bluuebunny/crossref_metadata_2025 huggingface dataset:
Acquisition of MDR phenotype by leukemic cells is associated with increased caspase‐3 activity and a collateral sensitivity to cold stress
Authors: Cerezo David , Lencina Miriam , Ruiz‐Alcaraz Antonio J. , Ferragut José Antonio , Saceda Miguel , Sanchez Manuel , Cánovas Manuel , García‐Peñarrubia Pilar , Martín‐Orozco Elena
Published: December 2011

The acquisition of a multidrug‐resistant (MDR) phenotype by tumor cells that renders them unsusceptible to anti‐neoplasic agents is one of the main causes of chemotherapy failure in human malignancies. The increased expression of P‐glycoprotein (MDR1, P‐gp, ABCB1) in tumor cells contributes to drug resistance by extruding chemotherapeutic agents or by regulating programmed cell death. In a study of MDR cell survival under cold stress conditions, it was found that resistant leukemic cells with P‐gp over‐expression, but not their sensitive counterparts, are hypersensitive to cold‐induced cell death when exposed to temperatures below 4°C. The transfection of parental cells with a P‐gp‐expressing plasmid makes these cells sensitive to cold stress, demonstrating an association between P‐gp expression and cell death at low temperatures. Furthermore, we observed increased basal expression and activity of effector caspase‐3 at physiological temperature (37°C) in MDR cells compared with their parental cell line. Treatment with a caspase‐3 inhibitor partially rescues MDR leukemic cells from cold‐induced apoptosis, which suggests that the cell death mechanism may require caspase‐3 activity. Taken together, these findings demonstrate that P‐gp expression plays a role in MDR cell survival, and is accompanied by a collateral sensitivity to death induced by cold stress. These findings may assist in the design of specific therapeutic strategies to complement current chemotherapy treatment against cancer. J. Cell. Biochem. 113: 1416–1425, 2012. © 2011 Wiley Periodicals, Inc.
Continuously generated H2O2stimulates the proliferation and osteoblastic differentiation of human periodontal ligament fibroblasts
Authors: Choe Youngji , Yu Ji‐Yeon , Son Young‐Ok , Park Seung‐Moon , Kim Jong‐Ghee , Shi Xianglin , Lee Jeong‐Chae
Published: December 2011

Numerous studies have shown that hydrogen peroxide (H2O2) inhibits proliferation and osteoblastic differentiation in bone‐like cells. Human periodontal ligament fibroblasts (PLF) are capable of differentiating into osteoblasts and are exposed to oxidative stress during periodontal inflammation. However, the cellular responses of PLF to H2O2have not been identified. In this study, we examined how H2O2affects the viability and proliferation of PLF by exposing the cells to glucose oxidase (GO) or direct addition of H2O2. We also explored the effects of GO on the osteoblastic differentiation of PLF and the mechanisms involved. The viability and proliferation in PLF were increased with the addition of 10 mU/ml GO but not by volumes greater than 15 mU/ml or by H2O2itself. GO‐stimulated DNA synthesis was correlated with the increase in cyclin E protein levels in the cells. Osteoblastic differentiation of PLF was also augmented by combined treatment with GO, as evidenced by the increases in alkaline phosphatase activity, mineralization, collagen synthesis, and osteocalcin content in the cells. The inductions of runt‐related transcription factor 2 and osterix mRNA and proteins were further increased in PLF incubated in combination with GO compared to those in untreated cells. These results demonstrate that the continuous presence of H2O2stimulates the proliferation of PLF and augments their potential to differentiate into osteoblasts through the up‐regulation of bone‐specific transcription factors. Collectively, we suggest that H2O2may elicit the functions of PLF in maintaining the dimensions of the periodontal ligament and in mediating a balanced metabolism in alveolar bone. J. Cell. Biochem. 113: 1426–1436, 2012. © 2011 Wiley Periodicals, Inc.
Small molecule induction of neural‐like cells from bone marrow‐mesenchymal stem cells
Authors: Wang Ye , He Wenfeng , Bian Hetao , Liu Chuan , Li Shiyong
Published: December 2011

Bone marrow‐derived mesenchymal stem cells (MSCs) have been demonstrated to be able to differentiate into neuron‐like cell, but the precise mechanisms controlling this process are unclear. We report here that LY294002, a small molecule inhibitor of PI3K/AKT signal pathway, can inhibit proliferation and promote neuronal differentiation of MSCs after MSCs incubated with LY294002 for 6 and 12 h. RT‐PCR results indicated that mRNA expression of α5β1 integrin significantly increased in neuron‐like cell from MSCs. Interestingly, neuron‐like cells derived by this method adhere much more strongly than MSCs, which was related to the expression of α5β1 integrin and FAK phosphorylation. However, these effects could be attenuated by LiCL or GSK‐3β–siRNA. Our results indicate that activation GSK‐3β signaling may be involved in MSCs proliferation, differentiation, and adhesion. Furthermore, this study demonstrates that small molecule regulators of PI3K/AKT signaling may be valuable tools for stem cell research aimed at treatment of neurodegenerative disease. J. Cell. Biochem. 113: 1527–1536, 2012. © 2011 Wiley Periodicals, Inc.
Hyperthermia‐enhanced TRAIL‐ and mapatumumab‐induced apoptotic death is mediated through mitochondria in human colon cancer cells
Authors: Song Xinxin , Kim Han‐Cheon , Kim Seog‐Young , Basse Per , Park Bae‐Hang , Lee Byeong‐Chel , Lee Yong J.
Published: December 2011

Colorectal cancer is the third leading cause of cancer‐related mortality in the world; death usually results from uncontrolled metastatic disease. Previously, we developed a novel strategy of TNF‐related apoptosis‐inducing ligand (Apo2L/TRAIL) in combination with hyperthermia to treat hepatic colorectal metastases. However, previous studies suggest a potential hepatocyte cytotoxicity with TRAIL. Unlike TRAIL, anti‐human TRAIL receptor antibody induces apoptosis without hepatocyte toxicity. In this study, we evaluated the anti‐tumor efficacy of humanized anti‐death receptor 4 (DR4) antibody mapatumumab (Mapa) by comparing it with TRAIL in combination with hyperthermia. TRAIL, which binds to both DR4 and death receptor 5 (DR5), was approximately tenfold more effective than Mapa in inducing apoptosis. However, hyperthermia enhances apoptosis induced by either agent. We observed that the synergistic effect was mediated through elevation of reactive oxygen species, c‐Jun N‐terminal kinase activation, Bax oligomerization, and translocalization to the mitochondria, loss of mitochondrial membrane potential, release of cytochrome c to cytosol, activation of caspases, and increase in poly(ADP‐ribose) polymerase cleavage. We believe that the successful outcome of this study will support the application of Mapa in combination with hyperthermia to colorectal hepatic metastases. J. Cell. Biochem. 113: 1547–1558, 2012. © 2011 Wiley Periodicals, Inc.
Macrophage migration inhibitory factor increases cell motility and up‐regulates αvβ3 integrin in human chondrosarcoma cells
Authors: Lee Chun‐Yi , Su Mei‐Ju , Huang Chun‐Yin , Chen Meng‐Yi , Hsu Horng‐Chaung , Lin Ching‐Yuang , Tang Chih‐Hsin
Published: December 2011

The macrophage migration‐inhibitory factor (MIF) is a pro‐inflammatory cytokine first known for its effect on macrophage migration and activation. Recent studies have shown that MIP plays a critical role in tumor growth, angiogenesis, and metastasis. Chondrosarcoma is a type of highly malignant tumor with a potent capacity to invade locally and cause distant metastasis. However, the effects of MIF on human chondrosarcoma cells are largely unknown. In the present study, MIF was found to increase the migration and the expression of αvβ3 integrin in human chondrosarcoma cells. The phosphatidylinositol 3‐kinase (PI3K), Akt, and NF‐κB pathways were activated by MIF treatment, and the MIF‐induced expression of integrin and migration activity were inhibited by the specific inhibitors and mutant forms of PI3K, Akt, and NF‐κB cascades. In addition, migration‐prone sublines demonstrated that increased cell migration ability was correlated with increased expression of MIF and αvβ3 integrin. Taken together, our results indicate that MIF enhanced the migration of the chondrosarcoma cells by increasing αvβ3 integrin expression through the PI3K/Akt/NF‐κB signal transduction pathway. J. Cell. Biochem. 113: 1590–1598, 2012. © 2011 Wiley Periodicals, Inc.
Effect of phorbol 12‐myristate 13‐acetate activated signaling pathways on 1α, 25 dihydroxyvitamin D3 Regulated Human 25‐hydroxyvitamin D3 24‐hydroxylase Gene Expression in Differentiated Caco‐2 Cells
Authors: Jiang Yan , Fleet James C.
Published: December 2011

Phorbol‐12‐myristate‐13‐acetate (PMA), a protein kinase C (PKC) activator, can modulate 1α, 25 dihydroxyvitamin D3 (1,25(OH)2D3)‐induced expression of the 24‐hydroxylase (CYP24A1) gene but this has not been studied in differentiated enterocytes, a primary 1,25(OH)2D3 target cell. We found that in differentiated Caco‐2 cells, an established model of the mature absorptive epithelial cell, PMA significantly enhanced 1,25(OH)2D3‐induced human CYP24A1 (hCYP24A1) mRNA accumulation and hCYP24A1 promoter‐luciferase reporter gene activation by 150%. Reporter gene studies further identified the region between −298 and +74 bp in the hCYP24A1 promoter as critical for the PMA enhancing effect and chromatin immunoprecipitation (ChIP) analysis showed that PMA enhanced 1,25(OH)2D3‐induced binding of vitamin D receptor to this region. PMA can activate PKC, ERK1/2, and p38 MAP kinases and inhibition of these signaling pathways reduced both 1,25(OH)2D3‐induced hCYP24A1 gene transcription and the enhancing effect of PMA. The PMA enhancing effect on 1,25(OH)2D3 action was evident in a minimal promoter with three osteocalcin VDREs and was reduced after mutation of a putative vitamin D stimulatory site in the hCYP24A1 promoter. In contrast, mutation of a Ets binding site (EBS) in the hCYP24A1 promoter had no impact on 1,25(OH)2D3 action or the PMA enhancing effect. These data suggest that in the differentiated enterocyte PMA‐induced activation of several signaling pathways contribute to 1,25(OH)2D3‐induced hCYP24A1 gene expression through multiple regulatory motifs within the proximal hCYP24A1 promoter. J. Cell. Biochem. 113: 1599–1607, 2012. © 2011 Wiley Periodicals, Inc.
Nonmedical factors associated with prolonged hospital length of stay in an urban homebound population
Authors: Foer Dinah , Ornstein Katherine , Soriano Theresa A. , Kathuria Navneet , Dunn Andrew
Published: December 2011

BACKGROUND:

Prolonged length of stay (LOS) is a major concern for hospitalized populations at risk for adverse events. Homebound patients are at particular risk for long stays and may have unique discharge needs because of their commitment to be cared for at home despite poor functional status.

OBJECTIVE:

The goal of this study was to describe factors contributing to long hospitalizations in the homebound population.

DESIGN:

This retrospective observational pilot study included all 2007 discharges that occurred for patients at The Mount Sinai Hospital enrolled in the Mount Sinai Visiting Doctors Program.

MEASURES:

Long‐stay patients were defined as those having an LOS 2 standard deviations above the mean. Hospitalization days were defined as “nonmedical” when patients medically ready for discharge remained in the hospital. Patients discharged immediately after determination of medical readiness were characterized as “medical stay” cases. The University HealthSystems Consortium Database was used to calculate expected LOS and the LOS ratio. Chart reviews were performed to describe long‐stay cases as nonmedical or medical.

RESULTS:

The average LOS for 479 discharges was 7.84 days, with a mean LOS Ratio of 1.23. Seventeen cases were determined to be long stays. Eight of these cases (47%) were defined as nonmedical stays. These accounted for 136 days of hospitalization and 32% of total long‐stay days. The most common reason for a nonmedical stay was nursing facility placement delay.

CONCLUSIONS:

Nonmedical factors accounted for nearly one‐third of all long‐stay days in the hospitalized homebound population. Increased interdisciplinary collaboration may help address homebound patient LOS. Journal of Hospital Medicine 2012; © 2012 Society of Hospital Medicine.
Predictive value of MRI in the localization, staging, volume estimation, assessment of aggressiveness, and guidance of radiotherapy and biopsies in prostate cancer
Authors: Yakar Derya , Debats Oscar A. , Bomers Joyce G.R. , Schouten Martijn G. , Vos Pieter C. , van Lin Emile , Fütterer Jurgen J. , Barentsz Jelle O.
Published: December 2011

Multiparametric magnetic resonance imaging (MRI) has the potential of being the ideal prostate cancer (PCa) assessment tool. Information gathered with multiparametric MRI can serve therapy choice, guidance of interventions, and treatments. The purpose of this review is to discuss the potential role of multiparametric MRI in focal therapy with respect to patient selection and directing (robot‐guided) biopsies and intensity‐modulated radiation therapy (IMRT). Multiparametric MRI is a versatile and promising technique. It appears to be the best available imaging technique at the moment in localizing, staging (primary as well as recurrent disease, and local as well as distant disease), determining aggressiveness, and volume of PCa. However, larger study populations in multicenter settings have to confirm these promising results. However, before such studies can be performed more research is needed in order to achieve standardized imaging protocols. J. Magn. Reson. Imaging 2012;35:20‐31. © 2011 Wiley Periodicals, Inc.
Non‐contrast enhanced MR angiography: Established techniques
Authors: Miyazaki Mitsue , Akahane Masaaki
Published: December 2011

Until recently, time‐of‐flight (TOF) and phase contrast (PC) were the only non‐contrast MR angiography (NC‐MRA) techniques practically used in clinical. In the decade, NC‐MRA have been gained a revival of an interest among the MR researchers and scientists, in part because of safety concerns related to the possible link between gadolinium‐based contrast agents and nephrogenic systemic fibrosis (NSF). This article introduces other established NC‐MRA techniques, such as ECG‐gated partial Fourier fast spin echo (FSE) and balanced steady‐state free precession (bSSFP), both with and without arterial spin labeling. Then, the article focuses on two main applications: peripheral run‐off and renal MRA. Recently, both applications have achieved remarkable advancements and have become a viable clinical option as an alternative to contrast‐enhanced (CE)‐MRA. In addition, developments on the horizon including whole body MRA applications and further advancement at 3 Tesla are discussed. J. Magn. Reson. Imaging 2012 © 2011 Wiley Periodicals, Inc.
Recent advances in linear and nonlinear Raman spectroscopy. Part V
Authors: Nafie Laurence A.
Published: December 2011

The purpose of the review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in JRS as well as in trends across all related journals publishing in this research area. Context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the meetings of the Federation of Analytical Chemistry and Spectroscopy Societies 2011 and the Sixth International Conference on Advanced Vibrational Spectroscopy 2011. Papers published in JRS in 2010, as reviewed here, reflect trends at the cutting edge of Raman spectroscopy, which is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever‐widening sphere of novel applications. Copyright © 2011 John Wiley & Sons, Ltd.
Pooling health‐related quality of life outcomes in meta‐analysis—a tutorial and review of methods for enhancing interpretability
Authors: Thorlund Kristian , Walter Stephen D. , Johnston Bradley C. , Furukawa Toshi A. , Guyatt Gordon H.
Published: December 2011

Background

– Meta‐analyses of health‐related quality of life (HRQL) outcomes present difficulties in interpretation when studies use different instruments to measure the same construct. Presentation of results in standard deviation units (standardized mean difference) is widely used but is limited by vulnerability to differential variability in populations enrolled and interpretational challenges.

Objective

– The objective of this study is to identify and describe the available approaches for enhancing interpretability of meta‐analyses involving HRQL outcomes.

Findings

– We identified 12 approaches in three categories:

Summary estimates derived from the pooled standardized mean difference: conversion to units of the most familiar instrument or to risk difference or odds ratio. These approaches remain vulnerable to differential variability in populations.

Summary estimates derived from the individual trial summary statistics: conversion to units of the most familiar instrument or to ratio of means. Both are appropriate complementary approaches to measures derived from converted probabilities.

Summary estimates derived from the individual trial summary statistics and established minimally important differences for all instruments: presentation in minimally important difference units or conversion to risk difference or odds ratio. Risk differences are ideal for balancing desirable and undesirable consequences of alternative interventions.

Conclusion

– The use of these approaches may enhance the interpretability and the usefulness of systematic reviews involving HRQL outcomes. Copyright © 2011 John Wiley & Sons, Ltd.
Boundedness of solutions of retarded functional differential equations with variable impulses via generalized ordinary differential equations
Authors: Afonso S. M. , Bonotto E. M. , Federson M. , Gimenes L. P.
Published: December 2011

In this paper, we give sufficient conditions for the uniform boundedness and uniform ultimate boundedness of solutions of a class of retarded functional differential equations with impulse effects acting on variable times. We employ the theory of generalized ordinary differential equations to obtain our results. As an example, we investigate the boundedness of the solution of a circulating fuel nuclear reactor model.
Synthesis of High Molecular Weight Polyesters via In Vacuo Dehydrogenation Polymerization of Diols
Authors: Hunsicker David M. , Dauphinais Brian C. , Mc Ilrath Sean P. , Robertson Nicholas J.
Published: December 2011

The Milstein catalyst has proven to be highly effective for the conversion of alcohols to esters, as well as alcohols and amines to amides and polyamides. We have recently found that the catalyst's range can be extended to very efficient in vacuo dehydrogenation polymerization of α,ω‐diols to generate polyesters. The gaseous hydrogen byproduct that is produced is easily removed to drive the equilibrium toward product, which leads to the formation of high molecular weight polymer ( up to 145 000 g mol−1). This optimized methodology works well to polymerize diols with a spacer of six carbons or more. Diols with fewer carbons are cyclized to lactone; the dividing point is the dehydrogenation of 1,5‐pentanediol, which leads to a mixture of polyester and lactone. Reported herein is the synthesis and characterization of five aliphatic polyesters prepared via this novel dehydrogenation polymerization approach.
Model to Design Multilayer Tissue Engineering Scaffolds
Authors: Papenburg Bernke J. , Higuera Gustavo A. , de Vries Ida‐Jacoba , de Boer Jan , van Blitterswijk Clemens A. , Wessling Matthias , Stamatialis Dimitrios
Published: December 2011

In tissue engineering scaffolds, nutrient transport to cells is a major hurdle for building viable 3D tissue scaffolds.In vivo, a complex network of blood vessels and capillaries delivers nutrients and oxygen to the tissue. Forin vitrobuild constructs the distance to the main nutrient source is often long resulting in nutrient gradients over the scaffold and decreased cell proliferation or even cell death in parts of the scaffold. This work describes a numerical model for designing a multilayer scaffold for tissue engineering by stacking sheets featuring microchannels. These sheets fabricated by phase separation micromolding (PSµM) allow nutrient perfusion through the 3D scaffold whereas inner‐porosity of the sheets guarantees diffusion between layers. The model predicts significant nutrient limitation occurs under static conditions for scaffolds having over 3 sheets. The situation can improve dramatically under dynamic conditions when perfusion occurs through the microchannels.
Injectable Hydrogels by Enzymatic Co‐Crosslinking of Dextran and Hyaluronic Acid Tyramine Conjugates
Authors: Wennink Jos W.H. , Niederer Kerstin , Bochyńska Agnieszka I. , Moreira Teixeira Liliana S. , Karperien Marcel , Feijen Jan , Dijkstra Pieter J.
Published: December 2011

In this study, injectable hydrogels were prepared by the horseradish peroxidase mediated co‐crosslinking of dextran‐tyramine (Dex‐TA) and hyaluronic acid‐tyramine (HA‐TA) conjugates intended for cartilage tissue engineering. In general the gelation times of 10 wt% polysaccharide solutions are < 20 seconds and their storage moduli can be adjusted by varying the composition between Dex‐TA and HA‐TA. Dex‐TA/HA‐TA (50/50) hydrogels were fully degradable in the presence of hyaluronidase. Chondrocytes incorporated in 10 wt% Dex‐TA and Dex‐TA/HA‐TA (50/50) gels showed good viability after 28 days. These results indicate that Dex‐TA/HA‐TA (50/50) hydrogels are promising injectable and biodegradable hydrogels for cartilage repair.
Thermo‐Reversible Reactions for the Preparation of Smart Materials: Recyclable Covalently‐Crosslinked Shape Memory Polymers
Authors: Defize Thomas , Riva Raphaël , Thomassin Jean‐Michel , Jérôme Christine , Alexandre Michaël
Published: December 2011

[4+2] thermoreversible Diels‐Alder cycloaddition has been used to crosslink star‐shaped poly(ε‐caprolactone) in order to produce networks based on strong carbon‐carbon covalent bondings. Depending on the nature of the Diels‐Alder reactants, these bonds can be thermoreversibly broken, allowing re‐processing of the polymer matrix.
The Influence of Programming Conditions on the Triple‐Shape Effect of Copolymer Networks with Poly(ω‐pentadecalactone) and Poly(ε‐caprolactone) as Switching Segments
Authors: Zotzmann Jörg , Behl Marc , Lendlein Andreas
Published: December 2011

A versatile triple‐shape material based on the two crystallizable segments poly(ω–pentadecalactone) and poly(ε‐caprolactone) was synthesized showing triple‐shape capability after application of the typical two‐step triple‐shape creation procedure at elevated temperatures (TSCP) as well as a one‐step programming procedure at high temperature or at room temperature by cold drawing. By applying TSCP and varying the sequence of programming temperatures, the influence of the programming procedure on the triple‐shape capability was investigated. The application of such a modified TSCP enabled to a certain extent the control of triple‐shape capability by influencing the crystallization behavior of the two switching segments in these copolymer networks.
Comparative Study of Collagen and Gelatin Coatings on Titanium Surfaces
Authors: Vanderleyden Els , Van Hoorebeke Luc , Schacht Etienne , Dubruel Peter
Published: December 2011

The vast majority of studies in the bone tissue engineering field are focused on the surface modification of titanium scaffolds to obtain integration of the scaffold in the surrounding bone tissue. Our approach consisted in benefiting from the advantages of the cell‐interaction capabilities of collagen and gelatin. The biopolymers were immobilised onto the Ti surface through different methods and the stability of the obtained coatings was determined. The obtained results reveal that covalent immobilisation of collagen and gelatin is required to obtain stable surface coatings.
Fluorophore‐Labeled Siloxane‐Based Nanoparticles for Biomedical Applications
Authors: Koshkina Olga , Bantz Christoph , Würth Christian , Lang Thomas , Resch‐Genger Ute , Maskos Michael
Published: December 2011

We present the synthesis and characterization of multifunctional fluorophore‐labeled poly(organosiloxane) nanoparticles with core‐shell architecture, where the fluorescent dye is incorporated into the core. Grafting of heterobifunctional poly(ethylene oxide) (PEO) onto the particle surface leads to water‐soluble biocompatible nanoparticles. Two different strategies have been used for the synthesis: The encapsulation of dye‐labeled monomers during the polycondensation with additional PEO coating and subsequent dye labeling by covalent attachment of the fluorescent dye rhodamine B to the (chloromethylphenyl)siloxane groups in the core after polymerization and grafting of PEO onto the surface. Comparison of the fluorescence quantum yields of the nanoparticles before and after PEO coating show a decrease in quantum yield after PEO coating.
Degradation Behavior of Porous Copolyester Microparticles in the Light of Dynamic Changes in Their Morphology
Authors: Mathew Simi , Lendlein Andreas , Wischke Christian
Published: December 2011

The pore structures of microparticulate drug carriers are important diffusion pathways, which are not a static property but rather may be changing in the case of degradable matrix polymers such as poly[(rac‐lactide)‐co‐glycolide] (PLGA). In this study, the mutual impacts of dynamic changes in microparticle porosity and polymer degradation were analyzed for PLGA with different molecular weights and end groups as well as PLGA‐based triblock copolymers. In selected cases, particularly for PLGA with hydrophilic end groups and low initial number average molecular weight of 5 kDa, pore opening/pore closing phenomena were detected during incubation in phosphate buffer at 37 °C. Initially, pore closing was induced by water‐induced plasticization and the reduction of interfacial tension. The pattern of molecular weight decrease and mass loss suggested that pore closing did not result in undesired autocatalytic acceleration of degradation or delayed mass loss due to trapped acidic degradation products.
Shape Memory RGD‐Containing Networks: Synthesis, Characterization, and Application in Cell Culture
Authors: Xu Xiuling , Davis Kevin A. , Yang Pine , Gu Xinzhu , Henderson James H. , Mather Patrick T.
Published: December 2011

Hydrogels have found wide application in tissue engineering and cell mechanobiology research due to their tunable, and often biomimetic, biochemical and biomechanical properties. Although it has been known for more than a decade that hydrogels can be designed to exhibit shape memory functionality—the ability to change from one defined shape to another when triggered by a defined stimulus—shape memory hydrogels have not previously been exploited in tissue engineering or mechanobiology research. Here we report the development of a biodegradable and biocompatible hydrogel with tailored shape memory as well as desirable mechanical property for soft‐tissue applications. A shape memory hydrogel was synthesized by photopolymerization of PCL3k diacry‐lates together with acrylate‐PEG2k‐GRGDS in the presence of a crosslinker, tetrathiol, and photoinitiator, DMPA, through thiol‐ene chemistry. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were carried out to examine the thermal, mechanical and shape memory properties of the hydrogel in dry and wet states. Cell culture studies were performed to characterize material cytocompatibility. We found that the PCL phase was crystalline in the hydrogel, providing an excellent, reproducible shape memory effect. The transition temperature (shape memory “trigger”) was tuned to fall between room and body temperature. Both cell attachment and proliferation studies revealed that the presentation of GRGDS molecules in the hydrogel facilitated fibroblasts adhesion and spreading on the hydrogel surface. This hydrogel, tailored to exhibit shape memory behavior in the cell culture compatible temperature range, should provide new opportunities for “smart” shape‐changing scaffolds and substrates for application in tissue engineering and investigation of cell mechanobiology.
Comparison of office‐based versus home web‐based clinical assessments for Parkinson's disease
Authors: Cubo Esther , Trejo Gabriel‐Galán José M. , Seco Martínez Joaquin , Rioja Alcubilla Carlos , Yang Chengwu , Fernández Arconada Olga , Mariscal Pérez Natividad
Published: December 2011

Background:

The feasibility and validity of Web‐based assessments in Parkinson's disease is unknown. The objectives of this study were to develop and to compare home Web‐based assessments with office‐based assessments.

Methods: We tested feasibility and validity using a longitudinal, randomized crossover design. Patients were assessed at baseline and after 6 and 12 weeks using both assessments including the Unified Parkinson's Disease Rating Scale, the Unified Dyskinesia Rating scale, timed tests, and quality‐of life and Non‐Motor Symptoms questionnaires.

Results:

Forty‐two patients were included (22 men, 20 women; mean age, 64.7 ± 9.0 years). Only 2 patients (5%) dropped out. The mean intraclass correlation coefficient between Web‐ and office‐based assessments ranged from 0.67 (first visit) to 0.75 (last visit) and 0.81 and 0.82 for doctor‐ and patient‐administered scales, respectively. No differences in responsiveness (P = 0.63), and data precision (P = 0.11) were found, but Web‐based assessments had fewer missing values (P = 0.01).

Conclusions:

Web‐based assessments offer a feasible format for assessing PD‐related impairment from home. © 2011 Movement Disorder Society
Glucocerebrosidase mutations confer a greater risk of dementia during Parkinson's disease course
Authors: Setó‐Salvia Núria , Pagonabarraga Javier , Houlden Henry , Pascual‐Sedano Berta , Dols‐Icardo Oriol , Tucci Arianna , Paisán‐Ruiz Coro , Campolongo Antonia , Antón‐Aguirre Sofía , Martín Inés , Muñoz Laia , Bufill Enric , Vilageliu Lluïsa , Grinberg Daniel , Cozar Mónica , Blesa Rafael , Lleó Alberto , Hardy John , Kulisevsky Jaime , Clarimón Jordi
Published: December 2011

Mutations in the glucocerebrosidase gene are associated with Parkinson's disease and Lewy body dementia. However, whether these alterations have any effect on the clinical course of Parkinson's disease is not clear. The glucocerebrosidase coding region was fully sequenced in 225 Parkinson's disease patients, 17 pathologically confirmed Lewy body dementia patients, and 186 controls from Spain. Twenty‐two Parkinson's disease patients (9.8%) and 2 Lewy body dementia patients (11.8%) carried mutations in the glucocerebrosidase gene, compared with only 1 control (0.5%); P = .016 and P = .021 for Parkinson's disease and Lewy body dementia, respectively. The N370S and the L444P mutations represented 50% of the alterations. Two novel variants, L144V and S488T, and 7 previously described alterations were also found. Alterations in glucocerebrosidase were associated with a significant risk of dementia during the clinical course of Parkinson's disease (age at onset, years of evolution, and sex‐adjusted odds ratio, 5.8; P = .001). Mutation carriers did not show worse motor symptoms, had good response to L‐dopa, and tended to present the intermediate parkinsonian phenotype. Our findings suggest that mutations in the glucocerebrosidase gene not only increase the risk of both Parkinson's disease and Lewy body dementia but also strongly influence the course of Parkinson's disease with respect to the appearance of dementia. © 2011 Movement Disorder Society
An efficient second‐order model reduction enhanced by H‐LU for the finite element method full‐wave electromagnetic simulations
Authors: Li Mengmeng , Chen Rushan , Wan Ting , Feng Kun
Published: December 2011

A hierarchical LU(H‐LU) decomposition‐based direct method enhanced second‐order Krylov subspace projection‐based model order reduction (MOR) is presented. The construction of the projection matrix is the most important process in the Krylov subspace projection‐based MOR, where an inverse of the sparse matrix is involved in the construction of the projection matrix. It will be intractable for the computational capacity of a personal computer when the size of the problem is large. A H‐LU decomposition‐based direct method is used to the MOR with almost linear complexity. Numerical results demonstrate the validity of the proposed algorithm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:292–296, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26526
Lithium niobate photonic sensor for measurement of pulsed electric field with nanosecond risetime
Authors: Chen Kaixin , Sun Bao , Chen Fushen , Hu Zhefeng , Cao Yongsheng
Published: December 2011

Lithium niobate‐based photonic sensor with Mach–Zehnder optical waveguide interferometer and tapered antenna array was designed and fabricated for measuring pulsed electric field with nanosecond risetime. The fabricated photonic sensor exhibits relatively flat frequency response with a variation not more than 4 dBm from 10 kHz to 5 GHz and minimum detectable electric field intensity of 0.4 V/m. A 103 V/m pulsed electric field with nanosecond risetime was also measured by this photonic sensor, the experimental results exhibit the information of electromagnetic pulse can be detected and extracted by this photonic sensor. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:421–423, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26531
Asymmetric‐arm printed dipole antenna for wlan applications
Authors: Wang Yang‐Jing , Lei Zhen‐Ya , Zhang Na , Cai De‐Shui , Wang Ya‐Fang
Published: December 2011

A novel printed dipole antenna for wireless local area networks (WLAN) applications is presented in this article.The proposed antenna, characterized by dual‐band, low cross‐polarization, and small‐size, consists of two asymmetric tapered arms. A novel feed scheme is employed to realize a balanced feed. For validation, the antenna prototype is fabricated and measured. The performance of the antenna is verified and characterized in terms of return loss, radiation pattern, and gain. The simulated and measured results show good agreement. Details of the proposed antenna design and tested results are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:354–358, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26534
Dual‐band bandpass filter using novel side‐stub‐loaded resonator
Authors: Wu Xiao‐Hu , Chu Qing‐Xin , Tian Xu‐Kun
Published: December 2011

In this letter, a microstrip dual‐band bandpass filter (BPF) using novel side‐stub‐loaded resonator has been presented.By loading two open stubs at the symmetrical sides of a uniform‐impedance resonator, the center frequency of the fundamental odd mode could be independently controlled while that of the fundamental even mode is fixed. A dual‐band filter using pseudo‐interdigital configuration is implemented with three transmission zeros. To validate the design and analysis, a dual‐band BPF has been designed and fabricated with its two bands located at 2.4/5.2 GHz. It is shown that the measured and simulated performances are in good agreement. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:362–364 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26537
Application of lensed fiber collimator to miniature CWDM filter device
Authors: Lin Yu‐Cheng
Published: December 2011

Because of the miniature trend in most fiber optic device, we propose and experimentally verify a coarse wavelength division multiplexing (CWDM) device with lensed fiber collimators. Our key idea is to use a tiny gradient index fiber lensed fiber less than the dimension of ø0.14 × L0.5 mm to replace the traditional gradient index lens collimator ø3.2 × L11 mm. The insertion loss of a pair of 0.27 pitch lensed fiber collimator is measured in both axial and lateral direction. Then, the thin film filter is sandwiched with the lensed fiber collimators to work as CWDM device. Our experimental result shows the center wavelength and bandwidth are 1549 and 17 nm, respectively. Furthermore, owing to the tiny size and low cost, the lensed fiber collimator will provide a wide utilization in the design of other passive devices and biosensors. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:319–322 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26539
A low power UWB low noise amplifier using current reused and feedback techniques
Authors: Galal A. I. A. , Pokharel R. , Kanaya H. , Yoshida K.
Published: December 2011

This letter presents a full band low power low noise amplifier design in 0.18‐μm complementary metal‐oxide‐semiconductor FET (CMOS) technology.The proposed circuit adopts current reused technique to achieve low power consumption, and shunt resistive feedback for wide‐band operation. An excellent wide and flat gain, low noise figure, are achieved by composes of these techniques. The implemented ultra‐wideband (UWB) low noise amplifier (LNA) exhibits a flat gain of 18 dB with total power consumption of 5.2 mA from 1.8 V power supply. The noise figure is 3.1 dB within the entire bandwidth. The input and output return loss is less than −10 dB in the specified bandwidth. The proposed technique exhibits 0.8 dBm of IIP3. The active die area of UWB LNA occupies 0.72 mm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:471–474, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26550
Design of a novel compact broadband patch antenna using binary PSO
Authors: Wang N. Z. , Wang X. B. , Xu J. D.
Published: December 2011

In this article, a C‐Band broadband patch antenna is designed. The binary particle swarm optimization (BPSO) combining with IE3D software is adopted to broaden the bandwidth of the patch antenna automatically. Characteristics of the antenna are calculated using the well‐known Zeland IE3D software package while the bandwidth characteristic of the antenna is optimized using BPSO technique. The comparison results show that the 3.2% impedance bandwidth (4.63–4.78 GHz) of the patch antenna is upgrade to 10.4% (4.47–4.96 GHz) through the BPSO‐IE3D method. The antenna gain is stable and the radiation patterns are similar in configuration over the whole operating frequencies to that of a conventional patch antenna. A prototype of the optimized antenna has been fabricated and important antenna parameters such as reflection coefficient (S11) parameter, gains and radiation patterns are measured using Network Analyzer and antenna test‐bench. The measured values of the antenna parameters are found to match well with that of the simulated results, all of which illustrate that the method is valid and the antenna can operate well. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:434–438, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26552
Investigations on an improved interstitial antenna used for microwave hyperthermia and the specific absorption rate distribution within biological tissues
Authors: Li Li , Che Wenquan , Chang Yumei
Published: December 2011

Hepatocellular carcinoma is one of the common tumors in the world, which leads to more than 600,000 deaths per year.Microwave hyperthermia has been widely used in hepatocellular carcinoma treatment, whereby the cancer cells are heated and killed by making use of the different thermal sensitivity of the cancer cells and normal cells. Monopole is used to be microwave radiator in recent years; however, the ablation region is elongated along the antenna insertion direction so that the skin and normal tissue around the tumor is also heated unexpectedly. It is desirable to generate a heating region in the vicinity of the antenna tip in a spherical manner. To solve the issue, a coaxial‐slot antenna with choke is proposed in the article, the specific absorption rate (SAR) distribution around antenna is computed by means of the finite difference time domain method. By comparison with the SAR distribution caused by monopole antenna, it is clear that no unnecessary heating region is generated near the surface of the body when the improved antenna is used. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 54:405–409, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26553
Printed dual dipole antenna with modified taper matching for wlan communication
Authors: Lee Hyeonjin , Jung Jinwoo , Lim Yeongseog
Published: December 2011

In this letter, a printed dipole antenna for wireless local area network (WLAN) communication is proposed.The proposed antenna consists of two dipole strips, which have modified dual monopoles and modified strip arms with tapered matching by the ground plane. The proposed antenna is increased radiation gain than the conventional dipole structure. The operating frequency band of the antenna is able to support WLAN of 5∼6.45 GHz. The measured peak gain is 4.8 dBi at 5.3 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:398–401, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26560
Design of a broadband reflectarray using meander‐shaped elements
Authors: Zhao J.‐J. , Gong S.‐X. , Xu Y.‐X. , Ren L.‐S.
Published: December 2011

A novel cell element, the combination of meander‐shaped rectangle and ring, is presented for reflectarray. The feature of the cell element is investigated along with the design of the feed and array. A 52‐element array prototype based on the proposed element has been fabricated and measured showing good results over a 26% 1‐dB gain bandwidth. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:500–503, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26563
Generation of a narrow microwave carrier from a bimodal fiber laser
Authors: Ferreira da Silva T. , Thomas D.H. , von der Weid J. P.
Published: December 2011

We report the heterodyne generation of a narrow radiofrequency carrier by the beat of the signal of a bimodal fiber laser. The bimodal operation of the designed multiple‐cavities‐filter‐based laser is presented, as well as the measured narrow microwave tone, suitable for modern microwave photonics links. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:416–421, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26566
Zero phase velocity error finite‐difference time‐domain method for small space step and large time step sizes
Authors: Kusaf Mehmet , Oztoprak Abdullah Y.
Published: December 2011

Unconditionally stable multi (4, 6, and 8) split‐step finite‐difference time‐domain methods are isotropic for a certain space step size and a stability factor.It is shown in this letter that for small step sizes the phase velocity errors can be corrected by using a factor which is a function of the product of the space step size and the stability factor. This way, it is not necessary to obtain the multiplication factor each time when a different space step size is used. Also, by using this multiplication factor zero phase velocity error can be obtained in all directions at a chosen frequency. Performance analyses have shown that the method is also wideband. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:423–426, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26567
A single‐FED slot‐aperture hybrid antenna for broadband circular polarization operations
Authors: Lu Yu‐Chun , Yu Ming‐Je , Lin Yi‐Cheng
Published: December 2011

This article presents a microstrip‐fed slot‐aperture hybrid antenna for wideband circularly polarized (CP) operations. The antenna consists of a U‐shaped slot, a rectangular aperture, and a probing strip fed by a microstrip line. In general, the U‐shaped slot and the rectangular aperture resonate at two separate frequencies. When properly arranged, the proposed antenna may resonate over a single wideband of CP radiation. The 3‐dB axial ratio (AR) bandwidth of the presented antenna in free space is about 27% with the gain level about 34 dBic. When a planar reflector is incorporated for the desirable unidirectional pattern, the presented antenna has an enhanced gain about 7 dBic with a 3‐dB AR bandwidth of 25% and a front‐to‐back ratio of about 14 dB. Good agreement between measured and simulated results was achieved. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:412–415, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26569
Tunable fourth LO‐harmonic mixer using CRLH‐TL and varactor diode
Authors: Zhao Shiwei , Tang Zongxi , Guo Fanyu , Su Ping
Published: December 2011

A novel fourth order harmonic mixer using composite right/left handed transmission lines and varactor diode is presented.The structure provides more flexible phase for suppressing spurious signals and improving conversion loss. Compared with conventional harmonic mixer, the measured results show that 10.4 dB conversion loss and 80 dB suppression of unwanted harmonics are achieved when local oscillator signal power is 7 dBm at 5 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:543–545, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26575
Bandwidth enhancement of WWAN/LTE tablet computer antenna using embedded parallel resonant circuit
Authors: Wong Kin‐Lu , Liu Ying‐Chien , Chou Liang‐Che
Published: December 2011

By embedding a printed parallel resonant circuit, the lower‐band bandwidth of the proposed internal tablet computer antenna is greatly enhanced.This bandwidth‐enhancement technique allows the proposed antenna to cover the eight‐band wireless wide area network/long term evolution operation in the 704–960 and 1710–2690 MHz bands with a small size of 12 × 60 × 3.8 mm3 in the tablet computer. The main radiator of the antenna comprises a patch monopole, a longer shorted strip, and a shorter shorted strip. The latter two shorted strips form the outer boundary of the antenna and are parasitically excited by the patch monopole. The parallel resonant circuit is formed by embedding a chip‐inductor‐loaded narrow strip in‐between the longer shorted strip and the patch monopole, with the narrow strip whose front terminal connected to the patch monopole and end section gap‐coupled to the longer shorted strip. This embedded circuit can lead to the generation of a parallel resonance seen at the antenna's feeding point. By controlling the parallel resonance to be at the high‐frequency tail of the resonant mode at about 800 MHz contributed by the longer shorted strip, an additional resonance can be generated, which can result in dual‐resonance excitation of the original single‐resonance mode. Thus, a wide antenna's lower band is obtained. Further, the patch monopole can contribute a resonant mode to combine additional resonant modes contributed by the two shorted strips to form a wide antenna's upper band. Details of the proposed antenna with the embedded parallel resonant circuit are described in the article. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:305–309, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26580