bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of a Temperature-Dependent Mitotic Interval (τo) for Induction of Diploid Meiotic Gynogenetic Paddlefish
Authors: Mims Steven D , Shelton William L , Linhart Otomar , Wang Changzheng , Gomelsky Boris , Onders Richard J
Published: September 2005

We tested the application of mitotic interval (tau [τo]) unit in comparison with absolute time to help standardize preshock timing for a consistent production of diploid meiotic gynogenetic paddlefish Polyodon spathula. The diploid gynogenetic larvae were produced by applying heat shock (35°C; 2 min) at different times after activation of paddlefish eggs with irradiated sperm of shovelnose sturgeon Scaphirhynchus platorynchus at two different preshock temperatures (15°C and 20°C). When the timing of heat shock (minutes after activation) was expressed in absolute time, the yield of gynogenetic diploid larvae was distinctly different between the two preshock incubation temperatures. At 20°C, the highest yield was observed when the timing of the heat shock was 12- 13 min after activation, whereas at 15°C the highest yield was observed when the timing of the heat shock was 17- 22 min after activation. However, when the timing of heat shock was expressed in terms of τo, the yield of gynogenetic diploid larvae for the two preshock incubation temperatures coincided completely at each time point tested. The highest yield (about 30%) of diploid gynogenetic larvae was obtained when the timing of heat shock was between 0.22τo and 0.26τo. Reporting of heat shock timing in terms of τo provides the opportunity to standardize the preshock time interval for any preshock temperature. This could help to identify the optimal timing of heat shock for a specific experiment and allow comparison of data among different experiments in which different preshock temperatures were used.
Migration Timing and River Survival of Late‐Run Fraser River Sockeye Salmon Estimated Using Radiotelemetry Techniques
Authors: English Karl K. , Koski William R. , Sliwinski Cezary , Blakley Anita , Cass Alan , Woodey James C.
Published: September 2005

In recent years, large numbers of late‐run Fraser River sockeye salmonOncorhynchus nerkahave died in freshwater areas before they spawned. We used radiotelemetry techniques to determine river entry timing, migration rates, and survival for the summer and late runs of sockeye salmon in 2002 and 2003. Fishery removals and river detections accounted for 62% of the 873 fish tagged and released in marine areas in 2002. Some late‐run fish migrated from release sites to the Mission hydroacoustic site in 8–10 d and migrated upstream with the summer run. Most late‐run fish remained in the Strait of Georgia for 15–33 d and entered the river after the summer run. Tracking data indicated that individual sockeye salmon maintained essentially the same chronological order as they migrated up the Fraser and Thompson rivers. Summer‐run stocks traveled faster between Mission and the Thompson Junction (33–39 km/d) than late‐run fish (17–21 km/d). After accounting for fishery removals, the river survival rate for summer‐run fish was 92%, and differences between the three release timing groups were not significant. In contrast, the first migration group of late‐run fish that passed Mission had significantly lower survival (13%) than all other timing groups. The survival rate for the second and third river entry groups combined (74%) was significantly lower than that of the fourth group (92%). Period‐specific survival rates were used to define a relationship between river entry timing and survival and to identify additional factors influencing river entry timing for late‐run fish. These relationships may be useful in predicting river survival rates for late‐run stocks in future years.
Exogenous and Fibroblast Growth Factor 2/Epidermal Growth Factor–Regulated Endogenous Cytokines Regulate Neural Precursor Cell Growth and Differentiation
Authors: Deleyrolle Loïc , Marchal-Victorion Sophie , Dromard Cécile , Fritz Vanessa , Saunier Monique , Sabourin Jean-Charles , Tran Van Ba Christophe , Privat Alain , Hugnot Jean-Philippe
Published: September 2005

Neurospheres (NSs) are clonal cellular aggregates composed of neural stem cells and progenitors. A comprehensive description of their proliferation and differentiation regulation is an essential prerequisite for their use in biotherapies. Cytokines are essential molecules regulating cell precursor fate. Using a gene-array strategy, we conducted a descriptive and functional analysis of endogenous cytokines and receptors expressed by spinal cord–derived NSs during their growth or their differentiation into neuronal and glial cells. NSs were found to express approximately 100 receptor subunits and cytokine/secreted developmental factors. Several angiogenic factors and receptors that could mediate neural precursor cell–endothelial cell relationships were detected. Among them, receptor B for endothelins was highly expressed, and endothelins were found to increase NS growth. In contrast, NSs express receptors for ciliary neurotrophic factor (CNTF), bone morphogenetic protein (BMP), interferon (IFN)-γ, or tumor necrosis factor (TNF)-α, which, when added in the growth phase, led to a dramatic growth reduction followed by a reduction or a loss of oligodendrocyte formation on differentiation. In addition, NSs synthesize fibroblast growth factor 2/epidermal growth factor (FGF2/EGF)–regulated endogenous cytokines that participate in their growth and differentiation. Notably, BMP-7 and CNTF were expressed during expansion, but upon differentiation there was a remarkable switch from BMP-7 to BMP-4 and -6 and a sharp increase of CNTF. Reintroduction of growth factors reverses the BMP expression profile, indicating growth factor-BMP cross-regulations. The role of endogenous CNTF was investigated by deriving NSs from CNTF knockout mice. These NSs have an increased growth rate associated with reduction of apoptosis and generate astrocytes with a reduced glial fibulary acidic protein (GFAP) content. These results demonstrate the combined role of endogenous and exogenous cytokines in neural precursor cell growth and differentiation.
Modeling and simulation of hydrothermal oxidation of organic compounds
Authors: Vielcazals S. , Mercadier J. , Marias F. , Matéos D. , Bottreau M. , Cansell F. , Marraud C.
Published: September 2005

Hydrothermal oxidation is an efficient and clean way for the treatment of wastewater containing organic matter. The purpose of this work is to develop a mathematical model of a reactor for hydrothermal oxidation. This reactor is horizontal and tubular and is designed with multi‐injection points of oxidant. Its diameter is very small with regard to its length. The mathematical model is based on the plug flow assumption. The governing equations are: momentum, mass, species, and energy balances. Thanks to this model, the profiles of temperature, and concentration of chemical species are computed along the reactor. The numerical predictions of the model are compared to experimental profiles obtained in the case of supercritical oxidation of methanol. These comparisons show very good agreement. © 2005 American Institute of Chemical Engineers AIChE J, 2006
Synthesis and spectroscopic properties of 4‐ethoxymethylene‐2‐(1)‐naphthyl‐5(4H)‐oxazolone‐labeled fluorescent peptides
Authors: Bősze Szilvia , Csík Gabriella , Kóczán György , Hudecz Ferenc
Published: September 2005

Strategies for the preparation of new fluorescent oligopeptide conjugates labeled with 4‐ethoxymethylene‐2‐[1]‐naphthyl‐5(4H)‐oxazolone (naOx‐OEt) at the N‐terminal on solid support or in solution have been devised. These procedures are simple and easy to carry out by reacting naOx‐OEt or Nα‐naOx–amino acid with side chain protected peptide chains attached to resins. The integrity of the N‐alkyl bond was maintained even after the trifluoracetic acid or HF based cleavages procedures. Our data show that the naOx fluorophore is compatible with both Fmoc/tBu and Boc/Bzl methods and also suggest that naOx–amino acid could be utilized as building blocks for solid phase peptide synthesis. Comparative analysis of fluorescence properties of naOx–conjugates indicated that the spectral properties of the fluorophore do not change after incorporating into peptides. The compact size, the definite chemical reaction for its introduction in combination with the appropriate spectral features (e.g., intense emission, pH independent fluorescent characteristics, and beneficial photobleaching dose constant and rates) and with chemical and spectral stability, naOx‐based labeling could be attractive for novel cellular fluorescent techniques (e.g., in laser scanning confocal FRET) to study peptide–protein and protein–protein interactions even in biological matrices. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 81‐91, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Solution structures of stomoxyn and spinigerin, two insect antimicrobial peptides with an α‐helical conformation
Authors: Landon Céline , Meudal Hervé , Boulanger Nathalie , Bulet Philippe , Vovelle Françoise
Published: September 2005

Stomoxyn and spinigerin belong to the class of linear cysteine‐free insect antimicrobial peptides that kill a range of microorganisms, parasites, and some viruses but without any lytic activity against mammalian erythrocytes. Stomoxyn is localized in the gut epithelium of the nonvector stable fly that is sympatric with the trypanosome vector tsetse fly. Spinigerin is stored and secreted by hemocytes from the fungus‐growing termite. The structure of synthetic stomoxyn and spinigerin in aqueous solution and in TFE/water mixtures was analyzed by CD and NMR spectroscopy combined with molecular modeling calculations. Stomoxyn and spinigerin adopt a flexible random coil structure in water while both assume a stable helical structure in the presence of TFE. In 50% TFE, the structure of stomoxyn is typical of cecropins, including an amphipathic helix at the N‐terminus and a hydrophobic C‐terminus with helical features that probably fold in a helical conformation at higher TFE concentration. In contrast to stomoxyn, spinigerin acquires very rapidly a helical conformation. In 10% TFE the helix is highly bent and the structure is poorly defined. In 50% TFE, the helical structure is well defined all along its sequence, and the slightly bent α‐helix displays an amphiphilic character, as observed for magainin 2. The structural similarities between stomoxyn and cecropin A from Hyalophora cecropia and between spinigerin and magainin 2 suggest a similar mode of action on the bacterial membranes of both pairs of peptides. Our results also confirm that TFE induces helix formation and propagation for amino acids showing helical propensity in water but also enhances the helix propagation propensity of nonpolar β‐branched residues. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 92–103, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Examination of dye–protein interaction by gel‐permeation chromatography
Authors: Sereikaite Jolanta , Bumelis Vladas‐Algirdas
Published: September 2005

The interaction of Cibacron blue F3G‐A with two therapeutic proteins, recombinant human growth hormone and recombinant human interferon‐α2b, has been examined by applying gel‐permeation chromatography in combination with the absorption difference spectroscopy. The complexes of these proteins with Cibacron blue F3G‐A have been isolated, and their absorbance spectra have been registered. The influence of Cibacron blue F3G‐A on the oligomeric state of proteins has been investigated. It was found that Cibacron blue F3G‐A promotes the generation of interferon‐α2b dimers at pH 5.0. Copyright © 2005 John Wiley & Sons, Ltd.
Stability of Gaseous Thallium Monofluoride as TlF0, TlF+, and TlF2+.
Authors: Schroeder Detlef , van Wuellen Christoph , Schwarz Helmut , Klapoetke Thomas M.
Published: September 2005

For Abstract see ChemInform Abstract in Full Text.
Size Tuning, Functionalization, and Reactivation of Au in TiO2 Nanoreactors.
Authors: Li Jing , Zeng Hua Chun
Published: September 2005

For Abstract see ChemInform Abstract in Full Text.
Aza‐Annulation of Polarized N,S‐ and N,N‐Ketene Acetals with Itaconic Anhydride: Synthesis of Novel Functionalized 1,2,3,4‐Tetrahydro‐2‐pyridones and Related Azabicycles.
Authors: Chakrabarti Sriparna , Panda Kausik , Misra Nimesh C. , Ila Hiriyakkanavar , Junjappa Hiriyakkanavar
Published: September 2005

For Abstract see ChemInform Abstract in Full Text.
Highly Efficient and Regioselective Synthesis of 1,1‐Bis(alkoxydimethylsilyl)ethenes.
Authors: Pawluc Piotr , Hreczycho Grzegorz , Marciniec Bogdan
Published: September 2005

For Abstract see ChemInform Abstract in Full Text.
Synthesis of Fluorous Nitrogen Ligands and Their Metal Complexes as Precatalysts for Applications in Alkane, Alkene, and Alcohol Oxidation, and Atom Transfer Radical Reactions
Authors: Vincent Jean‐Marc , Lastecoueres Dominique , Contel Maria , Laguna Mariano , Fish Richard H.
Published: September 2005

For Abstract see ChemInform Abstract in Full Text.
Catalytic enantioselective addition of indoles to arylnitroalkenes: An effective route to enantiomerically enriched tryptamine precursors
Authors: Bandini Marco , Garelli Andrea , Rovinetti Matteo , Tommasi Simona , Umani‐Ronchi Achille
Published: September 2005

A new valuable catalytic protocol for the preparation of synthetically useful β‐indolyl nitro compounds bearing benzhydryl stereocenters is presented. The combined use of catalytic amounts of a commercially available chiral [SalenAlCl] complex and pyridine allowed, for the Friedel–Crafts alkylation reaction of indoles with aromatic nitro‐olefins to be carried out in good yields and enantioselectivity (up to 63% ee). © 2005 Wiley‐Liss, Inc. Chirality 17:522–529, 2005.
Chromosomal imbalances in laryngeal and hypopharyngeal cancers detected by comparative genomic hybridization
Authors: Juhász Attila , Balázs Margit , Sziklay István , Rákosy Zsuzsa , Treszl Andrea , Répássy Gábor , Ádány Róza
Published: September 2005

Background

The prognostic divergence of laryngeal and hypopharyngeal carcinomas is well known. Hypopharyngeal tumors are characterized by frequent metastasis formation and local recurrence, which is the source of the unfavorable prognosis of this subtype. The aim of this study was to define chromosomal alterations associated with the aggressive behavior of hypopharyngeal tumors.

Methods

Twenty‐nine head and neck squamous cell carcinomas (larynx n = 14 and hypopharynx n = 15) were analyzed by comparative genomic hybridization (CGH). Fluorescence in situ hybridization (FISH) was used to validate the CGH data and to compare the amplification pattern of the most frequently altered gene (cyclin‐D1, CCND1) located on 11q13.

Results

The average number of genetic alterations was significantly higher in the hypopharyngeal tumors (P = 0.02). A good correlation of FISH and CGH data were seen. Gains on 11q13 were present in both subtypes, whereas amplification of CCND1 was associated with the aggressive phenotype by FISH. Chromosomal alteration, which was rarely detected in hypopharyngeal tumors but was observed in more than 50% of laryngeal carcinomas, was 8q gain.

Conclusion

Our CGH and FISH data show that head and neck squamous cell carcinomas contain complex cytogenetic alterations and further support the hypothesis that different molecular pathways are responsible for the progression of differently localized tumors of the upper aerodigestive tract. © 2005 International Society for Analytical Cytology
Flow cytometer in the infrared: Inexpensive modifications to a commercial instrument
Authors: Stewart Carleton C. , Woodring Mitchell L. , Podniesinski Edward , Gray Brian
Published: September 2005

Background

The application of molecules that fluoresce in the infrared (IR) region to measure cell products would be enhanced by a flow cytometer capable of measuring them. To our knowledge, none exist at this time. Accordingly, we have developed such an instrument.

Methods

A Becton Dickinson LSR flow cytometer was modified to include a small 785‐nm IR diode laser the size of a C cell battery with 44‐mW output power. The instrument was modified further to accommodate this laser in addition to a 405‐nm solid‐state laser, a 488‐nm air‐cooled argon laser, and a 658‐nm solid‐state laser. Because the IR laser is dangerous to the eye, the laser beams were viewed for optical alignment using a CCD camera and video monitor. An avalanche photodiode was used in place of a photomultiplier tube because its detection sensitivity in the IR region is superior.

Results

To assess performance, scatter and florescence measurements were made using microspheres that fluoresce in the IR region, and human leukocytes were stained with CD45 biotin followed by a streptavidin conjugated with an IR dye. An avalanche photodiode was 2.3 to 2.8 times more sensitive than a photomultiplier tube for detecting IR fluorescence. Cells stained with CD45 biotin and avidin conjugated with an IR dye could easily be resolved and their fluorescence quantified; there was virtually no autofluorescence. In addition, a lipophilic membrane dye that emits in the IR region was studied. HL60 cells were stained with this dye and they exhibited bright fluorescence intensity.

Conclusion

A commercial instrument could be modified to accommodate an IR laser for exciting dyes that fluoresce in the IR region. This new capability will extend the range of fluorescence that can be measured by flow cytometry. © 2005 International Society for Analytical Cytology
Selective photoreactions in a programmable array microscope (PAM): Photoinitiated polymerization, photodecaging, and photochromic conversion
Authors: Fulwyler Mack , Hanley Quentin S. , Schnetter Christoph , Young Ian T. , Jares‐Erijman Elizabeth A. , Arndt‐Jovin Donna J. , Jovin Thomas M.
Published: September 2005

Background

Innovative thinking and experimentation were the hallmarks of Mack Fulwyler's approach to research. This report summarizes some of the ideas and their early realizations that he pursued in the field of imaging cytometry, work that was not published before his untimely death, although he composed the initial draft of this report.

Methods

Included are related experiments implemented in the programmable array microscope (PAM) devised for patterned illumination and detection, the instrument that Mack Fulwyler employed during a sabbatical leave in Göttingen in 1998. Despite being the originator of instrumentation for flow cytometry and sorting, Mack Fulwyler was intensely interested in imaging systems, recognizing their ability to resolve cellular details obscured by the whole cell signals generally acquired in flow. At one point, these interests merged with those of two other authors (I.T.Y. and T.M.J.), leading to the Image Cytometry and Sorting (ICAS) strategy and project. A major goal was uncomplicated rare cell detection and isolation using a sequential process of cellular labeling via suitable probes, whole field imaging, and selective area‐restricted photoinduced reactions designed to encapsulate and/or chemically or physically tag cells in a manner permitting subsequent fractionation by bulk techniques.

Results and Conclusion

This publication features photoinduced polymerization, photodecaging, photoactivation, and photochromic conversion reactions carried out by Fulwyler and/or the other authors with the PAM, employing operator designated patterns and locations in various samples. Photopolymerization of polyethylene glycol‐diacrylate to a gel‐like structure allowing the specific selection of objects (cells) for further analysis and processing techniques was the approach explored personally by Mack Fulwyler in relation to the ICAS concept. © 2005 International Society for Analytical Cytology
Flow cytometric analysis of fluorescence in situ hybridization with dye dilution and DNA staining (flow‐FISH‐DDD) to determine telomere length dynamics in proliferating cells
Authors: Potter Alan J. , Wener Mark H.
Published: September 2005

Background

Telomeres shorten during DNA replication; extensive erosion of telomeres likely promotes replicative senescence and chromosomal instability. Telomere length in individual cells has been quantified by flow cytometric analysis of fluorescence in situ hybridization (flow‐FISH). To determine the rate of telomere attrition (telomere erosion per cell division), we combined flow‐FISH with dye dilution and DNA staining (flow‐FISH‐DDD) and measured telomere‐specific fluorescence in proliferating cells identified by cell generation and cell cycle phase.

Methods

Peripheral blood mononuclear cells (PBMC) were stained with the cell division tracking dye carboxyfluorescein diacetate succinimidyl ester (CFSE), stimulated with phytohemagglutinin (PHA), grown for 5–6 days, hybridized with a telomere sequence‐specific peptide nucleic acid fluorescent probe (PNA‐Cy5), counterstained with DAPI, and analyzed by flow cytometry. The cell cycle distribution and cell division generations were respectively identified by analysis of DAPI emission and deconvolution of CFSE emission, and Cy5 emission was used to determine telomere‐specific fluorescence, an indicator of telomere length, in each cell.

Results

In stimulated PBMC, in each cell cycle phase, the telomere‐specific fluorescence diminished with increasing cell generation. The rate of decline of the telomere‐specific fluorescence per cell generation did not significantly differ between cell cycle phases.

Conclusions

Application of flow‐FISH‐DDD to measure mean telomere length and the rate of telomere attrition in proliferating cells may find use in studies of ageing and disease, the effects of telomere‐modifying agents, and variability between individuals. © 2005 International Society for Analytical Cytology
Lens and retina formation require expression of Pitx3 in Xenopus pre‐lens ectoderm
Authors: Khosrowshahian Farhad , Wolanski Marian , Chang Wing Y. , Fujiki Kazuhiro , Jacobs Larry , Crawford Michael J.
Published: September 2005

Pitx3 is expressed in tissues fated to contribute to eye development, namely, neurula stage ectoderm and prechordal mesoderm, then presumptive lens ectoderm, placode, and finally lens. Pitx3 overexpression alters lens, optic cup, optic nerve, and diencephalon development. Many of the induced anomalies are attributable to midline deficits; however, as assessed by molecular markers, ectopic Pitx3 appears to temporarily enlarge the lens field. These changes are usually insufficient to generate either ectopic lenses to enlarge the eye that eventually differentiates. Conversely, use of a repressor chimera or of antisense morpholinos alters early expression of marker genes, and later inhibits lens development, thereby abrogating retinal induction. Reciprocal grafting experiments using wild‐type and morpholino‐treated tissues demonstrate that Pitx3 expression in the presumptive lens ectoderm is required for lens formation. Contradictory to recent assertions that retina can form in the absence of a lens, the expression of Pitx3 in the presumptive lens ectoderm is critical for retina development. Developmental Dynamics 234:577–589, 2005. © 2005 Wiley‐Liss, Inc.
Cross‐presentation of oral antigens by liver sinusoidal endothelial cells leads to CD8 T cell tolerance
Authors: Limmer Andreas , Ohl Jutta , Wingender Gerhard , Berg Martina , Jüngerkes Frank , Schumak Beatrix , Djandji Dominik , Scholz Kai , Klevenz Alexandra , Hegenbarth Silke , Momburg Frank , Hämmerling Günter J. , Arnold Bernd , Knolle Percy A.
Published: September 2005

After ingestion, oral antigens distribute systemically and provoke T cell stimulation outside the gastrointestinal tract. Within the liver, scavenger liver sinusoidal endothelial cells (LSEC) eliminate blood‐borne antigens and induce T cell tolerance. Here we investigated whether LSEC contribute to oral tolerance. Oral antigens were efficiently cross‐presented on H‐2Kb by LSEC to naive CD8 T cells. Cross‐presentation efficiency in LSEC but not dendritic cells was increased by antigen‐exposure to heat or low pH. Mechanistically, cross‐presentation in LSEC requires endosomal maturation, involves hsc73 and proteasomal degradation. H‐2Kb‐restricted cross‐presentation of oral antigens by LSEC in vivo induced CD8 T cell priming and led to development of CD8 T cell tolerance in two independent experimental systems. Adoptive transfer of LSEC from mice fed with antigen (ovalbumin) into RAG2–/– knockout mice, previously reconstituted with naive ovalbumin‐specific CD8 T cells, prevented development of specific cytotoxicity and expression of IFN‐γ in CD8 T cells. Using a new transgenic mouse line expressing H‐2Kb only on endothelial cells, we have demonstrated that oral antigen administration leads to tolerance in H‐2Kb‐restricted CD8 T cells. Collectively, our data demonstrate a participation of the liver, in particular scavenger LSEC, in development of CD8 T cell tolerance towards oral antigens.
The BTG/TOB family protein TIS21 regulates stage‐specific proliferation of developing thymocytes
Authors: Konrad Mark A. P. , Zúñiga‐Pflücker Juan Carlos
Published: September 2005

As thymocytes undergo differentiation in the thymus, they progress through distinct phases of quiescence and proliferation. Identifying cellular mechanisms that maintain thymocytes in a non‐dividing state is critical to fully understand T cell development. A member of the B cell translocation gene/transducer of ErbB‐2 (BTG/TOB) family of anti‐proliferative proteins was identified as a key mediator of the quiescent state in peripheral anergic and unstimulated T cells. Here, we demonstrate that the BTG/TOB family member TPA‐inducible sequence 21 (TIS21) is expressed in quiescent CD44+CD25– early progenitor thymocytes and CD44–CD25+ cells prior to TCR β‐selection. However, TIS21 expression is decreased in proliferating CD25+CD44+ progenitor thymocytes and CD25lowCD44– β‐selected cells, suggesting that its regulated expression may enable thymocytes to remain quiescent in the absence of mitogenic signals. We addressed the role of TIS21 in regulating thymocyte stage‐specific expansion by ectopically expressing TIS21 in developing thymocytes and hematopoietic progenitors. Dysregulated expression of TIS21 inhibited the expansion of thymocytes even in the presence of endogenous mitogenic signals, while thymocyte differentiation was unimpeded. These findings imply that the intracellular mechanisms regulating thymocyte differentiation and proliferation, which are induced downstream of developmental cues, function independently during early T cell development.
Base‐Induced Trifluoroethanolysis of Acyclic Di‐ and Trihalogeno Ketones: Favorskii Rearrangement and [4+3] Cycloaddition
Authors: Föhlisch Baldur , Franz Thilo , Kreiselmeier Günter
Published: September 2005

Reactions of five acyclic dihalogeno‐ and trihalogeno ketones, representing the α,α‐, α,α′‐, α,α,α‐ and α,α,α′‐di‐ and trihalogeno substitution pattern, with sodium 2,2,2‐trifluoroethoxide in 2,2,2‐trifluoroethanol (NaTFE/TFE) in the presence of furan were investigated with the aim of obtaining [4+3] cycloadducts of the corresponding oxyallyl intermediates. Preference of Favorskii rearrangement over cycloaddition was observed with dichloromethyl isobutyl ketone (1a) and 1,3‐dibromobutan‐2‐one (12) that formed mainly the trifluoroethyl esters of 3‐chloro‐2‐isopropylpropanoic acid (9a), and (Z)‐but‐2‐enoic acid (isocrotonic acid) (13), respectively. 9a was dehydrohalogenated to form trifluoroethyl 3‐isopropylacrylate (11a). [4+3] Cycloaddition was favored with the 1,1,3‐trihalogenobutan‐2‐ones 24 and 25, leading to 2,4‐dihalogenated 8‐oxabicyclo[3.2.1]oct‐6‐en‐3‐ones (26, 27) as a mixture of endo‐exo‐stereoisomers. With trichloromethyl isobutyl ketone (30) the isomeric 2,4‐dichloro‐substituted oxabicycles (34) were formed in lithium perchlorate/diethyl ether/furan/triethylamine, while in NaTFE/TFE solvolytic displacement of one chloro substituent occurred, providing 2‐chloro‐4‐trifluoroethoxy‐4‐isopropyl‐8‐oxabicyclo[3.2.1]oct‐6‐en‐3‐one (36). By analogy, 27 reacted with sodium methoxide/methanol to form the methoxy‐substituted oxabicycles 39a and 39b. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Postmenopausal hormone therapy and breast cancer risk: The multiethnic cohort
Authors: Lee Sulggi , Kolonel Laurence , Wilkens Lynne , Wan Peggy , Henderson Brian , Pike Malcolm
Published: September 2005

Epidemiological studies indicate that menopausal estrogen‐progestin therapy (EPT) use is associated with an increase in breast cancer risk. Further data are needed on whether this association varies by specific prognostic factors and ethnicity. We conducted a cohort study among 55,371 African‐American, Native Hawaiian, Japanese‐American, Latina and White postmenopausal women aged 45–75 years old in the Multiethnic Cohort Study (MEC). A total of 1,615 incident invasive breast cancer cases were identified over an average of 7.3 years. Adjusted relative risks (RRs) were computed for the various forms of hormone therapy (HT). Assuming current users continued HT use to the end of follow‐up, current EPT use was associated with a 29% increased risk of breast cancer per 5 years of use (95% confidence interval (CI) = 23–35%), and current estrogen therapy (ET) use with a 10% increase in risk per 5 years of use (95% CI = 5–16%). These figures increased to only a very small extent when we adjusted for the estimated ˜3% of such women who stop HT use per year of follow‐up. EPT and ET use were associated with greater risk among leaner women, but the increase in risk with EPT use was still very evident in women with BMI ≥30 kg/m2. Current EPT use was associated with increased risk for ER+/PR+, ER+/PR‐ and ER‐/PR‐ tumors. There was little difference in risk by stage of disease or histologic subtype. The increase with EPT use was clearly seen in all 5 ethnic groups; and the increase with ET in 4 of the 5 groups. © 2005 Wiley‐Liss, Inc.
Overexpression of ORC subunits and increased ORC‐chromatin association in transformed mammalian cells
Authors: McNairn Adrian J. , Gilbert David M.
Published: September 2005

The origin recognition complex (ORC) is a conserved heterohexamer required for the formation of pre‐replication (pre‐RC) complexes at origins of DNA replication. Many studies of ORC subunits have been carried out in transformed human cell lines but the properties of ORC in primary cells have not been addressed. Here, we compare the expression levels and chromatin‐association of ORC subunits in HeLa cells to the primary human cell line, WI38, and a virally transformed derivative of WI38, VA13. ORC subunits 2 and 4 were highly overexpressed in both HeLa and VA13, whereas ORC1 levels were elevated in VA13 but considerably higher in HeLa cells. Cellular extraction revealed that the proportion of ORC2 and ORC4 subunits bound to chromatin was similar in all three cell lines throughout the cell‐cycle. In contrast, very little ORC1 was associated with chromatin after extraction of primary WI38 cells, whereas the majority of overexpressed ORC1 in both HeLa and VA13 co‐fractionated with chromatin throughout the cell‐cycle. Although none of the cell lines displayed significant changes in the levels or chromatin‐association of ORC during the cell‐cycle, the chromatin‐associated fraction of ORC1 displayed an increase in apparent molecular weight during S‐phase. Similar experiments comparing immortalized CHO cells to an isogenic virally transformed derivative revealed no changes in levels of ORC subunits but an increase in the proportion of all three ORC subunits associated with chromatin. These results demonstrate a complex influence of cellular immortalization and transformation properties on the expression and regulation of ORC subunits. These results extend the potential link between cancer and deregulation of pre‐RC proteins, and underscore the importance of considering the transformation status of cell lines when working with these proteins. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Force field validation for nucleic acid simulations: Comparing energies and dynamics of a DNA dodecamer
Authors: Jha Shantenu , Coveney Peter V. , Laughton Charles A.
Published: September 2005

Important questions exist regarding the quality of force fields used in molecular dynamics (MD) simulations and their interoperable use with other available MD implementations. NAMD is one of the most efficient and scalable parallel molecular dynamics codes for large‐scale biomolecular simulations in the open source domain. It is the aim of this article to analyze and compare the dynamics of a benchmark DNA dodecamer d(CTTTTGCAAAAG)2 system, including its binding to a specific drug molecule arising from the use of various simulation protocols in NAMD using Amber98, with the dynamics arising from simulations of the same dodecamer using Amber98 in the AMBER package, one of the most well‐established simulation codes for nucleic acids. Based upon a set of validation benchmarks, the details of which are discussed, we find that nucleic acid simulations using NAMD give meaningful results and that the essential features of the resulting dynamics are similar to those arising from the AMBER package. This sets the stage for reliable large‐scale simulations of nucleic acids using NAMD. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1617–1627, 2005
Development of zebrafish (Danio rerio) pectoral fin musculature
Authors: Thorsen D.H. , Hale M.E.
Published: September 2005

During posthatching development the fins of fishes undergo striking changes in both structure and function. In this article we examine the development of the pectoral fins from larval through adult life history stages in the zebrafish (Danio rerio), describing in detail their pectoral muscle morphology. We explore the development of muscle structure as a way to interpret the fins' role in locomotion. Genetic approaches in the zebrafish model are providing new tools for examining fin development and we take advantage of transgenic lines in which fluorescent protein is expressed in specific tissues to perform detailed three‐dimensional, in vivo fin imaging. The fin musculature of larval zebrafish is organized into two thin sheets of fibers, an abductor and adductor, one on each side of an endoskeletal disk. Through the juvenile stage the number of muscle fibers increases and muscle sheets cleave into distinct muscle subdivisions as fibers orient to the developing fin skeleton. By the end of the juvenile period the pectoral girdle and fin muscles have reoriented to take on the adult organization. We find that this change in morphology is associated with a switch of fin function from activity during axial locomotion in larvae to use in swim initiation and maneuvering in adults. The examination of pectoral fins of the zebrafish highlights the yet to be explored diversity of fin structure and function in subadult developmental stages. J. Morphol. © 2005 Wiley‐Liss, Inc.
Public eProcurement as socio‐technical change
Authors: Williams Susan P. , Hardy Catherine
Published: September 2005

ERP systems and those that support enterprise‐wide business activities such as eProcurement represent complex socio‐technical change.

The imperative for researchers and practitioners is to identify ways of understanding and develop methods to assist in managing the complexity and messiness associated with the breadth and depth of change as the affordances of technologies and the needs of users emerge over time.

In this paper theoretical concepts are presented and an empirical illustration of three cases of public eProcurement implementations is provided to make visible and make sense of the complex twists and turns of socio‐technical change.

These experiences reveal the nuances of socio‐technical change, its fluid and emergent nature, the effect of unintended consequences, the role of influential agents and change in the representations of work practices.

These theoretical concepts are analytically powerful and could provide practitioners with useful tools in understanding the envisaged and serendipitous nature of socio‐technical change and the intended and unintended outcomes that may emerge in implementing enterprise‐wide business information systems.

Copyright © 2005 John Wiley & Sons, Ltd.
Thermal decomposition kinetics of palladium(II) 1‐allylimidazole complexes
Authors: Vecchio Stefano , Materazzi Stefano , Kurdziel Krystyna
Published: September 2005

Thermal dehydration and decomposition processes of a Pd(II) coordination compound, [PdL4]Cl2·3H2O (1), (where L is 1‐allylimidazole) were studied by simultaneous TG/DSC techniques under constant heating rates condition. The released gas products were analyzed by online coupling a FTIR spectrometer to the TG equipment. The so obtained evolved gas analysis confirmed that only two ligand molecules were released and that a new 1‐allylimidazole Pd(II) complex, trans‐[PdL2Cl2] (2a), was obtained. The same coordination compound was also prepared by heating 1 at 413.15 K in air atmosphere until a constant weight was reached 2b. Thermal decomposition mechanisms for the 2a and 2b complexes examined were proposed according to the three mass loss steps derived by TG data. Based on the model‐free isoconversional method described by Flynn–Wall–Ozawa (FWO), the dependencies of activation energy on the degree of conversion were determined. A model‐free “single point” method was also applied using the Kissinger equation, and derived results were compared to those of the former method. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 667–674, 2005
Effect of substituents on the rate of oxidation of anilines with peroxomonosulfate monoanion (HOOSO−3) in aqueous acetonitrile: A mechanistic study
Authors: Meenakshisundaram Subbiah , Selvaraju M. , Gowda N. M. Made , Rangappa Kanchugarakoppal S.
Published: September 2005

Mechanistic studies on the oxidation of 18 meta‐, para‐, and ortho‐substituted anilines (Ans) by HOOSO−3 in aqueous acetonitrile medium have been performed. The reaction can be characterized by the experimental rate equation,

equation image

The addition of p‐toluenesulfonic acid (TsOH) retards the reaction. The increase in the reactivity of anilines as the medium is made more aqueous is interpreted. The reaction is enhanced by electron‐donating groups on the amine in the series consistent with the rate‐limiting nucleophilic attack of the amine on the persulfate oxygen. The proposed mechanism involves the conversion of phenylhydroxylamine to nitrosobenzene in a fast step. The ESR study reveals the absence of free radicals in the reaction. Various attempts have been made to analyze the experimental rate constants in terms of LFER plots. Improved correlations are obtained with σ− values and the σ− form of the Yukawa–Tsuno equation. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 649–657, 2005
Dual‐level direct dynamics study on the reactions of SH (SD) with F2
Authors: Wang Li , Liu Jing‐yao , Li Ze‐Sheng , Sun Chia‐chung
Published: September 2005

The dual‐level direct dynamics study is carried out in the reactions of SH (SD) + F2, and enthalpies of formation for the species FSH (FSD) are evaluated using isodesmic reactions. Furthermore, the dynamics calculations are performed using the variational transition‐state theory (VTST) with interpolated single‐point energies (ISPE) method at the approximate QCISD(T)/6‐311++G(3df, 2pd)//MPW1K/6‐311G(d, p) level. Over the temperature range of 200–2000 K, theoretical rate constants evaluated using canonical variational transition state theory (CVT) are in good agreement with the available experimental values. The kinetic isotope effects for the title reactions are not obvious. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 710–716, 2005
Electrochemical impedance spectroscopy study of surface films formed on copper in aqueous environments
Authors: Srivastava A. , Balasubramaniam R.
Published: September 2005

The electrochemical behavior of pure copper has been studied in aqueous environments using linear polarization and electrochemical impedance spectroscopy (EIS) techniques as a function of immersion time. The effect of pollutants (like chloride, sulfide and ammonium ions) on the nature of films formed on the copper surface has been studied. All the surfaces revealed the presence of a porous oxide layer. The corrosion resistance decreased with increasing amount of chloride ions. The addition of Na2S in the environments in the absence of any chloride species was beneficial for corrosion resistance. EIS data suggested that the capacitance of the films formed in chloride environments was higher. The surfaces obtained in presence of chloride ions were relatively rough and deeply attacked. The total impedance decreased after 432 h of immersion in solutions possessing chloride ions. The damaging role of chloride ions and the relatively less severe effect of sulfide ions were noted.
Directed Crystallisation of Poly(ε‐caprolactone) using a Low‐Molar‐Mass Self‐Assembled Template
Authors: Wangsoub Supatra , Olley Robert H. , Mitchell Geoffrey R.
Published: September 2005

Summary: We show that small quantities of dibenzylidene sorbitol dispersed in poly(ε‐caprolactone) coupled with shear flow provide a self‐assembling nanoscale framework to yield high levels of crystal orientation. During modest shear flow of the melt, the additive forms highly extended nanofibrils which adopt a preferred alignment with respect to the flow field, and on cooling polymer crystallisation is directed by these fibrils. We use in situ time‐resolving SAXS and WAXS techniques to explore how this behaviour can be modified by the composition, the shear rate and strain as well as the temperature at which the shear flow is imposed. SAXS studies show that the 3% DBS completely dissolves in the PCL melt at temperatures ≥120 °C and that any shear flow imposed at temperatures above such values is ineffective in directing crystallisation.

SAXS pattern of crystallized PCL after cooling.

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SAXS pattern of crystallized PCL after cooling.
Effect of Decoupling of Molecular Segments, Microscopic Stress‐Transfer and Confinement of the Nanophases in Semicrystalline Polymers
Authors: Wunderlich Bernhard
Published: September 2005

Summary: Semi‐crystalline macromolecules are globally metastable, multi‐phase systems with phase dimensions ranging from micrometers to nanometers. The polymer molecules, being usually longer than one micrometer, cross the boundaries and decouple at the interfaces. This decoupling is often not complete and different degrees of influence are extended across the interfaces. Thermodynamically, crystals can be characterized by their melting behavior and non‐crystalline phases by their glass transition. On weak coupling, the non‐crystalline segments only show a broadening of the glass transition to higher temperature. With stronger coupling, non‐crystalline material may remain solid at the transition of the bulk‐amorphous phase and form a separate, rigid‐amorphous nanophase, or rigid amorphous fraction, RAF. The RAF undergoes its glass transition either below, at, or even above, the melting temperature. In the presence of a RAF, the semi‐crystalline polymers may be a system of three or more types of phases with different relaxation effects due to the coupling between the phases. This and other examples of decoupling are discussed here and a general concept is developed. This applies to positional decoupling at positions of chemical changes within the molecule, such as in copolymers, and to physical changes, such as in entanglements, and is not limited to decoupling at interfaces. Finally, it is pointed out that there is also the possibility of a temporal decoupling of thermodynamically simultaneous changes, which on sufficiently slow kinetics in one may change to consecutive changes. Many of these aspects of decoupling on a molecular scale influence the macroscopic properties and must be considered for the analysis and application of modern materials.

Illustration of reversible melting of folded chain crystals.

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Illustration of reversible melting of folded chain crystals.
The male perineal sling: Intermediate‐term results
Authors: Comiter Craig V.
Published: September 2005

Aims

In men with stress urinary incontinence (SUI) due to sphincteric incompetence, surgical options include periurethral injection of bulking agents, implantation of an artificial urinary sphincter (AUS), and sling surgery. Short‐term results of the male sling have generally been favorable. We report the intermediate‐term results of the bone‐anchored male perineal sling with a median of 4 years and minimum of 2 years follow‐up.

Methods

From March 2000 to April 2003, 48 patients (average age = 68 years) underwent male sling surgery. Patients were evaluated pre‐operatively and post‐operatively via history, physical examination, pad score, and administration of the incontinence section of the UCLA/RAND prostate cancer index (PCI).

Results

Pre‐operatively all patients rated their incontinence as severe, and used ≥3 pads daily. Median follow‐up was 48 months (range = 24–60). Average pad usage decreased from 4.6 ± 2.1 pads per day to 1.0 ± 1.7 pads per day (P < 0.01). Median UCLA PCI incontinence score increased from 63–343 (P < 0.01). Overall, 31/48 patient (65%) were cured of their leakage (no problem, no pads), 7/48 (15%) were much improved (small problem, 1 pad), 3/48 (6%) were mildly improved (moderate problem, 2 pads daily), and 7/48 (15%) failed (big problem, ≥3 pads).

Conclusions

Intermediate‐term results for the male sling demonstrate a success rate comparable to that of the AUS (80% ≤ 1 pad daily). This technique has established a very low morbidity, and is a reliable alternative to AUS surgery for the treatment of male SUI. Neurourol. Urdynam. © 2005 Wiley‐Liss, Inc.
Predictors of satisfaction among cognitively intact nursing home residents in Hong Kong
Authors: Lee Linda Y.K. , Lee Diana T.F. , Woo Jean
Published: September 2005

Resident satisfaction is widely recognized as a critical dimension in assessing quality of nursing home care. Although many factors are associated with satisfaction, little is known about the relative importance of these factors in predicting satisfaction. The purpose of this study was to identify the demographic, physiological, psychological, and social predictors of satisfaction in a convenience sample of 175 nursing home residents in Hong Kong. Seventeen resident variables were investigated. Variables that showed significant bivariate associations with satisfaction were entered into the stepwise regression model. Health‐related quality of life (mental component), state self‐esteem, and social support satisfaction, significantly accounted for 31% of the variance of satisfaction. These findings suggest approaches to tailor care plans to increase resident satisfaction. © 2005 Wiley Periodicals, Inc. Res Nurs Health 28: 376–387, 2005.