bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Electrochemistry of the Monolacunary Dawson‐Type Tungstoarsenate [H4AsW17O61]11− and Some First‐Row Transition‐Metal Ion Derivatives
Authors: Mbomekalle Israel‐Martyr , Keita Bineta , Lu Yu Wei , Nadjo Louis , Contant Roland , Belai Nebebech , Pope Michael T.
Published: August 2004

The novel family of the Dawson‐type tungstomonoarsenate [H4AsW18O62]7− has been extended by preparing for the first time its monolacunary species and its first‐row transition‐metal ion substituted derivatives. All compounds were characterized by elemental analysis, IR and UV/Vis spectroscopy and representative examples by 183W NMR spectroscopy. Several lines of experimental evidence converge to indicate that the substitution occurs in the α2 position. The lacunary species, unlike its phosphorus analogue, was sufficiently stable for a few voltammetric runs. Therefore, the cyclic voltammetric properties of substituted compounds were studied as a function of pH and systematically compared with those of the lacunary precursor rather than with those of their analogues derived from the symmetrical species [As2W18O62]6−. The electrocatalytic properties of all compounds were illustrated by the reduction of nitrite by reduced [H4AsW18O62]7− and of nitrate by reduced α2‐[(H2O)Cu(H4AsW17O61)]9−. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Sequence‐Specific Oxidative Degradation of Tripeptides by a Cobalt(III) Complex Containing a Terpyridine Ligand
Authors: Jitsukawa Koichiro , Takahashi Hiroshi , Hyuga Ryoji , Arii Hidekazu , Masuda Hideki
Published: August 2004

A sequence‐specific oxidative degradation of an oligopeptide consisting of aliphatic amino acids was performed with a ternary cobalt(III) complex. Under aerobic conditions the reaction of [Co(CO3)(OH)(terpy)] and an equimolar amount of tripeptide at 40 °C at pH 8.5 gave two fraction bands (a and b) with water and then two bands (c and d) with NaCl solution, respectively, after column separation. In the case of gly‐gly‐leu (ggl, 1), [Co(gg′l)(terpy)] [1a, gg′l = glycyl(2‐oxoglycyl)leucine], [Co(g′l)(terpy)] [1b, g′l = N‐(2‐oxoglycyl)leucine], [Co(ggl)(terpy)]+ (1c), and [Co(terpy)2]3+ (1d) were obtained. The crystal structure of 1c, which was the main product, revealed that the starting ggl ligand was cleaved to give a bis‐amide compound, g′l, which might be generated by loss of N‐terminal glycine and carbonylation of the α‐carbon of the N‐2 glycine residue. Although the source of the oxygen of the newly generated carbonyl group is not clear, gg′l is supposed to be an intermediate for g′l on the basis of time‐dependent HPLC analyses. NMR investigation of other tripeptides [βala‐gly‐leu (2), gly‐gly‐phe (3), and gly‐gly‐ala (4)] containing a bulky C‐terminal aliphatic side chain indicated the formation of the corresponding oxidation complexes. On the other hand, peptides containing a C‐terminal glycine residue [gly‐gly‐gly (5) and phe‐gly‐gly (6)] or an N‐2 β‐alanine residue [gly‐βala‐leu (7)] did not give such a transformation product. The crystal structure of [Co(fgg)(terpy)] (6c) revealed that the tripeptide is coordinated to cobalt with a tridentate N‐terminal N‐N‐N geometry. Such sequence specificity demonstrated in the reaction of the aliphatic tripeptide complexes is interpreted by the interligand interaction between the side chain of the C‐terminal amino acid residue and terpy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Anion Binding of 1,1′‐Bis(dialkylboryl)cobaltocenium Complexes − Structures of [Co{C5H4(BMe2)}2]PF6, Co[C5H4(BMe2)][C5H4(BMe2Cl)], Co[C5H4(BiPr2)]2(µ‐F) and NMe4[Co{C5H4(BiPr2F)}2]
Authors: Herberich Gerhard E. , Englert Ulli , Fischer Andreas , Wiebelhaus Dag
Published: August 2004

The cobaltocenium salts [Co{C5H4(BiPr2)}2]PF6 [(1a)PF6] and [Co{C5H4(BMe2)}2]PF6 [(1b)PF6] are strong Lewis acids. With pyridine (1a)PF6 forms a mono‐adduct 2 and a di‐adduct 3 which show NMR spectra in the low‐temperature regime of pyridine exchange. With chloride from PPh4Cl the adduct formed is dynamic; quite remarkably, the formation of an anionic di‐adduct is also observed. The mono‐adducts (1a)X (X = F, Cl, Br, I, OH, and NH2) and (1b)X (X = F, Cl, and OH) as well as the di‐adduct salts NMe4[(1a)F2] (5) and K[(1a)(OH)2] (6) are made by treating the salts (1a,b)PF6 in CH2Cl2 or MeNO2 with salts PPh4X, NMe4F, or powders of NaNH2 or KOH in the appropriate ratios. X‐ray single‐crystal structures of the salt [Co{C5H4(BMe)2}2]PF6 [(1b)PF6], the semi‐quaternized mono‐adduct Co[C5H4(BMe2)][C5H4(BMe2Cl)] (4bd) [B−Cl = 1.969(2) Å], the inverse chelate Co[C5H4(BiPr2)]2(µ‐F) (4ac) with the very rare feature of fluorine bridging two boron centers [C2 symmetric; B−F = 1.641(4) Å, B−F−B′ = 148.4(3)°], and the doubly quaternized di‐adduct NMe4[Co{C5H4(BiPr2F)}2] (5) [exactly centrosymmetric; B−F = 1.477(4) Å] are given. Solution structures of the 1:1 products greatly depend on the nature of the anion, displaying i) exclusively ionic structures for (1a)PF6 and (1b)PF6, ii) semi‐quaternized structures for the heavier halides (1a)Br (4ae) and (1a)I (4af) with some noticeable ionic dissociation, iii) semi‐quaternized structures in equilibrium with minor amounts of inverse chelate isomers for (1a)F (4ac), (1b)Cl (4bd), and very likely for (1a)Cl (4ad), and iv) stable inverse chelate structures for Co[C5H4(BiPr2)]2(µ‐NH2) (4aa) (static in variable temperature NMR spectra, with diastereotopic Me groups), Co[C5H4(BR2)]2(µ‐OH) [4ab: R = iPr; 4bb: R = Me; dynamic; for 4ab Tc = 95 ± 5 °C, ΔG≠368 = 75(1) kJ·mol−1 for interchange of the diastereotopic Me groups], and Co[C5H4(BMe2)]2(µ‐F) (4bc). The stability of the inverse chelates decreases in the order amide (4aa) > hydroxides (4ab and 4bb) > fluorides (4ac and 4bc) > chlorides (4ad and 4bd), and also in the order BMe2 > BiPr2 (specifically 4bc > 4ac, and 4bd > 4ad). Variable temperature NMR spectra of solutions of 4bd (CD2Cl2, 173−243 K) show that i) the ring‐opening of the chelated chloride (ΔG≠368 ≈︁ 45 kJ·mol−1) is energetically easier than for the chelated hydroxide 4ab, ii) the predominance of the semi‐quaternized isomer over the inverse chelate (ΔRH = 2.5 ± 1.1 kJ·mol−1, ΔRS = 37.6 ± 5.4 kJ·mol−1·K−1) in the equilibrium is entropic in nature, and iii) the semi‐quaternized isomer still undergoes fast chloride‐exchange in the low‐temperature regime of this equilibrium, proving the existence of an independent, intermolecular chloride‐exchange mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
endo and exo Coordination of Indanol: Synthesis, Isolation and Structural Characterisation of [H3Ru3(endo‐Indanol)(C6Me6)2(O)]+ and [H3Ru3(exo‐Indanol)(C6Me6)2(O)]+ as Their Tetrafluoroborate Salts
Authors: Vieille‐Petit Ludovic , Karmazin‐Brelot Lydia , Labat Gaël , Süss‐Fink Georg
Published: August 2004

The reaction of 2,3,4,7‐tetrahydro‐1H‐inden‐2‐ol with ruthenium chloride hydrate in refluxing ethanol yields the chloro‐bridged dinuclear complex [RuCl2(indanol)]2 (1). The mononuclear complex [Ru(indanol)(H2O)3]2+ (2), formed in situ from 1 in aqueous solution, reacts with the dinuclear complex [H3Ru2(C6Me6)2]+ to give a trinuclear arene‐ruthenium cluster as a mixture of two isomers, the cations [H3Ru3(endo‐indanol)(C6Me6)2(O)]+ (3a) and [H3Ru3(exo‐indanol)(C6Me6)2(O)]+ (3b), in a 1:1 ratio. The hydroxy function of the indanol ligand is oriented towards the μ3‐oxo cap of 3a, whereas the OH group is bent away from the metal skeleton of 3b. These two isomers, which can easily be separated by silica‐gel chromatography, were isolated and characterised as their tetrafluoroborate salts. The single‐crystal X‐ray structure analysis of [3a][BF4] shows a strong intramolecular hydrogen bond between the μ3‐oxo ligand and the hydroxyl function, which even persists in acetone solution, as demonstrated by NMR spectroscopy. On the other hand, the hydroxy function of 3b was found to be free in the solid state as well as in solution, as shown by an X‐ray crystal structure analysis and by NMR spectroscopy. The catalytic activities of the water‐soluble trinuclear cations 3a and 3b for the hydrogenation of benzene to give cyclohexane under biphasic conditions are considerably different, the exo isomer 3b being more active than the endo isomer 3a. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Novel Cadmium(II) Adipate Coordination Polymers with Structural Transformation via Oxalate Ligand: Syntheses, Structures and Fluorescence Properties
Authors: Hao Na , Shen Enhong , Li Yang‐Guang , Wang En‐Bo , Hu Chang‐Wen , Xu Lin
Published: August 2004

Two novel cadmium adipate coordination polymers [Cd{O2C(CH2)4CO2}{1,10‐phen}]n (1) and [Cd2(C2O4){O2C(CH2)4CO2(OH2)2}{2,2′‐bipy}]·H2O (2) [adipic acid = HO2C(CH2)4CO2H] have been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray diffraction. Crystallographic data for 1: monoclinic, C2/c, a = 16.186(3) Å, b = 15.487(3) Å, c = 14.052(3) Å, β = 112.73(3)°, Z = 8. Crystal data for 2: monoclinic, Cc, a = 23.448(5) Å, b = 11.826(2) Å, c = 8.3163(17) Å, β = 99.08(3)°, Z = 4. The structural analysis reveals that 1 forms a novel one‐dimensional chain in which the binuclear Cd centers are linked by adipate anions. Compound 2 is the first example in which both a 2,2′‐bipy ligand and an oxalate group are found in the {M/adipate} system. Compound 2 possesses one‐dimensional sine‐ or cosine‐type chains, which are alternately connected together by the oxalate group to form a three‐dimensional framework. The structural determination reveals that the introduction of the oxalate ligand causes the dimensional transformation of the compounds. Compounds 1 and 2 show strong fluorescent properties at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Copper(II) and Nickel(II) Complexes of N,N‐Bis(2‐hydroxyethyl)octamethyl‐1,4,8,11‐tetraazacyclotetradecane
Authors: Roy Tapashi G. , Hazari Saroj K. S. , Dey Benu K. , Miah Hazarat A. , Bader Cerstin , Rehder Dieter
Published: August 2004

Reaction of ethylene oxide with the 1,4,8,11‐tetraazacyclotetradecanes Me8[14]ane LB (diaxial‐diequatorial with respect to the methyl substituents at the secondary ring carbons) and LC (axial‐triequatorial) yielded the N4,N11‐disubstituted 2‐hydroxyethyl (Y) derivatives LBY (diaxial‐diequatorial) and LAY (all‐equatorial). These new ligands interact with Cu(ClO4)2 to produce octahedral blue‐violet [CuLBY][ClO4]2 and deep‐blue [CuLAY][ClO4]2, with the hydroxyl groups of the −CH2−CH2−OH arms in axial positions. Reaction of LBY with nickel(II) acetate and subsequent addition of Li(ClO4) yielded square‐planar yellow [NiLBY][ClO4]2. Characterisation has been carried out on the basis of analytical, spectroscopic, conductometric and magneto‐chemical data. The structures of LBY and [CuLAY][ClO4]2 have been confirmed by X‐ray diffraction analyses. The antifungal and antibacterial activities of these compounds have been studied against some phytopathogenic fungi and bacteria. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Diastereoselective Insertion of Isocyanide into the Alkyl−Metal Bond of Methylbenz[e]indenyl ansa‐Zirconocene Complexes
Authors: Sebastián Alfredo , Royo Pascual , Gómez‐Sal Pilar , Ramírez de Arellano Carmen
Published: August 2004

Alkylation of ansa‐zirconocene [Zr{(η5‐C5H5)SiMe2(MBI)}Cl2] (MBI = η5‐2‐Me−C13H7) with MgRCl gave the dimethyl complex [Zr{(η5‐C5H5)SiMe2(MBI)}Me2], but unresolvable mixtures containing mono‐alkylated compounds were obtained when bulkier alkyls were used. However pure dialkyl complexes [Zr{(η5‐C5H5)SiMe2(MBI)}R2] (R = CH2Ph, CH2SiMe3) were easily obtained using K(CH2Ph) and Li(CH2SiMe3) as alkylating agents. Diastereoselective insertion into the MBI‐unprotected Zr−R bond was observed when all of these dialkyl complexes were treated with 2,6‐xylyl isocyanide to give the iminoacyl compounds [Zr{(η5‐C5H5)SiMe2(MBI)}R{CR[η2‐N‐(2,6‐xylyl)]}] (R = Me, CH2Ph, CH2SiMe3). All of the new complexes were characterized by NMR spectroscopy and the X‐ray molecular structures of the dibenzyl and the imino‐benzyl compounds were determined. The catalytic activity for ethene polymerization and ethene/1‐hexene copolymerization of the dichloro zirconocenes [Zr{(η5‐C5H5)EMe2(MBI)}Cl2] (E = C, Si), activated with methylalumoxane (MAO), was measured. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
2,4‐N,N′‐Bis(dialkylamido)‐2,4‐dithioxo‐1,3,2λ5,4λ5‐dithiadiphosphetanes
Authors: Dimitrov Anton , Hartwich Irmgard , Neubauer Petra , Meisel Manfred
Published: August 2004

Dialkylamide derivatives of the monometadithioxaphosphoric acid stabilised by pyridine as a donor, i.e. [(C5H5N)PS2NR2], readily react with AlCl3. The elimination of the donor and formation of the adduct C5H5N·AlCl3 liberates the unstable σ3λ5‐phosphoranes (PS2NR2). The latter are stabilised by [2+2] “cycloaddition‐dimerization” leading to the title compounds [PS2NR2]2 in nearly quantitative yields. The synthesis and characterisation of two compounds possessing NR2 substituents of very different basicities clearly demonstrate the generalisation of such a procedure as an easy way of accessing further derivatives in this class. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Novel Cytotoxic Copper(II) Complexes of 8‐Aminoquinoline Derivatives: Crystal Structure and Different Reactivity towards Glutathione
Authors: Zhang Shouchun , Tu Chao , Wang Xiongyong , Yang Zhen , Zhang Junyong , Lin Liping , Ding Jian , Guo Zijian
Published: August 2004

Two novel CuII complexes [Cu(CMQA)(H2O)] (1) (CMQA = N‐carboxymethyl‐L‐methionine‐N′‐8‐quinolylamide) and [Cu(MQA)(OAc)] (2) (MQA = L‐methionine‐N′‐8‐quinolylamide, OAc = CH3COO−) have been synthesized and structurally characterized. Complex 1 crystallizes in the orthorhombic system with space group P212121 [a = 5.556(1) Å, b = 15.002(3) Å, c = 20.886(4) Å] while complex 2 crystallizes in the monoclinic system with space group C2 [a = 28.463(6) Å, b = 5.264(1) Å, c = 13.345(3) Å, β = 109.142(3)°]. In both complexes the CuII center is coordinated by three N atoms of the ligand and one O atom of H2O (1) or OAc (2). The in vitro cytotoxicity of both complexes and their corresponding ligands have been tested against the murine leukemia P‐388 and lung adenocarcinoma A‐549 cell lines. Complex 2 shows a potent activity against both cell lines with an inhibitory rate of 100% for the murine leukemia P‐388 cell line and 93.4% for the lung adenocarcinoma A‐549 cell line at a concentration of 10−6 mol·L−1, while complex 1 shows only a marginal activity against the same cell lines. The reactivity of the two complexes towards γ‐glutathione (GSH) has been investigated and is discussed in association with their different cytotoxicity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Location of a missing object and detection of its absence by infants: Contribution of an eye‐tracking system to the understanding of infants' strategies
Authors: Lécuyer Roger , Berthereau Sophie , Taïeb Amel Ben , Tardif Nadia
Published: August 2004

Previous research has demonstrated infants' capacity to discriminate between situations in which all the objects successively hidden behind a screen are present, or not, after the removal of the screen. Two types of interpretation have been proposed: counting capacity or object memorization capacity. In the usual paradigm, the missing object in the impossible event is usually the last object which is placed behind the screen. Following this, a third interpretation can be offered: infants' exploration is first directed to this object's location, and its presence or absence is noticed. Two experiments using Wynn's (Nature 1992; 358:749) paradigm were performed to test the third hypothesis. The first experiment involved four objects (teddy bears) placed in four squares. Infants looked longer at the impossible event (3 objects, the last one missing) than at the possible event (4 objects) when the impossible event was presented first. No difference in looking duration was observed for the opposite order. In the second experiment, the four objects were disposed in a line and an eye‐tracking system was used. No difference in the number of looks was observed between the impossible event (3 objects, the second one missing) and the possible event (4 objects). Therefore, it appears that at least in this complex situation (4 objects used instead of 2 usually), the location of the missing object is a key factor for event discrimination. Eye‐tracking also indicated in the second experiment that infants looked less at the second location during an impossible event (object missing) than during the possible event (object present), indicating that the impossibility of the event was not a determining factor for looking durations. Altogether, the data indicate the potential usefulness of eye‐tracking analysis in this type of situation. Copyright © 2004 John Wiley & Sons, Ltd.
α1‐antitrypsin inhibits angiogenesis and tumor growth
Authors: Huang Hanhua , Campbell Steven C. , Nelius Thomas , Bedford Dhugal F. , Veliceasa Dorina , Bouck Noel P. , Volpert Olga V.
Published: August 2004

Disturbances of the ratio between angiogenic inducers and inhibitors in tumor microenvironment are the driving force behind angiogenic switch critical for tumor progression. Angiogenic inhibitors may vary depending on organismal age and the tissue of origin. We showed that α1‐antitrypsin (AAT), a serine protease inhibitor (serpin) is an inhibitor of angiogenesis, which induced apoptosis and inhibited chemotaxis of endothelial cells. S‐ and Z‐type mutations that cause abnormal folding and defective serpin activity abrogated AAT antiangiogenic activity. Removal of the C‐terminal reactive site loop had no effect on its angiostatic activity. Both native AAT and AAT truncated on C‐terminus (AATΔ) inhibited neovascularization in the rat cornea and delayed the growth of subcutaneous tumors in mice. Treatment with native AAT and truncated AATΔ, but not control vehicle reduced tumor microvessel density, while increasing apoptosis within tumor endothelium. Comparative analysis of the human tumors and normal tissues of origin showed correlation between reduced local α1‐antitrypsin expression and more aggressive tumor growth. © 2004 Wiley‐Liss, Inc.
Thymidylate synthase and dihydropyrimidine dehydrogenase gene expression in relation to differentiation of gastric cancer
Authors: Ichikawa Wataru , Takahashi Takehiro , Suto Kenichi , Nihei Zenro , Shirota Yoshinori , Shimizu Michio , Sasaki Yasutsuna , Hirayama Renzo
Published: August 2004

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are important enzymes of DNA de novo synthesis and the salvage pathway in cancer cells, respectively. Intratumoral TS and DPD gene expressions were evaluated to determine the correlation between the expression of the 2 genes in both normal stromal tissues and tissues with different degrees of malignant differentiation in primary gastric cancer. The study population consisted of 78 consecutive patients with advanced gastric cancer who underwent surgical treatment. Laser‐captured microdissection of malignant or normal stromal tissues was performed in formalin‐fixed, paraffin‐embedded specimens. After extraction of RNA, TS and DPD gene expressions were measured by the real‐time reverse transcriptional PCR method. Apart from degree of differentiation, TS and DPD in malignant tissue showed no correlation with clinicopathologic factors. TS in malignant tissue was higher in differentiated type cases than undifferentiated type cases (p < 0.01). However, DPD in malignant tissue of undifferentiated type cases was statistically higher than that of differentiated type cases (p < 0.05). In normal stromal tissue, neither TS nor DPD had any correlation with clinicopathologic factors. TS in malignant tissue was statistically higher than in normal stromal tissue in both differentiated and undifferentiated types (p < 0.0001). DPD in differentiated type malignant tissue was statistically lower than in normal stromal tissue (p < 0.001), but no difference was seen in undifferentiated type cases. TS and DPD gene expressions in primary gastric cancer differ according to degree of differentiation and between malignant and normal stromal tissue. © 2004 Wiley‐Liss, Inc.
An overview of the effect of linoleic and conjugated‐linoleic acids on the growth of several human tumor cell lines
Authors: Maggiora Marina , Bologna Mauro , Cerù Maria Paola , Possati Laura , Angelucci Angelo , Cimini Anna , Miglietta Antonella , Bozzo Francesca , Margiotta Chiara , Muzio Guiliana , Canuto Rosa Angela
Published: August 2004

Both n‐6 and n‐3 polyunsaturated fatty acids are dietary fats important for cell function, being involved in several physiologic and pathologic processes, such as tumorigenesis. Linoleic acid and conjugated linoleic acid, its geometrical and positional stereoisomer, were tested on several human tumor cell lines originating from different tissues and with different degrees of malignancy. This was to provide the widest possible view of the impact of dietary lipids on tumor development. While linoleic acid exerted different effects, ranging from inhibitory to neutral, even promoting growth, conjugated linoleic acid inhibited growth in all lines tested and was particularly effective against the more malignant cells, with the exception of mammary tumor cells, in which behavior was the opposite, the more malignant cell line being less affected. The inhibitory effect of conjugated linoleic acid on growth may be accompanied by different contributions from apoptosis and necrosis. The effects of conjugated linoleic acid on growth or death involved positive or negative variations in PPARs. The important observation is that a big increase of PPARα protein occurred in cells undergoing strong induction of apoptosis, whereas PPARβ/δ protein decreased. Although PPARα and PPARβ/δ seem to be correlated to execution of the apoptotic program, the modulation of PPARγ appears to depend on the type of tumor cell, increasing as protein content, when inhibition of cell proliferation occurred. In conclusion, CLA may be regarded as a component of the diet that exerts antineoplastic activity and its effect may be antiproliferative or pro‐apoptotic. © 2004 Wiley‐Liss, Inc.
Super‐resolution approach to overcome physical limitations of imaging sensors: An overview
Authors: Choi Euncheol , Choi Jongseong , Kang Moon Gi
Published: August 2004

Although the performance of CCD and CMOS imaging sensors has improved since their invention, they still have several physical limitations, such as various sources of noise, limited dynamic range, and limited spatial resolution. Besides these physical limitations, they have malfunctioning problems, such as smearing and blooming, which degrade the quality of captured images. These limitations and malfunctioning problems can be overcome, based on device physics and circuit technology. However, a signal‐processing‐based approach is a good alternative solution to these problems, because it may cost less and existing imaging systems can be still utilized. In a broad sense, this signal‐processing‐based approach can be called a super‐resolution approach. The goal of this article is to introduce a super‐resolution approach that overcomes the limitations of imaging sensors. To this purpose, we describe the existing limitations of imaging sensors first, and then describe the corresponding super‐resolution approach. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 36–46, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20006
Advances and challenges in super‐resolution
Authors: Farsiu Sina , Robinson Dirk , Elad Michael , Milanfar Peyman
Published: August 2004

Super‐Resolution reconstruction produces one or a set of high‐resolution images from a sequence of low‐resolution frames. This article reviews a variety of Super‐Resolution methods proposed in the last 20 years, and provides some insight into, and a summary of, our recent contributions to the general Super‐Resolution problem. In the process, a detailed study of several very important aspects of Super‐Resolution, often ignored in the literature, is presented. Specifically, we discuss robustness, treatment of color, and dynamic operation modes. Novel methods for addressing these issues are accompanied by experimental results on simulated and real data. Finally, some future challenges in Super‐Resolution are outlined and discussed. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 47–57, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20007
High‐resolution images from compressed low‐resolution video: Motion estimation and observable pixels
Authors: Alvarez L. D. , Mateos J. , Molina R. , Katsaggelos A. K.
Published: August 2004

In this article, we address the problem of obtaining a high‐resolution (HR) image from a compressed low‐resolution (LR) video sequence. Motion information plays a critical role in solving this problem, and we determine which pixels in the sequence provide useful information for calculating the high‐resolution image. The bit stream of hybrid motion compensated video compression methods includes low‐resolution motion‐compensated images; we therefore also study which pixels in these images should be used to increase the quality of the reconstructed image. Once the useful (observable) pixels in the low‐resolution and motion‐compensated sequences have been detected, we modify the acquisition model to only account for these observations. The proposed approach is tested on real compressed video sequences and the improved performance is reported. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 58–66, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20008
High‐resolution imaging using integrated optical systems
Authors: Prasad S. , Torgersen T. C. , Pauca V. P. , Plemmons R. J. , van der Gracht J.
Published: August 2004

Certain optical aberrations, such as defocus, can significantly degrade the signal collected by an imaging system, producing images with low resolution. In images with depth‐dependent detail, such degradations are difficult to remove due to their inherent spatially varying nature. In 1995, Dowski and Cathey introduced the concept of wavefront coding to extend the depth of field. They showed that wavefront coding and decoding enables quality control of such images using integrated optical‐digital imaging systems. With wavefront coding, a high‐resolution image can be efficiently obtained without the need to resort to expensive algorithms for spatially varying restoration. In this article, we discuss a novel and effective multiple‐design‐parameter approach for optimizing the processes of encoding and decoding the wavefront phase in integrated optical‐digital imaging systems. Our approach involves the use of information metrics, such as the Strehl ratio and Fisher information, for determining the optimal pupil‐phase distribution for which the resulting image is insensitive to certain aberrations, such as focus errors. The effectiveness of this approach is illustrated with a number of numerical simulation experiments, and applications to the development of iris recognition systems with high‐resolution capabilities are briefly discussed. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 67–74, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20009
High‐resolution image reconstruction from rotated and translated low‐resolution images with multisensors
Authors: Wen You‐Wei , Ng Michael K. , Ching Wai‐Ki
Published: August 2004

We extend the multisensor work by Bose and Boo (1998) and consider the perturbations of displacement error that are due to both translation and rotation. The warping process is introduced to obtain the ideal low‐resolution image, which is located at exactly horizontal and vertical shift. In this approach, the problem of high‐resolution image reconstruction is turned into the problem of image restoration, and the system becomes spatially invariant rather than spatially variant in the original problem. An efficient algorithm is presented. Experimental results show that the proposed methods are quite effective, and they perform better than the bilinear image interpolation method. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 75–83, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20010
A second‐generation wavelet framework for super‐resolution with noise filtering
Authors: Bose N. K. , Chappalli Mahesh B.
Published: August 2004

The use of second‐generation wavelets to attain super‐resolution with noise filtering is described for a captured sequence of low‐resolution frames without any assumptions on grid (sampling lattice) structure. The approach is based on 2D methods. The procedure allows the incorporation of the more general projective camera motion model into the framework, instead of only displacement and rotational models. Several simulations that compare the implementations of the algorithm presented here with other related approaches help illustrate the suitability of SGWs (coupled with hard or soft thresholding) in the task of image sequence superresolution with simultaneous noise filtering. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 14, 84–89, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.20011
Engineering bone‐like tissue in vitro using human bone marrow stem cells and silk scaffolds
Authors: Meinel Lorenz , Karageorgiou Vassilis , Hofmann Sandra , Fajardo Robert , Snyder Brian , Li Chunmei , Zichner Ludwig , Langer Robert , Vunjak‐Novakovic Gordana , Kaplan David L.
Published: August 2004

Porous biodegradable silk scaffolds and human bone marrow derived mesenchymal stem cells (hMSCs) were used to engineer bone‐like tissue in vitro. Two different scaffolds with the same microstructure were studied: collagen (to assess the effects of fast degradation) and silk with covalently bound RGD sequences (to assess the effects of enhanced cell attachment and slow degradation). The hMSCs were isolated, expanded in culture, characterized with respect to the expression of surface markers and ability for chondrogenic and osteogenic differentiation, seeded on scaffolds, and cultured for up to 4 weeks. Histological analysis and microcomputer tomography showed the development of up to 1.2‐mm‐long interconnected and organized bonelike trabeculae with cuboid cells on the silk‐RGD scaffolds, features still present but to a lesser extent on silk scaffolds and absent on the collagen scaffolds. The X‐ray diffraction pattern of the deposited bone corresponded to hydroxyapatite present in the native bone. Biochemical analysis showed increased mineralization on silk‐RGD scaffolds compared with either silk or collagen scaffolds after 4 weeks. Expression of bone sialoprotein, osteopontin, and bone morphogenetic protein 2 was significantly higher for hMSCs cultured in osteogenic than control medium both after 2 and 4 weeks in culture. The results suggest that RGD‐silk scaffolds are particularly suitable for autologous bone tissue engineering, presumably because of their stable macroporous structure, tailorable mechanical properties matching those of native bone, and slow degradation. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 25–34, 2004
Increased GADD gene expression in human colon epithelial cells exposed to deoxycholate
Authors: Scott David W. , Mutamba Sophia , Hopkins Robin G. , Loo George
Published: August 2004

The colonic epithelium is often exposed to high concentrations of secondary bile acids, which stresses the epithelial cells, leading potentially to activation of stress‐response genes. To examine this possibility in vitro, the purpose of this study was to determine if expression of certain growth arrest and DNA damage‐inducible genes (GADD) is upregulated in human colonic epithelial cells exposed to deoxycholate (DOC). DNA macroarray screening of a small cluster of stress/apoptosis‐related genes in DOC‐treated HCT‐116 colonocytes revealed clearly higher expression of only GADD45, which was confirmed by gene‐specific relative RT‐PCR analysis. Subsequently, it was found that DOC also increased GADD34 mRNA expression. However, mRNA expression of GADD153 was increased most markedly in DOC‐treated HCT‐116 colonocytes, which express wild‐type p53. However, the upregulation of GADD34, GADD45, and GADD153 mRNA expression apparently did not require p53, based on the finding that DOC increased expression of all three GADD genes in HCT‐15 colonocytes, which express mutant p53. In further studying GADD153 in particular, the effect of DOC on GADD153 mRNA was prevented by actinomycin‐D (Act‐D), but not by antioxidants or MAPK inhibitors. DOC also caused GADD153 protein to be expressed in close parallel with increased GADD153 mRNA expression. Induction of GADD153 protein by DOC was prevented by either anisomycin or cycloheximide. These findings suggest that DOC‐induced upregulation of GADD153 mRNA expression occurred at the level of transcription without involving reactive oxygen species and MAPK signaling, and that the expression of GADD153 protein was due also to translation of pre‐existing, and not just newly synthesized, mRNA. © 2005 Wiley‐Liss, Inc.
Caspase‐3 inhibits the growth of breast cancer cells independent of protease activity
Authors: Faraglia Beatrice , Bonsignore Alessia , Scaldaferri Franco , Boninsegna Alma , Cittadini Achille , Mancuso Cesare , Sgambato Alessandro
Published: August 2004

In this study, the MCF‐7 breast cancer cells that lack caspase‐3 were transfected with a wild type (WT) or mutant caspase‐3 cDNA. Expression of the WT, but not of the mutant, caspase‐3 was associated with increased caspase activity and susceptibility to staurosporine (STS)‐induced apoptosis. Both derivatives displayed inhibition of cell growth compared with vector control cells. Growth inhibition was associated with increased expression of the cyclin dependent kinase (CDK) inhibitor p27Kip1 in the WT, but not in the mutant caspase‐3 expressing cells. Cyclin D1 expression level was not affected by caspase‐3 expression. Phosphorylation of the Akt protein was decreased in both WT and mutant caspase transfected cells, although Akt expression level remained unchanged. These results suggest that caspase‐3 might have biological functions independent of its protease activity and that its loss might contribute to tumor development by increasing the growth potential of cancer cells. © 2004 Wiley‐Liss, Inc.
PKC mediates cyclic stretch‐induced cardiac hypertrophy through Rho family GTPases and mitogen‐activated protein kinases in cardiomyocytes
Authors: Pan Jing , Singh Ugra S. , Takahashi Toshiyuki , Oka Yoshitomo , Palm‐Leis Ants , Herbelin Bradley S. , Baker Kenneth M.
Published: August 2004

Signaling events, including Rho GTPases and protein kinase C (PKC), are involved in cardiac hypertrophy. However, the mechanisms by which these pathways cooperate during the hypertrophic process remain unclear. Using an in vitro cyclic stretch model with neonatal rat cardiomyocytes, we demonstrated that stretch‐induced activation of RhoA, Rac1/Cdc42, and phosphorylation of Rho‐guanine nucleotide dissociation inhibitor (GDI) were prevented by inhibition or depletion of PKC, using chelerythrine and phorbol 12‐myristate 13‐acetate, indicating that phorbol ester‐sensitive PKC isozymes may be upstream regulators of Rho GTPases. Using adenoviral‐mediated gene transfer of wild‐type (WT) and dominant‐negative (DN) mutants of PKCα and δ, we found that stretch‐induced activation of Rho GTPases and phosphorylation of Rho‐GDI were mainly regulated by PKCα. PKCδ was involved in regulation of the activation of Rac1. Stretch‐induced increases in [3H]‐leucine incorporation, myofibrillar reorganization and cell size, were blocked by inhibition of Rho GTPases, or overexpression of DN PKCα and δ, suggesting that PKCα and δ are both required in stretch‐induced hypertrophy, through Rho GTPases‐mediated signaling pathways. The mechanism, whereby PKC and Rho GTPases regulate hypertrophy, was associated with mitogen‐activated protein (MAP) kinases. Stretch‐stimulated phosphorylation of MEK1/ERK1/2 and MKK4/JNK was inhibited by overexpression of DN PKCα and δ, and that of MKK3/p38 inhibited by DN PKCδ. The phosphorylation of ERK and JNK induced by overexpression of WT PKCα, and the phosphorylation of p38 induced by WT PKCδ, were regulated by Rho GTPases. This study represents the first evidence that PKCα and δ are important regulators in mediating activation of Rho GTPases and MAP kinases, in the cyclic stretch‐induced hypertrophic process. © 2004 Wiley‐Liss, Inc.
Steroids dilate nuclear pores imaged with atomic force microscopy
Authors: Shahin Victor , Albermann Lars , Schillers Hermann , Kastrup Lilian , Schäfer Claudia , Ludwig Yvonne , Stock Christian , Oberleithner Hans
Published: August 2004

Macromolecules that act in the cell nucleus must overcome the nuclear envelope (NE). This barrier between cytosol and the nucleus is perforated by nuclear pore complexes (NPCs) that serve as translocation machineries. We visualized the translocation process at the NE surface, applying a nanotechnical approach using atomic force microscopy (AFM). In order to initiate protein targeting to NPCs, dexamethasone (dex) was injected into Xenopus laevis oocytes. Dex is a synthetic steroid of great therapeutic relevance that specifically binds to glucocorticoid receptors and thus triggers an intracellular signal cascade involving the cell nucleus. Ninety and 180 sec after dex injection cell nuclei were isolated, the NEs spread on glass and scanned with AFM. With single molecule resolution we observed that dex initiated proteins (DIPs) first bind to NPC‐free areas of the outer nuclear membrane. This causes NPCs to dilate. Then, in a second step, DIPs attach directly to NPCs and enter the dilated central channels. DIPs accumulation and NPC conformational changes were blocked by RU486, a specific glucocorticoid receptor antagonist. In conclusion, dex exposure induces NPC dilation. NPCs change conformation already prior to transport. The NPC dilation signal is most likely transmitted through NPC associated filaments or yet unknown structures in the NE outer membrane. NPC dilation could have significant impact on nuclear targeting of therapeutic macromolecules. © 2004 Wiley‐Liss, Inc.
Phosphoinositide 3‐kinase/Akt involvement in arsenic trioxide resistance of human leukemia cells
Authors: Tabellini Giovanna , Cappellini Alessandra , Tazzari Pier Luigi , Falà Federica , Billi Anna Maria , Manzoli Lucia , Cocco Lucio , Martelli Alberto M.
Published: August 2004

The purpose of this study was to evaluate the possible involvement of the phosphoinositide 3‐kinase (PI3K)/Akt survival pathway in determining resistance to arsenic trioxide (As2O3)‐induced apoptosis. We employed a HL60 cell clone (HL60AR) with a constitutively active PI3K/Akt survival pathway, as well as U937 and K562 cells. In addition, we used parental (PT) HL60 cells overexpressing a constitutively active Akt. Selective pharmacological inhibitors of the PI3K/Akt axis (LY294002, wortmannin) were employed to influence the sensitivity to As2O3. While HL60PT cells were sensitive to 2.5 μM As2O3 and died of apoptosis, HL60AR cells were resistant up to 5 μM As2O3. Treatment with either LY294002 or wortmannin lowered resistance of HL60AR cells to As2O3. Also in U937 and K562 cells, inhibitors of the PI3K/Akt axis caused a decrease in As2O3 resistance. Overexpression of constitutively active Akt in HL60PT cells caused the induction of resistance to 2.5 μM As2O3. Conversely, forced expression of a dominant negative Akt in HL60AR cells resulted in a decrease in As2O3 resistance. Moreover, HL60 cell resistance to 2.5 μM As2O3 could be significantly reduced by incubation with SN50, a peptide inhibitor selective for the NF‐κB transcription factor. Taken together our findings suggest that a constitutive activation of the PI3K/Akt pathway, which is increasingly detected in some types of acute myeloid leukemia, may contribute to As2O3 resistance, most likely through NF‐κB activation. Selective pharmacological inhibitors of this survival pathway, as well as of NF‐κB, might be usefully employed in the future to reverse resistance to this treatment. © 2004 Wiley‐Liss, Inc.
Intraocular gene transfer of pigment epithelium‐derived factor rescues photoreceptors from light‐induced cell death
Authors: Imai Daisuke , Yoneya Shin , Gehlbach Peter L. , Wei Lisa L. , Mori Keisuke
Published: August 2004

In this study, we investigated whether intraocular gene transfer of pigment epithelium‐derived factor (PEDF) ameliorates the extent of light‐induced photoreceptor cell death. Lewis rats received intravitreous injection of 3 × 109 particles of adenoviral vector expressing PEDF (AdPEDF.11) in one eye and 3 × 109 particles of empty adenoviral vector (AdNull.11) in the contralateral eye. The rats were then dark‐adapted for 3 days after which they were continuously exposed to fluorescent light (2,500 lux) for 0, 6, 24, 96, and 168 h. Both eyes were then enucleated and processed for morphometric analysis. Cell death in the retina was examined using TUNEL staining with a propidium iodide counterstain. The photoreceptor cell counts in each of the three groups were significantly different (P < 0.001). Eyes that received intravitreous injection of AdNull.11 or no injection showed a greater number of pyknotic photoreceptor cells and a reduced photoreceptor cell density as compared to eyes treated with intravitreous AdPEDF.11 injection. AdNull.11 treated eyes showed a lesser but still significant protection of photoreceptor cells when compared to untreated eyes. Fewer TUNEL‐positive photoreceptor cells were present in AdPEDF.11 treated eyes than in AdNull.11 treated or untreated eyes (P = 0.004). The amplitudes of the ERG a‐wave, b‐wave, and oscillatory potentials (OPs) were increased significantly by treatment (P < 0.05). These data suggest that adenovirus vector‐mediated intraocular expression of PEDF significantly increases photoreceptor cell survival following excessive light exposure. Neuroprotection may result from inhibition of light‐induced apoptotic processes. This study provides proof of concept for a gene transfer approach to modulating retinal cell death resulting from photo‐oxidative damage and supports the hypothesis that gene transfer of PEDF is broadly applicable to modulating apoptosis in the retina. © 2004 Wiley‐Liss, Inc.
Nuclear trafficking of metallothionein requires oxidation of a cytosolic partner
Authors: Takahashi Yukihisa , Ogra Yasumitsu , Suzuki Kazuo T.
Published: August 2004

The present study revealed the mechanism underlying the nuclear trafficking of metallothionein (MT). Nuclear localization of MT in digitonin‐permeabilized BALB 3T3 cells was enhanced in the presence of a cytosolic factor added as a rat red blood cell lysate by oxidation with H2O2 in a dose‐dependent manner, but inhibited with excess glutathione. A cytosolic partner was assumed to bind MT and retain it in the cytoplasm, and its oxidation can mobilize MT to the nuclei on cellular oxidation. Pre‐treatment of nuclei with H2O2 did not enhance the localization, and MT that had been localized in the nuclei was washed out, indicating that MT is in the nuclei as a result of a higher rate of uptake by the nuclei than the rate of diffusion from the nuclei. Nuclear localization of lysozyme and nuclear localization signal (NLS)‐bearing allophycocyanin were not enhanced by the oxidation in the presence of cytosolic factor, suggesting that the nuclear traffic occurring on oxidation is specific to MT. Moreover, when cells were arrested the cell cycle at the S phase, MT was localized in the nuclei in response to coincidental generation of a feeble reactive oxygen species (ROS). These observations suggest that MT comes localized in the nuclei on the sensing of intracellular oxidation, whereby a cytosolic partner specific to MT comes oxidized as a cargo system, MT being localized as a result of enhanced uptake in the nuclei and re‐localized in the cytoplasm diffusely. Nuclear MT was proposed to protect the nuclei from the oxidation occurring with progression of the cell cycle. © 2004 Wiley‐Liss, Inc.
Anti‐inflammatory effect of heme oxygenase 1: Glycosylation and nitric oxide inhibition in macrophages
Authors: Lin Hui‐Yi , Shen Shing‐Chuan , Chen Yen‐Chou
Published: August 2004

Flavonoids including the aglycones, hesperetin (HT; 5,7,3′‐trihydroxy‐4′‐methoxy‐flavanone), and naringenin (NE; 5,7,4′‐trihydroxy flavanone) and glycones, hesperidin (HD; 5,7,3′‐trihydroxy‐4′‐methoxy‐flavanone 7‐rhamnoglucoside) and naringin (NI; 5,7,4′‐trihydroxy flavanone 7‐rhamno glucoside), were used to examine the importance of rutinose at C7 on the inhibitory effects of flavonoids on lipopolysaccharide (LPS)‐induced nitric oxide production in macrophages. Both HT and NE, but not their respective glycosides HD and NI, induced heme oxygenase 1 (HO‐1) protein expression in the presence or absence of LPS and showed time and dose‐dependent inhibition of LPS‐induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression in RAW264.7, J774A.1, and thioglycolate‐elicited peritoneal macrophages. Additive inhibitory effect of an HO‐1 inducer hemin and NE or NI on LPS‐induced NO production and iNOS expression was identified, and HO enzyme inhibitor tin protoporphyrin (SnPP) attenuated the inhibitory effects of HT, NE, and hemin on LPS‐induced NO production. Both NE and HT showed no effect on iNOS mRNA and protein stability in RAW264.7 cells. Removal of rutinose at C7 of HD and NI by enzymatic digestion using hesperidinase (HDase) and naringinase (NIase) produce inhibitory activity on LPS‐induced NO production, according to the production of the aglycones, HT and NE, by high‐performance liquid chromatography (HPLC) analysis. Furthermore, the amount of NO produced by LPS or lipoteichoic acid (LTA) was significantly reduced in HO‐1‐overexpressing cells (HO‐1/RAW264.7) compared to that in parental cells (RAW264.7). Results of the present study provide scientific evidence to suggest that rutinose at C7 is a negative moiety in flavonoid inhibition of LPS‐induced NO production, and that HO‐1 is involved in the inhibitory mechanism of flavonoids on LPS‐induced iNOS and NO production. © 2004 Wiley‐Liss, Inc.
Mitogen‐activated protein kinases and asthma
Authors: Pelaia Girolamo , Cuda Giovanni , Vatrella Alessandro , Gallelli Luca , Caraglia Michele , Marra Monica , Abbruzzese Alberto , Caputi Mario , Maselli Rosario , Costanzo Francesco S. , Marsico Serafino A.
Published: August 2004

Mitogen‐activated protein kinases (MAPKs) are evolutionary conserved enzymes which play a key role in signal transduction mediated by cytokines, growth factors, neurotransmitters and various types of environmental stresses. In the airways, these extracellular stimuli elicit complex inflammatory and structural changes leading to the typical features of asthma including T cell activation, eosinophil and mast cell infiltration, as well as bronchial hyperresponsiveness and airway remodelling. Because MAPKs represent an important point of convergence for several different signalling pathways, they affect multiple aspects of normal airway function and also significantly contribute to asthma pathophysiology. Therefore, this review focuses on the crucial involvement of MAPKs in asthma pathogenesis, thus also discussing their emerging role as molecular targets for anti‐asthma drugs. © 2004 Wiley‐Liss, Inc.