bluuebunny/crossref_metadata_2025 huggingface dataset:
Melt spinning and drawing of 2‐methyl‐1,3‐propanediol‐substituted poly(ethylene terephthalate)
Authors: Suh Jaein , Spruiell J. E. , Schwartz Steven A.
Published: March 2003

The structure and properties of fibers prepared from copolymers of poly(ethylene terephthalate) (PET) in which 2‐methyl‐1,3‐propanediol (MPDiol® Glycol is a registered trademark of Lyondell Chemical Company) at 4, 7, 10, and 25 mol% was substituted for ethylene glycol were studied and compared with those of PET homopolymer. Filaments were melt spun over a range of spinning conditions, and some filaments that were spun at relatively low spinning speeds were subjected to hot drawing. The filaments were characterized by measurements of birefringence, differential scanning calorimetry (DSC) crystallinity, melting point, glass transition temperature, wide‐angle X‐ray diffraction patterns, boiling water shrinkage, tenacity, and elongation to break. Filaments containing 25 mol% MPDiol did not crystallize in the spinline at any spinning speed investigated, whereas the other resins did crystallize in the spinline at high spinning speeds. However, compared with PET homopolymer, increasing substitution of MPDiol reduced the rate at which the crystallinity of the melt spun filaments increased with spinning speed and reduced the ultimate crystallinity that could be achieved by high‐speed spinning. The rate of development of molecular orientation, as measured by birefringence, also decreased somewhat with increasing MPDiol content. Shrinkage in boiling water decreased at high spinning speeds as the amount of crystallinity increased; however, the shrinkage decreased more slowly with increase in spinning speed as MPDiol content increased. Tenacity also decreased slightly at any given spinning speed as MPDiol content increased, but there was no significant effect on elongation to break. The addition of MPDiol in amounts up to 7 mol% increased the maximum take‐up velocity that could be achieved at a given mass throughput. This result indicates that the use of higher spinning speeds could potentially increase the productivity of melt spun yarns. Copolymer filaments spun at low speeds were readily drawn to produce highly oriented fibers with slightly less birefringence, crystallinity, and tenacity than similarly processed PET homopolymer. Preliminary dyeing experiments showed that the incorporation of MPDiol improved the dyeability of the filaments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2598–2606, 2003
Removal properties of crosslinked poly(2‐acrylamido glycolic acid) for trace heavy metal ions: Effect of pH, temperature, contact time, and salinity on the adsorption behavior
Authors: Rivas Bernabé L. , Quilodrán Benita , Quiroz Eduardo
Published: March 2003

Crosslinked poly(2‐acrylamido glycolic acid) resin was synthesized by radical polymerization. This resin contains three potential ligand groups and was studied as an adsorbent of trace heavy metal ions from a saline aqueous solution and sea water by using the Batch equilibrium procedure. Adsorption characteristics of the resin toward Cu(II), Ni(II), Cd(II), and Pb(II) were studied spectrophotometrically, both in competitive and noncompetitive conditions. The effect of pH, contact time, amount of sorbent, temperature, and salinity were studied. The resin showed a high affinity particularly for Ni(II). It was possible to remove completely Ni(II) and Pb(II) from the resin by 4M HNO3. The retention properties of the resin were also investigated for Cu(II) contained in natural sea waters. The retention behavior was similar to that of the synthetic metal ion aqueous solution. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2614–2621, 2003
Evaluation of isocyanate functional groups as a reactive group in the reactive compatibilizer
Authors: Jung Woo‐Chul , Park Kang‐Yeol , Kim Ju‐Young , Suh Kyung‐Do
Published: March 2003

Reactive compatibilization of an isocyanate (NCO) functional group as a reactive group was investigated. Five kinds of reactive polymers were prepared through solution graft polymerization of low‐density polyethylene (LDPE) copolymerized with acrylic acid (AA), maleic anhydride (MAH), glycidyl methacrylate (GMA), and masked and naked NCO functional monomers and were used as compatibilizers in poly(ethylene terephthalate) (PET)/LDPE and polyamide 6 (Nylon 6)/LDPE blends. The reactivity of the NCO functional group in the reactive blend was evaluated in terms of the blend morphology, adhesive test, mechanical properties, and rheological properties. It was found that GMA and NCO groups were the most effective compatibilizing agents in the PET/LDPE blends and MAH and NCO groups showed effective compatibilization of the Nylon 6/LDPE blends. We confirmed that the NCO functional group as a reactive group could be used as a universal reactive compatibilizer for PET/LDPE and Nylon 6/LDPE blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2622–2629, 2003
Effects of the presence of water on ultrasonic devulcanization of polydimethylsiloxane
Authors: Shim Sang Eun , Isayev A. I.
Published: March 2003

The effects of the presence of water on ultrasonic devulcanization of 30 phr silica‐filled polydimethylsiloxane (PMDS) were investigated at increasing feed rates and different die gap sizes. The results showed that the initial die entrance pressure without ultrasound for wet rubber was higher than in the case without water and then it decreased monotonously with applying ultrasound. The die pressure for wet rubber decreased significantly even at low ultrasonic amplitude, while that for dry rubber changed little at low amplitude. The power consumption at an amplitude of 10 μm, where devulcanization was most effectively achieved, was lower for wet rubber even though the pressure was lower. The crosslink density and gel fraction after the devulcanization of wet rubber were lower than those of dry rubber, indicating that the presence of water facilitates the devulcanization process under the same devulcanization conditions. The good mechanical properties of recycled silica‐filled PDMS were obtained at higher feed rates and at lower ultrasound amplitudes, which are directly related to the economics of a recycling process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2630–2638, 2003
Thermoplastic hydrogel based on pentablock copolymer consisting of poly(γ‐benzyl L‐glutamate) and poloxamer
Authors: Oh Sang‐Bong , Choi Yong‐Kook , Cho Chong‐Su
Published: March 2003

A thermoplastic hydrogel based on a pentablock copolymer composed of poly(γ‐benzyl L‐glutamate) (PBLG) and poloxamer was synthesized by polymerization of BLG N‐carboxyanhydride, which was initiated by diamine‐terminated groups located at the ends of poly(ethylene oxide) (PEO) chains of the poloxamer, to attain a new pH‐ and temperature‐sensitive hydrogel for drug delivery systems. Circular dichroism measurements in solution and IR measurements in the solid state revealed that the polypeptide block existed in the α‐helical conformation, as in the PBLG homopolymer. The intensity of the wide‐angle X‐ray diffraction patterns of the polymers depended on the poloxamer content in the copolymer and showed basically similar reflections to the PBLG homopolymer. The melting temperature (Tm) of the poloxamer in the copolymer was reduced with an increase of the PBLG block in comparison with the Tm of the poloxamer, which is indicative of a thermoplastic property. The water contents of the copolymers were dependent on the poloxamer content in the copolymers, for example, those for the GPG‐2 (48.7 mol % poloxamer) and GPG‐1 (57.5 mol % poloxamer) copolymers were 31 and 41 wt %, respectively, indicating characteristics of a polymeric hydrogel. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2649–2656, 2003
Dynamic vulcanization of acrylic rubber‐blended PVC
Authors: Wong‐On Jessada , Wootthikanokkhan Jatuphorn
Published: March 2003

Poly(vinyl chloride) was blended with an acrylic rubber at a variety of blending ratio using a twin‐screw extruder. The acrylic rubber was compounded with sulfur and sodium stearate in a two‐roll mill prior to the blending. Dynamic vulcanization was performed in a compression mould at 170°C. Mechanical properties of the blends were determined by using a tensile testing machine. Scanning electron microscope was used to examine morphology of these blends. Degree of crosslinking of acrylic rubber in the blends was evaluated by using a differential scanning calorimeter. It was found that the normal blends are miscible regardless of the blending variables. By performing dynamic vulcanization, however, the blends became immisicible, showing a typical dispersed particle morphology, which was accompanied by a remarkable improvement of tensile properties. The screw‐rotating speed was an important parameter affecting particle size and crosslink density of the rubber phase, which in turn controlled the tensile toughness of the blends. On the one hand, tensile toughness increased with the speed because of the decreasing particle size. On the other hand, the toughness decreased with the speed because of the decreasing crosslink density of the rubber. As a result, there was an optimum speed for each blend ratio, which corresponded to the maximum toughness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2657–2663, 2003
Structure and applications of CB/crystal fluoride resin alloy in self‐regulated heating cables
Authors: Wang Jikui , Guo Weihong , Cheng Shujun , Zhang Zhiping
Published: March 2003

A conductive composite was prepared by blending carbon black with a modified crystal fluoride resin alloy. The formulation and the processing technology were optimized, and the positive‐temperature‐coefficient (PTC) characteristics under different conditions were studied by SEM, WAXD, and DSC. Relationships between the properties and the structures are illustrated, and applications of this composite in high‐grade temperature self‐regulating heating cables (135°C) are suggested. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2664–2669, 2003
Study of free‐radical copolymerization of N‐isopropylacrylamide with 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid
Authors: Zhang Chi , Easteal Allan J.
Published: March 2003

The free‐radical copolymerization of N‐isopropylacrylamide and 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid at varying comonomer mole ratios was studied at 70°C. The extent of conversion was determined as a function of time and comonomer mixture composition, and copolymer compositions were determined using elemental analysis and 13C NMR spectroscopy. Monomer reactivity ratios were evaluated for low conversions using Kelen‐Tüdos and Fineman‐Ross methods. The copolymers were characterized using 13C and 1H NMR spectra, FTIR spectroscopy, and differential scanning calorimetry. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2563–2569, 2003
Preparation and adsorption properties for metal ions of chitin modified by L‐cysteine
Authors: Shao Jian , Yang Yumin , Shi Chuanguo
Published: March 2003

A new adsorbent for heavy metal ions, cys‐chitin, was produced by modifying chitin in THF with L‐cysteine in the presence of sulfuric acid as a catalyst. Its structure was confirmed by elemental analysis and FTIR spectra analysis. The adsorption properties of cys‐chitin for CuII, CdII, PbII, ZnII, and NiII were investigated. The effect of pH value on adsorption and adsorption kinetics was examined. The results indicate that the cys‐chitin has much better adsorption for CdII, PbII, and ZnII than chitin itself. The adsorption capacities of cys‐chitin for CdII, PbII, and ZnII were 214.6, 351.5, and 107.0 mg/g, respectively. It also had good adsorption properties for heavy metal ions. The adsorption capacities were also affected by the acidity of medium. The adsorbed CdII, PbII could be eluted by diluted nitric acid. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2575–2579, 2003
Blends of SBS triblock copolymer with poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polystyrene mixture
Authors: Picchioni Francesco , Casentini Emanuele , Passaglia Elisa , Ruggeri Giacomo
Published: March 2003

Blends of styrene–butadiene–styrene (SBS) or styrene–ethylene/1‐butene–styrene (SEBS) triblock copolymers with a commercial mixture of polystyrene (PS) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were prepared in the melt at different temperatures according to the chemical kind of the copolymer. Although solution‐cast SBS/PPO and SBS/PS blends were already known in the literature, a general and systematic study of the miscibility of the PS/PPO blend with a styrene‐based triblock copolymer in the melt was still missing. The thermal and mechanical behavior of SBS/(PPO/PS) blends was investigated by means of DSC and dynamic thermomechanical analysis (DMTA). The results were then compared to analogous SEBS/(PPO/PS) blends, for which the presence of a saturated olefinic block allowed processing at higher temperatures (220°C instead of 180°C). All the blends were further characterized by SEM and TGA to tentatively relate the observed properties with the blends' morphology and degradation temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2698–2705, 2003
Optical properties of injection‐molded polystyrene scintillators. II. Distribution of dopants
Authors: Martins J. A. , Seixas J. , Oliveira M. J. , Maio A. , Pouzada A. S.
Published: March 2003

The distribution of fluorescing dye solutes in scintillating tiles for the Tilecal/Atlas project is assessed, and a link between the homogeneity of the dopant distribution and the optical yield and nonuniformity is established. The effect of the injection‐molding parameters on the dye distribution is also analyzed, as well as the actual dye incorporation into the scintillators. This incorporation has been assessed with a set of experiments performed with laboratory samples with controlled amounts of additives and with samples obtained from injection‐molded scintillators. Differential scanning calorimetry has been used to characterize the raw material and to establish a link between the thermophysical properties and the processing conditions, and it is proven to be a quite appropriate technique. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2714–2718, 2003
Low power millimeter wave irradiation exerts no harmful effect on human keratinocytes in vitro
Authors: Szabo Imre , Manning Michael R. , Radzievsky Alexander A. , Wetzel Michele A. , Rogers Thomas J. , Ziskin Marvin C.
Published: March 2003

Low power millimeter wave (LP‐MW) irradiation has been successfully used in clinical practice as an independent and/or supplemental therapy in patients with various diseases. It is still not clear, however, whether exposed skin is directly affected by repeated LP‐MW irradiation and whether cells of the epidermis can be activated by the absorbed energy. Keratinocytes, the most numerous component of the epidermis are believed to manifest functional responses to physical stimuli. In this study we analyzed whether LP‐MW irradiation modulated the production of chemokines, including RANTES and IP‐10 of keratinocytes in vitro. We also investigated whether LP‐MW irradiation induces a heat stress reaction in keratinocytes, and stimulates heat shock protein 70 (Hsp70) production. Vital staining of keratinocytes with carboxyfluorescein succinimidyl ester and ethidium bromide was used to analyze the MW effect on the viability of adherent cells. In addition, we studied the effect of LP‐MW irradiation on intercellular gap junctional communication in keratinocyte monolayers by Lucifer yellow dye transfer. We found no significant changes in constitutive RANTES and inducible IP‐10 production following LP‐MW irradiation. LP‐MW exposure of keratinocyte monolayers did not alter Hsp70 production, unlike exposure to higher power MWs (HP‐MW) or hyperthermia (43 °C; 1 h). LP‐MW irradiation and hyperthermia did not alter the viability of adherent keratinocytes, while HP‐MW irradiation induced cellular damage within the beam area. Finally, we found no alteration in the gap junctional intercellular communication of keratinocytes following LP‐MW irradiation, which on the other hand, was significantly increased by hyperthermia. In summary, we detected no harmful effect of LP‐MW irradiation on both keratinocyte function and structure in vitro, although these cells were sensitive to higher MW power that developed heat stress reaction and cellular damage. Our results provide further evidence that LP‐MW irradiation does not induce evidence of skin inflammation or keratinocyte damage and that its clinical application appears to be safe. Bioelectromagnetics 24:165–173, 2003. © 2003 Wiley‐Liss, Inc.
Development of a dielectric equivalent gel for better impedance matching for human skin
Authors: Sunaga Takahiro , Ikehira Hiroo , Furukawa Shigeo , Tamura Mitsuru , Yoshitome Eiji , Obata Takayuki , Shinkai Hiroshi , Tanada Shuji , Murata Hajime , Sasaki Yasuhito
Published: March 2003

It would be useful to develop a tissue equivalent gel to improve the uniformity of the electromagnetic field in the human body, and for making a tissue equivalent dielectric human phantom. In this study, solid type, water based gelatin‐honey gels were developed which have the electrical characteristics of skin tissue. It was demonstrated that a stable and homogeneous gel, with a relative dielectric constant ε′ chosen from desired ranges found in skin, can be made for 200–400 MHz. Bioelectromagnetics 24:214–217, 2003. © 2003 Wiley‐Liss, Inc.
Effects of GSM‐900 microwaves on the experimental allergic encephalomyelitis (EAE) rat model of multiple sclerosis
Authors: Anane R. , Geffard M. , Taxile M. , Bodet D. , Billaudel B. , Dulou P.E. , Veyret B.
Published: March 2003

The effects of acute exposure to GSM‐900 microwaves (900 MHz, 217 Hz pulse modulation) on the clinical parameters of the acute experimental allergic encephalomyelitis (EAE) model in rats were investigated in two independent experiments: rats were either habituated or nonhabituated to the exposure restrainers. EAE was induced with a mixture of myelin basic protein and Mycobacterium tuberculosis. Female Lewis rats were divided into cage control, sham exposed, and two groups exposed either at 1.5 or 6.0 W/kg local specific absorption rate (SAR averaged over the brain) using a loop antenna placed over their heads. There was no effect of a 21 day exposure (2 h/day) on the onset, duration, and termination of the EAE crisis. Bioelectromagnetics 24:211–213, 2003. © 2003 Wiley‐Liss, Inc.
Extremely low frequency magnetic field exposure modulates the diurnal rhythm of the pain threshold in mice
Authors: Choi Yoon Mee , Jeong Ji Hoon , Kim Jeong Soo , Lee Byung‐Cheon , Je Hyun Dong , Sohn Uy Dong
Published: March 2003

The aim of this study was to determine whether exposure to extremely low frequency magnetic field (ELF‐MF) affects the normal diurnal rhythm of the pain threshold in mice. Pain thresholds were evaluated in mice using the hot plate test. A significant increase of pain threshold during night was observed compared to that during day. This rhythm was attenuated by both constant exposure to light (LL) and constant exposure to darkness (DD) for 5 days. Under DD exposure, the diurnal rhythm in pain threshold was restored when mice were exposed to ELF‐MF (60 Hz, 1.5 mT for 12 h daily, from 08:00 to 20:00 h) for 5 days. The diurnal rhythm was not reversed under dark with reversed ELF‐MF cycle (exposure to 1.5 mT from 20:00 to 08:00 h, next day) for 5 days, although pain threshold in the ELF‐MF exposed period of night was slightly decreased. The diurnal rhythm of melatonin analgesic effect related to pain threshold was also observed under DD by the exposure of ELF‐MF for 5 days, but not for 5 nights. The present results suggest that ELF‐MF may participate in the diurnal rhythm of pain threshold by acting on the system that is associated with environmental light‐dark cycle. Bioelectromagnetics 24:206–210, 2003. © 2003 Wiley‐Liss, Inc.
Subjective symptoms among mobile phone users—A consequence of absorption of radiofrequency fields?
Authors: Wilén Jonna , Sandström Monica , Hansson Mild Kjell
Published: March 2003

In a previous epidemiological study, where we studied the prevalence of subjective symptoms among mobile phone (MP) users, we found as an interesting side finding that the prevalence of many of the subjective symptoms increased with increasing calling time and number of calls per day. In this extrapolative study, we have selected 2402 people from the epidemiological study who used any of the four most common GSM MP. We used the information about the prevalence of symptoms, calling time per day, and number of calls per day and combined it with measurements of the Specific Absorption Rate (SAR). We defined three volumes in the head and measured the maximum SAR averaged over a cube of 1 g tissue (SAR1g) in each volume. Two new exposure parameters Specific Absorption per Day (SAD) and Specific Absorption per Call (SAC) have been devised and are obtained as combinations of SAR, calling time per day, and number of calls per day, respectively. The results indicates that SAR values >0.5 W/kg may be an important factor for the prevalence of some of the symptoms, especially in combination with long calling times per day. Bioelectromagnetics 24:152–159, 2003. © 2003 Wiley‐Liss, Inc.
Structures and interactions of the core histone tail domains
Authors: Zheng Chunyang , Hayes Jeffrey J.
Published: March 2003

The core histone tail domains are “master control switches” that help define the structural and functional characteristics of chromatin at many levels. The tails modulate DNA accessibility within the nucleosome, are essential for stable folding of oligonucleosome arrays into condensed chromatin fibers, and are important for fiber–fiber interactions involved in higher order structures. Many nuclear signaling pathways impinge upon the tail domains, resulting in posttranslational modifications that are likely to alter the charge, structure, and/or interactions of the core histone tails or to serve as targets for the binding of ancillary proteins or other enzymatic functions. However, currently we have only a marginal understanding of the molecular details of core histone tail conformations and contacts. Here we review data related to the structures and interactions of the core histone tail domains and how these domains and posttranslational modifications therein may define the structure and function of chromatin. © 2003 Wiley Periodicals, Inc. Biopolymers 68: 539–546, 2003
Quantitative characterization of specific genomic promoters using agarose gel electrophoresis
Authors: Georgel Philippe T. , Hansen Jeffrey C.
Published: March 2003

Over the past decade a large number of studies have focused attention on the role of nucleosomes as negative and positive regulators of specific nuclear functions. Due to the lack of an analytical method to determine the higher order conformation of the nucleosomal arrays that encompass specific genetic loci (e.g., promoters, enhancers), research emphasis has mostly been centered on chromatin remodeling and histone posttranslational modifications. We have recently developed an agarose gel electrophoresis method that permits us to analyze the higher order structure of specific in vivo assembled chromatin fragments. After calibration using a well‐defined in vitro system, we have been able to experimentally determine the size, shape, and conformational flexibility of the Mouse Mammary Tumor Virus long‐terminal repeat promoter region in its repressed and activated states. These studies pave the way for widespread analyses of the higher order structure of specific, functionally important chromosomal loci, and in so doing enhance our understanding of the roles that the higher order structure of chromatin play in genome regulations. © 2003 Wiley Periodicals, Inc. Biopolymers 68: 557–562, 2003
Molecular dynamics simulations of A · T‐rich oligomers: Sequence‐specific binding of Na+ in the minor groove of B‐DNA
Authors: Mocci Francesca , Saba Giuseppe
Published: March 2003

Molecular dynamics simulations have been employed to probe the sequence‐specific binding of sodium ions to the minor groove of B‐DNA of three A · T‐rich oligomers having identical compositions but different orders of the base pairs: C(AT)4G, CA4T4G, and CT4A4G.

Recent experimental investigations, either in crystals or in solution, have shown that monovalent cations bind to DNA in a sequence‐specific mode, preferentially in the narrow minor groove regions of uninterrupted sequences of four or more adenines (A‐tracts), replacing a water molecule of the ordered hydration structure, the hydration spine.

Following this evidence, it has been hypothesized that in A‐tracts these events may be responsible for structural peculiarities such as a narrow minor groove and a curvature of the helix axis.

The present simulations confirm a sequence specificity of the binding of sodium ions: Na+ intrusions in the first layer of hydration of the minor groove, with long residence times, up to ∼3 ns, are observed only in the minor groove of A‐tracts but not in the alternating sequence. The effects of these intrusions on the structure of DNA depend on the ion coordination: when the ion replaces a water molecule of the spine, the minor groove becomes narrower. Ion intrusions may also disrupt the hydration spine modifying the oligomer structure to a large extent. However, in no case intrusions were observed to locally bend the axis toward the minor groove. The simulations also show that ions may reside for long time periods in the second layer of hydration, particularly in the wider regions of the groove, often leading to an opening of the groove. © 2003 Wiley Periodicals, Inc. Biopolymers 68: 471–485, 2003
1H‐NMR studies on a potent and selective antagonist at human melanocortin receptor 4 (hMC‐4R)
Authors: Victoria Silva Elipe Maria , Mosley Ralph T. , Bednarek Maria A. , Arison Byron H.
Published: March 2003

Melanocortin receptor 4 (MC‐4R) is involved in the regulation of energy balance and body weight, and recognizes α‐, β‐, and γ‐melanocyte stimulating hormones (α‐, β‐, γ‐MSH). In the search for compounds that regulate food intake and body weight, two synthetic lactam‐derivative ligands of α‐MSH were discovered, MTII and SHU9119. MTII is an agonist and reduces food intake in rats, whereas SHU9119 is an antagonist, and increases food intake and body weight in rats. MTII and SHU9119 are nonselective compounds to MC‐4R. To enhance the potency and selectivity at the human MC‐4R (hMC‐4R), we recently synthesized analogs of SHU9119 (M. A. Bednarek, T. MacNeil, R. N. Kalyani, R. Tang, Van der L. H. T. Ploeg, and D. H. Weinberg, Journal of Medicinal Chemistry, 2001, Vol. 44, pp. 401–409), wherein compound 1 was the most selective for hMC‐4R. Replacement of D‐Nal by L‐Nal in compound 1 made compound 2 weakly active. Comparison of the structures by NMR and molecular modeling of compounds 1 and 2 vs SHU9119 and MTII indicated that, even though they existed as an average of several conformations in solution, there were distinctions in their structures. The γ‐methylene protons of Arg in compound 1 were nonequivalent and shielded probably by the aromatic ring of Nal. The NHi–NHi+1 NOE cross peaks and the temperature coefficients of the amide protons around the “essential core” Nal/Phe7–Arg8–Trp9, required for high affinity and high selectivity at hMC‐4R, were indicative of a possible turn structure for these compounds but with differences in their NOE strengths and temperature coefficient values. Molecular modeling of these compounds based on their NMR data showed that the essential core appeared as a “V” shape with two different orientations, one for compound 1 and some of the conformers of SHU9119 and MTII, and the other for compound 2 and some other conformers of SHU9119 and MTII. The remaining conformers of SHU9119 and MTII, which did not map to compound 1 or 2, suggested that they were outside of the hMC‐4R binding envelop. These observations may lead to conjectures as to why compound 1 is highly active and selective toward hMC‐4R. © 2003 Wiley Periodicals, Inc. Biopolymers 68: 512–527, 2003
Elongational flow studies on conformational change in DNA induced by DNA‐binding protein HU
Authors: Endoh Takashi , Iyaguchi Daisuke , Sasaki Naoki , Tanaka Isao , Nakata Mitsuo
Published: March 2003

Interaction of DNA‐binding protein HU from Bacillus stearothermophilis (HUBst) with coliphage T2 DNA was investigated by observing an elongational flow‐induced birefringence, Δn, of a T2‐phage DNA aqueous solution at various HU concentrations. Localized flow birefringence was observed in the pure elongational flow region, and the strain rate dependence of Δn had a critical strain rate ϵ˙c for the appearance of flow birefringence at all of the HU concentrations examined, indicating that a coil–stretch transition occurred at ϵ˙c in each DNA–HU system. For strain rates larger than ϵ˙c, Δn increased rapidly and then gradually, approaching a plateau value. The value of ϵ˙c increased with an increase in HU concentration. Analysis based on the relationship between ϵ˙ c and the Rouse–Zimm relaxation time revealed that the increase in ϵ˙cwith increase in HU can be explained by the decrease in the size of the DNA–HU complex. The plateau birefringence value, Δnp, decreased at small HU concentrations but did not change at larger HU concentrations. Considering that Δnp is related to the orientational order parameter of segments, it was concluded that there were at least two stages in the process of compaction of DNA induced by HU. © 2003 Wiley Periodicals, Inc. Biopolymers 68: 486–496, 2003
A framework for delivering fine granularity and fair service discrimination in DiffServ networks
Authors: Dumitrescu Avadora , Harju Jarmo
Published: March 2003

In order to achieve a quality of service (QoS) capable of satisfying an ever increasing range of user requirements, differentiated services (DiffServ) have been introduced as a scalable solution that emerges ‘naturally’ from today's best effort service approach. Mapping the packet treatment into a small number of per hop behaviours (PHBs) is the key idea behind the scalability of DiffServ but this comes at the cost of loosing some behavioural differentiation and some fairness between flows multiplexed into the same aggregated traffic. The paper proposes a novel simple and effective DiffServ approach, the ‘Simple Weighted Integration of diFferentiated Traffic’ (SWIFT), and uses it in a series of simulations covering a relatively wide range of local network conditions. Measured voice and video traffic traces and computer generated self‐similar background traffic were used in simulations performed at various congestion levels and for in‐profile and out‐of‐profile source behaviour. The resulted throughput, mean delay, maximum delay and jitter are used to asses SWIFT's capabilities—isolation of the in‐profile traffic from congestion effects, treatment differentiation, increased resource utilization, fairness in treatment under congestion, and incentivity for nice behaviour. Comparisons with other approaches employing traffic control are also provided. Copyright © 2003 John Wiley & Sons, Ltd.
Multimedia transmission with adaptive QoS based on real‐time protocols
Authors: Bouras Ch. , Gkamas A.
Published: March 2003

In this paper, we describe a mechanism for adaptive transmission of multimedia data, which is based on real‐time protocols. The proposed mechanism can be used for unicast or multicast transmission of multimedia data over heterogeneous networks, like the Internet, and has the capability to adapt the transmission of the multimedia data to network changes. In addition, the implemented mechanism uses an inter‐receiver fairness function in order to treat the group of clients with fairness during the multicast transmission in a heterogeneous environment. The proposed mechanism uses a ‘friendly’ to the network users congestion control policy to control the transmission of the multimedia data. We implement a prototype application based on the proposed mechanism and we evaluate the proposed mechanism both in unicast and multicast transmission through a number of experiment and a number of simulations in order to examine its fairness to a group of clients and its behaviour against transport protocols (TCP) and UDP data streams. Copyright © 2003 John Wiley & Sons, Ltd.
A multi‐user CDMA receiver utilizing decorrelating detector with additional dummy pilot response
Authors: Tomita Mitsuhiro , Kuroyanagi Noriyoshi , Ozawa Satoru , Suehiro Naoki
Published: March 2003

A pilot assisted CDMA system which uses extended spreading sequences with guard sequences under a quasi‐synchronous condition is capable of separating the interference components included in the input of a de‐correlating receiver by solving a system of linear equations. The performance of such a system, however, depends on the property of the de‐correlating matrix consisting of the received pilots, which correspond to the respective user spreading sequences and the multi‐path channel conditions. That is, the regularity of the matrix often tends to degrade, and the rank reduces occasionally primarily due to the multi‐paths, resulting in solutions that are vulnerable to AWGN. The present paper proposes an effective technique to solve this problem by introducing a virtual user into a group of real users that are to be served. The simulation results indicate a remarkable improvement in the bit‐error‐rate (BER) performance. In addition, based on the BER performance, the system has a RAKE‐like function that has power‐sum characteristics. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of an enhancer region in the mouse ephA8 locus directing expression to the anterior region of the dorsal mesencephalon
Authors: Koo Jashin , Shim Sungbo , Gu Changkyu , Yoo Ookjoon , Park Soochul
Published: March 2003

Eph receptors and ephrins are dynamically expressed in a wide range of regions of the vertebrate during embryogenesis. The dorsal mesencephalon appears to be segmented into two broad regions demarcated by the mutually exclusive expression of EphA receptors and ephrinA ligands. It is of considerable interest to elucidate how these expression domains are established in the development of the mesencephalon. In this study, we used a transgenic approach to define the cis‐acting DNA regulatory elements involved in the anterior mesencephalon‐specific expression of the mouseephA8gene. Our analyses of the temporal and spatial expression patterns of variousephA8/lacZgene fusions in transgenic mice revealed that the 10‐kb genomic DNA 5′ immediately upstream of theephA8coding sequence is capable of directinglacZexpression in anephA8‐specific manner. Further deletion analyses of theephA8genomic region led to the identification of a 1‐kb enhancer region, which directs expression in the embryo to the anterior region of the developing midbrain. ThisephA8‐specific regulatory DNA sequences can now be used in biochemical analyses to identify proteins modulating the anterior differentiation of the optic tectum, and in functional analyses to direct the expression of other developmentally important genes to this region. Developmental Dynamics 226:596–603, 2003. © 2003 Wiley‐Liss, Inc.
Expression of mouse Tbx22 supports its role in palatogenesis and glossogenesis
Authors: Herr Alexander , Meunier Dominique , Müller Ines , Rump Andreas , Fundele Reinald , Ropers H.‐Hilger , Nuber Ulrike A.
Published: March 2003

TBX22 belongs to the T‐box family of transcription factors and was originally found in an in silico approach designed to identify new genes on the human Xq12‐q21 region. Mutations in TBX22 have been reported in families with X‐linked cleft palate and ankyloglossia (CPX), but the underlying pathogenetic mechanism remained unknown. We have identified mouse Tbx22 and analyzed its expression during embryogenesis by reverse transcriptase‐polymerase chain reaction and in situ hybridization. In mouse embryos, it is expressed in distinct areas of the head, namely the mesenchyme of the inferior nasal septum, the posterior palatal shelf before fusion, the attachment of the tongue, and mesenchymal cells surrounding the eye anlage. The localization in the tongue frenulum perfectly correlates with the ankyloglossia phenotype in CPX. Furthermore, we identified positionally conserved binding sites for transcription factors, two of which have been implicated previously in palatogenesis (MSX1, PRX2). Developmental Dynamics 226:579–586, 2003. © 2003 Wiley‐Liss, Inc.
Expression of ZIC genes in the development of the chick inner ear and nervous system
Authors: Warner Stephen J. , Hutson Mary R. , Oh Seung‐Ha , Gerlach‐Bank Lisa M. , Lomax Margaret I. , Barald Kate F.
Published: March 2003

ZIC genes, vertebrate homologues of the Drosophila pair‐rule gene odd‐paired (opa), function in embryonic pattern formation, in the early stages of central nervous system neurogenesis and in cerebellar maturation. Mouse Zic genes are expressed in restricted, and in some cases overlapping, patterns during development, particularly in the central and peripheral nervous systems. We identified chick ZIC2 in a differential display analysis of the auditory system designed to find genes up‐regulated after noise trauma. In this study, we examined the expression of chick ZIC1, ZIC2, and ZIC3 by in situ hybridization in normal inner ear development and in the tissues that influence its development, including the hindbrain, the neural crest, and the periotic mesenchyme. Between Hamburger and Hamilton stages 13 and 24, all three ZIC genes were found in the dorsal periotic mesenchyme adjacent to the developing inner ear. ZIC1 mRNA was expressed in the otocyst epithelium between stages 12 and 24, in some sensory tissue, as well as in a striped pattern in the floorplate of the hindbrain that appears to be complementary to that of Chordin, a gene known to regulate ZIC expression in frogs. Chick ZIC genes are also expressed in the neuroectoderm, paraxial mesenchyme, brain, spinal cord, neural crest, and/or the overlying ectoderm as well as the limb buds. In general, ZIC1 and ZIC2 expression patterns overlapped, although ZIC2 expression was less robust; ZIC3 expression was minimal. These observations suggest that ZIC genes, in addition to their known roles in brain development, may play an important role in the development of the chick inner ear. Developmental Dynamics 702–712, 2003. © 2003 Wiley‐Liss, Inc.
Differential expression of decorin and biglycan genes during palatogenesis in normal and retinoic acid–treated mice
Authors: Zhang Yuxiang , Mori Tetsuji , Iseki Ken , Hagino Seita , Takaki Hiromi , Takeuchi Mayumi , Hikake Tsuyoshi , Tase Choichiro , Murakawa Masahiro , Yokoya Sachihiko , Wanaka Akio
Published: March 2003

Proteoglycans are involved in secondary palate formation. In the present study, we focused on two small leucine‐rich proteoglycans, decorin and biglycan, because they assembled extracellular matrix molecules such as collagens and modulated signaling pathway of transforming growth factor‐β. To investigate the functions of decorin and biglycan in palatogenesis, we compared their mRNA expression patterns between normal palate and retinoic acid‐induced cleft palate in mice by using in situ hybridization analysis during the period of embryonic day 13.5 (E13.5) to E15.5. On E13.5, decorin mRNA was expressed in the epithelia and mesenchyme on the nasal side of the developing secondary palate. During the period the palate shelves were fusing (E14.5), decorin mRNA was strongly expressed in the mesenchyme but its expression pattern was asymmetric; decorin mRNA expression area in the nasal side was broader than that in the oral side. The expression of decorin mRNA was hardly detected in the mesenchyme on either side of the medial edge epithelium. After fusion (E15.5), its expression converged to the mesenchyme just around the palatine bone. Biglycan mRNA was ubiquitously distributed throughout the palatal mesenchyme for the mid‐gestation period. Its expression area became limited to the ossification area within the palate after the late gestation period. In the retinoic acid–treated mice, the area of the decorin gene expression expanded to the core region of the palate primordium where little signal was observed in control mice. On the other hand, biglycan in the retinoic acid–treated mice did not show remarkable change in its distribution patterns compared with that in the control mice. These findings suggest that decorin and biglycan play distinct roles in palatogenesis, and decorin was more actively involved in the process of secondary palate formation than biglycan. Up‐regulation of decorin gene expression in the retinoic acid–treated mice might influence the pathogenesis of cleft palate. Developmental Dynamics 226:618–626, 2003. © 2003 Wiley‐Liss, Inc.
Expression and regulation of groucho‐related genes in the embryonic chicken feather bud
Authors: Houghton Leslie , Freeman Allison , Morgan Bruce A.
Published: March 2003

The groucho‐related gene (Grg) products modulate the transcriptional response to several extracellular signals, including the Wnts. In an effort to define the roles of Grgs in the morphogenesis of the feather bud, cDNAs encoding members of the Grg family were cloned from embryonic chick skin. In situ hybridization was used to localize transcripts for cGrg2, Grg3, Grg4, and Grg5 in embryos from day 6 through day 9. Expression of cGrg2, 3, and 5 is detected throughout the initial epidermal placode. As the buds mature, expression becomes limited to the posterior halves and eventually to the distal tip of the outgrowing bud. This pattern and the effects of forced activation of the bone morphogenetic protein and β‐catenin signal transduction pathways on Grg gene expression suggest that these genes act downstream of the early activation of the β‐catenin pathway that initiates placode formation. Induction of Grg genes by β‐catenin may serve as a negative feedback to modulate pathway activation while also altering the activity of other transduction pathways involved in bud patterning. Developmental Dynamics 226:587–595, 2003. © 2003 Wiley‐Liss, Inc.
Expression and misexpression of members of the FGF and TGFβ families of growth factors in the developing mouse pancreas
Authors: Dichmann Darwin S. , Miller Christopher P. , Jensen Jan , Scott Heller R. , Serup Palle
Published: March 2003

We have performed a high‐capacity, semiquantitative, reverse transcriptase‐polymerase chain reaction screen for expression of fibroblast growth factor (FGF) and transforming growth factor β (TGFβ) family genes as well as their cognate receptors. By using cDNA prepared from embryonic day 12 to postnatal day 0 embryonic mouse pancreas, we have identified several factors potentially involved in the development of the endocrine pancreas. We find high‐level early expression of TGFβ‐1 and ‐2, and constitutive expression of TGFβ‐3 and their receptors. Of the Inhibin/Activin members, we found exclusively Inhibin‐α and Activin‐βB to be expressed, and the BMP family was represented by BMP4, BMP5, and BMP7. The predominant forms of the BMP and Activin type II receptors were ActR‐IIB and BMPR‐II and of the type I receptors, BMPR‐1A and ‐1B were the highest expressed. FGF1, FGF7, FGF9, FGF10, FGF11, and FGF18 were also expressed in the pancreas at varying time points and levels, as well as FGF receptor forms FGFR1b, FGFR1c, FGFR2b, FGFR2c, FGFR3b, and FGFR4. To gain insight into the biological function, we misexpressed members of these families in the pancreas by using the early pancreas promoter Pdx1. Misexpression of FGF4 results in disruption of the pancreas morphology with epithelial structures interspersed in stroma tissue. The endocrine compartment was reduced to scattered single cells, and the exocrine consisted of unbranched ductal epithelia with acinar structures budding off. In contrast, misexpression of BMP‐6 resulted in complete agenesis of the pancreas and reduced the size of the stomach and spleen dramatically and caused fusion of the liver and duodenum. Developmental Dynamics 226:663–674, 2003. © 2003 Wiley‐Liss, Inc.
Expression and regulation of eHAND during limb development
Authors: Fernandez‐Teran Marian , Piedra M. Elisa , Rodriguez‐Rey Jose C. , Talamillo Ana , Ros Maria A.
Published: March 2003

eHAND is a bHLH transcription factor with important functions during embryogenesis. Here, we report that eHAND has a dynamic pattern of expression during limb development. In chick embryos, eHAND expression is first observed in the ventral mesoderm of the emerging limb. Its expression is then restricted to an anteroventral area of mesoderm at mid‐level in the proximodistal axis. At later stages, expression is observed in the autopod encompassing the ventral tendons of the digits. In mouse embryos, only the anteroventral domain of expression is conserved, the early ventral expression not being detectable and the late pattern of expression differing clearly from that in the chick. A constant feature of all areas of expression is their ventral and anterior localization. Respecification of the anterior mesoderm as occurs secondarily to Sonic hedgehog (SHH) or retinoic acid application to the anterior border leads to down‐regulation of eHAND expression. Accordingly, eHAND expression is not detectable in talpid2 mutant limbs, which are considered to be posteriorized limbs. However, eHAND expression is little modified in oligozeugodactyly, a chick mutant that lacks Shh signaling in the limb but retains certain anteroposterior polarity. Interestingly, eHAND expression is also linked to the ventral identity of the mesoderm and is repressed by the dorsal ectoderm. It is also positively regulated by bone morphogenetic protein signaling, which is also known to participate in dorsoventral patterning. We suggest that eHAND expression may be related to the anteroventral identity of the mesoderm. However, in overexpression experiments using retroviral vectors, only a low percentage of cases (5%) showed phenotypic alterations, consisting of a duplication of digit 2. Developmental Dynamics 226:690–701, 2003. © 2003 Wiley‐Liss, Inc.
Mitochondrial ATP synthase controls larval development cell nonautonomously in Caenorhabditis elegans
Authors: Tsang William Y. , Lemire Bernard D.
Published: March 2003

The mitochondrial respiratory chain is composed of five protein complexes capable of generating cellular energy in the form of ATP. Defects in mitochondrial energy production can result in a wide variety of diseases with tissue‐specific effects. We previously have isolated a mutation in the atp‐2 gene, which encodes the active site or β‐subunit of complex V in Caenorhabditis elegans. This atp‐2(ua2) mutation is lethal, resulting in developmental arrest at the third larval stage (L3). In this report, we use mosaic analysis to identify the tissues in which atp‐2 gene activity is dispensable for development past the L3 stage. The loss of atp‐2 in any tissue can provoke arrest at the L3 stage. However, animals with a loss of the atp‐2 gene in the ABa lineage, which gives rise to neuronal, pharyngeal, and hypodermal cells, and/or the E lineage, which gives rise to the intestinal cells, can occasionally develop past L3. Loss of atp‐2 gene function in the lineages that give rise to the body muscles is invariably associated with developmental arrest. This finding suggests that the body muscles may play a key role in regulating development. We conclude that atp‐2 functions cell nonautonomously in this developmental process. Our findings suggest that atp‐2 is involved in the production or the regulation of a global, developmental signal required for the L3‐to‐L4 transition. Developmental Dynamics 719–726, 2003. © 2003 Wiley‐Liss, Inc.