bluuebunny/crossref_metadata_2025 huggingface dataset:
Tillage and Crop Rotation Impact on Soybean Grain Yield and Composition
Authors: Temperly Ryan J. , Borges Rogerio
Published: June 2006

Soybean [Glycine max (L.) Merr.] yield response to tillage and crop rotation has varied among studies. Information regarding the effects of crop rotation and tillage on protein and oil concentrations in soybean grain is limited. A 3‐yr field study was conducted near Arlington, WI using conventional tillage and no‐tillage systems in seven soybean and corn (Zea mays L.) rotations. The objective was to determine the effect of tillage system and crop rotation on the yield, protein concentration, and oil concentration of soybean grain. The tillage × rotation interaction was significant (P ≤ 0.05) for grain yield. In the no‐tillage system, yields dropped 42% from 4.00 Mg ha−1 in first‐year soybean following 5 yr of consecutive corn to 2.33 Mg ha−1 in continuous soybean. In the conventional tillage system, yields dropped 35% from 3.01 Mg ha−1 in first‐year soybean following 5 yr of consecutive corn to 2.04 Mg ha−1 in continuous soybean. The tillage × rotation interaction was significant (P ≤ 0.05) for protein concentration. In the conventional tillage system, protein concentration decreased from 357 mg kg−1 in first‐year soybean following five consecutive years of corn to 351 mg kg−1 in fifth‐year soybean following five consecutive years of corn. No clear trend was observed for protein concentration in the no‐tillage system. Oil concentration increased as consecutive years of soybean production increased in both tillage systems at a similar rate.
Suppressing Sting Nematodes with Brassica sp., Poinsettia, and Spotted Spurge Extracts
Authors: Cox Campbell J. , McCarty Lambert B. , Toler Joe E. , Lewis Stephen A. , Martin S. Bruce
Published: June 2006

With synthetic nematicide options becoming limited, two studies were initiated to investigate the usefulness of selective botanical extracts for the suppression of sting (Belonolaimus longicaudatus Rau) nematodes. Plant materials were from greenhouse‐grown mature specimens of spotted spurge (Chamaesyce maculata L. Small); poinsettia (Euphorbia pulcherima Willd. ‘Freedom Red’); lantana (Lantana camara var. hybrida); mature, field‐grown tall lettuce (Lactuca canadensis L.); and goldenrod (Solidago altissima L. var. scabra), plus a seed meal extract from Brassica juncea ‘Pacific Gold’ (BSM). Nematodes were exposed to 1.2‐mL extract of either shoot or roots of each plant species. Nematode mortality counts were made daily for 4 d. In Study 1, effects of botanical extracts on nematode mortality were evaluated when applied directly to laboratory‐controlled sting nematode populations in test tubes. Root extracts of spurge, poinsettia, and lantana provided 69, 70, and 57% mortality, respectively, by 96 h while goldenrod and tall lettuce root extracts and the untreated provided 0% mortality. Shoot portions of poinsettia and spurge provided 95 to 98% mortality while goldenrod, tall lettuce, and lantana shoot extracts had 64, 40, and 25% mortality, respectively. Greenhouse studies evaluated the most successful laboratory extracts in a soil environment and included poinsettia shoot extracts and BSM. Poinsettia shoot extracts with irrigation provided 70% control compared with the untreated pots while poinsettia nonirrigated provided 73% control. Brassica sp. seed meal with irrigation provided 92% control while BSM nonirrigated provided 99.5% control. Brassica sp. seed meal, poinsettia, and spurge shoot extracts showed most promise as possible biocontrol agents of sting nematodes.
Field Tests of the Soil Heat Flux Plate Method and Some Alternatives
Authors: Ochsner Tyson E. , Sauer Thomas J. , Horton Robert
Published: June 2006

Heat flux plates are commonly used to measure soil heat flux, a component of the surface energy balance. The plate method is simple and precise, but several previous studies have demonstrated the potential for relatively large errors. Here we present the results of in situ tests of the plate method, and we describe some promising alternative methods. Summertime soil heat flux was measured with heat flux plates and with two alternative methods at each of three sites. In total, three alternative methods were used: a single probe gradient method, a three needle gradient method, and a self‐calibrating plate method. The standard plate method underestimated the magnitude of the heat flux by 18 to 66% depending on the site and type of plate. Agreement between the alternative methods was good with discrepancies ranging from 2 to 6%. The plates underestimate flux apparently due to a combination of low plate thermal conductivity, thermal contact resistance, and latent heat transfer effects. The three needle gradient method for measuring heat flux performed well at all three sites, providing a good alternative to the standard plate method. The self‐calibrating plate method performed well at the one site where it was tested and may also be a good alternative. Increased adoption of these methods should lead to more accurate soil heat flux and surface energy balance data.
Effect of Crowding Stress on Dry Matter Accumulation and Harvest Index in Maize
Authors: Tollenaar Matthijs , Deen William , Echarte Laura , Liu Weidong
Published: June 2006

Conflicting results have been reported on the effects of spacing and emergence variability on grain yield in maize (Zea mays L.). Effects of spacing and emergence variability on maize grain yield are the net result of the responses of all plants within the stand. The objective of this study was to quantify effects of spacing and emergence variability on crop yield in terms of increased or decreased crowding stress on resource capture (i.e., dry matter accumulation) and resource utilization (i.e., dry matter partitioning) of the individual plants within the crop canopy. Results of previously reported studies were analyzed in terms of plant dry matter accumulation, leaf area, plant growth rate during the critical period for kernel set bracketed by silking (PGRs), grain yield, and harvest index, that is, the proportion of dry matter partitioned to the grain at maturity. Results show that a moderate increase in plant‐spacing variability does not influence maize grain yield at the canopy level because reductions in grain yield of plants that experience enhanced crowding stress is compensated, in part, by increased yield of plants that experience reduced crowding stress; crowding stress affected dry matter accumulation but did not affect harvest index. In contrast, plant‐emergence variability reduced grain yield at the canopy level because the reduction in grain yield was attributable, in part, to a reduction in harvest index of plants with PGRs less than the threshold for kernel set. Hence, plants can compensate for factors that influence resource capture, but cannot compensate for a reduction in factors that influence resource utilization.
Winter Straw and Water Management Effects on Soil Nitrogen Dynamics in California Rice Systems
Authors: Linquist Bruce A. , Brouder Sylvie M. , Hill James E.
Published: June 2006

This study examines the effects of straw management and winter flooding on soil N dynamics and crop N uptake in California rice (Oryza sativa L.) systems. Experiments were established in two locations in northern California with main plot treatments being winter flooding or no flooding; and four straw management practices (burn, remove, incorporate, and roll) as subplot treatments. Fertilizer was applied to the plots at the recommended levels for each site, but within each plot a zero N microplot was established. Total straw inputs before winter flooding averaged 7000 kg ha−1 for the incorporate and roll treatments, 4200 kg ha−1 for the remove, and 1600 kg ha−1 for the burn treatment (straw N ranged from 11 to 66 kg ha−1). Before flooding the field for planting, there was 9% less straw in winter flooded plots compared to nonflooded plots. Straw incorporation resulted in more rapid straw decomposition compared to other treatments where the straw was not incorporated. Furthermore, potentially mineralizable N and soil extractable N was higher in the winter flooded treatments and where rice straw was retained. Crop response varied between sites but our results suggest that N fertilizer recommendations could potentially be reduced by 20 kg ha−1 if straw is incorporated and winter flooded.
Forage Yield Response to Water Use for Dryland Corn, Millet, and Triticale in the Central Great Plains
Authors: Nielsen David C. , Vigil Merle F. , Benjamin Joseph G.
Published: June 2006

Forages, with greater water use efficiency (WUE) than grain and seed crops, could be used to diversify reduced and no‐till dryland cropping systems from the traditional wheat (Triticum aestivum L.)–fallow system in the semiarid central Great Plains. However, farmers need a simple tool to evaluate forage productivity under widely varying precipitation conditions. The objectives of this study were to (i) quantify the relationship between crop water use and dry matter (DM) yield for corn (Zea mays L.), foxtail millet (Setaria italica L. Beauv.), and winter triticale (X Triticosecale Wittmack); and (ii) determine the range and distribution of expected DM yields for these three crops in the central Great Plains based on historical precipitation records. The three crops were grown in a dryland no‐till corn–millet–triticale sequence from 1998 through 2004 at Akron, CO. Dry matter production was linearly correlated with water use for all three crops, with regression slopes ranging from 24.2 (corn) to 33.0 kg ha−1 mm−1 (millet). Water use efficiency varied widely from year to year (0–32.2 kg ha−1 mm−1) for the three crops, as influenced by growing season precipitation and time of year in which the crops were grown. Millet and triticale produced similar amounts of DM for a given water use, while corn produced less. Precipitation use efficiency for the millet–triticale–corn forage system was 8.7 kg ha−1 mm−1, suggesting this as an efficient forage system for the region.
Generalized Alexandroff Duplicates and CD
0(K) spaces
Authors: Çaglar Mert , Ercan Zafer , Polat Faruk
Published: June 2006

We define and investigateCD
Σ,Γ(K, E)-type spaces, which generalizeCD
0-type Banach lattices introduced in [1]. We state that the space CD
Σ,Γ(K, E) can be represented as the space of E-valued continuous functions on the generalized Alexandroff Duplicate of K. As a corollary we obtain the main result of [6, 8].
Rate-equation calculations of the current flow through two-site molecular device and DNA-based junction
Authors: Walczak Kamil
Published: June 2006

Here we present the calculations of incoherent current flowing through the two-site molecular device as well as the DNA-based junction within the rate-equation approach. Selected phenomena of interest are discussed in detail. The structural asymmetry of a two-site molecule results in a rectification effect, which can be neutralized by an asymmetric voltage drop at the molecule-metal contacts due to coupling asymmetry. The results received for the poly(dG)-poly(dC) DNA molecule reveal the coupling-and temperature-independent saturation effect of the current at high voltages, establishing for short chains the inverse square distance dependence. Additionally we document the conductance peak shifting in the direction of higher voltages due to a temperature decrease.
Modulating expression of LAMPs and ABH histo-blood group antigens in normal and neoplastic human skin
Authors: Sarafian Victoria , Dikov Dorian , Karaivanov Milen
Published: June 2006

Although the precise biological role of lysosomal membrane-associated glycoproteins (LAMPs) and ABH histo-blood group antigens (HBGAs) remains somewhat unclear, they are thought to be related to cell differentiation, cellular adhesion, and tumorigenesis. Here, we present the first comparative immunohistochemical study of both LAMPs and HBGAs in normal and neoplastic skin. Their localization is compared to that of high molecular weight cytokeratin and cytokeratin MNF 116. LAMPs and HBGA were differentially expressed in the normal stratified squamous epithelium, suggesting that they are involved in the initial steps of the differentiation process, whereas HBGAs are characteristic of terminal keratinocyte differentiation. No change in the reactivity for HBGA was detected in the stratified epithelium overlying squamous cell or basal cell carcinomas, whereas a considerable loss of LAMPs was detected. LAMPs were overexpressed in tumor cells, whereas HBGAs were lost in tumor zones of basocellular carcinomas. In spinocellular carcinomas, HBGAs were detected in tumor keratinocytes and in keratin pearls. These results provide new evidence for the differential expression of LAMPs and HBGAs in the normal stratified squamous epithelium, as well as the presence of a modulating reactivity in basocellular and spinocellular carcinomas, suggesting that these glycoproteins are involved in differentiation and tumorigenesis of human skin.
Web issue analysis: An integrated water resource management case study
Authors: Thelwall Mike , Vann Katie , Fairclough Ruth
Published: June 2006

In this article Web issue analysis is introduced as a new technique to investigate an issue as reflected on the Web. The issue chosen, integrated water resource management (IWRM), is a United Nations–initiated paradigm for managing water resources in an international context, particularly in developing nations. As with many international governmental initiatives, there is a considerable body of online information about it: 41,381 hypertext markup language (HTML) pages and 28,735 PDF documents mentioning the issue were downloaded. A page uniform resource locator (URL) and link analysis revealed the international and sectoral spread of IWRM. A noun and noun phrase occurrence analysis was used to identify the issues most commonly discussed, revealing some unexpected topics such as private sector and economic growth. Although the complexity of the methods required to produce meaningful statistics from the data is disadvantageous to easy interpretation, it was still possible to produce data that could be subject to a reasonably intuitive interpretation. Hence Web issue analysis is claimed to be a useful new technique for information science.
Contralateral recurrence and prognostic factors in familial non-BRCA1/2-associated breast cancer
Authors: Tilanus-Linthorst M M A , Alves C , Seynaeve C , Menke-Pluymers M B E , Eggermont A M M , Brekelmans C T M
Published: June 2006

Background

A higher incidence of contralateral breast cancer and ipsilateral recurrence has been reported in familial breast cancer than in sporadic cancer. This study investigated the influence of contralateral cancer and tumour stage on survival in patients with familial non-BRCA1/BRCA2-associated breast cancer.

Methods

The incidences of contralateral breast cancer, ipsilateral recurrence, distant disease-free and overall survival were assessed in 327 patients from families with three or more breast and/or ovarian cancers, but no BRCA1 or BRCA2 gene mutation (familial non-BRCA1/2), and in 327 control subjects with sporadic breast cancer, matched for year and age at detection.

Results

Mean follow-up was 7·3 years for patients with familial-non-BRCA1/2 cancers and 6·5 years for patients with sporadic breast cancer. Tumours were stage T1 or lower in 62·1 per cent of familial non-BRCA1/2 cancers versus 49·9 per cent in sporadic breast cancers (P = 0·003), and node negative in 55·8 versus 52·1 per cent, respectively (P = 0·477). After 10 years the incidence of metachronous contralateral breast cancer was 6·4 per cent for familial non-BRCA1/2 tumours versus 5·4 per cent for sporadic cancers. The rate of ipsilateral recurrence was not significantly increased (17·0 versus 14·2 per cent, respectively, at 10 years; P = 0·132). Tumour size (hazard ratio (HR) 1·02 per mm increase, P = 0·016) and node status (HR 2·6 for three or more involved nodes versus node negative, P = 0·017) were independent predictors of overall survival in the familial non-BRCA1/2 group, and in the whole group, whereas contralateral breast cancer (HR 0·7, P = 0·503) and risk-reducing contralateral mastectomy (HR 0·4, P = 0·163) were not.

Conclusion

Stage at detection was a key determinant of prognosis in familial non-BRCA1/2 breast cancer, whereas contralateral cancer was not. Risk-reducing contralateral mastectomy did not significantly improve survival, but early detection can. Decisions on breast-conserving treatment can be made on the same grounds in patients with familial and sporadic breast cancer.
Forging the links: (de)constructing chains of behaviours
Authors: Piper Heather , Myers Steve
Published: June 2006

This paper will discuss an article by Becker and French (2005) in this Journal which proposed the general acceptance of correlations or the ‘links’ between child abuse, animal abuse and domestic violence. Becker and French claim this topic has ‘seen a growth of interest’ (p. 399) over the past two decades and they suggest that organizations across the UK should ‘institutionalize the “links” within policy and practice’ (p. 410). In this paper we question the appropriateness of linking different forms of violence in such a mechanistic and predictive way by drawing on and extending arguments we have made elsewhere. We consider the proposed ‘links’ in terms of assumptions, deﬁnitions, methods and logic, and raise concerns for a prospective practice which is based on retrospective (and ﬂawed) research. We aim to appeal to inﬂuential doubters (social workers, child care workers, animal welfare workers, vets, educators and policy‐makers) in a language of ‘reason’, and we propose that the identiﬁed reluctance of professionals in the UK to adopt the rhetoric of ‘links’ can be viewed as an informed and reﬂective response. Throughout, we offer a corrective commentary to the ﬂawed assumptions of the ‘links’ argument and seek to encourage others to remain sceptical about these claims and the suggested implications for practice. Copyright © 2006 John Wiley & Sons, Ltd.
scyllo‐Inositol Pentakisphosphate as an Analogue of myo‐Inositol 1,3,4,5,6‐Pentakisphosphate: Chemical Synthesis, Physicochemistry and Biological Applications
Authors: Riley Andrew M. , Trusselle Melanie , Kuad Paul , Borkovec Michal , Cho Jaiesoon , Choi Jae H. , Qian Xun , Shears Stephen B. , Spiess Bernard , Potter Barry V. L.
Published: June 2006

myo‐Inositol 1,3,4,5,6‐pentakisphosphate (Ins(1,3,4,5,6)P5), an inositol polyphosphate of emerging significance in cellular signalling, and its C‐2 epimer scyllo‐inositol pentakisphosphate (scyllo‐InsP5) were synthesised from the same myo‐inositol‐based precursor. Potentiometric and NMR titrations show that both pentakisphosphates undergo a conformational ring‐flip at higher pH, beginning at pH 8 for scyllo‐InsP5 and pH 9 for Ins(1,3,4,5,6)P5. Over the physiological pH range, however, the conformation of the inositol rings and the microprotonation patterns of the phosphate groups in Ins(1,3,4,5,6)P5 and scyllo‐InsP5 are similar. Thus, scyllo‐InsP5 should be a useful tool for identifying biologically relevant actions of Ins(1,3,4,5,6)P5, mediated by specific binding sites, and distinguishing them from nonspecific electrostatic effects. We also demonstrate that, although scyllo‐InsP5 and Ins(1,3,4,5,6)P5 are both hydrolysed by multiple inositol polyphosphate phosphatase (MINPP), scyllo‐InsP5 is not dephosphorylated by PTEN or phosphorylated by Ins(1,3,4,5,6)P5 2‐kinases. This finding both reinforces the value of scyllo‐InsP5 as a biological control and shows that the axial 2‐OH group of Ins(1,3,4,5,6)P5 plays a part in substrate recognition by PTEN and the Ins(1,3,4,5,6)P5 2‐kinases.
Photoaddition of N‐Substituted Piperazines to C60: An Efficient Approach to the Synthesis of Water‐Soluble Fullerene Derivatives
Authors: Troshina Olesya A. , Troshin Pavel A. , Peregudov Alexander S. , Kozlovski Viacheslav I. , Lyubovskaya Rimma N.
Published: June 2006

An oxidative radical photoaddition of mono N‐substituted piperazines to [60]fullerene was systematically investigated. Reactions of C60 with piperazines bearing bulky electron‐withdrawing groups (2‐pyridyl, 2‐pyrimidinyl) were found to be the most selective and yielded C60(amine)4O as major products along with small amounts of C60(amine)2. In contrast, interactions of fullerene with N‐methylpiperazine and N‐(tert‐butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions. Tetraaminofullerene derivative C60(N‐(2‐pyridyl)piperazine)4O was found to react readily with organic and inorganic acids to yield highly water‐soluble salts (solubility approximately 150 mg mL−1). In contrast, C60(N‐(2‐pyrimidinyl)piperazine)4O undergoes hydrolysis under the same conditions and results in a complex mixture of compounds with an average composition of C60(N‐(2‐pyrimidinyl)piperazine)2(OH)2O. Radical photoaddition of N‐(2‐pyridyl)piperazine to fullerene derivatives can be used as a facile route for their transformation into water‐soluble compounds. Two model fullerene cycloadducts (a methanofullerene and a pyrrolidinofullerene) were easily converted into mixtures of regioisomers of A=C60(N‐(2‐pyridyl)piperazine)4O (A=cyclic addend) that give highly water‐soluble salts under acid treatment.
Oxidative DNA Cleavage Promoted by Multinuclear Copper Complexes: Activity Dependence on the Complex Structure
Authors: Zhao Yongmei , Zhu Jianhui , He Weijiang , Yang Zhen , Zhu Yangguang , Li Yizhi , Zhang Junfeng , Guo Zijian
Published: June 2006

Polynuclear copper complexes with two or three Cu(BPA) (BPA, bis(2‐pyridylmethyl)amine) motifs, [Cu2(mTPXA)Cl4]⋅3 H2O (1), [Cu2(pTPXA)Cl4]⋅3 H2O (2), [Cu3(HPTAB)Cl5]Cl⋅3 H2O (3) (mTPXA = N,N,N′,N′‐tetra‐(2‐pyridylmethyl)‐m‐xylylene diamine; pTPXA = N,N, N′,N′‐tetra‐(2‐pyridylmethyl)‐p‐xylylenediamine; HPTAB = N,N,N′,N′,N′′,N′′‐hexakis(2‐pyridylmethyl)‐1,3,5‐tris‐(aminomethyl)benzene) have been synthesized and characterized. The crystal structures of compounds 2 and 3 showed each Cu(BPA) motif had a 4+1 square‐pyramidal coordination environment with one chloride occupying the apical position and three N atoms from the same BPA moiety together with another Cl atom forming the basal plane. Fluorescence and circular dichroism (CD) spectroscopy studies indicated that the DNA binding followed an order of 3>2>1 in the compounds. These complexes cleave plasmid pUC19 DNA by using an oxidative mechanism with mercaptopropionic acid (MPA) as the reductant under aerobic conditions. Dinuclear Cu2+ complexes 1 and 2 showed much higher cleavage efficiency than their mononuclear analogue [Cu(bpa)Cl2] at the same [Cu2+] concentration, suggesting a synergistic effect of the Cu2+ centers. Moreover, the meta‐dicopper centers in complex 1 facilitated the formation of linear DNA. Interestingly, the additional copper center to the meta‐dicopper motif in complex 3 decreased the cleavage efficacy of meta‐dicopper motif in complex 1, although it is able to cleave DNA to the linear form at higher [Cu2+] concentrations. Therefore, the higher DNA binding ability of complex 3 did not lead to higher cleavage efficiency. These findings have been correlated to the DNA binding mode and the ability of the Cu2+ complexes to activate oxygen (O2). This work is a good example of the rational design of multinuclear Cu2+ artificial nuclease and the activity of which can be manipulated by the geometry and the number of metal centers.
Syntheses and Structures of Sterically Congested Linear and Branched Cobalta[n]triangulanes
Authors: Kozhushkov Sergei I. , Foerstner Jan , Kakoschke Alf , Stellfeldt Dirk , Yong Li , Wartchow Rudolf , de Meijere Armin , Butenschön Holger
Published: June 2006

Treatment of {η5:η1[2‐(di‐tert‐butylphosphanyl‐P)ethyl]cyclopentadienyl}cobalt(I) chloride (5) with methylenecyclopropane (3) or bicyclopropylidene (4), as well as with their spirocyclopropanated analogues methylenespiropentane (7), cyclopropylidenespiropentane (10), or 7,7′‐bi(dispiro[2.0.2.1]heptylidene) (15) in the presence of sodium amalgam at −50 °C, furnished the stable cobalt complexes6,9,8,11, and16, respectively, in 72, 83, 84, 86, and 54 % isolated yield, respectively. The complexes14and16were also obtained by ligand exchange of the ethene complex {η5:η1[2‐(di‐tert‐butylphosphanyl‐P)ethyl]cyclopentadienyl}(η2‐ethene)cobalt(I) (12) with13and15in 79 and 52 % yield, respectively. The X‐ray crystal‐structure analyses of complexes9,14, and16, as well as the NMR‐spectroscopic data of all complexes, reveal that they can be regarded as linear and branched cobalta[n]triangulanes. The thermal stability of complexes6,8, and9up to 109, 145, and 160 °C was determined by differential thermal analysis‐thermogravimetry (DTA‐TG) analysis.
Reactivity of Lanthanocene Amide Complexes toward Ketenes: Unprecedented Organolanthanide‐Induced Conjugate Electrophilic Addition of Ketenes to Arenes
Authors: Liu Ruiting , Zhang Chunmei , Zhu Zhenyu , Luo Jun , Zhou Xigeng , Weng Linhong
Published: June 2006

This paper presents some unusual types of reactions of lanthanocene amide complexes with ketenes, and demonstrates that these reactions are dependent on the nature of amide ligands and ketenes as well as the stoichiometric ratio under the conditions involved. The reaction of [{Cp2LnNiPr2}2] with four equivalents of Ph2CCO in toluene affords the unexpected enolization dearomatization products [Cp2Ln(OC{2,5‐C6H5(CPhCONiPr2‐4)}CPh2)] (Ln = Yb (1 a), Er (1 b)) in good yields, representing an unprecedented conjugate electrophilic addition to a non‐coordinated benzenoid nucleus. Treatment of [{Cp2LnNiPr2}2] with four equivalents of PhEtCCO under the same conditions gives the unexpected enolization dearomatization/rearomatization products [{Cp2Ln(OC{C6H4(p‐CHEtCONiPr2)}CEtPh)}2] (Ln = Yb (2 a), Er (2 b), Dy (2 c)). However, reaction of [{Cp2YbNiPr2}2] with PhEtCCO in THF forms only the mono‐insertion product [Cp2Yb{OC(NiPr2)CEtPh}](THF) (3). Hydrolysis of 2 afforded aryl ketone PhEtCHCOC6H4(p‐CHEtCONiPr2) (4) and the overall formation of aryl ketone 4 provides an alternative route to the acylation of aromatic compounds. Moreover, reaction of [{Cp2LnNHPh}2] with excess of PhEtCCO or Ph2CCO in toluene affords only the products from a formal insertion of the CC bond of the ketene into the NH bond, [(Cp2Ln{OC(CHEtPh)NPh})2] (Ln = Yb (5 a), Y (5 b)) or [(Cp2Er{OC(CHPh2)NPh})2] (6), respectively, indicating that an isomerization involving a 1,3‐hydrogen shift occurs more easily than the conjugate electrophilic addition reaction, along with the initial amide attack on the ketene carbonyl carbon. [{Cp2ErNHEt}2] reacts with an excess of PhEtCCO to give [(Cp2Er{PhEtCHCON(Et)COCEtPh})2] (7), revealing another unique pattern of double‐insertion of ketenes into the metal–ligand bond without bond formation between two ketene molecules. All complexes were characterized by elemental analysis and by their spectroscopic properties. The structures of complexes 1 b, 2 a, 2 b, 5 a, 5 b, 6, and 7 were also determined through X‐ray single‐crystal diffraction analysis.
Ruthenium‐Catalyzed Cycloaddition of 1,6‐Diynes and Nitriles under Mild Conditions: Role of the Coordinating Group of Nitriles
Authors: Yamamoto Yoshihiko , Kinpara Keisuke , Ogawa Ryuji , Nishiyama Hisao , Itoh Kenji
Published: June 2006

In the presence of a catalytic amount of [Cp*RuCl(cod)] (Cp*=pentamethylcyclopentadienyl, cod=1,5‐cyclooctadiene), 1,6‐diynes were allowed to react chemo‐ and regioselectively with nitriles bearing a coordinating group, such as dicyanides or α‐halonitriles, at ambient temperature to afford bicyclic pyridines. Careful screening of nitrile components revealed that a CC triple bond or heteroatom substituents, such as methoxy and methylthio groups, proved to act as the coordinating groups, whereas CC or CO double bonds and amino groups failed to promote cycloaddition. This suggests that coordinating groups with multiple π‐bonds or lone pairs are essential for the nitrile components.
Cover Picture: Easily Prepared Air‐ and Moisture‐Stable Pd–NHC (NHC=N‐Heterocyclic Carbene) Complexes: A Reliable, User‐Friendly, Highly Active Palladium Precatalyst for the Suzuki–Miyaura Reaction / A User‐Friendly, All‐Purpose Pd–NHC (NHC=N‐Heterocyclic Carbene) Precatalyst for the Negishi Reaction: A Step Towards a Universal Cross‐Coupling Catalyst (Chem. Eur. J. 18/2006)
Authors: O'Brien Christopher J. , Kantchev Eric Assen B. , Valente Cory , Hadei Niloufar , Chass Gregory A. , Lough Alan , Hopkinson Alan C. , Organ Michael G. , Avola Stephanie , Dubovyk Igor
Published: June 2006

One precatalyst fits all! The ease‐of‐synthesis, high reactivity, and low cost of the PEPPSI (pyridine‐enhanced precatalyst, preparation, stabilization, and initiation) precatalyst greatly improves the ease‐of‐use and reliability of the methodology based on the use of palladium N‐heterocyclic carbene (NHC) complexes. M. Organ et el. report on its use in Suzuki–Miyaura reactions on page 4743 ff. and in Negishi reactions on page 4749 ff.
Bonding Trends in Lewis Acid Adducts of S4N4 – X‐ray Structure of TeCl4·S4N4
Authors: Konu Jari , Bajorek Tom , Laitinen Risto S. , Chivers Tristram , Suontamo Reijo J. , Ahlgrén Markku
Published: June 2006

Tetrasulfur tetranitride and tellurium tetrachloride react in dichloromethane to form a 1:1 adduct TeCl4·S4N4 (1). The crystal structure of 1 shows that TeCl4 is bonded to the S4N4 ring through a Te–N linkage. As a consequence, the transannular S···S bonds in S4N4 are broken and the molecule assumes an open, monocyclic conformation. The Te–N bond of 2.16(1) Å is slightly longer than the single bond. The S–N bonds span a range of 1.55(1)–1.67(1) Å. The adduct 1 was also characterized by mass spectrometry and Raman spectroscopy. The bonding and spectroscopic properties of 1 are compared by DFT calculations at the B3PW91/(RLC ECP) level of theory with those of BF3·S4N4 (2), SO3·S4N4 (3), AsF5·S4N4 (4), SbCl5·S4N4 (5) for which experimental structural information is available. The structural and bonding trends in TeF4·S4N4 (6), TeBr4·S4N4 (7), and SeX4·S4N4 [X = F (8), Cl (9), Br (10)] are also discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Energetic Nitrate, Perchlorate, Azide and Azolate Salts of Hexamethylenetetramine
Authors: Xue Hong , Gao Haixiang , Twamley Brendan , Shreeve Jean’ne M.
Published: June 2006

Hexamethylenetetrammonium salts, composed of energetic anions 3,5‐dinitropyrazolate, 4,5‐dinitroimidazolate, 3,5‐dinitro‐1,2,4‐triazolate, 5‐nitrotetrazolate, perchlorate, nitrate and azide, were synthesized and characterized. The structure of N‐methyl‐hexamethylenetetrammonium 3,5‐dinitro‐1,2,4‐triazolate (6) was confirmed by X‐ray analysis. The standard enthalpies of formation for the new salts were calculated by using the computationally feasible DFT(B3LYP) and MP2 methods in conjunction with an empirical approach based on the densities of the salts. The calculated values range from ΔHf° = –30.6 (7) to +468.8 kJ·mol–1 (10) where the experimental densities > 1.35 g cm–3. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Effect of radio‐opaque filler on biodegradable stent properties
Authors: Chan W.A. , Bini T.B. , Venkatraman Subbu S. , Boey F.Y.C.
Published: June 2006

The effect of the addition of a radio‐opaque filler, barium sulfate (BaSO4), on the mechanical properties of a biodegradable amorphous polymer film (poly‐lactic‐co‐glycolic acid, PLGA) was studied, as a function of degradation. With up to about 18% loading (v/v), the modulus of the filled polymer increases; beyond this concentration, agglomerates are formed. The filled systems are also radio‐opaque, over a thickness range of 0.07–0.19 mm in stent form (helicoidal). These stents were then immersed in phosphate buffer pH 7.4 at 37oC for 2 weeks. The radial strength of stent was measured by using a compression test. It was found that filler‐loaded stent (FS) increased in radial strength by about 4 times (14.95 ± 1.20 N/mm) compared to the unfilled stent (UFS). However, both samples lost radial strength as the polymer degraded in buffer, but FS retained 60% (9.05 ± 0.07 N/mm) of its strength after 2 weeks whereas only 36% (1.39 ± 1.04 N/mm) was retained for UFS. Moreover, UFS lost its helical shape after 3 weeks. The findings have implications for optimization of degradable stent formulations. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Dynamic mechanical properties of 3D fiber‐deposited PEOT/PBT scaffolds: An experimental and numerical analysis
Authors: Moroni L. , Poort G. , Van Keulen F. , de Wijn J.R. , van Blitterswijk C.A.
Published: June 2006

Mechanical properties of three‐dimensional (3D) scaffolds can be appropriately modulated through novel fabrication techniques like 3D fiber deposition (3DF), by varying scaffold's pore size and shape. Dynamic stiffness, in particular, can be considered as an important property to optimize the scaffold structure for its ultimate in vivo application to regenerate a natural tissue. Experimental data from dynamic mechanical analysis (DMA) reveal a dependence of the dynamic stiffness of the scaffold on the intrinsic mechanical and physicochemical properties of the material used, and on the overall porosity and architecture of the construct. The aim of this study was to assess the relationship between the aforementioned parameters, through a mathematical model, which was derived from the experimental mechanical data. As an example of how mechanical properties can be tailored to match the natural tissue to be replaced, articular bovine cartilage and porcine knee meniscus cartilage dynamic stiffness were measured and related to the modeled 3DF scaffolds dynamic stiffness. The dynamic stiffness of 3DF scaffolds from poly(ethylene oxide terephthalate)–poly(butylene terephthalate) (PEOT/PBT) copolymers was measured with DMA. With increasing porosity, the dynamic stiffness was found to decrease in an exponential manner. The influence of the scaffold architecture (or pore shape) and of the molecular network properties of the copolymers was expressed as a scaffold characteristic coefficient α, which modulates the porosity effect. This model was validated through an FEA numerical simulation performed on the structures that were experimentally tested. The relative deviation between the experimental and the finite element model was less than 15% for all of the constructs with a dynamic stiffness higher than 1 MPa. Therefore, we conclude that the mathematical model introduced can be used to predict the dynamic stiffness of a porous PEOT/PBT scaffold, and to choose the biomechanically optimal structure for tissue engineering applications. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Cornea engineering on polyester carriers
Authors: Zorlutuna P. , Tezcaner A. , Kıyat I. , Aydınlı A. , Hasırcı V.
Published: June 2006

In this study, biodegradable polyester based carriers were designed for tissue engineering of the epithelial and the stromal layers of the cornea, and the final construct was tested in vitro. In the construction of the epithelial layer, micropatterned films were prepared from blends of biodegradable and biocompatible polyesters of natural (PHBV) and synthetic (P(L/DL)LA) origin, and these films were seeded with D407 (retinal pigment epithelial) cells. To improve cell adhesion and growth, the films were coated with fibronectin. To serve as the stromal layer of the cornea, highly porous foams of P(L/DL)LA‐PHBV blends were seeded with 3T3 fibroblasts. Cell numbers on the polyester carriers were significantly higher than those on the tissue culture polystyrene control. The cells and the carriers were characterized scanning electron micrographs showed that the foam was highly porous and the pores were interconnected. 3T3 Fibroblasts were distributed quite homogeneously at the seeding site, but probably because of the high thickness of the carrier (∼6 mm); they could not sufficiently populate the core (central parts of the foam) during the test duration. The D407 cells formed multilayers on the micropatterned polyester film. Immunohistochemical studies showed that the cells retained their phenotype during culturing; D407 cells formed tight junctions characteristic of epithelial cells, and 3T3 cells deposited collagen type I into the foams. On the basis of these results, we concluded that the micropatterned films and the foams made of P(L/DL)LA‐PHBV blends have a serious potential as tissue engineering carriers for the reconstruction of the epithelial and stromal layers of the cornea. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Nearly light cycles in embedded graphs and crossing‐critical graphs
Authors: Lomelí Mario , Salazar Gelasio
Published: June 2006

We find a lower bound for the proportion of face boundaries of an embedded graph that are nearly light (that is, they have bounded length and at most one vertex of large degree). As an application, we show that every sufficiently large k‐crossing‐critical graph has crossing number at most 2k + 23. © 2006 Wiley Periodicals, Inc. J Graph Theory 53: 151–156, 2006
Predicting and monitoring response to chemotherapy by 1,3‐bis(2‐chloroethyl)‐1‐nitrosourea in subcutaneously implanted 9L glioma using the apparent diffusion coefficient of water and 23Na MRI
Authors: Babsky Andriy M. , Hekmatyar S. K. , Zhang Hong , Solomon James L. , Bansal Navin
Published: June 2006

Purpose

To examine the effects of the alkylating anticancer drug 1,3‐bis(2‐chloroethyl)‐1‐nitrosourea (BCNU) on 23Na MRI and the water apparent diffusion coefficient (ADC) in subcutaneously‐ (sc‐) implanted 9L glioma in rats.

Materials and Methods

23Na MRI and 1H water ADC measurements were performed on sham‐treated control (N = 6) and BCNU‐treated (N = 15) Fisher rats one day before BCNU injection and then one, three, and five days after BCNU injection.

Results

The BCNU‐treated tumors were divided into BCNU‐responsive (RBCNU) and BCNU‐nonresponsive (NRBCNU) groups depending on the tumor volume changes that occurred after therapy. The pretreatment 23Na MRI signal intensity (SI) and water ADC values were higher in RBCNU tumors compared to NRBCNU tumors. 23Na MRI SI and water ADC increased with tumor growth in control and NRBCNU groups, but these changes were interrupted by BCNU therapy in RBCNU group.

Conclusion

23Na MRI and water ADC measurements may be useful for predicting and monitoring response to chemotherapy in some tumors. However, the changes that occurred in 23Na MRI SI and water ADC in sc‐implanted 9L tumors are in contrast to previously published results for BCNU therapy of orthotopic 9L tumors. This may have important implications for monitoring therapy response in tumors. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Enantiomeric resolution of bifonazole by supercritical fluid chromatography
Authors: Toribio Laura , del Nozal Ma Jesús , Bernal José L. , Alonso Cristina , Jiménez Juan J.
Published: June 2006

The enantiomeric separation of bifonazole by supercritical fluid chromatography on Chiralpak AD has been studied. The effect of different modifiers (methanol, ethanol, 2‐propanol, and acetonitrile) was examined. Enantioseparation was possible with all of them, but the best results were provided by the alcohol‐type ones. The resolution was higher than 5 in all cases. The isoelution temperatures Tiso were calculated from the study of the temperature effect for the different organic modifiers. The value of Tiso was below the working temperature range on using methanol, but above it with ethanol or 2‐propanol.
Botulinum toxin treatment of facial myoclonus in suspected Rasmussen encephalitis
Authors: Browner Nina , Azher Shaheda N. , Jankovic Joseph
Published: June 2006

Patients with Rasmussen encephalitis (RE) may develop a variety of involuntary movements. We report a 26‐year‐old woman who presented with a 3‐year history of progressive, continuous myoclonus of the left side of the face and left arm as well as left spastic hemiparesis. Magnetic resonance imaging of the brain showed right hemisphere and basal ganglia atrophy, and 24‐hour electroencephalogram demonstrated diffuse slowing with random sharp waves in both hemispheres. An 18‐fluoro‐deoxy‐glucose positron emission tomography scan indicated hypometabolism of the right cerebral hemisphere, including basal ganglia and thalamus. We successfully treated her myoclonus with injections of botulinum toxin A into the left zygomaticus muscle. © 2006 Movement Disorder Society
Neutrophils and the blood–brain barrier dysfunction after trauma
Authors: Scholz Martin , Cinatl Jindrich , Schädel‐Höpfner Michael , Windolf Joachim
Published: June 2006

Despite the fact that neutrophils are essential for the protection from invading pathogens, hyperactive neutrophils may elicit detrimental cerebral damage after severe trauma. The neutrophil interactions with the neurovascular unit entail endothelial dysfunction involving endothelial leakage, formation of edema, coagulation abnormalities, disturbed hemodynamics, tissue infiltration etc. These elements of the “whole body inflammation,” designated systemic inflammatory response syndrome (SIRS) in conjunction with intracerebral proinflammatory activities, are important triggers of post‐traumatic cerebral damage and mortality according to the “second hit” concept. From the immunologic point of view, the brain is an immune privileged site, known to resist autodestructive inflammatory activity much more efficiently than other organs because of the highly efficient diverse functions of the blood–brain barrier (BBB). However, both the underlying strategy of the BBB to maintain cerebral protecting functions against the post‐traumatic neutrophil‐mediated “second hit” and how activated neutrophils may overcome the BBB are currently unknown. Therefore, this review summarizes the current understanding of the “second hit,” the BBB physiology, and its role in the maintenance of cerebral immune privilege, and discusses recent findings that may explain the pathophysiologic neutrophil–BBB interactions occurring after severe trauma, thus offering novel therapeutic options to protect from post‐traumatic brain damage. © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 3, 401–416, 2007
Endogenous 5‐HT2B receptor activation regulates neonatal respiratory activity in vitro
Authors: Günther Silke , Maroteaux Luc , Schwarzacher Stephan W.
Published: June 2006

An implication of 5‐HT2B receptors in central nervous system has not yet been clearly elucidated. We studied the role of different 5‐HT2 receptor subtypes in the medullary breathing center, the pre‐Bötzinger complex, and on hypoglossal motoneurons in rhythmically active transversal slice preparations of neonatal rats and mice. Local microinjection of 5‐HT2 receptor agonists revealed tonic excitation of hypoglossal motoneurons. Excitatory effects of the 5‐HT2B receptor agonist BW723C86 could be blocked by bath application of LY272015, a highly selective 5‐HT2B receptor antagonist. Excitatory effects of the 5‐HT2A/B/C receptor agonist α‐methyl 5‐HT could be blocked by the preferential 5‐HT2A receptor antagonist ketanserin. Therefore, 5‐HT‐induced excitation of hypoglossal motoneurons is mediated by convergent activation of 5‐HT2A and 5‐HT2B receptors. Local microinjection of BW723C86 in the pre‐Bötzinger complex increased respiratory frequency. Bath application of LY272015 blocked respiratory activity, whereas ketanserin had no effect. Therefore, endogenous 5‐HT appears to support tonic action on respiratory rhythm generation via 5‐HT2B receptors. In preparations of 5‐HT2B receptor‐deficient mice, respiratory activity appeared unaltered. Whereas BW723C86 and LY272015 had no effects, bath application of ketanserin disturbed and blocked rhythmic activity. This demonstrates a stimulatory role of endogenous 5‐HT2B receptor activation at the pre‐Bötzinger complex and hypoglossal motoneurons that can be taken up by 5‐HT2A receptors in the absence of 5‐HT2B receptors. The presence of functional 5‐HT2B receptors in the neonatal medullary breathing center indicates a potential convergent regulatory role of 5‐HT2B and ‐2A receptors on the central respiratory network. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Activity‐dependent regulation of synaptic size in Drosophila neuromuscular junctions
Authors: Nakayama Hiroaki , Kazama Hokto , Nose Akinao , Morimoto‐Tanifuji Takako
Published: June 2006

One of the fundamental questions in neural development is how neurons form synapses of the appropriate size for the efficient transfer of information across neural circuits. Here we investigated the mechanisms that bring about the size correlation between synapses and postsynaptic cells during development of Drosophila neuromuscular junctions (NMJs). To do this, we made use of a unique system in which two neighboring muscles (M6 and M7) are innervated by the same neurons. In mature NMJs, synaptic size on M6 is normally larger than that on M7, in accordance with the difference in muscle volume; this ensures the same extent of contraction of both muscles, and we refer to this correspondence as “matching”. We found that matching was apparent in larvae 8 h after hatching, but not in newly hatched larvae despite the difference in muscle volume. When sensory inputs were suppressed by the expression of tetanus toxin in sensory neurons, matching did not occur, although synapses were able to grow. Matching was also suppressed by the inhibition of motoneuronal activity. These results suggest that matching is induced by regulating the rate of synaptic growth on M6 and M7 in an experience‐ and activity‐dependent manner. It seems most likely that retrograde signals from the postsynaptic to the presynaptic cell convey the information about muscle cell size. We thus examined whether a candidate of retrograde signaling in NMJs, BMP signaling, is involved inmatching. However, there was no effect on matching inBMP type II receptor gene mutants, suggesting thatother experience‐driven mechanisms besides BMP signaling are involved in the proper development of synapses. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006
Reduced metabolites mediate neuroprotective effects of progesterone in the adult rat hippocampus. The synthetic progestin medroxyprogesterone acetate (Provera) is not neuroprotective
Authors: Ciriza Iratxe , Carrero Paloma , Frye Cheryl A. , Garcia‐Segura Luis M.
Published: June 2006

The ovarian hormone progesterone is neuroprotective in different experimental models of neurodegeneration. In the nervous system, progesterone is metabolized to 5α‐dihydroprogesterone (DHP) by the enzyme 5α‐reductase. DHP is subsequently reduced to 3α,5α‐tetrahydroprogesterone (THP) by a reversible reaction catalyzed by the enzyme 3α‐hydroxysteroid dehydrogenase. In this study we have analyzed whether progesterone metabolism is involved in the neuroprotective effect of the hormone in the hilus of the hippocampus of ovariectomized rats injected with kainic acid, an experimental model of excitotoxic cell death. Progesterone increased the levels of DHP and THP in plasma and hippocampus and prevented kainic‐acid‐induced neuronal loss. In contrast to progesterone, the synthetic progestin medroxyprogesterone acetate (MPA, Provera) did not increase DHP and THP levels and did not prevent kainic‐acid‐induced neuronal loss. The administration of the 5α‐reductase inhibitor finasteride prevented the increase in the levels of DHP and THP in plasma and hippocampus as a result of progesterone administration and abolished the neuroprotective effect of progesterone. Both DHP and THP were neuroprotective against kainic acid. However, the administration of indomethacin, a 3α‐hydroxysteroid dehydrogenase inhibitor, blocked the neuroprotective effect of both DHP and THP, suggesting that both metabolites are necessary for the neuroprotective effect of progesterone. In conclusion, our findings indicate that progesterone is neuroprotective against kainic acid excitotoxicityin vivowhile the synthetic progestin MPA is not and suggest that progesterone metabolism to its reduced derivatives DHP and THP is necessary for the neuroprotective effect of the hormone. © 2006 Wiley Periodicals, Inc. J Neurobiol, 2006