bluuebunny/crossref_metadata_2025 huggingface dataset:
Graft interpenetrating polymer networks of polyurethane and epoxy containing rigid rods in side chain
Authors: Han J. L. , Lin S. P. , Ji S. B. , Hsieh K. H.
Published: August 2007

The rigid rod‐like 4,4′‐bis(6‐hydroxyhexyloxy)biphenyl (BHHBP) units were distributed in either the epoxy or polyurethane to become SR‐epoxy and PU (with or without BHHBP) polymer matrices. The interpenetrating polymer networks (IPNs) of PU (with or without BHHBP) and SR‐epoxy were synthesized through simultaneous polymerization, and connected each other via the grafting reaction between the NCO groups of the PU polymer network and the OH groups on the side chains of SR‐epoxy network. The thermal and mechanical characteristics, compatibilities, and morphologies of these PU (with or without BHHBP)/SR‐epoxy graft‐IPNs were investigated. The polyether‐type PU(PPG series)/SR‐ epoxy graft‐IPNs exhibited two‐phased morphologies (i.e., phase separation occurred), and higher fracture energies (GIC). Whereas the polyester‐type PU(PBA series)/SR‐ epoxy graft‐IPNs were homogeneous (no phase separation), and exhibited higher tensile and Izod impact strengths. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Study of wettability and improvement of adhesion of UV curable powder coatings on polypropylene substrates
Authors: Castell P. , Wouters M. , Fischer H. , de With G.
Published: August 2007

Different benzophenone type photoinitiators were photografted onto polypropylene. The polymer surfaces were analysed by means of contact angle measurements, UV spectroscopy, and FTIR‐ATR. The modified samples showed a better wettability and higher surface energies increasing from 26 mN/m for pure polypropylene up to 36 mN/m for the modified samples. Different acrylates were grafted efficiently onto the modified polymer surfaces. FTIR‐ATR and contact angle measurements confirmed the presence of the grafted chains. The surface energy of the grafted surfaces samples increased then up to 70 mN/m depending of the type of acrylate used. Finally UV curable powder coatings were applied onto the modified polypropylene substrates and the adhesion was improved. Adhesion was measured by pull‐off tests and values of ∼ 0.20 MPa were obtained for pure polypropylene while the modified polypropylene reach pull‐off values of 2.00 MPa. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Mining Web data for Chinese segmentation
Authors: Wang Fu Lee , Yang Christopher C.
Published: August 2007

Modern information retrieval systems use keywords within documents as indexing terms for search of relevant documents. As Chinese is an ideographic character‐based language, the words in the texts are not delimited by white spaces. Indexing of Chinese documents is impossible without a proper segmentation algorithm. Many Chinese segmentation algorithms have been proposed in the past. Traditional segmentation algorithms cannot operate without a large dictionary or a large corpus of training data. Nowadays, the Web has become the largest corpus that is ideal for Chinese segmentation. Although most search engines have problems in segmenting texts into proper words, they maintain huge databases of documents and frequencies of character sequences in the documents. Their databases are important potential resources for segmentation. In this paper, we propose a segmentation algorithm by mining Web data with the help of search engines. On the other hand, the Romanized pinyin of Chinese language indicates boundaries of words in the text. Our algorithm is the first to utilize the Romanized pinyin to segmentation. It is the first unified segmentation algorithm for the Chinese language from different geographical areas, and it is also domain independent because of the nature of the Web. Experiments have been conducted on the datasets of a recent Chinese segmentation competition. The results show that our algorithm outperforms the traditional algorithms in terms of precision and recall. Moreover, our algorithm can effectively deal with the problems of segmentation ambiguity, new word (unknown word) detection, and stop words.
Diasporic information environments: Reframing immigrant‐focused information research
Authors: Srinivasan Ramesh , Pyati Ajit
Published: August 2007

Studies of immigrant information behavior need to be situated within the dynamic contexts of globalization and diaspora. Most immigrant‐focused information‐science research has focused on distinctly local, place‐based scenarios, while diasporic research on information behavior, in contrast, focuses mainly on issues of transnational identity online. This article suggests a methodology that mediates between these two poles, by recognizing the place‐based, lived realities of immigrant communities while also acknowledging the existence of complex, globalized diasporic information environments. We refer to this methodology as the Diasporic Information Environment Model (DIEM), and argue that local information‐science research can be extended to address the globalized experiences of immigrant communities
The context of embryonic development and its ethical relevance
Authors: Camporesi Silvia
Published: August 2007

Research on human stem cells and embryos creates ethical issues. Here I discuss ten frequently used arguments against research and point out their weaknesses. These arguments include the possessed potentiality of the embryo per se and, in contrast to other cell systems, the “slippery slope” argument, the right of disposal of parents, totipotency versus pluripotency, the burden of proof for research, natural versus artificial, and three arguments based on the precaution principle (the open biological questions, uncertainty regarding clinically applicable therapies, and the problem solving rule). I finally suggest a different answer to the ethical questions concerning research on human embryos and embryonic stem cells, which takes into consideration their biological context.
Talking biotech with the public
Authors: Brauerhoch Frank‐Olaf , Ewen Christoph , Sinemus Kristina
Published: August 2007

In the estimation of risks involved in complex technical applications, such as, for example, gene technology or nanotechnology, the problem of communication between science and the wider society becomes evident. The path towards transparent, authentic and credible communication must be built upon the reconciliation of the risk perceptions of the scientist – and of his or her institution – with the corresponding ideas of risk and communication existing in the society. Additionally, to accomplish goal‐oriented discourse within the public sphere and to realistically assess his or her effective options when addressing this public, the scientist is faced with the necessity of reflecting upon his or her own determining assumptions on the condition, constitution and functionalities of this “public”. Combined with the use of modern tools – and supported with supplementary coaching and organizational consultation – such a foundation allows the establishment of targeted communication with specific groups.
Portals, blogs and co.: the role of the Internet as a medium of science communication
Authors: Minol Klaus , Spelsberg Gerd , Schulte Elisabeth , Morris Nicholas
Published: August 2007

While the use of the Internet for the exchange of scientific data was characterised by exclusivity during its pioneer era, the active employment of the medium today, by a broad social spectrum of users in the exchange of information, for dialogue and in the accumulation of knowledge, displays an almost unbounded inclusion. Blo and online encyclopaedias based on the 'Wikipedia' model have contributed to the formation of a marketplace in which the free expression of opinions and the relaying of information occur. Counted among the ideas which have been popularised in the wake of this phenomenon, “lay journalism” and the “wisdom of the masses” are seen to be integral to the new 'web 2.0'. Consequently, the ever‐increasing information disseminated in the web has been diluted in quality and authenticity, resulting in the presentation of new challenges to online science journalism. In reference to the public debate surrounding green gene technology, the communications platform bioSicherheit.de, which receives more than one million visitors per year, will be examined as an example of an agent that retrieves and mobilises information on biological safety research and that successfully has established itself as an intermediary between the scientific community and the broader public.
Production of plant sesquiterpenes in Saccharomyces cerevisiae: Effect of ERG9 repression on sesquiterpene biosynthesis
Authors: Asadollahi Mohammad A. , Maury Jérôme , Møller Kasper , Nielsen Kristian Fog , Schalk Michel , Clark Anthony , Nielsen Jens
Published: August 2007

The yeast Saccharomyces cerevisiae was chosen as a microbial host for heterologous biosynthesis of three different plant sesquiterpenes, namely valencene, cubebol, and patchoulol. The volatility and low solubility of the sesquiterpenes were major practical problems for quantification of the excreted sesquiterpenes. In situ separation of sesquiterpenes in a two‐phase fermentation using dodecane as the secondary phase was therefore performed in order to enable quantitative evaluation of different strains. In order to enhance the availability of the precursor for synthesis of sesquiterpenes, farnesyl diphosphate (FPP), the ERG9 gene which is responsible for conversion of FPP to squalene was downregulated by replacing the native ERG9 promoter with the regulatable MET3 promoter combined with addition of 2 mM methionine to the medium. This strategy led to a reduced ergosterol content of the cells and accumulation of FPP derived compounds like target sesquiterpenes and farnesol. Adjustment of the methionine level during fermentations prevented relieving MET3 promoter repression and resulted in further improved sesquiterpene production. Thus, the final titer of patchoulol and farnesol in the ERG9 downregulated strain reached 16.9 and 20.2 mg/L, respectively. The results obtained in this study revealed the great potential of yeast as a cell factory for production of sesquiterpenes. Biotechnol. Bioeng. 2008;99: 666–677. © 2007 Wiley Periodicals, Inc.
Bismuth dimercaptopropanol (BisBAL) inhibits the expression of extracellular polysaccharides and proteins by Brevundimonas diminuta: Implications for membrane microfiltration
Authors: Badireddy Appala Raju , Chellam Shankararaman , Yanina Svetlana , Gassman Paul , Rosso Kevin M.
Published: August 2007

A 2:1 molar ratio preparation of bismuth with a lipophilic dithiol (3‐dimercapto‐1‐propanol, BAL) significantly reduced extracellular polymeric substances (EPS) expression by Brevundimonas diminuta in suspended cultures at levels just below the minimum inhibitory concentration (MIC). Total polysaccharides and proteins secreted by B. diminuta decreased by approximately 95% over a 5‐day period when exposed to the bismuth‐BAL chelate (BisBAL) at near MIC (12 µM). Fourier‐transform infrared spectroscopy (FTIR) suggested that a possible mechanism of biofilm disruption by BisBAL is the inhibition of carbohydrate O‐acetylation. FTIR also revealed extensive homology between EPS samples with and without BisBAL treatment, with proteins, polysaccharides, and peptides varying predominantly only in the amount expressed. EPS secretion decreased following BisBAL treatment as verified by atomic force microscopy and scanning electron microscopy. Without BisBAL treatment, a slime‐like EPS matrix secreted by B. diminuta resulted in biofouling and inefficient hydrodynamic backwashing of microfiltration membranes. Bioeng. 2008;99: 634–643. © 2007 Wiley Periodicals, Inc.
Lentiviruses inefficiently incorporate human parainfluenza type 3 envelope proteins
Authors: Jung Cindy , Le Doux Joseph M.
Published: August 2007

We have previously shown that the envelope glycoproteins of human parainfluenza type 3 (HPIV3), F and HN, are able to pseudotype lentiviruses, but the titers of these viruses are too low for use in clinical gene transfer. In this study we investigated the cause of these low titers. We compared the mRNA and protein expression levels of HN and F in transfected cells and in cells infected with wild‐type HPIV3. Transfected cells contained similar levels of HN and F cytosolic mRNA, but fewer cell‐surface HN and F proteins (3.8‐ and 1.3‐fold less, respectively), than cells infected with wild‐type HPIV3. To increase expression of HN in transfected cells, we codon‐optimized HN and used it to transfect lentivirus producer cells. Cell surface expression of HN, as well as the amount of HN incorporated into virus particles, increased two‐ to threefold. Virus titers increased 1.2‐ to 6.4‐fold, and the transduction efficiency of polarized MDCK cells via their apical surfaces increased 1.4‐fold. Interestingly, even though codon optimization improved the expression levels of HN and virus titers, we found that HPIV3 pseudotyped viruses contained about 14‐fold fewer envelope proteins than lentiviruses pseudotyped with the amphotropic envelope protein. Taken together, our findings suggest that titers are low, not because virus producer cells express levels of HPIV3 envelope proteins that are too low, but because too few of these proteins are incorporated by the lentiviruses for them to be able to efficiently transduce cells. Biotechnol. Bioeng. 2008; 99; 1016–1027. © 2007 Wiley Periodicals, Inc.
Production of cell‐enclosing hollow‐core agarose microcapsules via jetting in water‐immiscible liquid paraffin and formation of embryoid body‐like spherical tissues from mouse ES cells enclosed within these microcapsules
Authors: Sakai Shinji , Hashimoto Ichiro , Kawakami Koei
Published: August 2007

We developed agarose microcapsules with a single hollow core templated by alginate microparticles using a jet‐technique. We extruded an agarose aqueous solution containing suspended alginate microparticles into a coflowing stream of liquid paraffin and controlled the diameter of the agarose microparticles by changing the flow rate of the liquid paraffin. Subsequent degradation of the inner alginate microparticles using alginate lyase resulted in the hollow‐core structure. We successfully obtained agarose microcapsules with 20–50 µm of agarose gel layer thickness and hollow cores ranging in diameter from ca. 50 to 450 µm. Using alginate microparticles of ca. 150 µm in diameter and enclosing feline kidney cells, we were able to create cell‐enclosing agarose microcapsules with a hollow core of ca. 150 µm in diameter. The cells in these microcapsules grew much faster than those in alginate microparticles. In addition, we enclosed mouse embryonic stem cells in agarose microcapsules. The embryonic stem cells began to self‐aggregate in the core just after encapsulation, and subsequently grew and formed embryoid body‐like spherical tissues in the hollow core of the microcapsules. These results show that our novel microcapsule production technique and the resultant microcapsules have potential for tissue engineering, cell therapy and biopharmaceutical applications. Biotechnol. Bioeng. 2008;99: 235–243. © 2007 Wiley Periodicals, Inc.
Non‐native protein aggregation kinetics
Authors: Roberts Christopher J.
Published: August 2007

Experimental kinetics of non‐native protein aggregation are of practical importance in that they help dictate viable processing, formulation, and storage conditions for biotechnology products, and appear to play a role in determining the onset of a number of diseases. Fundamentally, aggregation kinetics provide insights into the identity of key intermediates in the process, and quantitative tests of available models of aggregation. Although aggregation kinetics often display seemingly disparate behaviors across different proteins and sample conditions, this review illustrates how many of these can be understood within a general framework that treats aggregation as a multi‐stage process, and how most available kinetic models of aggregation can be grouped hierarchically in terms of which stage(s) they include. This provides an aid for workers seeking a mechanistic interpretation of in vitro aggregation kinetics, for discriminating among competing models, and in designing experiments to assess in vitro protein stability. Limitations and the utility of purely kinetic approaches to studying aggregation, clarifications of common misperceptions regarding experimental aggregation kinetics, and some outstanding challenges in the field are briefly discussed. Biotechnol. Bioeng. 2007;98: 927–938. © 2007 Wiley Periodicals, Inc.
Clinical prognostic scoring system to aid decision-making in gastro-oesophageal cancer
Authors: Deans D A C , Wigmore S J , de Beaux A C , Paterson-Brown S , Garden O J , Fearon K C H
Published: August 2007

Background

Accurate prediction of prognosis in gastro-oesophageal cancer remains challenging. The aim of this study was to develop a robust model for outcome prediction.

Methods

The study included 220 patients with gastric or oesophageal cancer newly diagnosed over a 2-year period. Patients were staged and underwent treatment following discussion at a multidisciplinary team (MDT) meeting. Clinical and investigative variables were collected, including performance and nutritional status, and serum C-reactive protein (CRP) level. Primary endpoints were death within 12 and 24 months.

Results

Overall median survival was 13 months. Advanced clinical stage (P < 0·001), reduced performance score (P < 0·001), weight loss exceeding 2·75 per cent per month (P = 0·026) and serum CRP concentration above 5 mg/l (P = 0·031) were identified as independent prognostic indicators in multivariable analysis. A prognostic score was constructed using these four variables to estimate a probability of death. Applying the model gave an area under the receiver–operator characteristic curve of 0·84 and 0·85 for prediction of death at 12 and 24 months respectively (both P < 0·001).

Conclusion

This model accurately estimated the probability of death within 12 and 24 months. This may aid the MDT decision-making process.
Effects of thyroxine replacement on lipid profile and endothelial function after thyroidectomy
Authors: Erbil Y , Özbey N , Giriş M , Salmaslıoğlu A , Özarmağan S , Tezelman S
Published: August 2007

Background

Hypothyroidism is a risk factor for atherosclerotic cardiovascular disease. This study investigated the effects of l-thyroxine replacement therapy on lipid profile and endothelial function after thyroidectomy in patients with overt transient non-autoimmune hypothyroidism.

Methods

Twenty-two patients with non-toxic multinodular goitre treated by total or near-total thyroidectomy and 22 healthy individuals matched for age, sex and body mass index were studied. Lipid profile and endothelial function were determined in each patient at the euthyroid phase before thyroidectomy (stage 1), the hypothyroid phase 3 weeks after surgery (stage 2), and the euthyroid phase 3 months (stage 3) and 6 months (stage 4) after the start of thyroxine treatment.

Results

The lipid profile and endothelial function deteriorated between stage 1 and stages 2 and 3. Findings at stage 4 were similar to those at stage 1. There was a positive correlation between serum thyroid-stimulating hormone (TSH) and total cholesterol (rs = 0·588, P < 0·001), and a negative correlation between serum TSH and flow-mediated arterial dilatation (rs = 0·506, P < 0·001). Total cholesterol and TSH were independent determinants of endothelial function.

Conclusion

A 3-week hypothyroid period after thyroidectomy led to a more atherogenic lipid profile and impaired endothelial function that persisted for at least 3 months.
Liquid‐Phase Aerobic Oxidation of Benzyl Alcohol Catalyzed by Pt/ZrO2
Authors: Ilyas M. , Sadiq M.
Published: August 2007

The oxidation of benzyl alcohol by molecular oxygen in the liquid phase and catalyzed by Pt/ZrO2 using n‐heptane as the solvent was studied. Pt/ZrO2 was very active and 100 % selective for benzyl alcohol conversion to benzaldehyde. The catalyst can be separated by filtration and reused. No leaching of Pt or Zr into the solution was observed. Typical batch reactor kinetic data were obtained and fitted to the Langmuir‐Hinshelwood, Eley‐Rideal and Mars‐van Krevelen models of heterogeneously catalyzed reactions. The Langmuir‐Hinshelwood model was found to give a better fit. The rate‐determining step was proposed to involve direct interaction of an adsorbed oxidizing species with the adsorbed reactant or an intermediate product of the reactant. H2O2 was also proposed to be an intermediate product. n‐Heptane was found to be an appropriate solvent in this reaction system.
Bedeutung der Dynamik der Rektifikation und deren Einbindung in die Ingenieurausbildung
Authors: Landwehr B. , Trägner U. K.
Published: August 2007

Stetige Rektifikationsprozesse werden meist nur auf der Basis stationärer Modelle ausgelegt. Zur Verbesserung der Regelung, einer Optimierung des Anfahrens oder für das Verständnis des Betriebsverhaltens gekoppelter Anlagenstrukturen ist jedoch die Untersuchung des dynamischen Verhaltens meist unverzichtbar. Damit kann der Energieeinsatz reduziert und die Produktqualität sowie die Betriebsstabilität gesichert werden. Der folgende Artikel stellt die Modelle der dynamischen Kolonnensimulation, deren Anwendungsmöglichkeiten und eine Einbindung dieses wichtigen Themas in eine praxisnahe Lehre dar.
Novel structural and functional findings of the ehFLN protein from Entamoeba histolytica
Authors: Díaz‐Valencia Juan Daniel , Almaraz‐Barrera Ma de Jesús , Jay David , Hernández‐Cuevas Nora Adriana , García Elizabeth , González‐De la Rosa Claudia H , Arias‐Romero Luis Enrique , Hernandez‐Rivas Rosaura , Rojo‐Domínguez Arturo , Guillén Nancy , Vargas Miguel
Published: August 2007

The ehFLN protein (previously known as EhABP‐120) is the first filamin to be identified in the parasitic protozoan Entamoeba histolytica. Filamins are a family of cross‐linking actin‐binding proteins that organize filamentous actin in networks and stress fibers. It has been reported that filamins of different organisms directly interact with more than 30 cellular proteins and some PPIs. The biochemical consequences of such interactions may have either positive or negative effects on the cross‐linking function. Besides, filamins form a link between cytoskeleton and plasma membrane. In this work, the ehFLN protein was biochemically characterized; amoebae filamin was found to associate with both PA and PI(3)P in vitro, new lipid targets for a member of the filamins. By molecular modeling analysis and protein‐lipid overlay assays, K‐609, 709, and 710 were determined to be essential for the PA‐ehFLN1 complex stability. Also, the integrity of the 4th repeat of ehFLN is essential to keep interaction with the PI(3)P. Transfected trophozoites that overexpressed the d100, d50NH2, and d50COOH regions of ehFLN1 displayed both increased motility and chemotactic response to TYI‐S‐33 media. Together, these results suggest that short regions of ehFLN are involved in signaling events that, in cooperation with phosphatidic acid, EhPLD2 and EhPI3K, could promote cell motility. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
G protein βγ subunits interact with αβ‐ and γ‐tubulin and play a role in microtubule assembly in PC12 cells
Authors: Montoya Valentina , Gutierrez Christina , Najera Omar , Leony Denisse , Varela‐Ramirez Armando , Popova Juliana , Rasenick Mark M. , Das Siddhartha , Roychowdhury Sukla
Published: August 2007

The βγ subunit of G proteins (Gβγ) is known to transfer signals from cell surface receptors to intracellular effector molecules. Recent results suggest that Gβγ also interacts with microtubules and is involved in the regulation of the mitotic spindle. In the current study, the anti‐microtubular drug nocodazole was employed to investigate the mechanism by which Gβγ interacts with tubulin and its possible implications in microtubule assembly in cultured PC12 cells. Nocodazole‐induced depolymerization of microtubules drastically inhibited the interaction between Gβγ and tubulin. Gβγ was preferentially bound to microtubules and treatment with nocodazole suggested that the dissociation of Gβγ from microtubules is an early step in the depolymerization process. When microtubules were allowed to recover after removal of nocodazole, the tubulin‐Gβγ interaction was restored. Unlike Gβγ, however, the interaction between tubulin and the α subunit of the Gs protein (Gsα) was not inhibited by nocodazole, indicating that the inhibition of tubulin‐Gβγ interactions during microtubule depolymerization is selective. We found that Gβγ also interacts with γ‐tubulin, colocalizes with γ‐tubulin in centrosomes, and co‐sediments in centrosomal fractions. The interaction between Gβγ and γ‐tubulin was unaffected by nocodazole, suggesting that the Gβγ‐γ‐tubulin interaction is not dependent on assembled microtubules. Taken together, our results suggest that Gβγ may play an important and definitive role in microtubule assembly and/or stability. We propose that βγ‐microtubule interaction is an important step for G protein‐mediated cell activation. These results may also provide new insights into the mechanism of action of anti‐microtubule drugs. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
Dehydrogenation Reaction for NaOH System: A First‐Principles Study
Authors: Zhang Xin‐Bo , Shi Si‐Qi , Ke Xue‐Zhi , Han Song , Shioyama Hiroshi , Kuriyama Nobuhiro , Kobayashi Tetsuhiko , Xu Qiang
Published: August 2007

The crystal structures, electronic, dielectric, and vibrational properties of NaH, Na2O and NaOH are systematically investigated by first‐principles calculations and the quasiharmonic approximation. The phonon dispersion relations and the phonon density of states of the phases and their thermodynamic functions including the heat capacity, the vibrational enthalpy, and the vibrational entropy are calculated using a direct force‐constant method. Based on these results, the dehydrogenation reaction, NaH+NaOH→H2+Na2O, is predicted to take place at 528 K, which is in agreement with the experimental observed value.
Protein kinase C δ is a critical regulator of CD1d‐mediated antigen presentation
Authors: Brutkiewicz Randy R. , Willard Claire A. , Gillett‐Heacock Kristin K. , Pawlak M. Robert , Bailey Jennifer C. , Khan Masood A. , Nagala Manjula , Du Wenjun , Gervay‐Hague Jacquelyn , Renukaradhya Gourapura J.
Published: August 2007

We have recently demonstrated that the p38 and ERK1/2 MAP kinases play reciprocal roles in the control of CD1d‐mediated antigen presentation. Although the use of specific inhibitors for these pathways clearly had an effect, the effects were not complete, leading to speculations that additional pathways were involved. Here, we show that inhibiting protein kinase C δ (PKCδ) substantially impairs antigen presentation by murine CD1d1 to NKT cells. This effect was accompanied by marked changes in the intracellular localization of CD1d. Expression of a dominant‐negative mutant of PKCδ in CD1d+ cells resulted in nearly undetectable endogenous antigen presentation, substantially impaired CD1d recycling, a decrease in MAPK activation, and a decrease in the ability to present low (but not high) concentrations of α‐galactosylceramide at the cell surface. These data strongly suggest that PKCδ is a critical regulator of CD1d‐mediated antigen presentation and is involved in multiple steps of the process.
Identification and isolation of murine antigen‐reactive T cells according to CD154 expression
Authors: Kirchhoff Dennis , Frentsch Marco , Leclerk Patrick , Bumann Dirk , Rausch Sebastian , Hartmann Susanne , Thiel Andreas , Scheffold Alexander
Published: August 2007

T helper (Th) cells are central regulators of adaptive immune responses. However, the detection of the small number of Th cells specific for a particular antigen or pathogen is still a major challenge. CD154 was recently introduced as a marker for antigen‐specific Th cells. To date, this technology was not applicable for mice – arguably the most important immunological model system. CD154 is difficult to detect due to its rapid removal from the cell surface upon binding to CD40 during antigen‐specific activation by APC. We present an efficient strategy to block the degradation of murine CD154 by combined use of antibodies against CD40 and CD154. This strategy makes CD154 easily accessible for surface staining, which allows isolation and expansion of rare antigen specific T cells. Importantly, CD154 identified all specific T cells in strongly Th1‐ or Th2‐polarized immune responses against pathogens like Salmonella typhimurium and Heligmosomoides polygyrus, independent of their potential to produce cytokines. We demonstrate that CD154 can in fact be used as a reliable marker for antigen‐specific CD4 T cells in mice, offering a unique option to analyze, isolate and rapidly expand the entire pool of Th‐cells generated during a physiological T cell response in vivo.
Bim regulates BCR‐induced entry of B cells into the cell cycle
Authors: Craxton Andrew , Draves Kevin E. , Clark Edward A.
Published: August 2007

BH3‐only Bcl‐2 homologs are key regulators of the intrinsic apoptotic pathway. In particular, Bim, is critical for mediating apoptosis of hematopoietic cells including B cells. While studies using Bcl‐2 Tg mice have defined an important role for Bcl‐2 in cell cycle control, the role of BH3‐only proteins is less clear. Using Bim KO mice, we show that Bim is required for B cells to enter the cell cycle normally. Bim KO B cells had reduced cell division compared to WT B cells in response to BCR, TLR3 or TLR4 signaling, whereas Bim deficiency did not affect TLR9‐induced B cell division. Cell cycle progression in BCR‐ and LPS‐stimulated Bim KO B cells was blocked at the G0–G1 stage. BCR‐induced p130 degradation and pRb hyperphosphorylation on Ser807/811, which are critical for G1 entry, were reduced in Bim KO compared to WT B cells. Likewise, BCR‐induced p27Kip1 degradation was decreased in Bim KO compared to WT B cells. These defects in BCR‐induced cell cycle entry correlated with a proximal defect in BCR‐mediated intracellular calcium release in Bim KO B cells. Our results suggest that the balance of pro‐ and anti‐apoptotic Bcl‐2 family proteins is critical for controlling both cell cycle progression and apoptosis in B cells.
Synthetic Studies Towards Bridgehead Diprenyl‐Substituted Bicyclo[3.3.1]nonane‐2,9‐diones as Models for Polyprenylated Acylphloroglucinol Construction
Authors: Pouplin Thomas , Tolon Blanca , Nuhant Philippe , Delpech Bernard , Marazano Christian
Published: August 2007

The synthesis of bridgehead diprenylated bicyclo[3.3.1]nonane‐2,9‐dione, based on a reductive rearrangement of an enol lactone, is presented. The same target could be reached by a one‐step sequence involving Michael addition of 2,6‐diprenylcyclohexanone onto acrolein and intramolecular aldol reaction. The first method could be extended to the formation of a compound with gem‐dimethyl substituents adjacent to the bridgehead position, but the construction of a suitably substituted enol lactone, with a view to polyprenylated acylphloroglucinol elaboration, could not be achieved. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis, X‐ray Crystal Structures and Solid‐State Fluorescence Properties of 3‐Dibutylamino‐6‐alkoxy‐6‐phenylnaphtho[2,3‐b]benzofuran‐11(6H)‐one Derivatives
Authors: Ooyama Yousuke , Mamura Toshiki , Yoshida Katsuhira
Published: August 2007

Novel heterocyclic fluorophores – 6‐alkoxy‐3‐dibutylamino‐6‐phenylnaphtho[2,3‐b]benzofuran‐11(6H)‐ones 2a–2g with different chain lengths in alkoxy substituents non‐conjugatedly linked to the chromophore skeleton – have been derived from the quinol‐type compound 1, and their photophysical properties have been investigated in solution and in the solid state. In solution, the fluorophores 1 and 2a–2g exhibit similar fluorescence properties. In the solid state, however, the fluorophores 2a–2g exhibit stronger fluorescence properties than the quinol 1. Furthermore, the fluorescence quantum yields (Φ) of 2 in the solid state are higher than those of 2 in solution, and considerable differences in the solid‐state fluorescence were observed among the alkoxy derivatives 2a–2g. To elucidate the dramatic effect of the alkoxy substituents we performed semiempirical molecular orbital calculations (AM1 and INDO/S) and X‐ray crystallographic analysis. On the basis of the results of the calculations and the X‐ray crystal structures, the relationships between the solid‐state photophysical properties and the chemical and crystal structures of 1 and 2a–2g are discussed. It was confirmed that the introduction of long alkoxy chains such as butoxy and pentoxy groups in non‐conjugated linkage to the chromophore can efficiently prevent short π–π contacts between the fluorophores in molecular aggregation states and thus cause dramatic solid‐state fluorescence enhancements.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The First Example of an Azaphenalene Profluorescent Nitroxide
Authors: Blinco James P. , McMurtrie John C. , Bottle Steven E.
Published: August 2007

The synthesis of the first example of an azaphenalene‐based fused aromatic nitroxide TMAO, [1,1,3,3‐tetramethyl‐2,3‐dihydro‐2‐azaphenalen‐2‐yloxyl, (5)], is described. This novel nitroxide possesses some of the structural rigidity of the isoindoline class of nitroxides, as well as some properties akin to TEMPO nitroxides. Additionally, the integral aromatic ring imparts fluorescence that is switched on by radical scavenging reactions of the nitroxide, which makes it a sensitive probe for polymer degradation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Multiple frequency dielectrophoresis
Authors: Urdaneta Mario , Smela Elisabeth
Published: August 2007

A novel method of modeling multiple frequency dielectrophoresis (MFDEP) is introduced based on the concept of an effective Clausius–Mossotti factor, CMeff, for a particle that is exposed to electrical fields of different frequencies, coming either from one or multiple pairs of electrodes. This analysis clearly illustrates how adding frequencies adds control parameters, up to two additional parameters per frequency. As a result, MFDEP can be used for a wide variety of applications, including separating particles with very similar Clausius–Mossotti spectra, trapping multiple groups of cells simultaneously, and cancelling unwanted dielectrophoretic traps. Illustrating the modeling approach, we determine the CMeffs for live and dead yeast cells, and then predict their equilibrium distribution on a three‐electrode configuration, with two electrodes at different frequencies and the third electrode at ground. This prediction is validated experimentally, using MFDEP to selectively attract live cells to one location and dead cells to another, trapping both. These results demonstrate that the use of multiple frequencies for the manipulation of particles can enhance the performance of dielectrophoretic devices, not only for sorting, but also for such applications as patterning cells in close proximity for the formation of cell consortia.
EOF using the Ritz method: Application to superelliptic microchannels
Authors: Wang Chang Yi , Chang Chien C.
Published: August 2007

An efficient Ritz method is developed from the variational principle to solve the Poisson–Boltzmann equation under the Debye–Hückel approximation for studying the EOF in microchannels. The method is applied to the family of superelliptic cross sections which includes the elliptic channel and the rectangular channel as limiting cases. Several accurate tables presented are useful for design of electroosmotic channels, especially rectangular channels with rounded corners. It is shown how the flow rate Q is a sophisticated consequence of the nondimensional electrokinetic width K, the aspect ratio b as well as the superelliptic exponent n.
SNPlexing the human Y‐chromosome: A single‐assay system for major haplogroup screening
Authors: Berniell‐Lee Gemma , Sandoval Karla , Mendizabal Isabel , Bosch Elena , Comas David
Published: August 2007

SNPs are one of the main sources of DNA variation among humans. Their unique properties make them useful polymorphic markers for a wide range of fields, such as medicine, forensics, and population genetics. Although several high‐throughput techniques have been (and are being) developed for the vast typing of SNPs in the medical context, population genetic studies involve the typing of few and select SNPs for targeted research. This results in SNPs having to be typed in multiple reactions, consuming large amounts of time and of DNA. In order to improve the current situation in the area of human Y‐chromosome diversity studies, we decided to employ a system based on a multiplex oligo ligation assay/PCR (OLA/PCR) followed by CE to create a Y multiplex capable of distinguishing, in a single reaction, all the major haplogroups and as many subhaplogroups on the Y‐chromosome phylogeny as possible. Our efforts resulted in the creation of a robust and accurate 35plex (35 SNPs in a single reaction) that when tested on 165 human DNA samples from different geographic areas, proved capable of assigning samples to their corresponding haplogroup.
Modelling dynamic water redistribution patterns in arid catchments in the Negev Desert of Israel
Authors: Buis E. , Veldkamp A.
Published: August 2007

In arid climate regions, redistribution of runoff water is highly relevant for vegetation development. The process of water redistribution at catchment scale is studied with the landscape process model LAPSUS, mainly used for erosion and sedimentation modelling. LAPSUS, formerly applied in Mediterranean climates, is modified to deal with the arid climate of the Negev Desert of Israel. Daily event based model runs were used instead of yearly model runs, and the infiltration module was modified to better represent the spatial diversity in water availability in an arid catchment. The model is calibrated for two small catchments in the Negev Desert of Israel, Halluqim and Avdat. First, a sensitivity analysis of the modified LAPSUS is performed. Pore volume appears to have an especially strong influence on the modelling results. Second, the capability of LAPSUS to deal with varying surface characteristics is assessed by comparing the water redistribution patterns in the two catchments with field data. Simulation results demonstrate that the catchments respond very differently to precipitation. Water redistribution is larger in the dominantly bedrock covered Halluqim compared to the dominantly loess covered catchment of Avdat. Consequently, Halluqim has more positions with water accumulation than Avdat, and can sustain a larger vegetation cover, including Mediterranean species. Finally, the modelled infiltration patterns are compared with vegetation cover in the catchments. The results indicate that there is a broad agreement between infiltration and vegetation patterns, but locally there is a strong mismatch, indicating that some of the involved processes are still missing from the model. Copyright © 2007 John Wiley & Sons, Ltd.
How do streamflow generation mechanisms affect watershed hypsometry?
Authors: Huang Xiangjiang , Niemann Jeffrey D.
Published: August 2007

Several studies have shown that the dominant streamflow generation mechanism in a river basin can leave distinct geomorphological signatures in basin topography. In particular, it has been suggested previously that basins generated by groundwater discharge tend to have a larger hypsometric integral than surface runoff basins because fluvial erosion is more focused in the valleys where groundwater discharge tends to occur. In this analysis, we aim to clarify this relationship by developing an alternative method to quantify the effects of streamflow generation mechanisms on basin hypsometry and by using a numerical model that can generate streamflow by different processes to evaluate the sensitivity of the results to the hydrological and geomorphological properties of the basin. The model results suggest that the hypsometric characteristics that are usually associated with groundwater discharge basins, such as a larger hypsometric integral, occur primarily when drainage networks are still advancing in the watershed. During later stages of development, an additional factor such as lithological controls or a distinct geomorphological process would be needed to preserve these features. The model results also show that the hypsometric effects are stronger when the parameters of the fluvial erosion process promote the influence of small discharge rates. Copyright © 2007 John Wiley & Sons, Ltd.
Determination of axial displacement extent based on transformer winding transfer function estimation using vector‐fitting method
Authors: Karimifard P. , Gharehpetian G. B. , Tenbohlen S.
Published: August 2007

This paper suggests a new method to determine the extent of the axial winding displacement which is based on the transfer function (TF) estimation using the vector‐fitting (VF) method. The identification of the TF in normal and displaced conditions can be achieved properly using VF methods. To study the different degrees of mechanical displacements, a verified detailed model of transformer in the frequency range of kHz < f <MHz has been used. A new index for the determination of the displacement extent has been presented, too. Copyright © 2007 John Wiley & Sons, Ltd.
Notch signaling modulates the activation of microglial cells
Authors: Grandbarbe Luc , Michelucci Alessandro , Heurtaux Tony , Hemmer Karin , Morga Eleonora , Heuschling Paul
Published: August 2007

The Notch signaling pathway plays a crucial role in specifying cellular fate in metazoan development by regulating communication between adjacent cells. Correlative studies suggested an involvement of Notch in hematopoietic cell development. Here, we report that the Notch pathway is expressed and active in microglial cells. During inflammatory activation, the transcription of the Notch down‐stream effector Hes1 is downregulated. When Notch1 transcription in microglia is inhibited, an upregulation of the expression of pro‐inflammatory cytokines is observed. Notch stimulation in activated microglia, using a soluble form of its ligand Jagged1, induces a decrease in pro‐inflammatory cytokines secretion and nitric oxide production as well as an increase in phagocytic activity. Notch‐stimulation is accompanied by an increase in the rate of STAT3 phosphorylation and nuclear translocation. Our results show that the Notch pathway plays an important role in the control of inflammatory reactions in the CNS. © 2007 Wiley‐Liss, Inc.
Decreased estradiol release from astrocytes contributes to the neurodegeneration in a mouse model of Niemann‐Pick disease type C
Authors: Chen Gang , Li Hai‐Min , Chen Yi‐Ren , Gu Xiao‐Song , Duan Shumin
Published: August 2007

Niemann‐Pick disease type C (NPC) is a deadly neurodegenerative disease often caused by mutation in a gene called NPC1, which results in the accumulation of unesterified cholesterol and glycosphingolipids in the endosomal–lysosomal system. Most studies on the mechanisms of neurodegeneration in NPC have focused on neurons. However, the possibility also exists that NPC1 affects neuronal functions indirectly by acting on other cells that are intimately interacting with neurons. In this study, using a heterotypic neuron‐glia coculture system, we found that wild‐type neurons cultured on a layer of NPC1−/− astrocytes showed decreased neurite growth compared with those cultured on wild‐type astrocytes. RT‐PCR and immunohistochemical assessments showed significantly lower expression of neurosteroid enzymes and StAR (steroidogenic acute regulatory protein) in NPC1−/− astrocyte cultures than in wild‐type cultures. Furthermore, a reduced level of estradiol was measured from both astrocyte culture medium and whole brains from NPC1−/− mice. Administration of 17β‐estradiol to neonatal NPC1−/− mice significantly delayed the onset of neurological symptoms, increased Purkinje cell survival, and extended the animals' life span. Our findings suggest that astrocyte dysfunction contributes to the neurodegeneration of NPC and estradiol treatment may be useful in ameliorating progression of the disease. © 2007 Wiley‐Liss, Inc.
Myelin‐associated glycoprotein reduces axonal branching and enhances functional recovery after sciatic nerve transection in rats
Authors: Tomita Koichi , Kubo Tateki , Matsuda Ken , Yano Kenji , Tohyama Masaya , Hosokawa Ko
Published: August 2007

The mature peripheral nervous system (PNS) generally shows better regeneration of injured axons as opposed to the central nervous system (CNS). However, complete functional recovery is rarely achieved even in the PNS although morphologically good axonal regeneration often occurs. This mainly results from aberrant reinnervation due to extensive branching of cut axons with consequent failure of synchronized movements of the muscles. Myelin‐associated glycoprotein (MAG), a well‐characterized molecule existing both in the CNS and PNS myelin, is considered to be a potent inhibitor of axonal regeneration especially in the CNS. In the present study, we investigated whether MAG has any effects not only on axonal elongation, but also on axonal branching. We show herein that MAG minimized branching of the peripheral axons both in vitro and in vivo via activation of RhoA. Furthermore, after sciatic nerve transection in rats, focal and temporary application of MAG to the lesion dramatically enhanced the functional recovery. Using double retrograde labeling and preoperative/postoperative labeling of spinal neurons, reduced hyperinnervation and improved accuracy of target reinnervation was confirmed, respectively. In conclusion, as MAG significantly improves the quality of axonal regeneration, it can be used as a new therapeutic approach for peripheral nerve repair with possible focal and temporary application. © 2007 Wiley‐Liss, Inc.
Region‐of‐interest‐based analysis with application of cortical thickness variation of left planum temporale in schizophrenia and psychotic bipolar disorder
Authors: Qiu Anqi , Vaillant Marc , Barta Patrick , Ratnanather J.Tilak , Miller Michael I.
Published: August 2007

In neuroimaging studies, spatial normalization and multivariate testing are central problems in characterizing group variation of functions (e.g., cortical thickness, curvature, functional response) in an atlas coordinate system across clinical populations. We present a region‐of‐interest (ROI)‐based analysis framework for detecting such a group variation. This framework includes two main techniques: ROI‐based registration via large deformation diffeomorphic metric surface mapping and a multivariate testing using a Gaussian random field (GRF) model on the cortical surface constructed by the eigenfunctions of the Laplace–Beltramioperator. We compared our GRF statistical model with a pointwise hypothesis testing approach, whose P‐value is corrected using false discovery rate or random field theory at several smoothness scales. As an illustration, we applied this framework to a clinical study of the cortical thickness of the left planum temporale (PT) in subjects with psychotic bipolar disorder, schizophrenia, and healthy comparison controls. Our results show that the anterior portion of the left PT is thinner in the psychotic bipolar and schizophrenic groups than in the healthy control group, and the posterior portion of the left PT shows the reversal finding. Moreover, there may be a greater thickness variation in the left PT in psychotic bipolar patients when compared with that in schizophrenic patients. Hum Brain Mapp, 2008. © 2007 Wiley‐Liss, Inc.