bluuebunny/crossref_metadata_2025 huggingface dataset:
Acetyl‐11‐keto‐β‐boswellic acid suppresses invasion of pancreatic cancer cells through the downregulation of CXCR4 chemokine receptor expression
Authors: Park Byoungduck , Sung Bokyung , Yadav Vivek R. , Cho Sung‐Gook , Liu Mingyao , Aggarwal Bharat B.
Published: February 2011

Ninety percent of cancer‐mediated deaths are due to metastasis of the tumor; however, the mechanisms controlling metastasis remain poorly understood. Thus, no therapy targeting this process has yet been approved. Chemokines and their receptors are mediators of chronic inflammation and have been linked to the metastasis of numerous cancers. More recently, the Cysteine X Cysteine (CXC) chemokine receptor 4 (CXCR4) has emerged as a key mediator of tumor metastasis; therefore, identification of inhibitors of this receptor has the potential to abrogate metastasis. In this report, we demonstrate that acetyl‐11‐keto‐β‐boswellic acid (AKBA), a component of the therapeutic plant Boswellia serrata, can downregulate CXCR4 expression in pancreatic cancer cells. The reduction in CXCR4 induced by this terpenoid was found to be cell‐type specific, as its expression was also abrogated in leukemia, myeloma and breast cancer cell lines. Neither proteasome inhibitors nor lysosomal stabilization could prevent the AKBA‐induced reduction in CXCR4 expression. This downregulation occurred at the transcriptional level. Suppression of CXCR4 by AKBA was accompanied by the inhibition of pancreatic cancer cell invasion, which is induced by CXCL12, the ligand for CXCR4. In addition, abrogation of the expression of chemokine receptor by AKBA was found in human pancreatic tissues from orthotopic animal model. AKBA also abolished breast tumor cell invasion, and this effect correlated with the disappearance of both the CXCR4 messenger RNA and CXCR4 protein. Overall, our results show that AKBA is a novel inhibitor of CXCR4 expression and, thus, has the potential to suppress the invasion and metastasis of cancer cells.
Expression of aldehyde dehydrogenase and CD133 defines ovarian cancer stem cells
Authors: Kryczek Ilona , Liu Suling , Roh Michael , Vatan Linhua , Szeliga Wojciech , Wei Shuang , Banerjee Mousumi , Mao Yujun , Kotarski Jan , Wicha Max S. , Liu Rebecca , Zou Weiping
Published: February 2011

Identification of cancer stem cells is crucial for advancing cancer biology and therapy. Several markers including CD24, CD44, CD117, CD133, the G subfamily of ATP‐binding cassette transporters (ABCG), epithelial specific antigen (ESA) and aldehyde dehydrogenase (ALDH) are used to identify and investigate human epithelial cancer stem cells in the literature. We have now systemically analyzed and compared the expression of these markers in fresh ovarian epithelial carcinomas. Although the expression levels of these markers were unexpectedly variable and partially overlapping in fresh ovarian cancer cells from different donors, we reliably detected important levels of CD133 and ALDH in the majority of fresh ovarian cancer. Furthermore, most of these stem cell markers including CD133 and ALDH were gradually lost following in vitro passage of primary tumor cells. However, the expression of ALDH and CD133, but not CD24, CD44 and CD117, could be partially rescued by the in vitro serum‐free and sphere cultures and by the in vivo passage in the immune‐deficient xenografts. ALDH+ and CD133+ cells formed three‐dimensional spheres more efficiently than their negative counterparts. These sphere‐forming cells expressed high levels of stem cell core gene transcripts and could be expanded and form additional spheres in long‐term culture. ALDH+, CD133+ and ALDH+CD133+ cells from fresh tumors developed larger tumors more rapidly than their negative counterparts. This property was preserved in the xenografted tumors. Altogether, the data suggest that ALDH+ and CD133+ cells are enriched with ovarian cancer‐initiating (stem) cells and that ALDH and CD133 may be widely used as reliable markers to investigate ovarian cancer stem cell biology.
Cyclooxygenase‐2 inhibition causes antiangiogenic effects on tumor endothelial and vascular progenitor cells
Authors: Muraki Chikara , Ohga Noritaka , Hida Yasuhiro , Nishihara Hiroshi , Kato Yasutaka , Tsuchiya Kunihiko , Matsuda Kohei , Totsuka Yasunori , Shindoh Masanobu , Hida Kyoko
Published: February 2011

Tumor angiogenesis is necessary for solid tumor progression and metastasis. Cyclooxygenase (COX)‐2 is known to play an important role in cancer growth and invasion, and it activates the signaling pathways controlling cell proliferation, migration, apoptosis, and angiogenesis. COX‐2 is reported to be expressed in many cancer cells. Several studies have reported successful treatment of cancer cells with COX‐2 inhibitors (COX‐2is). However, the effect of COX‐2 inhibition on the tumor endothelium remains to be elucidated. Our study shows that COX‐2 is expressed in the vasculature of surgically resected human tumors. To investigate the effects of COX‐2 inhibition on the tumor endothelium in vitro, we isolated tumor endothelial cells (TECs) from human melanoma and oral carcinoma xenografts in mice, in which we confirmed that tumor growth was suppressed by inhibiting angiogenesis with the COX‐2is NS398. COX‐2 mRNA was upregulated in TECs compared to normal endothelial cells (NECs). Cell migration and proliferation were suppressed by NS398 in TECs but not in NECs. The effects of NS398 in vivo were consistent with the in vitro results. The number of CD133+/vascular endothelial growth factor receptor‐2+ cells in circulation was significantly suppressed by COX‐2 inhibition. In addition, the number of progenitor marker‐positive cells decreased in the tumor blood vessels after COX‐2i treatment, which suggests that the homing of progenitor cells into the tumor was also blocked. We conclude that NS398 specifically targets both TECs and vascular progenitor cells without affecting NECs.
Phospho-Smad1 modulation by nedd4 e3 ligase in BMP/TGF-β signaling
Authors: Kim Byung-Gyu , Lee Ji-Hyun , Yasuda Jiro , Ryoo Hyun-Mo , Cho Je-Yoel
Published: February 2011

A considerable number of studies have focused on the regulation of mothers against decapentaplegic homologue (Smad)–dependent or –independent pathways in the signaling by each transforming growth factor β (TGF-β) superfamily member in diverse biologic contexts. The sophisticated regulation of the actions of these molecules and the underlying molecular mechanisms still remain elusive. Here we show new mechanisms of ambilateral R (receptor-regulated)–Smad regulation of bone morphogenetic protein 2 (BMP-2)/TGF-β1 signals. In a specific context, both signals regulate the nonclassic Smads pathway reciprocally, BMP-2 to Smad2/3 and TGF-β1 to Smad1/5/8, as well as their own classic linear Smad pathway. Interestingly, in this study, we found that C-terminal phosphorylated forms of each pathway Smad degraded rapidly 3 hours after stimulation of nonclassic signals but are dramatically restored by treatment with via proteasomal inhibition. Furthermore, an E3 ligase, neural precursor cell expressed, developmentally down-regulated 4 (Nedd4), also was found as one of the important modulators of the p-Smad1 in both BMP-2 and TGF-β1 action. Overexpressed Nedd4 suppressed the BMP-induced osteoblast transdifferentiation process of premyoblast C2C12 cells or alkaline phosphatase (ALP) level of human osteosarcoma cells and promoted TGF-β1-induced degradation of p-Smad1 via physical interaction and polyubiquitination. Conversely, siNedd4 potentiated BMP signals through upregulation of p-Smad1 and ALP activity, the effect of which led to an increased the rate of Pi-induced calcification of human vascular smooth muscle cells. These new insights about proteasomal degradation–mediated phosphorylated nonclassic Smad regulation of BMP-2/TGF-β1 could, in part, help to unravel the complex mechanisms of abnormal nonosseous calcification by the aberrant activity of BMP/TGF-β/Smads. © 2011 American Society for Bone and Mineral Research.
Predictors of doctoral student success in professional psychology: characteristics of students, programs, and universities
Authors: Graham James M. , Kim Yang‐Hyang
Published: February 2011

In the face of the rising number of doctoral recipients in professional psychology, many have voiced concerns about the quality of nontraditional training programs. Past research suggests that, on a variety of outcomes, graduates from clinical PhD programs outperform graduates from clinical PsyD and, to a lesser extent, counseling PhD programs. We examine an aggregate archival dataset to determine whether student or university characteristics account for the differences in outcomes among programs. The data show meaningful differences in the outcomes of clinical PhD, PsyD, and counseling PhD programs. Furthermore, graduates from research‐intensive universities perform better on the psychology licensure exam and are more likely to become American Board of Professional Psychology diplomates. The available data support the notion that the ability to conduct research is an essential component of graduate education. In this light, PsyD programs represent a unique opportunity to train students in the types of evaluation and outcomes assessments used by practicing psychologists. We discuss implications for graduate‐level training in professional psychology. © 2011 Wiley Periodicals, Inc. J Clin Psychol 67:1‐15, 2011.
Effectiveness of virtual reality exposure therapy for active duty soldiers in a military mental health clinic
Authors: Reger Greg M. , Holloway Kevin M. , Candy Colette , Rothbaum Barbara O. , Difede JoAnn , Rizzo Albert A. , Gahm Gregory A.
Published: February 2011

Exposure therapy is an evidence‐based treatment for posttraumatic stress disorder (PTSD), but research evaluating its effectiveness with active duty service members is limited. This report examines the effectiveness of virtual reality exposure therapy (VRE) for active duty soldiers (N = 24) seeking treatment following a deployment to Iraq or Afghanistan. Relative to their pretreatment self‐reported symptoms on the PTSD Checklist, Military Version (M = 60.92; SD = 11.03), patients reported a significant reduction at posttreatment (M = 47.08; SD = 12.70; p < .001). Sixty‐two percent of patients (n = 15) reported a reliable change of 11 points or more. This study supports the effectiveness of exposure therapy for active duty soldiers and extends previous research on VRE to this population.
Solvent polarity and hydrogen bond effects on nucleophilic substitution reaction of 2‐bromo‐5‐nitrothiophene with piperidine
Authors: Harifi‐Mood Ali Reza , Rahmati Masoud , Gholami Mohammad Reza
Published: February 2011

The reaction kinetics of 2‐bromo‐5‐nitro thiophene with piperidine was studied in a solvent with a mixture of propan‐2‐ol with methanol and n‐hexane at 25°C. The measured rate coefficients of the reaction demonstrated dramatic variations in propan‐2‐ol–n‐hexane mixtures and mild variations in propan‐2‐ol–methanol system. The second‐order rate coefficients of the reaction, kA, decreased sharply with n‐hexane content. The multiparameter correlation of log kA versus molecular‐microscopic solvent parameters shows interesting results in these solutions. Linear free energy relationship investigations confirm that polarity has a major effect on the reaction rate and hydrogen bond ability of the media has a slight effect on the reaction rate. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 185–190, 2011
MAPPING LINEAR EROSION FEATURES USING HIGH AND VERY HIGH RESOLUTION SATELLITE IMAGERY
Authors: Desprats J.F. , Raclot D. , Rousseau M. , Cerdan O. , Garcin M. , Le Bissonnais Y. , Ben Slimane A. , Fouche J. , Monfort‐Climent D.
Published: February 2011

Mapping and monitoring linear erosion features (LEFs) over large areas is fundamental for a better understanding of the main erosion processes and for planning suitable protection measures. The advent of very high‐resolution satellite imagery has expanded the range of satellite LEF identification to moderate‐size elements. After determining the relationship between satellite imagery resolution and the ability to detect LEFs, we discuss a highly automated method for extracting such LEFs from a very high spatial resolution image (0.61 m resolution). The method is based on a two‐stage strategy: (1) extraction of all linear features visible on the satellite image using filters and photo‐interpretation; (2) filtering these linear features according to geometric criteria (e.g. orientation relative to slope, sinuosity, position in landscape, etc.) so as to retain only those relative to linear erosion. A series of three images with increasing spatial resolution (10.5 and 0.61 m) was prepared for an area on the Cap Bon peninsula (Tunisia). This predominantly agricultural area has a high density of LEFs with very varied geometric characteristics. The area's problems are both onsite for the agriculture itself, and offsite with the silting up of hillside reservoirs. Respectively 22 per cent, 37 per cent and 73 per cent of the site's LEFs, with respective average widths of 2.8, 3.0 and 2.2 m, are visible on the 10, 5 and 0.61 m resolution images. Gully identification should help to identify the most threatened areas to help land use planning and management or to validate erosion models whether at regional or local (drainage basin) scale. Copyright © 2011 John Wiley & Sons, Ltd.
Splenic artery embolization for the treatment of refractory ascites after liver transplantation
Authors: Quintini Cristiano , D'Amico Giuseppe , Brown Chase , Aucejo Federico , Hashimoto Koji , Kelly Dympna M. , Eghtesad Bijan , Sands Mark , Fung John J. , Miller Charles M.
Published: February 2011

Refractory ascites (RA) is a challenging complication after orthotopic liver transplantation. Its treatment consists of the removal of the precipitating factors. When the etiology is unknown, supportive treatment can be attempted. In severe cases, transjugular intrahepatic portosystemic shunts, portocaval shunts, and liver retransplantation have been used with marginal results. Recently, splenic artery embolization (SAE) has been described as an effective procedure for reducing portal hyperperfusion in patients undergoing partial or whole liver transplantation. Here we describe our experience with SAE for the treatment of RA. Between June 2004 and June 2010, 6 patients underwent proximal SAE for RA. Intraoperative flow measurements, graft characteristics, embolization portal vein (PV) velocities before and after SAE, and spleen/liver volume ratios were collected and analyzed. The response to treatment was assessed with imaging (ultrasound/computed tomography) and on the basis of clinical outcomes (weight changes, diuretic requirements, and the time to ascites resolution). The PV velocity decreased significantly for each patient after the embolization (median = 66.5 cm/second before SAE and median = 27.5 cm/second after SAE, P < 0.01). All patients experienced a significant postprocedural weight loss (mean = 88.1 ± 28.4 kg before SAE and mean = 75.8 ± 28.4 kg after SAE, P < 0.01) and a dramatic decrease in their diuretic requirements. All but 1 of the patients experienced a complete resolution of ascites after a median time of 49.5 days (range = 12-295 days). No patient presented with postembolization complications. In conclusion, SAE was effective in reducing the PV velocity immediately after the procedure. Clinically, this translated into a dramatic weight loss, a reduction of diuretic use, and a resolution of ascites. SAE appears to be a safe and effective treatment for RA. Liver Transpl 17:668–673, 2011. © 2011 AASLD.
A Case-Controlled Study of the Safety and Efficacy of Transjugular Intrahepatic Portosystemic Shunts After Liver Transplantation
Authors: King Andrew , Masterton Gail , Gunson Bridget , Olliff Simon , Redhead Doris , Mangat Kamarjit , Oniscu Gabriel , Hayes Peter , Tripathi Dhiraj
Published: February 2011

The role of transjugular intrahepatic portosystemic shunt (TIPS) insertion in managing the complications of portal hypertension is well established, but its utility in patients who have previously undergone liver transplantation is not well documented. Twenty-two orthotopic liver transplantation (OLT) patients and 44 nontransplant patients (matched controls) who underwent TIPS were analyzed. In the OLT patients, the TIPS procedure was performed at a median of 44.8 months (range = 0.3-143 months) after transplantation. Eight (36.4%) had variceal bleeding, and 14 (63.6%) had refractory ascites. The underlying liver disease was cholestatic in 10 (45.4%) and viral in 4 (18.2%). The mean pre-TIPS Model for End-Stage Liver Disease (MELD) score was 13.4 ± 5.1. There were no significant differences in age, sex, indication, etiology, or MELD score with respect to the control group. The mean initial portal pressure gradients (PPGs) were similar in the 2 groups (21.0 versus 22.4 mm Hg for the OLT patients and controls, respectively), but the final PPG was lower in the control group (9.9 versus 6.9 mm Hg, P < 0.05). The rates of both technical success and clinical success were higher in the control group versus the OLT group [95.5% versus 68.2% (P < 0.05) and 93.2% versus 77.2% (P < 0.05), respectively]. The rates of complications and post-TIPS encephalopathy were similar in the 2 groups, and there was a trend toward increased rates of shunt insufficiency in the OLT group. The mortality rate of the patients with a pre-TIPS MELD score > 15 was significantly higher in the OLT group [hazard ratio (HR) = 4.32, 95% confidence interval (CI) = 1.45-12.88, P < 0.05], but the mortality rates of the patients with a pre-TIPS MELD score < 15 were similar in the 2 groups. In the OLT group, the predictors of increased mortality were the pre-TIPS MELD score (HR = 1.161, 95% CI = 1.036-1.305, P < 0.05) and pre-TIPS MELD scores > 15 (HR = 5.846, 95% CI = 1.754-19.485, P < 0.05). In conclusion, TIPS insertion is feasible in transplant recipients, although its efficacy is lower in these patients versus control patients. Outcomes are poor for OLT recipients with a pre-TIPS MELD score > 15. Liver Transpl 17:771-778, 2011. © 2011 AASLD.
A Novel Approach for Investigation of Chain Transfer Events by Pulsed Laser Polymerization
Authors: Nikitin Anatoly N. , Hutchinson Robin A. , Buback Michael , Hesse Pascal
Published: February 2011

Pulsed laser polymerization (PLP) with subsequent analysis of molecular mass distribution (MMD) is used to determine the rate coefficient of chain transfer to an agent A, ktrA, by varying pulse repetition rate such that the contributions of PLP‐induced and chain‐transfer‐induced peaks to the MMD change to a significant extent. It is shown by simulation that the relative heights of these peaks may be used to estimate ktrA. The method is applied to evaluation of the rate coefficient of chain transfer to dodecyl mercaptan with butyl methacrylate polymerizations at −11, 0, 20 and 40 °C. The Arrhenius parameters for this coefficient are determined to be: A(ktrA) = (2.2 ± 0.6) × 106 L · mol−1 · s−1 and Ea(ktrA) = (22.1 ± 0.7) kJ · mol−1.

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Tandem mass spectrometry strategies for phosphoproteome analysis
Authors: Palumbo Amanda M. , Smith Scott A. , Kalcic Christine L. , Dantus Marcos , Stemmer Paul M. , Reid Gavin E.
Published: February 2011

Protein phosphorylation is involved in nearly all essential biochemical pathways and the deregulation of phosphorylation events has been associated with the onset of numerous diseases. A multitude of tandem mass spectrometry (MS/MS) and multistage MS/MS (i.e., MSn) strategies have been developed in recent years and have been applied toward comprehensive phosphoproteomic analysis, based on the interrogation of proteolytically derived phosphopeptides. However, the utility of each of these MS/MS and MSn approaches for phosphopeptide identification and characterization, including phosphorylation site localization, is critically dependant on the properties of the precursor ion (e.g., polarity and charge state), the specific ion activation method that is employed, and the underlying gas‐phase ion chemistries, mechanisms and other factors that influence the gas‐phase fragmentation behavior of phosphopeptide ions. This review therefore provides an overview of recent studies aimed at developing an improved understanding of these issues, and highlights the advantages and limitations of both established (e.g., CID) and newly maturing (e.g., ECD, ETD, photodissociation, etc.) yet complementary, ion activation techniques. This understanding is expected to facilitate the continued refinement of existing MS/MS strategies, and the development of novel MS/MS techniques for phosphopeptide analysis, with great promise in providing new insights into the role of protein phosphorylation on normal biological function, and in the onset and progression of disease. © 2011 Wiley Periodicals, Inc., Mass Spec Rev 30:600–625, 2011
The Euler Characteristic of Phantom Elastomeric Polymer Networks
Authors: Galiatsatos Vassilios , Heinrich Gert
Published: February 2011

It is shown that through a relationship between the Euler characteristic and the cycle rank of polymer networks one has access to a quantitative description of functionality heterogeneity in these fascinating structures. This relationship is applied and extended to study heterogeneous network structures resulting from the random removal of chains from a perfect 2D tetrafunctional network. It is shown that the distribution of crosslink functionality is correlated strongly with the mechanical properties of the networks as those are manifested in the cycle rank.

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A simple method for approximating a general Pareto surface
Authors: Lehtonen Tapani , Pulkkinen Pertti
Published: February 2011

We present a simple iterative procedure for approximating the Pareto surface of a set S and the only assumption is that S is closed and bounded. The algorithm creates a sequence of upper bounds for the Pareto surface and these upper bounds tighten towards the surface as the number of iteration loops increases towards infinity. The approximation method is further developed towards a tool for optimization in general situations and it may also be applied in interactive multiobjective optimization. Copyright © 2011 John Wiley & Sons, Ltd.
Estimation of the iron concentration in excised gray matter by means of proton relaxation measurements
Authors: Ye Frank Q. , Martin W. R. Wayne , Allen Peter S.
Published: February 2011

To validate their correlation with tissue iron concentration, proton transverse relaxation measurements have been made at 2.35 T (100 MHz) in 25 samples of excised, frozen, but unfixed human gray matter tissue obtained from the globus pallidus, putamen, caudate, thalamus, and cortex of five postmortem brains free of neurological disease. The iron concentration was independently measured, using atomic absorption spectroscopy. The proton transverse relaxation measurements exploited the interecho time dependence of the apparent transverse relaxation rate, R2app, obtained from a Carr‐Purcell‐Meiboom‐Gill (CPMG) sequence. An empirical semilogarithmic relationship between R2app and the interecho time provided a measure of the relaxation enhancement due to iron, namely, a slope p, which demonstrated a significant correlation (r = 0.78, P < 0.001) with tissue iron concentration. Moreover, a simple rate difference, δR2app, determined between interecho time values of 6 and 60 ms, was also found to correlate significantly with iron concentration (r = 0.81, P < 0.001). Both of the foregoing correlations were better than that of R2app itself. When the tissue samples were subdivided into brain structure groups, the intergroup differences in p reflected their known differences in iron accumulation and correlated with those of the mean group iron content, determined by atomic absorption spectrometry.
Decomposition of inflow and blood oxygen level‐dependent (BOLD) effects with dual‐echo spiral gradient‐recalled echo (GRE) fMRI
Authors: Glover Gary H. , Lemieux Susan K. , Drangova Maria , Pauly John M.
Published: February 2011

Image contrast with gradient‐recalled echo sequences (GRE) used for fMRI can have both blood oxygen level‐dependent (BOLD) and inflow components, and the latter is often undesirable. A dual‐echo technique can be used to differentiate these mechanisms, because modulation of signal from inflow is common to both echoes, whereas susceptibility and diffusion‐related signal losses are larger in the second echo. An efficient dual‐echo interleaved spiral sequence was developed for use with a conventional scanner. It uses a κ‐space trajectory that spirals out from the origin while the first echo is collected, then spirals back in while collecting the second echo. Decomposition of the data provides separate images of the inflow and T2*‐weighted components. Results demonstrate the decomposition with phantom experiments and with photic stimulation in normal volunteers.
Movement‐Related effects in fMRI time‐series
Authors: Friston Karl J. , Williams Steven , Howard Robert , Frackowiak Richard S. J. , Turner Robert
Published: February 2011

This paper concerns the spatial and intensity transformations that are required to adjust for the confounding effects of subject movement during functional MRI (fMRI) activation studies. An approach is presented that models, and removes, movement‐related artifacts from fMRI time‐series. This approach is predicated on the observation that movement‐related effects are extant even after perfect realignment. Movement‐related effects can be divided into those that are a function of position of the object in the frame of reference of the scanner and those that are due to movement in previous scans. This second component depends on the history of excitation experienced by spins in a small volume and consequent differences in local saturation. The spin excitation history thus will itself be a function of previous positions, suggesting an autoregression‐moving average model for the effects of previous displacements on the current signal. A model is described as well as the adjustments for movement‐related components that ensue. The empirical analyses suggest that (in extreme situations) over 90% of fMRI signal can be attributed to movement, and that this artifactual component can be successfully removed.
Criteria for analysis of multicomponent tissue T2 relaxation data
Authors: Graham Simon J. , Stanchev Peter L. , Bronskill Michael J.
Published: February 2011

Monte Carlo simulations were performed to determine whether the multicomponent T2 distribution of tissue can be estimated accurately from T2 decay data acquired in vivo. Simulated data were generated for white matter, fast twitch muscle, and breast tissue. The signal‐to‐noise ratio, number of data samples, and minimum echo time were varied from the experimental conditions currently achievable with MRI to those achievable for in vitro experiments. Data were fitted by a distribution of T2 values using the T2NNLS algorithm, and statistics characterizing the estimated T2 components were determined. Current MRI techniques were found to provide conditions insufficient for accurate multicomponent T2 analysis on a pixel‐by‐pixel basis. However, volume localization methods that measure T2 decay from a large volume of interest have potential for this analysis. These results illustrate a general framework for development of new techniques to measure T2 decay accurately in vivo.
Assessment of flow in the right human coronary artery by magnetic resonance phase contrast velocity measurement: Effects of cardiac and respiratory motion
Authors: Hofman Mark B. M. , van Rossum Albert C. , Sprenger Michiel , Westerhof Nico
Published: February 2011

Flow in the human right coronary artery was determined using magnetic resonance phase contrast velocity quantification. Two methods were applied to reduce respiratory motion: imaging during breath holding, which is fast, and retrospective respiratory gating, which has a high temporal resolution (32 ms) in the cardiac cycle. Vessel cross‐sectional area, through‐plane velocity, and volume flow were determined in six healthy subjects. In‐plane vessel displacement during the cardiac cycle, caused by cardiac contraction, was about 2–4 mm within a time frame of 32 ms in systole and early diastole. The motion resulted in blurring of images obtained during breath holding caused by the large acquisition time window (126 ms) within the cardiac cycle. Therefore, only with a high temporal resolution correct velocity images over the entire cardiac cycle could be obtained. The time‐ and cross‐sectionally averaged velocity was 7 ± 2 cm/s, and the volume flow was 30 ± 10 ml/min.
Detection and characterization of primary liver cancer in rats by MS‐264‐enhanced MRI
Authors: Petré Carine , Ni Yicheng , Marcha Guy , Yu Jie , Wevers Martine , Lauffer Randall B. , Baert Albert L.
Published: February 2011

A new MR contrast agent, MS‐264 (Gd(1 RS)‐1‐(p‐butylbenzyl)‐DTPA), was developed to achieve hepatobiliary specificity and its potential evaluated for detecting and characterizing liver tumors in rats with chemically induced hepatocellular carcinoma (HCC). In seven rats with 66 HCC lesions, enhancements of different abdominal organs and tumors were compared on T1‐weighted images after intravenous administration of Gd‐DTPA (0.3 mmol/kg) and MS‐264 (0.05 mmol/kg). MR images were correlated with postmortem microangiographic and histological findings. An overall enhancement of different organs, which normalized within 24 h, was observed after Gd‐DTPA and MS‐264 injection. MS‐264 caused a higher relative enhancement (RE) in liver (60%), compared with that of Gd‐DTPA (40%), which resulted in a prompt negative contrast enhancement in 59 of 66 HCCs. All were moderately to poorly differentiated (Grades II–IV) tumors. Six of these 59 negative contrast‐enhancing lesions showed a positively enhanced peritumoral rim, which corresponded histologically to malignant infiltration (n = 2) or compression (n = 4). On the other hand, six well differentiated HCCs showed prolonged positive enhancement. However, one well differentiated HCC was not positively enhanced by MS‐264, probably due to poor access of the agent to the lesion. In comparison to that of the pre‐contrast images, enhancement with Gd‐DTPA and MS‐264 increased the number of detected lesions by 22 and 42%, respectively. In this animal study, MS‐264 proved to be useful in detection and characterization of primary liver cancers.
A new design for a three‐channel surface gradient coil employing a three‐dimensional finite element model
Authors: Shi Funan , Latour Lawrence L. , Ludwig Reinhold , Sotak Christopher H.
Published: February 2011

A new design of a three‐channel surface gradient coil (SGC) is presented. The optimal objective of this design is to minimize parasitic field gradients by modifying the wire arrangement in the individual coils. A 3D finite element (FE) model is employed to analyze the SGC's field predictions. The numerical analysis results of the new SGC design indicate improved field behaviors when compared with those of a previously reported SGC designed by Cho and Yi (J. Magn. Resort. 94, 471–485 (1991)). To confirm the predicted improvement, two Gy (y‐axis) gradient coils, based on the old and new designs, have been constructed and installed in a General Electric CSI 2 Tesla MRI system with a 15‐cm bore. Based on the resulting MR images, the new gradient coil configuration provides more uniform field gradients and less parasitic field gradients, which results in higher quality images than the previously reported SGC design. This paper also demonstrates the remarkable accuracy of the 3D FE simulation model.
Alternate k‐space sampling in EPI: Compensation for T2* and adjustable T2 weighting
Authors: Aletras Anthony H. , Abduljalil Amir M. , Robitaille Pierre‐Marie L.
Published: February 2011

In this work, preliminary results are described for a modification of the MBEST sampling scheme such that image resolution can be increased while preserving image contrast. In this new approach, a single spin‐echo is used in sampling k‐space. The basic idea relies on acquiring a conventional EPI image from the center of k‐space and applying a ψ pulse to permit the acquisition of the two outer edges of k‐space. Using this new approach, it is possible to obtain an enhancement in EPI image resolution, while reducing the extent of T2* weighting. As a result, the resulting images possess reduced T2* contrast and suffer less signal loss from T2* effects such as spatial variations in susceptibility and field inhomogeneity.
Monitoring tissue development in acellular matrix‐based regeneration for bladder tissue engineering: Multiexponential diffusion and T2* for improved specificity
Authors: Cheng Hai‐Ling Margaret , Loai Yasir , Farhat Walid A.
Published: February 2011

Cell‐seeded acellular matrices (ACMs) are a promising approach for the tissue engineering of soft tissues and organs, such as the urinary bladder. ACM contains site‐preferred structural and functional molecules, and degradation products derived from ACM play important roles in tissue remodeling. Regeneration proceeds along concurrent trajectories of cell growth and matrix degradation, characterized by evolving biophysical and biochemical properties. The assessment of tissue development through a noninvasive imaging technique, such as MRI, must therefore be capable of distinguishing these concurrent biophysical and biochemical changes. However, although MRI provides exquisite sensitivity to tissue microstructure, composition and function, specificity remains limited. In this study, multiexponential diffusion and the effective transverse relaxation time T2* were investigated for their ability to assess cell growth and tissue composition, respectively. Bladder ACMs prepared with and without hyaluronic acid, and ACMs seeded with smooth muscle cells, were assessed on MRI. The slow diffusion fraction from multiexponential diffusion analysis demonstrated the best correlation with cellularity, with minimal influence from underlying matrix degradation. T2* measurements were sensitive to macromolecular content, specifically the presence of hyaluronic acid, without confounding influence from tissue hydration. T2* also appeared to be sensitive to cell filling of the matrix pore space. Compared with these metrics, commonly used MRI parameters, such as T1, T2 and single diffusion coefficients, were more limited in specificity. The use of T2 to measure tissue structure and composition is limited by its large dependence on water content, and single diffusion can only reflect the overall characteristics of the extra‐ and intracellular environment. These findings are important for further development of more specific MRI methods for the monitoring of regeneration in tissue‐engineered systems. Copyright © 2011 John Wiley & Sons, Ltd.
7‐T 1H MRS with adiabatic refocusing at short TE using radiofrequency focusing with a dual‐channel volume transmit coil
Authors: Boer V.O. , van Lier A.L.H.M.W. , Hoogduin J.M. , Wijnen J.P. , Luijten P.R. , Klomp D.W.J.
Published: February 2011

In vivo MRS of the human brain at ultrahigh field allows for the identification of a large number of metabolites at higher spatial resolutions than currently possible in clinical practice. However, the in vivo localization of single‐voxel spectroscopy has been shown to be challenging at ultrahigh field because of the low bandwidth of refocusing radiofrequency (RF) pulses. Thus far, the proposed methods for localized MRS at 7 T suffer from long TE, inherent signal loss and/or a large chemical shift displacement artifact that causes a spatial displacement between resonances, and results in a decreased efficiency in editing sequences. In this work, we show that, by driving a standard volume coil with two RF amplifiers, focusing the B field in a certain location and using high‐bandwidth adiabatic refocusing pulses, a semi‐LASER (semi‐localized by adiabatic selective refocusing) localization is feasible at short TE in the human brain with full signal acquisition and a low chemical shift displacement artifact at 7 T. Copyright © 2011 John Wiley & Sons, Ltd.
Optimal power control in OFDMA cellular networks
Authors: Detti Paolo , Nicosia Gaia , Pacifici Andrea , Servilio Mara
Published: February 2011

This article addresses the problem of allocating users to radio resources in the downlink of an OFDMA cellular system. We consider a classical multicellular environment with a realistic interference model and a margin adaptive approach, i.e., we aim at minimizing total transmission power while maintaining a certain given rate for each user. We discuss computational complexity issues of the resulting model and present a heuristic approach that finds optima under suitable conditions or reasonably good solutions in the general case. Computational experiments show the effectiveness of the proposed heuristic in a comparison with both a commercial state‐of‐the‐art optimization solver and other approaches from the literature. © 2011 Wiley Periodicals, Inc. NETWORKS, 2011
Ill‐conditioning of the truncated singular value decomposition, Tikhonov regularization and their applications to numerical partial differential equations
Authors: Li Zi‐Cai , Huang Hung‐Tsai , Wei Yimin
Published: February 2011

This paper explores some intrinsic characteristics of accuracy and stability for the truncated singular value decomposition (TSVD) and the Tikhonov regularization (TR), which can be applied to numerical solutions of partial differential equations (numerical PDE). The ill‐conditioning is a severe issue for numerical methods, in particular when the minimal singular value sigmamin of the stiffness matrix is close to zero, and when the singular vector umin of σmin is highly oscillating. TSVD and TR can be used as numerical techniques for seeking stable solutions of linear algebraic equations. In this paper, new bounds are derived for the condition number and the effective condition number which can be used to improve ill‐conditioning by TSVD and TR. A brief error analysis of TSVD and TR is also made, since both errors and condition number are essential for the numerical solution of PDE. Numerical experiments are reported for the discrete Laplace operator by the method of fundamental solutions. Copyright © 2011 John Wiley & Sons, Ltd.
OLEDs und organische Elektronik auf dem Vormarsch
Authors: Birnstock Jan , Haldi Andreas
Published: February 2011

Organische Leuchtdioden, kurz OLEDs, sind heutzutage in einigen mobilen Displayanwendungen anzutreffen und auch der erste OLED‐Fernseher ist schon auf dem Markt erhältlich. Dank der kontinuierlichen Effizienzsteigerung der OLEDs in den letzten Jahren, die auch durch Redoxdotierung der organischen Materialien ermöglicht wurde, werden OLEDs zukünftig jedoch auch in der Wohnbeleuchtung eine Alternative zur traditionellen Glühlampe bieten. Die Redoxdotierung könnte aber auch anderen organischen Halbleiterbauelementen zum Durchbruch verhelfen.
Noise in Laser Technology
Authors: Paschotta Rüdiger
Published: February 2011

Lasers can exhibit various kinds of “noise”, with manifold influences on applications. Here we discuss where such noise can come from, how it is quantified and how its influences can be minimized.
From Terra Incognita to Security Technology
Authors: Deninger Anselm
Published: February 2011

Not long ago, the terahertz frequency range was considered the last remaining gap of the electromagnetic spectrum. The main reason was the difficulty of generating intense, directional terahertz radiation. During the past few years, optoelectronic approaches based on modern laser technologies have helped to bridge the “terahertz gap”. This report discusses some of the scenarios in which terahertz technologies are just about to make their industrial entrance — in applications as varied as trace gas detection, process control, and the imaging of airbag safety covers.
Komplementäre Mikroskopie‐Techniken intelligent kombiniert
Authors: Fischer Harald
Published: February 2011

In Life Science, der chemisch‐pharmazeutischen Analytik und in den modernen Materialwissenschaften spielen zerstörungsfreie Analysenmethoden eine elementare Rolle und sind in Forschung und Entwicklung nicht mehr wegzudenken. Die konfokale Raman Mikroskopie stellt dabei ein Instrument dar, mit der die chemische Zusammensetzung einer Probe mit einer Ortsauflösung im subMikrometerbereich untersucht werden kann. Durch eine Kombination dieser Technik mit der Rasterkraftmikroskopie ist der Erhalt umfangreicher Informationen über die Struktur und die chemischen Eigenschaften der Probe möglich.
Nanoimprint Lithography
Authors: Glinsner Thomas , Kreindl Gerald , Kast Michael
Published: February 2011

CMOS image sensors represent a multi‐billion‐dollar market, with continued growth expected due to increasing demand for a multitude of consumer and industrial applications. To continue to drive down manufacturing costs while enabling increased device performance, manufacturers are looking to innovative production methods, such as nanoimprint lithography (NIL). In addition to lower cost, NIL offers high repeatability and accuracy, all of which are particularly critical for ensuring optimal production of micro lenses, which are an integral part of the CMOS image sensor. Beyond CMOS image sensors, NIL offers the potential to enable a number of other device applications, from high‐brightness light emitting diodes (HB‐LEDs) to micro‐fluidics.
Laseroptiken für den Weltraum im Test
Authors: Riede Wolfgang , Schröder Helmut
Published: February 2011

Der Einsatz des Lasers bietet im Bereich der Raumfahrt ein enormes Potenzial und einzigartige Möglichkeiten zur Klärung aktueller globaler Fragestellungen. Die Anforderungen an die Präzision und Zuverlässigkeit der Systeme sind jedoch extrem hoch, und eine aufwändige Qualifizierung aller Komponenten ist für einen Missionserfolg unabdingbar. Ein Forscherteam am Institut für Technische Physik des Deutschen Zentrums für Luftund Raumfahrt (DLR) in Stuttgart ist sowohl mit der Qualifizierung als auch mit den entsprechenden wissenschaftlichen Fragestellungen zur Charakterisierung von Laseroptiken für Weltraumanwendungen beschäftigt.
Chirped‐Pulse Amplification
Authors: Jovanovic Igor
Published: February 2011

Introduction of chirped‐pulse amplification (CPA) enabled the latest revolution in production of high peak powers from lasers through amplification of very short (femtosecond) laser pulses to pulse energies previously available only from long‐pulse lasers. CPA has rapidly bridged the gap from its initial modest demonstrations to multi‐terawatt and petawattscale systems in research facilities and universities, as well as numerous lowerpower scientific and industrial applications.
Ultrashort laser pulses in regenerative medicine
Authors: Heisterkamp Alexander
Published: February 2011

The goal of regenerative medicine is to reconstitute organ functions or to replace damaged or degenerated tissue by cell therapies or tissue engineering. Within this field, the use of optical methods for imaging and manipulation of cells and tissue down to the subcellular level provides a precise and non‐contact way for new therapies. This includes applications of ultrashort laser pulses for high resolution imaging as well as precise and selective cell manipulation.
In situ immune response after neoadjuvant chemotherapy for breast cancer predicts survival
Authors: Ladoire Sylvain , Mignot Grégoire , Dabakuyo Sandrine , Arnould Laurent , Apetoh Lionel , Rébé Cedric , Coudert Bruno , Martin Francois , Bizollon Marie Hélène , Vanoli André , Coutant Charles , Fumoleau Pierre , Bonnetain Franck , Ghiringhelli François
Published: February 2011

Accumulating preclinical evidence suggests that anticancer immune responses contribute to the success of chemotherapy. However, the predictive value of tumour‐infiltrating lymphocytes after neoadjuvant chemotherapy for breast cancer remains unknown. We hypothesized that the nature of the immune infiltrate following neoadjuvant chemotherapy would predict patient survival. In a series of 111 consecutive HER2‐ and a series of 51 non‐HER2‐overexpressing breast cancer patients treated by neoadjuvant chemotherapy, we studied by immunohistochemistry tumour infiltration by FOXP3 and CD8 T lymphocytes before and after chemotherapy. Kaplan‐Meier analysis and Cox modelling were used to assess relapse‐free survival (RFS) and overall survival (OS). A predictive scoring system using American Joint Committee on Cancer (AJCC) pathological staging and immunological markers was created. Association of high CD8 and low FOXP3 cell infiltrates after chemotherapy was significantly associated with improved RFS (p = 0.02) and OS (p = 0.002), and outperformed classical predictive factors in multivariate analysis. A combined score associating CD8/FOXP3 ratio and pathological AJCC staging isolated a subgroup of patients with a long‐term overall survival of 100%. Importantly, this score also identified patients with a favourable prognosis in an independent cohort of HER2‐negative breast cancer patients. These results suggest that immunological CD8 and FOXP3 cell infiltrate after treatment is an independent predictive factor of survival in breast cancer patients treated with neoadjuvant chemotherapy and provides new insights into the role of the immune milieu and cancer. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Fabrication of super water repellent silver flake/copolymer blend films and their potential as smart fabrics
Authors: Bayer I. S. , Biswas A. , Ellialtioglu G.
Published: February 2011

A facile technique is demonstrated for the fabrication of super water repellent co‐polymer blend‐silver composite films from fatty acid surface functionalized fine silver flakes. Initially, high concentrations of surface functionalized silver flakes were dispersed in poly(vinyl chloride‐co‐vinyl acetate‐co‐vinyl alcohol) copolymer in solution to form electrically conducting adhesives/paints (ECAs) with a bulk resistivity of ∼3 × 10−5 Ω cm. The solvent‐borne ECAs were then blended with a water‐dispersed perfluoromethacrylate copolymer (Zonyl 8740) using a simple solvent‐inversion process to obtain super water‐repellent colloidal copolymer blend‐silver emulsions. The colloidal emulsions could be spray‐deposited on a number of fibrous substrates including fabrics and paper. A particular example is demonstrated herein by spray‐depositing these emulsions onto molten paraffin wax‐based laminates (60°C), which were partially impregnated into fabrics to fabricate highly water repellent, flexible, and thermoresponsive fabrics. A paraffin wax/polyolefin blend base film was used for the purpose. The surface topology of the superhydrophobic copolymer/silver composite films displayed fractal‐like hierarchical structures ideal for self‐cleaning hydrophobicity. On relatively low‐absorbent permeable porous surfaces such as cellulosic films (paper) impregnated with wax/polyolefin films, self‐cleaning ability of the coatings was maintained even for temperatures at which paraffin wax component of the laminated film was molten indicated by low‐water roll‐off angles. Hence, the composites have excellent compatibility with organic phase change materials such as paraffin wax and wax/polyolefin blends, and they can be used to fabricate nonwetting, thermoregulated, and electroactive fabrics. Antimicrobial properties of silver offer additional advantages for potential biomedical applications. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers