bluuebunny/crossref_metadata_2025_split huggingface dataset:
Contrast-enhanced peripheral MRA: technique and contrast agents
Authors: Nielsen Yousef W , Thomsen Henrik S 
Published: July 2012

In the last decade contrast-enhanced magnetic resonance angiography (CE-MRA) has gained wide acceptance as a valuable tool in the diagnostic work-up of patients with peripheral arterial disease. This review presents current concepts in peripheral CE-MRA with emphasis on MRI technique and contrast agents. Peripheral CE-MRA is defined as an MR angiogram of the arteries from the aortic bifurcation to the feet. Advantages of CE-MRA include minimal invasiveness and lack of ionizing radiation. The basic technique employed for peripheral CE-MRA is the bolus-chase method. With this method a paramagnetic MRI contrast agent is injected intravenously and T1-weighted images are acquired in the subsequent arterial first-pass phase. In order to achieve high quality MR angiograms without interfering venous contamination or artifacts, a number of factors need to be taken into account. This includes magnetic field strength of the MRI system, receiver coil configuration, use of parallel imaging, contrast bolus timing technique, and k-space filling strategies. Furthermore, it is possible to optimize peripheral CE-MRA using venous compression techniques, hybrid scan protocols, time-resolved imaging, and steady-state MRA. Gadolinium(Gd)-based contrast agents are used for CE-MRA of the peripheral arteries. Extracellular Gd agents have a pharmacokinetic profile similar to iodinated contrast media. Accordingly, these agents are employed for first-pass MRA. Blood-pool Gd-based agents are characterized by prolonged intravascular stay, due to macromolecular structure or protein binding. These agents can be used for first-pass, as well as steady-state MRA. Some Gd-based contrast agents with low thermodynamic stability have been linked to development of nephrogenic systemic fibrosis in patients with severe renal insufficiency. Using optimized technique and a stable MRI contrast agent, peripheral CE-MRA is a safe procedure with diagnostic accuracy close to that of conventional catheter X-ray angiography.
Sclerosing angiomatoid nodular transformation of the spleen: clinical and radiologic characteristics
Authors: Kim Hyoung Jung , Kim Kyoung Won , Yu Eun Sil , Byun Jae Ho , Lee Seung Soo , Kim Jin Hee , Lee Jong Seok 
Published: July 2012

Background Sclerosing angiomatoid nodular transformation (SANT) is a rare benign primary vascular lesion of the spleen. Although there have been many reports about the pathology of SANTs of the spleen, there have been no comprehensive descriptions of the imaging findings of SANTs of the spleen. Purpose To determine the clinical characteristics and imaging findings of SANTs of the spleen. Material and Methods We retrospectively evaluated seven patients with pathologically confirmed SANT, who underwent CT ( n = 7), MRI ( n = 4), ultrasonography ( n = 4), and PET/CT ( n = 3). Follow-up CT examinations were obtained in five patients. Clinical characteristics such as symptoms and concurrent disease were assessed. CT and MRI findings were evaluated by two radiologists, including the number, border, signal intensity, enhancement pattern, hemorrhage, and cystic change or necrosis. The longest diameter of each tumor was measured on CT. Echogenicity on ultrasonography and standardized uptake value on PET/CT were also evaluated. Results No specific symptom was associated with SANT. Two patients had a history of malignancy, one with cervical cancer and the other with early gastric cancer. Tumor growth was observed in four of five patients. On CT, all seven SANTs appeared as single, well-demarcated masses. CT showed a heterogeneous enhancement in seven patients. MRI showed centripetal progressive enhancement and absence of cystic change or necrosis in four patients, with three of these patients showing evidence of old hemorrhage. Ultrasonography showed heterogeneous hypoechoic mass in four patients. PET/CT showed increased standardized uptake value, ranging from 2.0 to 2.8, in three patients. Conclusion SANT of the spleen is a single, well-demarcated solid mass without cystic change or necrosis. Increased FDG activity and tumor growth on follow-up imaging are common.
Assessment of paediatric CT dose indicators for the purpose of optimisation
Authors: Brady Z , Ramanauskas F , Cain T M , Johnston P N 
Published: July 2012

Objectives
To establish local diagnostic reference levels (LDRLs) at the Royal Children's Hospital (RCH) Melbourne, Parkville, Australia, for typical paediatric CT examinations and compare these with international diagnostic reference levels (DRLs) to benchmark local practice. In addition, the aim was to develop a method of analysing local scan parameters to enable identification of areas for optimisation.

Methods
A retrospective audit of patient records for paediatric CT brain, chest and abdomen/pelvis examinations was undertaken. Demographic information, examination parameters and dose indicators—volumetric CT dose index (CTDIvol) and dose–length product (DLP)—were collected for 220 patients. LDRLs were derived from mean survey values and the effective dose was estimated from DLP values. The normalised CTDIvol values, mAs values and scan length were analysed to better identify parameters that could be optimised.

Results
The LDRLs across all age categories were 18–45 mGy (CTDIvol) and 250–700 mGy cm (DLP) for brain examinations; 3–23 mGy (CTDIvol) and 100–800 mGy cm (DLP) for chest examinations; and 4–15 mGy (CTDIvol) and 150–750 mGy cm (DLP) for abdomen/pelvis examinations. Effective dose estimates were 1.0–1.6 mSv, 1.8–13.0 mSv and 2.5–10.0 mSv for brain, chest and abdomen/pelvis examinations, respectively.

Conclusion
The RCH mean CTDIvol and DLP values are similar to or lower than international DRLs. Use of low-kilovoltage protocols for body imaging in younger patients reduced the dose considerably. There exists potential for optimisation in reducing body scan lengths and justifying the selection of reference mAs values. The assessment method used here proved useful for identifying specific parameters for optimisation.

Advances in knowledge
Assessment of individual CT parameters in addition to comparison with DRLs enables identification of specific areas for CT optimisation.
Nanotopography-Guided Migration of T Cells
Authors: Kwon Keon Woo , Park Hyoungjun , Song Kwang Hoon , Choi Jong-Cheol , Ahn Hyungmin , Park Moon Jeong , Suh Kahp-Yang , Doh Junsang 
Published: July 2012

Abstract
T cells navigate a wide variety of tissues and organs for immune surveillance and effector functions. Although nanoscale topographical structures of extracellular matrices and stromal/endothelial cell surfaces in local tissues may guide the migration of T cells, there has been little opportunity to study how nanoscale topographical features affect T cell migration. In this study, we systematically investigated mechanisms of nanotopography-guided migration of T cells using nanoscale ridge/groove surfaces. The velocity and directionality of T cells on these nanostructured surfaces were quantitatively assessed with and without confinement, which is a key property of three-dimensional interstitial tissue spaces for leukocyte motility. Depending on the confinement, T cells exhibited different mechanisms for nanotopography-guided migration. Without confinement, actin polymerization-driven leading edge protrusion was guided toward the direction of nanogrooves via integrin-mediated adhesion. In contrast, T cells under confinement appeared to migrate along the direction of nanogrooves purely by mechanical effects, and integrin-mediated adhesion was dispensable. Therefore, surface nanotopography may play a prominent role in generating migratory patterns for T cells. Because the majority of cells in periphery migrate along the topography of extracellular matrices with much lower motility than T cells, nanotopography-guided migration of T cells would be an important strategy to efficiently perform cell-mediated immune responses by increasing chances of encountering other cells within a given amount of time.
Heligmosomoides polygyrus bakeri Induces Tolerogenic Dendritic Cells that Block Colitis and Prevent Antigen-Specific Gut T Cell Responses
Authors: Blum Arthur M. , Hang Long , Setiawan Tommy , Urban Joseph P. , Stoyanoff Korynn M. , Leung John , Weinstock Joel V. 
Published: July 2012

Abstract
Immunological diseases such as inflammatory bowel disease (IBD) are infrequent in less developed countries, possibly because helminths provide protection by modulating host immunity. In IBD murine models, the helminth Heligmosomoides polygyrus bakeri prevents colitis. It was determined whether H. polygyrus bakeri mediated IBD protection by altering dendritic cell (DC) function. We used a Rag IBD model where animals were reconstituted with IL10−/− T cells, making them susceptible to IBD and with OVA Ag-responsive OT2 T cells, allowing study of a gut antigenic response. Intestinal DC from H. polygyrus bakeri-infected Rag mice added to lamina propria mononuclear cells (LPMC) isolated from colitic animals blocked OVA IFN-γ/IL-17 responses in vitro through direct contact with the inflammatory LPMC. DC from uninfected Rag mice displayed no regulatory activity. Transfer of DC from H. polygyrus bakeri-infected mice into Rag mice reconstituted with IL10−/− T cells protected animals from IBD, and LPMC from these mice lost OVA responsiveness. After DC transfer, OT2 T cells populated the intestines normally. However, the OT2 T cells were rendered Ag nonresponsive through regulatory action of LPMC non-T cells. The process of regulation appeared to be regulatory T cell independent. Thus, H. polygyrus bakeri modulates intestinal DC function, rendering them tolerogenic. This appears to be an important mechanism through which H. polygyrus bakeri suppresses colitis. IFN-γ and IL-17 are colitogenic. The capacity of these DC to block a gut Ag-specific IFN-γ/IL-17 T cell response also is significant.
Olfactomedin 4 Inhibits Cathepsin C-Mediated Protease Activities, Thereby Modulating Neutrophil Killing of Staphylococcus aureus and Escherichia coli in Mice
Authors: Liu Wenli , Yan Ming , Liu Yueqin , McLeish Kenneth R. , Coleman William G. , Rodgers Griffin P. 
Published: July 2012

Abstract
Neutrophils kill bacteria generally through oxidative and nonoxidative mechanisms. Whereas much research has focused on the enzymes essential for neutrophil killing, little is known about the regulatory molecules responsible for such killing. In this study, we investigated the role of olfactomedin 4 (OLFM4), an olfactomedin-related glycoprotein, in neutrophil bactericidal capability and host innate immunity. Neutrophils from OLFM4−/− mice have increased intracellular killing of Staphylococcus aureus and Escherichia coli in vitro. The OLFM4−/− mice have enhanced in vivo bacterial clearance and are more resistant to sepsis when challenged with S. aureus or E. coli by i.p. injection. OLFM4 was found to interact with cathepsin C, a cysteine protease that plays an important role in bacterial killing and immune regulation. We demonstrated that OLFM4 inhibited cathepsin C activity in vitro and in vivo. The cathepsin C activity in neutrophils from OLFM4−/− mice was significantly higher than that in neutrophils from wild-type littermate mice. The activities of three serine proteases (neutrophil elastase, cathepsin G, and proteinase 3), which require cathepsin C activity for processing and maturity, were also significantly higher in OLFM4−/− neutrophils. The bacterial killing and clearance capabilities observed in OLFM4−/− mice that were enhanced relative to wild-type mice were significantly compromised by the additional loss of cathepsin C in mice with OLFM4 and cathepsin C double deficiency. These results indicate that OLFM4 is an important negative regulator of neutrophil bactericidal activity by restricting cathepsin C activity and its downstream granule-associated serine proteases.
Stability and Function of Secondary Th1 Memory Cells Are Dependent on the Nature of the Secondary Stimulus
Authors: Kim Chulwoo , Jay David C. , Williams Matthew A. 
Published: July 2012

Abstract
Following acute infection in some mouse models, CD4+ memory T cells steadily decline over time. Conversely, in humans, CD4+ memory T cells can be maintained for many years at levels similar to CD8+ T cells. Because we previously observed that the longevity of Th1 memory cell survival corresponded to their functional avidity, we hypothesized that secondary challenge, which enriches for high functional avidity Th1 responders, would result in more stable Th1 memory populations. We found that following a heterologous secondary challenge, Th1 memory cells were maintained at stable levels compared with primary Th1 memory cells, showing little to no decline after day 75 postinfection. The improved stability of secondary Th1 memory T cells corresponded to enhanced homeostatic turnover; enhanced trafficking of effector memory Th1 cells to tissue sites of infection, such as the liver; and acquisition or maintenance of high functional avidity following secondary challenge. Conversely, a weaker homologous rechallenge failed to induce a stable secondary Th1 memory population. Additionally, homologous secondary challenge resulted in a transient loss of functional avidity by Th1 memory cells recruited into the secondary response. Our findings suggest that the longevity of Th1 memory T cells is dependent, at least in part, on the combined effects of primary and secondary Ag-driven differentiation. Furthermore, they demonstrate that the quality of the secondary challenge can have profound effects on the longevity and function of the ensuing secondary Th1 memory population.
A TCR Affinity Threshold Regulates Memory CD4 T Cell Differentiation following Vaccination
Authors: Baumgartner Christina K. , Yagita Hideo , Malherbe Laurent P. 
Published: July 2012

Abstract
Diverse Ag-specific memory TCR repertoires are essential for protection against pathogens. Subunit vaccines that combine peptide or protein Ags with TLR agonists are very potent at inducing T cell immune responses, but their capacity to elicit stable and diverse memory CD4 T cell repertoires has not been evaluated. In this study, we examined the evolution of a complex Ag-specific population during the transition from primary effectors to memory T cells after peptide or protein vaccination. Both vaccination regimens induced equally diverse effector CD4 TCR repertoires, but peptide vaccines skewed the memory CD4 TCR repertoire toward high-affinity clonotypes whereas protein vaccines maintained low-affinity clonotypes in the memory compartment. CD27-mediated signaling was essential for the maintenance of low-affinity clonotypes after protein vaccination but was not sufficient to promote their survival following peptide vaccination. The rapid culling of the TCR repertoire in peptide-immunized mice coincided with a prolonged proliferation phase during which low-affinity clonotypes disappeared despite exhibiting no sign of enhanced apoptosis. Our study reveals a novel affinity threshold for memory CD4 T cell differentiation following vaccination and suggests a role for nonapoptotic cell death in the regulation of CD4 T cell clonal selection.
Integrin αXβ2 Is a Leukocyte Receptor forCandida albicansand Is Essential for Protection against Fungal Infections
Authors: Jawhara Samir , Pluskota Elzbieta , Verbovetskiy Dmitriy , Skomorovska-Prokvolit Olena , Plow Edward F. , Soloviev Dmitry A. 
Published: July 2012

AbstractThe opportunistic fungus Candida albicans is one of the leading causes of infections in immunocompromised patients, and innate immunity provides a principal mechanism for protection from the pathogen. In the present work, the role of integrin αXβ2 in the pathogenesis of fungal infection was assessed. Both purified αXβ2 and αXβ2-expressing human epithelial kidney 293 cells recognized and bound to the fungal hyphae of SC5314 strain of C. albicans but not to the yeast form or to hyphae of a strain deficient in the fungal mannoprotein, Pra1. The binding of the integrin to the fungus was inhibited by β-glucans but not by mannans, implicating a lectin-like activity in recognition but distinct in specificity from that of αMβ2. Mice deficient in αXβ2 were more prone to systemic infection with the LD50 fungal inoculum decreasing 3-fold in αXβ2-deficient mice compared with wild-type mice. After challenging i.v. with 1.5 × 104 cell/g, 60% of control C57BL/6 mice died within 14 d compared with 100% mortality of αXβ2-deficient mice within 9 d. Organs taken from αXβ2-deficient mice 16 h postinfection revealed a 10-fold increase in fungal invasion into the brain and a 2-fold increase into the liver. These data indicate that αXβ2 is important for protection against systemic C. albicans infections and macrophage subsets in the liver, Kupffer cells, and in the brain, microglial cells use αXβ2 to control fungal invasion.
Crystal Growth and Photoelectrochemical Characterization of Cd4BSe6 (B = Si or Ge)
Authors: Manivannan A. , Fujishima A. , Aravamudan G. , Rao G. V. Subba 
Published: July 2012

AbstractSingle crystals of Cd4BSe6 (B = Si, Ge) (ARGYRODITES) were grown by CVT method using a three zone furnace. As‐grown crystals were of n‐type and they have been characterized by photoelectrochemical (PEC) measurements in aqueous electrolytes. The current‐potential curves, Mott‐Schottky plots and action spectra were examined. From the analysis of spectral response measurements the band gaps (indirect) for Cd4SiSe6 and Cd4GeSe6 were found to be 1.68 and 1.5 eV, respectively. The opencircuit photopotentials for these semiconductor electrodes were as high as 1.1 V vs. SCE in some of the electrolytes used.
Flow Properties and Shear‐induced Structural Changes in Fluids: A Case Study on the Interplay between Theory, Simulation, Experiment and Application
Authors: Hess Siegfried , Loose Werner 
Published: July 2012

AbstractThe interrelation between the flow properties of fluids and the shear‐induced changes of their structure is discussed and the methods for their study are reviewed. The fruitful interaction between (conventional) theory, simulation, experiment and application is emphasized. Results are presented for simple fluids where the distortion of the local (short range) order, as described by the pair‐correlation function or the static structure factor, is found to be in good agreement with kinetic theory predictions. Experimental data are compared with results of nonequilibrium molecular dynamics (NEMD) computer simulations which are also used to study the non‐newtonian flow behavior of simple fluids. The spectacular long range positional order found in NEMD simulations at high shear rates is reviewed and interpreted as a hydrodynamic instability.
Self and Collective Diffusion Coefficients of Hard Sphere Suspensions
Authors: Cichocki B. , Hinsen K. 
Published: July 2012

AbstractWe present the results of a computer simulation of the dynamics of a hard sphere suspension without hydrodynamic interactions that was performed using an algorithm recently developed by the authors. The dynamical structure factors and the mean‐square displacement have been calculated for various volume fractions between 0.1 and 0.5. Is is shown that the temporal behaviour of the time derivative of the mean‐square displacement is very well described by the stretched exponential function exp(‐const.√t). It is also shown that the results for the dynamical structure factors almost perfectly agree with those of a theory combining in the proper way the Enskog term with the mode‐mode coupling term.
MD Simulation Results on the Dynamics in a Liquid‐Vapour Interface
Authors: And Amal Lotfi , Fischer Johann 
Published: July 2012

AbstractMolecular Dynamics simulations with vectorized codes on a CYBER 205 have been performed for the free liquid surface at three different temperatures. The particles passing through the Gibbs dividing surface and subsequently through a parallel control plane are counted which yields cumulative numbers for the particle trajectories of the following four types: evaporation, retention, condensation and reflection. It is observed that the particle fluxes leaving the Gibbs dividing surface are essentially due to either reflection or retention. This means that the particles can not so easily pass through the liquid‐vapour interface from one phase to the other.
Molecular Motion in Krypton Films Physisorbed on a Grooved Graphite Surface: A Computer Simulation Study
Authors: Bojan Mary J. , Steele William 
Published: July 2012

AbstractMolecular dynamics simulations of monolayers of krypton adsorbed on a heterogeneous graphite surface are reported. The heterogeneity is introduced by modeling a surface with parallel, straight‐walled grooves of depth ≃ 7 Å. The dynamical processes simulated included diffusion parallel to the surface; transfer between first layer atoms and the small amount of second layer adsorption that occurs at the simulation temperatures of 90, 110 and 140 K; and transfers between step and groove. Also considered was the special role played by the edge atoms adsorbed at the ledge between step and groove. Diffusion constants and transfer rates are reported and the results are discussed.
Isotope Effects upon Translational Diffusion as a Probe for Translation‐Rotation Coupling in Molecular Liquids
Authors: Holz M. , Weinärtner H. , Sacco A. 
Published: July 2012

AbstractMass changes of molecules caused by isotopic substitution (e.g. H‐D substitution) can change the dynamic properties of a molecular liquid. Up to now, these dynamic isotope effects have been investigated only for a very small number of liquids. In the present paper we report on isotope effects upon self‐diffusion coefficients, upon limiting tracer diffusion coefficients and upon viscosities of methanol, dimethylsulphoxide, dimethylformamide and nitromethane at 25°C. It is shown that the square‐root of mass dependence, which follows from a first theoretical approach, cannot predict the observed dynamic isotope effects. The experimental data correlate much better with the square root of the moments of inertia. Thus we establish a strong coupling between translational and rotational motion in these liquids. These results demonstrate that the dynamic isotope effects may serve as a sensitive probe for translation‐rotation coupling in molecular liquids. The experimental finding of translation‐rotation coupling is in agreement with recent computer simulations and has far consequences for the correct interpretation of liquid‐state spectra as e.g. far‐infrared absorption spectra.
Corresponding States Concept for Simple Supercooled Liquids Identifying a Change of Diffusion Mechanism above the Glass Transition Temperature
Authors: Rössler Ernst 
Published: July 2012

AbstractA corresponding states concept is applied to viscosity η and reorientational correlation times τ of simple supercooled liquids revealing a change of dynamics for a temperature Tc well above the glass transition temperature Tg. Reducing T by the minorly corrected Tg an improved master plot for the viscosity results. An universal behaviour is discovered above 103P whereas the viscosity follows individual curves below 103P. A power law, η = A (T — Tc), describes the individual curves with Tc = 1.18 Tg for all liquids. Above 103P several approaches are checked. For NMR correlation times plotted on such an improved scale the bifurcation of the correlation times for the β and α process appears at T/Tg = 1.18. The β process is an intrinsic feature of the universal viscous regime, only. The change of dynamics is also indicated by a breakdown of the Stokes‐Einstein relations. Comparing several supercooled liquids a discontinuity for τ/η and 1/(Dη) as a function of 1/T is found at T/Tg = 1.19–1.25. In addition, arguments are given which support a cease of anisotropic reorientation in the viscous regime. All together, these indications favour the concept of the recent mode coupling theory where a dynamical phase transition is predicted above Tg.