bluuebunny/crossref_metadata_2025 huggingface dataset:
Beyond the nearest‐neighbor Zimm–Bragg model for helix‐coil transition in peptides
Authors: Murza Adrian , Kubelka Jan
Published: September 2008

The nearest‐neighbor (μ = 1) variant of the Zimm and Bragg (ZB) model has been extensively used to describe the helix‐coil transition in biopolymers. In this work, we investigate the helix‐coil transition for a 21‐residue alanine peptide (AP) with the ZB model up to fourth nearest neighbor (μ = 1, 2, 3, and 4). We use a matrix approach that takes into account combinations of any number of helical stretches of any length and therefore gives the exact statistical weight of the chain within the assumptions of the ZB model. The parameters of the model are determined by fitting the temperature‐dependent circular dichroism and Fourier transform infrared experimental spectra of the AP. All variants of the model fit the experimental data, thus giving similar results in terms of the macroscopic observables, such as temperature‐dependent fractional helicity. However, the resulting microscopic parameters, such as distributions of the individual residue helical probabilities and free energy surfaces, vary significantly depending on the variant of the model. Overall, the mean residue enthalpy and entropy (in the absolute value) both increase with μ, but combined yield essentially the same “effective” value of the ZB propagation parameters for all μ. Greater helical probabilities for individual residues are predicted for larger μ, in particular, near the center of the sequence. The ZB nucleation parameters increase with increasing μ, which results in a lower free energy barrier to helix nucleation and lower apparent “cooperativity” of the transition. The significance of the long‐range interactions for the predictions of ZB model for helix‐coil transition, the calculated model parameters and the limitations of the model are discussed. © 2008 Wiley Periodicals, Inc. Biopolymers 91: 120–131, 2009.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Optimizing high‐performance liquid chromatography method for quantification of glucosamine using 6‐aminoquinolyl‐N‐hydroxysuccinimidyl carbamate derivatization in rat plasma: application to a pharmacokinetic study
Authors: Wang Xianhuo , Chen Xiang , Chen Lijuan , Wang Biqin , Peng Cheng , He Chunmei , Tang Minghai , Zhang Fan , Hu Jia , Li Rui , Zhao Xia , Wei Yuquan
Published: September 2008

A sensitive and reliable HPLC method with fluorescence detection based on the precolumn derivatization of glucosamine with 6‐aminoquinolyl–N–hydroxylsuccinimidyl carbamate (AQC) was established for the quantitative determination of glucosamine in rat plasma. The plasma protein was precipitated by acetonitrile, followed by vortex mixing and centrifugation. The supernatant was divided into the organic layer and aqueous layer by adding sodium chloride, and then the aqueous layer was derivatized with AQC in 0.2mborate buffer of pH 8.8 before the HPLC analysis. An amino acid analysis column (3.9 × 150 mm, 4 µm) was applied, with 140 mmsodium acetate buffer (pH = 5.25) and acetonitrile as mobile phase at a flow rate of 1 mL/min. A linear correlation coefficient of 0.9987 was calculated within the range of 0.1–30 µg/mL of the standard curve for glucosamine. The limit of detection was 30 ng/mL. The intra‐ and inter‐day precisions (as RSD) were less than 7.38 and 12.72%, respectively. The intra‐ and inter‐day accuracy ranged from 91.8 to 110.0%. Extraction recoveries of glucosamine in plasma were more than 90%. The validated method was successfully applied for the quantitative determination of glucosamine in rat plasma and evaluation for pharmacokinetic study of glucosamine. It was also possible to be applied for the quantitative determination of other compounds containing amino group in biological samples. Copyright © 2008 John Wiley & Sons, Ltd.
High‐performance liquid chromatography determination of nitrated polycyclic aromatic hydrocarbons by indirect fluorescence detection
Authors: Al‐Kindy Salma M. , Miller James N.
Published: September 2008

A high‐performance liquid chromatography (HPLC) method for the analysis of nitrated polcyclic aromatic hydrocarbons (NPAHs) is reported. NPAH mixtures were pre‐concentrated using solid‐phase extraction and well resolved on a C18 column. They were detected using an indirect method involving the quenching of the emission from the fluorophores 5,6,7,8‐tetrahydronaphthol (5,6,7,8‐THN‐1‐OH), 7‐amino‐4‐methyl coumarin (Coumarin 120, COU‐120) and 3‐hydroxy‐4‐(2‐hydroxy‐4‐sulfo‐1‐naphthylazo)2‐naphthalene carboxylic acid (Calcon carboxylic acid, CCA). Linear calibration curves were obtained in the range 1.1 × 10−9 to 1.1 × 10−8 mol/L. Using COU 120 as the fluorophore, the detection limit was 2.9 × 10−10 mol/L for 1‐nitronaphthalene and 2.1 × 10−11 mol/L for 2‐nitrofluorene. Recoveries of NPAHs from spiked tap water samples were between 88 and 100%. Copyright © 2008 John Wiley & Sons, Ltd.
Determination of serotonin, melatonin and metabolites in gastrointestinal tissue using high‐performance liquid chromatography with electrochemical detection
Authors: Chau Rosanna M. W. , Patel Bhavik Anil
Published: September 2008

In this paper we show a simple isocratic chromatographic method for the detection of serotonin and its precursors and metabolites from various types of gastrointestinal tissue. The paper measures for the first time basal measurements of melatonin in the gastrointestinal tract, which has recently been shown to be released from the musosal lining of the gut. Tissue samples were stable following sample preparation in either 0.1 m perchloric acid or mobile phase. Analysis was carried out using a mobile phase consisting of 10% acetonitrile–90% acetate acid buffer pH 4.0 with 2 mm decane–sulfonic acid sodium salt at a column temperature of 50°C. Electrochemical detection was utilized at a potential of +850 mV vs Ag/AgCl reference electrode at 10 µA full‐scale deflection. The detection limit of 5‐HT and melatonin was 241 and 308 nm respectively for a 10 µL injection. As a result of the method optimization, total analysis was reduced to 30 min. Accurate responses of the tissue samples following sample preparation could be obtained following a week after storage at –80°C. This method is capable of preparing and analysing of samples from all regions of the gastrointestinal tract. Copyright © 2008 John Wiley & Sons, Ltd.
Preparative isolation and purification of alkannin/shikonin derivatives from natural products by high‐speed counter‐current chromatography
Authors: Assimopoulou Andreana N. , Sturm Sonja , Stuppner Hermann , Papageorgiou Vassilios P.
Published: September 2008

Alkannin and shikonin (A/S) and their derivatives have been found in the roots of several Boraginaceous species and are also produced through plant tissue cultures. The chiral compounds A/S are potent pharmaceutical substances with a wide spectrum of biological and pharmacological activities like wound healing, antimicrobial, anti‐inflammatory, anticancer and antioxidant activity. High‐speed counter‐current chromatography (HSCCC) was applied for the first time to the separation, preparative isolation and purification of A/S and their esters from extracts of Alkanna tinctoria roots, as well as commercial samples. The constituents of HSCCC fractions and their purity were determined by high‐performance liquid chromatography–diode array detection–mass spectrometry (HPLC‐DAD‐MS), since DAD cannot detect oligomeric A/S derivatives that are present in most of the samples containing the respective monomeric derivatives. The purity of HSCCC fractions was compared with the one of fractions isolated by column chromatography (CC) using as stationary phases silica gel and Sephadex LH‐20. As shown, the purity of monomeric alkannin/shikonin was greater by HSCCC than CC separation of commercial A/S samples. Copyright © 2008 John Wiley & Sons, Ltd.
Liquid chromatographic method for the determination of sirolimus in blood using electrochemical detection
Authors: Mochizuki Nobuo , Suka Etsuko , Matsumoto Kunihiro , Akimoto Osamu , Ohno Keiko , Shimamura Tsuyoshi , Furukawa Hiroyuki , Todo Satoru , Kishino Satoshi
Published: September 2008

Therapeutic drug monitoring of sirolimus (rapamycin) is important for immunosuppressive therapy in solid organ transplantation. We have developed a simple and reliable method for determining blood concentrations of sirolimus using reversed‐phase HPLC with electrochemical detection (ECD). The E2potential was set at +900 mV. The potential of guard cell was set at +950 mV and that of the E1cell at +400 mV. The method was linear for a concentration range of 1–50 ng/mL when 0.5 mL blood was used. The correlation coefficients of all standard curves were greater than or equal to 0.999. The limit of detection was 0.5 ng/mL. The inter‐assay precision ranged from 3.22 to 7.48%, and the coefficient of variation (CV) for a quality control sample at 10 ng/mL was 7.48% with a bias of 8.4% from the target value. The intra‐assay precision ranged from 0.72 to 3.71%, and the CV for a quality control sample at 10 ng/mL was 0.72% with a bias of 6.8% from the target value. In a solid organ transplant recipient, trough concentrations of sirolimus were well within the analytic range of the HPLC/ECD procedure. The method described here is suitable for management of sirolimus therapy in solid organ transplantation. Copyright © 2008 John Wiley & Sons, Ltd.
Method validation for measurement of hair nicotine level in nonsmokers
Authors: Kim Sung Roul , Wipfli Heather , Avila‐Tang Erika , Samet Jonathan M. , Breysse Patrick N.
Published: September 2008

The development of strategies to address the growing worldwide burden of exposure to secondhand smoke (SHS) would be facilitated by sensitive and accurate methods for assessing SHS exposure. Hair provides a readily available matrix for assessing biomarkers of typical SHS exposure. We developed and applied an optimized analytical method using an isotope dilution gas chromatography–mass spectrometry (GC/MS) for hair nicotine measurement. The utility of this optimized method is illustrated by presenting data on SHS exposure of women and children from 31 countries. Using this isotope dilution method with spiked samples (3.3 ng/mg), we found that the greatest hair nicotine extraction efficiency was obtained with a 60 min shaking time. In the field study (n = 2400), a positive association was evident between hair nicotine concentrations from nonsmokers and higher numbers of cigarettes smoked per day in a household. Copyright © 2008 John Wiley & Sons, Ltd.
Development of an immunochromatographic assay for rapid detection of 1‐Aminohydantoin in urine specimens
Authors: Xu Yi Ping , Liu Li Qiang , Li Qiu Shen , Peng Chi Fang , Chen Wei , Xu Chuan Lai
Published: September 2008

A rapid immunochromatographic assay was developed and validated for detection of 1‐aminohydantoin (AHD) in urine specimens. Colloidal gold‐labeled polyclonal antibody specific to AHD derivative was used as the marker; based on the competitive reactivity theory, the metabolite of nitrofurantoin after derivatization with benzaldehyde would compete with carboxyphenyl AHD derivative‐conjugated ovalbumin. The test strip could efficaciously detect the novel analyte with a visual detection limit of 10 ng mL−1 and high specificity. The reliability of the assay was determined by testing 80 standard samples comparing with enzyme‐linked immunosorbent assay. The semi‐quantitative detection was accomplished in less than 15 min with low cost, especially for requirements of rapid and simple screening. This is the first publication of an immunochromatographic assay for detection of nitrofuran residues. Copyright © 2008 John Wiley & Sons, Ltd.
Anatomical development of urinary bladder during the fetal period
Authors: Sulak O. , Cankara N. , Malas M.A. , Koyuncu E. , Desdicioglu K.
Published: September 2008

The aim of this study was to determine the development, location, and size of the urinary bladder during the fetal period. The study was performed on 149 human fetuses between 9 and 40 weeks of gestation. The location of the urinary bladder with respect to transverse plane between the highest point of pubic symphysis and the sacral promontory and median sagittal plane was first determined. The dimensions and the angle of the urinary bladder were measured, and bladder shapes were determined. In addition, the edges of the vesical trigone were measured. There was no significant difference between sexes for any of the parameters (P > 0.05). A significant correlation was observed between all parameters and gestational age (P < 0.001). The urinary bladder was located above the transverse plane in most of the cases (83%) and in the median sagittal plane in every case. It was determined that the angle of bladder did not change and the mean value of the angle was 151° during the fetal period. Bladder was categorized into four different shapes (ellipsoid, round, cuboid, and triangular), and the most common shape found during the fetal period was cuboid. The vesical trigone was an isosceles triangle during the fetal period. The new data provided by this study will enable evaluation of the development of the fetal urinary bladder, and should be useful in several fields such as anatomy, fetopathology, medical imaging, obstetrics, and pediatric urology. Clin. Anat. 21:683–690, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis and Cytotoxic Evaluation of Novel Dimethyl [1,1′‐Biphenyl]‐2,2′‐dicarboxylates Bearing 1,3,4‐Thiadiazole Moieties
Authors: Kong Xiang‐Wen , Zhang Yi‐Hua , Wang Tao , Lai Yi‐Sheng , Peng Si‐Xun
Published: September 2008

In search of novel anticancer agents, two series of dimethyl [1,1′‐biphenyl]‐2,2′‐dicarboxylate derivatives, 8a–8k and 9a–9k, containing both methylenedioxy and 1,3,4‐thiadiazole moieties were designed and synthesized. Cytotoxicity of these compounds was evaluated in vitro against five human tumor cell lines, i.e., HepG2, KB, A549, K562, and MCF‐7. The results indicated that 8h, 8j, 8k, 9d, 9g, 9h, 9j, and 9k showed notable anticancer activities comparable to or stronger than that of 5‐fluorouracil, a canonical anticancer drug. Structure–activity relationships were also discussed based on the experimental data obtained.
Pentacyclic Triterpenoids from the Aerial Parts of Lantana camara and Their Nematicidal Activity
Authors: Begum Sabira , Zehra Syeda Qamar , Siddiqui Bina Shaheen , Fayyaz Shahina , Ramzan Musarrat
Published: September 2008

Two new olean‐12‐ene triterpenoids, camarolic acid (1) and lantrigloylic acid (2), have been isolated from the aerial parts of Lantana camara, along with ten known triterpenes, namely, camaric acid, lantanolic acid, lantanilic acid, pomolic acid, camarinic acid, lantoic acid, camarin, lantacin, camarinin, and ursolic acid. The new compounds have been characterized as 3,25‐epoxy‐3α‐hydroxy‐22β‐{[(S)‐3‐hydroxy‐2‐methylidenebutanoyl]oxy}olean‐12‐en‐28‐oic acid (1) and 3,25‐epoxy‐3α‐hydroxy‐22β‐[(3‐methylbut‐2‐enoyl)oxy]olea‐9(11),12‐dien‐28‐oic acid (2) through spectroscopic studies and a chemical transformation. Seven of the constituents, namely pomolic acid, lantanolic acid, lantoic acid, camarin, lantacin, camarinin, and ursolic acid, were tested for nematicidal activity against root‐knot nematode Meloidogyne incognita. Pomolic acid, lantanolic acid, and lantoic acid showed 100% mortality at 1 mg/ml concentration after 24 h, while camarin, lantacin, camarinin, and ursolic acid exhibited 100% mortality at this concentration after 48 h. These results are comparable to those obtained with the conventional nematicide furadan (100% mortality at 1 mg/ml concentration after 24 h).
The Influence of the Nitrogen Substitution in Three Cytisine Derivatives as Ligands for the Neuronal nAChRs: A Structural and Theoretical Study
Authors: Bombieri Gabriella , Meneghetti Fiorella , Artali Roberto , Tasso Bruno , Canu Boido Caterina , Sparatore Fabio
Published: September 2008

Three cytisine derivatives, (−)‐(7R,9S)‐1‐phenyl‐3‐(cytisin‐12‐yl)propan‐1‐one (1), (−)‐(7R,9S)‐1‐phenyl‐2‐(cytisin‐12‐yl)ethane (2), and (−)‐(7R,9S)‐1,2‐bis(cytisin‐12‐yl)ethane (3), with different electronic and steric features have been characterized by X‐ray analysis and theoretical calculations in order to evaluate how structural modulations affect the intrinsic binding affinity at the neuronal nicotinic receptors (nAChRs). The crystal structures of1and2, which display comparable affinities, are characterized by the same conformation of the cytisine moiety with different orientations of the substituent at N(2). In3, two independent molecules have the pyridinone rings diversely oriented. This compound has a lower affinity with respect to1and2, but it increases the expression of neuronal nAChRs. Compounds1, 2, and3retain the key prerequisite of the classical pharmacophoric models, with sp3‐N‐atomHBA distances close to the expected value, both in solid state and in solution (theoretical calculations), where, in contrast with the extended in the crystal state, acurled‐upconformation has been found, though maintaining theN‐substituent in equatorial position.
Poly(p‐phenylene ethynylene)s with Facially Amphiphilic Pendant Groups: Solvatochromism and Supramolecular Assemblies
Authors: Li Yan , Li Guangtao , Wang Xinyan , Lin Changxu , Zhang Yihe , Ju Yong
Published: September 2008

Novel functionalized poly(p‐phenylene ethynylene)s (PPEs) bearing facially amphiphilic cholic and deoxycholic acid units are synthesized by a Pd‐catalyzed Sonogashira cross‐coupling reaction. Some interesting properties, particularly their optical and self‐assembly characteristics, are unraveled. The PPEs that carry bile acid substituents exhibit remarkable solvatochromism in a wide range of solvent systems, and judicious choice of the solvents can adjust the size and morphology of the formed nanoscale supramolecular aggregates. The incorporation of these naturally occurring building blocks can also impart biocompatibility to the conjugated system and stimulate the growth of living cells.
Gold‐Film‐Catalysed Hydrosilylation of Alkynes by Microwave‐Assisted, Continuous‐Flow Organic Synthesis (MACOS)
Authors: Shore Gjergji , Organ Michael G.
Published: September 2008

Thin gold films on the surface of glass capillaries have proven to be highly active catalysts for the rapid hydrosilylation of alkynes that are flowed through the reactor while being heated by microwave irradiation. The films are able to be reused at least five times with no loss of activity and with no detectable levels of gold showing up in the hydrosilylated products.
Molecular Structure, Theoretical Calculation and Thermal Behavior of DAG(NTO)
Authors: CHANG Chun‐Ran , XU Kang‐Zhen , HUANG Jie , LI Meng , SONG Ji‐Rong , MA Hai‐Xia , ZHAO Feng‐Qi
Published: September 2008

A new compound, (NH2NH)2CNH2+C2N4O3H− [DAG(NTO)], was prepared by mixing the NaNTO·H2O aqueous solution and diaminogaunidine hydrochloride aqueous solution. Single crystals suitable for X‐ray measurement were obtained by recrystallization from water at room temperature. The crystal belongs to triclinic, space group P‐1 with crystal parameters of a=0.6732(3) nm, b=0.6745(3) nm, c=0.9840(4) nm, α=88.309(7)°, β=77.255(6)°, γ=86.520(7)°, V=4.349(3) nm3, Z=2, µ=0.144 mm−1, F(000) =228, and Dc=1.674 g/cm3. The theoretical investigation on DAG(NTO) as a structural unit was carried out by B3LYP, MP2 and HF methods with 6‐31+G(d) basis set. The apparent activation energy and pre‐exponential constant of the exothermic decomposition reaction of DAG(NTO) are 112.15 kJ·mol−1 and 109.603 s−1, respectively. The critical temperature of thermal explosion is 208.6 °C.
An Efficient Synthesis of Polysubstituted 1,3‐Enynes from (E)‐β‐Iodovinyl Sulfones and Terminal Alkynes
Authors: GU Xiao‐Xia , XIE Mei‐Hua , ZHAO Xin‐Yang , SUN Ying , ZHANG Wei , XIE Fa‐Dong , WANG Shao‐Wu
Published: September 2008

Sulfonyl‐substituted 1,3‐enynes were synthesized in moderate to high yields by Sonogashira coupling reaction of (E)‐β‐iodovinyl sulfones with terminal alkynes. The sulfonyl group was further transformed to various substitutents by desulfonylation coupling with Grignard reagents in the presence of NiCl2(PPh3)2.
Synthesis of 5‐Androstene‐3β,7α,17β‐triol and 5‐Androstene‐3β,7β,17β‐triol
Authors: LI He‐Ping , YU Peng , ZHANG Hong‐Jie , LIU Hong‐Min
Published: September 2008

Two important neuroactive steroids 5‐androstene‐3β,7α,17β‐triol (6) and 5‐androstene‐3β,7β,17β‐triol (7) were prepared through a microbial transformation of 5‐androstene‐3β,17β‐diol, which was the first report for the synthesis of compounds 6 and 7 through a microbial transformation with Mucor racemosu isolated by ourselves.
Molybdophosphoric Acid: An Efficient Keggin‐type Heteropoloacid Catalyst for the One‐pot Three‐Component Synthesis of 1‐Amidoalkyl‐2‐naphthols
Authors: JIANG Wen‐Qing , AN Li‐Tao , ZOU Jian‐Ping
Published: September 2008

A one‐pot three‐component reaction of 2‐naphthol, aldehyde, urea or amide catalyzed by the molybdophosphoric acid (heteropolyacid) to afford 1‐amidoalkyl‐2‐naphthols is described, which is high yield with simple work‐up.
Magnetic HP‐β‐CD Composite Nanoparticle: Synthesis, Characterization and Application as a Carrier of Doxorubicin in vitro
Authors: ZHANG Hua , PENG Ming‐Li , CUI Ya‐Li , CHEN Chao
Published: September 2008

Hydroxylpropyl‐β‐cyclodextrin (HP‐β‐CD) was introduced to the surface of magnetic nanoparticles in the presence of NH3·H2O to synthesize magnetic HP‐β‐CD composite nanoparticles, which were used as a carrier in magnetic targeted drug delivery. The composite nanoparticles were characterized by FTIR, ICP‐AES, TEM and VSM. The results showed that the iron content in the composite nanoparticles was 55.4%. The range of size is 10–20 nm and the magnetization is 59.9 emu/g. The capacity of composite nanoparticles for doxorubicin adsorption is 87.8 µg/mg after incubation for 72 h. The cumulative percentage of released doxorubicin in PBS buffer (pH=7.4) in 1, 4, 10 d were 35.5%, 49.3% and 76.5%, respectively. Thus, the magnetic HP‐β‐CD composite nanoparticles could be a potential carrier in the magnetic targeted drug delivery.
Hydrolysis of Adiponitrile in Near‐critical Water
Authors: DUAN Pei‐Gao , NIU Yan‐Lei , WANG Yuan‐Yuan , DAI Li‐Yi
Published: September 2008

Hydrolysis of adiponitrile (ADN) in near‐critical water was successfully conducted in a batch reactor. Influences of m(AND)/m(water) ratio, temperature, time, m(AND)/m(additive) ratio, kind of additive and pressure on the yield of each product were investigated. Five compounds resulting from the hydrolysis of ADN, including 5‐cyanovaleramide, adipamide, adipamic acid, adipic acid and trace of 5‐cyanovaleric acid, were detected by high performance liquid chromatography. The results showed that change of ADN concentration and temperature had significant influences on the yields of adipamide, adipamic acid and adipic acid; time was the significant factor for the yield of 5‐cyanovaleric acid; and the yield of 5‐cyanovaleramide was more dependent on the ADN concentration.
Synthesis of Aromatase Inhibitors and Dual Aromatase Steroid Sulfatase Inhibitors by Linking an Arylsulfamate Motif to 4‐(4H‐1,2,4‐triazol‐4‐ylamino)benzonitrile: SAR, Crystal Structures, in vitro and in vivo Activities
Authors: Bubert Christian , Woo L. W. Lawrence , Sutcliffe Oliver B. , Mahon Mary F. , Chander Surinder K. , Purohit Atul , Reed Michael J. , Potter Barry V. L.
Published: September 2008

4‐(((4‐Cyanophenyl)(4H‐1,2,4‐triazol‐4‐yl)amino)methyl)phenyl sulfamate (6 a) was the first dual aromatase–sulfatase inhibitor (DASI) reported. Several series of its derivatives with various linker systems between the steroid sulfatase (STS) and the aromatase inhibitory pharmacophores were synthesised and evaluated in JEG‐3 cells. The X‐ray crystal structures of the aromatase inhibitors, DASI precursors 42 d and 60, and DASI 43 h were determined. Nearly all derivatives show improved in vitro aromatase inhibition over 6 a but decreased STS inhibition. The best aromatase inhibitor is 42 e (IC50=0.26 nM) and the best DASI is 43 e (IC50 aromatase=0.45 nM, IC50 STS=1200 nM). SAR for aromatase inhibition shows that compounds containing an alkylene‐ and thioether‐based linker system are more potent than those that are ether‐, sulfone‐, or sulfonamide‐based, and that the length of the linker has a limited effect on aromatase inhibition beyond two methylene units. Compounds 43 d–f were studied in vivo (10 mg kg−1, single, p.o.). The most potent DASI is 43 e, which inhibited PMSG‐induced plasma estradiol levels by 92 % and liver STS activity by 98 % 3 h after dosing. These results further strengthen the concept of designing and developing DASIs for potential treatment of hormone‐related cancers.
Vitamin D receptor polymorphisms and the risk of cutaneous melanoma
Authors: Mocellin Simone , Nitti Donato
Published: September 2008

It has been hypothesized that polymorphisms in the vitamin D receptor (VDR) gene affect the risk of developing melanoma. However, results often are conflicting, and no meta‐analysis has been performed to date on published data. Six studies (cases, 2152; controls, 2410) that investigated the association between 5 VDR polymorphisms (TaqI, FokI, BsmI, EcoRV, and Cdx2) and the risk of melanoma were retrieved and analyzed. The model‐free approach was applied to meta‐analyze these molecular association studies. Available data suggested a significant association between the BsmI VDR polymorphism and melanoma risk (pooled odds ratio [OR], 1.30; 95% confidence interval [CI], 1.11‐1.53; P = .002; heterogeneity Cochran Q test, P > .1), and the population‐attributable risk was 9.2%. In contrast, the FokI polymorphism did not appear to be associated with such risk (OR, 1.09; 95% CI, 0.99‐1.21; P = .07; heterogeneity Cochran Q test, P > .1). For the TaqI and the EcoRV polymorphisms, significant between‐study heterogeneity did not support genotype data pooling. Only 1 study investigated the Cdx2 variant, and the findings were negative. Current evidence is in favor of an association between 1 VDR gene polymorphism (BsmI) and the risk of developing melanoma. The current findings prompt further investigation on this subject andindirectly support the hypothesis that sun exposure may have an antimelanoma effect through activation of the vitamin D system. Cancer 2008. © 2008 American Cancer Society.
Non‐locking tetrahedral finite element for surgical simulation
Authors: Joldes Grand Roman , Wittek Adam , Miller Karol
Published: September 2008

To obtain a very fast solution for finite element models used in surgical simulations, low‐order elements, such as the linear tetrahedron or the linear under‐integrated hexahedron, must be used. Automatic hexahedral mesh generation for complex geometries remains a challenging problem, and therefore tetrahedral or mixed meshes are often necessary. Unfortunately, the standard formulation of the linear tetrahedral element exhibits volumetric locking in case of almost incompressible materials. In this paper, we extend the average nodal pressure (ANP) tetrahedral element proposed by Bonet and Burton for a better handling of multiple material interfaces. The new formulation can handle multiple materials in a uniform way with better accuracy, while requiring only a small additional computation effort. We discuss some implementation issues and show how easy an existing Total Lagrangian Explicit Dynamics algorithm can be modified in order to support the new element formulation. The performance evaluation of the new element shows the clear improvement in reaction forces and displacements predictions compared with the ANP element in case of models consisting of multiple materials. Copyright © 2008 John Wiley & Sons, Ltd.
Cytomics and nanobioengineering
Authors: Pierzchalski Arkadiusz , Robitzki Andrea , Mittag Anja , Emmrich Frank , Sack Ulrich , O'Connor José‐Enrique , Bocsi József , Tárnok Attila
Published: September 2008

The finding that an individual's genome differs as much as by many million variants from that of the human reference assembly diminished the great enthusiasm that every disease could be predicted based on nucleotide polymorphisms. Even individual cells of an organ may be specifically equipped to perform specific tasks and that the information of individual cells in a cell system is key information to understand function or dysfunction. Therefore, cytomics received great attention during the last years as it allows to quantitatively and qualitatively analyzing great number of individual cells, cell constituents, and of their intracellular and functional interactions in a cellular system and also giving the concept of analysis of these data.

Exhaustive data extraction from multiparametric assays and multiple tests are the prerequisite for prediction of drug toxicity. Cytomics, as novel approach for unsupervised data analysis give a chance to find the most predictive parameters, which describe best the toxicity of a chemical. Cytomics is intrinsically connected to drug development and drug discovery.

Focused on small structures, nanobioengineering is the ideal partner of cytomics, the systems biological discipline for cell population analysis. Realizing the idea “from the molecule to the patient” develops and offers chemical compounds, proteins, and other biomolecules, cells as well as tissues as instruments and products for a wide variety of biotechnological and biomedical applications.

The integrative nanobioengineering combining different disciplines of nanotechnology will promote the development of innovative therapies and diagnostic methods. It can improve the precision of the measurements with focus on single cell analysis. By nanobioengineering and whole body imaging techniques, cytomics covers the field from molecules through bacterial cells, eukaryotic tissues, and organs to small animal live analysis. Toxicological testing and medical drug development are currently strongly broadening. It harbors the promise to substantially impact on various fields of biomedicine, drug discovery, and predictive medicine.

As the number of scientific data is rising exponentially, new data analysis tools and strategies like cytomics and nanobioengineering take a lead and get closer to application. Bionanoengineering may strongly support the quantitative data supply, thus strengthening the rational for cytomics approach. © 2008 Clinical Cytometry Society

How to cite this article: Pierzchalski A, Robitzki A, Mittag A, Emmrich F, Sack U, O'Connor J‐E, Bocsi J, Tárnok A. Cytomics and nanobioengineering. Cytometry Part B 2008; 72B: 416–426.
Symbol detection in spatial multiplexing system using particle swarm optimization meta‐heuristics
Authors: Khan Adnan Ahmed , Bashir Sajid , Naeem Muhammad , Shah Syed Ismail , Li Xiaodong
Published: September 2008

Symbol detection in multi‐input multi‐output (MIMO) communication systems using different particle swarm optimization (PSO) algorithms is presented. This approach is particularly attractive as particle swarm intelligence is well suited for real‐time applications, where low complexity and fast convergence is of absolute importance. While an optimal maximum likelihood (ML) detection using an exhaustive search method is prohibitively complex, PSO‐assisted MIMO detection algorithms give near‐optimal bit error rate (BER) performance with a significant reduction in ML complexity. The simulation results show that the proposed detectors give an acceptable BER performance and computational complexity trade‐off in comparison with ML detection. These detection techniques show promising results for MIMO systems using high‐order modulation schemes and more transmitting antennas where conventional ML detector becomes computationally non‐practical to use. Hence, the proposed detectors are best suited for high‐speed multi‐antenna wireless communication systems. Copyright © 2008 John Wiley & Sons, Ltd.
Organizational effects of maternal testosterone on reproductive behavior of adult house sparrows
Authors: Partecke Jesko , Schwabl Hubert
Published: September 2008

Despite the well‐known, long‐term, organizational actions of sex steroids on phenotypic differences between the sexes, studies of maternal steroids in the vertebrate egg have mainly focused on effects seen in early life. Long‐term organizational effects of yolk hormones on adult behavior and the underlying mechanisms that generate them have been largely ignored. Using an experiment in which hand‐reared house sparrows (Passer domesticus) from testosterone‐ or control‐treated eggs were kept under identical conditions, we show that testosterone treatment in the egg increased the frequency of aggressive, dominance, and sexual behavior of 1‐year‐old, reproductively competent house sparrows. We also show that circulating plasma levels of progesterone, testosterone, 5α‐dihydrotestosterone, and 17β‐estradiol did not differ between treatment groups. Thus, a simple change in adult gonadal hormone secretion is not the primary physiological cause of long‐term effects of maternal steroids on adult behavior. Rather, differences in adult behavior caused by exposure to yolk testosterone during embryonic development are likely generated by organizational modifications of brain function. Furthermore, our data provide evidence that hormone‐mediated maternal effects are an epigenetic mechanism causing intra‐sexual variation in adult behavioral phenotype. © 2008 Wiley Periodicals, Inc. Develop Neurobiol 2008
A novel role for anosmin‐1 in the adhesion and migration of oligodendrocyte precursors
Authors: Bribián Ana , Esteban Pedro F. , Clemente Diego , Soussi‐Yanicostas Nadia , Thomas Jean‐Léon , Zalc Bernard , de Castro Fernando
Published: September 2008

At embryonic stages of development, oligodendrocyte precursors (OPCs) generated in the preoptic area colonize the entire optic nerve (ON). Different factors controlling migration of ON OPCs have been identified, including secreted growth factors, morphogens and guidance cues, as well as cell adhesion molecules. We have shown previously that the soluble form of the extracellular matrix (ECM) protein anosmin‐1, impairs OPC migration induced by FGF‐2. In the present work, we show that anosmin‐1 is expressed by both migrating OPCs and axons of the retinal ganglion cells in the embryonic ON. In vitro, we observe that OPC migration is strongly impaired by contact with anosmin‐1 when used as a substrate and, in contrast to previous results, this effect is independent of FGF‐2/FGFR1 signaling. We also show that OPCs preferentially adhere to anosmin‐1 when compared with other ECM molecules used as substrates, and that when the endogenous anosmin‐1 expressed by OPCs is blocked, OPC adhesion to all the different substrates (including anosmin‐1), is significantly reduced. This novel effect of anosmin‐1 on cell adhesion is also independent of FGF‐2/FGFR1. We finally demonstrate that the blockade of the endogenous anosmin‐1 expressed by OPCs impairs their migration. Our data suggest that the endogenous anosmin‐1 expressed by OPCs is necessary for the correct adhesion of these cells to the different components of the ECM (including anosmin‐1 itself), contributing to the migration of these cells. © 2008 Wiley Periodicals, Inc. Develop Neurobiol 2008
Functional differentiation of a clone resembling embryonic cortical interneuron progenitors
Authors: Li Hedong , Han Yu R. , Bi Caixia , Davila Jonathan , Goff Loyal A. , Thompson Kevin , Swerdel Mavis , Camarillo Cynthia , Ricupero Christopher L. , Hart Ronald P. , Plummer Mark R. , Grumet Martin
Published: September 2008

We have generated clones (L2.3 and RG3.6) of neural progenitors with radial glial properties from rat E14.5 cortex that differentiate into astrocytes, neurons, and oligodendrocytes. Here, we describe a different clone (L2.2) that gives rise exclusively to neurons, but not to glia. Neuronal differentiation of L2.2 cells was inhibited by bone morphogenic protein 2 (BMP2) and enhanced by Sonic Hedgehog (SHH) similar to cortical interneuron progenitors. Compared with L2.3, differentiating L2.2 cells expressed significantly higher levels of mRNAs for glutamate decarboxylases (GADs), DLX transcription factors, calretinin, calbindin, neuropeptide Y (NPY), and somatostatin. Increased levels of DLX‐2, GADs, and calretinin proteins were confirmed upon differentiation. L2.2 cells differentiated into neurons that fired action potentials in vitro, and their electrophysiological differentiation was accelerated and more complete when cocultured with developing astroglial cells but not with conditioned medium from these cells. The combined results suggest that clone L2.2 resembles GABAergic interneuron progenitors in the developing forebrain. © 2008 Wiley Periodicals, Inc. Develop Neurobiol 2008
A stochastic residential load model and its application to the unified loss theory
Authors: Raisz David , Dán András
Published: September 2008

This paper presents a residential load model which is a combination of a “bottom‐up” (synthetical) and a “top‐down” (analytical) model. Using the bottom‐up approach a household load is composed of several “elementary appliances” that can be identified based on household current measurements. Then a “top‐down” method ensures that the sum of the household currents equals the measured transformer current.

Latter condition needs to be fulfilled in order to apply the model in the framework of a unified loss theory, a measurement based computation method for the determination of network losses. This approach enables to treat jointly (and yet separately) various components of losses such as reactive current, asymmetry and harmonic currents and the time‐variance of those, thus making it possible to evaluate and compare the order of magnitude of the loss components and in consequence the efficiency of different loss‐reduction investments. Copyright © 2008 John Wiley & Sons, Ltd.
On the iterative mitigation of clipping noise for COFDM transmissions
Authors: Déjardin Romain , Colas Maxime , Gelle Guillaume
Published: September 2008

Large peak‐to‐average power ratio (PAPR) of multicarrier communication systems is a widely discussed topic in the literature and remains the major drawback of the orthogonal frequency division multiplexing (OFDM) modulation. Deliberate amplitude clipping has been found as a suitable way to reduce output signal peaks at the transmitter side. Unfortunately, it also causes numerous degradations. In this paper, we propose a study of nonlinearities led by the clipping process and a comparison of iterative receivers derived from the turbo‐principle and devoted to the system performance restoration under severe clipping ratio (CR) constraint. Copyright © 2008 John Wiley & Sons, Ltd.
Stabilized finite element formulation for incompressible flow on distorted meshes
Authors: Förster Ch. , Wall W. A. , Ramm E.
Published: September 2008

Flow computations frequently require unfavourably meshes, as for example highly stretched elements in regions of boundary layers or distorted elements in deforming arbitrary Lagrangian Eulerian meshes. Thus, the performance of a flow solver on such meshes is of great interest. The behaviour of finite elements with residual‐based stabilization for incompressible Newtonian flow on distorted meshes is considered here.

We investigate the influence of the stabilization terms on the results obtained on distorted meshes by a number of numerical studies. The effect of different element length definitions within the elemental stabilization parameter is considered. Further, different variants of residual‐based stabilization are compared indicating that dropping the second derivatives from the stabilization operator, i.e. using a streamline upwind Petrov–Galerkin type of formulation yields better results in a variety of cases. A comparison of the performance of linear and quadratic elements reveals further that the inconsistency of linear elements equipped with residual‐based stabilization introduces significant errors on distorted meshes, while quadratic elements are almost unaffected by moderate mesh distortion. Copyright © 2008 John Wiley & Sons, Ltd.
The predictive value of temporally disaggregated volatility: evidence from index futures markets
Authors: Taylor Nicholas
Published: September 2008

This paper examines the benefits to forecasters of decomposing close‐to‐close return volatility into close‐to‐open (nighttime) and open‐to‐close (daytime) return volatility. Specifically, we consider whether close‐to‐close volatility forecasts based on the former type of (temporally aggregated) data are less accurate than corresponding forecasts based on the latter (temporally disaggregated) data. Results obtained from seven different US index futures markets reveal that significant increases in forecast accuracy are possible when using temporally disaggregated volatility data. This result is primarily driven by the fact that forecasts based on such data can be updated as more information becomes available (e.g., information flow from the preceding close‐to‐open/nighttime trading session). Finally, we demonstrate that the main findings of this paper are robust to the index futures market considered, the way in which return volatility is constructed, and the method used to assess forecast accuracy. Copyright © 2008 John Wiley & Sons, Ltd.
Lovastatin induces the formation of abnormal myelin‐like membrane sheets in primary oligodendrocytes
Authors: Maier Olaf , De Jonge Jenny , Nomden Anita , Hoekstra Dick , Baron Wia
Published: September 2008

Statins, well‐known inhibitors of cholesterol synthesis and protein isoprenylation, have been proposed as therapeutic drugs for multiple sclerosis (MS). As lovastatin and simvastatin, which are currently tested for their use in MS, can cross the blood‐brain barrier, they may affect cellular processes in the central nervous system. This is especially relevant with respect to remyelination as a proposed additional treatment for MS, because cholesterol is a major component of myelin. Here, we show that primary oligodendrocytes, treated with lovastatin, form extensive membrane sheets, which contain galactosphingolipids. However, these membrane sheets are devoid of the major myelin proteins, myelin basic protein (MBP) and proteolipid protein (PLP). Reduced MBP protein expression was confirmed by SDS‐PAGE and Western blotting, and in situ hybridization experiments revealed that lovastatin blocks MBP mRNA transport into oligodendrocyte processes. In contrast, PLP expression was only mildly affected by lovastatin. However, lovastatin treatment resulted in intracellular accumulation of PLP and prevented its translocation to the cell surface. Interestingly, another inhibitor of cholesterol synthesis (ro48‐8071), which does not interfere with isoprenylation, had a similar effect on the localization of PLP, but it did not affect MBP expression and localization. These results suggest that lovastatin affects PLP transport predominantly by the inhibition of cholesterol synthesis, whereas reduced MBP expression is caused by impaired isoprenylation. Based on these results we recommend to carefully monitor the effect of statins on myelination prior to their use in demyelinating diseases. © 2008 Wiley‐Liss, Inc.
Leptin induces migration and invasion of glioma cells through MMP‐13 production
Authors: Yeh Wei‐Lan , Lu Dah‐Yuu , Lee Ming‐Jen , Fu Wen‐Mei
Published: September 2008

Leptin, the product of the obese gene, plays an important role in the regulation of body weight by coordinating metabolism, feeding behavior, energy balance, and neuroendocrine responses. However, regulation of leptin gene expression in the central nervous system is different from that in the adipocytes. In addition, leptin has been found in many tumor cell lines and has been shown to have mitogenic and angiogenic activity in a number of cell types. Glioma is the most common primary adult brain tumor with poor prognosis because of the spreading of tumor cell to the other regions of brain easily. Here we found that malignant C6 glioma cells expressed more leptin and leptin receptors than nonmalignant astrocytes. Furthermore, it was found that exogenous application of leptin enhanced the migration and invasion of C6 glioma cells. In addition, we found that the expression of matrix metalloproteinase‐13 (MMP‐13) but not of MMP‐2 and MMP‐9 was increased in response to leptin stimulation. The leptin‐induced increase of cell migration and invasion was antagonized by MMP‐13 neutralizing antibody or silencing MMP‐13. The up‐regulation of MMP‐13 induced by leptin was mainly through p38 MAP kinase and NF‐κB pathway. In addition, migration‐prone sublines demonstrate that cells with increasing migration ability had more expression of MMP‐13 and leptin. Taken together, these results indicate that leptin enhanced migration and invasion of C6 glioma cells through the increase of MMP‐13 production. © 2008 Wiley‐Liss, Inc.
Rocks are expressed in brain tumors and are required for glioma‐cell migration on myelinated axons
Authors: Oellers Patrick , Schröer Uwe , Senner Volker , Paulus Werner , Thanos Solon
Published: September 2008

The interactions between migrating glioma cells and myelinated fiber tracts are poorly understood. We identified that C6 glioma cells can migrate along myelinated chicken retinal axons in a novel coculture, thereby expressing small GTPases of the Rho family and serine/threonine Rho‐associated kinases (ROCKs). We found that the ROCK1 isoform is also highly expressed in native human high‐grade gliomas. Glioma cells migrated faster in vitro along myelinated axons than on laminin‐1, with the former but not the latter being specifically and reversibly blocked by the ROCK inhibitor Y27632. These data suggest that the mechanisms underlying the migration of glioma cells on myelinated axons differ from those underlying the migration on extracellular matrix molecules such as laminin‐1. © 2008 Wiley‐Liss, Inc.
Upregulation of p21Cip1 in activated glial cells
Authors: Tusell Josep Maria , Ejarque‐Ortiz Aroa , Mancera Pilar , Solà Carme , Saura Josep , Serratosa Joan
Published: September 2008

The cdk inhibitor p21Cip1, also named p21Cip1/Waf1, is intimately involved in coupling growth arrest to cellular differentiation in several cell types. p21Cip1 is a multifunctional protein that might regulate cell‐cycle progression at different levels. In a recent study, we found no differences in the rate of proliferation between glial cells from wild‐type and p21Cip1−/− mice. In the present study, we examined differences in glial activation between glial cells from wild‐type and p21Cip1−/− mice, using mixed glial cultures, microglia‐enriched cultures, and astrocyte‐enriched cultures. We compared the effect of lipopolysaccharide and two forms (oligomeric and fibrillar) of the 1‐42 β‐amyloid peptide on glial activation. We observed an attenuation of nuclear translocation of the nuclear factor kappa‐B in p21Cip1−/− glial cells, when compared with glial cells from wild‐type mice. In contrast, tumor necrosis factor‐α release was enhanced in p21Cip1−/−microglial cells. In addition glial activation induced by lipopolysaccharide and the fibrillar form of the 1‐42 β‐amyloid peptide upregulated p21Cip1. Our results support a role for p21Cip1 in the activation of glial cells, particularly in microglia. © 2008 Wiley‐Liss, Inc.