bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and Magnetism of a New Dodecanuclear CuII Complex with Acetato and Imidazolato Bridges, Formed by Oxidation of the Chelating Ligand 1,1,7,7‐Tetrakis(imidazol‐2‐yl)‐2,6‐diazaheptane
Authors: Song Yufei , Gamez Patrick , Stassen Arno F. , Lutz Martin , Spek Anthony L. , Reedijk Jan
Published: November 2003

A novel dodecanuclear copper(II) complex [Cu12(tidhd)4(MeOH)8(CH3COO)8](MeOH)0.8 (Htidhd = 1,1,7,7‐tetrakis(imidazol‐2‐yl)‐2,6‐diaza‐1,6‐heptadiene) with imidazolato and acetato bridging ligands was synthesized by reaction of polyimidazole 1,1,7,7‐tetrakis(imidazol‐2‐yl)‐2,6‐diazaheptane (Htidahp) with copper acetate in a methanol solution. The complex crystallized in the triclinic space group P$\bar 1$
with a = 9.1204(1), b = 13.5139(2), c = 27.6925(5), α = 76.8006(6)°, β = 82.8066(7)°, γ = 76.4594(9)°, Z = 1. Structure analysis shows that the unit cell of the complex contains twelve copper(II) ions in three different coordination environments. The complex is centrosymmetric and the two hexanuclear units are linked by two μ3‐acetate anions [the Cu1−Cu1a distance is 3.5507(7) Å]. The magnetic superexchange interaction via the bridging imidazolate ligand appears to be the most important magnetic interaction in this complex. Magnetic susceptibility measurement vs. temperature in the range of 6−300 K were fitted to the parameters g = 2.05, Ja = −32.0 cm−1 and Jb = −5.45 cm−1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Optimization by full factorial design of the emulsifying properties of ethanol insoluble fraction from rapeseed lecithin
Authors: Sosada Marian , Pasker Beata , Gabzdyl Renata
Published: November 2003

Rapeseed lecithin ethanol insoluble fraction (LEIF), was acetylated and optimum conditions for improving LEIF emulsifying property were determined. The effects of reaction time, pyridine amount and temperature on phosphatidyl ethanolamine conversion degree (PECD) and emulsion stability index (ESI) have been described in the form of regression equations. A full factorial design method was used. Regression equations for the maximum value of response functions and computation results were calculated and compared with those obtained in control experiments. Acetylation of rapeseed LEIF with the use of calculated optimal parameters led to 35% and 60% increments in PECD and ESI, respectively.
The fatty acid composition of small and large naturally occurring milk fat globules
Authors: Briard Valérie , Leconte Nadine , Michel Françoise , Michalski Marie‐Caroline
Published: November 2003

Native milk fat globules of various mean diameters, ranging from d43 = 1.5 to 7.3 μm, were obtained using microfiltration of raw whole milk acquired in winter and spring. After total lipid extraction, fatty acid composition was characterized by methyl and butyl ester analysis using gas chromatography. The oleic and linoleic acid content of milk obtained in winter increased with fat globule size, whereas myristic and palmitic acid decreased. There was significantly more lauric, myristic and palmitoleic acid, and less stearic acid in small fat globules compared to large fat globules in milk obtained in both winter and spring. The relative content of oleic and linoleic acids were found to depend on fat globule size and season. Results are interpreted on the basis of the relative content of milk fat globule membrane depending on fat globule size, and on consequences of compositional variations on milk fat globule melting behavior.
Determination of fatty acids and some undesirable fatty acid isomers in selected Turkish margarines
Authors: Çetin Mehmet , Yıldırım Ayhan , Şahin A. Metin
Published: November 2003

The fatty acid composition and total trans fatty acid content in 10 margarines produced in Turkey were determined by capillary gas chromatography and Fourier transform‐infrared spectroscopy (FT‐IR) spectroscopy. The fatty acid composition ranged as follows: saturated fatty acids, C16:0 (palmitic) 11.3 to 31.8% and C18:0 (stearic) 5.7 to 8.7%, monounsaturated fatty acids, C18:1 (oleic) 21.8 to 35.7% and C18:1 trans isomers 0.4 to 27.4%, polyunsaturated fatty acid, C18:2 linoleic acid 5.2 to 40.2%. Some positional isomers of C18:1 as cis‐11‐octadecenoic acid varied from 0.7 to 4.6% and cis‐13 trace to 2.4%. The total trans fatty acid contents were between 0.9 and 32.0% when measured with capillary gas chromatography and between 0 and 30.2% with FT‐IR spectroscopy. Some of the margarines analyzed contained trace amount of trans fatty acids which could not be detected by FT‐IR spectroscopy.
Platelet activating factor — a molecular link between atherosclerosis theories
Authors: Demopoulos Constantinos A. , Karantonis Haralabos C. , Antonopoulou Smaragdi
Published: November 2003

The most common causes of death in westernized societies remain heart disease and stroke. For this reason the prevention of atherosclerosis is a major objective of modern medicine. Platelet‐Activating Factor (PAF, 1‐O‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine) is a crucial mediator in the inflammatory response. PAF is synthesized by several types of cells, including platelets, monocytes, macrophages, foam cells and endothelial cells upon activation. Many experimental data reveal that atherogenic activities of oxidized LDLs can be attributed to PAF and PAF‐like lipids, which render these molecules the initiators of atherosclerosis.

Several theories have been formulated for atherosclerosis. The purpose of this review is to highlight the significance of PAF and PAF‐like lipids during the early stages of atherosclerosis. Secondly to link the biological action of PAF molecules to the most accepted, current hypotheses of atherosclerosis. Thirdly to propose a mechanism for the initiation and propagation of atherosclerosis by PAF.

The mechanism we propose offers a new biochemical approach and may help to explains the beneficial effects of the Mediterranean diet. Mediterranean foods contain a significant number of lipid‐like components with anti‐PAF action in vitro. The comsumption of PAF antagonist from Mediterranian foods inhibits the development of atherosclerosis. Such observations suggest that our hypothesis serves as a sound basis for further research.
Asymmetric Synthesis of (S)‐(−)‐Acromelobic Acid
Authors: Wild Nicole , Groth Ulrich
Published: November 2003

(S)‐(−)‐Acromelobic acid (1) was synthesized in nine steps in enantiomerically pure form from citrazinic acid (4) in an overall yield of 21%. The key steps of this synthesis are the introduction of the amino function by the bis(lactim) ether method and the introduction of the acid function by Stille coupling. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Heterocyclization Reaction of α‐Imino Carbonyl Compounds − Derivatives of 2,5‐Dihydro‐1H‐imidazole Nitroxides
Authors: Roshchupkina Galina A. , Pervukhina Natalie V. , Rybalova Tatjana V. , Gatilov Yuri V. , Burdukov Alexey B. , Reznikov Vladimir A.
Published: November 2003

α‐Imino carbonyl compounds − derivatives of 3‐imidazoline nitroxides − were found to undergo heterocyclization reactions, yielding oxazole and 1,3,5‐triazine derivatives. The most probable course of the reaction was suggested by the radioactive label method. The structures of the heterocycles synthesized were verified by X‐ray analysis of the mixed‐ligand complexes with copper hexafluoroacetylacetonate. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Structural Characterization of meso‐Thienyl Core‐Modified Porphyrins
Authors: Gupta Iti , Hung C.‐Hsiung , Ravikanth Mangalampalli
Published: November 2003

A series of meso‐thienyl‐substituted porphyrins with different porphyrin cores such as N3S, N2S2 and N3O were synthesized and characterized. The thienyl groups at the meso‐carbon atoms change the electronic properties of the porphyrin ring. The X‐ray structure solved for the N2S2 porphyrin with four meso‐thienyl groups showed supramolecular assembly formation in the solid state due to C−H···N hydrogen bonding between the CH group of the meso‐thienyl group of one porphyrin ring with the pyrrole N atom of another porphyrin ring. The X‐ray analysis of the N3S porphyrin with two meso‐thienyl groups and two meso‐aryl groups did not show any supramolecular assembly formation in the solid state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Acid Rearrangement of Secoiridoids Related to Oleuropein and Secologanin
Authors: Bianco Armandodoriano , Jensen Soren Rosendal , Olesen Jens , Passacantilli Pietro , Ramunno Alessia
Published: November 2003

Acid treatment of an iridoid glycoside results in the cleavage of the acetal bond between the sugar unit and the monoterpenoid aglycon. Iridoids possessing non‐conjugated enol ether systems, however, undergo the hydration of the iridoid enol ether functionality in acid medium, as well as the hydrolysis of the bond. We examined the acid rearrangement of secoiridoids such as oleuropein (1) and secologanin (2) and their reduction products oleuropeinol (3) and secologaninol (4), to examine whether similar behaviour also occurs in this case. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structure and Reactivity of 3,3‐Disubstituted 1‐(5‐Nitro‐2,1‐benzisothiazol‐3‐yl)triazenes
Authors: Přikryl Josef , Lyčka Antonín , Bertolasi Valerio , Holčapek Michal , Macháček Vladimír
Published: November 2003

The reaction between 5‐nitro‐2,1‐benzisothiazole‐3‐diazonium species and N‐substituted anilines produces the 1‐(5‐nitro‐2,1‐benzisothiazol‐3‐yl)‐3,3‐disubstituted triazenes 1. These triazenes are highly stable, and even in strongly acidic medium (0.5 mol⋅L−1 H2SO4) they are only slowly decomposed back to the diazonium ion and substituted anilinium ion (for the N‐ethyl derivative in 0.5 mol·L−1 H2SO4 at 25 °C, t1/2 ≈︁ 7 h). A series of six triazenes were characterised by their 1H and 13C NMR spectra and mass spectra. Two of the triazenes were also identified by X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
From a Calix[4]arene to a Hexameric Supracycle
Authors: Dyker Gerald , Mastalerz Michael , Merz Klaus
Published: November 2003

We investigated a simple and economic method for the selective O‐arylation of calix[4]arenes with N‐heteroarenes with temperature control under neat conditions. The resulting multidentate ligands are potential building blocks for transition metal complexes or supramolecular aggregates: dipyridoxycalixarene 3b, together with palladium(II) chloride, produced a complex with a fascinating crystal structure, six molecules self‐assembling into hexameric supracycles with an outer diameter of roughly 30 Å and an inner diameter of roughly 7 Å, containing six dichloromethane molecules. The supracycles themselves are organised into hexagonal assembled tubes along the c axis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Reactions between Benzocyclobutenone Tricarbonylchromium Complexes and Lithium Dialkylphosphides: A New Route to Isochromanones
Authors: Schnebel Matthias , Weidner Ingo , Wartchow Rudolf , Butenschön Holger
Published: November 2003

The reaction between rac‐(benzocyclobutenone)tricarbonylchromium (rac‐1) and lithium diisopropylphosphide (LDP) or lithium di‐tert‐butylphosphide, unlike its reaction with lithium diisopropylamide (LDA), results in a distal ring‐opening, with formation of acylphosphane derivatives. The tricarbonylchromium complex rac‐6 of 2‐methylbenzoyldiisopropylphosphane has been structurally characterized. The reaction proceeds through the corresponding benzylic anion intermediate, which was shown to react with ketones or aldehydes with formation of isochromanone derivatives. This indicates that a dialkylphosphide is a much better leaving group than an amide. The availability of 1 in enantiomerically pure form inspired an inspection of the diastereoselectivity of the cyclization with aldehydes. It was found that the reaction between the intermediate and benzaldehyde took place with complete diastereoselectivity, thus establishing a route to enantiomerically pure 3‐phenylisochromanone. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A Concise Total Synthesis of (+)‐Heliotridine
Authors: Pisaneschi Federica , Cordero Franca M. , Brandi Alberto
Published: November 2003

A practical synthesis of the necine base (+)‐heliotridine (1) is reported here. The present total synthesis is based on the highly selective 1,3‐dipolar cycloaddition of (S)‐3‐tert‐butoxypyrroline N‐oxide (2) to the commercially available ethyl 4‐bromocrotonate, followed by a suitable elaboration of the adduct. The synthesis gives a 17% overall yield from nitrone 2. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
An Efficient Asymmetric Synthesis of Tarchonanthuslactone
Authors: Enders Dieter , Steinbusch Daniel
Published: November 2003

An efficient and straightforward ten‐step asymmetric synthesis of the polyketide tarchonanthuslactone (1) in good overall yield (21% starting from chloro lactone 5) and with excellent diastereomeric and enantiomeric excesses (de, ee ⩾ 96%) is described. The new synthetic route is based on the α,β‐unsaturated δ‐lactone building block 5, available in enantiopure form (ee > 99%) through an enzymatic procedure, and its conversion into methyl ketone 11 by an Umpolung strategy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Design of Cyclopentaisoxazoline Amino Acids as Conformationally Constrained Agonists at Glutamate Receptors
Authors: Conti Paola , De Amici Marco , Grazioso Giovanni , Roda Gabriella , Stensbøl Tine B. , Bräuner‐Osborne Hans , Madsen Ulf , Toma Lucio , De Micheli Carlo
Published: November 2003

We have prepared four isomeric 3‐hydroxycyclopentaisoxazoline amino acids 12−15, which represent analogues of glutamic acid having restricted conformations, through a strategy based on the 1,3‐dipolar cycloaddition of bromonitrile oxide to a suitably protected 1‐aminocyclopent‐2‐enecarboxylic acid. These target compounds proved to be inactive when assayed at ionotropic and metabotropic glutamate receptors, except for 12 which is an agonist primarily at mGluR5 (EC50 = 79 μM), but is less active at mGluR2 and only marginally active at mGluR1. The biological data are accounted for through comparison of the conformational profiles of the test compounds with that of reference agonists, i.e., N‐methyl‐D‐aspartate (NMDA, 2), and 1‐aminocyclopentane‐1,3‐dicarboxylic acids [trans‐ACPD, 10; cis‐ACPD, 11]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Use of Rhodium N‐Heterocyclic Carbene Complexes in Catalytic Cyclization and Hydrosilylation of 1,6‐Enynes to 2‐Methyl‐1‐silylmethylidene‐2‐cyclopentane
Authors: Park Kang Hyun , Kim So Yeon , Son Seung Uk , Chung Young Keun
Published: November 2003

The neutral rhodium complexes [RhCl(NHC)(cod)] (NHC = N‐heterocyclic carbene) catalyzed the hydrosilylation/cyclization of 1,6‐enynes and HSiR3 (R3 = Et3 and PhMe2) to form 2‐methyl‐1‐silylmethylidene‐2‐cyclopentanes in high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Development of Thiourea‐Based Ligands for the Palladium‐Catalyzed Bis(methoxycarbonylation) of Terminal Olefins
Authors: Dai Mingji , Wang Cuihua , Dong Guangbin , Xiang Jing , Luo Tuoping , Liang Bo , Chen Jiahua , Yang Zhen
Published: November 2003

Thiourea‐based ligands were evaluated for the palladium‐catalyzed bis(methoxycarbonylation) of terminal olefins. The usefulness of these ligands for this reaction is demonstrated by their stability to oxidizing agents, and their superiority in preventing palladium precipitation and double‐bond isomerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Cover Picture: Use of Rhodium N‐Heterocyclic Carbene Complexes in Catalytic Cyclization and Hydrosilylation of 1,6‐Enynes to 2‐Methyl‐1‐silylmethylidene‐2‐cyclopentane (Eur. J. Org. Chem. 22/2003)
Authors: Park Kang Hyun , Kim So Yeon , Son Seung Uk , Chung Young Keun
Published: November 2003

The cover picture shows a neutral rhodium complex [Rh(NHC)(cod)Cl] (NHC = N‐heterocyclic carbene) catalyzing the hydrosilylation/cyclization of 1,6‐enynes and HSiR3 (R3 = Et3 and PhMe2) to form 2‐methyl‐1‐silylmethylidene‐2‐cyclopentanes in high yields. Details are described in the Short Communication by Y. K. Chung et al. on p. 4341 ff.
Fabrication of porous polymer monoliths covalently attached to the walls of channels in plastic microdevices
Authors: Stachowiak Timothy B. , Rohr Thomas , Hilder Emily F. , Peterson Dominic S. , Yi Mingqiang , Svec Frantisek , Fréchet Jean M. J.
Published: November 2003

UV‐initiated grafting of plastic tubes and microfluidic chips with ethylene diacrylate followed by the preparation of porous polymer monoliths has been studied. The first step affords a thin grafted layer of polymer with a multiplicity of pendent double bonds that are then used in the second step for covalent attachment of the monolith to the wall. As clearly seen on scanning electron micrographs, this procedure prevents the formation of voids at the monolith‐channel interface a problem that has always plagued approaches involving bulk polymerization in nontreated channels due to the shrinkage of the monolith during the polymerization process and its lack of compatibility with the material of the device. Irradiation with UV light through a photomask allows precise patterning specifying both the area subjected to surface modification and the location of the monolith within specific areas of the device.
Monolithic valves for microfluidic chips based on thermoresponsive polymer gels
Authors: Luo Quanzhou , Mutlu Senol , Gianchandani Yogesh B. , Svec Frantisek , Fréchet Jean M. J.
Published: November 2003

The direct preparation of thermoresponsive monolithic copolymers by photopatterning of a liquid phase consisting of an aqueous solution of N‐isopropylacrylamide, N‐ethylacrylamide, N,N'‐methylenebisacrylamide, and 4,4'‐azobis(4‐cyanovaleric acid) has been studied and the products used as valves within the channels of microfluidic devices. The volume change associated with the polymer phase transition at its lower critical solution temperature (LCST) leads to the rapid swelling and the deswelling of the 2.5% cross‐linked monolithic gel thus enabling the polymer to close or open the channel and to function as a nonmechanically actuated valve. The LCST at which the valve switches was easily adjusted within a range of 35°C–74°C by varying the proportions of the monovinyl monomers in the polymerization mixture. The closed valve holds pressures of up to 18 MPa without noticeable dislocation, structural damage, or leakage. In contrast, following deswelling by raising the temperature above LCST the valve offers no appreciable flow resistance since its large, micrometer‐size pores are open. Laser‐triggered photobleaching of a fluorescent dye contained in the liquid phase enabled monitoring of flow through the device and determination of the times required to open and close the valve. The valves are characterized by very fast actuation times in a range of 1–4 s depending on the type of device. No changes in performance were observed even after repeated open‐close cycling of the valves.
Automated chip‐based nanoelectrospray‐mass spectrometry for rapid identification of proteins separated by two‐dimensional gel electrophoresis
Authors: Zhang Sheng , Van Pelt Colleen K. , Henion Jack D.
Published: November 2003

We report a method using a fully automated chip‐based nanoelectrospray system for two‐dimensional (2‐D) gel sample analyses with mass spectrometric detection. The automated nanoelectrospray system, consisting of the NanoMate and electrospray ionization (ESI) chip, serves as both an autosampler and nanoESI source. This infusion system aspirates samples from a 96‐well plate using disposable pipette tips and then delivers these samples sequentially to an ESI chip. This chip is a fully integrated monolithic device consisting of a 10×10 array of nozzles. The automated nanoelectrospray system is easily controlled through software, permitting the user to select the number of samples to be analyzed, the volume of sample to aspirate, the spray voltage, and analysis time. The system offers all the advantages of conventional nanoelectrospray plus automated, high‐throughput analyses without analyte carryover. The system was used for a protein identification study of 2‐D gel spots of both Escherichia coli and yeast crude cell extracts. The identification of 50 spots from E. coli crude cell extract and 27 spots from yeast extract is presented, demonstrating the powerful combination of the automated nanoESI system, the Thermo Finnigan LCQ Deca ion‐trap mass spectrometer, and SEQUEST search software. In addition, the effects of silver staining and colloidal Coomassie blue staining of 2‐D gel spots on the detection sensitivity and protein sequence coverage are compared and discussed. Furthermore, the comparison results using the multiwell microscale preparation kit versus manual extraction for in‐gel samples are presented.
Cross‐linked coatings for electrophoretic separations in poly(dimethylsiloxane) microchannels
Authors: Hu Shuwen , Ren Xueqin , Bachman Mark , Sims Christopher E. , Li G. P. , Allbritton Nancy
Published: November 2003

We have developed a strategy using ultraviolet light to polymerize mixed monomer solutions onto the surface of a poly(dimethylsiloxane) (PDMS) microdevice. By including monomers with different chemical properties, electrophoretic separations were optimized for a test set of analytes. The properties of surfaces grafted with a single neutral monomer, a neutral and a negative monomer, or a neutral, negative, and cross‐linking monomer were assessed. The highest quality separations were achieved in channels with cross‐linked coatings. The separation efficiency for biologically relevant peptides (kinase substrates) on these surfaces was as high as 18 600 theoretical plates in a 2.5 cm channel. The test peptides were fluorescein‐AEEEIYGEFEAKKKK, fluorescein‐GRPRAATFAEG, fluorescein‐GRPRAA(T‐PO3)FAEG, fluorescein‐DLDVPIP GRFDRRVSVAAE, and fluorescein‐DLDVPIPGRFDRRV(S‐PO3)VAAE. Separations between two different peptides occurred in as little as 400 ms after injection into the separation channel. The simultaneous separation of five kinase and phosphatase substrates was also demonstrated. By carefully selecting mixtures of monomers with the appropriate properties, it may be possible to tailor the surface of PDMS for a large number of different electrophoretic separations.
Preconcentration and separation of double‐stranded DNA fragments by electrophoresis in plastic microfluidic devices
Authors: Wainright Ann , Nguyen Uyen T. , Bjornson TorLeif , Boone Travis D.
Published: November 2003

We have evaluated double‐stranded DNA separations in microfluidic devices which were designed to couple a sample preconcentration step based on isotachophoresis (ITP) with a zone electrophoretic (ZE) separation step as a method to increase the concentration limit of detection in microfluidic devices. Developed at ACLARA BioSciences, these LabCard™ devices are plastic 32 channel chips, designed with a long sample injection channel segment to increase the sample loading. These chips were designed to allow stacking of the sample into a narrow band using discontinuous ITP buffers, and subsequent separation in the ZE mode in sieving polymer solutions. Compared to chip ZE, the sensitivity was increased by 40‐fold and we showed baseline resolution of all fragments in the ΦX174/HaeIII DNA digest. The total analysis time was 3 min/sample, or less than 100 min per LabCard device. The resolution for multiplexed PCR samples was the same as obtained in chip ZE. The limit of detection was 9 fg/μL of DNA in 0.1×polymerase chain reaction (PCR) buffers using confocal fluorescence detection following 488 nm laser excitation with thiazole orange as the fluorescent intercalating dye.
Sequencing of real‐world samples using a microfabricated hybrid device having unconstrained straight separation channels
Authors: Liu Shaorong , Elkin Christopher , Kapur Hitesh
Published: November 2003

We describe a microfabricated hybrid device that consists of a microfabricated chip containing multiple twin‐T injectors attached to an array of capillaries that serve as the separation channels. A new fabrication process was employed to create two differently sized round channels in a chip. Twin‐T injectors were formed by the smaller round channels that match the bore of the separation capillaries and separation capillaries were incorporated to the injectors through the larger round channels that match the outer diameter of the capillaries. This allows for a minimum dead volume and provides a robust chip/capillary interface. This hybrid design takes full advantage, such as sample stacking and purification and uniform signal intensity profile, of the unique chip injection scheme for DNA sequencing while employing long straight capillaries for the separations. In essence, the separation channel length is optimized for both speed and resolution since it is unconstrained by chip size. To demonstrate the reliability and practicality of this hybrid device, we sequenced over 1000 real‐world samples from Human Chromosome 5 and Ciona intestinalis, prepared at Joint Genome Institute. We achieved average Phred20 read of 675 bases in about 70 min with a success rate of 91%. For the similar type of samples on MegaBACE 1000, the average Phred20 read is about 550–600 bases in 120 min separation time with a success rate of about 80–90%.
High‐efficiency peptide analysis on monolithic multimode capillary columns: Pressure‐assisted capillary electrochromatography/capillary electrophoresis coupled to UV and electrospray ionization‐mass spectrometry
Authors: Ivanov Alexander R. , Horváth Csaba , Karger Barry L.
Published: November 2003

High‐efficiency peptide analysis using multimode pressure‐assisted capillary electrochromatography/capillary electrophoresis (pCEC/pCE) monolithic polymeric columns and the separation of model peptide mixtures and protein digests by isocratic and gradient elution under an applied electric field with UV and electrospray ionization‐mass spectrometry (ESI‐MS) detection is demonstrated. Capillary multipurpose columns were prepared in silanized fused‐silica capillaries of 50, 75, and 100 μm inner diameters by thermally induced in situ copolymerization of methacrylic monomers in the presence of n‐propanol and formamide as porogens and azobisisobutyronitrile as initiator. N‐Ethylbutylamine was used to modify the chromatographic surface of the monolith from neutral to cationic. Monolithic columns were termed as multipurpose or multimode columns because they showed mixed modes of separation mechanisms under different conditions. Anion‐exchange separation ability in the liquid chromatography (LC) mode can be determined by the cationic chromatographic surface of the monolith. At acidic pH and high voltage across the column, the monolithic stationary phase provided conditions for predominantly capillary electrophoretic migration of peptides. At basic pH and electric field across the column, enhanced chromatographic retention of peptides on monolithic capillary column made CEC mechanisms of migration responsible for separation. The role of pressure, ionic strength, pH, and organic content of the mobile phase on chromatographic performance was investigated. High efficiencies (exceeding 300 000 plates/m) of the monolithic columns for peptide separations are shown using volatile and nonvolatile, acidic and basic buffers. Good reproducibility and robustness of isocratic and gradient elution pressure‐assisted CEC/CE separations were achieved for both UV and ESI‐MS detection. Manipulation of the electric field and gradient conditions allowed high‐throughput analysis of complex peptide mixtures. A simple design of sheathless electrospray emitter provided effective and robust low dead volume interfacing of monolithic multimode columns with ESI‐MS. Gradient elution pressure‐assisted mixed‐mode separation CE/CEC‐ESI‐MS mass fingerprinting and data‐dependent pCE/pCEC‐ESI‐MS/MS analysis of a bovine serum albumin (BSA) tryptic digest in less than 5 min yielding high sequence coverage (73%) demonstrated the potential of the method.
Immobilized metal‐ion chelating capillary microreactor for peptide mapping analysis of proteins by matrix assisted laser desorption/ ionization‐time of flight‐mass spectrometry
Authors: Guo Zhong , Xu Songyun , Lei Zhengdeng , Zou Hanfa , Guo Baochuan
Published: November 2003

Peptide mass mapping analysis, utilizing a regenerable enzyme microreactor with metal‐ion chelated adsorption of enzyme, combined with matrix assisted laser desorption/ionization‐time of flight‐mass spectrometry (MALDI‐TOF‐MS) was developed. Different procedures from the conventional approaches were adopted to immobilize the chelator onto the silica supports, that is, the metal chelating agent of iminodiacetic acid (IDA) was reacted with glycidoxypropyltrimethoxysilane (GLYMO) before its immobilization onto the inner wall of the fused‐silica capillary pretreated with NH4HF2. The metal ion of copper and subsequently enzyme was specifically adsorbed onto the surface to form the immobilized enzyme capillary microreactor, which was combined with MALDI‐TOF‐MS to apply for the mass mapping analysis of nL amounts of protein samples. The results revealed that the peptide mapping could routinely be generated from 0.5 pmol protein sample in 15 min at 50°C, even 20 fmol cytochrome c could be well digested and detected.
Hybrid microdevice electrophoresis of peptides, proteins, DNA, viruses, and bacteria in various separation media, using UV‐detection
Authors: Végvári Ákos , Hjertén Stellan
Published: November 2003

Recently we described the design of a hybrid microdevice for micro(nano)electrophoresis and electrochromatography, discussed its advantages and disadvantages compared to conventional microdevices and presented a few applications with low‐molecular‐weight samples. In this paper, we demonstrate the broad application range of this device using UV‐based analyses of (i) peptides by free‐zone electrophoresis and electrophoresis in a recently introduced gel (polyacrylamide cross‐linked with allyl‐β‐cyclodextrin), (ii) proteins by electrophoretic molecular‐sieving in a polymer solution supplemented with SDS, (iii) DNA fragments by electrophoresis in the above gel, (iv) virus particles in this gel, as well as in free buffer and (v) bacteria in free buffer. To illustrate the advantages of the hybrid microdevice we can mention that electrophoresis of proteins in a polymer‐containing buffer, supplemented with sodium dodecyl sulfate (SDS), in a 4.30 (2.75) cm long channel gave a resolution similar to that in conventional capillary electrophoresis in a 23.5 (18.6) cm long capillary and analysis times which were 15‐fold shorter.
Electrokinetic supercharging preconcentration and microchip gel electrophoretic separation of sodium dodecyl sulfate‐protein complexes
Authors: Xu Zhongqi , Ando Tomomi , Nishine Tsutomu , Arai Akihiro , Hirokawa Takeshi
Published: November 2003

A microchip gel electrophoresis (MCGE) method with electrokinetic supercharging (EKS, electrokinetic injection with transient isotachophoresis) on a single channel chip was developed for high‐sensitive detection of a standard mixture of six proteins (phosphorylase b, albumin, ovalbumin, carbonic anhydrase, trypsin inhibitor, and α‐lactalbumin) in the form of sodium dodecyl sulfate (SDS) complexes. An average lower limit of detectable concentration (LLDC) achieved using UV detection at 214 nm was 0.27 μg/mL that is 30 times lower than that of conventional MCGE on a cross geometry chip. The calibration curves for molecular weight and concentration of SDS‐protein complexes suggested that the present EKS‐MCGE method had a better linear dynamic range and benefited future applications for qualitative and quantitative analysis of unknown protein samples. It was found that an excessive amount of unbound SDS in the sample deteriorated the preconcentration effect and resolution. The developed method appears greatly promising for high‐speed and high sensitive analysis of SDS‐proteins by MCGE.
Surface modification of poly(dimethylsiloxane) microchannels
Authors: Makamba Honest , Kim Jin Ho , Lim Kwanseop , Park Nokyoung , Hahn Jong Hoon
Published: November 2003

This review looks at the efforts that are being made to modify the surface of poly(dimethylsiloxane) (PDMS) microchannels, in order to enhance applicability in the field of microfluidics. Many surface modifications of PDMS have been performed for electrophoretic separations, but new modifications are being done for emerging applications such as heterogeneous immunoassays and cell‐based bioassays. These new modification techniques are powerful because they impart biospecificity to the microchannel surfaces and reduce protein adsorption. Most of these applications require the use of aqueous or polar solvents, which makes surface modification a very important topic.
Microfluidic systems in proteomics
Authors: Lion Niels , Rohner Tatiana C. , Dayon Loïc , Arnaud Isabelle L. , Damoc Eugen , Youhnovski Nikolay , Wu Zhi‐Yong , Roussel Christophe , Josserand Jacques , Jensen Henrik , Rossier Joël S. , Przybylski Michael , Girault Hubert H.
Published: November 2003

We present the state‐of‐the‐art in miniaturized sample preparation, immunoassays, one‐dimensional and multidimensional analyte separations, and coupling of microdevices with electrospray ionization‐mass spectrometry. Hyphenation of these different techniques and their relevance to proteomics will be discussed. In particular, we will show that analytical performances of microfluidic analytical systems are already close to fulfill the requirements for proteomics, and that miniaturization results at the same time in a dramatic increase in analysis throughput. Throughout this review, some examples of analytical operations that cannot be achieved without microfluidics will be emphasized. Finally, conditions for the spreading of microanalytical systems in routine proteomic labs will be discussed.
Targeting hepatocytes from liver tissue by laser capture microdissection and proteomics expression profiling
Authors: Marko‐Varga György , Berglund Magnus , Malmström Johan , Lindberg Henrik , Fehniger Thomas E.
Published: November 2003

A tissue proteomics process is presented where hepatocyte cell isolation in combination with two‐dimensional (2‐D) gel electrophoresis and mass spectrometric identification were used to annotate the liver proteome. Laser microdissection of 8 μm liver tissue sections was performed and protein expression profiling was compared using a variety of quantities of input cells, and gel separation conditions. The 30 μm diameter laser generated the highest protein yields from the polymer coated caps following microsolubilization. We found that 6000 laser pulses (approximately 7200 hepatocytes) were required in order to generate high‐resolution gel maps. Within homogeneous tissue samples, this could be accomplished in a total cycle time of 20 min using an automated dissection procedure. Close to 1000 high‐quality gel annotations were generated from the corresponding 2‐D gel expression profiles which matched closely the corresponding patterns of analytical‐scale liver preparations detected by silver staining.
A massively parallel PicoTiterPlate™ based platform for discrete picoliter‐scale polymerase chain reactions
Authors: Leamon John H. , Lee William L. , Tartaro Karrie R. , Lanza Janna R. , Sarkis Gary J. , deWinter Alex D. , Berka Jan , Lohman Kenton L.
Published: November 2003

We demonstrate successful, simultaneous polymerase chain reaction (PCR) amplification of up to 300 000 discrete reactions in a novel platform, the PicoTiterPlate™. In addition to elevated throughput, the PicoTiterPlate™ based amplifications (PTPCR) can be performed in extremely small volumes: individual reactions volumes are as low as 39.5 pL, with a total 15.3 μL reaction volume for the entire PicoTiterPlate™. The bulk PTPCR product can be recovered and assayed with real‐time PCR, or discrete PTPCR products can be driven to solid supports, enabling downstream applications such as translation/transcription or sequencing.
Improved solid‐phase microextraction device for use in on‐line immunoaffinity capillary electrophoresis
Authors: Guzman Norberto A.
Published: November 2003

A simple solid‐phase microextraction device was fabricated for use in on‐line immunoaffinity capillary electrophoresis (CE). The device, designed in the form of a four‐part cross‐shaped or cruciform configuration, includes a large‐bore tube to transport samples and washing buffers and a small‐bore fused‐silica capillary for separation of analytes. At the intersection of the transport and separation tubes, a small cavity was fabricated, termed the analyte concentrator‐microreactor, which contains four porous walls or semipermeable membranes (one for each inlet and outlet of the tubes) permitting the confinement of beads or suitable microstructures. The surface of the beads in the analyte concentrator carried a molecular recognition adsorbing chemical or affinity ligand material. The improved cruciform configuration of the analyte concentrator‐microreactor device, designed for use in on‐line immunoaffinity CE, enables it to specifically trap, enrich, and elute an analyte from any biological fluid or tissue sample extract without any sample pretreatment except filtration, centrifugation, and/or dilution allowing the separation and characterization of target analyte(s) with improved speed, sensitivity, and lower cost than existing techniques. As a model system, Fab' fragments derived from a purified immunoglobulin G (IgG) antibody were covalently bound to controlled‐porosity glass and used as constituents of the analyte‐microreactor device. The high‐specificity polyclonal antibodies employed in these experiments were individually raised against the acidic nonsteroidal anti‐inflammatory drugs ibuprofen and naproxen, and the neuropeptides angiotensin II, and neurotensin. These compounds, which were present in simple and complex matrices were captured by and eluted from the analyte concentrator‐microreactor using a 50 mM sodium tetraborate buffer solution, pH 9.0, followed by a 100 nL plug of 300 mM glycine buffer, pH 3.4. Two analyte concentrators were tested independently: one containing Fab' fragments derived from antibodies raised against ibuprofen and naproxen; the other containing Fab' fragments derived from antibodies raised against angiotensin II and neurotensin. Each resulting electropherogram demonstrated the presence of two eluted materials in less than 20 min. Immunoaffinity CE performed in a cruciform structure was simpler and faster than previously reported in the literature using on‐line microextraction devices designed in a linear format. The new concentration‐separation system operated consistently for many runs, maintaining reproducible migration times and peak areas for every analyte studied.
Parallel processing in the isoelectric focusing chip
Authors: Zilberstein Gleb V. , Baskin Emmanuil M. , Bukshpan Shmuel
Published: November 2003

Investigation of isoelectric focusing (IEF) kinetics has been performed to provide the theoretical basis for miniaturization of classical IEF in immobilized pH‐gradients. Standard IEF demands colinearity of the electric field and pH‐gradient directions (serial devices). It is shown that the IEF separation process based on a continuous, serial pH gradient is incompatible with miniaturization of separation devices. The new realization of the IEF device by a parallel IEF chip is suggested and analyzed. The main separation tool of the device is a dielectric membrane (chip) with conducting channels that are filled by Immobiline gels of varying pH. The membrane is held perpendicular to the applied electric field and proteins are collected (trapped) in the channels whose pH are equal to the pI of the proteins. The pH value of the surrounded aqueous solution is not equal to any channel's pH. The fast particle transport between different channels takes place due to convection in the aqueous solution. The new device geometry introduces two new spatial scales to be considered: the scale of transition region from a solution to the gel in a channel and a typical channel size. The corresponding time scales defining the IEF process kinetics are analyzed and scaling laws are obtained. It is shown both theoretically and experimentally that parallel IEF accelerates the fractionation of proteins by their pI down to several minutes and enables possible efficient sample collection and purification.
Predation on Mosquito Larvae by Mesocyclops thermocyclopoides (Copepoda: Cyclopoida) in the Presence of Alternate Prey
Authors: Kumar Ram , Ramakrishna Rao T.
Published: November 2003

The cyclopoid copepod Mesocyclops thermocyclopoides, a dominant invertebrate predator in many shallow ponds and temporary water bodies in northern India, feeds on cladocerans, rotifers, ciliates and when present, on mosquito larvae also. We studied in the laboratory the prey consumption rates of the copepod on first and fourth instar larvae of two species of mosquito (Anopheles stephensi and Culex quinquefasciatus) in relation to their density. We also studied its prey selectivity with mosquito larvae in the presence of an alternate prey (the cladocerans‐either Moina macrocopa or Ceriodaphnia cornuta) in different proportions. With either mosquito species, the copepod actively selected Instar‐I larvae, avoiding the Instar‐IV larvae, and with either instar, selected Anopheles stephensi over Culex quinquefasciatus. When prey choice included the cladoceran as an alternate prey, the copepod selected the cladoceran only when the other prey was Instar‐IV mosquito larvae. Our results point to the potential and promise of M. thermocyclopoides as a biological agent for controlling larval populations of vectorially important mosquito species.
Haplotype Frequency Distribution in Northeastern European Saduria entomon (Crustacea: Isopoda) Populations. A Phylogeographic Approach
Authors: Sell Jerzy
Published: November 2003

The distribution pattern of mtDNA haplotypes in distinct populations of the glacial relict crustacean Saduria entomon was examined to assess phylogeographic relationships among them. Populations from the Baltic, the White Sea and the Barents Sea were screened for mtDNA variation using PCR‐based RFLP analysis of a 1150 bp fragment containing part of the CO I and CO II genes. Five mtDNA haplotypes were recorded. An analysis of geographical heterogeneity in haplotype frequency distributions revealed significant differences among populations. The isolated populations of S. entomon have diverged since the retreat of the last glaciation. The geographical pattern of variation is most likely the result of stochastic (founder effect, genetic drift) mechanisms and suggests that the haplotype differentiation observed is probably older than the isolation of the Baltic and Arctic seas.
Size‐Fractionated Phytoplankton and Relationships with Metazooplankton in a Newly Flooded Reservoir
Authors: Tadonléké Rémy D. , Thouvenot A. , Gilbert D. , Sime‐Ngando T. , Debroas D. , Devaux J.
Published: November 2003

In order to yield some insights into the planktonic food web structure of new reservoirs, size‐fractionated biomass and productivity of phytoplankton were examined from 1996 to 1997 (following the 1995 flooding of the Sep Reservoir, Puy‐de‐Dôme, France), in relation to nutrients (P, N) and metazooplankton (Rotifers, Cladocera, Copepods). Autotrophic nanoplankton (ANP, size class 3–45 μm) dominated the phytoplankton biomass (as Chlorophyll a) and production, while autotrophic picoplankton (APP, 0.7–3 μm) exhibited the lowest and relatively constant biomass and production. Cells of the autotrophic microplankton (AMP, >45 μm) were considered inedible for planktonic herbivores. The production‐biomass diagram for the different size classes and the positive correlation between APP production and ANP + AMP production suggested that grazing was potentially more important than nutrients in shaping the phytoplankton size structure. Metazooplankton biomass was low compared to other newly flooded reservoirs or to natural lakes with phytoplankton biomass similar to that of the Sep Reservoir. This resulted in low ratios (metazooplankton to edible phytoplankton) both in terms of production (average 0.43% in 1996 and 0.76% in 1997) and biomass, suggesting that only a small fraction of phytoplankton was directly consumed by metazooplankton. We suggest that the observed low ratios in the Sep Reservoir, reflect possible low metazooplankton inputs in the main influents, changes in hydrologic conditions and a high potential role of microheterotrophs. The latter role was supported by (i) the positive inter‐annual correlation between ciliates and phytoplankton, (ii) the significant and negative correlations between ciliates and metazooplankton, and (iii) the significant and negative correlations between total metazooplankton biomass and total phosphorus (TP), whereas neither TP nor total metazooplankton biomass was correlated with phytoplankton variables.
Strain‐rate effect on the biomechanical response of bovine temporomandibular joint disk under compression
Authors: Tanaka Eiji , del Pozo Rodrigo , Tanaka Masao , Aoyama Junko , Hanaoka Koichi , Nakajima Akira , Inuzuka Shinichi , Tanne Kazuo
Published: November 2003

This study evaluates the effect of strain rate on the biomechanical responses of bovine temporomandibular joint (TMJ) disk under compression. Ten specimens derived from the central region of bovine TMJ disks were used for compression tests. Each specimen was loaded upto 20% of strain with seven different strain rates: 1, 10, 20, 30, 40, 50, and 60%/s. Although the stress–strain curves presented similar patterns for all the specimens, the strain‐rate effect was obvious. The linear modulus by regression fit for the linear part of the curve was significantly larger at 60%/s of strain rate than at the lower strain rates. The “supplemental stress” ratio (SSR) obviously increased with the augmentation of the strain rate. At strain rates of 30–60%/s, the SSR was significantly larger than those at strain rates below 20%/s. These findings indicate that although water easily can move through the TMJ disk at the lower strain rates, the higher strain rates make such movement difficult. It is concluded that the secondary changes of the TMJ disk may be dependent on the pattern and velocity of masticatory mandibular movements directly associated with the dynamic strain rate in the TMJ disk. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 761–765, 2003