bluuebunny/crossref_metadata_2025 huggingface dataset:
Multidimensional long‐term time‐lapse microscopy of in vitro peripheral nerve regeneration
Authors: Öztürk Gürkan , Erdoǧan Ender
Published: September 2004

In order to test the effectiveness of a new advanced time‐lapse microscopy imaging and image processing and analysis system, and to do quantitative and qualitative temporal analyses of in vitro peripheral nerve regeneration, long‐term time‐lapse imaging of cultures of mouse dorsal root ganglia (DRGs) was performed. DRGs were placed in a Petri dish, covered with collagen gel, their attached peripheral nerves were cut in the middle, creating a gap, and the dish was filled with culture medium. Six preparations were kept on the time‐lapse imaging system, which provides a suitable incubation environment and enables to capture images from multiple coordinates at x,y,z axes at desired time intervals for 13 days. In general, the time‐lapse imaging system proved quite stable and efficient, although some improvements are certainly required. Two main components of peripheral nerve regeneration, outgrowth of axons and activities of resident cells, were examined. Axons started to grow during the first hour of incubation with a 16.5 μm/h rate and showed the slowest rates (0.7 μm/h) on days 8 and 9, after which they resumed higher speeds again. The first cell came out of the proximal end of the cut nerve on the second day and it was a Schwann cell (SC), which was the prominent cell type in the preparations throughout the experiment. SCs were higher in number (83.15% of all cells) but slower in migration (3.4 vs. 7.3 μm/h, P < 0.001) than other cells. Other observed characteristics of axonal outgrowth and cellular activity and interactions between axons and the cells are discussed. Microsc. Res. Tech. 64:228–242, 2004. © 2004 Wiley‐Liss, Inc.
Chiral recognition in solution and the gas phase. Experimental and theoretical studies of aromatic D‐ and L‐amino acid–Cu(II)–chiragen complexes
Authors: Seymour Jennifer L. , Tureček František , Malkov Andrei V. , Kočovský Pavel
Published: September 2004

This study was focused on distinguishing L‐ and D‐enantiomers of amino acids using electrospray ionization mass spectrometry (ESI‐MS) of ternary complexes with Cu(II) and chiral derivatives of bipyridine. A pinene‐annulated derivative of 2,2′‐bipyridine, (5R,7S,8S)‐(−)‐5,6,7,8‐tetrahydro‐6,6,8‐trimethyl‐2‐(pyridin‐2‐yl)‐5,7‐methanoquinoline, called a chiragen, was used as the auxiliary ligand bound to Cu(II) to study the complexation of D‐ and L‐phenylalanine and D‐ and L‐tryptophan and their detection by MS. NMR studies showed that the D‐ and L‐amino acid complexes can be distinguished in solution by the difference in the amount of band broadening of the α‐carbon proton, with the D‐complex showing greater broadening from a more intense interaction with the paramagnetic copper center. In ESI‐MS studies, the ion abundances for the analyte complexes were compared with those of internal standards to investigate competition in binding to Cu(II)chiragen between the internal standard and D‐ and L‐amino acids. The D‐Phe complex showed stronger binding than the L‐Phe complex, although differences in response related to solvent effects were also apparent. In studies involving two separate internal standards, the Trp enantiomers were practically indistinguishable in all but one solvent environment. In 100% methanol, the L‐Phe and D‐Phe complexes were readily distinguished and the L‐Phe complex out‐competed the L‐Phe complex by a factor of two. Density functional theory calculations were performed on D‐ and L‐complexes of Phe and Trp to determine the optimized geometries and the most energetically favorable structures. Calculations agreed with experiments, where the D‐Phe complex was the most stable structure, while the L‐Trp and D‐Trp complexes were comparably stable in the gas phase. Copyright © 2004 John Wiley & Sons, Ltd.
Accuracy of enthalpy and entropy determination using the kinetic method: are we approaching a consensus?
Authors: Drahos László , Peltz Csaba , Vékey Károly
Published: September 2004

There is an emerging consensus regarding the applicability of the kinetic method. All parties acknowledge that it is an approximate quantitative technique, capable of yielding not only enthalpy, but also entropy values. Opinions differ mainly on the accuracy of the results but it is agreed that the energy (effective temperature) dependence of kinetic method plots needs to be checked in all but the simplest of cases. When the ‘apparent basicity’ is found to depend on collision energy (and hence effective temperature), the extended kinetic method must be used. We have performed a large‐scale modeling study, involving thousands of randomly selected molecular systems and a variety of experimental conditions, using exact calculations and realistic data sets. The results show that when the measured entropy difference between the two competing reaction channels is less than ∼35 J mol−1 K−1, overall errors (standard deviations) of ΔH298 determined by the kinetic method are ±5 kJ mol−1; those of ΔS298 are ±10 J mol−1 K−1. These include not only inherent errors of the kinetic method, but also errors in ion abundance measurement (5%) and inaccurate knowledge of reference compound thermochemistry (±2 kJ mol−1, on average). We recommend, in general, that these errors be reported in kinetic method studies. When the measured entropy difference between the two competing fragmentation channels is large (>35 J mol−1 K−1), it is likely to be significantly underestimated and errors of the kinetic method increase significantly. Copyright © 2004 John Wiley & Sons, Ltd.
Internalization of the dengue virus is cell cycle modulated in HepG2, but not vero cells
Authors: Phoolcharoen Waranyoo , Smith Duncan R.
Published: September 2004

While many studies have investigated the relationship between cell type and dengue virus infection, no study to date has examined the effect of cell physiology on permissiveness to infection. Unsynchronized and artificially synchronized cell populations at different stages of the cell cycle of two cell types (Vero and HepG2) were examined for permissiveness to infection by two dengue virus serotypes (serotypes 2 and 3) by determining both the levels of virus produced as well as the percentage of cells infected. Vero cells showed no significant differences between either viral production or percentage of cells infected as compared to unsynchronized cells for any of the phases investigated, although production of virus (for both serotypes 2 and 3) was somewhat lower for cells infected during S phase. In contrast, HepG2 cells were significantly more permissive for both infection and virus production in the G2 phase as compared to other phases examined and serotype differences in permissiveness to infection were noted with cells in the M phase of the cell cycle. These results suggest that the cell cycle may be a mediator of cell permissiveness in some cell types. J. Med. Virol. 74:434–441, 2004. © 2004 Wiley‐Liss, Inc.
Dominant expression of interleukin‐10 and transforming growth factor‐β genes in activated T‐cells of chronic active epstein–barr virus infection
Authors: Ohga Shouichi , Nomura Akihiko , Takada Hidetoshi , Tanaka Tamami , Furuno Kenji , Takahata Yasushi , Kinukawa Naoko , Fukushima Noriyasu , Imai Shosuke , Hara Toshiro
Published: September 2004

Chronic active Epstein–Barr virus (EBV) infection is a chronic mononucleosis syndrome associated with clonal proliferation of EBV‐carrying T‐/natural killer (NK)‐cells. High levels of circulating EBV and activated T‐cells are sustained during the prolonged disease course, whereas it is not clear how ectopic EBV infection in T‐/NK‐cells has been established and maintained. To assess the biological role of activated T‐cells in chronic active EBV infection (CAEBV), EBV DNA and cellular gene expressions in peripheral T‐cells were quantified in CAEBV and infectious mononucleosis (IM) patients. In CAEBV, HLA‐DR+ T‐cells had higher viral load and larger amounts of IFNγ, IL‐10, transforming growth factor‐beta (TGFβ), and cytotoxic T lymphocyte antigen‐4 (CTLA4) mRNA than HLA‐DR−T‐cells. HLA‐DR+ T cells of IM patients transcribed more IFNγ and IL‐10 than their HLA‐DR−T cells. Expression levels of IFNγ and forkhead box p3 (Foxp3) in CAEBV HLA‐DR+ T‐cells were higher than in IM HLA‐DR+ T‐cells. The effective variables to discriminate the positivity of HLA‐DR were IL‐10, IFNγ, CTLA4, TGFβ, and IL‐2 in the order of statistical weight. EBV load in CAEBV T‐cells correlated with the expression levels of only IL‐10 and TGFβ. These results suggest that CAEBV T‐cells are activated to transcribe IFNγ, IL‐10, and TGFβ excessively, and the latter two genes are expressed preferentially in the EBV‐infected subsets. The dominant expression of regulatory cytokines in T‐cells may imply a viral evasion mechanism in the disease. J. Med. Virol. 74:449–458, 2004. © 2004 Wiley‐Liss, Inc.
Correlates of human herpes virus‐8 and herpes simplex virus type 2 infections in Northern Cameroon
Authors: Volpi A. , Sarmati L. , Suligoi B. , Montano M. , Rezza G. , Andreoni M.
Published: September 2004

The association between sexual activity and human herpes virus‐8 (HHV‐8) infection has been established, but the mode of acquisition is still unclear. Blood samples from 238 individuals from Northern Cameroon were tested to evaluate the incidence of herpes simplex virus‐2 (HSV‐2), human immunodeficiency virus (HIV), Treponema pallidum, and HHV‐8 infections and to identify their possible association. The presence of HSV‐2 antibodies was associated significantly with gender, age, and HIV, HHV‐8 antilatent, and T. pallidum antibodies, but not with HHV‐8 antilytic antibodies. In a multivariate model older age, female gender, seropositivity for HIV, for HHV‐8 latent antigens and for T. pallidum were associated independently with seropositivity for HSV‐2. HSV‐2‐seropositive individuals had significantly higher titers of antibodies to both lytic (P = 0.019) and latent (P = 0.021) HHV‐8 antigens. These results suggest that HSV‐2 infection can contribute to sexual transmission of HHV‐8 infection. J. Med. Virol. 74:467–472, 2004. © 2004 Wiley‐Liss, Inc.
Hydrophobic dipeptide Leu‐Ile protects against neuronal death by inducing brain‐derived neurotrophic factor and glial cell line‐derived neurotrophic factor synthesis
Authors: Nitta Atsumi , Nishioka Hirofumi , Fukumitsu Hidefumi , Furukawa Yoshiko , Sugiura Haruo , Shen Liya , Furukawa Shoei
Published: September 2004

We investigated whether certain hydrophobic dipeptides, Leu‐Ile, Leu‐Pro, and Pro‐Ile, which partially resemble the site on FK506 that binds to immunophilin, could stimulate glial cell line‐derived neurotrophic factor (GDNF) and brain‐derived neurotrophic factor (BDNF) synthesis in cultured neurons and found only Leu‐Ile to be an active dipeptide. Leu‐Ile protected against the death of mesencephalic neurons from wild‐type mice but not from mice lacking the BDNF or GDNF gene. Next, we examined the effects of i.p. or i.c.v. administration of Leu‐Ile on BDNF and GDNF contents. Both types of administration increased the contents of BDNF and GDNF in the striatum of mice. Also, peripheral administration of Leu‐Ile inhibited dopaminergic (DA) denervation caused by unilateral injection of 6‐hydroxydopamine (6‐OHDA) into the striatum of mice. The number of rotations following a methamphetamine challenge was lower in the Leu‐Ile‐treated group than in the nontreated group. Next, we compared the calcineurin activity and immunosuppressant activity of Leu‐Ile with those of FK506. Leu‐Ile was not inhibitory toward calcineurin cellular activity in cultured neuronal cells. Furthermore, Leu‐Ile did not suppress concanavalin A (ConA)‐induced synthesis/secretion of interleukin‐2 by cultured spleen cells, suggesting that the immunosuppressant activity of Leu‐Ile may be negligible when used as a therapeutic tool for neurodegenerative diseases. © 2004 Wiley‐Liss, Inc.
Maternal hypoxia during pregnancy induces fetal neurodevelopmental brain damage: Partial protection by magnesium sulfate
Authors: Golan H. , Kashtuzki I. , Hallak M. , Sorokin Y. , Huleihel M.
Published: September 2004

Fetal low brain oxygenation may be an outcome of maternal complications during pregnancy and is associated with increased risk of cerebral palsy and periventricular leukomalacia in newborns. One treatment used for prevention of fetal brain damage is maternal treatment with MgSO4. Although this treatment is indicated to reduce the risk of cerebral palsy in newborns, its use remains controversial. We have shown previously that pretreatment with MgSO4 in a mouse model of maternal hypoxia prevented a delay in the development of motor reflexes induced by hypoxia. We demonstrate here that pretreatment with MgSO4 reduces hypoxia‐induced motor disabilities in adult offspring. This effect is associated with histologic protection of the Purkinje cells in the cerebellum and stabilization of brain‐derived neurotrophic factor (BDNF) levels in the cerebellum. MgSO4 did not prevent the reduction in cerebral cortex cell density and cell size induced by maternal hypoxia, however, nor did it interfere with the modulation of BDNF and nerve growth factor (NGF) expression in the cerebral cortex. MgSO4 pretreatment also prevented the impairment of short‐term memory (30 min, P < 0.05) but not long‐term memory (7 days). Nevertheless, maternal pretreatment with MgSO4 reduced CA1 cell layer width and induced alterations in both NGF and BDNF in the hippocampus. These results support the prophylactic effect of MgSO4 against motor disabilities; however, they may also indicate possible harmful effects on the cerebral cortex and hippocampus. © 2004 Wiley‐Liss, Inc.
Re‐examination of the adsorption and reduction processes of thiosemicarbazide at a silver electrode: SERS, UV–visible and capillary electrophoresis studies
Authors: Andrade Gustavo F. S. , Micke Gustavo A. , Tavares Marina F. M. , Temperini Marcia L. A.
Published: September 2004

The faradaic reduction process of thiosemicarbazide (TSC) on a silver electrode in acidic solution was investigated using surface‐enhanced Raman scattering (SERS), UV–visible and capillary electrophoresis. No faradaic reduction product was detected, in disagreement with a previous SERS report. The TSC adsorption process on a silver electrode with different electrolyte anions in neutral solution was also studied by SERS and the change in the relative intensities of the TSC bands with the applied potential is explained based on variations in the TSC adsorbed conformations. Copyright © 2004 John Wiley & Sons, Ltd.
Differences in microbial activity of digesta from three sections of the porcine large intestine according to in vitro fermentation of carbohydrate‐rich substrates
Authors: Bauer Eva , Williams Barbara A , Bosch Marlou W , Voigt Christina , Mosenthin Rainer , Verstegen Martin WA
Published: September 2004

To determine whether faecal microorganisms can represent the entire large intestinal population, samples from caecum, mid‐colon and rectum of three adult pigs were used for the in vitro fermentation of fructo‐oligosaccharide (FOS), potato starch, wheat bran and oat hulls. The cumulative gas production technique measured fermentation kinetics and end‐products such as total gas, NH3 and volatile fatty acids (VFA). There were significant differences in the fermentability of substrates, in terms of both kinetics and end‐products. More relevant to this study, there were also differences between pigs in respect of total gas production, the rate of gas production (RM) and VFA production. For large intestine sections, there were more VFA from mid‐colon and rectal inocula compared with that from the caecum (p < 0.0001). Total gas, RM and NH3 were highest for rectal, intermediate for mid‐colon and lowest for caecal inocula (p < 0.0001). It was concluded that, while faecal sampling might overestimate caecal fermentation, its use is valid for in vitro assessment of large intestinal fermentation. However, differences between pigs indicate that a mix of samples from several animals remains important. Copyright © 2004 Society of Chemical Industry
Influence of enzymes on rheological, microstructure and quality characteristics of parotta—an unleavened Indian flat bread
Authors: Prabhasankar P , Indrani D , Jyotsna R , Venkateswara Rao G
Published: September 2004

Enzymes are used in the baking and milling industries to control dough properties and improve the quality of finished products. The role of enzymes in the baking process of an unleavened Indian flat bread, namely South Indian parotta, was studied. In this connection, comparisons have been made on the effects of different enzymes such as fungal α‐amylase (FA), glucose oxidase (GO), proteinase and xylanase on rheological characteristics and microstructure of parotta dough and its relation to the overall quality characteristics of baked parotta. Addition of GO increased, while FA, xylanase and proteinase decreased farinograph stability. Extensograph resistance to extension increased with GO or xylanase and decreased with FA or proteinase. The extensibility increased with FA, xylanase or proteinase and decreased with GO. The microstructure of parotta dough with different enzymes revealed that the use of proteinase improved the continuous gluten formation compared with the control and the other three enzymes, FA, xylanase and GO. This could be due to the proteinase enzyme breaking larger protein fibrils into smaller fibrils and thus enhancing the continuous gluten film formation. A similar observation was also noted in the microstructure of baked parotta layers. The microstructure of parotta with proteinase enzyme showed a continuous network of protein films compared with a cluster of protein films in parotta with GO. In the case of xylanase‐treated parotta, the starch granules were deformed completely and these deformed starch granules were found sticking to the protein films. In parottas prepared with GO and FA, only a few starch granules with faint outlines were visible. Generally speaking, the overall quality score of parotta decreased to 68 and 64 with the use of FA and, GO respectively, as against the control parotta score of 74. The score increased to 92 and 82 with the addition of proteinase and xylanase, respectively. Copyright © 2004 Society of Chemical Industry
The wet corrosion of molybdenum thin film – Part II: Behavior at 85°C
Authors: Tomachuk C. R. , De Rosa L. , Springer J. , Mitton D. B. , Saiello S. , Bellucci F.
Published: September 2004

In the past few years there has been increased interest in molybdenum thin films, which are commonly prepared by magnetron sputtering. There is a variety of novel applications of molybdenum such as, for example, components for soft X‐ray optics based on Mo/Si multi‐layers, the back contact in thin film solar cells, NO gas detection, and microelectronics. Molybdenum is, also, widely used as an alloying addition in stainless steels to facilitate the formation of the passive film and to improve resistance to pitting attack. Its corrosion behaviour is complex and many aspects still need to be clarified. During this study, the corrosion behaviour of the PVD‐Mo thin film immersed in aerated sulfate and chloride solutions at 85°C was investigated with both polarization and electrochemical impedance spectroscopy (EIS) measurements. It is apparent that the Mo thin film exhibits increased susceptibility to corrosion in more alkaline environments.
Role of tert‐Butyl Methyl Ether (TBME) as an External Donor in Propene Polymerization with Dibutyl Phthalate (DBP)‐Containing MgCl2‐Supported Ti Catalysts Activated with Al(i‐C4H9)3
Authors: Ohnishi Rikuo , Konakazawa Takehito
Published: September 2004

Summary: Stopped‐flow polymerization of propene was first conducted at 40 °C using the TiCl4/DBP/MgCl2 catalyst (DBP = dibutyl phthalate) combined with Al(C2H5)3. An induction period was observed at the beginning of polymerization, and the resulted polymer contained a considerable amount of the isolated ethylene unit. The formation of such unusual structures was concluded to be the result of copolymerization with ethylene originating from the ethylated Ti4+ species. Catalyst washing with toluene and stopped‐flow polymerization at 70 °C brought about a drastic decrease in the contents of both Ti and DBP as well as a disappearance of both the induction period and isolated ethylene unit. The microstructures of polymers revealed that the highly stereoregular polymers are produced at the initial stage of polymerization. Changes in yield and molecular weight of polymers with polymerization time showed that the addition of tert‐butyl methyl ether (TBME) brought about an increase in the concentration of active sites, but did not affect the propagation rate of propene polymerization. Such an increase in the active site concentration caused by an external donor has hardly been reported so far in kinetic studies using the stopped‐flow method; thus, the present result is believed to be a unique example.

Kinetic curves of propene polymerization with the Cat. IV‐Al(i‐C4H9)3 catalyst. (•): with TBME/Al = 0.1 and hydrogen, (♦): with TBME/Al = 0.1 and without hydrogen, (○): without TBME and with hydrogen, (⋄): without TBME and hydrogen.

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Kinetic curves of propene polymerization with the Cat. IV‐Al(i‐C4H9)3 catalyst. (•): with TBME/Al = 0.1 and hydrogen, (♦): with TBME/Al = 0.1 and without hydrogen, (○): without TBME and with hydrogen, (⋄): without TBME and hydrogen.
“Inorganic and Organometallic Clusters and Polymers: Syntheses and Applications” Symposium
Authors: Harvey Pierre D. , Abd‐El‐Aziz Alaa S.
Published: September 2004

Conference Reports: This section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.
Two applications of the curve lemma for orthogonal groups
Authors: Bruinier Jan Hendrik
Published: September 2004

We show (under some hypothesis in small dimensions) that the analytic degree of the divisor of a modular form on the orthogonal group O(2, p) is determined by its weight. Moreover, we prove that certain integrals, occurring in Arakelov intersection theory, associated with modular forms on O(2, p) converge. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Kreĭn's extension theory of nonnegative operators
Authors: Hassi Seppo , Malamud Mark , de Snoo Henk
Published: September 2004

In M. G. Kreĭn's extension theory of nonnegative operators a complete description is given of all nonnegative selfadjoint extensions of a densely defined nonnegative operator. This theory, the refinements to the theory due to T. Ando and K. Nishio, and its extension to the case of nondensely defined nonnegative operators is being presented in a unified way, building on the completion of nonnegative operator blocks. The completion of nonnegative operator blocks gives rise to a description of all selfadjoint contractive extensions of a symmetric (nonselfadjoint) contraction. This in turn is equivalent to a description of all nonnegative selfadjoint relation (multivalued operator) extensions of a nonnegative relation. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bound state solutions of the Dirac equation in the extreme Kerr geometry
Authors: Schmid Harald
Published: September 2004

In this paper we consider bound state solutions, i.e., normalizable time‐periodic solutions of the Dirac equation in an extreme Kerr black hole background with mass M and angular momentum J. It is shown that for each azimuthal quantum number k and for particular values of J the Dirac equation has a bound state solution, and that the energy of this Dirac particle is uniquely determined by $ \textstyle \omega = { {kM} \over {2J} } $. Moreover, we prove a necessary and sufficient condition for the existence of bound states in the extreme Kerr‐Newman geometry, and we give an explicit expression for the radial eigenfunctions in terms of Laguerre polynomials. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and Self‐Assembly of Styrene–[1]Dimethylsilaferrocenophane–Methyl Methacrylate Pentablock Copolymers
Authors: Datta Uttam , Rehahn Matthias
Published: September 2004

Summary:Well‐defined pentablock copolymers of styrene–[1]dimethylsilaferrocenophane–methyl methacrylate (PMMA‐b‐PFS‐b‐PS‐b‐PFS‐b‐PMMA) are synthesized using lithium naphthalide as initiator and a 1,1‐dimethylsilacyclobutane‐mediated 1,1‐diphenylethylene (DPE) end‐capping technique. Annealing under various conditions followed by analysis by transmission electron microscopy revealed good phase separation by the copolymers and the presence of ordered microstructures, such as spheres‐on/in‐spheres, and spheres‐on/in‐lamellae micromorphologies.

Structure of the styrene–[1]dimethylsilaferrocenophane–methyl methacrylate pentablock copolymers.

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Structure of the styrene–[1]dimethylsilaferrocenophane–methyl methacrylate pentablock copolymers.
Unique Insertion Mode of 1,7‐Octadiene in Copolymerization with Ethylene by a Constrained‐Geometry Catalyst
Authors: Naga Naofumi , Toyota Akinori
Published: September 2004

Summary: The copolymerization of ethylene and 1,7‐octadiene (OD) was investigated with a constrained‐geometry catalyst. The 13C NMR spectrum of the copolymer indicated cyclization insertion of the OD unit in the penultimate position after a single ethylene insertion step. This unique insertion mode of OD forms a 1,5‐disubstituted cyclononane unit in the main chain of polyethylene.

Copolymerization of ethylene and 1,7‐octadiene (OD) with a constrained‐geometry catalyst.

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Copolymerization of ethylene and 1,7‐octadiene (OD) with a constrained‐geometry catalyst.
Selectivity in Polystyryllithium Chain Coupling Induced by Monobromoalkane Additives
Authors: Ariura Fumi , Carlotti Stéphane , Deffieux Alain
Published: September 2004

Summary: The end coupling of living PSLi chains in hydrocarbon media by the addition of monoalkylbromides has been examined. A very selective PS–PS coupling reaction was obtained with neo‐pentylbromide (94%) at a ratio of PSLi/alkylbromide equal to 1 while the secondary and tertiary bromine derivatives yield only very limited coupling. The coupling mechanism is likely to involve a lithium‐bromine interchange at the PS chain end, generating polystyryl‐bromide which then reacts selectively with the remaining polystyryllithium chains.

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Cover Picture: Macromol. Rapid Commun. 17/2004
Authors: Tezuka Yasuyuki , Tsuchitani Akiko , Oike Hideaki
Published: September 2004

Cover: Polymeric topological isomers, theta‐shaped and manacle‐shaped polymers, have been synthesized from a polymer self‐assembly using a star telechelic poly(THF) having N‐phenylpyrrolidinium salt end groups carrying dicarboxylate counteranions. The two constitutional polymeric isomers were subsequently separated by means of a reversed‐phase liquid chromatography (RPC) technique. The picture shows that the theta‐ and manacle‐shaped polymers obtainable from linear and from star precursors are distinctive from each other with respect to the position of linking groups within their identical polymer framework, and it demonstrates the ability to place functional groups in specific locations in complex macromolecular topologies.

Further details can be found in the Communication by Y. Tezuka,* A. Tsuchitani, and H. Oike on page 1531.
Persistence Length of Cartilage Aggrecan Macromolecules Measured via Atomic Force Microscopy
Authors: Ng Laurel , Grodzinsky Alan J. , Sandy John , Plaas Anna , Ortiz Christine
Published: September 2004

Tapping mode atomic force microscopy (TMAFM) was employed to directly calculate the persistence length of individual fetal bovine epiphyseal and mature nasal cartilage aggrecan monomers, as well as their constituent chondroitin sulfate glycosaminoglycan chains.
Morphology and Micromechanical Behaviour of SBS Block Copolymer Systems
Authors: Adhikari R. , Godehardt R. , Lebek W. , Goerlitz S. , Michler G.H. , Knoll K.
Published: September 2004

By means of transmission electron microscopy (TEM) and uniaxial tensile testing, the connection between the morphology and the micromechanical properties of selected styrene‐rich styrene/butadiene block copolymers was studied with respect to their molecular architecture. In particular, the structure‐property correlation of a lamellae forming asymmetric linear SBS triblock copolymer was examined by systematically varying the sample preparation techniques and testing temperature. The molecular architecture was found to influence directly the morphology formation of the block copolymers. Different mechanisms such as drawing of the lamellae, shearing in the rubbery phase and rotation of the lamellar axis were observed. From room temperature down to the temperature close to glass transition temperature of the soft phase, a homogeneous plastic drawing of glassy lamellae was perceptible.
Conductive Composite Materials of Polyethylene and Polypyrrole with High Modulus and High Strength
Authors: Zhu Dan , Bin Yuezhen , Oishi Kumiko , Fukuda Yasuyuki , Nakaoki Takahiko , Matsuo Masaru
Published: September 2004

Composite films of polyethylene (PE) and polypyrrole (PPy) were prepared by polymerization of PPy on an ultradrawn polyethylene film with high modulus and high strength in ferric chloride (FeCl3) aqueous solution. The electrical conductivity of the composite film was found to be related to the polymerization conditions, such as polymerization temperature, polymerization time, the concentration and the oxidation potential of the FeCl3 solution. Scanning electron microscopy, FTIR and 13C NMR spectra were used to elucidate the morphological and structural variations of PPy prepared under different conditions, which lead to the differences in the electrical properties of the resultant composite films. The best electrical conductivity of the composite was about 5.5 S/cm for the film prepared under optimum conditions. The Young's modulus and the tensile strength reached 80 GPa and 3.2 GPa, respectively, which indicated the successful production of a conductive polymer with high strength and high modulus.
Failure Envelope Curves in Polyethylene Solids
Authors: Nitta Koh‐hei , Ishiburo Takashi
Published: September 2004

The present work demonstrates that the failure envelope analysis can be applied for characterizing the ultimate tensile properties of polyethylene solids in which the inhomogeneous necking process is avoided. As a result, the ultimate properties are essentially identical to those of vulcanized rubbers above the glass transition temperature, suggesting that tie molecules connecting the fragmented lamellar clusters transmit the external led to the fracture site in the same manner as cross‐linked rubbers do. Consideration of this crystal‐network model may provide information about the molecular processes that lead to rupture. Furthermore, the present analytical method can possibly be developed for predicting rupture times when different types of tests, such as constant drawn, constant stress and constant rate of stress, are conducted.
Side Chain Extension of Polypropylene by Aliphatic Diamine and Isocyanate
Authors: Kim K.Y. , Kim S.C.
Published: September 2004

A post‐reaction modification of polypropylene by which to obtain increased melt strength is by reactive extrusion of randomly functionalized PP with polyfunctional monomers. In this study, reactive melt processing of maleated polypropylene (PP‐g‐MA) with poly[methylene (phenylene isocyanate)] (PMPI), hexamethylene diamine (HMDA), and poly(propylene glycol)‐bis‐(2‐propylamine) (Jeffamine D‐400) was carried out. The resulting chain‐extended PP‐g‐MA was confirmed by FTIR analysis. Its thermal and rheological properties were also measured. HMDA and D‐400 react with both the carboxylic acid and anhydride form of MA. Though PMPI only reacts with the carboxylic acid of MA, PP‐g‐MA reacted with PMPI has higher gel content and storage modulus compared to PP‐g‐MA reacted with the amine. This is because of the higher functionality of PMPI and localized reaction between the isocyanate in PMPI and the carboxylic acid in PP‐g‐MA.
Morphology and Temperature Phase Transitions in α,ω‐Alkanediols with Different Chain Lengths
Authors: Marikhin Vyacheslav , Egorov Victor , Ivan'kova Elena , Myasnikova Liubov , Radovanova Elena , Volchek Boris , Medvedeva Darya , Jonas Alan
Published: September 2004

A comparative analysis of phase transitions in diols with various chain lengths [(CH2)44(OH)2 and (CH2)22(OH)2] and changes in their absorption spectra with temperature have been investigated by DSC and FTIR. Analysis of the DSC data has led to the conclusion that the low‐temperature phase transition of (CH2)22(OH)2 in a solid state (Ts‐s = 367.1 K) is a phase transition of the first order, while the high‐temperature phase transition (Tm = 376.3 K) is of the second order, i.e., a transition of the order‐disorder type. Splitting of the IR absorption bands into doublets at 720‐730 cm−1 and 1463‐1473 cm−1 indicates that crystalline subcells in the lamellae of both diols are orthorhombic lattices with the parameters typical of hydrocarbons. IR spectra showed that at the phase transition temperature Ts‐s transformation of an orthorhombic subcell into a hexagonal one occurs. This type of molecular chain packing remains the same up to the melting temperature Tm. In a (CH2)44(OH)2 diol, the ortho‐hexagonal subcell transition occurs only at the melting temperature (390.0 K). The wide IR band in the region from 3000 cm−1 to 3600 cm−1 shows that end hydroxyl groups of diol molecules form, on the surfaces of lamellar crystals, long (polymer) regular sequences consisting of intermolecular hydrogen bonds.
Visual kinesthesia and locomotion in Parkinson's disease
Authors: Schubert Martin , Prokop Thomas , Brocke Frank , Berger Wiltrud
Published: September 2004

We investigated predominance of visual control in Parkinson's disease (PD) gait regulation and whether visual kinesthesia has systematic effects on gait parameters. Effects of artificial optic flow were studied on walking velocity (WV), stride length (SL), and stride frequency (SF) during treadmill walking in PD patients and young and elderly adults. The independent variable was relative optic flow (rOF), ranging from −1 times (forward flow, i.e., in walking direction) to 3 times WV (backward flow, natural direction). All walkers were influenced similarly by rOF, inducing systematic changes of WV. Backward flow caused a decrease and forward flow an increase of WV. Without effect of rOF, PD patients on average walked at 0.89 meters per second compared to 1.31 meters per second in the age‐matched healthy group. The rOF‐induced mean changes of WV in all PD patients amounted to 0.45 meters per second (50.4%), with 45.1% due to changes in SL and 5.3% to SF. In the age‐matched, rOF‐induced WV changes reached 0.18 meters per second (13.8%), with 10.8% due to SL and 3.2% to SF. Thus, compared to the results of the age‐matched group, effects of rOF in PD patients were stronger, which increased WV to a normal level by normalization of SL. Contrary to the healthy subjects, no attenuation of optic flow effects over time was observed in the PD patients. Predominance of visual control in PD gait is suggested due to deficits in proprioception compensated by visual kinesthesia, causing exaggerated reaction to visual feedback. The results extend beyond earlier findings, generally stating improvement of PD gait by presence of visual feedback but show systematic effects on gait parameters due to reweighting of visual kinesthesia. © 2004 Movement Disorder Society
Non‐empirical calculations of NMR indirect carbon–carbon coupling constants. Part 10—Carbocages
Authors: Krivdin Leonid B.
Published: September 2004

A comprehensive theoretical study of nine classical caged polycycloalkanes (tetrahedrane, prismane, homoprismane, quadricyclane, cubane, pentaprismane, hexaprismane, adamantane and diamantane) was carried out with special focus on the structural behavior of their J(C,C) values calculated at the SOPPA level. The structural behavior of J(C,C) in small carbocages is dominated by steric strain whereas in medium‐sized polycycloalkanes the J(C,C) values show no marked peculiarities and follow several well‐defined structural trends typical of other alicyclic compounds. Copyright © 2004 John Wiley & Sons, Ltd.
Neuroepileptic correlates of autistic symptomatology in tuberous sclerosis
Authors: Bolton Patrick F.
Published: September 2004

Tuberous sclerosis is a genetic condition that is strongly associated with the development of an autism spectrum disorder. However, there is marked variability in expression, and only a subset of children with tuberous sclerosis develop autism spectrum disorder. Clarification of the mechanisms that underlie the association and variability in expression will potentially throw light on the biological processes involved in the etiology of idiopathic forms of autism spectrum disorder. Current evidence indicates that the likelihood of a child with tuberous sclerosis developing an autism spectrum disorder is greater if the child has a mutation in the TSC2 gene, although autism can and does develop in children with TSC1 mutations. The likelihood is also greater if the child has early‐onset infantile spasms that are difficult to control, especially if there is an epileptiform focus in the temporal lobes. The emerging evidence is consistent with the notion that early onset electrophysiological disturbances within the temporal lobes (and perhaps other locations) has a deleterious effect on the development and establishment of key social cognitive representations concerned with processing social information, perhaps especially from faces. However, alternative mechanisms to account for the findings cannot yet be ruled out. Future research will have to employ prospective longitudinal designs and treatment trials to clarify the processes involved. MRDD Research Reviews 2004;10:126–131. © 2004 Wiley‐Liss, Inc.
Landau–Kleffner syndrome, electrical status epilepticus in slow wave sleep, and language regression in children
Authors: McVicar Kathryn A. , Shinnar Shlomo
Published: September 2004

The Landau–Kleffner syndrome (LKS) and electrical status epilepticus in slow wave sleep (ESES) are rare childhood‐onset epileptic encephalopathies in which loss of language skills occurs in the context of an epileptiform EEG activated in sleep. Although in LKS the loss of function is limited to language, in ESES there is a wider spectrum of cognitive impairment. The two syndromes are distinct but have some overlap. The relationship between the epileptiform EEG abnormalities and the loss of cognitive function remains controversial, even in LKS which is the most widely accepted as an acquired epileptic aphasia. Language regression also occurs in younger children, frequently in the context of a more global autistic regression. Many of these children have epileptiform EEGs. The term autistic regression with epileptiform EEG has been proposed for these children. Whether these children are part of an extended LKS spectrum is very controversial, because there are differences in age of onset, clinical phenotype, and EEG findings. An understanding of the available data on clinical characteristics, EEG findings, pathology, prognosis, and treatment of these syndromes is essential for further progress in this area. MRDD Research Reviews 2004;10:144–149. © 2004 Wiley‐Liss, Inc.
Detrusor overactivity in spina bifida: How long does it need to be treated?
Authors: AB Elisabeth , Dik Pieter , Klijn Aart J. , van Gool Jan D. , de Jong Tom P.V.M.
Published: September 2004

Aims

To determine whether a lasting therapeutic effect can be expected from long‐term antimuscarinic therapy for neurogenic detrusor overactivity in spina bifida and to answer the question whether detrusor overactivity in spina bifida children with detrusor/sphincter dyssynergia is primarily based on the neuropathy or, in part, can be a secondary detrusor reaction to the functional urethral obstruction.

Methods

Fifteen spina bifida patients, aged between 1 and 12 years, all on a regime of clean intermittent catheterisation (CIC) and oxybutynin since shortly after birth, underwent three consecutive urodynamic studies (UDS). One prestudy UDS for treatment control, one UDS after withdrawal of oxybutynin for 3–5 days and one UDS after reinstallment of oxybutynin treatment. Urodynamic results were compared concerning detrusor overactivity, cystometric bladder capacity, and compliance.

Results

Detrusor overactivity was seen in two patients on the prestudy UDS. After several days of withdrawal of oxybutynin overactivity was seen in 11 patients. After oxybutynin withdrawal, bladder compliance was within safe margins for two patients only, after reinstallment, safe vesical pressures were seen in 11 patients.

Conclusion

The functional obstruction due to detrusor/sphincter dyssynergia has been by‐passed chronically in all these children by CIC and oxybutynin. Due to the fact that detrusor overactivity recurs immediately after withdrawal of medication after long‐term treatment with oxybutynin, one can conclude that there is no long‐lasting therapeutic effect of pharmacological suppression. This suggests that in children with detrusor/sphincter dyssynergia, detrusor overactivity is primarily of neuropathic origin. © 2004 Wiley‐Liss, Inc.
Functional imaging of the human trigeminal system: Opportunities for new insights into pain processing in health and disease
Authors: Borsook David , Burstein Rami , Becerra Lino
Published: September 2004

Peripheral inflammation or nerve damage result in changes in nervous system function, and may be a source of chronic pain. A number of animal studies have indicated that central neural plasticity, including sensitization of neurons within the spinal cord and brain, is part of the response to nervous system insult, and can result in the appearance of altered sensation, including pain. It cannot be assumed, however, that data obtained from animal models unambiguously reflects CNS changes that occur in humans. Currently, the only noninvasive approach to determining objective changes in neural processing and responsiveness within the CNS in humans is the use of functional imaging techniques. It is now possible to use functional magnetic resonance imaging (fMRI) to measure CNS activation in the trigeminal ganglion, spinal trigeminal nucleus, the thalamus, and the somatosensory cortex in healthy volunteers, in a surrogate model of hyperalgesia, and in patients with trigeminal pain. By offering a window into the temporal and functional changes that occur in the damaged nervous system in humans, fMRI can provide both insight into the mechanisms of normal and pathological pain and, potentially, an objective method for measuring altered sensation. These advances are likely to contribute greatly to the diagnosis and treatment of clinical pain conditions affecting the trigeminal system (e.g., neuropathic pain, migraine). © 2004 Wiley Periodicals, Inc. J Neurobiol 61: 107–125, 2004
Applications of numerical eigenfunctions in the fractal‐like finite element method
Authors: Tsang D. K. L. , Oyadiji S. O. , Leung A. Y. T.
Published: September 2004

The fractal‐like finite element method is an accurate and efficient method to determine the stress intensity factors (SIF) around crack tips. The use of a self‐similar mesh together with the William's eigenfunctions reduce the number of unknowns significantly. The SIFs are the primary unknowns and no post‐processing is required. In all previous studies, we used the analytic eigenfunction expression to perform the global transformation. However, the eigenfunction cannot be found analytically in general crack problems. Two‐dimensional axisymmetrical cracks are considered here. The resulting static equilibrium equations in local co‐ordinates are non‐homogeneous ordinary differential equations, for which the analytic eigenfunction cannot be found completely. We use a finite difference method to determine all the eigenfunctions needed numerically. Our evaluated SIF values show very close agreement with published results. Copyright © 2004 John Wiley & Sons, Ltd.
Error estimation for geometrically non‐linear analysis of framed structures
Authors: Izzuddin B. A. , Chew A. , Smith D. Lloyd
Published: September 2004

This paper is concerned with the estimation of errors that arise in the geometrically non‐linear analysis of framed structures using 1D beam‐column finite elements. A quartic element is used to illustrate specific issues of error estimation relating to geometrically non‐linear analysis, this element exhibiting most of the sources of error that arise with other 1D elements. After a brief description of the quartic element, the sources of error that it manifests in geometrically non‐linear analysis are highlighted. The first source of error is due to equilibrium defaults, including contributions from finite element discretization and from the approximation of equivalent loads, whereas the second source of error is due to compatibility defaults. Next, a stress recovery method, termed the ‘Exact equilibrium recovery’ (EER) method, is proposed for the estimation of equilibrium errors due to finite element discretization. This method, specifically developed for framed structures, is element based and is shown to be more effective than other patch‐based recovery methods. An overall error estimation method is then proposed, providing separate yet combinable measures for equilibrium and compatibility errors. Finally, several examples are presented to demonstrate the effectiveness of the proposed error estimation method in the geometrically non‐linear analysis of framed structures, illustrating also the relative importance of the various sources of error that are manifested in typical problems. Copyright © 2004 John Wiley & Sons, Ltd.
Small organization mergers in arts and humanities
Authors: Toepler Stefan , Seitchek Cara , Cameron Theresa
Published: September 2004

This chapter discusses a case study of the merger between two relatively small organizations: a local nonprofit arts council and a public county‐level humanities commission. As this case deviates from other merger analyses that tend to focus on larger health and social service agencies, the chapter examines how well key findings of the nonprofit merger literature apply to mergers of organizations of smaller size and in other fields. Generally, we find that the merger literature so far provides sufficient guidance for nonprofit managers in fields such as the arts, where merger pressures have only now begun to mount.
Fetal cells in maternal plasma are found in a late state of apoptosis
Authors: Kolialexi Aggeliki , Tsangaris George Th , Antsaklis Aris , Mavrou Ariadni
Published: September 2004

Objective

The present study was designed to give possible answers to some of the discrepancies regarding the presence or not of intact fetal cells in maternal plasma during pregnancy.

Materials and Methods

12‐mL peripheral blood was collected from 33 pregnant women in the second trimester: 6 mL was harvested by 3‐step Percoll gradient centrifugation and plasma cells were analyzed by FISH with X/Y chromosome specific probes. From the remaining 6 mL, plasma‐derived cells were isolated with three different gradient centrifugation protocols and apoptosis was determined following EthBr staining.

Results

The number of cells recovered ranged from 900 to 3000. At least one Y positive signal was seen in 12 out of 17 cases with male fetuses at a frequency of 0.12% (range 0.05–0.27%). No XY cells were detected in the plasma of women carrying female fetuses. Hybridization efficiency was <60%. EthBr staining demonstrated that the majority of these cells were in their late apoptosis.

Conclusion

Our findings confirm the presence of intact fetal apoptotic cells in maternal plasma; however, their late apoptotic state and the low number does not as yet encourage their use in clinical practice. Copyright © 2004 John Wiley & Sons, Ltd.