bluuebunny/crossref_metadata_2025 huggingface dataset:
An Origami Inspired Additive Manufacturing Process for Building Thin-Shell Structures
Authors: Deng Dongping , Chen Yong
Published: April 2014

Additive manufacturing (AM) process is widely used in fabricating three-dimensional (3D) models with complex internal features due to its flexibility and fast building speed. Inspired by the recent development of origami structures, we investigate a super-fast AM process for fabricating prototype models of hollow shapes. By combining the origami design and the additive manufacturing technology, a new fabrication process named Assembled Additive Manufacturing (AAM) is developed. A folding technique is used either during or after the layer-based fabrication process. By turning a 3D structure into a foldable two-dimensional (2D) structure, the fabrication speed is dramatically increased due to the decreased number of layers that is required in the building process. Detailed procedures of the AAM process such as unfolding algorithms of an input model, foldable structure design and folding mechanism are introduced in the paper. Experimental tests are also presented to illustrate the effective and efficiency of the AAM process.
Effect of EDM Process Parameters for Burr Removal of Drilled Holes of Inconel-718
Authors: Dabade Uday A.
Published: April 2014

Most of the components used in automobile and aerospace industries are replaced by advanced materials such as Metal Matrix Components (MMCs) and Inconel. So in this area, drilling is most popular method used for joining, bolting and riveting purpose. Inconel-718 is a high strength, temperature resistant (HSTR) nickel -based super alloy. It is extensively used in aerospace applications, such as gas turbines, rocket motors, and spacecraft as well as in nuclear reactors, pumps and tooling. Inconel-718 is difficult to machine, because of its poor thermal properties, high toughness, high hardness, and high work hardening rate. Therefore, many researchers have tried for an alternative source by many conventional and nonconventional machining processes. Electro discharge machining (EDM) is widely used non conventional machining process for such materials. Hence, in this paper some efforts are taken to investigate the effect of different EDM process parameters such as current, dielectric flow rate and pulse on time on the tool wear rate (TWR) and grading of deburred holes by visual inspection for burr removal in drilled holes of Inconel-718 material. In this study burr removal operation of drilled holes via EDM process is carried out. Two types of electrode materials such as Aluminum and Brass with cylindrical taper geometry at tip is used. The experiments are performed using Taguchi method of design of experiment and L27 orthogonal array. The results indicate that only current is most significant parameter affecting for tool wear rate (TWR) as well as grading of drilled holes by visual inspection. Secondarily, SEM photographs of deburred holes indicate that effective burr removal operation using Brass electrode compared to Aluminium provides better solution for Inconel-718 material.
Characterization and Optimization of Rotational Friction Welding for Small Stainless Steel Tubes
Authors: Adams Alex , Miller David
Published: April 2014

Rotational friction welding is a common joining process used to join cylindrical metal components. Typically, one piece is rotated and a secondary piece is held rigid. The two samples are then forced together in a controlled manner, and the resulting friction generates enough heat to weld the two pieces. This process was characterized and optimized for 304 stainless steel tubes with a .317 cm (.125 in) outer diameter and .14 cm (.055 in) inner diameter. The goal was to characterize and optimize parameters around a weld with no leak, strong ultimate tensile strength, and proper through-hole integrity. Also, solid bars were welded to some tubes to analyze a capped system. Key parameters to the process that were monitored and/or controlled include rotational speed, applied force, temperature, duration, and material upset. Often times the applied force is divided into two steps. A lower force is applied during heating (friction force), and a larger force is applied once rotation stops (forging force). The material upset, maximum temperature, and forging fore were the primary controlling variables in this study. Other parameters were held constant. A testing setup was built to analyze these factors. Modifications were made to a three axis mill to perform friction welding in a controlled environment. Then, tests were run to understand the effects each parameter had on weld quality. Welds with an upset greater than .1 cm held a pressure at a much higher success rate than welds with lower upsets. In general, the forging force was shown to have a large positive impact on ultimate tensile force. The integrity of the through-hole was compromised in many of the tube to tube tests. Several welds were post-drilled to recreate the through-hole. Tests with this done held a pressure 66.67% of the time. It was found that successful welding can be accomplished with this process, and different adjustments to testing procedures can maximize different qualities in the weld.
Experimental Investigation of Manufacturing Possibility of Multilayered Ni-ZrO2 System Functionally Graded Material by Powder Injection Molding
Authors: Suzuki Ryosuke , Matsubara Masaaki , Maruyama Takumi , Sakamoto Kenji , Arakawa Kazuyuki
Published: April 2014

Manufacturing possibility was experimentally investigated for a bulk multilayered Ni-ZrO2 system functionally graded material (FGM) by powder injection molding. Ni-ZrO2 system FGMs with various composition gradients and layer numbers were manufactured from compounds used in powder injection molding methods. Compounds with various chemical compositions were obtained by kneading Ni and ZrO2 powders with a polymeric binder. A compound was filled into a mold and heated to the softening temperature of binder. A compact was obtained by compressing at the softening temperature. Some compacts were stacked in the mold and compressed at the softening temperature again. The multilayered compact was heated to near the melting point of Ni. The FGM with little flaws was obtained for high composition gradient in ZrO2 rich side. However, calculated maximum thermal stress of the FGM was higher than that of the linear composition gradient. The maximum thermal stress was compressive stress and occurred in ZrO2 rich side. The compressive strength of a ceramics is higher than that of the tensile strength. Thus, the thermal compressive stress in ZrO2 rich side would be effective to manufacture a bulk multilayered Ni-ZrO2 system FGM by powder injection molding.
The Design and Fabrication of an Electrochemical Machining Test Apparatus
Authors: Bingham Bruce C. , Atanasov Atanas A. , Parmigiani John P.
Published: April 2014

The removal of residual casting material from gating has traditionally been performed by abrasive grinding techniques. However, high amounts of belt wear can occur when working with high strength alloys, especially those typically seen in the aerospace industry. An alternative machining process called electrochemical machining (ECM) uses electrolysis to precisely remove material at high rates. ECM has many advantages over conventional grinding: no tool wear, no induced mechanical or thermal stresses, and high removal rates independent of material hardness or strength. The industrial application of ECM to residual casting material removal can potentially realize large cost savings and decreased component processing time by eliminating belt wear and increasing material removal rates. The approach taken in this work is the design and fabrication of a laboratory apparatus for the purpose of testing the ECM of casting material. Commercial ECM machines, while more powerful, can be excessively large and cost prohibitive when performing an initial feasibility study. Many times these commercial machines are calibrated to mass produce a specific part, and do not have the level of variability desired for laboratory experimentation. The test apparatus presented provides a robust and relatively low cost method of investigating the applicability of ECM to this purpose. The device is comprised of an electrolyte filtration and delivery system, a stable machining enclosure, and a single axis computer controlled tool. The ECM variables that can be adjusted include electrolyte temperature, mass flow rate, applied voltage, tool feed rate, and electrode gap. Process data from these variables is collected via multiple sensors in the machine and provides real-time feedback to users. A universal tool connection and workpiece fixture allows for different experimental setups to be easily tested. From experimentation with this test apparatus, it will be possible to identify optimum methods for the ECM of these residual casting artifacts.
Design of a Nozzle for the Production of Metal Powder via Gas Atomization
Authors: Sofuoglu Mehmet Alper , Erbas Murat , Uslan Ibrahim , Biyikoglu Atilla
Published: April 2014

In this study, a nozzle has been designed in order to produce metal powder via the method of gas atomization. The design has been performed in two stages. At the first stage of design, the size and geometry of the nozzle have been determined using empirical relations as a pre-design. At the second stage, a parametrical analysis has been done using a CFD code. As a parametrical study, the effects of nozzle exit angle, throat distance and protrusion length on pressure and flow velocity at the nozzle exit are investigated with the numerical model. Appropriate values for the investigated parameters have been determined to get maximum pressure in vacuum condition at the tip of the melt. The nozzle has been designed based on the determined parameters.
Heart-Rate Variability and Training-Intensity Distribution in Elite Rowers
Authors: Plews Daniel J. , Laursen Paul B. , Kilding Andrew E. , Buchheit Martin
Published: April 2014

Purpose:

Elite endurance athletes may train in a polarized fashion, such that their training-intensity distribution preserves autonomic balance. However, field data supporting this are limited.

Methods:

The authors examined the relationship between heart-rate variability and training-intensity distribution in 9 elite rowers during the 26-wk build-up to the 2012 Olympic Games (2 won gold and 2 won bronze medals). Weekly averaged log-transformed square root of the mean sum of the squared differences between R-R intervals (Ln rMSSD) was examined, with respect to changes in total training time (TTT) and training time below the first lactate threshold (>LT1), above the second lactate threshold (LT2), and between LT1 and LT2 (LT1–LT2).

Results:

After substantial increases in training time in a particular training zone or load, standardized changes in Ln rMSSD were +0.13 (unclear) for TTT, +0.20 (51% chance increase) for time >LT1, –0.02 (trivial) for time LT1–LT2, and –0.20 (53% chance decrease) for time >LT2. Correlations (±90% confidence limits) for Ln rMSSD were small vs TTT (r = .37 ± .80), moderate vs time >LT1 (r = .43 ± .10), unclear vs LT1–LT2 (r = .01 ± .17), and small vs >LT2 (r = –.22 ± .50).

Conclusion:

These data provide supportive rationale for the polarized model of training, showing that training phases with increased time spent at high intensity suppress parasympathetic activity, while low-intensity training preserves and increases it. As such, periodized low-intensity training may be beneficial for optimal training programming.
Relationship of Falls and Fear of Falling to Activity Limitations and Physical Inactivity in Parkinson’s Disease
Authors: Bryant Mon S. , Rintala Diana H. , Hou Jyh-Gong , Protas Elizabeth J.
Published: April 2014

Aim:

To investigate the relationships between falls, fear of falling, and activity limitations in individuals with Parkinson’s disease (PD).

Design/methods:

Cross-sectional study of individuals with mild to moderate PD (N = 83). Associations among demographic data, fall frequency, disease severity, motor impairment, ability to perform activities of daily living (ADL), Activities Balance Confidence Scale, Iowa Fatigue Scale, Comorbidity Index, and Physical Activity Scale for Elders were studied.

Results:

Frequent fallers had more ADL limitations than nonfallers (p < .001) and rare fallers (p = .004). Frequent fallers reported a lower percentage of ability to perform ADL than nonfallers (p = .003). Frequent fallers and rare fallers were less physically active than nonfallers (p = .015 and p = .040, respectively). Frequent fallers and rare fallers reported a higher level of fear of falling than nonfallers (p = .031 and p = .009, respectively).

Conclusions:

Falls and fear of falling were associated with more ADL limitations and less physical activity after adjusting for physical impairments.
Validity and Reliability of Maximal-Strength Assessment of Knee Flexors and Extensors Using Elastic Bands
Authors: Guex Kenny , Daucourt Chantal , Borloz Stéphane
Published: April 2014

Context:

In the field of sport rehabilitation, an easy, valid, and reliable assessment of maximal strength is crucial for efficient muscle rehabilitation. Classically, it is performed on fitness equipment that is not necessary available in the field. Thera-Band has developed elastic bands with different resistances depending on the color of the band and on the percentage of its stretch. This may allow testing maximal strength.

Objective:

To determine validity and reliability of maximal-strength assessment of knee flexors and extensors using elastic bands.

Design:

Reliability and validity study.

Participants:

22 healthy participants (31.3 ± 7.0 y, 175.5 ± 8.5 cm, 70.7 ± 12.9 kg).

Intervention:

Participants performed 2 maximal-strength assessments, separated by 7 d, of the knee flexors and extensors using elastic bands. After the 2nd trial, a maximal concentric isokinetic test at 60°/s was performed.

Main Outcome Measures:

Correlations between 1-repetition maximum using elastic bands and peak torque on an isokinetic dynamometer were used to determine the validity of the proposed method, while ICC, CV, and SEM were used to determine reliability between the 1st and 2nd trials.

Results:

The validity of the proposed method was found to be very high (r = .93 for both knee flexors and extensors). The relative reliability was found to be very high (ICC = .98 and .99 for knee flexors and extensors, respectively), while absolute reliability was also very satisfying (CV = 3.44% and 2.33%; SEM = 1.70 and 2.16 kg for knee flexors and extensors, respectively).

Conclusions:

Thera-Band is a valid and reliable alternative to the use of fitness equipment to test maximal strength of the knee flexors and extensors in healthy subjects. The ease of use, accessibility, and low cost of elastic bands should allow regular assessment during the rehabilitation process.
Geophysical and Geochemical Evidence for Deep Temperature Variations Beneath Mid-Ocean Ridges
Authors: Dalton Colleen A. , Langmuir Charles H. , Gale Allison
Published: April 2014

Deep, Driving Temperatures

Convection in Earth's mantle is largely controlled by the physical properties of the mantle such as density and viscosity. Because these factors are influenced by both temperature and composition, it has been difficult to ascribe one as the primary control over mantle convection or explain the long-wavelength features associated with mid-ocean ridges. Examining correlations between a global seismic velocity model with constraints on the depth and geochemical signature of mid-ocean ridges,

Dalton
et al.

(p.
80
; see the Perspective by

Kelley

) suggest that large temperature variations extending into the upper mantle explain most of the geophysical and geochemical observations. Moreover, the analysis provides support for deeply rooted mantle plumes as the source of hot spot volcanism.
Neuronal Control of
Drosophila
Walking Direction
Authors: Bidaye Salil S. , Machacek Christian , Wu Yang , Dickson Barry J.
Published: April 2014

Backward or Forward

Although land animals generally walk forward, they readily switch to walking backward if they sense an obstruction or danger in the path ahead. Such a switch is likely to involve a neural signal sent from the brain down to local motor circuits, instructing these motor circuits to alter the phase at which specific leg muscles are activated.

Bidaye
et al.

(p.
97
; see the Perspective by

Mann

) identified such a neuron in
Drosophila
, which they call MDN (moonwalker descending neuron). Blocking synaptic transmission from MDN inhibited backward walking, and conversely artificially activating MDN caused flies to walk backward.
Soft Microfluidic Assemblies of Sensors, Circuits, and Radios for the Skin
Authors: Xu Sheng , Zhang Yihui , Jia Lin , Mathewson Kyle E. , Jang Kyung-In , Kim Jeonghyun , Fu Haoran , Huang Xian , Chava Pranav , Wang Renhan , Bhole Sanat , Wang Lizhe , Na Yoon Joo , Guan Yue , Flavin Matthew , Han Zheshen , Huang Yonggang , Rogers John A.
Published: April 2014

Wearable Monitors

Advances in microelectronics have yielded high-quality devices that allow for intensive signal collection or transmission.

S. Xu
et al.

(p.
70
) show how to make a soft wearable system that is constructed like a stretchable circuit board, where the electronic components are bridged electrically by thin, meandering conducting traces that float in a highly visco-elastic polymer. A complete soft circuit capable of multisignal physiological sensing on skin was created, with potential for use in health monitoring or neonatal care.
A CO
2
Cloak for the Cyanide Dagger
Authors: Alabugin Igor , Mohamed Rana K.
Published: April 2014

The fleeting stability of the cyanoformate ion formed from CO
2
and cyanide has implications for plant enzymology and CO
2
sequestration.

[Also see Report by

Murphy
et al.

]
The Adapter: Rachel Brewster
Authors: Couzin-Frankel Jennifer
Published: April 2014

Her funding tight, a biologist adapts her work on early brain development as she strives to keep training young scientists.
Performance of the Architect EBV Antibody Panel for Determination of Epstein-Barr Virus Infection Stage in Immunocompetent Adolescents and Young Adults with Clinical Suspicion of Infectious Mononucleosis
Authors: Guerrero-Ramos Alvaro , Patel Mauli , Kadakia Kinjal , Haque Tanzina
Published: April 2014

The Architect EBV antibody panel is a new chemiluminescence immunoassay system used to determine the stage of Epstein-Barr virus (EBV) infection based on the detection of IgM and IgG antibodies to viral capsid antigen (VCA) and IgG antibodies against Epstein-Barr nuclear antigen 1 (EBNA-1). We evaluated its diagnostic accuracy in immunocompetent adolescents and young adults with clinical suspicion of infectious mononucleosis (IM) using the RecomLine EBV IgM and IgG immunoblots as the reference standard. In addition, the use of the antibody panel in a sequential testing algorithm based on initial EBNA-1 IgG analysis was assessed for cost-effectiveness. Finally, we investigated the degree of cross-reactivity of the VCA IgM marker during other primary viral infections that may present with an EBV IM-like picture. High sensitivity (98.3% [95% confidence interval {CI}, 90.7 to 99.7%]) and specificity (94.2% [95% CI, 87.9 to 97.8%]) were found after testing 162 precharacterized archived serum samples. There was perfect agreement between the use of the antibody panel in sequential and parallel testing algorithms, but substantial cost savings (23%) were obtained with the sequential strategy. A high rate of reactive VCA IgM results was found in primary cytomegalovirus (CMV) infections (60.7%). In summary, the Architect EBV antibody panel performs satisfactorily in the investigation of EBV IM in immunocompetent adolescents and young adults, and the application of an EBNA-1 IgG-based sequential testing algorithm is cost-effective in this diagnostic setting. Concomitant testing for CMV is strongly recommended to aid in the interpretation of EBV serological patterns.
Combining Parasite Lactate Dehydrogenase-Based and Histidine-Rich Protein 2-Based Rapid Tests To Improve Specificity for Diagnosis of Malaria Due to Plasmodium knowlesi and Other Plasmodium Species in Sabah, Malaysia
Authors: Grigg Matthew J. , William Timothy , Barber Bridget E. , Parameswaran Uma , Bird Elspeth , Piera Kim , Aziz Ammar , Dhanaraj Prabakaran , Yeo Tsin W. , Anstey Nicholas M.
Published: April 2014

Plasmodium knowlesi
causes severe and fatal malaria in Malaysia. Microscopic misdiagnosis is common and may delay appropriate treatment.
P. knowlesi
can cross-react with “species-specific” parasite lactate dehydrogenase (pLDH) monoclonal antibodies used in rapid diagnostic tests (RDTs) to detect
P. falciparum
and
P. vivax
. At one tertiary-care hospital and two district hospitals in Sabah, we prospectively evaluated two combination RDTs for malaria diagnosis by using both a pan-
Plasmodium
-pLDH (pan-pLDH)/
P. falciparum
-specific-pLDH (
Pf
-pLDH) RDT (OptiMAL-IT) and a non-
P. falciparum
VOM-pLDH/
Pf
-HRP2 RDT (CareStart). Differential cross-reactivity among these combinations was hypothesized to differentiate
P. knowlesi
from other
Plasmodium
monoinfections. Among 323 patients with PCR-confirmed
P. knowlesi
(
n
= 193),
P. falciparum
(
n
= 93), and
P. vivax
(
n
= 37) monoinfections, the VOM-pLDH individual component had the highest sensitivity for nonsevere (35%; 95% confidence interval [CI], 27 to 43%) and severe (92%; CI, 81 to 100%)
P. knowlesi
malaria. CareStart demonstrated a
P. knowlesi
sensitivity of 42% (CI, 34 to 49%) and specificity of 74% (CI, 65 to 82%), a
P. vivax
sensitivity of 83% (CI, 66 to 93%) and specificity of 71% (CI, 65 to 76%), and a
P. falciparum
sensitivity of 97% (CI, 90 to 99%) and specificity of 99% (CI, 97 to 100%). OptiMAL-IT demonstrated a
P. knowlesi
sensitivity of 32% (CI, 25 to 39%) and specificity of 21% (CI, 15 to 29%), a
P. vivax
sensitivity of 60% (CI, 42 to 75%) and specificity of 97% (CI, 94 to 99%), and a
P. falciparum
sensitivity of 82% (CI, 72 to 89%) and specificity of 39% (CI, 33 to 46%). The combination of CareStart plus OptiMAL-IT for
P. knowlesi
using predefined criteria gave a sensitivity of 25% (CI, 19 to 32%) and specificity of 97% (CI, 92 to 99%). Combining two RDT combinations was highly specific for
P. knowlesi
malaria diagnosis; however, sensitivity was poor. The specificity of pLDH RDTs was decreased for
P. vivax
and
P. falciparum
because of
P. knowlesi
cross-reactivity and cautions against their use alone in areas where
P. knowlesi
malaria is endemic. Sensitive
P. knowlesi
-specific RDTs and/or alternative molecular diagnostic tools are needed in areas where
P. knowlesi
malaria is endemic.
Sequence-Level and Dual-Phase Identification of Salmonella Flagellum Antigens by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Authors: Cheng Keding , Sloan Angela , Meakin Julie , McCorrister Stuart , Jerome Morganne , Westmacott Garrett , Drebot Mike , Nadon Celine , Knox J. David , Wang Gehua
Published: April 2014

Forty-three reference strains involving the 24 most common serovars of
Salmonella enterica
were examined by using a mass spectrometry-based H antigen typing platform (MS-H). The results indicate that MS-H can be used as a sensitive, rapid, and straightforward approach for the typing of
Salmonella
flagella at the molecular level without antiserum and phase inversion.
Detection of Antibodies to the Feline Leukemia Virus (FeLV) Transmembrane Protein p15E: an Alternative Approach for Serological FeLV Detection Based on Antibodies to p15E
Authors: Boenzli Eva , Hadorn Maik , Hartnack Sonja , Huder Jon , Hofmann-Lehmann Regina , Lutz Hans
Published: April 2014

The aim of this report was to investigate whether the diagnosis of feline leukemia virus (FeLV) infection by serology might be feasible and useful. Among the various viral proteins, the FeLV env-gene product (SU) and the envelope transmembrane protein p15E were considered promising candidates for the serological diagnosis of FeLV infection. Thus, we evaluated p15E and three other FeLV antigens, namely, a recombinant env-gene product, whole FeLV, and a short peptide from the FeLV transmembrane protein, for their potential to detect FeLV infection. To evaluate possible exposure of cats to FeLV, we tested serum and plasma samples from experimentally and naturally infected and vaccinated cats for the presence of antibodies to these antigens by enzyme-linked immunosorbent assays (ELISAs). The serological results were compared with the p27 and proviral real-time PCR results. We found that p15E displayed a diagnostic sensitivity of 95.7% and a specificity of 100% in experimentally infected cats. In naturally infected cats, p15E showed a diagnostic sensitivity of 77.1% and a specificity of 85.6%. Vaccinated cats displayed minimal antibody levels to p15E, suggesting that anti-p15E antibodies indicate infection rather than vaccination. The other antigens turned out to be too unspecific. The lower specificity in cats exposed to FeLV under field conditions may be explained by the fact that some cats become infected and seroconvert in the absence of detectable viral nucleic acids in plasma. We conclude that p15E serology may become a valuable tool for diagnosing FeLV infection; in some cases, it may replace PCR.
ROCK1 and LIM Kinase Modulate Retrovirus Particle Release and Cell-Cell Transmission Events
Authors: Wen Xiaoyun , Ding Lingmei , Wang Jaang-Jiun , Qi Mingli , Hammonds Jason , Chu Hin , Chen Xuemin , Hunter Eric , Spearman Paul
Published: April 2014

The assembly and release of retroviruses from the host cells require dynamic interactions between viral structural proteins and a variety of cellular factors. It has been long speculated that the actin cytoskeleton is involved in retrovirus production, and actin and actin-related proteins are enriched in HIV-1 virions. However, the specific role of actin in retrovirus assembly and release remains unknown. Here we identified LIM kinase 1 (LIMK1) as a cellular factor regulating HIV-1 and Mason-Pfizer monkey virus (M-PMV) particle release. Depletion of LIMK1 reduced not only particle output but also virus cell-cell transmission and was rescued by LIMK1 replenishment. Depletion of the upstream LIMK1 regulator ROCK1 inhibited particle release, as did a competitive peptide inhibitor of LIMK1 activity that prevented cofilin phosphorylation. Disruption of either ROCK1 or LIMK1 led to enhanced particle accumulation on the plasma membrane as revealed by total internal reflection fluorescence microscopy (TIRFM). Electron microscopy demonstrated a block to particle release, with clusters of fully mature particles on the surface of the cells. Our studies support a model in which ROCK1- and LIMK1-regulated phosphorylation of cofilin and subsequent local disruption of dynamic actin turnover play a role in retrovirus release from host cells and in cell-cell transmission events.

IMPORTANCE
Viruses often interact with the cellular cytoskeletal machinery in order to deliver their components to the site of assembly and budding. This study indicates that a key regulator of actin dynamics at the plasma membrane, LIM kinase, is important for the release of viral particles for HIV as well as for particle release by a distantly related retrovirus, Mason-Pfizer monkey virus. Moreover, disruption of LIM kinase greatly diminished the spread of HIV from cell to cell. These findings suggest that LIM kinase and its dynamic modulation of the actin cytoskeleton in the cell may be an important host factor for the production, release, and transmission of retroviruses.
Efficient Norovirus and Reovirus Replication in the Mouse Intestine Requires Microfold (M) Cells
Authors: Gonzalez-Hernandez Mariam B. , Liu Thomas , Payne Hilary C. , Stencel-Baerenwald Jennifer E. , Ikizler Mine , Yagita Hideo , Dermody Terence S. , Williams Ifor R. , Wobus Christiane E.
Published: April 2014

Microfold (M) cells are specialized intestinal epithelial cells that internalize particulate antigens and aid in the establishment of immune responses to enteric pathogens. M cells have also been suggested as a portal for pathogen entry into the host. While virus particles have been observed in M cells, it is not known whether viruses use M cells to initiate a productive infection. Noroviruses (NoVs) are single-stranded RNA viruses that infect host organisms via the fecal-oral route. Murine NoV (MNV) infects intestinal macrophages and dendritic cells and provides a tractable experimental system for understanding how an enteric virus overcomes the intestinal epithelial barrier to infect underlying target cells. We found that replication of two divergent MNV strains was reduced in mice depleted of M cells. Reoviruses are double-stranded RNA viruses that infect hosts via respiratory or enteric routes. In contrast to MNV, reovirus infects enterocytes in the intestine. Despite differences in cell tropism, reovirus infection was also reduced in M cell-depleted mice. These data demonstrate that M cells are required for the pathogenesis of two unrelated enteric viruses that replicate in different cell types within the intestine.

IMPORTANCE
To successfully infect their hosts, pathogens that infect via the gastrointestinal tract must overcome the multilayered system of host defenses. Microfold (M) cells are specialized intestinal epithelial cells that internalize particulate antigens and aid in the establishment of immune responses to enteric pathogens. Virus particles have been observed within M cells. However, it is not known whether viruses use M cells to initiate a productive infection. To address this question, we use MNV and reovirus, two enteric viruses that replicate in different cell types in the intestine, intestinal epithelial cells for reovirus and intestinal mononuclear phagocytes for MNV. Interestingly, MNV- and reovirus-infected mice depleted of M cells showed reduced viral loads in the intestine. Thus, our work demonstrates the importance of M cells in the pathogenesis of enteric viruses irrespective of the target cell type in which the virus replicates.
Ebolavirus Entry Requires a Compact Hydrophobic Fist at the Tip of the Fusion Loop
Authors: Gregory Sonia M. , Larsson Per , Nelson Elizabeth A. , Kasson Peter M. , White Judith M. , Tamm Lukas K.
Published: April 2014

Ebolavirus is an enveloped virus causing severe hemorrhagic fever. Its surface glycoproteins undergo proteolytic cleavage and rearrangements to permit membrane fusion and cell entry. Here we focus on the glycoprotein's internal fusion loop (FL), critical for low-pH-triggered fusion in the endosome. Alanine mutations at L529 and I544 and particularly the L529 I544 double mutation compromised viral entry and fusion. The nuclear magnetic resonance (NMR) structures of the I544A and L529A I544A mutants in lipid environments showed significant disruption of a three-residue scaffold that is required for the formation of a consolidated fusogenic hydrophobic surface at the tip of the FL. Biophysical experiments and molecular simulation revealed the position of the wild-type (WT) FL in membranes and showed the inability of the inactive double mutant to reach this position. Consolidation of hydrophobic residues at the tip of FLs may be a common requirement for internal FLs of class I, II, and III fusion proteins.

IMPORTANCE
Many class I, II, and III viral fusion proteins bear fusion loops for target membrane insertion and fusion. We determined structures of the Ebolavirus fusion loop and found residues critical for forming a consolidated hydrophobic surface, membrane insertion, and viral entry.
Live Attenuated Tetravalent Dengue Virus Host Range Vaccine Is Immunogenic in African Green Monkeys following a Single Vaccination
Authors: Briggs Caitlin M. , Smith Katherine M. , Piper Amanda , Huitt Emerson , Spears Carla J. , Quiles Michelle , Ribeiro Mariana , Thomas Malcolm E. , Brown Dennis T. , Hernandez Raquel
Published: April 2014

The causative agent of dengue fever, dengue virus (DENV), is transmitted by mosquitoes, and as distribution of these insects has expanded, so has dengue-related disease. DENV is a member of the
Flaviviridae
family and has 4 distinct serotypes (DENV-1, -2, -3, and -4). No lasting cross protection is afforded to heterologous serotypes following infection by any one of the individual serotypes. The presence of nonneutralizing antibodies to one serotype can facilitate the occurrence of more-severe dengue hemorrhagic fever through immune enhancement upon infection with a second serotype. For this reason, the development of a safe, tetravalent vaccine to produce a balanced immune response to all four serotypes is critical. We have developed a novel approach to produce safe and effective live-attenuated vaccines for DENV and other insect-borne viruses. Host range (HR) mutants of each DENV serotype were created by truncating transmembrane domain 1 of the E protein and selecting for strains of DENV that replicated well in insect cells but not mammalian cells. These vaccine strains were tested for immunogenicity in African green monkeys (AGMs). No vaccine-related adverse events occurred. The vaccine strains were confirmed to be attenuated
in vivo
by infectious center assay (ICA). Analysis by 50% plaque reduction neutralization test (PRNT
50
) established that by day 62 postvaccination, 100% of animals seroconverted to DENV-1, -2, -3, and -4. Additionally, the DENV HR tetravalent vaccine (HR-Tet) showed a tetravalent anamnestic immune response in 100% (16/16) of AGMs after challenge with wild-type (WT) DENV strains.

IMPORTANCE
We have generated a live attenuated viral (LAV) vaccine capable of eliciting a strong immune response in African green monkeys (AGMs) in a single dose. This vaccine is delivered by injecting one of four attenuated serotypes into each limb of the animal. 100% of animals given the vaccine generated antibodies against all 4 serotypes, and this response was found to be balanced in nature. This is also one of the first studies of dengue in AGMs, and our study suggests that viremia and antibody response in AGMs may be similar to those seen in DENV infection in humans.
A Broadly Neutralizing Human Monoclonal Antibody Directed against a Novel Conserved Epitope on the Influenza Virus H3 Hemagglutinin Globular Head
Authors: Benjamin Ebony , Wang Weijia , McAuliffe Josephine M. , Palmer-Hill Frances J. , Kallewaard Nicole L. , Chen Zhongying , Suzich JoAnn A. , Blair Wade S. , Jin Hong , Zhu Qing
Published: April 2014

Most neutralizing antibodies elicited during influenza virus infection or vaccination target immunodominant, variable epitopes on the globular head region of hemagglutinin (HA), which leads to narrow strain protection. In this report, we describe the properties of a unique anti-HA monoclonal antibody (MAb), D1-8, that was derived from human B cells and exhibits potent, broad neutralizing activity across antigenically diverse influenza H3 subtype viruses. Based on selection of escape variants, we show that D1-8 targets a novel epitope on the globular head region of the influenza virus HA protein. The HA residues implicated in D1-8 binding are highly conserved among H3N2 viruses and are located proximal to antigenic site D. We demonstrate that the potent
in vitro
antiviral activity of D1-8 translates into protective activity in mouse models of influenza virus infection. Furthermore, D1-8 exhibits superior therapeutic survival benefit in influenza virus-infected mice compared to the neuraminidase inhibitor oseltamivir when treatment is started late in infection. The present study suggests the potential application of this monoclonal antibody for the therapeutic treatment of H3N2 influenza virus infection.

IMPORTANCE
Recently, a few globular head-targeting MAbs have been discovered that exhibit activity against different subtypes of influenza subtypes, such as H1; however, none of the previously described MAbs showed broadly neutralizing activity against diverse H3 viruses. In this report, we describe a human MAb, D1-8, that exhibits potent, broadly neutralizing activity against antigenically diverse H3 subtype viruses. The genotypic analysis of escape mutants revealed a unique putative epitope region in the globular head of H3 HA that is comprised of highly conserved residues and is distinct from the receptor binding site. Furthermore, we demonstrate that D1-8 exhibits superior therapeutic efficacy in influenza virus-infected mice compared to the neuraminidase inhibitor oseltamivir when treatment is started late in infection. In addition to describing a novel anti-globular head of H3 HA MAb with potent broadly neutralizing activity, our report suggests the potential of D1-8 for therapeutic treatment of seasonal influenza virus H3 infection.
Epstein-Barr Virus Infection Induces Indoleamine 2,3-Dioxygenase Expression in Human Monocyte-Derived Macrophages through p38/Mitogen-Activated Protein Kinase and NF-κB Pathways: Impairment in T Cell Functions
Authors: Liu Wan-li , Lin Yue-hao , Xiao Han , Xing Shan , Chen Hao , Chi Pei-dong , Zhang Ge
Published: April 2014

Epstein-Barr virus (EBV) infection has been observed in tumor-infiltrated macrophages, but its infection effects on macrophage immune functions are poorly understood. Here, we showed that some macrophages in the tumor stroma of nasopharyngeal carcinoma (NPC) tissue expressed the immunosuppressive protein indoleamine 2,3-dioxygenase (IDO) more strongly than did tumor cells. EBV infection induced mRNA, protein, and enzymatic activity of IDO in human monocyte-derived macrophages (MDMs). Infection increased the production of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), whereas the neutralizing antibodies against TNF-α and IL-6 inhibited IDO induction. EBV infection also activated the mitogen-activated protein kinase (MAPK) p38 and NF-κB, and the inhibition of these two pathways with SB202190 and SN50 almost abrogated TNF-α and IL-6 production and inhibited IDO production. Moreover, the activation of IDO in response to EBV infection of MDMs suppressed the proliferation of T cells and impaired the cytotoxic activity of CD8
+
T cells, whereas the inhibition of IDO activity with 1-methyl-
l
-tryptophan (1-MT) did not affect T cell proliferation and function. These findings indicate that EBV-induced IDO expression in MDMs is substantially mediated by IL-6- and TNF-α-dependent mechanisms via the p38/MAPK and NF-κB pathways, suggesting that a possible role of EBV-mediated IDO expression in tumor stroma of NPC may be to create a microenvironment of suppressed T cell immune responses.

IMPORTANCE
CD8
+
cytotoxic T lymphocytes (CTLs) play an important role in the control of viral infections and destroy tumor cells. Activation of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO) in cancer tissues facilitates immune escape by the impairment of CTL functions. IDO expression was observed in some macrophages of the tumor stroma of nasopharyngeal carcinoma (NPC) tissue, and IDO could be induced in Epstein-Barr virus (EBV)-infected human monocyte-derived macrophages (MDMs). NPC cells and macrophages have been found to produce IDO in a gamma interferon (IFN-γ)-dependent manner. Instead, EBV-induced IDO expression in MDMs is substantially mediated by IL-6- and TNF-α-dependent mechanisms via the p38/MAPK and NF-κB pathways, which suppressed the proliferation of T cells and impaired the cytotoxic activity of CD8
+
T cells. This finding provides a new interpretation of the mechanism of immune escape of EBV and shows the immunosuppressive role of EBV-mediated IDO expression in tumor stroma of NPC.
The Stress Granule Component TIA-1 Binds Tick-Borne Encephalitis Virus RNA and Is Recruited to Perinuclear Sites of Viral Replication To Inhibit Viral Translation
Authors: Albornoz Amelina , Carletti Tea , Corazza Gianmarco , Marcello Alessandro
Published: April 2014

Flaviviruses
are a major cause of disease in humans and animals worldwide. Tick-borne encephalitis virus (TBEV) is the most important arthropod-borne flavivirus endemic in Europe and is the etiological agent of tick-borne encephalitis, a potentially fatal infection of the central nervous system. However, the contributions of host proteins during TBEV infection are poorly understood. In this work, we investigate the cellular protein TIA-1 and its cognate factor TIAR, which are stress-induced RNA-binding proteins involved in the repression of initiation of translation of cellular mRNAs and in the formation of stress granules. We show that TIA-1 and TIAR interact with viral RNA in TBEV-infected cells. During TBEV infection, cytoplasmic TIA-1 and TIAR are recruited at sites of viral replication with concomitant depletion from stress granules. This effect is specific, since G3BP1, another component of these cytoplasmic structures, remains localized to stress granules. Moreover, heat shock induction of stress granules containing TIA-1, but not G3BP1, is inhibited in TBEV-infected cells. Infection of cells depleted of TIA-1 or TIAR by small interfering RNA (siRNA) or TIA-1
−/−
mouse fibroblasts, leads to a significant increase in TBEV extracellular infectivity. Interestingly, TIAR
−/−
fibroblasts show the opposite effect on TBEV infection, and this phenotype appears to be related to an excess of TIA-1 in these cells. Taking advantage of a TBE-luciferase replicon system, we also observed increased luciferase activity in TIA-1
−/−
mouse fibroblasts at early time points, consistent with TIA-1-mediated inhibition at the level of the first round of viral translation. These results indicate that, in response to TBEV infection, TIA-1 is recruited to sites of virus replication to bind TBEV RNA and modulate viral translation independently of stress granule (SG) formation.

IMPORTANCE
This study (i) extends previous work that showed TIA-1/TIAR recruitment at sites of flavivirus replication, (ii) demonstrates that TIAR behaves like TIA-1 as an inhibitor of viral replication using an RNA interference (RNAi) approach in human cells that contradicts the previous hypothesis based on mouse embryonic fibroblast (MEF) knockouts only, (iii) demonstrates that tick-borne encephalitis virus (TBEV) is capable of inducing bona fide G3BP1/eIF3/eIF4B-positive stress granules, (iv) demonstrates a differential phenotype of stress response proteins following viral infection, and (v) implicates TIA-1 in viral translation and as a modulator of TBEV replication.
Pathogenic Features Associated with Increased Virulence upon Simian Immunodeficiency Virus Cross-Species Transmission from Natural Hosts
Authors: Mandell Daniel T. , Kristoff Jan , Gaufin Thaidra , Gautam Rajeev , Ma Dongzhu , Sandler Netanya , Haret-Richter George , Xu Cuiling , Aamer Hadega , Dufour Jason , Trichel Anita , Douek Daniel C. , Keele Brandon F. , Apetrei Cristian , Pandrea Ivona
Published: April 2014

While simian immunodeficiency viruses (SIVs) are generally nonpathogenic in their natural hosts, dramatic increases in pathogenicity may occur upon cross-species transmission to new hosts. Deciphering the drivers of these increases in virulence is of major interest for understanding the emergence of new human immunodeficiency viruses (HIVs). We transmitted SIVsab from the sabaeus species of African green monkeys (AGMs) to pigtailed macaques (PTMs). High acute viral replication occurred in all SIVsab-infected PTMs, yet the outcome of chronic infection was highly variable, ranging from rapid progression to controlled infection, which was independent of the dynamics of acute viral replication, CD4
+
T cell depletion, or preinfection levels of microbial translocation. Infection of seven PTMs with plasma collected at necropsy from a rapid-progressor PTM was consistently highly pathogenic, with high acute and chronic viral replication, massive depletion of memory CD4
+
T cells, and disease progression in all PTMs. The plasma inoculum used for the serial passage did not contain adventitious bacterial or viral contaminants. Single-genome amplification showed that this inoculum was significantly more homogenous than the inoculum directly derived from AGMs, pointing to a strain selection in PTMs. In spite of similar peak plasma viral loads between the monkeys in the two passages, immune activation/inflammation levels dramatically increased in PTMs infected with the passaged virus. These results suggest that strain selection and a massive cytokine storm are major factors behind increased pathogenicity of SIV upon serial passage and adaptation of SIVs to new hosts following cross-species transmission.

IMPORTANCE
We report here that upon cross-species transmission and serial passage of SIVsab from its natural host, the sabaeus African green monkey (AGM), to a new host, the pigtailed macaque (PTM), viral adaptation and increased pathogenicity involve strain selection and a massive cytokine storm. These results permit the design of strategies aimed at preventing cross-species transmission from natural hosts of SIVs to humans in areas of endemicity. Furthermore, our study describes a new animal model for SIV infection. As the outcomes of SIVsab infection in PTMs, African green monkeys, and rhesus macaques are different, the use of these systems enables comparative studies between pathogenic, nonpathogenic, and elite-controlled infections, to gain insight into the mechanisms of SIV immunodeficiency and comorbidities.
Pneumothorax as a presentation of perforated duodenal ulcer
Authors: Mahdi Shihab Ahmed , Kareem AlNajjar Firas Jaafar , Hussain Kosar
Published: April 2014

A young man presented with a sudden onset of severe abdominal pain and vomiting. He also had shortness of breath with right-sided pleuritic chest pain. On examination he was found to have a rigid and diffusely tender abdomen. Auscultation of the chest revealed reduced air entry into the right lung. An erect chest X-ray confirmed the presence of pneumoperitoneum and a right-sided pneumothorax. He underwent placement of a right intercostal drain followed by urgent laparotomy. The intraoperative findings were consistent with a small duodenal perforation, which was managed by a simple omental patch closure. His postoperative course was uneventful. Pneumothorax is a rare complication of perforated duodenal ulcer and should be kept in mind while assessing patients who present with abdominal pain and dyspnoea. We have discussed various possibilities that should be considered in patients who present with a concomitant pneumothorax and pneumoperitoneum.
A rare cause of susceptibility to neutropenic sepsis in a patient with metastatic pancreas cancer
Authors: Suarez Martinez-Falero Beatriz , Gillmore Roopinder
Published: April 2014

A 71-year-old patient receiving combination chemotherapy (irinotecan, oxaliplatin and 5-fluorouracil (5-FU)) for metastatic pancreas cancer was admitted after her first cycle of chemotherapy with a severe and unexpectedly prolonged episode of neutropenic sepsis associated with pancytopenia and marked mucositis. Owing to the unusual picture, the patient was tested for mutations in the gene encoding the enzyme dihydropyrimidine dehydrogenase (DPD)—an enzyme involved in the metabolism of the chemotherapy drug 5-FU. The patient was found to be heterozygous for a mutation, DPD IVS14+1G>A, leading to the severe toxicity exhibited following this regimen caused by delayed metabolism of 5-FU. She was treated aggressively with supportive care and recovered from this episode. Importantly she was subsequently switched to an alternative chemotherapy regimen to treat her disease. She continues to maintain an excellent quality of life some 9 months after her initial diagnosis on third-line chemotherapy.
Conservative management of subglottic stenosis in pregnancy resulting in vaginal birth
Authors: Nash Zachary , Krishna Archana , Darwish Mohamed , Mascarenhas Lawrence
Published: April 2014

We present a case of subglottic stenosis complicating pregnancy. The patient was born prematurely at 24 weeks gestation and required a twelve-month period of intubation. Airway trauma from prolonged intubation resulted in acquired subglottic stenosis. As an adult the patient had a longstanding audible stridor; however, was not breathless during activity before or during pregnancy. The patient went into spontaneous labour at 37+4 weeks and delivered vaginally with epidural analgesia. This case is significant, as no cases of a patient with such a degree of stenosis delivering vaginally without airway treatment have been reported.