bluuebunny/crossref_metadata_2025 huggingface dataset:
RNA Interference in the Moss Physcomitrella patens
Authors: Bezanilla Magdalena , Pan Aihong , Quatrano Ralph S.
Published: October 2003

The moss Physcomitrella patens performs efficient homologous recombination, which allows for the study of individual gene function by generating gene disruptions. Yet, if the gene of study is essential, gene disruptions cannot be isolated in the predominantly haploid P. patens. Additionally, disruption of a gene does not always generate observable phenotypes due to redundant functions from related genes. However, RNA interference (RNAi) can provide mutants for both of these situations. We show that RNAi disrupts gene expression in P. patens, adding a significant tool for the study of plant gene function. To assay for RNAi in moss, we constructed a line (NLS-4) expressing a nuclearly localized green fluorescent protein (GFP):β-glucuronidase (GUS) fusion reporter protein. We targeted the reporter protein with two RNAi constructs, GUS-RNAi and GFP-RNAi, expressed transiently by particle bombardment. Transformed protonemal cells are marked by cobombardment with dsRed2, which diffuses between the nucleus and cytoplasm. Cells transformed with control constructs have nuclear/cytoplasmic red fluorescence and nuclear green fluorescence. In cells transformed with GUS-RNAi or GFP-RNAi constructs, the nuclear green fluorescence was reduced on average 9-fold as soon as 48 h after transformation. Moreover, isolated lines of NLS-4 stably transformed with GUS-RNAi construct have silenced nuclear GFP, indicating that RNAi is propagated stably. Thus, RNAi adds a powerful tool for functional analysis of plant genes in moss.
The Penalty of a Long, Hot Summer. Photosynthetic Acclimation to High CO2 and Continuous Light in “Living Fossil” Conifers
Authors: Osborne Colin P. , Beerling David J.
Published: October 2003

Deciduous forests covered the ice-free polar regions 280 to 40 million years ago under warm “greenhouse” climates and high atmospheric pCO2. Their deciduous habit is frequently interpreted as an adaptation for minimizing carbon losses during winter, but experiments with “living fossils” in a simulated warm polar environment refute this explanation. Measured carbon losses through leaf abscission of deciduous trees are significantly greater than losses through winter respiration in evergreens, yet annual rates of primary productivity are similar in all species. Here, we investigate mechanisms underlying this apparent paradox by measuring the seasonal patterns of leaf photosynthesis (A) under pCO2 enrichment in the same trees. During spring, A increased significantly in coastal redwood (Sequoia sempervirens), dawn redwood (Metasequoia glyptostroboides), and swamp cypress (Taxodium distichum) at an elevated pCO2 of 80 Pa compared with controls at 40 Pa. However, strong acclimation in Rubisco carboxylation capacity (V  c,max) completely offset the CO2 response of A in all species by the end of 6 weeks of continuous illumination in the simulated polar summer. Further measurements demonstrated the temporary nature of acclimation, with increases in V  c,max during autumn restoring the CO2 sensitivity of A. Contrary to expectations, the acclimation of V  c,max was not always accompanied by accumulation of leaf carbohydrates, but was associated with a decline in leaf nitrogen in summer, suggesting an alteration of the balance in plant sources and sinks for carbon and nitrogen. Preliminary calculations using A indicated that winter carbon losses through deciduous leaf abscission and respiration were recovered by 10 to 25 d of canopy carbon fixation during summer, thereby explaining the productivity paradox.
Neutral-Lipid Analysis Reveals Elevation of Acylglycerols and Lack of Cholesterol Esters in
Plasmodium falciparum
-Infected Erythrocytes
Authors: Nawabi Parwez , Lykidis Athanasios , Ji Darder , Haldar Kasturi
Published: October 2003

Here we show that blood-stage
Plasmodium falciparum
organisms accumulate a high mass of triacylglycerol and diacylglycerol. However, we failed to detect cholesterol esters, a second neutral lipid species reported to be important for a related apicomplexan,
Toxoplasma gondii
. Evidence for
P. falciparum
and
T. gondii
homologues of acyl coenzyme A:diacylglycerol acyltransferase suggests that acylglycerols may be the conserved neutral lipids in apicomplexans.
Ask10p Mediates the Oxidative Stress-Induced Destruction of the
Saccharomyces cerevisiae
C-Type Cyclin Ume3p/Srb11p
Authors: Cohen Todd J. , Lee Kun , Rutkowski Lisa H. , Strich Randy
Published: October 2003

Srb11p-Srb10p is the budding yeast C-type cyclin-cyclin-dependent kinase that is required for the repression of several stress response genes. To relieve this repression, Srb11p is destroyed in cells exposed to stressors, including heat shock and oxidative stress. In the present study, we identified Ask10p (for activator of Skn7) by two-hybrid analysis as an interactor with Srb11p. Coimmunoprecipitation studies confirmed this association, and we found that, similar to Srb11p-Srb10p, Ask10p is a component of the RNA polymerase II holoenzyme. Ask10p is required for Srb11p destruction in response to oxidative stress but not heat shock. Moreover, this destruction is important since the hypersensitivity of an
ask10
mutant strain to oxidative stress is rescued by deleting
SRB11
. We further show that Ask10p is phosphorylated in response to oxidative stress but not heat shock. This modification requires the redundant mitogen-activated protein (MAP) kinase kinase Mkk1/2 but not their normal MAP kinase target Slt2p. Moreover, the other vegetative MAP kinases—Hog1p, Fus3p, or Kss1p—are not required for Ask10p phosphorylation, suggesting the existence of an alternative pathway for transducing the Pkc1p→Bck1→Mkk1/2 oxidative stress signal. In conclusion, Ask10p is a new component of the RNA polymerase II holoenzyme and an important regulator of the oxidative stress response. In addition, these results define a new role for the Pkc1p MAP kinase cascade (except the MAP kinase itself) in transducing the oxidative damage signal directly to the RNA polymerase II holoenzyme, thereby bypassing the stress-activated transcription factors.
To File Or Not To File? Systemic Incentives, Corporate Control, and the Bankruptcy Decision
Authors: Donoher William J.
Published: October 2003

This research investigates the distinctions between bankrupt firms and equally leveraged firms that avoid bankruptcy. Building upon the systemic incentives of bankruptcy law, and specifically those applicable to Chapter 11 reorganizations, the study argues that the firm’s governance and capital structure characteristics moderate the relationship between the firm’s financial condition and the filing decision. The results of this study indicate that, contrary to agency theoretical predictions, firms with high levels of inside equity ownership and secured indebtedness file in poorer financial condition than peer firms with low levels of these variables. By contrast, firms with high levels of outside equity ownership and short-term indebtedness file when in relatively better financial condition.
Identification of a very long chain polyunsaturated fatty acid Δ4‐desaturase from the microalga Pavlova lutheri1
Authors: Tonon Thierry , Harvey David , Larson Tony R , Graham Ian A
Published: October 2003

Pavlova lutheri, a marine microalga, is rich in the very long chain polyunsaturated fatty acids (VLCPUFAs) eicosapentaenoic (20:5n‐3) and docosahexaenoic (22:6n‐3) acids. Using an expressed sequence tag approach, we isolated a cDNA designated Pldes1, and encoding an amino acid sequence showing high similarity with polyunsaturated fatty acid front‐end desaturases. Heterologous expression in yeast demonstrated that PlDES1 desaturated 22:5n‐3 and 22:4n‐6 into 22:6n‐3 and 22:5n‐6 respectively, and was equally active on both substrates. Thus, PlDES1 is a novel VLCPUFA Δ4‐desaturase. Pldes1 expression is four‐fold higher during the mid‐exponential phase of growth compared to late exponential and stationary phases.
Conservation of RNase III Processing Pathways and Specificity in Hemiascomycetes
Authors: Chanfreau Guillaume
Published: October 2003

Rnt1p, the only known
Saccharomyces cerevisiae
RNase III endonuclease, plays important functions in the processing of precursors of rRNAs (pre-rRNAs) and of a large number of small nuclear RNAs (snRNAs) and small nucleolar RNAs (snoRNAs). While most eukaryotic RNases III, including the
Schizosaccharomyces pombe
enzyme Pac1p, cleave double-stranded RNA without sequence specificity, Rnt1p cleavage relies on the presence of terminal tetraloop structures that carry the consensus sequence AGNN. To search for the conservation of these processing signals, I have systematically analyzed predicted secondary structures of the 3′ external transcribed spacer (ETS) sequences of the pre-rRNAs and of flanking sequences of snRNAs and snoRNAs from sequences available in 13 other Hemiascomycetes species. In most of these species, except in
Yarrowia lipolytica
, double-stranded RNA regions capped by terminal AGNN tetraloops can be found in the 3′ ETS sequences of rRNA, in the 5′- or 3′-end flanking sequences of sn(o)RNAs, or in the intergenic spacers of polycistronic snoRNA transcription units. This analysis shows that RNase III processing signals and RNase III cleavage specificity are conserved in most Hemiascomycetes species but probably not in the evolutionarily more distant species
Y. lipolytica
.
Occupational exposures associated with work‐related asthma and work‐related wheezing among U.S. workers
Authors: Arif Ahmed A. , Delclos George L. , Whitehead Lawrence W. , Tortolero Susan R. , Lee Eun S.
Published: September 2003

Background

National estimates of occupational asthma (OA) in the United States are sparse.

Methods

Using data from the Third National Health and Nutrition Examination Survey (NHANES III) 1988–1994, we analyzed associations between occupation and work‐related asthma and work‐related wheezing among U.S. workers.

Results

This study identified several occupations that were at risk of developing work‐related asthma and/or wheezing, with cleaners and equipment cleaners showing the highest risks. Other major occupations identified were farm and agriculture; entertainment; protective services; construction; mechanics and repairers; textile; fabricators and assemblers; other transportation and material moving occupations; freight, stock, and material movers; and motor vehicle operators. The population attributable risks for work‐related asthma and work‐related wheezing were 26% and 27%, respectively.

Conclusions

This study adds evidence to the literature that identifies work‐related asthma as an important public health problem. Several occupations are targeted for additional evaluation and study. Of particular interest are cleaners, which are being increasingly reported as a risk group for asthma. Future intervention strategies need to be developed for effective control and prevention of asthma in the workplace. Am. J. Ind. Med. 44:368–376, 2003. © 2003 Wiley‐Liss, Inc.
Recent Developments in the Catalytic Asymmetric Synthesis of α‐ and β‐Amino Acids
Authors: Ma Jun‐An
Published: September 2003

The stereoselective synthesis of amino acids is of great importance for the construction of optically active natural products and pharmaceuticals. Apart from enzymes, a broad repertoire of chiral reagents, auxiliaries, and catalysts can be used for the formation of amino acids. Asymmetric reactions using catalytic amounts of chiral molecules provide efficient methods for the generation of optically active proteinogenic and nonproteinogenic amino acids. This minireview collects recent work on catalytic asymmetric synthesis of α‐ and β‐amino acids.
Molecular Structure–Activity Relationships for the Oxidation of Organic Compounds Using Mesoporous Silica Catalysts Derivatised with Bis(halogeno)dioxomolybdenum(VI) Complexes
Authors: Nunes Carla D. , Valente Anabela A. , Pillinger Martyn , Rocha João , Gonçalves Isabel S.
Published: September 2003

Mo K‐edge XAFS spectra have been measured for ordered mesoporous silica MCM‐41 grafted with the complexes [MoO2X2(thf)2] (X=Cl, Br). For grafting reactions in the absence of triethylamine, materials with 1 wt. % Mo are obtained; the Mo K‐edge EXAFS results indicate the co‐existence of isolated surface‐fixed monomeric species {MoO2[(O)3SiO]2(thf)n} and {MoO2[(O)3SiO]X(thf)n}. When Et3N is used in the grafting reactions, materials with 4 wt. % Mo are obtained. The EXAFS data for the material prepared using [MoO2Cl2(thf)2] and Et3N indicate the presence of dinuclear species with two MoVI centres, each with two MoO groups and each linked by one or two oxo bridges (Mo⋅⋅⋅Mo 3.27 Å). The molybdenum centres in the material prepared using the dibromo complex comprise mainly isolated four‐coordinate dioxomolybdenum(VI) and trioxomolybdenum(VI) monomeric species, with a small contribution from dimeric species. All materials were further characterised in the solid state by powder X‐ray diffraction, N2 adsorption analysis, MAS NMR (13C, 29Si) and FTIR spectroscopy. The derivatised MCMs perform differently as catalysts in the liquid‐phase oxidation of various olefins and alcohols with tert‐butyl hydroperoxide. The highest alkene epoxidation activity was recorded for the catalysts with low metal loading, whereas the material containing oxo‐bridged dimers had the highest activity for oxidation of alcohols. The recyclability of all the catalysts was tested: the catalytic activity of the derivatised materials tended to stabilize with ageing.
Molecular Scale Speciation of First‐Row Transition Elements Bound to Ligneous Material by Using X‐ray Absorption Spectroscopy
Authors: Guillon Emmanuel , Merdy Patricia , Aplincourt Michel
Published: September 2003

To develop a solid scientific basis for maintaining soil quality and formulating effective remediation strategies, it is critical to determine how environmentally‐important trace metals are sequestered in soils at the molecular scale. The speciation of Mn, Fe and Cu in soil organic matter has been determined by synchrotron‐based techniques: extended X‐ray absorption fine structure (EXAFS) and X‐ray absorption near edge structure (XANES). We show the structural similarity between the surface complexes of MnII, FeIII and CuII. These cations are bound to the surface through oxygen atoms. Each one presents a more or less tetragonal‐distorted octahedral geometry. The use of X‐ray absorption spectroscopy provides a relevant method for determining trace‐metal speciation in both natural and contaminated environmental materials.
Relevance of the Electronegativity of Boron in η5‐Coordinating Ligands: Regioselective Monoalkylation and Monoarylation in Cobaltabisdicarbollide [3,3′‐Co(1,2‐C2B9H11)2]− Clusters
Authors: Rojo Isabel , Teixidor Francesc , Viñas Clara , Kivekäs Raikko , Sillanpää Reijo
Published: September 2003

Regioselective monoalkylation and monoarylation in cobaltabisdicarbollide clusters has been achieved starting from Cs[8‐I‐3,3′‐Co(1,2‐C2B9H10)(1′,2′‐C2B9H11)] by cross‐coupling reactions between a BI fragment and an appropriate Grignard reagent in the presence of a Pd catalyst and CuI. A considerable number of monoalkylated and monoarylated derivatives have been synthesized, which allowed study of the influence of boron in metallocene‐type ligands and the effect of alkyl and aryl substituents on boron in boron anionic clusters. Experimental data from UV/Vis spectroscopy, E1/2 measurements, and X‐ray diffraction analysis, and supported by EHMO and ab initio analyses, indicate that the participation of metal d orbitals in the HOMO is less than that in typical metallocene complexes. This can be explained in terms of the lower electronegativity of boron compared to carbon. Related to this is the −I character of alkyl groups when bonded to boron in boron anionic clusters, contrary to the common belief that alkyl groups are generally electron‐releasing moieties.
An Accurate Barrier for the Hydrogen Exchange Reaction from Valence Bond Theory: Is this Theory Coming of Age?
Authors: Song Lingchun , Wu Wei , Hiberty Philippe C. , Danovich David , Shaik Sason
Published: September 2003

One of the landmark achievements of quantum chemistry, specifically of MO‐based methods that include electron correlation, was the precise calculation of the barrier for the hydrogen‐exchange reaction (B. Liu, J. Chem. Phys. 1973, 58, 1925; P. Siegbahn, B. Liu, J. Chem. Phys. 1978, 68, 2457). This paper reports an accurate calculation of this barrier by two recently developed VB methods that use only the eight classical VB structures. To our knowledge, the present work is the first accurate ab initio VB barrier that matches an experimental value. Along with the accurate barrier, the VB method provides accurate bond energies and diabatic quantities that enable the barrier height to be analyzed by the VB state correlation diagram approach, VBSCD (S. Shaik, A. Shurki, Angew. Chem. 1999, 111, 616; Angew. Chem. Int. Ed. Engl. 1999, 38, 586). This is a proof of principal that VB theory with appropriate account of dynamic electron correlation can achieve quantitative accuracy of reaction barriers, and still retain a compact and interpretable wave function. A sample of SN2 barriers and dihalogen bonding energies, which are close to CCSD(T) and G2(+) values, show that the H3 problem is not an isolated case, and while it is premature to conclude that VB theory has come of age, the occurrence of this event is clearly within sight.
Thermal expansion, pyroelectricity and linear optical properties of Li2SeO4·H2O and Li2SO4·H2O
Authors: Becker P. , Ahrweiler S. , Held P. , Schneeberger H. , Bohatý L.
Published: September 2003

Large single crystals of polar Li2SeO4·H2O were grown at 343 K from aqueous solution. Temperature dependent thermal expansion coefficients of Li2SeO4·H2O and Li2SO4·H2O were determined within the temperature range 133 K–313 K and coefficients of the pyroelectric effect within the temperature range 183–343 K. Refractive indices between 365 nm and 1530 nm as well as unpolarized absorption spectra of Li2SeO4·H2O and Li2SO4·H2O were measured and phase‐matching curves for second harmonic generation were calculated. Both compounds allow type I and type II phase‐matching at wavelengths from about 650 nm to the near infrared region. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Organomagnesium Phosphanide “Grignard” Analogues − Synthesis, Structural Characterisation and Solution Behaviour of [BuMg{P(CH[SiMe3]2)(C6H3‐2‐OMe‐3R)}]2 [R = H, Me]
Authors: Blair Stuart , Izod Keith , Clegg William , Harrington Ross W.
Published: September 2003

The reaction between either one or two equivalents of the secondary phosphane {(Me3Si)2CH}PH(C6H3‐2‐OMe‐3‐R′) [R′ = H (1a), Me (1b)] and Bu2Mg yields the heteroleptic complexes [BuMg{P[CH(SiMe3)2](C6H3‐2‐OMe‐3‐R′)}]2 [R′ = H (2a), Me (2b)], irrespective of the ratio of 1 to Bu2Mg. X‐ray crystallography shows that 2a and 2b crystallise as dimers containing a central Mg2P2 core. Dissolution of either 2a or 2b in THF results in complex degradation and formation of the tertiary phosphanes {(Me3Si)2CH}P(Me)(C6H3‐2‐OMe‐3‐R′) and unidentified magnesium‐containing products. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structural Studies of Lithium Telluro‐ and Seleno‐Phosphorus Compounds
Authors: Davies Robert P. , Martinelli M. Giovanna , Wheatley Andrew E. H. , White Andrew J. P. , Williams David J.
Published: September 2003

Lithium tellurophosphinite [Ph2PTe][Li(TMEDA)1.33(THF)1.33] (4), ditellurophosphinate, [Ph2PTe2][Li(THF)3.5(TMEDA)0.25] (5), and selenotellurophosphinate [Ph2P(Se)Te][Li(THF)2(TMEDA)] (6) complexes have been prepared from the insertion/oxidation reactions of lithiated secondary phosphanes with elemental chalcogens and characterised by X‐ray crystallography. Compounds 4−6 contain no tellurium−lithium bonding interactions in the solid state, instead existing as ion‐separated species with THF/TMEDA‐solvated lithium cations. Reaction of dilithiated primary phosphanes with more than three equivalents of elemental selenium gives [{(c‐C6H11)P(Se)(SeLi)}2·2TMEDA] (7) via a phosphorus‐phosphorus coupling reaction. Solid state characterisation of 7 reveals the organo groups in the tetradentate tetraselenohypodisphosphinate ligand to be in an anti conformation to one another and each lithium atom to be coordinated by two selenium atoms, one from each of the diselenophosphinate groups. Multinuclear NMR spectroscopic data are consistent with retention of the solid‐state structures of 4−7 in solution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Structural Diversity in Lewis‐Base Complexes of Lithium Triflamide
Authors: Davidson Matthew G. , Raithby Paul R. , Johnson Andrew L. , Bolton Philip D.
Published: September 2003

Complexation of the salt lithium triflamide [LiNTf2; NTf2 = N(SO2CF3)2], with a range of nitrogen donor ligands results in the formation of a series of coordination complexes [(Tf2N)Li·N(H)PPh2Me] (1), [(Tf2N)Li·N(H)PPh3] (2), [(Tf2N)Li·TMEDA] (3), [(Tf2N)Li·PMDTEA] (4) and [(Bz‐TAC)2Li][NTf2] (5). The molecular structures of 1, 3, 4 and 5 have been determined by single‐crystal X‐ray diffraction. The resulting solvated structures are discussed in terms of solvent‐separated ion pairs, contact ion pairs and higher aggregates, with the degree of aggregation and ion contact being dependent on the relative coordinating abilities and steric demands of the donor ligand and the anion, and provide an insight into the possible structures of lithium aggregates present in complex systems such as polymer electrolytes and synthetic reaction media. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Heteroaromatic Oligoamides with dDNA Affinity
Authors: Gallmeier Hans‐Christoph , König Burkhard
Published: September 2003

Heteroaromatic oligoamides are selective ligands for sequence‐specific dDNA binding, many artificial oligoamides modeled on naturally occurring compounds and their dDNA binding motifs having been prepared over the last ten years. The large number of reported individual compounds does not allow each structure to be covered within the scope of this review, so we concentrate on examples of the most successful linear and tethered oligoamide structures, such as hairpin, H‐pin, or cyclic structures, and the ensemble of heteroaromatic amino acids used as their building blocks. This provides an overview of which chemical structures are currently in use for sequence‐specific dDNA recognition by artificial ligands and what they can achieve. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Enantioselective Synthesis of the Pyrrolidine Core of Endothelin Antagonist ABT‐627 (Atrasentan) via 1,2‐Oxazines
Authors: Buchholz Monika , Reißig Hans‐Ulrich
Published: September 2003

Diastereoselective syntheses of the pyrrolidine core 6a of the endothelin antagonist ABT‐627 (Atrasentan) either as a racemic mixture or as an enantiopure compound are presented. The crucial steps of these syntheses utilized the highly diastereoselective conjugate addition of 1,3‐benzodioxol‐5‐yllithium to racemic 6H‐1,2‐oxazine 3 or enantiopure 6H‐1,2‐oxazines 7 or 8, followed by trapping with ethyl cyanoformate (Mander′s reagent). The resulting 5,6‐dihydro‐4H‐1,2‐oxazines were transformed into the 2,3,4‐trisubstituted pyrrolidine 6a. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Acid‐Catalyzed Conversion of 7‐Ethynyl‐ and 7‐Vinylcyclohepta‐1,3,5‐trienes to Substituted Benzene Derivatives
Authors: Minegishi Shinya , Kamada Jun , Takeuchi Ken’ichi , Komatsu Koichi , Kitagawa Toshikazu
Published: September 2003

The acid‐catalyzed rearrangement in THF/TFA (5:1, v/v) of cyclohepta‐1,3,5‐trienes containing an α,β‐unsaturated substituent at C‐7 was investigated. 7‐Ethynylcyclohepta‐1,3,5‐triene (1a) and its 1,4‐di‐tert‐butyl (1b), 1,5‐di‐tert‐butyl (1c), and 2,5‐di‐tert‐butyl (1d) derivatives underwent isomerization to phenylallenes 2, 3, 7, and 3, respectively. 2,5‐Di‐tert‐butyl‐7‐vinylcyclohepta‐1,3,5‐triene (17) gave a mixture (66:34) of (E)‐ and (Z)‐1,4‐di‐tert‐butyl‐2‐(1‐propenyl)benzene (20). A mechanism involving the protonation of the norcaradiene tautomer (NCD), which is in equilibrium with cycloheptatriene (CHT) 1 or 17, followed by the cleavage of a three‐membered ring to give an arenium ion, is proposed. In contrast, 2,5‐di‐tert‐butyl‐7‐cyanocyclohepta‐1,3,5‐triene (12) and bis(cyclohepta‐2,4,6‐trien‐1‐yl)ethyne (21) did not give the expected products, probably due to the unfavorable energetics of the ring‐opening step. A thermal 1,5‐hydrogen shift predominates in these cases. Kinetic studies indicated that the rearrangement of 1a is significantly accelerated by the presence of tert‐butyl groups on the seven‐membered ring. The order of reactivity, 1a < 1b < 1c < 1d, is in agreement with the population of NCD forms at equilibrium, as estimated by the calculated CHT−NCD energy‐difference and the 13C NMR chemical shifts of 1a−d, indicating the importance of the equilibrium concentration of the norcaradiene form as a rate‐controlling factor. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis and Electronic Properties of Alkynylated Phenothiazines
Authors: Krämer Christa S. , Müller Thomas J. J.
Published: September 2003

Alkynylated phenothiazines 1, 2, 5, 7, and 12−15 can be synthesized in moderate to excellent yields by sequences of aldehyde−alkyne transformations and/or Sonogashira cross‐coupling reactions from suitable phenothiazine aldehydes or bromides. The electronic properties of (hetero)aryl ethynyl‐substituted N‐methyl‐phenothiazines (UV/Vis absorption, fluorescence, redox potentials) strongly correlate with Hammett σP parameters and indicate that remote substituents transmit their electronic information through π‐electron delocalization and the σ‐framework. Phenothiazinyl dyads (7g, 12, 13) and triads (14) reveal different degrees of intramolecular electronic coupling as demonstrated by cyclic voltammetry, qualifying them as good model candidates for redox‐active molecular wires. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Gold‐Catalyzed Hydroarylation of Alkynes
Authors: Reetz Manfred T. , Sommer Knut
Published: September 2003

The hydroarylation of aryl‐substituted alkynes by substituted electron‐rich arenes is catalyzed by AuCl3 activated by such silver salts as AgSbF6. In the case of terminal alkynes, complete regioselectivity in favor of the 1,1‐disubstituted olefin is observed. In the case of electron‐poor alkynes such as acetylenecarboxylic acid ester, gold(I) complexes such as [Ph3PAuCl] activated by Ag salts or BF3·OEt2 are the best catalysts, resulting in opposite regioselectivity and high degrees of (Z)‐selectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
3‐Functionalized Tetronic Acids From Domino Rearrangement/Cyclization/Ring‐Opening Reactions of Allyl Tetronates
Authors: Schobert Rainer , Gordon Gary J. , Bieser Arno , Milius Wolfgang
Published: September 2003

Allyl tetronates 1 thermally rearrange to stable 3‐(spirocyclopropyl)dihydrofuran‐2,4‐diones 2 (R3 = H, Aryl), which can be ring‐opened with O‐, N‐, S‐ and C‐nucleophiles to give 3‐substituted tetronic acids 3−7. Compounds 2 with R3 = Alkyl are not isolable, but are interceptable intermediates in formal [2,3]‐sigmatropic rearrangements of allyl tetronates. The vinylogous hexadienyl tetronate 17 undergoes a different domino [3,5]‐rearrangement/cyclization reaction to give the 2H,5H‐furano[4,3‐b]oxepin‐6‐one 19. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis of Oligoarabinofuranosides from the Mycobacterial Cell Wall
Authors: Marotte Karine , Sanchez Sylvie , Bamhaoud Toufiq , Prandi Jacques
Published: September 2003

Oligoarabinofuranosides 1−4, fragments of the arabinan components found in the mycobacterial cell wall have been synthesized. 1 and 2 are representative of the structural features of the internal core of arabinogalactan, arabinomannan and lipoarabinomannans. 3 is the capping motif of the lipoarabinomannan of Mycobacterium tuberculosis and M. bovis BCG while 4 is the hexasaccharide found at the non‐reducing end of arabinogalactan. Complete stereocontrol was achieved for the elaboration of glycosidic linkages between arabinofuranoside units: α‐glycosides were obtained by participation of an ester or carbonate group on the 2‐position, while β‐arabinofuranosides were secured by an internal aglycon delivery approach. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
The feasibility of intraoperative diagnosis of sentinel lymph node metastases in breast cancer
Authors: Leidenius Marjut Hannele Kristiina , Krogerus Leena Anneli , Toivonen Terttu Sinikka , von Smitten Karl Johan Albert
Published: September 2003

Background and Objectives

The aim of the study was to analyse in detail the feasibility of intraoperative assessment of sentinel lymph nodes in breast cancer.

Methods

Altogether 139 consecutive breast cancer patients with metastases in axillary sentinel nodes were included in a prospective study. A combination of imprint cytology and frozen section was used as the method of intraoperative diagnosis of sentinel node metastases. The definite postoperative evaluation of the sentinel nodes was taken as the gold standard.

Results

The overall sensitivity of intraoperative diagnosis was 83%, reaching 81% if the intraoperative assessment had been limited to the two first retrieved sentinel nodes. False negative (FN) findings were more common in connection with invasive lobular carcinoma (28%) than with invasive ductal carcinoma (8%) (P < 0.01) as well as in connection with micro‐metastases, in 38% of the cases, compared to the larger metastases, 6% (P < 0.00005).

Conclusions

Intraoperative examination of sentinel lymph nodes enables breast surgery, axillary staging, and treatment in the same operation in a substantial proportion of breast cancer patients. Hospital costs as well as workload in the pathology laboratory may be reduced, limiting the intraoperative assessment to the two first retrieved nodes. J. Surg. Oncol. 2003;84:68–73. © 2003 Wiley‐Liss, Inc.
On summability of bilinear operators
Authors: Carando Daniel , Dimant Verónica
Published: September 2003

We study some properties of strongly and absolutely p‐summing bilinear operators. We show that Hilbert‐Schmidt bilinear mappings are both strongly and absolutely p‐summing, for every p ≥ 1. Giving an example of a strongly 1‐summing bilinear mapping which fails to be weakly compact, we answer a question posed in [6]. We prove that, as in the linear case, every bilinear operator from ℒ︁∞‐spaces to an ℒ︁2‐space is absolutely 2‐summing. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Inhibition of cutaneous ultraviolet light B–mediated inflammation and tumor formation with topical celecoxib treatment
Authors: Wilgus Traci A. , Koki Alane T. , Zweifel Ben S. , Kusewitt Donna F. , Rubal Patricia A. , Oberyszyn Tatiana M.
Published: September 2003

Inflammation, which includes the release of growth factors, proinflammatory cytokines and prostaglandins, the infiltration and activation of inflammatory cells, and the induction of oxidative DNA damage, is known to play a role in cancer development. The combination of damage to the skin resulting from chronic ultraviolet light B (UVB) exposure itself and the inflammatory response it induces is a major source of skin cancer development. Cyclooxygenase‐2 (COX‐2), an inflammatory enzyme responsible for the production of prostaglandins, is now implicated in the development of epithelial cancers, including squamous cell carcinoma in the skin. Previous work conducted in our laboratory has shown that topical treatment with celecoxib following UVB irradiation inhibits several parameters of acute inflammation, including vascular permeability, the infiltration and activation of neutrophils, and the production of prostaglandin E2 (PGE2). The present studies expanded these observations, demonstrating the ability of topical celecoxib to inhibit acute oxidative damage. In addition, long‐term studies illustrate the effectiveness of topical treatment with this drug in reducing chronic inflammation and UVB‐induced papilloma/carcinoma formation. This data provides compelling evidence to explore the clinical efficacy of topically applied COX‐2 inhibitors for the prevention of human skin cancers. © 2003 Wiley‐Liss, Inc.
Travelling for radiation cancer treatment: Patient perspectives
Authors: Fitch Margaret I. , Gray Ross E. , McGowan Tom , Brunskill Ian , Steggles Shawn , Sellick Scott , Bezjak Andrea , McLeese Donna
Published: September 2003

Radiation treatment for cancer requires patients to receive frequent administrations and attend the treatment facility on a daily basis for several weeks. Travelling for radiation treatment has the potential to add to the distress an individual may be feeling. This study utilized in‐depth interviews to capture 118 patients' perspectives about travelling for cancer treatment. Four themes emerged during the analysis of the data: (1) waiting was the most difficult part of the experience; (2) the idea of travelling for treatment was distressing; (3) travelling for treatment was tiring and posed difficulties for patients; and (4) being away from home had both benefits and drawbacks. Given the inevitability of travelling for radiation treatment, and the issues that arises for patients, supportive strategies need to be designed and implemented. Copyright © 2003 John Wiley & Sons, Ltd.
Quality of life of breast cancer patients in Taiwan: Validation of the Taiwan Chinese version of the EORTC QLQ‐C30 and EORTC QLQ‐BR23
Authors: Chie Wei‐Chu , Chang King‐Jen , Huang Chiun‐Sheng , Kuo Wen‐Hong
Published: September 2003

The objective of this study was to test the reliability and validity of the Taiwan Chinese version of the EORTC QLQ‐C30 (version 3) and EORTC QLQ‐BR23. The authors followed the guidelines of translation and pilot testing of the questionnaires. The questionnaires were given to 35 breast cancer patients under active treatment and 54 under follow‐up at the National Taiwan University Hospital from November 2000 to October 2001. A retest was conducted one to two weeks after the first interview/form completion for the follow‐up group. The intraclass correlation coefficients of the two questionnaires were moderate to high in the follow‐up group. The Cronbach's α coefficients of most scales of the two questionnaires were ≥ 0.70 except that of physical functioning (0.68), cognitive functioning (0.53), and arm symptoms (0.59). Correlations of scales measuring similar dimensions of the EORTC QLQ‐C30 and the SF‐36 were moderate. Patients in the active treatment group had more serious QOL problems due to disease and treatment. Results of this study showed that the Taiwan Chinese version of the two questionnaires had good test/retest reliability, high internal consistency in most scales, and could show the expected differences between patients in active chemotherapy and follow‐up group. Copyright © 2003 John Wiley & Sons, Ltd.
Quantization of the optical phase space in terms of the group
Authors: Kastrup H.A.
Published: September 2003

The problem of quantizing properly the canonical pair “angle and action variables”, φ and I, is almost as old as quantum mechanics itself and since decades an intensively debated but still unresolved issue in quantum optics. The present paper proposes a new approach to the problem, namely quantization in terms of the group SO(1,2): The crucial point is that the phase space has the global structure (a simple cone) and cannot be quantized in the conventional manner. As the group SO(1,2) acts transitively, effectively and Hamilton‐like on that space its irreducible unitary representations of the positive discrete series provide the appropriate quantum theoretical framework. The phase space has the conic structure of an orbifold . That structure is closely related to a Z2 gauge symmetry which corresponds to the center of a 2‐fold covering of SO(1,2), the symplectic group . The basic variables on the phase space are the functions h0 = I, h1 = I cos φ and h2 = ‐I sin φ the Poisson brackets of which obey the Lie algebra . In the quantum theory they are represented by the self‐adjoint Lie algebra generators K0, K1, and K2 of a unitary representation, where K0 has the spectrum {k + n, n = 0, 1, …; k > 0}. A crucial prediction is that the classical Pythagorean relation h12 + h22 = h02 can be violated in the quantum theory. For each representation one can define three different types of coherent states the complex phases of which may be “measured” by means of the operators K1 and K2 alone without introducing any new phase operators! The SO(1,2) structure of optical squeezing and interference properties as well as that of the harmonic oscillator are analyzed in detail. The additional coherent states can be used for the introduction of (Husimi type) “Q” distributions and (Sudarshan‐Glauber type) “P” representations of the density operator. The three operators K0, K1, and K2 are fundamental in the sense that one can construct composite position and momentum operators out of them! The new framework poses quite a number of fascinating experimental and theoretical challenges.
Total chemical synthesis of enzymes
Authors: Kent Stephen
Published: September 2003

The total synthesis, at will, of a wide variety of protein and enzyme molecules is made feasible by modern chemical ligation methods. As Emil Fischer intuitively understood, synthetic access to the enzyme molecule enables the power of chemical science to be applied to elucidating the molecular basis of catalytic function in unprecedented detail. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
Synthetic glycopeptides for the development of tumour‐selective vaccines
Authors: Kunz Horst
Published: September 2003

Based on structural information reported for the tumour‐associated epithelial mucin MUC1, glycopeptides have been synthesized which contain tumour‐associated saccharide antigens, such as the Thomsen‐Friedenreich (T), TN or sialyl TN antigen, in combination with peptide sequences of the tandem repeat region of MUC1. Solid‐phase syntheses have been carried out using N‐Fmoc protected O‐glycosyl serine and threonine building blocks and an allylic anchor which is stable to basic and acidic conditions, but can be cleaved under neutral conditions in a palladium(0)‐catalysed allyl transfer reaction. In addition, a (2–3)sialyl T antigen threonine building block was prepared by a chemoenzymatic strategy and used in the synthesis of an N‐terminal glycopeptide antigen of leukosialin (CD43). The proliferation of cytotoxic T cells could be induced using a construct consisting of a MUC1‐glycopeptide antigen and a T cell epitope Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
The fluorenylmethoxycarbonyl group in solid phase synthesis
Authors: Sheppard Robert
Published: September 2003

The history of the fluorenylmethoxycarbonyl amino‐protecting group since its introduction into solid phase peptide synthesis in 1978 is briefly traced. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd.
New aspects of galectin functionality in nuclei of cultured bone marrow stromal and epidermal cells: biotinylated galectins as tool to detect specific binding sites
Authors: Purkrábková Tereza , Smetana Karel , Dvořánková Barbora , Holíková Zuzana , Böck Corina , Lensch Martin , André Sabine , Pytlík Robert , Liu Fu‐Tong , Klíma Jiří , Smetana Karel , Motlík Jan , Gabius Hans‐Joachim
Published: October 2003

Nuclear presence of galectins suggests a role of these endogenous lectins in the regulation of transcription, pre‐mRNA splicing and transport processes. Therefore, detection and localization of nuclear binding sites for galectins by a new methodological step, has potential to further functional analysis. In the first step of our model study we monitored the nuclear expression of galectins‐1 and −3 in cultured stromal cells of human bone marrow and human/porcine keratinocytes. To enable detection and localization of galectin‐specific binding sites, we used purified galectins biotinylated without loss of activity as cytochemical tool. The degree of labeling of the probes was determined by adapting two‐dimensional gel electrophoresis and calculating pI changes in response to stepwise chemical modification of basic and acidic side chains by the biotinylation reagents. Binding studies revealed positivity for galectin‐1, whereas galectins‐3, −5, and −7 were not reactive with nuclear sites under identical conditions in bone marrow stromal cells and keratinocytes prepared from hair follicle enriched for stem cells. Inhibition by lactose indicated an involvement of the carbohydrate recognition domain in nuclear binding of galectin‐1. Colocalization of the galectin‐1‐dependent signal with the SC35 splicing factor and sensitivity toward RNase treatment argued in favor of galectin binding in nuclear speckles, albeit only for a small fraction of the cells. Epidermal cells positive for galectin‐1‐binding sites expressed ΔNp63 known as a potential marker of stem cells. Based on cytokeratin expression cells with nuclear binding of labeled galectin‐1 were basal and not suprabasal cells. Regarding proliferation, no relationship to the expression of a proliferation marker, Ki‐67, was observed. The nucleolar signal colocalized with fibrillarin and nucleophosmin/B23 as representatives of nucleolar proteins in both types of studied cells. In conclusion, the application of labeled galectins to localize accessible binding sites adds a new aspect to the functional analysis of these lectins in the nucleus.
Institutional forces and the written business plan
Authors: Honig Benson , Karlsson Tomas
Published: October 2003

In this study, we examined factors that led nascent organizations to write business plans, following 396 nascent entrepreneurs during a two-year period. We examined both the production and the outcomes of written business plans produced in nascent organizations. Our findings show that institutional variables, such as coercion and mimetic forces, are important predictors influencing the propensity of new organizations to write business plans. Our results are contrary to rationalist predictions of planning-performance, and are more in line with institutional predictions. Interestingly there was no evidence to support positive outcomes, in terms of profitability, for those nascent organizations that produced business plans during a two-year initial period. We discuss the implications for institutional theory and studies of nascent businesses, as well as for the literature on business planning.
Dues Paying: A Theoretical Explication and Conceptual Model
Authors: Martinko Mark J. , Douglas Scott C. , Ford Robert C. , Gundlach Michael J.
Published: October 2003

This article uses a practical and theoretical explication of “dues paying” as a vehicle for synthesizing and integrating attribution, justice, and impression management theories. A model is proposed that depicts the dues paying process as a specific type of impression management process that is stimulated by information that cues attributions of justice and equity. The paper ends with a discussion of the potential for integrating research and theory in the areas of impression management, attributions, and justice and suggestions are offered for managing dues paying impressions.
Structurally conserved α‐neurotoxin genes encode functionally diverse proteins in the venom of Naja sputatrix1
Authors: Jeyaseelan Kandiah , Poh Siew Lay , Nair Ramkishen , Armugam Arunmozhiarasi
Published: October 2003

The structure and organization of the genes encoding the long‐chain neurotoxins and four other isoforms of weak neurotoxins in the venom of Naja sputatrix are reported. The genes contained three exons interrupted by two introns, a structure similar to other members of the three‐finger toxin family. The proteins encoded by these genes, however, show varied affinity towards nicotinic acetylcholine receptors. Phylogenetic analysis of these genes showed that the weak neurotoxin gene is confined to a distinct group. We also observe that specific mutations of the gene provide the diversity in function in these toxins while maintaining a common structural scaffold. This forms the first report where the molecular basis of evolution of postsynaptic neurotoxins from an ancestral gene can be demonstrated using the same species of snake.
An environmental chamber investigation of chlorine‐enhanced ozone formation in Houston, Texas
Authors: Tanaka Paul L. , Allen David T. , Mullins C. Buddie
Published: September 2003

Three identical mobile chambers were designed and constructed for use in outdoor and field investigations. These chambers were employed during the Texas Air Quality Study (TEXAQS 2000) in Houston, Texas. Experiments were performed to investigate the ability of chlorine atoms (Cl·) to enhance ozone formation in captive ambient air from the Houston, Texas, area under the following conditions: (1) Release of Cl· precursor into captive ambient air, (2) release of Cl simultaneously with other ozone precursors (i.e., reactive hydrocarbons and nitrogen oxides) into captive ambient air, and (3) release of Cl into captive aged air masses. The investigation yielded the following results: (1) Chlorine atoms can enhance ozone formation in Houston's ambient air, (2) Cl· provide the greatest enhancement to reactivity in the morning hours after sunrise, (3) the enhancement by Cl· in the morning hours is greater than comparable amounts of reactive hydrocarbons such as propene, and (4) Houston air masses can display much variability in reactivity. This paper describes some of the unique characteristics of the chambers employed during this study and results from captive air experiments performed using these environmental chambers during TEXAQS 2000.
Chronology, chemistry, and origin of trachytes from Hualalai Volcano, Hawaii
Authors: Cousens Brian L. , Clague David A. , Sharp Warren D.
Published: September 2003

Hualalai Volcano is unique among Hawaiian volcanoes in that it possesses a relatively high proportion of evolved, trachytic lavas that were erupted at the beginning of the alkalic, postshield phase of volcanism. These evolved lavas yield insights into magma sources, magma supply rates, and the evolution of the subvolcanic magmatic plumbing system at this time. Trachyte lavas are exposed at the Puu Waawaa pumice dome and Puu Anahulu flow, as blocks in maars on the south flank of the volcano, and as flows in water wells drilled on the west flank of Hualalai. New 40Ar/39Ar dates show that the Puu Waawaa and Puu Anahulu complex is 114 ka, a block from the Waha Pele maar is 103 ka, and water well trachytes range from 107 to 92 ka in age, indicating a range for trachyte volcanism of 20 ka. Nd and Pb isotopic compositions overlap with younger alkalic basalts from Hualalai but are distinct from Hualalai tholeiitic basalts and Pacific mid‐ocean ridge basalts, linking the trachytes to alkalic parental magmas that underwent extensive crystallization to yield trachytic residual magmas. Both Sr and O isotopic ratios are higher in the trachytes than in Hualalai alkalic lavas, which is best explained by reaction with, or assimilation of, altered Hualalai shield basalts at shallow depth. Major, trace element, and isotopic variations between trachytes are consistent with their evolution by fractional crystallization from a Puu Anahulu parent. The short time gap between the end of tholeiitic volcanism (<133 ka) and the onset of trachytic, alkalic volcanism and the lack of deep‐origin xenoliths place the magma reservoir within which the trachytes evolved rapidly at shallow (<7 km) depth. Whereas Mauna Kea and Kohala volcanoes produced small volumes of highly evolved lavas as magma supply rates dwindled through the postshield stage, postshield magma intrusion rates at Hualalai were lowest during trachyte formation and increased through a more recent period of alkalic basalt eruptions. Subtle rare earth element and radiogenic isotopic distinctions between trachytes from the three localities indicate that the roof of the shallow magma reservoir may have been irregular, allowing some trachytes to evolve independently from others.