bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of nonviral promoters in adenovirus‐mediated gene therapy: reduction of lysosomal storage in the aspartylglucosaminuria mouse
Authors: Virta Salli , Rapola Juhani , Jalanko Anu , Laine Minna
Published: March 2006

Background

Aspartylglucosaminuria (AGU) is a lysosomal storage disease with severe neurodegenerative clinical features resulting from the deficiency of lysosomal aspartylglucosaminidase (AGA). The AGU knockout mouse is a good model to test different therapy strategies, as it mimics well the human pathogenesis of the disease exhibiting storage vacuoles in all tissues. In this study we investigated the efficiency of nonviral promoters in adenovirus‐mediated gene therapy.

Methods

The deficient corrective enzyme, AGA, was expressed using two tissue‐specific promoters, neuron‐specific enolase (NSE), astrocyte‐specific (GFAP) and the endogenous AGA promoter. An intrastriatal injection site was chosen due to its wide connections in the central nervous system (CNS). The expression of AGA was analyzed 1 week, 2 weeks, 4 weeks, 2 months and 4 months after the virus injection by lysosomal AGA‐specific immunostaining. A correction of the lysosomal storage in the brain of treated mice was also studied using toluidine blue stained thin sections.

Results

The overexpressed AGA enzyme was detected in addition to the injection site, also in the ipsilateral parietal cortex indicating migration of AGA in the brain tissue. Duration of AGA expression was markedly longer with all the viruses used compared to the green fluorescent protein (GFP) expression driven by the viral cytomegalovirus (CMV) promoter. In most animals the storage was decreased by at least 50% as compared to untreated AGU mouse brains. Remarkably, >90% correction of storage at the ipsilateral cortex was found with the NSE promoter at 4 weeks and 2 months after injection. Additionally, partial clearance of storage was demonstrated also in the contralateral side of the brain.

Conclusions

These data implicate that tissue‐specific promoters are especially useful in virus‐mediated gene therapy aiming at long‐term gene expression. Copyright © 2006 John Wiley & Sons, Ltd.
VEGF 164 gene transfer by electroporation improves diabetic sensory neuropathy in mice
Authors: Murakami Tatsufumi , Arai Makiko , Sunada Yoshihide , Nakamura Akihiro
Published: March 2006

Background

Diabetic neuropathy is the most common cause of peripheral neuropathy and a serious complication of diabetes. Vascular endothelial growth factor (VEGF) stimulates angiogenesis and has neurotrophic and neuroprotective activities. To examine the efficiency of VEGF 164 electro‐gene therapy for neuropathy, intramuscular VEGF 164 gene transfer by electroporation was performed to treat sensory neuropathy in diabetic mice.

Methods

VEGF 164 was overexpressed in the tibial anterior (TA) muscles of streptozotocin‐induced diabetic mice with hypoalgesia, using a VEGF 164 plasmid injection with electroporation. From 2 weeks after electro‐gene transfer, the nociceptive threshold was measured weekly using the paw‐pressure test. The TA muscles, sciatic nerve, liver and spleen were histochemically examined at 4 weeks after electro‐gene transfer.

Results

Two weeks after electro‐gene transfer into the bilateral TA muscles, the elevated nociceptive threshold was decreased to a normal level in all treated mice. Improvement of the hypoalgesia continued for 14 weeks. When the VEGF 164 plasmid was injected with electroporation into a unilateral TA muscle, recovery from hypoalgesia was observed in not only the ipsilateral hindpaw, but also the contralateral one, suggesting that VEGF circulates in the blood. No increase in the number of endoneurial vessels in the sciatic nerve was found in the VEGF 164 plasmid‐electroporated mice.

Conclusions

These findings suggest that VEGF 164 electro‐gene therapy completely recovered the sensory deficits, i.e. hypoalgesia, in the diabetic mice through mechanisms other than angiogenesis in the endoneurium of the peripheral nerve, and may be useful for treatment for diabetic sensory neuropathy in human subjects. Copyright © 2006 John Wiley & Sons, Ltd.
Therapeutic level of functional human alpha 1 antitrypsin (hAAT) secreted from murine muscle transduced by adeno‐associated virus (rAAV1) vector
Authors: Lu Yuanqing , Choi Young‐Kook , Campbell‐Thompson Martha , Li Chengwen , Tang Qiushi , Crawford James M. , Flotte Terence R. , Song Sihong
Published: March 2006

Alpha 1 antitrypsin (AAT) is a serine proteinase inhibitor (serpin). One well‐known function of this protein is to inactivate neutrophil elastase and other neutrophil‐derived proteinases, and prevent the destruction of pulmonary extracellular matrix. Deficiency of AAT can cause emphysema due to degradation of interstitial elastin by elastase. The majority of circulating AAT is secreted from the liver. Muscle‐directed gene therapy using recombinant adeno‐associated virus 2 (rAAV2) vectors has been tested to increase the serum levels of AAT. However, inefficient transduction of rAAV2 vector makes it difficult to reach therapeutic levels of AAT in clinical trials and it remains unclear as to whether muscle‐secreted AAT is functional. In the present study, we evaluated five serotypes (1, 2, 3, 4, and 5) of rAAV vectors for transduction efficiency in mouse muscle. Results from these studies showed that rAAV1 is the most efficient vector among these serotypes and mediated at least 100‐fold higher levels of AAT secretion than the rAAV2 vector. Western blot analysis showed that this murine muscle‐secreted human AAT (hAAT) formed a complex with human neutrophil elastase in a dose‐dependent manner. An anti‐elastase activity assay showed that murine muscle‐secreted hAAT inhibited elastase with equal capacity as hAAT purified from plasma. These results provide strong support for the functionality of AAT in ongoing clinical studies of muscle‐directed AAT gene therapy. Copyright © 2006 John Wiley & Sons, Ltd.
Upper cervical cord area in early relapsing‐remitting multiple sclerosis: Cross‐sectional study of factors influencing cord size
Authors: Rashid Waqar , Davies Gerard R. , Chard Declan T. , Griffin Colette M. , Altmann Dan R. , Gordon Ros , Kapoor Raju , Thompson Alan J. , Miller David H.
Published: March 2006

Purpose

To determine whether the upper cervical cord area (UCCA) is influenced by disease effect in early relapsing‐remitting multiple sclerosis (MS), using statistical modeling to account for potential covariates.

Materials and Methods

A cohort of 39 patients were studied cross‐sectionally within three years of first symptom onset (median disease duration = 1.6 years) and compared with 26 healthy controls. The UCCA was measured from axial reconstructions of three‐dimensional T1‐weighted scans with automated detection of the edge of the cord. Statistical analysis adjusted for factors such as total intracranial volume (TICV) and gender. Clinical correlations, in particular those thought likely to be related to cord pathology, were also investigated.

Results

No significant disease effect was noted on UCCA (P = 0.685), although there was borderline evidence of a lower UCCA in patients with symptoms of bowel or bladder disturbance (P = 0.043). A strong association was noted between UCCA and TICV (r = 0.558; P ≤ 0.001), and there was a trend for females to have a smaller UCCA (P = 0.062). The latter finding appeared to reflect a gender‐related difference in TICV (P ≤ 0.001).

Conclusion

Atrophy of the upper cervical cord is not readily apparent in most patients early in the course of relapsing‐remitting MS. In evaluations of disease‐related changes in the UCCA in cross‐sectional studies, TICV and gender should be considered as potentially confounding covariates. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
fMRI studies of sensitivity and habituation effects within the auditory cortex at 1.5 T and 3 T
Authors: Rabe Kerstin , Michael Nikolaus , Kugel Harald , Heindel Walter , Pfleiderer Bettina
Published: March 2006

Purpose

To assess habituation effects in relation to field strength by fMRI at 1.5 vs. 3.0 T within the auditory cortex of healthy subjects.

Materials and Methods

fMRI experiments were performed on 19 healthy subjects at 1.5 T (N = 12) and 3 T (N = 12). The auditory cortex was stimulated binaurally by digitally generated pulsed (ν = 5 Hz) 800 Hz sine tones with three alternating on and off periods.

Results

The mean activation after stimulation (4.4% ± 1.2% (1.5 T) and 5.3% ± 2.3% (3 T)) and number of activated pixels (96.7 ± 49.8 (1.5 T) and 139.9 ± 101 (3 T)) were higher at 3 T compared to 1.5 T; however, that difference did not reach statistical significance. A characteristic signal decay with repeated stimuli was revealed at both 1.5 and 3 T, and the response to the second and third stimulation blocks was significantly lower compared to the first. The habituation pattern was the same, independently of field strength and age.

Conclusion

The mean activation and number of pixels were only modestly higher at 3 T, probably due to higher physiologic noise and higher local macroscopic susceptibility gradients within the temporal lobes at 3 T. Our data reveal that measured auditory habituation is independent of field strength, and data obtained at two different field strengths do not differ fundamentally in this context. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
On the transmission properties of left‐handed microstrip lines implemented by complementary split rings resonators
Authors: Gil M. , Bonache J. , Gil I. , García‐García J. , Martín F.
Published: March 2006

In this paper, the transmission properties of left‐handed microstrip lines implemented by etching complementary split rings resonators (CSRRs) and capacitive gaps in the ground plane and conductor strip, respectively, are investigated. To this end, we make use of the lumped element equivalent circuit model of the structure, from which an accurate analysis is carried out, and the influence of the main electrical parameters on the transmission properties is pointed out through electrical simulations. Aspects such as bandwidth and in‐band ripple control are discussed in detail. The influence of the geometrical parameters is also discussed and interpreted to the light of the equivalent circuit model. From the results obtained, there are inferred design guidelines that are suitable for the design of metamaterial transmission lines subjected to specifications. Copyright © 2006 John Wiley & Sons, Ltd.
Wave scattering by metamaterial wedges and interfaces
Authors: Sukhorukov Andrey A. , Shadrivov Ilya V. , Kivshar Yuri S.
Published: March 2006

We outline specific features of numerical simulations of metamaterial wedges and interfaces. We study the effect of different positioning of a grid in the Yee method, which is necessary to obtain consistent convergence in modelling of interfaces with metamaterials characterized by negative dielectric permittivity and negative magnetic permeability. We demonstrate however that, in the framework of the continuous‐medium approximation, wave scattering on the wedge may result in a resonant excitation of waves with infinitely large spatial frequencies, leading to non‐convergence of the simulation results that depend on the discretization step. Copyright © 2006 John Wiley & Sons, Ltd.
Wave properties of computational TLM models of metamaterials with negative refractive index
Authors: Hoefer Wolfgang J. R. , Du Huilian , So Poman P. M.
Published: March 2006

We derive and compare the wave properties of transmission‐line‐based negative refractive index metamaterials and their transmission line matrix (TLM) models. The TLM networks are computational replica of reactively loaded periodic structures that support backward waves and constitute artificial media with negative refractive index. After a brief review of the TLM algorithms for three types of nodes, namely the 2D Shunt Node, the 3D Expanded (or Distributed) Node, and the 3D Symmetrical Condensed Node, we formulate and solve the general dispersion equations in 2D and 3D metamaterials based on these nodes. We compare the results with the dispersion properties of both idealized homogeneous metamaterials and of L‐C loaded periodic transmission line structures that have the same cell size as their computational TLM counterparts. Copyright © 2006 John Wiley & Sons, Ltd.
Numerical studies of the interaction of time‐modulated multi‐gigabit sequences with metamaterial structures at millimeter‐wave frequencies
Authors: Franson Steven J. , Ziolkowski Richard W.
Published: March 2006

It is shown with time domain simulations using the finite integration technique (FIT) that a metamaterial that acts as an artificial magnetic conductor (AMC), i.e. a metamaterial which produces an in‐phase reflection, exhibits a time delay before its intended response can occur. A millimeter‐wave metamaterial AMC is obtained as a generalization of a successfully designed microwave frequency AMC block consisting of an array of capacitively loaded loops (CLLs). It is also shown that while this time delay does distort millimeter‐wave frequency signals composed of time‐modulated multi‐gigabit sequences, it does not have a detrimental impact on the overall system performance when these multi‐gigabit/s signals interact with this CLL‐based AMC. This time delay behaviour is demonstrated for several different but common communication‐based modulation schemes. The presence of peculiar spikes in the output waveforms is tied to the time domain behaviour of the currents on the CLLs in the metamaterial AMC. Copyright © 2006 John Wiley & Sons, Ltd.
Off‐normal incidence simulations of metamaterials using FDTD
Authors: Schurig D.
Published: March 2006

A method is described for applying FDTD simulation to electromagnetic metamaterial slabs with off‐normal incident plane wave radiation. Issues of incommensurate spatial periods and interpolation of irregularly spaced data are discussed. Validity of the method is tested on a dielectric slab with known analytical solutions and the method is used to analyse split ring resonators of current interest. Copyright © 2006 John Wiley & Sons, Ltd.
Impact of South Pacific circulation variability on east African rainfall
Authors: McHugh Maurice J.
Published: March 2006

While examining the atmospheric structure and dynamics through which the El Niño‐Southern Oscillation phenomenon is associated with east African rainfall, it was discovered that circulation variability in the subtropical South Pacific Ocean has a significant but seasonally varying influence on east African rainfall receipt on interannual timescales. Enhanced equatorial east African rainfall receipt associated with El Niño events is well known to occur during the long rains from October to December, but rainfall deficits during the same season are typical of La Niña events. South Pacific circulation variability is found to enhance rainfall receipt during the October to December period, but is associated with significant east African rainfall deficits during the March to May rainy period. It is demonstrated here that outbreaks of moist South Atlantic westerly flows that are often associated with anomalous rainfall receipt over east Africa are enhanced (weakened) during El Niño (La Niña) periods.

An empirical orthogonal function analysis is performed to extract the principal mode of sea level pressure variability in the tropical and subtropical South Pacific region. The time series associated with the principal mode of South Pacific circulation variability is correlated with circulation, atmospheric humidity, and outgoing longwave radiation fields during the short rains (October–December) and long rains (March–May). It is shown that South Pacific circulation variability is positively associated with east African rainfall receipt (r = 0.42, significant at the 99% confidence interval). Strengthened inflows of moist South Atlantic westerlies are associated with enhanced low‐level moisture convergence, decreased lower tropospheric stability, increased cloudiness, and increased precipitable water anomalies observed during OND. Reverse circulation and hydroclimatic anomalies observed during MAM are consistent with a negative association with east African rainfall during that season; r = −0.33, significant at the 98% confidence interval.

The temporal stability of these associations was tested during periods in which the principal interannual signal associated with El Niño was either very strong or very weak, and it was demonstrated that the correlations strengthened slightly (weakened markedly) during the period when the 5‐year signal was very strong (weak). Copyright © 2006 Royal Meteorological Society
Effects of a glycoconjugate from Lycium barbarum on body composition in growing mice
Authors: Zhang Min , Chen Haixia
Published: March 2006

This study investigated the effect of a kind of glycoconjugate from Lycium barbarum (GLB) on body composition in growing mice. The composition of GLB was determined; the body weight, food conversion rate, visceral index, fat index and mineral concentration in bone and muscle of mice were assessed. The health of the mice was evaluated in a swimming endurance test. The results showed that the contents of neutral sugar, uronic acid, protein and mineral in GLB were (mg g−1): 287.8, 494.5, 56.3 and 161, respectively. GLB fed at rates of 5 mg kg−1 d−1, 10 mg kg−1 d−1 and 20 mg kg−1 d−1 could reduce the growth rate of body weight, food conversion rate and the subcutaneous fat of mice. The swimming time of the growing mice was increased by GLB treatment. GLB induced an increase in thymus index and a decrease in spleen index. GLB had significant effects on the concentration of Zn and Fe in shank (p < 0.01) and could elevate the concentration of Ca and Zn in haunch muscle. The results showed that GLB was helpful to the development of mice. Copyright © 2006 Society of Chemical Industry
Ripening‐related changes in the cell walls of olive (Olea europaea L.) pulp of two consecutive harvests
Authors: Mafra Isabel , Barros António S , Nunes Cláudia , Vitorino Rui , Saraiva Jorge , Smith Andrew C , Waldron Keith W , Delgadillo Ivonne , Coimbra Manuel A
Published: March 2006

Olive fruits, harvested in two consecutive seasons at green, cherry and black stages, were used to study compositional changes in the cell walls during ripening. Ripening‐related changes in both harvests were characterised mainly by an increase in the solubilisation of pectic and hemicellulosic polysaccharides, an increase in the relative amount of arabinose in pectic polysaccharides and a decrease in the degree of methylesterification of pectic polysaccharides. Further to degrading processes, the data obtained suggest the synthesis of new polysaccharides. The analysis of olive cell wall phenolics showed mainly the presence of p‐coumaric acid, which increased in one harvest, whereas in the other the values did not differ. The samples of the second harvest, although presenting green, cherry and black colours, had less distinct ripening characteristics than those of the previous harvest. Different activity levels of polyphenol oxidase, polygalacturonase and pectin methylesterase might have contributed to the differences observed between the two harvests. The results showed the distinct extension of ripening‐related changes in the cell walls of the two harvests, indicating that the olive colour, although characteristic of the stage of ripening, cannot be strictly used for its evaluation and definition. Copyright © 2006 Society of Chemical Industry
Green Polymers from Geobacillus thermodenitrificans DSM465 – Candidates for Molecularly Imprinted Materials
Authors: Yoshikawa Masakazu , Kawamura Kensuke , Ejima Akinori , Aoki Takashi , Sakurai Shinichi , Hayashi Kyoko , Watanabe Kunihiko
Published: March 2006

Summary: Novel molecular recognition materials were prepared from water soluble proteins from thermophile G. thermodenitrificans DSM465 by an alternative molecular imprinting method. Water soluble proteins from G. thermodenitrificans DSM465 were converted into the molecularly imprinted materials by adopting 9‐EA as a print molecule. The molecularly imprinted protein membranes recognized As in preference to Gs. The adsorption isotherms led to the conclusion that molecular recognition sites toward As were constructed by the presence of 9‐EA during the membrane preparation process. The affinity constant between As and the molecular recognition site thus constructed was determined to be 1.75 × 105 mol−1 dm3. The results obtained in the present study suggest that water soluble proteins from G. thermodenitrificans DSM465 is one of environmentally‐friendly ‘green’ polymers to be converted into molecular recognition materials by applying an alternative molecular imprinting method.

Adsorption isotherms of As and Gs in the 9‐EA molecularly imprinted protein and the control non‐imprinted membranes. (a): As in the 9‐EA molecularly imprinted membrane. (b): Gs in the 9‐EA molecularly imprinted membrane. (c): As in the control non‐imprinted membrane. (d): Gs in the control non‐imprinted membrane.

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Adsorption isotherms of As and Gs in the 9‐EA molecularly imprinted protein and the control non‐imprinted membranes. (a): As in the 9‐EA molecularly imprinted membrane. (b): Gs in the 9‐EA molecularly imprinted membrane. (c): As in the control non‐imprinted membrane. (d): Gs in the control non‐imprinted membrane.
Tailored Synthesis and Fundamental Characterization of Organic‐Inorganic Hybrid Gels by Means of a Hydrosilylation Reaction
Authors: Naga Naofumi , Oda Emiko , Toyota Akinori , Horie Kazuyuki , Furukawa Hidemitsu
Published: March 2006

Summary: Organic‐inorganic hybrid gels have been synthesized from siloxane, 1,3,5,7‐tetramethylcyclotetrasiloxane (TMCTS), tetrakis(dimethylsilyloxy)silane (TDSS) or silsesquioxane, 1,3,5,7,9,11,13,15‐octakis(dimethylsilyloxy)pentacyclo‐[9,5,1,1,1,1]octasilsesquioxane (POSS), as crosslinking reagents and α,ω‐nonconjugated dienes, 1,5‐hexadiene (HD), 1,7‐octadiene (OD) and 1,9‐decadiene (DD), using a hydrosilylation reaction with a Pt catalyst. The network structures of the resulting gels were investigated by means of a novel scanning microscopic light scattering system. The structures of the crosslinking reagent and the length of the α,ω‐non‐conjugated dienes strongly affected the formation and network structures of the resulting gels. The critical gel concentration decreased when the molecular length of the non‐conjugated diene used was increased. The structures and SiH group numbers of the crosslinking reagents affected the critical gel concentration, and its values decreased in the following order: TDSS > TMCTS > POSS. The mesh size distribution in the network structure was quantitatively characterized using the light scattering system and almost presupposed sizes with quite narrow size distributions were attained in the gels from TMCTS‐HD, OD systems and TDSS‐OD systems. On the other hand, the gels derived from POSS or DD showed larger mesh sizes than expected.

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Melt Mixing of Polycarbonate with Multi‐Walled Carbon Nanotubes in Miniature Mixers
Authors: Lin Bin , Sundararaj Uttandaraman , Pötschke Petra
Published: March 2006

Summary: MWNT mixtures with PC were prepared in three different miniature mixers at 265 °C and 50 rpm for 6 min by the master batch dilution method. One mixer is a 4.5 cm3 DACA microcompounder (DACA Instruments) consisting of two conical co‐rotating screws with a bypass, allowing the material to circulate for defined periods. The other two miniature mixers are custom‐built in our lab: the 2.2 cm3 APAM and the 3 cm3 MBM. The volume resistivity for the nanocomposites obtained from the APAM and the MBM showed a similar trend for different MWNT compositions. The electrical percolation concentration for the nanocomposites prepared in the APAM and the MBM is between 0.50 wt.‐% (or 0.34 vol.‐%) and 0.75 wt.‐% (or 0.52 vol.‐%) MWNT, and it is between 0.75 wt.‐% (or 0.52 vol.‐%) and 1.00 wt.‐% (or 0.69 vol.‐%) for the DACA microcompounder. Rheological characterization indicates that the microstructure of PC/MWNT composites prepared from the miniature mixers changes at a concentration of 0.38 wt.‐% for the APAM and the MBM and 0.50 wt.‐% for the DACA where an interconnected network is formed. TEM micrographs show that there are some small aggregates in the nanocomposites obtained from the APAM, fewer aggregates from the MBM, and least from the DACA. AFM analysis suggests that the length of nanotubes is reduced from 0.57 µm to 0.38–0.42 µm after they were melt mixed in the three mixers.

Effect of MWNT content on volume resistivity of PC/MWNT obtained from different microcompounders.

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Effect of MWNT content on volume resistivity of PC/MWNT obtained from different microcompounders.
Indentation Fracture Mechanics for Toughness Assessment of PMMA/SiO2 Nanocomposites
Authors: Lach Ralf , Kim Gyeong‐Man , Michler Goerg Hannes , Grellmann Wolfgang , Albrecht Klaus
Published: March 2006

Summary: Based on the results from agglomerate‐free PMMA nanocomposites with 10 and 20 wt.‐% spherical SiO2 nanoparticles, it has been shown that indentation fracture mechanics is a straightforward, powerful, cost‐effective and time‐effective tool for analyzing the fracture resistance of novel polymer materials, such as brittle nanostructured polymer‐ceramic hybrids. In contrast to pure PMMA, the R‐curve effect, i.e., the enhancement in crack resistance as a function of crack size, was not observed in the nanocomposites investigated. Fracture toughness was found to depend on the SiO2 nanoparticle content, and the maximum value was observed at 10 wt.‐%. A significant reduction in fracture toughness occurred at 20 wt.‐% SiO2 nanoparticles, which is associated with a percolation of the bound layers (interfacial layers) around the SiO2 particles. From DSC data, the thickness of the interfacial polymer layer was estimated to be about 9 nm.

Hardness, elastic modulus and fracture toughness of PMMA/SiO2 composites as a function of nanoparticle fraction.

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Hardness, elastic modulus and fracture toughness of PMMA/SiO2 composites as a function of nanoparticle fraction.
Ethylene and Propylene Polymerization Using In Situ Supported Me2Si(Ind)2ZrCl2 Catalyst: Experimental and Theoretical Study
Authors: Franceschini Fernando C. , da R. Tavares Tatiana T. , dos Santos João H. Z. , Ferreira Maria L. , Soares João B. P.
Published: March 2006

Summary: Me2Si(Ind)2ZrCl2 was in situ immobilized onto SMAO and used for ethylene and propylene polymerization in the presence of TEA or TIBA as cocatalyst. The catalytic system Me2Si(Ind)2ZrCl2/SMAO exhibited different behavior depending on the amount and nature of the alkylaluminum employed and on the monomer type. The catalyst activity was nearly 0.4 kg polymer · g cat−1 · h−1 with both cocatalysts for propylene polymerization. Similar activities were observed for ethylene polymerization in the presence of TIBA. When ethylene was polymerized using TEA at an Al/Zr molar ratio of 250, the activity was 10 times higher. Polyethylenes made by in situ supported or homogeneous catalyst systems had practically the same melting point (Tm). On the other hand, poly(propylenes) made using in situ supported catalyst systems had a slightly lower Tm than poly(propylenes) made using homogeneous catalyst systems. The nature and amount of the alkylaluminum also influenced the molar mass. The poly(propylene) molar mass was higher when TIBA was the cocatalyst. The opposite behavior was observed for the polyethylenes. Concerning the alkylaluminum concentration, the molar mass of the polymers decreased as the amount of TEA increased. In the presence of TIBA, the polyethylene's molar mass was almost the same, independent of the alkylaluminum concentration, and the poly(propylene) molar mass increased with increasing amounts of cocatalyst. The deconvolution of the GPC curves showed 2 peaks for the homogeneous system and 3 peaks for the heterogeneous in situ supported system. The only exception was observed when TEA was used at an Al/Zr molar ratio of 500, where the best fit was obtained with 2 peaks. Based on the GPC deconvolution results and on the theoretical modeling, a proposal for the active site structure was made.

Molar mass distribution deconvolution of polyethylene prepared with the system Me2Si(Ind)2ZrCl2/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst.

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Molar mass distribution deconvolution of polyethylene prepared with the system Me2Si(Ind)2ZrCl2/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst.
Combining In‐Situ Organic Modification of Montmorillonite and the Latex Compounding Method to Prepare High‐Performance Rubber‐Montmorillonite Nanocomposites
Authors: Jia Qing‐Xiu , Wu You‐Ping , Xu Yan‐Li , Mao Hui‐Hui , Zhang Li‐Qun
Published: March 2006

Summary: To improve the interfacial interaction in MMT‐SBR nanocomposites, one type of UOAC was introduced to in‐situ modified MMT before latex compounding with SBR. The influence of the UOAC/MMT ratio on the structure and properties of MMT/SBR nanocomposites were carefully studied by XRD, TEM, and mechanical testing. It was found that through the in‐situ organic modification, a rubber‐intercalated structure of MMT was obtained in the nanocomposites, and the amount of rubber‐intercalated structure strongly depended on the UOAC/MMT ratio. The tensile strength of MMT‐SBR nanocomposites was enhanced dramatically from 4 to 18 MPa by in‐situ organic modification of MMT.

Stress‐strain diagram of SBR/clay nanocomposites.

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Stress‐strain diagram of SBR/clay nanocomposites.
Development and Characterization of Novel Biomimetic Composite Scaffolds Based on Bioglass‐Collagen‐Hyaluronic Acid‐Phosphatidylserine for Tissue Engineering Applications
Authors: Wang Yingjun , Yang Chunrong , Chen Xiaofeng , Zhao Naru
Published: March 2006

Summary: Biomimetic scaffolds are appealing products for the repair of bone defects using tissue engineering strategies. The present study prepared novel biomimetic composite scaffolds with similar composite to natural bone using bioactive glass, collagen, hyaluronic acid, and phosphatidylserine. The microstructure, swelling ratio, biodegradability, and biomineralization characteristic of the composite scaffolds with and without hyaluronic acid and phosphatidylserine were compared and analyzed by SEM/EDAX, XRD, and FTIR techniques and in vitro test, and the properties can be influenced by 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC)/N‐hydroxysuccinimide (NHS) crosslinking. The optimized properties of the crosslinked composite scaffolds observed in this study show the possibility of their use of bioactive and bioresorbable scaffolds in bone tissue engineering.

SEM micrographs of BG‐COL‐HYA‐PS composite scaffolds after immersion in SBF for 1 d.

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SEM micrographs of BG‐COL‐HYA‐PS composite scaffolds after immersion in SBF for 1 d.
Nanogel‐Templated Mineralization: Polymer‐Calcium Phosphate Hybrid Nanomaterials
Authors: Sugawara Ayae , Yamane Setsuko , Akiyoshi Kazunari
Published: March 2006

Summary: We report novel organic‐inorganic hybrid nanomaterials that consist of polymer hydrogel nanoparticles (nanogels) and calcium phosphate. Hybrid nanoparticles that measure ca. 40 nm are synthesized from a dilute solution of hydroxyapatite using nanogels as templates for calcium phosphate mineralization. These nanoparticles show a narrow size distribution and high colloidal stability. Nanogel‐adsorbed liposomes act as templates for hierarchical hybrid nanostructures. These nanohybrids can potentially be used as biocompatible drug carriers with controlled‐release properties.

TEM images of calcium phosphate nanoparticles formed in the presence of CHP nanogels (0.5 mg · mL−1) (left) and nanogel‐liposomes (CHP 0.05 mg · mL−1, DPPC 0.08 mg · mL−1)(right).

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TEM images of calcium phosphate nanoparticles formed in the presence of CHP nanogels (0.5 mg · mL−1) (left) and nanogel‐liposomes (CHP 0.05 mg · mL−1, DPPC 0.08 mg · mL−1)(right).
Preparation and Characterization of Polypyrrole/TiO2 Coaxial Nanocables
Authors: Lu Xiaofeng , Zhao Qidong , Liu Xincai , Wang Dejun , Zhang Wanjin , Wang Ce , Wei Yen
Published: March 2006

Summary: We demonstrate in this communication that large‐scale coaxial nanocables of polypyrrole (PPy)/TiO2 can be obtained via three steps: (1) synthesis of TiO2 nanofibers by electrospinning; (2) physical adsorption Fe3+ oxidant on the surface of TiO2 nanofibers; (3) followed by polymerization of pyrrole (from vapor) on the surface of TiO2 nanofibers. During the synthesis, the PPy formed on TiO2 nanofibers as a template and formed PPy/TiO2 coaxial nanocables. TEM image proved that PPy (20 nm thickness) covered the surface of TiO2 nanofibers. Fourier‐transform infrared (FTIR), X‐ray photoelectron spectra (XPS), and X‐ray diffraction patterns (XRD) characterized the chemical structure of the coaxial nanocables. Surface photovoltage spectroscopy (SPS) revealed the surface properties of the PPy/TiO2 coaxial nanocables.

TEM image of individual PPy/TiO2 coaxial nanocable.

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TEM image of individual PPy/TiO2 coaxial nanocable.
Cooperative Self‐Assembly of Nanoparticle Mixtures in Lamellar Diblock Copolymers: A Dissipative Particle Dynamics Study
Authors: Liu Dahuan , Zhong Chongli
Published: March 2006

Summary: Dissipative particle dynamics simulations are performed on the distribution of binary nanoparticle mixtures in lamellar diblock copolymers. The results show that the self‐assembly of nanoparticle mixtures in polymer matrix is a cooperative assembly that is affected by various factors, providing molecular‐level information for the rational design of new polymer nanocomposites with tailored properties.

The simulated polymer nanocomposite structure (the polymer matrix was omitted for clarity; P, gray; Q, black).

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The simulated polymer nanocomposite structure (the polymer matrix was omitted for clarity; P, gray; Q, black).
Quantification of atherosclerotic plaque components using in vivo MRI and supervised classifiers
Authors: Hofman J.M.A. , Branderhorst W.J. , ten Eikelder H.M.M. , Cappendijk V.C. , Heeneman S. , Kooi M.E. , Hilbers P.A.J. , ter Haar Romeny B.M.
Published: March 2006

In this work we aimed to study the possibility of using supervised classifiers to quantify the main components of carotid atherosclerotic plaque in vivo on the basis of multisequence MRI data. MRI data consisting of five MR weightings were obtained from 25 symptomatic subjects. Histological micrographs of endarterectomy specimens from the 25 carotids were used as a standard of reference for training and evaluation. The set of subjects was divided in a training set (12 subjects) and an evaluation set (13 subjects). Four different classifiers and two human MRI readers determined the percentages of calcified tissue, fibrous tissue, lipid core, and intraplaque hemorrhage on the subject level for all subjects in the evaluation set. Quantification of the relatively small amounts of calcium could not be done with statistical significance by either the classifiers or the MRI readers. For the other tissues a simple Bayesian classifier (Bayes) performed better than the other classifiers and the MRI readers. All classifiers performed better than the MRI readers in quantifying the sum of hemorrhage and lipid proportions. The MRI readers overestimated the hemorrhage proportions and tended to underestimate the lipid proportions. In conclusion, this pilot study demonstrates the benefits of algorithmic classifiers for quantifying plaque components. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Targeted magnetic resonance imaging of Scavidin‐receptor in human umbilical vein endothelial cells in vitro
Authors: Mäntylä Tuomas , Hakumäki Juhana M. , Huhtala Tuulia , Närvänen Ale , Ylä‐Herttuala Seppo
Published: March 2006

Current therapeutic approaches to treat cancer are often hampered by the lack of specificity of the drugs used for therapy. Scavidin, a novel fusion protein expressed on cell membranes, could be utilized for targeting of therapeutic molecules. Scavidin exploits the high binding affinity between avidin and biotin and is capable of mediating endocytosis of a bound ligand. In the current study we evaluated the efficiency of biotinylated ultrasmall superparamagnetic iron oxide (USPIO) particles in Scavidin‐expressing human umbilical vein endothelial cell (HUVEC) cultures in vitro as a novel receptor‐targeted magnetic resonance imaging contrast agent. Biotinylated USPIO (bUSPIO) were targeted to Scavidin adenovirus‐transduced HUVECs in vitro. Scavidin expressing cells were capable of binding and mediating endocytosis of the bUSPIO in vitro, which led to a significant decrease in T2 relaxation times, and a loss of signal intensity in comparison to controls. The findings were confirmed with Prussian blue staining for iron and detection of Scavidin by bound biotinylated horseradish peroxidase. Our data shows that biotinylated ligands target specifically to Scavidin‐expressing HUVEC in vitro. The utilization of Scavidin gene transfer ex vivo thus constitutes a platform for potential ligand delivery via cell therapy and time‐independent imaging of biologic processes. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Fast‐kzthree‐dimensional tailored radiofrequency pulse for reducedB1inhomogeneity
Authors: Saekho Suwit , Yip Chun‐yu , Noll Douglas C. , Boada Fernando E. , Stenger V. Andrew
Published: March 2006

This article presents a small‐flip‐angle, three‐dimensional tailored RF pulse that excites thin slices with an adjustable quadratic in‐plane spatial variation. The quadratic spatial variation helps to compensate for the loss in image uniformity using a volume coil at 3 T due to the wavelike properties of the RF field. The pulse is based on a novel “fast‐kz” design that uses a series of slice‐select subpulses alongkzand phase encoding “blips” alongkx–ky. The method is demonstrated by acquiring a series of 5‐mm‐thickT2‐weighted images of the human brain at 3 T using pulses 4.8 ms in length with a 45 ° flip angle. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Magnetic resonance imaging image intensity correction with extrapolation and adaptive smoothing
Authors: Cheng Hu , Huang Feng
Published: March 2006

A significant problem in magnetic resonance imaging (MRI) is the inhomogeneity of the image resulting from a number of factors that are hardware related. The obtained image can be treated as the true image multiplied by a signal modulator, which is usually smooth across the image. A class of MR image intensity correction methods extracts the slowly varying component from the image with low‐pass filtering or smoothing to approximate the signal modulator. This usually causes the edge enhancement artifact in the corrected image. A novel method of extrapolating the image in advance is proposed to reduce this effect significantly. Closest point algorithm is implemented to minimize the calculation time for extrapolation. To remove bright spots caused by nonuniform sensitivity profiles, a gradient‐weighted smoothing method is discussed in this work. The partial differential equations based model is applied for locally adaptive smoothing. The filtered gradient of the corrupted image is used as the weight for smoothing. Phantom and clinical data collected on various MRI systems are used for evaluation of our method. These experimental results show that the proposed method solves the edge enhancement and bright spots problem effectively and robustly. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Spin echo spectroscopic electron paramagnetic resonance imaging
Authors: Mailer Colin , Sundramoorthy Subramanian V. , Pelizzari Charles A. , Halpern Howard J.
Published: March 2006

The use of spin echoes to obtain spectroscopic EPR images (spectral–spatial images) at 250 MHz is described. The advantages of spin echoes—larger signals than the free induction decay, better phase characteristics for Fourier transformation, and decay shapes undistorted by instrumental dead time—are clearly shown. An advantage is gained from using a crossed loop resonator that isolates the 250‐W pump power by greater than 50 dB from the observer arm preamplifiers. The echo decay rates can be used to determine the oxygen content in solutions containing 1 mM trityl concentrations. Two‐ and three‐dimensional images of oxygen concentration are presented. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Proteome analysis of sorbitol fermentation specific protein in Vibrio cholerae by 2‐DE and MS
Authors: QingHua Zou , XiaoMei Yan , BoQing Li , Xun Zeng , Jun Zhou , JianZhong Zhang
Published: March 2006

Vibrio cholerae can be differentiated into epidemic and non‐epidemic strains by sorbitol fermentation speed, but little research has been done on its mechanisms. In this study, we investigated differential protein expression of the two strains in response to sorbitol metabolism. V. cholerae strains were cultured in media with and without sorbitol, respectively. Proteins were separated by 2‐DE, and those that showed different expression in the two media were identified by MALDI‐TOF MS. Fifteen proteins in epidemic strains and 11 proteins in non‐epidemic strains showed a different expression in sorbitol medium. Among them, 4 proteins were common to epidemic and non‐epidemic strains. Gene sequence analysis showed that some mutations occurred in these proteins between the two strains. Potential functions of these proteins included sugar uptake, amino acid uptake, electron transport, sulfate and thiosulfate transport.
Proteomic analysis of nasal cells from cystic fibrosis patients and non‐cystic fibrosis control individuals: Search for novel biomarkers of cystic fibrosis lung disease
Authors: Roxo‐Rosa Mónica , da Costa Gonçalo , Luider Theo M. , Scholte Bob J. , Coelho Ana V. , Amaral Margarida D. , Penque Deborah
Published: March 2006

Potential biological markers for cystic fibrosis (CF) lung disease were identified by comparative proteomics profiling of nasal cells from deletion of phenylalanine residue 508 (F508del)‐homozygous CF patients and non‐CF controls. From the non‐CF 2‐DE gels, 65 spots were identified by MS, and a reference 2‐DE map was thus established. The majority of those correspond to ubiquitously expressed proteins. Consistent with the epithelial origin of this tissue, some of the identified proteins are epithelial markers (e.g. cytokeratins, palate lung and nasal epithelium clone protein (PLUNC), and squamous cell carcinoma antigen 1). Comparison of this protein profile with the one similarly obtained for CF nasal cells revealed a set of differentially expressed proteins. These included proteins related to chronic inflammation and some others involved in oxidative stress injury. Alterations were also observed in the levels of cytoskeleton proteins, being probably implicated with cytoskeleton organization changes described to occur in CF‐airways. Lower levels were found for some mitochondrial proteins suggesting an altered mitochondrial metabolism in CF. Differential expression was also found for two more enzymes that have not been previously associated to CF. Further studies will clarify the involvement of such proteins in CF pathophysiology and whether they are targets for CF therapy.
Proteomics analysis revealed changes in rat bronchoalveolar lavage fluid proteins associated with oil mist exposure
Authors: Lee Yung‐Shan , Chen Pang‐Wei , Tsai Perng‐Jy , Su Shu‐Hui , Liao Pao‐Chi
Published: March 2006

Exposure to oil mist has been associated with a variety of acute and chronic respiratory effects. Using proteomics approaches to investigate exposure‐associated proteins may provide useful information to understand the mechanisms of associated respiratory effects. The aim of this study was to investigate changes in rat bronchoalveolar lavage fluid proteins associated with oil mist exposure using nano‐HPLC‐ESI‐MS/MS. The results revealed that 29 proteins exhibited significant changes after exposure. These proteins included surfactant‐associated proteins (SP‐A and SP‐D), inflammatory proteins (complement component 3, immunoglobulins, lysozyme, etc.), growth factors (e.g., transforming growth factor alpha (TGF‐α)), calcium‐binding proteins (calcyclin, calgranulin A, calreticulin, and calvasculin), and other proteins (e.g., cathepsin D, saposin, and intestinal trefoil factor). To further evaluate changes in protein levels, a simple quantitative strategy was developed in this study. A large decrease in protein levels of SP‐A and SP‐D (0.24‐ and 0.38‐fold, respectively) following exposure was observed. In contrast, protein levels of TGF‐α and calcium‐binding proteins were significantly increased (4.46‐ and 1.4–1.8‐fold, respectively). Due to the diverse functions of these proteins, the results might contribute to understand the mechanisms involved in lung disorders induced by oil mist exposure.
An evaluation of in vitro protein–protein interaction techniques: Assessing contaminating background proteins
Authors: Howell Jenika M. , Winstone Tara L. , Coorssen Jens R. , Turner Raymond J.
Published: March 2006

Determination of protein–protein interactions is an important component in assigning function and discerning the biological relevance of proteins within a broader cellular context. In vitro protein–protein interaction methodologies, including affinity chromatography, coimmunoprecipitation, and newer approaches such as protein chip arrays, hold much promise in the detection of protein interactions, particularly in well‐characterized organisms with sequenced genomes. However, each of these approaches attracts certain background proteins that can thwart detection and identification of true interactors. In addition, recombinant proteins expressed in Escherichia coli are also extensively used to assess protein–protein interactions, and background proteins in these isolates can thus contaminate interaction studies. Rigorous validation of a true interaction thus requires not only that an interaction be found by alternate techniques, but more importantly that researchers be aware of and control for matrix/support dependence. Here, we evaluate these methods for proteins interacting with DmsD (an E. coli redox enzyme maturation protein chaperone), in vitro, using E. coli subcellular fractions as prey sources. We compare and contrast the various in vitro interaction methods to identify some of the background proteins and protein profiles that are inherent to each of the methods in an E. coli system.
Surface enhanced laser desorption ionization spectrometry reveals biomarkers for drug treatment but not dose
Authors: Paweletz Cloud P. , Wiener Matthew C. , Sachs Jeffrey R. , Meurer Roger , Wu Margaret S. , Wong Kenney K. , Yates Nathan A. , Hendrickson Ronald C.
Published: March 2006

Here we describe the use of SELDI‐MS to detect dose‐dependent peptide changes in plasma from mice treated with vehicle or rosiglitazone at one of two doses (10 and 30 mg/kg). SELDI features differentiating spectra from the three conditions were found and used to train classifiers. Samples treated with vehicle could be reliably distinguished from samples treated with either dose, but samples treated with the different doses could not be reliably distinguished from one another. We conclude that while SELDI‐TOF mass spectra can be used to distinguish treated from untreated samples, the reproducibility and information content of SELDI‐TOF are currently not sufficient as a pharmacodynamic readout to distinguish between mice treated with 10 or 30 mg/kg of rosiglitazone. This raises more general questions about whether SELDI's sensitivity is sufficient for detecting dose‐dependent changes in plasma.