bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of sialylated by sulfated oligosaccharides in negative MALDI‐FTMS
Authors: An Hyun Joo , Lebrilla Carlito B.
Published: April 2004

Sialylated oligosaccharides are suppressed by sulfated oligosaccharides during matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. The sialylated oligosaccharide may be suppressed by as much as a factor of ten to twenty. This suppression factor is constant over a large concentration range. As both sialylated and sulfated (or anionic) oligosaccharides are found together in many biological systems, the suppression has important consequences in the analysis of these compounds. Methods for overcoming the effect of suppression without laborious separation are provided.
UV resonance Raman probe of heme‐bound imidazole established by 15N‐labeling of hemoglobin
Authors: Zhao Xiaojie , Chen Ruopian , Deng Qing , Mabrouk Patricia Ann , Spiro Thomas G.
Published: April 2004

Recent studies of Cu, Zn superoxide dismutase, and of zinc‐finger peptides have established that histidine ligands can be detected in ultraviolet resonance Raman (UVRR) spectra, following NH/D exchange of the imidazole. UVRR spectroscopy therefore offers promise for monitoring histidine ligation in heme proteins. In this work, we characterize heme‐bound histidine UVRR bands for N‐acetyl‐microperoxidase‐8 (MP‐8) and microperoxidase‐11 (MP‐11), and also for hemoglobin (Hb). The Hb UVRR spectra are dominated by tyrosine and tryptophan contributions, but a band appears at 1340 cm−1 in D2O solution, which is assigned to a mode of Fe‐bound imidazole. This band shifted 24 cm−1 in protein which was labeled with 15N via expression of the Hb gene in E. coli grown on 15NH4+. In MP‐11, the position of this band is insensitive to ligation or oxidation state changes, but it is 2 cm−1 lower in deoxyHb than in the CO adduct. This shift may reflect mechanical forces on the proximal histidine in the T state, and/or changes in its H‐bonding.
Synthesis, structure, and thermal behavior of [Cu70Se35(PEt2Ph)24]
Authors: Eichhöfer Andreas , Beckmann Erich , Fenske Dieter , Herein Daniel , Krautscheid Harald , Schlögl Robert
Published: April 2004

We investigated the molecular and crystal structure as well as the thermal behavior of [Cu70Se35(PEt2Ph)24] using single‐crystal X‐ray diffraction, high‐resolution transmission electron microscopy (HRTEM), X‐ray powder diffractometry, and thermal gravimetric analysis (TGA). The use of a He‐cooled sample head in HRTEM makes possible for the first time the investigation of semiconductor cluster molecules under the extreme conditions of the experiment and, thus, comparison with the results of single‐crystal X‐ray diffraction. The lattice spacings and packing symmetry of the three‐dimensional cluster molecule superlattice found in HRTEM are in good agreement with the ones determined by X‐ray structure diffraction. The atomic ordering inside the cluster molecules, which resembles a hexagonal packing of the selenium atoms, could not be resolved in the HRTEM measurements, since upon irradiation with the electron beam the clusters start to move after a few seconds and the images go out of focus. This movement is possibly affected by cleavage processes of the phosphine ligands, as could be observed in thermal gravimetric analysis under comparably mild conditions. Powder diffraction measurements show that this cleavage of ligand molecules is accompanied by the formation of larger copper selenide cluster cores and ends up at high temperatures in the formation of bulk α‐Cu2Se.
The Hydroformylation Reaction
Authors: Ojima Iwao , Tsai Chung‐Ying , Tzamarioudaki Maria , Bonafoux Dominique
Published: April 2004

The reaction of 1‐alkenes with carbon monoxide and hydrogen in the presence of a catalyst gives the corresponding homologous aldehydes. The discovery of this reaction was made by Roelen in 1938 using Co2(CO)8as the catalyst at high temperature (120–170°) and high pressure of carbon monoxide/hydrogen (200–300 bar). This reaction has been called the “Oxo reaction”, “Roelen reaction” or “hydroformylation”. Hydroformylation is a general term indicating that both a hydrogen and a formyl group are introduced to unsaturated bonds, especially olefins.

Later this reaction was developed as an industrial process, i.e., the Oxo Process, for the production of alkanals from 1‐alkenes using a cobalt or rhodium catalyst. Most noteworthy is the conversion of propene to butanal, which can be subsequently hydrogenated to 1‐butanol or converted to 2‐ethylhexanol by self‐aldol condensation. 2‐Ethylhexanol, a crucial intermediate for the production of ester‐type plasticizers, is the most important bulk chemical produced by the Oxo Process. A variety of transition metal catalysts other than Co2(CO)8have been investigated, including phosphine complexes of cobalt and hydridocobalt clusters. Platinum and ruthenium complexes show reasonably good catalytic activities, but modified cobalt catalysts are still much more advantageous. However, various rhodium complexes demonstrate higher catalytic activity (103–104times) than the cobalt complexes. Although the price of rhodium is higher than cobalt, reactions using rhodium catalysts require lower temperature (50–80°) and pressure (10–50 atm).

Other important commercial applications of hydroformylation include the production of long‐chain alcohols from C5–C17isomeric linear alkenes. These long‐chain alcohols serve as intermediates for lubricants, plasticizers and detergents. The hydroformylation of ethene to propanal is another important Oxo Process.

In this chapter, the authors put clear emphasis on the scope of the hydroformylation reaction in organic synthesis. In this context, there is a relevant review in 1987 of the hydroformylation of functionalized alkenes. The hydroformylation reaction now can be performed under very mild conditions using a variety of functionalized alkenes. Reactions in aqueous biphase, supercritical carbon dioxide or fluorous biphase have recently emerged in response to separation and environmental issues. In fact, a highly efficient Oxo Process using a water‐soluble rhodium catalyst in aqueous biphasic conditions has been commercialized by Ruhrchemie/Rhône‐Poulenc for the production of butanal. Asymmetric hydroformylation of prochiral olefins catalyzed by enantiopure rhodium complexes has been developed to the level that practical applications appear possible. Although the reactions of formaldehyde, oxiranes, and others with carbon monoxide and hydrogen in the presence of transition metal catalyst could be considered as variations of hydroformylation, this chapter only deals with hydroformylation of carbon‐carbon multiple bonds.
Simmons‐Smith Cyclopropanation Reaction
Authors: Charette André B. , Beauchemin André
Published: April 2004

Almost 30 years after Emschwiller prepared IZnCH2I, Simmons and Smith discovered that the reagent formed by mixing a zinc‐copper couple with CH2I2in ether could be used for the stereospecific conversion of alkenes to cyclopropanes. Nowadays, the Simmons‐Smith cyclopropanation reaction is one of the most widely used reactions in the organic chemist's arsenal for the conversion of olefins into cyclopropanes. This popularity is mainly due to the stereospecificity of the reaction with respect to the double bond geometry and its compatibility with a wide range of functional groups. The chemoselectivity of the reaction toward some olefins is excellent and very few side reactions are observed with functionalized substrates. The metal carbenoid is electrophilic in nature and electron‐rich alkenes usually react much faster than electron‐poor alkenes.

Furthermore, the ability to use proximal hydroxy or ether groups to dictate the stereochemical outcome of the CC bond forming process was recognized early on, and this unique property has been successfully exploited on numerous occasions. It has been recognized that halomethylmetal reagents are powerful synthetic tools for the stereoselective addition of a methylene unit to chiral acyclic allylic alcohols and allylic ethers. In addition, the use of halomethylzinc reagents in the presence of chiral additives is one of the few ways to cyclopropanate allylic alcohols efficiently and with good enantiocontrol.

Carbenoids can be divided into the following two classes: (1) those of general structure MCH2X and (2) those corresponding to M = CH2. This chapter is focussed exclusively on the first class in which M = Zn, Sm, or Al. Although other metal carbenoids of type MCH2X, such as those derived from Cu, Cd, Hg, and In, have been reported to be effective reagents for the cyclopropanation of some olefins, they have been used only sporadically, and this review does not highlight these reactions. This chapter covers cyclopropanation reactions involving haloalkylzinc, aluminum, and samarium reagents published since the comprehensive chapter inOrganic Reactionsby Simmons that surveyed the literature up to 1973.
Reductive Aminations of Carbonyl Compounds with Borohydride and Borane Reducing Agents
Authors: Baxter Ellen W. , Reitz Allen B.
Published: April 2004

Reductive amination is an important tool for synthetic organic chemists in the construction of carbon‐nitrogen bonds. This reaction, also termed reductive alkylation, involves condensation of an aldehyde or ketone with an amine in the presence of a reducing agent. A wide variety of substrates can be used including aliphatic and aromatic aldehydes and ketones, and even benzophenones. A range of amines from ammonia to aromatic amines, including those with electron‐withdrawing substituents, can be employed. For particularly sluggish reactions, such as those involving weakly electrophilic carbonyl groups, poorly nucleophilic amines, or sterically congested reactive centers, additives such as molecular sieves or Lewis acids are often useful.

This chapter focuses on those conditions in which the carbonyl component, amine, and reducing reagent react in the same vessel. This review is restricted to reductive aminations using borohydride and borane reducing agents. This chapter concentrates on reductive amination chemistry mediated by borohydride and other boron‐containing reducing agents from 1971, the year when sodium cyanoborohydride was introduced, through the middle of 1999. In addition to reductive aminations of aldehyde and ketone substrates, reactions of related structures including acetals, aminals, ketals, carboxylic acids, nitriles, and dicarbonyls that form a nitrogen‐containing ring are reviewed. Intramolecular processes in which the substrate contains both the carbonyl and amine moieties are described. The intramolecular variant is a useful method for preparing cyclic amines. All of the various boron‐containing hydride sources in reductive aminations, including labeled metal hydrides, are reviewed. Instances of reductive aminations that failed are described. Applications of this method to a solid support in parallel synthesis in combinatorial chemistry as well as reductive aminations that proceed in tandem with a second reaction such as reductive lactamizations are discussed.
Transformation of Glycals into 2,3‐Unsaturated Glycosyl Derivatives
Authors: Ferrier Robert J. , Zubkov Oleg A.
Published: April 2004

Various elimination procedures conducted on appropriate pyranoid and furanoid carbohydrate derivatives, especially onO‐protected glycosyl halides afford cyclic vinyl ethers which Fischer (inappropriately) named glycals. These are used extensively in general organic synthesis and for the preparation of non‐carbohydrate natural products as well as biologically important complex carbohydrates and glycoconjugates. The best known member, tri‐O‐acetyl‐D‐glucal, is normally made from tetra‐O‐acetyl‐alpha‐D‐glucopyranosyl bromide, is commercially available, and is used very frequently in this chapter to represent the family in examples of the reactions under discussion.

Because of the pronounced region‐ and stereoselectivities with which their addition reactions can be conducted, glycal derivatives are of major importance in synthesis. They also, however, take part in rearrangement processes that, likewise, have proved useful for synthesis. The principal one involves nucleophilic substitution of the allylic group with allylic rearrangement and results in products having double bonds in the 2, 3 positions and new substituents at the anomeric centers. By far the simplest and most commonly used way to this conversion involves the removal of the allylic substituent of the glycal and the generation of highly resonance‐stabilized oxocarbenium ion intermediate. This may then react with nucleophiles at the anomeric center to give products as mixtures of diastereomers. Many examples and variations of this theme are described and form the major part of this chapter, but other ways are also considered

Almost no formal mechanistic studies have been carried out on the reactions in this chapter. Categorization of mechanism required for the treatment of this topic has been done on the basis of conditions used, product identification and largely, chemical intuition.
Influence of maleic anhydride on the compatibility of thermal plasticized starch and linear low‐density polyethylene
Authors: Wang Shujun , Yu Jiugao , Yu Jinglin
Published: April 2004

In the presence of dicumyl peroxide, the compatibility of thermal plasticized starch/linear low‐density polyethylene (TPS/LLDPE) blends using maleic anhydride (MAH) as compatibilizer was investigated. The thermal plasticization of starch and its compatibilizing modification with LLDPE was accomplished in a single‐screw extruder at the same time. We prepared three types of blends containing different percentages of TPS and MAH. The content of MAH based on LLDPE was 0, 1, and 2 wt %, respectively. The morphology of the blends was studied by SEM. It was found that, with the addition of MAH, the blends have good interfacial adhesion and finely dispersed TPS and LLDPE phases, which is reflected in the mechanical and thermal properties of the blends. The blends containing MAH showed higher tensile strength, elongation at break, and thermal stability than those of blends without MAH. The rheologic properties of the blends demonstrated the existence of processing. Finally, the dynamic thermal mechanical analysis results indicated that, with the addition of MAH, the compatibility between TPS and LLDPE in the blends was substantially improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 686–695, 2004
Preparation and properties of waterborne polyurethane/polyaniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid blends
Authors: Kwon Ji‐Yun , Koo Young‐Seok , Kim Han‐Do
Published: April 2004

A conductive poly(aniline codoped with dodecyl benzene sulfonic acid and hydrochloric acid) [PANI‐D/H, yield: 32.2%, intrinsic viscosity ([η]): 1.39 dL/g, electrical conductivity: 7.3 S/cm] was synthesized by chemical oxidative polymerization from aniline‐dodecylbenzene sulfonic acid salt (A‐DS)/aniline‐hydrochloric acid salt (A‐HS) (6/4M ratio) in an aqueous system. Waterborne polyurethane (WBPU) dispersion obtained from isophorone diisocyanate/poly(tetramethylene oxide)glycol/dimethylol propionic acid/ethylene diamine/triethylene amine/water was used as a matrix polymer. The blend films of WBPU/PANI‐D/H with various weight ratios (99.9/0.1–25/75) were prepared by solution blending/casting. Effect of PANI‐D/H content on the mechanical property, dynamic mechanical property, hardness, electrical conductivity, and antistaticity of WBPU/PANI‐D/H blend films was investigated. The dynamic storage modulus and initial tensile modulus increased with increasing PANI‐D/H content up to 1 wt %, and then it was significantly decreased about the content. With increasing PANI‐D/H content, the glass transition temperature of soft segment (Tgs) and hard segment (Tgh) of WBPU/PANI‐D/H blend films were shifted a bit to lower the temperature. The tensile strength and hardness of WBPU/PANI‐D/H blend films increased a little with increasing PANI‐D/H content up to 0.5 wt %, and then it was dramatically decreased over the content. The elongation at break of WBPU/PANI‐D/H decreased with an increase in PANI‐D/H content. From these results, it was concluded that 0.5–1 wt % of PANI‐D/H was the critical concentration to reinforce those various properties of WBPU/PANI‐D/H blend films prepared in this study. The electrical conductivity of WBPU/ultrasonic treated PANI‐D/H (particle size: 0.7 μm) blend films prepared here increased from 4.0 × 10−7 to 0.33 S/cm with increasing PANI‐D/H content from 0.1 to 75 wt %. The antistatic half‐life time (τ1/2) of pure WBPU film was about 110 s. However, those of WBPU/ultrasonic treated PANI‐D/H blend films (τ1/2: 8.2–0.1 s, and almost 0 s) were found to decrease exponentially with increasing PANI‐D/H content (0.1–9 wt %, and above 9 wt %). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 700–710, 2004
Adsorption of Zn(II) by crosslinked acrylic copolymers with amine functional groups
Authors: Barsanescu Adriana , Buhaceanu Rodica , Dulman Viorica , Bunia I. , Neagu Violeta
Published: April 2004

Adsorption of Zn(II) ions from diluted aqueous solutions by the acrylic copolymer based on ethylacrylate : acrylonitrile : divinylbenzene matrix with different crosslinking degrees and ethylenediamine and triethylenetetramine functional groups was investigated. Adsorption experiments were carried out by batch method. The effects of the pH, initial concentration of zinc, time of contact, and the crosslinking degree of the copolymers were studied. On the basis of Langmuir and Freundlich isotherms, the parameters that characterize the adsorption were determined. The maximum Zn(II) retention capacity value (500 mg g−1) was obtained for the acrylic copolymer with 2% crosslinking degree and ethylenediamine, as functional groups. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 803–808, 2004
New evidence derived from the discrimination of Henry and Langmuir modes parameters in glassy polymeric film revealed by the Freeze‐Purged‐Desorption method
Authors: Togawa Junya , Kobayashi Masayoshi
Published: April 2004

The Freeze‐Purged‐Desorption (FPD) method was developed for the experimental measurement of gas permeability coefficients as a new technique using a desorption curve of gas immobilized in polymeric films. The FPD method was effectively used to evaluate four gas permeation parameters (CD, CH, DD, and DH) of glassy polymeric films (polycarbonate and polystyrene) by using CO2. The modes of the CO2 gas desorption response curve (D‐curve) obtained were sensitively characterized by the proportion of sorption in the Henry and Langmuir modes in the polymeric films accompanied by their own gas diffusivity. A graphical analysis of the D‐curve of CO2 reasonably proposed a linear relation between the desorption rate and the sorption amount of CO2, which was strongly influenced by the kind of sorption gas, film, temperature, and other factors. The desorption rate of sorbed CO2 gas for the PC and PS films gave a characteristic straight line with an inflection point indicating a shift in the gas‐diffusion mechanism from the complex type of the Henry and the Langmuir modes to the Langmuir mode. The characteristic D‐curves obtained were graphically analyzed, and they clearly discriminated the Henry mode part and the Langmuir mode part. This discrimination process quantitatively and individually evaluated CD, CH, DD, and DH. By using the four parameters evaluated, a mathematical model to describe the D‐curve was proposed, and it consistently explained the experimental D‐curves. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 934–941, 2004
Organic–inorganic hybrid material. I. Synthesis, characterization, and thermal property of a novel polyhedral cubic silsesquioxane
Authors: Dare Enock O. , Olatunji Gabriel A. , Ogunniyi David S.
Published: April 2004

Hydrosilylation of 2‐chloroethylvinyl ether by octahydridosilsesilsesquioxane catalyzed by hexachloroplatinic acid was carried out to afford a quantitative yield of 3 in its white crystals. Thermogravimetric analysis of Si8O12(CH2CH2OCH2CH2Cl)8 3 revealed that it is reasonably thermally stable. Spectroscopic data and crystal structure were used to justify the integrity, structural and molecular connectivity of the hitherto novel compound. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 907–910, 2004
Degradability of expanded starch/PVA blends prepared using calcium carbonate as the expanding inhibitor
Authors: Park Jong‐Shin , Yang June‐Ho , Kim Dae‐Hyun , Lee Dae‐Hoon
Published: April 2004

In this study, expanded starch/poly(vinyl alcohol) (PVA) blends for packing material were prepared by using calcium carbonate as the expansion inhibitor to investigate the degradability and the structural and mechanical properties of expanded starch/PVA/calcium carbonate blends (ESPCs). The structure of ESPCs became more compact with increasing CaCO3 content and at least 2 parts of CaCO3 were required to obtain the sufficient inhibiting effect on the expansion. As CaCO3 content increased from 1 to 4 parts, tensile strength more than doubled from 70 to 180 KPa, while elongation at break increased about 1.5‐fold. The moduli of ESPCs also increased with increasing CaCO3 content, but they decreased continuously with exposure to UV radiation over all periods of exposure and remained in the range of 10–15 KPa after exposure for 7 weeks. The weight loss of ESPCs due to exposure to soil environment increased with exposure time and the final weight loss after the 5‐week exposure was about 25–30%. Specifically, the degradability of ESPC with 20 parts of PVA was 5% higher than that of ESPC with 30 parts of PVA. The water solubility of ESPC with 30 parts of PVA was somewhat higher than that of ESPC with 20 parts of PVA. Furthermore, most of ESPCs began to be degraded thermally at 292°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 911–919, 2004
PMMA blended and DPNR‐g‐PMMA coated DPNR and NR‐LA for dipping applications
Authors: Kovuttikulrangsie S. , Sahakaro K. , Intarakong C. , Klinpituksa P.
Published: April 2004

Deproteinized natural rubber (DPNR) latex, prepared by digesting the protein within low‐ammonia preserved concentrated (NR‐LA) latex with alcalase enzyme at 40°C for 24 h, has the nitrogen content of 0.039 wt %. Poly(methyl methacrylate) (PMMA) and graft copolymers (DPNR‐g‐PMMA) latices were synthesized by emulsion polymerization technique for blending or coating on DPNR or NR‐LA. Their general properties of natural and synthesized latices including compounded latex were verified. The friction coefficient of a homogenous film obtained from PMMA blended DPNR or NR‐LA latex and a DPNR‐g‐PMMA coated DPNR and NR‐LA film was found to be lower than those of films prepared by using DPNR or NR‐LA latex. Furthermore, the DPNR‐g‐PMMA coated films had lower friction coefficient than those of PMMA blended films. The physical properties in terms of 300% modulus, tensile strength, and elongation at break of those rubbers were tested and confined to the ASTM 3377‐78a and ASTM 3378‐99 standards for dipping products of surgical gloves and examination gloves, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 833–844, 2004
Synthesis of poly(vinyl pyridine)–silica nanocomposites using perhydropolysilazane
Authors: Saito Reiko , Tobe Tadakuni
Published: April 2004

Poly(2‐vinyl pyridine)/silica and poly(4‐vinyl pyridine)/silica nanocomposites were synthesized by casting of blend solutions of perhydropolysilazane and poly(2‐vinyl pyridine‐co‐2‐hydroxyethyl methacrylate) and poly(4‐vinyl pyridine‐co‐2‐hydroxyethyl methacrylate) random copolymers, respectively, and calcination of dried films at 100°C under steam. The structures of the separated phases and the thermal properties of the composites were investigated by transmission electron microscopy (TEM), DSC, and TGA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 749–757, 2004
User information‐seeking behavior in a medical Web portal environment: A preliminary study
Authors: Zhang Dongming , Zambrowicz Caroline , Zhou Hong , Roderer Nancy K.
Published: April 2004

The emergence of information portal systems in the past few years has led to a greatly enhanced Web‐based environment for users seeking information online. While considerable research has been conducted on user information‐seeking behavior in regular IR environments over the past decade, this paper focuses specifically on how users in a medical science and clinical setting carry out their daily information seeking through a customizable information portal system (MyWelch). We describe our initial study on analyzing Web usage data from MyWelch to see whether the results conform to the features and patterns established in current information‐seeking models, present several observations regarding user information‐seeking behavior in a portal environment, outline possible long‐term user information‐seeking patterns based on usage data, and discuss the direction of future research on user information‐seeking behavior in the MyWelch portal environment.
On the Web at home: Information seeking and Web searching in the home environment
Authors: Rieh Soo Young
Published: April 2004

As more people gain at‐home access to the Internet, information seeking on the Web has become embedded in everyday life. The objective of this study was to characterize the home as an information use environment and to identify a range of information seeking and Web‐search behaviors at home. Twelve Northern California residents were recruited, and the data were collected through semi‐structured at‐home interviews based on a self‐reported Search Activities Diary that subjects kept over a 3–5 day period. The data were analyzed on four levels: home environment, information seeking goals, information retrieval interaction, and search query. Findings indicated that the home, indeed, provided a distinct information use environment beyond physical setting alone in which the subjects used the Web for diverse purposes and interests. Based on the findings, the relationships among home environment, Web context, and interaction situation were identified with respect to user goals and information‐seeking behaviors.
New fadB homologous enzymes and their use in enhanced biosynthesis of medium‐chain‐length polyhydroxyalkanoates in fadB mutant Escherichia coli
Authors: Jae Park Si , Yup Lee Sang
Published: April 2004

Recombinant Escherichia coli harboring the medium‐chain‐length (MCL) polyhydroxyalkanoate (PHA) synthase gene has been shown to accumulate MCL‐PHAs from fatty acids when FadB is inactive. However, the enzymes in fadB mutant E. coli responsible for channeling the β‐oxidation intermediates to PHA biosynthesis have not been fully elucidated. Only recently, two enzymes encoded by yfcX and maoC have been found to be partially responsible for this. In this study, we identified five new FadB homologous enzymes in E. coli: PaaG, PaaF, BhbD, SceH, and YdbU, by protein database search, and examined their roles in the biosynthesis of MCL‐PHAs in an fadB mutant E. coli strain. Coexpression of each of these genes along with the Pseudomonas sp. 61‐3 phaC2 gene did not allow synthesis of MCL‐PHA from fatty acid in recombinant E. coli W3110, which has a fully functional β‐oxidation pathway, but allowed MCL‐PHA accumulation in an fadB mutant E. coli WB101. In particular, coexpression of the paaG, paaF, and ydbU genes resulted in a MCL‐PHA production up to 0.37, 0.25, and 0.33 g/L, respectively, from 2 g/L of sodium decanoate, which is more than twice higher than that obtained with E. coli WB101 expressing only the phaC2 gene (0.16 g/L). These results suggest that the newly found FadB homologous enzymes, or at least the paaG, paaF, and ydbU genes, are involved in MCL‐PHA biosynthesis in an fadB mutant E. coli strain and can be employed for the enhanced production of MCL‐PHA. © 2004 Wiley Periodicals, Inc.
Selective precipitation and recovery of xylanase using surfactant and organic solvent
Authors: Shin Youn‐Ok , Wahnon Daphne , Weber Martin E. , Vera Juan H.
Published: April 2004

The selective precipitation of xylanase from an aqueous phase containing mixtures of xylanase and cellulase was studied using an ionic surfactant as precipitating ligand and a polar organic solvent as recovery solvent. Of four ionic surfactants tested, sodium di‐(2‐ethylhexyl) sulfosuccinate (AOT) showed a complete removal of xylanase at pH 4.5. The recovery of xylanase from the xylanase‐AOT complex was a strong function of the type and the volume of the polar solvent and of the concentration of sodium acetate buffer in the final aqueous solution used to solubilize the recovered xylanase. With ethanol as a recovery solvent, a recovery of xylanase activity of 78 ± 10% was obtained. The cellulase activity in the recovered xylanase was below the detection limit. The results demonstrate that an ionic surfactant can recover enzymes from aqueous solutions without loss in their activity. © 2004 Wiley Periodicals, Inc.
Expression of a feedback‐resistant anthranilate synthase in Catharanthus roseus hairy roots provides evidence for tight regulation of terpenoid indole alkaloid levels
Authors: Hughes Erik H. , Hong Seung‐Beom , Gibson Susan I. , Shanks Jacqueline V. , San Ka‐Yiu
Published: April 2004

Different plant species produce a variety of terpenoid indole alkaloids, which are of interest as plant defensive secondary metabolites and as valuable pharmaceuticals. Although significant progress has been made, the mechanisms regulating the levels of this important class of compounds require continued elucidation. Previous precursor feeding studies have indicated that alkaloid accumulation can be improved during the exponential growth phase of hairy root cultures through enhanced tryptophan availability. To test this relationship, transgenic hairy root cultures of Catharanthus roseus were established with a glucocorticoid‐inducible promoter controlling the expression of an Arabidopsis feedback‐resistant anthranilate synthase alpha subunit. Enzyme assays demonstrated that the Arabidopsis alpha subunit is compatible with the native beta subunit and that anthranilate synthase activity is more resistant to tryptophan inhibition in induced than in uninduced extracts. The metabolic effects of expressing the feedback‐resistant anthranilate synthase alpha subunit were also dramatic. Over a 6‐day induction period during the late exponential growth phase, tryptophan and tryptamine specific yields increased from almost undetectable levels to 2.5 mg/g dry weight and from 25 μg/g to 267 μg/g dry weight, respectively. The greater than 300‐fold increase in tryptophan levels observed in these studies under certain induction conditions compares favorably with the fold increases obtained in previous constitutive expression studies. Despite the large increases in tryptophan and tryptamine, the levels of most terpenoid indole alkaloids were not significantly altered, with the exception of lochnericine, which increased 81% after a 3‐day induction period. These results suggest that terpenoid indole alkaloid levels are tightly controlled. © 2004 Wiley Periodicals, Inc.
Split time‐integration for low Mach number compressible flows
Authors: Lange H. C. de
Published: April 2004

In low‐Mach number flows the time‐integration is usually bounded by the stability of the acoustic fluxes. This poses a restriction to the maximum timestep. Integration of all fluxes on this time‐scale, leads to huge cpu times. To decrease this problem a timestep splitting technique has been developed by which the acoustic, convective and diffusive fluxes are treated separately. The integration of each of the fluxes is bounded by their separate stability criteria. As an example, the time‐integration technique will be applied to a temporally developing mixing layer. The results show that the proposed splitted integration technique, applied at a Mach number of 0.2, reduces the cpu time by about a factor three. Furthermore, it will be shown that the technique may also be applied at low (0.05) Mach number flows. Here, the cpu‐reduction reaches its maximum of about a factor of four. Copyright © 2004 John Wiley & Sons, Ltd.
Solution of two‐dimensional Poisson problems in quadrilateral domains using transfinite Coons interpolation
Authors: Provatidis Christopher G.
Published: April 2004

This paper proposes a global approximation method to solve elliptic boundary value Poisson problems in arbitrary shaped 2‐D domains. Using transfinite interpolation, a symmetric finite element formulation is derived for degrees of freedom arranged mostly along the boundary of the domain. In cases where both Dirichlet and Neumann boundary conditions occur, the numerical solution is based on bivariate Coons interpolation using the boundary only. Furthermore, in case of only Dirichlet boundary conditions and no existing axes of symmetry, it is proposed to use at least one internal point and apply transfinite interpolation. The theory is sustained by five numerical examples applied to domains of square, circular and elliptic shape. Copyright © 2004 John Wiley & Sons, Ltd.
CD8α is an activation marker for a subset of peripheral CD4 T cells
Authors: Kenny Emma , Mason Don , Saoudi Abdelhadi , Pombo Ana , Ramírez Francisco
Published: April 2004

Rat CD4 T lymphocytes express CD8α upon activation. Here, we show that double‐positive cells express CD8α α homodimers, and we study their phenotype and function. Most activated CD4+ lymphocytes expressing CD8α are recent thymic emigrants. Accordingly, most activated CD4 single‐positive thymocytes express CD8α, and thymectomy and aging decrease the frequency of CD4+CD8α+ lymphocytes. However, CD8 induction is not restricted to CD4+ recent thymic emigrants. CD4+CD8α+ and CD4+CD8α–cells were generated in vitro from naive or from primed donors and, to study their function, were transferred to normal rats. Both cell types helped primary humoral responses, but only CD4+CD8α– cells promoted secondary responses. Thus, memory CD4 T cells mediating antibody responses and some naive CD4+ lymphocytes do not express CD8α. In addition, CD4+CD8α+ cells produce mainly Th1 cytokines while CD4+CD8α– cells produce IL‐10 and showed a sustained proliferative response. Hence, CD8α expressionafter activation distinguishes two distinct CD4 T cell subsets.
Perforin and IFN‐γ do not significantly regulate the virus‐specific CD8+ T cell response in the absence of antiviral effector activity
Authors: Christensen Jeanette E. , Wodarz Dominik , Christensen Jan P. , Thomsen Allan R.
Published: April 2004

Using gene‐targeted mice we have investigated whether perforin and/or interferon‐γ exert a direct regulatory effect on the expansion and contraction of antigen‐specific CD8+ T cells following infection with a virus (vesicular stomatitis virus) which is not controlled through these molecular effector systems. Unlike what has been observed when these molecules are essential for pathogen clearance, neither molecule was found to play an important role in regulating the kinetics of the virus‐specific CD8+ T cell response in the absence of antiviral effector activity.
Fertility pattern does not explain social gradient in breast cancer in denmark
Authors: Danø Hella , Hansen Kasper Daniel , Jensen Per , Petersen Jørgen Holm , Jacobsen Rune , Ewertz Marianne , Lynge Elsebeth
Published: April 2004

The present study was undertaken to assess the impact of reproductive behavior on the social class gradient in breast cancer occurrence in Denmark. Objectives were to study whether the gradient across socioeconomic groups could be explained by fertility differences, whether the gradient across educational groups could be explained by fertility differences and whether the effect of socioeconomic group on breast cancer incidence and mortality could be explained by education and vice versa. We studied 674,084 women aged 20–39 at the census on 9 November 1970 for whom we had complete data on fertility history. The cohort was followed up for breast cancer incidence and mortality until 8 November 1998. Fertility history varied considerably across socioeconomic group, where 38% of the academics were childless at the age of 30, in contrast to only 8% of women in agriculture. The academics had the highest risk of breast cancer and women in agriculture had the lowest risk. For incidence, the gradient in the relative risks was 1.74, which changed to 1.49 when fertility history was incorporated and to 1.29 when school education was also taken into account. For school education, women with ≥ 12 years of schooling had the highest risk and women with ≤ 7 years of schooling had the lowest risk. For incidence, the gradient in the relative risk was 1.38, which changed to 1.26 when fertility history was incorporated and to 1.22 when socioeconomic group was also taken into account. © 2004 Wiley‐Liss, Inc.
Intratumor chromosomal heterogeneity in advanced carcinomas of the uterine cervix
Authors: Lyng Heidi , Beigi Marzieh , Svendsrud Debbie H. , Brustugun Odd T. , Stokke Trond , Kristensen Gunnar B. , Sundfør Kolbein , Skjønsberg Ane , De Angelis Paula M.
Published: April 2004

Intratumor heterogeneity in chromosomal aberrations is believed to represent a major challenge in the treatment of cancer. The aim of our work was to assess the chromosomal heterogeneity of advanced cervical carcinomas and to distinguish aberrations that had occurred at a late stage of the disease from early events. A total of 55 biopsies, sampled from 2–4 different sites within 20 tumors, were analyzed by use of comparative genomic hybridization. Heterogeneous aberrations were identified as those present in at least 1 of the biopsies and which were not seen, nor seen as a tendency, in the others of the same tumor. The homogeneous aberrations were those seen in all biopsies of the tumor. The most frequent homogeneous aberrations were gain of 3q (65%), 20q (65%) and 5p (50%), indicating that these are early events in the development of the disease. Chromosomal heterogeneity was observed in 11 tumors. The most frequent heterogeneous aberrations were loss of 4p14–q25 (60% of 10 cases with this aberration), and gain of 2p22–pter (50% of 6 cases), 11qcen–q13 (33% of 9 cases) and 8q (27% of 11 cases), suggesting that these events promote progression at a later stage. Many of the heterogeneous regions contained genes known to influence the prognosis of cervical cancer, such as 7p (EGFR), 8q (c‐MYC), 11qcen‐q13 (CCND1) and 17q (ERBB2). Three evolution sequences for the subpopulations in the heterogeneous tumors were identified: a serial, a parallel and a mixed sequence. In 2 tumors with a serial sequence, it was indicated that the aberrations +8 and −X had occurred after the other heterogeneous aberrations and hence were the aberrations most recently formed. Our results suggest pronounced chromosomal instability in advanced cervical carcinomas. Moreover, aggressive and treatment‐resistant subpopulations may emerge at a late stage and possibly contribute to a poor prognosis of the advanced stages. © 2004 Wiley‐Liss, Inc.
Carcinoembryonic antigen induction of IL‐10 and IL‐6 inhibits hepatic ischemic/reperfusion injury to colorectal carcinoma cells
Authors: Jessup John Milburn , Laguinge Luciana , Lin Shuling , Samara Raed , Aufman Kimberly , Battle Paul , Frantz Marilyn , Edmiston Kirsten H. , Thomas Peter
Published: April 2004

Tumor cells cause ischemia/reperfusion (I/R) injury as they arrest within the hepatic microvasculature with the production of nitric oxide (NO) and reactive oxygen species (ROS) that kill both host liver and implanting tumor cells. Carcinoembryonic antigen (CEA) both facilitates the survival of experimental metastasis to nude mouse liver by weakly metastatic human colorectal carcinomas (CRCs) and induces the release of the proinflammatory cytokine IL‐6. We hypothesized that CEA also stimulates the release of the antiinflammatory cytokine IL‐10 causing inhibition of the toxicity of hepatic I/R injury and indirect stimulation of tumor cell colonization of the liver. Intravenous injection of CEA produced more than 1 ng/ml of IL‐10 in the systemic circulation within 1 hr which subsided by 8 hr. The IL‐10 response is specific to CEA since the pentapeptide sequence in CEA that binds to the CEA receptor stimulated isolated Kupffer cells to produce IL‐10. IL‐10, but not IL‐6, increased the survival of weakly metastatic CRC cocultured with ischemic‐reoxygenated liver fragments but did not affect the survival of CRC exposed to oxidative stress in the absence of any host cells. CEA, IL‐6 and IL‐10 pretreatment reduced expression of iNOS but only CEA and IL‐10 strongly inhibited NO and total reactive species production by ischemic‐rexoygenated liver. IL‐6 was toxic to CRC exposed to oxidative stress while IL‐10 did not have a direct effect on CRC. Thus, CEA stimulates production of IL‐10 that may enhance metastasis by promoting the ability of circulating CRC cells to survive the I/R injury of implantation. © 2004 Wiley‐Liss, Inc.
Oral lactoferrin inhibits growth of established tumors and potentiates conventional chemotherapy
Authors: Varadhachary Atul , Wolf Jeffrey S. , Petrak Karel , O'Malley Bert W. , Spadaro Michela , Curcio Claudia , Forni Guido , Pericle Federica
Published: April 2004

In this work, we investigated the anticancer activity of orally administered recombinant human lactoferrin (rhLF) alone and in combination with chemotherapy in tumor‐bearing mice. rhLF inhibited the growth of squamous cell carcinoma (O12) tumors in T cell–immunocompromised nu/nu mice by 80% when administered at 1,000 mg/kg (2.9 g/m2) by oral gavage twice daily for 8 days (p < 0.001). Similar activity was observed in syngeneic, immunocompetent BALB/c mice, where orally administered rhLF (1,000 mg/kg, 2.9 g/m2 once daily) halted the growth of mammary adenocarcinoma TUBO. Oral rhLF (200 mg/kg, 0.57 g/m2) was also used alone and in combination with cis‐platinum (5 mg/kg) to treat head‐and‐neck squamous cell carcinoma in a syngeneic murine model. Monotherapy with oral rhLF or cis‐platinum caused 61% or 66% tumor growth inhibition over placebo, respectively. Mice receiving both therapies showed 79% growth inhibition, a statistically significant improvement over each drug alone. We then demonstrated that administration of oral rhLF (300 mg/kg, 0.86 g/m2) to tumor‐bearing or naive mice resulted in (i) significantly increased production of IL‐18 in the intestinal tract, (ii) systemic NK cell activation and (iii) circulating CD8+ T‐cell expansion. These data suggest that oral rhLF is an immunomodulatory agent active against cancer as a single agent and in combination chemotherapy, exerting its systemic effect through stimulation of IL‐18 and other cytokines in the gut enterocytes. rhLF has been administered orally to 211 people without a single serious drug‐related adverse event. Thus, rhLF shows promise as a safe and well‐tolerated novel immunomodulatory anticancer agent. © 2004 Wiley‐Liss, Inc.
Do Protozoa Control the Elimination of Vibrio choleraein Brackish Water?
Authors: Martínez Pérez María Elena , Macek Miroslav , Castro Galván María Teresa
Published: April 2004

Elimination of inoculated Vibrio cholerae (≥107 cells ml−1) within a brackish water bacteria assemblage (Mecoacán Lagoon, State of Tabasco, Mexico) was studied in laboratory microcosms with filtration‐fractionated water. Feeding of a ciliate, Cyclidium glaucoma was evaluated using fluorescently labelled V. cholerae o1. Even though V. cholerae was not exploited as the major food source, ciliates were able to eliminate it efficiently. An addition of chitin directly supported the growth of bacteria, although not so much of V. cholerae, and indirectly the growth of the protistan assemblage. Generally, the changes in a bacterial assemblage structure were the most important in V. cholerae elimination.
Determinants of Benthic Diatom Community Structurein Boreal Streams: the Role of Environmental and Spatial Factors at Different Scales
Authors: Soininen Janne
Published: April 2004

Benthic diatoms were sampled at 197 sites in Finnish boreal streams. The diatom distribution patterns were related to environmental and spatial factors at three spatial scales using Canonical Correspondence Analysis (CCA). The results emphasized the predominance of chemical‐constituent concentration and ion composition on structuring benthic diatom communities in running waters. Within a river system, physical factors had notable influence on diatom community structure reflecting mainly only minor changes in water chemistry within a watershed. Partial CCA revealed that pure spatial component explained ca. 20% of explainable variation in diatom data at each of the three scales. Environmental factors captured 53–78% of explained variation in species data at ecoregion and river system level. According to Procrustean Randomization Test, spatial coordinates of the study sites and patterns in diatom community structure were strongly concordant (m2 = 0.862, p = 0.001) across the largest spatial scale. Similarly, at smaller spatial scales in southern and central Finland, congruence was significant. These data support the view that diatom communities exhibit a rather strong spatial component especially at largest, national scale.
Identification of Pseudomonas aeruginosa, Burkholderia cepacia complex, and Stenotrophomonas maltophilia in respiratory samples from cystic fibrosis patients using multiplex PCR
Authors: da Silva Filho Luiz V.F. , Tateno Adriana F. , Velloso Luciana de F. , Levi José E. , Fernandes Silvana , Bento Christina N.O. , Rodrigues Joaquim C. , Ramos Sonia R.T.S.
Published: April 2004

A multiplex PCR method was developed to identify P. aeruginosa, B. cepacia complex, and S. maltophilia directly in sputum and oropharyngeal samples from CF patients. One hundred and six patients (53 male, and 53 female) attending our pulmonology clinic were studied from September 2000–April 2001. Two hundred and fifty‐seven samples were cultured in selective media and submitted to multiplex PCR reactions, using three primer pairs targeting specific genomic sequences of each species, with an additional primer pair targeting a stretch of ribosomal 16S DNA, universal for bacteria, to act as a control. P. aeruginosa was isolated by culture in 56% of samples, B. cepacia complex in 4.3%, and S. maltophilia in 2.7%, while multiplex PCR identified P. aeruginosa in 78.7%, B. cepacia complex in 3.9%, and S. maltophilia in 3.1% of samples. Multiplex PCR results were verified by PCR reactions using different species‐specific primers described in the literature and DNA sequencing of amplicons from a few samples. Comparing to culture results, the sensitivity and specificity values of multiplex PCR for bacterial identification were, respectively, 97.2% and 45.5% for P. aeruginosa, 45.5% and 97.9% for B. cepacia complex, and 40% and 97.6% for S. maltophilia. All 10 multiplex PCR‐positive results for B. cepacia complex were confirmed using other species‐specific primers described in the literature, while this approach confirmed results for S. maltophilia identification in 7/8 samples (87.5%). Sequencing of amplicons from samples culture‐negative but multiplex PCR‐positive for P. aeruginosa and B. cepacia complex confirmed their identity, while minor nucleotide differences among amplicons ruled out the hypothesis of PCR contamination. Pediatr Pulmonol. 2004; 37:537–547. © 2004 Wiley‐Liss, Inc.