bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of proximity of a rail end in elastic-plastic contact between a wheel and a rail
Authors: Chen Y. C.
Published: September 2003

This paper investigates the effects of a free rail end on the contact stress distribution near the rail end by employing elastic-plastic finite element methods. The contact elements were used to simulate the interaction between a wheel and a rail. A plane strain model was used in this study. Variations in contact stress fields at various contact points near the rail end were compared. The availability of the Hertz contact theory in the region near the rail end was also investigated. The numerical results indicated that the contact stress distributions around the rail end are sensitive to the contact distance. The location of the maximum von Mises stress was shifted to the contact surface as the contact point moves close to the rail end. Results also show that the plastic zone size and the von Mises stress are increased gradually and extend to the rail end as the contact point moves near the rail end. A higher stress, larger deflection and serious plastic deformation occurring at the rail end may lead to deterioration and delamination at the rail end.
On computational fluid dynamics modelling of crosswind effects for high-speed rolling stock
Authors: Diedrichs B
Published: September 2003

This work addresses crosswind stability exemplified for the German Railway Deutsche Bahn AG high-speed train ICE 2. The scope of the work is to describe the flow by means of computational fluid dynamics past the leading two cars of the train for yaw angles in the range 12.2–40.0°. Three track formations are utilized. The basic results are the set of independent aerodynamic coefficients for the lead and subsequent cars. The results are to some extent compared with experimental data for ICE 2 and also with data obtained for the Swedish high-speed train X2000.

A numerical sensitivity study is undertaken to quantify differences in the above results dependent on the grid density and quality, turbulence model, numerical scheme, location of inlet and outlet boundaries, turbulence intensity and flow simulation software.
Adenosine 5′-O-(3-thio)triphosphate (ATPγS) is a substrate for the nucleotide hydrolysis and RNA unwinding activities of eukaryotic translation initiation factor eIF4A
Authors: PECK MATTHEW L. , HERSCHLAG DANIEL
Published: September 2003

Whereas ATPγS is often considered a nonhydrolyzable substrate for ATPases, we present evidence that ATPγS is a good substrate for the RNA-stimulated nucleotide hydrolysis and RNA unwinding activities of eIF4A. In the presence of saturating single-stranded poly(U) RNA, eIF4A hydrolyzes ATPγS•Mg and ATP•Mg with similar steady-state parameters (KMNTP•Mg = 66 and 58 μM and kcat = 1.0 and 0.97 min−1, respectively). ATPγS•Mg also supports catalysis of RNA unwinding within 10-fold of the rate supported by ATP•Mg. The identical steady-state rate parameters, in comparison with the expected difference in the intrinsic rate of hydrolysis for ATP and ATPγS, suggest a nonchemical rate-limiting step for nucleotide hydrolysis. These results raise caution concerning the assumption that ATPγS is a nonhydrolyzable ATP analog and underscore the utility of thio-substituted NTPs as mechanistic probes.
Nonreplicative homologous RNA recombination: Promiscuous joining of RNA pieces?
Authors: GMYL ANATOLY P. , KORSHENKO SERGEY A. , BELOUSOV EVGENY V. , KHITRINA ELENA V. , AGOL VADIM I.
Published: September 2003

Biologically important joining of RNA pieces in cells, as exemplified by splicing and some classes of RNA editing, is posttranscriptional, whereas in RNA viruses it is generally believed to occur during viral RNA polymerase-dependent RNA synthesis. Here, we demonstrate the assembly of precise genome of an RNA virus (poliovirus) from its cotransfected fragments, which does not require specific RNA sequences, takes place before generation of the viral RNA polymerase, and occurs in different ways: Apparently unrestricted ligation of the terminal nucleotides, joining of any one of the two entire fragments with the relevant internal nucleotide of its partner, or internal crossovers within the overlapping sequence. Incorporation of the entire 5′ or 3′ partners into the recombinant RNA is activated by the presence of terminal 3′-phosphate and 5′-OH, respectively. Such postreplicative reactions, fundamentally differing from the known site-specific and structurally demanding cellular RNA rearrangements, might contribute to the origin and evolution of RNA viruses and could generate new RNA species during all stages of biological evolution.
Efficiency of a programmed −1 ribosomal frameshift in the different subtypes of the human immunodeficiency virus type 1 group M
Authors: BARIL MARTIN , DULUDE DOMINIC , GENDRON KARINE , LEMAY GUY , BRAKIER-GINGRAS LÉA
Published: September 2003

The synthesis of the Gag-Pol polyprotein, the precursor of the enzymes of the human immunodeficiency virus type 1 (HIV-1), requires a programmed −1 ribosomal frameshift. This frameshift has been investigated so far only for subtype B of HIV-1 group M. In this subtype, the frameshift stimulatory signal was found to be a two-stem helix, in which a three-purine bulge interrupts the two stems. In this study, using a luciferase reporter system, we compare, for the first time, the frameshift efficiency of all the subtypes of group M. Mutants of subtype B, including a natural variant were also investigated. Our results with mutants of subtype B confirm that the bulge and the lower stem of the frameshift stimulatory signal contribute to the frameshift in addition to the upper stem–loop considered previously as the sole participant. Our results also show that the frameshift stimulatory signal of all of the other subtypes of group M can be folded into the same structure as in subtype B, despite sequence variations. Moreover, the frameshift efficiency of these subtypes, when assessed in cultured cells, falls within a narrow window (the maximal deviation from the mean value calculated from the experimental values of all the subtypes being ~35%), although the predicted thermodynamic stability of the frameshift stimulatory signal differs between the subtypes (from −17.2 kcal/mole to −26.2 kcal/mole). The fact that the frameshift efficiencies fall within a narrow range for all of the subtypes of HIV-1 group M stresses the potential of the frameshift event as an antiviral target.
The extended loops of ribosomal proteins L4 and L22 are not required for ribosome assembly or L4-mediated autogenous control
Authors: ZENGEL JANICE M. , JERAULD ADAM , WALKER ANDRE , WAHL MARKUS C. , LINDAHL LASSE
Published: September 2003

Ribosomal proteins L4 and L22 both have a globular domain that sits on the surface of the large ribosomal subunit and an extended loop that penetrates its core. The tips of both loops contribute to the lining of the peptide exit tunnel and have been implicated in a gating mechanism that might regulate the exit of nascent peptides. Also, the extensions of L4 and L22 contact multiple domains of 23S rRNA, suggesting they might facilitate rRNA folding during ribosome assembly. To learn more about the roles of these extensions, we constructed derivatives of both proteins that lack most of their extended loops. Our analysis of ribosomes carrying L4 or L22 deletion proteins did not detect any significant difference in their sedimentation property or polysome distribution. Also, the role of L4 in autogenous control was not affected. We conclude that these extensions are not required for ribosome assembly or for L4-mediated autogenous control of the S10 operon.
Efficient and specific repair of sickle β-globin RNA by trans-splicing ribozymes
Authors: BYUN JONGHOE , LAN NING , LONG MEREDITH , SULLENGER BRUCE A.
Published: September 2003

Previously we demonstrated that a group I ribozyme can perform trans-splicing to repair sickle β-globin transcripts upon transfection of in vitro transcribed ribozyme into mammalian cells. Here, we sought to develop expression cassettes that would yield high levels of active ribozyme after gene transfer. Our initial expression constructs were designed to generate trans-slicing ribozymes identical to those used in our previous RNA transfection studies with ribozymes containing 6-nucleotide long internal guide sequences. The ribozymes expressed from these cassettes, however, were found to be unable to repair sickle β-globin RNAs. Further experiments revealed that two additional structural elements are important for ribozyme-mediate RNA repair: the P10 interaction formed between the 5′ end of the ribozyme and the beginning of the 3′ exon and an additional base-pairing interaction formed between an extended guide sequence and the substrate RNA. These optimized expression cassettes yield ribozymes that are able to amend 10%–50% of the sickle β-globin RNAs in transfected mammalian cells. Finally, a ribozyme with a 5-bp extended guide sequence preferentially reacts with sickle β-globin RNAs over wild-type β-globin RNAs, although the wild-type β-globin transcript forms only a single mismatch with the ribozyme. These results demonstrate that trans-splicing ribozyme expression cassettes can be generated to yield ribozymes that can repair a clinically relevant fraction of sickle β-globin RNAs in mammalian cells with greatly improved specificity.
A second functional RNA domain in the 5′ UTR of the Tomato bushy stunt virus genome: Intra- and interdomain interactions mediate viral RNA replication
Authors: RAY DEBASHISH , WU BAODONG , WHITE K. ANDREW
Published: September 2003

The 5′ untranslated regions (UTRs) of (+)-strand RNA viruses play a variety of roles in the reproductive cycles of these infectious agents. Tomato bushy stunt virus (TBSV) belongs to this class of RNA virus and is the prototype member of the genus Tombusvirus. Previous studies have demonstrated that a T-shaped domain (TSD) forms in the 5′ half of the TBSV 5′ UTR and that it plays a central role in viral RNA replication. Here we have extended our structure–function analysis to the 3′ half of the 5′ UTR. Investigation of this region in the context of a model viral replicon (i.e., a TBSV-derived defective interfering [DI] RNA) revealed that this segment contains numerous functionally relevant structural features. In vitro solution structure probing along with comparative and computer-aided RNA secondary structure analyses predicted the presence of a simple stem loop (SL5) followed by a more complex downstream domain (DSD). Both structures were found to be essential for efficient DI RNA accumulation when tested in a plant protoplast system. For SL5, maintenance of the base of its stem was the principal feature required for robust in vivo accumulation. In the DSD, both helical and unpaired regions containing conserved sequences were necessary for efficient DI RNA accumulation. Additionally, optimal DI RNA accumulation required a TSD–DSD interaction mediated by a pseudoknot. Modifications that reduced accumulation did not appreciably affect DI RNA stability in vivo, indicating that the DSD and SL5 act to facilitate viral RNA replication.
Protein synthesis by single ribosomes
Authors: VANZI FRANCESCO , VLADIMIROV SERGUEI , KNUDSEN CHARLOTTE R. , GOLDMAN YALE E. , COOPERMAN BARRY S.
Published: September 2003

The ribosome is universally responsible for synthesizing proteins by translating the genetic code transcribed in mRNA into an amino acid sequence. Ribosomes use cellular accessory proteins, soluble transfer RNAs, and metabolic energy to accomplish the initiation, elongation, and termination of peptide synthesis. In translocating processively along the mRNA template during the elongation cycle, ribosomes act as supramolecular motors. Here we demonstrate that ribosomes adsorbed on a surface, as for mechanical or spectroscopic studies, are capable of polypeptide synthesis and that tethered particle analysis of fluorescent beads connected to ribosomes via polyuridylic acid can be used to estimate the rate of polyphenylalanine synthesis by individual ribosomes. This work opens the way for application of biophysical techniques, originally developed for the classical motor proteins, to the understanding of protein biosynthesis.
Effect of preparation parameters on performance of dense homogeneous polycarbonate gas separation membranes
Authors: Hacarlioglu P. , Toppare L. , Yilmaz L.
Published: September 2003

The aim of this study is to determine the effect of preparation parameters on the membrane permeation mechanism and separation performances of dense homogeneous poly(bisphenol A carbonate) (PC) membranes. Blade‐casting and drop‐casting techniques are used for casting films from solutions with varying concentrations. Chloroform and methylene chloride are used to determine the effect of the properties of the casting solvent. Permeation measurements are done with Ar, N2, O2, CH4, CO2, and H2 gases. The selectivity values of dense homogeneous membranes with a PC composition of 7% (w/v chloroform) are 1.7 for Ar/N2, 1.1. for CH4/N2, 18 for CO2/N2, 26 for H2/N2, and 9.7 for O2/N2. These values with a PC composition of 15% (w/v methylene chloride) are 2.7, 1.3, 25, 44, and 13 for the same gases, respectively. In addition to the importance of the solvent type and composition, the casting type and thermal history also affects the performance of the membrane. Increasing the annealing period enhances the selectivity while decreasing the permeability for both casting solvents, yet this thermal history effect strongly depends on the solvent type because of solvent–polymer interactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 776–785, 2003
Investigation of crystallization behavior in dynamically vulcanized EPDM–nylon copolymer blends
Authors: Huang Hua , Liu Xin , Ikehara Takayuki , Nishi Toshio
Published: September 2003

A thermoplastic vulcanizate (TPV) of a ethylene–propylene–diene terpolymer (EPDM) and nylon copolymer (PA) was prepared by dynamic vulcanization. Maleic anhydride (MAH)–grafted EPDM (EPDM–g–MAH), MAH‐grafted EPR (EPR–g–MAH), and chlorinated polyethylene (CPE) were used as compatibilizers. The effect of dynamic vulcanization and compatibilizer on the crystallization behavior of PA was investigated. Differential scanning calorimeter measurement results showed no pronounced shift in the crystallization temperature for PA in EPDM–PA TPV compared to that for PA in the neat state, whereas the crystallization temperature increased after adding compatibilizer. The decrease in the crystallinity of TPVs was a result of the crystallization occurring in confined spaces between rubber particles. The equilibrium melting temperature (Tm0) of the PA copolymer was measured and was determined to be 157°C. The isothermal crystallization kinetics of PA in the neat and TPV states also was investigated. The crystallization rate was highest in the compatibilized TPV and lowest in the neat PA, whereas it was intermediate in the uncompatibilized TPV unvulcanized blends. Compared with unvulcanized EPDM–PA blends, the dynamic vulcanization process seemed to cause an obvious increase in the crystallization rate of the PA copolymer, especially when a suitable compatibilizer was used. This occurred because the dynamic vulcanization introduced fine crosslinked rubber particles that could act as heterogeneous nucleating centers. In addition, the use of a suitable compatibilizer permitted the formation of finely dispersed vulcanized rubber particles and therefore increased the density of the nucleating centers. The complex morphology of the blends was investigated by atomic force microscopy to evaluate the effect of compatibilizer on the size of the dispersed rubber particles. Compared with the morphology of TPVs with the same dosage of EPDM–g–MAH compatibilizer, the morphology of TPVs using EPR–g–MAH as compatibilizer showed much smaller dispersed rubber particles, which may have contributed to the higher crystallization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 824–829, 2003
Preparation and properties of nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites
Authors: Chen‐Yang Y. W. , Chen S. F. , Yuan C. Y. , Lee H. F. , Li J. L. , Li C. Y. , Chiu Y. S.
Published: September 2003

New novel fire‐resistant and heat‐resistant cyclotriphosphazene‐containing polyimide resins were prepared in situ by the polymerization of (p‐aminophenoxy)(phenoxy)cyclotriphosphazenes with 3,3′,4,4′‐benzophenonetetracarboxylic acid or 3,3′,4,4′‐diphenylsulfonetetracarboxylic acid and a crosslink agent, 5‐norbornene‐2,3‐dicarboxylic acid and were used as polymer matrix compositing with a woven carbon fiber to prepare nadic‐end‐capped cyclotriphosphazene‐containing polyimide/carbon fiber composites. The thermal stability, flame retardance, morphology of the surface fracture, and some physical properties of the composites were investigated by thermogravimetric analysis, scanning electron microscopy, and a material testing system, respectively. The composites had good thermal stability, flame retardance, and mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 810–818, 2003
Synthesis and characterization of silica nanocomposite in situ photopolymerization
Authors: Xu Guo Cai , Li Ai Yuan , Zhang Li De , Wu Guo Sheng , Yuan Xiao You , Xie Ting
Published: September 2003

This study was carried out on nanocomposites consisting of nanometer silica fillers embedded in thermoset polymers that were prepared via the in situ polymerization of ultraviolet (UV) curable systems containing different contents of nanometer silicas by irradiation of UV light. Because of the introduction of nanosilicas, the curing rates of the UV curing of dispersing systems were played down; that is, the curing times were prolonged, but the mechanical properties of the nanocomposites, such as tensile strength and Young's modulus, increased, and the thermostability of the nanocomposites at temperatures lower than 400 K improved. The dispersing states of nanometer silicas within the polymer matrix were characterized by transmission electron microscopy, and the results show that the nanometer silicas had good homogeneously dispersing states within nanocomposites containing less than 3 wt % nanometer silicas. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 837–840, 2003
Compatibility of low‐density polyethylene/poly(ethylene‐co‐vinyl acetate) binary blends prepared by melt mixing
Authors: Takidis G. , Bikiaris D. N. , Papageorgiou G. Z. , Achilias D. S. , Sideridou I.
Published: September 2003

The compatibility of low‐density polyethylene and poly(ethylene‐co‐vinyl acetate) containing 18 wt % vinyl acetate units (EVA‐18) was studied. For this purpose, a series of different blends containing 25, 50, or 75 wt % EVA‐18 were prepared by melt mixing with a single‐screw extruder. For each composition, three different sets of blends were prepared, which corresponded to the three different temperatures used in the metering section and the die of the extruder (140, 160, and 180°C), at a screw rotation speed of 42 rpm. Blends that contained 25 wt % EVA‐18 were also prepared through mixing at 140, 160, or 180°C but at a screw speed of 69 rpm. A study of the blends by differential scanning calorimetry showed that all the prepared blends were heterogeneous, except that containing 75 wt % EVA‐18 and prepared at 180°C. However, because of the high interfacial adhesion, a fine dispersion of the minor component in the polymer matrix was observed for all the studied blends with scanning electron microscopy. The tensile strengths and elongations at break of the blends lay between the corresponding values of the two polymers. The absence of any minimum in the mechanical properties was strong evidence that the two polymers were compatible over the whole range of composition. The thermal shrinkage of the blends at various temperatures depended mainly on the temperature and EVA‐18 content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 841–852, 2003
Determination of polymer–polymer interaction parameters using inverse gas chromatography
Authors: Huang Jan‐Chan
Published: September 2003

A modified method is discussed that is based on Farooque and Deshpande's method to obtain polymer–polymer interaction parameters using inverse gas chromatography (IGC) data. In the Farooque and Deshpande method, the ratio of the difference of probe–polymer interaction parameters between two polymers and the probe volume [(χ12 − χ13)/V1] is used as the abscissa. In the modified method, the ratio [(ϕ2χ12 + ϕ3χ13)/V1] is used as the abscissa. Experimental data previously reported for a poly(ϵ‐caprolactone)‐polyepichlorohydrin (PCL/PECH) blend and a poly(ethyl acrylate)‐poly(vinyl propionate) (PEA/PVPr) blend are analyzed. It is found that the slopes obtained by the new method had smaller deviations from the theoretical values than the Farooque and Deshpande method. The standard deviations of both slopes and intercepts obtained from the new method are also smaller. Using the new method, the polymer–polymer interaction parameters obtained from the intercept are negative numbers for the PCL/PECH system and very small positive numbers for PEA/PVPr. Explanations are given for the probe and concentration dependency of the polymer–polymer interaction parameters that are generally observed in IGC studies. A new method for selecting the best probe for calculating the interaction parameter is discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 671–680, 2003
Solution spinning and characterization of poly(vinyl alcohol)/soybean protein blend fibers
Authors: Zhang Xiefei , Min Byung G. , Kumar Satish
Published: September 2003

Soybean protein/poly(vinyl alcohol) (PVA) blend fibers were processed using wet spinning, after modifying the protein solution by thermal denaturation without alkali. Dynamic mechanical properties as well as scanning electron microscopy studies suggest compatibility between PVA and soybean protein. The effect of crosslinking agent, crosslinking time, and heat‐treatment temperature on the mechanical properties of blend fibers was studied. The soybean protein fibers or the blend fibers containing less than 40% PVA were unoriented amorphous, whereas the blend fibers containing more than 40% PVA exhibited the crystalline structure of PVA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 716–721, 2003
Poly(dimethylsiloxane) coatings for controlled drug release. I. Preparation and characterization of pharmaceutically acceptable materials
Authors: Gao Zongming , Schulze Nahrup Julia , Mark James E. , Sakr Adel
Published: September 2003

The basic technology for forming crosslinked elastomers by the end linking of low molecular weight hydroxyl‐terminated poly(dimethylsiloxane) (PDMS) with tetraethoxysilane (TEOS) was modified to make it suitable for preparing coatings for controlled drug release. The requirements for this application included establishing conditions for the end linking that did not require the usual toxic tin or platinum catalysts; preparation of emulsions of small PDMS network particles that had extensive shelf‐lives and that could be coalesced into cohesive thin films or coatings; and the determination of the conditions to make such coatings pinhole free, mechanically robust, and of sufficient thermal stability for coating procedures at elevated temperatures. The approach taken consisted of preparing water‐based emulsions of the PDMS with sodium lauryl sulfate and restriction of the pH of the system to the acidic range with HCl. Evaporation of water from the emulsions resulted in elastomeric free‐standing films of the PDMS that were characterized using stress–strain isotherms in elongation and equilibrium swelling in toluene, both at room temperature. The mechanical properties of the films were found to improve with an increasing molar ratio of HCl/TEOS and an increase in the amount of TEOS (giving increased degrees of crosslinking). Conditions for the optimization of the thermal stabilities as gauged by thermogravimetic analysis were established, including beneficial effects from the introduction of the crosslinks. Scanning electron microscopy showed that the predominant morphology was void‐free films with very small, homogeneously dispersed silica particles from the hydrolysis of some of the TEOS. Additional work should be facilitated by the mechanisms for the crosslinking suggested by the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 658–666, 2003
Preparation and characterization of alginate hydrogel membranes crosslinked using a water‐soluble carbodiimide
Authors: Xu J. B. , Bartley J. P. , Johnson R. A.
Published: September 2003

The preparation of alginate hydrogel membranes by the film immersion method was optimized for maximum crosslinking using swelling measurements as an indicator of the degree of crosslinking. The variables investigated were the concentration of the nonsolvent (ethanol) for sodium alginate, water‐soluble carbodiimide (WSC) concentration, and pH of the crosslinking medium. Optimum conditions resulted when the crosslinking medium contained 60 vol % ethanol and 100 mM WSC at pH 4. Membranes prepared using different ethanol concentrations (100 mM WSC, pH 4) and different WSC concentrations (60 vol % ethanol, pH 4) were investigated using infrared spectroscopy. The spectra showed the characteristic ester linkage (crosslinking) band at 1698 cm−1 in cases where swelling measurements indicated that crosslinking had occurred. Differential scanning calorimetry of noncrosslinked and crosslinked membranes indicated that crosslinking increased the crystallinity of the membrane. Durability trials showed that membranes crosslinked using the optimum conditions determined in this work retained all weight when immersed in water for 32 days. Membranes prepared using these conditions possessed the characteristics required for use in the pervaporation separation of ethanol–water mixtures. These membranes also have potential as protective coatings for hydrophobic, microporous membranes in the membrane distillation and osmotic distillation concentration of feeds containing surface active components. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 747–753, 2003
Scanning tunnel microscopy study of rayon‐based carbon‐fiber surfaces
Authors: Wu Qi‐Lin , Pan Ding
Published: September 2003

Because of its atomic resolution, scanning tunnel microscopy (STM) was applied to the study of the surface topography, in air, of rayon‐based carbon fibers (RCF) that were not previously studied. By a variety of larger scales, RCF exhibits some rugosities with “peaks” and “valleys.” The surfaces are characterized by stripe‐form crystallite stackings with the diameter of about 10 nm aligned at an angle between 45 and 60° to the fiber axis. A graphitelike structure was first observed on the surface of RCF examined at an atomic resolution scale. Distances between two adjacent carbon atoms of RCF and that between the closest centers of hexagonal carbon rings were estimated. It was also concluded that the hexagonal structure of RCF is deformed graphene (graphitelike) compared with that of highly oriented pyrolytic graphite. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 754–758, 2003
Synthesis and characterization of highly branched poly(anhydride‐co‐glycol) with glycerin as branching agent
Authors: Chan Cheng‐Kuang , Chu I‐Ming
Published: September 2003

A novel branched poly(anhydride‐co‐glycerol) was synthesized by introducing glycerin into a poly(sebacic anhydride‐co‐ethylene glycol) system via melt condensation without catalyst. The nuclear magnetic resonance spectroscopy (NMR) analysis showed that the reaction between the hydroxyl group on glycerin and the sebacic anhydride pre‐polymer was completed without any hydroxyl group remaining. In addition, with more glycerin introduced, intramolecular chain reaction became more remarkable. This resulted in the production of more cyclic chains and lower molecular weight species that hinder the crystal growth of sebacic anhydride chain segments. This in turn decreases melting temperature of sebacic anhydride chain segments in these synthesized materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 886–893, 2003
Numerical investigation of kinetics of free‐radical polymerization on spinning disk reactor
Authors: Leveson P. , Dunk W. A. E. , Jachuck R. J.
Published: September 2003

Spinning disk reactor (SDR) technology has been demonstrated to achieve significant enhancements in free radical polymerization rates. The effect on the rate may be attributed to the unique hydrodynamic environment experienced by the reacting polymer films. The rotating surface of a SDR promotes extension of the polymer chains, which may prevent the propagating chains from terminating through bimolecular reactions. In this article, a numerical simulation is performed to investigate how reduced rates of termination would affect time conversion behavior of free radical initiated styrene polymerization. Comparisons have been made between model predictions and SDR experimental results. The closeness between predicted and experimental results yields strong evidence that the hydrodynamic regime created on the surface of a SDR can lead to reduced rates of bimolecular termination. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 693–699, 2003
A highly selective inhibitor of IκB kinase, BMS‐345541, blocks both joint inflammation and destruction in collagen‐induced arthritis in mice
Authors: McIntyre Kim W. , Shuster David J. , Gillooly Kathleen M. , Dambach Donna M. , Pattoli Mark A. , Lu Pin , Zhou Xia‐Di , Qiu Yuping , Zusi F. Christopher , Burke James R.
Published: September 2003

Objective

The transcription of several cytokines, cell adhesion molecules, and enzymes involved in the inflammatory and destructive mechanisms of rheumatoid arthritis is dependent on nuclear factor κB (NF‐κB). Because IκB kinase (IKK) is critical in transducing the signal‐inducible activation of NF‐κB, we examined whether the highly selective and orally bioavailable IKK inhibitor BMS‐345541 is efficacious against collagen‐induced arthritis (CIA) in mice.

Methods

Arthritis in DBA/1LacJ male mice was induced by subcutaneous immunization with bovine type II collagen on day 0 and day 21. BMS‐345541 was administered perorally daily, either prophylactically (before disease onset) or therapeutically (after disease onset). Clinical assessment of the incidence and severity of disease was conducted throughout the study, and histologic evaluation was performed at the time of study termination (day 42).

Results

When administered prophylactically, BMS‐345541 (in a dose range of 10–100 mg/kg) was effective, in a dose‐dependent manner, in reducing the incidence of disease and inhibiting clinical signs of disease. Histologic evaluation of the joints showed that both inflammation and joint destruction were blocked by the IKK inhibitor. Message levels of interleukin‐1β in the joints were also dose‐dependently inhibited in the mice that received BMS‐345541. Dose‐dependent efficacy in terms of both disease severity and histologic end points was observed with the therapeutic dosing regimen of BMS‐345541, with use of the 100‐mg/kg dose resulting in resolution of disease.

Conclusion

IKK plays a key role in CIA in mice, and inhibitors of this enzyme represent a promising target for the development of novel agents to treat rheumatoid arthritis and other inflammatory diseases. BMS‐345541 represents the first example of an inhibitor of IKK that has antiinflammatory activity in vivo.
Mutations in the amino terminus of ANKH in two US families with calcium pyrophosphate dihydrate crystal deposition disease
Authors: Williams Charlene J. , Pendleton Adrian , Bonavita Gina , Reginato Antonio J. , Hughes Anne E. , Peariso Shelly , Doherty Michael , McCarty Daniel J. , Ryan Lawrence M.
Published: September 2003

Objective

To analyze ANKH in families with calcium pyrophosphate dihydrate crystal deposition disease (CPPD) for disease‐causing mutations.

Methods

Two US families (one of British ancestry and the other of German/Swiss ancestry) with autosomal‐dominant CPPD, whose disease phenotypes were found to be linked to chromosome 5p15.1 (locus symbol CCAL2), were screened by direct sequencing for mutations in ANKH, a gene in the CCAL2 candidate interval that has been shown to harbor mutations in other families with CPPD. Observed sequence variants were confirmed by antisense sequencing, and expression of the mutant allele was verified by reverse transcriptase–polymerase chain reaction amplification of messenger RNA followed by direct sequencing.

Results

The two US families displayed the same mutation at position 5 of the ANKH gene product (P5T). All affected members were heterozygous for the P‐to‐T variant, and the mutation was not seen in 204 control alleles. The two families displayed distinct disease haplotypes, suggesting that they were unrelated to each other.

Conclusion

These observations represent the fourth and fifth families with heritable CPPD whose disease phenotypes are linked to the CCAL2 locus and who have missense mutations in the amino terminus of ANKH. This same position (P5) was the site of a missense mutation in an Argentinean family of northern Italian ancestry; however, the sequence variant in that family generated a P5L mutation. The distinct disease haplotypes among the 3 families with P5 mutations suggest that the mutations arose independently and that the evolutionarily conserved P5 position of ANKH may represent a hot spot for mutation in families with autosomal‐dominant CPPD.
Enhanced degradation of proteins of the basal lamina and stroma by matrix metalloproteinases from the salivary glands of Sjögren's syndrome patients: Correlation with reduced structural integrity of acini and ducts
Authors: Goicovich Eduardo , Molina Claudio , Pérez Paola , Aguilera Sergio , Fernández Juan , Olea Nancy , Alliende Cecilia , Leyton Cecilia , Romo Rafael , Leyton Lisette , González María‐Julieta
Published: September 2003

Objective

To determine the effect of matrix metalloproteinase (MMP) activity from the labial salivary glands (LSGs) of Sjögren's syndrome (SS) patients on proteins of the extracellular matrix (ECM) that form the basal lamina and stroma, and to compare this effect with the structural integrity of acini and ducts as well as the functionality of the LSGs.

Methods

Gelatinase activity was determined by zymography. The digestion pattern of extracellular matrix (ECM) macromolecules was detected by gel electrophoresis and quantified by densitometry. The structural integrity of acini and ducts was evaluated by light and electron microscopy. Secretory function was evaluated by measuring unstimulated salivary flow and by scintigraphy.

Results

LSG extracts showed increased levels of proteolytic activity toward purified proteins of the basal lamina (laminin and type IV collagen) and stroma (types I and III collagen and fibronectin). Enhanced degradation was most evident for fibronectin, laminin, and type IV collagen. Analysis of the ultrastructure of the acinar and ductal basal lamina revealed abnormalities ranging from disorganization to disappearance of this ECM structure. These changes were paralleled by an important loss of microvilli on the apical surface, as well as decreased unstimulated salivary flow. Interestingly, the results were similar in LSGs from all SS patients, regardless of the proximity of infiltrating mononuclear cell foci.

Conclusion

Our observation that the proteolytic action of MMPs toward ECM macromolecules is increased in SS patients provides a rationale for understanding the dramatic changes in the structural organization observed in the basal lamina and apical surface of acini in these patients. The results provide new evidence that acinar and ductal cells from the LSGs of SS patients display a molecular potential, with increased capacity to markedly disorganize their ECM environment and, thus, damage their architecture and functionality.
Distinct mechanisms of action of anti‐CD154 in early versus late treatment of murine lupus nephritis
Authors: Quezada Sergio A. , Eckert Maria , Adeyi Oyedele A. , Schned Alan R. , Noelle Randolph J. , Burns Christopher M.
Published: September 2003

Objective

Treatment with anti‐CD154 antibody is known to ameliorate murine lupus nephritis when given early in the disease. The aims of this study were to identify the mechanism of this early effect, to determine whether late anti‐CD154 treatment could halt established nephritis, and, if so, to examine potential mechanisms of late efficacy.

Methods

We studied the effects of anti‐CD154 treatment on autoantibody production and immune complex deposition, renal pathology, survival, and renal cytokine and chemokine messenger RNA (mRNA) expression both in (NZB × NZW)F1 mice (BW mice) and in NZM.2410 mice.

Results

Early treatment with anti‐CD154 produced long‐term survival in BW mice, with abrogation of renal immune complex deposition for months after treatment was stopped. Late anti‐CD154 treatment, started after development of nephritis, could halt disease in ∼40% of mice. In some mice, proteinuria could be reversed repeatedly with sequential courses of anti‐CD154 antibody. The remissions induced by late treatment with anti‐CD154 occurred despite ongoing renal immune complex deposition. In preliminary studies, responding mice had rapid reductions in renal mRNA for transforming growth factor β, interleukin‐10, and tumor necrosis factor α.

Conclusion

Amelioration of murine lupus by anti‐CD154 therapy is mediated by distinct mechanisms in early versus late intervention. We postulate that anti‐CD154 therapy prevents autoantibody production and renal immune complex deposition in the early, induction phase and limits secondary tissue damage in situ in the late, effector phase. These data demonstrate that CD40–CD154 interactions are critical for the maintenance of autoimmunity and suggest a potential role for anti‐CD154 as a therapeutic agent in established human lupus.
Hospitalizations for coronary artery disease among patients with systemic lupus erythematosus
Authors: Thorburn Christine M. , Ward Michael M.
Published: September 2003

Objective

Although patients with systemic lupus erythematosus (SLE) have an increased risk of coronary artery disease (CAD) compared with persons without SLE, the burden of CAD among SLE patients is unknown. This study was undertaken to estimate this burden.

Methods

We used the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project to estimate the number of hospitalizations for CAD among patients with SLE in the US in 1998. CAD diagnoses included acute myocardial infarction (MI), unstable angina, cardiac catheterization, percutaneous transluminal coronary angioplasty, or coronary artery bypass grafting as the primary reason for hospitalization. We compared these estimates with the frequency of hospitalization for other reasons.

Results

There were an estimated 98,217 hospitalizations among patients with SLE in 1998. Of these, 11,947 (12%) were among men, 43,674 (44%) were among women <50 years of age, and 42,596 (43%) were among women ≥50 years of age. There were 4,951 hospitalizations for CAD, with 1,763 of these for acute MI. In women <50 years old, there were an estimated 311 hospitalizations for MI. Hospitalizations for CAD were less common than hospitalizations for SLE itself or for infections, and in young women, were less common than hospitalizations for complications of chronic renal failure.

Conclusion

CAD is an important comorbid condition in patients with SLE, but is not as common a reason for hospitalization as SLE itself, infections, and, in some patient subgroups, chronic renal failure.
Activin A induces cell proliferation of fibroblast‐like synoviocytes in rheumatoid arthritis
Authors: Ota Fumie , Maeshima Akito , Yamashita Shin , Ikeuchi Hidekazu , Kaneko Yoriaki , Kuroiwa Takashi , Hiromura Keiju , Ueki Kazue , Kojima Itaru , Nojima Yoshihisa
Published: September 2003

Objective

To investigate the expression of activin A and its receptors in rheumatoid arthritis (RA) synovial tissues, and to determine the effect of activin A on cultured fibroblast‐like synoviocytes (FLS).

Methods

The localization of activin A and activin type II receptor (ARII) in synovial tissues of RA patients was analyzed by immunohistochemistry. The expression of activin A and activin receptors in human cultured FLS was examined by reverse transcriptase–polymerase chain reaction and Western blotting. Enzyme‐linked immunosorbent assay was used to measure activin A in culture supernatants. The cell growth of FLS was determined by 3H‐thymidine incorporation and MTT assay.

Results

Immunohistochemical analysis confirmed the up‐regulation of activin A in rheumatoid synovium as compared with osteoarthritis or normal joint tissues. CD68+ macrophage‐lineage cells and vimentin‐positive FLS were identified as activin‐producing cells in rheumatoid synovium. Both cell types also expressed ARII. The expression of activin A and ARII on cultured FLS was confirmed at the protein and messenger RNA levels. Interleukin‐1β (IL‐1β), tumor necrosis factor α, and transforming growth factor β activated FLS to secrete activin A. Recombinant activin A accelerated the proliferation of FLS, while follistatin, an endogenous activin antagonist, partially inhibited FLS proliferation induced by IL‐1β.

Conclusion

These results suggest that activin A acts as a growth factor of FLS in RA.
Criminal careers behind bars
Authors: DeLisi Matt
Published: September 2003

In the criminal career literature, prison is usually viewed as an interruption of offending. Little research has applied the criminal career perspective to misconduct committed by prisoners. The current study used official data from a probability sample of 1,005 inmates from the southwestern United States to examine offending careers during incarceration. Descriptive and negative binomial regression analyses produced findings that suggest both similarities and dissimilarities between conventional and prison criminal careers. The incidence and prevalence of crime were inversely related to its seriousness but the magnitude of crime was higher in prison. One‐third of inmates were never contacted for a prison violation and 74% were never contacted for a serious/violent violation. On the other hand, 40% of inmates were chronic or extreme career offenderseven while incarcerated. A small cadre of inmates accounted for 100% of the murders, 75% of the rapes, 80% of the arsons, and 50% of the aggravated assaults occurring behind bars. Finally, prior criminality was the best predictor of prison offending, which is supportive of the importation model. While a significant number of inmates fully comply with prison rules, an even larger percentage of inmates continue to commit an array of crimes and rule violations despite the efforts of prison officials. Copyright © 2003 John Wiley & Sons, Ltd.
Ethical and legal standards for research in prisons
Authors: Kalmbach K. C. , Lyons Phillip M.
Published: September 2003

Biobehavioral research, especially that which is conducted with prisoners, has become much more closely regulated in the last 30 years. State and federal law, as well as professional standards, regulate the conduct of many types of research; in the case of prisoners, this regulation is even more stringent. However, currently no mandatory, uniform, national regulatory or oversight process exists, and many privately funded research endeavors are operating in a regulatory void. In response to this, the National Bioethics Advisory Commission has argued for the creation of a single, national, independent regulatory body to oversee all human participant research, regardless of funding source. As ethicolegal research standards evolve alongside advances in science and technology, an appreciation of the history of prisoner research and an awareness of current standards is critical to conducting ethical prison research. Copyright © 2003 John Wiley & Sons, Ltd.
Role of cytology in the diagnosis of Barrett's esophagus and associated neoplasia
Authors: Saad Reda S. , Mahood Laura K. , Clary Karen M. , Liu Yulin , Silverman Jan F. , Raab Stephen S.
Published: September 2003

We studied 327 consecutive paired esophageal biopsies and brushing specimens obtained during the same endoscopic session to evaluate the role of cytology for the diagnosis of Barrett's esophagus (BE) and/or surveillance for associated dysplasia. A diagnosis of BE was based on the cytologic presence of goblet cells. Cases were reviewed and categorized into: 1) benign esophageal lesions (125 cases), with 48 cases of Candida (32 cases diagnosed by both techniques and 16 diagnosed only by cytology), 3 cases of herpes simplex with only 1 case diagnosed by cytology, and 74 cases of inflammation and/or repair; 2) benign BE (141 cases), with 74 cases (52%) diagnosed by both techniques, 11 cases by cytology only (8%), and 56 cases (40%) by histology only; 3) low‐grade dysplasia (LGD, 30 cases), with 5 cases (17%) diagnosed with both specimens, one case (3%) by cytology only, and 24 cases (80%) by histology only; 4) high‐grade dysplasia (HGD, 10 cases), with 8 cases (80%) diagnosed with both specimens, 1 case (10%) by cytology, and 1 case (10%) by histology; and 5) carcinomas (23 cases), with 20 cases (87%) diagnosed with both specimens, 2 cases (9%) by cytology only, and 1 case (4%) by histology only. Our results support the high degree of diagnostic accuracy of cytology for the diagnosis of Barrett's‐associated HGD and/or carcinoma, and moderate sensitivity for BE. Diagn. Cytopathol. 2003;29:130–135. © 2003 Wiley‐Liss, Inc.
Volatile needle and wood extracts of oriental spruce Picea orientalis (L.) Link
Authors: Uçar Günes , Balaban Mualla , Usta Mustafa
Published: September 2003

Volatile needle and wood extracts of oriental spruce obtained from trees grown naturally in eastern Black Sea regions and in an cultivated stand near Istanbul were analysed by GC–MS. Despite considerable differences in both tree‐to‐tree and natural‐to‐cultivated aspects, the needle and wood extracts exhibit characteristic compounds, which might be of chemotaxonomic interest. The monoterpenes δ‐3‐carene, limonene and bornyl acetate dominate in the needles, whereas the appreciable amounts of labdadienol isomers and high content of diterpenoids characterize the wood extracts. Copyright © 2003 John Wiley & Sons, Ltd.
Effect of starch and amylopectin concentrations on volatile ﬂavour release from aqueous model food systems
Authors: van Ruth Saskia M. , King Carmel
Published: September 2003

The inﬂuence of starch and amylopectin (0, 1, 2, 3, 4 and 5% w/v) in aqueous model food systems was evaluated for 20 volatile ﬂavour compounds. To understand the inﬂuence of the gelling agents on the thermodynamic and kinetic component of volatile ﬂavour release, the release of six alcohols, ﬁve ketones, four esters, three aldehydes, one sulphur compound and one terpene was determined under equilibrium conditions and mouth conditions. For equilibrium analysis, the air/product partition coefﬁcients of the compounds were determined by equilibrium headspace gas chromatography. Under mouth conditions, the ﬂavour released in a model mouth system was analysed by gas chromatography–mass spectrometry. Both gelling agents and their concentration affected the release of the volatile compounds signiﬁcantly, resulting in a distortion of the ﬂavour composition. Under equilibrium conditions, starch showed greater ﬂavour retention than amylopectin. Under mouth conditions the opposite was observed; amylopectin affected ﬂavour release more than starch. Both functional group and chain length of the ﬂavour compounds inﬂuenced the effect of the gelling agent. Since the effects of the gelling agents differed under mouth and equilibrium conditions, it is conceivable that the kinetic component of ﬂavour release is of greater importance for the effect of these gelling agents on volatile ﬂavour release than the thermodynamic component. Copyright © 2003 John Wiley & Sons, Ltd.