bluuebunny/crossref_metadata_2025 huggingface dataset:
Ceramic/polymer nanocomposites with tunable drug delivery capability at specific disease sites
Authors: Liu Huinan , Webster Thomas J.
Published: September 2009

Pharmaceutical agents are often used to stimulate new bone formation for the treatment of bone injuries or diseases (such as osteoporosis). However, there are several problems associated with current orthopedic drug delivery methods. First, conventional systemic administration of pharmaceutical agents may not effectively reach targeted sites and, thus, they can cause nonspecific bone formation in areas not affected by injury or disease. Second, even if intentionally delivered or implanted locally to the damaged bone tissue, these agents tend to rapidly diffuse into adjacent tissues due to weak physical bonding to their drug carriers, which limits their potential to promote prolonged bone formation in targeted areas of bone disease. Therefore, in this study, biodegradable ceramic/polymer nanocomposites were explored as novel drug carriers for orthopedic applications to prolong local drug release and, thus, improve drug effectiveness at bone disease sites. Specifically, a bone morphogenetic protein (BMP‐7) derived peptide (DIF‐7c) was used as a model drug in this study and was first loaded onto nanocrystalline hydroxyapatite (nano‐HA) by either covalent chemical attachment or physical adsorption. These drug‐carrying nano‐HA particles were then dispersed into a degradable polymer (poly‐lactide‐co‐glycolide or PLGA) matrix to create an implantable system capable of long‐term drug release. The aminophase silane covalent chemical immobilization process was utilized in this study. These nanocomposite‐based drug delivery systems were then characterized for drug loading efficiency andin vitrodrug release. Results demonstrated that DIF‐7c was successfully immobilized onto nano‐HA placed in PLGA. Moreover, a greater prolonged two‐phase release profile (of more than 3 months) was achieved when using aminophase silane chemical immobilization to nano‐HA particles. Since previous studies have demonstrated greaterin vivobone growth on nano‐ compared with micron‐HA particles placed in rat calvaria, this study continued to demonstrate that ceramic/polymer nanocomposites are promising candidates as novel orthopedic materials to promote bone regeneration. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Functionalization of chitosan/poly(lactic acid‐glycolic acid) sintered microsphere scaffolds via surface heparinization for bone tissue engineering
Authors: Jiang Tao , Khan Yusuf , Nair Lakshmi S. , Abdel‐Fattah Wafa I. , Laurencin Cato T.
Published: September 2009

Scaffolds exhibiting biological recognition and specificity play an important role in tissue engineering and regenerative medicine. The bioactivity of scaffolds in turn influences, directs, or manipulates cellular responses. In this study, chitosan/poly(lactic acid‐co‐glycolic acid) (chitosan/PLAGA) sintered microsphere scaffolds were functionalized via heparin immobilization. Heparin was successfully immobilized on chitosan/PLAGA scaffolds with controllable loading efficiency. Mechanical testing showed that heparinization of chitosan/PLAGA scaffolds did not significantly alter the mechanical properties and porous structures. In addition, the heparinized chitosan/PLAGA scaffolds possessed a compressive modulus of 403.98 ± 19.53 MPa and a compressive strength of 9.83 ± 0.94 MPa, which are in the range of human trabecular bone. Furthermore, the heparinized chitosan/PLAGA scaffolds had an interconnected porous structure with a total pore volume of 30.93 ± 0.90% and a median pore size of 172.33 ± 5.89 μm. The effect of immobilized heparin on osteoblast‐like MC3T3‐E1 cell growth was investigated. MC3T3‐E1 cells proliferated three dimensionally throughout the porous structure of the scaffolds. Heparinized chitosan/PLAGA scaffolds with low heparin loading (1.7 μg/scaffold) were shown to be capable of stimulating MC3T3‐E1 cell proliferation by MTS assay and cell differentiation as evidenced by elevated osteocalcin expression when compared with nonheparinized chitosan/PLAGA scaffold and chitosan/PLAGA scaffold with high heparin loading (14.1 μg/scaffold). This study demonstrated the potential of functionalizing chitosan/PLAGA scaffolds via heparinization with improved cell functions for bone tissue engineering applications. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Stable subclones of the chondrogenic murine cell line MC615 mimic distinct stages of chondrocyte differentiation
Authors: Surmann‐Schmitt Cordula , Widmann Nathalie , Mallein‐Gerin Frédéric , von der Mark Klaus , Stock Michael
Published: September 2009

Fourteen stable subclones derived from the murine chondrogenic cell line MC615 were established and characterised regarding their differentiation stages and responsivity to BMP2. Based on their gene expression profiles which revealed remarkable variances in Col2a1 and Col10a1 expression, subclones could be grouped into at least three distinct categories. Three representative subclones (4C3, 4C6 and 4H4) were further characterised with respect to gene expression pattern and differentiation capacity. These subclones resembled (i) weakly differentiated chondrogenic precursors, strongly responding to BMP2 stimulation (4C3), (ii) collagen II expressing chondrocytes which could be induced to undergo maturation (4C6) and (iii) mature chondrocytes expressing Col10a1 and other markers of hypertrophy (4H4). Interestingly, BMP2 administration caused Smad protein phosphorylation and stimulated Col10a1 expression in all clones, but induced Col2a1 expression only in precursor‐like cells. Most remarkably, these clones maintained a stable gene expression profile at least until the 30th passage of subconfluent culture, but revealed reproducible changes in gene expression and differentiation pattern in long term high density cultures. Thus, the newly established MC615 subclones may serve as a potent new tool for investigations on the regulation of chondrocyte differentiation and function. J. Cell. Biochem. 108: 589–599, 2009. © 2009 Wiley‐Liss, Inc.
JNK1/c‐Jun and p38α MAPK/ATF‐2 pathways are responsible for upregulation of Fas/FasL in human chronic myeloid leukemia K562 cells upon exposure to Taiwan cobra phospholipase A2
Authors: Chen Ku‐Chung , Chiou Yi‐Ling , Chang Long‐Sen
Published: September 2009

Fas and FasL expression upregulation was found in human leukemia K562 cells upon exposure to Naja naja atra phospholipase A2 (PLA2). PLA2 treatment induced an increase in intracellular Ca2+ ([Ca2+]i) and ROS generation levels, leading to activation of p38 MAPK and JNK. Suppression of both p38 MAPK and JNK abrogated Fas and FasL upregulation. Unlike PLA2, catalytically inactive PLA2 treatment did not markedly increase Fas and FasL protein expression, and p38 MAPK activation was exclusively responsible for catalytically inactive PLA2‐induced increase in Fas and FasL protein expression. Knockdown of p38α MAPK and JNK1 by siRNA proved that p38α MAPK and JNK1 were involved in ATF‐2 and c‐Jun phosphorylation, respectively. Compared with the p38α MAPK/ATF‐2 pathway, the JNK1/c‐Jun pathway played a crucial role in Fas/FasL upregulation. Unlike arachidonic acid, lysophosphatidylcholine mimicked the PLA2 action in inducing Fas/FasL upregulation. Together with the previous finding that c‐Jun and ATF‐2 are involved in transcriptional regulation of Fas and FasL, our data suggest that PLA2 induces Fas and FasL upregulation through p38α MAPK/ATF‐2 and JNK1/c‐Jun pathways in K562 cells, and PLA2 catalytic activity is involved in this action. J. Cell. Biochem. 108: 612–620, 2009. © 2009 Wiley‐Liss, Inc.
Neuropeptide Y is expressed by osteocytes and can inhibit osteoblastic activity
Authors: Igwe John C. , Jiang Xi , Paic Frane , Ma Li , Adams Douglas J. , Baldock Paul A. , Pilbeam Carol C. , Kalajzic Ivo
Published: September 2009

Osteocytes are the most abundant osteoblast lineage cells within the bone matrix. They respond to mechanical stimulation and can participate in the release of regulatory proteins that can modulate the activity of other bone cells. We hypothesize that neuropeptide Y (NPY), a neurotransmitter with regulatory functions in bone formation, is produced by osteocytes and can affect osteoblast activity. To study the expression of NPY by the osteoblast lineage cells, we utilized transgenic mouse models in which we can identify and isolate populations of osteoblasts and osteocytes. The Col2.3GFP transgene is active in osteoblasts and osteocytes, while the DMP1 promoter drives green fluorescent protein (GFP) expression in osteocytes. Real‐time PCR analysis of RNA from the isolated populations of cells derived from neonatal calvaria showed higher NPY mRNA in the preosteocytes/osteocytes fraction compared to osteoblasts. NPY immunostaining confirmed the strong expression of NPY in osteocytes (DMP1GFP+), and lower levels in osteoblasts. In addition, the presence of NPY receptor Y1 mRNA was detected in cavaria and long bone, as well as in primary calvarial osteoblast cultures, whereas Y2 mRNA was restricted to the brain. Furthermore, NPY expression was reduced by 30–40% in primary calvarial cultures when subjected to fluid shear stress. In addition, treatment of mouse calvarial osteoblasts with exogenous NPY showed a reduction in the levels of intracellular cAMP and markers of osteoblast differentiation (osteocalcin, BSP, and DMP1). These results highlight the potential regulation of osteoblast lineage differentiation by local NPY signaling. J. Cell. Biochem. 108: 621–630, 2009. © 2009 Wiley‐Liss, Inc.
ERK‐1 MAP kinase prevents TNF‐induced apoptosis through bad phosphorylation and inhibition of Bax translocation in HeLa Cells
Authors: Pucci Bruna , Indelicato Manuela , Paradisi Valentina , Reali Valentina , Pellegrini Laura , Aventaggiato Michele , Karpinich Natalie O. , Fini Massimo , Russo Matteo A. , Farber John L. , Tafani Marco
Published: September 2009

Extracellular signal‐regulated kinase (ERK) 1/2 signaling is involved in tumor cell survival through the regulation of Bcl‐2 family members. To explore this further and to demonstrate the central role of the mitochondria in the ERK1/2 pathway we used the HeLa cellular model where apoptosis was induced by tumor necrosis factor (TNF) and cycloheximide (CHX). We show that HeLa cells overexpressing ERK‐1 displayed resistance to TNF and CHX. HeLa cells overexpressing a kinase‐deficient form of ERK‐1 (K71R) were more sensitive to TNF and CHX. In the ERK‐1 cells, Bad was phosphorylated during TNF + CHX treatment. In the HeLa wt cells and in the K71R clones TNF and CHX decreased Bad phosphorylation. ERK‐1 cells treated with TNF and CHX did not release cytochrome c from the mitochondria. By contrast, HeLa wt and K71R clones released cytochrome c. Bax did not translocate to the mitochondria in ERK‐1 cells treated with TNF + CHX. Conversely, HeLa wt and K71R clones accumulated Bax in the mitochondria. In the HeLa wt cells and in both ERK‐1 transfectants Bid was cleaved and accumulated in the mitochondria. The caspase‐8 inhibitor IETD‐FMK and the mitochondrial membrane permeabilization inhibitor bongkrekic acid (BK), partially prevented cell death by TNF + CHX. Anisomycin, a c‐Jun N‐terminal kinases activator, increased TNF‐killing. The ERK‐1 cells were resistant to TNF and anisomycin, whereas K71R clones resulted more sensitive. Our study demonstrates that in HeLa cells the ERK‐1 kinase prevents TNF + CHX apoptosis by regulating the intrinsic mitochondrial pathway through different mechanisms. Inhibition of the intrinsic pathway is sufficient to almost completely prevent cell death. J. Cell. Biochem. 108: 1166–1174, 2009. © 2009 Wiley‐Liss, Inc.
Lanthanum suppresses osteoblastic differentiation via pertussis toxin‐sensitive G protein signaling in rat vascular smooth muscle cells
Authors: Shi Yan‐Ling , Wang Li‐Wen , Huang Jian , Gou Bao‐Di , Zhang Tian‐Lan , Wang Kui
Published: September 2009

A major cellular event in vascular calcification is the phenotypic transformation of vascular smooth muscle cells (VSMCs) into osteoblast‐like cells. After demonstrating that lanthanum chloride (LaCl3) suppresses hydrogen peroxide‐enhanced calcification in rat calcifying vascular cells (CVCs), here we report its effect on the osteoblastic differentiation of rat VSMCs, a process leading to the formation of CVCs. Cells were isolated from aortic media of male SD rats, and passages between three and eight were cultured in Dulbeccol's Modified Eagle's Medium (DMEM) containing 10% fetal bovine serum (FBS) and 10 mM β‐glycerophosphate (β‐GP) in the presence or absence of LaCl3. Exposure of cells to LaCl3 suppressed the β‐GP‐induced elevations in calcium deposition, alkaline phosphatase (ALP) activity, and Cbfa1/Runx2 expression, as well as the concomitant loss of SM α‐actin. Furthermore, LaCl3 activated the phosphorylation of extracellular signal‐regulated kinase (ERK) and c‐Jun N‐terminal kinase (JNK), and the blockage of either pathway with a specific inhibitor abolished the effects of LaCl3. In addition, pretreatment of the cells with pertussis toxin (PTx), an inhibitor of G protein‐mediated signaling pathway, repealed all the changes induced by LaCl3. These findings demonstrate that LaCl3 suppresses the β‐GP‐induced osteoblastic differentiation and calcification in rat VSMCs, and its effect is mediated by the activation of both ERK and JNK MAPK pathways via PTx‐sensitive G proteins. J. Cell. Biochem. 108: 1184–1191, 2009. © 2009 Wiley‐Liss, Inc.
Evaluation of exchange‐correlation functionals for time‐dependent density functional theory calculations on metal complexes
Authors: Holland Jason P. , Green Jennifer C.
Published: September 2009

The electronic absorption spectra of a range of copper and zinc complexes have been simulated by using time‐dependent density functional theory (TD‐DFT) calculations implemented in Gaussian03. In total, 41 exchange‐correlation (XC) functionals including first‐, second‐, and third‐generation (meta‐generalized gradient approximation) DFT methods were compared in their ability to predict the experimental electronic absorption spectra. Both pure and hybrid DFT methods were tested and differences between restricted and unrestricted calculations were also investigated by comparison of analogous neutral zinc(II) and copper(II) complexes. TD‐DFT calculated spectra were optimized with respect to the experimental electronic absorption spectra by use of a Matlab script. Direct comparison of the performance of each XC functional was achieved both qualitatively and quantitatively by comparison of optimized half‐band widths, root‐mean‐squared errors (RMSE), energy scaling factors (εSF), and overall quality‐of‐fit (QF) parameters. Hybrid DFT methods were found to outperform all pure DFT functionals with B1LYP, B97‐2, B97‐1, X3LYP, and B98 functionals providing the highest quantitative and qualitative accuracy in both restricted and unrestricted systems. Of the functionals tested, B1LYP gave the most accurate results with both average RMSE and overall QF < 3.5% and εSF values close to unity (>0.990) for the copper complexes. The XC functional performance in spin‐restricted TD‐DFT calculations on the zinc complexes was found to be slightly worse. PBE1PBE, mPW1PW91 and B1LYP gave the most accurate results with typical RMSE and QF values between 5.3 and 7.3%, and εSF around 0.930. These studies illustrate the power of modern TD‐DFT calculations for exploring excited state transitions of metal complexes. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010
Engineering adeno‐associated virus serotype 2‐based targeting vectors using a new insertion site‐position 453‐and single point mutations
Authors: Boucas Jorge , Lux Kerstin , Huber Anke , Schievenbusch Stephanie , von Freyend Miriam John , Perabo Luca , Quadt‐Humme Sibille , Odenthal Margarete , Hallek Michael , Büning Hildegard
Published: September 2009

Background

Genetic modification of capsid proteins by peptide insertion has created the possibility of using adeno‐associated viral (AAV) vectors for receptor specific gene transfer (AAV targeting). The most common site used for insertion in AAV serotype 2 capsids are amino acid positions 587 and 588 located at the second highest capsid protrusion. Reasoning that peptide insertions at the most exposed position augments target receptor interaction, we explored position 453 as a new insertion site.

Methods

Position 453 was identified in silico. Capsid mutants carrying the model ligand RGD‐4C in position 453 with and without R585A/R588A substitutions were compared with respective mutants carrying the ligand in position 587. The accessibility of the inserted ligand was determined by an enzyme‐linked immunosorbent assay, whereas the transduction efficiency and specificity of receptor binding were assayed by gene transfer and competition experiments, respectively. Vector biodistribution was determined in mice by quantitative polymerase chain reaction analysis.

Results

Initially, RGD‐4C, inserted at position 453, failed to efficiently bind its target receptor. R585 and R588, located at the neighboring peak and known to mediate primary receptor binding, were identified as interfering residues. R585A and R588A substitutions rendered position 453 mutants superior to those with the ligand in position 587 in target receptor binding and cell transduction efficiency. The in vivo biodistribution was independent of the insertion site, but directed by the inserted ligand when primary receptor binding was avoided.

Conclusions

Position 453 emerged as a prominent site for the development of targeting mutants. Furthermore, we show for the first time that linearly distant residues can be critical for the efficiency of inserted peptide ligands. Copyright © 2009 John Wiley & Sons, Ltd.
Identification and spectra–structure determination of soil minerals: Raman study supported by IR spectroscopy and X‐ray powder diffraction
Authors: Tomić Zorica , Makreski Petre , Gajić Boško
Published: September 2009

Raman and IR spectroscopy were used for the characterization of several minerals in morphologically similar vertisol sequences from Kiževak (Serbia). It helped us to establish the surface layer transition going from calcic vertisols (containing gypsum and calcite) to calcimagnesic vertisols (containing aragonite, magnesium‐calcite and dolomite) derived from peridotite and serpentinite. The observed band positions are found to be solely characteristic for each carbonate mineral and are used to discuss the main structural features of carbonates and sulfates present in the studied soil. It was found that the dolomite, calcite and aragonite concretions are present in the deepest layer of the soil, whereas the gypsum is found in the topsoil. The identification was confirmed of the carbonates having calcite and aragonite structure, and the representative from the sulfate group (gypsum) was confirmed by X‐ray powder diffraction. Copyright © 2009 John Wiley & Sons, Ltd.
Probing the adsorption of methylimidazole at ionic liquids/Cu electrode interface by surface‐enhanced Raman scattering spectroscopy
Authors: Yuan Ya‐Xian , Niu Tian‐Chao , Xu Min‐Min , Yao Jian‐Lin , Gu Ren‐Ao
Published: September 2009

Two kinds of room‐temperature ionic liquids, 1‐butyl‐3‐methylimidazolium bromide ([BMIM]Br) and 1‐butyl‐3‐methylimidazolium tetrafluoroboride ([BMIM]BF4), were used as solvent, and the adsorption of the ionic liquids themselves and of N‐methylimidazole (NMIM) were investigated by electrochemical surface‐enhanced Raman scattering (SERS) over a wide potential window. The results revealed that the cation of ionic liquid adsorbed onto Cu surface with different configurations in different potential ranges. When the potential was changed from the negative to the positive range, the orientation underwent a change from flat to vertical, and the onset potential for the orientation change was dependent on the types of anion of the ionic liquid. The ionic liquid in bulk solution exhibited a remarkable effect on the adsorption of NMIM. The electrode surface structure changed from adsorbing the ionic liquid at the negative potential to coadsorbing the ionic liquid and NMIM at relative positive potential for the [BMIM]BF4 liquids, and formed films of NMIM at extremely positive potential. Due to the strong specific adsorption of Br−, the coadsorption of ionic liquid and NMIM was not observed in the system [BMIM]Br. By simulating the electrode surroundings, two surface complexes [Cu(NMIM)4Br]Br·H2O and [Cu(NMIM)4](BF4)2 were synthesized by the electrochemical method in the corresponding ionic liquids for modeling the surface coordination chemistry of NMIM. The surface coordination configuration of NMIM and ionic liquids is proposed. Copyright © 2009 John Wiley & Sons, Ltd.
Expression of X‐linked inhibitor of apoptosis protein in human colorectal cancer and its correlation with prognosis
Authors: Guoan Xiang , Xiaomin Wen , Hanning Wang , Kaiyun Chen , Hao Liu
Published: September 2009

Background

X‐linked inhibitor of apoptosis protein (XIAP) is a member of the inhibitor of apoptosis family of proteins and deregulation of XIAP can result in tumorigenicity. The objective of this study was to evaluate the prognostic significance of XIAP expression in colorectal cancer (CRC).

Methods

RT‐PCR was performed to detect the expression of XIAP mRNA in CRC cells and tissues. The expression of XIAP protein in tissues was measured by immunohistochemistry. The correlation of XIAP expression with clinicopathologic factors and prognosis of CRC patients was evaluated.

Results

CRC cells showed significantly higher levels of XIAP mRNA expression than normal human intestinal epithelial cell. The expression level of XIAP mRNA in CRC samples was significantly higher than that in corresponding non‐tumor samples. XIAP staining was positive in the cytoplasm of CRC cells. Higher XIAP protein expression was significantly correlated with tumor differentiation (P = 0.016), venous invasion (P = 0.039), and Duke's staging (P = 0.002). Moreover, XIAP‐high group showed lower disease‐free (P = 0.0136) and overall survival (P = 0.0084) rates than XIAP‐low group. Multivariate analysis indicated that the status of XIAP expression was an independent prognostic factor for CRC (P = 0.0206; HR: 2.730; 95% CI: 1.226–5.445).

Conclusion

The status of XIAP expression might become an independent prognostic marker for CRC. J. Surg. Oncol. 2009;100:708–712. © 2009 Wiley‐Liss, Inc.
Dispersion‐solidification liquid–liquid microextraction for volatile aromatic hydrocarbons determination: Comparison with liquid phase microextraction based on the solidification of a floating drop
Authors: Vickackaite Vida , Pusvaskiene Edita
Published: September 2009

Two microextraction techniques – liquid phase microextraction based on solidification of a floating organic drop (LPME‐SFO) and dispersive liquid–liquid microextraction combined with a solidification of a floating organic drop (DLLME‐SFO) – are explored for benzene, toluene, ethylbenzene and o‐xylene sampling and preconcentration. The investigation covers the effects of extraction solvent type, extraction and disperser solvents' volume, and the extraction time. For both techniques 1‐undecanol containing n‐heptane as internal standard was used as an extracting solvent. For DLLME‐SFO acetone was used as a disperser solvent. The calibration curves for both techniques and for all the analytes were linear up to 10 μg/mL, correlation coefficients were in the range 0.997–0.998, enrichment factors were from 87 for benzene to 290 for o‐xylene, detection limits were from 0.31 and 0.35 μg/L for benzene to 0.15 and 0.10 μg/L for o‐xylene for LPME‐SFO and DLLME‐SFO, respectively. Repeatabilities of the results were acceptable with RSDs up to 12%. Being comparable with LPME‐SFO in the analytical characteristics, DLLME‐SFO is superior to LPME‐SFO in the extraction time. A possibility to apply the proposed techniques for volatile aromatic hydrocarbons determination in tap water and snow was demonstrated.
Microfluidic HPLC‐Chip devices with integral channels containing methylstyrenic‐based monolithic media
Authors: Robotti Karla M. , Yin Hongfeng , Brennen Reid , Trojer Lukas , Killeen Kevin
Published: September 2009

Polyimide HPLC‐Chip devices containing poly(methylstyrene‐bis‐p‐vinylphenyl)ethane (MS/BVPE) stationary phase within the device channels and with wall attachment were prepared by thermally initiated free radical polymerization. The microfluidic devices were coupled to both UV and MS detectors. The potential of the MS/BVPE monolith as an alternative separation media within chip devices was investigated by side‐by‐side comparisons to particulate media within commercial devices. The chromatographic behavior of this stationary phase was comparable to particulate media for separations of proteins as the average peak width at half‐height was equal (6.2 s) for a separation within 8 min under gradient elution conditions. The ability to control the porosity characteristics of the MS/BVPE monolith with changes in polymerization time also extended its utility into small analyte (< 500 Da) applications, although more optimization is needed to match conventional RP media for these applications. The good mechanical stability of the MS/BVPE monolith within the microdevices enabled excellent run‐to‐run repeatability (%RSD retention time (⪇ 0.16) and chip‐to‐chip reproducibility (%RSD retention time (1.4). The use of this material within enrichment channels also shows its potential value in more complex work flows.
Determination of ethyl glucuronide in human serum by capillary zone electrophoresis and an immunoassay
Authors: Jung Balthasar , Caslavska Jitka , Thormann Wolfgang
Published: September 2009

Ethyl glucuronide (EtG) is a marker of recent alcohol consumption. For the optimization of the analysis of EtG by CZE with indirect absorbance detection, the use of capillaries with permanent and dynamic wall coatings, the composition of the BGE, and various sample preparation procedures, including dilution with water, ultrafiltration, protein precipitation, and SPE, were investigated. Two validated screening assays for the determination of EtG in human serum, a CZE‐based approach and an enzyme immunoassay (EIA), are described. The CZE assay uses a coated capillary, 2,4‐dimethylglutaric acid as an internal standard, and a pH 4.65 BGE comprising 9 mM nicotinic acid, ε‐aminocaproic acid and 10% v/v ACN. Proteins are removed via precipitation with ACN prior to analysis and the LOQ is 0.50 mg/L. The EIA is based upon commercial reagents which are promoted for the determination of urinary EtG. Krebs–Ringer solution containing 5% BSA is used as a calibration matrix. All samples are ultrafiltered prior to analysis of the ultrafiltrate on a Mira Plus analyzer. Assay calibration ranged between 0 and 2 mg/L and the upper reference limit was determined to be 0.05 mg/L. Both assays proved to be suitable for the analysis of samples from different individuals. For EtG levels above 0.50 mg/L, good agreement was observed for the comparison of the results of the two methods.
Rotenone induces apoptosis in MCF‐7 human breast cancer cell‐mediated ROS through JNK and p38 signaling
Authors: Deng Yea‐Tzy , Huang Hsiu‐Chen , Lin Jen‐Kun
Published: September 2009

Rotenone is an inhibitor of the mitochondrial electron transport chain complex I, resulting in the generation of reactive oxygen species (ROS). Rotenone has been shown to display anticancer activity through the induction of apoptosis in various cancer cells. However, the underlying mechanism is still not fully understood. Here, rotenone showed a strong growth inhibitory effect against human breast cancer MCF‐7 cells. DNA flow cytometric analysis, chromatin condensation, and poly (ADP‐ribose) polymerase (PARP) cleavage indicated rotenone actively induced apoptosis in MCF‐7 cells. The antiapoptotic protein, Bcl‐2, was decreased, whereas the apoptotic protein, Bax, was increased in a time‐dependent manner in rotenone‐induced apoptosis. Moreover, the treatment of rotenone in MCF‐7 cells caused the activation of c‐junN‐terminal kinase (JNK) and p38 mitogen‐activated protein kinases (MAPKs), and the inactivation of extracellular signal‐regulated protein kinase 1/2 (ERK1/2). The pharmacological inhibition of JNK and p38 MAPK revealed significant protection against rotenone‐induced apoptosis. Taken together, these results indicate rotenone may induce apoptosis through ROS and JNK/p38 MAPKs activation in MCF‐7 cells. © 2009 Wiley‐Liss, Inc.
Tunable band‐notched ultra wideband planar monopole antenna
Authors: Jeong Won‐Seok , Kim Dong‐Zo , Lim Won‐Gyu , Yu Jong‐Won
Published: September 2009

A new tunable band‐notched ultra wideband planar monopole antenna is presented. The proposed antenna consists of a wideband planar monopole antenna, band‐notched resonating stubs, and varactor diodes. To generate the tunable band‐notched characteristic, we applied a short‐circuited quarter‐wavelength stub with a varactor diode to the wideband planar monopole antenna. We show the mechanism for notch characteristic using surface current distribution. This new approach is suitable for designing wideband antenna with narrow band interferer rejection characteristic. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2829–2832, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24744
The application of wide spectrum laser in noncontact vibration measurement
Authors: Wang Chao , Tang Huang , Xiao Qian , Jia Bo
Published: September 2009

An all‐fiber interferometer with wide spectrum laser source to measure vibration is introduced. The interference fringes envelop decay caused by wide spectrum laser source under large amplitude vibration is analyzed. The interference signals is retrieved through solving linear equations, and the wide spectrum distortion while demodulating the vibration signal is eliminated. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2858–2861, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24746
A highly linear and efficient three‐way Doherty amplifier using two‐stage GaN HEMT cells for repeater systems
Authors: Lee Yong‐Sub , Lee Mun‐Woo , Kam San‐Ho , Jeong Yoon‐Ha
Published: September 2009

In this article, we propose a highly linear and efficient three‐way Doherty amplifier using two‐stage GaN HEMT cells for repeater systems. The driving cells are used as the predistortion circuit to improve linearity as well as the gain stage. The main cells are optimized to achieve high efficiency at a large back‐off power. After gate bias optimization of the driving cells, the proposed three‐way Doherty amplifier with two‐stage cells shows highly linear and efficient performance. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2895–2898, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24748
A novel coding method with remodulation format used in a WDM‐PON to enhance extinction ratio
Authors: Huang Bo , Liang Yaoxiong , Qin Yi , Chi Nan
Published: September 2009

We report a new approach to eliminate the extinction ratio (ER) limitation in a wavelength division multiplexed passive optical network using RZ‐ASK/DPSK remodulation format corresponding to downstream/upstream signals, respectively. A novel precoding method can improve the ER tolerance from 6 to 13 dB for a 40‐Gb/s RZ‐ASK downstream and 622‐Mb/s DPSK upstream experimental transmission with <1 dB penalty. Rayleigh and stimulated Brillouin backscattering effects are simulated and analyzed in the deployment of a bidirectional 40G Ethernet PON probably using in practical application. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2994–2997, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24750
Biocompatibility study of beta tricalcium phosphate bioceramics and chitosan biopolymer and their use as phantoms for medical imaging applications
Authors: Augustine Robin , Kalappura Ullas G. , Laheurte Jean‐Marc , Mathew Kattackal T.
Published: September 2009

Beta tricalcium phosphate (β‐TCP) bioceramics and chitosan biopolymers are used as biomedical implants because of their better biocompatibility and good bioresorption characteristics. As they are biomaterials, they have good interactions with microwave frequencies. β‐TCP and chitosan powder, films, pellets, and gel are prepared and studied at the S‐band microwave frequencies. Dielectric parameters such as dielectric constant, dielectric loss, conductivity, and S‐parameters are evaluated. Dielectric parameters of different forms of β‐TCP and chitosan show resemblance with that of human tissues. Hence, these materials can also be considered as potential phantoms for specific absorption rate measurements as well as in microwave imaging applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2923–2927, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24752
Super‐dense array emulating the human eye vision properties
Authors: Andrés‐García B. , García‐Muñoz E. , González‐Posadas V. , Segovia‐Vargas D.
Published: September 2009

A super‐dense array based on the human eye photoreceptor physiology is proposed in this article. This study is a retinal model using individual dipole elements working at 20 GHz. The gain of the system in terms of the distance to the center is computed for applying it to an image. In this way, the human eye vision with elemental antennas is emulated. Also, an electromagnetic explanation has been given to the transmission of the information to the brain through the mutual coupling between elements. This article stands for checking the versatility of the human eye vision in the microwave range, for applying it to imaging arrays in the low‐Terahertz band. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2954–2959, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24754
Matching a Bluetooth headset antenna on a small system ground by using a conductive wire
Authors: Chou Jui‐Hung , Su Saou‐Wen
Published: September 2009

In this article, a simple, yet effective method for matching a compact planar inverted‐F antenna (PIFA) on a small system circuit board for Bluetooth headset applications is presented. The antenna is perpendicular to and extends along the top and right sides of the system ground, making it possible for the antenna to occupy almost no limited board space. Results have shown that by introducing a thin conductive wire soldered to the bottom corner of the system ground, good input matching over the 2400–2484 MHz band can easily be achieved for the PIFA mounted on a small ground of length less than a quarter wavelength at 2440 MHz. Radiation measurements of the proposed design in a real headset attached to a standard head phantom are also taken. Details of the obtained experimental and simulation results are given and discussed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2802–2805, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24755
Design of Appollian‐like gasket fractal antenna with coplanar waveguide (CPW)‐fed
Authors: Kumar Raj , Tiwari Anupam
Published: September 2009

This article presents design of Appollian‐like gasket CPW‐fed fractal antenna. The antenna has been designed on FR4 substrate, εr = 4.3, with a thickness of 1.53 mm. The antenna has been fabricated and tested using VNA. The experimental result of this antenna shows the multiband behavior with the centre frequencies of 1.265, 4.66, and 7.8 GHz with impedance bandwidth of 50%, 17.5%, and 15%, respectively. The shift in first resonant frequency of antenna reveals the size reduction in comparison of solid equilateral triangular patch of 40 mm. The experimental radiation pattern of the antenna has been observed near to omnidirectional at lower frequency and like electric dipole antenna at higher frequency. This antenna can be used for short range wireless applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2836–2839, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24757
High‐efficiency outphasing transmitter using class‐E power amplifiers and asymmetric combining
Authors: Beltran Ramon , Raab Frederick H. , Velazquez Arturo
Published: September 2009

Chireix outphasing systems have been used successfully with power amplifiers (PAs) operating in class‐B and F. Class‐E PAs can produce high efficiency at microwave frequencies. However, the impedances produced by conventional outphasing are unsuitable for class E, resulting in poor efficiency and/or poor dynamic range. The asymmetric combining technique described here uses transmission lines or equivalent networks of different electrical lengths to position the impedance loci to provide good dynamic range while maintaining high efficiency. This in turn allows linear power amplification of amplitude‐modulated signals with high average efficiency. The concept is verified by a 25.7‐W peak output power transmitter that achieves an efficiency of 85% or better over an amplitude range of 10 dB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2959–2963, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24758
Compact monopole antenna design for WLAN/UWB applications
Authors: Chung Wen‐Tsan , Lee Ching‐Her , Sim Chow‐Yen‐Desmond
Published: September 2009

This article presents a compact microstrip‐fed monopole antenna for application in WLAN (2.4–2.484 GHz) and UWB (3.1–10.6 GHz) bands. The radiating element of the proposed antenna consists of two arms that resonate at the fundamental frequencies of 2.45 and 3.5 GHz. A narrow slot is purposely embedded in the ground plane under the microstrip feed line to improve the impedance matching for the higher‐order modes of the two radiating arms for achieving an ultra‐wide‐band response. A prototype of the designed antenna is fabricated and measured, and satisfactory radiation properties were observed. The measured 10‐dB return‐loss bandwidth (maximum peak gain) of the 2.4‐GHz WLAN band is 0.17 GHz (4 dB), and that of the UWB band is 7.65 GHz (8.7 dB). In addition, a small group‐delay variation of less than 1 ns was observed in the UWB. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2874–2878, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24759
An investigation of wideband circular cylindrical sector dielectric resonator antenna with microstripline feed
Authors: Gopakumar C. , Yohannan Jaimon , Kalappura Ullas G. , Mathew K. T.
Published: September 2009

The article proposes a compact microstrip line fed dielectric resonator antenna with half split circular, cylindrical profile which is experimentally investigated. It shows that at optimum parameters, this low profile, small size antenna gives a wideband response similar to that of its full cylindrical counter part with moderate gain but at different frequency. The return loss and radiation pattern of the proposed antenna is measured and studied. The simulated and measured results verify that the proposed antenna offers an impedance bandwidth of 36.7% (from 3.24 to 4.70 GHz) and shows a radiation pattern which is relatively conical in shape with linear polarization. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2861–2865, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24762
Compact directional antenna for ultra wideband microwave imaging system
Authors: Abbosh A. M. , Bialkowski M. E.
Published: September 2009

A planar antenna of tapered slot configuration for use in ultra wideband microwave imaging systems aimed for early breast cancer detection is presented. It is designed to operate across the ultra wideband frequency (3.1–10.6 GHz) in a liquid of a high dielectric constant that matches the electric properties of average breast tissues. It has a very compact size with overall dimensions of 0.9 cm × 1 cm. The antenna's ultra wideband performance even when it is close to the breast tissues and its distortionless response in the time domain make it suitable for the microwave imaging systems utilizing a short‐pulse radar technique. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2898–2901, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24764
Four FET active integrated microstrip antenna
Authors: Eccleston Kimberley W.
Published: September 2009

In this article, an active integrated microstrip antenna combining the output power of four field‐effect transistors (FETs) is described. The radiation pattern is similar to a four‐element phased array. The antenna is fed along its nonradiating edge thereby permitting the FETs to be connected directly to it. A prototype operating at 2.455 GHz demonstrates the feasibility of the antenna. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2997–3000, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24768
Capacitively loaded spiral‐shaped resonator for coplanar waveguide
Authors: Son Wang‐Ik , Lim Won‐Gyu , Kim Dong‐Zo , Lee Moon‐Que , Yu Jong‐Won
Published: September 2009

A new coplanar waveguide bandstop filter using capacitively loaded spiral‐shaped resonator is proposed. The filter consists of a rectangular stepped coplanar waveguide and a spiral‐shaped slot in the center conductor. By embedding capacitor in the spiral‐shaped slot, tunable bandstop filter can be implemented, and tuning range from 1.5 to 3.0 GHz have been obtained. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 3001–3004, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24769
A miniaturized UWB antenna with improved stop‐band characteristics
Authors: Jang Joon‐Won , Hwang Hee‐Yong
Published: September 2009

This article presents a miniaturized UWB antenna with improved band‐rejection characteristics in 5 GHz band for ultra‐wideband applications. Using the symmetrical planes of a conventional circular‐slot (CS)‐UWB antenna and additional optimizing on its ground plane, slot angle, and feeding part we obtain a miniaturized UWB antenna with only 15.7% size of the conventional CS‐UWB antenna or 64% size of the conventional QCS‐UWB antenna. Adopting a small parasitic patch and a parasitic slot, simultaneously, to the miniaturized UWB antenna, we achieved the final miniaturized UWB antenna with excellent band‐rejection characteristics. We fabricated the proposed miniaturized UWB antenna on RF‐60A substrate. The measured bandwidth is from 3.0 GHz to 10.13 GHz for VSWR below 2.0 with excellent band‐rejection characteristics in 5.18–6.16 GHz band. The asymmetric antenna geometry by the miniaturization gives higher directivity in radiation pattern and slightly reduced gain compared to the conventional CS‐UWB antenna. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2842–2845, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24772
Small‐size printed monopole with a printed distributed inductor for pentaband WWAN mobile phone application
Authors: Chang Chih‐Hua , Wong Kin‐Lu
Published: September 2009

In this article, a small‐size printed monopole embedded with a printed narrow strip as a distributed inductor for application in the mobile phone to achieve GSM850/900/1800/1900/UMTS pentaband wireless wide area network operation is presented. With the printed distributed inductor, the fundamental (lowest) resonant mode of the proposed antenna can be effectively shifted to lower frequencies with a wide operating bandwidth, owing to the contributed inductance of the printed distributed inductor compensating for the increased capacitance resulting from the decreased resonant length of the monopole. In this study, the proposed antenna can be printed on the small no‐ground portion of size 14 × 40 mm2 on the main circuit board of the mobile phone, making it easy to fabricate at low cost and generally showing no thickness above the circuit board; the latter is very attractive for thin‐profile mobile phone applications. The proposed monopole antenna is studied in detail in this article. The results also show that the antenna is very suitable to be placed at the bottom of the mobile phone; in this case, the antenna meets the specific absorption rate limit for practical applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2903–2908, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24775
A novel CSRR‐based defected ground structure with dual‐bandgap characteristics
Authors: Fu Shu‐Hong , Tong Chuang‐Ming
Published: September 2009

A new type of dumbbell‐shaped defected ground structure (DGS) is introduced in this article. Its dual‐bandgap characteristics are reported for the first time and can be adjusted by changing the dimension of complementary split‐ring resonators (CSRR) unit and gap. The dual bandstop filter using proposed DGS is designed and fabricated. Measured results show that there are two bandgaps centered at 3.35 GHz and 5.82 GHz, respectively. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2908–2910, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24776
Right isosceles triangular microstrip antenna with narrow L‐shaped slot
Authors: Sharma Vijay , Shekhawat S. , Saxena V. K. , Saini J. S. , Sharma K. B. , Soni B. , Bhatnagar D.
Published: September 2009

The radiation performance of a right isosceles triangular microstrip antenna (RITMA) having a narrow L slot is analyzed in free space. The designed antenna on glass epoxy FR‐4 substrate efficiently resonates at three different frequencies that lie in three frequency bands allotted by IEEE 802.16 working group for Wi‐Max systems. Two of these frequencies present excellent matching with inset feed network applied during this course of work. The bandwidth and directivity of proposed RITMA structure with ‘L’ shaped slot has also improved considerably in comparison to that of a simple RITMA geometry, although gain and efficiency of antenna are marginally decreased. The E and H plane co‐polar and cross‐polar radiation patterns of this antenna are also drawn. The measured and simulated results of this antenna are compared with that of a simple RITMA having identical dimensions to obtain important conclusions. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 3006–3010, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24781
Development of a K‐band FMCW phased array radar sensor with low complexity receiver based on antenna switching
Authors: Lee Moon‐Sik , Kim Yong‐Hoon
Published: September 2009

A K‐band frequency‐modulated continuous wave phased array radar sensor with low‐complexity receiver based on antenna switching is developed. The radar sensor comprises a single transmitter, a single transmitting antenna, four receiving antennas, a single‐pole four‐throw switch, and a single receiving channel. The receiving antennas are switched to the single receiving channel periodically. The performance of the developed radar sensor is evaluated experimentally on the basis of the angle and range information obtained by using a beamforming method. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2848–2850, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24785
Comparison of Pendry's superlens with computational image reconstruction
Authors: Neice Andrew
Published: September 2009

A comparison of two methods of subwavelength imaging is undertaken. Pendry's superlens is compared with a computational image reconstruction technique. In both cases, limitations of materials impose limits on resolution. Both systems have similar limits, suggesting that resolution restrictions on Pendry's superlens apply generally to various forms of subwavelength imaging. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2913–2914, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24791