Cécilia S. , Chiang Hsin-I , Zhang Kun , Lomas Michael W. , Martiny Adam C.
Published: December 2013

Prochlorococcus
and
Synechococcus
are the most abundant photosynthetic organisms in oligotrophic waters and responsible for a significant percentage of the earth's primary production. Here we developed a method for metagenomic sequencing of sorted
Prochlorococcus
and
Synechococcus
populations using a transposon-based library preparation technique. First, we observed that the cell lysis technique and associated amount of input DNA had an important role in determining the DNA library quality. Second, we found that our transposon-based method provided a more even coverage distribution and matched more sequences of a reference genome than multiple displacement amplification, a commonly used method for metagenomic sequencing. We then demonstrated the method on
Prochlorococcus
and
Synechococcus
field populations from the Sargasso Sea and California Current isolated by flow cytometric sorting and found clear environmentally related differences in ecotype distributions and gene abundances. In addition, we saw a significant correspondence between metagenomic libraries sequenced with our technique and regular sequencing of bulk DNA. Our results show that this targeted method is a viable replacement for regular metagenomic approaches and will be useful for identifying the biogeography and genome content of specific marine cyanobacterial populations.
Microbial Enterotypes, Inferred by the Prevotella-to-Bacteroides Ratio, Remained Stable during a 6-Month Randomized Controlled Diet Intervention with the New Nordic Diet
Authors: Roager Henrik M. , Licht Tine R. , Poulsen Sanne K. , Larsen Thomas M. , Bahl Martin I.
Published: December 2013

It has been suggested that the human gut microbiota can be divided into enterotypes based on the abundance of specific bacterial groups; however, the biological significance and stability of these enterotypes remain unresolved. Here, we demonstrated that subjects (n= 62) 18 to 65 years old with central obesity and components of metabolic syndrome could be grouped into two discrete groups simply by their relative abundance ofPrevotellaspp. divided byBacteroidesspp. (P/Bratio) obtained by quantitative PCR analysis. Furthermore, we showed that these groups remained stable during a 6-month, controlled dietary intervention, where the effect of consuming a diet in accord with the new Nordic diet (NND) recommendations as opposed to consuming the average Danish diet (ADD) on the gut microbiota was investigated. In this study, subjects (with and without stratification according toP/Bratio) did not reveal significant changes in 35 selected bacterial taxa quantified by quantitative PCR (ADD compared to NND) resulting from the dietary interventions. However, we found higher total plasma cholesterol within the high-P/Bgroup than in the low-P/Bgroup after the intervention. We propose that stratification of humans based simply on theirP/Bratio could allow better assessment of possible effects of interventions on the gut microbiota and physiological biomarkers.
Type II Fatty Acid Biosynthesis Is Essential for Plasmodium falciparum Sporozoite Development in the Midgut of Anopheles Mosquitoes
Authors: van Schaijk Ben C. L. , Kumar T. R. Santha , Vos Martijn W. , Richman Adam , van Gemert Geert-Jan , Li Tao , Eappen Abraham G. , Williamson Kim C. , Morahan Belinda J. , Fishbaugher Matt , Kennedy Mark , Camargo Nelly , Khan Shahid M. , Janse Chris J. , Sim Kim Lee , Hoffman Stephen L. , Kappe Stefan H. I. , Sauerwein Robert W. , Fidock David A. , Vaughan Ashley M.
Published: December 2013

The prodigious rate at which malaria parasites proliferate during asexual blood-stage replication, midgut sporozoite production, and intrahepatic development creates a substantial requirement for essential nutrients, including fatty acids that likely are necessary for parasite membrane formation.
Plasmodium
parasites obtain fatty acids either by scavenging from the vertebrate host and mosquito vector or by producing fatty acids
de novo
via the type two fatty acid biosynthesis pathway (FAS-II). Here, we study the FAS-II pathway in
Plasmodium falciparum
, the species responsible for the most lethal form of human malaria. Using antibodies, we find that the FAS-II enzyme FabI is expressed in mosquito midgut oocysts and sporozoites as well as liver-stage parasites but not during the blood stages. As expected, FabI colocalizes with the apicoplast-targeted acyl carrier protein, indicating that FabI functions in the apicoplast. We further analyze the FAS-II pathway in
Plasmodium falciparum
by assessing the functional consequences of deleting
fabI
and
fabB/F
. Targeted deletion or disruption of these genes in
P. falciparum
did not affect asexual blood-stage replication or the generation of midgut oocysts; however, subsequent sporozoite development was abolished. We conclude that the
P. falciparum
FAS-II pathway is essential for sporozoite development within the midgut oocyst. These findings reveal an important distinction from the rodent
Plasmodium
parasites
P. berghei
and
P. yoelii
, where the FAS-II pathway is known to be required for normal parasite progression through the liver stage but is not required for oocyst development in the
Anopheles
mosquito midgut.
Endosymbiotic Gene Transfer in Tertiary Plastid-Containing Dinoflagellates
Authors: Burki Fabien , Imanian Behzad , Hehenberger Elisabeth , Hirakawa Yoshihisa , Maruyama Shinichiro , Keeling Patrick J.
Published: December 2013

Plastid establishment involves the transfer of endosymbiotic genes to the host nucleus, a process known as endosymbiotic gene transfer (EGT). Large amounts of EGT have been shown in several photosynthetic lineages but also in present-day plastid-lacking organisms, supporting the notion that endosymbiotic genes leave a substantial genetic footprint in the host nucleus. Yet the extent of this genetic relocation remains debated, largely because the long period that has passed since most plastids originated has erased many of the clues to how this process unfolded. Among the dinoflagellates, however, the ancestral peridinin-containing plastid has been replaced by tertiary plastids on several more recent occasions, giving us a less ancient window to examine plastid origins. In this study, we evaluated the endosymbiotic contribution to the host genome in two dinoflagellate lineages with tertiary plastids. We generated the first nuclear transcriptome data sets for the “dinotoms,” which harbor diatom-derived plastids, and analyzed these data in combination with the available transcriptomes for kareniaceans, which harbor haptophyte-derived plastids. We found low level of detectable EGT in both dinoflagellate lineages, with only 9 genes and 90 genes of possible tertiary endosymbiotic origin in dinotoms and kareniaceans, respectively, suggesting that tertiary endosymbioses did not heavily impact the host dinoflagellate genomes.
Ght Protein of Neisseria meningitidis Is Involved in the Regulation of Lipopolysaccharide Biosynthesis
Authors: Putker Florian , Grutsch Andreas , Tommassen Jan , Bos Martine P.
Published: December 2013

Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria and is responsible for the barrier function of this membrane. A
ght
mutant of
Neisseria meningitidis
that showed increased sensitivity to hydrophobic toxic compounds, suggesting a breach in this permeability barrier, was previously described. Here, we assessed whether this phenotype was possibly caused by a defect in LPS transport or synthesis. The total amount of LPS appeared to be drastically reduced in a
ght
mutant, but the residual LPS was still detected at the cell surface, suggesting that LPS transport was not impaired. The
ght
mutant was rapidly overgrown by pseudorevertants that produced normal levels of LPS. Genetic analysis of these pseudorevertants revealed that the
lpxC
gene, which encodes a key enzyme in LPS synthesis, was fused to the promoter of the upstream-located
pilE
gene, resulting in severe
lpxC
overexpression. Analysis of
phoA
and
lacZ
gene fusions indicated that Ght is an inner membrane protein with an N-terminal membrane anchor and its bulk located in the cytoplasm, where it could potentially interact with LpxC. Cell fractionation experiments indeed indicated that Ght tethers LpxC to the membrane. We suggest that Ght regulates LPS biosynthesis by affecting the activity of LpxC. Possibly, this mechanism acts in the previously observed feedback inhibition of LPS synthesis that occurs when LPS transport is hampered.
The MiaA tRNA Modification Enzyme Is Necessary for Robust RpoS Expression in Escherichia coli
Authors: Thompson Karl M. , Gottesman Susan
Published: December 2013

The stationary phase/general stress response sigma factor RpoS (σ
S
) is necessary for adaptation and restoration of homeostasis in stationary phase. As a physiological consequence, its levels are tightly regulated at least at two levels. Multiple small regulatory RNA molecules modulate its translation, in a manner that is dependent on the RNA chaperone Hfq and the
rpoS
5′ untranslated region. ClpXP and the RssB adaptor protein degrade RpoS, unless it is protected by an anti-adaptor. We here find that, in addition to these posttranscriptional levels of regulation, tRNA modification also affects the steady-state levels of RpoS. We screened mutants of several RNA modification enzymes for an effect on RpoS expression and identified the
miaA
gene, encoding a tRNA isopentenyltransferase, as necessary for full expression of both an
rpoS750-lacZ
translational fusion and the RpoS protein. This effect is independent of
rpoS
, the regulatory RNAs, and RpoS degradation. RpoD steady-state levels were not significantly different in the absence of MiaA, suggesting that this is an RpoS-specific effect. The
rpoS
coding sequence is significantly enriched for
leu
codons that use MiaA-modified tRNAs, compared to
rpoD
and many other genes. Dependence on MiaA may therefore provide yet another way for RpoS levels to respond to growth conditions.
It's All in the Mind! Or is It? Positive Acupuncture Responses in Patients with Dementia: A Series of Case Reports
Authors: Williams Nicolette , Lawler Duncan , Dilworth Peter
Published: December 2013

Controversy continues over whether or not there is any real effect from acupuncture over and above that of placebo. However, this series of case studies may provide us with evidence from an unlikely source. Anticipation of clinical benefit is a major element of placebo, and clearly cognition is needed to experience this. This raises the question of how much placebo effect is experienced by a patient with dementia. These cases document reliably witnessed responses to acupuncture in patients with impaired cognition, which have been reproducible and maintained. Given the similarity of responses, it could be argued that these reports provide evidence of a ‘real’ effect of acupuncture, and raise the possibility of including patients with dementia in formal studies from which they might routinely be excluded.
Werner's syndrome: incidental finding during pregnancy
Authors: Hurtarte Sandoval A R , Penate Dardón J D , Flores Robles B J , Porres S
Published: December 2013

Werner's syndrome (WS) is a rare autosomal recessive disorder, characterised by skin changes prematurely during adolescence. An unusual case of WS was found in a 27-year-old pregnant woman who presented to the hospital with a history of uncontrolled hypertension at 32 weeks of gestation. All clinical features corresponding to WS (early aging of skin, hair loss, blurred vision and diabetes type 2) appeared to match with the prospective diagnosis, which was confirmed later with genetic testing. The pregnancy became complicated due to oligohydramnios and therefore a caesarean section was carried out in order to preserve the fetus. Despite all implemented efforts, the patient died intraoperative as a result of cardiac arrest and its complications. Successfully, the newborn survived and it was further investigated to exclude this condition.
Streptokinase therapy in the treatment of neonatal obstructive renal candidiasis
Authors: Yeo Kee Thai , Priyadarshi Archana , Bolisetty Srinivas
Published: December 2013

A 6-week-old ex-25-week gestation male infant developed candidal sepsis with subsequent bilateral acute obstructive nephropathy that was not responsive to intravenous antifungal therapy. Bilateral percutaneous nephrotomies were performed and irrigation with fluconazole started. Owing to the persistence of the candidaemia and left renal obstruction, streptokinase was administered through the nephrostomy with eventual resolution of obstruction and improvement in his kidney function. This case report discusses the use of the streptokinase therapy as an adjunct therapy in the clearance of fungal bezoars.
Is previous history a reliable predictor for acute mountain sickness susceptibility? A meta-analysis of diagnostic accuracy
Authors: MacInnis Martin J , Lohse Keith R , Strong Jenny K , Koehle Michael S
Published: December 2013

Purpose

The goal of this meta-analysis was to determine the clinical utility of acute mountain sickness (AMS) history to predict future incidents of AMS.

Method

17 studies (n=7921 participants) were included following a systematic review of the literature. A bivariate random-effects model was used to calculate the summary sensitivity and specificity of the diagnostic test, and moderator variables were tested to explain the heterogeneity across studies. The Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) method was used to assess concerns for bias and applicability for the included studies.

Results

The history of AMS had a low diagnostic accuracy for the prediction of future AMS incidents: the summary sensitivity was 0.50 (95% CI (0.40 to 0.59)) and the summary specificity was 0.72 (95% CI (0.66 to 0.78)). There was significant heterogeneity in the sensitivity and specificity across studies, which we modelled using moderator analysis. Studies that restricted the use of acetazolamide and dexamethasone had not only a higher sensitivity (0.66) relative to those that did not (0.44; p=0.03) but also an increased false-positive rate (0.39 vs 0.23, p=0.03). The QUADAS-2 analysis showed that AMS histories were insufficiently detailed, and few studies controlled for prophylactic medication use or recent altitude exposure, leading to high risks of bias and concerns for applicability.

Conclusions

The use of AMS history to guide prophylactic strategies for high-altitude ascent is not supported by the literature; however, the low sensitivity and specificity of this diagnostic test could reflect the quality of the available studies. Ensuring that the characteristics of the history and future ascents are similar may improve the clinical utility of AMS history.
Using accelerometers to measure physical activity in large-scale epidemiological studies: issues and challenges
Authors: Lee I-Min , Shiroma Eric J
Published: December 2013

Background

The current guidelines for aerobic activity require that adults carry out ≥150 min/week of moderate-intensity physical activity, with a large body of epidemiological evidence showing this level of activity to decrease the incidence of many chronic diseases. Less is known about whether light-intensity activities also have such benefits, and whether sedentary behaviour is an independent predictor of increased risks of these chronic diseases, as imprecise assessments of these behaviours and cross-sectional study designs have limited knowledge to date.

Methods

Recent technological advances in assessment methods have made the use of movement sensors, such as the accelerometer, feasible for use in longitudinal, large-scale epidemiological studies. Several such studies are collecting sensor-assessed, objective measures of physical activity with the aim of relating these to the development of clinical endpoints. This is a relatively new area of research; thus, in this article, we use the Women's Health Study (WHS) as a case study to illustrate the challenges related to data collection, data processing and analyses of the vast amount of data collected.

Results

The WHS plans to collect 7 days of accelerometer-assessed physical activity and sedentary behaviour in ∼18 000 women aged ≥62 years. Several logistical challenges exist in collecting data; nonetheless, as of 31 August 2013, 11 590 women have already provided some data. In addition, the WHS experience on data reduction and data analyses can help inform other similar large-scale epidemiological studies.

Conclusions

Important data on the health effects of light-intensity activity and sedentary behaviour will emerge from large-scale epidemiological studies collecting objective assessments of these behaviours.
Tentorial dural arteriovenous fistula manifesting as contralateral trigeminal neuralgia: resolution after transarterial Onyx embolization
Authors: Lu Xiaojian , Qin Xuanfeng , Ni Lanchun , Chen Jian , Xu Feng
Published: December 2013

Tentorial dural arteriovenous fistula (DAVF) as a cause of trigeminal neuralgia is extremely rare. Although less than 10 cases have been reported in the literature, all cases presented with ipsilateral trigeminal neuralgia. Here we report a unique case of tentorial DAVF manifesting as contralateral trigeminal neuralgia. A 58-year-old man presented with right-sided trigeminal neuralgia. Cerebral angiography revealed a left tentorial DAVF and the MR imaging demonstrated a variceal venous dilatation occupying the left lateral pontine cistern and multiple venous flow voids adjacent to the right trigeminal nerve root entry zone. Transarterial Onyx embolization resulted in near complete obliteration of the fistula with immediate resolution of facial pain. The patient remains symptom free and without evidence of recurrence during 9 months of follow-up. Transarterial Onyx embolization may be an effective treatment modality for such an usual case.
Relationship between exercise behavior, cardiorespiratory fitness, and cognitive function in early breast cancer patients treated with doxorubicin-containing chemotherapy: a pilot study
Authors: Crowgey Theresa , Peters Katherine B. , Hornsby Whitney E. , Lane Amy , McSherry Frances , Herndon James E. , West Miranda J. , Williams Christina L. , Jones Lee W.
Published: December 2013

The purpose of this study was to examine the relationship between self-reported exercise behavior, cardiorespiratory fitness (CRF), and cognitive function in early breast cancer patients. Thirty-seven breast cancer patients following completion of chemotherapy (median 16 months) and 14 controls were studied. Cognitive function was assessed using the Central Nervous System (CNS) Vital Signs software (CNS Vital Signs, LLC, Morrisville, N.C., USA), a computerized test battery consisting of 9 cognitive subtests. Exercise behavior was evaluated using the Godin Leisure Time Exercise Questionnaire, and CRF was assessed via a cardiopulmonary exercise test to assess peak oxygen consumption. Patients’ mean total exercise was 184 ± 141 min·week−1 compared with 442 ± 315 min·week−1 in controls (p < 0.001). Significantly fewer patients (32%) were meeting exercise guidelines (i.e., ≥150 min of moderate-intensity or vigorous exercise per week) compared with 57% of controls (p = 0.014). Patients’ peak oxygen consumption averaged 23.5 ± 6.3 mL·kg–1·min−1 compared with 30.6 ± 7.0 mL·kg–1·min−1 in controls (p < 0.01). Scores on the cognitive subdomains were generally lower in patients compared with controls, although only the difference in verbal memory was significant (unadjusted p = 0.041). In patients, weak to moderate correlations were indicated between exercise, peak oxygen consumption, and the majority of cognitive subdomain scores; however, there was a significant positive correlation between exercise and visual memory (r = 0.47, p = 0.004). In conclusion, breast cancer patients following the completion of primary adjuvant chemotherapy exhibit, in general, worse cognitive performance than healthy women from the general population, and such performance may be related to their level of exercise behavior.
PHYSICS BASED ANALYTICAL MODELING OF NANOSCALE MULTIGATE MOSFETs
Authors: FJELDLY TOR A. , MONGA UDIT
Published: December 2013

Various physics based modeling schemes for multigate MOSFETs are presented. In all cases, the models are derived from an analysis of the device body electrostatics in terms of two- or three-dimensional Laplace's and Poisson's equations, where short-channel and scaling effects are implicitly accounted for. Thus a comprehensive modeling framework is derived for the subthreshold electrostatics of double-gate MOSFETs based on a conformal mapping analysis of the potential distribution in the device body arising from the inter-electrode capacitive coupling. This technique is also applied to the circular gate-all-around MOSFET by utilizing the symmetry properties of this device. For both these devices, the modeling is extended to include the strong inversion regime by a self-consistent procedure that simultaneously allows the calculation of the quasi-Fermi potential distribution, the drain current, and the intrinsic capacitances. In an alternative modeling framework, covering a wide range of multigate devices in a unified manner, the potential distribution is derived from a select set of isomorphic trial functions that reflect the geometry and symmetry properties of the devices. Modeling parameters used are self-consistently determined by imposing boundary conditions associated with Laplace's or Poisson's equation. Finally, the effects of quantum mechanical confinement are discussed for ultra thin body devices. The results of the modeling are in excellent agreement with numerical simulations.
A polynomial-delay algorithm for enumerating approximate solutions to the interval constrained coloring problem
Authors: Canzar Stefan , Elbassioni Khaled , Mestre Julián
Published: December 2013

We study the interval constrained coloring problem, a combinatorial problem arising in the interpretation of data on protein structure emanating from experiments based on hydrogen/deuterium exchange and mass spectrometry. The problem captures the challenging task of increasing the spatial resolution of experimental data in order to get a better picture of the protein structure. Since solutions proposed by any algorithmic framework have to ultimately be verified by biochemists, it is important to provide not just a single solution, but a valuable set of candidate solutions. Our contribution is a polynomial-delay, polynomial-space algorithm for enumerating all exact solutions plus further approximate solutions, which are guaranteed to be within an absolute error of two of the optimum within fragments of the protein, that is, within sets of consecutive residues. Our experiments indicate that the quality of the approximate solutions is comparable to the optimal ones in terms of deviation from the underlying true solution. In addition, the experiments also confirm the effectiveness of the method in reducing the delay between two consecutive solutions considerably, compared to what it takes an integer programming solver to produce the next exact solution.
Optimal selection and sorting via dynamic programming
Authors: Hofri Micha
Published: December 2013

We show how to find optimal algorithms for the selection of one or more order statistics over a small set of numbers, and as an extreme case, complete sorting. The criterion is using the smallest number of comparisons; separate derivations are performed for minimization on the average (over all permutations) or in the worst case. When the computational process establishes the optimal values, it also generates C-language functions that implement policies which achieve those optimal values. The search for the algorithms is driven by a Markov decision process, and the program provides the optimality proof as well.
Perinatal Exposure to Insecticide Methamidophos Suppressed Production of Proinflammatory Cytokines Responding to Virus Infection in Lung Tissues in Mice
Authors: Watanabe Wataru , Yoshida Hiroki , Hirose Akihiko , Akashi Toshi , Takeshita Tomomi , Kuroki Nao , Shibata Asami , Hongo Satoko , Hashiguchi Seiko , Konno Katsuhiko , Kurokawa Masahiko
Published: December 2013

Methamidophos, a representative organophosphate insecticide, is regulated because of its severe neurotoxicity, but it is suspected of contaminating agricultural foods in many countries due to illicit use. To reveal unknown effects of methamidophos on human health, we evaluated the developmental immunotoxicity of methamidophos using a respiratory syncytial virus (RSV) infection mouse model. Pregnant mice were exposed to methamidophos (10 or 20 ppm) in their drinking water from gestation day 10 to weaning on postnatal day 21. Offsprings born to these dams were intranasally infected with RSV. The levels of interleukin-6 (IL-6) and interferon-gamma in the bronchoalveolar lavage fluids after infection were significantly decreased in offspring mice exposed to methamidophos. Treatment with methamidophos did not affect the pulmonary viral titers but suppressed moderately the inflammation of lung tissues of RSV-infected offspring, histopathologically. DNA microarray analysis revealed that gene expression of the cytokines in the lungs of offspring mice exposed to 20 ppm of methamidophos was apparently suppressed compared with the control. Methamidophos did not suppress IL-6 production in RSV-infected J774.1 cell cultures. Thus, exposure of the mother to methamidophos during pregnancy and nursing was suggested to cause an irregular immune response in the lung tissues in the offspring mice.
Renal Anemia Control in Lithuania: Influence of Local Conditions and Local Guidelines
Authors: Ziginskiene Edita , Kuzminskis Vytautas , Petruliene Kristina , Vaiciuniene Ruta , Stankuviene Asta , Bumblyte Inga Arune
Published: December 2013

Erythropoietin stimulating agents had a long haul in Lithuania—we had no epoetin till 1994 and there was no intravenous iron in 2001–2004. The aim of this study was to assess the changes of renal anemia control in hemodialysis patients from early independence of Lithuania till nowadays and to evaluate the link of anemia with hospitalization rates and survival and hemoglobin variability in association with mortality. In December of each year since 1996 all hemodialysis centers have been visited and data has been collected using special questionnaires. The history of renal anemia control in Lithuania was complicated; however, a significant improvement was achieved: 54.7% of hemodialysis patients reached the target hemoglobin; all patients have a possibility of treatment with epoetin and intravenous iron. The involuntary experiment with an intravenous iron occurred in Lithuania because of economic reasons and confirmed the significant role of intravenous iron in the management of renal anemia. Hemoglobin below 100 g/L was associated with a 2.5‐fold increase in relative risk of death and 1.7‐fold increase in relative risk of hospitalization in Lithuanian hemodialysis patients. Although hemoglobin variability was common in Lithuanian hemodialysis patients, we did not find the association between hemoglobin variability and all‐cause mortality in our study.