bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Properties of the Fetal Bovine Bladder Lamina Propria and Their Correlation With Changes in Extracellular Matrix
Authors: Cargill Robert S. , Toosi Kevin K. , Macarak Edward J.
Published: March 2014

The urinary bladder is an organ whose purpose is to store urine at low pressure and periodically expel it. This system normally operates at relatively low pressure to protect the kidneys from the deleterious effects of increased pressure. In certain pathologies, this organ can be subject to a decrease in compliance (“stiffening”) and an increase of the storage pressure which causes higher back pressure on the kidney and ultimately results in kidney damage if untreated. Clinically, these pathologies are exemplified in disorders such as myelomeningocele, posterior urethral valves, dysfunctional voiding, and disorders associated with spinal cord injuries. In these disorders, bladder structure is altered and the bladder becomes stiff and noncompliant.
Estimation of Achilles Tendon Moment Arms In Vivo: A Novel Hybrid Method Using Ultrasound and Motion Analysis
Authors: Cowder Justin D. , Chimera Nicole J. , Buchanan Thomas S. , Manal Kurt T.
Published: March 2014

The musculotendon moment arm (MA) is the perpendicular distance from a muscle’s line of action to the rotational center of a joint. Moment arms are important in muscle modeling [1], and thus their accuracy is of great importance. Current in vivo techniques for computing MAs include the center of rotation and tendon excursion methods [1, 2]. The tendon excursion (TE) method relates the change in musculotendon length to an angular change in joint position [3]. This requires two measurements of musculotendon length for each MA computed. Similarly, the center of rotation method requires multiple image-based geometry measurements to compute the MA for a specific joint angle. The TE and center of rotation methods are both prone to measurement error, and thus it is difficult to ascertain the accuracy of the resulting MA. In this paper we present a novel hybrid methodology combining ultrasound (US) and video-based motion capture to compute the Achilles tendon moment arm. An advantage of this approach is that data used to derive the MA are acquired using highly accurate and reliable measurement instruments (i.e, US & motion capture), which may improve the accuracy of the MA estimate. The purpose of this paper is to present the hybrid methodology and validation results based on testing the method using an animal model.
Comparison of In Vitro and In Vivo Testing of Fluid Diodes as a Pulmonary Heart Valve Replacement
Authors: Camp Tiffany , Figliola Richard , McQuinn Tim , Hsia T.-Y. , Conover Tim
Published: March 2014

The operating pressures in the right heart are significantly lower than those of the left heart and with marked differences in the circulation impedances. The pulmonary circulation shows a tolerance for mild regurgitation and pressure gradient [1]. Pulmonary regurgitation fractions on the order of 20% and transvalvular pressure gradients of less than 25mm Hg are considered mild [2]. Given this tolerance, we examine the concept of using a motionless valve to regulate flow in the pulmonary position. In a previous study, the use of fluid diodes was shown to be a promising concept for use as a pulmonary valve [3]. In this study, we test a fluid diode both in a bench top circulatory system [4] and in a swine model and compare the pressure gradients and regurgitant fractions.
A Volume Fraction Based Two-Phase Constitutive Model for Blood
Authors: Zhao Rui , Massoudi Mehrdad , Hund Samuel J. , Antaki James F.
Published: March 2014

Mechanically-induced blood trauma such as hemolysis and thrombosis often occurs at microscopic channels, steps and crevices within cardiovascular devices. A predictive mathematical model based on a broad understanding of hemodynamics at micro scale is needed to mitigate these effects, and is the motivation of this research project.
Role of Mechanical Forces in Endothelial Homeostasis
Authors: Chien Shu
Published: March 2014

Shear stress and stretch can modulate functions of vascular endothelial cells (ECs) by activating mechano-sensors, signaling pathways, and gene/protein expressions. Sustained shear stress with a forward direction causes only a transient activation of atherogenic genes, followed by down-regulation. In ECs exposed to complex flow with little forward direction, activation of these atherogenic genes is sustained, and cell turnover is accelerated. Cyclic uniaxial stretch causes orientation of actin stress fibers perpendicular to stretch direction, and this causes a decrease of intracellular stress, transient JNK activation, and protection of ECs against apoptosis. Cyclic biaxial stretch without a preferred direction has opposite effects. In the straight arteries, laminar shear stress with a forward direction and uniaxial strain with a circumferential direction have anti-atherogenic effects. At branch points, the complex shear flow and mechanical strain with little net direction are atherogenic. The direction of mechanical forces has important effects on ECs in health and disease.
A Numerical and Experimental Study of Blood Disturbances in a Stented Arterial Segment: Flat vs. Cylindrical Mock-Ups
Authors: Mejia Juan , Mongrain Rosaire , Drapeau Guy , Cabau-Rodes Josep , Bertrand Olivier F.
Published: March 2014

Today cardiac complications are the leading cause of death in the developed world [1]. Millions of people suffer from cardiovascular disease, with most of the cases caused by or related to atherosclerosis. Historically, blood flow in stenosed arteries has been restored by means of balloon angioplasty. In 1987 stents were introduced to the procedure in order to provide structural support to the diseased artery.
Force Recovery After Activated Stretching in Whole Skeletal Muscle: Transient Aspects of Force Enhancement
Authors: Koppes Ryan A. , Corr David T.
Published: March 2014

The enhancement of isometric force after active stretching is a well-accepted and demonstrated characteristic of skeletal muscle in both whole muscle [1,2] and single-fiber preparations [1,3], but its mechanisms remain unknown. Although traditionally analyzed at steady-state, transient phenomena caused, at least in part, by cross-bridge kinetics may provide novel insight into the mechanisms associated with force enhancement (FE). In order to identify the transient aspects of FE and its relation to stretching speed, stretching amplitude, and muscle mechanical work, a post hoc analysis of in situ experiments in soleus muscle tendon units of anesthetized cats [2] was conducted. The period immediately following stretching, at which the force returns to steady-state, was fit using an exponential decay function. The aims of this study were to analyze and quantify the effects of stretching amplitude, stretching speed, and muscle mechanical work on steady-state force enhancement (FEss) and transient force relaxation rate after active stretching. The results of this study were interpreted with respect to prior force depression (FD) experiments [4], to identify if the two phenomena exhibited similar transient and steady-state behaviors, and thus could be described by the same underlying mechanism(s).
The St. Petersburg Wrist: A Prototype Powered Flexion Wrist Unit
Authors: De Laurentis Kathryn J. , Phillips Sam L.
Published: March 2014

This is the presentation of a prototype wrist, which has powered rotation and flexion. Powered flexion is an important addition to an externally powered prosthesis. Flexion and extension, along with rotation give the prosthesis two additional degrees of freedom, which when added to degrees of freedom for the shoulder and elbow yield a six-degree of freedom system. Six-degrees of freedom are important because they allow placement of the hand throughout the entire workspace. Without flexion, amputees cannot reach some positions, and must use compensatory motions for many other movements.
The Importance of Proliferation of the Arterial Wall in Formation of Saccular Cerebral Aneurysms
Authors: Shimogonya Y. , Ishikawa T. , Imai Y. , Mori D. , Yamaguchi T.
Published: March 2014

Cerebral aneurysms are an important cerebrovascular condition because aneurysm rupture is the most common cause of subarachnoid hemorrhage, which has a high mortality rate and a poor prognosis. Since the mechanism of cerebral aneurysm pathogenesis has not yet been understood, the preventative treatment for unruptured aneurysms is surgery only; however, the morbidity of the surgery is as high as over 10% [1]. On the other hand, the annual risk of rupture of cerebral aneurysms is not so high, reported to be 1.9% [2]. Consequently, it is difficult to judge whether a patient with an unruptured cerebral aneurysm should undergo surgery, when it is detected. Thus, it is important to develop a better understanding of the mechanism of cerebral aneurysm pathogenesis.
Simulation of the Transverse Fractures of the Sacrum Using a Finite Element Model of Lumbar Spine-Pelvis Segment
Authors: Ivanov A. , Kiapour A. , Ebraheim N. , Goel V. K.
Published: March 2014

The sacrum fractures are very severe trauma which frequently accompanied with lumbar spine fractures. The surgical procedures often require primary stabilization of both lumbar spine and sacrum. To understand the rationale of the instrumentation numerous cadaveric studies were conducted to elucidate the anatomy of fractures and treatment options [1,2,3]. The modern computer technology allowed simulating the fractures and repairing using the Finite Element Analysis, also [4,5]. The last method has a raw of advantages versus cadaveric method such as higher reliability, accuracy, and safety. Finite element investigations of the pelvic fractures allowed comparing the influence of implants on pelvis stability. However, the extensive search of the literature failed to find a finite element model which includes the pelvis and lumbar spine together. Current study is the first step to accomplish this goal. An experimentally validated model of ligamentous lumbar spine was combined with the FE model of pelvis [7], and simulation of the sacrum fractures was conducted.
Stem Cells and Vascular Regenerative Medicine
Authors: Ahsan Taby , Doyle Adele M. , Duffy Garry P. , Barry Frank , Nerem Robert M.
Published: March 2014

Vascular applications in regenerative medicine include blood vessel substitutes and vasculogenesis in ischemic or engineered tissues. For these repair processes to be successful, there is a need for a stable supply of endothelial and smooth muscle cells. For blood vessel substitutes, the immediate goal is to enable blood flow, but vasoactivity is necessary for long term success. In engineered vessels, it is thought that endothelial cells will serve as an anti-thrombogenic lumenal layer, while smooth muscle cells contribute to vessel contractility. In other clinical applications, what is needed is not a vessel substitute but the promotion of new vessel formation (vasculogenesis). A simplified account of vasculogenesis is that endothelial cells assemble to form vessel-like structures that can then be stabilized by smooth muscle cells. Overall, the need for new vasculature to transfer oxygen and nutrients is important to reperfuse not only ischemic tissue in vivo, but also dense, structurally complex engineered tissue. The impact of these vascular therapies, however, is limited in part by the low yield and inadequate in vitro proliferation potential of primary endothelial and smooth muscle cells. Thus, there is a need to address the cell sourcing issue for vascular cell-based therapies, potentially using stem cells.
Simplicity amid Complexity
Authors: Held Isaac
Published: March 2014

Despite the complexity of Earth's climate system, the influence of human activities on climate can be identified and predicted.
The Parable of Google Flu: Traps in Big Data Analysis
Authors: Lazer David , Kennedy Ryan , King Gary , Vespignani Alessandro
Published: March 2014

Large errors in flu prediction were largely avoidable, which offers lessons for the use of big data.
Society, Where None Intrudes
Authors: Godfray H. Charles J.
Published: March 2014

A field study reveals an intricate tropical community of plants, herbivores, and parasitoids.

[Also see Report by

Condon
et al.

]
How Earth Can Cool Without Plunging Into a Deep Freeze
Authors: Kerr Richard A.
Published: March 2014

A geochemical model published online this week in
Science
suggests that Earth's temperature controls have built-in restraints, rooted in the chemistry of rock and flowing water, that have kept the planet habitable for eons.
Water's Tough Skin
Authors: Pennisi Elizabeth
Published: March 2014

Surface tension is a force to be reckoned with, especially if you are small.
Routine Testing for Anaerobic Bacteria in Cerebrospinal Fluid Cultures Improves Recovery of Clinically Significant Pathogens
Authors: Pittman Meredith E. , Thomas Benjamin S. , Wallace Meghan A. , Weber Carol J. , Burnham Carey-Ann D.
Published: March 2014

In North America, the widespread use of vaccines targeting
Haemophilus influenzae
type b and
Streptococcus pneumoniae
have dramatically altered the epidemiology of bacterial meningitis, while the methodology for culturing cerebrospinal fluid (CSF) specimens has remained largely unchanged. The aims of this study were 2-fold: to document the current epidemiology of bacterial meningitis at a tertiary care medical center and to assess the clinical utility of routinely querying for anaerobes in CSF cultures. To that end, we assessed CSF cultures submitted over a 2-year period. A brucella blood agar (BBA) plate, incubated anaerobically for 5 days, was included in the culture procedure for all CSF specimens during the second year of evaluation. In the pre- and postimplementation years, 2,353 and 2,302 CSF specimens were cultured, with 49 and 99 patients having positive culture results, respectively. The clinical and laboratory data for patients with positive cultures were reviewed. Anaerobic bacteria were isolated in the CSF samples from 33 patients post-BBA compared to two patients pre-BBA (
P
= 0.01). The anaerobic isolates included
Bacteroides thetaiotaomicron
(
n
= 1),
Propionibacterium
species (
n
= 15), and
Propionibacterium acnes
(
n
= 19) isolates; all of these isolates were recovered on the BBA. Eight of the 35 patients from whom anaerobic organisms were isolated received antimicrobial therapy. Although six of these patients had central nervous system hardware, two patients did not have a history of a neurosurgical procedure and had community-acquired anaerobic bacterial meningitis. This study demonstrates that the simple addition of an anaerobically incubated BBA to the culture of CSF specimens enhances the recovery of clinically significant anaerobic pathogens.
Clinical Evaluation of the Walk-Away Specimen Processor and ESwab for Recovery of Streptococcus agalactiae Isolates in Prenatal Screening Specimens
Authors: Buchan Blake W. , Olson Wendy J. , Mackey Tami-Lea A. , Ledeboer Nathan A.
Published: March 2014

Rectal/vaginal specimens (
n
= 97) were collected in parallel using ESwab and Liquid Stuart (LS) rayon fiber wrapped swab collection devices. Each collection device was used to directly inoculate culture medium and LIM broth. Medium inoculation by ESwab was conducted using the Walk-Away specimen processor (WASP). Medium inoculation by the LS device was conducted manually. The sensitivities of ESwab and LS upon direct plating were 93.8% and 87.5%, respectively, and increased to 96.9% and 90.6%, respectively, following broth enrichment.
Adjunctive
mecA
PCR for Routine Detection of Methicillin Susceptibility in Clinical Isolates of Coagulase-Negative Staphylococci
Authors: Nijjar Chandanjit Kaur , Smith Melvyn Howard , Eltringham Ian Joseph
Published: March 2014

Concerns over the reliability of routine sensitivity testing in coagulase-negative staphylococci often lead to the use of potentially less-effective antibiotics as few laboratories have access to routine tests for the
mecA
resistance gene. Although previous studies have shown a reasonable correlation between oxacillin disc and automated sensitivity testing, changing epidemiology and methodology dictate periodic reappraisal of these methods. In the present study, we evaluated two real-time PCR assays against novel targets in the
mecA
gene as an adjunct to routine susceptibility testing using the Vitek II AST-P620 card. All samples were further examined for the presence of the
mecC
gene. Of 118 strains of coagulase-negative staphylococci tested, 81 were oxacillin resistant and 37 oxacillin susceptible by the Vitek II assay compared with 103 positive and 15 negative by
mecA
PCR. In-house PCR results correlated well with a previously published reference PCR, though little correlation was found between
mecA
PCR or Vitek II and PBP 2a latex agglutination. Incubation conditions may have affected the accuracy of the latter test. None of the strains tested were
mecC
PCR positive. The inclusion of dual-target PCRs in the testing algorithm was inexpensive and offered the safest strategy for determining beta-lactam susceptibility in coagulase-negative staphylococci in our laboratory.
Single-Locus-Sequence-Based Typing of
bla
OXA-51-like
Genes for Rapid Assignment of Acinetobacter baumannii Clinical Isolates to International Clonal Lineages
Authors: Pournaras Spyros , Gogou Vasiliki , Giannouli Maria , Dimitroulia Evangelia , Dafopoulou Konstantina , Tsakris Athanasios , Zarrilli Raffaele
Published: March 2014

Single-locus
bla
OXA-51-like
sequence-based typing (SBT) was evaluated for its ability to determine correctly sequence types (STs) in
Acinetobacter baumannii
clinical isolates, in comparison with the Pasteur's multilocus sequence typing (MLST) reference method and 3-locus sequence typing (3-LST). The comparative study was performed in 585 multidrug-resistant (MDR)
A. baumannii
clinical isolates recovered from 21 hospitals located throughout Greece, Italy, Lebanon, and Turkey. The isolates belonged to nine clonal complexes (CCs) that correspond to 12 distinct sequence types (STs) and to one singleton ST. These clonal lineages predominate worldwide among nosocomial MDR
A. baumannii
strains. The most common clone was CC2 (ST2 and ST45;
n
= 278 isolates) followed by CC1 (ST1 and ST20;
n
= 155), CC25 (
n
= 65), ST78 (
n
= 62), CC15 (ST15 and ST84;
n
= 9), CC10 (
n
= 4), CC3 (
n
= 4), CC6 (
n
= 3), CC54 (
n
= 3), and CC83 (
n
= 2). Using the
bla
OXA-51-like
SBT method, all 585 isolates of the study were typed and assigned correctly to the nine CCs and the singleton ST78. The 3-LST method was not able to classify isolates belonging to CC6, CC10, CC54, and CC83, which are not yet characterized in its database. The low-cost and convenient
bla
OXA-51-like
SBT method, compared with 3-LST and MLST, discriminated all epidemic and sporadic lineages of our collection and could be effectively applied to type rapidly
A. baumannii
strains.
HIV-1 Vpu Antagonism of Tetherin Inhibits Antibody-Dependent Cellular Cytotoxic Responses by Natural Killer Cells
Authors: Alvarez Raymond A. , Hamlin Rebecca E. , Monroe Anthony , Moldt Brian , Hotta Mathew T. , Rodriguez Caprio Gabriela , Fierer Daniel S. , Simon Viviana , Chen Benjamin K.
Published: March 2014

The type I interferon-inducible factor tetherin retains virus particles on the surfaces of cells infected withvpu-deficient human immunodeficiency virus type 1 (HIV-1). While this mechanism inhibits cell-free viral spread, the immunological implications of tethered virus have not been investigated. We found that surface tetherin expression increased the antibody opsonization ofvpu-deficient HIV-infected cells. The absence of Vpu also stimulated NK cell-activating FcγRIIIa signaling and enhanced NK cell degranulation and NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). The deletion ofvpuin HIV-1-infected primary CD4+T cells enhanced the levels of antibody binding and Fc receptor signaling mediated by HIV-positive-patient-derived antibodies. The magnitudes of antibody binding and Fc signaling were both highly correlated to the levels of tetherin on the surfaces of infected primary CD4 T cells. The affinity of antibody binding to FcγRIIIa was also found to be critical in mediating efficient Fc activation. These studies implicate Vpu antagonism of tetherin as an ADCC evasion mechanism that prevents antibody-mediated clearance of virally infected cells.

IMPORTANCEThe ability of the HIV-1 accessory factor to antagonize tetherin has been considered to primarily function by limiting the spread of virus by preventing the release of cell-free virus. This study supports the hypothesis that a major function of Vpu is to decrease the recognition of infected cells by anti-HIV antibodies at the cell surface, thereby reducing recognition by antibody-dependent clearance by natural killer cells.
Genome Segregation and Packaging Machinery in Acanthamoeba polyphaga Mimivirus Is Reminiscent of Bacterial Apparatus
Authors: Chelikani Venkata , Ranjan Tushar , Zade Amrutraj , Shukla Avi , Kondabagil Kiran
Published: March 2014

Genome packaging is a critical step in the virion assembly process. The putative ATP-driven genome packaging motor ofAcanthamoeba polyphagamimivirus (APMV) and other nucleocytoplasmic large DNA viruses (NCLDVs) is a distant ortholog of prokaryotic chromosome segregation motors, such as FtsK and HerA, rather than other viral packaging motors, such as large terminase. Intriguingly, APMV also encodes other components, i.e., three putative serine recombinases and a putative type II topoisomerase, all of which are essential for chromosome segregation in prokaryotes. Based on our analyses of these components and taking the limited available literature into account, here we propose for the first time a model for genome segregation and packaging in APMV that can possibly be extended to NCLDV subfamilies, except perhapsPoxviridaeandAscoviridae. This model might represent a unique variation of the prokaryotic system acquired and contrived by the large DNA viruses of eukaryotes. It is also consistent with previous observations that unicellular eukaryotes, such as amoebae, are melting pots for the advent of chimeric organisms with novel mechanisms.

IMPORTANCEExtremely large viruses with DNA genomes infect a wide range of eukaryotes, from human beings to amoebae and from crocodiles to algae. These large DNA viruses, unlike their much smaller cousins, have the capability of making most of the protein components required for their multiplication. Once they infect the cell, these viruses set up viral replication centers, known as viral factories, to carry out their multiplication with very little help from the host. Our sequence analyses show that there is remarkable similarity between prokaryotes (bacteria and archaea) and large DNA viruses, such as mimivirus, vaccinia virus, and pandoravirus, in the way that they process their newly synthesized genetic material to make sure that only one copy of the complete genome is generated and is meticulously placed inside the newly synthesized viral particle. These findings have important evolutionary implications about the origin and evolution of large viruses.
A Temporospatial Map That Defines Specific Steps at Which Critical Surfaces in the Gag MA and CA Domains Act during Immature HIV-1 Capsid Assembly in Cells
Authors: Robinson Bridget A. , Reed Jonathan C. , Geary Clair D. , Swain J. Victor , Lingappa Jaisri R.
Published: March 2014

During HIV-1 assembly, Gag polypeptides target to the plasma membrane, where they multimerize to form immature capsids that undergo budding and maturation. Previous mutational analyses identified residues within the Gag matrix (MA) and capsid (CA) domains that are required for immature capsid assembly, and structural studies showed that these residues are clustered on four exposed surfaces in Gag. Exactly when and where the three critical surfaces in CA function during assembly are not known. Here, we analyzed how mutations in these four critical surfaces affect the formation and stability of assembly intermediates in cells expressing the HIV-1 provirus. The resulting temporospatial map reveals that critical MA residues act during membrane targeting, residues in the C-terminal CA subdomain (CA-CTD) dimer interface are needed for the stability of the first membrane-bound assembly intermediate, CA-CTD base residues are necessary for progression past the first membrane-bound intermediate, and residues in the N-terminal CA subdomain (CA-NTD) stabilize the last membrane-bound intermediate. Importantly, we found that all four critical surfaces act while Gag is associated with the cellular facilitators of assembly ABCE1 and DDX6. When correlated with existing structural data, our findings suggest the following model: Gag dimerizes via the CA-CTD dimer interface just before or during membrane targeting, individual CA-CTD hexamers form soon after membrane targeting, and the CA-NTD hexameric lattice forms just prior to capsid release. This model adds an important new dimension to current structural models by proposing the potential order in which key contacts within the immature capsid lattice are made during assembly in cells.

IMPORTANCE
While much is known about the structure of the completed HIV-1 immature capsid and domains of its component Gag proteins, less is known about the sequence of events leading to formation of the HIV-1 immature capsid. Here we used biochemical and ultrastructural analyses to generate a temporospatial map showing the precise order in which four critical surfaces in Gag act during immature capsid formation in provirus-expressing cells. Because three of these surfaces make important contacts in the hexameric lattices that are found in the completed immature capsid, these data allow us to propose a model for the sequence of events leading to formation of the hexameric lattices. By providing a dynamic view of when and where critical Gag-Gag contacts form during the assembly process and how those contacts function in the nascent capsid, our study provides novel insights into how an immature capsid is built in infected cells.
Differential Sensitivities of Tetherin Isoforms to Counteraction by Primate Lentiviruses
Authors: Weinelt Julia , Neil Stuart J. D.
Published: March 2014

The mammalian antiviral membrane protein tetherin (BST2/CD317) can be expressed as two isoforms derived from differential translational initiation. The shorter isoform of the human protein (S-tetherin) lacks the first 12 amino acids of the longer (L-tetherin) cytoplasmic tail, which includes a tyrosine motif that acts as both an endocytic recycling signal and a determinant of virus-induced NF-κB activation. S-tetherin is also reported to be less sensitive to the prototypic viral antagonist human immunodeficiency virus type 1 (HIV-1) Vpu. Here we analyzed the relative sensitivities of L- and S-tetherins to primate lentiviral countermeasures. We show that the reduced sensitivity of S-tetherin to HIV-1 Vpu is a feature of all group M proteins, including those of transmitted founder viruses, primarily because it cannot be targeted for endosomal degradation owing to the truncation of its cytoplasmic tail. In contrast, both isoforms of the human and rhesus macaque tetherins display the same sensitivity to nondegradative lentiviral countermeasures of HIV-2 and SIVmac, respectively. Surprisingly, however, the Vpu proteins encoded by simian immunodeficiency viruses (SIVs) of African guenons, as well as that from recently isolated highly pathogenic HIV-1 group N, do not discriminate between tetherin isoforms. Together, these data suggest that the group M HIV-1 Vpu primarily adapted to target L-tetherin upon zoonotic transmission from chimpanzees, and further, we speculate that functions specifically associated with this isoform, such as proinflammatory signaling, play key roles in human tetherin's antiviral function
in vivo
.

IMPORTANCE
The ability of HIV-1 and related viruses to counteract a host antiviral protein, tetherin, is strictly maintained. The adaptation of the HIV-1 Vpu protein to counteract human tetherin is thought to have been one of the key events in the establishment of the HIV/AIDS pandemic. Recent evidence shows that tetherin is expressed as two isoforms and that Vpu preferentially targets the longer form. Here we show that unlike other virus-encoded countermeasures, such as those from primate viruses related to HIV-1, the enhanced ability to counteract the long tetherin isoform is conserved among HIV-1 strains that make up the majority of the human pandemic. This correlates with the ability of Vpu to induce long tetherin degradation. We speculate that functions associated with the human version of this isoform, such as an inflammatory signaling capacity, selected for Vpu's enhanced targeting of long tetherin during its adaptation to humans.
Left maxillary artery pseudoaneurysm: a rare and late postoperative complication after head and neck cancer treatment
Authors: Kamath Ganesh , Naalla Ravikiran , Pai Vasudev Baburaya , Narayanan Ramakrishna
Published: March 2014

We report a case of a 50-year-old man presented with pulsatile swelling in the left side of the face since 2 months and a continuous sinus discharge since 3 days. Three years earlier, he was operated for squamous cell carcinoma (SCC) of the left lower alveolus and underwent surgical excision with myocutaneous flap reconstruction, followed by chemoradiotherapy. CT angiogram of the expansile swelling revealed pseudoaneurysm of third part of the left maxillary artery and treated by surgical intervention.
Chest pain caused by pulmonary vein thrombi could be curable by dabigatran
Authors: Takeuchi Hidekazu
Published: March 2014

Chest pain is a common clinical event that overwhelms many patients and is often a sign of coronary ischaemia. The comprehensive influence of pulmonary vein thrombosis (PVT) on coronary artery ischaemia is underappreciated. A 64-slice multidetector CT (64-MDCT) scan can detect pulmonary vein thrombi. A 68-year-old man was referred for the assessment of recent chest pain. A 64-MDCT scan was performed to assess his coronary artery. Although the scan did not show a coronary artery plaque, it did show a thrombus in the right lower pulmonary vein. After 3 months of dabigatran therapy, some parts of the thrombus had dissolved, and the image of the thrombus was more vague. The darkness of the thrombus was lost, indicating that the thrombus had loosened in structure and that the contrast enhancements were able to penetrate into the thrombus. PVT was identified as the likely aetiology for the cause of the chest pain.
Semilobar holoprosencephaly with 21q22 deletion: an autopsy report
Authors: Mallick Saumyaranjan , Panda Shasanka Shekhar , Ray Ruma , Shukla Rashmi , Kabra Madhulika , Agarwal Ramesh
Published: March 2014

Holoprosencephaly (HPE) is the most common forebrain developmental anomaly with a prevalence of 1:16 000 live-births. Possible aetiological agents include environmental factors and genetic defects such as trisomies (13, 18) and deletions (18p, 7q, 2p and 21q). This complex malformation is due to incomplete division of the cerebral hemisphere. The phenotypes of HPE include alobar, semilobar, lobar and midline interhemispheric fusion variants. Craniofacial anomalies occur in 80% of cases. Severely affected babies die in the neonatal period. Here we report an autopsied case of semilobar HPE with pituitary and adrenal agenesis with 21q22 deletion. Additional findings are noted that would help expand the spectrum of 21q22 deletion.
Conventional endovascular treatment of small intracranial aneurysms is not associated with additional risks compared with treatment of larger aneurysms
Authors: Stetler William R , Wilson Thomas J , Al-Holou Wajd N , Chaudhary Neeraj , Gemmete Joseph J , Thompson B Gregory , Pandey Aditya S
Published: March 2014

Background

Endovascular treatment of small intracranial aneurysms has historically been technically challenging and has been associated with high rates of complications and intraprocedural rupture. In this study, we compared complication and recurrence rates for treatment of small aneurysms (≤4 mm) versus large aneurysms in the context of the advent of improvements in endovascular techniques and technologies.

Methods

A retrospective cohort study was performed to include all patients who underwent coiling of an intracranial aneurysm between 2005 and 2012. Small aneurysms were defined as any aneurysm 4.0 mm or smaller in all dimensions. The primary outcome was a composite outcome of the occurrence of an intraoperative rupture or a perioperative thromboembolic event. The secondary outcome of interest was aneurysm recurrence.

Results

During the study period, 483 patients were treated using endovascular techniques; 85 (17.6%) of these patients had small aneurysms. In the small aneurysm group, there was only one (1.2%) intraoperative rupture, three (3.5%) perioperative thromboembolic events, and 11 (12.9%) incidents of aneurysm recurrence. Both the primary and secondary outcomes of interest were similar in patients presenting with small or large aneurysms. Small aneurysm size was not a risk factor for either the composite primary outcome or aneurysm recurrence in multivariate analysis.

Conclusions

Treatment of small intracranial aneurysms via conventional endovascular coiling techniques is not inferior to endovascular treatment of larger aneurysms based on our single institution experience. While technically challenging, such aneurysms may be treated safely and effectively with acceptable rates of complications and recurrence.
Group reduction factors for analysis of laterally loaded pile groups
Authors: Fayyazi M. Sajjad , Taiebat Mahdi , Finn W.D. Liam
Published: March 2014

The lateral response of piles embedded in soil is typically analyzed using the beam on nonlinear Winkler springs approach, in which soil–pile interaction is modeled by nonlinear p–y curves (where p is soil resistance and y is horizontal displacement). In this approach, one of the most common methods of accounting for interaction effects in pile groups is to modify the single pile p–y curves using a p-multiplier for each row of piles in the group, with higher values for leading row and lower values for trailing rows. The leading and trailing rows interchange during seismic loading; therefore, sometimes an average p-multiplier is used for all piles in the group. This average p-multiplier is called the group reduction factor. Group reduction factors have been established from experimental data from static loading tests on small pile groups, mostly 3 × 3 groups with free pile head conditions and center-to-center pile spacings of about 3 pile diameters. In this paper, continuum simulations are used to study the group reduction factors in 3 × 3 to 6 × 6 square pile groups subjected to static loading. The study includes the effects of various parameters, including pile spacing, pile head condition, and the friction angle of soil, on the group reduction factors. Calculated group reduction factors from this study compare well with available group test data, that is, typically small pile groups. However, the study shows that design guidelines such as the American Association of State Highway and Transportation Officials (AASHTO) and Federal Emergency Management Agency (FEMA) P-751 overestimate the group reduction factors, hence the lateral resistance, in larger pile groups and larger spacings, especially for fixed pile head conditions.
Behaviour of H-piles supporting an integral abutment bridge
Authors: Huntley Shelley A. , Valsangkar Arun J.
Published: March 2014

Integral abutment bridges accommodate thermal superstructure movements through flexible foundations rather than expansion joints. While these structures are a common alternative to conventional design, the literature on measured field stresses in piles supporting integral abutments appears to be quite limited. Therefore, field data from strain gauges installed on the abutment foundation piles of a 76 m long; two-span integral abutment bridge are the focus of this paper. Axial load, weak- and strong-axis bending moments of the foundation piles, as well as abutment movement and backfill response, are presented and discussed. Results indicate that the abutment foundation piles are bending in double curvature about the weak axis, as a result of thermal bridge movements, and bending also about the strong axis due to tilting of the abutments. A simple subgrade modulus approach is used to show its applicability in predicting behaviour under lateral loading. In the past, much emphasis has been placed on the lateral displacements of piles and less on variations of axial load. In this paper, a new hypothesis, which offers insight into the mechanisms behind the observed thermal variations in axial load, is proposed and assessed. The data from the field monitoring are also compared with the limited data reported in the literature.
Ab initio study of structural, electronic, magnetic and optical properties of Ti-doped ZnTe and CdTe
Authors: El Amine Monir M. , Baltache H. , Murtaza G. , Khenata R. , Bin Omran S. , Uğur Ş. , Benalia S. , Rached D.
Published: March 2014

The full potential linearized augmented plane wave method within the framework of density functional theory (DFT) is employed to investigate the structural, magnetic, electronic and optical properties of Ti -doped ZnTe and CdTe in the zinc blende phase. In this approach the local spin density approximation (LSDA) is used for the exchange-correlation (XC) potential. Results are provided for the lattice constant, bulk modulus, pressure derivative, magnetic moment, band structure, density of states and refractive indices. Our results are compared with other theoretical works and good agreement is shown.
Partial melting of oceanic gabbro triggered by migrating water-rich fluids: a prime example from the Oman Ophiolite
Authors: Koepke J. , Berndt J. , Horn I. , Fahle J. , Wolff P. E.
Published: March 2014

Detailed backscattered electron (BSE) and cathodoluminescence (CL) observations in an olivine gabbro from the Wadi Rajmi of the Fizh Block of the Oman Ophiolite revealed that this gabbro represents a perfect example of a partial melting reaction. The observed microtextures imply that water-rich fluids migrated on grain boundaries in a ductile regime, causing an incongruent partial melting reaction. All grain boundaries between primary plagioclases are characterized by
c.
50 µm thick haloes of Anorthite-rich (An) plagioclase, with An contents which are
c.
10 mol higher compared to the host plagioclase composition. Where these An-rich zones are in contact with the mafic primary minerals (olivine, clinopyroxene) in places, reactive rims of orthopyroxene and pargasitic amphibole around the primary mafic silicates have been formed.
In situ
analyses of
87
Sr/
86
Sr isotope ratios on primary plagioclases and on An-enriched zones along grain boundaries revealed no significant difference, implying that the water/rock ratio was very low during the fluid–rock interaction. The observed features imply a model of hydrothermal activity proceeding on grain boundaries within the deep oceanic crust at very high temperatures (900–1000 °C) without any crack system, a prerequisite in current models to enable hydrothermal circulation. Interconnected porosity is generated by coupled dissolution–reprecipitation which allows pervasive fluid transport through the minerals at the grain boundaries, establishing a novel type of hydrothermal circulation maintaining water–rock interaction at very high temperatures in the ductile regime. The presence of isolated product phases as inclusions within the parent minerals emphasizes the importance of an interconnecting fluid establishing local equilibrium between parent and product phases of the incongruent melting reaction.
Structural control on chromitite deposits in ophiolites: the Oman case
Authors: Boudier Françoise , Al-Rajhi Ali
Published: March 2014

Chromitite genesis in ophiolites is indirectly related to spreading rate, controlling mantle fertility and depth of melt crystallization. The most favourable conditions for chromitite concentrations are found in ophiolites generated at moderate spreading rates, where the world's largest chromitite deposits reside. A huge extension of the Oman Ophiolite permits an overview of chromitite distribution in relation to ridge tectonics, yielding constraints on ophiolitic chromitite genesis. Chromite genesis requires large instantaneous melt delivery, coupled with increasing oxygen fugacity produced by hydrous fluids. Chromitites in the Oman Ophiolite reside either in the Moho Transition Zone or at depth in the mantle, along wide shear zones. Both locations are domains of large melt transfer. Thinner crust on top of mantle diapirs and large shear zones limiting propagating segments represent particular domains where seawater circulation at depth is favoured. The thermal structure of these domains may explain the preferential formation of Al-rich versus Cr-rich chromites. A frozen equilibrium with parent mid-ocean ridge basalt (MORB) in the Al-rich chromites could result from rapid cooling of chromitites formed close to the ridge axis. Alternatively, equilibrium with primitive melt and a variable oxidation state is explained here by fluid circulation along the shear zones, active during transition from spreading to detachment.
Conditioned medium from Bifidobacteria infantis protects against Cronobacter sakazakii-induced intestinal inflammation in newborn mice
Authors: Weng Meiqian , Ganguli Kriston , Zhu Weishu , Shi Hai Ning , Walker W. Allan
Published: March 2014

Necrotizing enterocolitis (NEC) is associated with a high morbidity and mortality in very low birth weight infants. Several hypotheses regarding the pathogenesis of NEC have been proposed but to date no effective treatment is available. Previous studies suggest that probiotic supplementation is protective. We recently reported that probiotic ( Bifidobacterium infantis) conditioned medium (PCM) has an anti-inflammatory effect in cultured fetal human intestinal cells (H4) and fetal intestine explants. In this study, we tested in vivo whether PCM protects neonatal mice from developing intestinal inflammation induced by exposure to Cronobacter sakazakii ( C. sakazakii), an opportunistic pathogen associated with NEC. We found that infected neonatal mice had a significantly lower body weight than control groups. Infection led to ileal tissue damage including villous rupture, disruption of epithelial cell alignment, intestinal inflammation, apoptotic cell loss, and decreased mucus production. Pretreatment with PCM prevented infection caused decrease in body weight, attenuated enterocyte apoptotic cell death, mitigated reduced mucin production, and maintained ileal structure. Infected ileum expressed reduced levels of IκBα, which could be restored upon pretreatment with PCM. We also observed a nuclear translocation of NF-κB p65 in H4 cells exposed to C. sakazakii, which was prevented in PCM-pretreated cells. Finally, treatment of neonatal mice with PCM prior to infection sustained the capacity of ileal epithelial proliferation. This study suggests that an active component(s) released into the culture medium by B. infantis may prevent ileal damage by a pathogen linked to NEC.
L-type calcium channel-dependent inhibitory plasticity in the thalamus
Authors: Hulme Sarah R. , Connelly William M.
Published: March 2014

Thalamocortical neurons integrate sensory and cortical activity and are regulated by input from inhibitory neurons in the thalamic reticular nucleus. Evidence suggests that during bursts of action potentials, dendritic calcium transients are seen throughout the dendritic tree of thalamocortical cells. Here, we review a recent study that suggests these calcium transients regulate inhibitory input, and we attempt to reconcile studies that differ on which ion channels are the source of the calcium.
Short-Term and Procedural Memory for Colours and Inferior Temporal Cortex Activity
Authors: Castro-Sierra E. , Paredes-Díaz E. , Lazareff J. A.
Published: March 2014

Two children (male, 10 years, and female, 13 years one month) with tumours of the inferior temporal (IT) cortex of the brain were studied post-surgically for their abilities to carry out a short-term memory test. This involved: differences in colour, number and shape of small plastic objects; differences in receptacles where these objects should be placed and in ways in which this placement should be done; a procedural task involving differences either in colour or in size of wooden rings employed in the task. Their performances in these tests, and those of patients with tumours of other encephalic areas, were compared with the performances of normal controls. The subjects with IT tumours spent a significantly greater amount of time than normal subjects of their age in carrying out the procedural task involving differences in colour. One of the IT subjects also spent a significantly greater amount of time in the procedural task involving size differences. Other differences in the performances of patients with encephalic tumours and the performances of normal controls were not significant. Results are discussed in relation to findings of colour and size perception and memory localized to the inferior temporal and middle temporal cortices.
Second-Order Nonlinear Analysis of Steel Tapered Beams Subjected to Span Loading
Authors: Hadidi Ali , Azar Bahman Farahmand , Marand Hossein Zonouzi
Published: March 2014

A second-order elastic analysis of tapered steel members with I-shaped sections subjected to span distributed and concentrated loadings is developed. Fixed end forces and moments as well as exact stiffness matrix of tapered Timoshenko-Euler beam are obtained with exact geometrical properties of sections. The simultaneous action of bending moment, shear, and axial force including P−δ effects is also considered in the analysis. A computer code has been developed in MATLAB software using a power series method to solve governing second-order differential equation of equilibrium with variable coefficients for beams with distributed span loading. A generalized matrix condensation technique is then utilized for analysis of beams with concentrated span loadings. The accuracy and efficiency of the results of the proposed method are verified through comparing them to those obtained from other approaches such as finite element methods, which indicates the robustness and time saving of this method even for large scale frames with tapered members.
Imhotep and the Discovery of Cerebrospinal Fluid
Authors: Blomstedt Patric
Published: March 2014

Herbowski (2013) suggested recently the Egyptian Imhotep from the 3rd dynasty in Egypt to be the discoverer of cerebrospinal fluid. There are, however, no sources within the first 2000 years after Imhotep suggesting him to be in any way connected with the field of medicine. Over the course of three millennia Imhotep evolves into the sage who besides architecture also masters the arts of medicine, magic, astronomy, and astrology, at the same time as him being transformed from man to demi-God, and finally to a God. The identification of Imhotep as a doctor has thus little to do with facts and it is unlikely that he had anything to do with the Edwin-Smith papyrus from a much later period where CSF is first mentioned.