bluuebunny/crossref_metadata_2025 huggingface dataset:
High resolution three‐dimensional cine phase contrast MRI of small intracranial aneurysms using a stack of stars k‐space trajectory
Authors: Kecskemeti Steven , Johnson Kevin , Wu Yijing , Mistretta Charles , Turski Patrick , Wieben Oliver
Published: February 2012

Purpose:

To develop a method for targeted volumetric, three directional cine phase contrast (PC) imaging with high spatial resolution in clinically feasible scan times.

Materials and Methods:

A hybrid radial‐Cartesian k‐space trajectory is used for cardiac gated, volumetric imaging with three directional velocity encoding. Imaging times are reduced by radial undersampling and temporal viewsharing. Phase contrast angiograms are displayed in a new approach that addresses the concern of signal drop out in regions of slow flow. The feasibility of the PC stack of stars (SOS) trajectory was demonstrated with an in vivo study capturing 14 small intracranial aneurysms (2–10 mm). Aneurysm measures from six aneurysms also imaged with digital subtraction angiography (DSA) were compared with linear regression with those from the PC SOS images.

Results:

All aneurysms were identified on the phase contrast angiograms. The geometric measures from PC SOS and DSA were in good agreement (linear regression: slope = 0.89, intercept = 0.35, R∧2 = 0.88).

Conclusion:

PC SOS is a promising method for obtaining volumetric angiograms and cine phase contrast velocity measurements in three dimensions. Acquired spatial resolutions of 0.4 × 0.4 × (0.7–1.0) mm make this method especially promising for studying flow in small intracranial aneurysms. J. Magn. Reson. Imaging 2012. © 2012 Wiley Periodicals, Inc.
Comparison of statistical inferences from the DerSimonian–Laird and alternative random‐effects model meta‐analyses – an empirical assessment of 920 Cochrane primary outcome meta‐analyses
Authors: Thorlund Kristian , Wetterslev Jørn , Awad Tahany , Thabane Lehana , Gluud Christian
Published: February 2012

In random‐effects model meta‐analysis, the conventional DerSimonian–Laird (DL) estimator typically underestimates the between‐trial variance. Alternative variance estimators have been proposed to address this bias. This study aims to empirically compare statistical inferences from random‐effects model meta‐analyses on the basis of the DL estimator and four alternative estimators, as well as distributional assumptions (normal distribution and t‐distribution) about the pooled intervention effect. We evaluated the discrepancies of p‐values, 95% confidence intervals (CIs) in statistically significant meta‐analyses, and the degree (percentage) of statistical heterogeneity (e.g. I2) across 920 Cochrane primary outcome meta‐analyses. In total, 414 of the 920 meta‐analyses were statistically significant with the DL meta‐analysis, and 506 were not. Compared with the DL estimator, the four alternative estimators yielded p‐values and CIs that could be interpreted as discordant in up to 11.6% or 6% of the included meta‐analyses pending whether a normal distribution or a t‐distribution of the intervention effect estimates were assumed. Large discrepancies were observed for the measures of degree of heterogeneity when comparing DL with each of the four alternative estimators. Estimating the degree (percentage) of heterogeneity on the basis of less biased between‐trial variance estimators seems preferable to current practice. Disclosing inferential sensitivity of p‐values and CIs may also be necessary when borderline significant results have substantial impact on the conclusion. Copyright © 2012 John Wiley & Sons, Ltd.
A proposal for the timing of management of patients with melanoma presenting during pregnancy
Authors: Broer Niclas , Buonocore Samuel , Goldberg Carolyn , Truini Carolyn , Faries Marc B. , Narayan Deepak , Ariyan Stephan
Published: February 2012

The treatment of melanoma during and immediately after pregnancy poses a significant challenge to surgeons, oncologists, and patients alike. With the overall increase in incidence of melanoma in the United States and worldwide, it is likely that more surgeons will be faced with management decisions regarding pregnant patients with melanoma. We report on five patients who presented to the Yale Melanoma Unit with melanoma during their pregnancy. We propose the management option of resection of the primary tumor under local anesthesia, and postponing of the sentinel lymph node biopsy until after the birth of the child. The completion lymphadenectomy can be performed if these nodes are found to be harboring metastases. We further discuss treatment options and propose an algorithm for management of patients diagnosed with melanoma while pregnant. J. Surg. Oncol. 2012; 106:36–40. © 2012 Wiley Periodicals, Inc.
Pulsed Light Irradiation Improves Behavioral Outcome in a Rat Model of Chronic Mild Stress
Authors: Wu Xingjia , Alberico Stephanie L. , Moges Helina , De Taboada Luis , Tedford Clark E. , Anders Juanita J.
Published: February 2012

Background and Objective

Transcranial laser therapy (TLT) has been used successfully for the treatment of stroke in animal models and clinical trials. These results support the hypothesis that TLT could be used to treat other central nervous system conditions, such as depression. Current therapy for depression emphasizes pharmaco‐therapeutics. However, these interventions often cause unwanted side effects. Here, TLT as a treatment for depression was studied in a rat model of chronic mild stress (CMS).

Study Design/Material and Methods

Wistar rats were randomized into four experimental groups (n = 8): (1) No‐stress; (2) stress without treatment (Stress); (3) stress treated with an antidepressant (Drug); and (4) stress treated with TLT (TLT). The rats in the stress groups were exposed sequentially to a variety of mild stressors for 8 weeks. Rats were weighed weekly. After 5 weeks of stressing, the Drug group received a daily injection of fluoxetine (10 mg/kg), and the TLT group was irradiated transcranially 3 times a week (810 nm wavelength laser, 3 mm diameter probe, 350 mW peak power, 100 Hz with 20% duty cycle, 2‐minute treatment time, 120 J/cm2 average energy density on skin surface). After 3 weeks of treatment, a forced swimming test (FST) was performed and recorded for behavioral assessment. Animals were euthanized after 8 weeks of the study.

Results

The No‐stress group had significantly higher body weight than stress groups from week 5 (P < 0.05). No weight difference was found between the stress groups before treatment. However, the Drug group had significantly less body weight than both Stress and TLT groups after 2 weeks of treatment (P < 0.05). FST showed that the Stress group had significantly more immobility than the No‐stress group (P < 0.05). Both Drug and TLT groups had significantly less immobility than the stress group (P < 0.05). There was no significant difference in immobility between both Drug and TLT groups (P = 0.62).

Conclusions

TLT was comparable to fluoxetine in improving the behavioral outcome after CMS. TLT did not cause weight loss, which is consistently seen in patients treated with fluoxetine. This study demonstrates that TLT has potential as an effective treatment for depression. Lasers Surg. Med. 44:227–232, 2012. © 2012 Wiley Periodicals, Inc.
Outcomes of liver transplant recipients with hepatitis C and human immunodeficiency virus coinfection
Authors: Terrault Norah A. , Roland Michelle E. , Schiano Thomas , Dove Lorna , Wong Michael T. , Poordad Fred , Ragni Margaret V. , Barin Burc , Simon David , Olthoff Kim M. , Johnson Lynt , Stosor Valentina , Jayaweera Dushyantha , Fung John , Sherman Kenneth E. , Subramanian Aruna , Millis Michael J. , Slakey Douglas , Berg Carl L. , Carlson Laurie , Ferrell Linda , Stablein Donald M. , Odim Jonah , Fox Lawrence , Stock Peter G.
Published: February 2012

Hepatitis C virus (HCV) is a controversial indication for liver transplantation (LT) in human immunodeficiency virus (HIV)–infected patients because of reportedly poor outcomes. This prospective, multicenter US cohort study compared patient and graft survival for 89 HCV/HIV-coinfected patients and 2 control groups: 235 HCV-monoinfected LT controls and all US transplant recipients who were 65 years old or older. The 3-year patient and graft survival rates were 60% [95% confidence interval (CI) = 47%-71%] and 53% (95% CI = 40%-64%) for the HCV/HIV patients and 79% (95% CI = 72%-84%) and 74% (95% CI = 66%-79%) for the HCV-infected recipients (P < 0.001 for both), and HIV infection was the only factor significantly associated with reduced patient and graft survival. Among the HCV/HIV patients, older donor age [hazard ratio (HR) = 1.3 per decade], combined kidney-liver transplantation (HR = 3.8), an anti-HCV–positive donor (HR = 2.5), and a body mass index < 21 kg/m2 (HR = 3.2) were independent predictors of graft loss. For the patients without the last 3 factors, the patient and graft survival rates were similar to those for US LT recipients. The 3-year incidence of treated acute rejection was 1.6-fold higher for the HCV/HIV patients versus the HCV patients (39% versus 24%, log rank P = 0.02), but the cumulative rates of severe HCV disease at 3 years were not significantly different (29% versus 23%, P = 0.21). In conclusion, patient and graft survival rates are lower for HCV/HIV-coinfected LT patients versus HCV-monoinfected LT patients. Importantly, the rates of treated acute rejection (but not the rates of HCV disease severity) are significantly higher for HCV/HIV-coinfected recipients versus HCV-infected recipients. Our results indicate that HCV per se is not a contraindication to LT in HIV patients, but recipient and donor selection and the management of acute rejection strongly influence outcomes.
Decay of the energy for the Benjamin–Bona–Mahony equation posed on bounded intervals and on a half‐line
Authors: Larkin Nikolai A. , Vishnevskii Mikhail P.
Published: February 2012

This paper concerns nonlinear dissipative initial boundary value problems for the Benjamin–Bona–Mahony equation posed on a half‐line and on bounded intervals. We prove the existence and uniqueness of global solutions and decay of the energy as time tends to infinity as well as convergence of solutions on bounded intervals to a solution on a half‐line. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of glucose concentration during in vitro culture of mouse embryos on development to blastocyst, success of embryo transfer, and litter sex ratio
Authors: Bermejo‐Alvarez P. , Roberts R.M. , Rosenfeld C.S.
Published: February 2012

A high‐glucose concentration in the reproductive tract during early development may result in aberrant embryo or fetal development, with effects that could have a greater impact on one sex than the other. Here, we determine if a high‐glucose concentration impacts embryo development and pregnancy outcomes in a sex‐specific manner in the mouse. Zygotes were cultured in potassium simple optimized medium, which typically contains 0.2 mM D‐glucose, with and without additional glucose supplementation to a concentration of 28 mM. Zygote cleavage and blastocyst rate did not differ between treatments, but total and trophectoderm cell counts were reduced in blastocysts cultured in a high glucose. No differences between sexes nor inner cell mass cell number were observed within each treatment. Blastocysts developed in both media were transferred to recipients. The percentage of blastocysts resulting in viable pups was significantly reduced when the blastocysts were cultured in 28 mM glucose (74 ± 4%, controls vs. 55.8 ± 7.1%, 28 mM glucose), but conceptus loss affected both sexes equally as litter sex ratio did not differ between treatments (52.7% and 52.2% males for controls and high glucose, respectively). Pup body weight at birth was higher for males than females, but was not affected by earlier culture in high glucose. In conclusion, in vitro culture in medium with a glucose concentration approximating that of diabetic serum reduces total and trophectoderm cell numbers at the blastocyst stage and conceptus development to term, but these detrimental effects are not sex‐specific. Mol. Reprod. Dev. 79: 329–336, 2012. © 2012 Wiley Periodicals, Inc.
Cloning the uteroglobin gene promoter from the relic volcano rabbit (Romerolagus diazi) reveals an ancient estrogen‐response element
Authors: Acosta‐MontesdeOca Adriana , Zariñán Teresa , Macías Héctor , Pérez‐Solís Marco A. , Ulloa‐Aguirre Alfredo , Gutiérrez‐Sagal Rubén
Published: February 2012

To gain further insight on the estrogen‐dependent transcriptional regulation of the uteroglobin (UG) gene, we cloned the 5′‐flanking region of the UG gene from the phylogenetically ancient volcano rabbit (Romerolagus diazi; Rd). The cloned region spans 812 base pairs (bp; −812/−1) and contains a noncanonical TATA box (TACA). The translation start site is 48 bp downstream from the putative transcription initiation site (AGA), and is preceded by a consensus Kozak box. Comparison of the Rd‐UG gene with that previously isolated from rabbits (Oryctolagus cuniculus) showed 93% in sequence identity as well as a number of conserved cis‐acting elements, including the estrogen‐response element (ERE; −265/−251), which differs from the consensus by two nucleotides. In MCF‐7 cells, 17β‐estradiol (E2) induced transcription of a luciferase reporter driven by the Rd‐UG promoter in a similar manner as in an equivalent rabbit UG reporter; the Rd‐UG promoter was 30% more responsive to E2 than the rabbit promoter. Mutagenesis studies on the Rd‐ERE confirmed this cis‐element as a target of E2 as two luciferase mutant reporters of the Rd‐promoter, one with the rabbit and the other with the consensus ERE, were more responsive to the hormone than the wild‐type reporter. Gel shift and super‐shift assays showed that estrogen receptor‐α indeed binds to the imperfect palindromic sequence of the Rd‐ERE. Mol. Reprod. Dev. 79: 337–345, 2012. © 2012 Wiley Periodicals, Inc.
Minimum‐time anti‐swing motion planning of cranes using linear programming
Authors: Da Cruz J.J. , Leonardi F.
Published: February 2012

A novel method to solve the minimum‐time anti‐swing motion planning problem for cranes based on the use of linear programming is proposed. It is shown that its solution can be obtained by solving a sequence of fixed‐time maximum‐range linear programming problems. A convergence proof is presented. A classical kinematical model for which the trolley acceleration is the control variable is used. The crane motion equations are discretized in time assuming that the control variable is piecewise constant. Inequality constraints on both trolley speed and acceleration are included to represent physical bounds associated to the electromechanical driving system. The load and the trolley are required to be at rest both at the initial and at the final times. The load cable length as a function of time is assumed given. The ease of both the formulation and the solution of the problem is in contrast with the traditional two‐point boundary value problem associated to the Pontryagin's minimum principle. Copyright © 2012 John Wiley & Sons, Ltd.
A time‐varying coefficient‐based manipulability‐maximizing scheme for motion control of redundant robots subject to varying joint‐velocity limits
Authors: Zhang Yunong , Li Jun , Zhang Zhijun
Published: February 2012

A time‐varying coefficient‐based manipulability‐maximizing (TVCMM) scheme subject to varying joint‐velocity limits (VJVL) is proposed and investigated in this paper for the optimal motion control of redundant robot manipulators (where a planar robot manipulator is specifically considered). In order to improve the manipulability during the end‐effector task execution, a manipulability‐maximizing index is considered into the scheme formulation. Besides, for the remedy of the nonzero initial/final joint‐velocity problem, a time‐varying coefficient is introduced and incorporated in the scheme, which is further reformulated as a quadratic program (QP) subject to equality and bound constraints. For guaranteeing the physical realizability of such a scheme, an efficient linear variational inequality‐based (LVI‐based) numerical algorithm is employed to solve such a QP, and an experiment based on a 6‐DOF manipulator is presented, of which the redundancy is on the horizontal plane. Simulative and experimental results validate the physical realization, effectiveness, and accuracy of the proposed QP‐based manipulability‐maximizing scheme. Copyright © 2012 John Wiley & Sons, Ltd.
Solution of linear optimal control problems with time delay using a composite Chebyshev finite difference method
Authors: Marzban H.R. , Hoseini S.M.
Published: February 2012

In this paper, a composite Chebyshev finite difference method is introduced and applied for finding the solution of optimal control of time‐delay systems with a quadratic performance index. This method is an extension of the Chebyshev finite difference scheme. The proposed method can be regarded as a nonuniform finite difference scheme and is based on a hybrid of block‐pulse functions and Chebyshev polynomials using the well‐known Chebyshev–Gauss–Lobatto points. Various types of time‐delay systems are included to demonstrate the validity and the applicability of the technique. The method is easy to implement and provides very accurate results. Copyright © 2012 John Wiley & Sons, Ltd.
Deposition of Fluorocarbon Nanoclusters by Gas Aggregation Cluster Source
Authors: Drábik Martin , Serov Anton , Kylián Ondřej , Choukourov Andrei , Artemenko Anna , Kousal Jaroslav , Polonskyi Oleksandr , Biederman Hynek
Published: February 2012

Gas aggregation cluster source based on planar magnetron was used for deposition of fluorocarbon nanocluster films. The films possess a high roughness with a size of nanoclusters estimated to be about 30 nm in average. Their chemical structure was found to resemble that of a conventional bulk polytetrafluoroethylene which was confirmed by X‐ray photoelectron spectroscopy and Fourier‐transform infrared spectroscopy. The fluorine to carbon elemental ratio was found to be 1.95 with 86% of CF2 structural units. The deposited films revealed super‐hydrophobic character with values of water contact angle reaching over 170°.

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Exploration of the tree‐level S‐matrix of massless particles
Authors: Benincasa P.
Published: February 2012

In recent years, the BCFW construction provided a very powerful tool for computing scattering amplitudes as well as it shed light on the perturbation theory structure. In this talk, I discuss the long‐standing issue of the boundary term arising when the amplitudes do not vanish as some momenta are taken to infinity along some complex direction. In particular, we provide a new set of on‐shell recursion relations valid for such theories and discuss its consequences on our understanding on the perturbation theory structure of the S‐Matrix.
Characterization of low Al content AlxGa1−xN epitaxial films grown by atmospheric‐pressure MOVPE
Authors: Touré A. , Halidou I. , Benzarti Z. , Fouzri A. , Bchetnia A. , El Jani B.
Published: February 2012

AlxGa1−xN epitaxial films grown on GaN/sapphire by atmospheric‐pressure metalorganic vapor phase epitaxy (AP‐MOVPE) using trimethylgallium (TMG) and trimethylaluminum (TMA) as group III precursors have been studied. Two groups of samples were grown. The aluminum (Al) solid composition of AlxGa1−xN was varied in the range from 0.03 to 0.20 by changing the molar flow ratio [TMA/(TMA + TMG)]. The effect of TMA flow rate, respectively, TMG flow rate, on the growth rate, and Al solid composition is discussed. The structural properties of the alloys have been investigated by high‐resolution X‐ray diffraction (HRXRD). The optical properties of these samples were investigated by photoluminescence (PL). It is found that on increasing Al solid composition, via an increase of the TMA flow rate, the structural quality is deteriorated and the growth efficiency decreases. On the other hand, when the TMG flow rate is reduced, a decrease of the full width at half‐maximum (FWHM) is observed with Al content.
A new dual‐material (DM) gate design to improve the subthreshold behavior of deep submicron GaN‐MESFETs
Authors: Lakhdar Nacereddine , Djeffal Fayçal , Dibi Zohir
Published: February 2012

In the present work, we present a new design called the Dual‐Material‐gate (DM) Gallium Nitride (GaN)‐MESFET to improve the immunity against short channel effects (SCEs). The analytical analysis includes the modeling of the channel potential, subthreshold swing, threshold voltage and Drain‐Induced Lowering Barrier (DIBL). The influence of gate length and the work function of each gate region on subthreshold behavior was investigated using the developed analytical models. The developed analytical approaches are verified and validated by the good agreement found with the 2D numerical simulations for wide range of device parameters and bias conditions. The proposed (DM) GaN‐MESFET can alleviate the critical problem and further improve the immunity of SCEs of deep submicron GaN‐MESFET‐based circuits for low power and high Frequency applications (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Real‐time studies of In‐adlayer during PAMBE of InGaN/GaN MQWs
Authors: Kim Tong‐Ho , Losurdo Maria , Choi Soojeong , Yoon Inho , Bruno Giovanni , Brown April
Published: February 2012

The control of In adlayer during plasma‐assisted molecular beam epitaxy (PAMBE) of InGaN/GaN multiquantum wells (MQWs) is critical to achieve good structural and optical properties. This contribution focuses on the investigation by real‐time spectroscopic ellipsometry, corroborated by reflection high energy electron diffraction (RHEED), of In adlayer during the PAMBE growth of InGaN/GaN MQWs. The ellipsometric data reveal In accumulation during InGaN growth, which results in thicker quantum well than designed. We address the effect of the indium adlayer on the growth of InGaN/GaN with an indium composition between 7% and 13%, and on their optical and structural properties determined by high‐resolution X‐ray diffraction and photoluminescence. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction of mechanical stresses in GaN/sapphire templates via formation of regular porous structure
Authors: Ivukin Ivan N. , Bougrov Vladislav E. , Odnoblyudov Maxim A. , Romanov Alexey E.
Published: February 2012

Reduction of mechanical stresses generated at a GaN/sapphire interface is an important issue on the way to more reliable and mechanically stable templates for manufacturing of efficient light‐emitting diodes. One of the techniques to reduce such stresses is the formation of the patterned porous structure in a GaN film in the vicinity of the GaN/sapphire interface by GaN overgrowth. The aim of the present study is to determine the effectiveness of the described method in reducing internal stresses and to find out the preferential configuration for the patterned structure. To achieve the aim, we performed a parametrical study of stresses in the structure, which consists of a porous GaN film and a sapphire substrate, by varying geometrical parameters of the pattern. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of In incorporation into the quantum well active region on the efficiency of AlGaN‐based ultraviolet light‐emitting diodes
Authors: Passow Thorsten , Gutt Richard , Kunzer Michael , Kirste Lutz , Pletschen Wilfried , Forghani Kamran , Scholz Ferdinand , Köhler Klaus , Wagner Joachim
Published: February 2012

Improving the internal quantum efficiency is still a major challenge for realizing efficient III‐nitride‐based light‐emitting diodes (LEDs) with emission wavelengths below 365 nm. Here, we report on the influence of a very low In amount of less than 1% on the luminescence properties of single Ga(In)N/AlGaN quantum well (QW) structures and the performance of AlGaN‐based LEDs with an emission wavelength of about 350 nm. The samples were grown by metalorganic vapor phase epitaxy on low defect density AlGaN buffer layers on (0001) sapphire substrates. The temperature dependence of the QW emission energy reveals a clear “S‐shape” behaviour indicating a significant carrier localization for In containing QWs. The electroluminescence efficiency of LEDs with a GaInN QW active region could be improved by a factor of 4 compared to LEDs with GaN QW, resulting in a continuous wave (cw) output power of 8.2 mW at 40 mA. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AFM Study for Morphological Characteristics and Biomechanical Properties of Human Cataract Anterior Lens Capsules
Authors: Choi Samjin , Lee Hui‐Jae , Cheong Youjin , Shin Jae‐Ho , Jin Kyung‐Hyun , Park Hun‐Kuk , Park Young‐Guk
Published: February 2012

The aim of this study was to quantitatively investigate the morphologies (surface roughness) and biomechanical properties (Young's modulus) of human anterior lens capsules (ALCs) for noncataract and cataract groups using atomic force microscopy. Eight human ALCs obtained during phacoemulsification from patients with senile cataracts (72 ± 13 years) were investigated in both the hydrated and dehydrated conditions. The cataract group showed clearly the proliferated lens epithelial cells (LECs) with a monomorphic cell structure, a diameter of 12.54 ± 4.31 μm, and a height of 0.23 ± 0.04 μm, whereas the control group showed no LECs. A substantial amount of false‐positive calcification was observed caused by the deposition of remnants of dried salt solution. Cataract group showed significantly higher surface roughness (382.06 nm, p ≤ 0.001) than control group in the anterior side of ALCs, whereas cataract group showed significantly lower surface roughness (353.79 nm, p ≤ 0.001) than control group in their posterior side. Cataract group showed significantly higher Young's modulus (69.52 kPa, p ≤ 0.001) compared to the control group, regardless of the ALC side. Therefore, it is significant that this study provides a new method to examine the nanostructural characteristic and biomechanical property of human ALCs through a nanometer‐scale resolution microscopy technique. SCANNING 34: 247‐256, 2012. © 2012 Wiley Periodicals, Inc.
Lost in translation: Cultural codes are not blueprints
Authors: Aldrich Howard E. , Yang Tiantian
Published: February 2012

Entrepreneurship enjoys widespread appeal in nearly all capitalist nations, but start‐up success has proved elusive for most entrepreneurs. We explain the low likelihood of entrepreneurial success by focusing on the contrast between organizational forms in terms of cultural codes that tap into widely held perceptions versus organizational forms in terms of blueprints that sustain effective guidance for organizational activities. The dilemma facing nascent entrepreneurs during their life course is the incomplete and fragmentary nature of these opportunities for learning about start‐up practices. We conclude the article by offering suggestions for further research to discover what entrepreneurs actually do during the start‐up process. Copyright © 2012 Strategic Management Society.
Intracellular Protein Delivery and Gene Transfection by Electroporation Using a Microneedle Electrode Array
Authors: Choi Seong‐O , Kim Yeu‐Chun , Lee Jeong Woo , Park Jung‐Hwan , Prausnitz Mark R. , Allen Mark G.
Published: February 2012

The impact of many biopharmaceuticals, including protein‐ and gene‐based therapies, has been limited by the need for better methods of delivery into cells within tissues. Here, intracellular delivery of molecules and transfection with plasmid DNA by electroporation is presented using a novel microneedle electrode array designed for the targeted treatment of skin and other tissue surfaces. The microneedle array is molded out of polylactic acid. Electrodes and circuitry required for electroporation are applied to the microneedle array surface by a new metal‐transfer micromolding method. The microneedle array maintains mechanical integrity after insertion into pig cadaver skin and is able to electroporate human prostate cancer cells in vitro. Quantitative measurements show that increasing electroporation pulse voltage increases uptake efficiency of calcein and bovine serum albumin, whereas increasing pulse length has lesser effects over the range studied. Uptake of molecules by up to 50% of cells and transfection of 12% of cells with a gene for green fluorescent protein is demonstrated at high cell viability. It is concluded that the microneedle electrode array is able to electroporate cells, resulting in intracellular uptake of molecules, and has potential applications to improve intracellular delivery of proteins, DNA, and other biopharmaceuticals.
The Removal of Single Layers from Multi‐layer Graphene by Low‐Energy Electron Stimulation
Authors: Jones Jason D. , Shah Rakesh K. , Verbeck Guido F. , Perez Jose M.
Published: February 2012

The removal of single atomic layers from multi‐layer graphene using a He plasma is reported. By applying sample biases of –60 and +60 V during He plasma exposure, layer removal is found to be due to electrons instead of He ions or neutrals in the plasma. The rate of layer removal depends on exposure time, sample bias, and pre‐annealing treatments. Optical contrast microscopy and atomic force microscopy studies show that the removal of C atoms occurs approximately one layer at a time across the entire multi‐layer sample with no observable production of large pits or reduction in lateral dimensions. Layer removal is proposed to arise from the electron‐stimulated dissociation of C atoms from the basal plane. This process differs from plasma techniques that use reactive species to etch multi‐layer graphene.
Scutellaria barbata inhibits angiogenesis through downregulation of HIF‐1 α in lung tumor
Authors: Shiau Ai‐Li , Shen Yu‐Ting , Hsieh Jeng‐Long , Wu Chao‐Liang , Lee Che‐Hsin
Published: February 2012

Hypoxia, a hallmark of many solid tumors, is associated with angiogenesis and tumor progression. Hypoxia‐inducible factor‐1 (HIF‐1) plays a significant role in tumor angiogenesis. In this study, the authors constructed a selective platform to screen the traditional Chinese medicine as anti‐angiogenic agent. The authors examined the molecular mechanism by which Scutellaria barbata regulates HIF‐1‐dependent expression of vascular endothelial growth factor (VEGF), which is an important angiogenic factor. Hypoxia promotes angiogenesis by increasing VEGF expression and secretion. Herein, the expression of VEGF was decreased by treatment with S. barbata in tumor cells. Meanwhile, S. barbata reduced the migration and proliferation of endothelial cells under hypoxic condition. S. barbata inhibited the expression of HIF‐1α, as well as phosphorylated their upstream signal mediators AKT. S. barbata significantly inhibited the tumor growth in vivo and immunohistochemical studies in the tumors revealed decreased intratumoral microvessel density. These results suggest that the traditional Chinese medicine therapy using S. barbata, which exerts anti‐angiogenic activities, represents a promising strategy for the treatment of tumors. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 363–370, 2014.
Establishing the stem cell state: insights from regulatory network analysis of blood stem cell development
Authors: Schütte Judith , Moignard Victoria , Göttgens Berthold
Published: February 2012

Transcription factors (TFs) have long been recognized as powerful regulators of cell‐type identity and differentiation. As TFs function as constituents of regulatory networks, identification and functional characterization of key interactions within these wider networks will be required to understand how TFs exert their powerful biological functions. The formation of blood cells (hematopoiesis) represents a widely used model system for the study of cellular differentiation. Moreover, specific TFs or groups of TFs have been identified to control the various cell fate choices that must be made when blood stem cells differentiate into more than a dozen distinct mature blood lineages. Because of the relative ease of accessibility, the hematopoietic system represents an attractive experimental system for the development of regulatory network models. Here, we review the modeling efforts carried out to date, which have already provided new insights into the molecular control of blood cell development. We also explore potential areas of future study such as the need for new high‐throughput technologies and a focus on studying dynamic cellular systems. Many leukemias arise as the result of mutations that cause transcriptional dysregulation, thus suggesting that a better understanding of transcriptional control mechanisms in hematopoiesis is of substantial biomedical relevance. Moreover, lessons learned from regulatory network analysis in the hematopoietic system are likely to inform research on less experimentally tractable tissues. WIREs Syst Biol Med 2012. doi: 10.1002/wsbm.1163

This article is categorized under:

Biological Mechanisms > Cell Fates
Selective Computed Tomography and Angioembolization Provide Benefits in the Management of Patients with Concomitant Unstable Hemodynamics and Negative Sonography Results
Authors: Fu Chih‐Yuan , Hsieh Chi‐Hsun , Shih Chun‐Han , Wang Yu‐Chun , Chen Ray‐Jade , Huang Hung‐Chang , Huang Jui‐Chien , Wu Shih‐Chi , Tsuo Hsun‐Chung , Tung Hsiu‐Jung
Published: February 2012

Background

The FAST (focused assessment of sonography for trauma) examination can rapidly identify free fluid in the abdominal or thoracic cavity, which is indicative of hemorrhage requiring emergency surgery in multiple‐trauma patients. In patients with negative FAST examination results, it is difficult to identify the site of the hemorrhage and to plan treatment accordingly. We attempted to delineate the role of selective computed tomography (CT) and transarterial angioembolization (TAE) in the management of such unstable patients.

Methods

From January 2005 to April 2011 patients with concomitant unstable hemodynamics and negative FAST examination results were identified. Their demographic and time to start of embolization were recorded. The initial systolic blood pressure (SBP) in emergency department patients was compared with the SBP after TAE.

Results

A total of 33 patients were enrolled, and 85% required TAE. SBP improved significantly after TAE. There were 18 patients who received TAE without CT scan because the site of hemorrhage was obvious. Fifteen patients received a CT scan during the time required for angiography preparation. Ten of them received subsequent TAE based on the CT scan findings, and the treatment plan was changed in the other five patients. There was no significant difference between patients with or without a CT scan with respect to the time interval between arrival and starting embolization.

Conclusions

Transarterial angioembolization is suggested in the management of patients with concomitant unstable hemodynamics and negative FAST examination results. During the time interval required for angiography preparation, a CT scan can be performed. This approach provides valuable information for further decision making without delaying definitive treatment.
Pancreatectomy Combined with Superior Mesenteric Vein–Portal Vein Resection for Pancreatic Cancer: A Meta‐analysis
Authors: Zhou Yanming , Zhang Zhiming , Liu Yujian , Li Bin , Xu Donghui
Published: February 2012

Background

Pancreatectomy combined with superior mesenteric vein–portal vein resection (VR) for pancreatic cancer remains a matter of debate. The present study is a meta‐analysis of the available evidence.

Methods

Articles published until end of March 2011, comparing the results of pancreatic resections with VR versus without VR, were searched. Pooled odds ratios (OR) and weighted mean differences (WMD; with 95% Confidence Intervals [95% CI]) were calculated using either the fixed effects model or the random effects model.

Results

Nineteen nonrandomized studies met the inclusion criteria, comprising 2,247 patients. There was no difference in perioperative morbidity (OR: 0.95; 95% CI: 0.74–1.21; P = 0.67), mortality (OR: 1.19; 95% CI: 0.73–1.96; P = 0.48), or 5‐year overall survival (OR: 0.57; 95% CI: 0.32–1.02; P = 0.06) between patients with VR and those without VR.

Conclusions

Pancreatectomy combined with VR resection for pancreatic cancer is justified because it can result in good perioperative outcome and long‐term survival comparable to that obtained with standard resection. Owing to the selection bias and low level of clinical evidence available so far, the results should be interpreted with caution.
Peritoneal Echinococcosis: Anatomoclinical Features and Surgical Treatment
Authors: Majbar Mohammed Anass , Souadka Amine , Sabbah Farid , Raiss Mohamed , Hrora Abdelmalek , Ahallat Mohamed
Published: February 2012

Background

Peritoneal hydatid disease is a rare and poorly known disease. We report our experience with 17 patients treated for peritoneal echinococcosis. The main objectives were to analyze and discuss the specific features of the anatomic peritoneal lesions along with their surgical treatment.

Methods

We analyzed retrospectively all patients treated in our unit for peritoneal echinococcosis between January 2001 and December 2008. Preoperative description of the lesions, and the surgical procedures were carefully reported.

Results

Peritoneal hydatidosis represented 6.3% of all abdominal localizations. There were 10 women (58.8%) and 7 men (41.2%). Median age was 34 years. Ten patients (58.8%) had had previous surgery for abdominal echinococcosis. Ten patients (58.8%) had synchronous abdominal localization of hydatid disease, and two patients had synchronous pulmonary localization. Sixteen patients were operated on by laparotomy. We classified the anatomic lesions into four groups: localized form (n = 6, 37.4%), disseminated form (n = 8, 50%), “hydatid carcinomatosis” (n = 3, 18.7%), hydatidoperitoneum (n = 1, 6.25%). One patient had a ruptured hydatid cyst of the left liver. We performed total cystectomies in 10 patients, partial cystectomies in 8 patients, and omentectomy in 5 patients. Two patients (12.5%) had surgical complications. One patient (6.25%) died owing to a pulmonary embolism. Anthelmintic chemotherapy was given to two patients before surgery and to nine patients postoperatively. Recurrences were seen in two patients (14.2%).

Conclusions

Peritoneal echinococcosis can cause a large variety of specific and complex anatomic lesions. The disseminated form is the most common, and therefore the surgical treatment is challenging in most cases.
Ruderality in extreme‐desert cacti? Population effects of chronic anthropogenic disturbance on Echinocereus lindsayi
Authors: Martorell Carlos , Garcillán Pedro P. , Casillas Francisco
Published: February 2012

Ruderal species, i.e., those that increase their numbers in the presence of disturbance, are not expected to occur in extreme environments. We test whether Echinocereus lindsayi, a cactus from an extreme desert, follows the ruderal trend observed in similar species from mild deserts, or, as theory suggests, it is a non ruderal. Contrary to expectations, its density and fraction of small individuals in the population increased with disturbance. This seemingly results from increased establishment, as it is nursed by rocks exposed by disturbance. A demographic model for two populations, one nearly pristine and another highly disturbed, showed that at the latter site recruitment was more frequent and likely. At the disturbed site the performance of E. lindsayi individuals was usually poor, except on favorable years. Then, competition release caused by disturbance apparently allowed for a better performance compared to the less disturbed site. Despite that this opportunistic behavior would suffice to maintain the population size stable, the large mortality produced by an insect outbreak in two of the four study years caused the population to diminish. In contrast, the population at the less disturbed site was near equilibrium. If the insect outbreak is associated to disturbance, E. lindsayi at the disturbed site would be already experiencing more disturbance than it tolerates. This agrees with the fact that no populations were found at greater disturbance intensities. While, contrary to our hypothesis, E. lindsayi is ruderal, this extreme desert species appears to tolerate far less disturbance than its counterparts from milder areas.
Estimating Design Effect and Calculating Sample Size for Respondent-Driven Sampling Studies of Injection Drug Users in the United States
Authors: Wejnert Cyprian , Pham Huong , Krishna Nevin , Le Binh , DiNenno Elizabeth
Published: February 2012

Respondent-driven sampling (RDS) has become increasingly popular for sampling hidden populations, including injecting drug users (IDU). However, RDS data are unique and require specialized analysis techniques, many of which remain underdeveloped. RDS sample size estimation requires knowing design effect (DE), which can only be calculated post hoc. Few studies have analyzed RDS DE using real world empirical data. We analyze estimated DE from 43 samples of IDU collected using a standardized protocol. We find the previous recommendation that sample size be at least doubled, consistent with DE = 2, underestimates true DE and recommend researchers use DE = 4 as an alternate estimate when calculating sample size. A formula for calculating sample size for RDS studies among IDU is presented. Researchers faced with limited resources may wish to accept slightly higher standard errors to keep sample size requirements low. Our results highlight dangers of ignoring sampling design in analysis.
Rewiring translation – Genetic code expansion and its applications
Authors: Neumann Heinz
Published: February 2012

With few minor variations, the genetic code is universal to all forms of life on our planet. It is difficult to imagine that one day organisms might exist that use an entirely different code to translate the information of their genome. Recent developments in the field of synthetic biology, however, have opened the gate to their creation. The genetic code of several organisms has been expanded by the heterologous expression of evolved aminoacyl‐tRNA synthetase/tRNACUA pairs that mediate the incorporation of unnatural amino acids in response to amber codons. These UAAs introduce exciting new features into proteins, such as spectroscopic probes, UV‐inducible crosslinkers, and functional groups for bioorthogonal conjugations or posttranslational modifications. Orthogonal ribosomes provide a parallel translational machinery in Escherichia coli that has lost its evolutionary constraints. Evolved variants of these ribosomes translate amber or quadruplet codons with massively enhanced efficiency. Here, I review these recent developments emphasizing their tremendous potential to facilitate biochemical and cell biological studies.
Diffusion patterns of anesthetic solution in the infiltration anesthesia depending on injection sites in the mandible of rats
Authors: Yamada Hiroyuki , Sato Tetsuji , Fukayama Haruhisa
Published: February 2012

Purpose: This study was conducted for the morphological and quantitative evaluation of the diffusible patterns of local anesthetic depending on the site of injection in infiltration anesthesia.

Experiments: The mandibular first molars of rats were anesthetized by the local infiltration of 30 μl of 2% lidocaine containing trypan blue at a distance of 2 mm from the gingival margin on either the lingual or buccal side over the distal root apex of the first molar. Frozen sections were prepared to measure the volume of the infiltrated anesthetic using volume‐calculating software.

Results: On the lingual side, the local anesthetic infiltrated into the mouth floor and spread backward in a sagittal direction at an infiltration volume of 8.36 ± 7.34 mm3. On the buccal side, the anesthetic solution was restricted to the injected area and the infiltration volume was 2.22 ± 1.62 mm3.

Conclusion The present results indicate that the infiltration volume of local anesthetics is very different between the lingual and buccal sides.
Still Looking for Liberation? Lutherans in El Salvador and Nicaragua
Authors: CHAPMAN RICHARD M.
Published: February 2012

Liberationist Christianity in Central America has faced considerable challenges adjusting to changing circumstances since 1990. Yet the political concerns and economic conditions that animated religious movements for liberation in the region have not disappeared, nor have adherents of progressive religion. Central American Lutherans embody a distinctive dialogue with liberationist religion, one not adequately treated or understood in existing studies focused on religious change and the state. In El Salvador and Nicaragua, Lutherans adapted perspectives from liberation theology through the resources of their own theological inheritance, but both this heritage and they themselves were equally shaped and transformed by their efforts to counter, survive and redeem the inhumanity and political violence of the societies they inhabited. The Lutheran story is an important addition to the current understanding of the diverse ways in which religious communities interacted with theologies and movements of liberation, and engaged with processes of social change in the Central American context.
Resistive wall mode in cylindrical plasmas in the presence of surface currents
Authors: CUI SHAOYAN , LU GAIMIN , LIU YUE
Published: February 2012

Stability of the resistive wall mode in cylindrical plasmas confined by surface currents is investigated for the δ-function and step-function equilibrium surface-current profiles. For the former, it is shown that the perturbations oscillate and even decay for all locations of the initial perturbation. The entire system is stable and the plasma flow has little effect. For the step-function surface-current distribution, it is found that the thicker the surface current layer, the more stable is the system even if the largest initial perturbation is located on the rational surface, but the plasma flow also has little effect on the system.
Invariant measures with bounded variation densities for piecewise area preserving maps
Authors: ZHANG YIWEI , LIN CONGPING
Published: February 2012

We investigate the properties of absolutely continuous invariant probability measures (ACIPs), especially those measures with bounded variation densities, for piecewise area preserving maps (PAPs) on ℝd. This class of maps unifies piecewise isometries (PWIs) and piecewise hyperbolic maps where Lebesgue measure is locally preserved. Using a functional analytic approach, we first explore the relationship between topological transitivity and uniqueness of ACIPs, and then give an approach to construct invariant measures with bounded variation densities for PWIs. Our results ‘partially’ answer one of the fundamental questions posed in [13]—to determine all invariant non-atomic probability Borel measures in piecewise rotations. When restricting PAPs to interval exchange transformations (IETs), our results imply that for non-uniquely ergodic IETs with two or more ACIPs, these ACIPs have very irregular densities, i.e. they have unbounded variation.
Cultural Heritage Law Committee of the International Law Association: Special Session, Kohunlich, Mexico, 26–29 October 2011
Authors: Cordero Jorge Sánchez
Published: February 2012

In October 2011 the Cultural Heritage Law Committee of the International Law Association, under the chairmanship of Professor James Nafziger, met in Kohunlich, Quintana Roo, Mexico. The purpose of the meeting was to fuse culture with working sessions over a period of four days. The meeting took place amid fascinating Mayan ruins and the Kalakmul biosphere reserve near the Belizean border. It proved to be a great and successful venture.