bluuebunny/crossref_metadata_2025 huggingface dataset:
Platelet derived growth factor induced tenascin‐C transcription is phosphoinositide 3‐kinase/Akt‐dependent and mediated by Ets family transcription factors
Authors: Jinnin Masatoshi , Ihn Hironobu , Asano Yoshihide , Yamane Kenichi , Trojanowska Maria , Tamaki Kunihiko
Published: October 2005

Previous studies have identified several cytokines as inducers of tenascin‐C (TN‐C) expression in various tissue culture systems. However, the signaling pathways of the regulation of TN‐C expression are almost unknown. In this study, we clarified the molecular mechanism(s) underlying the regulation of the TN‐C gene by platelet derived growth factor (PDGF) in cultured human dermal fibroblasts. PDGF induced the expression of TN‐C protein as well as mRNA in a dose‐dependent manner. Actinomycin D, an RNA synthesis inhibitor, significantly blocked the PDGF‐mediated upregulation of TN‐C mRNA expression, whereas cycloheximide, a protein synthesis inhibitor, did not. The PDGF‐mediated induction of TN‐C expression was inhibited by the treatment of fibroblasts with a selective phosphoinositide 3‐kinase (PI3K) inhibitor, wortmannin, or LY294002. These results suggest that PDGF induced the expression of TN‐C at a transcriptional level via phosphoinositide3‐kinase/Akt signaling pathways. We performed serial 5′ deletions and a transient transfection analysis to define the region in the TN‐C promoter mediating the responsiveness to PDGF. Overexpression of Sp1, Ets1, or Ets2 activated the TN‐C promoter and superinduced TN‐C promoter activity stimulated by PDGF, whereas overexpression of Fli1 inhibited the effects of PDGF on TN‐C expression. Mutation of the Sp1/3 binding sites or Ets binding sites in the TN‐C promoter region responsible to PDGF abrogated the PDGF‐inducible promoter activity. Immunoprecipitation analysis revealed that Sp1, Ets1, and Ets2 form a transcriptionally active complex. On the other hand, the interaction of Fli1 with Sp1 decreased after PDGF treatment. These results suggest that the upregulation of TN‐C expression by PDGF involves Ets family transcription factors, co‐operating with Sp1. J.Cell.Physiol. © 2005 Wiley‐Liss, Inc.
The Feeder layer‐mediated extended lifetime of cultured human skin keratinocytes is associated with altered levels of the transcription factors Sp1 and Sp3
Authors: Masson‐Gadais Bénédicte , Fugère Claudia , Paquet Claudie , Leclerc Steeve , Lefort Natalie R. , Germain Lucie , Guérin Sylvain L.
Published: October 2005

Primary cultured epithelial cells that are used for basic research are often cultivated on plastic whereas those used for clinical purposes are usually cultured in the presence of a feeder layer. Here, we examined the influence of a feeder layer on the expression, affinity and DNA binding ability of the transcription factors, Sp1 and Sp3 in primary cultures of human skin keratinocytes. Co‐culturing both newborn and adult skin keratinocytes with lethally irradiated 3T3 cells as a feeder layer contributed to maintain the cell's morphological and growth characteristics and delayed terminal differentiation in vitro. 3T3 also stabilized the DNA binding properties of Sp1 without altering its transcription. Stimulation of Sp1/Sp3 expression appears to be mediated through cell–cell interactions and by factors secreted by 3T3. Thus, we propose that the feeder layer delay terminal differentiation of primary cultured skin keratinocytes by preventing extinction of transcription factors, like Sp1 and Sp3, which play pivotal functions in the cell cycle. J.Cell.Physiol. © 2005 Wiley‐Liss, Inc.
CRH functions as a growth factor/cytokine in the skin
Authors: Slominski A. , Zbytek B. , Pisarchik A. , Slominski R.M. , Zmijewski M.A. , Wortsman J.
Published: October 2005

We tested the effect of CRH and related peptides in a large panel of human skin cells for growth factor/cytokine activities. In skin cells CRH action is mediated by CRH‐R1, a subject to posttranslational modification with expression of alternatively spliced isoforms. Activation of CRH‐R1 induced generation of both cAMP and IP3 in the majority of epidermal and dermal cells (except for normal keratinocytes and one melanoma line), indicating cell type‐dependent coupling to signal transduction pathways. Phenotypic effects on cell proliferation were however dependent on both cell type and nutrition conditions. Specifically, CRH stimulated dermal fibroblasts proliferation, by increasing transition from G1/0 to the S phase, while in keratinocytes CRH inhibited cell proliferation. In normal and immortalized melanocytes CRH effect showed dichotomy and thus, it inhibited melanocyte proliferation in serum‐containing medium CRH through G2arrest, while serum free media led instead to CRH enhanced DNA synthesis (through increased transition from G1/G0to S phase and decreased subG1signal, indicating DNA degradation). CRH also induced inhibition of early and late apoptosis in the same cells, demonstrated by analysis with the annexin V stains. Thus, CRH acts on epidermal melanocytes as a survival factor under the stress of starvation (anti‐apoptotic) as well as inhibitor of growth factors induced cell proliferation. In conclusion, CRH and related peptides can couple CRH‐R1 to any of diverse signal transduction pathways; they also regulate cell viability and proliferation in cell type and growth condition‐dependent manners. J.Cell.Physiol. © 2005 Wiley‐Liss, Inc.
Basolateral aromatic amino acid transporter TAT1 (Slc16a10) functions as an efflux pathway
Authors: Ramadan Tamara , Camargo Simone M.R. , Summa Vanessa , Hunziker Peter , Chesnov Serge , Pos Klaas M. , Verrey Francois
Published: October 2005

Basolateral efflux is a necessary step in transepithelial (re)absorption of amino acids from small intestine and kidney proximal tubule. The best characterized basolateral amino acid transporters are y+LAT1‐4F2hc and LAT2‐4F2hc that function as obligatory exchangers and thus, do not contribute to net amino acid (re)absorption. The aromatic amino acid transporter TAT1 was shown previously to localize basolaterally in rat's small intestine and to mediate the efflux of L‐Trp in the absence of exchange substrate, upon expression in Xenopus oocytes. We compared here the amino acid influx and efflux via mouse TAT1 in Xenopus oocytes. The results show that mTAT1 functions as facilitated diffusion pathway for aromatic amino acids and that its properties are symmetrical in terms of selectivity and apparent affinity. We show by real‐time RT‐PCR that its mRNA is highly expressed in mouse small intestine mucosa, kidney, liver, and skeletal muscle as well as present in all other tested tissues. We show that mTAT1 is not N‐glycosylated and that it localizes to the mouse kidney proximal tubule. This expression is characterized by an axial gradient similar to that of the luminal neutral amino acid transporter B0AT1 and shows the same basolateral localization as 4F2hc. mTAT1 also localizes to the basolateral membrane of small intestine enterocytes and to the sinusoidal side of perivenous hepatocytes. In summary, we show that TAT1 is a basolateral epithelial transporter and that it can function as a net efflux pathway for aromatic amino acids. We propose that it, thereby, may supply parallel exchangers with recycling uptake substrates that could drive the efflux of other amino acids. J.Cell.Physiol. © 2005 Wiley‐Liss, Inc.
Transforming growth factor β1 regulates follistatin mrna expression during in vitro bovine granulosa cell differentiation
Authors: Fazzini Monica , Vallejo Griselda , Colman‐Lerner Alejandro , Trigo Romina , Campo Stella , Barañao J. Lino S. , Saragüeta Patricia E.
Published: October 2005

In order to test the hypothesis that transforming growth factor β (TGF‐β) acts by FS regulation on bovine granulosa cells in in vitro differentiation, we analyzed the effect of TGF‐β1 on follistatin mRNA expression in three differentiation states of bovine granulosa cells. We showed a positive regulation of FS mRNA after TGF‐β1 (1 ng/ml) treatment of freshly isolated granulosa cells from small‐medium antral follicles (2–8 mm). This effect was abolished by the addition of exogenous follistatin (100 ng/ml), suggesting that this effect could be mediated by activin. Although these cells showed a similar effect on FS mRNA expression after treatment with activin‐A, a soluble form of activin receptor type IIA was unable to inactivate the TGF‐β effect. When we tested the TGF‐β effect on FS mRNA in different granulosa cell states, TGF‐β1 regulation was associated with progesterone production only in freshly isolated cells. The amount of total activin‐A produced by first passage cells (dedifferentiated cells), was ten times smaller than the one measured in a conditioned medium from freshly isolated cells (mature cells). The TGF‐β1‐dependent FS mRNA expression persisted in first passage cells without changes with FS addition. On the other hand, the BGC‐1 granulosa cell line (immature cells) produced large amounts of activin‐A regulated by TGF‐β1 and an invariable steady state of FS mRNAs. In summary, our results showed that FS mRNA expression is regulated by TGF‐β1 independently of activin effects in differentiated granulosa cells. J. Cell. Physiol. 207: 40–48, 2006. © 2005 Wiley‐Liss, Inc.
ErbB‐receptors expression and survival in breast carcinoma: A 15‐year follow‐up study
Authors: Bianchi Simonetta , Palli Domenico , Falchetti Mario , Saieva Calogero , Masala Giovanna , Mancini Biancamaria , Lupi Ramona , Noviello Cristiana , Omerovic Jasminka , Paglierani Milena , Vezzosi Vania , Alimandi Maurizio , Mariani‐Costantini Renato , Ottini Laura
Published: October 2005

Aberrant expression of the epidermal growth factor receptor family has been implicated in the pathogenesis and progression of breast cancer and associated with poor prognosis. To evaluate the prognostic impact of the ErbB receptors expression profile, we analyzed a well‐characterized series of 145 primary breast carcinomas for the simultaneous expression of epidermal growth factor receptor (EGFR/HER‐1), ErbB‐2 (HER‐2), ErbB‐3 (HER‐3), and ErbB‐4 (HER‐4), using immunohistochemistry. Tumors were considered negative or positive for each marker when less than or more than 25% of the cancer cells were immunopositive. Expression of EGFR, ErbB‐2, ErbB‐3, and ErbB‐4 was observed in 31 (21.4%), 65 (44.8%), 72 (49.7%), and 81 (55.9%) of the cases, respectively. There were significant associations between EGFR expression and pT status (P = 0.01), and between ErbB‐3 expression and pN (P = 0.003), menopausal (P = 0.01) and PR (P < 0.001) status. The majority of the cases co‐expressed two or more receptors. ErbB‐3 resulted positive in 51/81 (63.0%) of the ErbB‐4 positive cases and ErbB‐3/ErbB‐4 co‐expression was statistically significant (P = 0.0003). As expected, ErbB‐2 expression was associated with reduced overall survival at 15 years of follow‐up (P = 0.04), even after adjusting for a series of other prognostic factors (P = 0.05). Moreover, cumulative analysis of ErbB‐2/3/4 expression showed a strong positive association between higher total ErbB‐2/3/4 expression score and worse prognosis (P = 0.002). The simultaneous expression in cancer cells of more than one ErbB receptor identifies a subset of breast cancer patients at high risk for poor survival. J.Cell.Physiol. © 2005 Wiley‐Liss, Inc.
Graph relations, clique divergence and surface triangulations
Authors: Larrión F. , Neumann‐Lara V. , Pizaña M.A.
Published: October 2005

This work has two aims: first, we introduce a powerful technique for proving clique divergence when the graph satisfies a certain symmetry condition. Second, we prove that each closed surface admits a clique divergent triangulation. By definition, a graph is clique divergent if the orders of its iterated clique graphs tend to infinity, and the clique graph of a graph is the intersection graph of its maximal complete subgraphs. © 2005 Wiley Periodicals, Inc. J Graph Theory
Biocomposites of Plasticized Starch Reinforced with Cellulose Crystallites from Cottonseed Linter
Authors: Lu Yongshang , Weng Lihui , Cao Xiaodong
Published: October 2005

Summary: Environmentally friendly starch biocomposites were successfully developed using a colloidal suspension of cottonseed linter cellulose crystallite as a filler to reinforce glycerol plasticized starch (PS). The cellulose crystallites, having lengths of 350 ± 70 nm and diameters of 40 ± 8 nm on average, were prepared from cottonseed linters by acid hydrolysis. The dependence of morphology and properties of the PS‐based biocomposites on cellulose crystallites content in the range from 0 to 30 wt.‐% was investigated by scanning electron microscopy, differential scanning thermal analysis, dynamic mechanical thermal analysis, and measurements of mechanical properties and water absorption. The results indicate that the strong interactions between fillers and between the filler and PS matrix play a key role in reinforcing the resulting composites. The PS/cellulose crystallite composites, conditioned at 50% relative humidity, undergo an increase in both tensile strength and Young's modulus from 2.5 MPa for PS film to 7.8 MPa and from 36 MPa for PS film to 301 MPa. Further, incorporating cottonseed linter cellulose crystallites into PS matrix leads to an improvement in water resistance for the resulting biocomposites.

The mechanical behaviors of the starch‐based biocomposites as a function of cellulose crystallites content.

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The mechanical behaviors of the starch‐based biocomposites as a function of cellulose crystallites content.
Ternary Complex Formation in Aqueous Solution between a β‐Cyclodextrin Polymer, a Cationic Surfactant and DNA
Authors: Galant Céline , Amiel Catherine , Auvray Loïc
Published: October 2005

Summary: Polyelectrolyte complexes have been elaborated by mixing in water neutral poly(β‐CD), a cationic surfactant (DTAC) and herring sperm DNA fragments. The driving forces for the poly(β‐CD)/DTAC/DNA association in aqueous solution are, on the one hand, reversible inclusion interactions between the CD cavities of poly(β‐CD) and the alkyl group of DTAC, leading to the formation of a polycation and, on the other hand, electrostatic interactions between the opposite charges of the cationic surfactant and anionic DNA. Viscometry and SANS have been used to prove the occurrence of such ternary complexes in dilute aqueous solutions.

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Preparation and Interfacial Properties of a Novel Biodegradable Polymer Surfactant: Poly(ethylene oxide monooleate‐block‐DL‐lactide)
Authors: Nishino Satoru , Kitamura Yoshiro , Kishida Akio , Yoshizawa Hidekazu
Published: October 2005

Summary: In this paper, we report a novel synthesis of poly(ethylene oxide monooleate‐block‐DL‐lactide) (MOPEO‐PLA) in the presence of stannous 2‐ethylhexanoate catalyst. By utilizing the surfactant property and the reactive double bond of the amphiphilic MOPEO‐PLA, various characteristics of PLA microspheres, such as surface and internal structure, surface morphology, release property, and so on, may potentially be controlled. MOPEO‐PLA was found to be hydrophobic enough to prevent loss by dissolution into aqueous solution, which is often a problem for MOPEO. Furthermore, the interfacial tension measurements of a MOPEO‐PLA/toluene/water system revealed that MOPEO‐PLA had a good surface activity almost equal to that of MOPEO. The MOPEO‐PLA/PLA blend films were prepared by solvent casting on a water layer. Contact‐angle measurements of MOPEO‐PLA/PLA blend films confirmed that the hydrophilic PEO segments were selectivity accumulated at the oil/water interface. Moreover, the surface free energy on the ‘water side’ of the MOPEO‐PLA/PLA blend films was increased because of the increase in polar components as a result of the ether bonds of the PEO segments.

Schematic illustration of the adsorption property of a) MOPEO‐PLA with a high‐molecular‐weight PLA segment and b) MOPEO‐PLA with a low‐molecular‐weight PLA segment at an ethyl acetate/water interface.

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Schematic illustration of the adsorption property of a) MOPEO‐PLA with a high‐molecular‐weight PLA segment and b) MOPEO‐PLA with a low‐molecular‐weight PLA segment at an ethyl acetate/water interface.
UV‐Photocrosslinking of Inulin Derivatives to Produce Hydrogels for Drug Delivery Application
Authors: Tripodo Giuseppe , Pitarresi Giovanna , Palumbo Fabio Salvatore , Craparo Emanuela Fabiola , Giammona Gaetano
Published: October 2005

Summary: In this work, INU, a natural polysaccharide, has been chemically modified in order to obtain new photocrosslinkable derivatives. To reach this goal, INU has been derivatized with MA thus obtaining four samples (INU‐MA derivatives) as a function of the temperature and time of reaction. An aqueous solution of the derivative INU‐MA1 was irradiated by using a UV lamp with an emission range from 250 to 364 nm and without using photoinitiators. The obtained hydrogel showed a remarkable water affinity but it underwent a partial degradation in simulated gastric fluid. To overcome this drawback, INU‐MA1 was derivatized with SA thus obtaining the INU‐MA1‐SA derivative designed to produce a hydrogel showing a low swelling and an increased chemical stability in acidic medium. Ibuprofen, as a model drug, was loaded by soaking into INU‐MA1 and INU‐MA1‐SA hydrogels and its release from these matrices was evaluated in simulated gastrointestinal fluids. INU‐MA1 hydrogel showed the ability to quickly release the entrapped drug thus indicating its potential as a matrix for an oral formulation. INU‐MA1‐SA hydrogel showed a pH‐responsive drug delivery. Therefore it is a promising candidate for controlled drug release in the intestinal tract.

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Synthesis and Rheological Properties of Polylactide/Poly(ethylene glycol) Multiblock Copolymers
Authors: Li Feng , Li Suming , Vert Michel
Published: October 2005

Summary: Ring‐opening polymerization of D,L‐lactide was carried out in the presence of poly(ethylene glycol), using Zn powder as catalyst. The hydroxyl‐capped PLA‐PEG‐PLA triblock copolymers were coupled with adipoyl chloride at different molar ratios under mild conditions. N‐Dimethylaminopyridine (DMAP) was used as catalyst of the coupling reaction. The resulting PLA/PEG multiblock copolymers were characterized by various analytical techniques such as IR, 1H NMR, SEC, and DSC. Sol‐gel transition properties of the multiblock copolymers were investigated by mechanical rheology. The data showed that the sol‐gel transition temperature and the transition modulus increased with increasing molecular weight and the solution concentration of the multiblock copolymers.

Variation of storage modulus (G′) and loss modulus (G″) as a function of temperature for a 20% sample of MB3.

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Variation of storage modulus (G′) and loss modulus (G″) as a function of temperature for a 20% sample of MB3.
Resorcinol‐Formalin Foam Balls Via Gelation of Emulsion Using Phase‐Transfer Catalysts
Authors: Ito Fuyumi , Nagai Keiji , Nakai Mitsuo , Norimatsu Takayoshi
Published: October 2005

Summary: Highly spherical (98.5%) low‐density foam balls with 1‐mm diameters were fabricated from a density‐matched emulsion consisting of a resorcinol/formalin aqueous solution and a (mineral oil and carbon tetrachloride) mixture. Phase‐transfer catalysts of carboxylic acid were utilized to induce gelation of the emulsion. The gelation process was monitored by a mechanical test. Gelation forming ball shapes happened within 20–30 min, depending on the catalysts, at room temperature. The gelation time decreased with high‐catalyst concentration. Acids with long alkyl chains did not induce gelation and no balls were obtained. The gelated balls were dried to obtain foam via an exchange of the solvent with 2‐propanol and extraction using the supercritical fluid CO2. The density obtained from the catalyst was 0.15–0.16 g · cm−3. SEM images revealed surface membrane formation, which can be explained by local concentration at the interface of W/O. We observed different bulk foam cell sizes, which may depend on the catalysts and, therefore, on the different gelation rates.

Structure of a highly spherical low‐density foam ball with 1‐mm diameter.

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Structure of a highly spherical low‐density foam ball with 1‐mm diameter.
Transesterification of Poly(4,4′‐isopropylidene‐2,2′‐dimethyldiphenylene terephthalate) and Poly(ethylene adipate) Blend in Solution
Authors: Krentsel Liya B. , Markova Gali D. , Kudryavtsev Yaroslav V. , Filatova Marina P. , Vasnev Valerii A. , Litmanovich Arkady D. , Platé Nikolay A.
Published: October 2005

Summary: Transesterification of poly(4,4′‐isopropylidene‐2,2′‐dimethyldiphenylene terephthalate) and poly(ethylene adipate) (PEA) has been carried out in concentrated o‐dichlorobenzene solution at 210 °C with Bu2SnO as a catalyst. According to GPC data, during transesterification the reaction product acquires Flory MWD and only a slight degradation of chains proceeds in the system: on average each chain having undergone about one scission in 100 min. Chain structure of the reaction products was studied using 1H NMR spectroscopy. The kinetic and statistical analysis of the process was performed using following assumptions: transesterification proceeds in a homogeneous medium as a reversible second‐order reaction between diads, and the product chain structure obeys the first‐order Markov statistics. Calculated dependences of the parameters characterizing an evolution of the chain structure during the reaction fit experimental data fairly well. In 100 min the reacting system reaches a state close to the equilibrium. The difference between distributions of diads of residues and units is considered.

Change of the terephthalate‐centered r‐triads content with time.

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Change of the terephthalate‐centered r‐triads content with time.
Conjugated Silole and Carbazole Copolymers: Synthesis, Characterization, Single‐Layer Light‐Emitting Diode, and Field Effect Carrier Mobility
Authors: Wang Yan , Hou Lintao , Yang Kaixia , Chen Junwu , Wang Feng , Cao Yong
Published: October 2005

Summary: Soluble conjugated random and alternating copolymers (PCz‐PSP) derived from N‐hexyl‐3,6‐carbazole (Cz) and 1,1‐dimethyl‐2,3,4,5‐tetraphenylsilole (PSP) were synthesized by palladium(0)‐catalyzed Suzuki coupling reactions. The feed ratios of Cz to PSP were 95:5, 90:10, 80:20, 70:30, and 50:50. Chemical structures and optoelectronic properties of the copolymers were characterized by 1H NMR, 13C NMR, UV absorption, cyclic voltammetry, photoluminescence, electroluminescence, and field effect transistor. HOMO levels of the copolymers are between −5.15 and −5.34 eV. Single‐layer devices with a configuration of ITO/copolymer/Ba/Al were fabricated and the copolymer with PSP content of 20% displayed the highest external quantum efficiency of 0.77%. Field effect transistors with tantalum pentoxide‐polyacrylonitrile double insulators demonstrated that hole mobilities of the copolymers decreased with their PSP contents, and the hole mobility up to 9.3 × 10−6 cm2 · (V · s)−1 could be achieved.

Synthesis of coplymers derived from 3,6‐carbazole and silole.

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Synthesis of coplymers derived from 3,6‐carbazole and silole.
A New Copolymer Containing Perylene Bisimide and Porphyrin Moieties: Synthesis and Characterization
Authors: He Xiaorong , Liu Huibiao , Li Yuliang , Liu Yang , Lu Fushen , Li Yongjun , Zhu Daoben
Published: October 2005

Summary: A novel copolymer containing perylene bisimide and porphyrin units was synthesized through a Wittig‐type coupling reaction and characterized. An electrochemical experiment showed its electronic properties. Optoelectronic measurements showed a steady and rapid cathodic photocurrent response of the polymer film. The features of copolymer colloids were also studied by UV‐Vis spectrometry and TEM. A large quantity of nanoparticles were observed with TEM, with a mean diameter of 200 nm. The size effect leads the absorption wavelength of the nanoparticles to be red‐shifted, which is consistent with the results of UV‐Vis spectrometry.

TEM image of the polymer colloid.

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TEM image of the polymer colloid.
Michael Addition Polymerizations of Trifunctional Amines with Divinyl Sulfone
Authors: Zheng Zhiju , Pan Caiyuan , Wang Ding , Liu Ye
Published: October 2005

Summary: The mechanisms of the Michael addition polymerization of N‐aminoethyl piperazine (AEPZ) with divinyl sulfone (DVS) were clarified based on the reactivity sequence of three different amines in AEPZ: 2° amine in piperazine ring > 1° amine ≫ 2° amine formed in situ. When the feed molar ratio of DVS to AEPZ was 1:1, the polymerization of AB intermediate formed proceeded, and the linear poly(sulfone amine) containing secondary and tertiary amines in the backbones were produced. The linear structure of the product was confirmed by NMR spectra, and the molecular weights, molecular weight distribution, and properties of poly(sulfone amine)s were characterized by GPC, DSC, and TGA.

Polymerization of linear poly(DVS‐AEPZ).

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Polymerization of linear poly(DVS‐AEPZ).
Multicyclic Poly(ether ketone)s by Polycondensation of 1,3,5‐Tris(4‐fluorobenzoyl)benzene with Various Diphenols
Authors: Kricheldorf Hans R. , Hobzova Radka , Vakhtangishvili Lali , Schwarz Gert
Published: October 2005

Summary: 1,3,5‐Tris(4‐fluorobenzoyl)benzene (TFBB) was polycondensed with silylated 4,4′‐dihydroxybiphenyl, bisphenol‐A or 4‐tert‐butylcatechol in N‐methylpyrrolidine with K2CO3 as a promoter. The TFBB/diphenol feed ratio was varied from 1.0:1.0 to 1:0:1.5. Partial cross‐linking was observed with the stiff 4,4′‐dihydroxybiphenyl, even at the 1.0:1.0 ratio. With bisphenol‐A, no gelation took place up to a feed ratio of 1.0:1.3, indicating a high cyclization tendency. With 4‐tert‐butylcatechol, no cross‐linking occurred up to the 1.0:1.5 ratio, proving an even higher cyclization tendency. The formation of cyclic, bicyclic and multicyclic oligo‐ and polyethers was detected by means of MALDI‐TOF mass spectrometry for all reaction products. These results demonstrate that increasing chain stiffness reduces the influence of cyclization. Cyclization proved unavoidable, however, and a high cyclization tendency prevents the formation of hyperbranched and networked structures.

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Simple Synthesis of Hierarchically Structured Silicas by Poly(ethyleneimine) Aggregates Pre‐Organized by Media Modulation
Authors: Jin Ren‐Hua , Yuan Jian‐Jun
Published: October 2005

Summary: In this paper, we describe the multiple morphogenesis of poly(ethyleneimine) (PEI)‐directed silicas through the facile tuning of the media in which the PEIs pre‐organize. The silica shapes and structures ranged from nanofiber‐based asters, fans, particles, plates, and/or curved films to large aggregates composed of unit nanoribbon structures and networks that contained nanospheres or particles, depending on the media compositions or media modulations coupled with the polymer concentrations and chain architectures. We found that the media modulations not only controlled the formation of the silica unit structures but also manipulated the hierarchical structures based on the unit silicas. Furthermore, methanol modulation successfully allows us to elucidate the dependence of silica deposition ability on the polymer chain architectures that cause subtle differences in their aggregates. The approach of methanol modulation to obtain shaped silicas, which involves both PEI aggregation and silica deposition at room temperature, is of particular interest to applications for the immobilization of bioactive components.

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Cover Picture: Macromol. Chem. Phys. 20/2005
Authors: Jang Yong‐Jun , Naundorf Corinna , Klapper Markus , Müllen Klaus
Published: October 2005

Cover: The images of polyolefin product beads recorded by laser scanning confocal fluorescence microscopy (LSCFM) show the distribution of metallocene catalysts supported on silica and latex particles after different reaction times. This is correlated to fragmentation processes schematically presented below. Further details can be found in the Full Paper by Y.‐J. Jang, C. Naundorf, M. Klapper*, and K. Müllen* on page 2027.
Linear Viscoelastic Characteristics of Poly(trimethylene terephthalate)/Polycarbonate Blends in the Melt State
Authors: Yavari Ahmad , Asadinezhad Ahmad , Jafari Seyed Hassan , Khonakdar Hossein Ali , Ahmadian Shahin , Böhme Frank
Published: October 2005

Summary: Blends of poly(trimethylene terephthalate) (PTT) and polycarbonate (PC) over full composition range were prepared using a twin‐screw extruder. A glycidyl methacrylate‐based terpolymer was used to modify the interface of the blends. Morphological examinations were carried out using transmission electron microscopy (TEM) and confirmed the biphasic structure of the blends. Dynamic rheological response of the blends was recorded in the linear viscoelastic region. It was observed that addition of the terpolymer to the system increases the dynamic shear moduli and complex viscosity of the blends, which is attributed to interactions of the terpolymer at the interface of two phases leading to a restricted chain mobility of the blend components. The Veenstra model was found to be able to describe dynamic shear modulus of the PTT/PC 50/50 blend; however, for the compatibilized blend of PTT/PC 50/50, the fit is not as good as that of uncompatibilized system, which is believed to be due to formation of micelles in this system.

Dynamic storage modulus of the compatibilized and uncompatibilized PTT/PC blends.

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Dynamic storage modulus of the compatibilized and uncompatibilized PTT/PC blends.
Di‐Channel Polyfluorene Containing Spiro‐Bridged Oxadiazole Branches
Authors: Zhu Rui , Wen Gui‐An , Feng Jia‐Chun , Chen Run‐Feng , Zhao Lei , Yao He‐Ping , Fan Qu‐Li , Wei Wei , Peng Bo , Huang Wei
Published: October 2005

Summary: A p–n di‐channel copolymer based on polyfluorene (PF) has been designed and prepared. Branches containing oxadiazole units are attached to the PF backbone through the spiro‐structure and act as channels to improve the electron affinity; these branches form a steric ‘di‐channel’ framework with the polymer backbone. The polymer possesses excellent thermal stability. The lowest unoccupied molecular orbital energy level of the polymer is significantly altered in comparison with poly(9,9‐dioctylfluorene‐2,7‐diyl).

Schematic of the di‐channel polyfluorene synthesized here and the mechanism of energy transfer through the structure.

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Schematic of the di‐channel polyfluorene synthesized here and the mechanism of energy transfer through the structure.
Preparation of a Polyethylene Latex by Catalytic Hydrogenation of a Polybuta‐1,4‐diene‐Based Dispersion
Authors: Chemtob Abraham , Heroguez Valérie , Gnanou Yves
Published: October 2005

Summary: Fully linear polyethylene‐based latexes have been prepared by the hydrogenation of polybuta‐1,4‐diene dispersions. The latter were synthesized via dispersion ring‐opening metathesis polymerization of cycloocta‐1,5‐diene, and hydrogenated using RuCl2(PPh3)3 as catalyst, without any further treatment. A high hydrogenation efficiency was achieved as demonstrated by different techniques including DSC, and 1H NMR and FT‐IR spectroscopy. The hydrogenation process could be carried out without detrimental effect on particle size and colloidal stability as evidenced by optical microscopy and light scattering analysis.

Optical microscopy photograph of a polybutadiene‐based dispersion after hydrogenation. No change in size is observed.

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Optical microscopy photograph of a polybutadiene‐based dispersion after hydrogenation. No change in size is observed.
A New Acyclic α‐Hydrogen Bearing Nitroxide and its Corresponding Alkoxyamine for Stable Free Radical Polymerization
Authors: Flakus Silke , Mandel Kerstin , Bartsch Martina , Schmidt‐Naake Gudrun
Published: October 2005

Summary: The synthesis of the new α‐hydrogen bearing nitroxide, 2,2,5‐trimethyl‐4‐(isopropyl)‐3‐azahexane‐3‐oxyl (BIPNO) (4), and its corresponding alkoxyamine, N‐tert‐butyl‐N‐(1‐isopropyl‐2‐methyl‐propyl)‐O‐(1‐phenyl‐ethyl)‐hydroxylamine (PhEt‐BIPNO) (7), are described in this paper. Reaction of styrene with the new nitroxide in the presence of a Jacobsen‐like manganese catalyst, Mn(salen)Cl, at ambient atmosphere afforded the alkoxyamine in 96% yield. Styrene and n‐butyl acrylate were polymerized in bulk in the presence of the new alkoxyamine. The alkoxyamine turned out to be a suitable “initiator” for controlled radical polymerization.

Structure of α‐hydrogen bearing nitroxide and its corresponding alkoxyamine.

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Structure of α‐hydrogen bearing nitroxide and its corresponding alkoxyamine.
Photoinitiators with Functional Groups, 8
Authors: Jauk Sigrid , Liska Robert
Published: October 2005

Summary: Bimolecular type‐II photoinitiators for radical photopolymerization suffer from a diffusion‐controlled limitation of reactivity and from deactivation by back electron transfer. Here, a very efficient concept to increase the photoinitiator activity by the covalent binding of phenylglycine to benzophenone using a methylene spacer is presented. Photo‐DSC experiments proved that the rate of polymerization can be tripled in comparison to a physical mixture of the components or an industrially applied system with triethanolamine as coinitiator.

Structure of the new photoinitiator synthesized here.

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Structure of the new photoinitiator synthesized here.
Micelles Formed by Cylindrical Brush‐Coil Block Copolymers
Authors: Khelfallah Nawel , Gunari Nikhil , Fischer Karl , Gkogkas Giorgos , Hadjichristidis Nikos , Schmidt Manfred
Published: October 2005

Summary: Amphiphilic cylindrical brush‐coil block copolymers consisting of a polystyrene coil and a cylindrical brush block with poly(acrylic acid) side chains are prepared by ATRP of t‐butylacrylate from a block comacroinitiator. Upon acidolysis of the poly(t‐butylacrylate), water‐soluble polymers were obtained that were observed to form micelles consisting of 4–5 block copolymers on average in aqueous solution. The star‐like nature of such micelles was clearly visualized by scanning force microscopy.

Schematic of coil‐cylindrical brush block copolymer PS‐b‐(PiBEMA‐g‐PAA), its AFM image clearly showing the main chain and the PAA corona of the cylindrical brush block.

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Schematic of coil‐cylindrical brush block copolymer PS‐b‐(PiBEMA‐g‐PAA), its AFM image clearly showing the main chain and the PAA corona of the cylindrical brush block.
Facile Fabrication of Functional Polypyrrole Nanotubes via a Reactive Self‐Degraded Template
Authors: Yang Xiaoming , Zhu Zhengxi , Dai Tingyang , Lu Yun
Published: October 2005

Summary: Polypyrrole nanotubes with high electric conductivity and azo function have been fabricated in high yield via an in‐situ polymerization. During the process fibrillar complex of FeCl3 and methyl orange (MO), acting as a reactive self‐degraded template, directed the growth of polypyrrole on its surface and promoted the assembly into hollow nanotubular structures.

TEM image of uncompleted PPy nanotubes synthesized in MO solutions after reaction for 40 min.

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TEM image of uncompleted PPy nanotubes synthesized in MO solutions after reaction for 40 min.
Non‐Lipschitzian control algorithms: application to a nanofriction model
Authors: Protopopescu Vladimir , Barhen Jacob , Amselem Gabriel , Dahan Julien
Published: October 2005

Recently we proposed a new feedback control algorithm for quantities describing global features of non‐linear dynamical systems. The performance of the algorithm, which is based on the concepts of non‐Lipschitzian dynamics and global targeting, has been successfully demonstrated for systems confined to one spatial dimension and for a specific targeted global quantity, namely the velocity of the centre of mass. In this paper we extend the scope of the non‐Lipschitzian control scheme to multi‐dimensional systems and different targeted quantities. We illustrate the efficiency of the non‐Lipschitzian feedback w.r.t. the ordinary (Lipschitzian) feedback, as well as the robustness and accuracy of the algorithm in a broad variety of control scenarios on the 2‐d Frenkel‐Kontorova model for nanofriction. Published in 2005 by John Wiley & Sons, Ltd.
Understanding self‐organization of the inclusion complexes in the solid state—DSC, NMR and DFT studies
Authors: Potrzebowski M. J. , Heliński J. , Olejniczak S. , Ciesielski W.
Published: October 2005

The relationship between DSC profiles and changes of 13C and 31P the spin–lattice relaxation time of the host and 1H T1 of guest in inclusion complexes of bis[6‐O,6‐O′‐(1,2:3,4‐diisopropylidene‐α‐D‐galactopyranosyl)thiophosphoryl] disulfide (DGTD) with n‐propanol is discussed in term of guest migration in the crystal lattice. 1H–13C FSLG HETCOR experiment recorded with different contact times was employed to establish the guest localization in the crystal lattice for different modifications of the inclusion complex. The migration pathway of the guest was verified by means of theoretical DFT calculations. Copyright © 2005 John Wiley & Sons, Ltd.
Experimental techniques in high‐vacuum anionic polymerization
Authors: Uhrig David , Mays Jimmy W.
Published: October 2005

Experimental methods used in high‐vacuum anionic polymerization are described in detail, with extensive illustrations to demonstrate proper procedures and techniques. These descriptions include construction and operation of the vacuum line, handling purification chemicals, ampulization techniques, short‐path distillations, initiator synthesis, polymerization procedures, and linking reactions using chlorosilanes. A primary emphasis is placed on safety. We believe that this review of these methods will be useful to scientists working in the field of anionic polymerization and may also benefit other researchers in performing tasks requiring ultra‐high‐purity reaction conditions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6179–6222, 2005
Salt effect on polyaddition of bifunctional cyclic carbonate and diamine
Authors: Ochiai Bungo , Inoue Shoko , Endo Takeshi
Published: October 2005

The effect of various additives was examined for polyaddition of bifunctional cyclic carbonate and diamine giving poly(hydroxyurethane). Lithium chloride and lithium fluoride especially proved to be effective for the acceleration that resulted in giving polymers with higher molecular weights without coloration. The IR spectroscopic analysis of the mixtures of the additives and the carbonate monomer suggested that the acceleration with the lithium salts depends on the activation of the carbonyl group to enhance its electrophilicity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6282–6286, 2005
Polyimides based on new diamines having pendant imide groups
Authors: Kricheldorf Hans R. , Fan Shu‐chin , Vakhtangishvili Lali , Schwarz Gert , Fritsch Detlef
Published: October 2005

New aromatic diamines were prepared in two steps from 4,5‐dichlorophthalic anhydride and primary amines. The resulting 4,5‐dichlorophthalimide was reacted with 4‐mercaptoaniline, so that the chloroatoms were substituted by the mercapto groups (via the sulfide anions). The new diamines were polycondensed either with the diphenyl ether 3,3′,4,4′‐tetracarboxylic anhydride or with bicyclooctane tetracarboxylic anhydride. These polycondensations were conducted in boiling m‐cresol with azeotropic removal of water. The isolated polyimides were characterized by viscosity measurement, IR‐spectroscopy, elemental analyses, and MALDI‐TOF mass spectrometry. The mass spectra evidenced a high content of cyclic polyimides, indicating nearly perfect reaction conditions. The mass spectra also proved the formation of copolymers containing one diamine with a trialkylamine group in the side chain. High glass transition temperatures but a low crystallization tendency were found by DSC measurements. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6272–6281, 2005
Multicyclic polyethers with pendant keto groups by polycondensation of silylated 1,1,1‐tris(4‐hydroxyphenyl)ethane
Authors: Kricheldorf Hans R. , Vakhtangishvili Lali , Schwarz Gert , Prosenc Marc
Published: October 2005

1,1,1‐Tris(4‐trimethylsiloxyphenyl)ethane, (silylated THPE), was polycondensed with 2,4‐difluoroacetophenone and 2,4‐difluorobenzophenone. All polycondensations were performed in N‐methylpyrrolidone with K2CO3 as promotor. The feed ratio THPE/difluoroaromat was varied from 1.0:1.3 to 1.0:1.5. Instead of hyperbranched polymers or gels, soluble multicyclic oligo‐ and polyethers were identified as main reaction products by MALDI‐TOF mass spectrometry in all experiments. At feed ratios around 1.0:1.5 multicycles free of functional group were the main products. However, when isomeric a2‐monomers such as 2,6‐difluoroacetophenone, 2,6‐difluorobenzophenone (or 2,6‐difluorodiphenylsulfone) were used, gelation occurred at feed ratios as low as 1.0:1.1. An explanation of the different cyclization tendencies on the basis of different conformations is discussed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6233–6246, 2005
Solvent effect on the atom transfer radical polymerization of allyl methacrylate
Authors: París Rodrigo , de la Fuente José Luis
Published: October 2005

The controlled radical polymerization of allyl methacrylate by atom transfer radical polymerization was carried out in solution at 70 °C, with ethyl 2‐bromoisobutyrate as the initiator and copper halide (CuX, where X is Cl or Br) with N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst system. Kinetic analyses demonstrated that all the homopolymerization reactions showed a general behavior characterized by two clearly differentiated stages. Thus, in the early stage, the conversion increased continually with the time, independently of the solvent employed. In the second stage, a deceleration process took place, and a limit conversion was achieved, depending on the polarity and amount of the solvent used. The dependence of both the gel formation and limit conversion, as well as the molecular characteristics of poly(allyl methacrylate)s formed with different experimental parameters, such as the initial monomer concentration, the solvent employed, and the type of halide used as a catalyst, was also examined. The prepared polymers were characterized by size exclusion chromatography, Fourier transform infrared, and one‐ and two‐dimensional nuclear magnetic resonance spectroscopy. Moreover, chain‐growth experiments with butyl acrylate as the comonomer proved the living character of the poly(allyl methacrylate)s obtained, with these used as macroinitiators. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6247–6261, 2005
Deuterium oxide promotes assembly and bundling of FtsZ protofilaments
Authors: Santra Manas Kumar , Dasgupta Debjani , Panda Dulal
Published: October 2005

The assembly and bundling of FtsZ protofilaments play an important role during bacterial cell division. Deuterium oxide (D2O) is known to have strong stabilization effects on the assembly dynamics of several proteins including tubulin, a homologue of FtsZ. Here, we found that D2O enhanced the light‐scattering intensity of the assembly reaction, increased sedimentable polymer mass, and induced bundling of FtsZ protofilaments. D2O also increased the stability of FtsZ polymers under challenged GTP conditions and suppressed dilution‐induced disassembly of protofilaments. D2O enhances the assembly parameters of FtsZ and microtubules albeit differently. For example, D2O induced bundling of FtsZ protofilaments, whereas it did not induce bundling of microtubules in vitro. In addition, D2O strongly suppressed the GTP hydrolysis rate of microtubules, but it had no effect on the initial rate of GTP hydrolysis of the FtsZ assembly. D2O (80%) also increased the helical content of FtsZ by 25% compared to the helical content of FtsZ in aqueous buffer. D2O was shown to reduce the binding of 4,4′‐dianilino‐1,1′‐binaphthyl‐5,5′‐disulfonic acid (bis‐ANS) to tubulin. In contrast, we found that D2O strongly enhanced the binding of bis‐ANS to FtsZ. The results indicated that D2O promotes assembly and bundling of FtsZ protofilaments by increasing hydrophobic interactions between the protofilaments. The results also suggest that the phosphate release rather than the on‐site GTP hydrolysis is the rate‐limiting step of the GTP turnover reaction. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Effects of environment on the structure of Pyrococcus furiosus rubredoxin: A molecular dynamics study
Authors: Ergenekan Can E. , Tan Ming‐Liang , Ichiye Toshiko
Published: October 2005

Molecular dynamics simulations based on a 0.95‐Å resolution crystal structure of Pyrococcus furiosus have been performed to elucidate the effects of the environment on the structure of rubredoxin, and proteins in general. Three 1‐ns simulations are reported here: two crystalline state simulations at 123 and 300 K, and a solution state simulation at 300 K. These simulations show that temperature has a greater impact on the protein structure than the close molecular contacts of the crystal matrix in rubredoxin, although both have an effect on its dynamic properties. These results indicate that differences between NMR solution structures and X‐ray crystal structures will be relatively minor if they are done at similar temperatures. In addition, the crystal simulations appears to mimic previous crystallographic experiments on the effects of cryo‐temperature on temperature factors, and might provide a useful tool in the structural analysis of protein structures solved at cryo‐temperatures. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Rational genomics I: Antisense open reading frames and codon bias in short‐chain oxido reductase enzymes and the evolution of the genetic code
Authors: Duax William L. , Huether Robert , Pletnev Vladimir Z. , Langs David , Addlagatta Anthony , Connare Sonjay , Habegger Lukas , Gill Jay
Published: October 2005

The short‐chain oxidoreductase (SCOR) family of enzymes includes over 6000 members, extending from bacteria and archaea to humans. Nucleic acid sequence analysis reveals that significant numbers of these genes are remarkably free of stopcodons in reading frames other than the coding frame, including those on the antisense strand. The genes from this subset also use almost entirely the GC‐rich half of the 64 codons. Analysis of a million hypothetical genes having random nucleotide composition shows that the percentage of SCOR genes having multiple open reading frames exceeds random by a factor of as much as 1 × 106. Nevertheless, screening the content of the SWISS‐PROT TrEMBL database reveals that 15% of all genes contain multiple open reading frames. The SCOR genes having multiple open reading frames and a GC‐rich coding bias exhibit a similar GC bias in the nucleotide triple composition of their DNA. This bias is not correlated with the GC content of the species in which the SCOR genes are found. One possible explanation for the conservation of multiple open reading frames and extreme bias in nucleic acid composition in the family of Rossman folds is that the primordial member of this family was encoded early using only very stable GC‐rich DNA and that evolution proceeded with extremely limited introduction of any codons having two or more adenine or thymine nucleotides. These and other data suggest that the SCOR family of enzymes may even have diverged from a common ancestor before most of the AT‐rich half of the genetic code was fully defined. Proteins 2005. © 2005 Wiley‐Liss, Inc.