bluuebunny/crossref_metadata_2025 huggingface dataset:
An Articulating Tool for Endoscopic Screw Delivery
Authors: Petrzelka Joseph E. , Menon Manas C. , Stefanov-Wagner Clara J. , Agarwal Suresh K. , Chatzigeorgiou Dimitris , Lustrino Michelle , Slocum Alexander H.
Published: February 2011

This paper describes the development of an articulating endoscopic screw driver that can be used to place screws in osteosynthetic plates during thoracoscopic surgery. The device is small enough to be used with a 12 mm trocar sleeve and transmits sufficient torque to fully secure bone screws. The articulating joint enables correct screw alignment at obtuse angles, up to 60 deg from the tool axis. A novel articulating joint is presented, wherein a flexible shaft both transmits torque and actuates the joint; antagonist force is provided by a superelastic spring. Screws are secured against the driver blade during insertion with a retention mechanism that passively releases the screw once it is securely seated in the bone. The prototype has been fitted with a blade compatible with 2.0 and 2.3 mm self-drilling screws, though a different driver blade or drill bit can be easily attached. Efficacy of the tool has been demonstrated by thoracoscopically securing an osteosynthetic plate to a rib during an animal trial. This tool enables minimally invasive, thoracoscopic rib fixation.
Regional Left Ventricular Myocardial Contractility and Stress in a Finite Element Model of Posterobasal Myocardial Infarction
Authors: Wenk Jonathan F. , Sun Kay , Zhang Zhihong , Soleimani Mehrdad , Ge Liang , Saloner David , Wallace Arthur W. , Ratcliffe Mark B. , Guccione Julius M.
Published: February 2011

Recently, a noninvasive method for determining regional myocardial contractility, using an animal-specific finite element (FE) model-based optimization, was developed to study a sheep with anteroapical infarction (Sun et al., 2009, “A Computationally Efficient Formal Optimization of Regional Myocardial Contractility in a Sheep With Left Ventricular Aneurysm,” ASME J. Biomech. Eng., 131(11), p. 111001). Using the methodology developed in the previous study (Sun et al., 2009, “A Computationally Efficient Formal Optimization of Regional Myocardial Contractility in a Sheep With Left Ventricular Aneurysm,” ASME J. Biomech. Eng., 131(11), p. 111001), which incorporates tagged magnetic resonance images, three-dimensional myocardial strains, left ventricular (LV) volumes, and LV cardiac catheterization pressures, the regional myocardial contractility and stress distribution of a sheep with posterobasal infarction were investigated. Active material parameters in the noninfarcted border zone (BZ) myocardium adjacent to the infarct (Tmax_B), in the myocardium remote from the infarct (Tmax_R), and in the infarct (Tmax_I) were estimated by minimizing the errors between FE model-predicted and experimentally measured systolic strains and LV volumes using the previously developed optimization scheme. The optimized Tmax_B was found to be significantly depressed relative to Tmax_R, while Tmax_I was found to be zero. The myofiber stress in the BZ was found to be elevated, relative to the remote region. This could cause further damage to the contracting myocytes, leading to heart failure.
Multilaboratory Particle Image Velocimetry Analysis of the FDA Benchmark Nozzle Model to Support Validation of Computational Fluid Dynamics Simulations
Authors: Hariharan Prasanna , Giarra Matthew , Reddy Varun , Day Steven W. , Manning Keefe B. , Deutsch Steven , Stewart Sandy F. C. , Myers Matthew R. , Berman Michael R. , Burgreen Greg W. , Paterson Eric G. , Malinauskas Richard A.
Published: February 2011

This study is part of a FDA-sponsored project to evaluate the use and limitations of computational fluid dynamics (CFD) in assessing blood flow parameters related to medical device safety. In an interlaboratory study, fluid velocities and pressures were measured in a nozzle model to provide experimental validation for a companion round-robin CFD study. The simple benchmark nozzle model, which mimicked the flow fields in several medical devices, consisted of a gradual flow constriction, a narrow throat region, and a sudden expansion region where a fluid jet exited the center of the nozzle with recirculation zones near the model walls. Measurements of mean velocity and turbulent flow quantities were made in the benchmark device at three independent laboratories using particle image velocimetry (PIV). Flow measurements were performed over a range of nozzle throat Reynolds numbers (Rethroat) from 500 to 6500, covering the laminar, transitional, and turbulent flow regimes. A standard operating procedure was developed for performing experiments under controlled temperature and flow conditions and for minimizing systematic errors during PIV image acquisition and processing. For laminar (Rethroat=500) and turbulent flow conditions (Rethroat≥3500), the velocities measured by the three laboratories were similar with an interlaboratory uncertainty of ∼10% at most of the locations. However, for the transitional flow case (Rethroat=2000), the uncertainty in the size and the velocity of the jet at the nozzle exit increased to ∼60% and was very sensitive to the flow conditions. An error analysis showed that by minimizing the variability in the experimental parameters such as flow rate and fluid viscosity to less than 5% and by matching the inlet turbulence level between the laboratories, the uncertainties in the velocities of the transitional flow case could be reduced to ∼15%. The experimental procedure and flow results from this interlaboratory study (available at http://fdacfd.nci.nih.gov) will be useful in validating CFD simulations of the benchmark nozzle model and in performing PIV studies on other medical device models.
Entropy and irreversibility in the quantum realm
Authors: Oerter Robert N.
Published: February 2011

A simple quantum mechanical model is used to investigate irreversibility. This model exhibits some features that do not appear in classical mechanics. The model is employed to investigate several definitions of entropy, the nature of microstates and macrostates, and the effects of a measurement and of environmental interactions on the reversibility of the system. The model illustrates the utility of the density operator in quantum mechanics.
Resource Letter NO-1: Nonlinear Optics
Authors: Garmire Elsa
Published: February 2011

This Resource Letter provides a guide to the literature on nonlinear optics. Books, journals, and websites are introduced that cover the general subject. Journal articles and websites are cited covering the following topics: second-order nonlinearities in transparent media including second-harmonic generation and optical parametric oscillation, third-order and higher nonlinearities, nonlinear refractive index, absorptive nonlinearities such as saturable absorption and multiphoton absorption, and scattering nonlinearities such as stimulated Raman scattering and stimulated Brillouin scattering. Steady-state and transient phenomena, fiber optics, solitons, nonlinear wave mixing, optical phase conjugation, nonlinear spectroscopy, and multiphoton microscopy are all outlined.
Noether’s theorem in a rotating reference frame
Authors: Dallen Lucas , Neuenschwander Dwight E.
Published: February 2011

We use a Lagrangian that yields the equation of motion for particle dynamics in a rotating reference frame to obtain the corresponding conservation laws through Noether’s theorem, which relates continuous symmetries to conservation laws. We derive the symmetries by invoking Noether’s theorem definition of invariance and solving the resulting set of coupled equations for generators of the transformations. The results illustrate, in a seldom-used context, the unifying power of Noether’s theorem.
Regularization, renormalization, and dimensional analysis: Dimensional regularization meets freshman E&M
Authors: Olness Fredrick , Scalise Randall
Published: February 2011

We illustrate the dimensional regularization technique using a simple example from electrostatics. This example illustrates the virtues of dimensional regularization without the complications of a full quantum field theory calculation. We contrast the dimensional regularization approach with the cutoff regularization approach, and demonstrate that dimensional regularization preserves translational symmetry. We then introduce minimal subtraction and modified minimal subtraction schemes to renormalize the result. Finally, we consider dimensional transmutation as encountered in the case of compact “extra dimensions.”
P. A. M. Dirac and the discovery of quantum mechanics
Authors: Gottfried Kurt
Published: February 2011

Dirac’s contributions to the discovery of nonrelativistic quantum mechanics and quantum electrodynamics, prior to his discovery of the relativistic wave equation, are described.
Distinct Properties of the XY Pseudoautosomal Region Crucial for Male Meiosis
Authors: Kauppi Liisa , Barchi Marco , Baudat Frédéric , Romanienko Peter J. , Keeney Scott , Jasin Maria
Published: February 2011

Recombination between the sex chromosomes during sperm formation is controlled by a splicing isoform of the SPO11 protein.
Capillary Forces in Suspension Rheology
Authors: Koos Erin , Willenbacher Norbert
Published: February 2011

The addition of a small amount of a nonwetting immiscible fluid to a suspension can drastically alter its rheological properties.
Hibernation in Black Bears: Independence of Metabolic Suppression from Body Temperature
Authors: Tøien Øivind , Blake John , Edgar Dale M. , Grahn Dennis A. , Heller H. Craig , Barnes Brian M.
Published: February 2011

Hibernating black bears suppress their metabolic rate to 25% of normal, but only slightly reduce their body temperature.
Synthetic Clonal Reproduction Through Seeds
Authors: Marimuthu Mohan P. A. , Jolivet Sylvie , Ravi Maruthachalam , Pereira Lucie , Davda Jayeshkumar N. , Cromer Laurence , Wang Lili , Nogué Fabien , Chan Simon W. L. , Siddiqi Imran , Mercier Raphaël
Published: February 2011

Clonal reproduction is engineered in a sexual plant by manipulating conserved genes controlling meiosis.
Steric Control of the Reaction of CH Stretch–Excited CHD
3
with Chlorine Atom
Authors: Wang Fengyan , Lin Jui-San , Liu Kopin
Published: February 2011

Spectroscopy elucidates the complex interplay between orientational and vibrational effects in a simple chemical reaction.
Quantum Reflection of He
2
Several Nanometers Above a Grating Surface
Authors: Zhao Bum Suk , Meijer Gerard , Schöllkopf Wieland
Published: February 2011

The helium molecule can interact at large distances with the evanescent repulsion potential of the surface.
Controlling the Flow of Suspensions
Authors: Butt Hans-Jürgen
Published: February 2011

Adding a small amount of an immiscible liquid to a suspension can change it from a viscous fluid to an elastic gel.
Creating Stable Memories
Authors: Sweatt J. David
Published: February 2011

Epigenetic mechanisms are involved in “tagging” rat neurons active in long-term memory of food odors.
Hitting a Tiny Target in the Dark
Authors: Hawley R. Scott
Published: February 2011

A region in mammalian sex chromosomes has distinct properties that ensure proper segregation during gamete development.
Life on Low Flame in Hibernation
Authors: Heldmaier Gerhard
Published: February 2011

In hibernating black bears, changes in metabolic rate and core body temperature occur independently.
A Living Constitution
Authors: Jasanoff Sheila
Published: February 2011

Sequencing the human genome provided a powerful new way to represent human identity, and the moral implications of that re-representation are just beginning to unfold.
Of Mice and Humans
Authors: Yamanaka Shinya
Published: February 2011

The technological advances catalyzed by the sequencing of the human genome have been highly beneficial to stem cell research.
A Windfall for Defenders of the Planet
Authors: Kerr Richard A.
Published: February 2011

Only about 5% of near-Earth asteroids (NEAs) 140 meters in diameter and larger—so-called city killers—have been found under NASA's search program. If U.S. astronauts hopscotch from one NEA practicing for their trip to Mars, it will be a big help to the search.
Fast, Antigen-Saving Multiplex Immunoassay To Determine Levels and Avidity of Mouse Serum Antibodies to Pertussis, Diphtheria, and Tetanus Antigens
Authors: Stenger Rachel M. , Smits Mieke , Kuipers Betsy , Kessen Sabine F. M. , Boog Claire J. P. , van Els Cécile A. C. M.
Published: February 2011

To enhance preclinical evaluation of serological immune responses to the individual diphtheria, tetanus, and pertussis (DTP) components of DTP combination vaccines, a fast hexavalent bead-based method was developed. This multiplex immunoassay (MIA) can simultaneously determine levels of specific mouse serum IgG antibodies to P antigens P.69 pertactin (P.69 Prn), filamentous hemagglutinin (FHA), pertussis toxin (Ptx), and combined fimbria type 2 and 3 antigens (Fim2/3) and to diphtheria toxin (Dtx) and tetanus toxin (TT) in a single well. The mouse DTP MIA was shown to be specific and sensitive and to correlate with the six single in-house enzyme-linked immunosorbent assays (ELISAs) for all antigens. Moreover, the MIA was expanded to include avidity measurements of DTP antigens in a multivalent manner. The sensitivities of the mouse DTP avidity MIA per antigen were comparable to those of the six individual in-house avidity ELISAs, and good correlations between IgG concentrations obtained by both methods for all antigens tested were shown. The regular and avidity mouse DTP MIAs were reproducible, with good intra- and interassay coefficients of variability (CV) for all antigens. Finally, the usefulness of the assay was demonstrated in a longitudinal study of the development and avidity maturation of specific IgG antibodies in mice having received different DTP vaccines. We conclude that the hexaplex mouse DTP MIA is a specific, sensitive, and high-throughput alternative for ELISA to investigate the quantity and quality of serological responses to DTP antigens in preclinical vaccine studies.
Nasal Immunity to Staphylococcal Toxic Shock Is Controlled by the Nasopharynx-Associated Lymphoid Tissue
Authors: Fernandez Stefan , Cisney Emily D. , Hall Shannan I. , Ulrich Robert G.
Published: February 2011

The nasopharynx-associated lymphoid tissue (NALT) of humans and other mammals is associated with immunity against airborne infections, though it is generally considered to be a secondary component of the mucosa-associated lymphoid system. We found that protective immunity to a virulence factor of nasal mucosa-colonizingStaphylococcus aureus, staphylococcal enterotoxin B (SEB), requires a functional NALT. We examined the role of NALT using intranasal (IN) vaccination with a recombinant SEB vaccine (rSEBv) combined with an adjuvant in a mouse model of SEB-induced toxic shock. The rSEBv was rapidly internalized by NALT cells at the mucosal barrier, and transport into NALT was accelerated by inclusion of a Toll-like receptor 4 (TLR4) agonist. Vaccine-induced germinal centers of B cells formed within NALT, accompanied by elevated levels of IgA+and IgG+cells, and these were further increased by TLR4 activation. The NALT was the site of specific anti-rSEBv IgA and IgG production but was also influenced by intraperitoneal (IP) inoculation and perhaps other isolated lymphoid follicles observed within the nasal cavity. Vaccination by the IN route generated robust levels of anti-rSEBv IgA in saliva, nasal secretions, and blood compared to much lower levels after IP vaccination. IN vaccination also induced secretion of anti-rSEBv IgG in the blood and nasal secretions. Significantly, the efficacy of IN vaccination was dependent on NALT, as surgical removal resulted in greater sensitivity to IN challenge with wild-type SEB. Thus, protective immunity to SEB within the nasal sinuses was elicited by responses originating in NALT.
First Characterization of CTX-M-15-Producing Escherichia coli ST131 and ST405 Clones Causing Community-Onset Infections in South America
Authors: Ruiz Sory J. , Montealegre Maria Camila , Ruiz-Garbajosa Patricia , Correa Adriana , Briceño David F. , Martinez Ernesto , Rosso Fernando , Muñoz Martin , Quinn John P. , Cantón Rafael , Villegas Maria Virginia
Published: February 2011

CTX-M-15-producing
Escherichia coli
has emerged worldwide as an important pathogen associated with community-onset infections, but in South America reports are scarce. We document the presence of CTX-M-15-producing
E. coli
of the international ST131 and ST405 clones in Colombia and present the first molecular characterization of these isolates in South America.
Preferential Deletion Events in the Direct Repeat Locus of Mycobacterium tuberculosis
Authors: Schürch Anita C. , Kremer Kristin , Kiers Albert , Boeree Martin J. , Siezen Roland J. , Soolingen Dick van
Published: February 2011

The “Harlingen” IS
6110
restriction fragment length polymorphism (RFLP) cluster has linked over 100 tuberculosis cases in The Netherlands since 1993. Four
Mycobacterium tuberculosis
isolates that were epidemiologically linked to this cluster had different spoligotype patterns, as well as slightly divergent IS
6110
profiles, compared to the majority of the isolates. Sequencing of the direct repeat (DR) locus revealed sequence polymorphisms at the putative deletion sites. These deletion footprints provided evidence for independent deletions of the central region of the DR locus in three isolates, while the different genotype of the fourth isolate was explained by transmission. Our finding suggests that convergent deletions in the DR locus occur frequently. However, deletion footprints are not suitable to detect convergent deletions in the DR because they seem to be exceptional. Deletion footprints in the DR were not described previously, and we did not observe them in any public
M. tuberculosis
complex sequences. We conclude that preferential deletions in the DR loci of closely related strains are usually an unnoted event that interferes with clustering of closely related strains.
Reevaluating and Optimizing Polyomavirus BK and JC Real-Time PCR Assays To Detect Rare Sequence Polymorphisms
Authors: Dumoulin A. , Hirsch H. H.
Published: February 2011

PCR-based molecular assays have a central role in polyomavirus diagnostics. To assure optimal performance, target sequences should be regularly updated according to newly available sequences. The aim of this study was to review our in-house polyomavirus BK (BKV) and JC (JCV) real-time PCR assays. Database analysis revealed variations in the BKV target region which might affect the assay performance, while no significant changes were found in the JCV target region. We compared two degenerate versions of our BKV primers which accommodated at least 95% of all published genetic variants. Dilutions of cloned viral genomic DNA and probit analysis indicated an analytical sensitivity of the updated BKV assay of 4.15 copies/reaction and that of the JCV assay was 3.37 copies/reaction. The specificity was assessed by testing JCV- and BKV-positive samples that showed no cross-reactivity. The performance of the original and updated BKV assay was compared in 101 urine and 200 plasma samples submitted to our routine diagnostic laboratory revealed similar quantitative results. We conclude that our JCV and updated BKV real-time PCR assays are robust and detect rare variants possibly encountered in the clinical routine.
Fecal Leukocytes in Children Infected with Diarrheagenic Escherichia coli
Authors: Mercado Erik H. , Ochoa Theresa J. , Ecker Lucie , Cabello Martin , Durand David , Barletta Francesca , Molina Margarita , Gil Ana I. , Huicho Luis , Lanata Claudio F. , Cleary Thomas G.
Published: February 2011

The purpose of this study was to determine the presence and quantity of fecal leukocytes in children infected with diarrheagenic
Escherichia coli
and to compare these levels between diarrhea and control cases. We analyzed 1,474 stool samples from 935 diarrhea episodes and 539 from healthy controls of a cohort study of children younger than 2 years of age in Lima, Peru. Stools were analyzed for common enteric pathogens, and diarrheagenic
E. coli
isolates were studied by a multiplex real-time PCR. Stool smears were stained with methylene blue and read by a blinded observer to determine the number of polymorphonuclear leukocytes per high-power field (L/hpf). Fecal leukocytes at >10 L/hpf were present in 11.8% (110/935) of all diarrheal episodes versus 1.1% (6/539) in controls (
P
< 0.001). Among stool samples with diarrheagenic
E. coli
as the only pathogen isolated (excluding coinfection), fecal leukocytes at >10 L/hpf were present in 8.5% (18/212) of diarrhea versus 1.3% (2/157) of control samples (
P
< 0.01). Ninety-five percent of 99 diarrheagenic
E. coli
diarrhea samples were positive for fecal lactoferrin. Adjusting for the presence of blood in stools, age, sex, undernutrition, and breastfeeding, enterotoxigenic
E. coli
(ETEC) isolation as a single pathogen, excluding coinfections, was highly associated with the presence of fecal leukocytes (>10 L/hpf) with an odds ratio (OR) of 4.1 (95% confidence interval [CI], 1.08 to 15.51;
P
< 0.05). Although diarrheagenic
E. coli
was isolated with similar frequencies in diarrhea and control samples, clearly it was associated with a more inflammatory response during symptomatic infection; however, in general, these pathogens elicited a mild inflammatory response.
Comparison of Clinical Performance of Abbott RealTi
m
e High Risk HPV Test with That of Hybrid Capture 2 Assay in a Screening Setting
Authors: Carozzi F. M. , Burroni E. , Bisanzi S. , Puliti D. , Confortini M. , Giorgi Rossi P. , Sani C. , Scalisi A. , Chini F.
Published: February 2011

Randomized trials have produced sound evidence about the efficacy of screening with human papillomavirus (HPV) DNA tests in reducing cervical cancer incidence and mortality. We evaluated the clinical performance and reproducibility of the Abbott RealTi
m
e High Risk (HR) HPV test compared with that of the HR hybrid capture 2 (HC2) assay as assessed by a noninferiority score test. A random sample of 998 cervical specimens (914 specimens of cervical intraepithelial neoplasia less severe than grade 2 [<CIN2] and 84 specimens of cervical intraepithelial neoplasia grade 2 or more severe lesions [≥CIN2]), collected in the Florence and Catania cervical Cancer Screening Programs from women aged 25 to 64 and already tested by HR HC2, were retested with the Abbott RealTi
m
e HR HPV test. Absolute specificity was 92.3% (95% confidence interval [CI], 90.4 to 94.0) and 92.6% (95% CI, 90.7 to 94.2) for the Abbott RealTi
m
e HR HPV test and the HR HC2, respectively. Absolute sensitivity was 96.4% (95% CI, 89.9 to 99.3) and 97.6% (95% CI, 91.7 to 99.7) for the Abbott RealTi
m
e HR HPV test and the HR HC2, respectively. The noninferiority score test revealed that the clinical sensitivity and specificity of the Abbott RealTi
m
e HR HPV test were not inferior (
P
= 0.004 and 0.009, respectively) to those of HR HC2. Overall agreement between the two assays was 96.5%, with a
k
value of 0.86 (CI 95%, 0.82 to 0.91). We evaluated the intralaboratory reproducibility by retesting 521 samples at least 4 weeks after the first test; the crude agreement between the first and second test was 98.5%, with an overall
k
value of 0.97 (CI 95%, 0.95 to 0.99). This test fully satisfies the requirements of a primary cervical cancer screening test. This assay differentiates between HPV16, HPV18, and non-HPV16/18 types in every specimen, but how to use this information in a screening setting still is unclear.
Characterization of 2009 Pandemic Influenza A (H1N1) Virus Specimens with a Positive Hemagglutinin 1 Signal in the Luminex xTAG Respiratory Viral Panel Assay
Authors: McCloskey Cindy B. , Kraft Colleen S. , Ingersoll Jessica M. , Hill Charles E. , Burd Eileen M. , Caliendo Angela M.
Published: February 2011

This retrospective review analyzed Luminex xTAG respiratory viral panel (RVP) results for 2009 pandemic influenza A (H1N1) virus specimens. Comparing median fluorescence intensity (MFI) signals for the influenza A virus and hemagglutinin 1 (H1) reactions for specimens with very low positive (MFI < 1,000) or “no-call” H1 results reliably distinguished 2009 H1N1 from seasonal virus.
Adaptation of Subtype A Human Immunodeficiency Virus Type 1 Envelope to Pig-Tailed Macaque Cells
Authors: Humes Daryl , Overbaugh Julie
Published: February 2011

The relevance of simian/human immunodeficiency virus (SHIV) infection of macaques to HIV-1 infection in humans depends on how closely SHIVs mimic HIV-1 transmission, pathogenesis, and diversity. Circulating HIV-1 strains are predominantly subtypes C and A and overwhelmingly require CCR5 for entry, yet most SHIVs incorporate CXCR4-using subtype B envelopes (Envs). While pathogenic subtype C-based SHIVs have been constructed, the subtype A-based SHIVs (SHIV-As) constructed to date have been unable to replicate in macaque cells. To understand the barriers to SHIV-A replication in macaque cells, HIVA
Q23
/SIV
vif
was constructed by engineering a CCR5-tropic subtype A provirus to express SIV
vif
, which counters the macaque APOBEC3G restriction. HIVA
Q23
/SIV
vif
replicated poorly in pig-tailed macaque (Ptm) lymphocytes, but viruses were adapted to Ptm lymphocytes. Two independent mutations in gp120, G312V (V3 loop) and A204E (C2 region), were identified that increased peak virus levels by >100-fold. Introduction of G312V and A204E to multiple subtype A Envs and substitution of G312 and A204 with other residues increased entry into Ptm cells by 10- to 100-fold. G312V and A204E Env variants continued to require CCR5 for entry but were up to 50- and 200-fold more sensitive to neutralization by IgG1b12 and soluble CD4 and had a 5- to 50-fold increase in their ability to utilize Ptm CD4 compared to their wild-type counterparts. These findings identify the inefficient use of Ptm CD4 as an unappreciated restriction to subtype A HIV-1 replication in Ptm cells and reveal amino acid changes to gp120 that can overcome this barrier.
Infection, Viral Dissemination, and Antibody Responses of Rhesus Macaques Exposed to the Human Gammaretrovirus XMRV
Authors: Onlamoon Nattawat , Das Gupta Jaydip , Sharma Prachi , Rogers Kenneth , Suppiah Suganthi , Rhea Jeanne , Molinaro Ross J. , Gaughan Christina , Dong Beihua , Klein Eric A. , Qiu Xiaoxing , Devare Sushil , Schochetman Gerald , Hackett John , Silverman Robert H. , Villinger François
Published: February 2011

Xenotropic murine leukemia-related virus (XMRV) was identified in association with human prostate cancer and chronic fatigue syndrome. To examine the infection potential, kinetics, and tissue distribution of XMRV in an animal model, we inoculated five macaques with XMRV intravenously. XMRV established a persistent, chronic disseminated infection, with low transient viremia and provirus in blood lymphocytes during acute infection. Although undetectable in blood after about a month, XMRV viremia was reactivated at 9 months, confirming the chronicity of the infection. Furthermore, XMRV Gag was detected in tissues throughout, with wide dissemination throughout the period of monitoring. Surprisingly, XMRV infection showed organ-specific cell tropism, infecting CD4 T cells in lymphoid organs including the gastrointestinal lamina propria, alveolar macrophages in lung, and epithelial/interstitial cells in other organs, including the reproductive tract. Of note, in spite of the intravenous inoculation, extensive XMRV replication was noted in prostate during acute but not chronic infection even though infected cells were still detectable by fluorescence
in situ
hybridization (FISH) in prostate at 5 and 9 months postinfection. Marked lymphocyte activation occurred immediately postinfection, but antigen-specific cellular responses were undetectable. Antibody responses were elicited and boosted upon reexposure, but titers decreased rapidly, suggesting low antigen stimulation over time. Our findings establish a nonhuman primate model to study XMRV replication/dissemination, transmission, pathogenesis, immune responses, and potential future therapies.
EFFECTS OF ANTIMONY FLUX ON MORPHOLOGY AND PHOTOLUMINESCENCE SPECTRA OF GaSb QUANTUM DOTS FORMED ON GaAs BY DROPLET EPITAXY
Authors: KAWAZU T. , NODA T. , MANO T. , JO M. , SAKAKI H.
Published: February 2011

We investigated effects of the antimony flux on GaSb quantum dots (QDs) formed by droplet epitaxy. Ga droplets were first formed on GaAs and exposed to Sb4 molecular beam at 200 °C, where the flux PSb of Sb beam was varied from 2.4 to 12.8 × 10-7 Torr. The samples were then annealed for 2 minutes under the Sb flux. An atomic microscope study showed that the diameter of GaSb QDs increases and the density decreases, as the Sb flux PSb is increased. This indicates that the coalescence process of GaSb QDs occurs and is accelerated by the increase of the Sb flux. In a photoluminescence (PL) study, we observed a broad peak of GaSb QDs in all samples, while a strong luminescence of a wetting layer (WL)-like structure was found only in the samples prepared with the high Sb flux. This suggests that the PL of WL is controllable by adjusting the flux PSb of Sb beam.
Histone H3K4 trimethylation by MLL3 as part of ASCOM complex is critical for NR activation of bile acid transporter genes and is downregulated in cholestasis
Authors: Ananthanarayanan M. , Li Yanfeng , Surapureddi S. , Balasubramaniyan N. , Ahn Jaeyong , Goldstein J. A. , Suchy Frederick J.
Published: February 2011

The nuclear receptor Farnesoid x receptor (FXR) is a critical regulator of multiple genes involved in bile acid homeostasis. The coactivators attracted to promoters of FXR target genes and epigenetic modifications that occur after ligand binding to FXR have not been completely defined, and it is unknown whether these processes are disrupted during cholestasis. Using a microarray, we identified decreased expression of mixed lineage leukemia 3 (MLL3), a histone H3 lysine 4 (H3K4) lysine methyl transferase at 1 and 3 days of post-common bile duct ligation (CBDL) in mice. Chromatin immunoprecipitation analysis (ChIP) analysis revealed that H3K4me3 of transporter promoters by MLL3 as part of activating signal cointegrator-2 -containing complex (ASCOM) is essential for activation of bile salt export pump (BSEP), multidrug resistance associated protein 2 (MRP2), and sodium taurocholate cotransporting polypeptide (NTCP) genes by FXR and glucocorticoid receptor (GR). Knockdown of nuclear receptor coactivator 6 (NCOA6) or MLL3/MLL4 mRNAs by small interfering RNA treatment led to a decrease in BSEP and NTCP mRNA levels in hepatoma cells. Human BSEP promoter transactivation by FXR/RXR was enhanced in a dose-dependent fashion by NCOA6 cDNA coexpression and decreased by AdsiNCOA6 infection in HepG2 cells. GST-pull down assays showed that domain 3 and 5 of NCOA6 (LXXLL motifs) interacted with FXR and that the interaction with domain 5 was enhanced by chenodeoxycholic acid. In vivo ChIP assays in HepG2 cells revealed ligand-dependent recruitment of ASCOM complex to FXR element in BSEP and GR element in NTCP promoters, respectively. ChIP analysis demonstrated significantly diminished recruitment of ASCOM complex components and H3K4me3 to Bsep and Mrp2 promoter FXR elements in mouse livers after CBDL. Taken together, these data show that the “H3K4me3” epigenetic mark is essential to activation of BSEP, NTCP, and MRP2 genes by nuclear receptors and is downregulated in cholestasis.
Localized β-adrenergic receptor blockade does not affect sweating during exercise
Authors: Buono Michael J. , Tabor Brian , White Ailish
Published: February 2011

The purpose of the current study was to determine the effect of a locally administered nonselective β-adrenergic antagonist on sweat gland function during exercise. Systemically administered propranolol has been reported to increase, decrease, or not alter sweat production during exercise. To eliminate the confounding systemic effects associated with orally administered propranolol, we used iontophoresis to deliver it to the eccrine sweat glands within a localized area on one forearm prior to exercise. This allowed for determination of the direct effect of β-adrenergic receptor blockade on sweating during exercise. Subjects ( n = 14) reported to the laboratory (23 ± 1°C, 35 ± 3% relative humidity) after having refrained from exercise for ≥12 h. Propranolol (1% solution) was administered to a 5-cm2 area of the flexor surface of one forearm via iontophoresis (1.5 mA) for 5 min. A saline solution was administered to the opposing arm via iontophoresis. Each subject then exercised on a motor-driven treadmill at 75% of their age-predicted maximal heart rate for 20 min, while sweat rate was measured simultaneously in both forearms. Immediately after cessation of exercise, the number of active sweat glands was measured by application of iodine-impregnated paper to each forearm. The sweat rate for the control and propranolol-treated forearm was 0.62 ± 41 and 0.60 ± 0.44 (SD) mg·cm−2·min−1, respectively ( P = 0.86). The density of active sweat glands for the control and propranolol-treated forearm was 130 ± 6 and 134 ± 5 (SD) glands/cm2, respectively, ( P = 0.33). End-exercise skin temperature was 32.9 ± 0.2 and 33.1 ± 0.3°C for the control and propranolol-treated forearm, respectively ( P = 0.51). Results of the current study show that when propranolol is administered locally, thus eliminating the potential confounding systemic effects of the drug, it does not directly affect sweating during the initial stages of high-intensity exercise in young, healthy subjects.
Exercise-induced regulation of muscular Na+-K+ pump, FXYD1, and NHE1 mRNA and protein expression: importance of training status, intensity, and muscle type
Authors: Rasmussen Martin Krøyer , Juel Carsten , Nordsborg Nikolai B.
Published: February 2011

It is investigated if exercise-induced mRNA changes cause similar protein expression changes of Na+-K+ pump isoforms (α1, α2, β1, β2), FXYD1, and Na+/K+ exchanger (NHE1) in rat skeletal muscle. Expression was evaluated ( n = 8 per group) in soleus and extensor digutorum longus after 1 day, 3 days, and 3 wk (5 sessions/wk) of either sprint (4 × 3-min sprint + 1-min rest) or endurance (20 min) running. Two hours after exercise on day 1, no change in protein expression was apparent in either training group or muscle, whereas sprint exercise increased the mRNA of soleus α2 (4.9 ± 0.8-fold; P < 0.05), β2 (13.2 ± 4.4-fold; P < 0.001), and NHE1 (12.0 ± 3.1-fold; P < 0.01). Two hours after sprint exercise, protein expression normalized to control samples was higher on day 3 than day 1 for soleus α1 (41 ± 18% increase vs. 15 ± 8% reduction; P < 0.05), α2 (64 ± 35% increase vs. 37 ± 12% reduction; P < 0.05), β1 (17 ± 21% increase vs. 14 ± 29% reduction; P < 0.05), and FXYD1 (35 ± 16% increase vs. 13 ± 10% reduction; P < 0.05). In contrast, on day 3, soleus α1 (0.1 ± 0.1-fold; P < 0.001), α2 (0.2 ± 0.1-fold; P < 0.001), β1 (0.4 ± 0.1-fold; P < 0.05), and β2-mRNA (2.9 ± 1.7-fold; P < 0.001) expression was lower than after exercise on day 1. After 3 wk of training, no change in protein expression relative to control existed. In conclusion, increased expression of Na+-K+ pump subunits, FXYD1 and NHE1 after 3 days exercise training does not appear to be an effect of increased constitutive mRNA levels. Importantly, sprint exercise can reduce mRNA expression concomitant with increased protein expression.
Molecular mechanisms of angiotensin II stimulation on aquaporin-2 expression and trafficking
Authors: Li Chunling , Wang Weidong , Rivard Christopher J. , Lanaspa Miguel A. , Summer Sandra , Schrier Robert W.
Published: February 2011

ANG II plays a major role in renal water and sodium regulation. In the immortalized mouse renal collecting duct principal cells (mpkCCDcl4) cell line, we treated cells with ANG II and examined aquaporin-2 (AQP2) protein expression, trafficking, and mRNA levels, by immunoblotting, immunofluorescence, and RT-PCR. After 24-h incubation, ANG II-induced AQP2 protein expression was observed at the concentration of 10−10M and increased in a dose-dependent manner. ANG II (10−7M) increased AQP2 protein expression and mRNA levels at 0.5, 1, 2, 6, and 24 h. Immunofluorescence studies showed that ANG II increased the apical membrane targeting of AQP2 from 30 min to 6 h. Next, the signaling pathways underlying the ANG II-induced AQP2 expression were investigated. The PKC inhibitor Ro 31–8220 (5 × 10−6M) and the PKA inhibitor H89 (10−5M) blocked ANG II-induced AQP2 expression, respectively. Calmodulin inhibitor W-7 markedly reduced ANG II- and/or dDAVP-stimulated AQP2 expression. ANG II (10−9M) and/or dDAVP (10−10M) stimulated AQP2 protein levels and cAMP accumulation, which was completely blocked by pretreatment with the vasopressin V2 receptor (V2R) antagonist SR121463B (10−8M). Pretreatment with the angiotensin AT1receptor (AT1R) antagonist losartan (3 × 10−6M) blocked ANG II (10−9M)-stimulated AQP2 protein expression and cAMP accumulation, and partially blocked dDAVP (10−10M)- and dDAVP+ANG II-induced AQP2 protein expression and cAMP accumulation. In conclusion, ANG II regulates AQP2 protein, trafficking, and gene expression in renal collecting duct principal cells. ANG II-induced AQP2 expression involves cAMP, PKC, PKA, and calmodulin signaling pathways via V2 and AT1receptors.
Cdk2-dependent phosphorylation of p21 regulates the role of Cdk2 in cisplatin cytotoxicity
Authors: Hodeify Rawad , Tarcsafalvi Adel , Megyesi Judit , Safirstein Robert L. , Price Peter M.
Published: February 2011

Cisplatin cytotoxicity is dependent on cyclin-dependent kinase 2 (Cdk2) activity in vivo and in vitro. We found that an 18-kDa protein identified by mass spectrometry as p21WAF1/Cip1was phosphorylated by Cdk2 starting 12 h after cisplatin exposure. The analysis showed it was phosphorylated at serine 78, a site not previously identified. The adenoviral transduction of p21 before cisplatin exposure protects from cytotoxicity by inhibiting Cdk2. Although cisplatin causes induction of endogenous p21, the protection is inefficient. We hypothesized that phosphorylation of p21 at serine 78 could affect its role as a Cdk inhibitor, and thereby lessen its ability to protect from cisplatin cytotoxicity. To investigate the effect of serine 78 phosphorylation on p21 activity, we replaced serine 78 with aspartic acid, creating the phosphomimic p21S78D. Mutant p21S78Dwas an inefficient inhibitor of Cdk2 and was inefficient at protecting TKPTS cells from cisplatin-induced cell death. We conclude that phosphorylation of p21 by Cdk2 limits the effectiveness of p21 to inhibit Cdk2, which is the mechanism for continued cisplatin cytotoxicity even after the induction of a protective protein.
Bradykinin acutely inhibits activity of the epithelial Na+channel in mammalian aldosterone-sensitive distal nephron
Authors: Zaika Oleg , Mamenko Mykola , O'Neil Roger G. , Pochynyuk Oleh
Published: February 2011

Activation of the renal kallikrein-kinin system results in natriuresis and diuresis, suggesting its possible role in renal tubular sodium transport regulation. Here, we used patch-clamp electrophysiology to directly assess the effects of bradykinin (BK) on the epithelial Na+channel (ENaC) activity in freshly isolated split-opened murine aldosterone-sensitive distal nephrons (ASDNs). BK acutely inhibits ENaC activity by reducing channel open probability ( Po) in a dose-dependent and reversible manner. Inhibition of B2 receptors with icatibant (HOE-140) abolished BK actions on ENaC. In contrast, activation of B1 receptors with the selective agonist Lys-des-Arg9-BK failed to reproduce BK actions on ENaC. This is consistent with B2 receptors playing a critical role in mediating BK signaling to ENaC. BK has little effect on ENaC Powhen Gq/11was inhibited with Gp antagonist 2A. Moreover, inhibition of phospholipase C (PLC) with U73122, but not saturation of cellular cAMP levels with the membrane-permeable nonhydrolysable cAMP analog 8-cpt-cAMP, prevents BK actions on ENaC activity. This argues that BK stimulates B2 receptors with subsequent activation of Gq/11-PLC signaling cascade to acutely inhibit ENaC activity. Activation of BK signaling acutely depletes apical PI( 4 , 5 )P2levels. However, inhibition of Ca2+pump SERCA of the endoplasmic reticulum with thapsigargin does not prevent BK signaling to ENaC. Furthermore, caffeine, while producing a similar rise in [Ca2+]ias in response to BK stimulation, fails to recapitulate BK actions on ENaC. Therefore, we concluded that BK acutely inhibits ENaC Poin mammalian ASDN via stimulation of B2 receptors and following depletion of PI( 4 , 5 )P2, but not increases in [Ca2+]i.
The repeated-bout effect: influence on biceps brachii oxygenation and myoelectrical activity
Authors: Muthalib Makii , Lee Hoseong , Millet Guillaume Y. , Ferrari Marco , Nosaka Kazunori
Published: February 2011

This study investigated biceps brachii oxygenation and myoelectrical activity during and following maximal eccentric exercise to better understand the repeated-bout effect. Ten men performed two bouts of eccentric exercise (ECC1, ECC2), consisting of 10 sets of 6 maximal lengthening contractions of the elbow flexors separated by 4 wk. Tissue oxygenation index minimum amplitude (TOImin), mean and maximum total hemoglobin volume by near-infrared spectroscopy, torque, and surface electromyography root mean square (EMGRMS) during exercise were compared between ECC1 and ECC2. Changes in maximal voluntary isometric contraction (MVC) torque, range of motion, plasma creatine kinase activity, muscle soreness, TOImin, and EMGRMS during sustained (10-s) and 30-repeated isometric contraction tasks at 30% (same absolute force) and 100% MVC (same relative force) for 4 days postexercise were compared between ECC1 and ECC2. No significant differences between ECC1 and ECC2 were evident for changes in torque, TOImin, mean total hemoglobin volume, maximum total hemoglobin volume, and EMGRMS during exercise. Smaller ( P < 0.05) changes and faster recovery of muscle damage markers were evident following ECC2 than ECC1. During 30% MVC tasks, TOImin did not change, but EMGRMS increased 1–4 days following ECC1 and ECC2. During 100% MVC tasks, EMGRMS did not change, but torque and TOImin decreased 1–4 days following ECC1 and ECC2. TOImin during 100% MVC tasks and EMGRMS during 30% MVC tasks recovered faster ( P < 0.05) following ECC2 than ECC1. We conclude that the repeated-bout effect cannot be explained by altered muscle activation or metabolic/hemodynamic changes, and the faster recovery in muscle oxygenation and activation was mainly due to faster recovery of force.
Role of STIM1/Orai1-mediated store-operated Ca2+ entry in airway smooth muscle cell proliferation
Authors: Zou Jin-jing , Gao Ya-dong , Geng Shuang , Yang Jiong
Published: February 2011

Hyperplasia of airway smooth muscle cells (ASMCs) is a characteristic change of chronic asthma patients. However, the underlying mechanisms that trigger this process are not yet completely understood. Store-operated Ca2+ (SOC) entry (SOCE) occurs in response to the intracellular sarcoplasma reticulum (SR)/endoplasmic reticulum (ER) Ca2+ store depletion. SOCE plays an important role in regulating Ca2+ signaling and cellular responses of ASMCs. Stromal interaction molecule (STIM)1 has been proposed as an ER/SR Ca2+ sensor and translocates to the ER underneath the plasma membrane upon depletion of the ER Ca2+ store, where it interacts with Orai1, the molecular component of SOC channels, and brings about SOCE. STIM1 and Orai1 have been proved to mediate SOCE of ASMCs. In this study, we investigated whether STIM1/Orai1-mediated SOCE is involved in rat ASMC proliferation. We found that SOCE was upregulated during ASMC proliferation accompanied by a mild increase of STIM1 and a significant increase of Orai1 mRNA expression, whereas the proliferation of ASMCs was partially inhibited by the SOC channel blockers SKF-96365, NiCl2, and BTP-2. Suppressing the mRNA expression of STIM1 or Orai1 with specific short hairpin RNA resulted in the attenuation of SOCE and ASMC proliferation. Moreover, after knockdown of STIM1 or Orai1, the SOC channel blocker SKF-96365 had no inhibitory effect on the proliferation of ASMCs anymore. These results suggested that STIM1/Orai1-mediated SOCE is involved in ASMC proliferation.
Space coding by gamma oscillations in the barn owl optic tectum
Authors: Sridharan Devarajan , Boahen Kwabena , Knudsen Eric I.
Published: February 2011

Gamma-band (25–140 Hz) oscillations of the local field potential (LFP) are evoked by sensory stimuli in the mammalian forebrain and may be strongly modulated in amplitude when animals attend to these stimuli. The optic tectum (OT) is a midbrain structure known to contribute to multimodal sensory processing, gaze control, and attention. We found that presentation of spatially localized stimuli, either visual or auditory, evoked robust gamma oscillations with distinctive properties in the superficial (visual) layers and in the deep (multimodal) layers of the owl's OT. Across layers, gamma power was tuned sharply for stimulus location and represented space topographically. In the superficial layers, induced LFP power peaked strongly in the low-gamma band (25–90 Hz) and increased gradually with visual contrast across a wide range of contrasts. Spikes recorded in these layers included presumptive axonal (input) spikes that encoded stimulus properties nearly identically with gamma oscillations and were tightly phase locked with the oscillations, suggesting that they contribute to the LFP oscillations. In the deep layers, induced LFP power was distributed across the low and high (90–140 Hz) gamma-bands and tended to reach its maximum value at relatively low visual contrasts. In these layers, gamma power was more sharply tuned for stimulus location, on average, than were somatic spike rates, and somatic spikes synchronized with gamma oscillations. Such gamma synchronized discharges of deep-layer neurons could provide a high-resolution temporal code for signaling the location of salient sensory stimuli.
Exploring the Membrane Mechanism of the Bioactive Peptaibol Ampullosporin A Using Lipid Monolayers and Supported Biomimetic Membranes
Authors: Eid Marguerita , Rippa Sonia , Castano Sabine , Desbat Bernard , Chopineau Joël , Rossi Claire , Béven Laure
Published: February 2011

Ampullosporin A is an antimicrobial, neuroleptic peptaibol, the behavior of which was investigated in different membrane mimetic environments made of egg yolk L-α-phosphatidylcholine. In monolayers, the peptaibol adopted a mixed α/310-helical structure with an in-plane orientation. The binding step was followed by the peptide insertion into the lipid monolayer core. The relevance of the inner lipid leaflet nature was studied by comparing ampullosporin binding on a hybrid bilayer, in which this leaflet was a rigid alkane layer, and on supported fluid lipid bilayers. The membrane binding was examined by surface plasmon resonance spectroscopy and the effect on lipid dynamics was explored using fluorescence recovery after photobleaching. In the absence of voltage and at low concentration, ampullosporin A substantially adsorbed onto lipid surfaces and its interaction with biomimetic models was strongly modified depending on the inner leaflet structure. At high concentration, ampullosporin A addition led to the lipid bilayers disruption.