bluuebunny/crossref_metadata_2025 huggingface dataset:
Diagnostic accuracy of dual-time-point 18F-FDG PET/CT for the detection of axillary lymph node metastases in breast cancer patients
Authors: Hahn Steffen , Hecktor Jennifer , Grabellus Florian , Hartung Verena , Pöppel Thorsten , Kimmig Rainer , Forsting Michael , Antoch Gerald , Heusner Till A
Published: May 2012

Background

The diagnostic accuracy of FDG-PET/CT for the detection of axillary lymph node metastases in breast cancer patients acquired 60 min after FDG administration is reported to be only moderate, especially due to low sensitivity.

Purpose

To test whether a delayed scan 90 min after FDG administration could enhance the diagnostic accuracy of FDG-PET/CT for the detection of axillary lymph node metastases.

Material and Methods

Thirty-eight women suffering from primary breast cancer (mean age 52 years; range 25–78 years; standard deviation 14 years) underwent a pre-therapeutic dual-time-point FDG-PET/CT scan. The maximum standardized uptake value (SUVmax) of axillary lymph nodes was measured at two different time points (time point T1: 60 min after FDG injection, time point T2: 90 min after FDG injection). SUVmax of axillary lymph nodes at T1 and T2 were assessed for statistical significance using a paired Wilcoxon-Test ( P < 0.05). At T1 a qualitative analysis of the FDG-PET/CT scan was performed to define physiologic and metastatic lymph nodes. At T2 an increase of the SUVmax of at least 3.75% over time was rated as indicating malignancy. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the accuracy of FDG-PET/CT for the detection of axillary lymph node metastases was calculated at time points T1 and T2. Statistically significant differences were determined using Fisher's exact test ( P < 0.05). Histopathology served as the standard of reference. A compartment based analysis was done.

Results

Axillary lymph nodes had a mean SUVmax of 1.6 (range 0.6–10.8; SD 1.9) at T1 and a mean SUVmax of 1.8 (range 0.5–17.9; SD 3.5) at T2. This difference was statistically significant ( P = 0.047). The sensitivity, specificity, PPV, NPV, and accuracy of FDG-PET/CT for the detection of axillary lymph node metastases was 81%, 100%, 100%, 88%, and 92% at T1, and 88%, 50%, 56%, 85%, and 66% at T2, respectively. This difference was not statistically significant ( P = 0.27).

Conclusion

There is a slight increase of the FDG accumulation of axillary lymph nodes between 60 and 90 min after FDG administration. This increase did not translate into a statistical significant enhancement of the diagnostic accuracy of FDG-PET/CT for the detection of axillary lymph nodes. Especially due to false-positive results a delayed FDG-PET/CT scan 90 min after FDG administration is not able to enhance the diagnostic accuracy for the detection of lymph node metastases.
Transarterial chemoembolization for hepatocellular carcinoma after transjugular intrahepatic portosystemic shunt
Authors: Kang Ji-Won , Kim Jin Hyoung , Ko Gi-Young , Gwon Dong Il , Yoon Hyun-Ki , Sung Kyu-Bo
Published: May 2012

Background

The decreased portal blood flow and the potential decrease in arterial nutrient hepatic blood flow after creation of a transjugular intrahepatic portosystemic shunt (TIPS) makes the treatment of hepatocellular carcinoma (HCC) challenging.

Purpose

To evaluate the safety and efficacy of transarterial chemoembolization (TACE) after TIPS in patients with HCC.

Material and Methods

From 1998 to 2009, 20 patients underwent selective (segmental or subsegmental) TACE for HCC after TIPS. Among 20 patients, seven patients had undergone one to three sessions of TACE for HCC before TIPS creation. TACE was performed using a mixture of iodized oil and cisplatin, and absorbable gelatin sponge particles. Tumor response, complications, and patient survival were evaluated after TACE.

Results

After TACE, 14 of the 20 (70%) patients showed a tumor response, with only one (5%) experiencing a TACE-related major complication, spontaneous bacterial peritonitis. None of the patients who underwent TACE after TIPS died within 30 days. During the follow-up period (range 2.2–107 months; mean 32.6 months), 18 patients died and two remained alive. The median survival period after TACE was 23 months. Multivariate Cox regression analysis showed that tumor stage was the only independent prognostic factor for patient survival ( P = 0.049).

Conclusion

Selective TACE may be safe and effective for the palliative treatment of HCC in patients with TIPS. Late tumor stage ( ≥III) was poor prognostic factor for determining the patient survival period after post-TIPS TACE.
High frequency of activated natural killer and natural killer T-cells in patients with new onset of type 2 diabetes mellitus
Authors: Guo Hui , Xu Bingchuan , Gao Lichao , Sun Xiguang , Qu Xiaozhang , Li Xiaowei , Liu Shumei , Feng Junyan , Wang Juan , Tang Ying , Yan Guoqiang , Gao Xiuzhu , Jiang Yanfang
Published: May 2012

Chronic low-grade inflammation is crucial for the development of insulin resistance and type 2 diabetes mellitus (T2DM), and immunocompetent cells, such as T-cells, B-cells, mast cells and macrophages, regulate the pathogenesis of T2DM. However, little is known about the role of natural killer (NK) and natural killer T (NKT) cells in the pathogenic process of T2DM. A total of 16 patients with new onset T2DM and nine healthy subjects were recruited, and the frequency of peripheral blood activated and inhibitory NK and NKT cells in individual subjects was determined by flow cytometry. The frequency of spontaneous and inducible interferon gamma (IFN- γ) and CD107a+NK cells was further examined, and the potential association of the frequency of NK cells with clinical measures was analyzed. While there was no significant difference in the frequency of peripheral blood NK and NKT cells between patients and controls, the frequency of NKG2D+NK and NKT cells in patients was significantly higher than those in the controls ( P = 0.011). In contrast, the frequency of NKG2A+and KIR2DL3+inhibitory NK and NKT cells in patients was significantly lower than those in the controls ( P = 0.002, P < 0.0001, respectively). Furthermore, the frequencies of NKG2D+NK cells were correlated significantly with the values of body mass index in patients. Moreover, the frequencies of spontaneous and inducible CD107a+, but not IFN- γ-secreting, NK cells in patients were significantly higher than those in the controls ( P < 0.004, P < 0.0001). Our data indicated that a higher frequency of activated NK cells may participate in the obesity-related chronic inflammation involved in the pathogenesis of T2DM.
Evolution and Movement of Source Kitchens and Their Control of Oil and Gas in the Tarim Cratonic Basin, China
Authors: Pang Xiongqi , Yu Qiuhua , Guan Xiaoyan , Sumei Li , Fujie Jiang
Published: April 2012

The cratonic region of the Tarim Basin contains two main Lower Paleozoic source rocks–the Middle-Upper Ordovician and Lower-Middle Cambrian. However, few research focus on the relation between the evolution of hydrocarbon kitchens and its role in controlling oil and gas. Based on previous research results, this paper applies geochemical parameters of rock pyrolysis, hydrocarbon expulsion threshold theory and hydrocarbon-generated potential methods to identify the effectiveness of source rocks from the Lower Paleozoic while quantitatively calculating the hydrocarbon expulsion intensities and amounts for the two sets of source rocks. The above result is used to analysis the distribution of the effective hydrocarbon kitchen in each primary history stage and the controls on oil and gas. This study shows multiple phases of oil and gas generation and expulsion from the Cambrian-Ordovician source rocks with four oil-generating peaks with large-scale oil migration and accumulation. According to the changes in hydrocarbon expulsion intensity within different stages, we can elucidate the evolution of the source kitchens, because the hydrocarbon kitchens from the two sets of source rocks migrated in time and space, and there are multiple hydrocarbon expulsion centers. Based on the concept of the oil/gas threshold distribution model, the relation between the quantitative characterization of the hydrocarbon kitchen controlling function, and quantitative prediction of reservoir formation probability is studied, and the result shows that oil and gas reservoirs are located in more than 50% probability of controlling area. However, different periods and different layers of stacked hydrocarbon kitchen is complex and causing the main mixing of oil and gas. All these hydrocarbon expulsion centers had control over the distribution of oil and gas in the basin. From a macro and quantitative point of view, this discovery will provide certain guide for oil and gas exploration.
Using Carbon and Hydrogen Isotopes to Quantify Gas Maturity, Formation Temperature, and Formation Age — Specific Applications for Gas Fields from the Tarim Basin, China
Authors: Ni Yunyan , Liao Fengrong , Dai Jinxing , Zou Caineng , Zhu Guangyou , Zhang Bin , Liu Quanyou
Published: April 2012

The kinetic fractionation model for hydrogen isotope fractionation for methane, ethane and propane formation is tested in this study. The model agrees very well with the current existing model of carbon isotope fractionation for coal-derived gas from the Kuqa depression, Tarim basin, China. The strong correlation of carbon and hydrogen isotopes between theory and field data proves that it is unlikely that hydrogen isotopes will exchange with water under the gas formation condition. Using both gas carbon and hydrogen isotopes can further constrain our prediction of gas maturity, formation age and accumulation patterns for a natural gas system. Based on the carbon and hydrogen isotope fractionation model and field data, our results show the gas in the Kuqa depression was overmature in the central depression with Ro values up to 1.9–2.0% in the Kela 2 gas field and the gas maturity was much lower in the southern Front Uplift with Ro values ranging from 1.3% to 1.7%, which agree well with the distribution characteristics of the maturity of the local source rocks. However, the predicted gas maturity in the Front Uplift was relatively higher than that of the local source rocks, which probably indicates natural gases in the Front Uplift were migrated from the central depression. Our prediction demonstrates that natural gases in the Kuqa depression were formed during the last 3–5 million years and the gas formation temperature was 170–200°C, which is consistent with the burial history of the depression. According to our results, the potential accumulation pattern for the gas in the Kuqa depression is that gases were formed at depth and expelled from the Kuqa depression and migrated vertically along faults to some traps and formed giant gas fields, or migrated from north to south and accumulated in the Front Uplift or mixed with previous oil fields and formed condensate oil gas fields.
Impact of Late-Accumulated Mantle-Derived CO2 on Quality of Paleogene Clastic Reservoir at Actic Area, Qin Nan Sag
Authors: Zhou Xinhuai , Wang Qingbin , Li Jianping , Zang Chunyan , Guo Yonghua , Zhu Wensen
Published: April 2012

In this paper, the origin and accumulation time of CO2, and the transformation of clastic reservoir bed by CO2 in the A2 structure at the actic area of Qin Nan Sag were studied. The elevated δ13CCO2, R/Ra values and 40Ar/36Ar values showed that CO2 was mantle derived. CO2-bearing inclusions were associated with hydrocarbon inclusions, and CO2-bearing inclusions included hydrocarbon components, showing migration and filling of CO2 and hydrocarbon at the same stage. Basin modeling and homogenization temperature of inclusions indicated that the time of hydrocarbon and CO2 accumulation was mainly less than 3 Ma. CO2 late filling resulted in strong dissolution of feldspar and carbonate cement, with a high content of intragranular dissolution pores and a high proportion of intergranular primary pores, mostly from carbonate cement dissolution. Acidic environment inhibited illite growth, and dissolution of feldspar and acidic environment promoted formation of kaolinite. CO2 late filling brought out obvious thermal fluctuation, which was in favor of redistribution of dissolved matter, and top strong cementation was found at rock cores. Because of late accumulation of CO2, acidic environment of reservoir bed lasting for a long time, reservoir bed at a high temperature, undergrown dawsonite showed weak influence on reservoir bed quality. Dissolution of feldspar and carbonate cement, inhibition of illite growth, a high content of authigenic kaolinite, a low content of dawsonite, and redistribution of dissolved matter played a decisive role in improving reservoir quality, with rarely seen high permeability.
An Efficient Oxidation of Benzoins with the Jones Reagent Supported on Kieselguhr
Authors: Huang Li-Hong , Lou Ji-Dong , Ma Yi-Chun , Wang Qiang , Zhang Changhe
Published: April 2012

The heterogeneous room-temperature oxidation of benzoins with the Jones reagent supported on kieselguhr provides an efficient method for the preparation of the corresponding benzyls. The oxidations described in the present study were complete within 30 min with yields of between 82–93%.
Biosorption of Silver Ions by Paecilomyces Lilacinus Biomass: Equilibrium, Kinetics and Thermodynamics
Authors: Ou Hongxiang , Song Yujun , Huang Weihong , Pan Jianming , Xue Yonglai , Yi Chengwu , Yan Yongsheng
Published: April 2012

The freeze-dried biomass of Paecilomyces lilacinus was employed as a biosorbent for the removal of silver ions from aqueous solution. The effects of factors such as the solution pH, the initial Ag(I) ion concentration, contact time and temperature were examined. Maximum Ag(I) adsorption was obtained at pH 3.0. The pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetic models were fitted to the experimental data when it was found that such data were best fitted by the pseudo-second-order kinetic model. The equilibrium experimental data were well fitted by the Langmuir model (R2 > 0.995) and the maximum biosorption capacity at 298 K was 101.0 mmol/g. Thermodynamic parameters such as the Gibbs' free energy, ΔG0, the standard enthalpy, ΔH0, and the standard entropy, ΔS0, were evaluated. The results indicated that the biosorption of Ag(I) ions onto P. lilacinus biomass was spontaneous and endothermic in nature. The FT-IR analysis results indicated that amine, carboxylic and hydroxyl groups were involved in the biosorption process.
Sound Radiation from a Loudspeaker, from a Spherical Pole Cap, and from a Piston in an Infinite Baffle
Authors: Aarts Ronald M. , Janssen Augustus J.E.M.
Published: April 2012

Loudspeakers are often modelled as a rigid piston in an infinite baffle. As a model for real loudspeakers, this approach is limited in two ways. One issue is that a loudspeaker cone is not rigid, and a second issue is that a loudspeaker is mostly used in a cabinet. Both issues are addressed here by developing the velocity of the radiator in terms of orthogonal polynomials known from optical diffraction theory as Zernike circle polynomials. Using these polynomials we develop semi-analytic expressions for the sound pressure from the radiator in two different cases: as a flexible flat radiator mounted in an infinite baffle, and as the cap of a rigid sphere. In the latter case the comparison is done not only for the pressure but also for other quantities viz. the baffle-step response, sound power and directivity, and the acoustic centre of the radiator. These quantities are compared with those from a real loudspeaker. Finally, in the case of the baffled-piston radiation the spatial impulse response is presented.
Punching Shear Failure in Double-Layer Pultruded FRP Grid Reinforced Concrete Bridge Decks
Authors: Brunton Jeffrey J. , Bank Lawrence C. , Oliva Michael G.
Published: April 2012

The use of pultruded fiber reinforced polymer (FRP) grids is being investigated as tensile reinforcement in concrete bridge decks. Three full scale simply supported concrete slabs reinforced with double layer pultruded FRP girds representing long span bridge decks were tested. Punching shear was the critical failure mode. The punching shear capacity was compared to the University of Wisconsin punching shear equation, developed for the grid system on shorter spans by Jacobson (2004), and the punching shear capacity as given by ACI 440 (2006). The Jacobson equation conservatively predicted the capacity for slabs with edge restraint and accurately predicted the punching shear capacity for slabs without edge restraint. The ACI 440 (2006) punching shear equation underestimated the punching shear capacity of the slabs.
The FRP Reinforced Shear-Friction Mechanism
Authors: Lucas Wade , Oehlers Deric J. , Ali M.S. Mohamed , Griffith Michael C.
Published: April 2012

The ability of reinforced concrete to resist shear forces across possible sliding planes is a well established area of research and is also recognised as an important aspect of the ability of reinforced concrete members to both resist loads and deformation. This characteristic of reinforced concrete is often referred to as the shear-friction or aggregate interlock mechanism and much of the previous research in this area has dealt with ductile steel reinforcement, which is assumed to yield prior to the shear-friction capacity being attained. In this paper, it is shown that, as FRP is an elastic material, the shear friction behaviour of FRP reinforced concrete is different to that with ductile steel reinforcement. However, and perhaps surprisingly, the shear-friction capacity of FRP reinforced concrete can be just as ductile and strong as steel reinforced concrete.
Spatial Textile Reinforcement Structures for Ventilated and Sandwich Facade Elements
Authors: Hegger Josef , Kulas Christian , Horstmann Michael
Published: April 2012

Textile Reinforced Concrete (TRC) is a new composite material using mesh-like technical textiles to transfer tensile forces in a concrete member. The main advantage in using these reinforcements is the reduction of concrete covers to only few millimeters leading to slender and light-weight concrete applications like ventilated facade elements and sandwich panels with TRC facings. Based on three applications, which are realized in the last two years, it is revealed that there is a need not only for capable planar fabrics but also for spatial structures. Inherently stable reinforcement structures are achieved by impregnating the fabrics with a resin (e.g. epoxy resin) and curing the structures in the desired shape at temperatures up to 180°C. Moreover, the utilization of the cross-section of the rovings is homogenized and, thus, a tensile strength up to 1400 MPa is achieved for AR-glass fabrics.

The article deals with selected applications for facade structures made of TRC, material properties and demands on the textile reinforcement as well as production processes. Furthermore, test results regarding the load-bearing behavior of these selected applications are presented.
Evaporation of Nearly Monosized Droplets of Hexane, Heptane, Decane and Their Mixtures in Hot Air and an Air/Steam Mixture
Authors: Horender S. , Sommerfeld M.
Published: April 2012

This paper describes experiments on evaporating initially nearly monosized droplet chains with diameter 230 ± 15 μm under atmospheric conditions in a grid generated upward turbulent flow with initial liquid temperatures in the range 320 to 350 K and air temperatures in the range 365 to 455 K. The mean air velocity was 5 m/s and the initial droplet velocities were 17 m/s, resulting in a Reynolds number for the flow around the droplets of 100. The turbulent Stokes number was around 10. The liquids used were n-hexane, n-heptane, n-decane and mixtures thereof. A single chain and, for a reduced data set, a spray of 5 parallel chains, to study the influence of increased mass loading, have been investigated. Additionally, the influence of steam with mass fraction 15% on the evaporation rates has been investigated. The size of the droplets was measured by back light illumination and recording by a digital camera with macro optics. Digital image processing was applied to deduce the size of the droplets and their positions. Laser Doppler measurements delivered the droplet velocities. Besides the generation of a data set for validation of evaporation models the main findings were that turbulence of the surrounding air could increase evaporation for decane and that mixtures evaporated preferentially, indicating mixing inside the droplets being larger than pure diffusion limited. For heptane as evaporating liquid it was found that for elevated droplet loading at air temperature below the boiling point the evaporation rate decreased, while at higher temperatures the droplet loading hardly showed any influence on the evaporation rates. Adding steam led to increased evaporation rates for all liquids, most likely due to condensation on the droplets surfaces.
The Role of Homogeneous Chemistry during Ignition of Propane Combustion in Pt-Catalyzed Microburners
Authors: Regatte Venkat Reddy , Selle Gerhard , Kaisare Niket S.
Published: April 2012

The aim of this work is to numerically investigate the ignition behavior of homogeneous-heterogeneous (HH) combustion of propane in a Pt-catalyzed microburner to delineate the role of homogeneous chemistry during cold-start ignition. A two dimensional model with one-step homogeneous and catalytic mechanisms in a parallel-plate microburner is considered. The ignition characteristics (ignition temperature and ignition time) are explored for catalytic microreactor with and without homogeneous chemistry. We show that the catalytic reaction lights-off first, followed by the homogeneous reaction. Consequently, the homogeneous chemistry does not affect the ignition behavior of the catalytic microburner. The effect of inlet velocity, wall thermal conductivity and gap size on ignition characteristics is explored. The ignition characteristics are not affected by homogeneous chemistry even at larger gap sizes, despite the fact that the homogeneous contribution at steady state increases with increasing gap size of the microburner.
On the Prediction of Bubble Size Distribution and Void Fraction in Vertical Gas-Liquid Flows
Authors: Yeoh G. H. , Cheung Sherman C. P. , Tu J. Y.
Published: April 2012

Two-fluid modeling approach is considered as one of the most practical and accurate macroscopic formulation of handling bubbly flow systems. Nevertheless, in order to rigorously account for bubble-bubble interactions, the population balance equation (PBE) must be solved alongside with the continuity and momentum balance equations. Class method typified by the MUltiple SIze Group (MUSIG) model appears to be one of the most direct methods to solve the PBE using a finite series of discrete classes. In this paper, an alternative approach based on the direct quadrature method of moments (DQMOM) is investigated. In contrast to MUSIG model which requires a large number of classes to resolve the bubble distribution, the main advantage of DQMOM is that the number of moments to be solved is generally very small. Validation and assessment of the two population balance models are carried out against measurements of vertical bubbly flows for a range of flow conditions. Based on the present study, preliminary computed results have been found to compare very well against the experimental data as well as the numerical results predicted through the MUSIG model.
Study of Isothermal Vertical Bubbly Flow Using Direct Quadrature Method of Moments
Authors: Deju L. , Cheung S. C. P. , Yeoh G. H. , Tu J.
Published: April 2012

In the numerical study, investigation of bubbly flow requires deep understanding of complex hydrodynamics under various flow conditions. In order to simulate the bubble behaviour in conjunction with suitable bubble coalescence and bubble breakage kernels, direct quadrature method of moments (DQMOM) has been applied and validated instead. To examine the predictive results from DQMOM model, the validation has been carried out against experimental data of Lucas et al. (2005) and Prasser et al. (2007) measured in the Forschungszentrum Dresden-Rossendorf FZD facility. Numerical results showed good agreement against experimental data for the local and axial void fraction, bubble size distribution and interfacial area concentration profiles. Encouraging results demonstrates the prospect of the DQMOM two-fluid model against flow conditions with wider range of bubble sizes and rigorous bubble interactions. Moreover, moment sensitivity study also has been carried out to carefully assess the performance of the model. In order to perform the moment sensitivity test three different moment criteria has chosen – as 4 moments, 6 moments and 8 moments. Close agreement between the predictions and measurement was found and it appeared that increasing the number of moments does not have much significance to improve the conformity with experimental data. Nonetheless, increasing the number of moments merely contribute to perform the calculation expensive in terms of computational resource and time. Based on the present study, this preliminary assessment has definitely served to demonstrate and exploit DQMOM model's capabilities to handle wider range of bubble sizes as well as moment resolution required to achieve moment independent solution.
Numerical Simulations of Liquid-Gas-Solid Three-Phase Flows in Microgravity
Authors: Zhang Xinyu , Ahmadi Goodarz
Published: April 2012

Three-phase liquid-gas-solid flows under microgravity condition are studied. An Eulerian-Lagrangian computational model was developed and used in the simulations. In this approach, the liquid flow was modeled by a volume-averaged system of governing equations, whereas motions of particles and bubbles were evaluated using the Lagrangian trajectory analysis procedure. It was assumed that the bubbles remained spherical, and their shape variations were neglected. The bubble-liquid, particle-liquid and bubbl-particle two-way interactions were accounted for in the analysis. The discrete phase equations used included drag, lift, buoyancy, and virtual mass forces. Particle-particle interactions and bubble-bubble interactions were accounted for by the hard sphere model. Bubble coalescence was also included in the model. The transient flow characteristics of the three-phase flow were studied; and the effects of gravity, inlet bubble size and g-jitter acceleration on variation of flow characteristics were discussed. The low gravity simulations showed that most bubbles are aggregated in the inlet region. Also, under microgravity condition, bubble transient time is much longer than that in normal gravity. As a result, the Sauter mean bubble diameter, which is proportional to the transient time of the bubble, becomes rather large, reaching to more than 9 mm. The bubble plume in microgravity exhibits a plug type flow behavior. After the bubble plume reaches the free surface, particle volume fraction increases along the height of the column. The particles are mainly located outside the bubble plume, with very few particles being retained in the plume. In contrast to the normal gravity condition, the three phases in the column are poorly mixed under microgravity conditions. The velocities of the three phases were also found to be of the same order. Bubble size significantly affects the characteristics of the three-phase flows under microgravity conditions. For the same inlet bubble number density, the flow with larger bubbles evolves faster. The simulation results showed that the effect of g-jitter acceleration on the gas-liquid-particle three phase flows is small.
Simulation of Blood Flow and Nanoparticle Transport in a Stenosed Carotid Bifurcation and Pseudo-Arteriole
Authors: Doig Graham , Yeoh Guan H. , Timchenko Victoria , Rosengarten Gary , Barber Tracie J. , Cheung Sherman C.P.
Published: April 2012

Numerical simulation of flow through a realistic bifurcated carotid artery geometry with a stenosis has been conducted for comparison to experimental measurements. The behaviour of simplified therapeutic nanoparticles in relatively low concentration was observed using a discrete particle approach. The role of size (diameters from 500 nm to 50 nm) in determining particle residence time and the potential for both desirable and undesirable wall interactions was investigated. It was found that mean particle residence time reduced with decreasing particle diameter, and the percentage of particles experiencing one or more wall interactions increased simultaneously. Further simulations were conducted on a scaled-down version of the geometry which approximated the size and flow conditions of an arteriole with capillary branches, and in this instance the mean residence time increased with decreasing particle diameter, owing largely to the greater influence of Brownian motion. 33% of all 50 nm particles were involved in wall interactions, indicating that smaller particles would have a greater ability to target, for instance, cancerous tumours in such regions.
Exploring purine N7 interactions via atomic mutagenesis: The group I ribozyme as a case study
Authors: Forconi Marcello , Benz-Moy Tara , Gleitsman Kristin Rule , Ruben Eliza , Metz Clyde , Herschlag Daniel
Published: April 2012

Atomic mutagenesis has emerged as a powerful tool to unravel specific interactions in complex RNA molecules. An early extensive study of analogs of the exogenous guanosine nucleophile in group I intron self-splicing by Bass and Cech demonstrated structure–function relationships analogous to those seen for protein ligands and provided strong evidence for a well-formed substrate binding site made of RNA. Subsequent functional and structural studies have confirmed these interacting sites and extended our understanding of them, with one notable exception. Whereas 7-methyl guanosine did not affect reactivity in the original study, a subsequent study revealed a deleterious effect of the seemingly more conservative 7-deaza substitution. Here we investigate this paradox, studying these and other analogs with the more thoroughly characterized ribozyme derived from the Tetrahymena group I intron. We found that the 7-deaza substitution lowers binding by ∼20-fold, relative to the cognate exogenous guanosine nucleophile, whereas binding and reaction with 7-methyl and 8-aza-7-deaza substitutions have no effect. These and additional results suggest that there is no functionally important contact between the N7 atom of the exogenous guanosine and the ribozyme. Rather, they are consistent with indirect effects introduced by the N7 substitution on stacking interactions and/or solvation that are important for binding. The set of analogs used herein should be valuable in deciphering nucleic acid interactions and how they change through reaction cycles for other RNAs and RNA/protein complexes.
Identification of eRF1 residues that play critical and complementary roles in stop codon recognition
Authors: Conard Sara E. , Buckley Jessica , Dang Mai , Bedwell Gregory J. , Carter Richard L. , Khass Mohamed , Bedwell David M.
Published: April 2012

The initiation and elongation stages of translation are directed by codon–anticodon interactions. In contrast, a release factor protein mediates stop codon recognition prior to polypeptide chain release. Previous studies have identified specific regions of eukaryotic release factor one (eRF1) that are important for decoding each stop codon. The cavity model for eukaryotic stop codon recognition suggests that three binding pockets/cavities located on the surface of eRF1's domain one are key elements in stop codon recognition. Thus, the model predicts that amino acid changes in or near these cavities should influence termination in a stop codon-dependent manner. Previous studies have suggested that the TASNIKS and YCF motifs within eRF1 domain one play important roles in stop codon recognition. These motifs are highly conserved in standard code organisms that use UAA, UAG, and UGA as stop codons, but are more divergent in variant code organisms that have reassigned a subset of stop codons to sense codons. In the current study, we separately introduced TASNIKS and YCF motifs from six variant code organisms into eRF1 of Saccharomyces cerevisiae to determine their effect on stop codon recognition in vivo. We also examined the consequences of additional changes at residues located between the TASNIKS and YCF motifs. Overall, our results indicate that changes near cavities two and three frequently mediated significant effects on stop codon selectivity. In particular, changes in the YCF motif, rather than the TASNIKS motif, correlated most consistently with variant code stop codon selectivity.
Basis for ligand discrimination between ON and OFF state riboswitch conformations: The case of the SAM-I riboswitch
Authors: Boyapati Vamsi Krishna , Huang Wei , Spedale Jessica , Aboul-ela Fareed
Published: April 2012

Riboswitches are RNA elements that bind to effector ligands and control gene expression. Most consist of two domains. S-Adenosyl Methionine (SAM) binds the aptamer domain of the SAM-I riboswitch and induces conformational changes in the expression domain to form an intrinsic terminator (transcription OFF state). Without SAM the riboswitch forms the transcription ON state, allowing read-through transcription. The mechanistic link between the SAM/aptamer recognition event and subsequent secondary structure rearrangement by the riboswitch is unclear. We probed for those structural features of the Bacillus subtilis yitJ SAM-I riboswitch responsible for discrimination between the ON and OFF states by SAM. We designed SAM-I riboswitch RNA segments forming “hybrid” structures of the ON and OFF states. The choice of segment constrains the formation of a partial P1 helix, characteristic of the OFF state, together with a partial antiterminator (AT) helix, characteristic of the ON state. For most choices of P1 vs. AT helix lengths, SAM binds with micromolar affinity according to equilibrium dialysis. Mutational analysis and in-line probing confirm that the mode of SAM binding by hybrid structures is similar to that of the aptamer. Altogether, binding measurements and in-line probing are consistent with the hypothesis that when SAM is present, stacking interactions with the AT helix stabilize a partially formed P1 helix in the hybrids. Molecular modeling indicates that continuous stacking between the P1 and the AT helices is plausible with SAM bound. Our findings raise the possibility that conformational intermediates may play a role in ligand-induced aptamer folding.
Heterometallic cubane-type clusters containing group 13 and 16 elements
Authors: Geetharani K. , Bose Shubhankar Kumar , Ghosh Sundargopal
Published: May 2012

Heterometallic cubane-type clusters were synthesized from the reaction of group 6 and 8 metallaboranes using transition-metal carbonyl compounds. Structural and spectroscopic study revealed the existence of novel “capped-cubane” geometry. In addition, the crystal structure of these clusters distinctly confirms the presence of boride unit as one of the vertices. These clusters possess 60 cluster valence electrons (cve) and six metal–metal bonds. A plausible pathway for the formation of ruthenium-capped cubane has been described.
Progress toward red and near-infrared (NIR) emitting saccharide sensors
Authors: Sibrian-Vazquez Martha , Escobedo Jorge O. , Lowry Mark , Strongin Robert M.
Published: May 2012

Red-shifted and near-infrared (NIR)-active rhodamine analogs and their boronic acid derivatives were synthesized and studied. These latter compounds function as fluorogenic NIR active substrates for sugar sensing. The effects of benzannulation and boronic acid functionalization on fluorophore optical and sensing properties are described.
Annual fasting plasma glucose variation increases risk of cancer incidence and mortality in patients with type 2 diabetes: the Taichung Diabetes Study
Authors: Lin Cheng-Chieh , Li Chia-Ing , Liu Chiu-Shong , Lin Wen-Yuan , Chen Ching-Chu , Yang Sing-Yu , Lee Cheng-Chun , Li Tsai-Chung
Published: April 2012

The study aims to examine whether the annual variations in fasting plasma glucose (FPG) measurements, represented by the coefficient of variation (CV), predict cancer incidence and mortality in the subsequent years independent of traditional risk factors of type 2 diabetic patients. A computerized database of patients with type 2 diabetes of 30 years old and older (n=4805) enrolled in the Diabetes Care Management Program of a medical center before 2006 was analyzed using a time-dependent Cox's proportional hazards regression model. The mortality rates for the first, second, and third tertiles of the first annual FPG-CV were 8.64, 12.71, and 30.82 per 1000 person-years respectively. After adjusting for mean FPG, HbA1c, and other risk factors, the annual FPG-CV was independently associated with cancer incidence, cancer mortality, and cancer incidence or mortality, and the corresponding hazard ratios for the third vs first tertile of the annual FPG-CV were 3.03 (1.98, 4.65), 5.04 (2.32, 10.94), and 2.86 (1.91, 4.29) respectively. The annual variation in FPG was a strong predictor of cancer incidence and mortality in type 2 diabetic patients; therefore, glucose variation may be important in the clinical practice of care management and cancer prevention.
Catalysis leads to posttranslational inactivation of the type 1 deiodinase and alters its conformation
Authors: Zhu Bo , Shrivastava Ashutosh , Luongo Cristina , Chen Ting , Harney John W , Marsili Alessandro , Tran Thuy-Van , Bhadouria Anulika , Mopala Radhika , Steen Amanda I , Larsen P Reed , Zavacki Ann Marie
Published: April 2012

Previously, it was shown that the type 1 deiodinase (D1) is subject to substrate-dependent inactivation that is blocked by pretreatment with the inhibitor of D1 catalysis, propylthiouracil (PTU). Using HepG2 cells with endogenous D1 activity, we found that while considerable D1-mediated catalysis of reverse tri-iodothyronine (rT3) is observed in intact cells, there was a significant loss of D1 activity in sonicates assayed from the same cells in parallel. This rT3-mediated loss of D1 activity occurs despite no change in D1 mRNA levels and is blocked by PTU treatment, suggesting a requirement for catalysis. Endogenous D1 activity in sonicates was inactivated in a dose-dependent manner in HepG2 cells, with a ∼50% decrease after 10 nM rT3 treatment. Inactivation of D1 was rapid, occurring after only half an hour of rT3 treatment. D1 expressed in HEK293 cells was inactivated by rT3 in a similar manner. 75Se labeling of the D1 selenoprotein indicated that after 4 h rT3-mediated inactivation of D1 occurs without a corresponding decrease in D1 protein levels, though rT3 treatment causes a loss of D1 protein after 8–24 h. Bioluminescence resonance energy transfer studies indicate that rT3 exposure increases energy transfer between the D1 homodimer subunits, and this was lost when the active site of D1 was mutated to alanine, suggesting that a post-catalytic structural change in the D1 homodimer could cause enzyme inactivation. Thus, both D1 and type 2 deiodinase are subject to catalysis-induced loss of activity although their inactivation occurs via very different mechanisms.
Surgery for Type B Dissection Using a Short-Stented Elephant Trunk Procedure
Authors: Tian LiangXin , Qi RuiDong , Chang Qian , Yu CunTao , Zhu JunMing , Liu YongMin , Zheng Jun , Sun LiZhong
Published: April 2012

Background: Stent grafting is a very important treatment for type B dissection. Some patients are unsuitable for endograft repair because of inadequate proximal and/or distal fixation zones. We reviewed our experience of proximal descending thoracic replacement combined with short-stented elephant trunk implantation for type B dissection for patients without adequate fixation zones for endografts.

Methods: Twenty-one patients with type B dissection (10 acute, 11 chronic) underwent this procedure between August 2003 and December 2007. After replacement of the proximal descending thoracic aorta, a short-stented elephant trunk was implanted into the residual descending thoracic aorta. The residual false lumen was evaluated post-operatively using computed tomography (CT) scans.

Results: There were no in-hospital deaths. One death was observed during a mean follow-up of 69 � 15 months. One patient with preoperative shock suffered paraparesis but recovered postoperatively. One patient had paraplegia and was lost to follow-up. Cerebral hemorrhage was observed in 1 patient, but he recovered. Thrombus obliteration of the false lumen around the stented elephant trunk was observed in 19 patients (95%) and at the diaphragmatic level in 17 patients (85%) during follow-up.

Conclusion: Replacement of the proximal descending thoracic aorta combined with short-stented elephant trunk implantation was a suitable alternative for type B dissection for patients without adequate fixation zones for endografts (particularly for young subjects). This procedure allowed enlargement of the true lumen, re-establishment of the true lumen, induction of thrombosis of the false lumen, and shrinkage of the aorta. Injury to the spinal cord, however, was an intractable problem.
Surgical Strategy in Patients with Atrial Septal Defect and Severe Pulmonary Hypertension
Authors: Cho Yang Hyun , Jun Tae-Gook , Yang Ji-Hyuk , Park Pyo Won , Huh June , Kang I-Seok , Lee Heung Jae
Published: April 2012

The aim of the study was to review our experience with atrial septal defect (ASD) closure with a fenestrated patch in patients with severe pulmonary hypertension. Between July 2004 and February 2009, 16 patients with isolated ASD underwent closure with a fenestrated patch. All patients had a secundum type ASD and severe pulmonary hypertension. Patients ranged in age from 6 to 57 years (mean � SD, 34.9 � 13.5 years). The follow-up period was 9 to 59 months (mean, 34.5 � 13.1 months). The ranges of preoperative systolic and pulmonary arterial pressures were 63 to 119 mm Hg (mean, 83.8 � 13.9 mm Hg) and 37 to 77 mm Hg (mean, 51.1 � 10.1 mm Hg). The ranges of preoperative values for the ratio of the pulmonary flow to the systemic flow and for pulmonary arterial resistance were 1.1 to 2.7 (mean, 1.95 � 0.5) and 3.9 to 16.7 Wood units (mean, 9.8 � 2.9 Wood units), respectively. There was no early or late mortality. Tricuspid annuloplasty was performed in 14 patients (87.5%). The peak tricuspid regurgitation gradient and the ratio of the systolic pulmonary artery pressure to the systemic arterial pressure were decreased in all patients. The New York Heart Association class and the grade of tricuspid regurgitation were improved in 13 patients (81.2%) and 15 patients (93.7%), respectively. ASD closure in patients with severe pulmonary hypertension can be performed safely if we create fenestration. Tricuspid annuloplasty and a Cox maze procedure may improve the clinical result. Close observation and follow-up will be needed to validate the long-term benefits.
Nitroglycerin and Sodium Nitroprusside: Potential Contributors to Postoperative Bleeding?
Authors: Clark Donald , Tesseneer Stephanie , Tribble Curtis G.
Published: April 2012

Postoperative bleeding is common in patients undergoing cardiac surgery with cardiopulmonary bypass. Most cases of severe postoperative bleeding not due to incomplete surgical hemostasis are related to acquired transient platelet dysfunction mediated by platelet activation during contact with the synthetic surfaces of the cardiopulmonary bypass equipment. Antihypertensive agents nitroglycerin and sodium nitroprusside have been shown to have platelet inhibitory properties, yet the clinical consequence in terms of postoperative bleeding has been little studied. Knowing that cardiopulmonary bypass causes platelet dysfunction, it is prudent for physicians to be aware of the additional platelet inhibition caused by these commonly used antihypertensive agents.
Quality of Life after Children Undergo a Radical Arterial Switch Operation at an Older Age
Authors: Huang Jing-bin , Cao Yong-tao , Liang Jian , Lv Xiao-dong
Published: April 2012

Objective: The goal of the study was to evaluate the quality of life of children after the older corrective arterial switch operation (ASO) by means of the Pediatric Quality of Life Inventory (PedsQL), version 4.0.

Methods: The records of 86 patients who had complete transposition of the great arteries plus a nonrestrictive ventricular septal defect, or a Taussig-Bing anomaly, and severe pulmonary arterial hypertension, and who underwent a corrective ASO at an older age (>6 months) between May 2000 and October 2008 were reviewed retrospectively. Eighty survivors were followed up, and the health-related quality of life of the survivors was evaluated with the PedsQL, version 4.0.

Results: There were 6 hospital deaths. The mean (SD) follow-up interval was 3.5 � 2.3 years, and the mean age at last visit was 7.0 � 1.2 years. Two late deaths occurred, and 8 patients were lost to follow-up. Patients who underwent a corrective ASO at an older age showed acceptable scores for all scales, and they were all comparable with those of a healthy population.

Conclusions: Our data suggest that the quality of life of children who undergo a corrective ASO at an older age (>6 months) is acceptable, compared with that of healthy children in China.
The Use of Posterior Pericardiotomy Technique to Prevent Postoperative Pericardial Effusion in Cardiac Surgery
Authors: Cakalagaoglu Canturk , Koksal Cengiz , Baysal Ayse , Alici Gokhan , Ozkan Birol , Boyacioglu Kamil , Tasar Mehmet , Atasoy Emine Banu , Erdem Hasan , Esen Ali Metin , Alp Mete
Published: April 2012

Aim: The goal was to determine the effectiveness of the posterior pericardiotomy technique in preventing the development of early and late pericardial effusions (PEs) and to determine the role of anxiety level for the detection of late pericardial tamponade (PT).

Materials and Methods: We divided 100 patients randomly into 2 groups, the posterior pericardiotomy group (n = 50) and the control group (n = 50). All patients undergoing coronary artery bypass grafting surgery (CABG), valvular heart surgery, or combined valvular and CABG surgeries were included. The posterior pericardiotomy technique was performed in the first group of 50 patients. Evaluations completed preoperatively, postoperatively on day 1, before discharge, and on postoperative days 5 and 30 included electrocardiographic study, chest radiography, echocardiographic study, and evaluation of the patient's anxiety level. Postoperative causes of morbidity and durations of intensive care unit and hospital stays were recorded.

Results: The 2 groups were not significantly different with respect to demographic and operative data (P > .05). Echocardiography evaluations revealed no significant differences between the groups preoperatively; however, before discharge the control group had a significantly higher number of patients with moderate, large, and very large PEs compared with the pericardiotomy group (P < .01). There were 6 cases of late PT in the control group, whereas there were none in the pericardiotomy group (P < .05). Before discharge and on postoperative day 15, the patients in the pericardiotomy group showed significant improvement in anxiety levels (P = .03 and .004, respectively). No differences in postoperative complications were observed between the 2 groups.

Conclusion: Pericardiotomy is a simple, safe, and effective method for reducing the incidence of PE and late PT after cardiac surgery. It also has the potential to provide a better quality of life.