bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Behaviour of Stainless Steel Plates in PEMFC Working Conditions
Authors: Agneaux A. , Plouzennec M. H. , Antoni L. , Granier J.
Published: November 2005

Stainless steels commonly used as bipolar plates in PEMFC may corrode and produce metallic ions in anodic and cathodic media. In order to avoid or to limit as low as possible these pollutions, which reduce the fuel cell efficiency, studies are performed to understand occurring phenomena. The characterizations of the different stainless steels behaviour are obtained by means of electrochemical techniques in synthetic solutions representative of anodic and cathodic media.
Synthesis and Reactions of 1,4‐Anhydrogalactopyranose and 1,4‐Anhydroarabinose – Steric and Electronic Limitations
Authors: Nokami Toshiki , Werz Daniel B. , Seeberger Peter H.
Published: November 2005

Scope and limitations of 1,4‐anhydro sugars as precursors of glycofuranosyl building blocks are described. The experiments revealed that the choice of the substituents is very important for an efficient preparation as well as a successful ring‐opening reaction of 1,4‐anhydro sugars. DFT Calculations suggest that selective protonation of 1,4‐anhydro sugars is the key to the selective ring opening in order to afford only furanosides.
An Unusual β‐Oxidation of N‐Functionalized Alkyl Chains by 1H‐Imidazole
Authors: Langhals Heinz , Gold Josef
Published: November 2005

The 1H‐imidazole‐mediated condensation of primary aliphatic amines with perylene‐3,4 : 9,10‐tetracarboxylic bis‐anhydride resulted in by‐products where the aliphatic group was functionalized in the β‐position by imidazole units.
Synthesis of the Antibiotic (R)‐Reutericyclin via Dieckmann Condensation
Authors: Böhme Roswitha , Jung Günther , Breitmaier Eberhard
Published: November 2005

(R)‐Reutericyclin ((R)‐1), a bactericidal, amphiphilic natural product with a trisubstituted tetramic acid moiety, was prepared in four steps from D‐leucine in an overall yield of 24%. The chiral heterocyclic portion of 1 was synthesized by Dieckmann cyclization of ethyl N‐(acetoacetyl)leucinate (7), and the resulting pyrrole derivative 8 was N‐acylated with (E)‐dec‐2‐enoyl chloride in the presence of BuLi at − 70° (Scheme 2). This new procedure is straightforward and allows the synthesis of both antipodes of reutericyclin in an enantiomeric excess (ee) of ca. 80%.
Influence of the 4‐Substituted Pyridine Ligand L′ on both the Conformation and Spectroscopic Properties of the (2,2′‐Biquinoline‐κN1,κN1′)tricarbonyl(pyridine‐κN1)rhenium(1+) Complex ([Re(CO)3‐(bqui)(py)]+) and Its Derivatives [Re(CO)3(L)(L′)]+ (L = 2,2′‐Biquinoline and 3,3′‐(Ethane‐1,2‐diyl)‐2,2′‐biquinoline)
Authors: Moya Sergio A. , Guerrero Juan , Rodriguez‐Nieto Felipe J. , Wolcan Ezequiel , Féliz Mario R. , Baggio Ricardo F. , Garland María T.
Published: November 2005

A series of new rhenium(I) complexes of the type [ReI(CO)3(L)(L′)]n+ (L = 2,2′‐biquinoline (bqui) or 3,3′‐(ethane‐1,2‐diyl)‐2,2′‐biquinoline (CH2CN2)bqui); L′ = CF3SO$\rm{_3^ - }$, pyridine (py), or 4‐substituted pyridine (HOpy, Bzpy, or NCpy); n = 0 or 1) were prepared and characterized by FT‐IR, 1H‐NMR, UV/VIS and emission spectroscopy, luminescence lifetimes, and cyclic voltammetry. The pseudo‐octahedral facial configuration was established by X‐ray single‐crystal diffraction analysis of two complexes and by a FT‐IR study of all complexes. The [Re(CO)3(bqui)(Bzpy)](CF3SO3) complex crystallizes in the form of two mirror isomers arising from the conformational mobility of the biquinoline ligand. A correlation between the metal‐to‐ligand charge‐transfer (MLCT) emission maxima and the σ+ Hammett parameter was established for the complexes of the bqui series, while such correlation was not observed for the complexes of the (CH2CH2)bqui series. No correlation between oxidation potentials and the Hammett parameters was established. The results were rationalized in function of the effect of the 4‐substituted pyridine ligand on the octahedral distortion and conformational characteristic of the complexes. The 1H‐NMR data confirmed these results.
Four 6H‐Dibenzo[b,d]pyran‐6‐one Derivatives Produced by the Endophyte Cephalosporium acremonium IFB‐E007
Authors: Zhang Hua‐Wei , Huang Wu‐Yang , Song Yong‐Chun , Chen Jing‐Rong , Tan Ren‐Xiang
Published: November 2005

Two novel 6H‐dibenzo[b,d]pyran‐6‐one derivatives, graphislactone G (1) and graphislactone H (2), besides graphislactone A (3) and alternariol monomethyl ether (4) were isolated from the CHCl3/MeOH 1 : 1 extract of the solid‐substrate culture of Cephalosporium acremonium IFB‐E007, an endophytic fungus in Trachelospermum jasminoides (Lindl.) Lem. The structures of compounds 1 and 2 were unambiguously established as 2‐chloro‐7‐hydroxy‐3,9‐dimethoxy‐1‐methyl‐6H‐dibenzo[b,d]pyran‐6‐one and 7‐hydroxy‐3,4,9‐trimethoxy‐1‐methyl‐6H‐dibenzo[b,d]pyran‐6‐one, respectively, by a combination of spectroscopic analyses. Compound 1 was unique in its bearing a Cl‐atom. Anticancer tests showed that compounds 1–4 had pronounced activities against SW1116 cell with IC50 values of 21, 12, 8.5, and 14 μg ml−1, respectively.
Design and Synthesis of Novel Artemisinin‐Like Ozonides with Antischistosomal Activity
Authors: Yang Zhong‐Shun , Wu Wen‐Min , Li Ying , Wu Yu‐Lin
Published: November 2005

To develop new drugs for prevention and treatment of schistosomiasis, a series of novel artemisinin‐like ozonides 10 were synthesized via a facile three‐step procedure starting with the degraded product of artemisinin (Scheme). The Criegee ozonolysis reaction of the unsaturated lactone intermediates 14 is the key step which provided the target molecules 10. The in vivo pharmacological results suggested that this type of artemisinin analogues exhibited moderate antischistosomal activity (Table).
New Phenolic Components from Daphne giraldii
Authors: Liao Shang‐Gao , Zhang Bang‐Le , Wu Yan , Yue Jian‐Min
Published: November 2005

Two new bis‐coumarins, namely daphnogitin (1), daphnogirin (2), and a flavan‐3‐ol derivative, 5‐O‐methylafzelechin (3), together with eleven known compounds, daphnetoxin, 1,2‐dihydrodaphnetoxin, daphnetin, daphnoretin, daphneticin, isodaphneticin, trans‐2,3‐dihydro‐3‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐(hydroxymethyl)‐9H‐pyrano[2,3‐f]‐1,4‐benzodioxin‐9‐one (= demethoxyisodaphneticin; 4b), (+)‐pinoresinol, acuminatin, (−)‐dihydrosesamin, and isosalicifoline, were isolated from the leaves and stems of Daphne giraldii. Compound 4b was isolated for the first time as a natural product, and 1,2‐dihydrodaphnetoxin, daphneticin, isodaphneticin, (+)‐pinoresinol, acuminatin, (−)‐dihydrosesamin, and isosalicifoline were isolated for the first time from Daphne giraldii. The structures of the three new compounds were elucidated by spectroscopic analysis.
Synthesis of Substituted Pyrrolo[3,4‐a]carbazoles
Authors: Bleile Michaela , Wagner Trixie , Otto Hans‐Hartwig
Published: November 2005

The cycloaddition between N‐protected 3‐{1‐[(trimethylsilyl)oxy]ethenyl}‐1H‐indoles and substituted maleimides (= 1H‐pyrrole‐2,5‐diones) yielded substituted pyrrolo[3,4‐a]carbazole derivatives bearing an additional succinimide (= pyrrolidine‐2,5‐dione) moiety either at C(5a) or C(10b) depending on the type of the protection group at the indole N‐atom. Derivatives substituted at C(10b) were isolated when the protection group, Me3Si or Boc (tBuOCO), was eliminated during the reaction (Schemes 2 and 3), whereas a substitution at C(5a) was observed when an electron‐withdrawing group, Tos (4‐MeC6H4SO2) or pivaloyl (Me3CCO), was not eliminated (Scheme 1). Complex results were found in reactions between 1‐(trimethylsilyl)‐3‐{1‐[(trimethylsilyl)oxy]ethenyl}‐1H‐indole, in contrast to formerly reported results (Scheme 3). Some derivatives of 1H,5H‐[1,2,4]triazolo[1′,2 : 1,2]pyridazino[3,4‐b]indole‐1,3(2H)‐dione were obtained from reactions with 4‐phenyl‐3H‐1,2,4‐triazole‐3,5(4H)‐dione (Scheme 2). All structures were established by spectroscopic data, by calculations, and one representative structure was confirmed by an X‐ray crystallographic analysis (Fig.). Finally, the formation of the different structure types was discussed, and compared with similar reactions reported in the literature.
Spiro‐biflavonoids from Larix olgensisHenry var. koreanaNakai
Authors: Yang Bao‐Hua , Zhang Wei‐Dong , Liu Run‐Hui , Tan Chang‐Heng , Li Ting‐Zhao , Zhang Chuan , Xu Xi‐Ke , Su Juan
Published: November 2005

Four new spiro‐biflavonoids, named olgensisinols A–D (1–4), along with a known one, vitisinol (5), were isolated from the stem bark of Larix olgensis Henry var. koreana Nakai. Their structures were established on the basis of spectroscopic analysis and molecular‐model studies.
Spontaneous Aminoacylation of a RNA Sequence Containing a 3′‐Terminal 2′‐Thioadenosine
Authors: Porcher Sébastien , Meyyappan Muthuppalaniappan , Pitsch Stefan
Published: November 2005

We report the synthesis of a modified 8mer RNA sequence, (C‐C‐C‐C‐A‐C‐C‐(2′‐thio)A)‐RNA 5′‐(dihydrogen phosphate) (9) containing a 3′‐terminal 2′‐thioadenosine (Schemes 2 and 3), and its spontaneous and site‐specific aminoacylation with the weakly activated amino acid thioester HPheSPh (12). This reaction, designed in analogy to the ‘native chemical ligation’ of oligopeptides, occurs efficiently in buffered aqueous solutions and under a wide range of conditions (Table). At pH values between 5.0 and 7.4, two products, the 3′‐O‐monoacylated and the 3′‐O,2′‐S‐diacylated RNA sequences 10 and 11 are formed fast and quantitatively (Scheme 4). At pH 7.4 and 37°, the 3′‐O‐monoacylated product 10 is formed as major product in situ by selective hydrolysis of the O,S‐diacylated precursor 11. Additionally, the preparation and isolation of the relevant 3′‐O‐monoacylated product 10 was optimized at pH 5. The here presented concept could be employed for a straightforward aminoacylation of analogously modified tRNAs.
New Resveratrol Oligomers from the Stem Bark of Hopea hainanensis
Authors: Liu Jun Y. , Ye Yong H. , Wang Lei , Shi Da H. , Tan Ren X.
Published: November 2005

Three new resveratrol oligomers, hopeahainanphenol (1), neohopeaphenol A (2), and neoisohopeaphenol A (3), were isolated from the stem bark of Hopea hainanensis (Dipterocarpaceae). Their structures were elucidated by in‐depth spectroscopic analyses, including 1D‐ and 2D‐NMR techniques, and by HR‐ESI‐MS. All the three phytochemicals were tested in vitro for acetylcholinesterase (AChE) inhibitory and antitumor activity. The dimeric compound 2, which corresponds to (1S*,6S*,7S*,11bS*)‐1,6,7,11b‐tetrahydro‐1,7‐bis(4‐hydroxyphenyl)‐6‐[(1R*,6R*,7R*,11bR*)‐1,6,7,11b‐tetrahydro‐4,8,10‐trihydroxy‐1,7‐bis(4‐hydroxyphenyl)benzo[6,7]cyclohepta[1,2,3‐cd]benzofuran‐6‐yl]benzo[6,7]cyclohepta[1,2,3‐cd]benzofuran‐4,8,10‐triol, was found to be significantly active against AChE, with an IC50 value of 7.66 ± 0.13 μm.
Functionalised Monocyclic Five‐ to Seven‐Membered exo‐Glycals by Alkynol Cycloisomerisation of Hydroxy Buta‐1,3‐diynes and 1‐Haloalkynols
Authors: Xu Ming , Miao Zhiwei , Bernet Bruno , Vasella Andrea
Published: November 2005

Base‐promoted (KOH or MeONa in MeOH, or NaH in THF) cycloisomerisation of partially benzylated, 1‐substituted (R = PhCC, pyridin‐2‐yl, or Br) ald‐1‐ynitols leads to (Z)‐configured five‐, six‐, and seven‐membered exo‐glycals. The reactivity of the ald‐1‐ynitols depends upon their configuration. The ald‐1‐ynitols were derived from 2,3,5‐tri‐O‐benzyl‐D‐ribofuranose 1, and the corresponding, partially O‐benzylated galactose, glucose, and mannose hemiacetals by ethynylation. The hex‐1‐ynitol 2 derived from 1 (61%) was transformed via the 1‐phenylbuta‐1,3‐diyne 3 and the 1‐(pyridin‐2‐yl)acetylene 5 into the five‐membered exo‐glycals 4 and 6 (in 66 and 72% yields, resp., from 2). The analoguous ethynylation of 2,3,4,6‐tetra‐O‐benzyl‐D‐galactose 8 was accompanied by elimination of one benzyloxy (BnO) group to the hept‐3‐en‐1‐ynitol 9 (71%), which was transformed into the non‐5‐ene‐1,3‐diynitol 10 and further into the six‐membered exo‐glycal 11 (50% from 9). Addition of Me3SiCCH to the galactose 8 and to the gluco‐ and manno‐analogues 16 and 24 gave epimeric mixtures of the silylated oct‐1‐ynitols (86% of 12L/12D 45 : 55, 94% of 17L/17D 7 : 3, and 86% of 25L/25D 55 : 45), which were separated by flash chromatography, and individually transformed into the corresponding 1‐bromooct‐1‐ynitols. Upon treatment with NaH in THF, only the minor epimers 13L, 18D, and 26D cyclised readily to form the seven‐membered hydroxy exo‐glycals. They were acetylated to the more stable monoacetates 14L, 23D, and 28D (82–89% overall yield). Under the same conditions, the epimers 13D, 18L, and 26L decomposed within 12 h mostly to polar products. The difference of reactivity was rationalised by analysing the consequences of an intramolecular C(3)OH ⋅⋅⋅ −OC(7) H‐bond of the intermediate alkoxides on the orientation of −OC(7) of 13L, 18D, and 26D and its proximity to the ethynyl group.
Dolabellane Diterpenoids from the Higher Plant Aglaia odorata
Authors: Cai Xiang‐Hai , Luo Xiao‐Dong , Zhou Jun , Hao Xiao‐Jiang
Published: November 2005

Two new dolabellane diterpenoids, (1R,3R,7E,11S,12R)‐dolabella‐4(16),7‐diene‐3,18‐diol (1) and (1R,3E,7R,11S,12R)‐dolabella‐3,8(17)‐diene‐7,18‐diol (2), and the known (1R,3E,7E,11S,12R)‐dolabella‐3,7‐dien‐18‐ol (3) were isolated from Aglaia odorata, along with twelve other known compounds. Their structures were elucidated on the basis of spectroscopic data. This is the first time that dolabellane‐type diterpenoids were detected in higher plants.
Fascicularones H–K, Four New Sesquiterpenoids from the Cultured Mycelia of the Fungus Hypholoma fasciculare
Authors: Akasaka Hironari , Shiono Yoshihito
Published: November 2005

The AcOEt extract of Hypholoma fasciculare yielded four new congeners, fascicularones H (4), I (5), J (6), and K (7). All structures were unambiguously established by 1D and 2D NMR and MS data. In a lettuce seedling assay, compounds 4–7 showed radicle elongation.
A New 2H‐Azirin‐3‐amine as a Synthon for 2‐Methylaspartate
Authors: Brun Kathrin A. , Heimgartner Heinz
Published: November 2005

The synthesis of a novel 2,2‐disubstituted 2H‐azirin‐3‐amine 3a as a building block for racemic Asp(2Me) is described. This synthon contains an ester group in the side chain. The reaction of 3a with thiobenzoic acid and the amino acid Z‐Val‐OH yielded the racemic monothiodiamide 10a and the dipeptide 11 as a mixture of diastereoisomers, respectively (Scheme 2). In 11, each of the protecting groups was removed selectively (Scheme 3). First attempts toward the preparation of enantiomerically pure synthons for Asp(2Me) with a chiral auxiliary group in the side chain are described. Synthons 3b with a 1‐(naphthalen‐1‐yl)ethyl ester group and 3c with a menthyl ester group were prepared and reacted with thiobenzoic acid to form monothiodiamides 10b and 10c (Scheme 2). However, the diastereoisomers of the synthons 3b and 3c could not be separated by chromatography.
2‐Hydroxytorularhodin, a New Xanthophyll from the Red Yeast Sporobolomyces coprosmae
Authors: Weber Roland W. S. , Madhour Abderrahim , Anke Heidrun , Mucci Adele , Davoli Paolo
Published: November 2005

A new hydroxylated carotenoic acid was isolated from the red yeast Sporobolomyces coprosmae and unambiguously identified as 2‐hydroxytorularhodin (1), i.e., (all‐E)‐3′,4′‐didehydro‐2‐hydroxy‐β,ψ‐caroten‐16′‐oic acid, by application of extensive 1D and 2D NMR techniques (gCOSY, gHSQC, gHMBC, DQS, gTOCSY, and ROESY). Hydroxylation of carotenoids at C(2) is uncommon in nature, very rare in fungi, and unprecedented for torularhodin.
Design and Synthesis of Aminoglycoside Antibiotics to Selectively Target 16S Ribosomal RNA Position 1408
Authors: Pathak Rashmi , Böttger Erik C. , Vasella Andrea
Published: November 2005

The glucopyranosyl moiety (ring I) of paromomycin was modified in a search for novel aminoglycoside antibiotics. The key intermediates were the 4′,6′‐O‐benzylidenated N‐Boc derivative 3 and the azido analogue 18. The bromobenzoates 4 and 19 were prepared by treating the benzylidene acetals 3 and 18, respectively, with N‐bromosuccinimide (NBS), and the diol 8 was obtained by hydrogenolysis of 3. The C(6′)‐deoxy derivative 5 was obtained from 4 by treatment with Bu3SnH. Selective fluorodehydroxylation of 8 gave the fluoro derivative 9. The pseudotrisaccharide 13 was obtained by reductive fragmentaion of the iodo compound 12 obtained from the bromobenzoate 4. The 3′,6′‐anhydro derivative 20 was obtained upon deacetylation of 19. Standard deprotection gave the C(6′)‐deoxy compound 7, the fluoro compound 11, the pseudotrisaccharide 15, and the 3′,6′‐anhydro‐paromomycin 22. As compared to paromomycin, the C(6′)‐deoxy and fluorodeoxy derivatives 7 and 11 showed a lower activity against both wild type 1408A and 1408G mutant ribosomes. A lower activity was also found for the 3′,6′‐anhydro derivative 22 and for the pseudotrisaccharide 15.
Triterpene Saponins from Four Species of the Polygalaceae Family
Authors: Mitaine‐Offer Anne‐Claire , Miyamoto Tomofumi , Jolly Claire , Delaude Clément , Lacaille‐Dubois Marie‐Aleth
Published: November 2005

Twelve triterpene saponins were isolated by successive MPLC over silica gel from four species of Polygalaceae: From Polygala ruwenzoriensis, five new saponins 1–5 of which 1–4 as two pairs of (E)/(Z)‐isomers, together with the four known compounds tenuifoline, (E)‐ and (Z)‐senegasaponin b, (E)‐ and (Z)‐senegin II, and polygalasaponin XXVIII, from the genus Carpolobia, one new saponin 6 from C. alba and the known arilloside (11) from C. lutea, and another new triterpene glycoside 7 from Polygala arenaria. Their structures were established mainly by 600‐MHz 2D‐NMR techniques (1H,1H‐COSY, TOCSY, NOESY, HSQC, HMBC) as 3‐O‐(β‐D‐glucopyranosyl)presenegenin 28‐{O‐α‐L‐arabinopyranosyl‐(1 → 4)‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐O‐α‐L‐rhamnopyranosyl‐(1 → 2)‐4‐O‐[(E)‐4‐methoxycinnamoyl]‐β‐D‐fucopyranosyl} ester (1) and its (Z)‐isomer 2, 3‐O‐(β‐D‐glucopyranosyl)presenegenin 28‐{O‐α‐L‐arabinopyranosyl‐(1 → 4)‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐O‐α‐L‐rhamnopyranosyl‐(1 → 2)‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D‐fucopyranosyl} ester (3) and its (Z)‐isomer 4, 3‐O‐(β‐D‐glucopyranosyl)presenegenin 28‐[O‐β‐D‐galactopyranosyl‐(1 → 4)‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐O‐α‐L‐rhamnopyranosyl‐(1 → 2)‐β‐D‐fucopyranosyl] ester (5), 3‐O‐(β‐D‐glucopyranosyl)presenegenin 28‐{O‐α‐L‐arabinopyranosyl‐(1 → 3)‐O‐[β‐D‐galactopyranosyl‐(1 → 4)]‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐O‐α‐L‐rhamnopyranosyl‐(1 → 2)‐O‐[β‐D‐apiofuranosyl‐(1 → 3)]‐4‐O‐acetyl‐β‐D‐fucopyranosyl} ester (6), and 3‐O‐(β‐D‐glucopyranosyl)presenegenin 28‐{O‐β‐D‐galactopyranosyl‐(1 → 4)‐O‐[β‐D‐glucopyranosyl‐(1 → 3)]‐O‐β‐D‐xylopyranosyl‐(1 → 4)‐O‐α‐L‐rhamnopyranosyl‐(1 → 2)‐β‐D‐fucopyranosyl} ester (7) (presenegenin = (2β,3β,4α)‐2,3,27‐trihydroxyolean‐12‐ene‐23,28‐dioic acid).
Iodotrimethylsilane‐Accelerated One‐Pot Synthesis of 5‐Unsubstituted 3,4‐Dihydropyrimidin‐2(1H)‐ones: A Novel Procedure for the Biginelli‐Like Cyclocondensation Reaction at Room Temperature
Authors: Sabitha Gowravaram , Reddy Kusuma B. , Srinivas Rangavajjula , Yadav Jillu S.
Published: November 2005

A novel Biginelli‐like cyclocondensation reaction is efficiently catalyzed by iodotrimethylsilane (Me3SiI) in MeCN. The reaction proceeds at room temperature by a three‐component one‐pot condensation of ketones with aldehydes and urea to afford 5‐unsubstituted 3,4‐dihydropyrimidin‐2(1H)‐ones in good yields (Scheme 1 and Table).
Novel 1‐D Chains Constructed of Rings Which Include Six Metal Atoms [M2Au4] (M = Ni, Zn) with Aurophilic Interactions: Structure, Magnetic, and Spectral Studies
Authors: Wang Shu‐Ping , Song You , Gao Dong‐Zhao , Li Li‐Cun , Wang Qing‐Mei , Liao Dai‐Zheng , Jiang Zong‐Hui , Yan Shi‐Ping
Published: November 2005

Two novel 1‐D chain complexes of a formal iminomethyl nitroxide radical [M(tpyimo)2]2[Au(CN)2]4 (M = Ni, Zn for 1 and 2, typimo = 4,5‐dihydro‐4,4,5,5‐tetramethyl‐2‐(pyridin‐2‐yl)‐1H‐imidazol‐1‐yloxy), were synthesized and structurally characterized. Both 1‐D chains consist of two kinds of chair‐conformation rings, which include six metal atoms [M2Au4] (M = Ni, Zn), and are connected to each other alternately through aurophilic interactions. On the other hand, [Au(CN)$\rm{_2^ - }$]4 oligomers are also formed through aurophilic interactions, and used as bridges in the 1‐D chains. The magnetic coupling between the NiII ion and the tpyimo radical in 1 is a strong ferromagnetic interaction. Strong ligand‐centered luminescence is observed at room temperature for both complexes.
Chemical modification of SWNT alters in vitro cell‐SWNT interactions
Authors: Nimmagadda Aditya , Thurston Karen , Nollert Matthias U. , McFetridge Peter S.
Published: November 2005

Single‐walled carbon nanotubes (SWNT) have been the focus of considerable attention as a material with extraordinary mechanical and electrical properties. SWNT have been proposed in a number of biomedical applications, including neural, bone, and dental tissue engineering. In these applications, it is clear that surrounding tissues will come into surface contact with SWNT composites, and compatibility between SWNT and host cells must be addressed. This investigation describes the gross physical and chemical effects of different SWNT preparations on in vitro cell viability and metabolic activity. Three different SWNT preparations were analyzed: as purchased (AP‐NT), purified (PUR‐NT), and functionalized with glucosamine (GA‐NT), over concentrations of 0.001–1.0% (wt/vol). With the exception of the lowest SWNT concentrations, increasing concentrations of SWNT resulted in a decrease of cell viability, which was dependent on SWNT preparation. The metabolic activity of 3T3 cells was also dependent on SWNT preparation and concentration. These investigations have shown that these SWNT preparations have significant effects on in vitro cellular function that cannot be attributed to one factor alone, but are more likely the result of several unfavorable interactions. Effects, such as destabilizing the cell membrane, soluble toxic contaminants, and limitations in mass transfer as the SWNT coalesce into sheets, may all play a role in these interactions. Using comprehensive purification processes and modifying the NT‐surface chemistry to introduce functional groups or reduce hydrophobicity or both, these interactions can be significantly improved. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Mechanical stimuli and nutrients regulate rapamycin‐sensitive signaling through distinct mechanisms in skeletal muscle
Authors: Hornberger Troy A. , Chien Shu
Published: November 2005

The mammalian target of rapamycin (mTOR) has been identified as a growth factor and nutrient‐sensitive molecule that controls the translational machinery and cell growth. Rapamycin‐sensitive (RS) signaling events have also been shown to be necessary for mechanical load‐induced growth of skeletal muscle, but the mechanisms involved in the mechanical activation of RS signaling are not known. The finding that mechanical stimuli induce nutrient uptake in skeletal muscle raises the possibility that mechanically induced RS signaling is mediated via a nutrient‐dependent mechanism. To investigate this hypothesis, skeletal muscles (ex vivo) were stimulated with nutrients or intermittent mechanical stretch and the phosphorylation of p70S6k [P‐p70(389)], PKB [P‐PKB], mTOR [P‐mTOR(2481)], and p38 [P‐p38] was assessed. In comparison to vehicle‐treated controls, both nutrient and mechanical stimuli induced P‐p70(389), neither stimulus altered P‐PKB or P‐mTOR(2481), and only mechanical stimuli induced P‐p38. The nutrient and mechanically induced increase in P‐p70(389) was blocked by rapamycin, but only nutrient‐induced signaling to P‐p70(389) was blocked by wortmannin. Furthermore, the mechanically induced increase in P‐p70(389) was not impaired by the removal of exogenous nutrients. Taken together, these results indicate that exogenous nutrients are not required for mechanically induced RS signaling and that nutrient and mechanical stimuli activate RS signaling through distinct upstream mechanisms. J. Cell. Biochem. 97: 1207–1216, 2006. © 2005 Wiley‐Liss, Inc.
siRNA binding proteins of microglial cells: PKR is an unanticipated ligand
Authors: Zhang Zhiren , Weinschenk Toni , Guo Ketai , Schluesener Hermann J.
Published: November 2005

Small interfering RNA (siRNA), double‐stranded RNA (dsRNA) 21–23 nucleotides (nt) long with two nt 3′ overhangs, has been shown to mediate powerful sequence‐specific gene silence in mammalian cells through RNA interference (RNAi). Due to its high efficiency and high specificity siRNA has been used as a powerful post genomic tool and a potent therapeutic candidate. However, there is still a lot to learn about the mobility of siRNA inside cells and the cellular factors that might interfere with the specificity and activity of siRNA. Microglia are the brain's effector cells of the innate immune system and suitable targets in the development of novel therapeutic strategies. Here, we show the cellular uptake and intracellular distribution of siRNA in murine microglial N9 cells. siRNA was internalized by microglial N9 cells without transfection reagent and mainly localized to the endosomes However, no significant gene silencing effects were observed. Its cellular uptake and cellular distribution pattern were similar with that of a same length single stranded DNA (ssDNA). Further, cellular binding proteins of siRNA were purified and identified by mass spectrometry. Negative control siRNA and siRNA targeted to β‐actin were used in this part of experiment. Most of the siRNA binding proteins for negative control siRNA and siRNA targeted to β‐actin were dsRNA‐binding proteins, such as dsRNA‐dependent protein kinase R (PKR). Furthermore, both control siRNA and siRNA targeted to β‐actin activated PKR in N9 cells, which suggest that siRNA might cause off‐target effects through activation of PKR. J. Cell. Biochem. 97: 1217–1229, 2006. © 2005 Wiley‐Liss, Inc.
Structural specificity in a FGF7‐affinity purified heparin octasaccharide required for formation of a complex with FGF7 and FGFR2IIIb
Authors: Luo Yongde , Ye Sheng , Kan Mikio , McKeehan Wallace L.
Published: November 2005

Variations in sulfation of heparan sulfate (HS) affect interaction with FGF, FGFR, and FGF–HS–FGFR signaling complexes. Whether structurally distinct HS motifs are at play is unclear. Here we used stabilized recombinant FGF7 as a bioaffinity matrix to purify size‐defined heparin oligosaccharides. We show that only 0.2%–4% of 6 to 14 unit oligosaccharides, respectively, have high affinity for FGF7 based on resistance to salt above 0.6M NaCl. The high affinity fractions exhibit highest specific activity for interaction with FGFR2IIIb and formation of complexes of FGF7‐HS‐FGFR2IIIb. The majority fractions with moderate (0.30–0.6M NaCl), low (0.14–0.30M NaCl) or no affinity at 0.14M NaCl for FGF7 supported no complex formation. The high affinity octasaccharide mixture exhibited predominantly 7‐ and 8‐sulfated components (7,8‐S‐OctaF7) and formed FGF7–HS–FGFR2IIIb complexes with highest specific activity. Deduced disaccharide analysis indicated that 7,8‐S‐OctaF7 comprised of ΔHexA2SGlcN6S in a 2:1 ratio to a trisulfated and a variable unsulfated or monosulfated disaccharide. The inactive octasaccharides with moderate affinity for FGF7 were much more heterogenous and highly sulfated with major components containing 11 or 12 sulfates comprised of predominantly trisulfated disaccharides. This suggests that a rare undersulfated motif in which sulfate groups are specifically distributed has highest affinity for FGF7. The same motif also exhibits structural requirements for high affinity binding to dimers of FGFR2IIIb prior to binding FGF7 to form FGF7–HS–FGFR2IIIb complexes. In contrast, the majority of more highly sulfated HS motifs likely play FGFR‐independent roles in stability and control of access of FGF7 to FGFR2IIIb in the tissue matrix. J. Cell. Biochem. 97: 1241–1258, 2006. © 2005 Wiley‐Liss, Inc.
Photo‐degradation of hydrophobic esters of pyridinecarboxylic acids as copper extractants from chloride media and their copper complexes
Authors: Klonowska Karolina , Olszanowski Andrzej , Borowiak‐Resterna Aleksandra
Published: November 2005

The photo‐stability of hydrophobic esters of pyridine‐3‐carboxylic acid and pyridine‐3,5‐dicarboxylic acid containing 2‐ethylhexyl‐, octyl‐, and dodecyl‐substituents which are model extractants of copper from chloride media were studied together with the photo‐degradation of their copper complexes. The results indicate that UV light degraded the esters of both pyridine‐3,5‐dicarboxylic acid and pyridine‐3‐carboxylic acid. The degree of degradation depended on the structure of the ester, the type of solvent, and the presence of oxygen, water or hydrochloric acid in the solution during exposure to visible or UV‐visible light. Photo‐reactions between the solvent and the esters were also observed. Copper has a considerable influence on the photo‐stability of the esters. Copyright © 2005 Society of Chemical Industry
Equilibrium and kinetic studies on the extraction of gadolinium(III) from nitrate medium by di‐2‐ethylhexylphosphoric acid in kerosene using a single drop technique
Authors: El‐Hefny Naglaa E , El‐Dessouky Sahar I
Published: November 2005

The liquid–liquid extraction of Gd(III) from aqueous nitrate medium was studied using di‐2‐ethylhexylphosphoric acid (HDEHP) in kerosene. On the basis of the slope analysis data, the composition of the extracted species was found to be [Gd A3(HA)] with the extraction equilibrium constant (Kex) = (1.48 ± 0.042) × 10−12 mol dm−3. The results of the effect of temperature on the value of the equilibrium extraction constant indicated the endothermic character of the extraction system. The kinetics of the forward extraction of Gd3+ from nitrate medium by HDEHP in kerosene was investigated using the single drop column technique. The rate of flux (mass transfer per unit area) was found to be proportional to [Gd(III)], [H2A2](o), [NO3−], and [H+]−1 in the liquid drop organic phase. The forward extraction rate constant, kf, was 2.24 × 10−3 m s−1 using the equation:

Copyright © 2005 Society of Chemical Industry
Synthesis and application of dicationic ionic liquids
Authors: Liu Qingbin , van Rantwijk Fred , Sheldon Roger A
Published: November 2005

Ionic liquids were synthesised that consisted of two methylimidazolium rings joined by a spacer 1–12 carbon atoms in length. The bis(triflic)imides with spacer ≤C4 were solids; the others were liquid at room temperature. The polarity of the dication liquids and their performance in the extraction of phenol from water were compared with those of similar monocationic liquids. Copyright © 2005 Society of Chemical Industry
Degradation of cellulosic and hemicellulosic substrates using a chelator‐mediated Fenton reaction
Authors: Arantes Valdeir , Milagres Adriane Maria Ferreira
Published: November 2005

The involvement of catechol and hydroxamate chelators, along with hydrogen peroxide and Fe3+, in the degradation of cellulosic and hemicellulosic substrates was examined with the purpose of improving our current knowledge of the non‐enzymatic mechanisms involved in wood biodegradation by fungi. It could be demonstrated that a catechol chelator‐mediated Fenton reaction not only clearly degraded hemicellulosic substrates but also significantly accelerated and increased the effectiveness of degradation reactions. On the other hand, when a hydroxamate chelator‐mediated Fenton reaction was used, an inhibitory effect was observed. When cellulosic substrates underwent a chelator‐mediated Fenton reaction, no significant difference in degradation was observed between catechol and hydroxamate chelator‐mediated reactions. However, a catechol‐mediated reaction did accelerate the degradation of cellulosic substrates at the beginning of reactions. In addition, it was observed that with a chelator‐mediated Fenton reaction, oxidation of cellulose proceeds depolymerization. Copyright © 2005 Society of Chemical Industry
Effect of inoculation dosing on the composting of source‐selected organic fraction of municipal solid wastes
Authors: Barrena Raquel , Pagans Estela , Faltys Gary , Sánchez Antoni
Published: November 2005

The effects of a commercial inoculum (MicroGest 10X, Brookside Agra L.C.) on the field‐scale composting of the source‐selected organic fraction of municipal solid wastes (OFMSW) have been studied by following routine parameters of the composting process (temperature, oxygen content and moisture) and biologically‐related tests such as the respirometric index and the maturity grade. The inoculum was added to composting piles of OFMSW at different levels: control (no added inoculum), treatment A (105 CFU g−1 of OFMSW), treatment B (106 CFU g−1 of OFMSW) and treatment C (107 CFU g−1 of OFMSW). The inoculum selected produced a significant acceleration of the composting process with high levels of biological activity in the thermophilic phase. In terms of the acceleration of composting and economy the optimal treatment was B, which produced a reduction of approximately half of the total composting time. Treatment C did not improve significantly the results obtained with treatment B, whereas treatment A has little effect on the composting of OFMSW when compared with the control experiment. Respirometric index (determined at 55 °C) and maturity grade appeared to be the most reliable tests to follow the biological activity of the composting of OFMSW. On the other hand, routine parameters such as temperature, oxygen content and moisture showed no significant differences among the different inoculation levels tested in the composting process. Copyright © 2005 Society of Chemical Industry
Optimisation of the amino–carboxy coupling of oligonucleotides to beads used in liquid arrays
Authors: Wittebolle Lieven , Verstuyft Karmen , Verstraete Willy , Boon Nico
Published: November 2005

Interest is increasing in the multiplexed bead‐based method to detect nucleic acid quantities, using oligonucleotides (oligos) coupled to micrometre‐sized polystyrene beads. This paper describes an evaluation of this coupling step by examining different buffers at various pHs and the effect of changing the oligo concentration. The use of 2‐(N‐morpholino)ethanesulfonic acid (MES)–borate buffer (pH 4.5) during the effective coupling step yielded the best coupling efficiency. The addition of 15 pmol of oligo to 105 beads resulted in the highest number of coupled oligos per bead (∼336 ± 28 oligos µm−2). In addition, an alternative method to calibrate the fluorescence intensity by using FloSense Rainbow Calibration Particles was evaluated. In this way, it was possible to compare data independently of the type of flow cytometer used or the photomultiplier tube settings. Copyright © 2005 Society of Chemical Industry
Effect of ozonation on chemical oxygen demand fractionation and color profile of textile wastewaters
Authors: Doǧruel Serdar , Dulekgurgen Ebru , Orhon Derin
Published: November 2005

Filtration and ultrafiltration with a size range of 2–1600 nm were used to evaluate the effect of ozonation on the particle size distribution‐based chemical oxygen demand (COD) and color profiles of textile wastewater before and after biological treatment. Ozonation induced a net effect of 9% COD reduction in the influent and 15% in the effluent. However, a more in‐depth evaluation based on particle size distribution and mass balance for the influent revealed different mechanisms of ozonation, which were interpreted as total oxidation in the soluble range, replenishment of soluble COD through solubilization of organics into simpler compounds and polymerization towards the upper size range (>220 nm). For the biological treatment effluent, the greatest effect of ozonation was in the lower particle size range (<8 nm). Ozone was very effective for color removal, giving 80–93% optical density reductions in the influent and 96–99% in the effluent, depending on the excitation wavelength selected. Ozonation of the influent removed practically all color fractions, except in the particulate range. In the effluent, the particulate fraction was removed by biological treatment and settling and consequently the remaining color were almost entirely removed by ozonation. Copyright © 2005 Society of Chemical Industry
Purification of monoclonal antibodies from cell culture supernatants by Gradiflow™ electrophoresis technology
Authors: Mahler Stephen M , Leong Sharon , Gilbert Andrew , Yang Fan , Gray Peter , Dyk Derek Van , Roeth Philip
Published: November 2005

Monoclonal antibodies (mAbs) are used extensively for analytical, diagnostic and therapeutic applications. The purification of mAbs from cell culture supernatants typically consists of protein A, G or L affinity chromatography, often in association with other conventional chromatographic techniques such as ion exchange and gel filtration. We report the application of Gradiflow™ preparative electrophoresis technology, for the separation of mouse and mouse/human chimeric mAbs from cell culture supernatants in their native state. The one‐step purification of murine mAb HuLym3 shows that mAbs can be purified from hybridoma cell culture supernatants to high purity, and is thus an alternative to other purification methods based on conventional and affinity chromatography for the production of mAbs for analytical and diagnostic applications. A mouse/human IgG1 chimeric mAb produced by Chinese hamster ovary cells was also purified from cell culture supernatant, and the purity achieved suggests that Gradiflow™ electrophoresis could replace affinity chromatography in the downstream processing of mAbs for therapeutic use. Gradiflow™ electrophoresis technology is scaleable and thus is applicable to industrial‐scale purification of mAbs. Copyright © 2005 Society of Chemical Industry
Kinetic model for simultaneous cell disruption and aqueous two‐phase extraction
Authors: Chang Bingsheng , Su Zhiguo
Published: November 2005

A process of simultaneous cell disruption and aqueous two‐phase extraction demonstrated improved product yield and selectivity compared with the traditional process of cell disruption followed by extraction. Addition of aqueous two‐phase components did not decrease the efficiency of cell disruption. Moreover, ADH, LDH and G6PDH recovery was enhanced in this new process with recovery ratios of 97%, 93% and 95%, respectively. Cell disruption kinetics were established based on a new mechanism that was different from traditional first‐order kinetics, consisting of the release of intracellular proteins and enzymes, the denaturation and subsequent renaturation of these proteins that may be due to the protection of the aqueous two‐phase components during the cell disruption process. To account for this, the kinetics parameters were calculated, and the experimental data were regressed. The resulting kinetic model could provide a better fit for the experimental data with a correlation ratio of 99% (for total protein), and led to insights into the differences between the new process and the traditional one. Copyright © 2005 Society of Chemical Industry
Comparative studies of Oryza sativa L. husk and chitosan as lead adsorbent
Authors: Zulkali Mohamed Mohamed Daud , Ahmad Abdul Latif , Norulakmal Nor Hadi , Sharifah Nor Sulaiman
Published: November 2005

The adsorption capacity of two low‐cost adsorbents, Oryza sativa L. husk and chitosan, was studied. Lead solution was used as the adsorbate. The effect of initial lead concentration, pH, temperature, weight of adsorbent, particle size and contact time on lead uptake was investigated. It was found that the isotherm data were well described by the Freundlich isotherm for both adsorbents. The adsorption capacities of rice husk and chitosan were 5.69 and 8.31 mg g−1, respectively. It was shown that chitosan was more effective than rice husk. Copyright © 2005 Society of Chemical Industry
A single immunization with a minute dose of a lentiviral vector‐based vaccine is highly effective at eliciting protective humoral immunity against West Nile virus
Authors: Iglesias Maria Candela , Frenkiel Marie‐Pascale , Mollier Karine , Souque Philippe , Despres Philippe , Charneau Pierre
Published: November 2005

Background

Lentiviral vectors, due to their capacity to transduce non‐dividing cells, have become precious and worldwide used gene transfer systems. Their ability to efficiently and stably transduce dendritic cells (DCs) has led to their successful use as vaccination vectors for eliciting strong, specific and protective cellular immune responses mostly in anti‐tumoral but also in anti‐viral applications. However, the ability of lentiviral vectors to elicit an antibody‐based protective immunity has, to date, not been evaluated. In the present study, we evaluated the potential of a lentiviral vector‐based vaccine to elicit humoral immunity against West Nile virus (WNV). WNV is a mosquito‐borne flavivirus that emerged in North America and causes encephalitis in humans, birds and horses. Neutralizing anti‐WNV antibodies have been shown to be crucial for protection against WNV encephalitis.

Methods

The ability of lentiviral vector TRIP/sEWNV, expressing the secreted soluble form of the envelope E‐glycoprotein (sEWNV) from the highly virulent IS‐98‐ST1 strain of WNV, to induce a specific humoral response and protection against WNV infection was assessed in a mouse model of WNV encephalitis.

Results

Remarkably, a single immunization with a minute dose of TRIP/sEWNV was efficient at eliciting a long‐lasting, protective and sterilizing humoral immunity, only 1 week after priming.

Conclusions

This study broadens the applicability of lentiviral vectors as efficient non‐replicating vaccines against pathogens for which a neutralizing humoral response is one active arm of the protective immunity. The TRIP/sEWNV lentiviral vector appears to be a promising tool for veterinary vaccination against zoonotic WNV. Copyright © 2005 John Wiley & Sons, Ltd.
Interaction between complementary liposomes: a process leading to multicompartment systems formation
Authors: Paleos Constantinos M. , Tsiourvas Dimitris
Published: November 2005

Interaction of complementary liposomes induces a series of processes, involving reorganization of their membrane lipids, which lead to the formation of large aggregates. In several cases these aggregates exhibit multicompartment structures and only primitively mimic, in some aspects at least, the multicompartmental features of cells. Similar multicompartment structures were repeatedly obtained following the interaction of a diversity of complementary liposomal pairs. Thus, a working hypothesis is proposed, according to which, molecular recognition of liposomes induces the formation of multicompartment structures. Copyright © 2005 John Wiley & Sons, Ltd.
Characterization of prostate‐specific antigen binding peptides selected by phage display technology
Authors: Ferrieu‐Weisbuch Catherine , Michel Sandrine , Collomb‐Clerc Emilie , Pothion Catherine , Deléage Gilbert , Jolivet‐Reynaud Colette
Published: November 2005

Prostate‐specific antigen (PSA) is an important marker for the diagnosis and management of prostate cancer. Free PSA has been shown to be more extensively cleaved in sera from benign prostatic hyperplasia patients than in sera from prostate cancer patients. Moreover, the presence of enzymatically activatable PSA was characterized previously in sera from patients with prostate cancer by the use of the specific anti‐free PSA monoclonal antibody (mAb) 5D3D11. As an attempt to obtain ligands for the specific recognition of different PSA forms including active PSA, phage‐displayed linear and cyclic peptide libraries were screened with PSA coated directly into microplate wells or presented by two different anti‐total PSA mAbs. Four different phage clones were selected for their ability to recognize PSA and the inserted peptides were produced as synthetic peptides. These peptides were found to capture and to detect specifically free PSA, even in complex biological media such as sera or tumour cell culture supernatants. Alanine scanning of peptide sequences showed the involvement of aromatic and hydrophobic residues in the interaction of the peptides with PSA whereas Spotscan analysis of overlapping peptides covering the PSA sequence identified a peptide binding to the kallikrein loop at residues 82–87, suggesting that the peptides could recognize a non‐clipped form of PSA. Moreover, the PSA‐specific peptides enhance the enzymatic activity of PSA immobilized into microplate wells whereas the capture of PSA by the peptides inhibited totally its enzymatic activity while the peptide binding to PSA had no effect in solution. These PSA‐specific peptides could be potential tools for the recognition of PSA forms more specifically associated to prostate cancer. Copyright © 2005 John Wiley & Sons, Ltd.
Musculoskeletal tumors: Use of proton MR spectroscopic imaging for characterization
Authors: Fayad Laura M. , Bluemke David A. , McCarthy Edward F. , Weber Kristin L. , Barker Peter B. , Jacobs Michael A.
Published: November 2005

Purpose

To determine the value of multivoxel proton magnetic resonance spectroscopic imaging (MRSI) in distinguishing malignant skeletal tumors from benign tumors and normal bone marrow using the metabolite choline (Cho) as a marker for malignancy.

Materials and Methods

Pathologic specimens obtained from 13 patients who had undergone wide resection for skeletal tumors underwent evaluation by MRSI at 1.5 T. Coronal T1‐weighted gradient‐echo sequence obtained for localization purposes (TR/TE = 250/1.8 msec, field of view [FOV] = 18 × 18), and single‐slice MRSI (TR/TE = 2000/272 msec, FOV = 18 × 18, 10‐mm slice‐thickness) were performed. Water, lipid, and Cho images were reconstructed from MRSI data. Cho signal was measured in each specimen and expressed relative to background noise level (signal‐to‐noise ratio [SNR]) where noise was measured between 7.0 and 9.0 ppm. Cho SNRs were compared between areas containing malignant tumor and nonmalignant tissue (benign lesion or normal bone marrow) as determined by histopathology.

Results

Specimens included 13 skeletal sarcomas (seven osteosarcomas, three chondrosarcomas, one malignant fibrous histiocytoma, one fibrosarcoma, and one leiomyosarcoma). All specimens included a sample of normal bone marrow and two specimens also contained benign lesions. All sarcomas demonstrated a signal at 3.2 ppm assigned to Cho‐containing metabolites in areas of malignancy. Peak Cho SNR was significantly different for areas containing histologically‐proven malignancy compared to nonmalignant tissue (9.8 ± 5.1 vs. 2.7 ± 1.4, respectively, P < 0.002).

Conclusion

These preliminary results indicate that MRSI at 1.5 T is a promising noninvasive method of differentiating malignant skeletal tumors from nonmalignant tissue. Using MRSI, Cho can be detected in skeletal tumors and may serve as a marker for malignancy. J. Magn. Reson. Imaging 2006. © 2005 Wiley‐Liss, Inc.